In plain terms

The claim being assessed: Increased intestinal epithelial permeability is a primary initiating cause of human autoimmune, inflammatory and metabolic disease through translocation of microbial products.

Where the evidence stands: Γ — Plausible mechanism. There is a believable biological story and partial support, but the causal step has not been demonstrated.

What this mechanism does: This makes the process worse or keeps it going, but something else starts it.

Strongest evidence for it: Scope-matched SC6 returns Γ. The preregistered human cross-disease initiator has partial experimental support but lacks a selective causal test in its claimed scope. SC2 reaches Ε for mapped experimental contributions; it cannot carry the human initiation claims. Weakest-link would return Β because the descriptive association subclaim is Β; primary-subclaim and scope-matched return Γ.

What decisive evidence would look like

In plain terms, researchers would change the proposed cause, confirm it changed as intended, and measure a meaningful health outcome while checking other explanations. The result should be able to support or count against the claim.

Relative explanatory fit: Alternative ranked ahead

What this review means for Leaky Gut Syndrome

Claim being assessed: Increased intestinal epithelial permeability is a primary initiating cause of human autoimmune, inflammatory and metabolic disease through translocation of microbial products.. This review asks whether the proposed factor causes the health outcome—not just whether the two appear together. For the wording assessed here, the evidence is rated Plausible mechanism (HSEF Γ; Moderate confidence). There is a believable biological story and partial support, but the causal step has not been demonstrated. That rating applies to this claim and scope; it does not mean the biological process is irrelevant in every setting.

Implications for health and treatment: This is an assessment of a causal explanation, not proof that a particular supplement, diet, test, or treatment improves health. A treatment claim needs studies that test the intervention in people and measure meaningful benefits and harms. These findings can help frame research and informed clinical questions, but they do not identify what is right for one person.

Limits for individual care: Evidence from cells, animals, associations, or a plausible mechanism may not predict what happens in people. The grade is limited to the exact claim, outcomes, and sources reviewed, and it is not a diagnosis or an individual forecast. Do not start, stop, or change care based on this page; discuss personal decisions with a qualified clinician.

Medical information notice: This review provides general health information, not medical advice. It cannot diagnose a condition or replace an individual discussion with a qualified clinician.

This assessment rests on 68 sources and 75 individually checked claims. 75 of those claims were verified against the original paper.

A low grade is not an accusation. It means the causal work has not been done yet, which is the ordinary state of most actively studied mechanisms in biology.

At a glance

Sub-claims assessed separately

ID	Sub-claim	Type	Level	Pivotal card
SC1	Intestinal epithelial permeability is elevated in the assessed human disease states.	existence	Β	—
SC2	Increased epithelial permeability permits microbial-product translocation that causally worsens systemic pathology.	mechanism	Ε	Card ↗
SC3	Increased epithelial permeability initiates human type 1 diabetes.	primacy	Γ	—
SC4	Increased epithelial permeability initiates human rheumatoid arthritis.	primacy	Γ	—
SC5	Increased epithelial permeability initiates human metabolic disease.	primacy	Γ	—
SC6	The same epithelial leak mechanism is the primary initiating explanation across these human disease classes.	generalization	Γ	Card ↗

Visual Evidence Cards · Pivotal Subclaims

Pivotal subclaim illustrations

Dark-theme simulated-micrograph renders and concise causal evidence summaries for the pivotal subclaims that govern this review's grade. Click any card to inspect the master 2400×2400 render.

Master 2400×2400 render ↗

Master 2400×2400 render ↗

Figures

Explanatory figures summarizing this review. They carry no evidential weight of their own; where a figure and the review differ, the review governs.

Full assessment

From here the review is written for a technical reader: caps and thresholds, competing models, the independence basis, and the citation ledger.

Sources: 68 primary reports; claims: 75; verified: 75; unverified: 0. Verification is bounded attribution. Access: 8 partial-body and 60 complete abstract/status examinations. Cutoff: 2026-10-05. No complete-paper audit or blinded calibration claimed. Adversarial review: Generated by Sol 6.1; adversarially reviewed by Claude Opus 5.5 (Anthropic) on 2026-10-06. 1 correction applied (see ADVERSARIAL REVIEW AND APPROVAL). Status: Approved as revised.

AT A GLANCE

Barrier dysfunction can causally amplify disease in defined experimental settings; a common epithelial-leak initiator of human autoimmune and metabolic disease is not established.

Deciding experiment: Randomize objectively defined islet-autoantibody-positive participants or ACPA-positive pre-RA participants to a gut-restricted, selective barrier intervention versus matched control before clinical disease. Preregister flux and translocation mediation, disease incidence, follow-up and effect size; validate the agent’s target and independent off-target profile.

Belief versus evidence: Scope-matched SC6 returns Γ. The preregistered human cross-disease initiator has partial experimental support but lacks a selective causal test in its claimed scope. SC2 reaches Ε for mapped experimental contributions; it cannot carry the human initiation claims. Weakest-link would return Β because the descriptive association subclaim is Β; primary-subclaim and scope-matched return Γ.

Best-supported rival: Permissive second-hit amplifier. PMID31419514 distinguishes the top amplifier model from a purely epithelial explanation: endothelial protection left epithelial translocation possible while limiting later disease. PMID19027740 provides the clearest second-hit versus standalone comparison. Neither is a human prevention trial.

COMPETING MECHANISTIC MODELS

Rank 1: Permissive second-hit amplifier (Ε). An antecedent immune, dietary or toxic process makes barrier changes disease-modifying. No spontaneous colitis despite CA-MLCK leak, followed by accelerated transfer colitis, and stage-specific MLCK deletion distinguish contribution from sufficiency [62–63]. Human incidence mediation remains untested; some barrier perturbations are pleiotropic.

Rank 2: Multi-tier epithelial/vascular/hepatic firewall (Ε). Systemic exposure depends on successive containment and clearance layers. Endothelial beta-catenin preservation limited NASH despite epithelial bacterial translocation, and Kupffer-cell clearance studies identify a separate hepatic barrier [51–52,66]. Layer-specific experiments are mouse-dominant, and the vascular GOF experiment was not blinded or randomized.

Rank 3: Reactive permeability and shared diet/immune causes (Ε). Disease, glycemia or inflammation can cause leak and establish feedback loops. Epithelial GLUT2 and glucose-control interventions demonstrate the hyperglycemia-to-leak arrow; arthritis disrupts gut resolving mediators [20,43]. Selective barrier rescue also helps in defined contexts, so reaction alone cannot explain the entire literature.

Rank 4: Assay artifact in zonulin epidemiology (Ε). Some serum associations measure an unvalidated protein proxy rather than epithelial flux. Recombinant-protein, immunocapture, genotype and Ussing-chamber checks undermine named commercial kits [32,61,67]. Sugar permeability and direct biopsy results persist independently of zonulin kits; artifact cannot explain all real barrier defects.

Rank 5: Permeability as primary systemic initiator (Γ). A common epithelial leak starts the assessed human diseases. Prediagnostic associations and mouse gut-joint rescue are the strongest supporting case [1,44,60,64]. Immune priming precedes rescue, leak alone can lack disease, metabolic endpoints can be null and vascular/liver mechanisms cannot substitute for epithelial initiation [25,27,52,62–63].

The tournament does not alter the nominal level. Compatible pathways and flexible alternatives are not automatically proved by explaining observations.

FULL REVIEW

Registered claim and scope

Increased intestinal epithelial permeability is a primary initiating cause of human autoimmune, inflammatory and metabolic disease through translocation of microbial products.

The index specifies scope-matched assessment. SC6 carries the broad cross-disease initiating claim; SC3–SC5 retain separate disease applications. Disease-specific therapeutic effects cannot carry general initiation.

Selection: public-interest rank 6 from the editorial ranking compiled 2026-09-23; categorical prior verdicts were visible. Private fresh review; earlier documents are preserved.

Evidence and causal interpretation

The registered proposition is substantially stronger than the observation that diseased intestines can leak. Sugar tests, epithelial resistance, macromolecular flux and serum proteins interrogate different processes. Older diabetes studies found greater recoveries of both probes without a changed ratio [7–8], while PEG400 work did not find an identifiable increase [11]. The correct inference is heterogeneous barrier physiology, not a uniformly positive diagnostic category.

Commercial zonulin is a major measurement fault line. Ajamian examined CUSABIO and Immundiagnostik using recombinant protein and immunocapture; Scheffler used HP genotype and protein validation; colonic biopsy work compared direct flux with serum measurements [32,61,67]. The tested kits did not reliably measure pre-HP2, and candidate captured proteins were not automatically the reactive analyte. These findings weaken kit-dependent causal narratives while leaving independent functional permeability evidence intact.

The most persuasive animal evidence narrows the target and includes a disease phenotype. Divertin changes MLCK1 localization rather than inhibiting every MLCK function [15]. TNFR2 and long-MLCK deletion delay transfer colitis, but apoptosis bypasses that pathway later and DSS colitis remains possible [63]. This maps a real causal contribution and its stage boundary. Conversely, CA-MLCK overexpression produces leak and immune activation without spontaneous colitis [62]. Together these results fit a second-hit amplifier better than a universally sufficient initiator.

Tajik is a useful mechanistic bridge, but its human and mouse arms answer different questions. Human pre-RA participants were ACPA-positive without joint swelling and followed for transition; serum zonulin used CUSABIO. Mouse barrier rescue began after collagen/adjuvant immunization. Larazotide reduced barrier loss, arthritis and gut-to-joint cell traffic in mice, not a randomized human prevention arm [1]. These Methods/Results details were extracted through Consensus indexed full text and independently checked in the original article. The experiment supports a modifiable checkpoint after immune priming.

The newer HIF1a-RIPK3 gut-joint work adds epithelial genetic resolution and rescue [10]. Its human ileal samples were described in the earlier program, so the human component is not independent replication. ICI-colitis MLCK1 work and alcohol-associated cathepsin-B experiments further narrow defined pathways [14,16], although only their complete abstracts were accessible here. These are positive mechanism tests within specified antecedent exposures; none establishes the broad human initiating claim.

For T1D, Bosi detected increased permeability in people already carrying islet autoimmunity before clinical diagnosis [44]. This is a comparison across stages, not randomization or proof that leak preceded the first autoimmune event. Sapone includes stored prediagnostic serum observations [64], whose historical assay must be assessed on its own identity rather than automatically equated with newer kits. Sorini supplies a striking animal link, but DSS colitis is coupled to a transgenic diabetogenic repertoire [6]. Infection, pectin, nuclease and fingolimod studies are supportive yet mechanistically broader [12,40–41,45].

Metabolic endotoxemia is biologically active, but infusion does not test epithelial origin. Chronic LPS administration and CD14 work [21,50] differ from endogenous barrier perturbation; LPS source and duration can produce opposing glucose effects [22,53]. Hyperglycemia itself drives leak through epithelial glucose handling [20], and impaired glucose tolerance can arise without detected barrier loss [27]. These results make a feedback loop credible while weakening a common first-cause claim.

Human functional evidence remains nuanced. Genser found similar fasting permeability between obese and control groups but a stronger lipid-challenge effect ex vivo [68]. Randomized carrageenan increased permeability with null primary and co-primary insulin-sensitivity outcomes; BMI interactions were ancillary [25]. The probiotic/fibre trial’s ITT fat endpoint was null while selected PP and post-hoc analyses looked favorable and energy intake changed [30]. Neither result proves permeability mediation of metabolic disease.

The systemic barrier is not only epithelial. Endothelial beta-catenin gain-of-function preserved vascular containment and limited NASH while epithelial translocation remained possible [52]. Its mouse experiments were not randomized or blinded, which limits confidence. Liver phagocytic clearance constitutes another firewall [66]. A circulating microbial signal therefore cannot identify epithelial leakage without assessing vascular passage and hepatic handling [51–52,66].

Larazotide demonstrates why clinical benefit and mediation must remain separate. In gluten-challenge trials, permeability comparisons were null or too variable, while lower-dose symptoms or antibody outcomes improved [55,59]. A persistent-symptom celiac trial improved the primary symptom endpoint at the lowest dose [58]. These are relevant human interventions, but treatment of established gluten-driven disease is not prevention of the assessed human diseases, and null permeability outcomes cannot be silently replaced by symptom success.

Consensus sharpened the search by connecting barrier-selective rescue, assay identity, competing layers and prevention gaps. Its “primary study” label for a 2024 mechanistic review was rejected, and its description of Bosi as prospective was narrowed after reading the original abstract. Its meter and provider screening counts are neither independent evidence nor our examination count. The resulting Γ attaches to the common human initiating claim; the real phenomenon and the Ε experimental contribution remain explicitly supported.

HYPOTHESIS STATE EVALUATION FRAMEWORK (HSEF v5.3)

Subclaim matrix and aggregation

Preregistered aggregation: scope-matched. Scope-matched SC6 returns Γ. The preregistered human cross-disease initiator has partial experimental support but lacks a selective causal test in its claimed scope. SC2 reaches Ε for mapped experimental contributions; it cannot carry the human initiation claims. Weakest-link would return Β because the descriptive association subclaim is Β; primary-subclaim and scope-matched return Γ. Sensitivities: weakest-link Β; primary-subclaim Γ; scope-matched Γ.

Decisive-perturbation inventory and causal tally

[1] Larazotide reduced CIA severity and cell trafficking after collagen/adjuvant immunization; pre-RA serum signals predicted transition. The human arm was observational and used Cusabio; immunization preceded leak. This establishes a checkpoint in induced arthritis, not human disease initiation.

[10] IEC Hif1a deletion exacerbated CIA and RIPK3-directed rescue suppressed necroptosis and arthritis. Collagen induction remains upstream; HIF1a has effects beyond permeability. Human ileal biopsy material overlaps the earlier gut-joint study.

[13] Claudin-2 deletion improved septic mouse survival alongside reduced pore permeability and immune activation. Sepsis was induced; developmental deletion and altered microbial virulence require caution about isolated barrier mediation and other diseases.

[14] MLCK deletion preserved junctions and ameliorated checkpoint-inhibitor colitis; an interaction blocker retained antitumour efficacy. Abstract-only access; ICI exposure and wild microbiota define context, and systemic human disease initiation was not tested.

[15] Divertin blocked MLCK1 recruitment, delayed transfer-colitis symptoms and improved established experimental disease. Transfer colitis and IL10 deficiency supply upstream immune abnormalities; human prevention was not tested.

[16] Myeloid cathepsin B deletion or gut-restricted inhibition preserved occludin and attenuated ethanol steatohepatitis. Abstract-only access; alcohol is an antecedent and myeloid protease effects are broader than a pure epithelial perturbation.

[23] TRPV6 loss or inhibition blocked ethanol-induced calcium influx, barrier disruption and inflammatory response. Alcohol remains upstream and TRPV6 expression is not exclusively epithelial; inference is restricted to alcohol exposure.

[24] GLP2 antagonism abolished much of prebiotic barrier benefit and GLP2 agonism improved permeability and inflammation. ob/ob biology and GLP2 trophic effects bound inference; it does not demonstrate human metabolic disease initiation.

[63] TNFR2 or long-MLCK deletion delayed transfer colitis, but apoptosis and DSS injury bypassed protection. This maps a stage-specific pathway and its failure boundary, not a universal epithelial or systemic initiator.

Tally: 9 discriminating contrasts. Null and negative contrasts are discriminators, not positive threshold crossings. Reports and replications are not independent causal lines. Only positive selective in vivo contributions carry the decisive flag; negative contrasts, overexpression, forced microbial/LPS exposure and surrogate-only experiments do not. The count is reports, not independent lines.

Cap audit, precedence and Β/Γ/Δ boundary

"A perturbation crosses a threshold within the system it was actually run in. A universal cap governs the inference from that system to the hypothesis’s claimed scope." SC2 receives animal-context credit. Forced LPS infusion, DSS colitis and transgenic overexpression cannot establish endogenous human epithelial initiation; the convergent set is assessed without re-capping its observational leg. Rubric06 lifespan language is not used as an obesity endpoint requirement; functional metabolic outcomes remain distinct from permeability biomarkers.

Gamma hard-rule audit: Human initiating scope is not established by the selective animal perturbations; the complete convergent set is assessed without a blanket in vitro cap. Biomarker-only improvement without organismal benefit does not count as clinical disease causation.

SC1 cap: “Pure association evidence — however large, however replicated — cannot exceed Β.” Functional measures support abnormalities in some cohorts, with normal ratios or fasting permeability elsewhere; kit signals alone do not establish permeability [7–11,32,68].

SC1 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: no. Functional measures support abnormalities in some cohorts, with normal ratios or fasting permeability elsewhere; kit signals alone do not establish permeability [7–11,32,68].

SC2 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: yes. Selective MLCK intervention and stage-specific deletion, plus defined gut-joint and alcohol pathways, establish bounded causal contributions. DSS, forced LPS and vascular-only manipulations are not counted as isolated epithelial causation [1,13–16,23–24,63].

SC3 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: no. Preclinical human associations and animal perturbations support plausibility, but no examined barrier-selective human prevention result establishes initiation. Bosi compares disease stages after autoimmunity is already present [44,64].

SC4 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: no. Tajik combines human risk associations with post-immunization mouse rescue; the commercial serum assay has specificity limitations and there is no human prevention randomization [1,10,43,46,61,67].

SC5 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: no. Mouse endotoxin biology is causal but does not isolate human epithelial initiation. Human carrageenan permeability changed with null primary metabolic endpoints, and obesity can occur without measured barrier failure [20–22,25,27,30,50,68].

SC6 field-valid definition: “ - Gnotobiotic or transfer experiment showing phenotype movement, at minimum - Even without defined-consortium precision or robust rescue, a transfer paradigm in vivo is the minimum that crosses this threshold

Per Cap precedence above, a gnotobiotic or forced-transfer experiment crosses Δ for the recipient-animal subclaim it was actually run in, while universal cap 5 (seeding or forced-transfer paradigms cap at Γ) still blocks the inference from that result to endogenous human biology — score the two scopes separately rather than choosing between the rules.” Positive full-scope result: no. The animal and ex vivo mechanisms make cross-disease leak biologically plausible; distinct upstream triggers, barriers and null endpoints prevent a shared initiating claim in humans [1,20,25,27,51–52,63,66].

Upward threshold ladder

SC1 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

SC2 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: yes.

SC2 Ε: “Requires context-specific causal effect with defined limits. A transferable phenotype exists, but microbial identity or generalizability remains incomplete.” Satisfied: yes.

SC2 Ζ: “Requires: - Defined consortium or strain-level causal evidence - Rescue logic - Replication across at least two relevant models or cohorts” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

SC3 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

SC4 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

SC5 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

SC6 Δ: “Requires a transfer paradigm or causal perturbation in vivo.” Satisfied: no. A barrier-selective intervention with validated flux/translocation, prespecified incident disease or functional endpoint, and mediator specificity in the stated scope; replicate with orthogonal genetic or pharmacologic instruments.

Upper ladder: Human prevention and valid natural experiments could reach Η–Ω without demanding an unethical disease induction trial. Examined treatments do not isolate epithelial leak with incident human disease. HP genotype helps assess assay identity, not barrier causation. MR on an invalid serum proxy would not solve the problem.

Independence: No convergence sufficient for human initiation is claimed. Human ileal biopsies in PMID38503474 reuse material described in PMID32332732 and are not independent human replication; corresponding mouse manipulations are separate. Sources with overlapping author groups are not automatically independent lines.

Mouse barrier-selective intervention [15, 63]: Narrows barrier physiology beyond epidemiological confounding.

Human functional permeability [44, 60, 68]: Avoids relying entirely on commercial zonulin, but leaves latent disease and shared causes.

Assay identity audit [61, 67, 32]: Excludes interpreting every kit signal as validated epithelial permeability.

Falsification and pitfalls

Leak is not sufficient for spontaneous disease. CA-MLCK mice lacked spontaneous colitis despite leak [62]. Additional downgrade: False.

Disease can bypass the nominated pathway. MLCK loss delayed transfer disease but not late apoptosis or DSS colitis; metabolic impairment occurred without detected leak [27,63]. Additional downgrade: False.

Biomarker and phenotype dissociate. Carrageenan changed permeability with null metabolic primary endpoints; larazotide symptoms changed with null permeability comparisons [25,55,59]. Additional downgrade: False.

Mistaking presence for primacy. Serum markers in established disease [29,33,46].

Temporal order inferred rather than demonstrated. Bosi stage comparison precedes clinical diagnosis but not already-present islet autoimmunity [44].

Therapeutic effect misread as mechanistic proof. Fingolimod, irisin, antioxidants and probiotics have alternative mediators [3–4,12,30,38].

Scope fitted to the result. No subgroup defined as susceptible solely because it became ill; genotype, baseline autoantibody status and exposure are antecedent facts.

Adversarial steelman: above, then below

The case for Δ is that several gut-directed interventions prevent model disease, human leak can precede diagnosis, and local larazotide is closer to barrier specificity than broad immunosuppression [1,15,44,60]. If an incident human endpoint plus verified epithelial mediator were present, the full-scope boundary could be crossed.

The case for Β is that human initiation remains associational and commercial zonulin evidence is unreliable [32,61,67]. It is strongest if animal and organoid work are excluded entirely from plausibility rather than treated as partial system support.

Reject Δ for the full human initiating claim because model rescue does not carry that scope and the human clinical/permeability dissociations are material. Reject Β as the scope-matched level because experimentally grounded mechanisms supply more than association. Preserve Β as the preregistered weakest-link sensitivity.

Final score, causal direction and M/S/D

Scope-matched SC6 returns Γ. The preregistered human cross-disease initiator has partial experimental support but lacks a selective causal test in its claimed scope. SC2 reaches Ε for mapped experimental contributions; it cannot carry the human initiation claims. Weakest-link would return Β because the descriptive association subclaim is Β; primary-subclaim and scope-matched return Γ.

The assessed causal contribution is amplification in defined models: barrier rescue changes trajectory after collagen immunization, immune-cell transfer, alcohol or other triggers. Initiation, rate limitation and necessity across the human scope are not jointly demonstrated. Hyperglycemia and arthritis also produce leak, so causal direction is bidirectional and context-dependent rather than exclusively downstream.

Momentum: Mechanistic only. 2026 MLCK1 ICI-colitis and cathepsin-B alcohol-liver experiments attempt selective mechanism narrowing [14,16]. The examined human carrageenan, larazotide and synbiotic studies do not test prevention of T1D or RA [25,42,55,58–59]. No pending prevention trial is claimed without a verified registration.

Stability: Stable. No verified pending barrier-selective human disease-incidence result was identified. A positive independently replicated prevention result would raise the human subclaim; an assay-corrected null prospective study would narrow it, but these are proposed tests, not named pending results.

Divergence: Contested; no single implied-level arithmetic. These dimensions do not change level or confidence.

PROPOSED DECISIVE EXPERIMENTS

Randomize objectively defined islet-autoantibody-positive participants or ACPA-positive pre-RA participants to a gut-restricted, selective barrier intervention versus matched control before clinical disease. Preregister flux and translocation mediation, disease incidence, follow-up and effect size; validate the agent’s target and independent off-target profile.

Readout: Incident clinical T1D or synovitis alongside validated size-selective permeability, microbial-product identity and longitudinal immune activation. Controls: Equal diet and systemic immune therapy, blinded incidence adjudication, target engagement, an orthogonal barrier assay and prespecified baseline genotype/autoantibody strata. Supporting: Target-specific restoration precedes lower incident disease and mediation survives orthogonal perturbation and exposure controls. Falsifying: Verified restoration with adequate power leaves incident disease unchanged, or benefit is fully accounted for by systemic immunomodulation.

RESEARCH TIMELINE

KNOWLEDGE GAPS

Barrier-selective prevention with incident T1D or RA, rather than symptoms or serum proxies. Consensus proposed this gap; the examined human studies do not resolve it.

Determine the actual antigens detected by each serum kit and prospectively validate them against size-selective epithelial flux.

Measure epithelial passage, vascular escape and hepatic clearance together, so increased circulating material is assigned to the correct layer.

Prespecify exposure duration, LPS molecular structure, glycemic status and diet to test where endotoxemia is metabolically harmful or neutral.

Replicate the gut-joint intervention with independent human material and blinded randomized animal designs; shared biopsies should not count twice.

METHODS AND CONSENSUS CONTRIBUTION

Consensus was used through the signed-in browser for discovery, counterevidence, research-gap and timeline suggestions, and checks of specific indexed full-text passages. Extracted Methods/Results details were reconciled with original-paper passages where available. Provider screening counts, citation counts and meters were not used as primary counts or HSEF scores. This source log records access depth; it does not claim complete-paper or supplement review. The monthly API allowance was conserved: zero Consensus API calls in this batch.

REVIEWER NOTES

68 primary reports have source-specific appraisals. Eight original bodies were examined in selected passages, with exact receipts; other sources were examined at complete abstract/status depth. No supplement or complete-paper audit is claimed. One linked erratum is attached to its parent and must be considered for any affected numeric claim. This is a bounded critical review with reproducible searches, not an exhaustive systematic review.

Search leads, reviews, protocols and correction notices do not pad the primary count. Downloaded XML does not earn examination credit. Linked notices remain attached; unexamined correction details limit inference. This is a coordinator source/claim consistency assessment, not independent blinded calibration.

ADVERSARIAL REVIEW AND APPROVAL

Authoring model: Sol 6.1. Adversarial reviewer: Claude Opus 5.5 (Anthropic). Date: 2026-10-06.

Scope of checks. All 68 reference PMIDs re-verified against PubMed records (title, first author, journal, year, DOI, status flags): 68/68 resolve to the stated work; no retractions or expressions of concern; the only year differences are print-issue versus e-pub year. 16 load-bearing claims spot-checked against PubMed abstracts and the local examination records, including Tajik's human-plus-mouse design and larazotide arthritis result, the CA-MLCK and long-MLCK/TNFR2 colitis experiments, the Bosi staged permeability study, the gut-vascular-barrier and liver-firewall experiments, the hyperglycaemia/GLUT2 work, the Kless null, the randomised carrageenan trial, the three larazotide coeliac trials, the B420/polydextrose ITT-versus-per-protocol result, and the zonulin assay-validation studies. Scoring logic re-derived from framework/hsef-hypothesis-review-v5/SKILL.md and references/hsef-framework.md: cap order and cap precedence, the index-prescribed scope-matched aggregation, the Β/Γ/Δ boundary, the reported rule sensitivities, and the competing-model levels.

Rejected findings (checked, no change). (a) Overall Γ by scope-matched aggregation — SC6 is the subclaim whose scope matches the registered cross-disease initiating claim, and the weakest-link and primary-subclaim sensitivities are reported as the framework requires. (b) SC2 at Ε rather than Ζ — the review's own Ζ test (defined-mechanism causal evidence plus rescue logic plus replication across two relevant systems) is argued and failed; the stage-specific MLCK and gut-joint experiments share a model and an upstream trigger. (c) The "assay artifact" rival at Ε — the claim graded there is a measurement claim established by biochemical and ex vivo validation, not a biological-causality claim subject to universal cap 1; this is a defensible judgement call. (d) Momentum "Mechanistic only", Stability "Stable", Divergence "Contested" — all are canonical values with the artifacts the framework requires. (e) The Bosi characterisation (staged comparison in people already islet-autoantibody-positive, not a prospective pre-autoimmunity cohort) and the larazotide characterisation (null or uninterpretable permeability outcomes with symptom benefit at the lowest dose) — both verified against the source abstracts. (f) Citation years differing by one from the PubMed e-pub year (PMIDs 19027740, 20012858 and others) — print/issue-year convention.

Residual limitations. Access remains bounded: 8 partial-body and 60 abstract/status examinations, with no complete-paper or supplement audit; several mechanism papers (MLCK1 in checkpoint-inhibitor colitis, cathepsin B in alcohol-associated liver injury) were examined at abstract depth only. This pass checked citation integrity, attribution and framework conformance; it is not independent blinded peer review.

Approval: Following adversarial review and the corrections listed above, the revised document is approved. — Claude Opus 5.5 (Anthropic), 2026-10-06.

REFERENCES

1. Tajik N, Frech M, Schulz O et al. Targeting zonulin and intestinal epithelial barrier function to prevent onset of arthritis. Nature communications. 2020. PMID 32332732. DOI: 10.1038/s41467-020-15831-7. Access: full_text_partial. Study: GUT-JOINT-TAJIK-2020.

2. Sato K, Takahashi N, Kato T et al. Aggravation of collagen-induced arthritis by orally administered Porphyromonas gingivalis through modulation of the gut microbiota and gut immune system. Scientific reports. 2017. PMID 28761156. DOI: 10.1038/s41598-017-07196-7. Access: abstract_metadata. Study: PMID28761156.

3. Sun Y, Wang Y, Lin Z et al. Irisin delays the onset of type 1 diabetes in NOD mice by enhancing intestinal barrier. International journal of biological macromolecules. 2024. PMID 38493812. DOI: 10.1016/j.ijbiomac.2024.130857. Access: abstract_metadata. Study: PMID38493812.

4. Wang H, Wang G, Banerjee N et al. Aberrant Gut Microbiome Contributes to Intestinal Oxidative Stress, Barrier Dysfunction, Inflammation and Systemic Autoimmune Responses in MRL/lpr Mice. Frontiers in immunology. 2021. PMID 33912174. DOI: 10.3389/fimmu.2021.651191. Access: abstract_metadata. Study: PMID33912174.

5. Hardin JA, Donegan L, Woodman RC et al. Mucosal inflammation in a genetic model of spontaneous type I diabetes mellitus. Canadian journal of physiology and pharmacology. 2002. PMID 12489925. DOI: 10.1139/y02-138. Access: abstract_metadata. Study: PMID12489925.

6. Sorini C, Cosorich I, Lo Conte M et al. Loss of gut barrier integrity triggers activation of islet-reactive T cells and autoimmune diabetes. Proceedings of the National Academy of Sciences of the United States of America. 2019. PMID 31182588. DOI: 10.1073/pnas.1814558116. Access: full_text_partial. Study: PMID31182588.

7. Carratù R, Secondulfo M, de Magistris L et al. Altered intestinal permeability to mannitol in diabetes mellitus type I. Journal of pediatric gastroenterology and nutrition. 1999. PMID 10067726. DOI: 10.1097/00005176-199903000-00010. Access: abstract_metadata. Study: PMID10067726.

8. Mooradian AD, Morley JE, Levine AS et al. Abnormal intestinal permeability to sugars in diabetes mellitus. Diabetologia. 1986. PMID 3519337. DOI: 10.1007/BF00454879. Access: abstract_metadata. Study: PMID3519337.

9. Mielants H, Goemaere S, De Vos M et al. Intestinal mucosal permeability in inflammatory rheumatic diseases. I. Role of antiinflammatory drugs. The Journal of rheumatology. 1991. PMID 1906938. Access: abstract_metadata. Study: PMID1906938.

10. Lyu P, Wen J, Zhang W et al. Expression of HIF1α in intestinal epithelium restricts arthritis inflammation by inhibiting RIPK3-induced cell death machinery. Annals of the rheumatic diseases. 2024. PMID 38503474. DOI: 10.1136/ard-2023-224491. Access: full_text_partial. Study: GUT-JOINT-HIF2024-shared-human-biopsies.

11. Jenkins RT, Goodacre RL, Rooney PJ et al. Studies of intestinal permeability in inflammatory diseases using polyethylene glycol 400. Clinical biochemistry. 1986. PMID 3769195. DOI: 10.1016/s0009-9120(86)80045-5. Access: abstract_metadata. Study: PMID3769195.

12. Jia LL, Zhang M, Liu H et al. Early-life fingolimod treatment improves intestinal homeostasis and pancreatic immune tolerance in non-obese diabetic mice. Acta pharmacologica Sinica. 2021. PMID 33473182. DOI: 10.1038/s41401-020-00590-4. Access: abstract_metadata. Study: PMID33473182.

13. Oami T, Abtahi S, Shimazui T et al. Claudin-2 upregulation enhances intestinal permeability, immune activation, dysbiosis, and mortality in sepsis. Proceedings of the National Academy of Sciences of the United States of America. 2024. PMID 38412124. DOI: 10.1073/pnas.2217877121. Access: abstract_metadata. Study: PMID38412124.

14. Xiong L, Huang J, Dong Y et al. Targeting MLCK1 uncouples immune checkpoint inhibitor-induced colitis from antitumour immunity. Gut. 2026. PMID 41494803. DOI: 10.1136/gutjnl-2025-337780. Access: abstract_metadata. Study: PMID41494803.

15. Graham WV, He W, Marchiando AM et al. Intracellular MLCK1 diversion reverses barrier loss to restore mucosal homeostasis. Nature medicine. 2019. PMID 30936544. DOI: 10.1038/s41591-019-0393-7. Access: full_text_partial. Study: PMID30936544.

16. Fondevila MF, Kreimeyer H, Hsu CL et al. Macrophage-derived cathepsin B disrupts intestinal tight junctions through occludin degradation and promotes alcohol-associated liver disease. Journal of hepatology. 2026. PMID 41654223. DOI: 10.1016/j.jhep.2026.01.013. Access: abstract_metadata. Study: PMID41654223.

17. Nwako JG, Patel SD, Roach TJ et al. Enteroendocrine cells regulate intestinal barrier permeability. American journal of physiology. Cell physiology. 2025. PMID 40095977. DOI: 10.1152/ajpcell.01077.2024. Access: abstract_metadata. Study: PMID40095977.

18. Zuo L, Kuo WT, Cao F et al. Tacrolimus-binding protein FKBP8 directs myosin light chain kinase-dependent barrier regulation and is a potential therapeutic target in Crohn's disease. Gut. 2023. PMID 35537812. DOI: 10.1136/gutjnl-2021-326534. Access: abstract_metadata. Study: PMID35537812.

19. Everard A, Belzer C, Geurts L et al. Cross-talk between Akkermansia muciniphila and intestinal epithelium controls diet-induced obesity. Proceedings of the National Academy of Sciences of the United States of America. 2013. PMID 23671105. DOI: 10.1073/pnas.1219451110. Access: abstract_metadata. Study: PMID23671105.

20. Thaiss CA, Levy M, Grosheva I et al. Hyperglycemia drives intestinal barrier dysfunction and risk for enteric infection. Science (New York, N.Y.). 2018. PMID 29519916. DOI: 10.1126/science.aar3318. Access: abstract_metadata. Study: PMID29519916.

21. Cani PD, Bibiloni R, Knauf C et al. Changes in gut microbiota control metabolic endotoxemia-induced inflammation in high-fat diet-induced obesity and diabetes in mice. Diabetes. 2008. PMID 18305141. DOI: 10.2337/db07-1403. Access: abstract_metadata. Study: PMID18305141.

22. Anhê FF, Barra NG, Cavallari JF et al. Metabolic endotoxemia is dictated by the type of lipopolysaccharide. Cell reports. 2021. PMID 34525353. DOI: 10.1016/j.celrep.2021.109691. Access: abstract_metadata. Study: PMID34525353.

23. Meena AS, Shukla PK, Bell B et al. TRPV6 channel mediates alcohol-induced gut barrier dysfunction and systemic response. Cell reports. 2022. PMID 35705057. DOI: 10.1016/j.celrep.2022.110937. Access: abstract_metadata. Study: PMID35705057.

24. Cani PD, Possemiers S, Van de Wiele T et al. Changes in gut microbiota control inflammation in obese mice through a mechanism involving GLP-2-driven improvement of gut permeability. Gut. 2009. PMID 19240062. DOI: 10.1136/gut.2008.165886. Access: abstract_metadata. Study: PMID19240062.

25. Wagner R, Buettner J, Heni M et al. Carrageenan and insulin resistance in humans: a randomised double-blind cross-over trial. BMC medicine. 2024. PMID 39593091. DOI: 10.1186/s12916-024-03771-8. Access: full_text_partial. Study: PMID39593091.

26. Rungratanawanich W, Lin Y, Wang X et al. ALDH2 deficiency increases susceptibility to binge alcohol-induced gut leakiness, endotoxemia, and acute liver injury in mice through the gut-liver axis. Redox biology. 2023. PMID 36528936. DOI: 10.1016/j.redox.2022.102577. Access: abstract_metadata. Study: PMID36528936.

27. Kless C, Müller VM, Schüppel VL et al. Diet-induced obesity causes metabolic impairment independent of alterations in gut barrier integrity. Molecular nutrition & food research. 2015. PMID 25676872. DOI: 10.1002/mnfr.201400840. Access: abstract_metadata. Study: PMID25676872.

28. Floyd JL, Prasad R, Dupont MD et al. Intestinal neutrophil extracellular traps promote gut barrier damage exacerbating endotoxaemia, systemic inflammation and progression of diabetic retinopathy in type 2 diabetes. Diabetologia. 2025. PMID 39875729. DOI: 10.1007/s00125-024-06349-4. Access: abstract_metadata. Study: PMID39875729.

29. Carpes LS, Nicoletto BB, Canani LH et al. Could serum zonulin be an intestinal permeability marker in diabetes kidney disease? PloS one. 2021. PMID 34170951. DOI: 10.1371/journal.pone.0253501. Access: abstract_metadata. Study: PMID34170951.

30. Stenman LK, Lehtinen MJ, Meland N et al. Probiotic With or Without Fiber Controls Body Fat Mass, Associated With Serum Zonulin, in Overweight and Obese Adults-Randomized Controlled Trial. EBioMedicine. 2016. PMID 27810310. DOI: 10.1016/j.ebiom.2016.10.036. Access: abstract_metadata. Study: PMID27810310.

31. Yonker LM, Gilboa T, Ogata AF et al. Multisystem inflammatory syndrome in children is driven by zonulin-dependent loss of gut mucosal barrier. The Journal of clinical investigation. 2021. PMID 34032635. DOI: 10.1172/JCI149633. Access: abstract_metadata. Study: PMID34032635.

32. Meira de-Faria F, Bednarska O, Ström M et al. Colonic paracellular permeability and circulating zonulin-related proteins. Scandinavian journal of gastroenterology. 2021. PMID 33535002. DOI: 10.1080/00365521.2021.1879247. Access: abstract_metadata. Study: PMID33535002.

33. Pacifico L, Bonci E, Marandola L et al. Increased circulating zonulin in children with biopsy-proven nonalcoholic fatty liver disease. World journal of gastroenterology. 2014. PMID 25493023. DOI: 10.3748/wjg.v20.i45.17107. Access: abstract_metadata. Study: PMID25493023.

34. Koutoukidis DA, Yen S, Gomez Castro P et al. Changes in intestinal permeability and gut microbiota following diet-induced weight loss in patients with metabolic dysfunction-associated steatohepatitis and liver fibrosis. Gut microbes. 2024. PMID 39340210. DOI: 10.1080/19490976.2024.2392864. Access: abstract_metadata. Study: PMID39340210.

35. Wang W, Uzzau S, Goldblum SE et al. Human zonulin, a potential modulator of intestinal tight junctions. Journal of cell science. 2000. PMID 11082037. DOI: 10.1242/jcs.113.24.4435. Access: abstract_metadata. Study: PMID11082037.

36. Haidmayer A, Bosch P, Lackner A et al. Effects of Probiotic Strains on Disease Activity and Enteric Permeability in Psoriatic Arthritis-A Pilot Open-Label Study. Nutrients. 2020. PMID 32764250. DOI: 10.3390/nu12082337. Access: abstract_metadata. Study: PMID32764250.

37. Miranda-Ribera A, Ennamorati M, Serena G et al. Exploiting the Zonulin Mouse Model to Establish the Role of Primary Impaired Gut Barrier Function on Microbiota Composition and Immune Profiles. Frontiers in immunology. 2019. PMID 31608059. DOI: 10.3389/fimmu.2019.02233. Access: abstract_metadata. Study: ZONULIN-TG-2019.

38. Zhou Q, Verne ML, Fields JZ et al. Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome. Gut. 2019. PMID 30108163. DOI: 10.1136/gutjnl-2017-315136. Access: abstract_metadata. Study: PMID30108163.

39. Hond ED, Peeters M, Hiele M et al. Effect of glutamine on the intestinal permeability changes induced by indomethacin in humans. Alimentary pharmacology & therapeutics. 1999. PMID 10233193. DOI: 10.1046/j.1365-2036.1999.00523.x. Access: abstract_metadata. Study: PMID10233193.

40. Wu C, Pan LL, Luo Y et al. Low Methoxyl Pectin Protects against Autoimmune Diabetes and Associated Caecal Dysfunction. Molecular nutrition & food research. 2019. PMID 31423661. DOI: 10.1002/mnfr.201900307. Access: abstract_metadata. Study: PMID31423661.

41. Liang Y, Wang X, He D et al. Ameliorating gut microenvironment through staphylococcal nuclease-mediated intestinal NETs degradation for prevention of type 1 diabetes in NOD mice. Life sciences. 2019. PMID 30776371. DOI: 10.1016/j.lfs.2019.02.034. Access: abstract_metadata. Study: PMID30776371.

42. Stougaard EB, Tougaard NH, Sivalingam S et al. Effects of probiotics and fibers on markers of nephropathy, inflammation, intestinal barrier dysfunction and endothelial dysfunction in individuals with type 1 diabetes and albuminuria. The ProFOS Study. Journal of diabetes and its complications. 2024. PMID 39471704. DOI: 10.1016/j.jdiacomp.2024.108892. Access: abstract_metadata. Study: PMID39471704.

43. Flak MB, Colas RA, Muñoz-Atienza E et al. Inflammatory arthritis disrupts gut resolution mechanisms, promoting barrier breakdown by Porphyromonas gingivalis. JCI insight. 2019. PMID 31292292. DOI: 10.1172/jci.insight.125191. Access: abstract_metadata. Study: PMID31292292.

44. Bosi E, Molteni L, Radaelli MG et al. Increased intestinal permeability precedes clinical onset of type 1 diabetes. Diabetologia. 2006. PMID 17028899. DOI: 10.1007/s00125-006-0465-3. Access: abstract_metadata. Study: PMID17028899.

45. Lee AS, Gibson DL, Zhang Y et al. Gut barrier disruption by an enteric bacterial pathogen accelerates insulitis in NOD mice. Diabetologia. 2010. PMID 20012858. DOI: 10.1007/s00125-009-1626-y. Access: abstract_metadata. Study: PMID20012858.

46. Heidt C, Kämmerer U, Fobker M et al. Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis. Nutrients. 2023. PMID 37242269. DOI: 10.3390/nu15102386. Access: abstract_metadata. Study: PMID37242269.

47. Stadlbauer V, Horvath A, Komarova I et al. A single alcohol binge impacts on neutrophil function without changes in gut barrier function and gut microbiome composition in healthy volunteers. PloS one. 2019. PMID 30707717. DOI: 10.1371/journal.pone.0211703. Access: abstract_metadata. Study: PMID30707717.

48. Li C, Gao M, Zhang W et al. Zonulin Regulates Intestinal Permeability and Facilitates Enteric Bacteria Permeation in Coronary Artery Disease. Scientific reports. 2016. PMID 27353603. DOI: 10.1038/srep29142. Access: abstract_metadata. Study: PMID27353603.

49. Barmeyer C, Erko I, Awad K et al. Epithelial barrier dysfunction in lymphocytic colitis through cytokine-dependent internalization of claudin-5 and -8. Journal of gastroenterology. 2017. PMID 28138755. DOI: 10.1007/s00535-017-1309-2. Access: abstract_metadata. Study: PMID28138755.

50. Cani PD, Amar J, Iglesias MA et al. Metabolic endotoxemia initiates obesity and insulin resistance. Diabetes. 2007. PMID 17456850. DOI: 10.2337/db06-1491. Access: abstract_metadata. Study: PMID17456850.

51. Spadoni I, Zagato E, Bertocchi A et al. A gut-vascular barrier controls the systemic dissemination of bacteria. Science (New York, N.Y.). 2015. PMID 26564856. DOI: 10.1126/science.aad0135. Access: abstract_metadata. Study: PMID26564856.

52. Mouries J, Brescia P, Silvestri A et al. Microbiota-driven gut vascular barrier disruption is a prerequisite for non-alcoholic steatohepatitis development. Journal of hepatology. 2019. PMID 31419514. DOI: 10.1016/j.jhep.2019.08.005. Access: full_text_partial. Study: PMID31419514.

53. Stevens JR, McMillan RP, Resendes JT et al. Acute low-dose endotoxin treatment results in improved whole-body glucose homeostasis in mice. Metabolism: clinical and experimental. 2017. PMID 28183447. DOI: 10.1016/j.metabol.2016.12.008. Access: abstract_metadata. Study: PMID28183447.

54. Slifer ZM, Hernandez L, Pridgen TA et al. Larazotide acetate induces recovery of ischemia-injured porcine jejunum via repair of tight junctions. PloS one. 2021. PMID 33886649. DOI: 10.1371/journal.pone.0250165. Access: abstract_metadata. Study: PMID33886649.

55. Leffler DA, Kelly CP, Abdallah HZ et al. A randomized, double-blind study of larazotide acetate to prevent the activation of celiac disease during gluten challenge. The American journal of gastroenterology. 2012. PMID 22825365. DOI: 10.1038/ajg.2012.211. Access: abstract_metadata. Study: PMID22825365.

56. Gopalakrishnan S, Durai M, Kitchens K et al. Larazotide acetate regulates epithelial tight junctions in vitro and in vivo. Peptides. 2012. PMID 22401908. DOI: 10.1016/j.peptides.2012.02.015. Access: abstract_metadata. Study: PMID22401908.

57. Gopalakrishnan S, Tripathi A, Tamiz AP et al. Larazotide acetate promotes tight junction assembly in epithelial cells. Peptides. 2012. PMID 22401910. DOI: 10.1016/j.peptides.2012.02.016. Access: abstract_metadata. Study: PMID22401910.

58. Leffler DA, Kelly CP, Green PH et al. Larazotide acetate for persistent symptoms of celiac disease despite a gluten-free diet: a randomized controlled trial. Gastroenterology. 2015. PMID 25683116. DOI: 10.1053/j.gastro.2015.02.008. Access: abstract_metadata. Study: PMID25683116.

59. Kelly CP, Green PH, Murray JA et al. Larazotide acetate in patients with coeliac disease undergoing a gluten challenge: a randomised placebo-controlled study. Alimentary pharmacology & therapeutics. 2013. PMID 23163616. DOI: 10.1111/apt.12147. Access: abstract_metadata. Study: PMID23163616.

60. Turpin W, Lee SH, Raygoza Garay JA et al. Increased Intestinal Permeability Is Associated With Later Development of Crohn's Disease. Gastroenterology. 2020. PMID 32791132. DOI: 10.1053/j.gastro.2020.08.005. Access: abstract_metadata. Study: PMID32791132.

61. Ajamian M, Steer D, Rosella G et al. Serum zonulin as a marker of intestinal mucosal barrier function: May not be what it seems. PloS one. 2019. PMID 30640940. DOI: 10.1371/journal.pone.0210728. Access: full_text_partial. Study: PMID30640940.

62. Su L, Shen L, Clayburgh DR et al. Targeted epithelial tight junction dysfunction causes immune activation and contributes to development of experimental colitis. Gastroenterology. 2009. PMID 19027740. DOI: 10.1053/j.gastro.2008.10.081. Access: abstract_metadata. Study: PMID19027740.

63. Su L, Nalle SC, Shen L et al. TNFR2 activates MLCK-dependent tight junction dysregulation to cause apoptosis-mediated barrier loss and experimental colitis. Gastroenterology. 2013. PMID 23619146. DOI: 10.1053/j.gastro.2013.04.011. Access: abstract_metadata. Study: PMID23619146.

64. Sapone A, de Magistris L, Pietzak M et al. Zonulin upregulation is associated with increased gut permeability in subjects with type 1 diabetes and their relatives. Diabetes. 2006. PMID 16644703. DOI: 10.2337/db05-1593. Access: abstract_metadata. Study: PMID16644703.

65. Sturgeon C, Lan J, Fasano A et al. Zonulin transgenic mice show altered gut permeability and increased morbidity/mortality in the DSS colitis model. Annals of the New York Academy of Sciences. 2017. PMID 28423466. DOI: 10.1111/nyas.13343. Access: abstract_metadata. Study: ZONULIN-TG-2017.

66. Balmer ML, Slack E, de Gottardi A et al. The liver may act as a firewall mediating mutualism between the host and its gut commensal microbiota. Science translational medicine. 2014. PMID 24848256. DOI: 10.1126/scitranslmed.3008618. Access: abstract_metadata. Study: PMID24848256.

67. Scheffler L, Crane A, Heyne H et al. Widely Used Commercial ELISA Does Not Detect Precursor of Haptoglobin2, but Recognizes Properdin as a Potential Second Member of the Zonulin Family. Frontiers in endocrinology. 2018. PMID 29459849. DOI: 10.3389/fendo.2018.00022. Access: full_text_partial. Study: PMID29459849.

68. Genser L, Aguanno D, Soula HA et al. Increased jejunal permeability in human obesity is revealed by a lipid challenge and is linked to inflammation and type 2 diabetes. The Journal of pathology. 2018. PMID 29984492. DOI: 10.1002/path.5134. Access: abstract_metadata. Study: PMID29984492.

Source-specific evidence cards

[1] Targeting zonulin and intestinal epithelial barrier function to prevent onset of arthritis.

Shows: Larazotide reduced CIA severity and cell trafficking after collagen/adjuvant immunization; pre-RA serum signals predicted transition.

Does not show: The human arm was observational and used Cusabio; immunization preceded leak. This establishes a checkpoint in induced arthritis, not human disease initiation.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph1, 1:Results:paragraph3, 1:Results:paragraph5, 1:Results:paragraph6, 1:Results:paragraph7, 1:Results:paragraph8, 1:Results:paragraph9, 1:Results:paragraph10, 1:Results:paragraph12, 1:Results:paragraph13, 1:Results:paragraph14, 1:Results:paragraph15, 2:Discussion:paragraph1, 2:Discussion:paragraph3, 3:Methods:paragraph0, 3:Methods:paragraph1, 3:Methods:paragraph8, 3:Methods:paragraph24. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2, SC4, SC6.

[2] Aggravation of collagen-induced arthritis by orally administered Porphyromonas gingivalis through modulation of the gut microbiota and gut immune system.

Shows: Oral P. gingivalis aggravated induced arthritis and altered gut immunity and microbiota.

Does not show: Multiple bacterial functions and prior collagen induction prevent assigning the effect specifically to barrier leak.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC4.

[3] Irisin delays the onset of type 1 diabetes in NOD mice by enhancing intestinal barrier.

Shows: Irisin treatment delayed NOD diabetes with improved barrier and islet inflammation.

Does not show: Exercise-hormone effects on energy expenditure and immunity confound barrier-specific mediation; human samples were from new-onset disease.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[4] Aberrant Gut Microbiome Contributes to Intestinal Oxidative Stress, Barrier Dysfunction, Inflammation and Systemic Autoimmune Responses in MRL/lpr Mice.

Shows: N-acetylcysteine attenuated systemic autoimmunity alongside microbial and barrier changes in MRL/lpr mice.

Does not show: Antioxidant pleiotropy and lupus genotype prevent a selective test of spontaneous human barrier initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[5] Mucosal inflammation in a genetic model of spontaneous type I diabetes mellitus.

Shows: Diabetes-prone BB rats showed intestinal inflammatory activity before and after diabetes.

Does not show: Genotype, inflammation and barrier changes were not separated by a selective manipulation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC3.

[6] Loss of gut barrier integrity triggers activation of islet-reactive T cells and autoimmune diabetes.

Shows: DSS colitis activated islet-reactive T cells and diabetes in BDC2.5 NOD mice; antibiotics prevented activation.

Does not show: DSS injury and a transgenic diabetogenic T-cell repertoire are combined perturbations, not isolated endogenous epithelial leak in humans.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 0:Results:paragraph2, 0:Results:paragraph3, 0:Results:paragraph4, 0:Results:paragraph5. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[7] Altered intestinal permeability to mannitol in diabetes mellitus type I.

Shows: Mannitol recovery increased in established type 1 diabetes while the cellobiose/mannitol ratio remained normal.

Does not show: Probe absorption is not interchangeable with a selective macromolecular leak; disease duration can confound direction.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC3.

[8] Abnormal intestinal permeability to sugars in diabetes mellitus.

Shows: Both sugar recoveries increased in diabetic patients without a group difference in their ratio.

Does not show: Raw recovery and differential permeability diverged; established disease cannot establish initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC3.

[9] Intestinal mucosal permeability in inflammatory rheumatic diseases. I. Role of antiinflammatory drugs.

Shows: Antiinflammatory medication altered permeability in control subjects, complicating arthritis comparisons.

Does not show: NSAID and steroid exposure are potential common causes of measured leak and disease treatment status.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC4.

[10] Expression of HIF1α in intestinal epithelium restricts arthritis inflammation by inhibiting RIPK3-induced cell death machinery.

Shows: IEC Hif1a deletion exacerbated CIA and RIPK3-directed rescue suppressed necroptosis and arthritis.

Does not show: Collagen induction remains upstream; HIF1a has effects beyond permeability. Human ileal biopsy material overlaps the earlier gut-joint study.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Methods:paragraph0, 1:Methods:paragraph1, 1:Methods:paragraph2. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC4.

[11] Studies of intestinal permeability in inflammatory diseases using polyethylene glycol 400.

Shows: PEG400 urinary recovery did not identify increased permeability in active inflammatory disease.

Does not show: Different probe size and absorption kinetics limit direct comparison with lactulose or FITC-dextran results.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC4.

[12] Early-life fingolimod treatment improves intestinal homeostasis and pancreatic immune tolerance in non-obese diabetic mice.

Shows: Early fingolimod improved gut and pancreatic immune tolerance and reduced NOD diabetes incidence.

Does not show: Systemic lymphocyte trafficking effects make barrier restoration an unisolated mediator.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[13] Claudin-2 upregulation enhances intestinal permeability, immune activation, dysbiosis, and mortality in sepsis.

Shows: Claudin-2 deletion improved septic mouse survival alongside reduced pore permeability and immune activation.

Does not show: Sepsis was induced; developmental deletion and altered microbial virulence require caution about isolated barrier mediation and other diseases.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[14] Targeting MLCK1 uncouples immune checkpoint inhibitor-induced colitis from antitumour immunity.

Shows: MLCK deletion preserved junctions and ameliorated checkpoint-inhibitor colitis; an interaction blocker retained antitumour efficacy.

Does not show: Abstract-only access; ICI exposure and wild microbiota define context, and systemic human disease initiation was not tested.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[15] Intracellular MLCK1 diversion reverses barrier loss to restore mucosal homeostasis.

Shows: Divertin blocked MLCK1 recruitment, delayed transfer-colitis symptoms and improved established experimental disease.

Does not show: Transfer colitis and IL10 deficiency supply upstream immune abnormalities; human prevention was not tested.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:RESULTS:paragraph2, 1:RESULTS:paragraph16, 1:RESULTS:paragraph18, 1:RESULTS:paragraph19. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[16] Macrophage-derived cathepsin B disrupts intestinal tight junctions through occludin degradation and promotes alcohol-associated liver disease.

Shows: Myeloid cathepsin B deletion or gut-restricted inhibition preserved occludin and attenuated ethanol steatohepatitis.

Does not show: Abstract-only access; alcohol is an antecedent and myeloid protease effects are broader than a pure epithelial perturbation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[17] Enteroendocrine cells regulate intestinal barrier permeability.

Shows: Enteroendocrine-cell loss impaired enteroid barrier function and PYY or somatostatin supplementation rescued it.

Does not show: Organoid barrier physiology is not organismal systemic disease or proof of human initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. UpdateOf: PMID40161779. Subclaims: SC2.

[18] Tacrolimus-binding protein FKBP8 directs myosin light chain kinase-dependent barrier regulation and is a potential therapeutic target in Crohn's disease.

Shows: FKBP8 disruption blocked TNF-dependent MLCK recruitment and barrier loss; interactions were elevated in Crohn biopsies.

Does not show: Tacrolimus is immunosuppressive; barrier rescue without a disease-incidence endpoint cannot establish systemic primacy.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[19] Cross-talk between Akkermansia muciniphila and intestinal epithelium controls diet-induced obesity.

Shows: Viable A. muciniphila reduced high-fat-diet fat gain, endotoxemia and insulin resistance while restoring mucus.

Does not show: Microbial treatment changes several metabolites and endocrine signals; barrier mediation and human causality were not isolated.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[20] Hyperglycemia drives intestinal barrier dysfunction and risk for enteric infection.

Shows: Hyperglycemia drove barrier disruption; epithelial GLUT2 deletion or glucose control restored containment.

Does not show: This is causal evidence for the reverse arrow and infection susceptibility, not barrier-first metabolic disease.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5, SC6.

[21] Changes in gut microbiota control metabolic endotoxemia-induced inflammation in high-fat diet-induced obesity and diabetes in mice.

Shows: Antibiotics and CD14 deletion reduced HFD-associated endotoxemia and metabolic abnormalities.

Does not show: Antibiotics and immune receptor deletion do not isolate epithelial permeability as the initiating mediator.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[22] Metabolic endotoxemia is dictated by the type of lipopolysaccharide.

Shows: Equal endotoxin-unit doses from different bacterial LPS sources produced opposing glycemic effects.

Does not show: LPS structure and TLR4 activity matter; total measured endotoxin is not a uniform pathogenic exposure.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[23] TRPV6 channel mediates alcohol-induced gut barrier dysfunction and systemic response.

Shows: TRPV6 loss or inhibition blocked ethanol-induced calcium influx, barrier disruption and inflammatory response.

Does not show: Alcohol remains upstream and TRPV6 expression is not exclusively epithelial; inference is restricted to alcohol exposure.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[24] Changes in gut microbiota control inflammation in obese mice through a mechanism involving GLP-2-driven improvement of gut permeability.

Shows: GLP2 antagonism abolished much of prebiotic barrier benefit and GLP2 agonism improved permeability and inflammation.

Does not show: ob/ob biology and GLP2 trophic effects bound inference; it does not demonstrate human metabolic disease initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[25] Carrageenan and insulin resistance in humans: a randomised double-blind cross-over trial.

Shows: Randomized carrageenan exposure increased lactulose/mannitol permeability but primary and co-primary insulin-sensitivity endpoints were null.

Does not show: BMI interactions were ancillary, not proof of the nominal primary endpoint or mediation by permeability.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Methods:paragraph0, 1:Methods:paragraph2, 1:Methods:paragraph5, 1:Methods:paragraph6, 1:Methods:paragraph14, 2:Results:paragraph0, 2:Results:paragraph1, 2:Results:paragraph2, 2:Results:paragraph6. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC5.

[26] ALDH2 deficiency increases susceptibility to binge alcohol-induced gut leakiness, endotoxemia, and acute liver injury in mice through the gut-liver axis.

Shows: ALDH2 loss increased ethanol leak and liver injury, with complementary cell inhibition and activation.

Does not show: Acetaldehyde metabolism, cell injury and liver toxicity are pleiotropic; this is alcohol-context susceptibility.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[27] Diet-induced obesity causes metabolic impairment independent of alterations in gut barrier integrity.

Shows: Diet-induced impaired glucose tolerance occurred across tested mouse backgrounds without detectable barrier loss.

Does not show: Assay sensitivity and diets limit universal absence claims, but leak was not necessary in these tested metabolic models.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC5, SC6.

[28] Intestinal neutrophil extracellular traps promote gut barrier damage exacerbating endotoxaemia, systemic inflammation and progression of diabetic retinopathy in type 2 diabetes.

Shows: PAD4 inhibition reduced intestinal NETs, endotoxemia and progression of diabetic retinopathy.

Does not show: Late diabetes and direct retinal or marrow effects prevent interpreting benefit as barrier-first diabetes initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[29] Could serum zonulin be an intestinal permeability marker in diabetes kidney disease?

Shows: Serum zonulin-kit signals differed across diabetic kidney disease stages and predicted renal outcomes.

Does not show: Renal clearance, adiposity and assay identity confound interpreting a serum signal as intestinal permeability.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC5.

[30] Probiotic With or Without Fiber Controls Body Fat Mass, Associated With Serum Zonulin, in Overweight and Obese Adults-Randomized Controlled Trial.

Shows: The probiotic/fibre trial had no significant body-fat difference in ITT; PP and post-hoc analyses were more favorable.

Does not show: Attrition, compliance restriction, reduced energy intake and zonulin association do not establish barrier-mediated fat loss.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[31] Multisystem inflammatory syndrome in children is driven by zonulin-dependent loss of gut mucosal barrier.

Shows: MIS-C biospecimens showed antigenemia and barrier-associated signals; one larazotide-treated patient improved.

Does not show: An uncontrolled treated case and postinfectious disease cannot prove mediation, efficacy or a universal epithelial initiator.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[32] Colonic paracellular permeability and circulating zonulin-related proteins.

Shows: Circulating zonulin did not mirror colonic permeability or pre-HP2; pre-HP2 non-producers still had kit signals.

Does not show: Local biopsy relationships differ from plasma; the result invalidates a proxy in the tested setting, not all barrier biology.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC6.

[33] Increased circulating zonulin in children with biopsy-proven nonalcoholic fatty liver disease.

Shows: A serum zonulin signal tracked steatosis but not histological inflammation, ballooning or fibrosis in obese children.

Does not show: Cross-sectional case-control design and commercial-marker uncertainty prevent initiation or liver-injury causality.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC5.

[34] Changes in intestinal permeability and gut microbiota following diet-induced weight loss in patients with metabolic dysfunction-associated steatohepatitis and liver fibrosis.

Shows: Diet-induced weight loss improved MASH markers with falling serum zonulin; microbial changes were not sustained.

Does not show: No control arm or barrier-selective perturbation; caloric restriction and weight loss are plausible upstream causes.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC5.

[35] Human zonulin, a potential modulator of intestinal tight junctions.

Shows: An immunologically identified zonulin preparation reversibly disrupted primate epithelial junctions ex vivo.

Does not show: Early protein identity and purified exposure do not demonstrate necessity in endogenous human disease.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[36] Effects of Probiotic Strains on Disease Activity and Enteric Permeability in Psoriatic Arthritis-A Pilot Open-Label Study.

Shows: A small open-label PsA probiotic study reported transient improvement in symptoms and permeability markers.

Does not show: No placebo control, different arthritis disease and fecal-marker identity limit inference to rheumatoid arthritis.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC4.

[37] Exploiting the Zonulin Mouse Model to Establish the Role of Primary Impaired Gut Barrier Function on Microbiota Composition and Immune Profiles.

Shows: Zonulin-transgenic mice showed immune skew and dysbiosis; wildtype microbiota did not normalize immune profiles.

Does not show: Overexpression and latent inflammation need an environmental hit and do not establish spontaneous cross-disease causality.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[38] Randomised placebo-controlled trial of dietary glutamine supplements for postinfectious irritable bowel syndrome.

Shows: Glutamine improved symptoms and permeability in postinfectious IBS-D selected for high permeability.

Does not show: Glutamine has multiple actions; the population and symptom endpoint do not establish autoimmune or metabolic disease prevention.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[39] Effect of glutamine on the intestinal permeability changes induced by indomethacin in humans.

Shows: Glutamine effects on indomethacin permeability depended on dose timing; pretreatment alone failed.

Does not show: Drug-induced barrier damage is a different initiating exposure and there was no systemic disease endpoint.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC2.

[40] Low Methoxyl Pectin Protects against Autoimmune Diabetes and Associated Caecal Dysfunction.

Shows: Low-methoxyl pectin delayed NOD diabetes with caecal, SCFA and immune changes.

Does not show: Dietary fibre changes microbial and immune pathways simultaneously; permeability is not an isolated mediator.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[41] Ameliorating gut microenvironment through staphylococcal nuclease-mediated intestinal NETs degradation for prevention of type 1 diabetes in NOD mice.

Shows: Engineered L. lactis delivering nuclease reduced NET markers and improved NOD glycemia and inflammation.

Does not show: Microbial engineering, immune effects and commercial leak markers permit several alternative mediators.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[42] Effects of probiotics and fibers on markers of nephropathy, inflammation, intestinal barrier dysfunction and endothelial dysfunction in individuals with type 1 diabetes and albuminuria. The ProFOS Study.

Shows: ProFOS synbiotics did not improve albuminuria or measured secondary outcomes in type 1 diabetes.

Does not show: Established kidney disease and nonspecific microbiota treatment do not falsify a selective barrier prevention hypothesis.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[43] Inflammatory arthritis disrupts gut resolution mechanisms, promoting barrier breakdown by Porphyromonas gingivalis.

Shows: Arthritis disrupted intestinal resolving mediators; resolvin restored barrier and reduced joint inflammation after P. gingivalis.

Does not show: The reverse arrow is supported; pleiotropic immunoresolution is not epithelial-specific. Linked erratum must remain attached.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. ErratumIn: PMID36278492. Subclaims: SC2, SC4.

[44] Increased intestinal permeability precedes clinical onset of type 1 diabetes.

Shows: Lactulose/mannitol abnormality was present in autoantibody-positive preclinical as well as clinical diabetes groups.

Does not show: Stage comparison is not a prospective prevention experiment and cannot exclude autoimmunity already causing leak.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC3.

[45] Gut barrier disruption by an enteric bacterial pathogen accelerates insulitis in NOD mice.

Shows: Barrier-disrupting Citrobacter accelerated NOD insulitis; an espF-deficient strain did not.

Does not show: Virulence differences and infection immune effects complicate a pure permeability mediator interpretation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC3.

[46] Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis.

Shows: RA marker relationships differed by sex and disease duration in a proof-of-principle cohort.

Does not show: No healthy control group and unvalidated zonulin assays prevent defining a disease-specific barrier abnormality.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC4.

[47] A single alcohol binge impacts on neutrophil function without changes in gut barrier function and gut microbiome composition in healthy volunteers.

Shows: A single alcohol binge altered neutrophil function without detected barrier or translocation changes in healthy volunteers.

Does not show: Small cohort and short sampling window constrain null inference; immune effects need not require detectable leak.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC6.

[48] Zonulin Regulates Intestinal Permeability and Facilitates Enteric Bacteria Permeation in Coronary Artery Disease.

Shows: CAD blood bacterial sequences and zonulin-kit signals were accompanied by cell-culture junction changes.

Does not show: Low-biomass contamination, assay specificity and established CAD prevent assigning endogenous systemic causality.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[49] Epithelial barrier dysfunction in lymphocytic colitis through cytokine-dependent internalization of claudin-5 and -8.

Shows: Lymphocytic-colitis biopsies had barrier defects; TNF/IFNg reproduced claudin redistribution without MLCK dependence.

Does not show: Cytokines can lie upstream and different junction pathways prevent a single universal leak mechanism.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[50] Metabolic endotoxemia initiates obesity and insulin resistance.

Shows: Chronic subcutaneous LPS infusion induced weight and hepatic metabolic abnormalities and CD14 mutants were protected.

Does not show: Infusion bypasses epithelium and hepatic versus whole-body insulin effects differ; it is not proof of gut leak initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[51] A gut-vascular barrier controls the systemic dissemination of bacteria.

Shows: Gut endothelium formed a second barrier to bacteria; Salmonella penetrated through virulence-dependent beta-catenin disruption.

Does not show: Vascular escape is distinct from epithelial permeability; infection paradigms cannot prove all chronic systemic disease.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[52] Microbiota-driven gut vascular barrier disruption is a prerequisite for non-alcoholic steatohepatitis development.

Shows: Endothelial beta-catenin activation prevented vascular escape and diet-induced NASH despite epithelial translocation.

Does not show: The manipulated layer was vascular, not epithelial; gain-of-function, nonrandomized and unblinded mouse work limits attribution.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Materials and methods:paragraph0, 1:Materials and methods:paragraph1, 2:Results:paragraph0, 2:Results:paragraph9, 2:Results:paragraph11. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[53] Acute low-dose endotoxin treatment results in improved whole-body glucose homeostasis in mice.

Shows: Acute low-dose LPS improved mouse glucose homeostasis while long exposure reduced cell glycogen synthesis.

Does not show: Exposure duration and direct liver effects rebut treating endotoxin concentration as a monotonic metabolic toxin.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC5.

[54] Larazotide acetate induces recovery of ischemia-injured porcine jejunum via repair of tight junctions.

Shows: Larazotide improved ischemia-injured jejunal barrier at an intermediate dose, with fragment-dependent loss of efficacy.

Does not show: Ex vivo repair and nonmonotonic dosing are not systemic disease prevention or unambiguous target identity.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[55] A randomized, double-blind study of larazotide acetate to prevent the activation of celiac disease during gluten challenge.

Shows: Larazotide gluten-challenge trial showed variable permeability assays, null between-group permeability and lower-dose symptom signals.

Does not show: Null primary permeability results and induced gluten exposure prevent claiming barrier-mediated systemic disease initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[56] Larazotide acetate regulates epithelial tight junctions in vitro and in vivo.

Shows: Larazotide limited gliadin/cytokine junction changes and preserved gut junctions in sensitized transgenic mice.

Does not show: Experimental sensitization and junction readouts do not establish endogenous human autoimmune disease initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[57] Larazotide acetate promotes tight junction assembly in epithelial cells.

Shows: Larazotide promoted junction assembly in calcium-switch MDCK and leaky Caco2 models.

Does not show: Assembly physiology in vitro is capped at plausibility for organismal disease.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2.

[58] Larazotide acetate for persistent symptoms of celiac disease despite a gluten-free diet: a randomized controlled trial.

Shows: Low-dose larazotide improved persistent celiac symptoms; higher doses did not differ from placebo.

Does not show: Symptom treatment in established celiac disease is not prevention or proven mediation by reduced epithelial flux.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[59] Larazotide acetate in patients with coeliac disease undergoing a gluten challenge: a randomised placebo-controlled study.

Shows: Larazotide reduced gluten immune/symptom responses but did not significantly change lactulose/mannitol ratios.

Does not show: Clinical and biomarker effects cannot be assigned to permeability when the permeability endpoint was null.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[60] Increased Intestinal Permeability Is Associated With Later Development of Crohn's Disease.

Shows: Baseline permeability in asymptomatic Crohn relatives predicted later Crohn diagnosis over years.

Does not show: Prospective association reduces clinical reverse causation but does not eliminate latent inflammation, inherited risk or common exposures.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC6.

[61] Serum zonulin as a marker of intestinal mucosal barrier function: May not be what it seems.

Shows: CUSABIO and Immundiagnostik assays failed recombinant pre-HP2 detection; immunocaptured proteins included C3 or haptoglobin.

Does not show: Captured abundant proteins did not prove a unique reactive antigen; conclusions are kit-specific, not a denial of permeability.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Materials and methods:paragraph2, 1:Materials and methods:paragraph3, 1:Materials and methods:paragraph4, 1:Materials and methods:paragraph5, 1:Materials and methods:paragraph6, 2:Results:paragraph13, 2:Results:paragraph14, 2:Results:paragraph15, 2:Results:paragraph16, 3:Discussion:paragraph0. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC6.

[62] Targeted epithelial tight junction dysfunction causes immune activation and contributes to development of experimental colitis.

Shows: Constitutively active epithelial MLCK caused immune activation and accelerated transfer colitis without spontaneous disease.

Does not show: Overexpression sufficiency for leak does not establish endogenous necessity and the negative spontaneous-disease result argues for a second hit.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[63] TNFR2 activates MLCK-dependent tight junction dysregulation to cause apoptosis-mediated barrier loss and experimental colitis.

Shows: TNFR2 or long-MLCK deletion delayed transfer colitis, but apoptosis and DSS injury bypassed protection.

Does not show: This maps a stage-specific pathway and its failure boundary, not a universal epithelial or systemic initiator.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[64] Zonulin upregulation is associated with increased gut permeability in subjects with type 1 diabetes and their relatives.

Shows: Elevated serum signals and permeability occurred in a subset of T1D; stored prediagnostic sera showed earlier elevations.

Does not show: Archived precursor-marker association is not randomized prevention; exact historical assay identity must not be equated automatically with later commercial kits.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC3.

[65] Zonulin transgenic mice show altered gut permeability and increased morbidity/mortality in the DSS colitis model.

Shows: Zonulin-transgenic mice had greater DSS morbidity and antagonist rescue.

Does not show: DSS and overexpression define a sensitization experiment; neither demonstrates spontaneous human cross-disease initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[66] The liver may act as a firewall mediating mutualism between the host and its gut commensal microbiota.

Shows: Kupffer-cell clearance and liver damage experiments support a hepatic firewall to circulating gut commensals.

Does not show: Clearance failure can raise systemic exposure independently of epithelial leak and does not identify the first human disease event.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC2, SC6.

[67] Widely Used Commercial ELISA Does Not Detect Precursor of Haptoglobin2, but Recognizes Properdin as a Potential Second Member of the Zonulin Family.

Shows: ELISA signals failed to reflect HP genotype and did not detect recombinant pre-HP2; properdin was a candidate target.

Does not show: Properdin identity and pathogenic function are not settled by immunocapture alone; correlated kit signals are not validated epithelial flux.

Access/status: Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Materials and Methods:paragraph1, 1:Materials and Methods:paragraph9, 1:Materials and Methods:paragraph10, 1:Materials and Methods:paragraph11, 1:Materials and Methods:paragraph15, 1:Materials and Methods:paragraph16, 2:Results:paragraph0, 2:Results:paragraph1, 2:Results:paragraph2, 2:Results:paragraph4. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC6.

[68] Increased jejunal permeability in human obesity is revealed by a lipid challenge and is linked to inflammation and type 2 diabetes.

Shows: Fasting permeability was similar between obese and controls, while lipid challenge increased ex vivo macromolecular flux more in obesity.

Does not show: Diet challenge, established obesity, inflammation and ex vivo assays do not establish human metabolic initiation.

Access/status: Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed. none_found. Subclaims: SC1, SC5.

Documentary record

Every grade on this site is reproducible from its record. The files below are the posted edition exactly as assessed.

• SHA256.txt
• codex-correction-provenance.json
• consensus-addendum.md
• consensus-validation.json
• edition-approval-audit.json
• leaky-gut-systemic-disease.review.md
• leaky-gut-systemic-disease.scorecard.json
• validation-report.json
• validation-round2-2026-10-14.json
• validation.txt

Sources: 68 · load-bearing claims: 75 · verified: 75 · unverified: 0 · contradicted: 0 · schema 5.3