Non-Coeliac Wheat Sensitivity narrative review 2025 — H5 / B-Gen-2 promoted candidate

One-paragraph summary

Narrative review of non-coeliac wheat sensitivity (NCWS) as a clinical and biological entity. Self-reported rates >10% of general population but rigorous double-blind placebo-controlled challenge (DBPCC) studies confirm diagnosis in <30% of cases. Clinical presentation: IBS-like GI symptoms + systemic complaints including "brain fog," headaches, and fatigue — directly overlapping with FM/ME/CFS phenotype. Pathophysiology distinct from coeliac disease: innate immune activation, altered intestinal barrier function, gut dysbiosis. Non-gluten wheat components — fructans and amylase-trypsin inhibitors (ATIs) — implicated as potential triggers. Diagnostic challenge: requires exclusion of other disorders and adherence to complex dietary challenge protocols (Salerno Experts' Criteria). Biomarker candidates investigated: serological (IgG anti-gliadin antibodies), inflammatory (faecal calprotectin), barrier-integrity (zonulin) — but results conflicting. Management primarily wheat/gluten elimination + low-FODMAP adjunct. This paper was previously deferred in the project queue; the H5 framework re-opens it as a directly-relevant candidate. NCWS is the H5/H5b-aligned clinical entity in which wheat-driven innate immune activation + barrier failure + dysbiosis converges — the candidate "non-celiac" phenotype that H5 patients with non-DQ2/DQ8 HLA backgrounds might present as.

Claims as triples

• non_coeliac_wheat_sensitivity — overlaps_with → irritable_bowel_syndrome [evidence: clinical overlap; confidence: established]
• non_coeliac_wheat_sensitivity — overlaps_with → fibromyalgia [evidence: symptom overlap (brain fog, fatigue, systemic); confidence: bridging]
• non_coeliac_wheat_sensitivity — drives → intestinal_permeability [evidence: review consolidation; confidence: emerging]
• non_coeliac_wheat_sensitivity — drives → gut_brain_axis_disruption [evidence: review; confidence: emerging]
• amylase_trypsin_inhibitor — activates → innate_immunity [evidence: review; confidence: emerging]
• fructan — triggers → non_coeliac_wheat_sensitivity [evidence: DBPCC studies; confidence: emerging]
• gluten_free_diet — reduces → non_coeliac_wheat_sensitivity [evidence: management standard; confidence: emerging]

Methods note

Narrative review consolidating clinical, immunological, and dietary-challenge literature on NCWS. Methodologically constrained by the lack of validated diagnostic biomarkers — DBPCC remains the gold standard but is impractical for routine clinical use. The conflicting biomarker results across studies are partly attributable to the heterogeneity of the clinical entity (likely multiple sub-phenotypes within the NCWS umbrella).

Limitations

• Narrative not systematic
• NCWS diagnostic criteria still controversial
• Biomarker validation literature is heterogeneous
• FM extension is project-driven (review does not directly cite FM)
• DBPCC studies confirm <30% of self-reported NCWS — over-diagnosis caveat
• Mechanism layer (innate immunity + barrier failure + dysbiosis) is consistent with the H5/H5b framework but not specifically anchored on FM

Open questions raised

• Q-Gen-13 (new): What is the prevalence of NCWS within the FM-IgG-positive cohort? FM patients self-reporting "wheat sensitivity" + IBS-like GI symptoms should be DBPCC-tested for NCWS — if confirmed at >30%, the H5 framework gains a substantial validation.
• Q-Gen-14 (new): Do fecal calprotectin + zonulin + anti-gliadin IgG levels stratify FM-IgG-positive patients into NCWS-positive vs NCWS-negative subgroups? If yes, biomarker stratification at low cost.
• Q-Gen-15 (new): Does a stratified gluten-free trial (extending Q-Gen-5) include NCWS-positive non-HLA-DQ2/DQ8 FM patients? The original Q-Gen-5 stratifies on HLA-DQ2/DQ8 carriage; this paper suggests NCWS may be HLA-independent.

Triangulation notes

• Promotes the deferred candidate 2025-s-non-coeliac-wheat-sensitivity-symptoms from queue to ingested. The pre-H5 project did not have a framework to ingest NCWS literature; H5 supplies it.
• Extends B-Gen-2 (celiac-spectrum ↔ FM) to the non-celiac arm. The B-Gen-2 bridge was framed around celiac-spectrum disease; NCWS extends the spectrum into HLA-independent wheat sensitivity. H5/H5b therefore have two overlapping but distinct cross-condition anchors: classical celiac (HLA-DQ2/DQ8 + anti-tTG positive) and NCWS (HLA-DQ2/DQ8 carriage variable, anti-tTG negative, innate immunity activation).
• Compatible with the H5b barrier-failure arm: the MYO9B + OCLN + TJP1 + CLDN2 genetic-vulnerability framework would predict that NCWS-positive FM patients carry barrier-failure variants at population enrichment vs NCWS-negative FM patients.
• Compatible with the H2 mast-cell framework: amylase-trypsin inhibitors are known MRGPRX2 ligands in some contexts; NCWS-MC connection is testable.
• Closes some of the deferred candidate audit gap: NCWS papers (including the candidate-queue paper just promoted) become a coherent sub-domain within the project rather than orphaned in the queue.

Bridges

• B-Gen-2 extension: bridge now spans classical celiac AND non-celiac wheat sensitivity. Bridge advances bridging → bridging-with-clinical-entity-anchor.
• New candidate bridge B-NCWS-MC (NEW): amylase-trypsin inhibitors ↔ FM via MRGPRX2/innate immunity activation. Bridging tier. Testable via ATI-stimulated patient-derived MC degranulation.

Ontology additions needed

• Add non_coeliac_wheat_sensitivity as comorbidity entity
• Consider adding amylase_trypsin_inhibitor (ATI) as new molecule entity
• Consider adding fructan as new molecule entity (existing project has SCFA; fructans are upstream substrate)
• Consider adding anti_gliadin_IgG as new biomarker entity (paired with existing anti-tTG)
• Consider adding fecal_calprotectin as new biomarker entity

Chain-map update

• H5/H5b clinical-entity anchor: NCWS becomes the H5/H5b-aligned clinical entity for non-celiac HLA-DQ2/DQ8 FM patients. Q-Gen-5 stratification gains a sub-arm for NCWS-positive non-HLA-DQ2/DQ8 patients.
• B-Gen-2 framing: the celiac-spectrum bridge now explicitly includes both HLA-DQ2/DQ8-positive (classical celiac) AND HLA-DQ2/DQ8-negative (NCWS) arms.

Confidence-tier framing

• NCWS as distinct clinical entity: emerging (clinical overlap established; biomarker validation pending)
• NCWS overlap with FM symptom domains: bridging (project-driven inference from symptom overlap)
• NCWS mechanism = innate immunity + barrier + dysbiosis: emerging (review consolidation)
• ATI as MRGPRX2 ligand in FM: inferred (predicted by H2 + H5b framework; not tested)
• B-Gen-2 closure: partial (NCWS clinical anchor; FM-direct evidence still required)