Role of the Innate Immune System in the Pathogenesis of Gluten Sensitivity : Preliminary Study

de Magistris, Alessio Fasano, Gabriele Riegler Background: Reaction to gluten can involve either an allergic (wheat allergy), or nonallergic [gluten sensitivity (GS)], or an autoimmune [celiac disease (CD)] mechanism. Recent evidences suggest that early changes in intestinal permeability (IP) may play a pivotal role in the pathogenesis of CD. Conversely, no data are available on the role of IP in the pathogenesis of GS. Aims: To investigate the changes in IP, TJ protein genes expression and TLRs in GS and to establish whether these changes are related to an over expression of inflammatory cytokines. Methods: After obtaining informed consent, biopsy samples were obtained from 17 GS patients (pts), 27 pts with active CD, 5 pts with CD in remission, and 11 healthy controls (age range: 5 years -50 years). Quantitative gene expression of TJ proteins Claudin (CL) 1, CL2, CL3, CL4, ZO-1 and of TLR1, TLR2 and TLR4 were performed by Real-time PCR. IP was evaluated by means of the lactulose/mannitol test (LA/MA). Cytofluorimetric analyses of IL6, IL8, TNFα, IFNγ were conducted on PBMC of all patients. Results: Expression of CL1, CL3 and CL4 were significantly increased in GS subjects compared to healthy controls, while no changes in CL2, ZO-1 and Occludin expression were detected. This up-regulation did not influence IP, since in GS patients IP (0.017±0.012) was similar to that detected in healthy controls (0.016±0.010). Conversely, in CD patients a significant over-expression of CL1 and CL2 was observed, while no significant changes in the other TJ proteins were detected. The increased expression of CL1/2 was associated to an increase in IP (0.202±0.55). In CD patients in remission both IP (0.014±0.004) and CL1/2 expression returned to normal levels. To evaluate if the innate immune system is involved in the pathogenesis of GS, TLRs expression was measured in a subgroup of patients. TLR1, but not TLR2 and TLR4, resulted significantly increased in CD (p=0,027) and in the GS (p=0,0039) respect to normal controls. Preliminary results showed that in GS patients up-regulation of CL was associated to increased expression of IL6 and IL8. Conclusions: Compared to CD patients, GS subjects showed normal IP and CL2 expression, while the other CL tested were up-regulated. These data suggest different pathogenic mechanisms in the two conditions, i.e., in GS loss of intestinal barrier function is not involved. The over expression of TLR 1 in CD and GS could suggest an important role of innate immune system in both conditions. Gluten Sensitivity appears to be a new chapter in the book of “Food intolerance” to be investigated.