Probiotics Supplements Reduce ER Stress and Gut Inflammation Associated with Gliadin Intake in a Mouse Model of Gluten Sensitivity (1)

In Celiac Disease (CD) patients, gliadin, a gluten component, binds the chemokine CXC motif receptor 3 (CXCR3), thus promoting the release of Zonulin, resulting in the disassembly of tight junctions, with gliadin crossing the epithelial barrier. Next, through tissue transglutaminase 2 (TG2) activity, deamidated gliadin binds the HLA- DQ2/8 molecules on antigen-presenting cells (APCs). Active TG2 leads to NF-κB activation, causing an increased level of proinflammatory cytokines such as IL-15, IL-17A, and IL-21, the main cytokines involved in CD pathogenesis. new therapeutic approaches have been suggested which include Zonulin receptor inhibitors, engineered gluten-free grain, TG2 inhibitors, and probiotics in addition to the diets. Gut microbiota dysbiosis has been associated to the development and progression of several chronic gut diseases such as IBD, Colitis, and CD. Interestingly, dysbiosis often persists unexpectedly in some CD patients despite the gluten-free diet, with this condition potentially and surprisingly being induced by this restricted diet.

Balb/c gluten-sensitive mice were established by exposing to gliadin for 4 weeks and to gliadin in presence test articles formulations for 2 more weeks.

Gliadin exposure efficiently downregulated the expression of CFTR and consistently elevated the expression of TG2 at both mRNA and protein levels. The concomitant administration of P1 or P2 efficiently inhibited the gliadin induced TG2 upregulation at both mRNA and protein levels. The two probiotic formulations were able to restore, at least in part, the physiological protein levels of CFTR.

Fluorescence (FITC), measured in the plasma of mice, shows a considerable increased permeability in mice exposed to gliadin compared to untreated control mice. Occludin (three TJ components) observed in mice exposed to gliadin compared to controls and previously associated to abnormal intestinal permeability. The co-administration of P1 or P2 consistently inhibited the intestinal permeability abnormality mediated by the gliadin active peptides.

The upregulation of key pro-inflammatory cytokines, IFN–IL-15–IL-17A, in small intestine lysates of gliadin sensitive animals exposed 6 weeks to gliadin. The presence of P1 or P2 consistently inhibited the upregulation of the pro-inflammatory genes and cytokine release.

A consistent upregulation of the three main ER Stress markers, ATF4, ATF6, and XBP1, compatible with a chronic ER Stress condition. The exposure of gliadin-treated mice to P1 or P2 completely abrogated the gliadin-mediate upregulation of both ATF4 and XBP1. While the expression of ATF6 was completely inhibited by P1, in the same experimental conditions, P2 failed since the levels of this factor remained elevated.

PT efficiently downregulated the expression of CFTR as soon as 3 h, and its low expression level was stable at 9 h posttreatment. A prompt upregulation of TG2 (at 3 h), which was still evident after 9 h of PT treatment.

A major rule in the ignition of immune response toward gliadin peptides produced by partial enzymatic digestion in the intestine is played by tissue transglutaminase 2 (TG2). This enzyme is able to deaminate the glutamine rich gliadin-derived, resulting in an enhanced affinity to HLA-DQ2 or DQ8, finally resulting in downstream activation and CD4+T cell-mediated response. Altered microbiota homeostasis (dysbiosis) has been linked to the onset/progression of diseases characterized by inflammation of the GI tract, such as Crohn’s Disease, Ulcerative Colitis, and CD.

1. E. Ferrari, R. Monzani, V. Saverio, M. Gagliardi, E. Pańczyszyn, V. Raia, V. R. Villella, G. Bona, M. Pane, A. Amoruso, M. Corazzari, Probiotics Supplements Reduce ER Stress and Gut Inflammation Associated with Gliadin Intake in a Mouse Model of Gluten Sensitivity. Nutrients. 13 (2021), doi:10.3390/nu13041221.