Celiac Disease Monocytes Induce a Barrier Defect in Intestinal Epithelial Cells

Abstract

Intestinal epithelial barrier function in celiac disease (CeD) patients is altered. However, the mechanism underlying this effect is not fully understood. The aim of the current study was to evaluate the role of monocytes in eliciting the epithelial barrier defect in CeD. For this purpose, human monocytes were isolated from peripheral blood mononuclear cells (PBMCs) from active and inactive CeD patients and healthy controls. PBMCs were sorted for expression of CD14 and co-cultured with intestinal epithelial cells (IECs, Caco2BBe). Barrier function, as well as tight junctional alterations, were determined. Monocytes were characterized by profiling of cytokines and surface marker expression. Transepithelial resistance was found to be decreased only in IECs that had been exposed to celiac monocytes. In line with this, tight junctional alterations were found by confocal laser scanning microscopy and Western blotting of ZO-1, occludin, and claudin-5. Analysis of cytokine concentrations in monocyte supernatants revealed higher expression of interleukin-6 and MCP-1 in celiac monocytes. However, surface marker expression, as analyzed by FACS analysis after immunostaining, did not reveal significant alterations in celiac monocytes. In conclusion, CeD peripheral monocytes reveal an intrinsically elevated pro-inflammatory cytokine pattern that is associated with the potential of peripheral monocytes to affect barrier function by altering TJ composition.

Inulin ameliorates schizophrenia via modulation of the gut microbiota and anti-inflammation in mice

“…Tight junction indicators, ZO-1 and occludin, play indispensable roles in maintaining the intestinal mucosal barrier 49 . Our morphological results showed that the expression levels of the tight junction proteins (occludin and ZO-1) were reduced in SCZ mice, indicating increased intestinal permeability and impaired mucosal barrier, which were also observed in other diseases, such as in celiac disease 50 , IBD 51 , and diabetes 52 . However, drastically elevated expression of ZO-1 and occludin in the INU+SCZ group suggested that inulin could improve intestinal integrity and permeability, which was consistent with a previous study 39 .…”

Systematic Prioritization of Candidate Genes in Disease Loci Identifies TRAFD1 as a Master Regulator of IFNγ Signaling in Celiac Disease

“…We evaluated the transcriptional changes of knocking down TRAFD1 in the monocyte-like cell line THP-1 under resting conditions (unstimulated) or in the presence of LPS, a known inducer of the NFκB pathway (Dorrington and Fraser, 2019 ). We selected this cell line considering the role of monocytes in modulating the epithelial barrier function and cytokine secretion in a CeD-specific context (Delbue et al, 2019 ), as well as for the technical ability to alter the expression of TRAFD1 using siRNA and the quick response of monocytes to LPS (Sharif et al, 2007 ).…”

Pro-Inflammatory Effect of Gliadins and Glutenins Extracted from Different Wheat Cultivars on an In Vitro 3D Intestinal Epithelium Model

“…CD14 staining of the glycolipid-anchored membrane glycoprotein expressed on U937 cells enabled the identification of the pro-inflammatory-induced activation of the latter, which in the present study were greater following exposure to the higher gluten strength modern flour proteins. Interestingly, incubation of CD14 activated monocytes isolated from CD patients with cultured epithelial cells, resulting in an increase in TJ permeability, lower levels of occludin, and a mosaic expression pattern of ZO-1, an effect that was not evident following incubation with monocytes of healthy donors [ 48 ]. Given the potency of activated monocytes, the potential contribution of activated U937-monocyte-induced effects on Caco-2 cell TJ proteins cannot be excluded.…”