Protective effects of Acetobacter ghanensis against gliadin toxicity in intestinal epithelial cells with immunoregulatory and gluten-digestive properties.

Abstract

The aim of this study was to establish whether Acetobacter ghanensis, the probiotic characteristics of which were evaluated previously, attenuates gliadin-induced toxicity in intestinal epithelial cells with gluten-digestive and immunoregulatory properties. A co-culture model of human intestinal epithelial cell (Caco-2) monolayers on top of peripheral blood mononuclear cells (PBMCs) obtained from patients with celiac disease (CD) was established. The gluten-digestive properties of A. ghanensis were determined by checking bacterial growth in a medium containing gluten as the main nitrogen source. The mRNA levels of genes encoding TJ-associated proteins were measured by quantitative real-time PCR (qRT-PCR). The concentrations of IL-6 and TNFα were determined by enzyme-linked immunosorbent assay (ELISA). We found that PT-gliadin disrupted intestinal barrier integrity by modulating the expression of TJ-associated genes encoding zonulin (increased by ~ 60%), zonula occludens-1 (ZO-1) (decreased by ~ 22%), and occludin (decreased by ~ 28%) in Caco-2 cells. Furthermore, PT-gliadin treatment in Caco-2 cells was associated with increased concentrations of IL-6 (~ 1.6-fold) and TNFα (~ twofold) from PBMCs. These modulatory effects of PT-gliadin, however, were suppressed when Caco-2 cells were subjected to A. ghanensis in the presence of PT-gliadin. As a factor underlying these protective effects, we showed that A. ghanensis could digest gluten peptides. To our knowledge, the current study is the first to demonstrate that A. ghanensis improves intestinal barrier functions by attenuating the modulatory effects of PT-gliadin with immunoregulatory and gluten-digestive properties.