Differential effect of immune cells on non‐pathogenic Gram‐negative bacteria‐induced nuclear factor‐κB activation and pro‐inflammatory gene expression in intestinal epithelial cells

Abstract

SUMMARYWe have previously shown that non-pathogenic Gram negative bacteria induce RelA phosphorylation, nuclear factor (NF)-jB transcriptional activity and pro-inflammatory gene expression in intestinal epithelial cells (IEC) in vivo and in vitro. In this study, we investigated the molecular mechanism of immune-epithelial cell cross-talk on Gram-negative enteric bacteria-induced NF-jB signalling and pro-inflammatory gene expression in IEC using HT-29/ / MTX as well as CaCO-2 transwell cultures Interestingly, while differentiated HT-29/ /MTX cells are unresponsive to non-pathogenic Gram negative bacterial stimulation, interleukin-8 (IL-8) mRNA accumulation is strongly induced in Escherichia coli-but not Bacteroides vulgatus-stimulated IEC cocultured with peripheral blood (PBMC) and lamina propria mononuclear cells (LPMC). The presence of PBMC triggered both E. coli-and B. vulgatus-induced mRNA expression of the Toll-like receptor-4 accessory protein MD-2 as well as endogenous IjBa phosphorylation, demonstrating similar capabilities of these bacteria to induce proximal NF-jB signalling. However, B. vulgatus failed to trigger IjBa degradation and NF-jB transcriptional activity in the presence of PBMC. Interestingly, B. vulgatus-and E. coli-derived lipopolysaccharide-induced similar IL-8 mRNA expression in epithelial cells after basolateral stimulation of HT-29/ /PBMC cocultures. Although luminal enteric bacteria have adjuvant and antigenic properties in chronic intestinal inflammation, PBMC from patients with active ulcerative colitis and Crohn's disease differentially trigger epithelial cell activation in response to E. coli and E. coli-derived LPS. In conclusion, this study provides evidence for a differential regulation of non-pathogenic Gram-negative bacteria-induced NF-jB signalling and IL-8 gene expression in IEC cocultured with immune cells and suggests the presence of mechanisms that assure hyporesponsiveness of the intestinal epithelium to certain commensally enteric bacteria.

Suppression of NF-κB Activation by Entamoeba histolytica in Intestinal Epithelial Cells Is Mediated by Heat Shock Protein 27

“…To simulate this, several in vitro studies were carried out to assess the epithelial cell responses in the presence of immune cells such as leukocytes and lymphocytes. Under these conditions, a differential response was observed in epithelial cell lines exposed to various pathogenic and nonpathogenic bacteria (9,10). However, the effect of co-culturing with macrophages on epithelial cell responses has not been well characterized.…”

“…Hsp serve to protect the cells against several insults such as thermal, toxic, or apoptotic stimuli (12, 14 -16). Epithelial cell induction of Hsp in response to various pathogens such as E. coli, and toxins such as lipopolysaccharide and superantigen have been reported (10,12,14). It has also been shown that epithelial Hsp expression is regulated by cytokines and immune cells such as lymphocytes (13).…”

Role of Il - 23 in Crohn’s Disease and Ulcerative Colitis and Other Premalignant Disease , It’s Therapeutic S Approach

“…In several studies the bacterial DNA or bacteria as a whole were confirmed to express inflammatory responses. [9,10] The idea to introduce Lipopolysaccharide (LPS), a product of gram negative bacterial cell wall as an inflammatory agent is a new approach of our research laboratory for this study since no study in this regard has been made so far.…”

Involvement of capsular polysaccharide via a TLR2/NF-κB pathway in Vibrio vulnificus-induced IL-8 secretion of human intestinal epithelial cells

“…As IL-8 is a chemokine that plays a pivotal role in the mobilization of cellular defense mechanisms and may signal the onset of an acute inflammatory response (14,23), the CPS of V. vulnificus may constitute an important mediator of inflammatory response, which contributes to the epithelial injury inherent to V. vulnificus infection. Many other studies have reported that the infection of intestinal epithelial cells with pathogenic bacteria including H. pylori, S. typhimurium, EPEC or Bacillus subtilis results in increases in IL-8 production (32,33). In particular, surface polysaccharides such as CPS and lipopolysaccharides, perform crucial functions in the pathogenicity of gram-negative bacteria (4,5).…”