The expression of Toll-like receptors-2 and-4 by human crypt intestinal epithelial cells, intestinal myofibroblasts and putative intestinal stem cells in inflammatory bowel disease

• Main Author: Brown, Matthew
• Published: University of Nottingham 2012
• Subjects: 616.3; WI Digestive system
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.576816

Host-microbial interactions are of major importance in the pathogenesis of inflammatory bowel disease (IBD). Toll-like receptors (TLR) are pattern recognition receptors which recognise conserved molecular patterns derived from micro-organisms. Crypt intestinal epithelial cells (IEC) were isolated form mucosal specimens of healthy controls and patients with IBD (ulcerative colitis, UC, and Crohn's disease). A population of IEC enriched for intestinal stem cells (ISC) were identified using Hoechst dye exclusion and by their adherence to cultured primary intestinal myofibroblast cell monolayers. Compared to healthy control colon, TLR2 and TLR4 mRNA and surface protein were significantly up-regulated in crypt IEC isolated from the inflamed mucosa of UC and Crohn's colitis. Compared to healthy control ileum, TLR4 mRNA was significantly up-regulated in crypt epithelial cells isolated from the inflamed mucosa of Crohn‟s ileitis. TLR2 and TLR4 mRNA expression from histologically normal and inflamed colonic mucosa in UC did not significantly differ, and expression of TLR4 transcripts was significantly greater in crypt IEC isolated from histologically normal proximal colonic mucosal samples compared to healthy controls. Myofibroblast-adherent crypt cells expressed TLR2 and TLR4 protein to a greater level than the underlying myofibroblasts. Hoechst-effluxing putative intestinal stem cells expressed both TLR2 and TLR4 transcripts and protein, and TLR3 and TLR5 transcripts. In conclusion, crypt intestinal epithelial cells up-regulated TLR2 and TLR4 expression in UC and Crohn's colitis and up-regulated TLR4 expression in Crohn's ileitis. TLR2 and TLR4 was expressed constitutively in crypt IEC from histologically normal mucosa, suggesting differential TLR expression may in part be a primary event in UC. This provides further insights into the pathogenesis of IBD. Putative intestinal stem cells expressed TLR2, TLR3, TLR4 and TLR5, suggesting that direct microbial sensing by ISC may be important in maintaining intestinal homeostasis and in regulating ISC function.