Toll-like receptor expression in crypt epithelial cells, putative stem cells and intestinal myofibroblasts isolated from controls and patients with inflammatory bowel disease.

M Brown,S Moossavi,Y R Mahida,K R Hughes,A Robins

doi:10.1111/cei.12381

Abstract

The aim of our studies was to investigate the expression of Toll-like receptor (TLR)-2 and TLR-4 (and in some studies TLR-5) in myofibroblasts and small and large intestinal crypt epithelial cells from control patients and those affected by Crohn's disease and ulcerative colitis. Isolated and disaggregated crypt epithelial cells and monolayers of myofibroblasts were used for studies by reverse transcription–polymerase chain reaction (RT–PCR), real-time RT–PCR, flow cytometry, immunocytochemistry and Western blot analysis. Compared to control cells, crypt epithelial cells isolated from active ulcerative colitis and Crohn's disease colonic mucosal samples showed significantly higher expression of TLR-2 and TLR-4 transcripts and protein (on the cell surface). There was also enhanced expression of TLR-4 in crypt cells from ileal Crohn's disease. Expression of TLR-2 and TLR-4 transcripts in crypt epithelial cells isolated from inflamed mucosa of distal ulcerative colitis did not differ significantly from such cells obtained from the normal proximal colon. Crypt epithelial cells with side population characteristics (putative stem cells) also expressed transcripts and protein for TLR-2, TLR-4 and TLR-5. Colonic myofibroblast expression of these TLRs was much weaker than in crypt epithelial cells. In conclusion, enhanced TLR-2 and TLR-4 expression by crypt epithelial cells in active inflammatory bowel disease likely reflects greater ability to respond to microbial products. Results from our studies using mucosal samples from patients with distal ulcerative colitis suggest that the enhanced expression of these TLRs could be constitutive. TLR-2, TLR-4 and TLR-5 expression by stem cells imply ability to respond to distinct bacterial products.

Highlights

The inflammatory bowel diseases (IBD), ulcerative colitis and Crohn’s disease, are a group of chronic conditions affecting the gastrointestinal tract characterized by a relapsing and remitting course
In addition to providing a physical barrier to penetration by resident bacteria and their products, epithelial cells may shape immune responses mediated by cells in the lamina propria
Histological examination of mucosal samples from patients with inflammatory bowel disease showed mild to Intestinal toll-like receptor expression severe inflammation and they were on the following treatment at the time of intestinal resection: mesalazine (14), corticosteroids, azathioprine/6-mercaptopurine (15), methotrexate, infliximab/adalimumab, cyclosporin, metronidazole

Summary

Introduction

The inflammatory bowel diseases (IBD), ulcerative colitis and Crohn’s disease, are a group of chronic conditions affecting the gastrointestinal tract characterized by a relapsing and remitting course. The pathogenesis of IBD remains to be fully understood, studies have implicated the epithelium, innate and adaptive immunity and resident (commensal) bacteria in disease pathogenesis [1,2]. Changes in the nature of these interactions are believed to be required for the development of chronic inflammatory disease of the intestine, as seen in IBD [1,2]. In addition to providing a physical barrier to penetration by resident bacteria and their products, epithelial cells may shape immune responses mediated by cells in the lamina propria. This may occur via specific receptors which recognize and respond to bacterial products. Toll-like receptors (TLRs) are the best-known sensors of microbial components [6], and act by regulating gene expression

Methods

Discussion

Conclusion