Differential expression of TLR2, TLR4 and JNK in mucosa of ileal pouches for ulcerative colitis. Is there a role for bacterial antigen pathway in asymptomatic patients?

Abstract

Introduction: Ileal pouch-anal anastomosis (IPAA) is the preferred surgical procedure for patients with refractory ulcerative colitis (UC) and familial adenomatous polyposis (FAP). However, pouchitis is the most common complication after IPAA in UC patients and only occurs after ileostomy closure. Therefore, it is important to get more information about the role of the ileal pouch microbiota and mucosa susceptibility to inflammation in UC patients. Therefore, we evaluated Toll-like receptors (TLRs) expression in normal endoscopic and histological mucosa of the ileal pouch in patients with UC and FAP, in order to find any abnormality in this pathway in asymptomatic patients, which may contribute to pouchitis.

Materials and methods: Twelve patients (six with UC and six with FAP) with "J" pouch reconstruction, after total rectocolectomy, were studied. Biopsies were obtained from the mucosa of the pouch. Normal ileum biopsies were obtained from six patients submitted to ileocolonoscopy with no abnormalities. The specimens were snap-frozen and the expressions of TLR2, TLR4 and JNK (nuclear signalization factor) were determined by immunoblot protein extract.

Results: Patients with UC had significantly higher protein levels of TLR4 than controls and FAP. The expressions of TLR2 and JNK were similar in the groups.

Conclusion: Patients with UC had higher levels of TLR4, even in the absence of clinical, endoscopic and histological pouchitis. These findings may explain a tendency towards the up-regulation of intracellular pathways activated by bacterial antigens in UC patients, which could contribute to the production of proinflammatory mediators and pouchitis development.

Keywords: cytokines; familial adenomatous polyposis; ileal pouch; pouchitis; toll-like receptors; ulcerative colitis.

Figure 1

Representative Western blot analyses and determination of TLR4 protein expression in non-inflamed pouches in the Control, FAP and UC groups. For illustration purpose each line band represents one patient. For all conditions, n=06, *p<0.05 vs Control; § p<0.05 vs FAP.

Figure 2

Representative Western blot analyses and determination of TLR2 protein expression in noninflamed pouches in the Control, FAP and UC groups. For illustration purpose each line band represents one patient. For all conditions, n=06, *p<0.05 vs Control; § p<0.05 vs FAP.

Figure 3

Representative Western blot analyses and determination of JNK protein expression in noninflamed pouches in the Control, FAP and UC groups. For illustration purpose each line band represents one patient. For all conditions, n=06, *p<0.05 vs Control; § p<0.05 vs FAP.