Expression of integrin alphavbeta6 in the intestinal epithelial cells of patients with inflammatory bowel disease

Abstract

Background and aims: The prevalence of inflammatory bowel disease (IBD) is about 0.05% in industrialized countries. The pathogenesis of IBD remains to be further understood. The present study aims to elucidate the expression of integrin αvβ6 in the intestinal mucosa of patients with IBD.

Materials and methods: Colonic biopsy was obtained from a group of IBD patients. The expression of αvβ6 in the intestinal mucosa was detected by Western blotting. Human colonic epithelial cell line T84 cells were stimulated by microbial antigen flagellin. The expression of αvβ6 in T84 cells was evaluated by quantitative RT-PCR and Western blotting.

Results: The levels of αvβ6 in the intestinal mucosa were much lower than it in normal control subjects. The serum levels of myeloperoxidase (MPO) were higher in IBD patients that were negatively correlated with the levels of αvβ6 in the intestinal mucosa. The expression of αvβ6 was detectable in T84 cells at naοve status that could be upregulated by exposure to microbial antigen flagellin. Pretreatment with MPO dramatically suppressed the expression of αvβ6 in T84 cells.

Conclusions: We conclude that the expression of αvβ6 was suppressed in IBD intestinal mucosa, which could be resulted from the high levels of MPO.

Keywords: Inflammatory bowel disease; integrin; intestine; mucosa; oral tolerance.

Fig. 1

Expression of αvβ6 in IBD intestinal mucosa. Colonic biopsies were obtained from IBD patients. Expression of αvβ6 in the biopsies was examined by Western blotting. Panel A shows αvβ6 immune blots. Panel B shows the densitometry data of band analysis; data were expressed as percentage of β-actin (means ± SD). *: p<0.05, compared with normal control. UC: Ulcerative colitis. CD: Crohn's disease. Active: IBD patients with active inflammation. Remi: IBD patients at remission period.

Fig. 2

Serum MPO levels of IBD patient. Blood samples were obtained from each patients and control subjects. The sera were isolated and subjected to analysis of MPO levels by ELISA.

Fig. 3

Microbial antigen increases the expression avβ6 in human colonic epithelial cells. Human colonic epithelial cell line T84 cells were cultured and exposed to FGN for 3 h. A, bars indicate the β6 mRNA levels in T84 cell extracts. B, upper gel shows αvβ6 immune plots of protein extracts from T84 cells. The lower gel shows β-actin's immune plots using as internal control. Bars indicate the densitometry analysis data. Data were presented as mean ± SD. *, p<0.05, compared with group “0”.

Fig. 4

MPO suppresses the expression αvβ6 in human colonic epithelial cells. Human colonic epithelial cell line T84 cells were cultured and exposed to FGN (10 µg/ml) in the presence of MPO at graded doses for 3 h. A, bars indicate the β6 mRNA levels in T84 cell extracts. B, upper gel shows αvβ6 immune plots of protein extracts from T84 cells. The lower gel shows β-actin's immune plots using as internal control. Bars indicate the densitometry analysis data. Data were presented as mean ± SD. *: p<0.05, compared with group “0”.

Fig. 5

Expression of αvβ6 in colonic mucosa is correlated with inflammatory status. Colonic biopsies were taken from IBD patients in active status (A) and remission period (B). Paraffin sections were stained with hametoxylin and eosin. The Western blotting gels show αvβ6 blots from protein extracts.