The Deletion of IL-17A Enhances Colonization and Triggers Colitis.

OBJECTIVE

IL-17 is a key regulator of the inflammatory response, and as such, it is involved in the constraint and clearance of pathogens. The mechanism of IL-17 in the pathogenesis of inflammatory bowel disease (IBD) caused by microbial infection is still unclear. infection can induce colitis in many mouse strains, and thus, it has been widely used in the study of IBD pathogenesis.

METHODS

In this study, male C57BL/6, BALB/c, Il-10, and Il-17a mice were infected with for several weeks. Histopathology, colonization and distribution, expression of inflammatory cytokines and lysozyme, and distribution of mucus in proximal colon were examined.

RESULTS

The colonic colonization of was abnormally high in Il-17a mice. infection caused only mild to moderate colitis symptoms in Il-17a mice, including low levels of lymphocyte infiltration, epithelial cell defects, goblet cell reduction, and crypt atrophy without obvious hyperplasia in the later stage of infection. Furthermore, many inflammatory genes were significantly increased in the proximal colon of -infected Il-17a mice compared with C57BL/6 mice. In addition, the reduction of colonic mucus and the down-regulation of ZO-1, Claudin-1, and IL-22 were observed in Il-17a mice compared with C57BL/6 mice post infection.

CONCLUSION

These results demonstrated that the deletion of IL-17A impaired the integrity of the intestinal epithelium, weakened the secretion of mucus, attenuated colonic mucosal regeneration, reduced the ability to resist microbial infection, and finally led to colitis caused by .