Role of miR-22 in intestinal mucosa tissues and peripheral blood CD4+ T cells of inflammatory bowel disease.

Objective: miR-22 is known to be involved in the pathogenesis of several autoimmune diseases, but it remains unclear whether miR-22 is associated with inflammatory intestinal disease (IBD).

Methods: The patients with ulcerative colitis (UC) and Crohn's disease (CD) were enrolled in this study. After the CD4+ T cells from healthy controls and active IBD patients were isolated and then transfected with miR-22 mimics/inhibitors, Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to measure expressions of miR-22, HDAC4, specific transcription factors in intestinal mucosa tissue and CD4+ T cells, while enzyme-linked immuno sorbent assay (ELISA) to detect expressions of inflammatory cytokines in PB. Antisense miR-22 was administered into mice during trinitrobenzene sulphoni cacid (TNBS)-induced colitis to determine its role in IBD.

Results: A significant elevation of miR-22 but an evident decrease of HDAC4 was found in CD4+ T cells in PB and intestinal mucosa tissues from IBD patients. In addition, there was a great reduction in HDAC4 and a dramatic enhancement in Th17 cell specific transcription factor (RORC) and inflammatory cytokines (IL-17A, IL-6 and TNF-α) after overexpression miR-22, which was opposite to the effect of inhibition of miR-22. Furthermore, administration of antisense miR-22 in TNBS-induced mouse colitis model significantly decreased numbers of interleukin (IL)-17A+ CD4+ T cells and the expressions of IL-17A, RORC, IL-6 and TNF-α.

Conclusion: MiR-22 was up-regulated in CD4+ T cells in PB and intestinal mucosa tissues of IBD patients, which could promote Th17 cell differentiation via targeting HDAC4 to be involved in IBD progression.