Local delivery of T-bet shRNA reduces inflammation in collagen II-induced arthritis via downregulation of IFN-γ and IL-17.

Th1 and Th17 cells are involved in the pathogenesis of rheumatoid arthritis (RA). T-bet, a Th1-specific transcription factor, appears to drive the maturation of Th1 and IFN-γ secretion. In the present study, we established the T-bet shRNA recombinant plasmid (p-T-shRNA) and explored its possible anti-inflammatory effect in a collagen-induced arthritis (CIA) model by local injection of plasmid vectors. For the initiation of CIA, DBA/1J mice were immunized with type II collagen (CII) in Freund's adjuvant and the CII-immunized mice were treated with p-T-shRNA. Levels of T-bet, IFN-γ, IL-17 and RORγt mRNA in splenocytes and synovial joints were measured by quantitative real-time PCR and T-bet expression in joint tissue was detected by immunohistochemistry staining. The intracellular IFN-γ and IL-17 were analyzed by flow cytometry (FCM). The results demonstrated that therapeutic administration on the local joints with p-T-shRNA significantly suppressed IFN-γ and IL-17 gene expression and improved the pathogenesis of arthritis in CIA mice, while administration of a plasmid expressing T-bet (pIRES-T-bet) accelerated the disease onset. Our study suggests that T-bet may be developed as a potential target for arthritis therapy.