Functional role of PPAR-γ on the proliferation and migration of fibroblast-like synoviocytes in rheumatoid arthritis

Peroxisome proliferator-activated receptor (PPAR)-γ is involved in both normal physiological processes and pathology of various diseases. The purpose of this study was to explore the function and underlying mechanisms of PPAR-γ in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs) proliferation and migration. In the present study, we found PPAR-γ expression was remarkably reduced in RA synovium patient compare with OA and normal, as well as it was low-expression in Adjuvant-induced arthritis (AA). Moreover, inhibition PPAR-γ expression by T0070907 (12.5 μM) or PPAR-γ siRNA could promote FLSs proliferation and expressions of c-Myc, Cyclin D1, MMP-1, and MMP-9 in AA FLSs, except for TIPM-1. These date indicate that up-regulation of PPAR-γ may play a critical role in RA FLSs. Interestingly, co-incubation FLSs with Pioditazone (25 μM) and over expression vector with pEGFP-N1-PPAR-γ reduced proliferation and expressions of c-Myc, Cyclin D1, MMP-1, and MMP-9 in AA FLSs, besides TIMP-1. Further study indicates that PPAR-γ may induce activation Wnt/β-catenin signaling. In short, these results indicate that PPAR-γ may play a pivotal role during FLSs activation and activation of Wnt/β-catenin signaling pathway.