Immunoexpression of canonical Wnt and NF-κB signaling pathways in the temporomandibular joint of arthritic rats

Abstract

To investigate the participation of canonical Wnt and NF-κB signaling pathways in an experimental model of chronic arthritis induced by methylated bovine serum albumin (mBSA) in rat temporomandibular joint (TMJ). Wistar rats were sensitized by mBSA+Complete Freund Adjuvant (CFA)/Incomplete Freund Adjuvant (IFA) on the first 14days (1×/week). Subsequently, they received 1, 2 or 3 mBSA or saline solution injections into the TMJ (1×/week). Hypernociceptive threshold was assessed during the whole experimental period. 24h after the mBSA injections, the TMJs were removed for histopathological and immunohistochemical analyses for TNF-α, IL-1β, NF-κB, RANKL, Wnt-10b, β-catenin and DKK1. The nociceptive threshold was significantly reduced after mBSA injections. An inflammatory infiltrate and thickening of the synovial membrane were observed only after mBSA booster injections. Immunolabeling of TNF-α, IL-1β and Wnt-10b was increased in the synovial membrane in arthritic groups. The immunoexpression of nuclear β-catenin was significantly higher only in the group that received 2 booster TMJ injections. However, NF-κB, RANKL and DKK1 immunoexpression were increased only in animals with 3 mBSA intra-articular injections. Our results suggest that canonical Wnt and NF-κB signaling pathways participate in the hypernociception and inflammatory response in TMJ synovial membrane during the development of rheumatoid arthritis in rats.