Curcumin attenuates inflammatory response in IL-1β-induced human synovial fibroblasts and collagen-induced arthritis in mouse model

Abstract

Curcumin, a major component of turmeric, has been shown to exhibit anti-oxidant and anti-inflammatory activities. The present study was performed to determine whether curcumin is efficacious against both collagen-induced arthritis (CIA) in mice and IL-1β-induced activation in fibroblast-like synoviocytes (FLSs). DBA/1 mice were immunized with bovine type II collagen (CII) and treated with curcumin every other day for 2 weeks after the initial immunization. For arthritis, we evaluated the incidence of disease and used an arthritis index based on paw thickness. In vitro proliferation of CII- or concanavalin A-induced splenic T cells was examined using IFN-γ production. Pro-inflammatory cytokines TNF-α and IL-1β were examined in the mouse ankle joint and serum IgG1 and IgG2a isotypes were analyzed. The expression levels of prostaglandin E 2 (PGE 2), cyclooxygenase-2 (COX-2), and matrix metalloproteinases (MMPs) in human FLSs were also determined. The results showed that compared with untreated CIA mice, curcumin-treated mice downregulated clinical arthritis score, the proliferation of splenic T cells, expression levels of TNF-α and IL-1β in the ankle joint, and expression levels of IgG2a in serum. Additionally, by altering nuclear factor (NF)-κB transcription activity in FLSs, curcumin inhibited PGE 2 production, COX-2 expression, and MMP secretion. These results suggest that curcumin can effectively suppress inflammatory response by inhibiting pro-inflammatory mediators and regulating humoral and cellular immune responses.