HMGB1 and rheumatoid arthritis: Previous reports indicate that HMGB1 can interact with IL-1β through formation of complexes with enhanced stimulatory capacity [17,18], which is of interest regarding arthritis pathogenesis as both IL-1α and IL-1β are abundant proinflammatory cytokines in the RA arthritic joint and they have also been detected in OA joints [38,39].