IL6 and rheumatoid arthritis: While chronic immune activation in OA is considered low-grade relative to RA (Robinson et al., 2016), synovial explants and synovial fluid extracted from OA patients consistently demonstrate elevated levels of pro-inflammatory mediators TNF-α, IL-1β, IL-6, IL-8, IL-15, IL-17, IL-18, IL-21, PGE2, NO, and various complement components implicated in perpetuating immune activation (Blom et al., 2007; Robinson et al., 2016; Krishnasamy et al., 2018; Mora et al., 2018; Griffin and Scanzello, 2019).