CRP and rheumatoid arthritis: Previous studies have demonstrated that AHR signaling activation significantly alleviated progression of rheumatoid arthritis (RA) through repressing C-reactive protein (CRP), NLR family pyrin domain containing 3 (NLRP3), tumor necrosis factor-alpha (TNF-α), and IL-6 expression (Jin et al., 2011; Huai et al., 2014; Liang et al., 2019; Piper et al., 2019), and enhancing nuclear factor erythroid 2-related factor 2 (NRF2) and IL-10 expression in B cells, macrophages, or hepatocytes (Tsuji et al., 2012; Piper et al., 2019; Rosser et al., 2020).