TNFRSF11A and rheumatoid arthritis: Methotrexate (MTX), which is a cornerstone drug for the treatment of RA and has a clinical effective rate of approximately 60%, mainly inhibits inflammation and plays a certain role in bone protection by regulating RANK/RANKL/osteoprotegerin (OPG) (Swierkot et al., 2015; Kanagawa et al., 2016).