S100A9 and arthropathy: That IL-6 induces S100A9 expression in colonic epithelial cells through STAT3 activation has already been reported in recent studies about acute myeloid leukemia (AML), biliary tract cancer, and psoriasis-like skin and joint disease (Böttcher et al., 2022; Mellor et al., 2022; Ware et al., 2020).