AIF1 and rheumatoid arthritis: Spinal microgliosis (IBA1 immunopositive cells that also express p‐p38) in the dorsal horn correlated with decrease in grip force strength and increase in mechanical hypersensitivity in models of OA and rheumatoid arthritis, respectively (Lee et al., 2011; Clark et al., 2012; Nieto et al., 2016).