In the animal model of collagen‐induced arthritis, administration of PGE2 analogue, misoprostol, exacerbated joint inflammation, and this was associated with increased mRNA levels of IL‐23 p19 and other pro‐inflammatory cytokines such as IL‐17, IL‐6 and IL‐1β (Sheibanie et al., 2007a). This evidence concerns the gene IL6 and Arthritis.