FOXO1 and arthritic joint disease: To check if the inhibitory effect of ATO on the VEGF module is partially due to the effect of ATO on circHIPK3, and to verify the anti-circHIPK3/miR-149-5p/FOXO1/VEGF effect of ATO could be replicated in vivo, the collagen II–induced arthritis (CIA) model was established, and AAV-sh-circHIPK3 or AAV-sh-CMV-EGFP viral vectors as a control were intra-articularly administered to CIA mice on the seventh day after first (primary) immunization.