Collagen-induced arthritis (CIA) model
Nine-week-old male DBA/1 mice purchased from Vital River Laboratory Animal Technology (Beijing, China) were raised in accordance with institutional guidelines and with the approval of the Institutional Animal Care and Use Committee of Shandong First Medical University & Shandong Academy of Medical Sciences. CIA models were constructed and established as described before (Song, Feng, Zhao, Lu, & Han, 2019). Mice immunized with CII were randomly divided into 4 groups (n=6 mice for each group and time point) and administered AZM or Vehicle at the indicated doses twice a day after the initial immunization. In the therapeutic treatment study, when arthritis score reached 6, mice were randomly enrolled into groups. AZM, ETC or Vehicle (6 mice per group) were administered i.p. to mice, twice a day from the day of enrollment. Progression of arthritis was monitored continuously after the first immunization by assessing arthritis score (the sum of scores on a 0–4 scale for all 4 limbs, based on the swelling of the limbs, for a total possible score of 16 for each mouse), using methods as described before. The arthritis score for each mouse was defined as the sum of the scores of all four paws. In each category, joints were independently evaluated in a blinded manner. In addition, the thickness of the arthritic hind paws was measured daily with microcalipers.