Fig. 2. High-salt diet aggravates inflammatory arthritis in CIA mice. (A) Time schedule for salt ingestion in CIA mice. Salt-containing water and chow were started 1 week before and at the time of CII immunization, respectively. (B) Mean arthritis scores in wild-type mice (WT), CIA mice (CIA), and CIA mice fed a high-salt diet (CIA+NaCl). Arthritis of each paw was scored from 0 (no swelling) to 4 (erythema and severe swelling encompassing the ankle and foot). The arthritis score is the sum of the scores for the four paws. Data represent the mean arthritis score±SEM. ^*p<0.05. (C) Representative photographs of hind paws in control mice and CIA mice fed a high-salt diet. The hind paws of WT, CIA, and CIA+NaCl showed a different degree of swelling at day 58 after primary CII immunization. (D) Histological analysis of tarsal joints in control mice and CIA mice fed a high-salt diet. The tissue sections obtained at 58 days were stained with hematoxylin and eosin (H&E), Safranin O, and toluidine blue. The magnifications are indicated in the right bottom corner. (E) The mean histological score of the tarsal joints in each group. Inflammation and joint destruction were scored on a scale of 0–3 by three independent examiners. The data represent the mean histological score±SEM. ^‡p<0.001.