(a) Effects of in vivo administration of intraperitoneal injection of cathepsin inhibitors (Clik60, Clik148, and CA074). Each inhibitor was administered into SS model mice (n = 10 for each) at doses of 0.1 mg/mouse/day from 4 weeks to 7 weeks, and the results were analyzed at 8 weeks compared with those in untreated SS model mice (n = 7). Treatment with intraperitoneal injection of Clik60, but not treatment with Clik 148 and CA074, was effective in preventing the development of autoimmune lesions in the lacrimal, parotid, and submandibular glands of the SS model mice (*P < 0.01, **P < 0.005, Student’s t test). (b) Representative histologic features in the salivary and lacrimal glands showing preventive effects in Clik60-treated mice at 8 weeks of age. (c) The average saliva and tear volume of the SS model mice treated with Clik60 was significantly higher than that of control mice. Results are expressed as mean ± SEM in five mice examined per group (*P < 0.05, **P < 0.005, Student’s t test).