The effect of hydroxychloroquine on lupus erythematosus-like skin lesions in MRL/lpr mice

<i>Objectives</i>: To evaluate the effect and safety of hydroxychloroquine (HCQ) on lupus erythematosus (LE)-like skin lesions in the MRL/lpr mouse, a model for systemic LE (SLE). <i>Methods</i>: We divided the MRL/lpr mice into three groups that were given: (1) drinking water, (2) HCQ at a dose of 4 mg/kg/d, or (3) HCQ at a dose of 40 mg/kg/d. The HCQ was administered to examine the effect and safety of HCQ on skin lesions and the number of infiltrating cells including mast cells in the dermis. <i>Results</i>: Six of 13 mice in the group given drinking water, 3 of 11 mice in the group administered low-dose HCQ (4 mg/kg/d), and 1 of 10 mice in the group administered high-dose HCQ (40 mg/kg/d) presented the skin lesions. The average number of mast cells was 81, 50, and 12 (magnification, ×100), the mortality rate was 24%, 8%, and 9% and the mean body weight gain was 4.6 g, 8.0 g and 5.1 g, respectively. <i>Conclusions</i>: HCQ was demonstrated to decrease the appearance of LE-like lesions and the number of mast cells in the dermis. Furthermore, there were no obvious systemic adverse effects. This study provides evidence that suggests benefits in human patients.