Matrix metalloproteinase-2 and -9 activity levels increase in cutaneous lupus erythematosus lesions and correlate with disease severity

Lupus erythematosus is a chronic autoimmune disease characterized by remissions and exacerbations. Accumulated evidence indicated that matrix metalloproteinases (MMPs) are upregulated in inflammatory cells of cutaneous lupus erythematosus (CLE); however, the activity levels of these proteases have remained uncharacterized. To elucidate the significance of MMP-2, MMP-9, and TIMP-1 in CLE pathogenesis, gelatin zymography was used to investigate pro and active levels of MMP-2 and MMP-9 in lesional and perilesional skin biopsies obtained from twenty-two CLE patients. TIMP-1 protein levels were detected by ELISA in the biopsy specimens. The correlation between biochemical parameters and clinical characteristics of the disease was also evaluated. Significantly higher levels of active MMP-2, active MMP-9, proMMP-9, active/proMMP-2, and TIMP-1 were detected in lesional skin samples. Besides, the active/proMMP-9 was elevated in female and smoking patients. Active MMP-9 levels and active/proMMP-9 were also increased in elderly patients. Active MMP-9 levels were lower in patients who had smaller total damage score. Consistently, active/proMMP-9 and active/proMMP-2 were positively correlated with CLASI. Interestingly, in hydroxychloroquine or topical corticosteroid-treated patients, MMP-2/-9 activity levels were found to be higher compared to untreated patients. These findings suggest that increased MMP-2 and MMP-9 activities may contribute to the pathogenesis of CLE and cutaneous disease severity.