Expression of Matrix Metalloproteinases (MMP-3 and MMP-9) in Skin Lesions of Leprosy Patients

Background. Leprosy is a chronic granulomatous disease, caused by Mycobacterium leprae (M. leprae), principally affecting peripheral nerves and skin. To date, the role of matrix metalloproteinases (MMPs) in different types of leprosy has not been studied, except for their role in neuropathy. Objective. to investigate the changes in expression and distribution of MMP-3 and MMP-9 in biopsies taken from cutaneous lesions of leprosy patients. Patients and Methods. Using immunohistochemistry, 24 leprosy lesional skin biopsies compared with 20 matched healthy controls biopsies were assessed for expression of MMP3 and MMP9. Patients were divided into 4 groups; group I tuberculoid (TT) and borderline tuberculoid (BT), group II borderline borderline leprosy (BB), group III borderline lepromatous (BL) and lepromatous leprosy (LL), and group IV erythema nodosum leprosum (ENL). Results. MMP-3 is increased in type 2 lepra reaction; ENL, in endothelial cells of blood vessels of vasculitic lesions and in extracellular matrix (ECM), and fibroblasts around infiltrating cells. MMP-9 expression was mainly observed in functioning macrophages; epithelioid cells of the paucibacillary (PB) tuberculoid pole of leprosy spectrum, and immunoreactivity was decreased towards the multibacillary (MB) lepromatous pole, characterized by impaired-functioning foamy histiocytes. Conclusion. MMP-3 has a possible role in vasculitis process of ENL. MMP-9 is a key marker of functioning macrophages, epithelioid granuloma formation, and potential destruction of peripheral nerves of PB leprotic patients. Natural inhibitors of MMPs do exist, and synthetic inhibitors have been developed which offer the hope of new adjuvant treatment options in leprosy. (J Egypt Women Dermatol Soc 2009; 6: 80-87)