Expression of Smad 2 and 3 on the lesions of leprosy

Abstract

Background: Leprosy is an infections disease with two polar forms, tuberculoid leprosy (TT) and lepromatous leprosy (LL), that are characterized by strong cell-mediated immunity (CMI) and CMI anergy, respectively. Transforming growth factor-β (TGF-β) is a family of growth factors involved in essential physiological processes, including development, differentiation, tissue repair, cell growth control and inflammation. Cellular signaling by TGF-β family members is initiated by the assembly of specific cell surface receptors that activate transcription factors of the Smad family. Deregulation of the TGF-β-Smad signaling pathway has been implicated in developmental disorders and several human diseases. Recently, ELISA & immunohistochemistry revealed high expression of TGF-β isoforms in LL. Objective: The purpose of this study was to investigate TGF-β-Smad signaling in various forms of leprosy. Methods: We investigated the involvement of TGF-β by immunohistochemical staining for Smad 2 and 3 in skin biopsies from six patients of BL and four patients of TT. Results: The inflammatory cells, keratinocytes and fibroblasts in BL showed strong positivity for both Smad 2 and 3, whereas those in TT showed little positivity. Conclusion: The high expression of Smad 2/3 in BL could represent high expression of TGF-β, which possibly contributes to local CMI anergy and other clinical characteristic features of leprosy.