Immunohistochemical analysis of the expression of cellular transcription factors NFκB (p65), AP-1(c-Fos and c-Jun) and JAK/STAT in leprosy

Leprosy is a disease whose clinical spectrum depends on the cytokine patterns produced during the early stages of the immune response. The main objective of this study was to describe the activation pattern of cellular transcription factors and to correlate these factors with the clinical forms of leprosy. Skin samples were obtained from 16 patients with the tuberculoid (TT) form and 14 with the lepromatous (LL) form. The histological sections were immunostained with anti-c-Fos and anti-c-Jun monoclonal antibodies for investigation of AP-1, anti-NFkB p65 for the study of NFkB, and anti-JAK2, STAT1, STAT3 and STAT4 for investigation of the JAK/STAT pathway. Cells expressing STAT1 were more frequent in the TT form than in LL lesions (p = 0.0096), in agreement with the protective immunity provided by IFN-ʏ. STAT4 was also more highly expressed in the TT form than in the LL form (p = 0.0098). This transcription factor is essential for the development of a Th1 response since it is associated with IL-12. NFkB (p65) and STAT4 expression in the TT form showed a strong and significant correlation (r = 0.7556 and p = 0.0007). A moderate and significant correlation was observed between JAK2 and STAT4 in the TT form (r = 0.6637 and p = 0.0051), with these factors responding to IL-12 in Th1 profiles. The results suggest that STAT1, JAK2 and NFkB, together with STAT4, contribute to the development of cell-mediated immunity which is able to contain the proliferation of Mycobacterium leprae.