Avaliação da resposta TH17 em pacientes portadores de Hanseníase

Abstract

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, with a broad clinical spectrum, which affects the skin and nerves. Only 5% of infected individuals will develop the disease. Patients present with various clinical forms directly associated with the immune response, where individuals that have the tuberculoid pole, presents a vigorous cell-mediated response, with predominant Th1 cytokines profile, resulting in bacillary containment and individuals that have the lepromatous pole, presents humoral immune response with production of Th2 cytokines, which cause bacillary spread. Although they are described Th1 and Th2 responses in leprosy, various aspects of immunology of this disease have yet to be elucidated. Interleukin 17 (IL-17) is a cytokine capable of producing inflammation, indizindo quimicinas (CXCL8) and colony-stimulating factor granulocyte (G-CSG), with subsequent increase of neutrophils to the infection site. Plays an important role in the pathological development of autoimmune diseases and infection by extracellular pathogens, when produced by T helper lymphocytes. In intracellular infections, as is the case of mycobacteria, IL-17 acts in the defense early in the infection, being produced by cells of the innate system, such as lymphocytes Tδγ. This type of immune response has not been studied in leprosy and the aim to investigate the response pattern of IL-17 in leprosy patients was collected from peripheral blood to evaluate the levels of IL-17, IL-23 and IL-6 in serum by ELISA. We also analyzed the expression of genes for IL-17, IL-23 and IL-6 in biopsies of skin lesions by polymerase chain reaction quantitative (qPCR). This study aimed to evaluate the IL-17 and related cytokines response and compare the pattern of response observed among patients of the tuberculoid pole, lepromatous and healthy subjects. The results showed no detection of IL- 17 and IL-23 in peripheral blood in as many patients as in controls, but IL-6 was increased in lepromatous patients. When evaluated the expression of these cytokines in biopsy lesions of leprosy patients, all clinical forms showed low expression of IL-17, IL23 and IL-6 compared to healthy subjects. Moreover, negative correlation was demonstrated expression of IL-17 and IL-23 with the bacterial index. This absence of IL-17 in patients may be a constitutive feature of leprosy genetic or circumstantial event induced by a local presence of the pathogen, as an escape mechanism.