Avaliação do perfil de citocinas séricas e óxido nítrico na hanseníase experimental murina / Evaluation of the serum cytokines profile and nitric oxide in experimental murine leprosy

Introdução: a hanseníase é uma do-ença infecciosa crônica causada pelo Mycobacterium leprae (M. leprae), um para-sita intracelular obrigatório. Assim, a resis-tência do hospedeiro a esse patógeno depen-de da imunidade celular. O uso de modelos experimentais tem permitido o estudo da hanseníase do ponto de vista imunológico, microbiológico e terapêutico, entretanto, as diferenças na progressão da infecção entre os modelos mais empregados (camundongos imunocompetentes, BALB/c, e camundongos congenitamente atímicos, nude) são pouco estudadas. Objetivo: comparar a evolução da infecção pelo M. leprae em camundongos BALB/c e nude quanto à multi-plicação bacilar e avaliação do perfil inflamatório sistêmico pela quantificação sérica de citocinas e óxido nítrico (NO). Métodos: os camundongos foram inoculados com M. leprae nos coxins plantares e avaliados aos 3, 5 e 8 meses após a infecção. Resultados: camundongos nude apresentaram multiplicação bacilar progressiva nos coxins plantares. Em camundongos BALB/c, o número de bacilos foi maior aos 5 meses. Em relação à quantificação de citocinas, nos camundongos BALB/c houve aumento de IL-2 e IL-17A e diminuição de IL-6 e NO aos 8 meses de inoculação. Nos camundongos nude, verificou-se o aumento do TNF aos 8 meses de inoculação e manutenção dos níveis de NO. Conclusão: os resultados encontrados sugerem que em camundongos BALB/c ocorre a ativação de uma resposta imune capaz de controlar a multiplicação do M. leprae, em contrapartida em camundongos nude a infecção é progressiva a despeito de altos níveis de TNF. (AU)

Introduction: leprosy is a chronic infectious disease caused by Mycobacterium leprae (M. leprae), an obligate intracellular parasite. Thus, host resistance to this pathogen depends on cellular immunity. The use of experimental models has made it possible to study leprosy from an immunological, microbiological, and therapeutic point of view. However, the differences in the progression of the infection between the most used models (immunocompetent mice, BALB/c, and congenitally athymic mice, nude) have been little studied. Objective: to compare the evolution of M. leprae infection in BALB/c and nude mice in terms of bacillary multiplication and evaluation of the systemic inflammatory profile by quantifying serum cytokines and nitric oxide (NO). Methods: the mice were inoculated with M. leprae in the footpads and evaluated at 3, 5, and 8 months after infection. Results: nude mice showed progressive bacillary multiplication in the footpads. In BALB/c mice, the number of bacilli was higher at 5 months. In terms of cytokine quantification, BALB/c mice showed an increase in IL-2 and IL-17A and a decrease in IL-6 and NO at 8 months of inoculation. In the nude mice, there was an increase in TNF at 8 months of inoculation and maintenance of NO levels. Conclusion: the results suggest that BALB/c mice activate an immune response capable of controlling the multiplication of M. leprae, whereas in nude mice the infection is progressive despite high levels of TNF. (AU)

Effect of Mycobacterium leprae on neurotrophins expression in human Schwann cells and mouse sciatic nerves

BACKGROUND Although Mycobacterium leprae (ML) is well characterised as the causative agent of leprosy, the pathophysiological mechanisms underlying peripheral nerve damage still need further understanding. In vitro and in vivo studies have yielded insights into molecular mechanisms of ML interaction with Schwann cells (SC), indicating the regulation of genes and proteins crucial to neural plasticity. OBJECTIVES We aimed to investigate the effect of ML on neurotrophins expression in human SC (hSC) and mice sciatic nerves to better understand their role in leprosy neuropathy, and aiming to contribute to future therapeutic approaches. METHODS We evaluated mRNA and protein expression of BDNF, NGF, NT-3, NT-4 in hSC from amputation nerve fragments, as well as in athymic nude mice, infected by ML for eight months. FINDINGS and MAIN CONCLUSIONS Our in vitro results showed a trend to decline in NGF and BDNF mRNA in ML-treated hSC, compared to controls. The immunodetection of BDNF and NT-4 was significantly downregulated in ML-treated hSC. Conversely, ML-infected mice demonstrated upregulation of NT-3, compared to non-infected animals. Our findings indicate that ML may be involved in neurotrophins regulation, suggesting that a pathogen-related imbalance of these growth factors may have a role in the neural impairment of leprosy.

The involvement of endothelial mediators in leprosy

Leprosy is a chronic infectious disease that requires better understanding since it continues to be a significant health problem in many parts of the world. Leprosy reactions are acute inflammatory episodes regarded as the central etiology of nerve damage in the disease. The activation of endothelium is a relevant phenomenon to be investigated in leprosy reactions. The present study evaluated the expression of endothelial factors in skin lesions and serum samples of leprosy patients. Immunohistochemical analysis of skin samples and serum measurements of VCAM-1, VEGF, tissue factor and thrombomodulin were performed in 77 leprosy patients and 12 controls. We observed significant increase of VCAM-1 circulating levels in non-reactional leprosy (p = 0.0009). The immunostaining of VEGF and tissue factor was higher in endothelium of non-reactional leprosy (p = 0.02 for both) than healthy controls. Patients with type 1 reaction presented increased thrombomodulin serum levels, compared with non-reactional leprosy (p = 0.02). In type 2 reaction, no significant modifications were observed for the endothelial factors investigated. The anti-inflammatory and antimicrobial activities of the endotfhelial factors may play key-roles in the pathogenesis of leprosy and should be enrolled in studies focusing on alternative targets to improve the management of leprosy and its reactions.