Interleukin‐17, oxidative stress,and inflammation: role of melatonin during Trypanosoma cruzi infection

Although the exact etiology of Chagas' disease remains unknown, the inflammatory process and oxidative stress are believed to be the main contributors to the dysfunction and pathogenesis during chronic Trypanosoma cruzi infection. Our hypothesis is that melatonin administered for 2 months daily could modulate the oxidative stress and the inflammatory response during the chronic infection. Flow cytometric analysis of macrophages and antigen‐presenting cells (APC), expression of RT1B as well as LFA‐1 and MCP‐1 in CD4⁺ and CD8⁺T cells and levels of interleukin‐17A were assessed. The oxidative stress was evaluated through lipid peroxidation (LPO) analysis on the plasma of thiobarbituric acid‐reactive substances (TBARS) and nitric oxide production. Decreased concentrations of nitrite and TBARS were found in infected and melatonin‐treated animals, as well as a rising trend in the production of IL‐17A as compared to infected and untreated counterparts. A significant decrease was found in the percentages of CD4⁺ and CD8⁺T lymphocytes MCP‐1 producers for infected and melatonin‐treated rats. Reduced percentage of CD8⁺T cells producing LFA‐1 was observed in control and melatonin‐treated animals as compared to untreated rats. The cellular response of peritoneal APC cells and macrophages significantly dropped in infected and treated animals. As an endpoint, the use of antioxidant compounds such as melatonin emerges as a new and promising approach to control the oxidative stress during the chronic Chagas' disease partially mediated through the abrogation of LPO and the prevention of the inflammatory response and can be used for further investigation on treatment trials for other infectious diseases.