Microalgae extracts modulates the immune response in Trypanosoma cruzi-infected human cells

Chagas disease (CD) is caused by the hemoflagellate protozoan Trypanosoma cruzi. The control of the infection depends of the innate and acquired immune response of host. Moreover, CD plays a significant role in the immune response, and, in this context, microalgae can be an interesting alternative due to its immunomodulatory and trypanocidal effects. This study aimed to evaluate, in vitro, immunomodulatory potentials of the aqueous extracts of Chlorella vulgaris and Tetradesmus obliquus. Both microalgae extracts (ME) were obtained by sonication, and the selectivity index (SI) was determined by assays of inhibitory concentration (IC₅₀) in T. cruzi trypomastigotes cells; as well as the cytotoxic concentrations (CC₅₀) in human peripheral mononuclear cells (PBMC). The immune response was evaluated in T. cruzi-infected PBMC using the IC₅₀ value. ME led to inhibition of T. cruzi trypomastigotes after 24 h of treatment, in which the IC₅₀ values were 112.1 µg/ml to C. vulgaris and 15.8 µg ml^-1 to T. obliquus. On the other hand, C. vulgaris did not affect the viability of PBMCs in concentrations up to 1000 µg ml^-1, while T. obliquus was non-toxic to PBMCs in concentrations up to 253.44 µg ml^-1. In addition, T. obliquus displayed a higher SI against T. cruzi (SI = 16.8), when compared with C. vulgaris (SI = 8.9). C. vulgaris decreased the levels of IFN, indicating a reduction of the inflammatory process; while T. obliquus displayed an interesting immunomodulatory effect, since discretely increased the levels of TNF and stimulated the production of the anti-inflammatory cytokine IL-10. This study confirms that ME are effective against T. cruzi trypomastigotes, and may able to control the parasitemia and preventing the progress of CD while regulating the inflammatory process.