Avaliação funcional de Toll-Like Receptor 4 (TLR4) em células trofoblásticas humanas vilosa/extravilosa e em vilos placentários humanos de terceiro trimestre gestacional infectados por Toxoplasma gondii

Abstract

Toll-like receptors (TLRs) are receptors that are located on the cell surface or in cell compartments. The objective of this work was to evaluate the influence of the Toll-like receptor 4 (TLR4) pathway on trophoblastic cells, BeWo, JEG-3 and HTR-8/SVneo and on explants of chorionic human villi infected or not with Toxoplasma gondii. BeWo cells infected and treated with LPS, regardless of treatment time, showed a decrease in total parasitism. However, in JEG-3 and HTR8/SVneo cells, there was increased proliferation of the parasite or no significant change in parasitic intracellular growth. In explants of human chorionic villi there was a reduction of total parasitism under the conditions in which the TLR4 pathway was activated for 48 hours by LPS. Starting from cytokine profile analysis, it was observed that, in infected and untreated BeWo cells, there was an increase in IL-10 and a decrease in IFN-γ. However, when treated with LPS, there was an increase in the IFN-γ and reduction of TGF-β1, IL-10 and TNF. In JEG-3 cells, there was an increase in the production of TGF-β1, TNF and IFN-γ, but increased IL-10 after 24 hours and a decrease after 48 hours of LPS treatment. In HTR-8/SVneo, the LPS treatment promoted an increase in the production of IFN-γ, and a decrease in the production of TGF-β1, MIF and TNF. In human chorionic villi, LPS induced IFN-γ and TGF-β1, but reduced the production of TNF, IL-10, MIF and IL-8. It was observed that the inhibition of MyD88 further reduced parasitism in BeWo, however the inhibition of TRIF increased the growth of T. gondii in BeWo, while no significant effect was observed in the other cells. Finally, the inhibition of MyD88 and TRIF increased T. gondii infection in the chorionic villi. It can be concluded that the TLR4 pathway is important for the control of T. gondii replication in the villi and BeWo cells, since inhibition of MyD88 and/or TRIF reversed the activation of TLR4 by LPS, which was not observed in JEG-3 and HTR8/SVneo. This may mean that chorionic villi and transformed cells behave differently in their immune response to Toxoplasma infection.