LPS-mediated activation of TLR4 controls Toxoplasma gondii growth in human trophoblast cell (BeWo) and human villous explants in a dependent-manner of TRIF, MyD88, NF-κB and cytokines.

We evaluated the influence of the Toll-like receptor (TLR)-4 pathways on BeWo, JEG-3 and HTR-8/SVneo cells, as well as in human villous explants infected with Toxoplasma gondii. Cells and explants were stimulated with LPS for 24 or 48 h and processed for the MTT assay, and expression of TLR4 was evaluated by confocal microscopy. In addition, we used peptides that inhibit MyD88 or TRIF, and inhibitor to NF-κB. Finally, the parasite proliferation was verified, and ELISA was performed to verify the cytokine production. As results, LPS did not induce toxicity in cells and explants. However, LPS triggered a reduction in T. gondii proliferation only in BeWo cells and explants. Additionally, LPS downmodulated IL-10, TGF-β1 and TNF, but upregulated IFN-γ in BeWo cells. For explants, LPS induced high levels of IL-10, TGF-β1 and IFN-γ. Finally, it was observed that the inhibition of TRIF and NF-κB increased parasitism and modulated TGF-β1 in BeWo cells, while the inhibition of MyD88 and NF-κB increased T. gondii infection and modulated IFN-γ in explants. It can be concluded that the TLR4 pathway is important for the control of T. gondii replication in BeWo cells and villous explants, in a dependent-manner of TRIF, MyD88, NF-κB and cytokines.