BthTX-II Limits Toxoplasma gondii Infection and Alters Lipid Droplet Accumulation and Cytokine Release in Human Trophoblasts

Congenital toxoplasmosis poses serious risks to fetal development, while limitations of current therapies reinforce the search for new antiparasitic agents. Snake venom phospholipases A2 (PLA2s) exhibit diverse biological activities. This study investigated whether BthTX-II, an Asp49 PLA2 isolated from Bothrops jararacussu venom, impairs Toxoplasma gondii infection and modulates host-cell responses. Human BeWo trophoblasts were treated with BthTX-II (0.05 - 100 µg/mL) and assessed for viability (MTT), parasite invasion and proliferation (β-galactosidase), lipid droplets (Nile Red), and reactive oxygen species (H2DCFDA). IL-6, IL-8, macrophage migration inhibitory factor (MIF), and vascular endothelial growth factor (VEGF) were quantified in culture supernatants. Antiparasitic activity was also evaluated in human third-trimester placental villous explants. BthTX-II significantly reduced intracellular parasite proliferation at all three concentrations without significantly compromising BeWo viability. Pretreatment of tachyzoites or host cells reduced invasion by approximately 20% and 10%, respectively. BthTX-II also reduced lipid droplet-associated fluorescence in infected and uninfected trophoblasts (p < 0.0001), demonstrating an effect independent of parasite presence. In infected BeWo cells, treatment increased IL-6, IL-8, and MIF levels while decreasing VEGF. H2DCFDA fluorescence was higher in infected than uninfected cells across experimental conditions, although a toxin-specific effect on ROS was not established. In placental explants, BthTX-II (1.56 µg/mL) significantly inhibited parasite proliferation (p < 0.001). Together, these findings show that BthTX-II impairs early and intracellular stages of T. gondii infection and alters the lipid-associated and immune responses of trophoblasts, supporting further investigation of its antiparasitic potential. Funding: CAPES (Finance Code 001), CNPq, and FAPEMIG.