Participação de quinase regulada por sinais extracelulares (ERK)-1/2 e IL-6 na susceptibilidade de diferentes populações de células trofoblásticas humanas à infecção por Toxoplasma gondii

Abstract

During initial placentation, cytotrophoblast cells proliferate and differentiate by cellular fusion to form a multinucleated layer, the syncytiotrophoblast, and also form the extravilous trophoblast that invades the uterine mucosa, an essential phenomenon for successful gestation. In the course of gestation, infection caused by Toxoplasma gondii can trigger serious manifestations and potentially affect fetal development. . Differences in the susceptibility of trophoblastic cells to T. gondii infection should be evaluated to support the establishment of new therapeutic approaches capable of interfering in the control of fetal infection without compromising the success of pregnancy. This study aimed to evaluate the susceptibility of cytotrophoblast, syncytiotrophoblast and extravillous trophoblast cells to T. gondii infection and possible mechanisms involved in this process. BeWo line cells were used as model of cytotrophoblast (before syncytialization process) and syncytiotrophoblast cells (after syncytialization process by using forskolin and PMA), whereas human HTR-8/SVneo cells served as model of extravillous trophoblast cells, according to previous studies. Cells were cultured in coverslips into 6-well plates and infected by T. gondii tachyzoites (RH strain) for additional 24 hours. In parallel, the three cell types were treated with extracellular signals regulated kinases (ERK) 1/2 inhibitor (PD98059) for 3 hours and infected by T. gondii for additional 24 hours. The supernatants were collected to measure cytokine profile, and the cells analyzed for infection index, total number of parasites and mitogen activated protein kinases (MAPKs) phosphorylation. HTR-8/SVneo cells showed the highest susceptibility to T. gondii infection when compared to syncytiotrophoblast and cytotrophoblast cells, whereas syncytiotrophoblast was the cell type more resistant to the parasite infection. In addition, cytotrophoblast and syncytiotrophoblast cells produced significantly more IL-6 than HTR-8/SVneo cells. On the other hand, HTR-8/SVneo cells showed higher ERK1/2 phosphorylation than cytotrophoblast and syncytiotrophoblast cells. ERK1/2 inhibition reduced T. gondii infection and increased IL-6 production in HTR-8/SVneo cells. Thus, it is possible to suggest that HTR-8/SVneo cells are more susceptible to T. gondii infection likely because these cells presented higher ERK1/2 phosphorylation and lower IL-6 levels compared to other cells, suggesting that these mediators can be important to favor the parasite infection in this type of trophoblastic population.