Infecção placentária pelo Zika vírus : investigação das vias de sinalização e funções celulares afetadas

Abstract

Introduction: Zika Virus (ZIKV) infection is considered a major public health problem, due to its ability to cross the placental barrier and infect the fetus, which can cause a condition called Congenital Zika Virus Syndrome. Although the cases of ZIKV during pregnancy have drastically reduced, the infection still deserves great attention as it increases public spending in the short, medium and long term. Despite the scientific efforts made in recent years, studies on the pathogenesis of ZIKV and the immune response in the placenta are still needed. Objective: To investigate the morphological, immunological and molecular aspects associated with the pathophysiology of gestational infection by ZIKV in different experimental models in vitro. Methods: HTR-8/SVneo cells derived from the first trimester of gestation, extravillous cytotrophoblast cells (EVT) and chorionic villus explants from term placentas were infected with an African strain (MR766) and an Asian strain (PE243) of ZIKV. Infection was confirmed by flow cytometry, immunofluorescence and RT-qPCR for cells and by RT-qPCR for explants. Cells were analyzed by atomic force microscope (AFM). The immune response was observed by analyzing gene expression and cytokine production, as well as activation of specific molecular pathways. Results: Placental explants were infected only with the PE243 strain and showed increased production of IL-6 (p < 0.05) and IL-8 (p < 0.05). HTR-8/SVneo cells were infected by both strains (72.2% for MR766 and 80.2% for PE243) and showed morphological/topographic changes in infected cells, but showed no change in the gene expression or cytokine production. EVT cells were also infected with both strains (63.8% for MR766 and 66.5% for PE243), showing considerable morphological/topographic changes in cell size, shape and roughness, and showed increased production of IFN-α2 (p < 0.0005), IFN-λ1 (p < 0.01) and IL-6 (p < 0.01) after PE243 infection, and only an increase in IFN-λ1 (p <0.05) after MR766 infection. The signaling by the molecules analyzed differed only in PE243 infection, which increased the expression of p-IRF3 (p < 0.05) and IRF9 (p < 0.05), while p-STAT2 remained unchanged after infection with both the strains. Conclusions: The response to ZIKV is distinct in different cell culture models and depending on the viral strain. At the end of pregnancy, EVT cells present a different picture from other cell models, managing to produce some IFN and maintaining active antiviral response pathways, which may indicate that they are more virus-fighting than first-trimester cells.