Pro-inflammatory cytokines are modified during the multiplication of Trypanosoma cruzi within the placental chorionic villi and are associated with the level of infection via the signaling pathway NF-κB.

Abstract

Congenital Trypanosoma cruzi (T. cruzi) infection has been associated with changes in the levels of TNF-α and IFN-γ during the pregnancy. Therefore, we propose to study the participation and dynamics of proinflammatory cytokines in the infection process of placental explants infected by T. cruzi in vitro. Chorionic villous explants (CVE) obtained of human term placentas (n=8) from normal pregnancies were cultured with 105 trypomastigotes/mL of Tulahuen strain DTU VI for 0, 2, 4, 16, 24, 48 and 72h. Explants were treated with sulfasalazine (SULF) (5mM) and N-acetyl-cysteine (NAC) (15mM), as inhibitors molecules of NF-κB pathway, or LPS (1μg/mL) for 24 and 72h p.i. Motile trypomastigotes were counted in culture supernatants. Immunohistochemistry and ELISA for TNF-α, IFN-γ, IL-1β, IL-4, and IL-10 were performed in CVE and culture supernatants respectively. The parasite load was measured by RT-qPCR. T. cruzi invades the chorionic villi from 4h p.i. increasing significantly its DNA at 48 and 72h p.i. of culture (parasite multiplication phase). They were detected in stromal cells, which was related to elevation of TNF-α, IL-1β, IFN-γ, and IL-10. The inhibition of NF-κB activity in the explants decreased the production of the analyzed cytokines, showing elevated levels of T. cruzi DNA during the multiplication phase of the parasite. Placental tissue modifies the secretion of pro-inflammatory cytokines during the phase of parasite multiplication, but not during the invasion phase, which in turns modifies the level of infection via the signaling pathway NF-κB.