Trypanasoma cruzi induces cellular proliferation in the trophoblastic cell line bewo

Abstract

Chagas’ disease is caused by the haemophlagelated protozoan Trypanosoma cruzi (T. cruzi), which is able to cross the placental barrier and infect both the placenta and fetus. In ex vivo infected human chorionic villi, a low concentration of parasite induces activation of the Mitogen Activated Protein Kinase (MAPK) ERK1/2 signaling pathway, which plays an important role in cellular proliferation and differentiation.

In order to determine whether the parasite is able to induce cellular proliferation in the trophoblast, BeWo cells were incubated in presence and absence of T. cruzi trypomastigotes (Y strain) (ratio parasite/BeWo cells 1:10) and in presence and absence of FBS for 2, 6, 12 and 24 hours. DNA synthesis was assayed by bromodeoxyuridine (BrdU) incorporation and determined by spectrometry and immunocytochemistry. Mitotic index was determined in DAPI stained samples and cell growth by detection of Nucleolar organizer regions (NORs) using silver staining (AgNORs). Parasites inside cells were identified by their nuclear and kinetoplast morphology. At least 500 cells were counted in each condition and analyzed using the MATLAB software; the statistical significance was analyzed by ANOVA followed by the Dunnetts post-test.

The low concentration of T. cruzi used (mimicking women with chronic Chagas disease) induces a significant increase of BrdU incorporation into DNA and in the number of mitosis and of NORs in BeWo cells.

We conclude that T. cruzi induces cell proliferation in the trophoblast; this process may form part of a “local placental antiparasite” defense mechanism.

Financed by FONDECYT Projects Nº1120230 (UK), Nº 1130189 (JM), Nº1130113 (NG), 1120579 (SH). Support of CONICYT-PBCT Anillo ACT 112 and ICM (P09-015-F), Chile is also acknowledged.