Antibodies against Trypanosoma cruzi ribosomal P proteins induce apoptosis on HL-1 cardiac cells

LEVY G; GOMEZ KARINA A; LEVIN MJ

Mar del Plata, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigacion Bioquimica (SAIB=.; 2007

Sociedad Argentina de Bioquímica (SAIB)

Objectives: The aim of this work was to analyze the long-term stimulation effect induced by antibodies (Ab) directed to the C-terminal regions of Trypanosoma cruzi ribosomal P2b protein, defined by the epitope R13, in cardiac cells. Methods: Cardiac HL-1 cells were treated with A) mAb anti-R13, named 17.2; B) an irrelevant mAb, named 40.14; and C) IgG from patients with chronic Chagas Heart Disease (cChHD). Cell apoptosis was evaluated with annexin-V-FITC and Propidium Iodide (PI) staining by flow cytometry, terminal deoxynucleotidyl transferase-mediated UTP end labeling assay (TUNEL) and Bax/BclXl mRNA levels by Quantitative Real-Time PCR. Results: mAb 17.2 induced an increase of phosphatidylserine translocation to the outer layer of HL-1 cells together with DNA fragmentation and an augmentation in Bax/BclXl ratio. mAb 40.14 did not. The late apoptosis induced by mAb 17.2 was abolished after preincubation with b1-adrenergic receptor (b1-AR) antagonist, propranolol. IgG fractions with an exclusive b1-AR stimulating activity induced apoptosis, but IgG fractions with both b1-AR and muscarinic receptor stimulating effects only induced apoptosis when cells were incubated with atropine. Conclusions: These results support the hypothesis that Ab against the C-terminal end of TcP2b may contribute to the cardiac damage observed in patients with cChHD through long lasting stimulation of b1-AR.