Functional antibodies against G-protein coupled receptors in Beagle dogs infected with two different strains of Trypanosoma cruzi.

Abstract

The interaction of the anti-beta1-adrenergic receptor autoantibodies (b1ARAb) and the anti-muscarinic M2 receptor autoantibodies (M2RAb) with cardiac neurotransmitter receptors were identified in human chronic Chagas cardiomyopathy (CCC) related to the ECG and dysautonomia disturbances. Dogs are considered gold model to the study of Trypanosoma cruzi infection

due the clinical similarities with CCC. This study aims to evaluate whether anti- b1ARAb, anti-b2ARAb, and anti-muscarinic M2RAb are generated in Beagle

dogs infected by T. cruzi using Y and Berenice-78 strains of T. cruzi. Animals were infected with 4.0 x 103 bloodstream trypomastigotes/kg of body weight and, after 25 months of infection, blood sample was collected, and serum stored at -80°C. Dog serum was treated by ammonium sulphate precipitation and the IgG antibodies isolated and added to the beating neonatal rats’ cardiomyocytes. All T. cruzi-infected dogs developed agonistic b1ARAb, b2ARAb, and M2RAb. Animals infected by Berenice strain presented less b2ARAb and M2RAb activities than dogs infected by Y strain of the parasite. In cardiomyocytes culture, the antibodies recognized an epitope on the second extracellular loop of the receptors which were similar to findings in

human Chagas disease. There was no detection of antibody against G protein- coupled receptor in serum from uninfected dogs. In conclusion, both Y and

Berenice-78 strains of T. cruzi induced dog antibodies, whose targets located in the second extracellular loop of the adrenergic and muscarinic receptors were similar to those observed in individuals with CCC. Therefore, our findings highlight dogs as a promisor model to investigate pathogenic roles of functional Ab against G-protein coupled receptors.