title: Cardiac-oxidized antigens are targets of immune recognition by antibodies and potential molecular determinants in chagas disease pathogenesis.
abstract: Trypanosoma cruzi elicits reactive oxygen species (ROS) of inflammatory and mitochondrial origin in infected hosts. In this study, we examined ROS-induced oxidative modifications in the heart and determined whether the resultant oxidized cardiac proteins are targets of immune response and of pathological significance in Chagas disease. Heart biopsies from chagasic mice, rats and human patients exhibited, when compared to those from normal controls, a substantial increase in protein 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), carbonyl, and 3-nitrotyrosine (3-NT) adducts. To evaluate whether oxidized proteins gain antigenic properties, heart homogenates or isolated cardiomyocytes were oxidized in vitro and one- or two-dimensional gel electrophoresis (2D-GE)/Western blotting (WB) was performed to investigate the proteomic oxidative changes and recognition of oxidized proteins by sera antibodies in chagasic rodents (mice, rats) and human patients. Human cardiomyocytes exhibited LD(50) sensitivity to 30 µM 4-HNE and 100 µM H(2)O(2) at 6 h and 12 h, respectively. In vitro oxidation with 4-HNE or H(2)O(2) resulted in a substantial increase in 4-HNE- and carbonyl-modified proteins that correlated with increased recognition of cardiac (cardiomyocytes) proteins by sera antibodies of chagasic rodents and human patients. 2D-GE/Western blotting followed by MALDI-TOF-MS/MS analysis to identify cardiac proteins that were oxidized and recognized by human chagasic sera yielded 82 unique proteins. We validated the 2D-GE results by enzyme-linked immunosorbent assay (ELISA) and WB and demonstrated that oxidation of recombinant titin enhanced its immunogenicity and recognition by sera antibodies from chagasic hosts (rats and humans). Treatment of infected rats with phenyl-α-tert-butyl nitrone (PBN, antioxidant) resulted in normalized immune detection of cardiac proteins associated with control of cardiac pathology and preservation of heart contractile function in chagasic rats. We conclude that ROS-induced, cardiac-oxidized antigens are targets of immune recognition by antibodies and molecular determinants for pathogenesis during Chagas disease.
authors.affiliation: Department of Microbiology and Immunology, Center for Tropical Diseases, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America.
authors.forename: Monisha
authors.initials: M
authors.lastname: Dhiman
authors.forename: Maria Paola
authors.initials: MP
authors.lastname: Zago
authors.forename: Sonia
authors.initials: S
authors.lastname: Nunez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Amoroso
authors.forename: Hugo
authors.initials: H
authors.lastname: Rementeria
authors.forename: Pierre
authors.initials: P
authors.lastname: Dousset
authors.forename: Federico
authors.initials: F
authors.lastname: Nunez Burgos
authors.forename: Nisha Jain
authors.initials: NJ
authors.lastname: Garg
mesh_terms: D000818:Animals; D000915:Antibody Affinity; D000941:Antigens / Q000276:immunology / Q000378:metabolism; D001323:Autoantibodies / Q000276:immunology*; D002598:Chagas Cardiomyopathy / Q000209:etiology / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D014355:Chagas Disease / Q000209:etiology* / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D002986:Clinical Trials as Topic; D006321:Heart / Q000469:parasitology; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D009206:Myocardium / Q000276:immunology* / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D010084:Oxidation-Reduction; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000276:immunology* / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000276:immunology
chemical_list: D000941:Antigens; D001323:Autoantibodies; D017382:Reactive Oxygen Species