title: Disruption of myofibrillar proteins in cardiac muscle of Calomys callosus chronically infected with Trypanosoma cruzi and treated with immunosuppressive agent.
abstract: Calomys callosus (Rodentia: Cricetidae) chronically infected with CL strain of Trypanosoma cruzi undergo recrudescence of the acute phase when treated with the immunosuppressor cyclophosphamide. The distribution of cytoskeletal proteins in cardiac tissue of immunosuppressed animals was mapped by immunofluorescence and electron microscopy to evaluate myofibrillar distribution during the intracellular life cycle of T. cruzi. Cardiac muscle sections showed enhancement of myocarditis and parasite proliferation after immunosuppression. Immunofluorescence using monoclonal antibodies against myosin, actin, desmin, titin, tropomyosin, and troponin T demonstrated disruption and loss of contractile proteins, such as myosin and actin. Desmin and titin were irregularly distributed in close proximity to parasite nests. Ultrastructural observations confirmed alterations of cardiac cells with Z-line fragmentation, indistinguishable I-bands and A-bands, and loss of myofibrillar elements. The disruption of the muscle cell architecture was greater as infection progressed, probably as a result of increased myocarditis and physical displacement due to the activity of flagellated parasites.
authors.affiliation: Seção de Microscopia Eletrônica, Instituto Adolfo Lutz, Av. Dr. Arnaldo 355, 01246-902 São Paulo, SP, Brazil.
authors.forename: Noemi N
authors.initials: NN
authors.lastname: Taniwaki
authors.forename: Walter K
authors.initials: WK
authors.lastname: Andreoli
authors.forename: Kátia S
authors.initials: KS
authors.lastname: Calabrese
authors.forename: Solange
authors.initials: S
authors.lastname: da Silva
authors.forename: Renato A
authors.initials: RA
authors.lastname: Mortara
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D003411:Arvicolinae / Q000469:parasitology*; D002352:Carrier Proteins / Q000378:metabolism / Q000648:ultrastructure; D002598:Chagas Cardiomyopathy / Q000188:drug therapy* / Q000469:parasitology / Q000473:pathology; D002908:Chronic Disease; D003520:Cyclophosphamide / Q000627:therapeutic use*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology; D009206:Myocardium / Q000737:chemistry / Q000473:pathology*; D012376:Rodent Diseases / Q000188:drug therapy / Q000469:parasitology / Q000473:pathology; D014349:Trypanosoma cruzi / Q000472:pathogenicity*; D000099163:Myosin Binding Protein C
chemical_list: D002352:Carrier Proteins; D003520:Cyclophosphamide; D007166:Immunosuppressive Agents; D000099163:Myosin Binding Protein C