title: Syrian hamster infected with Leishmania infantum: a new experimental model for inflammatory myopathies.
abstract: Idiopathic inflammatory myopathies (IIMs) are inflammatory disorders of unknown origin. On the basis of clinical, histopathological, and immunological features, they can be differentiated into three major and distinct subsets: dermatomyositis; polymyositis; and inclusion-body myositis. Although a few animal models for IIM are currently available, they lack several characteristic aspects of IIMs. The aim of our study was to examine skeletal muscle involvement in an experimental animal model of visceral leishmaniasis, a disseminated infection caused by the protozoan parasite Leishmania infantum, and to compare features of associated inflammation with those of human IIM. Syrian hamsters infected intraperitoneally with amastigotes of L. infantum were killed at 3 or 4 months post-infection, and the skeletal muscles were studied. Focal inflammation was predominantly observed in the endomysium and, to a lesser extent, in perivascular areas. Degenerating muscle fibers were also found, as well as myonecrosis. Immunofluorescence with confocal laser scanning microscopy was used to characterize the phenotype of inflammatory infiltrates and the distribution of MHC class I and II in muscle biopsies. The infiltrating inflammatory cells consisted mainly of T cells, and CD8(+) T cells were found in non-necrotic muscle fibers that expressed MHC class I on the sarcolemma. In addition to T cells, several macrophages were present. The model we are proposing closely resembles polymyositis and may be useful in studying certain aspects of this disease such as the role of T cells in muscle inflammation and myocytotoxicity, while also providing novel therapeutic targets.
authors.affiliation: Department of Pathology and Animal Health, University of Naples Federico II, Via Delpino 1, 80137 Naples, Italy. paciello@unina.it
authors.forename: Orlando
authors.initials: O
authors.lastname: Paciello
authors.forename: Slawomir
authors.initials: S
authors.lastname: Wojcik
authors.forename: Luigi
authors.initials: L
authors.lastname: Gradoni
authors.forename: Gaetano
authors.initials: G
authors.lastname: Oliva
authors.forename: Francesca
authors.initials: F
authors.lastname: Trapani
authors.forename: Valentina
authors.initials: V
authors.lastname: Iovane
authors.forename: Luisa
authors.initials: L
authors.lastname: Politano
authors.forename: Serenella
authors.initials: S
authors.lastname: Papparella
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D006224:Cricetinae; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D007249:Inflammation / Q000276:immunology / Q000469:parasitology / Q000473:pathology*; D018314:Leishmania infantum; D007898:Leishmaniasis, Visceral / Q000276:immunology / Q000473:pathology*; D008285:Major Histocompatibility Complex / Q000276:immunology; D008647:Mesocricetus; D018613:Microscopy, Confocal; D018482:Muscle, Skeletal / Q000276:immunology / Q000469:parasitology / Q000473:pathology*; D009220:Myositis / Q000276:immunology / Q000469:parasitology / Q000473:pathology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D015703:Antigens, CD