Distribuição de macrófagos e alterações teciduais no coração e na medula espinhal de cães inoculados com formas tripomastigotas metacíclicas ou sangüíneas da cepa Berenice-78 do Trypanosoma cruzi submetidos à imunossupressão durante a fase aguda da infecção

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Trypanosoma cruzi, the causative agent of Chagas disease, affects not only cardiac and intestinal structures but also neurological structures. Experimental canine model of T. cruzi infection has been shown to mimetize the various aspects of Chagas disease. Our group has been demonstrated that the source of the inoculum (blood-BT or metacyclic trypomastigotes-MT) influences the evolution of the immunological and parasitological aspects of the acute phase of T. cruzi infection in dogs. We observed at the peripheric blood a predominance of CD8+T cells in MT group. Considering the histological picture, a major characteristic of Chagas disease is a myocarditis constituted primarily of mononuclear cells, during both, acute and chronic phases of the disease. So, the aim of this study was to evaluate the histopathological aspects of the heart and spinal cord, two immunologically distinct sites, during acute phase in BT and MT T. cruzi infection associated or not to immunosuppressive therapy (azathioprine-2mg/kg/daily during 42 days) and the macrophage contribution to the inflammatory infiltrate. The dogs (120 days old) were inoculate with 2000 BT or MT/kg body weight by intraperitoneal route (Berenice-78 T. cruzi strain). Twenty four animals were divided into six experimental groups: uninfected, infected with blood trypomastigotes (BT), infected with metacyclic trypomastigotes (MT), uninfected/immunossuppressed, infected with BT and immunossupressed (BTims) and infected with MT and immunossupressed (MTims). These were observed during the acute phase of the infection and necropsied on 42 days of infection. The heart and spinal cord were collected in totum and the histopathological evaluations were performed using Hematoxylin-Eosin to observe the generally histopathological alterations, Masson Trichromic to evaluate collagen neoformation, Cresil-Violet to evaluate and quantify glial nodules (GN) and perivascular infiltrate (PI), and the immunohistochemical technique against T. cruzi and macrophages, to visualize and quantify the parasitism and macrophages respectively. Previously we observed that: 1) immunosuppressive therapies lead to higher levels of parasitemia however, no differences were observed among MTims and BTims; 2) spinal cord lesions are characterized by GN and PI with or without parasites. The heart of dogs infected with BT showed more intense acute myocarditis characterized by a focal and diffuse exudation of mononuclear cells and collagen neoformation than MT group. Dogs infected and immunossupressed showed acute myocarditis more destructive than not-immunossupressed, characterized by diffuse exudation of mononuclear cells. Parasites and macrophages were observed more frequently in immunossupressed group. ix SANTOS, V.R.L. Abstract MT group presented greater number of cells in PI and GN than BT group. On the other hand, the number of cells in GN and PI were greater in BT and MT when compared to BTims and MTims. Parasites were observed in BT, BTims and MTims. Macrophages were greater in MT than BT and in MTims than BTims. Taken together, these data suggests that MT lead a more intense response than BT and that the immunossupression during acute phase of experimental T. cruzi infection in dogs do not permitted greater parasitism or lesions in spinal cord.

ASSUNTO(S)

medula espinhal de cães inoculados trypanosoma cruzi tripomastigotas metacíclicas sangüíneas da cepa macrófagos imunologia

ACESSO AO ARTIGO

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