Leishsmania (Leishmania) amazonensis infection: Muscular involvement in BALB/c and C3H.HeN mice.

Recent studies have provided some insights into Leishsmania (Leishmania) amazonensis muscular infection in dogs, although, muscular disease due to leishmaniasis has been poorly documented. The aim of our study was to evaluate involvement of Leishmania in muscular infection of two distinct mouse strains (BALB/c and C3H.He), with different genetic backgrounds. BALB/c mice, susceptible to Leishmania infection, showed, at the beginning of infection, a great number of infected macrophages among muscle fibers; however, in C3H.He resistant mice, muscle fibers were less damaged than in BALB/c mice, but some parasitized macrophages could be seen among them. A follow up of the infection showed an intense inflammatory infiltrate mainly composed of infected macrophages in BALB/c muscles and the presence of amastigotes within muscle fibers; while C3H.He mice exhibited a moderate inflammatory infiltrate among skeletal muscle fibers and an absence of amastigotes. Total destruction of muscles was observed in BALB/c mice in the late phase of infection (day 90) while C3H.He mice showed a process of muscle repair. We concluded that: (1) the muscles of BALB/c mice were more affected by leishmaniasis than those of C3/H.He mice; (2) Leishmania amastigotes are capable of infecting muscular fibers, as observed in BALB/c mice; (3) as inflammatory infiltrate is less intense in C3H.He mice these animals are capable of restoring muscular fibers.

Leishmania (Leishmania) infantum/chagasi: Histopathological aspects of the skin in naturally infected dogs in two endemic areas.

In the New World, visceral leishmaniasis (VL), which is a progressive disease and frequently fatal, is caused by Leishmania (Leishmania) infantum/chagasi. It is endemic in many regions of Brazil and occasionally occurs in non-endemic regions when dogs from an endemic area are introduced. The aim of the present study is to compare different skin infection patterns of dogs from two leishmaniasis endemic areas. A histological analysis of dogs from Campo Grande, Mato Grosso do Sul state, a region where epidemic episodes are currently taking place, showed dermic inflammatory infiltrates, composed of numerous vacuolated parasitized macrophages, few lymphocytes, plasma cells and many degranulated mast cells. In the other region of the study, São Luís, Maranhão state, the skin of dogs presented a remarkable inflammatory reaction composed mainly of plasma cells, lymphocytes and very few parasites. We concluded that there is a difference in the skin lesion patterns of dogs with leishmaniasis that is directly related to the endemic area where the animals live.

Extracellular matrix alterations in experimental murine Leishmania (L.) amazonensis infection.

Here we describe extracellular matrix alterations in footpad lesions and draining lymph nodes caused by Leishmania (L.) amazonensis in mouse strains with distinct susceptibilities to this parasite: BALB/c (susceptible), C57BL/6 (intermediate), and DBA/2 (resistant). Changes in ECM were observed mainly in BALB/c mice that, in general, presented tissue damage associated with high parasite burden. Under polarized light, Sirius Red revealed type I collagen that was predominant in the primary lesion in all strains studied at the early phase of infection, but gradually decreased and was replaced by abundant type III collagen fibres in chronic phase lesions. The presence of type III collagen seemed to provide support to inflammatory cells, mainly vacuolated and parasitized macrophages. Laminin expression was not altered during infection by L. (L.) amazonensis in any of the mouse strains studied. Furthermore, the decreased fibronectin expression, in all strains, in areas where amastigotes have been found, indicated that this decline was also not related to the genetic background.