CHANGES IN THE SPLENIC EXTRACELLULAR MATRIX IN DOGS NATURALLY INFECTED WITH Leishmania (Leishmania) infantum chagasi

The aim of this study was to study the changes in the splenic extracellular matrix of dogs naturally infected with Leishmania (Leishmania) infantum chagasi and its correlation to clinical, histopathological, and parasitological aspects. Eighteen dogs were used, separated into three groups: six non-infected animals (control group) and twelve infected animals. The dogs had undefined breed and age, from the township region of São Luís-MA. Paraffined slices of the spleen were stained with Hematoxilin and Eosin (H&E); Gomori’s ammoniacal Silver, to mark reticular fibers; and the Immunohistochemistry technique of streptavidin peroxidase to detect amastigote forms of Leishmania. The morphometrical analyses were done using the KS300 program and the images analysis system Kontron Elektronic/Carl Zeiss, Germany. The results showed that there is a significant increase in the deposition of collagen fibers in the spleen, compared to control animals, showing significant differences for symptomatic and asymptomatic animals. Positive correlations were found between the presence of the parasite in the tissue and collagen deposition. Symptomatic animals showed higher collagen deposition in the spleen, which can be associated to the high parasitism found in the tissue. The results showed that there is an intense fibrogenesis in the spleen in the canine visceral leishmaniasis, thus being associated to the parasitism of the tissue and the degenerative processes of the disease.