Leishmaniose Visceral Canina (LVC) natural e experimental como doença fibrosante

Abstract

The aim of this work was to confirm canine visceral leishmaniasis (CVL) as a systemic fibrotic disease. For this, an immunohistochemical and molecular quantitative study of canine liver, lungs, and kidneys tissues were carried as follow: two experimental groups consisting of five adult beagles experimentally infected with L. infantum strain MCAN BR/2002/BH401 and other five adult beagles infected with the strain MCAN/BR/2000/BH400; a positive control group consisting of twenty adult mixed breed dogs naturally infected with L. infantum, and a negative control group comprising four adult beagles negative for infection with L. infantum. Collagen deposition (fibropoiesis) was detected and quantified by Gomori ammoniacal silver´s staining where it detects reticular fibers in black. Dogs of BH401 group and the positive group showed a conspicuous and intense fibropoiesis in liver, lungs and kidneys always associated to a chronic hepatitis, interstitial chronic pneumonitis, and glomerulonephritis, respectively. Markers for myofibroblasts (mesenchymal markers) alpha‐ actin (α‐SMA) and vimentin were identified by immunohistochemistry. The cytokine transforming growth factor beta (TGF‐β) was identified by immunohistochemistry and molecular assays. The expression of α-SMA, vimentin, and TGF-β1 markers, as well as gene expression of TGF-β1, associated with high levels of collagen deposition was highest in the BH401 group, followed by the positive control group. We conclude that the fibrosis process occurs simultaneously in the liver, lungs and kidneys of naturally and experimentally infected dogs and that the MCAN BR / 2002 / BH401 strain of L. infantum would be a good choice for studying the mechanisms of fibrosis in dogs associated with the classic histological changes of CVL.