Tissue Changes in Experimental Cryptococcosis in Immunocompetent and Immunodeficient Murine Model

Abstract

Cryptococcosis is a subacute or chronic disease caused through the inhalation of infectious particles from the opportunistic yeast Cryptococcus neoformans spp. The objective of the present study was to evaluate cryptococcosis in a murine model Immunocompetent (BALB/c), as well as in a model with combined immunodeficiency (SCID) through histopathological analyzes of pulmonary and cerebral tissues. After intravenous inoculation with 3.0 × 105 viable yeast cells the animals were euthanized daily for evaluation. The study period was 15 days. There were no significant changes in lung tissue in immunocompetent murine model (BALB/c). While in brain tissue, it was observed: congested vessel, evolving when C. neoformans was visualized in the meningeal area, and a large area of ischemia, which evolved throughout the studied period culminating on the 15th day of inoculation with visualization of the yeast in the meningeal and parenchyma. In SCID model, twenty-four hours after inoculation were observed in the lung tissue, hemorrhagic areas and a discrete neutrophilic inflammatory infiltrate, presence of discrete congestion in the lung, diffuse hemorrhage, edema and intense quantity of yeast were observed on the wall of the capillary at 11 days after inoculation. In brain tissue discrete area necrosis liquefaction was observed, focal well as the presence of C. neoformans, interspersed with fragments of necrotic cells was observed. On day 11 after inoculation were large areas of liquefaction necrosis associated with the formation of cavities in the parenchyma and an intense quantify of the yeast. Histopathological examination is one of the techniques usually used in the definitive diagnosis of cryptococcosis.