Análises bioquímicas, biométricas, histológicas e imunológicas em ratos com nefropatia induzida pela doxorrubicina

Abstract

The nephrotic syndrome (NS) is characterized by proteinuria, hypoalbuminemia, dyslipidemia and edema. Studies have associated the NS with changes in the immune response. This study investigated the leukocyte count, the state of activation/migration by expression of CD80 and CD18 molecules in peripheral blood leukocytes and evaluated the biochemical, histological and biometric changes as well as the status redox of the renal tissue in rats with doxorubicin induced NS. Sixty-four Wistar rats, 6-8 weeks old and average weight 300 g., obtained from the Bioterism Center at Federal University of Minas Gerais, Brazil, were used in this study. The animals were divided into two groups: DOX (n=32) which received a single dose, in the tail vein of Doxorubicin hydrochloride (7.5 mg / kg) and group CON (n=32) which received saline. Animals from each groups were evaluated and sacrificed at days 7, 14, 21 and 28 after injection. A 24h-urine sample was collected in this same times and blood samples were obtained by cardiac puncture under anesthesia. After blood collection, animals were perfused with saline and the internal organs removed, weighed on semi-analytical electronic balance and kidneys fixed, paraffin-embedded and processed according to the different histological and immunohistochemical techniques employed. Total leukocyte counts were performed on automated cell counter and differential leukocyte counts by analysis of blood smears stained with May-Grunwald Giemsa. Immunophenotyping of circulating leukocytes was performed by flow cytometry using fluorochrome-conjugated monoclonal antibody. Status Redox was evaluated by TBARS production and activity of antioxidant enzymes superoxide dismutase (SOD) and catalase in renal tissue samples. Animals from DOX group developed proteinuria, dyslipidemia, biometric changes, and histological changes consistent with significant renal edema, tubule interstitial chronic inflammatory infiltrates and renal fibrosis. Also showed changes in total and differential count of leukocytes and a significant increase in expression of CD80 on monocytes and CD18 on cytotoxic T lymphocytes, NK cells and peripheral blood monocytes. There was an increase in lipid peroxidation in kidney tissue and a positive correlation with the expression of CD80 on monocytes and serum levels of creatinine. The DOX animals group showed a significant increase in cytotoxic T lymphocytes, NK cells and monocytes CD18 expression, and the CD80 expression by peripheral blood monocytes. The increased production of reactive oxygen species in renal tissue of DOX group animals was positively correlated with the CD80 expression by monocytes and serum levels of creatinine. The biochemical changes in this animal model arise early and serve as nonspecific biomarkers for NS; histological lesions become intense from day 21 after the doxorubicin injection. The phenotypic analyzes suggest that phagocytic and cytotoxic cells could be preferentially recruited from peripheral blood to the focus of injury and contribute to renal injury. The continued characterization of doxorubicin induced NS animal models may contribute to better understanding of the NS natural history. Additional studies should examine the effects of blocking the integrin and costimulatory molecules, as well as the participation of neutrophils and cytokines in the mechanism of cell activation/ migration. Must consider also The importance of renal edema in the evolution of renal injury in this animal model of NS induced by doxorubicin.