Avaliação dos podócitos nas diferentes classes da Nefrite Lúpica

Abstract

Introduction: Systemic Lupus Erythematosus (SLE) is a chronic autoimmune inflammatory disease characterized by the production of autoantibodies in response to the presence of autoantigen, resulting in the formation of immune complexes (IC). One of the most severe manifestations of SLE is Lupus Nephritis (LN), a glomerulonephritis resulting from the deposition of circulating IC or those formed in situ in the glomeruli. Morphologically, the diagnosis of LN is established through renal biopsy, by the histopathological classification of the International Society of Nephrology/Renal Pathology Society, where the disease is divided into 6 histopathological classes and its activity and chronicity are also evaluated semiquantitatively, with a total score of 24 for the activity index and 12 for the chronicity index. Clinically, LN may present with nephrotic syndrome caused by alterations in the glomerular filtration barrier (GFB) formed by podocytes, which are visceral epithelial cells, the glomerular basement membrane, and fenestrated endothelial cells. The pathogenesis of LN involves complex interactions between immune complex deposits, inflammatory cytokines, and the immune response, directly affecting podocytes. Therefore, research related to podocytes can elucidate mechanisms involved in the pathogenesis of LN, contributing to the development of more effective and specific therapeutic strategies. Objectives: To evaluate podocytes in different classes of LN in renal biopsies performed by the Kidney Research Center (CePRim) at the Federal University of Triângulo Mineiro. Methods: Podocyte quantification was performed by immunohistochemistry with WT1 for analysis of podocyte density, and the width of the podocyte foot process was measured by transmission electron microscopy to assess foot process effacement. Twenty control cases and 29 renal biopsy cases diagnosed with LN were selected, divided according to the histopathological classes of the disease and according to the deposits found in immunofluorescence, with the groups IgG+IgM+C1q+C3 and Full-House (IgA+IgG+IgM+C1q+C3). Results: Podocyte density was lower in the LN group compared to the control group, and this reduction was observed in all classes analyzed when compared to the control group. We observed more foot process effacement in the LN group compared to the control group, and there was more effacement in groups classes I/II and class IV compared to the control group. Comparing the classes, in the class IV group, more foot process effacement was observed compared to the class III group. An increase in proteinuria levels was observed as the classes progressed, and the class IV group presented higher proteinuria levels compared to the classes I/II group. A strong, positive, and significant correlation was observed between the activity index and foot process effacement in the class IV group. A reduction in podocyte density was observed in the IgG+IgM+C1q+C3 and Full-House groups, and greater foot process effacement was observed in these groups compared to the control group. Conclusion: The progression of Lupus Nephritis classes is related to the reduction of podocytes and foot process effacement. Podocytes play an important role in the development of Lupus Nephritis, especially in class IV. This class presents more pedicel effacement, and this lesion is related to disease activity.