Papel do sistema complemento na patogênese da glomeruloesclerose segmentar e focal e da doença de lesões mínimas.

Abstract

Introduction: Podocytopathies, minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS), are the main causes of nephrotic syndrome in the world and morphologically, show foot processes effacement in transmission electron microscopy. It is known that the immune system is important in the etiopathogenesis of these diseases and, in particular, the activation of the complement system has been recognized as a cause of injury and as a factor of poor prognosis in several kidney diseases. Objective: To evaluate the deposition of immunoglobulins and particles of the complement system in renal biopsies of patients with FSGS and MCD, and to relate it to laboratory data and prognosis. Materials and methods: 59 renal biopsies from patients with podocytopathies were selected, 31 from patients with FSGS and 28 with MCD. The epidemiological, clinical and laboratory information of these patients was evaluated. The analysis of the deposition of IgM, IgG, C3 and C1q in renal biopsies was performed using the immunofluorescence technique and C4d by immunohistochemistry. We related IgM and C3 deposition with laboratory data and clinical outcome. Results: Glomerular IgM deposition was significantly higher in the FSGS group, as well as IgM and C3 codeposition. The clinical evolution of patients was also worse in cases of FSGS, with a higher percentage progressing to CKD and death. In contrast, the vast majority of patients with MCD showed improvement in the disease after treatment. Patients with C3 deposition had significantly higher mean serum creatinine values and significantly lower eGFR, regardless of disease. Conclusions: Patients with FSGS had more IgM and C3 deposition in renal biopsies, worse laboratory parameters and clinical evolution than patients with MCD. C3 deposition, both in FSGS and MCD, can contribute to the worsening of renal function.