Análise do perfil fenotípico e funcional de leucócitos do sangue periférico de crianças com síndrome nefrótica idiopática

Abstract

Idiopathic nephrotic syndrome (INS) is a disease characterized by massive proteinuria, hypoproteinemia and edema. Considering the immunopathological characteristics of INS, this study aimed to analyze the phenotypic and functional profile of peripheral blood leukocytes of pediatric patients with INS. We evaluated 44 pediatric patients with INS recruited at the Pediatric Nephrology Unit of the Clinics Hospital from Federal University of Minas Gerais and 10 health children and adolescent as control group (CON). Pacients were subdivided according to the levels of proteinuria at the time of blood collection in high proteinuria (HP 200mg/24 hours) and low proteinuria (LP<200mg/24 hours); and also based on the response to corticosteroids in steroid sensitive (SS) and steroid resistant/dependent (SR). Patients and controls were submitted to blood collection for ex-vivo analysis of the phenotype profile of circulating leukocytes by flow cytometry. In vitro production of pro- and anti-inflammatory cytokines in specific lymphocytes populations from peripheral blood was also analyzed. Data were compared between patients and controls and in patients according the level of proteinuria. In addition, the migratory and celular activation behavior and the percentage of T-cells with regulatory profile were evaluated in lymphocytes of INS patients and controls. These parameters were compared in the subgroups of SS and SR patients, as well according to the proteinuria. Our results showed an increase of the percentage of CD4+TNF-+ lymphocytes and a decrease of the percentage of CD8+IFN-+ lymphocytes in patients with INS, regardless the levels of proteinuria. In patients with HP, there was increased percentage of CD4+ lymphocytes stained to pro-inflammatory cytokines, IFN-, TNF- and IL-17, as compared to control group. Only patients with HP exhibited an increase in the percentage of CD8+TNF-+ lymphocytes as compared to control group. These results suggest that patients with persistent proteinuria have more pronounced pro-inflammatory response, mediated primarily by TCD4+ lymphocytes, even under anti-inflammatory medication. The comparison of patients divided according to steroid response showed reduced percentages of B lymphocytes and NK cells in SR group as compared to control group. SS patients had lower percentage of NKT cells than controls. In CD4+ lymphocytes, the expression of the regulatory marker FoxP3 was significantly higher in SS patients than controls and SR group. The percentage of CD4+CTLA4+ cells was higher in SS patients than in SR group. Reduced expression of the migration marker CD18 was observed in CD3+ and CD8+ T lymphocytes of the SS group as compared to controls. The analysis of chemokine receptors revealed increased percentage of lymphocytes stained for CCR2 and CXCR4 both in SS and SR groups as compared to the control group. The increased percentage of cells stained for CCR5 receptor was observed only in SR group as compared to controls. Reduced expression of CD18 on the surface of TCD3 and TCD8 lymphocytes, as well the higher percentage of TCD4 cells with regulatory profile only in SS patients suggest that the control of inflammatory response in this group of patients might be related to changes in these parameters. Higher expression of chemokine receptors, CCR2 and CCR4, in INS patients may be explained by the inflammatory nature of the disease. On the other hand, only SR group showed an increased expression of CCR5, indicating higher inflammatory activity in this subgroup of patients. Taken together, our results suggest that the ability to activate regulatory mechanisms of immune response would be associated with steroid sensitivity.