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Introduction: Lupus nephritis (LN) affects up to 60 % of the patients with Systemic Lupus Erythematosus (SLE) and renal damage progression is associated with proteinuria, caused in part by the integrity of the glomerular basement membrane (GBM) and by podocyte injury. The soluble urokinase plasminogen activator receptor (suPAR) and Wilms Tumor 1 (WT1) have been related to podocyte effacement and consequently with proteinuria which raises questions about its pathogenic role in LN. Objective: Define whether suPAR levels and WT1 expression influence in podocyte anchorage destabilization in LN class IV. Materials and methods: This is a cross-sectional study of cases and controls. We studied patients with SLE without renal involvement (n = 12), SLE and LN class IV with proteinuria ≤0.5 g/24 h (n = 12), LN class IV with proteinuria ≥0.5 g/24 h (n = 12) and compared them with renal tissue control (CR) (n = 12) and control sera (CS) (n = 12). The CR was integrated by cadaveric samples without SLE or renal involvement and the CS was integrated by healthy participants. The expression and cellular localization of WT1, urokinase-type plasminogen activator receptor (uPAR), ac-α-tubulin, vimentin, and ß3-integrin was assessed by immunohistochemistry (IHC). The concentration of suPAR in serum was analyzed by enzyme-linked immunosorbent assay (ELISA). Results: In patients with LN, the activation of anchoring proteins was increased, such as podocyte ß3-integrin, as well as the acetylation of alpha-acetyl-tubulin and uPAR, in contrast to the decrease in vimentin; interestingly, the cellular localization of WT1 was cytoplasmic and the number of podocytes per glomerulus decreased. The concentrations of suPAR was increased in patients with LN. Conclusion: The destabilization of podocyte anchorage modulated by ß3-integrin activation, and tubulin acetylation, associated with decreased WT1 cytoplasmic expression, and increased suPAR levels could be involved in kidney damage in patients with LN class IV.
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INTRODUCTION: Urinary CD80 has been shown to have good specificity for minimal change disease (MCD) in children. However, the investigation of circulating factors such as soluble urokinase plasminogen activator receptor (suPAR) as biomarkers of focal segmental glomerulosclerosis (FSGS) is quite controversial. The objective of this study was to determine whether urinary CD80 and serum suPAR can be used for the diagnosis of MCD and FSGS, respectively, in the adult population of Brazil. We also attempted to determine whether those biomarkers assess the response to immunosuppressive treatment. METHODS: This was a prospective study in which urine and blood samples were collected for analysis of CD80 and suPAR, respectively, only in the moment of renal biopsy, from patients undergoing to diagnostic renal biopsy. At and six months after biopsy, we analyzed serum creatinine, serum albumin, and proteinuria in order to evaluate the use of the CD80 and suPAR collected in diagnosis as markers of response to immunosuppressive treatment. In healthy controls were collected urinary CD80 and proteinuria, serum suPAR, and creatinine. RESULTS: The results of 70 renal biopsies were grouped, by diagnosis, as follows: FSGS (n = 18); membranous nephropathy (n = 14); MCD (n = 5); and other glomerulopathies (n = 33). There was no significant difference among the groups in terms of the urinary CD80 levels, and serum suPAR was not significantly higher in the FSGS group, as would have been expected. Urinary CD80 correlated positively with nephrotic syndrome, regardless of the type of glomerular disease. Neither biomarker correlated with proteinuria at six months after biopsy. CONCLUSION: In adults, urinary CD80 can serve as a marker of nephrotic syndrome but is not specific for MCD, whereas serum suPAR does not appear to be useful as a diagnostic or treatment response marker.
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RATIONALE & OBJECTIVE: Biomarker studies are important for generating mechanistic insight and providing clinically useful predictors of chronic kidney disease (CKD) progression. However, variability across studies can often muddy the evidence waters. Here we evaluated real-world variability in biomarker studies using two published studies, independently conducted, of the novel plasma marker soluble urokinase-type plasminogen activator receptor (suPAR) for predicting CKD progression in children with CKD. STUDY DESIGN: A comparison of 2 prospective cohort studies. SETTING & PARTICIPANTS: 541 children from the Chronic Kidney Disease in Children (CKiD) study, median age 12 years, median glomerular filtration rate (GFR) of 54 mL/min/1.73m2. OUTCOME: The first occurrence of either a 50% decline in GFR from baseline or incident end-stage kidney disease. ANALYTICAL APPROACH: The suPAR plasma marker was measured using the Quantikine ELISA immunoassay in the first study and Meso Scale Discovery (MSD) platform in the second. The analytical approaches varied. We used suPAR data from the 2 assays and mimicked each analytical approach in an overlapping subset. RESULTS: We found that switching assays had the greatest impact on inferences, resulting in a 38% to 66% change in the magnitude of the effect estimates. Covariate and modeling choices resulted in an additional 8% to 40% variability in the effect estimate. The cumulative variability led to different inferences despite using a similar sample of CKiD participants and addressing the same question. LIMITATIONS: The estimated variability does not represent optimal repeatability but instead illustrates real-world variability that may be present in the CKD biomarker literature. CONCLUSIONS: Our results highlight the importance of validation, avoiding conclusions based on P value thresholds, and providing comparable metrics. Further transparency of data and equal weighting of negative and positive findings in explorations of novel biomarkers will allow investigators to more quickly weed out less promising biomarkers.
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La esclerosis focal y segmentaria glomerular primaria es una causa frecuente de sindrome nefrótico con alta morbilidad que con frecuencia lleva a la insuficiencia renal terminal debido a que sus esquemas terapeúticos no son exitosos, ya que sus mecanismos fisiopatológicos a la actualidad han sido parcialmente descifrados. Éstos son heterogéneos, complejos de integrar, y además el término agrupa bajo la misma denominación -la cual evoca una descripción histológica- a un variado número de causas moleculares con distinta fisiopatogenia. En esta revisión se describen los últimos adelantos respecto a la fisiopatología de esta compleja entidad y los últimos adelantos en su terapéutica.
Primary focal and segmental glomerulosclerosis is a common cause of nephrotic syndrome with high morbidity that often leads to end-stage renal failure as the different available therapeutic approaches are unsuccessful, due in part to the fact that the pathophysiological mechanisms have not been fully deciphered, are heterogeneous and complex to integrate, and more important, the denomination employed evokes a histological description shared by a number of different causes with different molecular pathogenesis. This review describes the latest developments regarding the pathophysiology of this complexentity and describes recent advances in therapy.
Assuntos
Glomerulosclerose Segmentar e Focal , Ativador de Plasminogênio Tipo Uroquinase , Podócitos , ProteinúriaRESUMO
La esclerosis focal y segmentaria glomerular primaria es una causa frecuente de sindrome nefrótico con alta morbilidad que con frecuencia lleva a la insuficiencia renal terminal debido a que sus esquemas terapeúticos no son exitosos, ya que sus mecanismos fisiopatológicos a la actualidad han sido parcialmente descifrados. Estos son heterogéneos, complejos de integrar, y además el término agrupa bajo la misma denominación -la cual evoca una descripción histológica- a un variado número de causas moleculares con distinta fisiopatogenia. En esta revisión se describen los últimos adelantos respecto a la fisiopatología de esta compleja entidad y los últimos adelantos en su terapéutica.(AU)
Primary focal and segmental glomerulosclerosis is a common cause of nephrotic syndrome with high morbidity that often leads to end-stage renal failure as the different available therapeutic approaches are unsuccessful, due in part to the fact that the pathophysiological mechanisms have not been fully deciphered, are heterogeneous and complex to integrate, and more important, the denomination employed evokes a histological description shared by a number of different causes with different molecular pathogenesis. This review describes the latest developments regarding the pathophysiology of this complexentity and describes recent advances in therapy.(AU)