Focal segmental glomerulosclerosis histologic variants and renal outcomes based on nephrotic syndrome, immunosuppression, and proteinuria remission

Clinicopathological features and medium-term outcomes of histologic variants of primary focal segmental glomerulosclerosis in adults: A retrospective study

BACKGROUND

The Columbia classification identified five histological variants of focal segmental glomerulosclerosis (FSGS). The prognostic significance of these variants remains controversial.

AIM

To evaluate the relative frequency, clinicopathologic characteristics, and medium-term outcomes of FSGS variants at a single center in Pakistan.

METHODS

This retrospective study was conducted at the Department of Nephrology, Sindh Institute of Urology and Transplantation, Karachi, Pakistan on all consecutive adults (≥ 16 years) with biopsy-proven primary FSGS from January 1995 to December 2017. Studied subjects were treated with steroids as a first-line therapy. The response rates, doubling of serum creatinine, and kidney failure (KF) with replacement therapy were compared between histological variants using ANOVA or Kruskal Wallis, and Chi-square tests as appropriate. Data were analyzed by SPSS version 22.0. P-value ≤ 0.05 was considered significant.

RESULTS

A total of 401 patients were diagnosed with primary FSGS during the study period. Among these, 352 (87.7%) had a designated histological variant. The not otherwise specified (NOS) variant was the commonest, being found in 185 (53.9%) patients, followed by the tip variant in 100 (29.1%) patients. Collapsing (COL), cellular (CEL), and perihilar (PHI) variants were seen in 58 (16.9%), 6 (1.5%), and 3 (0.7%) patients, respectively. CEL and PHI variants were excluded from further analysis due to small patient numbers. The mean follow-up period was 36.5 ± 29.2 months. Regarding response rates of variants, patients with TIP lesions achieved remission more frequently (59.5%) than patients with NOS (41.8%) and COL (24.52%) variants (P < 0.001). The hazard ratio of complete response among patients with the COL variant was 0.163 [95% confidence interval (CI): 0.039-0.67] as compared to patients with NOS. The TIP variant showed a hazard ratio of 2.5 (95%CI: 1.61-3.89) for complete remission compared to the NOS variant. Overall, progressive KF was observed more frequently in patients with the COL variant, 43.4% (P < 0.001). Among these, 24.53% of patients required kidney replacement therapy (P < 0.001). The hazard ratio of doubling of serum creatinine among patients with the COL variant was 14.57 (95%CI: 1.87-113.49) as compared to patients with the TIP variant.

CONCLUSION

In conclusion, histological variants of FSGS are predictive of response to treatment with immunosuppressants and progressive KF in adults in our setup.

The epidemiology of primary FSGS including cluster analysis over a 20-year period

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is one of the leading causes of nephrotic syndrome in adults. This epidemiological study describes a renal centre's 20-year experience of primary FSGS.

METHODS

Patients were identified with a diagnosis of primary FSGS after exclusion of known secondary causes. In this retrospective observational study, data was collected for baseline demographics, immunosuppression and outcomes. A two-step cluster analysis was used to identify natural groupings within the dataset.

RESULTS

The total cohort was made up of 87 patients. Those who received immunosuppression had lower median serum albumin than those who did not- 23g/L vs 40g/L (p<0.001) and higher median urine protein creatinine ratios (uPCR)- 795mg/mmol vs 318mg/mmol (p <0.001). They were more likely to achieve complete remission (62% vs 40%, p=0.041), but relapsed more 48.6% vs 22% (p=0.027). Overall 5 year mortality was 10.3% and 5 year progression to RRT was seen in 17.2%. Complete remission was observed in 49.4%. The 2-step cluster analysis separated the cohort into 3 clusters: cluster 1 (n=26) with 'nephrotic-range proteinuria'; cluster 2 (n=43) with 'non-nephrotic-range proteinuria'; and cluster 3 (n=18) with nephrotic syndrome. Immunosuppression use was comparable in clusters 1 and 3, but lower in cluster 2 (77.8% and 69.2% vs 11.6%, p<0.001). Rates of complete remission were greatest in clusters 1 and 3 vs cluster 2: 57.7% and 66.7% vs 37.2%.

CONCLUSION

People who received immunosuppression had lower serum albumin and achieved remission more frequently, but were also prone to relapse. Our cluster analysis highlighted 3 FSGS phenotypes: a nephrotic cluster that clearly require immunosuppression; a cohort with preserved serum albumin and non-nephrotic range proteinuria who will benefit from supportive care; and lastly a cluster with heavy proteinuria but serum albumin > 30g/L. This group may still have immune mediated disease and thus could potentially benefit from immunosuppression.

TRIAL REGISTRATION

This study protocol was reviewed and approved by the 'Research and Innovation committee of the Northern Care Alliance NHS Group', study approval number (Ref: ID 22HIP54).

An integrated bioinformatics approach to identify key biomarkers in the tubulointerstitium of patients with focal segmental glomerulosclerosis and construction of mRNA-miRNA-lncRNA/circRNA networks

OBJECTIVE

The purpose of this study was to identify potential biomarkers in the tubulointerstitium of focal segmental glomerulosclerosis (FSGS) and comprehensively analyze its mRNA-miRNA-lncRNA/circRNA network.

METHODS

The expression data (GSE108112 and GSE200818) were downloaded from the Gene Expression Omnibus database (https://www.ncbi.nlm.nih.gov/geo/). Identification and enrichment analysis of differentially expressed genes (DEGs) were performed. the PPI networks of the DEGs were constructed and classified using the Cytoscape molecular complex detection (MCODE) plugin. Weighted gene coexpression network analysis (WGCNA) was used to identify critical gene modules. Least absolute shrinkage and selection operator regression analysis were used to screen for key biomarkers of the tubulointerstitium in FSGS, and the receiver operating characteristic curve was used to determine their diagnostic accuracy. The screening results were verified by quantitative real-time-PCR (qRT-PCR) and Western blot. The transcription factors (TFs) affecting the hub genes were identified by Cytoscape iRegulon. The mRNA-miRNA-lncRNA/circRNA network for identifying potential biomarkers was based on the starBase database.

RESULTS

A total of 535 DEGs were identified. MCODE obtained eight modules. The green module of WGCNA had the greatest association with the tubulointerstitium in FSGS. PPARG coactivator 1 alpha (PPARGC1A) was screened as a potential tubulointerstitial biomarker for FSGS and verified by qRT-PCR and Western blot. The TFs FOXO4 and FOXO1 had a regulatory effect on PPARGC1A. The ceRNA network yielded 17 miRNAs, 32 lncRNAs, and 50 circRNAs.

CONCLUSIONS

PPARGC1A may be a potential biomarker in the tubulointerstitium of FSGS. The ceRNA network contributes to the comprehensive elucidation of the mechanisms of tubulointerstitial lesions in FSGS.

Demographics and treatment of patients with primary nephrotic syndrome in Japan using a national registry of clinical personal records

The nationwide clinical features of Japanese patients with primary nephrotic syndrome (NS), including minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or membranous nephropathy (MN), have not yet been reported. We collected the clinical personal records of patients with primary NS between 2015 and 2018 from the national registry organized by the Japanese Ministry of Health, Labour, and Welfare. Overall, the demographics, chronic kidney disease classification based on glomerular filtration rate and albuminuria, and treatment of 6036 patients were collected: 3394 (56.2%) with MCD, 677 (11.2%) with FSGS, 1455 (24.1%) with MN, and 510 (8.5%) with others. MN patients were older than MCD and FSGS patients (67 vs. 42 and 47 years, respectively). Steroid-dependent NS or frequently relapsing NS was found in 70.2%, 40.5%, and 24.6%, whereas steroid-resistant NS was found in 6.4%, 36.0%, and 37.9% of patients in the MCD, FSGS, and MN, respectively. The present oral prednisolone use (mean dose, mg/day) was 87.2% (21.2), 80.9% (20.0), and 77.5% (18.8) of patients in the MCD, FSGS, and MN, respectively. The national registry of clinical personal records of primary NS could provide an informative insight into the characteristics, clinical features, and treatment approaches for patients with primary NS in Japan.

Develop and Validate a Risk Score in Predicting Renal Failure in Focal Segmental Glomerulosclerosis

Introduction

The aim of this study was to develop and validate a risk score (RS) for end-stage kidney disease (ESKD) in patients with focal segmental glomerulosclerosis (FSGS).

Methods

Patient with biopsy-proven FSGS was enrolled. All the patients were allocated 1:1 to the two groups according to their baseline gender, age, and baseline creatinine level by using a stratified randomization method. ESKD was the primary endpoint.

Results

We recruited 359 FSGS patients, and 177 subjects were assigned to group 1 and 182 to group 2. The clinicopathological variables were similar between two groups. There were 23 (13%) subjects reached to ESKD in group 1 and 22 (12.1%) in group 2. By multivariate Cox regression analyses, we established RS 1 and RS 2 in groups 1 and 2, respectively. RS 1 consists of five parameters including lower eGFR, higher urine protein, MAP, IgG level, and tubulointerstitial lesion (TIL) score; RS 2 also consists of five predictors including lower C3, higher MAP, IgG level, hemoglobin, and TIL score. RS 1 and RS 2 were cross-validated between these two groups, showing RS 1 had better performance in predicting 5-year ESKD in group 1 (c statics, 0.86 [0.74-0.98] vs. 0.82 [0.69-0.95]) and group 2 (c statics, 0.91 [0.83-0.99] vs. 0.89 [0.79-0.99]) compared to RS 2. We then stratified the risk factors into four groups, and Kaplan-Meier survival curve revealed that patients progressed to ESKD increased as risk levels increased.

Conclusions

A predictive model incorporated clinicopathological feature was developed and validated for the prediction of ESKD in FSGS patients.

Decoding the Mechanism behind the Pathogenesis of the Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a chronic glomerular disease associated with podocyte injury which is named after the pathologic features of the kidney. The aim of this study is to decode the key changes in gene expression and regulatory network involved in the formation of FSGS. Integrated network analysis included Gene Expression Omnibus (GEO) datasets to identify differentially expressed genes (DEGs) between FSGS patients and healthy donors. Bioinformatics analysis was used to identify the roles of the DEGs and included the development of protein-protein interaction (PPI) networks, Gene Ontology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and the key modules were assured. The expression levels of DEGs were validated using the additional dataset. Eventually, transcription factors and ceRNA networks were established to illuminate the regulatory relationships in the formation of FSGS. 1130 DEGs including 475 upregulated genes and 655 downregulated genes with functional enrichment analysis were determined. Further analysis uncovered that the validated hub genes were defined as candidate genes, including Complement C3a Receptor 1 (C3AR1), C-C Motif Chemokine Receptor 1(CCR1), C-X3-C Motif Chemokine Ligand 1 (CX3CL1), Melatonin Receptor 1A (MTNR1A), and Purinergic Receptor P2Y13 (P2RY13). More importantly, we identified transcription factors and mRNA-miRNA-lncRNA regulatory networks associated with the candidate genes. The candidate genes and regulatory networks discovered in this study can help to comprehend the molecular mechanism of FSGS and supply potential targets for the diagnosis and therapy of FSGS.