Objective: Idiopathic membranous nephropathy (IMN) is a leading cause of nephrotic syndrome in middle-aged and elderly populations. Early intervention can delay disease progression and improve patient outcomes. This study aims to identify urinary biomarkers for IMN and investigate their association with disease progression, offering new insights for precise diagnosis and treatment.Methods: This study began with RNA sequencing of three urine sample types (first-void morning urine, second-void morning urine, and random urine), combined with single-cell RNA sequencing of renal tissues. Bioinformatics analyses—including differential gene expression screening, machine learning, and molecular function annotation—were employed to identify potential IMN biomarkers. Furthermore, we established both a siRNA-mediated gene silencing model and a lentivirus transfection-mediated gene overexpression model in HK-2 cells. Subsequently, we investigated the functional mechanisms of the candidate biomarkers through qRT-PCR, Western blot, immunohistochemistry, and immunofluorescence assays.Results: SPP1 was identified as a promising biomarker for IMN, demonstrating a critical role in promoting fibrosis and inflammatory responses associated with the disease. These findings suggest its potential as a novel therapeutic target for IMN intervention.

Renal fibrosis (RF) is a typical pathological presentation of end‐stage chronic kidney disease (CKD) and autosomal dominant polycystic kidney disease (ADPKD). However, the precise regulatory mechanisms governing this re‐expression process remain unclear. Differentially expressed microRNAs (miRNAs) associated with RF were screened by microarray analysis using the Gene Expression Omnibus (GEO) database. The miRNAs upstream of the genes in question were predicted using the miRWalk database. The miRNAs involved in the two GEO data sets were intersected to identify key miRNAs; their regulatory pathways were investigated using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Subsequently, the effects and the underlying mechanisms of target miRNA on RF were examined in a unilateral ureteral obstruction (UUO)‐induced mice renal fibrotic model and a transforming growth factor‐β1 (TGF‐β1)‐induced tubular epithelium (HK‐2) fibrotic cell model. In total, 109 and 32 differentially expressed miRNAs were identified in the GSE133530 and GSE80247 data sets, respectively. GREM1 was identified as a hub gene, where its 2196 upstream miRNAs were predicted; miR‐574‐5p was found to be downregulated and closely related to fibrosis after data set intersection and enrichment analyses, thus was selected for further investigation. A differential expression heatmap (GSE162794) showed that miR‐542‐5p was downregulated. The expression of GREM1 mRNA was upregulated, whereas that of miR‐542‐5p was downregulated in UUO mice and fibrotic HK‐2 cells as compared with the relevant controls. The binding site of miR‐542‐5p was predicted at the 3'UTR region of GREM1 and was confirmed by subsequent dual luciferase reporter gene assay. Western blot analysis showed that Gremlin‐1 and Fibronectin were significantly upregulated after induction of TGF‐β1; when miR‐542‐5p was overexpressed or GREM1 mRNA was interfered, the upregulations of Gremlin‐1 and Fibronectin were significantly reduced. Our research demonstrates that miR‐542‐5p plays a critical role in the progression of RF, and thus may be a promising therapeutic target for CKD and ADPKD.

Background: IgA nephropathy (IgAN) is a leading cause of renal failure, but its pathogenesis remains unclear, complicating diagnosis and treatment. The invasive nature of renal biopsy highlights the need for non-invasive diagnostic biomarkers. Bulk RNA sequencing (RNA-seq) of urine offers a promising approach for identifying molecular changes relevant to IgAN.Methods: We performed bulk RNA-seq on 53 urine samples from 11 untreated IgAN patients and 11 healthy controls, integrating these data with public renal RNA-seq, microarray, and scRNA-seq datasets. Machine learning was used to identify key differentially expressed genes, with protein expression validated by immunohistochemistry (IHC) and drug-target interactions explored via molecular docking.Results: Urine RNA-seq analysis revealed differential expression profiles, from which TYROBP and HCK were identified as key biomarkers using machine learning. These biomarkers were validated in both a test cohort and an external validation cohort, demonstrating strong predictive accuracy. scRNA-seq confirmed their cell-specific expression patterns, correlating with renal function metrics such as GFR and serum creatinine. IHC further validated protein expression, and molecular docking suggested potential therapeutic interactions with IgAN treatments.Conclusion: TYROBP and HCK are promising non-invasive urinary biomarkers for IgAN. Their predictive accuracy, validated through machine learning, along with IHC confirmation and molecular docking insights, supports their potential for both diagnostic and therapeutic applications in IgAN.

Background: Secreted phosphoprotein 1 (SPP1), a glycoprotein encoded by the SPP1 gene, can be detected in body fluids and tumor tissues of various diseases, representing a promising candidate biomarker. However, its application in focal segmental glomerulosclerosis (FSGS) remains at the exploratory stage. Patients and Methods: In a small-scale cohort, Bulk-RNA sequencing was employed to screen for core differentially expressed genes in urinary cells of FSGS patients, with SPP1 identified as a key candidate. RT-qPCR and ELISA were subsequently used to detect SPP1 expression in clinical urine samples. An adriamycin (ADR)-induced FSGS mouse model was established, and renal histopathological changes were evaluated using hematoxylin-eosin (HE), periodic acid-Schiff (PAS), and Masson staining. Immunohistochemistry and immunofluorescence were performed to examine the expression of SPP1, fibronectin, and F4/80 in renal tissues, with assessment of the effects of prednisone intervention. Results: Urinary SPP1 expression was significantly elevated in FSGS patients, particularly in those with CKD stage III. In the ADR mouse model, as glomerulosclerosis progressed, albuminuria levels increased, accompanied by enhanced expression of SPP1 and F4/80-positive macrophages. Prednisone treatment attenuated these parameters. Conclusion: SPP1 is involved in the progression of FSGS and is closely associated with renal immune inflammation and fibrosis. Prednisone exerts renoprotective effects by downregulating SPP1 expression and inhibiting macrophage infiltration, suggesting that SPP1 represents a promising molecular marker for disease monitoring and targeted intervention in FSGS.

Objective: This study aims to investigate the prevalence of chronic kidney disease (CKD) and explore the associations of the Visceral Adiposity Index (VAI) and Body Roundness Index (BRI) with CKD risk in the Hakka population, while quantitatively assessing the mediating effects of blood pressure indicators. Methods: Data for this study were obtained from a cross-sectional survey conducted in Bobai County, Guangxi, which included 8971 adult participants. Log-binomial regression, robust Poisson regression, and restricted cubic spline regression were used to evaluate the associations between the VAI/BRI and CKD risk. Mediation analysis was further conducted to assess the role of blood pressure parameters in these associations. Results: The overall prevalence of CKD was 12.62% in the study population. In the fully adjusted multivariable model (Model 3), compared with the lowest quartiles (Q1, reference), the highest quartiles (Q4) of both VAI and BRI were significantly associated with increased risks of CKD, with prevalence ratios of 1.61 (95% CI: 1.32–1.98) and 1.26 (95% CI: 1.05–1.52), respectively. Restricted cubic spline analysis revealed nonlinear associations between VAI/BRI and CKD risk, with accelerated risk increments at higher levels of both indices. Mediation analysis revealed that blood pressure indicators significantly mediated the VAI/BRI-CKD relationships, with notably stronger effects observed for BRI (SBP: 42.69%; DBP: 51.16%; MAP: 53.38%) compared to VAI (SBP: 21.4%; DBP: 28.15%; MAP: 28.41%). Additionally, PP exhibited a significant mediating effect only in the BRI-CKD pathway (12.21, 95% CI: 7.28–20.70). Conclusion: The VAI and BRI were independent risk factors for CKD in Hakka Biobank (HKB), with their associations with CKD are partially mediated by blood pressure. Given their ease of measurement and cost-effectiveness, VAI and BRI may serve as practical screening tools for identifying CKD high-risk individuals in community populations, thereby enabling early intervention and targeted prevention strategies of CKD.