Cathepsin S regulates renal fibrosis in mouse models of mild and severe hydronephrosis

Targeting ferroptosis: a new therapeutic opportunity for kidney diseases

Ferroptosis is a form of non-apoptotic regulated cell death (RCD) that depends on iron and is characterized by the accumulation of lipid peroxides to lethal levels. Ferroptosis involves multiple pathways including redox balance, iron regulation, mitochondrial function, and amino acid, lipid, and glycometabolism. Furthermore, various disease-related signaling pathways also play a role in regulating the process of iron oxidation. In recent years, with the emergence of the concept of ferroptosis and the in-depth study of its mechanisms, ferroptosis is closely associated with various biological conditions related to kidney diseases, including kidney organ development, aging, immunity, and cancer. This article reviews the development of the concept of ferroptosis, the mechanisms of ferroptosis (including GSH-GPX4, FSP1-CoQ1, DHODH-CoQ10, GCH1-BH4, and MBOAT1/2 pathways), and the latest research progress on its involvement in kidney diseases. It summarizes research on ferroptosis in kidney diseases within the frameworks of metabolism, reactive oxygen biology, and iron biology. The article introduces key regulatory factors and mechanisms of ferroptosis in kidney diseases, as well as important concepts and major open questions in ferroptosis and related natural compounds. It is hoped that in future research, further breakthroughs can be made in understanding the regulation mechanism of ferroptosis and utilizing ferroptosis to promote treatments for kidney diseases, such as acute kidney injury(AKI), chronic kidney disease (CKD), diabetic nephropathy(DN), and renal cell carcinoma. This paves the way for a new approach to research, prevent, and treat clinical kidney diseases.

SOCS3, Transcriptionally Activated by NR4A1, Induces Apoptosis and Extracellular Matrix Degradation of Vaginal Fibroblasts in Pelvic Organ Prolapse

Background

Pelvic organ prolapse (POP) is a common gynecological chronic disorder. Human vaginal fibroblasts (HVFs) that maintain the integrity of vaginal wall tissues are essential for keeping pelvic organs in place. Apoptosis and the degradation of the extracellular matrix in HVFs contribute to the progression of POP. The cytokine signal transduction inhibitor 3 (SOCS3) exerts significant regulatory effects on cell signal transduction pathways, thereby affecting various pathological processes.

Aims

To explore the role and mechanism of SOCS3 on HVFs in the context of POP.

Study Design

In vitro cell lines and human-sample study.

Methods

Anterior vaginal wall tissues were obtained from POP or non-POP patients for the analysis of SOCS3 expression. HVFs were isolated from the vaginal tissues of POP patients, and SOCS3 was either overexpressed or knocked down in HVFs via lentivirus infection. Subsequently, the biological function and mechanism of SOCS3 in HVFs were investigated.

Results

SOCS3 was highly expressed in the vaginal tissues of POP patients compared to non-POP patients. Functionally, the overexpression of SOCS3 suppressed cell viability while promoting cell apoptosis in HVFs. The overexpression of SOCS3 also accelerated extracellular matrix degradation (decreasing collagen I, collagen III, and elastin, and increasing MMP2 and MMP9). In terms of mechanism, NR4A1 transcriptionally activated SOCS3 by binding to its promoter. Furthermore, rescue experiments revealed that SOCS3 knockdown hindered NR4A1 overexpression-induced cell apoptosis and extracellular matrix degradation in HVFs.

Conclusion

SOCS3 mediated the apoptotic and extracellular matrix degradation effects of NR4A1 on HVFs, underlining that the restraining of the SOCS3 expression may be a promising strategy for POP treatment.

Piezo1 specific deletion in macrophage protects the progression of liver fibrosis in mice

Background and Aims: Liver fibrosis is the common pathological pathway of chronic liver diseases and its mechanisms of which have not been fully declared. Macrophages play essential roles in progression of liver fibrosis partially by sensing abnormal mechanical signals. The aim of the study is to investigate the functions of macrophage Piezo1, a mechano-sensitive ion channel, in liver fibrosis. Approach and Results: Immunofluorescence in human and murine fibrotic liver samples revealed that expression of macrophage Piezo1 was increased. Myeloid-specific Piezo1 knockout (Piezo1ΔLysM) attenuated liver fibrosis by decreased collagen deposition and epithelial-mesenchymal transition (EMT). In Piezo1ΔLysM mice, less inflammation during development of liver fibrosis was observed by lessened macrophage infiltration, decreased M1 polarization and expression of inflammatory cytokines. RNA-seq data showed macrophage Piezo1 regulated transcription of cathepsin S (CTSS). Piezo1ΔLysM inhibited expression and activity of CTSS in vitro and in vivo and regulated T cell activity. Furthermore, inhibition of CTSS reversed macrophage inflammatory response driven by Piezo1 activation and LPS. Macrophage Piezo1 activation promoted CTSS secretion due to increased activity of Ca2+-dependent calpain protease induced by Ca2+ influx to cleave lysosome-associated membrane protein-1 (LAMP1). Pharmacological inhibition of calpain activity partially blocked Piezo1 mediated CTSS secretion. Conclusions: Macrophage Piezo1 deficiency limits the progression of liver fibrosis by inhibited inflammatory response and decreased secretion of CTSS. These findings suggest that targeting Piezo1 channel may be a potential strategy for treating hepatic fibrosis.

Identification of immune-related molecular clusters and diagnostic markers in chronic kidney disease based on cluster analysis

Background: Chronic kidney disease (CKD) is a heterogeneous disease with multiple etiologies, risk factors, clinical manifestations, and prognosis. The aim of this study was to identify different immune-related molecular clusters in CKD, their functional immunological properties, and to screen for promising diagnostic markers. Methods: Datasets of 440 CKD patients were obtained from the comprehensive gene expression database. The core immune-related genes (IRGs) were identified by weighted gene co-expression network analysis. We used unsupervised clustering to divide CKD samples into two immune-related subclusters. Then, functional enrichment analysis was performed for differentially expressed genes (DEGs) between clusters. Three machine learning methods (LASSO, RF, and SVM-RFE) and Venn diagrams were applied to filter out 5 significant IRGs with distinguished subtypes. A nomogram diagnostic model was developed, and the prediction effect was verified using calibration curve, decision curve analysis. CIBERSORT was applied to assess the variation in immune cell infiltration among clusters. The expression levels, immune characteristics and immune cell correlation of core diagnostic markers were investigated. Finally, the Nephroseq V5 was used to assess the correlation among core diagnostic markers and renal function. Results: The 15 core IRGs screened were differentially expressed in normal and CKD samples. CKD was classified into two immune-related molecular clusters. Cluster 2 is significantly enriched in biological functions such as leukocyte adhesion and regulation as well as immune activation, and has a severe immune prognosis compared to cluster 1. A nomogram diagnostic model with reliable prediction of immune-related clusters was developed based on five signature genes. The core diagnostic markers LYZ, CTSS, and ISG20 were identified as playing an important role in the immune microenvironment and were shown to correlate meaningfully with immune cell infiltration and renal function. Conclusion: Our study identifies two subtypes of CKD with distinct immune gene expression patterns and provides promising predictive models. Along with the exploration of the role of three promising diagnostic markers in the immune microenvironment of CKD, it is anticipated to provide novel breakthroughs in potential targets for disease treatment.

Title: Bioinformatic Identification of Genes Involved in Diabetic Nephropathy Fibrosis and their Clinical Relevance

Tubulointerstitial fibrosis is an important pathological feature of diabetic nephropathy that is associated with impaired renal function. However, the mechanism by which fibrosis occurs in diabetic nephropathy is unclear. Differentially expressed genes were identified from transcriptome profiles of renal tissue from diabetic patients and unilateral ureteral obstruction mice and intersected to obtain genes that may be involved in diabetic fibrosis. Biological function analysis and protein-protein interaction network analysis were performed. ROC curve and Pearson correlation analysis between hub genes were performed and glomerular filtration rate estimated. Finally, the RNA levels of hub genes were measured using real-time PCR. A total of 283 genes were identified as potentially involved in diabetic nephropathy fibrosis. TYROBP, CTSS, LCP2, LUM and TLR7 were identified as aberrantly expressed hub genes. Immune cell infiltration analysis demonstrated higher numbers of cytotoxic lymphocytes, B lineage cells, monocyte lineage cells, myeloid dendritic cells, neutrophils, and fibroblasts in the diabetic nephropathy group. The areas under ROC curves for TYROBP, CTSS, LCP2, LUM and TLR7 were 0.9167, 0.9583, 0.9917, 0.93333, and 0.9583, respectively (P < 0.001), and their correlation coefficients with estimated glomerular filtration rate were - 0.8332, - 0.752, - 0.7875, - 0.7567, and - 0.7136, respectively (P < 0.001). The RNA levels of TYROBP, CTSS, LUM and TLR7 were upregulated in high-glucose-treated human renal tubular epithelial cells (P < 0.005). Our study identified TYROBP, CTSS, LCP2, LUM and TLR7 as potentially involved in diabetic nephropathy fibrosis. Furthermore, TYROBP, CTSS, LUM and TLR7 may be associated with epithelial-mesenchymal transition of tubular epithelial cells.

Identifying effective diagnostic biomarkers and immune infiltration features in chronic kidney disease by bioinformatics and validation

Background: Chronic kidney disease (CKD), characterized by sustained inflammation and immune dysfunction, is highly prevalent and can eventually progress to end-stage kidney disease. However, there is still a lack of effective and reliable diagnostic markers and therapeutic targets for CKD. Methods: First, we merged data from GEO microarrays (GSE104948 and GSE116626) to identify differentially expressed genes (DEGs) in CKD and healthy patient samples. Then, we conducted GO, KEGG, HPO, and WGCNA analyses to explore potential functions of DEGs and select clinically significant modules. Moreover, STRING was used to analyse protein-protein interactions. CytoHubba and MCODE algorithms in the cytoscape plug-in were performed to screen hub genes in the network. We then determined the diagnostic significance of the obtained hub genes by ROC and two validation datasets. Meanwhile, the expression level of the biomarkers was verified by IHC. Furthermore, we examined immunological cells' relationships with hub genes. Finally, GSEA was conducted to determine the biological functions that biomarkers are significantly enriched. STITCH and AutoDock Vina were used to predict and validate drug-gene interactions. Results: A total of 657 DEGs were screened and functional analysis emphasizes their important role in inflammatory responses and immunomodulation in CKD. Through WGCNA, the interaction network, ROC curves, and validation set, four hub genes (IL10RA, CD45, CTSS, and C1QA) were identified. Furthermore, IHC of CKD patients confirmed the results above. Immune infiltration analysis indicated that CKD had a significant increase in monocytes, M0 macrophages, and M1 macrophages but a decrease in regulatory T cells, activated dendritic cells, and so on. Moreover, four hub genes were statistically correlated with them. Further analysis exhibited that IL10RA, which obtained the highest expression level in hub genes, was involved in abnormalities in various immune cells and regulated a large number of immune system responses and inflammation-related pathways. In addition, the drug-gene interaction network contained four potential therapeutic drugs targeting IL10RA, and molecular docking might make this relationship viable. Conclusion: IL10RA and its related hub molecules might play a key role in the development of CKD and could be potential biomarkers in CKD.

Inflammation-Driven Secretion Potential Is Upregulated in Osteoarthritic Fibroblast-Like Synoviocytes

Osteoarthritis (OA) is one of the most common joint pathologies and a major cause of disability among the population of developed countries. It manifests as a gradual degeneration of the cartilage and subchondral part of the bone, leading to joint damage. Recent studies indicate that not only the cells that make up the articular cartilage but also the synoviocytes, which build the membrane surrounding the joint, contribute to the development of OA. Therefore, the aim of the study was to determine the response to inflammatory factors of osteoarthritic synoviocytes and to identify proteins secreted by them that may influence the progression of OA. This study demonstrated that fibroblast-like synoviocytes of OA patients (FLS-OA) respond more strongly to pro-inflammatory stimulation than cells obtained from control patients (FLS). These changes were observed at the transcriptome level and subsequently confirmed by protein analysis. FLS-OA stimulated by pro-inflammatory factors [such as lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNFα) were shown to secrete significantly more chemokines (CXCL6, CXCL10, and CXCL16) and growth factors [angiopoietin-like protein 1 (ANGPTL1), fibroblast growth factor 5 (FGF5), and insulin-like growth factor 2 (IGF2)] than control cells. Moreover, the translation of proteolytic enzymes [matrix metalloprotease 3 (MMP3), cathepsin K (CTSK), and cathepsin S (CTSS)] by FLS-OA is increased under inflammatory conditions. Our data indicate that the FLS of OA patients are functionally altered, resulting in an enhanced response to the presence of pro-inflammatory factors in the environment, manifested by the increased production of the previously mentioned proteins, which may promote further disease progression.

Identification of Hub Genes and Immune-Related Pathways for Membranous Nephropathy by Bioinformatics Analysis

OBJECTIVE: We aim to explore the detailed molecular mechanisms of membrane nephropathy (MN) related genes by bioinformatics analysis.

METHODS: Two microarray datasets (GSE108109 and GSE104948) with glomerular gene expression data from 65 MN patients and 9 healthy donors were obtained from the Gene Expression Omnibus (GEO) database. After processing the raw data, DEGs screening was conducted using the LIMMA (linear model for microarray data) package and Gene set enrichment analysis (GSEA) was performed with GSEA software (v. 3.0), followed by gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. The protein-protein interaction (PPI) network analysis was carried out to determine the hub genes, by applying the maximal clique centrality (MCC) method, which was visualized by Cytoscape. Finally, utilizing the Nephroseq v5 online platform, we analyzed subgroups associated with hub genes. The findings were further validated by immunohistochemistry (IHC) staining in renal tissues from MN or control patients.

RESULTS: A sum of 370 DEGs (188 up-regulated genes, 182 down-regulated genes) and 20 hub genes were ascertained. GO and KEGG enrichment analysis demonstrated that DEGs of MN were preponderantly associated with cell damage and complement cascade-related immune responses. Combined with literature data and hub gene-related MN subset analysis, CTSS, ITGB2, and HCK may play important roles in the pathological process of MN.

CONCLUSION: This study identified novel hub genes in MN using bioinformatics. We found that some hub genes such as CTSS, ITGB2, and HCK might contribute to MN immunopathological process, providing new insights for further study of the molecular mechanisms underlying glomerular injury of MN.

Renal-on-Chip Microfluidic Platform with a Force-Sensitive Resistor (ROC-FS) for Molecular Pathogenesis Analysis of Hydronephrosis

Hydronephrosis is one of the most common diseases in urology. However, due to the difficulties in clinical trials and the lack of reliable in vitro platforms, the surgical indicators are not clear. Herein, the renal-on-chip with a force-sensitive resistor microfluidic platform was established to simulate the state of hydronephrosis. Cell counting kit-8 (CCK-8) and tight junction protein claudin-2 were detected on a renal-on-chip microfluidic platform with a force-sensitive resistor (ROC-FS). The results indicated that the ROC-FS had normal physiological functions and the cell viability on ROC-FS declined to around 40% after 48 h of hydronephrosis-simulated treatment. In addition, proteomics analysis of 15 clinical ureteropelvic junction obstruction (UPJO) samples showed that compared with normal children, a total of 50 common proteins were differentially expressed in UPJO children (P < 0.05, |log₂fold change| ≥ 1). Metabolomic analysis of 39 clinical UPJO samples showed that a total of 241 metabolisms were dysregulated. Subsequent immunofluorescence and enzyme-linked immunosorbent assay (ELISA) analysis using ROC-FS were performed to identify the clinical multi-omics results for screening. All results pointed out that the TGF-β-related signaling pathways and arginine-related metabolism signaling pathways were dysregulated and α-SMA, AGT, and AGA might be the potential biomarkers of hydronephrosis. In addition, correlation analysis of AGT and KLK1 with differential renal function (DRF) from clinical samples indicated good correlation coefficients (R² 0.923, 0.8742, 0.6412, and 0.8347). This demonstrates the state of hydronephrosis could be significantly correlated with the biomarkers. These findings could provide a reliable reference for determining surgical biomarkers clinically, and ROC could be further used in the analysis of other kidney diseases.

Proteomics changes after negative pressure wound therapy in diabetic foot ulcers

Label-free quantitative mass spectrometry was used to analyze the differences in the granulation tissue protein expression profiles of patients with diabetic foot ulcers (DFUs) before and after negative-pressure wound therapy (NPWT) to understand how NPWT promotes the healing of diabetic foot wounds. A total of three patients with DFUs hospitalized for Wagner grade 3 were enrolled. The patients received NPWT for one week. The granulation tissue samples of the patients prior to and following NPWT for one week were collected. The protein expression profiles were analyzed with label-free quantitative mass spectrometry and the differentially expressed proteins (DEPs) in the DFU patients prior to and following NPWT for one week were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were conducted to annotate the DEPs and DEP-associated signaling pathways. Western blotting and ELISA were performed to validate the results. By comparing the differences in the protein profiles of granulation tissue samples prior to and following NPWT for one week, 36 proteins with significant differences were identified (P<0.05); 33 of these proteins were upregulated and three proteins were downregulated. NPWT altered proteins mainly associated with antioxidation and detoxification, the cytoskeleton, regulation of the inflammatory response, complement and coagulation cascades and lipid metabolism. The functional validation of the DEPs demonstrated that the levels of cathepsin S in peripheral blood and granulation tissue were significantly lower than those prior to NPWT (P<0.05), while the levels of protein S isoform 1, inter α-trypsin inhibitor heavy chain H4 and peroxiredoxin-2 in peripheral blood and granulation tissue were significantly higher than those prior to NPWT (P<0.05). The present study identified multiple novel proteins altered by NPWT and laid a foundation for further studies investigating the mechanism of action of NPWT.

Urine peptidome analysis in cardiorenal syndrome reflects molecular processes

The cardiorenal syndrome (CRS) is defined as the confluence of heart-kidney dysfunction. This study investigates the molecular differences at the level of the urinary peptidome between CRS patients and controls and their association to disease pathophysiology. The urinary peptidome of CRS patients (n = 353) was matched for age and sex with controls (n = 356) at a 1:1 ratio. Changes in the CRS peptidome versus controls were identified after applying the Mann-Whitney test, followed by correction for multiple testing. Proteasix tool was applied to investigate predicted proteases involved in CRS-associated peptide generation. Overall, 559 differentially excreted urinary peptides were associated with CRS patients. Of these, 193 peptides were specifically found in CRS when comparing with heart failure and chronic kidney disease urinary peptide profiles. Proteasix predicted 18 proteases involved in > 1% of proteolytic cleavage events including multiple forms of MMPs, proprotein convertases, cathepsins and kallikrein 4. Forty-four percent of the cleavage events were produced by 3 proteases including MMP13, MMP9 and MMP2. Pathway enrichment analysis supported that ECM-related pathways, fibrosis and inflammation were represented. Collectively, our study describes the changes in urinary peptides of CRS patients and potential proteases involved in their generation, laying the basis for further validation.

Decreased Expression of Canstatin in Rat Model of Monocrotaline-Induced Pulmonary Arterial Hypertension: Protective Effect of Canstatin on Right Ventricular Remodeling

Pulmonary arterial hypertension (PAH) is a progressive disease which causes right ventricular (RV) failure. Canstatin, a C-terminal fragment of type IV collagen α2 chain, is expressed in various rat organs. However, the expression level of canstatin in plasma and organs during PAH is still unclear. We aimed to clarify it and further investigated the protective effects of canstatin in a rat model of monocrotaline-induced PAH. Cardiac functions were assessed by echocardiography. Expression levels of canstatin in plasma and organs were evaluated by enzyme-linked immunosorbent assay and Western blotting, respectively. PAH was evaluated by catheterization. RV remodeling was evaluated by histological analyses. Real-time polymerase chain reaction was performed to evaluate RV remodeling-related genes. The plasma concentration of canstatin in PAH rats was decreased, which was correlated with a reduction in acceleration time/ejection time ratio and an increase in RV weight/body weight ratio. The protein expression of canstatin in RV, lung and kidney was decreased in PAH rats. While recombinant canstatin had no effect on PAH, it significantly improved RV remodeling, including hypertrophy and fibrosis, and prevented the increase in RV remodeling-related genes. We demonstrated that plasma canstatin is decreased in PAH rats and that administration of canstatin exerts cardioprotective effects.