Circ_0000524/miR-500a-5p/CXCL16 axis promotes podocyte apoptosis in membranous nephropathy

Hsa_circ_0001162 Inhibition Alleviates High Glucose-Induced Human Podocytes Injury by the miR-149-5p/MMP9 Signaling Pathway

Emerging evidences suggested that circular RNAs (circRNAs) are involved in diabetic nephropathy (DN). Accumulating evidence had suggested that the degree of podocyte is a major prognostic determinant of DN progression. However, the function and in-depth mechanisms of hsa_circ_0001162 in podocyte injury of DN remain unclear. Hsa_circ_0001162 expression was detected by real-time quantitative PCR (RT-qPCR) in peripheral blood of DN patients and high glucose-induced podocytes injury model. The cell counting kit 8, 5-ethynyl-2'-deoxyuridine, flow cytometry with Annexin V-FITC/PI staining, caspase-3 activity assay Kit, enzyme linked immunosorbent assay (ELISA), RT-qPCR and western blotting were used to evaluate the effect of hsa_circ_0001162 / miR-149-5p / MMP9 axis on high glucose-induced podocyte injury. Mechanistically, dual luciferase reporter was used to confirm the relationship of miR-149-5p and hsa_circ_0001162 or MMP9. Furthermore, RNA-pull down and immunoprecipitation assay were implemented to verify the potential regulatory effects of EIF4A3 on biogenesis of hsa_circ_0001162. Our results showed that hsa_circ_0001162 was highly expressed in peripheral blood of DN patients and high glucose-induced podocytes injury model, and the knockdown of hsa_circ_0001162 increased the proliferation, inhibited the apoptosis, and suppressed inflammatory response in high glucose-induced podocytes injury. Mechanism studies demonstrated that EIF4A3 bound with flanking sequences of hsa_circ_0001162 to promote hsa_circ_0001162 expression, upregulated hsa_circ_0001162 increased the MMP9 expression via sponging miR-149-5p, thus aggravating the high glucose-induced podocytes injury. Overall, our data demonstrated that knockdown of hsa_circ_0001162 inhibited high glucose-induced podocytes injury by regulating miR-149-5p/MMP9 axis, and intervention of hsa_circ_0001162/miR-149-5p/MMP9 axis may be a potentially promising therapeutic strategy for podocyte injury in DN patients.

Network pharmacology and molecular docking predictions of the active compounds and mechanism of action of Huangkui capsule for the treatment of idiopathic membranous nephropathy

BACKGROUND

Huangkui Capsule is a single herbal concoction prepared from the flower of Abelmoschus manihot, which is used to treat idiopathic membranous nephropathy (IMN), a frequent pathologically damaging kidney condition. It has been widely utilized to treat a variety of renal disorders, including IMN, in clinical practice. However, the active compounds and mechanism of action underlying the anti-IMN effects of Huangkui Capsule remain unclear. In this study, we aimed to predict the potential active compounds and molecular targets of Huangkui Capsule for the treatment of IMN.

METHODS

The possible active components of Huangkui were located using the SymMap v2 database. The targets of these drugs were predicted using Swiss Target Prediction, while IMN-related genes with association scores under 5 were gathered from the GeneCards and DisGeNET databases. The common targets of the disease and the components were determined using VENNY 2.1. Using Cytoscape 3.8.0, a drug-disease network diagram was created. Molecular docking was carried out with Pymol, AutoDock Tools, and AutoDock Vina.

RESULTS

With 1260 IMN-related illness genes gathered from GeneCards and DisGeNET databases, we were able to identify 5 potentially active chemicals and their 169 target proteins in Huangkui. Based on degree value, the top 6 targets for Huangkui treatment of IMN were chosen, including AKT, MAPK3, PPARG, MMP9, ESR1, and KDR.

CONCLUSION

This work theoretically explains the mechanism of action of Huangkui Capsule in treating IMN and offers a foundation for using Huangkui Capsule in treating IMN in clinical settings. The findings require additional experimental validation.

Present and Future of IgA Nephropathy and Membranous Nephropathy Immune Monitoring: Insights from Molecular Studies

IgA Nephropathy (IgAN) and Membranous Nephropathy (MN) are primary immune-mediated glomerular diseases with highly variable prognosis. Current guidelines recommend that greater immunologic activity and worse prognosis should guide towards the best treatment in an individualized approach. Nevertheless, proteinuria and glomerular filtration rate, the current gold standards for prognosis assessment and treatment guidance in primary glomerular diseases, may be altered with chronic damage and nephron scarring, conditions that are not related to immune activity. In recent years, thanks to the development of new molecular technologies, among them genome-wide genotyping, RNA sequencing techniques, and mass spectrometry, we have witnessed an outstanding improvement in understanding the pathogenesis of IgAN and MN. In addition, recent genome-wide association studies have suggested potential targets for immunomodulating agents, stressing the need for the identification of specific biomarkers of immune activity. In this work, we aim to review current evidence and recent progress, including the more recent use of omics techniques, in the identification of potential biomarkers for immune monitoring in IgAN and MN.

Circ_RBM23 knockdown suppresses chemoresistance, proliferation, migration and invasion of sorafenib-resistant HCC cells through miR-338-3p/RAB1B axis

BACKGROUND

Circular RNA RNA-binding motif protein 23 (circ_RBM23; ID: hsa_circ_0000524) is a novel regulator in hepatocellular carcinoma (HCC). Herein, we planned to investigate its role in sorafenib resistance in HCC.

METHOD

Levels of circ_RBM23, microRNA (miR)-338-3p, Ras-related GTPase-trafficking protein (RAB1B), Snail and E-cadherin were detected by real-time quantitative PCR and western blotting. Sorafenib resistant (SR) HCC cells (Huh7/SR and SK-HEP-1/SR) were established by acquisition of sorafenib resistance, and cell functions were measured by MTT assay, Edu assay, colony formation assay, apoptosis assay, transwell assay, and in vivo xenograft formation assay. Crosslink between miR-338-3p and circ_RBM23 or RAB1B was confirmed by bioinformatics analysis and dual-luciferase reporter assay.

RESULTS

Circ_RBM23 upregulation was discovered in the tissues of SR patients and SR cells, which was accompanied with miR-338-3p downregulation and RAB1B upregulation. The 50% inhibitory concentration (IC₅₀) of sorafenib in SR cells was greatly suppressed by interfering circ_RBM23 or reinforcing miR-338-3p, allied with this was the inhibition of EdU-positive cell rate, colony formation and migration/invasion abilities under sorafenib treatment, as well as the enhancement of apoptotic rate. Moreover, circ_RBM23 inhibition delayed tumor growth of Huh7/SR cells under sorfanib treatment in vivo.

CONCLUSION

Circ_RBM23 promoted chemoresistance, malignant proliferation, migration and invasion of SR HCC cells by modulating miR-338-3p/RAB1B axis.

Myostatin silencing inhibits podocyte apoptosis in membranous nephropathy through Smad3/PKA/NOX4 signaling pathway

This article focuses on deciphering the effect of myostatin (MSTN) on podocyte apoptosis in membranous nephropathy (MN) and fathoming out its underlying mechanism. Rats received the intravenous injection of cationized-bovine serum albumin to induce MN in vivo, while angiotensin II (Ang II) was exposed to AB8/13 cells to induce MN model in vitro. The mRNA expression of MSTN was detected by qRT-PCR. The effects of MSTN silencing on MN model rats and cells were assessed by cell counting kit-8 assay, flow cytometry, hematoxylin and eosin staining, and TUNEL assay. The expressions of proteins related to apoptosis and Smad3/protein kinase A (PKA)/NADPH oxidase 4 (NOX4) signaling pathway were examined by western blot. As a result, MSTN was highly expressed in MN cell and rat models. Besides, knockdown of MSTN elevated the MN cell viability and dwindled apoptosis rate, as well as attenuated kidney injury in MN rats. Meanwhile, MSTN silencing lessened the expressions of phosphorylated (p)-Smad3 and Nox4, while boosting the p-PKA expression in MN rats and cells. Additionally, Smad3 overexpression reversed the above effects of MSTN silencing on Ang II-induced podocytes. In conclusion, MSTN knockdown restrains the podocyte apoptosis through regulating Smad3/PKA/NOX4 signaling pathway.

Integrated Network Pharmacology Analysis and Experimental Validation to Investigate the Molecular Mechanism of Triptolide in the Treatment of Membranous Nephropathy

BACKGROUND

Triptolide, a major active ingredient isolated from Tripterygium wilfordii Hook f., is effective in the treatment of membranous nephropathy (MN); however, its pharmacological mechanism of action has not yet been clarified. We applied an approach that integrated network pharmacology and experimental validation to systemically reveal the molecular mechanism of triptolide in the treatment of MN.

METHODS

First, potential targets of triptolide and the MN-related targets were collected from publicly available database. Then, based on a protein-protein interaction network as well as GO and KEGG pathway enrichment analyses, we constructed target-pathway networks to unravel therapeutic targets and pathways. Moreover, molecular docking was applied to validate the interactions between the triptolide and hub targets. Finally, we induced passive Heymann nephritis (PHN) rat models and validated the possible molecular mechanisms of triptolide against MN.

RESULTS

The network pharmacology results showed that 118 intersected targets were identified for triptolide against MN, including mTOR, STAT3, CASP3, EGFR and AKT1. Based on enrichment analysis, signaling pathways such as PI3K/AKT, MAKP, Ras and Rap1 were involved in triptolide treatment of MN. Furthermore, molecular docking confirmed that triptolide could bind with high affinity to the PIK3R1, AKT1 and mTOR, respectively. Then, in vivo experiments indicated that triptolide can reduce 24 h urine protein (P < 0.01) and protect against renal damage in PHN. Serum albumin level was significantly increased and total cholesterol, triglycerides, and low-density lipoprotein levels were decreased by triptolide (P < 0.05). Compared with PHN group, triptolide treatment regulated the PI3K/AKT/mTOR pathway according to Western blot analyses.

CONCLUSION

Triptolide could exert antiproteinuric and renoprotective effects in PHN. The therapeutic mechanism of triptolide may be associated with the regulation of PI3K/AKT/mTOR signaling pathway. This study demonstrates the pharmacological mechanism of triptolide in the treatment of MN and provides scientific evidence for basic and clinical research.

circMTND5 Participates in Renal Mitochondrial Injury and Fibrosis by Sponging MIR6812 in Lupus Nephritis

Recent studies have focused on nuclear-encoded circular RNAs (circRNAs) in kidney diseases, but little is known about mitochondrial circRNAs. Differentially expressed circRNAs were analyzed by RNA deep sequencing from lupus nephritis (LN) biopsies and normal human kidneys. In LN renal biopsies, the most downregulated circRNA was circMTND5, which is encoded in the mitochondrial genome. We quantitated circMTND5 by qPCR and localized by fluorescence in situ hybridization (FISH). Mitochondrial abnormalities were identified by electron microscopy. The expression of mitochondrial genes was decreased, and the expression of profibrotic genes was increased on qPCR and immunostaining. RNA binding sites for MIR6812 and circMTND5 were predicted. MIR6812 expression was increased by FISH and qPCR. In HK-2 cells and its mitochondrial fraction, the role of circMTND5 sponging MIR6812 was assessed by their colocalization in mitochondria on FISH, RNA immunoprecipitation, and RNA pulldown coupled with luciferase reporter assay. circMTND5 knockdown upregulated MIR6812, decreased mitochondrial functional gene expression, and increased profibrotic gene expression. Overexpression of circMTND5 reversed these effects in hTGF-β stimulated HK-2 cells. Similar effects were observed in HK-2 cells with overexpression and with knockdown of MIR6812. We conclude that circMTND5 alleviates renal mitochondrial injury and kidney fibrosis by sponging MIR6812 in LN.

Membranous nephropathy: Systems biology-based novel mechanism and traditional Chinese medicine therapy

Membranous nephropathy (MN) is a renal-limited non-inflammatory autoimmune disease in the glomerulus, which is the second or third main cause of end-stage kidney diseases in patients with primary glomerulonephritis. Substantial achievements have increased our understanding of the aetiology and pathogenesis of murine and human MN. The identification of nephritogenic autoantibodies against neutral endopeptidase, phospholipase A₂ receptor (PLA₂R) and thrombospondin type-1 domain-containing 7A (THSD7A) antigens provide more specific concept-driven intervention strategies for treatments by specific B cell-targeting monoclonal antibodies to inhibit antibody production and antibody-antigen immune complex deposition. Furthermore, additional antibody specificities for antigens have been discovered, but their pathogenic effects are uncertain. Although anti-PLA₂R and anti-THSD7A antibodies as a diagnostic marker is widely used in MN patients, many questions including autoimmune response development, antigenic epitopes, and podocyte damage signalling pathways remain unresolved. This review describes the current available evidence regarding both established and novel molecular mechanisms based on systems biology approaches (gut microbiota, long non-coding RNAs, metabolite biomarkers and DNA methylation) in MN, with an emphasis on clinical findings. This review further summarizes the applications of traditional Chinese medicines such as Tripterygium wilfordii and Astragalus membranaceus for MN treatment. Lastly, this review considers how the identification of novel antibodies/antigens and unresolved questions and future challenges reveal the pathogenesis of MN.

Novel Biomarkers in Membranous Nephropathy

Membranous nephropathy (MN) is the main cause of adult nephrotic syndrome (NS). The pathogenesis of MN is complex and involves subepithelial immune complex deposition. Approximately one-third of patients with MN develop end-stage renal disease (ESRD). Timely diagnosis and reasonable intervention are the keys to improving prognosis. In recent years, with the development of high-throughput technologies, such as mass spectrometry (MS), microarray, and sequencing technologies, the discovery of biomarkers for MN has become an important area of research. In this review, we summarize the significant progress in biomarker identification. For example, a variety of podocyte target antigens and their autoantibodies have been reported. Phospholipase A2 receptor (PLA2R) is the most well-established target antigen in MN. PLA2R and its autoantibodies have clinical significance, with both diagnostic and therapeutic value for MN. In addition, a variety of new biomarkers, including proteins, metabolites, noncoding RNAs (ncRNAs), and immune cells, have recently been found. These MN-related biomarkers have great significance in the diagnosis, progression, prognosis, and treatment response of MN.

Serum protein signatures using aptamer-based proteomics for minimal change disease and membranous nephropathy

Introduction

Minimal change disease (MCD) and membranous nephropathy (MN) are glomerular diseases (glomerulonephritis [GN]) that present with the nephrotic syndrome. Although circulating PLA2R antibodies have been validated as a biomarker for MN, the diagnosis of MCD and PLA2R-negative MN still relies on the results of kidney biopsy or empirical corticosteroids in children. We aimed to identify serum protein biomarker signatures associated with MCD and MN pathogenesis using aptamer-based proteomics.

Methods

Quantitative SOMAscan proteomics was applied to the serum of adult patients with MCD (n = 15) and MN (n = 37) and healthy controls (n = 20). Associations between the 1305 proteins detected with SOMAscan were assessed using multiple statistical tests, expression pattern analysis, and systems biology analysis.

Results

A total of 208 and 244 proteins were identified that differentiated MCD and MN, respectively, with high statistical significance from the healthy controls (Benjamin-Hochberg [BH] P < 0.0001). There were 157 proteins that discriminated MN from MCD (BH P < 0.05). In MCD, 65 proteins were differentially expressed as compared with MN and healthy controls. When compared with MCD and healthy controls, 44 discriminatory proteins were specifically linked to MN. Systems biology analysis of these signatures identified cell death and inflammation as key pathways differentiating MN from MCD and healthy controls. Dysregulation of fatty acid metabolism pathways was confirmed in both MN and MCD as compared with the healthy subjects.

Conclusion

SOMAscan represents a promising proteomic platform for biomarker development in GN. Validation of a greater number of discovery biomarkers in larger patient cohorts is needed before these data can be translated for clinical care.

circRNA_0001679/miR-338-3p/DUSP16 axis aggravates acute lung injury

Acute lung injury (ALI) is a respiratory disorder characterized by acute respiratory failure. circRNA mus musculus (mmu)-circ_0001679 was reported overexpressed in septic mouse models of ALI. Here the function of circ_0001679 in sepsis-induced ALI was investigated. In vitro models and animal models with ALI were, respectively, established in mouse lung epithelial (MLE)-12 cells and C57BL/6 mice. Pulmonary specimens were harvested for examination of the pathological changes. The pulmonary permeability was examined by wet-dry weight (W/D) ratio and lung permeability index. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in the bronchoalveolar lavage fluid (BALF), the lung tissues, and the supernatant of MLE-12 cells were measured by enzyme linked immunosorbent assay . Apoptosis was determined by flow cytometry. Bioinformatics analysis and luciferase reporter assay were used to assess the interactions between genes. We found that circ_0001679 was overexpressed in lipopolysaccharide (LPS)-stimulated MLE-12 cells. circ_0001679 knockdown suppressed apoptosis and proinflammatory cytokine production induced by LPS. Moreover, circ_0001679 bound to mmu-miR-338-3p and miR-338-3p targeted dual-specificity phosphatases 16 (DUSP16). DUSP16 overexpression reversed the effect of circ_0001679 knockdown in LPS-stimulated MLE-12 cells. Furthermore, circ_0001679 knockdown attenuated lung pathological changes, reduced pulmonary microvascular permeability, and suppressed inflammation in ALI mice. Overall, circ_0001679 knockdown inhibits sepsis-induced ALI progression through the miR-338-3p/DUSP16 axis.

CircRNAs as Potential Blood Biomarkers and Key Elements in Regulatory Networks in Gastric Cancer

Gastric cancer (GC) is the fifth most common type of cancer and the third leading cause of cancer death in the world. It is a disease that encompasses a variety of molecular alterations, including in non-coding RNAs such as circular RNAs (circRNAs). In the present study, we investigated hsa_circ_0000211, hsa_circ_0000284, hsa_circ_0000524, hsa_circ_0001136 and hsa_circ_0004771 expression profiles using RT-qPCR in 71 gastric tissue samples from GC patients (tumor and tumor-adjacent samples) and volunteers without cancer. In order to investigate the suitability of circRNAs as minimally invasive biomarkers, we also evaluated their expression profile through RT-qPCR in peripheral blood samples from patients with and without GC (n = 41). We also investigated the predicted interactions between circRNA-miRNA-mRNA and circRNA-RBP using the KEGG and Reactome databases. Overall, our results showed that hsa_circ_0000211, hsa_circ_0000284 and hsa_circ_0004771 presented equivalent expression profiles when analyzed by different methods (RNA-Seq and RT-qPCR) and different types of samples (tissue and blood). Further, functional enrichment results identified important signaling pathways related to GC. Thus, our data support the consideration of circRNAs as new, minimally invasive biomarkers capable of aiding in the diagnosis of GC and with great potential to be applied in clinical practice.

MicroRNAs: Potential mediators between particulate matter 2.5 and Th17/Treg immune disorder in primary membranous nephropathy

Primary membranous nephropathy (PMN), is an autoimmune glomerular disease and the main reason of nephrotic syndrome in adults. Studies have confirmed that the incidence of PMN increases yearly and is related to fine air pollutants particulate matter 2.5 (PM2.5) exposure. These imply that PM2.5 may be associated with exposure to PMN-specific autoantigens, such as the M-type receptor for secretory phospholipase A2 (PLA2R1). Emerging evidence indicates that Th17/Treg turns to imbalance under PM2.5 exposure, but the molecular mechanism of this process in PMN has not been elucidated. As an important indicator of immune activity in multiple diseases, Th17/Treg immune balance is sensitive to antigens and cellular microenvironment changes. These immune pathways play an essential role in the disease progression of PMN. Also, microRNAs (miRNAs) are susceptible to external environmental stimulation and play link role between the environment and immunity. The contribution of PM2.5 to PMN may induce Th17/Treg imbalance through miRNAs and then produce epigenetic affection. We summarize the pathways by which PM2.5 interferes with Th17/Treg immune balance and attempt to explore the intermediary roles of miRNAs, with a particular focus on the changes in PMN. Meanwhile, the mechanism of PM2.5 promoting PLA2R1 exposure is discussed. This review aims to clarify the potential mechanism of PM2.5 on the pathogenesis and progression of PMN and provide new insights for the prevention and treatment of the disease.

Sanqi Oral Solution Mitigates Proteinuria in Rat Passive Heymann Nephritis and Blocks Podocyte Apoptosis via Nrf2/HO-1 Pathway

Idiopathic membranous nephropathy (IMN) is the most common pathological type in adult nephrotic syndrome where podocyte apoptosis was found to mediate the development of proteinuria. Sanqi oral solution (SQ), an effective Chinese herbal preparation clinically used in treatment of IMN for decades, plays an important role in reducing proteinuria, but the underlying mechanisms have not been fully elucidated yet. The current study tested the hypothesis that SQ directly lessens proteinuria in IMN by reducing podocyte apoptosis. To investigate the effects of SQ, we established the experimental passive Heymann nephritis (PHN) rat model induced by anti-Fx1A antiserum in vivo and doxorubicin hydrochloride (ADR)-injured apoptotic podocyte model in vitro. SQ intervention dramatically reduced the level of proteinuria, together with the rat anti-rabbit IgG antibodies, complement C3, and C5b-9 deposition in glomerulus of PHN rats, accompanied by an elevation of serum albumin. Protein expression of synaptopodin, marker of podocyte injury, restored after SQ administration, whereas the electron microscopic analysis indicated that fusion of foot processes, and the pachynsis of glomerular basement membrane was markedly diminished. Further studies showed that SQ treatment could significantly inhibit podocyte apoptosis in PHN rats and ADR-injured podocytes, and protein levels of Cleaved Caspase-3 or the ratio of Bax/Bcl-2 were significantly decreased with SQ treatment in vivo or in vitro. Moreover, we found that the nuclear factor erythroid 2–related factor-2/heme oxygenase 1 (Nrf2/HO-1) pathway mediated the anti-apoptosis effective of SQ in podocyte. Thus, SQ mitigates podocyte apoptosis and proteinuria in PHN rats via the Nrf2/HO-1 pathway.

Integrative analysis of miRNA-mRNA network in idiopathic membranous nephropathy by bioinformatics analysis

Background

Currently, several specific antigens, M-type receptor for secretory phospholipase A2(PLA2R1), thrombospondin type-1 domain-containing 7A(THSD7A), and neural epidermal growth factor-like 1 protein (NELL-1), are discovered associated with the onset of idiopathic membranous nephropathy (IMN). But the pathomechanisms of IMN still need to be further claried. Understanding the mechanisms of IMN is required to improve its diagnosis and treatment.

Methods

In this study, we constructed miRNA regulatory networks to investigate IMN development. Moreover, miRNAs and mRNAs that were differentially expressed between Idiopathic Membranous Nephropathy (IMN) patients and normal controls were examined using the GSE115857 dataset and our previous sequence study. DE miRNA target genes were determined based on the FUNRICH software, starBase, miRDB, and miRWalk, and an miRNA-mRNA network was designed using DE-mRNAs that were negatively correlated with DE-miRNAs. The miRNA-mRNA network contained 228 miRNA-mRNA pairs. Thereafter, we conducted KEGG pathway, GO functional annotation, immune-related gene screening, protein interaction networks, and potential hub gene analyses. Furthermore, 10 miRNAs and 10 genes were determined and preliminarily validated using the validation dataset from GEO. Finally, we identified which pair may offer more accurate diagnosis and therapeutic targets for IMN.

Results

Two miRNA-mRNA pairs, miR-155-5p-FOS and miR-146a-5p-BTG2, were differentially expressed in IMN, indicating that these genes may affect IMN through immune processes. These findings may offer more accurate diagnoses and therapeutic targets for IMN.