Bile acid metabolism in health and ageing-related diseases

Bile acids (BAs) have surpassed their traditional roles as lipid solubilizers and regulators of BA homeostasis to emerge as important signalling molecules. Recent research has revealed a connection between microbial dysbiosis and metabolism disruption of BAs, which in turn impacts ageing-related diseases. The human BAs pool is primarily composed of primary BAs and their conjugates, with a smaller proportion consisting of secondary BAs. These different BAs exert complex effects on health and ageing-related diseases through several key nuclear receptors, such as farnesoid X receptor and Takeda G protein-coupled receptor 5. However, the underlying molecular mechanisms of these effects are still debated. Therefore, the modulation of signalling pathways by regulating synthesis and composition of BAs represents an interesting and novel direction for potential therapies of ageing-related diseases. This review provides an overview of synthesis and transportion of BAs in the healthy body, emphasizing its dependence on microbial community metabolic capacity. Additionally, the review also explores how ageing and ageing-related diseases affect metabolism and composition of BAs. Understanding BA metabolism network and the impact of their nuclear receptors, such as farnesoid X receptor and G protein-coupled receptor 5 agonists, paves the way for developing therapeutic agents for targeting BA metabolism in various ageing-related diseases, such as metabolic disorder, hepatic injury, cardiovascular disease, renal damage and neurodegenerative disease.

High urea induces anxiety disorders associated with chronic kidney disease by promoting abnormal proliferation of OPC in amygdala

Chronic kidney disease (CKD) with anxiety disorder is of a great concern due to its high morbidity and mortality. Urea, as an important toxin in CKD, is not only a pathological factor for complications in patients with CKD, but also is accumulated in the brain of aging and neurodegenerative diseases. However, the pathological role and underlying regulatory mechanism of urea in CKD related mood disorders have not been well established. We previously reported a depression phenotype in mice with abnormal urea metabolism. Since patients with depression are more likely to suffer from anxiety, we speculate that high urea may be an important factor causing anxiety in CKD patients. In adenine-induced CKD mouse model and UT-B-/- mouse model, multiple behavioral studies confirmed that high urea induces anxiety-like behavior. Single-cell transcriptome revealed that down-regulation of Egr1 induced compensatory proliferation of oligodendrocyte progenitor cells (OPC). Myelin-related signaling pathways of oligodendrocytes (OL) were change significant in the urea accumulation amygdala. The study showed that high urea downregulated Egr1 with subsequent upregulation of ERK pathways in OPCs. These data indicate that the pathological role and molecular mechanism of high urea in CKD-related anxiety, and provide objective serological indicator and a potential new drug target for the prevention and treatment of anxiety in CKD patients.

TGF-β as A Master Regulator of Aging-Associated Tissue Fibrosis

Fibrosis is the abnormal accumulation of extracellular matrix proteins such as collagen and fibronectin. Aging, injury, infections, and inflammation can cause different types of tissue fibrosis. Numerous clinical investigations have shown a correlation between the degree of liver and pulmonary fibrosis in patients and telomere length and mitochondrial DNA content, both of which are signs of aging. Aging involves the gradual loss of tissue function over time, which results in the loss of homeostasis and, ultimately, an organism's fitness. A major feature of aging is the accumulation of senescent cells. Senescent cells abnormally and continuously accumulate in the late stages of life, contributing to age-related fibrosis and tissue deterioration, among other aging characteristics. Furthermore, aging generates chronic inflammation, which results in fibrosis and decreases organ function. This finding suggests that fibrosis and aging are closely related. The transforming growth factor-beta (TGF-β) superfamily plays a crucial role in the physiological and pathological processes of aging, immune regulation, atherosclerosis, and tissue fibrosis. In this review, the functions of TGF-β in normal organs, aging, and fibrotic tissues is discussed: TGF-β signalling is altered with age and is an indicator of pathology associated with tissue fibrosis. In addition, this review discusses the potential targeting of noncoding.

Hexarelin alleviates apoptosis on ischemic acute kidney injury via MDM2/p53 pathway

INTRODUCTION

Hexarelin exhibits significant protection against organ injury in models of ischemia/reperfusion (I/R)-induced injury (IRI). Nevertheless, the impact of Hexarelin on acute kidney injury (AKI) and its underlying mechanism remains unclear. In this study, we investigated the therapeutic potential of Hexarelin in I/R-induced AKI and elucidated its molecular mechanisms.

METHODS

We assessed the protective effects of Hexarelin through both in vivo and in vitro experiments. In the I/R-induced AKI model, rats were pretreated with Hexarelin at 100 μg/kg/d for 7 days before being sacrificed 24 h post-IRI. Subsequently, kidney function, histology, and apoptosis were assessed. In vitro, hypoxia/reoxygenation (H/R)-induced HK-2 cell model was used to investigate the impact of Hexarelin on apoptosis in HK-2 cells. Then, we employed molecular docking using a pharmmapper server and autodock software to identify potential target proteins of Hexarelin.

RESULTS

In this study, rats subjected to I/R developed severe kidney injury characterized by tubular necrosis, tubular dilatation, increased serum creatinine levels, and cell apoptosis. However, pretreatment with Hexarelin exhibited a protective effect by mitigating post-ischemic kidney pathological changes, improving renal function, and inhibiting apoptosis. This was achieved through the downregulation of conventional apoptosis-related genes, such as Caspase-3, Bax and Bad, and the upregulation of the anti-apoptotic protein Bcl-2. Consistent with the in vivo results, Hexarelin also reduced cell apoptosis in post-H/R HK-2 cells. Furthermore, our analysis using GSEA confirmed the essential role of the apoptosis pathway in I/R-induced AKI. Molecular docking revealed a strong binding affinity between Hexarelin and MDM2, suggesting the potential mechanism of Hexarelin's anti-apoptosis effect at least partially through its interaction with MDM2, a well-known negative regulator of apoptosis-related protein that of p53. To validate these findings, we evaluated the relative expression of MDM2 and p53 in I/R-induced AKI with or without Hexarelin pre-administration and observed a significant suppression of MDM2 and p53 by Hexarelin in both in vivo and in vitro experiments.

CONCLUSION

Collectively, Hexarelin was identified as a promising medication in protecting apoptosis against I/R-induced AKI.

Targeted VEGFA therapy in regulating early acute kidney injury and late fibrosis

Damage to peritubular capillaries is a key process that contributes to acute kidney injury (AKI) progression. Vascular endothelial growth factor A (VEGFA) plays a critical role in maintaining the renal microvasculature. However, the physiological role of VEGFA in various AKI durations remains unclear. A severe unilateral ischemia‒reperfusion injury model was established to provide an overview of VEGFA expression and the peritubular microvascular density from acute to chronic injury in mouse kidneys. Therapeutic strategies involving early VEGFA supplementation protecting against acute injury and late anti-VEGFA treatment for fibrosis alleviation were analyzed. A proteomic analysis was conducted to determine the potential mechanism of renal fibrosis alleviation by anti-VEGFA. The results showed that two peaks of extraglomerular VEGFA expression were observed during AKI progression: one occurred at the early phase of AKI, and the other occurred during the transition to chronic kidney disease (CKD). Capillary rarefaction progressed despite the high expression of VEGFA at the CKD stage, and VEGFA was associated with interstitial fibrosis. Early VEGFA supplementation protected against renal injury by preserving microvessel structures and counteracting secondary tubular hypoxic insults, whereas late anti-VEGFA treatment attenuated renal fibrosis progression. The proteomic analysis highlighted an array of biological processes related to fibrosis alleviation by anti-VEGFA, which included regulation of supramolecular fiber organization, cell-matrix adhesion, fibroblast migration, and vasculogenesis. These findings establish the landscape of VEGFA expression and its dual roles during AKI progression, which provides the possibility for the orderly regulation of VEGFA to alleviate early acute injury and late fibrosis.

Moshen granule ameliorates membranous nephropathy by blocking intrarenal renin-angiotensin system signalling via the Wnt1/β-catenin pathway

BACKGROUND

Membranous nephropathy (MN) is one of the cardinal causes of nephrotic syndrome in adults, but an adequate treatment regimen is lacking.

PURPOSE

We assessed the effect of Moshen granule (MSG) on patients with MN and cationic bovine serum albumin (CBSA)-induced rats. We further identified the bioactive components of MSG and revealed the underlying molecular mechanism of its renoprotective effects.

METHODS

We determined the effect of MSG on patients with MN and CBSA-induced rats and its components on podocyte injury in zymosan-activated serum (ZAS)-elicited podocytes and revealed their regulatory mechanism on the Wnt/β-catenin/renin-angiotensin system (RAS) signalling axis.

RESULTS

MSG treatment improved renal function and reduced proteinuria in MN patients and significantly reduced proteinuria and preserved the protein expression of podocin, nephrin, podocalyxin and synaptopodin in CBSA-induced MN rats. Mechanistically, MSG treatment significantly inhibited the protein expression of angiotensinogen, angiotensin converting enzyme and angiotensin II type 1 receptor, which was accompanied by inhibition of the protein expression of Wnt1 and β-catenin and its downstream gene products, including Snail1, Twist, matrix metalloproteinase-7, plasminogen activator inhibitor-1 and fibroblast-specific protein 1, in CBSA-induced MN rats. We further identified 81 compounds, including astragaloside IV (AGS), calycosin, barleriside A and geniposidic acid, that preserve the podocyte-specific protein expression in ZAS-induced podocytes. Among these four compounds, AGS exhibited the strongest inhibitory effects on podocyte protein expression. AGS treatment significantly inhibited the protein expression of RAS components and Wnt1 and β-catenin and its downstream gene products in ZAS-induced podocytes. In contrast, the inhibitory effect of AGS on podocyte-specific proteins, β-catenin downstream gene products and RAS components was partially abolished in ZAS-induced podocytes treated with ICG-001 and β-catenin siRNA.

CONCLUSION

This study first demonstrates that AGS mitigates podocyte injury by inhibiting the activation of RAS signalling via the Wnt1/β-catenin pathway by both pharmacological and genetic methods. Therefore, AGS might be considered a new β-catenin inhibitor that inhibits the Wnt1/β-catenin pathway to retard MN in patients.

Shen Qi Wan attenuates renal interstitial fibrosis through upregulating AQP1

Renal interstitial fibrosis (RIF) is the crucial pathway in chronic kidney disease (CKD) leading to the end-stage renal failure. However, the underlying mechanism of Shen Qi Wan (SQW) on RIF is not fully understood. In the current study, we investigated the role of Aquaporin 1 (AQP1) in SQW on tubular epithelial-to-mesenchymal transition (EMT). A RIF mouse model induced by adenine and a TGF-β1-stimulated HK-2 cell model were etablished to explore the involvement of AQP 1 in the protective effect of SQW on EMT in vitro and in vivo. Subsequently, the molecular mechanism of SQW on EMT was explored in HK-2 cells with AQP1 knockdown. The results indicated that SQW alleviated kidney injury and renal collagen deposition in the kidneys of mice induced by adenine, increased the protein expression of E-cadherin and AQP1 expression, and decreased the expression of vimentin and α-smooth muscle actin (α-SMA). Similarly, treatmement with SQW-containing serum significantly halted EMT process in TGF-β1 stimulated HK-2 cells. The expression of snail and slug was significantly upregulated in HK-2 cells after knockdown of AQP1. AQP1 knockdown also increased the mRNA expression of vimentin and α-SMA, and decreased the expression of E-cadherin. The protein expression of vimentin increased, while the expression of E-cadherin and CK-18 significantly decreased after AQP1 knockdown in HK-2 cells. These results revealed that AQP1 knockdown promoted EMT. Furthermore, AQP1 knockdown abolished the protective effect of SQW-containing serum on EMT in HK-2 cells. In sum, SQW attentuates EMT process in RIF through upregulation of the expression of AQP1.

Metabolomic profiles in serum and urine uncover novel biomarkers in children with nephrotic syndrome

BACKGROUND

Nephrotic syndrome is common in children and adults worldwide, and steroid-sensitive nephrotic syndrome (SSNS) accounts for 80%. Aberrant metabolism involvement in early SSNS is sparsely studied, and its pathogenesis remains unclear. Therefore, the goal of this study was to investigate the changes in initiated SSNS patients-related metabolites through serum and urine metabolomics and discover the novel potential metabolites and metabolic pathways.

METHODS

Serum samples (27 SSNS and 56 controls) and urine samples (17 SSNS and 24 controls) were collected. Meanwhile, the non-targeted analyses were performed by ultra-high-performance liquid chromatography-quadrupole time of flight-mass spectrometry (UHPLC-QTOF-MS) to determine the changes in SSNS. We applied the causal inference model, the DoWhy model, to assess the causal effects of several selected metabolites. An ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to validate hits (D-mannitol, dulcitol, D-sorbitol, XMP, NADPH, NAD, bilirubin, and α-KG-like) in 41 SSNS and 43 controls. In addition, the metabolic pathways were explored.

RESULTS

Compared to urine, the metabolism analysis of serum samples was more clearly discriminated at SSNS. 194 differential serum metabolites and five metabolic pathways were obtained in the SSNS group. Eight differential metabolites were identified by establishing the diagnostic model for SSNS, and four variables had a positive causal effect. After validation by targeted MS, except XMP, others have similar trends like the untargeted metabolic analysis.

CONCLUSION

With untargeted metabolomics analysis and further targeted quantitative analysis, we found seven metabolites may be new biomarkers for risk prediction and early diagnosis for SSNS.

USP22 aggravated diabetic renal tubulointerstitial fibrosis progression through deubiquitinating and stabilizing Snail1

Renal tubulointerstitial fibrosis (TIF) is one of the main pathological changes induced by diabetic kidney disease (DKD), and epithelial-to-mesenchymal transition (EMT) induced by high glucose (HG) can promote TIF. Our previous study has shown that ubiquitin-specific protease 22 (USP22) could affect the process of DKD by deubiquitinating and stabilizing Sirt1 in glomerular mesangial cells. However, whether USP22 could regulate EMT occurrence in renal tubular epithelial cells and further aggravate the pathological process of TIF in DKD remains to be elucidated. In this study, we found that USP22 expression was upregulated in kidney tissues of db/db mice and HG-treated NRK-52E cells. In vitro, USP22 overexpression promoted the EMT process of NRK-52E cells stimulated by HG and further increased the levels of extracellular matrix (ECM) components such as fibronectin, Collagen I, and Collagen Ⅳ. Meanwhile, USP22 deficiency exhibited the opposite effects. Mechanism studies showed that USP22, depending on its deubiquitinase activity, deubiquitinated and stabilized the EMT transcriptional factor Snail1. In vivo experiment showed that interfering with USP22 could improve the renal pathological damages and renal function of the db/db spontaneous diabetic mice by decreasing Snail1 expression, which could inhibit EMT occurrence, and reduce the production of ECM components. These results suggested that USP22 could accelerate renal EMT and promote the pathological progression of diabetic TIF by deubiquitinating Snail1, providing an experimental basis for using USP22 as a potential target for DKD.

Protective effect of selenomethionine on kidney injury induced by ochratoxin A in rabbits

The purpose of this study was to investigate the protective effect and mechanism of selenomethionine (SeMet) on ochratoxin A (OTA)-induced nephrotoxicity in rabbits. In total, sixty Ira rabbits were randomly divided into 5 groups (the control group, OTA group, 0. 2 mg/kg SeMet + OTA group, 0. 4 mg/kg SeMet + OTA group, and 0. 6 mg/kg SeMet + OTA group). The rabbits were fed diets supplemented with different doses of SeMet for 21 days and given 0. 2 mg/kg OTA starting on day 15 for a week. The results showed that the SeMet supplementation could improve the changes in blood physiological indices and renal function decline caused by OTA poisoning, and alleviate pathological kidney injury in the rabbits. SeMet also increased the activities of total antioxidant capacity, superoxide dismutase, and glutathione peroxidase, and decreased the contents of malondialdehyde and reactive oxygen species and the expression of interleukin-1β, interleukin-6, and tumor necrosis factor-α in the damaged kidneys of the rabbits. In addition, the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream gene heme oxygenase 1 (HO-1) was also inhibited after OTA poisoning, while SeMet activated the Nrf2 signaling pathway and enhanced the expression of Nrf2 and the downstream gene HO-1. In conclusion, SeMet protected against kidney injury caused by OTA in rabbits, and the mechanism may be the activation of the Nrf2 signaling pathway.

Naringin abrogates angiotensin-converting enzyme (ACE) activity and podocin signalling pathway in cobalt chloride-induced nephrotoxicity and hypertension

PurposeThe persistent and alarming rates of increase in cardiovascular and renal diseases caused by chemicals such as cobalt chloride (CoCl₂) in mammalian tissues have led to the use of various drugs for the treatment of these diseases. This study aims at evaluating the nephron-protective action of Naringin (NAR), a metal-chelating antioxidant against CoCl₂-induced hypertension and nephrotoxicity.MethodsForty-two male Wistar rats were randomly distributed to seven rats of six groups and classified into Group A (Control), Group B (300 part per million; ppm CoCl₂), Group C (300 ppm CoCl₂ + 80 mg/kg NAR), Group D (300 ppm CoCl₂ + 160 mg/kg NAR), Group E (80 mg/kg NAR), and Group F (160 mg/kg NAR). NAR and CoCl₂ were administered via oral gavage for seven days. Biomarkers of renal damage, oxidative stress, antioxidant status, blood pressure parameters, immunohistochemistry of renal angiotensin-converting enzyme and podocin were determined.ResultsCobalt chloride intoxication precipitated hypertension, renal damage, and oxidative stress. Immunohistochemistry revealed higher expression of angiotensin-converting enzyme (ACE) and podocin in rats administered only CoCl₂.ConclusionTaken together, the antioxidant and metal-chelating action of Naringin administration against cobalt chloride-induced renal damage and hypertension could be through abrogation of angiotensin-converting enzyme and podocin signalling pathway.

Transforming growth factor-β signaling: From tissue fibrosis to therapeutic opportunities

Fibrosis refers to the excessive deposition of extracellular matrix components in the processes of wound repair or tissue regeneration after tissue damage. Fibrosis occurs in various organs such as lung, heart, liver, and kidney tissues, resulting in the failure of organ structural integrity and its functional impairment. It has long been thought to be relentlessly progressive and irreversible process, but both preclinical models and clinical trials in multiorgans have shown that fibrosis is a highly dynamic process. Transforming growth factor-beta (TGF-β) is a superfamily of related growth factors. Many studies have described that activation of profibrotic TGF-β signaling promotes infiltration and/or proliferation of preexisting fibroblasts, generation of myofibroblasts, extracellular matrix deposition, and inhibition of collagenolysis, which leads to fibrosis in the pathological milieu. This review describes the effect of TGF-β signaling in fibrotic-associate lung, heart, liver, and kidney tissues, followed by a detailed discussion of canonical and non-canonical TGF-β signaling pathway. In addition, this review also discusses therapeutic options by using natural products and chemical agents, for targeting tissue fibrosis via modulating TGF-β signaling to provide a more specific concept-driven therapy strategy for multiorgan fibrosis.

Neoxanthin alleviates the chronic renal failure-induced aging and fibrosis by regulating inflammatory process

Chronic renal failure (CRF) refers to progressive renal damage caused by chronic kidney diseases (CKD). Dialysis therapy and kidney transplantation are the important treatment for CRF. However, due to the limitation of conditions, they cannot be widely utilized. At present, the treatment of renal failure is a worldwide problem in clinic. Therefore, in the current study, we investigated the potential therapeutic effects of neoxanthin on CFR-caused aging and fibrosis. In this work, the effects of neoxanthin on CRF were studied using experimental techniques such as biochemistry, immunohistochemistry and molecular biology. In vitro, neoxanthin alleviated the aging and oxidative damage of kidney cells. In vivo, we found that Neoxanthin could alleviate adenine-induced CRF. Neoxanthin also inhibited CRF-caused renal aging, fibrosis, oxidative stress and inflammation. These findings indicate that neoxanthin could delay the progression of CRF and alleviate CRF-induced aging and fibrosis. Collectively, we found that neoxanthin shows good potential to inhibit CRF-caused kidney aging and fibrosis, suggesting that neoxanthin may be used as a drug (or a functional food) for the treatment of CRF-related diseases.

Calycosin attenuates renal ischemia/reperfusion injury by suppressing NF-κB mediated inflammation via PPARγ/EGR1 pathway

Renal ischemia reperfusion injury (IRI) is a leading and common cause of acute kidney injury (AKI), and inflammation is a critical factor in ischemic AKI progression. Calycosin (CAL), a major active component of Radix astragali, has been reported to have anti-inflammatory effect in multiple organs. However, whether CAL can alleviate renal IRI and its mechanism remain uncertain. In the present study, a renal IRI model is established by bilateral renal pedicles occlusion for 35 min in male C57BL/6 mice, and the effect of CAL on renal IRI is measured by serum creatinine and pathohistological assay. Hypoxia/reoxygenation (H/R) stimulated human renal tubular epithelial cells HK-2 were applied to explore the regulatory mechanisms of CAL. Luciferase reporter assay and molecular docking were applied to identify the CAL's target protein and pathway. In the mice with renal IRI, CAL dose dependently alleviated the renal injury and decreased nuclear factor kappa B (NF-κB) mediated inflammatory response. Bioinformatics analysis and experiments showed that early growth response 1 (EGR1) increased in mice with renal IRI and promoted NF-κB mediated inflammatory processes, and CAL dose-dependably reduced EGR1. Through JASPAR database and luciferase reporter assay, peroxisome proliferator-activated receptor γ (PPARγ) was predicted to be a transcription factor of EGR1 and repressed the expression of EGR1 in renal tubular epithelial cells. CAL could increase PPARγ in a dose dependent manner in mice with renal IRI and molecular docking predicted CAL could bind stably to PPARγ. In HK-2 cells after H/R, CAL increased PPARγ, decreased EGR1, and inhibited NF-κB mediated inflammatory response. However, PPARγ knockdown by siRNA transfection abrogated the anti-inflammation therapeutic effect of CAL. CAL produced a protective effect on renal IRI by attenuating NF-κB mediated inflammatory response via PPARγ/EGR1 pathway.

Carvacrol preserves antioxidant status and attenuates kidney fibrosis via modulation of TGF-β1/Smad signaling and inflammation

Chronic kidney disease (CKD) with diverse aetiologies is emerging as a challenging kidney disorder associated with inflammation and interstitial fibrosis. Carvacrol (CVL) is a bioactive monoterpenoid found abundantly in oregano, thyme, and bergamot, having diverse pharmacological benefits. However, the effect of CVL against fibrotic changes in the kidneys is poorly defined. In the current study, a robust mouse model of renal fibrosis induced through unilateral ureteral obstruction (UUO) is used to investigate the anti-fibrotic activity of CVL. The mice were treated with two different oral doses of CVL (25 mg kg^-1 and 50 mg kg^-1 body weight) for 14 consecutive days. The UUO induction resulted in impaired renal function, severe histological damage, and collagen deposition in the obstructed kidney. Our findings revealed profound activation of transforming growth factor-β1 (TGF-β1) and NF-κB (p65) signaling along with the downregulation of antioxidant proteins, nuclear factor-erythroid factor 2-related factor 2 (Nrf2), NAD(P)H: quinone oxidoreductase 1 (NQO1), and superoxide dismutase (SOD) in the obstructed kidney. CVL administration markedly recovered antioxidant proteins and kidney histological changes. In addition, CVL blunted the NF-κB (p65) phosphorylation and reduced the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and cyclooxygenase 2 (COX-2) compared to the UUO control group. CVL also alleviated the increased fibrotic protein levels of TGF-β1, pSmad2/3, collagen I, collagen III, fibronectin, and myofibroblast activation and epithelial-mesenchymal transition (EMT) markers, including alpha-smooth muscle actin (α-SMA), E-cadherin, and vimentin in the kidneys. Findings from in vitro study also confirmed that CVL inhibits the EMT process in TGF-β1 stimulated renal tubular epithelial cells (NRK 52E cells). Collectively, our findings indicate that CVL administration attenuates kidney fibrosis by targeting oxidative stress and inflammation.

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.

Shenkang injection improves chronic kidney disease by inhibiting multiple renin-angiotensin system genes by blocking the Wnt/β-catenin signalling pathway

Chronic kidney disease (CKD) is a major worldwide public health problem. The increase in the number of patients with CKD and end-stage kidney disease requesting renal dialysis or transplantation will progress to epidemic proportions in the next several decades. Although blocking the renin-angiotensin system (RAS) has been used as a first-line standard therapy in patients with hypertension and CKD, patients still progress towards end-stage kidney disease, which might be closely associated with compensatory renin expression subsequent to RAS blockade through a homeostatic mechanism. The Wnt/β-catenin signalling pathway is the master upstream regulator that controls multiple intrarenal RAS genes. As Wnt/β-catenin regulates multiple RAS genes, we inferred that this pathway might also be implicated in blood pressure control. Therefore, discovering new medications to synchronously target multiple RAS genes is necessary and essential for the effective treatment of patients with CKD. We hypothesized that Shenkang injection (SKI), which is widely used to treat CKD patients, might ameliorate CKD by inhibiting the activation of multiple RAS genes via the Wnt/β-catenin signalling pathway. To test this hypothesis, we used adenine-induced CKD rats and angiotensin II (AngII)-induced HK-2 and NRK-49F cells. Treatment with SKI inhibited renal function decline, hypertension and renal fibrosis. Mechanistically, SKI abrogated the increased protein expression of multiple RAS elements, including angiotensin-converting enzyme and angiotensin II type 1 receptor, as well as Wnt1, β-catenin and downstream target genes, including Snail1, Twist, matrix metalloproteinase-7, plasminogen activator inhibitor-1 and fibroblast-specific protein 1, in adenine-induced rats, which was verified in AngII-induced HK-2 and NRK-49F cells. Similarly, our results further indicated that treatment with rhein isolated from SKI attenuated renal function decline and epithelial-to-mesenchymal transition and repressed RAS activation and the hyperactive Wnt/β-catenin signalling pathway in both adenine-induced rats and AngII-induced HK-2 and NRK-49F cells. This study first revealed that SKI repressed epithelial-to-mesenchymal transition by synchronously targeting multiple RAS elements by blocking the hyperactive Wnt/β-catenin signalling pathway.