Wnt/β-catenin links oxidative stress to podocyte injury and proteinuria

Nutritional management of pediatric nephrotic syndrome regarding oxidative stress and antioxidant balance

Pediatric nephrotic syndrome remains a complex clinical entity, with incompletely elucidated pathogenetic mechanisms, in which oxidative stress appears to have a substantial etiopathogenic role. Recent evidence supports the involvement of redox imbalance in podocyte damage, impaired glomerular function, and systemic decline. All this suggests that antioxidant interventions can favorably modulate the course of the disease. This narrative review aims to synthesize the most relevant data from the current literature on the interaction between oxidative stress and nephrotic syndrome in children, with a focus on the therapeutic potential of antioxidants. The analysis focuses on the molecular mechanisms by which oxidative stress contributes to the progression of renal dysfunction, the role of oxidative biomarkers in disease monitoring, and the ability of antioxidants to reduce the need for immunosuppressants and corticosteroids, thus contributing to the decrease in associated morbidity. The translational perspectives of antioxidant therapy are also discussed, in the context of the urgent need for effective adjuvant strategies with a safety profile superior to conventional therapies. By integrating these data, the paper supports the valorization of antioxidant interventions as an emerging direction in the management of pediatric nephrotic syndrome and substantiates the need for controlled clinical trials, with rigorous design, in this field.

Calycosin ameliorates albuminuria in nephrotic syndrome by targeting Notch1/Snail pathway

BACKGROUND

Heavy proteinuria is an important hallmark for kidney disease including nephrotic syndrome. Astragali Radix, a traditional Chinese herb, holds the potential to alleviate nephrotic syndrome; however, the underlying mechanism has not been completely clarified. The study aimed to explore the role of calycosin (C16H12O5), a major active component of Astragali Radix, in regulating adriamycin-induced proteinuria.

METHODS

A rat model of nephrotic syndrome was established through two adriamycin injections within two weeks (4 mg/kg for the first week and 2 mg/kg for the second week). After the induction of renal injury, 10 mg/kg or 20 mg/kg calycosin was intraperitoneally injected into rats for four weeks. Before euthanasia of rats, urine and blood samples were collected, and body weight was recorded. Then, 24 h urine protein content, kidney index, total cholesterol (TC), triglyceride (TG), as well as renal function indicators including blood urea nitrogen (BUN), serum creatinine (SCR), and urine albumin excretory rate (UAE) were measured. Hematoxylin-eosin staining for renal cortex tissues was performed to evaluate glomerular structural damage. TUNEL assay was performed to evaluate renal cell apoptosis. Western blotting was conducted to measure protein levels of podocyte-specific markers (podocin and nephrin), Notch1, and Snail in rat renal tissues.

RESULTS

Calycosin reversed adriamycin-induced increase in proteinuria content, kidney index, and concentrations of renal function indicators. Calycosin ameliorated glomerular structural damage, inflammatory cell infiltration, and basement membrane thickening in model rats. In addition, calycosin rescued the suppressive impact of adriamycin on renal cell apoptosis and protein levels of podocyte markers. The activated Notch1/Snail signaling in model rats was suppressed by calycosin intervention.

CONCLUSION

Calycosin exerts a protective role against adriamycin-induced nephrotic syndrome via inhibition of the Notch1/Snail signaling.

CLINICAL TRIAL DETAILS

Not applicable.

Wnt/β-catenin Pathway Aggravates Renal Fibrosis by Activating PUM2 Transcription to Repress YME1L-mediated Mitochondrial Homeostasis

Chronic kidney disease (CKD) affects more than 10% of people worldwide and is a leading cause of death. However, the pathogenesis of CKD remains elusive. The oxidative stress and mitochondrial membrane potential were detected using Enzyme-linked immunosorbent assay and JC-1 assay. Co-immunoprecipitation, dual-luciferase assay, chromatin IP, RNA IP and RNA pull-down were used to validate the interactions among genes. Exploiting a H2O2-induced fibrosis model in vitro, PUM2 expression was upregulated in Human kidney 2 cell (HK-2) cells, along with reduced cell viability, enhanced oxidative stress, impaired mitochondrial potential, and upregulated expressions of fibrosis-associated proteins. While PUM2 knockdown reversed the H2O2-induced injury in HK-2 cells. Mechanically, Wnt/β-catenin pathway activated PUM2 transcription via TCF4. It was further identified that Wnt/β-catenin pathway inhibited YME1L expression through PUM2-mediated destabilizing of its mRNA. PUM2 aggravated H2O2-induced oxidative stress, mitochondrial dysfunction, and renal fibrosis in HK-2 cell via suppressing YME1L expression. Our study revealed that Wnt/β-catenin aggravated renal fibrosis by activating PUM2 transcription to repress YME1L-mediated mitochondrial homeostasis, providing novel insights and potential therapeutic targets for the treatment of kidney fibrosis.

Adeno-Associated Virus-Mediated Dickkopf-1 Gene Transduction Reduces Silica-Induced Oxidative Stress and Silicosis in Mouse Lung

Aims: Silicosis is a lung disease caused by inhalation of silica particles. Both silica-induced oxidative stress and aberrant activation of the Wnt/β-catenin signaling pathway are potential targets in the treatment of pulmonary fibrosis. Dickkopf-1 (Dkk1), an inhibitor of the Wnt/β-catenin signaling pathway, plays regulatory roles in cell fate determination and immune responses. Our previous study demonstrated that adenoviral vector-mediated Dkk1 gene transfer alleviated the silica-induced mouse silicosis. However, the mechanism of therapeutic action of Dkk1 in silicosis is yet completely understood; together with the drawbacks of adenoviral vectors in gene therapy, we investigated the therapeutic effect and mechanisms of Dkk1 by employing an adeno-associated virus (AAV) vector in a silicosis mouse model. Results: The AAV vector could efficiently transduce the Dkk1 gene in silicotic lung during both the early and the late phases of disease, resulting in an alleviation of silicotic lesions, improvement of pulmonary compliance, and radiological findings. Mechanistic studies further demonstrated that the transduction of Dkk1 inhibited the silica-activated Wnt/β-catenin signaling and reduced the silica-induced reactive oxygen species-producing enzyme NADPH oxidase 4, oxidative stress regulator nuclear factor erythroid 2-related factor 2, and signaling molecules binding immunoglobulin protein and C/EBP homologous protein. In addition, shRNA-mediated downregulation of Dkk1 exacerbated the progression of silicosis in mice, whereas the treatment of ROS scavenger n-acetylcysteine showed a comparable mitigation of silicosis that was seen in the AAV-Dkk1 treatment. Innovation and Conclusion: This study provides an insight into the mechanism by which Dkk1 inhibits the silica-induced Wnt signaling and oxidative stress to mitigate the pathogenesis of lung silicosis and evidence of the potential of AAV-mediated Dkk1 gene transfer as an alternative approach in silicosis treatment. Antioxid. Redox Signal. 42, 529-546.

Zinc Deficiency Causes Glomerulosclerosis and Renal Interstitial Fibrosis Through Oxidative Stress and Increased Lactate Metabolism in Rats

Chronic kidney disease (CKD) is a highly prevalent condition characterized by renal fibrosis as its ultimate manifestation. Zinc deficiency is closely associated with CKD, evidenced by its link to renal fibrosis. Recently, local lactic acidosis has been demonstrated to promote renal fibrosis. Under zinc-deficient conditions, mitochondrial function is compromised and abnormal lactate metabolism might be induced potentially. However, it remains unclear whether zinc deficiency leads to renal fibrosis through local lactic acidosis. Zinc deficiency rat models were successfully established by feeding zinc-deficient diet. Western blot, qPCR, IHC, and other experiments were employed to investigate the key markers and molecular mechanisms of glomerulosclerosis and renal interstitial fibrosis. Our results indicate that zinc deficiency reduces specific markers of podocytes (podocalyxin, WT1, and nephrin) and activates the Wnt3a/β-catenin pathway, a key pathway in podocyte injury. Concurrently, glomerulosclerosis is indicated by increased urinary microalbumin and serum creatinine levels along with histological alteration observed through PAS and Masson staining in zinc-deficient rats. Furthermore, various degrees of upregulation for several markers of interstitial fibrosis including α-SMA, FN1 and collagen III are also revealed. These findings were further confirmed by Masson staining and IHC. Additionally, alterations in four markers in the EMT process, N-cadherin, E-cadherin, Vimentin, and snail, were consistent with expectations. We then confirmed the activation of the non-canonical TGF-β1 pathway known as the PI3K/AKT/mTOR pathway. An elevation in renal ROS levels accompanied by increased mitochondrial marker cytochrome C expression as well as an elevated NADH/NAD + ratio is also observed within the kidneys. Furthermore, the activity of both MMP/TIMP system and fibrinolytic system was abnormally enhanced under zinc deficiency conditions. Finally, we find zinc supplementation could significantly ameliorate relevant pathological alterations induced by zinc deficiency. These results collectively point that zinc deficiency causes podocyte damage ultimately resulting in glomerulosclerosis via accumulation of ROS and induces interstitial fibrosis via lactic acidosis.

Extractable organic matter from PM2.5 inhibits cardiomyocyte differentiation via AHR-mediated m6A RNA methylation

An ever-increasing body of research has established a link between maternal PM2.5 exposure and congenital heart diseases in the offspring, but the underlying mechanisms remain elusive. We recently reported that activation of the aryl hydrocarbon receptor (AHR) by PM2.5 causes aberrant m6A RNA methylation, leading to cardiac malformations in zebrafish embryos. We hypothesized that PM2.5 can disrupt heart development by inducing m6A methylation changes through AHR in mammals. In this study, we observed that extractable organic matters (EOM) from PM2.5 significantly impaired cardiomyocyte differentiation in embryonic rat cardiomyoblasts H9c2. Importantly, EOM exposure reduced global m6A methylation levels, which was reversed by AHR inhibition. Moreover, AHR, activated by EOM directly promoted the transcription of the demethylase, FTO, leading to global m6A hypomethylation. Specifically, AHR-induced FTO overexpression decreased the m6A methylation levels of Nox4 mRNA, resulting in NOX4 overexpression and subsequent oxidative stress in EOM samples. We then demonstrated that oxidative stress contributes to the inhibition of cardiomyocyte differentiation by EOM through suppression of Wnt/β-catenin signaling. In summary, our findings indicate that AHR activation by PM2.5 directly enhances the expression of the demethylase, FTO, which increases NOX4 expression by reducing its m6A methylation. The oxidative stress caused by NOX4 overexpression inhibits Wnt/β-catenin signaling, thereby compromising cardiomyocyte differentiation.

Estimated glucose processing rates and the association of chronic kidney disease and proteinuria in non-diabetic adults

The study, which was based on NHANES data (1999-2018), included 21,234 nondiabetic individuals aged 20 years and older to investigate the associations between the estimated glucose disposal rate (eGDR) and the risk of chronic kidney disease (CKD) and proteinuria. CKD was defined as an estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m2, and proteinuria was defined as a urinary albumin-to-creatinine ratio (UACR) exceeding 30 mg/g. The results demonstrated a significant inverse association between eGDR levels and the risks of CKD and proteinuria. After adjusting for potential confounders, the association between eGDR and CKD showed that, compared with those for Q1, the adjusted odds ratios (ORs) for Q2, Q3, and Q4 were 0.82 (95% CI: 0.61-1.11), 0.62 (95% CI: 0.39-0.98), and 0.55 (95% CI: 0.28-1.05), respectively. For the relationship between eGDR and proteinuria, the adjusted ORs for Q2, Q3, and Q4 were 0.54 (95% CI: 0.42-0.69), 0.41 (95% CI: 0.27-0.62), and 0.65 (95% CI: 0.43-0.98), respectively. Moreover, each standard deviation increase in eGDR was associated with a 9% reduction in CKD risk (OR: 0.91, 95% CI: 0.85-0.98) and a 13% reduction in proteinuria risk (OR: 0.87, 95% CI: 0.82-0.93). Further adjustments via restricted cubic spline (RCS) regression analysis revealed a significant nonlinear relationship between eGDR and CKD and a U-shaped relationship between eGDR and proteinuria. A lower risk of proteinuria was observed when eGDR levels were between 8.70 and 9.91. These findings, combined with those of previous studies, suggest that eGDR may serve as a potential alternative metric for insulin resistance (IR). In nondiabetic individuals, the eGDR was significantly associated with the risk of CKD and proteinuria, with a notable nonlinear pattern in these relationships.

Targeting the NF-κB p65-MMP28 axis: Wogonoside as a novel therapeutic agent for attenuating podocyte injury in diabetic nephropathy

BACKGROUND

Although recent progress provides mechanistic insights into diabetic nephropathy (DN), effective treatments remain scarce. DN, characterized by proteinuria and a progressive decline in renal function, primarily arises from podocyte injury, which impairs the glomerular filtration barrier. Wogonoside, a bioactive compound from the traditional Chinese herb Scutellaria baicalensis, has not been explored for its role in DN.

PURPOSE

This study aimed to investigate the therapeutic effects of wogonoside on podocyte injury in DN and its molecular mechanisms.

METHODS

The effects of wogonoside were examined using HFD/STZ-induced DN mouse models and high glucose (HG)-induced MPC-5 cells. Oxidative stress and inflammation markers were analyzed via Western blot and RT-qPCR. Wogonoside targets were identified through DARTS-MS and validated by SPR, molecular docking, alanine scanning, and CETSA. RNA-Seq analysis was employed to identify downstream targets, and the p65-MMP28 axis was explored through p65 knockdown and overexpression studies. The regulatory effect of p65 on Mmp28 was confirmed through dual-luciferase reporter assays and ChIP-qPCR.

RESULTS

Wogonoside treatment significantly reduced oxidative stress and inflammation in vivo and in vitro. Mechanistic studies identified p65 as a direct target of wogonoside, with SPR confirming a strong binding affinity (KD = 25.05 μM). Molecular docking and alanine scanning identified LYS221 as a critical binding site, which was further supported by CETSA using the p65 K221A mutant. RNA-Seq analysis revealed Mmp28 as a downstream effector of p65 involved in HG-induced podocyte injury. Functional studies demonstrated that wogonoside's protective effects on antioxidant and inflammatory pathways are mediated via the p65-MMP28 axis. Dual-luciferase reporter assays revealed that p65 regulates Mmp28 transcription, and ChIP-qPCR confirmed its direct promoter binding.

CONCLUSIONS

This study highlights wogonoside as a promising candidate for the treatment of podocyte injury in DN by targeting the NF-κB p65-MMP28 signaling axis. These findings provide novel insights into wogonoside's therapeutic potential and its molecular mechanisms, paving the way for its further development as a DN intervention.

Effect of β-catenin on hypoxia induced epithelial mesenchymal transition in HK-2 cells by regulating Brachyury

Background

Chronic kidney disease (CKD) has become a worldwide health problem and the incidence rate and mortality of CKD have been rising. Renal fibrosis (RF) is the final common pathological feature of almost all kinds of CKD and Epithelial-mesenchymal transition (EMT) is the predominant stage of RF. β-catenin is a key component of the Wnt signaling pathway, which has been fully proven to promote EMT. However, the underlying mechanism of β-catenin in EMT during the pathogenesis of RF is yet to be determined.

Objective

This study was designed to investigate the effects of β-catenin on RF-related EMT and further investigate its underlying mechanism.

Methods

Human proximal tubular epithelial cell (HK-2) was treated with hypoxia to construct RF injury cell model. The viability of cells was determined by CCK-8 assay. Immunofluorescence was used to detect α-SMA content. Expressions of β-catenin, Brachyury and RF-related proteins were measured by Western blot. The correlation between β-catenin and Brachyury was detected by ChIP-qPCR and dual luciferase reporter assay.

Results

We found β-catenin was overexpressed in hypoxia-induced HK-2 cells. In the RF cell model, silencing of β-catenin weakened the EMT and fibrogenesis activity of HK-2 cells. Mechanistically, we found β-catenin binds to T-cell factor (TCF) to activate Brachyury, which is a positive player in EMT. Further studies clarified that Brachyury was responsible for β-catenin-promoted the EMT and HK-2 cell injury under hypoxia condition.

Conclusions

Herein, we demonstrated that β-catenin is overexpressed in hypoxia-induced HK-2 cells and promotes EMT and cell injury via activating Brachyury. These findings suggest that targeting β-catenin/Brachyury may be an effective new approach for treating RF.

Cross-talk of renal cells through WNT signal transduction in the development of fibrotic kidneys

Chronic kidney disease (CKD) is a progressive condition that can lead to chronic renal failure (CRF), affecting 8%-16% of adults globally and imposing a significant burden on healthcare systems. Renal fibrosis is a key pathological hallmark of CKD progression and is linked to poor prognosis. Multiple signaling pathways, including WNT/β-catenin.Aberrant activation of WNT/β-catenin is implicated in renal fibrosis. The roles of renal macrophages and fibroblasts are pivotal in fibrosis progression and prognosis.

Potential Signal Pathways and Therapeutic Effects of Mesenchymal Stem Cell on Oxidative Stress in Diseases

Oxidative stress is a biological stress response produced by the destruction of redox equilibrium in aerobic metabolism in organisms, which is closely related to the occurrence of many diseases. Mesenchymal stem cells (MSCs) have been found to improve oxidative stress injury in a variety of diseases, including lung injury, liver diseases, atherosclerotic diseases, diabetes and its complications, ischemia-reperfusion injury, inflammatory bowel disease. The antioxidant stress capacity of MSCs may be a breakthrough in the treatment of these diseases. This review found that MSCs have the ability to resist oxidative stress, which may be achieved through MSCs involvement in mediating the Nrf2, MAPK, NF-κB, AMPK, PI3K/AKT and Wnt4/β-catenin signaling pathways.

Klotho enhances stability of chronic kidney disease atherosclerotic plaques by inhibiting GRK2/PLC-β-mediated endoplasmic reticulum stress in macrophages via modulation of the ROS/SHP1 pathway

Klotho has been importantly linked to atherosclerosis, but little is known about its specific role. This study investigates the mechanism by which Klotho enhances the stability of atherosclerotic plaques in chronic kidney disease. apoE-/- knockout mice and C57BL/6 mice underwent 5/6 nephrectomy and then klotho-NC and klotho-mimic groups were set up to be fed a high-fat chow diet and a dummy group was created to be fed a normal chow diet. qPCR detected relative mRNA expression of klotho. Oil Red O and HE staining assessed lipid proportion in the aorta. Masson staining evaluated renal failure pathology in mice. Immunohistochemistry measured MAC-2 and α-SMA expression in the aorta. ELISA quantified urea, cholesterol, calcium ions, and triglycerides in mouse plasma. Western blotting detected associated protein expression, followed by cell-based experiments for validation. Compared with the Klotho-NC group, the plaque area and aortic lipid and renal fibrosis area were reduced in the Klotho-mimic group. Klotho-mimic reduced macrophage area, plasma urea, cholesterol, calcium ions, and triglyceride levels, and decreased the expression of p-PERK, NOX2, NOX4, Caspase-3, Caspase-9, Bax, p-GRK2, p-PLCβ, p-Src, and p-IP3R. Without ox-LDL stimulation, Klotho expression increased in the Klotho-mimic group, with no significant differences in NOX2, p-SHP1, p-Src, p-PERK, p-GRK2, and p-PLCβ. With ox-LDL in high-calcium medium, Klotho and p-SHP1 increased, while NOX2, p-Src, p-PERK, p-GRK2, and p-PLCβ decreased in the Klotho-mimic group. After ox-LDL and TPI-1 treatment, Klotho increased, NOX2 decreased, and other proteins showed no significant changes. Adding shRNA-GRK2 reduced NOX2, p-Src, and p-PERK, increased p-SHP1, with no changes in p-GRK2 and p-PLCβ. Differences in NOX2, p-GRK2, p-PLCβ, and p-PERK between groups were reduced in high-calcium medium, while p-SHP1 differences increased. Klotho enhances chronic kidney disease atherosclerotic plaque stability by inhibiting GRK2/PLC-β-mediated endoplasmic reticulum stress in macrophages via the ROS/SHP1 pathway.

Interplay of cell death pathways and immune responses in ischemic stroke: insights into novel biomarkers

Stroke is a severe neurological disease and a major worldwide issue, mostly manifesting as ischemic stroke (IS). In order to create effective treatments for IS, it is imperative to fully understand the underlying pathologies, as the existing therapeutic choices are inadequate. Recent investigations have shown the complex relationships between several programmed cell death (PCD) pathways, including necroptosis, ferroptosis, and pyroptosis, and their correlation with immune responses during IS. However, this relationship is still unclear. To address this gap, this review study explored the cellular interactions in the immune microenvironment of IS. Then, to validate prior findings and uncover biomarkers, the study investigated bioinformatics studies. Several pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Toll-like receptor 4 (TLR4), and receptor-interacting protein kinase (RIPK), were involved in PCD-immune interactions. The bioinformatics studies reported key biomarkers such as glutathione peroxidase 4 (GPX4), NOD-like receptor family pyrin domain containing 3 (NLRP3), gasdermin D (GSDMD), and TLR4, which have important implications in ferroptosis, cuproptosis, pyroptosis, and necroptosis respectively. These biomarkers were associated with PCD mechanisms such as oxidative stress and inflammatory reactions. The immune infiltration analysis consistently revealed a significant correlation between PCD pathways and detrimental immune cells, such as neutrophils and γδ T cells. Conversely, M2 macrophages and T helper cells showed protective effects. In conclusion, considering the intricate network of interactions between immune responses and PCD pathways, this study emphasized the necessity of a paradigm shift in therapeutic approaches to address the injuries that are related to this complex network.

Association of serum klotho level with albuminuria in middle‑aged and elderly participants without diabetes mellitus: a cross‑sectional study

BACKGROUND

The relationship between serum klotho level and albuminuria is unknown in middle-aged and elderly participants without diabetes mellitus (DM). Therefore, we will investigate the association between serum klotho level and albuminuria in middle-aged and elderly participants without DM.

METHODS

Participants (aged 40-79) were from the five continuous cycles (2007-2016) of the National Health and Nutrition Examination Survey (NHANES). Multiple logistic regression was performed to investigate the association between serum klotho level and albuminuria.

RESULTS

9217 participants were included in the present study. 47.6% of the participants were male. The average age of the overall participants was 56.3 years (40-79 years). Overall, 823 participants with albuminuria were identified. After adjusted confounders (age, gender, marital status, ethnicity, family income to poverty ratio, education, body mass index, smoke, charlson comorbidity index, hypertension, hyperlipidemia, angiotensin converting enzyme inhibitor/angiotonin receptor blocker, and estimated glomerular filtration rate), participants with a high serum klotho level had a decreased risk for albuminuria. Compared with the lowest serum klotho level (Tertile 1), participants in Tertile 2 (odds ratio [OR] 0.83, 95% CI 0.70-0.99, P = 0.044) and Tertile 3 (OR 0.76, 95% CI 0.63-0.91, P = 0.003) had a lower risk of albuminuria (P for trend = 0.002). The stratified analysis showed that serum klotho level was still negatively associated with albuminuria in the subgroups, and statistically significant interactions were not observed in the subgroups (all P values for interactions > 0.05, except for the hypertension subgroup).

CONCLUSIONS

In middle-aged and elderly participants without DM, a high serum klotho level is associated with a decreased risk of albuminuria. In the future, the mechanism of the interaction between klotho and albuminuria needs to be elucidated to find new treatment targets for individuals without DM who suffer from albuminuria.

Advances in Traditional Chinese Medicine research in diabetic kidney disease treatment

CONTEXT

Diabetic kidney disease (DKD) is a prominent complication arising from diabetic microangiopathy, and its prevalence and renal impact have placed it as the primary cause of end-stage renal disease. Traditional Chinese Medicine (TCM) has the distinct advantage of multifaceted and multilevel therapeutic attributes that show efficacy in improving clinical symptoms, reducing proteinuria, protecting renal function, and slowing DKD progression. Over recent decades, extensive research has explored the mechanisms of TCM for preventing and managing DKD, with substantial studies that endorse the therapeutic benefits of TCM compounds and single agents in the medical intervention of DKD.

OBJECTIVE

This review lays the foundation for future evidence-based research efforts and provide a reference point for DKD investigation.

METHODS

The relevant literature published in Chinese and English up to 30 June 2023, was sourced from PubMed, Cochrane Library, VIP Database for Chinese Technical Periodicals (VIP), Wanfang Data, CNKI, and China Biology Medicine disc (CBM). The process involved examining and summarizing research on TCM laboratory tests and clinical randomized controlled trials for DKD treatment.

RESULTS AND CONCLUSIONS

The TCM intervention has shown the potential to inhibit the expression of inflammatory cytokines and various growth factors, lower blood glucose levels, and significantly affect insulin resistance, lipid metabolism, and improved renal function. Furthermore, the efficacy of TCM can be optimized by tailoring personalized treatment regimens based on the unique profiles of individual patients. We anticipate further rigorous and comprehensive clinical and foundational investigations into the mechanisms underlying the role of TCM in treating DKD.

Pan-Nox inhibitor treatment improves renal function in aging murine diabetic kidneys

BACKGROUND

Aging is a risk factor for development of chronic kidney disease and diabetes mellitus with commonly shared features of chronic inflammation and increased oxidative stress. Here, we investigated the effect of pan-Nox-inhibitor, APX-115, on renal function in aging diabetic mice.

METHODS

Diabetes was induced by intraperitoneal injection of streptozotocin at 50 mg/kg/day for 5 days in 52-week-old C57BL/6J mice. APX-115 was administered by oral gavage at a dose of 60 mg/kg/day for 12 weeks in nondiabetic and diabetic aging mice.

RESULTS

APX-115 significantly improved insulin resistance in diabetic aging mice. Urinary level of 8-isoprostane was significantly increased in diabetic aging mice than nondiabetic aging mice, and APX-115 treatment reduced 8-isoprostane level. Urinary albumin and nephrin excretion were significantly higher in diabetic aging mice than nondiabetic aging mice. Although APX-115 did not significantly decrease albuminuria, APX-115 markedly improved mesangial expansion, macrophage infiltration, and expression of fibrosis molecules such as transforming growth factor beta 1 and plasminogen activator inhibitor 1. Interestingly, the expression of all Nox isoforms including Nox1, Nox2, and Nox4 was significantly increased in diabetic aging kidneys, and APX-115 treatment decreased Nox1, Nox2, and Nox4 protein expression in the kidney. Furthermore, Klotho expression was significantly decreased in diabetic aging kidneys, and APX-115 restored Klotho level.

CONCLUSION

Our results provide evidence that pan-Nox inhibition may improve systemic insulin resistance and decrease oxidative stress, inflammation, and fibrosis in aging diabetic status and may have potential protective effects on aging diabetic kidney.

Origins and Molecular Mechanisms Underlying Renal Vascular Development

Kidneys play a crucial role in maintaining homeostasis within the body, and this function is intricately linked to the vascular structures within them. For vascular cells in the kidney to mature and function effectively, a well-coordinated spatial alignment between the nephrons and complex network of blood vessels is essential. This arrangement ensures efficient blood filtration and regulation of the electrolyte balance, blood pressure, and fluid levels. Additionally, the kidneys are vital in regulating the acid-base balance and producing hormones involved in erythropoiesis and blood pressure control. This article focuses on the vascular development of the kidneys, summarizing the current understanding of the origin and formation of the renal vasculature, and the key molecules involved. A comprehensive review of existing studies has been conducted to elucidate the cellular and molecular mechanisms governing renal vascular development. Specific molecules play a critical role in the development of renal vasculature, contributing to the spatial alignment between nephrons and blood vessels. By elucidating the cellular and molecular mechanisms involved in renal vascular development, this study aims to advance renal regenerative medicine and offer potential avenues for therapeutic interventions in kidney disease.

Identification of Genes Associated with Familial Focal Segmental Glomerulosclerosis Through Transcriptomics and In Silico Analysis, Including RPL27, TUBB6, and PFDN5

Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and often leads to progressive kidney failure. Its varying clinical presentation suggests potential genetic diversity, requiring further molecular investigation. This study aims to elucidate some of the genetic and molecular mechanisms underlying FSGS. The study focuses on the use of bioinformatic analysis of gene expression data to identify genes associated with familial FSGS. A comprehensive in silico analysis was performed using the GSE99340 data set from Gene Expression Omnibus (GEO) comparing gene expression in glomerular and tubulointerstitial tissues from FSGS patients (n = 10) and Minimal Change Disease (MCD) patients (n = 8). These findings were validated using transcriptomics data obtained using RNA sequencing from FSGS (n = 3) and control samples (n = 3) from the UAE. Further validation was conducted using qRT-PCR on an independent FFPE cohort (FSGS, n = 6; MCD, n = 7) and saliva samples (FSGS, n = 3; Control, n = 7) from the UAE. Three genes (TUBB6, RPL27, and PFDN5) showed significant differential expression (p < 0.01) when comparing FSGS and MCD with healthy controls. These genes are associated with cell junction organization and synaptic pathways of the neuron, supporting the link between FSGS and the neural system. These genes can potentially be useful as diagnostic biomarkers for FSGS and to develop new treatment options.

Wnt/β-catenin signaling inhibits oxidative stress-induced ferroptosis to improve interstitial cystitis/bladder pain syndrome by reducing NF-κB

BACKGROUND

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a bladder syndrome of unknown etiology. Reactive oxygen species (ROS) plays a major role in ferroptosis and bladder dysfunction of IC/BPS, while the role of ferroptosis in IC/BPS progression is still unclear. This study aims to investigate the role and mechanism of ROS-induced ferroptosis in IC/BPS using cell and rat model.

METHODS

We collected IC/BPS patient bladder tissue samples and established a LPS-induced IC/BPS rat model (LRM). The level of oxidative stress and ferroptosis in IC/BPS patients and LRM rats was analyzed. Function and regulatory mechanism of ferroptosis in IC/BPS were explored by in vitro and in vivo experiments.

RESULTS

The patients with IC/BPS showed mast cells and inflammatory cells infiltration in bladder epithelial tissues. Expression of NRF2 was up-regulated, and GPX4 was decreased in IC/BPS patients compared with normal tissues. IC model cells underwent oxidative stress, which induced ferroptosis. These above results were validated in LRM rat models, and inhibition of ferroptosis ameliorated bladder dysfunction in LRM rats. Wnt/β-catenin signaling was deactivated in IC/BPS patients and animals, and activation of Wnt/β-catenin signaling reduced cellular free radical production, thereby inhibited ferroptosis in IC model cells. Mechanistically, the Wnt/β-catenin signaling pathway inhibited oxidative stress-induced ferroptosis by down-regulating NF-κB, thus contributing to recover IC/BPS both in vitro and in vivo.

CONCLUSIONS

We demonstrate for the first time that oxidative stress-induced ferroptosis plays an important role in the pathology of IC/BPS. Mechanistically, the Wnt/β-catenin signaling suppressed oxidative stress-induced ferroptosis by down-regulating NF-κB to improve bladder injury in IC/BPS.

Anti-Inflammatory Role of the Klotho Protein and Relevance to Aging

The α-Klotho protein (hereafter Klotho) is an obligate coreceptor for fibroblast growth factor 23 (FGF23). It is produced in the kidneys, brain and other sites. Klotho insufficiency causes hyperphosphatemia and other anomalies. Importantly, it is associated with chronic pathologies (often age-related) that have an inflammatory component. This includes atherosclerosis, diabetes and Alzheimer's disease. Its mode of action in these diseases is not well understood, but it inhibits or regulates multiple major pathways. Klotho has a membrane form and a soluble form (s-Klotho). Cytosolic Klotho is postulated but not well characterized. s-Klotho has endocrine properties that are incompletely elucidated. It binds to the FGF receptor 1c (FGFR1c) that is widely expressed (including endothelial cells). It also attaches to soluble FGF23, and FGF23/Klotho binds to FGFRs. Thus, s-Klotho might be a roaming FGF23 coreceptor, but it has other functions. Notably, Klotho (cell-bound or soluble) counteracts inflammation and appears to mitigate related aging (inflammaging). It inhibits NF-κB and the NLRP3 inflammasome. This inflammasome requires priming by NF-κB and produces active IL-1β, membrane pores and cell death (pyroptosis). In accord, Klotho countered inflammation and cell injury induced by toxins, damage-associated molecular patterns (DAMPs), cytokines, and reactive oxygen species (ROS). s-Klotho also blocks the TGF-β receptor and Wnt ligands, which lessens fibrotic disease. Low Klotho is associated with loss of muscle mass (sarcopenia), as occurs in aging and chronic diseases. s-Klotho counters the inhibitory effects of myostatin and TGF-β on muscle, reduces inflammation, and improves muscle repair following injury. The inhibition of TGF-β and other factors may also be protective in diabetic retinopathy and age-related macular degeneration (AMD). This review examines Klotho functions especially as related to inflammation and potential applications.

Rehmapicrogenin attenuates lipopolysaccharide-induced podocyte injury and kidney dysfunctions by regulating nuclear factor E2-related factor 2/antioxidant response element signalling

BACKGROUND

Apoptosis and oxidative stress in kidneys are critical players in acute kidney injury (AKI). Rehmapicrogenin, a monomeric compound extracted from Rehmanniae radix, has been found to possess nitric oxide inhibitory and anti-inflammatory activities. Thus, this study aimed to investigate the roles and mechanisms of rehmapicrogenin in AKI.

METHODS

Lipopolysaccharide (LPS) was used to induce AKI-like conditions. Cell survival conditions were detected by cell counting kit-8 assays and flow cytometry. Several renal function markers including blood urea nitrogen, proteinuria, creatinine, and albumin were measured. Apoptosis and reactive oxygen species (ROS) production were examined by TUNEL and dihydroethidium staining, respectively. Haematoxylin-eosin staining and periodic acid-Schiff staining were conducted to assess histopathological changes. Gene expression was evaluated by western blotting, commercially available kits and immunofluorescence staining.

RESULTS

For in vitro analysis, rehmapicrogenin inhibited the LPS-induced podocyte apoptosis by activating the Nrf2/ARE pathway. For in vivo analysis, rehmapicrogenin improved renal functions in LPS-induced mice. Additionally, rehmapicrogenin suppressed LPS-induced podocyte apoptosis and oxidative stress in kidney tissues. Mechanistically, rehmapicrogenin activated the Nrf2/ARE pathway in LPS-induced mice.

CONCLUSION

Rehmapicrogenin relieves the podocyte injury and renal dysfunctions through activating the Nrf2/ARE pathway to inhibit apoptosis and oxidative stress.

Molecular mechanisms and therapeutic potential of natural flavonoids in diabetic nephropathy: Modulation of intracellular developmental signaling pathways

Recognized as a common microvascular complication of diabetes mellitus (DM), diabetic nephropathy (DN) is the principal cause of chronic end-stage renal disease (ESRD). Patients with diabetes have an approximately 25% risk of developing progressive renal disease. The underlying principles of DN control targets the dual outcomes of blood glucose regulation through sodium glucose cotransporter 2 (SGLT 2) blockade and hypertension management through renin-angiotensin-aldosterone inhibition. However, these treatments are ineffective in halting disease progression to kidney failure and cardiovascular comorbidities. Recently, the dysregulation of subcellular signaling pathways has been increasingly implicated in DN pathogenesis. Natural compounds are emerging as effective and side-effect-free therapeutic agents that target intracellular pathways. This narrative review synthesizes recent insights into the dysregulation of maintenance pathways in DN, drawing from animal and human studies. To compile this review, articles reporting DN signaling pathways and their treatment with natural flavonoids were collected from PubMed, Cochrane Library Web of Science, Google Scholar and EMBASE databases since 2000. As therapeutic interventions are frequently based on the results of clinical trials, a brief analysis of data from current phase II and III clinical trials on DN is discussed.

m6A RNA methylation drives kidney fibrosis by upregulating β-catenin signaling

N6-methyladenosine (m6A) methylation plays a crucial role in various biological processes and the pathogenesis of human diseases. However, its role and mechanism in kidney fibrosis remain elusive. In this study, we show that the overall level of m6A methylated RNA was upregulated and the m6A methyltransferase METTL3 was induced in kidney tubular epithelial cells in mouse models and human kidney biopsies of chronic kidney disease (CKD). Proximal tubule-specific knockout of METTL3 in mice protected kidneys against developing fibrotic lesions after injury. Conversely, overexpression of METTL3 aggravated kidney fibrosis in vivo. Through bioinformatics analysis and experimental validation, we identified β-catenin mRNA as a major target of METTL3-mediated m6A modification, which could be recognized by a specific m6A reader, the insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3). METTL3 stabilized β-catenin mRNA, increased β-catenin protein and induced its downstream profibrotic genes, whereas either knockdown of IGF2BP3 or inhibiting β-catenin signaling abolished its effects. Collectively, these results indicate that METTL3 promotes kidney fibrosis by stimulating the m6A modification of β-catenin mRNA, leading to its stabilization and its downstream profibrotic genes expression. Our findings suggest that targeting METTL3/IGF2BP3/β-catenin pathway may be a novel strategy for the treatment of fibrotic CKD.

Admission proteinuria predicts the incidence of acute kidney injury among patients with acute ST-segment elevation myocardial infarction: a retrospective cohort study

BACKGROUND

Proteinuria indicates renal dysfunction and is associated with the development of acute kidney injury (AKI) in several conditions, but the association between proteinuria and AKI in patients with ST-segment elevation myocardial infarction (STEMI) remains unclear. This research aims to investigate the predictive value of proteinuria for the development of AKI in STEMI patients.

METHODS

A total of 2735 STEMI patients were enrolled. The present study's endpoint was AKI incidence during hospitalization. AKI is defined according to the Kidney Disease: Improving Global Outcomes criteria. We defined proteinuria, measured with a dipstick, as mild (1+) or heavy (2+ to 4+). Multivariate logistic regression and subgroup analyses were used to testify to the association between proteinuria and AKI.

RESULTS

Overall, proteinuria was observed in 634 (23.2%) patients. Multivariate logistic regression analyses revealed that proteinuria [odds ratio (OR), 1.58; 95% confidence interval (CI), 1.25-2.00; P  < 0.001] was the independent predictive factor for AKI. Severe proteinuria was associated with a higher adjusted risk for AKI compared with the nonproteinuria group (mild proteinuria: OR, 1.35; 95% CI, 1.04-1.75; P  = 0.025; severe proteinuria: OR, 2.50; 95% CI, 1.70-3.68; P  < 0.001). The association was highly consistent across all studied subgroups. (all P for interaction >0.05).

CONCLUSION

Admission proteinuria measured using a urine dipstick is an independent risk factor for the development of AKI in STEMI patients.

Eucommia granules activate Wnt/β-catenin pathway, and improve oxidative stress, inflammation, and endothelial injury in preeclampsia rats

PURPOSE

Pre-eclampsia (PE) is a pregnancy-related complication. Eucommia is effective in the treatment of hypertensive disorders in pregnancy, but the specific effects and possible mechanisms of Eucommia granules (EG) in PE remain unknown. The aim of this study was to investigate the effects and possible mechanisms of EG in PE rats.

METHODS

Pregnant Sprague Dawley rats were divided into five groups (n = 6): the control group, the model group, the low-dose group, the medium-dose group, and the high-dose group of EG. The PE model was established by subcutaneous injection of levonitroarginine methyl ester. Saline was given to the blank and model groups, and the Eucommia granules were given by gavage to the remaining groups. Blood pressure and urinary protein were detected. The body length and weight of the pups and the weight of the placenta were recorded. Superoxide dismutase (SOD) activity and levels of malondialdehyde (MDA), placental growth factor (PIGF), and soluble vascular endothelial growth factor receptor-1 (sFIt-1) were measured in the placenta. Pathological changes were observed by hematoxylin-eosin staining. Wnt/β-catenin pathway-related protein expression was detected using Western blot.

RESULTS

Compared with the model group, the PE rats treated with EG had lower blood pressure and urinary protein. The length and weight of the pups and placental weight were increased. Inflammation and necrosis in the placental tissue was improved. SOD level increased, MDA content and sFIt-1/PIGF ratio decreased, and Wnt/β-catenin pathway-related protein expression level increased. Moreover, the results of EG on PE rats increased with higher doses of EG.

CONCLUSIONS

EG may activate the Wnt/β-catenin pathway and inhibit oxidative stress, inflammation, and vascular endothelial injury in PE rats, thereby improving the perinatal prognosis of preeclamptic rats. EG may inhibit oxidative stress, inflammation, and vascular endothelial injury through activation of the Wnt/β-catenin pathway in preeclampsia rats, thereby improving perinatal outcomes in PE rats.

Metadherin orchestrates PKA and PKM2 to activate β-catenin signaling in podocytes during proteinuric chronic kidney disease

Podocyte damage is the major cause of glomerular injury and proteinuria in multiple chronic kidney diseases. Metadherin (MTDH) is involved in podocyte apoptosis and promotes renal tubular injury in mouse models of diabetic nephropathy and renal fibrosis; however, its role in podocyte injury and proteinuria needs further exploration. Here, we show that MTDH was induced in the glomerular podocytes of patients with proteinuric chronic kidney disease and correlated with proteinuria. Podocyte-specific knockout of MTDH in mice reversed proteinuria, attenuated podocyte injury, and prevented glomerulosclerosis after advanced oxidation protein products challenge or adriamycin injury. Furthermore, specific knockout of MTDH in podocytes repressed β-catenin phosphorylation at the Ser675 site and inhibited its downstream target gene transcription. Mechanistically, on the one hand, MTDH increased cAMP and then activated protein kinase A (PKA) to induce β-catenin phosphorylation at the Ser675 site, facilitating the nuclear translocation of MTDH and β-catenin; on the other hand, MTDH induced the deaggregation of pyruvate kinase M2 (PKM2) tetramers and promoted PKM2 monomers to enter the nucleus. This cascade of events leads to the formation of the MTDH/PKM2/β-catenin/CBP/TCF4 transcription complex, thus triggering TCF4-dependent gene transcription. Inhibition of PKA activity by H-89 or blockade of PKM2 deaggregation by TEPP-46 abolished this cascade of events and disrupted transcription complex formation. These results suggest that MTDH induces podocyte injury and proteinuria by assembling the β-catenin-mediated transcription complex by regulating PKA and PKM2 function.

SGLT2i relieve proteinuria in diabetic nephropathy patients potentially by inhibiting renal oxidative stress rather than through AGEs pathway

AIMS

To estimate the effects of the sodium-glucose cotransporter 2 inhibitor (SGLT2i) on proteinuria and oxidative stress expression in type 2 diabetes patients.

MATERIALS AND METHODS

68 patients with type 2 diabetes mellitus (T2DM) were divided into three groups according urinary albumin-to-creatinine ratio (UACR), including T2DM with non-albuminuria group (UACR < 30 mg/g), T2DM with microalbuminuria group (30 ≤ UACR ≤ 300 mg/g), T2DM with macroalbuminuria group (UACR>300 mg/g). They all received SGLT2 inhibitors (SGLT2i) treatment for 12 weeks. The expression of advanced glycation end products (AGEs) in plasma and 8-hydroxy-2-deoxyguanosine (8-OHdG) in urine were measured as indications of oxidative stress. The 24-hour urine samples were collected to measure the concentration of proteinuria and 8-OHdG before and after 12 weeks SGLT2i treatment. Plasma renin activity (PRA), angiotensin II (Ang II) and Aldosterone (ALD) were measured to evaluate renin angiotensin aldosterone system (RASS) levels.

RESULTS

After 12 weeks SGLT2 inhibitors treatment, the median values of 24-hour proteinuria decreased in macroalbuminuria compared to baseline (970 vs. 821 mg/d, P = 0.006). The median values of AGEs and 8-OHdG decreased in microalbuminuria and macroalbuminuria groups when compared to baseline, AGEs (777 vs. 136 ug/ml, P = 0.003) and (755 vs. 210 ug/ml, P = 0.001), 8-OHdG (8.00 vs. 1.88 ng/ml, P = 0.001) and (11.18 vs. 1.90 ng/ml, P < 0.001), respectively. Partial correlations showed that 8-OHdG were relevant to the baseline 24-h proteinuria (r = 0.389, p = 0.001), the reduction of OHdG (Δ8-OHdG) were positively correlated with the decrease of 24-h proteinuria (Δ24-h proteinuria) after 12 weeks of SGLT2i treatment (r = 0.283, P = 0.031). There was no significant correlation between 24-h proteinuria and AGEs in baseline (r = -0.059, p = 0.640) as well as between ΔAGEs and Δ24-h proteinuria (r = 0.022, p = 0.872) after12 weeks of SGLT2i treatment in T2DM patients.

CONCLUSIONS

SGLT2i may reduce proteinuria in diabetic nephropathy patients, potentially by inhibiting renal oxidative stress, but not through the AGEs pathway and does not induce RAAS activation.

TRIAL REGISTRATION

This clinical trial was registered on 15/10/2019, in ClinicalTrials.gov, and the registry number is NCT04127084.

Analysis and identification of oxidative stress-ferroptosis related biomarkers in ischemic stroke

Studies have shown that a series of molecular events caused by oxidative stress is associated with ferroptosis and oxidation after ischemic stroke (IS). Differential analysis was performed to identify differentially expressed mRNA (DEmRNAs) between IS and control groups. Critical module genes were identified using weighted gene co-expression network analysis (WGCNA). DEmRNAs, critical module genes, oxidative stress-related genes (ORGs), and ferroptosis-related genes (FRGs) were crossed to screen for intersection mRNAs. Candidate mRNAs were screened based on the protein-protein interaction (PPI) network and the MCODE plug-in. Biomarkers were identified based on two types of machine learning algorithms, and the intersection was obtained. Functional items and related pathways of the biomarkers were identified using gene set enrichment analysis (GSEA). Finally, single-sample GSEA (ssGSEA) and Wilcoxon tests were used to identify differential immune cells. An miRNA-mRNA-TF network was created. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the expression levels of biomarkers in the IS and control groups. There were 8287 DE mRNAs between the IS and control groups. The genes in the turquoise module were selected as critical module genes for IS. Thirty intersecting mRNAs were screened for overlaps. Seventeen candidate mRNAs were also identified. Four biomarkers (CDKN1A, GPX4, PRDX1, and PRDX6) were identified using two types of machine-learning algorithms. GSEA results indicated that the biomarkers were associated with steroid biosynthesis. Nine types of immune cells (activated B cells and neutrophils) were markedly different between the IS and control groups. We identified 3747 miRNA-mRNA-TF regulatory pairs in the miRNA-mRNA-TF regulatory network, including hsa-miR-4469-CDKN1A-BACH2 and hsa-miR-188-3p-GPX4-ATF2. CDKN1A, PRDX1, and PRDX6 were upregulated in IS samples compared with control samples. This study suggests that four biomarkers (CDKN1A, GPX4, PRDX1, and PRDX6) are significantly associated with IS. This study provides a new reference for the diagnosis and treatment of IS.

MAGL protects against renal fibrosis through inhibiting tubular cell lipotoxicity

Rationale: Renal fibrosis, with no therapeutic approaches, is a common pathological feature in various chronic kidney diseases (CKD). Tubular cell injury plays a pivotal role in renal fibrosis. Commonly, injured tubular cells exhibit significant lipid accumulation. However, the underlying mechanisms remain poorly understood. Methods: 2-arachidonoylglycerol (2-AG) levels in CKD patients and CKD model specimens were measured using mass spectrometry. 2-AG-loaded nanoparticles were infused into unilateral ureteral obstruction (UUO) mice. Lipid accumulation and renal fibrosis were tested. Furthermore, monoacylglycerol lipase (MAGL), the hydrolyzing enzyme of 2-AG, was assessed in CKD patients and models. Tubular cell-specific MAGL knock-in mice were generated. Moreover, MAGL recombination protein was also administered to unilateral ischemia reperfusion injury (UIRI) mice. Besides, a series of methods including RNA sequencing, metabolomics, primary cell culture, lipid staining, etc. were used. Results: 2-AG was increased in the serum or kidneys from CKD patients and models. Supplement of 2-AG further induced lipid accumulation and fibrogenesis through cannabinoid receptor type 2 (CB2)/β-catenin signaling. β-catenin knockout blocked 2-AG/CB2-induced fatty acid β-oxidation (FAO) deficiency and lipid accumulation. Remarkably, MAGL significantly decreased in CKD, aligning with lipid accumulation and fibrosis. Specific transgene of MAGL in tubular cells significantly preserved FAO, inhibited lipid-mediated toxicity in tubular cells, and finally retarded fibrogenesis. Additionally, supplementation of MAGL in UIRI mice also preserved FAO function, inhibited lipid accumulation, and protected against renal fibrosis. Conclusion: MAGL is a potential diagnostic marker for kidney function decline, and also serves as a new therapeutic target for renal fibrosis through ameliorating lipotoxicity.

Fibroblast growth factor 21 alleviates unilateral ureteral obstruction-induced renal fibrosis by inhibiting Wnt/β-catenin signaling pathway

Fibroblast growth factor 21 (FGF21) is a key regulator of energy metabolism. Recent studies suggested that serum FGF21 levels increase with declining renal function. However, the link between FGF21 and kidney diseases and the direct effect of FGF21 in renal fibrosis remains unclear. In this study, FGF21 was upregulated in unilateral ureteral obstruction (UUO)-induced renal fibrosis and cellular fibrosis induced by transforming growth factor-β, and renal expression of FGF21 was positively correlated with fibrosis markers. Additionally, FGF21 was regulated by Wnt/β-catenin signaling pathway. The knockdown and overexpression of FGF21 in mouse tubular epithelial cells demonstrated that FGF21 alleviates renal fibrosis by inhibiting the Wnt/β-catenin signaling pathway. To investigate the effect of FGF21 on renal fibrosis in vivo, we established an overexpression model by injecting the plasmid in mice and found that FGF21 overexpression relieved UUO-induced renal fibrosis and renal inflammatory response. Taken together, FGF21 is upregulated with the activation of Wnt/β-catenin signaling pathway and alleviates renal fibrosis by inhibiting the activation of Wnt/β-catenin signaling pathway in a negative feedback mode. These results provide a new understanding for the source of elevated serum FGF21 in patients with chronic kidney disease and prove that FGF21 is a direct inhibitor of the progression of renal fibrosis, thus providing novel therapeutic intervention insights for renal fibrosis.

The CXCR4-AT1 axis plays a vital role in glomerular injury via mediating the crosstalk between podocyte and mesangial cell

Glomeruli stand at the center of nephrons to accomplish filtration and albumin interception. Podocytes and mesangial cells are the major constituents in the glomeruli. However, their interdependency in glomerular injury has rarely been reported. Herein, we investigated the role of C-X-C chemokine receptor type 4 (CXCR4) in mediating the crosstalk between podocytes and mesangial cells. We found CXCR4 and angiotensin II (AngII) increased primarily in injured podocytes. However, type-1 receptor of angiotensin II (AT1) and stromal cell-derived factor 1α (SDF-1α), a ligand of CXCR4, were evidently upregulated in mesangial cells following the progression of podocyte injury. Ectopic expression of CXCR4 in 5/6 nephrectomy mice increased the decline of renal function and glomerular injury, accelerated podocyte injury and mesangial cell activation, and initiated CXCR4-AT1 axis signals. Additionally, treatment with losartan, an AT1 blocker, interrupted the cycle of podocyte injury and mesangial matrix deposition triggered by CXCR4. Podocyte-specific ablation of CXCR4 gene blocked podocyte injury and mesangial cell activation. In vitro, CXCR4 overexpression induced oxidative stress and renin angiotensin system (RAS) activation in podocytes, and triggered the communication between podocytes and mesangial cells. In cultured mesangial cells, AngII treatment induced the expression of SDF-1α, which was secreted into the supernatant to further promote oxidative stress and cell injury in podocytes. Collectively, these results demonstrate that the CXCR4-AT1 axis plays a vital role in glomerular injury via mediating pathologic crosstalk between podocytes and mesangial cells. Our findings uncover a novel pathogenic mechanism by which the CXCR4-AT1 axis promotes glomerular injury.

Vinpocetine improves dyskinesia in Parkinson's disease rats by reducing oxidative stress and activating the Wnt/β-catenin signaling pathway

Parkinson's disease (PD) is the commonest neurodegenerative disorder. It reduces motor and cognitive function in patients. Vinpocetine (Vinp) has the effects of anti-inflammatory and antioxidant, and could improve cognitive function in patients. This study was aimed to investigating the therapeutic effects of Vinp on dyskinesia in a 6-Hydroxydopamine hydrobromide (6-OHDA)-induced PD rat model. We constructed a PD rat model by injecting 6-OHDA, and intervened with Vinp for 7 days. The motor function of the rats was evaluated by an open-field test and rotation test. Besides, H&E staining was applied to observe the changes of dopaminergic neurons in the striatum. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in the rat striatum were detected. We assessed the impact of Vinp on α-synuclein (α-Syn) and Wnt/β-catenin signaling pathway-related molecules by western blot and qRT-PCR. Rats in the PD group showed reduced horizontal movement frequency and number of squares crossed, increased contact time and rotation frequency, and reduced number of dopaminergic neurons accompanied by severe morphological damage. Vinp treatment increased the horizontal movement frequency and number of squares crossed, reduced the contact time, and rotation frequency in PD rats. Also, Vinp downregulated α-Syn protein expression and MDA level, while upregulated SOD activity in the striatum of PD rats. Furthermore, Vinp treatment activated the Wnt/β-catenin signaling pathway in the striatum of PD rats. In conclusion, Vinp improved the dyskinesia in 6-OHDA-induced PD rats by alleviating oxidative stress, and these effects may be associated with activating the Wnt/β-catenin signaling pathway.

Early growth response 1 as a podocyte injury marker in human glomerular diseases

Background

In human glomerular diseases, visualizing podocyte injury is desirable since podocytes do not regenerate and podocyte injury leads to podocyte loss. Herein, we investigated the utility of immunostaining for early growth response 1 (EGR1), which is expressed in injured podocytes from the early stages of injury in animal experiments, as a podocyte injury marker in human glomerular diseases.

Methods

This study included 102 patients with biopsy-proven glomerular diseases between 2018 and 2021. The proportion of EGR1 expression in podocytes (%EGR1pod) was analyzed in relation to clinical and histopathological features, including glomerular and urinary podocyte-specific markers.

Results

%EGR1pod correlated significantly with the urinary protein:creatinine ratio, urinary nephrin and podocin mRNA levels, and glomerular podocin staining (rho = 0.361, 0.514, 0.487 and -0.417, respectively; adjusted P = .002, <.001, <.001 and <.001, respectively). Additionally, %EGR1pod correlated with cellular/fibrocellular crescents (rho = 0.479, adjusted P <.001). %EGR1pod was high in patients with glomerulonephritis, such as immunoglobulin A nephropathy (IgAN), lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis, and in those with podocytopathies, such as membranous nephropathy and primary focal segmental glomerulosclerosis, while %EGR1pod was low in patients with minimal change disease. In a subgroup analysis of IgAN, %EGR1pod was higher in Oxford C1 patients than in C0 patients. However, unexpectedly, patients with higher %EGR1pod were more prone to attain proteinuria remission, suggesting that EGR1 in the context of IgAN reflects reversible early injury.

Conclusions

Our findings indicate that EGR1 is a promising potential marker for identifying active early podocyte injury in human glomerular diseases.

Effect of octreotide on oxidative stress in the erythrocyte and kidney tissue in adriamycin-induced experimental nephrotic syndrome model

INTRODUCTION

Nephrotic syndrome (NS) is one of the reasons of end-stage kidney disease, and elucidating the pathogenesis and offer new treatment options is important. Oxidative stress might trigger pathogenesis systemically or isolated in the kidneys. Octreotide (OCT) has beneficial antioxidant effects. We aimed to investigate the source of oxidative stress and the effect of OCT on experimental NS model.

METHODS

Twenty-four non-uremic Wistar albino rats were divided into 3 groups. Control group, 2 mL saline intramuscular (im); NS group, adriamycin 5 mg/kg intravenous (iv); NS treatment group, adriamycin 5 mg/kg (iv) and OCT 200 mcg/kg (im) were administered at baseline (Day 0). At the end of 21 days, creatinine and protein levels were measured in 24-hour urine samples. Erythrocyte and renal catalase (CAT) and thiobarbituric acid reactive substance (TBARS) were measured. Renal histology was also evaluated.

RESULTS

There was no significant difference among the 3 groups in terms of CAT and TBARS in erythrocytes. Renal CAT level was lowest in NS group, and significantly lower than the control group. In treatment group, CAT level significantly increased compared with NS group. In terms of renal histology, tubular and interstitial evaluations were similar in all groups. Glomerular score was significantly higher in NS group compared with control group and it was significantly decreased in treatment group compared to NS group.

CONCLUSIONS

Oxidative stress in NS might be due to the decrease in antioxidant protection mechanism in kidney. Octreotide improves antioxidant levels and histology in renal tissue and might be a treatment option.

Podocyte injury of diabetic nephropathy: Novel mechanism discovery and therapeutic prospects

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus, posing significant challenges in terms of early prevention, clinical diagnosis, and treatment. Consequently, it has emerged as a major contributor to end-stage renal disease. The glomerular filtration barrier, composed of podocytes, endothelial cells, and the glomerular basement membrane, plays a vital role in maintaining renal function. Disruptions in podocyte function, including hypertrophy, shedding, reduced density, and apoptosis, can impair the integrity of the glomerular filtration barrier, resulting in elevated proteinuria, abnormal glomerular filtration rate, and increased creatinine levels. Hence, recent research has increasingly focused on the role of podocyte injury in DN, with a growing emphasis on exploring therapeutic interventions targeting podocyte injury. Studies have revealed that factors such as lipotoxicity, hemodynamic abnormalities, oxidative stress, mitochondrial dysfunction, and impaired autophagy can contribute to podocyte injury. This review aims to summarize the underlying mechanisms of podocyte injury in DN and provide an overview of the current research status regarding experimental drugs targeting podocyte injury in DN. The findings presented herein may offer potential therapeutic targets and strategies for the management of DN associated with podocyte injury.

Imbalanced lipid homeostasis caused by membrane αKlotho deficiency contributes to the acute kidney injury to chronic kidney disease transition

After acute kidney injury (AKI), renal tubular epithelial cells (RTECs) are pathologically characterized by intracellular lipid droplet (LD) accumulation, which are involved in RTEC injury and kidney fibrosis. However, its pathogenesis remains incompletely understood. The protein, αKlotho, primarily expressed in RTECs, is well known as an anti-aging hormone wielding versatile functions, and its membrane form predominantly acts as a co-receptor for fibroblast growth factor 23. Here, we discovered a connection between membrane αKlotho and intracellular LDs in RTECs. Fluorescent fatty acid (FA) pulse-chase assays showed that membrane αKlotho deficiency in RTECs, as seen in αKlotho homozygous mutated (kl/kl) mice or in mice with ischemia-reperfusion injury (IRI)-induced AKI, inhibited FA mobilization from LDs by impairing adipose triglyceride lipase (ATGL)-mediated lipolysis and lipophagy. This resulted in LD accumulation and FA underutilization. IRI-induced alterations were more striking in αKlotho deficiency. Mechanistically, membrane αKlotho deficiency promoted E3 ligase peroxin2 binding to ubiquitin-conjugating enzyme E2 D2, resulting in ubiquitin-mediated degradation of ATGL which is a common molecular basis for lipolysis and lipophagy. Overexpression of αKlotho rescued FA mobilization by preventing ATGL ubiquitination, thereby lessening LD accumulation and fibrosis after AKI. This suggests that membrane αKlotho is indispensable for the maintenance of lipid homeostasis in RTECs. Thus, our study identified αKlotho as a critical regulator of lipid turnover and homeostasis in AKI, providing a viable strategy for preventing tubular injury and the AKI-to-chronic kidney disease transition.

Oxidatively stressed extracellular microenvironment drives fibroblast activation and kidney fibrosis

Kidney fibrosis is associated with tubular injury, oxidative stress and activation of interstitial fibroblasts. However, whether these events are somehow connected is poorly understood. In this study, we show that glutathione peroxidase-3 (GPX3) depletion in renal tubular epithelium after kidney injury plays a central role in orchestrating an oxidatively stressed extracellular microenvironment, which drives interstitial fibroblast activation and proliferation. Through transcriptional profiling by RNA-sequencing, we found that the expression of GPX3 was down-regulated in various models of chronic kidney disease (CKD), which was correlated with induction of nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase-4 (NOX4). By using decellularized extracellular matrix (ECM) scaffold, we demonstrated that GPX3-depleted extracellular microenvironment spontaneously induced NOX4 expression and reactive oxygen species (ROS) production in renal fibroblasts and triggered their activation and proliferation. Activation of NOX4 by advanced oxidation protein products (AOPPs) mimicked the loss of GPX3, increased the production of ROS, stimulated fibroblast activation and proliferation, and activated protein kinase C-α (PKCα)/mitogen-activated protein kinase (MAPK)/signal transducer and activator of transcription 3 (STAT3) signaling. Silencing NOX4 or inhibition of MAPK with small molecule inhibitors hampered fibroblast activation and proliferation. In mouse model of CKD, knockdown of NOX4 repressed renal fibroblast activation and proliferation and alleviated kidney fibrosis. These results indicate that loss of GPX3 orchestrates an oxidatively stressed extracellular microenvironment, which promotes fibroblast activation and proliferation through a cascade of signal transduction. Our studies underscore the crucial role of extracellular microenvironment in driving fibroblast activation and kidney fibrosis.

High-sulfated derivative of polysaccharide from Ulva pertusa improves Adriamycin-induced nephrotic syndrome by suppressing oxidative stress

Nephrotic syndrome (NS) is characterized by proteinuria, hyperlipidemia, and hypoalbuminemia. Ulva pertusa, a green seaweed, is a nutritional supplement. In this study, the high-sulfated derivative of Ulva pertusa polysaccharide (HU) was prepared by combining U pertusa polysaccharide with chlorosulfonic acid. The NS rat model was established by tail vein single injection of Adriamycin (6.0 mg kg-1). Normal rats were used as the control group. NS rat models were treated with HU or U (173 mg kg-1 day-1). After treatment for 6 weeks, we assessed urine protein, renal function, and blood lipids, and observed morphology and histologic injury of the kidney and glomerular microstructure. Furthermore, we detected antioxidant enzyme activity and expression level of the Keap1/Nrf2 signaling pathway to explore the potential mechanism of HU. Results showed that HU not only alleviated hyperlipidemia and hypoalbuminemia, but also reduced urine protein by inhibiting podocyte detachment, thickening of the glomerular basement membrane, and expression of kidney fibrosis markers (collagens I and IV). In addition, HU enhanced antioxidant enzyme activity (GSH-Px, CAT, SOD) in both serum and the kidney, which may be due to upregulating the expression of Nrf2 and downregulating the expression of Keap1. In conclusion, HU appears to be effective in attenuating NS in rats through suppressing oxidative stress by regulating the Keap1/Nrf2 signaling pathway.

Dendrobium officinale polysaccharide decreases podocyte injury in diabetic nephropathy by regulating IRS-1/AKT signal and promoting mitophagy

BACKGROUNDS

High glucose (HG) caused oxidative stress and mitochondrial dysfunction, resulting in insulin resistance in podocytes, a key mechanism of diabetic nephropathy. Dendrobium officinale polysaccharide (DOP) was able to improve insulin resistance and antioxidant capability.

OBJECTIVE

The purpose of this study is to explore the mechanism by which DOP decreases the podocyte injury induced by HG.

METHODS

MPC5 cells were treated with HG, DOP, and IRS-1/2 inhibitor NT157. Afterwards, glucose consumption, generations of ROS and MDA were measured using the detection kits. Mitophagy was monitored using both MtphagTracyker and LysoTracker. The mitochondrial membrane potential was evaluated by JC-1 staining. DOP was also used in a mouse model of diabetes, with the measurements of urine albumin, blood creatinine and blood urea nitrogen.

RESULTS

Treatment with DOP suppressed the HG-induced reduction of glucose consumption, the phosphorylation of IRS-1 (phospho Y632), AKT (phospho Ser473 and Thr308) and Nephrin. In addition, HG-induced augment of ROS and MDA, formation of γ-H2A.X foci and translocation of AKT to nucleus were inhibited by DOP. DOP enhanced mitophagy, which was associated with decreased mitochondrial membrane potential and ROS production. DOP conferred protective effect on podocyte in the diabetic mouse by reducing the albumin/creatinine ratio and blood urea nitrogen, and restoring Nephrin expression in podocytes.

CONCLUSIONS

DOP alleviates HG-induced podocyte injuryby regulating IRS-1/AKT signal and promoting mitophagy.

Biofactors regulating mitochondrial function and dynamics in podocytes and podocytopathies

Podocytes are terminally differentiated kidney cells acting as the main gatekeepers of the glomerular filtration barrier; hence, inhibiting proteinuria. Podocytopathies are classified as kidney diseases caused by podocyte damage. Different genetic and environmental risk factors can cause podocyte damage and death. Recent evidence shows that mitochondrial dysfunction also contributes to podocyte damage. Understanding alterations in mitochondrial metabolism and function in podocytopathies and whether altered mitochondrial homeostasis/dynamics is a cause or effect of podocyte damage are issues that need in-depth studies. This review highlights the roles of mitochondria and their bioenergetics in podocytes. Then, factors/signalings that regulate mitochondria in podocytes are discussed. After that, the role of mitochondrial dysfunction is reviewed in podocyte injury and the development of different podocytopathies. Finally, the mitochondrial therapeutic targets are considered.

Celastrol attenuates diabetic nephropathy by upregulating SIRT1-mediated inhibition of EZH2related wnt/β-catenin signaling

Proteinuria is an independent risk factor for the progression of diabetic nephropathy (DN) and an imbalance in podocyte function aggravates proteinuria. Celastrol is the primary active ingredient of T. wilfordii, effective in treating DN renal injury; however, the mechanisms underlying its effect are unclear. We explored how celastrol prevents DN podocyte damage using in vivo and in vitro experiments. We randomly divided 24 male C57BLKS/J mice into three groups: db/m (n = 8), db/db (n = 8), and celastrol groups (db/db + celastrol, 1 mg/kg/d, gavage administration, n = 8). In vivo experiments lasted 12 weeks and intervention lasted ten weeks. Serum samples and kidney tissues were collected for biochemical tests, pathological staining, transmission electron microscopy, fluorescencequantitation polymerase chain reaction, and western blotting analysis. In vitro experiments to elaborate the mechanism of celastrol protection were performed on high glucose (HG)-induced podocyte injury. Celastrol reduced blood glucose levels and renal function index in db/db mice, attenuated renal histomorphological injury and glomerular podocyte foot injuries, and induced significant anti-inflammatory effects. Celastrol upregulated silent information regulator 2 related enzyme 1(SIRT1) expression and downregulated enhancer of zeste homolog (EZH2), inhibiting the wnt/β-catenin pathway-related molecules, such as wnt1, wnt7a, and β-catenin. SIRT1 repressed the promoter activity of EZH2, and was co-immunoprecipitated with EZH2 in mouse podocyte cells (MPC5). SIRT1 knockdown aggravated the protective effects of celastrol on MPC5 cells. Celastrol protected podocyte injury via SIRT1/EZH2, which participates in the wnt/β-catenin pathway. Overall, celastrol-mediated SIRT1 upregulation inhibited the EZH2-related wnt/β-catenin signaling pathway to attenuate DN and podocyte injury, providing a theoretical basis for celastrol clinical application.

Therapeutic Potential Targeting Podocyte Mitochondrial Dysfunction in Focal Segmental Glomerulosclerosis

Background

Podocytes are essential components of the glomerular filtration barrier and essential for the proper filtration function of the glomerulus. Podocyte injury under various stress conditions is the primary pathogenesis and key determinant of focal segmental glomerulosclerosis (FSGS) with prominent clinical manifestations of proteinuria or nephrotic syndrome.

Summary

Under physiological conditions, a highly coordinated mitochondrial quality control system, including antioxidant defenses, mitochondrial dynamics (fusion, fission, and mitophagy), and mitochondrial biogenesis, guarantees the sophisticated structure and various functions of podocytes. However, under FSGS pathological conditions, mitochondria encounter oxidative stress, dynamics disturbances, and defective mitochondrial biogenesis. Moreover, mutations in mitochondrial DNA and mitochondria-related genes are also strongly associated with FSGS. Based on these pieces of evidence, bioactive agents that function to relieve mitochondrial oxidative stress and promote mitochondrial biogenesis have been proven effective in preclinical FSGS models. Targeting the mitochondrial network is expected to provide new therapeutic strategies for the treatment of FSGS and delay its progression to end-stage renal disease.

Key Messages

Mitochondrial dysfunction plays a key role in podocyte injury and FSGS progression. This review summarized recent advances in the study of mitochondrial homeostatic imbalance and dysfunction in FSGS and discussed the potential of mitochondria-targeted therapeutics in improving FSGS and retarding its progression to end-stage renal disease.

Knockdown of USF2 inhibits pyroptosis of podocytes and attenuates kidney injury in lupus nephritis

As an essential factor in the prognosis of Systemic lupus erythematosus (SLE), lupus nephritis (LN) can accelerate the rate at which patients with SLE can transition to chronic kidney disease or even end-stage renal disease (ESRD). Proteinuria due to decreased glomerular filtration rate following podocyte injury is LN's most common clinical manifestation. Podocyte pyroptosis and related inflammatory factors in its process can promote lupus to involve kidney cells and worsen the occurrence and progression of LN, but its regulatory mechanism remains unknown. Accumulating evidence has shown that upstream stimulatory factor 2 (USF2) plays a vital role in the pathophysiology of kidney diseases. In this research, multiple experiments were performed to investigate the role of USF2 in the process of LN. USF2 was abnormally highly expressed in MRL/lpr mice kidney tissues. Renal function impairment and USF2 mRNA levels were positively correlated. Silencing of USF2 in MRL/lpr serum-stimulated cells significantly reduced serum-induced podocyte pyroptosis. USF2 enhanced NLRP3 expression at the transcriptional level. Silencing of USF2 in vivo attenuated kidney injury in MRL/lpr mice, which suggests that USF2 is important for LN development and occurrence.

Glycyrrhizic acid alters the hyperoxidative stress-induced differentiation commitment of MSCs by activating the Wnt/β-catenin pathway to prevent SONFH

This study aimed to examine the in vivo and in vitro therapeutic effects of glycyrrhizic acid (GA) on steroid-induced osteonecrosis of the femoral head (SONFH), which is caused by the overuse of glucocorticoids (GCs). Clinically, we identified elevated oxidative stress (OS) levels and an imbalance in osteolipogenic homeostasis in SONFH patients compared to femoral neck fracture (FNF) patients. In vivo, we established experimental SONFH in rats via lipopolysaccharides (LPSs) combined with methylprednisolone (MPS). We showed that GA and Wnt agonist-S8320 alleviated SONFH, as evidenced by the reduced microstructural and histopathological alterations in the subchondral bone of the femoral head and the decreased levels of OS in rat models. In vitro, GA reduced dexamethasone (Dex)-induced excessive NOX4 and OS levels by activating the Wnt/β-catenin pathway, thereby promoting the osteogenic differentiation of mesenchymal stem cells (MSCs) and inhibiting lipogenic differentiation. In addition, GA regulated the expression levels of the key transcription factors downstream of this pathway, Runx2 and PPARγ, thus maintaining osteolipogenic homeostasis. In summary, we demonstrated for the first time that GA modulates the osteolipogenic differentiation commitment of MSCs induced by excessive OS through activating the Wnt/β-catenin pathway, thereby ameliorating SONFH.

LDP alleviates TKI-induced proteinuria through reversing the expression of RelA in renal tissues

Tyrosine kinase inhibitors (TKIs), as an important tumor therapy, can induce severe proteinuria that significantly affects anti-tumor therapy. Existing therapies against proteinuria induced by other etiologies are currently ineffective for TKI-induced proteinuria. It has been shown that various types of proteinuria are related to podocyte damage caused by changes in the RelA signaling pathway. Our experiments confirmed that TKIs activate the renal RelA signaling pathway, and induce death of podocytes and destruction of the glomerular filtration barrier. Here we found that Liuwei Dihuang Pill (LDP) attenuated the inflammatory injury of podocytes through inhibiting activation of RelA, and subsequently relieved TKI-related proteinuria and prevented the progression of TMA and FSGS. Our finding indicated that LDP may be effective for the treatment of TKI-induced proteinuria, which is clinically significant.

Contribution of IL-33/ILC2-mediated Th2 cytokines during the progression of minimal change disease

Minimal change disease (MCD) is a common type of nephrotic syndrome with high recurrence rate. This study aims to explore the impacts of interleukin (IL)-33 in MCD and to discuss its potential mechanism. In adriamycin (ADM) and puromycin aminonucleoside (PAN)-induced MCD rat model, IL-33 was used for treatment. H&E staining was applied for detecting histological changes. Critical proteins were examined by western blot. Corresponding commercial kits tested oxidative stress- and inflammation-related factors. Cell apoptosis was measured by TUNEL assay. ADM-induced podocyte injury model was establish to mimic MCD in vitro. Cell proliferation and apoptosis were detected by CCK-8 and TUNEL assays. Finally, podocyte was stimulated by innate lymphoid type-2 cells-secreted Th2 cytokines (ILC2s: IL-13 and IL-5 respectively), with or without incubation with M1 macrophage medium to further explore the immune-regulation of ILC2s behind the inflammatory environment of MCD. It was found that PAN-induced kidney jury, inflammation, oxidative stress and apoptosis were severer than ADM, and IL-33 treatment significantly alleviated the above injuries in PAN and ADM-induced MCD rat model. Moreover, IL-33 reversed the reduced viability and increased oxidative stress and apoptosis in ADM-induced podocyte injury model. Further, the capacities of IL-13 alone in inducing M1/M2 macrophage polarization, apoptosis, inflammation, kidney injury and reducing cell viability are stronger than IL-5. However, IL-13 reversed reduced cell viability and stimulated apoptosis, inflammation, kidney injury mediated by co-incubation with M1-conditioned medium. Collectively, IL-33 might protect against immunologic injury in MCD via mediating ILC2s-secreted IL-13.

Sestrin2 Signaling Pathway Regulates Podocyte Biology and Protects against Diabetic Nephropathy

Sestrin2 regulates cell homeostasis and is an upstream signaling molecule for several signaling pathways. Sestrin2 leads to AMP-activated protein kinase- (AMPK-) and GTPase-activating protein activity toward Rags (GATOR) 1-mediated inhibition of mammalian target of rapamycin complex 1 (mTORC1), thereby enhancing autophagy. Sestrin2 also improves mitochondrial biogenesis via AMPK/Sirt1/peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) signaling pathway. Blockade of ribosomal protein synthesis and augmentation of autophagy by Sestrin2 can prevent misfolded protein accumulation and attenuate endoplasmic reticulum (ER) stress. In addition, Sestrin2 enhances P62-mediated autophagic degradation of Keap1 to release nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2 release by Sestrin2 vigorously potentiates antioxidant defense in diabetic nephropathy. Impaired autophagy and mitochondrial biogenesis, severe oxidative stress, and ER stress are all deeply involved in the development and progression of diabetic nephropathy. It has been shown that Sestrin2 expression is lower in the kidney of animals and patients with diabetic nephropathy. Sestrin2 knockdown aggravated diabetic nephropathy in animal models. In contrast, upregulation of Sestrin2 enhanced autophagy, mitophagy, and mitochondrial biogenesis and suppressed oxidative stress, ER stress, and apoptosis in diabetic nephropathy. Consistently, overexpression of Sestrin2 ameliorated podocyte injury, mesangial proliferation, proteinuria, and renal fibrosis in animal models of diabetic nephropathy. By suppressing transforming growth factor beta (TGF-β)/Smad and Yes-associated protein (YAP)/transcription enhancer factor 1 (TEF1) signaling pathways in experimental models, Sestrin2 hindered epithelial-mesenchymal transition and extracellular matrix accumulation in diabetic kidneys. Moreover, modulation of the downstream molecules of Sestrin2, for instance, augmentation of AMPK or Nrf2 signaling and inhibition of mTORC1, has been protective in diabetic nephropathy. Regarding the beneficial effects of Sestrin2 on diabetic nephropathy and its interaction with several signaling molecules, it is worth targeting Sestrin2 in diabetic nephropathy.

Therapeutic potential of artemisinin and its derivatives in managing kidney diseases

Artemisinin, an antimalarial traditional Chinese herb, is isolated from Artemisia annua. L, and has shown fewer side effects. Several pieces of evidence have demonstrated that artemisinin and its derivatives exhibited therapeutic effects on diseases like malaria, cancer, immune disorders, and inflammatory diseases. Additionally, the antimalarial drugs demonstrated antioxidant and anti-inflammatory activities, regulating the immune system and autophagy and modulating glycolipid metabolism properties, suggesting an alternative for managing kidney disease. This review assessed the pharmacological activities of artemisinin. It summarized the critical outcomes and probable mechanism of artemisinins in treating kidney diseases, including inflammatory, oxidative stress, autophagy, mitochondrial homeostasis, endoplasmic reticulum stress, glycolipid metabolism, insulin resistance, diabetic nephropathy, lupus nephritis, membranous nephropathy, IgA nephropathy, and acute kidney injury, suggesting the therapeutic potential of artemisinin and its derivatives in managing kidney diseases, especially the podocyte-associated kidney diseases.

A study of the molecular mechanism of quercetin and dasatinib combination as senolytic in alleviating age-related and kidney diseases

Aging is a significant risk factor for the majority of prevalent human illnesses. The chance of having severe chronic conditions grows dramatically with advancing age. Indeed, more than 90% of people over 65 get at least one chronic disease, including diabetes, heart disease, malignancy, memory loss, and kidney disease, whereas more than 70% have two or more of these ailments. Mouse and human aging lead to increased senescent cells and decreased klotho concentrations. Mice lacking the protein α-klotho show faster aging, similar to human aging. α-Klotho upregulation extends life and slows or suppresses the onset of many age-related illnesses and kidney diseases. Like the consequences of α-klotho deficiency, senescent cell accumulation is linked to tissue dysfunction in various organs and multiple age-related kidney diseases. In addition, α-klotho and cell senescence are negatively and presumably mechanistically linked. Earlier research has demonstrated that klotho exerts its protective effects in age-related and kidney disease by interacting with Wnt ligands, serving as an endogenous antagonist of Wnt/β-catenin signaling. In addition, decreasing senescent cell burden with senolytics, a class of drugs that remove senescent cells selectively and extend the life span of mice. In this work, we are studying the molecular mechanism of the combination of quercetin and dasatinib as senolytic in easing age-related chronic renal illness by altering the level of klotho/Wnt/β-catenin. PRACTICAL APPLICATIONS: There is an inverse relationship between the onset and the development of age-related disorders and cellular senescence and Klotho. Earlier attempts to suppress transforming growth factor-beta 1 (TGF-β1) in kidney disease with anti-TGF-β1 antibodies were ineffective, and this should be kept in mind. Senolytic medications may benefit from targeting senescent cells, which enhances the protective factor α-klotho. In addition, our study provides a unique, translationally feasible route for creating orally active small compounds to enhance α-klotho, which may also be a valuable biomarker for age-related kidney disease. Additionally, other aspects of aging can be affected by senolytics, such as limiting age-related mitochondrial dysfunction, lowering inflammation and fibrosis, blunting reactive oxygen species (ROS) generation, decreasing deoxyribonucleic acid (DNA) damage, and reinforcing insulin sensitivity. Senolytic agents have been shown to increase adipose progenitor and cardiac progenitor cell activity in aging animals and animals with cellular senescence-related diseases, such as heart, brain, and kidney disease.