Research progress on multiple cell death pathways of podocytes in diabetic kidney disease

Mitigation of Ferroptosis in Diabetic Kidney Disease Through Mesenchymal Stem Cell Intervention via the Smad2/3/METTL3/S1PR1 Axis

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD) and is associated with heightened cardiovascular risk and increased overall mortality. Although mesenchymal stem cells (MSCs) have demonstrated therapeutic potential in DKD, their precise mechanisms of action have not been fully elucidated. This study aimed to investigate the involvement of Smad signaling, N6-methyladenosine (m6A) modifications, and ferroptosis in MSC-mediated treatment of DKD. Cellular and animal models of DKD were used to evaluate MSC intervention effects, supported by gene knockdown and overexpression experiments. Protein expression and phosphorylation levels of Smad2/3, m6A-associated enzymes, and markers of ferroptosis were assessed. Additionally, transcriptional targets associated with ferroptosis were identified through integrated transcriptome and m6A methylation sequencing analyses, followed by subsequent validation. Elevated Smad2/3 phosphorylation and ferroptosis were observed in DKD, while MSC interventions effectively alleviated these processes, resulting in improved renal lesions. Furthermore, MSC treatment reduced the heightened levels of m6A modification observed in DKD. Mechanistic investigations identified methyltransferase-like 3 (METTL3) as a key regulator of m6A modification in DKD. Suppression of METTL3 reversed the upregulated m6A modification and ferroptosis induced by Smad2 overexpression. Importantly, sphingosine-1-phosphate receptor 1 (S1PR1) was identified as a protective target gene against ferroptosis in DKD. In DKD models, Smad2 facilitated the m6A modification of the S1PR1 gene by interacting with METTL3 following its nuclear translocation, thereby influencing S1PR1 expression and promoting cellular ferroptosis. Intervention with MSCs mitigated this process, providing further insights into the regulatory mechanisms through which MSCs modulate ferroptosis in podocytes affected by DKD.

From fat to filter: the effect of adipose tissue-derived signals on kidney function

Obesity is associated with severe consequences for the renal system, including chronic kidney disease, kidney failure and increased mortality. Obesity has both direct and indirect effects on kidney health through several mechanisms, including activation of the renin-angiotensin system, mechanical compression, inflammation, fibrosis, increased filtration barrier permeability and renal nerve activity. The expansion of adipose tissue through hypertrophy and hyperplasia can induce haemodynamic changes that promote glomerular hyperfiltration to compensate for the greater metabolic demands of the increased body weight. Adipose expansion is also associated with the release of adipokines and pro-inflammatory cytokines, hyperinsulinaemia and insulin resistance, which exert direct and indirect effects on kidney function via various mechanisms. Increased uptake of fatty acids by the kidney leads to alterations in lipid metabolism and lipotoxicity, also contributing to the pro-inflammatory and pro-fibrotic environment. The role of the adipose tissue-brain-kidney axis in the obesity-associated decline in renal function is sustained by studies showing that stimulation of adipose tissue sensory neurons by locally released factors increases renal sympathetic nerve activity. Conversely, pre-existent kidney disease can contribute to adipose dysfunction through the accumulation of uraemic toxins and hormonal changes. These findings highlight the importance of crosstalk between adipose tissue and the kidneys and provide insights into the mechanisms underlying the associations between obesity and kidney disease.

Shenzhuo formulation ameliorates diabetic nephropathy by regulating cytochrome P450-mediated arachidonic acid metabolism

BACKGROUND

Diabetic nephropathy (DN) is a major complication of diabetes, marked by progressive renal damage and an inflammatory response. Although research has investigated the pathological mechanisms underlying DN, effective treatment options remain limited.

AIM

To evaluate the therapeutic impact of Shenzhuo formulation (SZF) on a DN mouse model and to examine its potential molecular mechanisms using transcriptomic and metabolomic approaches.

METHODS

We established a DN mouse model through a high-fat diet combined with streptozotocin (STZ) injection, followed by SZF treatment. We analyzed SZF’s effects on gene expression and metabolite profiles in renal tissues of DN mice using transcriptomics and metabolomics techniques. Additionally, based on transcriptomic and non-targeted metabolomic findings, we further assessed SZF’s influence on the expression of factors related to the cytochrome P450 (CYP450)-mediated arachidonic acid (AA) metabolism pathway, as well as its effects on inflammation and oxidative stress.

RESULTS

SZF intervention significantly decreased hyperglycemia and mitigated renal function impairment in DN mice. Pathological analysis revealed that SZF treatment improved renal tissue damage, reduced fibrosis, and diminished glycogen deposition. Transcriptomic analysis indicated that SZF influenced mRNA expression of CYP450-related genes, including Cyp2j13, Cyp2b9, Pla2 g2e/Cyp4a12a, Cyp4a32, Cyp2e1, and Cyp4a14. Non-targeted metabolomic results demonstrated that SZF altered the levels of metabolites associated with the AA metabolic pathway, including 5,6-EET, 14,15-EET, phosphatidylcholine, and 20-HETE. Further experiments showed that SZF upregulated the expression of CYP4A and CYP2E proteins in renal tissue, as well as CYP2J and CYP2B proteins. Additionally, SZF significantly reduced the expression of inflammatory factors in renal tissue, enhanced antioxidant enzyme activity, and alleviated oxidative stress.

CONCLUSION

SZF exerts anti-inflammatory and antioxidant effects by regulating CYP450-mediated AA metabolism, leading to improved renal function and improved pathological state in DN mice.

Cross Talk Between Macrophages and Podocytes in Diabetic Nephropathy: Potential Mechanisms and Novel Therapeutics

Diabetic nephropathy (DN) is a leading cause of chronic kidney disease and end-stage renal failure worldwide. Podocytes, essential components of the glomerular filtration barrier (GFB), are profoundly affected in the diabetic milieu, resulting in structural and functional alterations. Concurrently, macrophages, pivotal innate immune cells, infiltrate the diabetic kidney and exhibit diverse activation states influenced by the local environment, playing a crucial role in kidney physiology and pathology. This review synthesizes current insights into how the dynamic cross talk between these two cell types contributes to the progression of DN, exploring the molecular and cellular mechanisms underlying this interaction, with a particular focus on how macrophages influence podocyte survival through various forms of cell death, including apoptosis, pyroptosis, and autophagy. The review also discusses the potential of targeting macrophages to develop more effective treatments for DN.

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.

Umbilical Cord Mesenchymal Stem Cells Attenuate Podocyte Injury in Diabetic Nephropathy Rats by Inhibiting Angpltl4/Integrin β3 in the Glomerulus

In this study, we investigated the therapeutic effects and mechanisms of umbilical cord mesenchymal stem cells (UCMSCs) in diabetic nephropathy (DN) ZDF (FA/FA) rats. The therapeutic effects were assessed by renal function tests, the urinary albumin-creatinine ratio, PAS staining, electron microscopy, and TGF-β1 expression in renal tissue. Subsequently, podocyte injury in renal tissue was detected by immunofluorescence staining for podocin. To further explore the underlying mechanism, serum Angptl4 levels were measured, and Angptl4, integrin β3, fibronectin, and podocin levels in renal tissue were analysed by Western blotting. In vitro, podocytes are stimulated with high glucose and then treated with UCMSCs, and podocyte activity and the expression of synaptopodin, Angptl4, and integrin β3 were observed. UCMSC significantly improve renal function, pathological injury, and podocyte injury in the ZDF (FA/FA) rats. Western blot revealed increased expression of Angptl4, integrin β3, and fibronectin in renal tissues of the DN group, and UCMSC treatment significantly downregulated those proteins. However, UCMSC showed no effects on serum Angptl4 concentration. Podocin expression in renal tissues was significantly restored by UCMSC treatment. In vitro, podocyte activity was decreased after high glucose stimulation and improved by UCMSC treatment. UCMSC restored the expression of synaptopodin, and Angptl4 and downstream integrin β3 were also inhibited. Our study suggested that UCMSC therapy could improve renal function and renal pathological changes in ZDF (FA/FA) rats. In addition, inhibition of the Angptl4/integrin β3 pathway is the potential mechanism by which UCMSC attenuates podocyte injury in the DN model.

Diabetic Kidney Disease: Disease Progression Driven by Positive Feedback Loops and Therapeutic Strategies Targeting Pathogenic Pathways

Diabetic kidney disease (DKD) is a major complication of diabetes mellitus, with its pathogenesis intricately regulated by dynamic feedback mechanisms. This comprehensive review systematically analyzes the hierarchical feedback networks driving DKD progression, spanning from systemic interactions to molecular cross-talks. We reveal that self-amplifying positive feedback loops dominate the disease process, manifested through three key dimensions: (1) The systemic triad of hyperglycemia-hypertension-proteinuria establishes a vicious cycle accelerating renal dysfunction; (2) Cellular homeostasis collapse through cross-amplified cell death modalities (apoptosis, pyroptosis, ferroptosis) and cell cycle dysregulation; (3) Molecular cascades centered on AGE/RAGE signaling that fuel chronic inflammation and fibrotic transformation. Collectively, these form a major positive feedback loop where PKC activation, oxidative stress propagation, and TGF-β-mediated fibrosis induced by hyperglycemia lead to progressive renal deterioration and fibrosis. Therapeutically, we propose a dual intervention strategy targeting both the acute phase through AGE/RAGE axis inhibition, coupled with chronic phase via precision modulation of fibrotic pathways. These findings redefine DKD progression as a self-reinforcing network disorder, providing a roadmap for developing multi-target therapies that disrupt pathological feedback loops while preserving renal repair mechanisms.

Klotho antiaging protein: molecular mechanisms and therapeutic potential in diseases

Klotho, initially introduced as an anti-aging protein, is expressed in the brain, pancreas, and most prominently in the kidney. The two forms of Klotho (membrane-bound and soluble form) have diverse pharmacological functions such as anti-inflammatory, anti-oxidative, anti-fibrotic, tumour-suppressive etc. The membrane-bound form plays a pivotal role in maintaining kidney homeostasis by regulating fibroblast growth factor 23 (FGF 23) signalling, vitamin D metabolism and phosphate balance. Klotho deficiency has been linked with significantly reduced protection against various kidney pathological phenotypes, including diabetic kidney disease (DKD), which is a major cause of chronic kidney disease leading to end-stage kidney disease. Owing to the pleiotropic actions of klotho, it has shown beneficial effects in DKD by tackling the complex pathophysiology and reducing kidney inflammation, oxidative stress, as well as fibrosis. Moreover, the protective effect of klotho extends beyond DKD in other pathological conditions, including cardiovascular diseases, alzheimer's disease, cancer, inflammatory bowel disease, and liver disease. Therefore, this review summarizes the relationship between Klotho expression and various diseases with a special emphasis on DKD, the distinct mechanisms and the potential of exogenous Klotho supplementation as a therapeutic strategy. Future research into exogenous Klotho could unravel novel treatment avenues for DKD and other diseases.

Hirsutine mitigates ferroptosis in podocytes of diabetic kidney disease by downregulating the p53/GPX4 signaling pathway

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease worldwide, and podocyte ferroptosis plays a crucial role in its pathogenesis. Hirsutine (HS) reduces blood glucose levels and improve insulin resistance in diabetic mice, suggesting its potential use in diabetes treatment. Here, we established a db/db mouse model of DKD and administered HS for 8 weeks. We found that HS decreased the concentrations of iron, reactive oxygen species (ROS), and malondialdehyde (MDA) in renal tissues. Furthermore, HS treatment restored mitochondrial morphology, increased Glutathione Peroxidase 4(GPX4) levels, and decreased p53 levels, alleviating podocyte loss in the DKD mouse model. However, the effects of HS were reversed by the p53 activator Nutlin-3. Therefore, we propose HS may mitigate podocyte injury in DKD by regulating the p53/GPX4 pathway, providing a novel strategy for targeting podocyte ferroptosis in DKD.

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.

Boeravinone C ameliorates lipid accumulation and inflammation in diabetic kidney disease by activating PPARα signaling

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Oxybaphus himalaicus Edgew. is a traditional Tibetan herbal medicine with kidney reinforcing and tonifying effects, which is commonly applied to treat nephritis. Boeravinone C has been identified as one of the primary constituents of O. himalaicus. However, the potential renal protective effects of boeravinone C remains unclear.

AIM OF THE STUDY

This research aimed to investigate the protective effects of boeravinone C on diabetic kidney disease and the underlying mechanisms.

MATERIALS AND METHODS

Streptozotocin (100 mg/kg) was intraperitoneally injected to induce DKD in mice. High glucose (50 mM)-induced HK-2 cells were utilized to investigate the mechanisms of boeravinone C against tubular injuries in vitro. Anti-DKD activity was assessed by measuring reactive oxygen species (ROS) levels, analyzing apoptosis through flow cytometry, and evaluating inflammation, apoptosis, and FAO-related proteins via Western blotting. Additionally, serum biochemical assays, as well as histopathological and immunohistochemical analyses of kidney tissues, were performed to explore the pharmacological effects of boeravinone C.

RESULTS

In vivo, boeravinone C administered significantly reduced the creatinine (CRE), blood urea nitrogen (BUN), triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels in serum of DKD mice. In vitro, boeravinone C significantly restored the apoptosis induced by HG in HK-2 cells, which is further validated by an upregulation of the apoptosis-inhibiting protein Bcl-2, along with a decreased expression of the apoptosis-promoting proteins Bax and caspase-3. Mechanistically, boeravinone C reversed HG-induced downregulation of peroxisome proliferator-activated receptor α (PPARα) expression. As a transcription factor, elevated expression of PPARα led to upregulation of CPT1A and ACOX1, which then enhanced fatty acid oxidation (FAO) to reduce lipid accumulation in HK-2 cells. Furthermore, boeravinone C-mediated high expression of PPARα sequestered p65 subunit of NF-κB in the cytoplasm, leading to reduced expression of proinflammatory cytokines such as iNOS, TNF-α and IL-6. To verify that the therapeutic effects of boeravinone C in diabetic kidney disease (DKD) are mediated via PPARα activation, we developed a PPARα knockdown HK-2 cell line. Our findings revealed that PPARα downregulation modified biological effects of boeravinone C, especially regarding fatty acid metabolism and the inflammatory response, with significant repercussions on apoptosis.

CONCLUSION

This study demonstrates that the major component boeravinone C from O. himalaicus promotes the fatty acid oxidation and suppresses inflammatory response by upregulating PPARα expression, thereby reducing apoptosis in HG-induced renal tubule cells. Consequently, boeravinone C restores tubular function in DKD mice. Collectively, this study provides a pharmacological basis for utilizing of O. himalaicus in treating DKD.

Targeting endoplasmic reticulum stress: an innovative therapeutic strategy for podocyte-related kidney diseases

The endoplasmic reticulum (ER) is a vital organelle responsible for protein quality control, including the folding, modification, and transport of proteins. When misfolded or unfolded proteins accumulate in the ER, it triggers endoplasmic reticulum stress (ERS) and activates the unfolded protein response (UPR) to restore ER homeostasis. However, prolonged or excessive ERS can lead to apoptosis. The kidneys play a crucial role in maintaining physiological functions by excreting metabolic waste, regulating blood volume, balancing electrolytes and acid-base levels, and secreting various bioactive substances. Podocytes, epithelial cells situated outside the glomerular basement membrane, are essential for maintaining the structural integrity and permeability of the glomerular filtration barrier. Previous studies have shown that ERS in podocytes can contribute to the development of diseases such as glomerulonephritis, hereditary nephropathy, and diabetic kidney disease, potentially progressing to end-stage renal disease and causing patient mortality. As such, investigating ERS in podocytes has become a key area of focus in kidney disease research. This study examines recent advancements in understanding the effects of excessive ERS on podocytes across various kidney diseases, highlights the role of podocyte ERS in disease progression, and explores the potential therapeutic benefits of targeting the UPR to manage ERS in kidney diseases, thereby providing a scientific basis for clinical interventions.

Research hotspots and frontiers of endoplasmic reticulum in glomerular podocytes: a bibliometric and visual analysis from 2005 to 2023

Background

The glomerular podocyte endoplasmic reticulum is a critical component in renal function, yet its research landscape is not fully understood. This study aims to map the existing research on podocyte endoplasmic reticulum by analyzing publications in the Web of Science Core Collection (WOSCC) from the past 19 years.

Methods

We conducted a bibliometric analysis using Citespace, VOSviewer, the Metrology Literature Online platform, and the Bibliometrix software package to visualize and interpret the data from WOSCC. The analysis focused on publication volume, authorship, institutional contributions, and research trends.

Results

The analysis revealed a significant growth in publications, indicating a surge in interest in podocyte endoplasmic reticulum research. Cybulsky, Andrey V, and Papillon, Joan emerge as the most prolific authors, and the Journal of the American Society of Nephrology is the leading journal in this field. China is the top contributor in terms of publications, with McGill University being the most productive institution. The research primarily focuses on endoplasmic reticulum stress, diabetic nephropathy, and apoptosis, with emerging trends in "foot cell apoptosis," "cell signaling pathways," and "autophagy."

Conclusion

The findings highlight the expanding scope of podocyte endoplasmic reticulum research, with a particular emphasis on the mechanisms of endoplasmic reticulum stress and podocyte apoptosis. Future research directions may include the identification of specific therapeutic targets, detailed exploration of podocyte signaling pathways, and the role of autophagy. This study provides a comprehensive overview of the major research areas, frontiers, and trends in podocyte endoplasmic reticulum research, which are pivotal for guiding future investigations.

Activation of protein kinase B rescues against thapsigargin-elicited cardiac dysfunction through regulation of NADPH oxidase and ferroptosis

Endoplasmic reticulum (ER) stress is a known contributor to cardiac remodeling and contractile dysfunction. Although NADPH oxidase has been implicated in ER stress-induced organ damage, its specific role in myocardial complications resulting from ER stress remains unclear. This study aimed to investigate the possible involvement of NADPH oxidase in ER stress-induced myocardial abnormalities and to evaluate the impact of Akt constitutive activation on these myocardial defects. Mice with cardiac-specific overexpression of active mutant of Akt (Myr-Akt) and their wild-type (WT) littermates were treated with ER stress instigator thapsigargin (1 mg/kg, i. p. 72 hrs) before evaluating myocardial morphology and function. Our results noted that thapsigargin significantly impaired echocardiographic parameters and cell shortening indices, including elevated LVESD, decreased ejection fraction, fractional shortening, peak shortening, electrically-stimulated intracellular Ca2+ release, and cardiomyocyte survival. These functional deteriorations were accompanied by upregulation of NADPH oxidase, O2- production, mitochondrial damage, carbonyl formation, lipid peroxidation, apoptosis, and interstitial fibrosis, with unchanged myocardial size. Constitutive Akt hyperactivation did not generate any response on myocardial morphology and function, although it greatly suppressed or nullified thapsigargin-induced myocardial remodeling and dysfunction. Thapsigargin also triggered dephosphorylation of Akt and its downstream signal GSK3β, along with development of ferroptosis, all of which were nullified by Akt hyperactivation. In vitro studies further revealed that thapsigargin provoked cardiomyocyte mechanical anomalies and lipid peroxidation, similar to in vivo results. These effects were reverted by inhibitors of NADPH oxidase and ferroptosis (apocynin and LIP1). Collectively, our data denote an important protective role for Akt hyperactivation in thapsigargin-evoked myocardial anomalies, likely through NADPH oxidase-mediated regulation of ferroptosis.

Targeting programmed cell death in diabetic kidney disease: from molecular mechanisms to pharmacotherapy

Diabetic kidney disease (DKD), one of the most prevalent microvascular complications of diabetes, arises from dysregulated glucose and lipid metabolism induced by hyperglycemia, resulting in the deterioration of renal cells such as podocytes and tubular epithelial cells. Programmed cell death (PCD), comprising apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis, represents a spectrum of cell demise processes intricately governed by genetic mechanisms in vivo. Under physiological conditions, PCD facilitates the turnover of cellular populations and serves as a protective mechanism to eliminate impaired podocytes or tubular epithelial cells, thereby preserving renal tissue homeostasis amidst hyperglycemic stress. However, existing research predominantly elucidates individual modes of cell death, neglecting the intricate interplay and mutual modulation observed among various forms of PCD. In this comprehensive review, we delineate the diverse regulatory mechanisms governing PCD and elucidate the intricate crosstalk dynamics among distinct PCD pathways. Furthermore, we review recent advancements in understanding the pathogenesis of PCD and explore their implications in DKD. Additionally, we explore the potential of natural products derived primarily from botanical sources as therapeutic agents, highlighting their multifaceted effects on modulating PCD crosstalk, thereby proposing novel strategies for DKD treatment.

Regulation of pyroptosis and ferroptosis by mitophagy in chronic kidney disease

Chronic kidney disease (CKD) is a chronic progressive disease characterized by kidney injury or declining renal function. With its insidious onset and significant harm, CKD has become a major global public health concern. Abnormal cell death can directly or indirectly contribute to kidney injury, among which excessive pyroptosis and ferroptosis are central events in CKD pathogenesis. These two forms of cell death may interact through mechanisms such as reactive oxygen species release, further aggravating renal damage. Mitophagy, a selective autophagic process that removes damaged mitochondria, plays an important role in maintaining cellular homeostasis. In CKD, mitophagy is impaired; however, enhancing mitophagy signaling pathways can alleviate inflammation, reduce iron accumulation and lipid peroxidation in renal cells. This suggests that mitophagy may be a key regulator of pyroptosis and ferroptosis in kidney cells and holds potential as a novel target for the prevention, diagnosis, and treatment of CKD.

Methyltransferase-like 3 represents a prospective target for the diagnosis and treatment of kidney diseases

Kidney disease is marked by complex pathological mechanisms and significant therapeutic hurdles, resulting in high morbidity and mortality rates globally. A deeper understanding of the fundamental processes involved can aid in identifying novel therapeutic targets and improving treatment efficacy. Current comprehensive data analyses indicate the involvement of methyltransferase-like 3 (METTL3) and its role in RNA N6-methyladenosine methylation in various renal pathologies, including acute kidney injury, renal fibrosis, and chronic kidney disease. However, there is a paucity of thorough reviews that clarify the functional mechanisms of METTL3 and evaluate its importance in enhancing therapeutic outcomes. This review seeks to systematically examine the roles, mechanisms, and potential clinical applications of METTL3 in renal diseases. The findings presented suggest that METTL3 is implicated in the etiology and exacerbation of kidney disorders, affecting their onset, progression, malignancy, and responsiveness to chemotherapeutic agents through the regulation of specific genetic pathways. In conclusion, this review underscores a detrimental correlation between METTL3 and kidney diseases, highlighting the therapeutic promise of targeting METTL3. Additionally, it offers critical insights for researchers concerning the diagnosis, prognosis, and treatment strategies for renal conditions.

Therapeutic effects of natural compounds against diabetic complications via targeted modulation of ferroptosis

Diabetes mellitus, a chronic metabolic disorder, can result in serious tissue and organ damage due to long-term metabolic dysfunction, leading to various complications. Therefore, exploring the pathogenesis of diabetic complications and developing effective prevention and treatment drugs is crucial. The role of ferroptosis in diabetic complications has emerged as a significant area of research in recent years. Ferroptosis, a recently discovered form of regulated cell death closely linked to iron metabolism imbalance and lipid peroxidation, has garnered increasing attention in studies exploring the potential role of natural products in its regulation. This review provides an overview of the mechanisms underlying ferroptosis, outlines detection methods, and synthesizes information from natural product databases. It also summarizes current research on how natural products may regulate ferroptosis in diabetic complications. Studies have shown that these products can modulate the ferroptosis process by influencing iron ion balance and combating oxidative stress. This highlights the potential of natural products in treating diabetic complications by regulating ferroptosis, offering a new strategy for managing such complications.

Quercetin-4'-O-β-D-glucopyranoside inhibits podocyte injury by SIRT5-mediated desuccinylation of NEK7

Diabetic kidney disease (DKD) is a complication of diabetic mellitus. New treatments need to be developed. This study aimed to investigate the effects of quercetin-4'-O-β-D-glucopyranoside (QODG) on podocyte injury. Podocytes were cultured in high glucose (HG) medium, treated with QODG, and overexpressing or knocking down SIRT5. Oxidative stress indicators were assessed using corresponding kits. Pyroptosis was detected by flow cytometry and western blot analysis. Succinylation modification was detected using immunoprecipitation (IP) and western blot analysis. The interaction between NEK7 and NLRP3 was determined by co-IP. The results indicated that QODG inhibited oxidative stress and pyroptosis of podocytes induced by HG. Besides, QODG suppressed succinylation levels in HG-induced podocytes, with the upregulation of SIRT5. Knockdown of SIRT5 reversed the effects of QODG on oxidative stress and pyroptosis. Moreover, SIRT5 inhibited the succinylation of NEK7 and the interaction between NLRP3 and NEK7. In conclusion, QODG upregulates SIRT5 to inhibit the succinylation modification of NEK7, impedes the interaction between NEK7 and NLRP3, and then inhibits the pyroptosis and oxidative stress injury of podocytes under HG conditions. The findings suggested that QODG has the potential to treat DKD and explore a novel underlying mechanism of QODG function.

HNRNP I promotes IRAK1 degradation to reduce podocyte apoptosis and inflammatory response alleviating renal injury in diabetic nephropathy

Podocytes maintain renal filtration integrity when the glomerular filtration barrier (GFB) is integrated. Impairment or attrition of podocytes, leading to compromised GFB permeability, constitutes the primary etiology of proteinuria and is a hallmark pathological feature of diabetic nephropathy (DN). This study centers on Heterogeneous Nuclear Ribonucleoprotein I (HNRNP I), an RNA-binding protein, delineating its role in facilitating DN-induced renal damage by modulating podocyte health. Comparative analyses in renal biopsy specimens from DN patients and high-glucose-challenged podocyte models in vitro revealed a marked downregulation of HNRNP I expression relative to normal renal tissues and podocytes. In vitro assays demonstrated that high-glucose conditions precipitated a significant reduction in podocyte viability and an escalation in markers indicative of apoptosis. Conversely, HNRNP I overexpression was found to restore podocyte viability and attenuate apoptotic indices. IRAK1, a gene encoding a protein integral to inflammatory signaling, was shown to interact with HNRNP I, which promotes IRAK1 degradation. This interaction culminates in suppressing the PI3K/AKT/mTOR signaling pathway, thereby diminishing podocyte apoptosis and mitigating renal damage in DN. This investigation unveils the mechanistic role of HNRNP I in DN for the first time, potentially informing novel therapeutic strategies for DN renal impairment.

Research progress on Alpinia oxyphylla in the treatment of diabetic nephropathy

Diabetic nephropathy (DN) constitutes a major microvascular complication of diabetes and is a primary cause of mortality in diabetic individuals. With the global rise in diabetes, DN has become an urgent health issue. Currently, there is no definitive cure for DN. Alpinia oxyphylla, a Chinese herbal medicine traditionally used, exhibits a wide range of pharmacological effects and is frequently used in the prevention and management of DN. This paper offers an extensive review of the biological mechanisms by which A. oxyphylla delivers therapeutic advantages in DN management. These mechanisms include activating podocyte autophagy, regulating non-coding RNA, modulating gut microbiota, alleviating lipotoxicity, counteracting oxidative stress, and diminishing inflammatory responses, underscoring the therapeutic potential of A. oxyphylla in DN treatment.

Biomedicine and pharmacotherapeutic effectiveness of combinatorial atorvastatin and quercetin on diabetic nephropathy: An in vitro study

INTRODUCTION

Diabetic nephropathy is a type of kidney disorder that develops as a complication of multifactorial diabetes. Diabetic nephropathy is characterized by microangiopathy, resulting from glucose metabolism, oxidative stress, and changes in renal hemodynamics. This study strived to evaluate the in vitro cytoprotective activity of atorvastatin (ATR), and quercetin (QCT) alone and in combination against diabetic nephropathy.

METHODS

The MTT assay was utilized to analyze the effects of the test compounds on NRK-52E rat kidney epithelial cells. The detection of apoptosis and ability to scavenge free radicals was assessed via acridine orange-ethidium bromide (AO-EB) dual fluorescence staining, and 2,2-diphenyl-1-picrylhydrazyfree assay (DPPH), respectively. The ability of anti-inflammatory effect of the test compounds and western blot analysis against TGF-β, TNF-α, and IL-6 further assessed to determine the combinatorial efficacy.

RESULTS

Atorvastatin and quercetin treatment significantly lowered the expression of TGF-β, TNF-α, and IL-6 indicating the protective role in Streptozotocin-induced nephrotoxicity. The kidney cells treated with a combination of atorvastatin and quercetin showed green fluorescing nuclei in the AO-EB staining assay, indicating that the combination treatment restored cell viability. Quercetin, both alone and in combination with atorvastatin, demonstrated strong DPPH free radical scavenging activity and further encountered an anti-oxidant and anti-inflammatory effect on the combination of these drugs.

CONCLUSION

Nevertheless, there is currently no existing literature that reports on the role of QCT as a combination renoprotective drug with statins in the context of diabetic nephropathy. Hence, these findings suggest that atorvastatin and quercetin may have clinical potential in treating diabetic nephropathy.

Lipid metabolism disorder in diabetic kidney disease

Diabetic kidney disease (DKD), a significant complication associated with diabetes mellitus, presents limited treatment options. The progression of DKD is marked by substantial lipid disturbances, including alterations in triglycerides, cholesterol, sphingolipids, phospholipids, lipid droplets, and bile acids (BAs). Altered lipid metabolism serves as a crucial pathogenic mechanism in DKD, potentially intertwined with cellular ferroptosis, lipophagy, lipid metabolism reprogramming, and immune modulation of gut microbiota (thus impacting the liver-kidney axis). The elucidation of these mechanisms opens new potential therapeutic pathways for DKD management. This research explores the link between lipid metabolism disruptions and DKD onset.

Tangshen formula protects against podocyte apoptosis via enhancing the TFEB-mediated autophagy-lysosome pathway in diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease and currently there are no specific and effective drugs for its treatment. Podocyte injury is a detrimental feature and the major cause of albuminuria in DN. We previously reported Tangshen Formula (TSF), a Chinese herbal medicine, has shown therapeutic effects on DN. However, the underlying mechanisms remain obscure.

AIM OF THE STUDY

This study aimed to explore the protective effect of TSF on podocyte apoptosis in DN and elucidate the potential mechanism.

MATERIALS AND METHODS

The effects of TSF were assessed in a murine model using male KKAy diabetic mice, as well as in advanced glycation end products-stimulated primary mice podocytes. Transcription factor EB (TFEB) knockdown primary podocytes were employed for mechanistic studies. In vivo and in vitro studies were performed and results assessed using transmission electron microscopy, immunofluorescence staining, and western blotting.

RESULTS

TSF treatment alleviated podocyte apoptosis and structural impairment, decreased albuminuria, and mitigated renal dysfunction in KKAy mice. Notably, TSF extracted twice showed a more significant reduction in proteinuria than TSF extracted three times. Accumulation of autophagic biomarkers p62 and LC3, and aberrant autophagic flux in podocytes of DN mice were significantly altered by TSF therapy. Consistent with the in vivo results, TSF prevented the apoptosis of primary podocytes exposed to AGEs and activated autophagy. However, the anti-apoptosis capacity of TSF was countered by the autophagy-lysosome inhibitor chloroquine. We found that TSF increased the nuclear translocation of TFEB in diabetic podocytes, and thus upregulated transcription of its several autophagic target genes. Pharmacological activation of TFEB by TSF accelerated the conversion of autophagosome to autolysosome and lysosomal biogenesis, further augmented autophagic flux. Conversely, TFEB knockdown negated the favorable effects of TSF on autophagy in AGEs-stimulated primary podocytes.

CONCLUSIONS

These findings indicate TSF appears to attenuate podocyte apoptosis and promote autophagy in DN via the TFEB-mediated autophagy-lysosome system. Thus, TSF may be a therapeutic candidate for DN.

Exosomes derived from mesenchymal stem cells in diabetes and diabetic complications

Diabetes, a group of metabolic disorders, constitutes an important global health problem. Diabetes and its complications place a heavy financial strain on both patients and the global healthcare establishment. The lack of effective treatments contributes to this pessimistic situation and negative outlook. Exosomes released from mesenchymal stromal cells (MSCs) have emerged as the most likely new breakthrough and advancement in treating of diabetes and diabetes-associated complication due to its capacity of intercellular communication, modulating the local microenvironment, and regulating cellular processes. In the present review, we briefly outlined the properties of MSCs-derived exosomes, provided a thorough summary of their biological functions and potential uses in diabetes and its related complications.

Desmosterol-driven atypical macrophage polarization regulates podocyte dynamics in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) stands as a leading diabetes complication, with macrophages intricately involved in its evolution. While glucose metabolism's impact on macrophage activity is well-established, cholesterol metabolism's contributions remain less explored. Our study seeks to elucidate this association.

METHODS AND RESULTS

Methods and Results: Gene expression analysis of monocytes from the blood of both normal and diabetic patients was conducted using public databases, showing that cholesterol metabolism pathways, especially Bloch and Kandutsch-Russell, were more altered in diabetic monocytes/macrophages than glucose-responsive pathways. When bone marrow-derived macrophages (BMDMs) were subjected to desmosterol, they exhibited an unconventional polarization. These BMDMs displayed heightened levels of both M1-related pro-inflammatory cytokines and M2-linked anti-inflammatory factors. Further, in co-culture, desmosterol-conditioned BMDMs paralleled M2 macrophages in augmenting Ki-67 + podocyte populations while mimicking M1 macrophages in elevating TUNEL + apoptotic podocytes. Comparable outcomes on podocytes were obtained using conditioned media from the respective BMDMs.

CONCLUSIONS

Our data underscores the pivotal role of cholesterol metabolism, particularly via desmosterol, in steering macrophages toward an unconventional polarization marked by both inflammatory and regulatory traits. Such unique macrophage behavior concurrently impacts podocyte proliferation and apoptosis, shedding fresh light on DN pathogenesis and hinting at potential therapeutic interventions.

Triptolide Attenuates Renal Slit Diagram to Tight Junction Transition in Diabetic Kidney Disease by Regulating Nrf2-Ferroptosis Pathway

Diabetic kidney disease (DKD) is a prominent etiological factor underlying the onset of end-stage kidney disease, which is characterized by the presence of microalbuminuria. Recent studies have found that high glucose can induce mitochondrial dysfunction and ferroptosis in podocytes, leading to renal impairment and proteinuria. Triptolide was extracted from traditional Chinese medicine Tripterygium wilfordii Hook F., which has anti-inflammatory, anti-oxidant, and podocyte protective activities. Multiple studies have shown that triptolide can ameliorate proteinuria in DKD. However, the specific mechanisms remain unclear. This study investigates whether triptolide can reverse proteinuria in DKD by inhibiting ferroptosis in db/db mice and its specific protective mechanisms. The results demonstrate that triptolide could preserve podocytes and reduce proteinuria in db/db mice via inhibiting ferroptosis. In vivo and in vitro, the expression of glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH-1), and the cystine/glutamate reverse antiporter solute carrier family 7 member 11 (SLC7A11) were increased, and the production of transferrin receptor 1 (TFR-1) was decreased by triptolide. Moreover, triptolide suppressed oxidative stress and mitochondria dysfunction. Additionally, triptolide up-regulated the expression of NFE2-related factor 2 (Nrf2) and change the expression of its downstream targets related to ferroptosis. Furthermore, the podocyte actin cytoskeleton was stabilized by triptolide, and the transition from slit diaphragm (SD) to tight junction (TJ), which is a pivotal character of filtration barrier damage, was attenuated by triptolide. In conclusion, our results suggest that triptolide could stabilize the glomerular podocyte cytoskeleton and attenuate renal SD-TJ transition in DKD by upregulating Nrf2 and thereby inhibiting ferroptosis.