Autophagy in kidney homeostasis and disease

Vincamine induces cytoprotective autophagy via regulation of ampk/mtor signaling pathway in gentamicin-induced hepatotoxicity and nephrotoxicity in rats

Gentamicin (GET), a widely utilized aminoglycoside antibiotic for severe bacterial infections, is associated with significant hepatorenal toxicity. These adverse effects are frequently exacerbated by GET-induced oxidative stress and inflammation. This study aimed to evaluate the potential protective efficacy of vincamine (VIN) against GET-induced hepatic and renal damage. 4 groups of adult male rats were assigned: normal control (received CMC), GET (100 mg/kg, i.p.), VIN (40 mg/kg, p.o.), and GET/VIN (received both VIN and GET) for 7 days. Liver and kidney function tests were performed. Serum total antioxidant capacity (TAC) and tissue malondialdehyde (MDA) were quantified. To assess apoptosis, Bax and Bcl-2 mRNA levels were quantified using real-time polymerase chain reaction (RT-PCR), while cleaved caspase-3 protein levels were measured using ELISA. Histopathological alterations were also examined. The implication of autophagy was assessed by detecting AMPK, beclin-1, LC3 and mTOR proteins. Our results indicated that VIN significantly attenuated GET-induced hepatotoxicity and nephrotoxicity by mitigating oxidative stress and apoptosis. Mechanistically, VIN modulated apoptotic pathways by upregulating the anti-apoptotic Bcl-2 gene and downregulating the pro-apoptotic Bax gene. Notably, VIN potently enhanced autophagy through modulation of the AMPK/mTOR signaling pathway, evidenced by the upregulation of beclin1 and LC3 levels. Histopathological analysis further corroborated these findings, demonstrating that VIN markedly reduced the tissue damage associated with GET administration. VIN demonstrates potential as a cytoprotective agent against GET-induced hepatorenal toxicity. The protective effect of VIN may be attributed to its capacity to modulate the Bax/Bcl-2/Caspase-3-dependent apoptotic pathway and the AMPK/mTOR-mediated autophagy pathway.

Autophagic stagnation: a key mechanism in kidney disease progression linked to aging and obesity

Autophagy, a critical intracellular degradation and recycling pathway mediated by lysosomes, is essential for maintaining cellular homeostasis through the quality control of proteins and organelles. Our research focused on the role of proximal tubular autophagy in the pathophysiology of aging, obesity, and diabetes. Using a novel method to monitor autophagic flux in kidney tissue, we revealed that age-associated high basal autophagy supports mitochondrial quality control and delays kidney aging. However, an impaired ability to upregulate autophagy under additional stress accelerates kidney aging. In obesity induced by a high-fat diet, lysosomal dysfunction disrupts autophagy, leading to renal lipotoxicity. Although autophagy is initially activated to repair organelle membranes and maintain proximal tubular cell integrity, this demand overwhelms lysosomes, resulting in "autophagic stagnation" characterized by phospholipid accumulation. Similar lysosomal phospholipid accumulation was observed in renal biopsies from elderly and obese patients. We identified TFEB-mediated lysosomal exocytosis as a mechanism to alleviate lipotoxicity by expelling accumulated phospholipids. Therapeutically, interventions such as the SGLT2 inhibitor empagliflozin and eicosapentaenoic acid restore lysosomal function and autophagic activity. Based on these findings, we propose a novel disease concept, "Obesity-Related Proximal Tubulopathy." This study underscores autophagic stagnation as a key driver of kidney disease progression in aging and obesity, offering insights into the pathophysiology of kidney diseases and providing a foundation for targeted therapeutic strategies.

Hirsutine attenuated oxidative stress and autophagy in diabetic kidney disease through Keap1/Nrf2 pathway

OBJECTIVES

To investigate the therapeutic potential and renal protective mechanisms of hirsutine in diabetic kidney disease (DKD).

METHODS

A DKD model was induced in Sprague-Dawley rats using a high-fat diet (HFD) and streptozotocin (STZ). High glucose (HG)-stimulated HK-2 cells served as an in vitro model. Reactive oxygen species (ROS) levels in kidney tissues were measured using dihydroethidium (DHE) staining. ELISA was performed to measure MDA, SOD, and GSH in both rat tissues and HK-2 cells. Western blot and immunofluorescence analyses evaluated renal fibrosis, the Nrf2 signaling pathway, and autophagy-related proteins (Beclin 1, LC3I/II, P62).

RESULTS

Hirsutine treatment significantly improved metabolic and renal parameters in rats, enhancing renal function and reducing fibrosis, as shown by lower levels of Vimentin, Collagen-IV, and α-SMA. It alleviated oxidative stress, indicated by reduced ROS and MDA levels and increased SOD and GSH activity. Additionally, hirsutine enhanced autophagy, reflected by higher Beclin 1 and LC3I/II levels and decreased P62 expression. By disrupting the Keap1-Nrf2 interaction, hirsutine increased Nrf2 levels and upregulated antioxidative enzymes like NQO1, SOD-2, and HO-1.

CONCLUSION

Hirsutine exhibited renoprotective effects in DKD by modulating the Keap1/Nrf2 pathway, mitigating oxidative stress and promoting autophagy, making it a promising candidate for treatment.

Physical activity is associated with renal function in middle-aged and elderly populations in China: first cross-sectional and longitudinal evidence from CHARLS

OBJECTIVE

Chronic kidney disease (CKD) has become a common health problem among middle-aged and elderly people in China. The aim of this study was to investigate the effects of physical activity on renal function in Chinese middle-aged and elderly people.

STUDY DESIGN

Nationwide cohort study.

METHODS

3599 participants in the 2011 China Health and Aging Longitudinal Study (CHARLS) were used in the cross-sectional study, with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 as the endpoint event. 2309 participants in the 2015 CHARLS were used in the longitudinal study, with eGFR <60 ml/min/1.73 m2 or ≥25 % decrease in eGFR as the endpoint events. 2190 participants from the longitudinal study, after excluding those with baseline eGFR < 60 ml/min/1.73m2, were included in a sensitivity analysis to reassess the associations. Physical activity intensity was assessed by self-report. Associations between physical activity levels and renal function were analyzed using logistic regression.

RESULTS

In cross-sectional analyses, engaging in moderate (MPA) or vigorousphysical activity (VPA) for more than 300 min/week was associated with a significantly lower likelihood of renal endpoint events compared to physically inactive participants (OR = 0.39, 95 % CI: 0.30-0.51). After correction for clinical characteristics and blood test results, VPA and MPA >300 min/week remained independent protective factors for renal function. In the longitudinal cohort, VPA and MPA >300 min/w reduced the risk of renal endpoint events by 45 % (OR = 0.55, 95 % CI = 0.38-0.80). After correcting for clinical characteristics and blood test results, VPA and MPA >300min/w still reduced the risk of renal endpoint events by 37 % (OR = 0.63, 95 % CI = 0.43-0.92) and 39 % (OR = 0.61, 95 % CI: 0.42-0.89), respectively. Sensitivity analysis further confirmed the robustness of these findings, with VPA and MPA > 300 min/week consistently identified as independent protective factors.

CONCLUSIONS

Physical activity is associated with a reduced risk and delayed onset of renal insufficiency. The results of this study provide additional evidence for the renoprotective effects of exercise in non-CKD populations.

ShenQi ShenKang Granule Alleviates Chronic Kidney Disease by Inhibiting the PI3K/AKT/mTOR Pathway and Restoring Autophagy Flux and Mitochondrial Integrity

Purpose

This study investigates the effect of Shenqi Shenkang granule (SQSKG) on chronic kidney disease (CKD), focusing on regulating the PI3K/AKT/mTOR pathway, autophagy, and mitochondrial homeostasis.

Methods

The compounds and targets of SQSKG on CKD were identified by network pharmacology and validated by molecular docking. LC-MS/MS was used to verify the compounds screened by network pharmacology. In vitro experiments based on HK-2 cells were used to assess its impact on cell migration, viability, oxidative stress, and key proteins of the PI3K/AKT/mTOR pathway, autophagy, and fibrosis. Mitochondrial function and autophagic flux were evaluated via JC-1, Mito-Tracker, and Ad-mCherry-GFP-LC3B assays. In vivo, an adenine-induced CKD rat model was used to analyze renal function, fibrosis, and autophagy through serum/urine tests, histology, and immunofluorescence.

Results

Network pharmacology identified 49 compounds and 149 targets associated with SQSKG's therapeutic effects on CKD, highlighting critical targets such as AKT1, MAPK1, EGFR, HSP90AA, and IGF1R. The primary mechanism involves the PI3K/AKT pathway. In vitro experiments demonstrated that SQSKG significantly enhanced cell migration, colony formation, viability in AGEs-treated HK-2 cells, and exhibited robust antioxidant properties by increasing SOD levels and reducing MDA and ROS production. SQSKG effectively inhibited the phosphorylation of PI3K, AKT, and mTOR, and reduced TGF-β fluorescence intensity in kidney tissue. Autophagic flux analysis showed that SQSKG increased autophagic activity and reduced p62 accumulation. Additionally, JC-1 and Mito-Tracker Green assays demonstrated that SQSKG improved mitochondrial membrane potential and morphology. In vivo, SQSKG significantly improved renal function and alleviated renal fibrosis in a dose-dependent manner, reversing fibrosis marker overexpression (Col-I, α-SMA, TGF-β) and activating autophagy.

Conclusion

Our findings provide novel insights into the therapeutic potential of SQSKG in CKD management, highlighting its ability to modulate PI3K/AKT/mTOR pathway, activating autophagy flux, and restoring mitochondrial integrity, thereby offering a promising complementary or alternative treatment option for patients with CKD.

Regulation of autophagy by the PI3K-AKT pathway in Astragalus membranaceus -Cornus officinalis to ameliorate diabetic nephropathy

Aims and background

Autophagy plays an increasingly significant role in diabetic nephropathy (DN), but the mechanism by which autophagy participates in DN injury is not well understood. Our previous studies have shown that Astragalus membranaceus - Cornus officinalis (AM-CO) improves DN lipid metabolism disorders, however, the exact mechanism of which is also not well defined. The aim of this study was to investigate the therapeutic effects of AM-CO officinalis on DN and the mechanism of action on DN using lipidomic techniques and network pharmacological approaches.

Experimental methods

The in vivo experiments were carried out using the KKAy mice model with the intervention of AM-CO. Analysis of kidney and serum samples from KKAy mice treated with AM-CO using lipidomic technology to obtain biomarkers for the treatment of DN and to identify the main targets associated with DN; Analyse potential signalling pathways for the treatment of DN using network pharmacology methods. In vitro experiments were performed with PA-induced HK-2 cells and results verified by protein blotting and immunofluorescence.

Results

Lipidomic analysis revealed 363 differential metabolites in serum and 195 differential metabolites in kidney tissue, which were compared and analysed to find their common differential metabolites belonging to the phosphatidylethanolamine (PE) classes, respectively. In addition, PE plays a vital functiona in the process of autophagy. And the network analysis results speculated that Calycosin (Cal), a major component of AM-CO, could ameliorate DN injury by regulating autophagy through modulating the PI3K-AKT signaling pathway. In vivo experiments showed that AM-CO could induce autophagy, an increase in LC3II expression and a decrease in P62 expression. Meanwhile, in vitro experiments showed that Cal could also increase the expression of LC3II and inhibit the protein expression levels of p62, PI3K, P-AKT and AKT. The addition of a PI3K activator resulted in a reversal of protein expression.

Conclusion

In conclusion, Cal can ameliorate the injury in DN by regulating autophagy, and PI3K-AKT is the main pathway for its regulation of autophagy and a key pathway for the action of AM-CO.

Autophagy Related 5 Promotes Mitochondrial Fission and Inflammation via HSP90-HIF-1α-Mediated Glycolysis in Kidney Fibrosis

Although significant progress in identifying molecular mediators of fibrosis is made, there is still controversy regarding the role and mechanism of autophagy in kidney fibrosis. Here, this study finds that autophagy related 5 (ATG5) is obviously increased in uric acid (UA), aristolochic acid (AA) and transforming growth factor-β1 (TGF-β1)-induced HK-2 cells, as well as in kidneys from patients with chronic kidney disease (CKD) and mice with hyperuricemic nephropathy (HN), aristolochic acid nephropathy (AAN) and unilateral renal ischemia-reperfusion injury (uIRI). Conditional deletion of ATG5 in HN, AAN and uIRI murine models significantly alleviated aberrant glycolysis, attenuated pathological lesions, and improved kidney function. Mechanistically, ATG5 mediates the binding between heat shock protein 90 (HSP90) and hypoxia-inducible factor 1alpha (HIF-1α), thereby enhancing the stability of HIF-1α and further promoting the overactivation of glycolysis. Subsequently, the aberrant glycolysis facilitated the occurrence of mitochondrial fission and inflammatory response, thus leading to kidney fibrosis. Taken together, the study provides solid evidence supporting that persistent activation of ATG5 in kidney tubules promotes kidney fibrosis. The profibrotic function of ATG5 is related to the regulation on HSP90-HIF-1α-mediated glycolysis, resulting in mitochondrial fission and renal inflammation. Thus, ATG5 may be a novel therapeutic target for kidney fibrosis.

The boundaries of normal kidney tissue for biomedical research

PURPOSE OF REVIEW

In this review, we highlight the importance of understanding the inherent biological variability in normal kidney, or healthy reference tissue, to establish an accurate reference point for biomedical research. We explore this and the advantages and limitations of various sources of healthy reference tissue suitable for structural and omics-level studies.

RECENT FINDINGS

Several large consortia are employing omic technologies for diseased and normal kidney tissue, underscoring the importance of utilizing healthy reference tissue in these studies. Emerging approaches, such as artificial intelligence and multiomic analyses, are expanding our understanding of structural and molecular heterogeneity in healthy reference kidney tissue and uncovering new insights.

SUMMARY

Biological variability in healthy reference tissue at the functional, structural, and molecular level is complex and remains an active area of study. Thoughtful selection of healthy reference tissue sources is critical, providing the greatest potential for producing high-quality research outcomes.

WWP2 deletion aggravates acute kidney injury by targeting CDC20/autophagy axis

INTRODUCTION

Acute kidney injury (AKI) is associated with high morbidity and mortality rates. The molecular mechanisms underlying AKI are currently being extensively investigated. WWP2 is an E3 ligase that regulates cell proliferation and differentiation. Whether WWP2 plays a regulatory role in AKI remains to be elucidated.

OBJECTIVES

We aimed to investigate the implication of WWP2 in AKI and its underlying mechanism in the present study.

METHODS

We utilized renal tissues from patients with AKI and established AKI models in global or tubule-specific knockout (cKO) mice strains to study WWP2's implication in AKI. We also systemically analyzed ubiquitylation omics and proteomics to decipher the underlying mechanism.

RESULTS

In the present study, we found that WWP2 expression significantly increased in the tubules of kidneys with AKI. Global or tubule-specific knockout of WWP2 significantly aggravated renal dysfunction and tubular injury in AKI kidneys, whereas WWP2 overexpression significantly protected tubular epithelial cells against cisplatin. WWP2 deficiency profoundly affected autophagy in AKI kidneys. Further analysis with ubiquitylation omics, quantitative proteomics and experimental validation suggested that WWP2 mediated poly-ubiquitylation of CDC20, a negative regulator of autophagy. CDC20 was significantly decreased in AKI kidneys, and selective inhibiting CDC20 with apcin profoundly alleviated renal dysfunction and tubular injury in the cisplatin model with or without WWP2 cKO, indicating that CDC20 may serve as a downstream target of WWP2 in AKI. Inhibiting autophagy with 3-methyladenine blocked apcin's protection against cisplatin-induced renal tubular cell injury. Activating autophagy by rapamycin significantly protected against cisplatin-induced AKI in WWP2 cKO mice, whereas inhibiting autophagy by 3-methyladenine further aggravated apoptosis in cisplatin-exposed WWP2 KO cells.

CONCLUSION

Taken together, our data indicated that the WWP2/CDC20/autophagy may be an essential intrinsic protective mechanism against AKI. Further activating WWP2 or inhibiting CDC20 may be novel therapeutic strategies for AKI.

SuoquanYishen formula improves renal cellular senescence by inhibiting YTHDF1-Rubicon axis to promote autophagy in diabetic kidney disease

SuoquanYishen formula (SQYSF), a traditional Chinese herbal prescription for treating diabetic kidney disease (DKD), has demonstrated clinical efficacy in lowering blood glucose and alleviating renal damage. Emerging evidence implicates cellular senescence as a critical contributor to DKD progression. This study aimed to elucidate the mechanism by which SQYSF improves renal cellular senescence using both in vivo (db/db mice) and in vitro (high glucose-induced HK-2 cells) DKD models, with interventions involving SQYSF aqueous extract and SQYSF-containing serum. We screened 59 chemical compounds by UHPLC-QTOF-MS and used network pharmacology approach to discover that autophagy and cellular senescence are important pathways for pharmacological treatment of disease. Experimental validation demonstrated that senescence and damage occurred in the kidneys of db/db mice and HK-2 cells under high glucose environment, and SQYSF ameliorated these abnormal changes. Then, we also found that SQYSF enhanced autophagy in renal tissues and cells, whereas co-treatment with the autophagy inhibitor Bafilomycin A1 abolished SQYSF's anti-senescence effects. Notably, DKD progression was associated with elevated Rubicon expression at mRNA and protein levels, accompanied by increased m6A modification. While SQYSF effectively downregulated Rubicon mRNA and protein expression, it did not influence m6A modification levels. Further investigation identified that SQYSF was able to target to reduce YTHDF1 expression level. Overexpression of YTHDF1 in HK-2 cells increased Rubicon mRNA stability and protein expression, while concurrently reversing SQYSF-induced autophagy enhancement and senescence amelioration. These results suggest that SQYSF exerts its role in ameliorating renal cellular senescence in DKD by targeting to reduce the expression level of YTHDF1, which inhibits the level of Rubicon mRNA and protein translation, and thus promotes autophagy. Our results reveal the active components and mechanisms of SQYSF for the treatment of DKD, which may provide useful information to guide the clinical application of SQYSF as well as the therapeutic pathway for DKD.

mTOR-mediated nutrient sensing and oxidative stress pathways regulate autophagy: a key mechanism for traditional Chinese medicine to improve diabetic kidney disease

Context

Autophagy plays a pivotal role in the pathogenesis of DKD, and the mechanistic target of rapamycin (mTOR) pathway, which regulates nutrient sensing and oxidative stress responses, is a key regulator of autophagy. Traditional Chinese Medicine (TCM) has garnered attention for its potential to treat DKD by modulating the mTOR signaling pathway, reducing oxidative stress, and restoring autophagic function.

Objective

The objective of this study is to examine how mTOR-mediated regulation of nutrient sensing and oxidative stress impacts autophagy in DKD, and to explore how TCM modulates these pathways to improve the condition.

Methods

A systematic review was conducted using PubMed, Web of Science, Wanfang Data, and China National Knowledge Infrastructure (CNKI), with the search extended to December 2024. The search subject terms included 'diabetic kidney disease,' 'Traditional Chinese Medicine,' 'mTOR,' 'nutrient sensing,' and 'oxidative stress.' Studies were rigorously screened by two investigators.

Results

This review systematically examines the pathogenesis of mTOR-mediated nutrient sensing dysfunction and oxidative stress in DKD, highlighting their impact on autophagy. It further clarifies how these mechanisms are targeted by Chinese medicine in the treatment of DKD. The review summarizes the potential mechanisms by which TCM, including monomers (e.g., Astragaloside IV), individual botanical drugs (e.g., Dendrobium nobile Lindl.), and compound formulations (e.g., Tongluo Digui Decoction), regulate autophagy in DKD through pathways such as AMP-activated protein kinase (AMPK), mTOR, sirtuins (Sirt), and the phosphatidylinositol three kinase (PI3K)/Akt/mTOR signaling pathway. TCM compound formulas share a common foundational framework, with the majority being formulated based on therapeutic principles such as 'Yiqi', 'Yangyin', 'Tongluo', and 'Huashi'.

Conclusion

TCM shows promise in treating DKD, with unique advantages in modulating key signaling pathways. However, the underlying mechanisms remain complex and warrant further investigation.

To establish and validate autophagy related biomarkers for the diagnosis of IgA nephropathy

IgA nephropathy (IgAN) is one of the most common immune-related primary glomerular diseases. The pathological mechanism of this disease is complex, and the specific pathogenesis is still unclear. To obtain a comprehensive understanding of its molecular mechanism and to provide new perspectives regarding the detection and treatment of the disease, this study investigated the role of immune cells in IgAN, as well as the role of autophagy-related biomarkers in IgAN development. The original datasets GSE93798, GSE35487, GSE58539, GSE116626 and GSE115857 were downloaded from Gene Expression Omnibus (GEO) and were further integrated and analyzed. The differentially expressed genes (DEGs) between IgAN and healthy control (HC) group were identified by the "limma" R package. The gene ontology (GO) function, Kyoto Encyclopedia of Genes and Genome (KEGG) pathway, GeneSet Enrichment Analysis (GSEA) and DisGeNet enrichment were adopted to analyze the genes from the intersection of DEGs. The hub genes were screened by the square least absolute shrinkage and selection operator (LASSO) and cross validation. Immune cell infiltration was analyzed using CIBERSORT. The correlation between hub genes and infiltrating immune cells was calculated by R software. For the purpose of exploring the value of hub genes for diagnosing IgAN, a receiver operating characteristic (ROC) curve was constructed. Finally, Real-time quantitative polymerase chain reaction (qRT-PCR) was used to verify the relative mRNA level of the AT-DEGs. 12 DEGs were screened out. Enrichment analysis revealed that autophagy-related DEGs (AT-DEGs) were mainly related to intrinsic apoptotic signaling pathway, cellular response to external stimulus, transcription repressor complex and other cellular functions, KEGG pathways enriched by AT-DEGs mainly included biological metabolic pathways related to autophagy, while DisGeNET analysis showed that these AT-DEGs were mainly related to immunological diseases. The optimal six hub genes were obtained by lasso analysis as potential biomarkers for IgAN. ROC curve analysis showed that 4 of the 6 HUB genes had great diagnostic value. Immune infiltration results showed B cells memory, macrophages M2, NK cells activated, T cells CD4+ memory resting, and monocytes are the predominant immune cells with the development of IgAN. The qRT-PCR results showed that, compared to the NC group, SIRT1 mRNA expression in PBMCs from IgAN patients was significantly reduced, while BAG3, CDKN1A, and FOS mRNA levels were markedly elevated. SIRT1, BAG3, COKN1A and FOS can be considered as effective biomarkers related to autophagy for the diagnosis of IgAN. These findings suggest some potential new serum biomarkers for IgAN diagnosis.

Histone deacetylases and their inhibitors in kidney diseases

Histone deacetylases (HDACs) have emerged as key regulators in the pathogenesis of various kidney diseases. This review explores recent advancements in HDAC research, focusing on their role in kidney development and their critical involvement in the progression of chronic kidney disease (CKD), acute kidney injury (AKI), autosomal dominant polycystic kidney disease (ADPKD), and diabetic kidney disease (DKD). It also discusses the therapeutic potential of HDAC inhibitors in treating these conditions. Various HDAC inhibitors have shown promise by targeting specific HDAC isoforms and modulating a range of biological pathways. Their protective effects include modulation of apoptosis, autophagy, inflammation, and fibrosis, underscoring their broad therapeutic potential for kidney diseases. However, further research is essential to improve the selectivity of HDAC inhibitors, minimize toxicity, overcome drug resistance, and enhance their pharmacokinetic properties. This review offers insights to guide future research and prevention strategies for kidney disease management.

Targeting kinases that regulate programmed cell death: a new therapeutic strategy for breast cancer

Breast cancer is one of the most prevalent malignant tumors among women and ranks as the second leading cause of cancer-related deaths in females, primarily due to delays in diagnosis and shortcomings in treatment strategies. Consequently, there is a pressing need to identify reliable therapeutic targets and strategies. In recent years, the identification of effective biomarkers-particularly novel molecular therapeutic targets-has become a focal point in breast cancer research, aimed at predicting disease aggressiveness and monitoring treatment responses. Simultaneously, advancements in understanding the molecular mechanisms underlying cellular programmed death have opened new avenues for targeting kinase-regulated programmed cell death as a viable therapeutic strategy. This review summarizes the latest research progress regarding kinase-regulated programmed death (including apoptosis, pyroptosis, autophagy, necroptosis, and ferroptosis) in breast cancer treatment. It covers the key kinases involved in this mechanism, their roles in the onset and progression of breast cancer, and strategies for modulating these kinases through pharmacological interventions.

Autophagy: a double-edged sword in ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury describes the pathological process wherein tissue damage, initially caused by insufficient blood supply (ischemia), is exacerbated upon the restoration of blood flow (reperfusion). This phenomenon can lead to irreversible tissue damage and is commonly observed in contexts such as cardiac surgery and stroke, where blood supply is temporarily obstructed. During ischemic conditions, the anaerobic metabolism of tissues and organs results in compromised enzyme activity. Subsequent reperfusion exacerbates mitochondrial dysfunction, leading to increased oxidative stress and the accumulation of reactive oxygen species (ROS). This cascade ultimately triggers cell death through mechanisms such as autophagy and mitophagy. Autophagy constitutes a crucial catabolic mechanism within eukaryotic cells, facilitating the degradation and recycling of damaged, aged, or superfluous organelles and proteins via the lysosomal pathway. This process is essential for maintaining cellular homeostasis and adapting to diverse stress conditions. As a cellular self-degradation and clearance mechanism, autophagy exhibits a dualistic function: it can confer protection during the initial phases of cellular injury, yet potentially exacerbate damage in the later stages. This paper aims to elucidate the fundamental mechanisms of autophagy in I/R injury, highlighting its dual role in regulation and its effects on both organ-specific and systemic responses. By comprehending the dual mechanisms of autophagy and their implications for organ function, this study seeks to explore the potential for therapeutic interventions through the modulation of autophagy within clinical settings.

Attenuation of cisplatin-induced acute kidney injury by sanguinarine: modulation of oxidative stress, inflammation, and cellular damage

Introduction

Cisplatin (CP)-induced acute kidney injury (AKI) is a significant side effect of CP chemotherapy, driven by oxidative stress and inflammation. Sanguinarine (SANG), an alkaloid from the rhizomes of Sanguinaria canadensis and poppy-fumaria species, exhibits antioxidant and anti-inflammatory properties. This study examined SANG's effect on CP-induced AKI in mice and its underlying mechanisms.

Methods

Mice were orally administered 5 mg/kg SANG for 10 days. On the seventh day, they received a single intraperitoneal CP injection (20 mg/kg) and were sacrificed on the 11th day.

Results

SANG significantly improved CP-induced decreases in body weight, water intake, urine volume, relative kidney weight, creatinine clearance, albumin-to-creatinine ratio, and plasma urea and creatinine levels. It also reduced elevated plasma neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, cystatin C, and adiponectin levels, as well as renal markers of inflammation and oxidative stress induced by CP administration. SANG normalized kidney mitochondrial dysfunction, DNA damage, and apoptosis caused by CP. It also inhibited the CP-induced increase in the expression of phosphorylated nuclear factor-κB and autophagy markers in the kidney. Histological analysis showed that SANG reduced acute tubular necrosis and intraluminal protein accumulation due to CP.

Discussion

In conclusion, SANG mitigated CP-induced AKI by reducing inflammation, oxidative stress, DNA damage, apoptosis, and autophagy. Pending more comprehensive pharmacological and toxicological assessments, SANG may be regarded as a potential therapeutic agent for mitigating CP-induced AKI.

Sulforaphane alleviates renal fibrosis through dual regulation on mTOR-mediated autophagy pathway

Renal fibrosis is a common pathological process of progressive chronic kidney disease (CKD). However, effective therapy is constrained currently. Autophagy is an important mechanism in kidney injury and repairment but its exact role in renal fibrosis was discrepant according to previous studies. Sulforaphane (SFN), a natural plant compound, has been explored as a promising nutritional therapy for a variety of diseases. But the salutary effect and underlying mechanism of SFN on CKD have not been fully elucidated. In this study, we investigated the effect of SFN on renal fibrosis in unilateral ureteral obstruction (UUO) mice. Then we examined the regulatory effect of SFN on autophagy-related proteins in renal fibroblasts and renal tubular epithelial cells. Our results showed that sulforaphane could significantly alleviate renal fibrosis in UUO mice. In vitro, the expression levels of autophagy-related protein showed that SFN could upregulate the autophagy activity of renal interstitial fibroblasts and downregulate the autophagy activity of renal tubular epithelial cells. Furthermore, we found that phosphorylated mTOR protein levels was reduced in renal fibroblasts and increased in renal tubular epithelial cells after SFN treatment. Our results strongly suggested that SFN could alleviate renal fibrosis through dual regulation of mTOR-mediated autophagy pathway. This finding may provide a new perspective on the renal salutary effect of SFN and provide a preclinical rationale for exploring the therapeutic potential of SFN to slow down renal fibrosis.

AMPK protects proximal tubular epithelial cells from lysosomal dysfunction and dedifferentiation induced by lipotoxicity

Renal proximal tubules are a primary site of injury in metabolic diseases. In obese patients and animal models, proximal tubular epithelial cells (PTECs) display dysregulated lipid metabolism, organelle dysfunctions, and oxidative stress that contribute to interstitial inflammation, fibrosis and ultimately end-stage renal failure. Our research group previously pointed out AMP-activated protein kinase (AMPK) decline as a driver of obesity-induced renal disease. Because PTECs display high macroautophagic/autophagic activity and rely heavily on their endo-lysosomal system, we investigated the effect of lipid stress on autophagic flux and lysosomes in these cells. Using a model of highly differentiated primary PTECs challenged with palmitate, our data placed lysosomes at the cornerstone of the lipotoxic phenotype. As soon as 6 h after palmitate exposure, cells displayed impaired lysosomal acidification subsequently leading to autophagosome accumulation and activation of lysosomal biogenesis. We also showed the inability of lysosomal quality control to restore acidic pH which finally drove PTECs dedifferentiation. When palmitate-induced AMPK activity decline was prevented by AMPK activators, lysosomal acidification and the differentiation profile of PTECs were preserved. Our work provided key insights on the importance of lysosomes in PTECs homeostasis and lipotoxicity and demonstrated the potential of AMPK in protecting the organelle from lipid stress.Abbreviation: ACAC: acetyl-CoA carboxylase; ACTB: actin beta; AICAR: 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside; AMPK: AMP-activated protein kinase; APQ1: aquaporin 1 (Colton blood group); BSA: bovine serum albumin; CDH16: cadherin 16; CKD: chronic kidney disease; CTSB: cathepsin B; CTSD: cathepsin D; EPB41L5: erythrocyte membrane protein band 4.1 like 5; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; EMT: epithelial-to-mesenchymal transition; FA: fatty acid; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; GFP: green fluorescent protein; GUSB: glucuronidase beta; HEXB: hexosaminidase subunit beta; LAMP: lysosomal associated membrane protein; LD: lipid droplet; LGALS3: galectin 3; LLOMe: L-leucyl-L-leucine methyl ester hydrobromide; LMP: lysosomal membrane permeabilization; LRP2: LDL receptor related protein 2; LSD: lysosomal storage disorder; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MCOLN1: mucolipin TRP cation channel 1; MG132: N-benzyloxycarbonyl-L-leucyl-L-leucyl-L-leucinal; MmPTECs: Mus musculus (mouse) proximal tubular epithelial cells; MTORC1: mechanistic target of rapamycin kinase complex 1; OA: oleate; PA: palmitate; PIKFYVE: phosphoinositide kinase, FYVE-type zinc finger containing; PTs: proximal tubules; PTECs: proximal tubular epithelial cells; PRKAA: protein kinase AMP-activated catalytic subunit alpha; RFP: red fluorescent protein; RPS6KB: ribosomal protein S6 kinase B; SLC5A2: solute carrier family 5 member 2; SOX9: SRY-box transcription factor 9; SQSTM1: sequestosome 1; TFEB: transcription factor EB; Ub: ubiquitin; ULK1: unc-51 like autophagy activating kinase 1; VIM: vimentin.

Sex-specific and cell-type-specific changes in chaperone-mediated autophagy across tissues during aging

Aging leads to progressive decline in organ and tissue integrity and function, partly due to loss of proteostasis and autophagy malfunctioning. A decrease with age in chaperone-mediated autophagy (CMA), a selective type of lysosomal degradation, has been reported in various organs and cells from rodents and humans. Disruption of CMA recapitulates features of aging, whereas activating CMA in mice protects against age-related diseases such as Alzheimer's, retinal degeneration and/or atherosclerosis. However, sex-specific and cell-type-specific differences in CMA with aging remain unexplored. Here, using CMA reporter mice and single-cell transcriptomic data, we report that most organs and cell types show CMA decline with age, with males exhibiting a greater decline with aging. Reduced CMA is often associated with fewer lysosomes competent for CMA. Transcriptional downregulation of CMA genes may further contribute to CMA decline, especially in males. These findings suggest that CMA differences may influence organ vulnerability to age-related degeneration.

SET8 inhibition preserves PTEN to attenuate kidney cell apoptosis in cisplatin nephrotoxicity

The aberrant expression of SET8, a histone methyltransferase that mediates H4 lysine 20 mono-methylation (H4K20me1), is implicated in the pathogenesis of various tumors, however, its role in acute kidney injury (AKI) is unknown. Here, we showed that SET8 and H4K20me1 were upregulated in the murine kidney with AKI induced by cisplatin, along with increased renal tubular cell injury and apoptosis and decreased expression of E-cadherin and Phosphatase and Tensin Homolog (PTEN). Suppression of SET8 by UNC0379 improved renal function, attenuated tubule damage, and restored expression of PTEN but not E-cadherin. UNC0379 was also effective in lessening cisplatin-induced DNA damage response (DDR) as indicated by reduced expression of γ-H2AX, p53, p21, and alleviating cisplatin-impaired autophagy as shown by retained expression of Atg5, Beclin-1, and CHMP2A and enhanced levels of LC3-II in the kidney. Consistently, inhibition of SET8 with either UNC0379 or siRNA mitigated apoptosis and DDR and restored autophagy, along with PTEN preservation in cultured renal proximal tubular epithelial cells (TKPTs) exposed to cisplatin. Further studies showed that inhibition of PTEN with Bpv or siRNA potentiated cisplatin-induced apoptosis and DDR, hindered autophagy, and conversely, alleviated by overexpression of PTEN in TKPTs. Finally, blocking PTEN largely abolished the inhibitory effect of UNC0379 on apoptosis. Taken together, these results suggest that SET8 inhibition protects against cisplatin-induced AKI and renal cell apoptosis through a mechanism associated with the preservation of PTEN, which in turn inhibits DDR and restores autophagy.

Interplay Between Polyphenols and Autophagy: Insights From an Aging Perspective

The relationship between polyphenols and autophagy, particularly in the context of aging, presents a promising avenue for therapeutic interventions in age-related diseases. A decline in autophagy is associated with aging-related affections, and an increasing number of studies suggest that this enhancement is linked to cellular resilience and longevity. This review delves into the multifaceted roles of autophagy in cellular homeostasis and the potential of polyphenols to modulate autophagic pathways. We revised the most updated literature regarding the modulatory effects of polyphenols on autophagy in cardiovascular, liver, and kidney diseases, highlighting their therapeutic potential. We highlight the role of polyphenols as modulators of autophagy to combat age-related diseases, thus contributing to improving the quality of life in aging populations. A better understanding of the interplay of autophagy between autophagy and polyphenols will help pave the way for future research and clinical applications in the field of longevity medicine.

Extracellular vesicles derived from mesenchymal stem cells alleviate renal fibrosis via the miR-99b-5p/mTOR/autophagy axis in diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD) globally, presenting a significant therapeutic challenge. Extracellular vesicles (EVs) from mesenchymal stem cells (MSCs) have emerged as promising therapeutic agents. This study explored the therapeutic effects and mechanisms of EVs derived from human placental mesenchymal stem cells (hP-MSCs) on DKD.

METHODS

EVs were isolated from cultured hP-MSCs and administered to streptozotocin (STZ)-induced diabetic mice and high glucose-treated glomerular mesangial cells. The therapeutic impact of EVs was assessed through histological analysis and biochemical assays. miR-99b-5p expression in EVs and its role in modulating the mechanistic target of rapamycin (mTOR)/autophagy pathway were examined via western blotting and RT‒qPCR.

RESULTS

Treatment with hP-MSC-derived EVs significantly alleviated renal fibrosis and improved renal function in DKD models. These EVs were enriched with miR-99b-5p, which targeted and inhibited mTOR signaling, thereby increasing autophagic activity and reducing cellular proliferation and extracellular matrix accumulation in renal tissues.

CONCLUSIONS

hP-MSC-derived EVs can mitigate renal injury in DKD by modulating the miR-99b-5p/mTOR/autophagy pathway. These findings suggest a potential cell-free therapeutic strategy for managing DKD.

mTOR-Mediated Autophagy Regulates Cadmium-Induced Kidney Injury via Pyroptosis

The heavy metal cadmium (Cd) affects the global livestock production economy mainly through the contamination of feed raw materials and secondary contamination in feed processing, and it also poses a serious threat to food safety and human health. The nucleotide-binding oligomerization domain-like pyrin-domain-containing protein 3 (NLRP3) inflammasome is a key regulatory element of pyroptosis, which is engaged in kidney injury. Meanwhile, autophagy is also involved in renal inflammation. Mammalian target of rapamycin (mTOR) plays an important role in pyroptosis and autophagy, but its function in Cd-induced kidney injury remains unclear. In this study, we explored the role of mTOR-mediated autophagy and pyroptosis in kidney injury caused by Cd exposure and elucidated its underlying mechanism. Our data showed that Cd exposure reduced the integrity of kidney cell membranes, increased the expression of pyroptosis-associated proteins, and promoted the release of inflammatory cytokines. Subsequently, a notable attenuation in Cd-induced pyroptosis was observed following the administration of CY-09, an NLRP3 inhibitor. In addition, Cd exposure promoted autophagy in kidney cells. Importantly, in both in vivo and in vitro experiments, rapamycin, an mTOR inhibitor, downregulated the expression of pyroptosis-related proteins, thereby significantly improving Cd-induced kidney injury. In summary, our results indicate that mTOR-mediated autophagy has a significant protective effect on NLRP3 inflammasome-dependent kidney injury induced by Cd exposure, thus providing new insights into the prevention and treatment of Cd poisoning.

Morroniside Ameliorates High-Fat and High-Fructose-Driven Chronic Kidney Disease by Motivating AMPK-TFEB Signal Activation to Accelerate Lipophagy and Inhibiting Inflammatory Response

Studies have substantiated that dietary-fat- and fructose-overconsumption-caused lipid metabolism disorders can trigger renal lipotoxicity to drive the progression of chronic kidney disease (CKD). This study was conducted to evaluate the efficacy of morroniside, a natural active substance extracted from the fruit of Cornus officinalis, in inhibiting the progression of CKD in high-fat and high-fructose-fed mice. Our results showed histological changes such as fatty degeneration of renal tubular cells, tubular dilatation, glomerular fibrosis, and abnormal renal function in the kidneys of high-fat- and high-fructose-fed mice, which was significantly improved after morroniside treatment. Mechanistically, morroniside maintained renal lipid metabolism homeostasis and inhibited NLRP3 inflammatory vesicle activation by activating AMPKα to promote TFEB nuclear translocation-mediated lipophagy. Consistent results were observed in palmitic acid-induced HK-2 cells. Notably, silencing AMPKα or TFEB both reversed the effects of morroniside in promoting lipophagy and inhibiting the activation of inflammatory responses in vivo and in vitro. Therefore, our study provides compelling evidence that morroniside delays CKD progression by promoting AMPK/TFEB-mediated lipophagy and inhibiting NLRP3 inflammasome activation, suggesting that dietary supplementation with morroniside and morroniside-rich foods (such as Cornus officinalis) might be an effective strategy for the prevention of CKD.

Dietary Polyunsaturated Fatty Acid Deficiency Impairs Renal Lipid Metabolism and Adaptive Response to Proteinuria in Murine Renal Tubules

Background/Objectives: Kidneys are fatty acid (FA)-consuming organs that use adenosine triphosphate (ATP) for tubular functions, including endocytosis for protein reabsorption to prevent urinary protein loss. Peroxisome proliferator-activated receptor α (PPARα) is a master regulator of FA metabolism and energy production, with high renal expression. Although polyunsaturated fatty acids (PUFAs) are essential nutrients that are natural PPARα ligands, their role in tubular protein reabsorption remains unclear. As clinical PUFA deficiency occurs in humans under various conditions, we used a mouse model that mimics these conditions. Methods: We administered a 2-week intraperitoneal protein-overload (PO) treatment to mice that had been continuously fed a PUFA-deficient diet. We compared the phenotypic changes with those in mice fed a standard diet and those in mice fed a PUFA-deficient diet with PUFA supplementation. Results: In the absence of PO, the PUFA-deficient diet induced increased lysosomal autophagy activation; however, other phenotypic differences were not detected among the diet groups. In the PO experimental condition, the PUFA-deficient diet increased daily urinary protein excretion and tubular lysosomes; suppressed adaptive endocytosis activation, which was probably enhanced by continuous autophagy activation; and worsened FA metabolism and PPARα-mediated responses to PO, which disrupted renal energy homeostasis. However, these changes were attenuated by PUFA supplementation at the physiological intake level. Conclusions: PUFAs are essential nutrients for the tubular adaptive reabsorption response against urinary protein loss. Therefore, active PUFA intake may be important for patients with kidney disease-associated proteinuria, especially those with various PUFA deficiency-inducing conditions.

Exercise combined with metformin ameliorates diabetic kidney disease by increasing renal autophagy and reducing oxidative stress in rats with high-fat diet and streptozotocin induced diabetes

Diabetic kidney disease (DKD) is one of the common and serious complications of type 2 diabetes mellitus (T2DM). Metformin is commonly prescribed for the treatment of T2DM, while exercise is frequently recommended as adjunctive therapy. However, the therapeutic efficacy and molecular etiology of combined therapy with exercise and metformin in DKD remain to be elucidated. The present study therefore aimed to investigate the therapeutic effects and mechanisms underlying the combined effects of exercise and metformin on DKD. A rat model of T2DM was constructed by administering a high-fat diet and intraperitoneal injections of streptozotocin (30 mg/kg) for 6 weeks. The rats with T2DM exhibited reduced autophagic flux, increased oxidative stress, and morphological and structural lesions in the kidneys, compared to those of normal rats in the control group. The combination of exercise and metformin alleviated DKD, indicated by the elevation of renal autophagic flux, and a reduction in oxidative stress, renal fibrosis, and histopathological damage to the kidneys. Our findings suggested that exercise combined with metformin has a therapeutic role in DKD, and the study serves as a valuable reference for future research on the treatment of DKD.

Omega-3 PUFAs improve cognitive function in heat-stressed mice by enhancing autophagy via inhibition of the phosphorylation of the PI3K-Akt-mTOR pathway

The adverse effects of elevated temperatures on human health are becoming progressively severe. This research established a mouse model of cognitive dysfunction induced by heat stress to examine the impact of omega-3 PUFAs on the cognitive capabilities of heat-stressed mice. The study also aimed to elucidate the role and potential mechanisms of autophagy regulation in cognitive enhancement through omega-3 PUFAs interventions. Administration of omega-3 PUFAs ameliorated cognitive deficits in heat-stressed mice and increased brain concentrations of these fatty acids. Notably, omega-3 PUFAs significantly protected hippocampal neurons' morphology, quantity, and synaptic architecture in heat-stressed mice. Additionally, omega-3 PUFAs intake reduced the prevalence of damaged mitochondria in the hippocampus and mitigated oxidative harm. Further investigation revealed that heat stress induces autophagy. However, the autophagic process becomes dysfunctional, leading to impaired autophagic activity. Omega-3 PUFAs supplementation markedly augmented hippocampal autophagy in the heat-stressed mice. Moreover, heat stress upregulated the phosphorylation of the PI3K-Akt-mTOR pathway in both the mouse hippocampus and HT22 cells. In contrast, omega-3 PUFAs intake significantly diminished the phosphorylation levels within this pathway, alleviating the autophagic fusion barrier imposed by heat stress and promoting autophagic flux. The findings suggest that omega-3 PUFAs supplementation during heat stress may bolster autophagic function by inhibiting the phosphorylation of the PI3K-Akt-mTOR pathway. This modulation reduces structural and oxidative stress damage, ultimately enhancing cognitive function in mice subjected to heat stress.

Caloric restriction exacerbates renal post-ischemic injury and fibrosis by modulating mTORC1 signaling and autophagy

OBJECTIVE

This study investigates the effects of caloric restriction (CR) on renal injury and fibrosis following ischemia-reperfusion injury (IRI), with a focus on the roles of the mechanistic/mammalian target of rapamycin complex 1 (mTORC1) signaling and autophagy.

METHODS

A mouse model of unilateral IRI with or without CR was used. Renal function was assessed through serum creatinine and blood urea nitrogen levels, while histological analysis and molecular assays evaluated tubular injury, fibrosis, mTORC1 signaling, and autophagy activation. Inducible renal tubule-specific Atg7 knockout mice and autophagy inhibitor 3-MA were used to elucidate autophagy's role in renal outcomes.

RESULTS

CR exacerbated renal dysfunction, tubular injury, and fibrosis in IRI mice, associated with suppressed mTORC1 signaling and enhanced autophagy. Rapamycin, an mTORC1 inhibitor, mimicked the effects of CR, further supporting the involvement of mTORC1-autophagy pathway. Tubule-specific Atg7 knockout and autophagy inhibitor 3-MA mitigated these effects, indicating a central role for autophagy in CR-induced renal damage. Glucose supplementation, but not branched-chain amino acids (BCAAs), alleviated CR-induced renal fibrosis and dysfunction by restoring mTORC1 activation. Finally, we identified leucyl-tRNA synthetase 1 (LARS1) as a key mediator of nutrient sensing and mTORC1 activation, demonstrating its glucose dependency under CR conditions.

CONCLUSION

Our study provides novel insights into the interplay between nutrient metabolism, mTORC1 signaling, and autophagy in IRI-induced renal damages, offering potential therapeutic targets for mitigating CR-associated complications after renal IRI.

Integrin-Linked Kinase (ILK) Promotes Mitochondrial Dysfunction by Decreasing CPT1A Expression in a Folic Acid-Based Model of Kidney Disease

Integrin-linked kinase (ILK) is a key scaffolding protein between extracellular matrix protein and the cytoskeleton and has been implicated previously in the pathogenesis of renal damage. However, its involvement in renal mitochondrial dysfunction remains to be elucidated. We studied the role of ILK and its downstream regulations in renal damage and mitochondria function both in vivo and vitro, using a folic acid (FA)-induced kidney disease model. Wild type (WT) and ILK conditional-knockdown (cKD-ILK) mice were injected with a single intraperitoneal dose of FA and studied after 15 days of chronic renal damage progression. Human Kidney tubular epithelial cells (HK2) were transfected with specific siRNAs targeting ILK, glycogen synthase kinase 3-β (GSK3β), or CCAAT/enhancer binding protein-β (C/EBPβ). The expressions and activities of renal ILK, GSK3β, C/EBPβ, mitochondrial oxidative phosphorylation enzymes, and mitochondrial membrane potential were assessed. Additionally, the expression of markers for fibrosis fibronectin (FN) and collagen 1 (COL1A1), for autophagy p62 and cytosolic light chain 3 (LC3B) isoforms II and I, and mitochondrial homeostasis marker carnitine palmitoyl-transferase 1A (CPT1A) were evaluated using immunoblotting, RT-qPCR, immunofluorescence, or colorimetric assays. FA upregulated ILK expression, leading to the decrease of GSK3β activity, increased tubular fibrosis, and produced mitochondrial dysfunction, both in vivo and vitro. These alterations were fully or partially reversed upon ILK depletion, mitigating FA-induced renal damage. The signaling axis composed by ILK, GSK3β, and C/EBPβ regulated CPT1A transcription as the limiting factor in the FA-based impaired mitochondrial activity. We highlight ILK as a potential therapeutical target for preserving mitochondrial function in kidney injury.

Assessing Creatine-Related Gene Expression in Kidney Disease: Can Available Data Give Insights into an Old Discussion?

The impact of creatine supplementation on individuals with kidney disease or pathological conditions with an increased risk of developing kidney dysfunction remains an active discussion. However, the literature on gene expression related to cellular creatine uptake and metabolism under altered renal function is scarce. Therefore, the present study utilized comprehensive bioinformatics analysis to evaluate the expression of creatine-related genes and to establish their relationships to normal and disturbed renal conditions. We identified 44 genes modulated explicitly in response to creatine exposure from a gene enrichment analysis, including IGF1, SLC2A4, and various creatine kinase genes. The analysis revealed associations with metabolic processes such as amino acid metabolism, indicating a connection between creatine and tissue physiology. Using the Genotype-Tissue Expression Portal, we evaluated their basal tissue-specific expression patterns in kidney and pancreas tissues. Then, we selected several pieces of Gene Expression Omnibus (GEO) transcriptomic data, estimated their expression values, and established relationships to the creatine metabolism pathways and regulation, shedding light on the potential regulatory roles of creatine in cellular processes during kidney diseases. These observations also highlight the connection between creatine and tissue physiology, emphasizing the importance of understanding the balance between endogenous creatine synthesis and creatine uptake, particularly the roles of genes such as GATM, GAMT, SLC6A8, and IGF1, under several kidney dysfunction conditions. Overall, the available data in the biological databases can provide new insights and directions into creatine's effects and role in renal function.

Non-lethal sonodynamic therapy mitigates hypertensive renal fibrosis through the PI3K/AKT/mTORC1-autophagy pathway

Hypertension constitutes a significant public health concern, characterized by a high incidence and mortality rate. Hypertensive kidney disease is a prevalent complication associated with hypertension and is the second leading cause of end-stage renal disease (ESRD). Renal fibrosis linked to hypertension has emerged as the third leading cause of disease in dialysis patients. Autophagy activity is crucial for maintaining homeostasis, vitality, and physiological function of kidney cells, while also protecting the kidneys from fibrosis. The deficiency of autophagy will increase the sensitivity of the kidney to the damage, leading to impaired renal function, accumulation of damaged mitochondria and more severe of renal fibrosis. However, enhancing autophagy by activating the PI3K/AKT, AMPK, and mTOR pathways, improves podocyte injury and renal pathological changes, and ameliorates renal function. Current clinical interventions aimed at halting or reversing renal fibrosis in hypertensive patients are notably limited in their efficacy. Here, we present Non-lethal Sonodynamic Therapy (NL-SDT), in which ultrasound is used to activate locally sonosensitizers, thereby stimulating the production of reactive oxygen species for the purpose of modulating cell function or fate, as a novel methodology to inhibit progression of hypertensive renal fibrosis.To confirm whether NL-SDT can reduce hypertensive renal fibrosis and its mechanism. The mice model of hypertensive renal fibrosis was established by using osmotic minipumps (Alzet model 2004, Cupertino, CA) equipped with angiotensin-II (Ang II). The pumps were implanted in mice, ensuring constant infusion of Ang II at a dose of 1.0 µg/kg per minute for 4 weeks. The mice were exposed to 0.4 W/cm2 intensity ultrasonic radiation for 15 min at 4 h post injection of sinoporphyrin sodium (DVDMS) (4 mg/kg) into the caudal vein was repeated weekly for 4 treatments. The kidney from mice was stained with masson's trichrome staining for collagen fiber expression, while alpha-smooth muscle actin (α-SMA) expression was determined via immunohistochemical staining. The protein levels of fibrosis parameters (α-SMA, collagen I, vimentin), pathway-related proteins (PI3K, AKT, mTORC1) and autophagy-related protein LC3B were determined using western blotting. Intracellular reactive oxygen species (ROS) levels were detected using DCFH-DA probe. Immunofluorescence was also used to observe the expression of α-SMA and E-cadherin in cells. Pathway-related protein inhibitors (the autophagy-related inhibitor 3-methyladenine (3-MA), chloroquine (CQ), ROS inhibitor N-acetyl-L-cysteine (NAC) were applied, and autophagosome changes were observed under transmission electron microscopy. Immunofluorescence was used to observe LC3 spot formation within cells.We obtained the following results via animal and cellular research. In vivo, (1) The collagen area of renal tissue was increased significantly in Ang II group (50.6%). The positive expression of α-SMA was increased significantly (37.8%). (2) The collagen area decreased after NL-SDT treatment (34.8%). The expression of α-SMA was decreased too (48.9%). The expression of LC3B increased in NL-SDT group. (3) The effect of NL-SDT on reducing renal fibrosis can be changed by rapamycin and CQ. In vitro. (1) The expression of α-SMA, collagen I and vimentin were increased significantly in TGF-β1-induced NRK-52E cells. (2) The increase of autophagosomes was observed in TGF-β1-induced NRK-52E cells after NL-SDT. The levels of ROS were increased after NL-SDT (24.8%). The effect of NL-SDT on autophagy was reversed after administration of NAC. The expression of PI3K, P-AKT and P-mTORC1 was decreased in TGF-β1-induced NRK-52E cells after NL-SDT. NL-SDT inhibited the transition of epithelial cells into myofibroblasts by activating PI3K-AKT-mTORC1-autophagy pathway in TGF-β1-induced NRK-52E cells. (3) The administration of the pathway inhibitors showed a reciprocal effect on NL-SDT-inhibited epithelial-mesenchymal transition (EMT).(1) NL-SDT reduced blood pressure temporarily in mice model of hypertensive renal fibrosis induced by Ang II. (2) NL-SDT alleviated renal fibrosis in mice model of hypertensive renal fibrosis induced by Ang II. (3) NL-SDT promoted autophagy by inhibiting PI3K-AKT-mTORC1 signaling pathway and alleviated renal fibrosis in mice model of hypertensive renal fibrosis induced by Ang II. NL-SDT is a non-invasive and efficacious regimen to inhibit renal fibrosis. It may be a new approach for clinical treatment of renal fibrosis, delaying or reducing the occurrence of ESRD.

Cellular senescence: from homeostasis to pathological implications and therapeutic strategies

Cellular aging is a multifactorial and intricately regulated physiological process with profound implications. The interaction between cellular senescence and cancer is complex and multifaceted, senescence can both promote and inhibit tumor progression through various mechanisms. M6A methylation modification regulates the aging process of cells and tissues by modulating senescence-related genes. In this review, we comprehensively discuss the characteristics of cellular senescence, the signaling pathways regulating senescence, the biomarkers of senescence, and the mechanisms of anti-senescence drugs. Notably, this review also delves into the complex interactions between senescence and cancer, emphasizing the dual role of the senescent microenvironment in tumor initiation, progression, and treatment. Finally, we thoroughly explore the function and mechanism of m6A methylation modification in cellular senescence, revealing its critical role in regulating gene expression and maintaining cellular homeostasis. In conclusion, this review provides a comprehensive perspective on the molecular mechanisms and biological significance of cellular senescence and offers new insights for the development of anti-senescence strategies.

Augmenter of liver regeneration inhibits renal fibrosis during acute kidney injury to chronic kidney disease transition by regulating autophagic flux

BACKGROUND

Augmenter of liver regeneration (ALR) is believed to protect against acute kidney injury (AKI). The objective of this study was to investigate the mechanisms of ALR in the transition from AKI to chronic kidney disease (CKD).

METHODS

ALR Conditional Knockout (CKO) mice were bilateral renal artery clamped to induce AKI and CKD. Serum creatinine, blood urea nitrogen, and uric acid were measured to reflect renal function. Renal histology was used to assess kidney damage. Transcriptome sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to identify differentially expressed genes (DEGs) and related pathways. TUNEL assay was conducted to assess apoptosis. Polymerase chain reaction and immunohistology were used to analyze autophagy-related factors and kidney fibrosis. AAV9-mRFP-GFP-LC3 was injected to observe autophagy flux.

RESULTS

In the murine models of AKI and CKD, loss of ALR led to markedly reduced renal function and renal tubular pathology injury. Multiple autophagy-related pathways were found to be enriched in up-regulated DEGs in transcriptome sequencing of ALR CKO and control groups with AKI. Renal fibrosis was evident in ALR CKO mice, with marked suppression of Beclin-1, a factor associated with the initiation phase of autophagy, and ATG5, an important factor in the extension phase of autophagosomes. The marked accumulation of LC3 and SQSTM1/P62, which is associated with the formation of autophagosomes, was also observed, suggesting an impairment of autophagic processes. Correspondingly, the AAV9-mRFP-GFP-LC3 results indicated that decreased ALR led to the accumulation of autophagosomes and impaired autophagic lysosome generation.

CONCLUSIONS

Collectively, these results suggested that ALR deficiency led to apoptosis and enhanced renal fibrosis by impairing autophagic flux, which in turn led to the transition of AKI to CKD.

ACOT12, a novel factor in the pathogenesis of kidney fibrosis, modulates ACBD5

Lipid metabolism, particularly fatty acid oxidation dysfunction, is a major driver of renal fibrosis. However, the detailed regulatory mechanisms underlying this process remain unclear. Here we demonstrated that acyl-CoA thioesterase 12 (Acot12), an enzyme involved in the hydrolysis of acyl-CoA thioesters into free fatty acids and CoA, is a key regulator of lipid metabolism in fibrotic kidneys. A significantly decreased level of ACOT12 was observed in kidney samples from human patients with chronic kidney disease as well as in samples from mice with kidney injuries. Acot12 deficiency induces lipid accumulation and fibrosis in mice subjected to unilateral ureteral obstruction (UUO). Fenofibrate administration does not reduce renal fibrosis in Acot12-/- mice with UUO. Moreover, the restoration of peroxisome proliferator-activated receptor α (PPARα) in Acot12-/-Pparα-/- kidneys with UUO exacerbated lipid accumulation and renal fibrosis, whereas the restoration of Acot12 in Acot12-/- Pparα-/- kidneys with UUO significantly reduced lipid accumulation and renal fibrosis, suggesting that, mechanistically, Acot12 deficiency exacerbates renal fibrosis independently of PPARα. In Acot12-/- kidneys with UUO, a reduction in the selective autophagic degradation of peroxisomes and pexophagy with a decreased level of ACBD5 was observed. In conclusion, our study demonstrates the functional role and mechanistic details of Acot12 in the progression of renal fibrosis, provides a preclinical rationale for regulating Acot12 expression and presents a novel means of preventing renal fibrosis.

Hyperosmotic Stress Promotes the Nuclear Translocation of TFEB in Tubular Epithelial Cells Depending on Intracellular Ca2+ Signals via TRPML Channels

Purpose

We previously demonstrated that hyperosmotic stress, which acts as mechanical stress, induces autophagy of tubular epithelial cells. This study aims to elucidate the molecular mechanisms of hyperosmolarity-induced autophagy. The research question addresses how hyperosmotic stress activates autophagy through transcription factor EB (TFEB) and Ca2+ signaling pathways, contributing to understanding cellular responses to mechanical stress.

Methods

NRK-52E normal rat kidney cells were subjected to hyperosmotic stress using mannitol-containing medium. Fluorescence microscopy was utilized to observe TFEB nuclear translocation, a crucial event in autophagy regulation. An intracellular Ca2+ chelator, BAPTA-AM, and a calcineurin inhibitor were used to dissect the Ca2+ signaling pathway involved in TFEB translocation. The phosphorylation of p70S6K, a substrate of the mammalian target of rapamycin complex 1 kinase, was analyzed to explore its role in TFEB localization. Additionally, the function of transient receptor potential mucolipin 1 (TRPML1), an intracellular Ca2+ channel, was assessed using pharmacological inhibition to determine its impact on TFEB translocation and autophagy marker LC3-II levels.

Results

Mannitol-induced hyperosmotic stress promoted the nuclear translocation of TFEB, which was completely abolished by treatment with BAPTA-AM. Inhibition of calcineurin suppressed TFEB nuclear translocation under hyperosmolarity, indicating that a signaling pathway governed by intracellular Ca2+ is involved in TFEB's nuclear translocation. In contrast, hyperosmotic stress did not significantly alter p70S6K phosphorylation. Pharmacological inhibition of TRPML1 attenuated both TFEB nuclear translocation and LC3-II upregulation in response to hyperosmotic stress.

Conclusions

Hyperosmotic stress promotes TFEB nuclear localization, and TRPML1-induced activation of calcineurin is involved in the mechanism of hyperosmolarity-induced autophagy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-024-00839-6.

INHIBITING SIRT2 ATTENUATES SEPSIS-INDUCED ACUTE KIDNEY INJURY VIA FOXO1 ACETYLATION-MEDIATED AUTOPHAGY ACTIVATION

ABSTRACT

Sepsis-associated acute kidney injury (SAKI), a common complication in intensive care units (ICUs), is linked to high morbidity and mortality. Sirtuin 2 (SIRT2), an NAD + -dependent deacetylase, has been shown to have distinct effects on autophagy regulation compared to other sirtuins, but its role in SAKI remains unclear. This study explored the potential of SIRT2 as a therapeutic target for SAKI. We found that inhibition of SIRT2 with the antagonist AGK2 improved the survival of septic mice. SIRT2 inhibition reduced kidney injury, as indicated by lower levels of KIM-1, NGAL, serum creatinine, blood urea nitrogen, and proinflammatory cytokines following cecal ligation and puncture. Pretreatment with AGK2 in septic mice increased autophagosome and autolysosome formation in renal tubular epithelial cells and upregulated LC3 II expression in the renal cortex. Consistent with in vivo findings, SIRT2 gene silencing promoted autophagy in LPS-treated HK-2 cells, whereas SIRT2 overexpression inhibited it. Mechanistically, SIRT2 inhibition increased FOXO1 acetylation, inducing its nuclear-to-cytoplasmic translocation, which promoted kidney autophagy and alleviated SAKI. Our study suggests SIRT2 as a potential target for SAKI therapy.

Sirtuins in kidney homeostasis and disease: where are we now?

Sirtuins, identified as (NAD+)- dependent class III histone deacetylases, engage in a spectrum of biological functions, encompassing DNA damage repair, oxidative stress, immune modulation, mitochondrial homeostasis, apoptosis and autophagy. Sirtuins play an apoptosis role in regulating cellular operations and overall organism health. Mounting data indicate that dysregulated sirtuin expression is linked to the onset of renal diseases. Effective modulation of sirtuins expression and activity has been shown to improve renal function and attenuate the advancement of kidney diseases. In this review, we present a comprehensive overview of the biological impacts of sirtuins and their molecular targets in regulating renal diseases. Additionally, we detail advancements in elucidating sirtuin roles in the pathophysiology of both chronic and acute renal disorders. We review compounds that modulate sirtuin activity through activation or inhibition, potentially improving outcomes in renal disease. In summary, strategic manipulation of sirtuin activity represents a prospective therapeutic approach for renal diseases.

Trehalose activates autophagy to alleviate cisplatin-induced chronic kidney injury by targeting the mTOR-dependent TFEB signaling pathway

Rationale: Cisplatin is a potent chemotherapeutic agent limited by significant nephrotoxicity. Multiple cycles of cisplatin administration are necessary to confer chronic disease. Autophagy is a lysosomal degradation pathway that enables the clearance and reuse of cytoplasmic components and is essential for maintaining the integrity and normal physiological function of tissues and organs. However, the precise role of autophagy in renal fibrosis has been controversial. Trehalose, a well-known autophagy inducer, plays a cytoprotective role under various stress conditions, such as oxidative damage, dehydration, and temperature changes. In this study, we established a model of cisplatin-induced chronic kidney disease (CKD) and human renal tubular epithelial cells (HK2) injury to investigate the nephroprotective effects of trehalose on cisplatin-induced CKD and the underlying mechanisms involved. Methods: Firstly, we measured the role of autophagy in cisplatin-induced injury models both in vivo and in vitro by western blot and immunofluorescence staining, combined with transcriptomics. Then, biomedical, cellular, and molecular approaches were utilized to evaluate the potential protective effect of trehalose intervention in regulating autophagy. Mechanistically, we performed this study using proximal tubular epithelial cells-specific transcription factor EB (TFEB) knockout mice and TFEB small-interfering RNA technology to determine whether TFEB deficiency affects the pharmacological effected of trehalose in cisplatin-induced injury models. Results: Due to the activation of autophagy, trehalose inhibited mitochondrial dysfunction (mitochondrial fragmentation, depolarization, reactive oxygen species) and cellular senescence induced by cisplatin both in vitro and in vivo. Moreover, renal dysfunction, pathological changes and fibrosis were alleviated in CKD mice after trehalose treatment. Mechanistic investigations revealed that trehalose accumulated in lysosomes and inhibited mTORC1 activity, which triggered TFEB and TFEB-mediated autophagy. In addition, siRNA-mediated knockdown of TFEB in HK2 cells or renal proximal tubular epithelial cells-specific (TECs-specific) TFEB deficiency in mice markedly abolished the beneficial effects of trehalose. Conclusion: Our findings suggested that trehalose induced autophagy to alleviate cisplatin-induced chronic kidney injury by targeting the mTOR-dependent TFEB signaling pathway.

Autophagy and Mitophagy in Diabetic Kidney Disease-A Literature Review

Autophagy and mitophagy are critical cellular processes that maintain homeostasis by removing damaged organelles and promoting cellular survival under stress conditions. In the context of diabetic kidney disease, these mechanisms play essential roles in mitigating cellular damage. This review provides an in-depth analysis of the recent literature on the relationship between autophagy, mitophagy, and diabetic kidney disease, highlighting the current state of knowledge, existing research gaps, and potential areas for future investigations. Diabetic nephropathy (DN) is traditionally defined as a specific form of kidney disease caused by long-standing diabetes, characterized by the classic histological lesions in the kidney, including mesangial expansion, glomerular basement membrane thickening, nodular glomerulosclerosis (Kimmelstiel-Wilson nodules), and podocyte injury. Clinical markers for DN are albuminuria and the gradual decline in glomerular filtration rate (GFR). Diabetic kidney disease (DKD) is a broader and more inclusive term, for all forms of chronic kidney disease (CKD) in individuals with diabetes, regardless of the underlying pathology. This includes patients who may have diabetes-associated kidney damage without the typical histological findings of diabetic nephropathy. It also accounts for patients with other coexisting kidney diseases (e.g., hypertensive nephrosclerosis, ischemic nephropathy, tubulointerstitial nephropathies), even in the absence of albuminuria, such as a reduction in GFR.

Inhibition of OLR1 Reduces SASP of Nucleus Pulposus Cells by Targeting Autophagy-GATA4 Axis

Targeting cellular senescence and senescence associated secretory phenotype (SASP) through autophagy has emerged as a promising intervertebral disc (IVD) degeneration (IDD) treatment strategy in recent years. This study aimed to clarify the role and mechanism of autophagy in preventing IVD SASP. Methods involved in vitro experiments with nucleus pulposus (NP) tissues from normal and IDD patients, as well as an in vivo IDD animal model. GATA4's regulatory role in SASP was validated both in vitro and in vivo, while autophagy modulators were employed to assess their impact on GATA4 and SASP. Transcriptomic sequencing identified oxidized low-density lipoprotein receptor 1 (OLR1) as a key regulator of autophagy and GATA4. A series of experiments manipulated OLR1 expression to investigate associated effects. Results demonstrated significantly increased senescent NP cells (NPCs) and compromised autophagy in IDD patients and animal models, with SASP closely linked to IDD progression. The aged disc milieu impeded autophagic GATA4 degradation, leading to elevated SASP expression in senescent NPCs. Restoring autophagy reversed senescence by degrading GATA4, hence disrupting the SASP cascade. Moreover, OLR1 was identified for its regulation of autophagy and GATA4 in senescent NPCs. Silencing OLR1 enhanced autophagic activity, suppressing GATA4-induced senescence, and SASP expression in senescent NPCs. In conclusion, OLR1 was found to control autophagy-GATA4 and SASP, with targeted OLR1 inhibition holding promise in alleviating GATA4-induced senescence and SASP expression while delaying extracellular matrix degradation, offering a novel therapeutic approach for IDD management.

Downregulation of CD36 alleviates IgA nephropathy by promoting autophagy and inhibiting extracellular matrix accumulation in mesangial cells

BACKGROUND

Immunoglobulin A Nephropathy (IgAN) is a leading cause of end-stage renal disease (ESRD), but its pathogenesis remains unclear, and specific therapies are currently lacking. Consequently, identifying novel differentially expressed genes (DEGs) and therapeutic targets is of paramount importance to IgAN.

METHODS

The Gene Expression Omnibus (GEO) databases GSE37460 and GSE104948, containing data from renal tissue of patients with IgAN and normal controls, were screened for DEGs, followed by enrichment pathway analysis. The potential key gene for IgAN, CD36, was identified through the single-cell sequencing dataset GSE166793 and histopathological analysis of patients with IgAN. Clinical and pathological data from patients with IgAN were collected to analyze the correlation between CD36 expression and various indicators in renal tissue, thereby evaluating the influence of CD36 on IgAN progression. The accuracy of the risk score model was assessed using receiver operating characteristic (ROC) curve analysis. Finally, CD36 expression was knocked down to explore its regulatory role in polymeric IgA1 (pIgA1)-stimulated mouse mesangial cells (MCs).

RESULTS

CD36 was identified as a key DEG from two GEO databases and a single-cell sequencing dataset. Compared to peritumoral normal tissues, CD36 expression levels were significantly increased in the IgAN group. Statistically significant differences were observed between M0 and M1, E0 and E1, S0 and S1, C0 and C1-2 in the updated Oxford Classification. CD36 expression showed positive correlations with 24-hour proteinuria, serum creatinine, and levels of fibrosis-related and autophagy-related factors in renal tissue. Additionally, CD36 and fibrosis-related factors were significantly elevated in MCs following pIgA1 stimulation. CD36 knockdown resulted in decreased extracellular matrix (ECM) accumulation in pIgA1-stimulated MCs. RNA-seq analysis of MCs with CD36 knockdown revealed significant alterations in autophagy and CD36 silencing restored autophagy levels in MCs treated with the autophagy inhibitor 3MA.

CONCLUSION

Our study confirmed that CD36 expression increases with the clinical progression of IgAN and CD36 knockdown alleviates MCs injury by inhibiting ECM accumulation and restoring autophagy.

Evolutionary patterns and research frontiers in autophagy in podocytopathies: a bibliometric analysis

Introduction

Podocytopathies are a uniquely renal disease syndrome, in which direct or indirect podocyte injury leads to proteinuria or nephrotic syndrome. Of the many factors that contribute to podocytopathies, the abnormal regulation of autophagy, such insufficient or excessive autophagy levels, have been proposed to play a significant role in the occurrence and development of podocytopathies. However, there still has been a lack of systematic and comparative research to elucidate exact role of autophagy in podocytopathies and its current research status. This study aims to utilize bibliometric analysis to clarify the role of autophagy in the pathogenesis of podocytopathies, analyze the research focus in this area, as well as explore the future research trends.

Methods

We retrieved original articles and review papers with respect to autophagy in podocytopathies research published between the year 2008 and 2022 from the Web of Science Core Collection (WOSCC). Then, VOSviewer and CiteSpace software were employed to reveal the leading subjects and generate visual maps of countries/regions, organizations, authors, journals, and keyword networks in this field.

Results and discussion

A total of 825 publications regarding autophagy in podocytopathies published between 2008 and 2022 were included, with China contributing the most followed by the United States and Japan. Professor Koya Daisuke, Professor He Qiang, and Professor Jin Juan are the most prolific researchers in this field. Oxidative stress, the NLRP3 inflammasome, and therapeutic targets were the knowledge base for the research in this special field. Taken together, this bibliometric analysis helps us reveal the current research hotspots and guide future research directions, which provides a reference for scholars to further investigate the role of autophagy in podocytopathies as well as conduct clinical trial with autophagy regulators in podocytopathies.

Histopathologic Analysis of Human Kidney Spatial Transcriptomics Data: Toward Precision Pathology

The application of spatial transcriptomics (ST) technologies is booming and has already yielded important insights across many different tissues and disease models. In nephrology, ST technologies have helped to decipher the cellular and molecular mechanisms in kidney diseases and have allowed the recent creation of spatially anchored human kidney atlases of healthy and diseased kidney tissues. During ST data analysis, the computationally annotated clusters are often superimposed on a histologic image without their initial identification being based on the morphologic and/or spatial analyses of the tissues and lesions. Herein, histopathologic ST data from a human kidney sample were modeled to correspond as closely as possible to the kidney biopsy sample in a health care or research context. This study shows the feasibility of a morphology-based approach to interpreting ST data, helping to improve our understanding of the lesion phenomena at work in chronic kidney disease at both the cellular and the molecular level. Finally, the newly identified pathology-based clusters could be accurately projected onto other slides from nephrectomy or needle biopsy samples. Thus, they serve as a reference for analyzing other kidney tissues, paving the way for the future of molecular microscopy and precision pathology.

Unveiling the podocyte-protective effect of sodium-glucose cotransporter-2 inhibitors

The renoprotective effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors in both diabetic and nondiabetic nephropathy are widely recognized due to results from randomized controlled trials notably the DAPA-CKD and EMPA-KIDNEY trials. Research exploring the mechanisms of renoprotection indicates that SGLT2 inhibitors exert protective effects on podocytes by enhancing autophagy and stabilizing the structure of podocytes and basement membranes. Furthermore, reductions in lipotoxicity, oxidative stress, and inflammation have been confirmed with SGLT2 inhibitor treatment. Recent clinical studies have also begun to explore the effects of SGLT2 inhibitors on nondiabetic podocytopathies, such as focal segmental glomerulosclerosis. In this review, we summarize clinical and laboratory studies that focus on the podocyte-protective effects of SGLT2 inhibitors, exploring the potential for broader applications of this novel therapeutic agent in kidney disease.

Bioinformatics identifies key genes and potential therapeutic targets in the pathological mechanism of oxidative stress in Randall's plaque

Randall's plaque (RP) is recognized as a precursor lesion for kidney stones, with its formation and progression potentially linked to oxidative stress. Previous studies have provided limited insights into the underlying mechanisms of RP, failing to fully elucidate its molecular pathways. To investigate the relationship between oxidative stress and RP, we employed bioinformatics approaches to identify key genes, predict associated pathways and drug molecules, analyze variations in immune cell populations, and construct diagnostic models. We initially identified three differentially expressed genes related to oxidative stress: BFSP1, LONF1, and TAF1D. These genes and their co-expressed counterparts are enriched in pathways related to oxidative phosphorylation, cellular adhesion processes, steroid hormone biosynthesis, and autophagy. Furthermore, we observed significant differences in two types of immune cells across the study groups. Ultimately, predictions from drug molecular docking suggest that BFSP1 may serve as a promising therapeutic target for RP. We propose that the formation of RP mediated by oxidative stress could be associated with BFSP1, LONF1, TAF1D along with CD56dim natural killer cells and memory B cells. Thus far, BFSP1 emerges as a pivotal therapeutic target for RP development. These findings offer new perspectives on the mechanisms underlying the pathogenesis of RP.

The pro-fibrotic role of autophagy in renal intrinsic cells: mechanisms and therapeutic potential in chronic kidney disease

Chronic kidney disease (CKD) represents a significant global public health burden, affecting over 10% of the world's population. Its high morbidity, multifactorial complications, and substantial mortality impose significant burdens on healthcare systems and patients, necessitating considerable investment in healthcare resources. Renal fibrosis (RF) is a key pathological feature and driver of CKD progression. Extensive research indicates that autophagy participates in the complete pathogenesis of RF. Under physiological conditions, autophagy is essential for maintaining renal cellular homeostasis. However, under pathological conditions, perhaps aberrant and sustained activation of autophagy contributes to oxidative stress, apoptosis, inflammation, etc. Ultimately, they accelerate the development of RF. The role of autophagy in RF is currently controversial. This review investigates the molecular mechanisms by which intrinsic renal cell autophagy contributes to RF across diverse disease models, suggesting that autophagy and its associated regulatory pathways represent potential diagnostic and therapeutic targets for CKD.

Dynamic regulation of proximal tubular autophagy from injury to repair after ischemic kidney damage

BACKGROUND

The role of proximal tubular autophagy in repairing kidney injury following ischemia remains unclear.

METHODS

In this study, we utilized mice with conditional deletion of the Atg5 gene in proximal tubules and monitored the long-term dynamic regulation of autophagy following ischemic acute kidney injury (AKI).

RESULTS

The results showed that Atg5-deficient proximal tubule epithelial cells exhibited damaged mitochondria, concentric membranes, and lysosomal accumulation 24 h after ischemia/reperfusion. However, 28 days after ischemia/reperfusion, concentric membrane bodies remained, but lysosomal accumulation was no longer observed. Notably, the absence of Atg5 in renal tubular epithelial cells impaired renal function and led to increased tubular cell proliferation and oxidative stress in the early stage of injury. However, during the repair period following AKI, Atg5 deficiency exhibited no significant difference in the expression of proliferating cell nuclear antigen (PCNA) and 4-hydoxynonenal (4HNE), suggesting that the improvement in renal fibrosis associated with Atg5 deficiency is unlikely to result from its effect on cell proliferation or reactive oxygen species levels. Additionally, Atg5 deficiency inhibits the secretion of profibrotic factor fibroblast growth factor 2 (FGF2) from the early stage of renal injury to the recovery stage of AKI, indicating that autophagy-specific regulation of FGF2 secretion is a dynamic process overlapping with other stages of injury. Furthermore, increased co-localization of ATG5 with 4HNE and FGF2 was observed in patient samples.

CONCLUSION

In summary, our results suggest that the dynamic regulation of autophagy on key molecules involved in kidney injury and repair varies with the stage of kidney injury.

Advances in the study of key cells and signaling pathways in renal fibrosis and the interventional role of Chinese medicines

Renal fibrosis (RF) is a pathological process characterized by the excessive accumulation of extracellular matrix (ECM), which triggers a repair cascade in response to stimuli and pathogenic factors, leading to the activation of molecular signaling pathways involved in fibrosis. This article discusses the key cells, molecules, and signaling pathways implicated in the pathogenesis of RF, with a particular focus on tubular epithelial cells (TECs), cellular senescence, ferroptosis, autophagy, epithelial-mesenchymal transition (EMT), and transforming growth factor-β(TGF-β)/Smad signaling. These factors drive the core and regulatory pathways that significantly influence RF. A comprehensive understanding of their roles is essential. Through a literature review, we explore recent advancements in traditional Chinese medicine (TCM) aimed at reducing RF and inhibiting chronic kidney disease (CKD). We summarize, analyze, and elaborate on the important role of Chinese herbs in RF, aiming to provide new directions for their application in prevention and treatment, as well as scientific guidance for clinical practices.