Carnosine alleviates podocyte injury in diabetic nephropathy by targeting caspase-1-mediated pyroptosis

Electroacupuncture Promotes Gastric Motility by Suppressing Pyroptosis via NLRP3/Caspase-1/GSDMD Signaling Pathway in Diabetic Gastroparesis Rats

OBJECTIVE

To investigate the mechanism of electroacupuncture (EA) in treating diabetic gastroparesis (DGP) by inhibiting the activation of Nod-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome and pyroptosis mediated via NLRP3/cysteinyl aspartate specific proteinase-1 (caspase-1)/gasdermin D (GSDMD) signaling pathway.

METHODS

Forty Sprague-Dawley rats were randomly divided into 4 groups including the control, DGP model, EA, and MCC950 groups. The DGP model was established by a one-time high-dose intraperitoneal injection of 2% streptozotocin and a high-glucose and high-fat diet for 8 weeks. EA intervention was conducted at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6) with sparse-dense wave for 15 min, and was administered for 3 courses of 5 days. After intervention, the blood glucose, urine glucose, gastric emptying, and intestinal propulsive rate were observed. Besides, HE staining was used to observe histopathological changes in gastric antrum tissues, and TUNEL staining was utilized to detect DNA damage. Protein expression levels of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), pro-caspase-1, caspase-1 and GSDMD were measured by Western blot. Immunofluorescence staining was employed to assess the activity of GSDMD-N. Lactate dehydrogenase (LDH) levels were detected by using a biochemical kit.

RESULTS

DGP rats showed persistent hyperglycemia and a significant decrease in gastrointestinal motility (P<0.05 or P<0.01), accompanied by pathological damage in their gastric antrum tissues. Cellular DNA was obviously damaged, and the expressions of NLRP3, ASC, pro-caspase-1, caspase-1 and GSDMD proteins were significantly elevated, along with enhanced fluorescence signals of GSDMD-N and increased LDH release (P<0.01). EA mitigated hyperglycemia, improved gastrointestinal motility in DGP rats and alleviated their pathological injury (P<0.05). Furthermore, EA reduced cellular DNA damage, lowered the protein levels of NLRP3, ASC, pro-caspase-1, caspase-1 and GSDMD, suppressed GSDMD-N activity, and decreased LDH release (P<0.05 or P<0.01), demonstrating effects comparable to MCC950.

CONCLUSION

EA promotes gastrointestinal motility and repairs the pathological damage in DGP rats, and its mechanism may be related to the inhibition of NLRP3 inflammasome and pyroptosis mediated by NLRP3/caspase-1/GSDMD pathway.

Single-nucleus RNA sequencing reveals ARHGAP28 expression of podocytes as a biomarker in human diabetic nephropathy

Introduction

Diabetic kidney disease (DKD) represents serious diabetes-associated complications, and podocyte loss is an important histologic sign of DKD. The cellular and molecular profiles of podocytes in DKD have yet to be fully elucidated.

Methods

This study analyzed kidney-related single-nucleus RNA-seq datasets (GSE131882, GSE121862, and GSE141115) and human diabetic kidney glomeruli transcriptome profiling (GSE30122). ARHGAP28 expression was validated by western blot and immunohistochemistry.

Results

In human kidney tissues, 154 differentially expressed genes (DEGs) were identified in podocytes, which were enriched in biological processes related to nephron development and extracellular matrix-receptor interactions. Similarly, in the mouse kidney, 344 DEGs were found, clustering in pathways associated with renal development and signaling mechanisms like PI3K/Akt (phosphatidylinositol-3 kinase/protein kinase B) and PPAR (peroxisome proliferator-activated receptor). In diabetic human kidney glomeruli, 438 DEGs were identified, showing significant enrichment in pathways related to diabetic nephropathy. Venn analysis revealed 22 DEGs common across human and mouse podocytes and diabetic glomeruli, with ARHGAP28 being notably overexpressed in podocytes. The diabetic nephropathy model using db/db mice showed that ARHGAP28 expression was significantly upregulated in the kidney cortex and glomeruli. In vitro studies using a high-glucose podocyte model corroborated these findings.

Conclusions

Collectively, this study provides an insight into the function and diagnosis of DKD and indicates that ARHGAP28 in podocytes is a potential biomarker of DKD.

Targeting pyroptosis: A novel strategy of ginseng for the treatment of diabetes and its chronic complications

BACKGROUND

Pyroptosis is a recently identified form of programmed cell death that plays a crucial role in the pathogenesis and progression of diabetes and associated chronic complications, while the occurrence mechanism remains unclear. Ginseng (Panax Ginseng C. A. Mey.) is a valuable traditional medicinal material with proved therapeutic effects on prevention and treatment of diabetes and diabetic complications. Targeting pyroptosis pathway has become a focus of study for ginseng in improvement of diabetes and related chronic complications.

PURPOSE

The review aims to elucidate the happening mechanism of pyroptosis in diabetes and diabetic chronic complications, evaluate the effects of ginseng and its active components on diabetes and its chronic complications via pyroptosis-related pathways, and provide a new perspective for the management of diabetes.

METHODS

We conducted the literature retrieval with PubMed, Web of Science, and ScienceDirect databases in a systematic manner (up to August 2024). The keywords included pyroptosis, diabetes, diabetic nephropathy, diabetic retinopathy, diabetic cardiomyopathy, diabetic neuropathy, ginseng, ginseng extract, and ginsenoside. The obtained literatures were comprehensively sorted out.

RESULTS

Oxidative stress, endoplasmic reticulum stress (ERS), and inflammatory responses were primary contributors to pyroptosis in diabetes and associated chronic complications. In addition, some RNA molecules (miRNAs, circRNAs, and lncRNAs) also contributed to pyroptosis under hyperglycemia. The signaling pathways mainly included Nrf2/HO-1, IκB/NF-κB/NLRP3, NOX1/NOX4/TXNIP, and P2X7R/TXNIP/NLRP3. Ginseng extracts, some ginsenosides and flavonoid (Quercetin) could exert anti-diabetic effect by regulating pyroptosis-related pathways. We also discussed the toxicity, side effects and clinical applications of ginseng.

CONCLUSION

In summary, this review elucidates the happening mechanisms of pyroptosis in diabetes and associated chronic complications, and summarizes published studies about ginseng and its active ingredients in improving diabetes by regulating pyroptosis-related pathways. However, almost all researches are limited to animal and cell experiments, and more clinical trials are required to prove the therapeutic effect of ginseng on diabetes by targeting pyroptosis.

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.

Exploring the glycation association with dyslipidaemia: Novel approach for diabetic nephropathy

The transcription factor known as sterol regulatory element-binding protein (SREBP) and the glycation pathways, specifically the formation of Advanced Glycation End Products (AGEs), have a significant and deleterious impact on the kidney. They alter renal lipid metabolism and promote glomerulosclerosis, mesangial cell expansion, tubulointerstitial fibrosis, and inflammation, leading to diabetic nephropathy (DN) progression. Although several pieces of scientific evidence are reported for potential causes of glycation and lipotoxicity in DN, the underlying mechanism of renal lipid accumulation still needs to be fully understood. We provide a rationalized view on how AGEs exert multiple effects that cause SREBP activation and inflammation, contributing to DN through Receptor for AGEs (RAGE) signaling, AGE-R1-dependent downregulation of Sirtuin 1 (SIRT-1), and increased SREBP Cleavage Activating Protein (SCAP) glycosylation. This review emphasizes the association between glycation and the SREBP pathway and how it affects the onset of DN associated with obesity. Finally, we discuss the correlation of glycation and the SREBP pathway with insulin resistance (IR), oxidative stress, endoplasmic reticulum stress, inflammation, and existing and emerging therapeutic approaches toward better controlling obesity-related DN.

Identifying the Potential Diagnostic Gene Biomarkers and Forecasting the Potential Therapeutic Agents for Advanced Diabetic Nephropathy Based on Pyroptosis and Ferroptosis

Background

Diabetic nephropathy (DN) is a prevalent complication of diabetes, often leading to end-stage kidney disease (ESKD). Advanced DN progresses to ESKD rapidly, yet effective diagnostic indicators and treatments are lacking.

Methods

Two DN-related datasets were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the R packages. Pyroptosis-related genes (PRGs) and ferroptosis-related genes (FRGs) were collected from their respective database. Pyroptosis- and ferroptosis-related differentially expressed genes (PFRDEGs) were identified by overlapping DEGs, PRGs, and FRGs for further analysis, including functional enrichment and immune infiltration. Hub genes were identified using a PPI network via MCODE-plugin in Cytoscape. GeneMANIA was utilized to explore intermolecular interactions among hub genes. Based on these hub genes, a diagnostic model was constructed using the receiver operating characteristic curve and potential therapeutic agents were retrieved. Correlation analysis between hub genes and estimated glomerular filtration rate was performed using Nephroseq v5 database, and expression of hub genes was validated in external GEO database, Nephroseq v5 database and DN mice in vivo.

Results

Four hub genes (CYBB, LCN2, JUN and ADIPOQ) were identified, and three of the four hub genes (CYBB, LCN2 and ADIPOQ) were found to be potential biomarkers for advanced DN. On this basis, three potential therapeutic agents were screened. More importantly, a series of biological experiments confirmed that CYBB and LCN2 were significantly up-regulated in DN mice.

Conclusion

This study identifies three hub genes as diagnostic biomarkers and mines three potential therapeutic agents for advanced DN, providing new insights into the role of pyroptosis and ferroptosis in advanced DN and laying the foundation for future research.

Podocyte Death in Diabetic Kidney Disease: Potential Molecular Mechanisms and Therapeutic Targets

Cell deaths maintain the normal function of tissues and organs. In pathological conditions, the abnormal activation or disruption of cell death often leads to pathophysiological effects. Diabetic kidney disease (DKD), a significant microvascular complication of diabetes, is linked to high mortality and morbidity rates, imposing a substantial burden on global healthcare systems and economies. Loss and detachment of podocytes are key pathological changes in the progression of DKD. This review explores the potential mechanisms of apoptosis, necrosis, autophagy, pyroptosis, ferroptosis, cuproptosis, and podoptosis in podocytes, focusing on how different cell death modes contribute to the progression of DKD. It recognizes the limitations of current research and presents the latest basic and clinical research studies targeting podocyte death pathways in DKD. Lastly, it focuses on the future of targeting podocyte cell death to treat DKD, with the intention of inspiring further research and the development of therapeutic strategies.

PEGylation renders carnosine resistant to hydrolysis by serum carnosinase and increases renal carnosine levels

Carnosine's protective effect in rodent models of glycoxidative stress have provided a rational for translation of these findings in therapeutic concepts in patient with diabetic kidney disease. In contrast to rodents however, carnosine is rapidly degraded by the carnosinase-1 enzyme. To overcome this hurdle, we sought to protect hydrolysis of carnosine by conjugation to Methoxypolyethylene glycol amine (mPEG-NH2). PEGylated carnosine (PEG-car) was used to study the hydrolysis of carnosine by human serum as well as to compare the pharmacokinetics of PEG-car and L-carnosine in mice after intravenous (IV) injection. While L-carnosine was rapidly hydrolyzed in human serum, PEG-car was highly resistant to hydrolysis. Addition of unconjugated PEG to carnosine or PEG-car did not influence hydrolysis of carnosine in serum. In mice PEG-car and L-carnosine exhibited similar pharmacokinetics in serum but differed in half-life time (t1/2) in kidney, with PEG-car showing a significantly higher t1/2 compared to L-carnosine. Hence, PEGylation of carnosine is an effective approach to prevent carnosine degradations and to achieve higher renal carnosine levels. However, further studies are warranted to test if the protective properties of carnosine are preserved after PEGylation.

Insulin-like growth factor 1 knockdown attenuates high glucose-induced podocyte injury by promoting the JAK2/STAT signalling-mediated autophagy

PURPOSE

Podocyte injury plays a crucial role in the development of diabetic nephropathy (DN). A high serum level of insulin-like growth factor 1 (IGF-1) has been observed in patients with DN. This paper is to study the role and mechanism of IGF-1 in high glucose (HG)-induced podocyte injury.

METHODS

Mouse podocytes MPC-5 were treated with HG to establish a DN model in vitro. db/db diabetic mice and db/m nondiabetic mice were used to evaluate the IGF-1 role in vivo. Western blotting was used for measuring protein levels of IGF-1 receptor, Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling pathway-related markers, podocyte markers podocin and nephrin, apoptosis- and autophagy-related markers in MPC-5 cells. Immunofluorescence staining was implemented for measuring the expression of nephrin and the autophagy marker LC3. Flow cytometry was used for detecting podocyte apoptosis.

RESULTS

IGF-1 expression was increased in HG-stimulated MPC-5 cells and the kidney of db/db diabetic mice compared with corresponding controls. Knocking down IGF-1 downregulated IGF-1R and inhibited JAK2/STAT signalling pathway in HG-treated MPC-5 cells and db/db diabetic mice. IGF-1 silencing attenuated HG-induced podocyte injury, apoptosis and reduction in autophagy. Activating the JAK2/STAT signalling pathway or inhibiting autophagy reversed the effects of IGF-1 silencing on HG-treated MPC-5 cells.

CONCLUSION

Knocking down IGF-1 alleviates HG-induced podocyte injury and apoptosis by inactivating the JAK2/STAT signalling pathway and enhancing autophagy.

Carnosine ameliorates postoperative cognitive dysfunction of aged rats by limiting astrocytes pyroptosis

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in elderly patients, and neuroinflammation is a key hallmark. Recent studies suggest that the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome-mediated astrocytes pyroptosis is involved in the regulation of neuroinflammation in many neurocognitive diseases, while its role in POCD remains obscure. Carnosine is a natural endogenous dipeptide with anti-inflammatory and neuroprotective effects. To explore the effect of carnosine on POCD and its mechanism, we established a POCD model by exploratory laparotomy in 24-month-old male Sprague-Dawley rats. We found that the administrated of carnosine notably attenuated surgery-induced NLRP3 inflammasome activation and pyroptosis in astrocytes, central inflammation, and neuronal damage in the hippocampus of aged rats. In addition, carnosine dramatically ameliorated the learning and memory deficits of surgery-induced aged rats. Then in the in vitro experiments, we stimulated primary astrocytes with lipopolysaccharide (LPS) after carnosine pretreatment. The results also showed that the application of carnosine alleviated the activation of the NLRP3 inflammasome, pyroptosis, and inflammatory response in astrocytes stimulated by LPS. Taken together, these findings suggest that carnosine improves POCD in aged rats via inhibiting NLRP3-mediated astrocytes pyroptosis and neuroinflammation.

The protective role of carnosine against type 2 diabetes-induced cognitive impairment

The morbidity and mortality associated with type 2 diabetes mellitus (T2DM) have grown exponentially over the last 30 years. Together with its associated complications, the mortality rates have increased. One important complication in those living with T2DM is the acceleration of age-related cognitive decline. T2DM-induced cognitive impairment seriously affects memory, executive function, and quality of life. However, there is a lack of effective treatment for both diabetes and cognitive decline. Thus, finding novel treatments which are cheap, effective in both diabetes and cognitive impairment, are easily accessible, are needed to reduce impact on patients with diabetes and health-care systems. Carnosine, a histidine containing dipeptide, plays a protective role in cognitive diseases due to its antioxidant, anti-inflammation, and anti-glycation properties, all of which may slow the development of neurodegenerative diseases and ischemic injury. Furthermore, carnosine is also involved in regulating glucose and insulin in diabetes. Herein, we discuss the neuroprotective role of carnosine and its mechanisms in T2DM-induced cognitive impairment, which may provide a theoretical basis and evidence base to evaluate whether carnosine has therapeutic effects in alleviating cognitive dysfunction in T2DM patients.

NET-Related Gene as Potential Diagnostic Biomarkers for Diabetic Tubulointerstitial Injury

Background: Tubulointerstitial injury plays a pivotal role in the progression of diabetic kidney disease (DKD), yet the link between neutrophil extracellular traps (NETs) and diabetic tubulointerstitial injury is still unclear. Methods: We analyzed microarray data (GSE30122) from the Gene Expression Omnibus (GEO) database to identify differentially expressed genes (DEGs) associated with DKD's tubulointerstitial injury. Functional and pathway enrichment analyses were conducted to elucidate the involved biological processes (BP) and pathways. Weighted gene coexpression network analysis (WGCNA) identified modules associated with DKD. LASSO regression and random forest selected NET-related characteristic genes (NRGs) related to DKD tubulointerstitial injury. Results: Eight hundred ninety-eight DEGs were identified from the GSE30122 dataset. A significant module associated with diabetic tubulointerstitial injury overlapped with 15 NRGs. The hub genes, CASP1 and LYZ, were identified as potential biomarkers. Functional enrichment linked these genes with immune cell trafficking, metabolic alterations, and inflammatory responses. NRGs negatively correlated with glomerular filtration rate (GFR) in the Neph v5 database. Immunohistochemistry (IHC) validated increased NRGs in DKD tubulointerstitial injury. Conclusion: Our findings suggest that the CASP1 and LYZ genes may serve as potential diagnostic biomarkers for diabetic tubulointerstitial injury. Furthermore, NRGs involved in diabetic tubulointerstitial injury could emerge as prospective targets for the diagnosis and treatment of DKD.

Rutaecarpine protects podocytes in diabetic kidney disease by targeting VEGFR2/NLRP3-mediated pyroptosis

OBJECTIVE

Diabetic kidney disease (DKD) is the most common cause of the end-stage renal disease, which has limited treatment options. Rutaecarpine has anti-inflammatory effects, however, it has not been studied in DKD. Pyroptosis is a newly discovered mode of podocyte death related to inflammation. This study aimed to explore whether Rutaecarpine can ameliorate DKD and to clarify its possible mechanism.

METHODS

In this study, we investigated the effects of Rutaecarpine on DKD using diabetic mice model (db/db mice) and high glucose (HG)-stimulated mouse podocyte clone 5 (MPC5) cells. Quantitative reverse transcription polymerase chain reaction and western blot were performed to detect the related gene and protein levels. We applied pharmacological prediction, co-immunoprecipitation assay, cellular thermal shift assay, surface plasmon resonance to find the target and pathway of the substances. Gene knockdown experiments confirmed this view in HG-stimulated MPC5 cells.

RESULTS

Rutaecarpine significantly reduced proteinuria, histopathological damage, and pyroptosis of podocytes in a dose-dependent manner in db/db mice. Rutaecarpine also protected high glucose induced MPC5 injury in vitro experiments. Mechanistically, Rutaecarpine can inhibit pyroptosis in HG-stimulated MPC5 by reducing the expression of VEGFR2. VEGFR2 is a target of Rutaecarpine in MPC5 cells and directly binds to the pyroptosis initiation signal, NLRP3. VEGFR2-knockdown disrupted the beneficial effects of Rutaecarpine in HG-stimulated MPC5 cells.

CONCLUSION

Rutaecarpine inhibits renal inflammation and pyroptosis through VEGFR2/NLRP3 pathway, thereby alleviating glomerular podocyte injury. These findings highlight the potential of Rutaecarpine as a novel drug for DKD treatment.

Autophagy, Pyroptosis and Ferroptosis are Rising Stars in the Pathogenesis of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most common microvascular complications in diabetes and can potentially develop into end-stage renal disease. Its pathogenesis is complex and not fully understood. Podocytes, glomerular endothelial cells (GECs), glomerular mesangial cells (GMCs) and renal tubular epithelial cells (TECs) play important roles in the normal function of glomerulus and renal tubules, and their injury is involved in the progression of DN. Although our understanding of the mechanisms leading to DN has substantially improved, we still need to find more effective therapeutic targets. Autophagy, pyroptosis and ferroptosis are programmed cell death processes that are associated with inflammation and are closely related to a variety of diseases. Recently, a growing number of studies have reported that autophagy, pyroptosis and ferroptosis regulate the function of podocytes, GECs, GMCs and TECs. This review highlights the contributions of autophagy, pyroptosis, and ferroptosis to DN injury in these cells, offering potential therapeutic targets for DN treatment.

The Role of Pyroptosis in the Pathogenesis of Kidney Diseases

BACKGROUND

Recently, in addition to apoptosis and necrosis, several other forms of cell death have been discovered, such as necroptosis, autophagy, pyroptosis, and ferroptosis. These cell death modalities play diverse roles in kidney diseases. Pyroptosis is a newly described type of proinflammatory programmed necrosis. Further exploring pyroptosis is helpful to slow the progression of kidney diseases and reduce their complications.

SUMMARY

Pyroptosis is mainly mediated by the cleavage of gasdermin D (GSDMD) along with downstream inflammasome activation. Activated caspase-1 induces the release of cytokines by cleaving GSDMD. Inflammation is a major pathogenic mechanism for kidney diseases. Increasing evidence corroborated that pyroptosis was closely related to the progression of renal diseases, including acute kidney injury, renal fibrosis, diabetic nephropathy, and kidney cancer. In this paper, we reviewed the role and the therapeutic treatment of pyroptosis in renal diseases.

KEY MESSAGES

The better understanding of the progress and new intervention approaches of pyroptosis in kidney diseases may pave the way for new therapeutic opportunities in clinical practice.

Triptolide protects against podocyte injury in diabetic nephropathy by activating the Nrf2/HO-1 pathway and inhibiting the NLRP3 inflammasome pathway

Objectives: Diabetic nephropathy (DN) is the most common microvascular complication of diabetes mellitus. This study investigated the mechanism of triptolide (TP) in podocyte injury in DN.Methods: DN mouse models were established by feeding with a high-fat diet and injecting with streptozocin and MPC5 podocyte injury models were induced by high-glucose (HG), followed by TP treatment. Fasting blood glucose and renal function indicators, such as 24 h urine albumin (UAlb), serum creatinine (SCr), blood urea nitrogen (BUN), and kidney/body weight ratio of mice were examined. H&E and TUNEL staining were performed for evaluating pathological changes and apoptosis in renal tissue. The podocyte markers, reactive oxygen species (ROS), oxidative stress (OS), serum inflammatory cytokines, nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway-related proteins, and pyroptosis were detected by Western blotting and corresponding kits. MPC5 cell viability and pyroptosis were evaluated by MTT and Hoechst 33342/PI double-fluorescence staining. Nrf2 inhibitor ML385 was used to verify the regulation of TP on Nrf2.Results: TP improved renal function and histopathological injury of DN mice, alleviated podocytes injury, reduced OS and ROS by activating the Nrf2/heme oxygenase-1 (HO-1) pathway, and weakened pyroptosis by inhibiting the nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome pathway. In vitro experiments further verified the inhibition of TP on OS and pyroptosis by mediating the Nrf2/HO-1 and NLRP3 inflammasome pathways. Inhibition of Nrf2 reversed the protective effect of TP on MPC5 cells.Conclusions: Overall, TP alleviated podocyte injury in DN by inhibiting OS and pyroptosis via Nrf2/ROS/NLRP3 axis.

Identification and validation of disulfidptosis-related gene signatures and their subtype in diabetic nephropathy

Background: Diabetic nephropathy (DN) is the most common complication of diabetes, and its pathogenesis is complex involving a variety of programmed cell death, inflammatory responses, and autophagy mechanisms. Disulfidptosis is a newly discovered mechanism of cell death. There are little studies about the role of disulfidptosis on DN. Methods: First, we obtained the data required for this study from the GeneCards database, the Nephroseq v5 database, and the GEO database. Through differential analysis, we obtained differential disulfidptosis-related genes. At the same time, through WGCNA analysis, we obtained key module genes in DN patients. The obtained intersecting genes were further screened by Lasso as well as SVM-RFE. By intersecting the results of the two, we ended up with a key gene for diabetic nephropathy. The diagnostic performance and expression of key genes were verified by the GSE30528, GSE30529, GSE96804, and Nephroseq v5 datasets. Using clinical information from the Nephroseq v5 database, we investigated the correlation between the expression of key genes and estimated glomerular filtration rate (eGFR) and serum creatinine content. Next, we constructed a nomogram and analyzed the immune microenvironment of patients with DN. The identification of subtypes facilitates individualized treatment of patients with DN. Results: We obtained 91 differential disulfidptosis-related genes. Through WGCNA analysis, we obtained 39 key module genes in DN patients. Taking the intersection of the two, we preliminarily screened 20 genes characteristic of DN. Through correlation analysis, we found that these 20 genes are positively correlated with each other. Further screening by Lasso and SVM-RFE algorithms and intersecting the results of the two, we identified CXCL6, CD48, C1QB, and COL6A3 as key genes in DN. Clinical correlation analysis found that the expression levels of key genes were closely related to eGFR. Immune cell infiltration is higher in samples from patients with DN than in normal samples. Conclusion: We identified and validated 4 DN key genes from disulfidptosis-related genes that CXCL6, CD48, C1QB, and COL6A3 may be key genes that promote the onset of DN and are closely related to the eGFR and immune cell infiltrated in the kidney tissue.

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

Diabetic kidney disease (DKD) is the main cause of end-stage renal disease, and its clinical manifestations are progressive proteinuria, decreased glomerular filtration rate, and renal failure. The injury and death of glomerular podocytes are the keys to DKD. Currently, a variety of cell death modes have been identified in podocytes, including apoptosis, autophagy, endoplasmic reticulum (ER) stress, pyroptosis, necroptosis, ferroptosis, mitotic catastrophe, etc. The signaling pathways leading to these cell death processes are interconnected and can be activated simultaneously or in parallel. They are essential for cell survival and death that determine the fate of cells. With the deepening of the research on the mechanism of cell death, more and more researchers have devoted their attention to the underlying pathologic research and the drug therapy research of DKD. In this paper, we discussed the podocyte physiologic role and DKD processes. We also provide an overview of the types and specific mechanisms involved in each type of cell death in DKD, as well as related targeted therapy methods and drugs are reviewed. In the last part we discuss the complexity and potential crosstalk between various modes of cell death, which will help improve the understanding of podocyte death and lay a foundation for new and ideal targeted therapy strategies for DKD treatment in the future.

Astragaloside IV Inhibited Podocyte Pyroptosis in Diabetic Kidney Disease by Regulating SIRT6/HIF-1α Axis

To investigate the effect of astragaloside IV (AS) on podocytes pyroptosis in diabetic kidney disease (DKD). Forty male Sprague-Dawley rats were randomly divided into normal group (n = 10) and model group (n = 30). Rats in model group were intraperitoneally injected streptozotocin (60 mg/kg) for 3 days to induce DKD. Then rats were divided into DKD group, AS group, and UBCS group. The AS group was given 40 mg/kg/d of AS by gavage, and UBCS group was given 50 mg/kg/d of UBCS039 by gavage, and normal group and DKD group were given the same amount saline for 8 weeks, once a day. Hematoxylin-eosin and masson staining were used to observe pathology of kidney. Rat podocytes were divided into normal group, mannitol hypertonic group, high-glucose group, UBCS group, OSS group, and AS group. Western blotting, quantitative real-time polymerase chain reaction, immunofluorescence, and flow cytometry were used to analyze pyroptosis-related markers and reactive oxygen species (ROS) levels. Results showed that AS inhibited ROS and alleviated podocytes pyroptosis in rats by increasing expression of sirtuin 6 (SIRT6) and decreasing expression of hypoxia inducible factor 1 subunit alpha (HIF-1α). UBCS039 and AS enhanced SIRT6 level, decreased HIF-1α level, and finally improved pyroptosis of podocytes in vitro, whereas OSS-128167 showed the opposite effect for podocytes pyroptosis. AS improved podocytes pyroptosis in DKD by regulating SIRT6/HIF-1α pathway, thereby alleviating injury of DKD.

Active role of amino acid metabolism in early diagnosis and treatment of diabetic kidney disease

Diabetic Kidney Disease (DKD) is one of the significant microvascular consequences of type 2 diabetes mellitus with a complex etiology and protracted course. In the early stages of DKD, the majority of patients experience an insidious onset and few overt clinical symptoms and indicators, but they are prone to develop end-stage renal disease in the later stage, which is life-threatening. The abnormal amino acid metabolism is tightly associated with the development of DKD, which involves several pathological processes such as oxidative stress, inflammatory response, and immune response and is also closely related to autophagy, mitochondrial dysfunction, and iron death. With a focus on taurine, branched-chain amino acids (BCAAs) and glutamine, we explored the biological effects of various amino acid mechanisms linked to DKD, the impact of amino acid metabolism in the early diagnosis of DKD, and the role of amino acid metabolism in treating DKD, to offer fresh objectives and guidelines for later early detection and DKD therapy.

GBP2 promotes M1 macrophage polarization by activating the notch1 signaling pathway in diabetic nephropathy

Background

Diabetic nephropathy (DN) is one of the most common diabetic complications, which has become the primary cause of end-stage renal disease (ESRD) globally. Macrophage infiltration has been proven vital in the occurrence and development of DN. This study was designed to investigate the hub genes involved in macrophage-mediated inflammation of DN via bioinformatics analysis and experimental validation.

Methods

Gene microarray datasets were obtained from the Gene Expression Omnibus (GEO) public website. Integrating the CIBERSORT, weighted gene co-expression network analysis (WGCNA) and DEGs, we screened macrophage M1-associated key genes with the highest intramodular connectivity. Subsequently, the Least Absolute Shrinkage and Selection Operator (LASSO) regression was utilized to further mine hub genes. GSE104954 acted as an external validation to predict the expression levels and diagnostic performance of these hub genes. The Nephroseq online platform was employed to evaluate the clinical implications of these hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed to elucidate the dominant biological functions and signal pathways. Finally, we conducted experiments to verify the role of GBP2 in M1 macrophage-mediated inflammatory response and the underlying mechanism of this role.

Results

Sixteen DEGs with the highest connectivity in M1 macrophages-associated module (paleturquoise module) were determined. Subsequently, we identified four hub genes through LASSO regression analysis, including CASP1, MS4A4A, CD53, and GBP2. Consistent with the training set, expression levels of these four hub genes manifested memorably elevated and the ROC curves indicated a good diagnostic accuracy with an area under the curve of greater than 0.8. Clinically, enhanced expression of these four hub genes predicted worse outcomes of DN patients. Given the known correlation between the first three hub genes and macrophage-mediated inflammation, experiments were performed to demonstrate the effect of GBP2, which proved that GBP2 contributed to M1 polarization of macrophages by activating the notch1 signaling pathway.

Conclusion

Our findings detected four hub genes, namely CASP1, MS4A4A, CD53, and GBP2, may involve in the progression of DN via pro-inflammatory M1 macrophage phenotype. GBP2 could be a promising prognostic biomarker and intervention target for DN by regulating M1 polarization.

Identification of pyroptosis-related genes and potential drugs in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the serious microvascular complications of diabetes mellitus (DM). A growing body of research has demonstrated that the inflammatory state plays a critical role in the incidence and development of DN. Pyroptosis is a new way of programmed cell death, which has the particularity of natural immune inflammation. The inhibition of inflammatory cytokine expression and regulation of pathways related to pyroptosis may be a novel strategy for DN treatment. The aim of this study is to identify pyroptosis-related genes and potential drugs for DN.

METHODS

DN differentially expressed pyroptosis-related genes were identified via bioinformatic analysis Gene Expression Omnibus (GEO) dataset GSE96804. Dataset GSE30528 and GSE142025 were downloaded to verify pyroptosis-related differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression analysis was used to construct a pyroptosis-related gene predictive model. A consensus clustering analysis was performed to identify pyroptosis-related DN subtypes. Subsequently, Gene Set Variation Analysis (GSVA), Gene Ontology (GO) function enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted to explore the differences between DN clusters. A protein-protein interaction (PPI) network was used to select hub genes and DGIdb database was utilized to screen potential therapeutic drugs/compounds targeting hub genes.

RESULTS

A total of 24 differentially expressed pyroptosis-related genes were identified in DN. A 16 gene predictive model was conducted via LASSO regression analysis. According to the expression level of these 16 genes, DN cases were divided into two subtypes, and the subtypes are mainly associated with inflammation, activation of immune response and cell metabolism. In addition, we identified 10 hub genes among these subtypes, and predicted 65 potential DN therapeutics that target key genes.

CONCLUSION

We identified two pyroptosis-related DN clusters and 65 potential therapeutical agents/compounds for DN, which might shed a light on the treatment of DN.

Syringaresinol protects against diabetic nephropathy by inhibiting pyroptosis via NRF2-mediated antioxidant pathway

Diabetic nephropathy (DN) is one of the serious complications of diabetes that has limited treatment options. As a lytic inflammatory cell death, pyroptosis plays an important role in the pathogenesis of DN. Syringaresinol (SYR) possesses anti-inflammatory and antioxidant properties. However, the therapeutic effects and the underlying mechanism of SYR in DN remain unclear. Herein, we showed that SYR treatment ameliorated renal hypertrophy, fibrosis, mesangial expansion, glomerular basement membrane thickening, and podocyte foot process effacement in streptozotocin (STZ)-induced diabetic mice. Mechanistically, SYR prevented the abundance of pyroptosis-related proteins such as NOD-like receptor family pyrin domain containing 3 (NLRP3), cysteinyl aspartate-specific proteinase 1 (Caspase-1), and gasdermin D (GSDMD), and the biosynthesis of inflammatory cytokines interleukin 1β (IL-1β) and interleukin 18 (IL-18). In addition, SYR promoted the nuclear translocation of nuclear factor E2-related factor 2 (NRF2) and enhanced the downstream antioxidant enzymes heme oxygenase 1 (HO-1) and manganese superoxide dismutase (MnSOD), thereby effectively decreasing excess reactive oxygen species (ROS). Most importantly, knockout of NRF2 abolished SYR-mediated renoprotection and anti-pyroptotic activities in NRF2-KO diabetic mice. Collectively, SYR inhibited the NLRP3/Caspase-1/GSDMD pyroptosis pathway by upregulating NRF2 signaling in DN. These findings suggested that SYR may be promising a therapeutic option for DN.

Endoplasmic reticulum stress contributes to pyroptosis through NF-κB/NLRP3 pathway in diabetic nephropathy

AIMS

Diabetic nephropathy (DN) is known as a major microvascular complication in type 1 diabetes. Endoplasmic reticulum (ER) stress and pyroptosis play a critical role in the pathological process of DN, but their mechanism in DN has been litter attention.

MAIN METHODS

Here, we firstly used large mammal beagles as DN model for 120 d to explored the mechanism of endoplasmic reticulum stress-mediated pyroptosis in DN. Meanwhile, 4-Phenylbutytic acid (4-PBA) and BYA 11-7082 were added in the MDCK (Madin-Daby canine kidney) cells by high glucose (HG) treatment. ER stress and pyroptosis related factors expression levels were analyzed by immunohistochemistry, immunofluorescence, western blotting, and quantitative real-time PCR assay.

KEY FINDINGS

We identified that glomeruli atrophy, renal capsules were increased, and renal tubules thickened in diabetes. Masson and PAS staining resulted showed that the collagen fibers and glycogen were accumulated in kidney. Meanwhile, the ER stress and pyroptosis-related factors were significantly activated in vitro. Importantly, 4-PBA significantly inhibited the ER stress, which also alleviated the HG-induced pyroptosis in MDCK cells. Furthermore, BYA 11-7082 could reduce the expression levels of NLRP3 and GSDMD genes and proteins.

SIGNIFICANCE

These data provide evidence for ER stress contributes to pyroptosis through NF-κΒ/ΝLRP3 pathway in canine type 1 diabetic nephropathy.

Moderate Hyperglycemia-Preventive Effect and Mechanism of Action of Periplaneta americana Oligosaccharides in Streptozotocin-Induced Diabetic Mice

Periplaneta americana is a kind of medicinal and edible insect, and its oligosaccharides (PAOS) have been reported to exert anti-inflammatory effects by regulating immunity, reducing oxidative stress, and meliorating gut microbiota. We hypothesized PAOS might benefit experimental diabetes mellitus (DM), an inflammatory disease coordinated by both innate and adaptive immunity. This study aimed to evaluate the effect of PAOS on glycemia and its potential mechanisms. Mice model of diabetes was established, and then the potential effects of PAOS was tested in vivo. Here, we found that PAOS triggered a moderate hyperglycemia-preventive effect on DM mice, showing markedly alleviated symptoms of DM, reduced blood glucose, and meliorated functions of liver and pancreas β cell. Deciphering the underlying mechanism of PAOS-improving diabetes, the results revealed that PAOS downregulated the blood glucose level by activating PI3K/AKT/mTOR and Keap/Nrf2/HO-1 pathways, meanwhile inhibiting TLR4/MAPK/NF-κB, Beclin1/LC3, and NLRP3/caspase1 pathways in vivo. Furthermore, analyses of the microbial community intriguingly exhibited that PAOS promoted the communities of bacteria producing short-chain fatty acids (SCFAs), whereas attenuating lipopolysaccharides (LPS)-producing ones that favored inflammatory tolerance. Collectively, balancing the intestinal bacterial communities by PAOS, which favored anabolism but suppressed inflammatory responses, contributed substantially to the glycemia improvement of PAOS in DM mice. Accordingly, PAOS might function as complementary and alternative medicine for DM.

The role of discoid domain receptor 1 on renal tubular epithelial pyroptosis in diabetic nephropathy

Pyroptosis, a form of cell death associated with inflammation, is known to be involved in diabetic nephropathy (DN), and discoid domain receptor 1 (DDR1), an inflammatory regulatory protein, is reported to be associated with diabetes. However, the mechanism underlying DDR1 regulation and pyroptosis in DN remains unknown. We aimed to investigate the effect of DDR1 on renal tubular epithelial cell pyroptosis and the mechanism underlying DN. In this study, we used high glucose (HG)-treated HK-2 cells and rats with a single intraperitoneal injection of streptozotocin as DN models. Subsequently, the expression of pyroptosis-related proteins (cleaved caspase-1, GSDMD-N, Interleukin-1β [IL-1β], and interleukin-18 [IL-18]), DDR1, phosphorylated NF-κB (p-NF-κB), and NLR family pyrin domain-containing 3 (NLRP3) inflammasomes were determined through Western blotting. IL-1β and IL-18 levels were determined using ELISA. The rate of pyroptosis was assessed by propidium iodide (PI) staining. The results revealed upregulated expression of pyroptosis-related proteins and increased concentration of IL-1β and IL-18, accompanied by DDR1, p-NF-κB, and NLRP3 upregulation in DN rat kidney tissues and HG-treated HK-2 cells. Moreover, DDR1 knockdown in the background of HG treatment resulted in inhibited expression of pyroptosis-related proteins and attenuation of IL-1β and IL-18 production and PI-positive cell frequency via the NF-κB/NLRP3 pathway in HK-2 cells. However, NLRP3 overexpression reversed the effect of DDR1 knockdown on pyroptosis. In conclusion, we demonstrated that DDR1 may be associated with pyroptosis, and DDR1 knockdown inhibited HG-induced renal tubular epithelial cell pyroptosis. The NF-κB/NLRP3 pathway is probably involved in the underlying mechanism of these findings.

NLRP3-mediated pyroptosis in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD), which is characterized by a series of abnormal changes such as glomerulosclerosis, podocyte loss, renal tubular atrophy and excessive deposition of extracellular matrix. Simultaneously, the occurrence of inflammatory reaction can promote the aggravation of DN-induced kidney injury. The most important processes in the canonical inflammasome pathway are inflammasome activation and membrane pore formation mediated by gasdermin family. Converging studies shows that pyroptosis can occur in renal intrinsic cells and participate in the development of DN, and its activation mechanism involves a variety of signaling pathways. Meanwhile, the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome can not only lead to the occurrence of inflammatory response, but also induce pyroptosis. In addition, a number of drugs targeting pyroptosis-associated proteins have been shown to have potential for treating DN. Consequently, the pathogenesis of pyroptosis and several possible activation pathways of NLRP3 inflammasome were reviewed, and the potential drugs used to treat pyroptosis in DN were summarized in this review. Although relevant studies are still not thorough and comprehensive, these findings still have certain reference value for the understanding, treatment and prognosis of DN.

Paeoniflorin directly binds to TNFR1 to regulate podocyte necroptosis in diabetic kidney disease

Necroptosis was elevated in both tubulointerstitial and glomerular renal tissue in patients with diabetic kidney disease (DKD), and was most pronounced on glomerulus in the stage with macroalbuminuria. This study further explored whether paeoniflorin (PF) could affect podocyte necroptosis to protect kidney injure in vivo and in vitro. Our study firstly verified that there are obvious necroptosis-related changes in the glomeruli of DKD through bioinformatics analysis combined with clinicopathological data. STZ-induced mouse diabetes model and high-glucose induced podocyte injury model were used to evaluate the renoprotection, podocyte injury protection and necroptosis regulation of PF in DKD. Subsequently, the target protein-TNFR1 that PF acted on podocytes was found by computer target prediction, and then molecular docking and Surface plasmon resonance (SPR) experiments were performed to verify that PF had the ability to directly bind to TNFR1 protein. Finally, knockdown of TNFR1 on podocytes in vitro verified that PF mainly regulated the programmed necrosis of podocytes induced by high glucose through TNFR1. In conclusion, PF can directly bind and promote the degradation of TNFR1 in podocytes and then regulate the RIPK1/RIPK3 signaling pathway to affect necroptosis, thus preventing podocyte injury in DKD. Thus, TNFR1 may be used as a new potential target to treat DKD.

Schisandrin A from Schisandra chinensis Attenuates Ferroptosis and NLRP3 Inflammasome-Mediated Pyroptosis in Diabetic Nephropathy through Mitochondrial Damage by AdipoR1 Ubiquitination

Schisandra chinensis, as a Chinese functional food, is rich in unsaturated fatty acids, minerals, vitamins, and proteins. Hence, this study was intended to elucidate the effects and biological mechanism of Schisandrin A from Schisandra chinensis in DN. C57BL/6 mice were fed with a high-fat diet and then injected with streptozotocin (STZ). Human renal glomerular endothelial cells were stimulated with 20 mmol/L d-glucose for DN model. Schisandrin A presented acute kidney injury in mice of DN. Schisandrin A reduced oxidative stress and inflammation in model of DN. Schisandrin A reduced high glucose-induced ferroptosis and reactive oxygen species (ROS-)-mediated pyroptosis by mitochondrial damage in model of DN. Schisandrin A directly targeted AdipoR1 protein and reduced LPS+ATP-induced AdipoR1 ubiquitination in vitro model. Schisandrin A activated AdipoR1/AMPK signaling pathway and suppressed TXNIP/NLRP3 signaling pathway in vivo and in vitro model of DN. Conclusively, our study revealed that Schisandrin A from Schisandra chinensis attenuates ferroptosis and NLRP3 inflammasome-mediated pyroptosis in DN by AdipoR1/AMPK-ROS/mitochondrial damage. Schisandrin A is a possible therapeutic option for DN or other diabetes.

ManNAc protects against podocyte pyroptosis via inhibiting mitochondrial damage and ROS/NLRP3 signaling pathway in diabetic kidney injury model

Podocyte pyroptosis is an inflammatory form of cell death associated with Diabetic nephropathy (DN). It is reported that hyposialylated Angiopoietin-like-4 (Angptl4) secreted by glomerular podocytes plays an important role in the formation of proteinuria. Previous study indicated that supplementation of sialic acid precursor N-acetylmannosamine (ManNAc) could inhibit podocyte apoptosis and actin cytoskeleton rearrangement. Nevertheless, whether ManNAc could improve diabetic kidney damage by inhibiting podocyte pyroptosis remains unclear. This study aimed to explore the effect of ManNAc therapy on alleviating diabetic renal injury and podocyte pyroptosis, and its possible mechanism was also figured out. The male 8-week-old C57BL/6 mice were divided into three groups: control group, Streptozocin (STZ)-induced DN group, and ManNAc treated diabetic group. Then, the changes in renal function, renal histopathology, podocyte pyroptosis, reactive oxygen species (ROS), and mitochondrial dysfunction were measured. Herein, we observed that the upregulated expression of Angptl4 was involved in podocyte injury. ManNAc treatment ameliorated podocyte ultrastructure, renal function, and renal histopathology in STZ-induced DN mice. In addition, ManNAc administration attenuated podocyte cell death and suppressed the activation of Nucleotide leukin-rich polypeptide 3 (NLRP3), caspase-1, and interleukin-1β (IL-1β), and the cleavage of gasdermin-D (GSDMD). Moreover, ManNAc inhibited ROS production and restored mitochondrial morphology in vivo and vitro. Further, ManNAc administration significantly alleviated podocyte pyroptosis through inhibiting ROS/NLRP3 signaling pathway. Therefore, these results elucidated that the upregulated expression of Angptl4 was involved in podocyte injury and ManNAc treatment protected against podocyte pyroptosis via inhibiting mitochondrial injury and ROS/NLRP3 signaling pathway in DN mice.