Diabetic nephropathy: diagnosis and treatment

Whole-exome and whole-genome sequencing of 1064 individuals with type 1 diabetes reveals novel genes for diabetic kidney disease

AIMS/HYPOTHESIS

Diabetic kidney disease (DKD) is a severe diabetic complication that affects one third of individuals with type 1 diabetes. Although several genes and common variants have been shown to be associated with DKD, much of the predicted inheritance remains unexplained. Here, we performed next-generation sequencing to assess whether low-frequency variants, extending to a minor allele frequency (MAF) ≤10% (single or aggregated) contribute to the missing heritability in DKD.

METHODS

We performed whole-exome sequencing (WES) of 498 individuals and whole-genome sequencing (WGS) of 599 individuals with type 1 diabetes. After quality control, next-generation sequencing data were available for a total of 1064 individuals, of whom 541 had developed either severe albuminuria or end-stage kidney disease, and 523 had retained normal albumin excretion despite a long duration of type 1 diabetes. Single-variant and gene-aggregate tests for protein-altering variants (PAV) and protein-truncating variants (PTV) were performed separately for WES and WGS data and combined in a meta-analysis. We also performed genome-wide aggregate analyses on genomic windows (sliding window), promoters and enhancers using the WGS dataset.

RESULTS

In the single-variant meta-analysis, no variant reached genome-wide significance, but a suggestively associated common THAP7 rs369250 variant (p=1.50 × 10-5, MAF=49%) was replicated in the FinnGen general population genome-wide association study (GWAS) data for chronic kidney disease and DKD phenotypes. The gene-aggregate meta-analysis provided suggestive evidence (p<4.0 × 10-4) at four genes for DKD, of which NAT16 (MAFPAV≤10%) and LTA (also known as TNFβ, MAFPAV≤5%) are replicated in the FinnGen general population GWAS data. The LTA rs2229092 C allele was associated with significantly lower TNFR1, TNFR2 and TNFR3 serum levels in a subset of FinnDiane participants. Of the intergenic regions suggestively associated with DKD, the enhancer on chromosome 18q12.3 (p=3.94 × 10-5, MAFvariants≤5%) showed interaction with the METTL4 gene; the lead variant was replicated, and predicted to alter binding of the MafB transcription factor.

CONCLUSIONS/INTERPRETATION

Our sequencing-based meta-analysis revealed multiple genes, variants and regulatory regions that were suggestively associated with DKD. However, as no variant or gene reached genome-wide significance, further studies are needed to validate the findings.

Ramulus Mori (Sangzhi) Alkaloids Alleviate Diabetic Nephropathy through Improving Gut Microbiota Disorder

Diabetic nephropathy (DN), one of the leading causes of end-stage kidney failure worldwide, is closely associated with high mortality in diabetic patients. However, therapeutic drugs for DN are still lacking. Ramulus Mori alkaloids (SZ-A), an effective component of alkaloids extracted from Ramulus Mori, have been found to improve glucose and lipid metabolism to mitigate diabetes and obesity; however, few studies have focused on their effects on DN progression. Thus, we investigated the protective role of SZ-A on DN through 16S rRNA sequencing, non-targeted metabolomics, and fecal microbiota transplantation (FMT) experiments. To address our hypothesis, we established the DN mouse model by combining a high-fat diet (HFD) with streptozotocin (STZ) injection. Herein, we demonstrated that SZ-A supplementation was recalcitrant to renal injury in DN mice, improving glomerular morphology, reversing the blood biochemistry parameters, and ameliorating podocyte injury. Importantly, the composition of the gut microbiota altered after SZ-A treatment, especially with the elevated abundance of Dubosiella and the increased level of serum pentadecanoic acid. FMT experiments further revealed that the gut microbiota exerted critical effects in mediating the beneficial roles of SZ-A. In vitro experiments proved that pentadecanoic acid administration improved podocyte apoptosis induced by AGEs. Taken together, SZ-A play a renoprotective role, possibly through regulating the gut microbiota and promoting pentadecanoic acid production. Our current study lends support to more extensive clinical applications of SZ-A.

Quantifying Protein Acetylation in Diabetic Nephropathy from Formalin-Fixed Paraffin-Embedded Tissue

PURPOSE

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and a leading cause of chronic kidney disease and end-stage renal disease. One potential mechanism underlying cellular dysfunction contributing to kidney disease is aberrant protein post-translational modifications. Lysine acetylation is associated with cellular metabolic flux and is thought to be altered in patients with diabetes and dysfunctional renal metabolism.

EXPERIMENTAL DESIGN

A novel extraction and LC-MS/MS approach was adapted to quantify sites of lysine acetylation from formalin-fixed paraffin-embedded (FFPE) kidney tissue and from patients with DKD and non-diabetic donors (n = 5 and n = 7, respectively).

RESULTS

Analysis of FFPE tissues identified 840 total proteins, with 225 of those significantly changing in patients with DKD. Acetylomic analysis quantified 289 acetylated peptides, with 69 of those significantly changing. Pathways impacted in DKD patients revealed numerous metabolic pathways, specifically mitochondrial function, oxidative phosphorylation, and sirtuin signaling. Differential protein acetylation in DKD patients impacted sirtuin signaling, valine, leucine, and isoleucine degradation, lactate metabolism, oxidative phosphorylation, and ketogenesis.

CONCLUSIONS AND CLINICAL RELEVANCE

A quantitative acetylomics platform was developed for protein biomarker discovery in formalin-fixed and paraffin-embedded biopsies of kidney transplant patients suffering from DKD.

Zn(II)-curcumin prevents cadmium-aggravated diabetic nephropathy by regulating gut microbiota and zinc homeostasis

Background: Diabetic nephropathy (DN) is known as the most common complication of diabetes, resulting from a complex inheritance-environment interaction without effective clinical treatments. Herein, we revealed the protective effects and mechanisms of Zn(II)-curcumin, a curcumin derivative, against streptozotocin-induced DN in rats in the presence or absence of cadmium exposure. Methods: The present study focused on investigating the therapy of Zn(II)-curcumin against cadmium-aggravated DN by regulating gut microbiota, metabolism, inflammation and zinc homeostasis based on pathological changes, TLR4/NF-κB signaling pathway, inductively coupled plasma-mass spectrometry (ICP-MS), 16S rRNA gene sequencing and gas chromatography-mass spectrometer (GC-MS). Results: We found Zn(II)-curcumin significantly mitigated the cadmium-aggravated phenotypes of diabetic nephropathy, as indicated by the remission of renal dysfunction, pathological changes, inflammation and zinc dyshomeostasis in streptozotocin-treated rats exposed to cadmium. Administration of Zn(II)-curcumin significantly alleviated the dysbiosis of gut microbiota and the changes of serum metabolite profiles in rats treated with streptozotocin in combination with cadmium. Notably, fecal microbial transplantation identified the ability of Zn(II)-curcumin to regulate renal function, inflammation and zinc homeostasis was partly dependent on the gut microbiota. Conclusion: These findings revealed that Zn(II)-curcumin alleviated cadmium-aggravated diabetic nephropathy by reshaping the gut microbiota and zinc homeostasis, which provided unique insights into the mechanisms of the treatment and prevention of diabetic nephropathy.

Beyond drug discovery: Exploring the physiological and methodological dimensions of zebrafish in diabetes research

Diabetes mellitus is a chronic disease that is now considered a global epidemic. Chronic diabetes conditions include type 1 and type 2 diabetes, both of which are normally irreversible. As a result of long-term uncontrolled high levels of glucose, diabetes can progress to hyperglycaemic pathologies, such as cardiovascular diseases, retinopathy, nephropathy and neuropathy, among many other complications. The complete mechanism underlying diabetes remains unclear due to its complexity. In this scenario, zebrafish (Danio rerio) have arisen as a versatile and promising animal model due to their good reproducibility, simplicity, and time- and cost-effectiveness. The Zebrafish model allows us to make progress in the investigation and comprehension of the root cause of diabetes, which in turn would aid in the development of pharmacological and surgical approaches for its management. The current review provides valuable reference information on zebrafish models, from the first zebrafish diabetes models using genetic, disease induction and chemical approaches, to the newest ones that further allow for drug screening and testing. This review aims to update our knowledge related to diabetes mellitus by gathering the most authoritative studies on zebrafish as a chemical, dietary and insulin induction, and genetic model for diabetes research.

Identification and functional analysis of the hub Ferroptosis-Related gene EZH2 in diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is a common microvascular complication and one of the main causes of death in diabetes. Ferroptosis, an iron-dependent mode of cell death characterized by lipid ROS accumulation, was found to be associated with a number of diseases and has great potential for kidney diseases. It has great value to identify potential ferroptosis-related genes and their biological mechanisms in DKD.

METHODS

We obtained the GSE30122 dataset from Gene Expression Omnibus (GEO) database and ferroptosis-related genes from the Ferrdb database. After differential expression analysis, and three machine learning algorithms, the hub ferroptosis-related gene EZH2 was identified. In order to investigate the function of EZH2, Gene Set Enrichment Analysis (GSEA), Gene Set Variation Analysis (GSVA) and single cell analysis were conducted. The expression of EZH2 was validated in DKD patients, HK-2 cell models and DKD mouse models. EZH2 knockdown HK-2 cells and HK-2 cells treated with GSK126 were performed to verify whether EZH2 affected ferroptosis in DKD. CHIP assay was used to detect whether EZH2 regulated ferroptosis by suppressing SLC7A11. Molecular docking was performed to explore EZH2 and four traditional Chinese medicine (Sennoside A, Berberine, Umbelliferone, Platycodin D) related to ferroptosis in DKD treatment.

RESULTS

According to the GSE30122 dataset in GEO and ferroptosis-related genes from the Ferrb database, we obtained the hub ferroptosis-related gene EZH2 in DKD via diversified machine learning methods. The increasing of EZH2 expression was shown in single cell analysis, DKD patients, DKD mouse models and high glucose induced DKD cell models. Further study showed that EZH2 knockdown and inhibition can alleviate HG-induced ferroptosis in vitro. CHIP assay showed EZH2-mediated epigenetic silencing regulated the expression of SLC7A11. Molecular docking results showed that EZH2 had strong binding stability with Sennoside A, Berberine, Umbelliferone, and Platycodin D.

CONCLUSION

Overall, our data shouwed that histone H3K27 methyltransferase EZH2 could regulate the renal tubular epithelial cell ferroptosis by suppressing SLC7A11 in DKD, which may serve as a credible reliable indicator for diagnosing DKD and a potential target for treatment.

Arsenic aggravates the progression of diabetic nephropathy through miRNA-mRNA-autophagy axis

Environmental factors play an important role in the progression of diabetic nephropathy (DN), and previous study has shown that arsenic exposure can promote kidney damage in DN rats, however there is no relevant mechanism study so far. In this study, an arsenic-exposed (10 mg/L and 25 mg/L) DN mouse model was established through drinking water for 14 weeks. The results showed that 25 mg/L arsenic exposure increased the renal fibrosis in DN mice significantly, and urinary mAlb level increased with the increasing of arsenic exposure level. Transcriptome sequencing showed that autophagy-related pathways were significantly activated under the exposure dose of 25 mg/L, and levels of Beclin1 and p-ATG16L1/ATG16L1 were significantly higher in the 25 mg/L arsenic group compared to the control group. Silico analysis predicted the microRNAs those could regulate the hub genes of Mapk1, Rhoa and Cdc42, and dual-luciferase gene reporter assay was used to verify the targeted binding between these mRNAs and microRNAs. Our results suggested that high arsenic exposure could aggravate the progression of DN by altering autophagy, the miRNA-mRNA axles of let-7a-1-3p, let-7b-3p, let-7f-1-3p, miR-98-3p/Cdc42, Mapk1, Rhoa, could be considered promising targets to explore the mechanisms and therapeutic measures of DN after exposure to high levels of arsenic.

Ultrasensitive CCL2 Detection in Urine for Diabetic Nephropathy Diagnosis Using a WS2-Based Plasmonic Biosensor

The accurate diagnosis of diabetic nephropathy relies on achieving ultrasensitive biosensing for biomarker detection. However, existing biosensors face challenges such as poor sensitivity, complexity, time-consuming procedures, and high assay costs. To address these limitations, we report a WS2-based plasmonic biosensor for the ultrasensitive detection of biomarker candidates in clinical human urine samples associated with diabetic nephropathy. Leveraging plasmonic-based electrochemical impedance microscopy (P-EIM) imaging, we observed a remarkable charge sensitivity in monolayer WS2 single crystals. Our biosensor exhibits an exceptionally low detection limit (0.201 ag/mL) and remarkable selectivity in detecting CC chemokine ligand 2 (CCL2) protein biomarkers, outperforming conventional techniques such as ELISA. This work represents a breakthrough in traditional protein sensors, providing a direction and materials foundation for developing ultrasensitive sensors tailored to clinical applications for biomarker sensing.

Promoting mitochondrial dynamics by inhibiting the PINK1-PRKN pathway to relieve diabetic nephropathy

Diabetes is a metabolic disorder characterized by high blood glucose levels and is a leading cause of kidney disease. Diabetic nephropathy has been attributed to dysfunctional mitochondria. However, many questions remain about the exact mechanism. The structure, function and molecular pathways are highly conserved between mammalian podocytes and Drosophila nephrocytes; therefore, we used flies on a high-sucrose diet to model type 2 diabetic nephropathy. The nephrocytes from flies on a high-sucrose diet showed a significant functional decline and decreased cell size, associated with a shortened lifespan. Structurally, the nephrocyte filtration structure, known as the slit diaphragm, was disorganized. At the cellular level, we found altered mitochondrial dynamics and dysfunctional mitochondria. Regulating mitochondrial dynamics by either genetic modification of the Pink1-Park (mammalian PINK1-PRKN) pathway or treatment with BGP-15, mitigated the mitochondrial defects and nephrocyte functional decline. These findings support a role for Pink1-Park-mediated mitophagy and associated control of mitochondrial dynamics in diabetic nephropathy, and demonstrate that targeting this pathway might provide therapeutic benefits for type 2 diabetic nephropathy.

Biomarkers and signaling pathways of diabetic nephropathy and peripheral neuropathy: possible therapeutic intervention of rutin and quercetin

Diabetic nephropathy and peripheral neuropathy are the two main complications of chronic diabetes that contribute to high morbidity and mortality. These conditions are characterized by the dysregulation of multiple molecular signaling pathways and the presence of specific biomarkers such as inflammatory cytokines, indicators of oxidative stress, and components of the renin-angiotensin system. In this review, we systematically collected and collated the relevant information from MEDLINE, EMBASE, ELSEVIER, PUBMED, GOOGLE, WEB OF SCIENCE, and SCOPUS databases. This review was conceived with primary objective of revealing the functions of these biomarkers and signaling pathways in the initiation and progression of diabetic nephropathy and peripheral neuropathy. We also highlighted the potential therapeutic effectiveness of rutin and quercetin, two plant-derived flavonoids known for their antioxidant and anti-inflammatory properties. The findings of our study demonstrated that both flavonoids can regulate important disease-promoting systems, such as inflammation, oxidative stress, and dysregulation of the renin-angiotensin system. Importantly, rutin and quercetin have shown protective benefits against nephropathy and neuropathy in diabetic animal models, suggesting them as potential therapeutic agents. These findings provide a solid foundation for further comprehensive investigations and clinical trials to evaluate the potential of rutin and quercetin in the management of diabetic nephropathy and peripheral neuropathy. This may contribute to the development of more efficient and comprehensive treatment approaches for diabetes-associated complications.

Hyperglycemia - A culprit of podocyte pathology in the context of glycogen metabolism

Prolonged disruption in the balance of glucose can result in metabolic disorders. The kidneys play a significant role in regulating blood glucose levels. However, when exposed to chronic hyperglycemia, the kidneys' ability to handle glucose metabolism may be impaired, leading to an accumulation of glycogen. Earlier studies have shown that there can be a significant increase in glucose storage in the form of glycogen in the kidneys in diabetes. Podocytes play a crucial role in maintaining the integrity of filtration barrier. In diabetes, exposure to elevated glucose levels can lead to significant metabolic and structural changes in podocytes, contributing to kidney damage and the development of diabetic kidney disease. The accumulation of glycogen in podocytes is not a well-established phenomenon. However, a recent study has demonstrated the presence of glycogen granules in podocytes. This review delves into the intricate connections between hyperglycemia and glycogen metabolism within the context of the kidney, with special emphasis on podocytes. The aberrant storage of glycogen has the potential to detrimentally impact podocyte functionality and perturb their structural integrity. This review provides a comprehensive analysis of the alterations in cellular signaling pathways that may potentially lead to glycogen overproduction in podocytes.

Dapagliflozin improves podocytes injury in diabetic nephropathy via regulating cholesterol balance through KLF5 targeting the ABCA1 signalling pathway

Diabetic nephropathy (DN), one of the more prevalent microvascular complications in patients diagnosed with diabetes mellitus, is attributed as the main cause of end-stage renal disease (ESRD). Lipotoxicity in podocytes caused by hyperglycemia has been recognised as a significant pathology change, resulting in the deterioration of the glomerular filtration barrier. Research has demonstrated how dapagliflozin, a kind of SGLT2i, exhibits a multifaceted and powerful protective effect in DN, entirely independent of the hypoglycemic effect, with the specific mechanism verified. In this present study, we found that dapagliflozin has the potential to alleviate apoptosis and restore cytoskeleton triggered by high glucose (HG) in vivo and in vitro. We also discovered that dapagliflozin could mitigate podocyte cholesterol accumulation by restoring the expression of ABCA1, which is the key pathway for cholesterol outflows. This research also mechanistically demonstrates that the protective effect of dapagliflozin can be mediated by KLF-5, which is the upstream transcription factor of ABCA1. Taken together, our data suggest that dapagliflozin offers significant potential in alleviating podocyte injury and cholesterol accumulation triggered by high glucose. In terms of the mechanism, we herein reveal that dapagliflozin could accelerate cholesterol efflux by restoring the expression of ABCA1, which is directly regulated by KLF-5.

Discovery of PRDM16-Mediated TRPA1 Induction as the Mechanism for Low Tubulo-Interstitial Fibrosis in Diabetic Kidney Disease

The pathogenesis of Diabetic kidney disease(DKD) involves pathological changes in both tubulo-interstitium and the glomerulus. Surprisingly, tubulo-interstitial fibrosis (TIF), does not develop significantly until the late stage of DKD. Here, it is demonstrated that PR domain-containing 16 (PRDM16) is a key to the low level of TIF in DKD. In the experiments, PRDM16 is upregulated in high glucose-treated renal tubular cells, DKD mouse kidneys, and renal biopsy of human DKD patients via activation of NF-κB signal pathway. High glucose-induced expression of fibrotic proteins in renal tubular cells is suppressed by PRDM16. Mechanistically, PRDM16 bound to the promotor region of Transient receptor potential ankyrin 1 (TRPA1) to transactivate its expression and then suppressed MAPK (P38, ERK1/2) activation and downstream expression of TGF-β1. Knockout of PRDM16 from kidney proximal tubules in mice blocked TRPA1 expression and enhanced MAPK activation, TGF-β1 production, TIF development, and DKD progression, whereas knock-in of PRDM16 has opposite effects. In addition, overexpression of PRDM16 or its induction by formononetin ameliorated renal dysfunction and fibrosis in db/db diabetic mice. Finally, the above finding are detected in renal biopsies of DKD patients. Together, these results unveil PRDM16/TRPA1 as the mechanism responsible for the low level of TIF in the early stage of DKD by suppressing and TGF-β1 expression.

N6-methyladenosine RNA methylation in diabetic kidney disease

Diabetic kidney disease (DKD) is a major microvascular complication of diabetes, and hyperglycemic memory associated with diabetes carries the risk of disease occurrence, even after the termination of blood glucose injury. The existence of hyperglycemic memory supports the concept of an epigenetic mechanism involving n6-methyladenosine (m6A) modification. Several studies have shown that m6A plays a key role in the pathogenesis of DKD. This review addresses the role and mechanism of m6A RNA modification in the progression of DKD, including the regulatory role of m6A modification in pathological processes, such as inflammation, oxidative stress, fibrosis, and non-coding (nc) RNA. This reveals the importance of m6A in the occurrence and development of DKD, suggesting that m6A may play a role in hyperglycemic memory phenomenon. This review also discusses how some gray areas, such as m6A modified multiple enzymes, interact to affect the development of DKD and provides countermeasures. In conclusion, this review enhances our understanding of DKD from the perspective of m6A modifications and provides new targets for future therapeutic strategies. In addition, the insights discussed here support the existence of hyperglycemic memory effects in DKD, which may have far-reaching implications for the development of novel treatments. We hypothesize that m6A RNA modification, as a key factor regulating the development of DKD, provides a new perspective for the in-depth exploration of DKD and provides a novel option for the clinical management of patients with DKD.

The Effects of Apigenin in the Treatment of Diabetic Nephropathy: A Systematic Review of Non-clinical Studies

PURPOSE

Diabetes is one of the important and growing diseases in the world. Among the most common diabetic complications are renal adverse effects. The use of apigenin may prevent the development and progression of diabetes-related injuries. The current study aims to review the effects of apigenin in the treatment of diabetic nephropathy.

METHODS

In this review, a systematic search was performed based on PRISMA guidelines for obtaining all relevant studies on "the effects of apigenin against diabetic nephropathy" in various electronic databases up to September 2022. Ninety-one articles were obtained and screened in accordance with the predefined inclusion and exclusion criteria. Seven eligible articles were finally included in this review.

RESULTS

The experimental findings revealed that hyperglycemia led to the decreased cell viability of kidney cells and body weight loss and an increased kidney weight of rats; however, apigenin administration had a reverse effect on these evaluated parameters. It was also found that hyperglycemia could induce alterations in the biochemical and renal function-related parameters as well as histopathological injuries in kidney cells or tissue; in contrast, the apigenin administration could ameliorate the hyperglycemia-induced renal adverse effects.

CONCLUSION

The results indicated that the use of apigenin could mitigate diabetes-induced renal adverse effects, mainly through its antioxidant, anti-apoptotic, and anti-inflammatory activities. Since the findings of this study are based on experimental studies, suggesting the use of apigenin (as a nephroprotective agent) against diabetic nephropathy requires further clinical studies.

Human placenta-derived mesenchymal stem cells ameliorate diabetic kidney disease by modulating the T helper 17 cell/ regulatory T-cell balance through the programmed death 1 / programmed death-ligand 1 pathway

AIM

To investigate the therapeutic effects and immunomodulatory mechanisms of human placenta-derived mesenchymal stem cells (PMSCs) in diabetic kidney disease (DKD).

METHODS

Streptozotocin-induced DKD rats were administered an equivalent volume of saline or PMSCs (1 × 106 in 2 mL phosphate-buffered saline per rat) for 3 weeks. Eight weeks after treatment, we examined the biochemical parameters in the blood and urine, the ratio of T helper 17 cells (Th17) and regulatory T cells (Treg) in the blood, cytokine levels in the kidney and blood, and renal histopathological changes. In addition, we performed PMSC tracing and renal transcriptomic analyses using RNA-sequencing. Finally, we determined whether PMSCs modulated the Th17/Treg balance by upregulating programmed death 1 (PD-1) in vitro.

RESULTS

The PMSCs significantly improved renal function, which was assessed by serum creatinine levels, urea nitrogen, cystatin C levels, urinary albumin-creatinine ratio, and the kidney index. Further, PMSCs alleviated pathological changes, including tubular vacuolar degeneration, mesangial matrix expansion, and glomerular filtration barrier injury. In the DKD rats in our study, PMSCs were mainly recruited to immune organs, rather than to the kidney or pancreas. PMSCs markedly promoted the Th17/Treg balance and reduced the levels of pro-inflammatory cytokines (interleukin [IL]-17A and IL-1β) in the kidney and blood of DKD rats. In vitro experiments showed that PMSCs significantly reduced the proportion of Th17 cells and increased the proportion of Treg cells by upregulating PD-1 in a cell-cell contact manner and downregulating programmed death-ligand 1 (PD-L1) expression in PMSCs, which reversed the Th17/Treg balance.

CONCLUSION

We found that PMSCs improved renal function and pathological damage in DKD rats and modulated Th17/Treg balance through the PD-1/PD-L1 pathway. These findings provide a novel mechanism and basis for the clinical use of PMSCs in the treatment of DKD.

Stem cells as a regenerative medicine approach in treatment of microvascular diabetic complications

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high blood glucose and is associated with high morbidity and mortality among the diabetic population. Uncontrolled chronic hyperglycaemia causes increased formation and accumulation of different oxidative and nitrosative stress markers, resulting in microvascular and macrovascular complications, which might seriously affect the quality of a patient's life. Conventional treatment strategies are confined to controlling blood glucose by regulating the insulin level and are not involved in attenuating the life-threatening complications of diabetes mellitus. Thus, there is an unmet need to develop a viable treatment strategy that could target the multi-etiological factors involved in the pathogenesis of diabetic complications. Stem cell therapy, a regenerative medicine approach, has been investigated in diabetic complications owing to their unique characteristic features of self-renewal, multilineage differentiation and regeneration potential. The present review is focused on potential therapeutic applications of stem cells in the treatment of microvascular diabetic complications such as nephropathy, retinopathy, and polyneuropathy.

Hsa_circ_0003928 regulates the progression of diabetic nephropathy through miR-136-5p/PAQR3 axis

BACKGROUND

Diabetic nephropathy (DN) is one of the complications of diabetes and has a high mortality, but its specific pathogenesis is not clear. In recent years, researches on the mechanism of circRNAs in DN have been proved a lot, whereas the functional mechanism of circ_0003928 in DN remains open and it must be investigated to value its important role in DN prevention.

METHODS

HK-2 cells were treated with high glucose (HG), normal glucose (NG) or Mannitol. Cell counting kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were performed to detect cell proliferation. Enzyme-linked immunosorbent assay (ELISA) was applied to analyze malondialdehyde (MDA) and superoxide dismutase 1 (SOD) levels. Flow cytometry and western blot were preformed to measure cell apoptosis. Real-time quantitative PCR (RT-qPCR) was used to test the levels of circ_0003928, miR-136-5p and progestin and adipoQ receptor family member 3 (PAQR3) mRNA. Western blot was executed to detect Bcl2 associated X (Bax), B cell leukemia/lymphoma 2 (Bcl2), smooth muscle (αSMA), apolipoprotein (C-IV) and PAQR3 levels. Luciferase reporter assay and RNA pull-down assay were used to analyze the target relationship between miR-136-5p and circ_0003928 or PAQR3.

RESULTS

Circ_0003928 and PAQR3 expression were up-regulated, whereas miR-136-5p was decreased in DN serum and HG-induced HK-2 cells. Circ_0003928 knockdown promoted cell proliferation, and inhibit cell apoptosis, oxidative stress, and fibrosis in HK-2 cells under HG condition. MiR-136-5p silencing overturned the protective effects of si-circ_0003928 on HG-induced HK-2 cells. MiR-136-5p was targeted by circ_0003928 and directly targeted PAQR3. Overexpression of PAQR3 counteracted the inhibitory functions of circ_0003928 knockdown or miR-136-5p overexpression on HG-induced HK-2 cell injury.

CONCLUSION

Circ_0003928 acted as a sponge of miR-136-5p to up-regulating PAQR3 expression, and then regulate the proliferation, oxidative stress, fibrosis and apoptosis in HG-induced HK-2 cells.

The role of autophagy in the treatment of type II diabetes and its complications: a review

Type II diabetes mellitus (T2DM) is a chronic metabolic disease characterized by prolonged hyperglycemia and insulin resistance (IR). Its incidence is increasing annually, posing a significant threat to human life and health. Consequently, there is an urgent requirement to discover effective drugs and investigate the pathogenesis of T2DM. Autophagy plays a crucial role in maintaining normal islet structure. However, in a state of high glucose, autophagy is inhibited, resulting in impaired islet function, insulin resistance, and complications. Studies have shown that modulating autophagy through activation or inhibition can have a positive impact on the treatment of T2DM and its complications. However, it is important to note that the specific regulatory mechanisms vary depending on the target organ. This review explores the role of autophagy in the pathogenesis of T2DM, taking into account both genetic and external factors. It also provides a summary of reported chemical drugs and traditional Chinese medicine that target the autophagic pathway for the treatment of T2DM and its complications.

Association of S19W polymorphism in APOA5 gene and serum lipid levels in patients with type 2 diabetic nephropathy

OBJECTIVES

Type 2 diabetic Mellitus (T2DM) is the most common systemic and endocrine disease in humans, and diabetic nephropathy is one of the most serious complications of this disorder. The polymorphisms in the apolipoprotein A5 (ApoA5) gene are strongly related to hypertriglyceridemia and are considered a predisposing factor for diabetic nephropathy. The current study proposed to examine the association of APOA5-S19W polymorphism with serum lipids levels in patients with type 2 diabetic nephropathy in Mazandaran province.

METHODS

This case-control study was designed to determine the association of APOA5-S19W polymorphism with plasma lipid profile in 161 T2DM patients with nephropathy (DN+), without nephropathy (DN-), and in 58 healthy individuals. Lipid profile values were measured using Pars Azmoun commercial kits. S19W variant, one of the polymorphisms of the APOA5 gene, was determined by PCR-restriction fragment length polymorphism (PCR-RFLP) and Taq1 restriction enzyme.

RESULTS

In comparison between the three groups, DN+ had a higher mean TG than DN- and the control group (p<0.001). The incidence of the G allele in DN+ was not significant compared to groups of DN-. Comparing the relationship between the mean of biochemical variables with CC and CG genotypes showed that the mean level of TG in people with CC genotype was increased compared to people with CG genotype in diabetic patients. However, this increase was not significant (p=0.19).

CONCLUSIONS

There was no association between SNP APOA5 S19W and serum lipids in diabetic patients with and without nephropathy.

Iron Chelator Deferoxamine Alleviates Progression of Diabetic Nephropathy by Relieving Inflammation and Fibrosis in Rats

Diabetic nephropathy (DN) is one of the most devastating diabetic microvascular complications. It has previously been observed that iron metabolism levels are abnormal in diabetic patients. However, the mechanism by which iron metabolism levels affect DN is poorly understood. This study was designed to evaluate the role of iron-chelator deferoxamine (DFO) in the improvement of DN. Here, we established a DN rat model induced by diets high in carbohydrates and fat and streptozotocin (STZ) injection. Our data demonstrated that DFO treatment for three weeks greatly attenuated renal dysfunction as evidenced by decreased levels of urinary albumin, blood urea nitrogen, and serum creatinine, which were elevated in DN rats. Histopathological observations showed that DFO treatment improved the renal structures of DN rats and preserved podocyte integrity by preventing the decrease of transcripts of nephrin and podocin. In addition, DFO treatment reduced the overexpression of fibronectin 1, collagen I, IL-1β, NF-κB, and MCP-1 in DN rats, as well as inflammatory cell infiltrates and collagenous fibrosis. Taken together, our findings unveiled that iron chelation via DFO injection had a protective impact on DN by alleviating inflammation and fibrosis, and that it could be a potential therapeutic strategy for DN.

Emodin attenuates diabetic kidney disease by inhibiting ferroptosis via upregulating Nrf2 expression

Diabetic kidney disease (DKD) poses a threat to people's health. The current treatments only provide partial relief of symptoms. Therefore, seeking a promising therapeutic medication for the prevention and control on DKD will benefit patients. Recently, a novel iron-dependent and non-apoptotic regulated mode of cell death, termed as ferroptosis, is expected to offer us a novel insight into the mechanism of DKD. We conducted experiments to investigate the role of ferroptosis in the development of DKD. Iron accumulation, weakened antioxidant capacity and ROS overproduction were observed in the renal tissues of STZ-induced diabetic rats. A persistent high glucose condition contributed to down regulated levels of Glutathione Peroxidase 4 (GPX4) and Solute Carrier Family 7 Member 11 (SLC7A11) which marked the occurrence of ferroptosis. Treatment of Emodin in DKD models could significantly attenuated these changes and reduced renal injury. Besides, NFE2-related factor 2 (Nrf2), an important antioxidant regulator, was inhibited in both in vivo and in vitro assay, which contributes to Reactive Oxygen Species (ROS) generation that further promoted the expression of ferroptosis related protein. These unwanted effects were offset by the intervention of Emodin. The specific Nrf2 knock out enhanced cell's sensitivity to ferroptosis by being exposed to high glucose culture, which was improved by treatment of Emodin via restoring activity of Nrf2. In conclusion, our research demonstrated that Emodin exerted renal protection against DKD via inhibiting ferroptosis and restoring Nrf2 mediated antioxidant capacity, which could be employed as a novel therapeutic medication against DKD.

The cardio-renal-metabolic connection: a review of the evidence

Type 2 diabetes (T2D), cardiovascular disease (CVD) and chronic kidney disease (CKD), are recognized among the most disruptive public health issues of the current century. A large body of evidence from epidemiological and clinical research supports the existence of a strong interconnection between these conditions, such that the unifying term cardio-metabolic-renal (CMR) disease has been defined. This coexistence has remarkable epidemiological, pathophysiologic, and prognostic implications. The mechanisms of hyperglycemia-induced damage to the cardio-renal system are well validated, as are those that tie cardiac and renal disease together. Yet, it remains controversial how and to what extent CVD and CKD can promote metabolic dysregulation. The aim of this review is to recapitulate the epidemiology of the CMR connections; to discuss the well-established, as well as the putative and emerging mechanisms implicated in the interplay among these three entities; and to provide a pathophysiological background for an integrated therapeutic intervention aiming at interrupting this vicious crosstalks.

Integrated multiple-microarray analysis and mendelian randomization to identify novel targets involved in diabetic nephropathy

Background

Diabetic nephropathy (DN), which is the main cause of renal failure in end-stage renal disease, is becoming a common chronic renal disease worldwide. Mendelian randomization (MR) is a genetic tool that is widely used to minimize confounding and reverse causation when identifying the causal effects of complex traits. In this study, we conducted an integrated multiple microarray analysis and large-scale plasma proteome MR analysis to identify candidate biomarkers and evaluate the causal effects of prospective therapeutic targets in DN.

Methods

Five DN gene expression datasets were selected from the Gene Expression Omnibus. The robust rank aggregation (RRA) method was used to integrate differentially expressed genes (DEGs) of glomerular samples between patients with DN and controls, followed by functional enrichment analysis. Protein quantitative trait loci were incorporated from seven different proteomic genome-wide association studies, and genetic association data on DN were obtained from FinnGen (3676 cases and 283,456 controls) for two-sample MR analysis. External validation and clinical correlation were also conducted.

Results

A total of 82 DEGs (53 upregulated and 29 downregulated) were identified through RRA integrated analysis. The enriched Gene Ontology annotations and Kyoto Encyclopedia of Genes and Genomes pathways of the DEGs were significantly enriched in neutrophil degranulation, neutrophil activation, proteoglycan binding, collagen binding, secretory granule lumen, gluconeogenesis, tricarboxylic acid cycle, and pentose phosphate pathways. MR analysis revealed that the genetically predicted levels of MHC class I polypeptide-related sequence B (MICB), granzyme A (GZMA), cathepsin S (CTSS), chloride intracellular channel protein 5, and ficolin-1 (FCN1) were causally associated with DN risk. Expression validation and clinical correlation analysis showed that MICB, GZMA, FCN1, and insulin-like growth factor 1 may participate in the development of DN, and carbonic anhydrase 2 and lipoprotein lipase may play protective roles in patients with DN.

Conclusion

Our integrated analysis identified novel biomarkers, including MICB and GZMA, which may help further understand the complicated mechanisms of DN and identify new target pathways for intervention.

Single-cell RNA-seq with spatial transcriptomics to create an atlas of human diabetic kidney disease

Diabetic kidney disease (DKD) develops in ~40% of patients with diabetes and is the leading cause of chronic kidney disease worldwide. We used single-cell RNA-sequencing and spatial transcriptomic analyses of kidney specimens from patients with DKD. Unsupervised clustering revealed distinct cell clusters, including epithelial cells and fibroblasts. We also identified differentially expressed genes (DEGs) and assessed enrichment, and cell-cell interactions. Specific enrichment of DKD was evident in venous endothelial cells (VECs) and fibroblasts with elevated CCL19 expression. The DEGs in most kidney parenchymal cells in DKD were primarily enriched in inflammatory signaling pathways. Intercellular crosstalk revealed that most cell interactions in DKD are associated with chemokines. Spatial transcriptomics revealed that VECs co-localized with fibroblasts, with most immune cells being enriched in areas of renal fibrosis. These results provided insight into the cell populations, intercellular interactions, and signaling pathways underlying the pathogenesis and potential targets for treating DKD.

Germacrone protects renal tubular cells against ferroptotic death and ROS release by re-activating mitophagy in diabetic nephropathy

Mitophagy is a critical intracellular event during the progression of diabetic nephropathy (DN). Our previous study demonstrated that germacrone has anti-ferroptotic properties and is a potential therapeutic agent for DN. However, the relationship among germacrone, mitophagy, and ferroptosis in DN remains unclear. In this study, the data confirmed that germacrone ameliorates high glucose (HG)-induced ferroptosis through limiting Fe (2+) content and lipid reactive oxygen species (ROS) accumulation in human kidney 2 (HK-2) cells. Germacrone reversed HG-mediated inhibition of mitophagy. Mitophagy inhibition and anabatic mitochondrial ROS abrogate germacrone-mediated protective effects against ferroptotic death, resulting in the subsequent activation of mitochondrial DNA (mtDNA) cytosolic leakage-induced stimulator of interferon response CGAMP interactor 1 (STING) signaling. The combination of a mitochondrial ROS antagonist and germacrone acts synergistically to alleviate the ferroptotic death of tubular cells and DN symptoms. In summary, germacrone ameliorated ferroptotic death in tubular cells by reactivating mitophagy and inhibiting mtDNA-STING signaling in DN. This study provides a novel insight into germacrone-mediated protection against DN progression and further confirms that antioxidant pharmacological strategies facilitate the treatment of DN.

Effect of S-allylcysteine against diabetic nephropathy via inhibition of MEK1/2-ERK1/2-RSK2 signalling pathway in streptozotocin-nicotinamide-induced diabetic rats

OBJECTIVE

In the current study, we evaluated the ameliorative effect of S-allylcysteine (SAC) against streptozotocin (STZ)-nicotinamide (NAD)-induced diabetic nephropathy (DN) in rats and also an attempt was made to establish the molecular mechanism of SAC.

METHODS

DN rats were orally supplemented with SAC (150 mg/kg body weight) for a period of 45 days and the effect of SAC on urinary albumin excretion, metabolic parameters, and tubular injury biomarkers by ELISA, total levels and phosphorylation of MEK1/2, ERK1/2, and RSK2 by western blotting analysis in control and experimental rats were assessed.

RESULTS

From this study, we observed that SAC considerably decreased polydipsia, poly urea, polyphagia, albuminuria and the levels of urinary N-acetyl-beta-D-glucosaminidase, neutrophil gelatinase-associated lipocalin, transforming growth factor-β1 and SAC effectively altered the pathological changes in DN rats. SAC also reserved renal cortical phosphorylation of MEK1/2, ERK1/2 and RSK2.

CONCLUSION

Hence this study recommended that SAC can successfully protect the DN through regulation of MEK1/2-ERK1/2-RSK2 signalling.

Common gene signatures and molecular mechanisms of diabetic nephropathy and metabolic syndrome

Background

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Multiple metabolic toxicities, redox stress, and endothelial dysfunction contribute to the development of diabetic glomerulosclerosis and DN. Metabolic syndrome (MetS) is a pathological state in which the body's ability to process carbohydrates, fats, and proteins is compromised because of metabolic disorders, resulting in redox stress and renal remodeling. However, a causal relationship between MetS and DN has not been proven. This study aimed to provide valuable information for the clinical diagnosis and treatment of MetS with DN.

Methods

Here, transcriptome data of DN and MetS patients were obtained from the Gene Expression Omnibus database, and seven potential biomarkers were screened using bioinformatics analysis. In addition, the relationship between these marker genes and metabolism and immune infiltration was explored. Among the identified marker genes, the relationship between PLEKHA1 and the cellular process, oxidative phosphorylation (OXPHOS), in DN was further investigated through single-cell analysis.

Results

We found that PLEKHA1 may represent an important biomarker that perhaps initiates DN by activating B cells, proximal tubular cells, distal tubular cells, macrophages, and endothelial cells, thereby inducing OXPHOS in renal monocytes.

Conclusion

Overall, our findings can aid in further investigation of the effects of drug treatment on single cells of patients with diabetes to validate PLEKHA1 as a therapeutic target and to inform the development of targeted therapies.

Research progress on exosomes in podocyte injury associated with diabetic kidney disease

Diabetic kidney disease (DKD), a common cause of end-stage renal disease, is a serious complication that develops with the progression of chronic diabetes. Its main clinical manifestations are persistent proteinuria and/or a progressive decline in the estimated glomerular filtration rate. Podocytes, terminally differentiated glomerular visceral epithelial cells, constitute the glomerular filtration barrier together with the basement membrane and endothelial cells, and the structural and functional barrier integrity is closely related to proteinuria. In recent years, an increasing number of studies have confirmed that podocyte injury is the central target of the occurrence and development of DKD, and research on exosomes in podocyte injury associated with DKD has also made great progress. The aim of this review is to comprehensively describe the potential diagnostic value of exosomes in podocyte injury associated with DKD, analyze the mechanism by which exosomes realize the communication between podocytes and other types of cells and discuss the possibility of exosomes as targeted therapy drug carriers to provide new targets for and insights into delaying the progression of and treating DKD.

The Protective Effect of Theaflavins on the Kidney of Mice with Type II Diabetes Mellitus

Diabetic nephropathy, primarily caused by advanced glycation end products (AGEs), is a serious complication resulting from type 2 diabetes mellitus (T2DM). Reportedly, theaflavins (TFs) can improve diabetic nephropathy; however, the underlying molecular mechanism is not fully clear. In this study, T2DM mice were treated with different concentrations of TFs by gavage for 10 weeks to investigate the effect of TFs on diabetic nephropathy and their potential molecular mechanism of action. Biochemical and pathological analysis showed that the TFs effectively improved blood glucose, insulin resistance, kidney function, and other symptoms in diabetic mice. The mechanism studies indicated that TFs inhibited the formation of AGEs, thereby inhibiting the activation of the MAPK/NF-κB signaling pathway. Therefore, our study suggested that TFs improved diabetic nephropathy by inhibiting the formation of AGEs.

Protective effects of black onion polysaccharide on liver and kidney injury in T2DM rats through the synergistic impact of hypolipidemic and antioxidant abilities

In this study, the synergistic effects of black onion on the hypolipidemic and antioxidant activities in T2DM rats induced by a high-fat-diet and alloxan were investigated. The results showed that the fasting blood glucose of diabetic rats was significantly decreased after treatment with black onion polysaccharide (p < 0.01). Blood lipid analysis indicated that black onion polysaccharide could significantly improve the abnormal metabolism of blood lipids caused by diabetes. In addition, the MDA and ROS of the diabetic rats treated with black onion polysaccharide were significantly reduced; moreover, SOD was increased, indicating the excellent antioxidant activity of black onion polysaccharide. A histological examination clearly showed that black onion polysaccharide could improve the histological morphology of the liver and kidney. Furthermore, the indices of liver and kidney function were restored. These results indicate that black onion polysaccharide can reduce blood glucose and simultaneously show synergistic effects of hypoglycemic and antioxidant activities in diabetic rats. Therefore, black onion polysaccharide may alleviate liver and kidney function injury by improving the "two-hit" mechanism and can thus be used as a potential functional food to prevent diabetes and its complications.

Sleep, cardiovascular risk factors, and kidney function: The Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVES

Examine the associations of sleep measures with kidney function changes over time among individuals from a community-based study.

METHODS

The sample includes 1657 participants (287 with chronic kidney disease [CKD]) in the Multi-Ethnic Study of Atherosclerosis Sleep Cohort (mean age: 57.7 years, male: 46.0%). We examined associations between a large set of sleep variables (polysomnography, actigraphy, and questionnaires) and cardiovascular disease risk factors and changes in estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio over approximately 5 years using high-dimensional regression. We investigated the modifying effect of sleep on the associations between cardiovascular disease risk factors and kidney function.

RESULTS

Sleep metrics predicted kidney function decline only among individuals with baseline CKD. Among this group, eGFR decline was associated with decreased stage N3 sleep (0.32 mL/min/1.73 m2/y per 10% decrease in N3, p < .001); increased actigraphy napping frequency (beta: -0.20 [-0.30, -0.07]); and actigraphy sleep midpoint trajectory in early morning (ref: midnight, beta: -0.84 [-1.19, -0.50]). Urinary albumin-to-creatinine ratio increase was associated with high wake bouts trajectory (ref: low, beta: 0.97 [0.28, 1.67]) and increased sleep-related hypoxemia (oxygen saturation %time<90 [≥5%], beta: 2.17 [1.26, 3.08]). Sleep metrics--N3 sleep, naps, and midpoint trajectory--significantly modified associations between hemoglobin A1C and eGFR decline.

CONCLUSIONS

Reduced deep sleep, daytime napping, increased wake bouts, delayed sleep rhythms, and overnight hypoxemia are associated with longitudinal kidney function decline, with effects most apparent in individuals with CKD. Deep sleep, napping, and sleep timing modified the association between hemoglobin A1C and kidney function.

Plasmacytoma Variant Translocation 1 (PVT1) Gene as a Potential Novel Target for the Treatment of Diabetic Nephropathy

Introduction: Diabetic nephropathy (DN), a severe microvascular complication in patients with diabetes, is clinically characterized by progressive decline in glomerular filtration rate (GFR). DN is the most common cause of end-stage renal disease (ESRD), and has a consistently high mortality rate. Despite the fact that the prevalence of DN is increasing worldwide, the molecular mechanism underlying the pathogenesis of DN is not fully understood. Previous studies indicated PVT1 as a key determinant of ESRD as well as a mediator of extracellular matrix (ECM) accumulation in vitro. More investigations into the role of PVT1 in DN development are needed. Objectives: To study the effect of PVT1 silencing on progression of DN in diabetic male C57BL/6 mice at early, intermediate and relatively advanced ages. Methods: Diabetic mice were treated with either scramble-siRNA (DM + siRNA (scramble)) or PVT1-siRNA (DM + siRNA (PVT1)), whereas the control mice were normal mice without siRNA injection (Control). Blood, urine and kidney were collected at the age of 9 (young), 16 (middle-aged) or 24 (old) weeks old. Kidney function, histology and molecular gene expression were evaluated. Results: Our findings showed that silencing of PVT1 reduced kidney hypertrophy, proteinuria (UAE, UACR, UPE, UPCR), serum creatinine, serum TGF-β1, serum insulin decline, glomerular and mesangial areas, and increased creatinine clearance in diabetic mice to levels closer to the age-matched controls. Also, silencing of PVT1 markedly suppressed the upregulation of PAI-1, TGF-β1, FN1, COL4A1, and downregulation of BMP7. Conclusion: Silencing of PVT1 ameliorates DN in terms of kidney function and histology in diabetic mice. The renoprotection is attributed to the reduction in ECM accumulation, TGF-β1 elevation and insulin decline. PVT1 is suggested to play an important role in ECM accumulation which makes it a possible target for the treatment of DN.

Pursuing Diabetic Nephropathy through Aqueous Humor Proteomics Analysis

In order to determine the possible aqueous humor (AH) proteins involved in diabetic nephropathy (DN) progression, we performed gel electrophoresis-liquid chromatography-tandem mass spectrometry protein profiling of AH samples from 5 patients with proliferative diabetic retinopathy (PDR) combined DN and 5 patients with PDR. Function enrichment analyses were carried out after the identification of differentially expressed proteins (DEPs). Protein-protein interaction networks were then built and the Search Tool for the Retrieval of Interacting Genes database and CytoNCA plugin in Cytoscape were utilized for module analysis. Ingenuity Pathway Analysis (IPA) was used to analyze disease and biological function, Tox function enrichment and upstream regulatory molecules/networks. Fifty-four DEPs were finally confirmed, whose enriched functions and pathways covered cell adhesion, extracellular exosome, complement activation, complement and coagulation cascades, etc. Nine hub genes were identified, including NCAM1, PLG, APOH, C3, PSAP, RBP4, CDH2, NUCB1, and GNS. IPA showed that C3 and PLG are involved in renal and urological system abnormalities. Conclusively, DEPs and hub proteins confirmed in this exploratory AH proteomic analysis may help us gain a deeper understanding of the molecular mechanisms involved in DN progression, providing novel candidate biomarkers for the early detection for diagnosis of DN.

The landscape of immune cell infiltration in the glomerulus of diabetic nephropathy: evidence based on bioinformatics

Background

Increasing evidence suggests that immune cell infiltration contributes to the pathogenesis and progression of diabetic nephropathy (DN). We aim to unveil the immune infiltration pattern in the glomerulus of DN and provide potential targets for immunotherapy.

Methods

Infiltrating percentage of 22 types of immune cell in the glomerulus tissues were estimated by the CIBERSORT algorithm based on three transcriptome datasets mined from the GEO database. Differentially expressed genes (DEGs) were identified by the “limma” package. Then immune-related DEGs were identified by intersecting DEGs with immune-related genes (downloaded from Immport database). The protein–protein interactions of Immune-related DEGs were explored using the STRING database and visualized by Cytoscape. The enrichment analyses for KEGG pathways and GO terms were carried out by the gene set enrichment analysis (GSEA) method.

Results

11 types of immune cell were revealed to be significantly altered in the glomerulus tissues of DN (Up: B cells memory, T cells gamma delta, NK cells activated, Macrophages.M1, Macrophages M2, Dendritic cells resting, Mast cells resting; Down: B cells naive, NK cells resting, Mast cells activated, Neutrophils). Several pathways related to immune, autophagy and metabolic process were significantly activated. Moreover, 6 hub genes with a medium to strong correlation with renal function (eGFR) were identified (SERPINA3, LTF, C3, PTGDS, EGF and ALB).

Conclusion

In the glomerulus of DN, the immune infiltration pattern changed significantly. A complicated and tightly regulated network of immune cells exists in the pathological of DN. The hub genes identified here will facilitate the development of immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02906-4.

Identification of novel key genes and potential candidate small molecule drugs in diabetic kidney disease using comprehensive bioinformatics analysis

Objective: The currently established diagnostic and prognostic tools for diabetic kidney disease (DKD) have limitations, which demands the necessity to find new genes and pathways associated with diagnosis and treatment. Our study aims to reveal the gene expression alteration and discover critical genes involved in the development of DKD, thus providing novel diagnostic molecular markers and therapeutic targets.

Materials and methods: The differences of infiltrating immune cells within kidney were compared between healthy living donors and DKD patients. Besides, differentially expressed genes (DEGs) within kidney from healthy living donor, early stage DKD and advanced stage DKD samples were detected. Furthermore, the weighted co-expressed network (WGCNA) and protein-protein interaction (PPI) network were constructed, followed by recognition of core hub genes and module analysis. Receiver operating characteristic (ROC) curve analysis was implemented to determine the diagnostic value of hub genes, correlation analysis was employed to explore the association between hub genes and infiltrating immune cells, and certain hub genes was validated by quantitative real-time PCR and immunohistochemistry staining in cultured tubule cells and diabetic mice kidney. Finally, the candidate small molecules as potential drugs to treat DKD were anticipated through utilizing virtual screening and molecular docking investigation.

Results: Our study revealed significantly higher proportion of infiltrating immune cells within kidney from DKD patients via probing the immune landscape by single-cell transcriptomics. Besides, 126 commonly shared DEGs identified among three group samples were enriched in immune biological process. In addition, the ROC curve analysis demonstrated the strong diagnostic accuracy of recognized hub genes (NFKB1, DYRK2, ATAD2, YAP1, and CHD3) from PPI network. Correlation analysis further confirmed the positive association between these hub genes with infiltrating natural killer cells. More importantly, the mRNA transcripts and protein abundance of YAP1 were significantly higher in high glucose-treated renal tubule cells and diabetic mice kidney, and the small molecules exhibiting the best binding affinities with YAP1 were predicted and acquired.

Conclusion: Our findings for the first time indicate that NFKB1, DYRK2, ATAD2, YAP1, and CHD3 might be potential novel biomarkers and therapeutic targets for DKD, providing insights into the molecular mechanisms underlying the pathogenesis of DKD.

Epigallocatechin-3-gallate ameliorates renal endoplasmic reticulum stress-mediated inflammation in type 2 diabetic rats

Epigallocatechin-3-gallate (EGCG), an essential polyphenolic constituent found in tea leaves, possesses various potent biological activities. This research was undertaken to investigate the impact of EGCG against endoplasmic reticulum (ER) stress-mediated inflammation and to clarify the underlying molecular mechanism in type 2 diabetic kidneys. The male rats were randomized into four groups: normal, diabetic, low-dose EGCG, and high-dose EGCG. In type 2 diabetic rats, hyperglycemia and hyperlipidemia noticeably caused renal structural damage and dysfunction and aggravated ER stress. Meanwhile, sustained ER stress activated the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and then upregulated the contents of inflammatory cytokines in the diabetic kidney. Following supplementation with 40 mg/kg and 80 mg/kg EGCG, hyperglycemia, hyperlipidemia, and renal histopathological alterations and dysfunction were noticeably ameliorated; renal ER stress, NLRP3 inflammasome, and inflammatory response were markedly repressed in the EGCG treatment groups. In summary, the current study highlighted the renoprotective effects of EGCG in type 2 diabetes and its mechanisms are mainly associated with the repression of ER stress-mediated NLRP3 inflammasome overactivation.

The Interplay of NEAT1 and miR-339-5p Influences on Mesangial Gene Expression and Function in Various Diabetic-Associated Injury Models

Mesangial cells (MCs), substantial cells for architecture and function of the glomerular tuft, take a key role in progression of diabetic kidney disease (DKD). Despite long standing researches and the need for novel therapies, the underlying regulatory mechanisms in MCs are elusive. This applies in particular to long non-coding RNAs (lncRNA) but also microRNAs (miRNAs). In this study, we investigated the expression of nuclear paraspeckle assembly transcript 1 (NEAT1), a highly conserved lncRNA, in several diabetes in-vitro models using human MCs. These cells were treated with high glucose, TGFβ, TNAα, thapsigargin, or tunicamycin. We analyzed the implication of NEAT1 silencing on mesangial cell migration, proliferation, and cell size as well as on mRNA and miRNA expression. Here, the miRNA hsa-miR-339-5p was not only identified as a potential interaction partner for NEAT1 but also for several coding genes. Furthermore, overexpression of hsa-miR-339-5p leads to a MC phenotype comparable to a NEAT1 knockdown. In-silico analyses also underline a relevant role of NEAT1 and hsa-miR-339-5p in mesangial physiology, especially in the context of DKD.

Quantitative Crotonylome Analysis Reveals the Mechanism of Shenkang Injection on Diabetic Nephropathy

Shenkang injection (SKI) has been widely used in the clinical treatment of chronic kidney diseases in China because of its efficacy and safety. However, the underlying mechanism of SKI in diabetic nephropathy (DN) remains unclear. The present study aimed to investigate the renoprotective effects and possible mechanisms of SKI in diabetic db/db mice. We showed that SKI ameliorated hyperglycemia and abnormal renal biochemical parameters in db/db mice. Crotonylome and subsequent bioinformatics analyses indicated that the molecular functions of the significantly different crotonylated proteins regulated by SKI were closely related to oxidoreductase activity and oxidative phosphorylation might be one of the main pathways through which SKI functions in DN. Subsequent PRM validation of the selected crotonylated proteins confirmed these findings. In addition, we determined that SKI could regulate the expression of specific proteins in oxidative phosphorylation complexes and enhance antioxidant capacity. Taken together, our data suggest that SKI exerted the protective effect against DN potentially through reversing the abnormal crotonylation expression of oxidoreductase-related proteins.

MicroRNA-146a-5p-modified human umbilical cord mesenchymal stem cells enhance protection against diabetic nephropathy in rats through facilitating M2 macrophage polarization

Background

Diabetic nephropathy (DN) is a severe complication of diabetes mellitus and a common cause of end-stage renal disease (ESRD). Mesenchymal stem cells (MSCs) possess potent anti-inflammatory and immunomodulatory properties, which render them an attractive therapeutic tool for tissue damage and inflammation.

Methods

This study was designed to determine the protective effects and underlying mechanisms of human umbilical cord-derived MSCs (UC-MSCs) on streptozotocin-induced DN. Renal function and histological staining were used to evaluate kidney damage. RNA high-throughput sequencing on rat kidney and UCMSC-derived exosomes was used to identify the critical miRNAs. Co-cultivation of macrophage cell lines and UC-MSCs-derived conditional medium were used to assess the involvement of macrophage polarization signaling.

Results

UC-MSC administration significantly improved renal function, reduced the local and systemic inflammatory cytokine levels, and attenuated inflammatory cell infiltration into the kidney tissue in DN rats. Moreover, UC-MSCs shifted macrophage polarization from a pro-inflammatory M1 to an anti-inflammatory M2 phenotype. Mechanistically, miR-146a-5p was significantly downregulated and negatively correlated with renal injury in DN rats as determined through high-throughput RNA sequencing. Importantly, UC-MSCs-derived miR-146a-5p promoted M2 macrophage polarization by inhibiting tumor necrosis factor receptor-associated factor-6 (TRAF6)/signal transducer and activator of transcription (STAT1) signaling pathway. Furthermore, miR-146a-5p modification in UC-MSCs enhanced the efficacy of anti-inflammation and renal function improvement.

Conclusions

Collectively, our findings demonstrate that UC-MSCs-derived miR-146a-5p have the potential to restore renal function in DN rats through facilitating M2 macrophage polarization by targeting TRAF6. This would pave the way for the use of miRNA-modified cell therapy for kidney diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02855-7.

Administration of mesenchymal stem cells in diabetic kidney disease: mechanisms, signaling pathways, and preclinical evidence

Diabetic kidney disease (DKD) is a serious microvascular complication of diabetes. Currently, the prevalence and mortality of DKD are increasing annually. However, with no effective drugs to prevent its occurrence and development, the primary therapeutic option is to control blood sugar and blood pressure. Therefore, new and effective drugs/methods are imperative to prevent the development of DKD in patients with diabetes. Mesenchymal stem cells (MSCs) with multi-differentiation potential and paracrine function have received extensive attention as a new treatment option for DKD. However, their role and mechanism in the treatment of DKD remain unclear, and clinical applications are still being explored. Given this, we here provide an unbiased review of recent advances in MSCs for the treatment of DKD in the last decade from the perspectives of the pathogenesis of DKD, biological characteristics of MSCs, and different molecular and signaling pathways. Furthermore, we summarize information on combination therapy strategies using MSCs. Finally, we discuss the challenges and prospects for clinical application.

Impact of klotho on the expression of SRGAP2a in podocytes in diabetic nephropathy

Background

Diabetic nephropathy (DN) is the major cause of kidney failure, and glomerular podocytes play critical roles in the pathogenesis of DN by maintaining the glomerular structure and filtration barrier. Klotho and Slit-Robo GTP activating protein 2a (SRGAP2a) have been indicated to play protective roles in reducing kidney injury, but whether there is an internal relationship between these two factors is unclear.

Methods

In this study, we cultured differentiated rat podocytes in vitro and measured the SRGAP2a expressions by immunofluorescence staining, quantitative real-time PCR (qRT-PCR) and western blotting, after siRNA-mediated transforming growth factor β1 (TGF-β1) silencing, TGF-β1 overexpression and in the presence of a reactive oxygen species (ROS) inhibitor. And we detected the expressions of SRGAP2a, small mother against decapentaplegic (Smad)2/3, phosphorylated-Smad2/3 (p-Smad2/3), Smad7, and NAD(P)H oxidase 4 (NOX4), ROS levels and podocyte cytoskeletal remodelling under high glucose (HG) and exogenous klotho conditions. In addition, we performed haematoxylin–eosin (HE) staining and immunohistochemistry with diabetic rat models to confirm the in vitro results.

Results

The results indicated that SRGAP2a expression was significantly upregulated under siRNA-mediated TGF-β1 silencing conditions or after adding a ROS inhibitor, but significantly downregulated with TGF-β1 overexpression, in the presence of HG. The supplementation of exogenous klotho under HG conditions significantly increased the SRGAP2a expression, remodelled the actin cytoskeleton and altered the expressions of Smad2/3, p-Smad2/3, Smad7 and NOX4 and reduced the ROS generation in podocytes. Moreover, klotho administration protected kidney injury in DN rats.

Conclusions

This study indicated that klotho may modulate the expression of SRGAP2a by regulating the ROS and TGF-β1 signalling pathways and provided theoretical support for klotho protein as a novel therapeutic strategy for treating DN patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02765-z.

Efficacy of liraglutide in patients with diabetic nephropathy: a meta-analysis of randomized controlled trials

BACKGROUND

The efficacy of liraglutide to treat type 2 diabetic nephropathy (T2DN) remains controversial. Thus, we conducted this meta-analysis to systematically evaluate the clinical effect of liraglutide on T2DN patients.

METHODS

Eight databases (PubMed, Web of Science, the Cochrane Library, EMBASE, Chinese National Knowledge Infrastructure (CNKI), Wanfang database, China Science and Technology Journal Database, and China Biology Medicine Database (CBM)) were searched for published articles to evaluate the clinical efficacy of liraglutide in subjects with T2DN. The Revman 5.3 and Stata 13 software were used for analyses and plotting.

RESULTS

A total of 18 randomized controlled trials (RCTs) with 1580 diabetic nephropathy patients were screened. We found that the levels of UACR, Scr, Cysc were lower in the experimental group of T2DN patients treated with liraglutide than in the control group intervened without liraglutide. Liraglutide also reduced the levels of blood glucose (including FBG, PBG, and HbA1c), body mass index (BMI), and anti-inflammatory indicators (TNF-α, IL-6). However, there was no significant difference in BUN and eGFR between the experimental group and the control group.

CONCLUSIONS

Liraglutide reduced the levels of Blood Glucose, BMI, renal outcome indicators, and serum inflammatory factors of patients with T2DN, suggesting the beneficial effects of liraglutide on renal function.

Fungus-Derived 3-Hydroxyterphenyllin and Candidusin A Ameliorate Palmitic Acid-Induced Human Podocyte Injury via Anti-Oxidative and Anti-Apoptotic Mechanisms

Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. An elevated fatty acid plasma concentration leads to podocyte injury and DN progression. This study aimed to identify and characterize cellular mechanisms of natural compounds that inhibit palmitic acid (PA)-induced human podocyte injury. By screening 355 natural compounds using a cell viability assay, 3-hydroxyterphenyllin (3-HT) and candidusin A (CDA), isolated from the marine-derived fungus Aspergillus candidus PSU-AMF169, were found to protect against PA-induced podocyte injury, with half-maximal inhibitory concentrations (IC₅₀) of ~16 and ~18 µM, respectively. Flow cytometry revealed that 3-HT and CDA suppressed PA-induced podocyte apoptosis. Importantly, CDA significantly prevented PA-induced podocyte barrier impairment as determined by 70 kDa dextran flux. Reactive oxygen species (ROS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) direct scavenging assays indicated that both compounds exerted an anti-oxidative effect via direct free radical-scavenging activity. Moreover, 3-HT and CDA upregulated the anti-apoptotic Bcl2 protein. In conclusion, 3-HT and CDA represent fungus-derived bioactive compounds that have a novel protective effect on PA-induced human podocyte apoptosis via mechanisms involving free radical scavenging and Bcl2 upregulation.

miRNA-93-5p in exosomes derived from M2 macrophages improves lipopolysaccharide-induced podocyte apoptosis by targeting Toll-like receptor 4

Diabetic nephropathy (DN) is a common complication of diabetes mellitus which can result in renal failure and severely affect public health. Several studies have revealed the important role of podocyte injury in DN progression. Although, the involvement of exosomes derived from M2 macrophages has been reported in podocyte injury, the underlying molecular mechanism of M2 macrophage-secreted exosomes has not been fully elucidated. Our study suggests that M2 macrophages mitigate lipopolysaccharide (LPS)-induced injury of podocytes via exosomes. Moreover, we observed that miR-93-5p expression was markedly upregulated in exosomes from M2 macrophages. Inhibition of miR-93-5p derived from M2 macrophage exosomes resulted in apoptosis of LPS-treated podocytes. Additionally, TLR4 showed the potential to bind to miR-93-5p. Subsequently, we validated that TLR4 is a downstream target of miR-93-5p. Further findings indicated that silencing of TLR4 reversed the renoprotective effects of miR-93-5p-containing M2 macrophage exosomes on LPS-induced podocyte injury. In summary, our study demonstrated that M2 macrophage-secreted exosomes attenuated LPS-induced podocyte apoptosis by regulating the miR-93-5p/TLR4 axis, which provides a new perspective for the treatment of patients with DN.

Liuwei Dihuang Pill Attenuates Diabetic Nephropathy by Inhibiting Renal Fibrosis via TGF-β/Smad2/3 Pathway

Among all the complications of diabetes, diabetic nephropathy is a significant factor causing the end-stage renal disease associated with high death rates. Current treatment fails to produce an ideal outcome. Thus, searching for a new preventive drug is urgently needed. Liuwei Dihuang pill (LDP), a popular ancient Chinese medicine (TCM) prescription, has been applied to treat DN-like syndromes according to TCM theory. Here, we had established an animal model with DN and LDP therapy was put into use to assess its therapeutic effect in vivo. Our data showed that oxidative stress and TGF-β/Smad2/3 pathway-induced renal fibrosis could be observed in the DN animal model. However, the treatment of LDP impeded the generation of ROS and attenuated renal fibrosis-related proteins in damaged kidneys through interference in the TGF-β/Smad3 pathway. Our results indicated that LDP attenuated oxidative stress, accompanied by preventing the production of renal fibrosis through inhibiting the TGF-β/Smad2/3 pathway.

Does Far-Infrared Therapy Improve Peritoneal Function and Reduce Recurrent Peritonitis in Peritoneal Dialysis Patients?

The use of peritoneal dialysis in end-stage renal disease is increasing in clinical practice. The main purpose of this study was to evaluate the effect of far-infrared radiation therapy on inflammation and the cellular immunity of patients undergoing peritoneal dialysis. We recruited 56 patients undergoing peritoneal dialysis, and we included 32 patients for the experimental group and 24 patients from the control group in the final analysis. The experimental evaluation in our study was as follows: (1) We used abdominal computed tomography to explore the changes in abdominal blood vessels. (2) We compared the effects of peritoneal dialysis using blood glucose, HbAlC, albumin, urea nitrogen, creatinine, white blood cells, hs-CRP; peritoneal Kt/V of peritoneal function, and eGFR. (3) We compared the cytokines’ concentrations in the two groups while controlling for the other cytokines. Results and Discussion: (1) There was no significant difference in the abdominal blood vessels of the experimental group relative to the control group according to abdominal CT over the 6 months. (2) Our study demonstrates statistically significant effects of FIR therapy on the following parameters: creatinine (p = 0.039 *) and hs-CRP (p < 0.001 **) levels decreased significantly, and eGFR (p = 0.043 *), glucose (p < 0.001 **), and albumin (p = 0.048 *) levels increased significantly. Our study found that in the experimental group, creatinine and hs-CRP levels decreased significantly due to FIR therapy for 6 months. However, our study also found that the glucose level was significantly different after FIR therapy for 6 months. Peritoneal dialysis combined with FIR can reduce the side effects of the glucose in the dialysis buffer, which interferes with peritoneal inflammation and peritoneal mesothelial cell fibrosis. (3) In addition, we also found that no statistically significant difference in any inflammatory cytokine after FIR therapy. IFN-γ (p = 0.124), IL-12p70 (p = 0.093), IL-18 (p = 0.213), and TNF-α (p = 0.254) did not exhibit significant improvements after peritoneal dialysis with FIR treatment over 6 months. Conclusions: We found that the effectiveness of peritoneal dialysis was improved significantly with FIR therapy, and significant improvements in the peritoneal permeability and inflammatory response were observed.