Epigenetics in the pathogenesis of diabetic nephropathy

Podocan unraveled: Understanding its role in tumor proliferation and smooth muscle regulation

Podocan, a small leucine-rich repeat protein, is expressed in HIV-associated nephropathy, the cardiovascular system, and smooth muscle. Studies have linked PODN and PODNL to cancers such as osteosarcoma, glioma, and stomach cancer. Research has primarily focused on podocan's role in renal podocytes, injured smooth muscle cells, and various tumor cells. Bioinformatics studies have examined the role of PODN as a biomarker in tumors. Our research summarizes the modulatory role of podocan in smooth muscle and tumor proliferation through its suppression of cell proliferation and promotion of cell differentiation via various signaling pathways, including Wnt/β-catenin, TGF-β, and Akt/mTOR. We aim to provide a comprehensive overview of PODN's involvement in smooth muscle, cardiovascular system, and tumors by integrating current and past research. This review aims to enhance understanding and inform in the diagnosis, prognosis, and treatment of various diseases.

CD2 glycoprotein and CD44 structure and prevention of diabetes nephropathy: Central characteristics of related genes based on WGCNA and PPI

Diabetic nephropathy (DN) is a prevalent complication of diabetes mellitus, characterized by complex pathogenesis that involves numerous molecules and signaling pathways. Among these, CD2 glycoprotein and CD44 play pivotal roles in cell adhesion, signal transduction, and inflammatory responses, potentially contributing significantly to the onset and progression of DN. This study aimed to investigate the central features of CD2 glycoprotein and CD44 in preventing diabetic nephropathy. To achieve this, kidney tissue sample data from DN patients were sourced from a public gene expression database. The roles of CD2 glycoprotein and CD44 within the PPI network were then analyzed, focusing on their interactions with other related genes. WGCNA analysis identified several significant gene modules associated with DN, including CD2 glycoprotein and CD44. PPI network analysis showed that these two proteins had a high degree of connectivity in the network, suggesting that they may be central regulatory molecules of DN. Further functional enrichment analysis revealed the potentially important role of CD2 glycoprotein and CD44 in diabetic nephropathy.

MSU crystallization promotes fibroblast proliferation and renal fibrosis in diabetic nephropathy via the ROS/SHP2/TGFβ pathway

Monosodium urate (MSU) crystallisation deposited in local tissues and organs induce inflammatory reactions, resulting in diseases such as gout. MSU has been recognized as a common and prevalent pathology in various clinical conditions. In this study, we investigated the role of MSU in the pathogenesis of diabetic kidney disease (DKD). We induced renal injury in diabetic kidney disease mice using streptozotocin (STZ) and assessed renal histopathological damage using Masson's trichrome staining and Collagen III immunofluorescence staining. We measured the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and uric acid (UA) using ELISA. Protein expression levels of NLRP3, p-NF-κB, SHP2, p-STAT3, and p-ERK1/2 were analyzed by Western blot. To further investigate the role of MSU in diabetic kidney disease, we conducted in vitro experiments. In our in vivo experiments, we found that compared to the Model group, there was a significant increase in interstitial fibrosis in the kidneys of mice after treatment with MSU, accompanied by elevated levels of MDA, SOD, and UA. Furthermore, the protein expression of NLRP3, p-NF-NB, SHP2, p-STAT3, and p-ERK1/2 was upregulated. In our subsequent studies on mouse fibroblasts (L929 cells), we discovered that high glucose, MSU, and TGF-β could promote the expression of P22, GP91, NLRP3, NF-κB, p-NF-κB, p-SHP2, p-EGFR, p-STAT3, and Collagen-III proteins. Additionally, we found that SHP2 could counteract the upregulation trend induced by MSU on the expression of p-SHP2, p-EGFR, p-STAT3, and Collagen-III proteins, and inhibitors YQ128, NAC, and Cetuximab exhibited similar effects. Furthermore, immunofluorescence results indicated that SHP2 could inhibit the expression of the fibrosis marker α-SMA in L929 cells. These findings suggest that MSU can promote renal fibroblast SHP2 expression, induce oxidative stress, activate the NLRP3/NF-κB pathway, and enhance diabetic kidney disease fibroblast proliferation through the TGFβ/STAT3/ERK1/2 signaling pathway, leading to renal fibrosis.

Chinese herbal medicine for the treatment of diabetic nephropathy: From clinical evidence to potential mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is a typical chronic microvascular complication of diabetes, characterized by proteinuria and a gradual decline in renal function. At present, there are limited clinical interventions aimed at preventing the progression of DN to end-stage renal disease (ESRD). However, Chinese herbal medicine presents a distinct therapeutic approach that can be effectively combined with conventional Western medicine treatments to safeguard renal function. This combination holds considerable practical implications for the treatment of DN.

AIM OF THE STUDY

This review covers commonly used Chinese herbal remedies and decoctions applicable to various types of DN, and we summarize the role played by their active ingredients in the treatment of DN and their mechanisms, which includes how they might improve inflammation and metabolic abnormalities to provide new ideas to cope with the development of DN.

MATERIALS AND METHODS

With the keywords "diabetic nephropathy," "Chinese herbal medicine," "clinical effectiveness," and "bioactive components," we conducted an extensive literature search of several databases, including PubMed, Web of Science, CNKI, and Wanfang database, to discover studies on herbal formulas that were effective in slowing the progression of DN. The names of the plants covered in the review have been checked at MPNS (http://mpns.kew.org).

RESULTS

This review demonstrates the superior total clinical effective rate of combining Chinese herbal medicines with Western medicines over the use of Western medicines alone, as evidenced by summarizing the results of several clinical trials. Furthermore, the review highlights the nephroprotective effects of seven frequently used herbs exerting beneficial effects such as podocyte repair, anti-fibrosis of renal tissues, and regulation of glucose and lipid metabolism through multiple signaling pathways in the treatment of DN.

CONCLUSIONS

The potential of herbs in treating DN is evident from their excellent effectiveness and the ability of different herbs to target various symptoms of the condition. However, limitations arise from the deficiencies in interfacing with objective bioindicators, which hinder the integration of herbal therapies into modern medical practice. Further research is warranted to address these limitations and enhance the compatibility of herbal therapies with contemporary medical standards.

DNA methyltransferase isoforms regulate endothelial cell exosome proteome composition

Extrinsic and intrinsic pathological stimuli in vascular disorders induce DNA methylation based epigenetic reprogramming in endothelial cells, which leads to perturbed gene expression and subsequently results in endothelial dysfunction (ED). ED is also characterized by release of exosomes with altered proteome leading to paracrine interactions in vasculature and subsequently contributing to manifestation, progression and severity of vascular complications. However, epigenetic regulation of exosome proteome is not known. Hence, our present study aimed to understand influence of DNA methylation on exosome proteome composition and their influence on endothelial cell (EC) function. DNMT isoforms (DNMT1, DNMT3A, and DNMT3B) were overexpressed using lentivirus in ECs. Exosomes were isolated and characterized from ECs overexpressing DNMT isoforms and C57BL/6 mice plasma treated with 5-aza-2'-deoxycytidine. 3D spheroid assay was performed to understand the influence of exosomes derived from cells overexpressing DNMTs on EC functions. Further, the exosomes were subjected to TMT labelled proteomics analysis followed by validation. 3D spheroid assay showed increase in the pro-angiogenic activity in response to exosomes derived from DNMT overexpressing cells which was impeded by inclusion of 5-aza-2'-deoxycytidine. Our results showed that exosome proteome and PTMs were significantly modulated and were associated with dysregulation of vascular homeostasis, metabolism, inflammation and endothelial cell functions. In vitro and in vivo validation showed elevated DNMT1 and TGF-β1 exosome proteins due to DNMT1 and DNMT3A overexpression, but not DNMT3B which was mitigated by 5-aza-2'-deoxycytidine indicating epigenetic regulation. Further, exosomes induced ED as evidenced by reduced expression of phospho-eNOSser1177. Our study unveils epigenetically regulated exosome proteins, aiding management of vascular complications.

The immune-inflammation factor is associated with diabetic nephropathy: evidence from NHANES 2013-2018 and GEO database

Diabetic nephropathy (DN) is a common secondary kidney disease. Immune and inflammatory responses play an influential role in the development of DN. This study aims to explore the role and mechanisms of immune- and inflammatory-related factors in DN. Participants from the NHANES 2013-2018 were included to evaluate the association between the SII and DN. Considering the skewed distribution of SII, log SII was used for subsequent analysis. Then, the DEGs were extracted from the GSE96804 dataset by the "limma" package of R, which were further screened out genes in the key module based on WGCNA. The intersection genes between DEGs and key module genes were the key genes for the following mechanism exploration. The CyTargetlinker plug-in of Cytoscape software was used to construct the drug-genes network. Molecular docking was used to calculate the binding affinity between potential drugs and the hub genes. Among the 8236 participants from NHANES 2013-2018, Log SII was significantly associated with DN (p < 0.05). DEG and WGCNA revealed 30 DN-related genes, which mainly regulated immune- and inflammation pathways, and the NOD-like receptor signaling pathway was the core pathway highly involved in the DN occurrence. Moreover, NAIP, ZFP36, and DUSP1 were identified as hub genes in DN progression and there was a strong binding interaction between resveratrol and DUSP1.In conclusion, immune inflammation plays an influential role in the occurrence and development of DN. SII is an effective diagnostic marker for DN and resveratrol might have potential value in treating DN.

Unveiling diabetic nephropathy: a novel diagnostic model through single-cell sequencing and co-expression analysis

BACKGROUND

Diabetic nephropathy (DN) is a severe complication of diabetes that affects the kidneys. Disulfidptosis, a newly defined type of programmed cell death, has emerged as a potential area of interest, yet its significance in DN remains unexplored.

METHODS

This study utilized single-cell sequencing data GSE131882 from GEO database combined with bulk transcriptome sequencing data GSE30122, GSE30528 and GSE30529 to investigate disulfidptosis in DN. Single-cell sequencing analysis was performed on samples from DN patients and healthy controls, focusing on cell heterogeneity and communication. Weighted gene co-expression network analysis (WGCNA) and gene set enrichment analysis (GSEA) were employed to identify disulfidptosis-related gene sets and pathways. A diagnostic model was constructed using machine learning techniques based on identified genes, and immunocorrelation analysis was conducted to explore the relationship between key genes and immune cells. PCR validation was performed on blood samples from DN patients and healthy controls.

RESULTS

The study revealed significant disulfidptosis heterogeneity and cell communication differences in DN. Specific targets related to disulfidptosis were identified, providing insights into the pathogenesis of DN. The diagnostic model demonstrated high accuracy in distinguishing DN from healthy samples across multiple datasets. Immunocorrelation analysis highlighted the complex interactions between immune cells and key disulfidptosis-related genes. PCR validation supported the differential expression of model genes VEGFA, MAGI2, THSD7A and ANKRD28 in DN.

CONCLUSION

This research advances our understanding of DN by highlighting the role of disulfidptosis and identifying potential biomarkers for early detection and personalized treatment.

Targeting ferroptosis: a new therapeutic opportunity for kidney diseases

Ferroptosis is a form of non-apoptotic regulated cell death (RCD) that depends on iron and is characterized by the accumulation of lipid peroxides to lethal levels. Ferroptosis involves multiple pathways including redox balance, iron regulation, mitochondrial function, and amino acid, lipid, and glycometabolism. Furthermore, various disease-related signaling pathways also play a role in regulating the process of iron oxidation. In recent years, with the emergence of the concept of ferroptosis and the in-depth study of its mechanisms, ferroptosis is closely associated with various biological conditions related to kidney diseases, including kidney organ development, aging, immunity, and cancer. This article reviews the development of the concept of ferroptosis, the mechanisms of ferroptosis (including GSH-GPX4, FSP1-CoQ1, DHODH-CoQ10, GCH1-BH4, and MBOAT1/2 pathways), and the latest research progress on its involvement in kidney diseases. It summarizes research on ferroptosis in kidney diseases within the frameworks of metabolism, reactive oxygen biology, and iron biology. The article introduces key regulatory factors and mechanisms of ferroptosis in kidney diseases, as well as important concepts and major open questions in ferroptosis and related natural compounds. It is hoped that in future research, further breakthroughs can be made in understanding the regulation mechanism of ferroptosis and utilizing ferroptosis to promote treatments for kidney diseases, such as acute kidney injury(AKI), chronic kidney disease (CKD), diabetic nephropathy(DN), and renal cell carcinoma. This paves the way for a new approach to research, prevent, and treat clinical kidney diseases.

SRS 16-86 promotes diabetic nephropathy recovery by regulating ferroptosis

Diabetic nephropathy (DN) is a common complication of diabetes mellitus (DM), and cell death plays an important role. Ferroptosis is a recently discovered type of iron-dependent cell death and one that is different from other kinds of cell death including apoptosis and necrosis. However, ferroptosis has not been described in the context of DN. This study explored the role of ferroptosis in DN pathophysiology and aimed to confirm the efficacy of the ferroptosis inhibitor SRS 16-86 on DN. Streptozotocin injection was used to establish the DM and DN animal models. To investigate the presence or occurrence of ferroptosis in DN, we assessed the concentrations of iron, reactive oxygen species and specific markers associated with ferroptosis in a rat model of DN. Additionally, we performed haematoxylin-eosin staining, blood biochemistry, urine biochemistry and kidney function analysis to evaluate the efficacy of the ferroptosis inhibitor SRS 16-86 in ameliorating DN. We found that SRS 16-86 could improve the recovery of renal function after DN by upregulating glutathione peroxidase 4, glutathione and system xc -light chain and by downregulating the lipid peroxidation markers and 4-hydroxynonenal. SRS 16-86 treatment could improve renal organization after DN. The inflammatory cytokines interleukin 1β and tumour necrosis factor α and intercellular adhesion molecule 1 were significantly decreased following SRS 16-86 treatment after DN. The results indicate that there is a strong connection between ferroptosis and the pathological mechanism of DN. The efficacy of the ferroptosis inhibitor SRS 16-86 in DN repair supports its use as a new therapeutic treatment for DN.

Evaluating new biomarkers for diabetic nephropathy: Role of α2-macroglobulin, podocalyxin, α-L-fucosidase, retinol-binding protein-4, and cystatin C

BACKGROUND

The intricate relationship between type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) presents a challenge in understanding the significance of various biomarkers in diagnosis.

AIM

To elucidate the roles and diagnostic values of α2-macroglobulin (α2-MG), podocalyxin (PCX), α-L-fucosidase (AFU), retinol-binding protein-4 (RBP-4), and cystatin C (CysC) in DN.

METHODS

From December 2018 to December 2020, 203 T2DM patients were enrolled in the study. Of these, 115 were diagnosed with DN (115 patients), while the remaining 88 patients were classified as non-DN. The urinary levels of α2-MG, PCX, and AFU and the serum concentrations RBP-4 and CysC were measured in conjunction with other relevant clinical indicators to evaluate their potential correlations and diagnostic utility.

RESULTS

After adjustments for age and gender, significant positive correlations were observed between the biomarkers CysC, RBP-4, α2-MG/urinary creatinine (UCr), PCX/UCr, and AFU/UCr, and clinical indicators such as urinary albumin-to-creatinine ratio (UACR), serum creatinine, urea, 24-h total urine protein, and neutrophil-to-lymphocyte ratio (NLR). Conversely, these biomarkers exhibited negative correlations with the estimated glomerular filtration rate (P < 0.05). Receiver operating characteristic (ROC) curve analysis further demonstrated the diagnostic performance of these biomarkers, with UACR showcasing the highest area under the ROC curve (AUCROC) at 0.97.

CONCLUSION

This study underscores the diagnostic significance of α2-MG, PCX, and AFU in the development of DN. The biomarkers RBP-4, CysC, PCX, AFU, and α2-MG provide promising diagnostic insights, while UACR is the most potent diagnostic biomarker in assessing DN.

Ginsenoside Rg3 induces mesangial cells proliferation and attenuates apoptosis by miR-216a-5p/MAPK pathway in diabetic kidney disease

BACKGROUND

Ginsenoside Rg3 is an active saponin isolated from ginseng, which can reduce renal inflammation. However, the role and mechanism of Rg3 in diabetic kidney disease (DKD) are far from being studied.

METHODS

The effects of Rg3 and miR-216a-5p on the proliferation, apoptosis, and MAPK pathway in high glucose (HG)-induced SV40 MES 13 were monitored by CCK-8, TUNEL staining, and western blot.

RESULTS

Rg3 treatment could accelerate proliferation and suppress apoptosis in HG-induced SV40 MES. Moreover, miR-216a-5p inhibition also could alleviate renal injury, prevent apoptosis, and activate the MAPK pathway in kidney tissues of diabetic model mice.

CONCLUSION

Rg3 could attenuate DKD progression by downregulating miR-216a-5p, suggesting Rg3 and miR-216a-5p might be the potential drug and molecular targets for DKD therapy.

Sirt7/HIC1 complex participates in hyperglycaemia-mediated EndMT via modulation of SDC1 expression in diabetic kidney disease and metabolic memory

Diabetic kidney disease (DKD), a primary microvascular complication arising from diabetes, may result in end-stage renal disease. Epigenetic regulation of endothelial mesenchymal transition (EndMT) has been recently reported to exert function in metabolic memory and DKD. Here, we investigated the mechanism which Sirt7 modulated EndMT in human glomerular endothelial cells (HGECs) in the occurrence of metabolic memory in DKD. Lower levels of SDC1 and Sirt7 were noted in the glomeruli of both DKD patients and diabetes-induced renal injury rats, as well as in human glomerular endothelial cells (HGECs) with high blood sugar. Endothelial-to-mesenchymal transition (EndMT) was sustained despite the normalization of glycaemic control. We also found that Sirt7 overexpression associated with glucose normalization promoted the SDC1 expression and reversed EndMT in HGECs. Furthermore, the sh-Sirt7-mediated EndMT could be reversed by SDC1 overexpression. The ChIP assay revealed enrichment of Sirt7 and H3K18ac in the SDC1 promoter region. Furthermore, hypermethylated in cancer 1 (HIC1) was found to be associated with Sirt7. Overexpression of HIC1 with normoglycaemia reversed high glucose-mediated EndMT in HGECs. The knockdown of HIC1-mediated EndMT was reversed by SDC1 upregulation. In addition, the enrichment of HIC1 and Sirt7 was observed in the same promoter region of SDC1. The overexpressed Sirt7 reversed EndMT and improved renal function in insulin-treated diabetic models. This study demonstrated that the hyperglycaemia-mediated interaction between Sirt7 and HIC1 exerts a role in the metabolic memory in DKD by inactivating SDC1 transcription and mediating EndMT despite glucose normalization in HGECs.

SirT7-mediated transcription of fascin in hyperglycemic glomerular endothelial cells contributes to EndMT in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease worldwide. It is reported that the endothelial-to-mesenchymal transition (EndMT) in glomerular endothelial cells plays an important role in DN. As a specific form of epithelial-to-mesenchymal transition, EndMT may involve common regulators of epithelial-to-mesenchymal transition. Fascin has been shown to mediate epithelial-to-mesenchymal transition. In addition, SirT7 has been confir med to contribute to inflammation in hyperglycemic endothelial cells via the modulation of gene transcription. In this study, we speculate that SirT7 modulates fascin transcription and is thus involved in EndMT in hyperglycemic glomerular endothelial cells. Our data indicate that α-smooth muscle actin (α-SMA) and fascin levels are increased, while CD31 levels are decreased in the kidneys of DN rats. Consistently, our cellular experiments reveal that high glucose treatment elevates fascin levels and induces EndMT in human glomerular endothelial cells (HGECs). Moreover, silencing of fascin inhibits EndMT in hyperglycaemic HGECs. In addition, SirT7 is found to be decreased in hyperglycemic cells and in the kidneys of DN mice. Moreover, the inhibition of SirT7 increases fascin level and mediates EndMT. An increase in SirtT7 expression decreases fascin expression, inhibits EndMT, and improves renal function in hyperglycemic cells and DN mice. SirT7 is found to bind to the promoter region of fascin. In summary, the present study indicates that SirT7 transcribes fascin to contribute to hyperglycemia-induced EndMT in DN patients.

Nucleic acid and protein methylation modification in renal diseases

Although great efforts have been made to elucidate the pathological mechanisms of renal diseases and potential prevention and treatment targets that would allow us to retard kidney disease progression, we still lack specific and effective management methods. Epigenetic mechanisms are able to alter gene expression without requiring DNA mutations. Accumulating evidence suggests the critical roles of epigenetic events and processes in a variety of renal diseases, involving functionally relevant alterations in DNA methylation, histone methylation, RNA methylation, and expression of various non-coding RNAs. In this review, we highlight recent advances in the impact of methylation events (especially RNA m6A methylation, DNA methylation, and histone methylation) on renal disease progression, and their impact on treatments of renal diseases. We believe that a better understanding of methylation modification changes in kidneys may contribute to the development of novel strategies for the prevention and management of renal diseases.

Urinary stem cell-derived exocrine circRNA ATG7 regulates the SOCS1/STAT3 signaling pathway through miR-4500, inhibits M1 macrophage polarization, and alleviates the progression of diabetes nephropathy

OBJECTIVE

The etiopathogenesis of diabetes nephropathy (DN) has not yet been fully clarified. Finding effective treatments to prevent renal failure in DN patients has become the main focus of research in recent years. Circular RNA (circRNA) has been shown to play a momentous role in DN progression. Based on this, we aimed to investigate the potential mechanism by which urine-derived stem cell (USC)-derived exosome circRNA ATG7 (Exo-ATG7) mediates DN progression.

METHODS

Exosomes from USCs were isolated and identified. The DN rat model was established by intraperitoneally injecting 60 mg/kg streptozotocin. The protein expression levels were measured by Western blot and immunofluorescence. HE and Masson staining were used to evaluate renal injury, and the expression of related genes was detected by RT-qPCR.

RESULTS

CircRNA ATG7 was significantly downregulated in the DN rat model, and the extracellular vesicles of USCs improved renal function and reduced inflammation in DN rats. However, after knocking down the USCs-derived exosome circRNA ATG7, improvement and therapeutic effect on renal function in DN rats were lost. In addition, overexpression of ATG7 facilitated the switching of macrophages from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype both in vivo and in vitro. Mechanistically, upregulation of circRNA ATG7 expression can alleviate renal damage in DN rats. Importantly, the USCs-derived exosome circRNA ATG7 promotes macrophage M2 polarization by regulating the SOCS1/STAT3 signaling pathway through miR-4500. In addition, animal experiments also confirmed that after knocking down ATG7 in USC cells, the extracted exosome-treated DN rats could weaken the therapeutic effect of USC exosomes.

CONCLUSION

Our research results indicate that USC-derived exosomal circRNA ATG7 facilitates macrophage phenotype switching from M1 to M2 through the SOCS1/STAT3 signaling pathway mediated by miR-4500, thereby inhibiting DN progression.

Jian-Pi-Gu-Shen-Hua-Yu Decoction Alleviated Diabetic Nephropathy in Mice through Reducing Ferroptosis

Background

Diabetic nephropathy (DN), one of the most frequent complications of diabetes mellitus, is a leading cause of end-stage renal disease. However, the current treatment methods still cannot effectively halt the progression of DN. Jian-Pi-Gu-Shen-Hua-Yu (JPGS) decoction can be used for the treatment of chronic kidney diseases such as DN, but the specific mechanism of action has not been fully elucidated yet.

Purpose

The aim of this study is to clarify whether JPGS alleviates the progression of diabetic nephropathy by inhibiting ferroptosis.

Materials and Methods

We established a DN mouse model to investigate the therapeutic effect of JPGS in a DN mouse model. Subsequently, we examined the effects of JPGS on ferroptosis- and glutathione peroxidase 4 (GPX4) pathway-related indices. Finally, we validated whether JPGS inhibited ferroptosis in DN mice via the GPX4 pathway using GPX4 inhibitor and ferroptosis inhibitors.

Results

The results indicate that JPGS has a therapeutic effect on DN mice by improving kidney function and reducing inflammation. Additionally, JPGS treatment decreased iron overload and oxidative stress levels while upregulating the expression of GPX4 pathway-related proteins. Moreover, JPGS demonstrated a similar therapeutic effect as Fer-1 in the context of DN treatment, and RSL3 was able to counteract the therapeutic effect of JPGS and antiferroptotic effect.

Conclusion

JPGS has significant therapeutic and anti-inflammatory effects on DN mice, and its mechanism is mainly achieved by upregulating the expression of GPX4 pathway-related proteins, thereby alleviating iron overload and ultimately reducing ferroptosis.

IGF2BP3-stabilized CAMK1 regulates the mitochondrial dynamics of renal tubule to alleviate diabetic nephropathy

BACKGROUND

CAMK1 has been shown to be involved in human disease progression via regulating mitochondrial dynamics. However, whether CAMK1 mediates mitochondrial dynamics to regulate diabetic nephropathy (DN) process remains unclear.

METHODS

Mice were injected with streptozotocin (STZ) to mimic diabetic mice models in vivo, and mice with proximal tubule-specific knockout of CAMK1 (CAMK1-KO) were generated. HK-2 cells were treated with high-glucose (HG) to mimic DN cell model in vitro. Histopathological analysis was performed to confirm kidney injury in mice. ROS production and apoptosis were assessed by DHE staining and TUNEL staining. Mitochondria morphology was observed and analyzed by electron microscopy. Mitochondrial membrane potential was detected by JC-1 staining, and cell proliferation was measured by EdU assay. The mRNA and protein expression were examined by qRT-PCR, western blot and immunostaining. RNA interaction was confirmed by RIP assay and dual-luciferase reporter assay. The mRNA stability was tested by actinomycin D treatment, and m6A level was examined by MeRIP assay.

RESULTS

CAMK1 was reduced in DN patients and STZ-induced diabetic mice. Conditional deletion of CAMK1 aggravated kidney injury and promoted mitochondrial fission in diabetic mice. CAMK1 overexpression inhibited mitochondrial fission to alleviate HG-induced HK-2 cell apoptosis. IGF2BP3 promoted the stability of CAMK1 mRNA by m6A modification. IGF2BP3 inhibited mitochondrial fission to repress cell apoptosis in vitro and kidney injury in vivo by increasing CAMK1 expression.

CONCLUSION

IGF2BP3-mediated CAMK1 mRNA stability alleviated DN progression by inhibiting mitochondria fission.

Utilizing machine learning algorithms to identify biomarkers associated with diabetic nephropathy: A review

Diabetic nephropathy (DN), a multifaceted disease with various contributing factors, presents challenges in understanding its underlying causes. Uncovering biomarkers linked to this condition can shed light on its pathogenesis and support the creation of new diagnostic and treatment methods. Gene expression data were sourced from accessible public databases, and Weighted Gene Co-expression Network Analysis (WGCNA)was employed to pinpoint gene co-expression modules relevant to DN. Subsequently, various machine learning techniques, such as random forest, lasso regression algorithm (LASSO), and support vector machine-recursive feature elimination (SVM-REF), were utilized for distinguishing DN cases from controls using the identified gene modules. Additionally, functional enrichment analyses were conducted to explore the biological roles of these genes. Our analysis revealed 131 genes showing distinct expression patterns between controlled and uncontrolled groups. During the integrated WCGNA, we identified 61 co-expressed genes encompassing both categories. The enrichment analysis highlighted involvement in various immune responses and complex activities. Techniques like Random Forest, LASSO, and SVM-REF were applied to pinpoint key hub genes, leading to the identification of VWF and DNASE1L3. In the context of DN, they demonstrated significant consistency in both expression and function. Our research uncovered potential biomarkers for DN through the application of WGCNA and various machine learning methods. The results indicate that 2 central genes could serve as innovative diagnostic indicators and therapeutic targets for this disease. This discovery offers fresh perspectives on the development of DN and could contribute to the advancement of new diagnostic and treatment approaches.

Unveiling the pathogenesis and therapeutic approaches for diabetic nephropathy: insights from panvascular diseases

Diabetic nephropathy (DN) represents a significant microvascular complication in diabetes, entailing intricate molecular pathways and mechanisms associated with cardiorenal vascular diseases. Prolonged hyperglycemia induces renal endothelial dysfunction and damage via metabolic abnormalities, inflammation, and oxidative stress, thereby compromising hemodynamics. Concurrently, fibrotic and sclerotic alterations exacerbate glomerular and tubular injuries. At a macro level, reciprocal communication between the renal microvasculature and systemic circulation establishes a pernicious cycle propelling disease progression. The current management approach emphasizes rigorous control of glycemic levels and blood pressure, with renin-angiotensin system blockade conferring renoprotection. Novel antidiabetic agents exhibit renoprotective effects, potentially mediated through endothelial modulation. Nonetheless, emerging therapies present novel avenues for enhancing patient outcomes and alleviating the disease burden. A precision-based approach, coupled with a comprehensive strategy addressing global vascular risk, will be pivotal in mitigating the cardiorenal burden associated with diabetes.

Exosomes as nanostructures deliver miR-204 in alleviation of mitochondrial dysfunction in diabetic nephropathy through suppressing methyltransferase-like 7A-mediated CIDEC N6-methyladenosine methylation

OBJECTIVE

The exosomal cargo mainly comprises proteins, lipids, and microRNAs (miRNAs). Among these, miRNAs undertake multiple biological effects of exosomes (Exos). Some stem cell-derived exosomal miRNAs have shown the potential to treat diabetic nephropathy (DN). However, there is little research into the therapeutic effects of adipose-derived stem cell (ADSC)-derived exosomal miRNAs on DN. We aimed to explore the potential of miR-204-modified ADSC-derived Exos to mitigate DN.

METHODS

Exos were extracted and identified from ADSCs. Histopathological injury, oxidative stress (OS), mitochondrial function, cell viability, and apoptosis were assessed to explore the effects of ADSC-derived Exos on DN. For mechanism exploration, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to measure miR-204, methyltransferase (METTL3, METTL14, and METTL7A), and CIDEC. Also, CIDEC m6A methylation and miR-204-METTL7A, and METTL7A-CIDEC interactions were determined.

RESULTS

Initially, OS-induced mitochondrial dysfunction was observed in DN rats. ADSC-derived Exos inhibited histopathological injury, cell apoptosis, OS, and mitochondrial dysfunction in DN rats. The similar therapeutic effects of ADSC-derived Exos were detected in the in vitro model. Intriguingly, miR-204 was released by ADSC-derived Exos and its upregulation enhanced the anti-DN effects of Exos. Mechanically, miR-204 reduced METTL7A expression to CIDEC m6A methylation, thus suppressing OS and mitochondrial dysfunction.

CONCLUSIONS

ADSC-derived exosomal miR-204 rescued OS-induced mitochondrial dysfunction by inhibiting METTL7A-mediated CIDEC m6A methylation. This study first revealed the significant role of ADSC-derived exosomal miR-204 in DN, paving the way for the development of novel therapeutic strategies to improve the clinical outcomes of DN patients.

Individuals Diagnosed With Type 2 Diabetes Mellitus and the Status of Vitamin B12 Deficiency: A Review

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with a multifactorial etiology and a significant global burden. In recent years, emerging evidence has suggested a potential link between T2DM and vitamin B12 deficiency, raising concerns about its impact on disease progression, management, and associated complications. This comprehensive review critically examines the current understanding of the prevalence, risk factors, clinical implications, and management strategies related to vitamin B12 deficiency in individuals diagnosed with T2DM. The review begins by providing an overview of the epidemiology of T2DM and its associated complications, underscoring the need for comprehensive management approaches. Subsequently, it delves into the physiology of vitamin B12, including its sources, absorption mechanisms, and biological functions, laying the groundwork for understanding the potential implications of deficiency in T2DM. A thorough analysis of the literature is conducted to elucidate the prevalence and risk factors of vitamin B12 deficiency in individuals with T2DM, considering factors such as age, duration of diabetes, medication use (e.g., metformin), dietary patterns, and comorbidities. Special attention is given to the role of metformin, the first-line therapy for T2DM, in precipitating or exacerbating vitamin B12 deficiency through mechanisms involving alterations in the gut microbiota and intestinal absorption. The review further explores the clinical manifestations and diagnostic challenges associated with vitamin B12 deficiency in the context of T2DM, emphasizing the importance of recognizing subtle symptoms and implementing appropriate screening protocols. It discusses the potential implications of vitamin B12 deficiency on glycemic control, diabetic neuropathy, cognitive function, cardiovascular health, and overall quality of life in individuals with T2DM. In addressing the management of vitamin B12 deficiency in T2DM, the review examines various therapeutic strategies, including oral and parenteral supplementation, dietary modifications, and lifestyle interventions. It critically evaluates the evidence supporting routine screening for vitamin B12 deficiency in individuals with T2DM and discusses controversies surrounding optimal supplementation protocols, dosing regimens, and monitoring strategies. Furthermore, the review highlights gaps in current knowledge and identifies areas for future research, such as the long-term effects of vitamin B12 supplementation on clinical outcomes in T2DM, the impact of genetic factors on vitamin B12 metabolism, and the potential role of personalized interventions. Overall, this review consolidates existing evidence and provides insights into the complex relationship between T2DM and vitamin B12 deficiency, aiming to inform clinical practice, enhance patient care, and guide future research endeavors in this important area of metabolic medicine.

Tangshen formula improves diabetic nephropathy in STZ-induced diabetes rats fed with hyper-methionine by regulating the methylation status of kidney

BACKGROUND

The objective of this study was to examine and analyze differential methylation profiles in order to investigate the influence of hyper-methioninemia (HM) on the development of diabetic nephropathy (DN). Male Wistar rats, aged eight weeks and weighing 250-300 g, were randomly assigned into four groups: a control group (Healthy, n = 8), streptozocin-induced rats (STZ group, n = 8), HM + STZ group (n = 8), and the Tangshen Formula (TSF) treatment group (TSF group, n = 8). Blood glucose levels and other metabolic indicators were monitored before treatment and at four-week intervals until 12 weeks. Total DNA was extracted from the aforementioned groups, and DNA methylation landscapes were analyzed via reduced representative bisulfite sequencing.

RESULTS

Both the STZ group and HM + STZ group exhibited increased blood glucose levels and urinary albumin/creatinine ratios in comparison with the control group. Notably, the HM + STZ group exhibited a markedly elevated urinary albumin/creatinine ratio (411.90 ± 88.86 mg/g) compared to the STZ group (238.41 ± 62.52 mg/g). TSF-treated rats demonstrated substantial reductions in both blood glucose levels and urinary albumin/creatinine ratios in comparison with the HM + STZ group. In-depth analysis of DNA methylation profiles revealed 797 genes with potential therapeutic effects related to TSF, among which approximately 2.3% had been previously reported as homologous genes.

CONCLUSION

While HM exacerbates DN through altered methylation patterns at specific CpG sites, TSF holds promise as a viable treatment for DN by restoring abnormal methylation levels. The identification of specific genes provides valuable insights into the underlying mechanisms of DN pathogenesis and offers potential therapeutic targets for further investigation.

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.

Applicability of mesenchymal stem cell-derived exosomes as a cell-free miRNA therapy and epigenetic modifiers for diabetes

Given that exosome nanovesicles constitute various growth factors, miRNAs and lncRNAs, they have implications for epigenetic modifications. Few studies have shown that exosomes from mesenchymal stem cells (MSCs) exhibit therapeutic effects on diabetic complications by substituting miRNAs and regulating histone modifications. Therefore, reversing epigenetic aberrations in diabetes may provide new insight into its treatment. This review discusses the impact of DNA and histone methylations on the development of diabetes and its complications. Further, we talk about miRNAs dysregulated in diabetic conditions and the possibility of utilizing mesenchymal stem cell (MSC) exosomes for the development of miRNA cell-free therapy and epigenetic modifiers in reversing diabetic-induced epigenetic alterations.

Identification of necroptosis-related features in diabetic nephropathy and analysis of their immune microenvironent and inflammatory response

Background: Diabetic nephropathy (DN) was considered a severe microvascular complication of diabetes, which was recognized as the second leading cause of end-stage renal diseases. Therefore, identifying several effective biomarkers and models to diagnosis and subtype DN is imminent. Necroptosis, a distinct form of programmed cell death, has been established to play a critical role in various inflammatory diseases. Herein, we described the novel landscape of necroptosis in DN and exploit a powerful necroptosis-mediated model for the diagnosis of DN. Methods: We obtained three datasets (GSE96804, GSE30122, and GSE30528) from the Gene Expression Omnibus (GEO) database and necroptosis-related genes (NRGs) from the GeneCards website. Via differential expression analysis and machine learning, significant NRGs were identified. And different necroptosis-related DN subtypes were divided using consensus cluster analysis. The principal component analysis (PCA) algorithm was utilized to calculate the necroptosis score. Finally, the logistic multivariate analysis were performed to construct the necroptosis-mediated diagnostic model for DN. Results: According to several public transcriptomic datasets in GEO, we obtained eight significant necroptosis-related regulators in the occurrence and progress of DN, including CFLAR, FMR1, GSDMD, IKBKB, MAP3K7, NFKBIA, PTGES3, and SFTPA1 via diversified machine learning methods. Subsequently, employing consensus cluster analysis and PCA algorithm, the DN samples in our training set were stratified into two diverse necroptosis-related subtypes based on our eight regulators' expression levels. These subtypes exhibited varying necroptosis scores. Then, we used various functional enrichment analysis and immune infiltration analysis to explore the biological background, immune landscape and inflammatory status of the above subtypes. Finally, a necroptosis-mediated diagnostic model was exploited based on the two subtypes and validated in several external verification datasets. Moreover, the expression level of our eight regulators were verified in the singe-cell level and glomerulus samples. And we further explored the relationship between the expression of eight regulators and the kidney function of DN. Conclusion: In summary, our necroptosis scoring model and necroptosis-mediated diagnostic model fill in the blank of the relationship between necroptosis and DN in the field of bioinformatics, which may provide novel diagnostic insights and therapy strategies for DN.

Effects of paricalcitol combined with hemodiafiltration on bone-metabolism-related indexes in patients with diabetic nephropathy and chronic renal failure

BACKGROUND

Diabetic nephropathy (DN) is frequently seen in the development of diabetes mellitus, and its pathogenic factors are complicated. Its current treatment is controversial, and there is a lack of a relevant efficacy prediction model.

AIM

To determine the effects of paricalcitol combined with hemodiafiltration on bone-metabolism-related indexes in patients with DN and chronic renal failure (CRF), and to construct an efficacy prediction model.

METHODS

We retrospectively analyzed 422 patients with DN and CRF treated in Cangzhou Central Hospital between May 2020 and May 2022. We selected 94 patients who met the inclusion and exclusion criteria. Patients were assigned to a dialysis group (n = 45) and a joint group (n = 49) in relation to therapeutic regimen. The clinical efficacy of the two groups was compared after treatment. The changes in laboratory indexes after treatment were evaluated, and the two groups were compared for the incidence of adverse reactions. The predictive value of laboratory indexes on the clinical efficacy on patients was analyzed.

RESULTS

The dialysis group showed a notably worse improvement in clinical efficacy than the joint group (P = 0.017). After treatment, the joint group showed notably lower serum levels of serum creatinine, uric acid (UA) and blood urea nitrogen (BUN) than the dialysis group (P < 0.05). After treatment, the joint group had lower serum levels of phosphorus, procollagen type I amino-terminal propeptide (PINP) and intact parathyroid hormone than the dialysis group, but a higher calcium level (P < 0.001). Both groups had a similar incidence of adverse reactions (P > 0.05). According to least absolute shrinkage and selection operator regression analysis, UA, BUN, phosphorus and PINP were related to treatment efficacy. According to further comparison, the non-improvement group had higher risk scores than the improvement group (P < 0.0001), and the area under the curve of the risk score in efficacy prediction was 0.945.

CONCLUSION

For treatment of CRF and DN, combined paricalcitol and hemodiafiltration can deliver higher clinical efficacy and improve the bone metabolism of patients, with good safety.

The Role of Hypoxia on the Trimethylation of H3K27 in Podocytes

Epigenetic alterations contribute to the pathogenesis of chronic diseases such as diabetes mellitus. Previous studies of our group showed that diabetic conditions reduce the trimethylation of H3K27 in podocytes in a NIPP1- (nuclear inhibitor of protein phosphatase 1) and EZH2- (enhancer of zeste homolog 2) dependent manner. It has been previously reported that in differentiated podocytes, hypoxia decreases the expression of slit diaphragm proteins and promotes foot process effacement, thereby contributing to the progression of renal disease. The exact mechanisms are, however, not completely understood. The aim of this study was to analyze the role of hypoxia and HIFs (hypoxia-inducible factor) on epigenetic changes in podocytes affecting NIPP1, EZH2 and H3K27me3, in vitro and in vivo. In vivo studies were performed with mice exposed to 10% systemic hypoxia for 3 days or injected with 3,4-DHB (dihydroxybenzoate), a PHD (prolyl hydroxylase) inhibitor, 24 h prior analyses. Immunodetection of H3K27me3, NIPP1 and EZH2 in glomerular podocytes revealed, to the best of our knowledge for the first time, that hypoxic conditions and pharmacological HIFs activation significantly reduce the expression of NIPP1 and EZH2 and diminish H3K27 trimethylation. These findings are also supported by in vitro studies using murine-differentiated podocytes.

Circular RNA circADAM9 Promotes Inflammation, Oxidative Stress, and Fibrosis of Human Mesangial Cells via the Keap1-Nrf2 Pathway in Diabetic Nephropathy

OBJECTIVE

Circular RNAs (circRNAs) have been discovered as potential biomarkers for diabetic nephropathy (DN). In this study, the potential roles of circADAM9 in high glucose (HG)-induced cell injury of human mesangial cells (HMCs) were investigated, and the underlying mechanism was elucidated.

METHODS

DN cell model in vitro was simulated by HG treatment of HMCs. Endogenous expressions of circADAM9, miR-545-3p, and ubiquitin-specific protease 15 (USP15) were determined by real-time polymerase chain reaction. Cell proliferation and migration were evaluated using Cell Counting Kit-8 and wound healing assays. The inflammatory response was assessed by enzyme-linked immunosorbent assay. Oxidative stress was examined using commercially available kits. Dual-luciferase reporter and RNA pull-down assays were conducted to confirm the interaction among circADAM9, miR-545-3p, and USP15.

RESULTS

CircADAM9 was upregulated in DN samples and HG-treated HMCs, while its downregulation inhibited cell proliferation, inflammation, fibrosis, and oxidative stress. Further investigation revealed that circADAM9 exerted this influence by targeting the miR-545-3p/USP15 axis, thereby regulating the KELCH-like ECh-associated protein 1/nuclear factor erythroid 2 related factor 2 (Keap1/Nrf2) pathway. MiR-545-3p knockdown or USP15 overexpression reversed the effect of circADAM9 silencing in HG-induced HMCs.

CONCLUSION

These results indicate that the circADAM9/miR-545-3p/USP15/Keap1/Nrf2 signaling axis is critical for HG-induced cell injury in HMCs and might represent a novel therapeutic target for DN treatment.

Machine-learning algorithm-based prediction of a diagnostic model based on oxidative stress-related genes involved in immune infiltration in diabetic nephropathy patients

Diabetic nephropathy (DN) is the most prevalent microvascular consequence of diabetes and has recently risen to the position of the world's second biggest cause of end-stage renal diseases. Growing studies suggest that oxidative stress (OS) responses are connected to the advancement of DN. This study aimed to developed a novel diagnostic model based on OS-related genes. The differentially expressed oxidative stress-related genes (DE-OSRGs) experiments required two human gene expression datasets, which were given by the GEO database (GSE30528 and GSE96804, respectively). The potential diagnostic genes were identified using the SVM-RFE assays and the LASSO regression model. CIBERSORT was used to determine the compositional patterns of the 22 different kinds of immune cell fraction seen in DN. These estimates were based on the combined cohorts. DN serum samples and normal samples were both subjected to RT-PCR in order to investigate the degree to which certain genes were expressed. In this study, we were able to locate 774 DE-OSRGs in DN. The three marker genes (DUSP1, PRDX6 and S100A8) were discovered via machine learning on two different machines. The high diagnostic value was validated by ROC tests, which focused on distinguishing DN samples from normal samples. The results of the CIBERSORT study suggested that DUSP1, PRDX6, and S100A8 may be associated to the alterations that occur in the immunological microenvironment of DN patients. Besides, the results of RT-PCR indicated that the expression of DUSP1, PRDX6, and S100A8 was much lower in DN serum samples compared normal serum samples. The diagnostic value of the proposed model was likewise verified in our cohort, with an area under the curve of 9.946. Overall, DUSP1, PRDX6, and S100A8 were identified to be the three diagnostic characteristic genes of DN. It's possible that combining these genes will be effective in diagnosing DN and determining the extent of immune cell infiltration.

Association between metformin and vitamin B12 deficiency in patients with type 2 diabetes

Diabetes mellitus (DM) is still one of the most common diseases worldwide, and its prevalence is still increasing globally. According to the American and European recommendations, metformin is considered a first-line oral hypo-glycemic drug for controlling type 2 DM (T2DM) patients. Metformin is the ninth most often prescribed drug in the world, and at least 120 million diabetic people are estimated to receive the drug. In the last 20 years, there has been increasing evidence of vitamin B12 deficiency among metformin-treated diabetic patients. Many studies have reported that vitamin B12 deficiency is related to the ma-labsorption of vitamin B12 among metformin-treated T2DM patients. Vitamin B12 deficiency may have a very bad complication for the T2DM patient. In this review, we will focus on the effect of metformin on the absorption of vitamin B12 and on its proposed mechanisms in hindering vitamin B12 absorption. In addition, the review will describe the clinical outcomes of vitamin B12 deficiency in metformin-treated T2DM.

Oxidative stress as a culprit in diabetic kidney disease

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease (ESRD), and the prevalence of DKD has increased worldwide during recent years. DKD is associated with poor therapeutic outcomes in most patients, but there is limited understanding of its pathogenesis. This review suggests that oxidative stress interacts with many other factors in causing DKD. Highly active mitochondria and NAD(P)H oxidase are major sources of oxidants, and they significantly affect the risk for DKD. Oxidative stress and inflammation may be considered reciprocal causes of DKD, in that each is a cause and an effect of DKD. Reactive oxygen species (ROS) can act as second messengers in various signaling pathways and as regulators of metabolism, activation, proliferation, differentiation, and apoptosis of immune cells. Epigenetic modifications, such as DNA methylation, histone modifications, and non-coding RNAs can modulate oxidative stress. The development of new technologies and identification of new epigenetic mechanisms may provide novel opportunities for the diagnosis and treatment of DKD. Clinical trials demonstrated that novel therapies which reduce oxidative stress can slow the progression of DKD. These therapies include the NRF2 activator bardoxolone methyl, new blood glucose-lowering drugs such as sodium-glucose cotransporter 2 inhibitors, and glucagon-like peptide-1 receptor agonists. Future studies should focus on improving early diagnosis and the development of more effective combination treatments for this multifactorial disease.

Integrated analysis of RNA methylation regulators crosstalk and immune infiltration for predictive and personalized therapy of diabetic nephropathy

BACKGROUND

RNA methylation is a widely known post-transcriptional regulation which exists in many cancer and immune system diseases. However, the potential role and crosstalk of five types RNA methylation regulators in diabetic nephropathy (DN) and immune microenvironment remain unclear.

METHODS

The mRNA expression of 37 RNA modification regulators and RNA modification regulators related genes were identified in 112 samples from 5 Gene Expression Omnibus datasets. Nonnegative Matrix Factorization clustering method was performed to determine RNA modification patterns. The ssGSEA algorithms and the expression of human leukocyte antigen were employed to assess the immune microenvironment characteristics. Risk model based on differentially expression genes responsible for the modification regulators was constructed to evaluate its predictive capability in DN patients. Furthermore, the results were validated by using immunofluorescence co-localizations and protein experiments in vitro.

RESULTS

We found 24 RNA methylation regulators were significant differently expressed in glomeruli in DN group compared with control group. Four methylation-related genes and six RNA regulators were introduced into riskScore model using univariate Logistic regression and integrated LASSO regression, which could precisely distinguish the DN and healthy individuals. Group with high-risk score was associated with high immune infiltration. Three distinct RNA modification patterns were identified, which has significant differences in immune microenvironment, biological pathway and eGFR. Validation analyses showed the METTL3, ADAR1, DNMT1 were upregulated whereas YTHDC1 was downregulated in DN podocyte cell lines comparing with cells cultured by the normal glucose.

CONCLUSION

Our study reveals that RNA methylation regulators and immune infiltration regulation play critical roles in the pathogenesis of DN. The bioinformatic analyses combine with verification in vitro could provide robust evidence for identification of predictive RNA methylation regulators in DN.

The Nicotinamide/Streptozotocin Rodent Model of Type 2 Diabetes: Renal Pathophysiology and Redox Imbalance Features

Diabetic nephropathy (DN) is a common complication of diabetes mellitus. While there has been a great advance in our understanding of the pathogenesis of DN, no effective managements of this chronic kidney disease are currently available. Therefore, continuing to elucidate the underlying biochemical and molecular mechanisms of DN remains a constant need. In this regard, animal models of diabetes are indispensable tools. This review article highlights a widely used rodent model of non-obese type 2 diabetes induced by nicotinamide (NA) and streptozotocin (STZ). The mechanism underlying diabetes induction by combining the two chemicals involves blunting the toxic effect of STZ by NA so that only a percentage of β cells are destroyed and the remaining viable β cells can still respond to glucose stimulation. This NA-STZ animal model, as a platform for the testing of numerous antidiabetic and renoprotective materials, is also discussed. In comparison with other type 2 diabetic animal models, such as high-fat-diet/STZ models and genetically engineered rodent models, the NA-STZ model is non-obese and is less time-consuming and less expensive to create. Given that this unique model mimics certain pathological features of human DN, this model should continue to find its applications in the field of diabetes research.

Sirt7 associates with ELK1 to participate in hyperglycemia memory and diabetic nephropathy via modulation of DAPK3 expression and endothelial inflammation

Diabetic nephropathy (DN) is one of the most serious complications of advanced diabetes, and increases patient mortality. Recently, epigenetics-mediated hyperglycemic memory in pathological process of DN has received attention. The purpose of this study was to determine the underlying mechanism by which sirt7 modulates hyperglycemic memory in DN. In glomerular endothelial cells (GECs) cultured in high glucose and glomeruli of DN patients and rats, an increase in p65 phosphorylation and endothelial adhesion molecule levels persisted after glucose normalization but was reversed by glucose normalization associated with death-associated protein kinase-3 (DAPK3) knockout or DAPK3 inhibitor. High glucose-mediated decrease in sirt7, the deacetylase modulating H3K18-acetylation (H3K18ac), was sustained after normoglycemia. Sirt7 overexpression accompanied by glucose normalization suppressed DAPK3 expression and inflammation in GECs. Moreover, sh-sirt7-induced inflammation was inhibited by si-DAPK3. Furthermore, sirt7 and H3K18ac were located at the DAPK3 promoter region. ELK1 was found to combine with sirt7. si-ELK1 supplemented with normoglycemia inhibited high glucose-induced DAPK3 expression and inflammation in GECs. ELK1 overexpression-mediated inflammation was inhibited by si-DAPK3. In addition, ELK1 and sirt7 were located at the same promoter region of DAPK3. ELK1 overexpression enhanced DAPK3 promoter activity, which disappeared after specific binding site mutation. In vivo, sirt7 overexpression decreased inflammation and improved renal function during insulin treatment of DN rats, whereas insulin alone did not work. Our data demonstrated high glucose-mediated mutual inhibition between sirt7 and ELK1 induced DAPK3 transcription and inflammation despite normoglycemia in GECs, thus forming a vicious cycle and participating in the occurrence of hyperglycemic memory in DN.

SETD8 cooperates with MZF1 to participate in hyperglycemia-induced endothelial inflammation via elevation of WNT5A levels in diabetic nephropathy

Objective

Diabetic nephropathy (DN) is regarded as the main vascular complication of diabetes mellitus, directly affecting the outcome of diabetic patients. Inflammatory factors were reported to participate in the progress of DN. Wingless-type family member 5 (WNT5A), myeloid zinc finger 1 (MZF1), and lysine methyltransferase 8 (SETD8) have also been reported to elevate inflammatory factor levels and activate the nuclear factor kappa B (NF-κB) pathway to induce endothelial dysfunction. In the current study, it was assumed that MZF1 associates with SETD8 to regulate WNT5A transcription, thus resulting in hyperglycemia-induced glomerular endothelial inflammation in DN.

Methods

The present study recruited 25 diagnosed DN patients (type 2 diabetes) and 25 control participants (nondiabetic renal cancer patients with normal renal function, stage I–II) consecutively. Moreover, a DN rat and cellular model was constructed in the present study. Immunohistochemistry, Western blot, and quantitative polymerase chain reaction (qPCR) were implemented to determine protein and messenger RNA (mRNA) levels. Coimmunoprecipitation (CoIP) and immunofluorescence were implemented in human glomerular endothelial cells (HGECs). Chromatin immunoprecipitation assays and dual luciferase assays were implemented to determine transcriptional activity.

Results

The results of this study indicated that levels of WNT5A expression, p65 phosphorylation (p-p65), and inflammatory factors were all elevated in DN patients and rats. In vitro, levels of p-p65 and inflammatory factors increased along with the increase of WNT5A expression in hyperglycemic HGECs. Moreover, high glucose increased MZF1 expression and decreased SETD8 expression. MZF1 and SETD8 inhibit each other under the stimulus of high glucose, but cooperate to regulate WNT5A expression, thus influencing p-p65 and endothelial inflammatory factors levels. Overexpression of MZF1 and silencing of SETD8 induced endothelial p-p65 and inflammatory factors levels, which can be reversed by si-WNT5A. Mechanistic research indicated that MZF1, SETD8, and its downstream target histone H4 lysine 20 methylation (H4K20me1) all occupied the WNT5A promoter region. sh-SETD8 expanded the enrichment of MZF1 on WNT5A promoter. Our in vivo study proved that SETD8 overexpression inhibited levels of WNT5A, p-p65 expression, and inflammatory factors in DN rats.

Conclusions

MZF1 links with SETD8 to regulate WNT5A expression in HGECs, thus elevating levels of hyperglycemia-mediated inflammatory factors in glomerular endothelium of DN patients and rats.

Trial registration ChiCTR, ChiCTR2000029425. 2020/1/31, http://www.chictr.org.cn/showproj.aspx?proj=48548

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00328-6.