Diabetic nephropathy--emerging epigenetic mechanisms

Dihydromyricetin ameliorates diabetic renal fibrosis via regulating SphK1 to suppress the activation of NF-κB pathway

Dihydromyricetin (DHM) is a flavonoid from vine tea with broad pharmacological benefits, which improve inflammation by blocking the NF-κB pathway. A growing body of research indicates that chronic kidney inflammation is vital to the pathogenesis of diabetic renal fibrosis. Sphingosine kinase-1 (SphK1) is a key regulator of diabetic renal inflammation, which triggers the NF-κB pathway. Hence, we evaluated whether DHM regulates diabetic renal inflammatory fibrosis by acting on SphK1. Here, we demonstrated that DHM effectively suppressed the synthesis of fibrotic and inflammatory adhesion factors like ICAM-1, and VCAM-1 in streptozotocin-treated high-fat diet-induced diabetic mice and HG-induced glomerular mesangial cells (GMCs). Moreover, DHM significantly suppressed NF-κB pathway activation and reduced SphK1 activity and protein expression under diabetic conditions. Mechanistically, the results of molecular docking, molecular dynamics simulation, and cellular thermal shift assay revealed that DHM stably bound to the binding pocket of SphK1, thereby reducing sphingosine-1-phosphate content and SphK1 enzymatic activity, which ultimately inhibited NF-κB DNA binding, transcriptional activity, and nuclear translocation. In conclusion, our data suggested that DHM inhibited SphK1 phosphorylation to prevent NF-κB activation thus ameliorating diabetic renal fibrosis. This supported the clinical use and further drug development of DHM as a potential candidate for treating diabetic renal fibrosis.

Relationship between circulating thrombospondin-1 messenger ribonucleic acid and microribonucleic acid-194 levels in Chinese patients with type 2 diabetic kidney disease: The outcomes of a case-control study

AIMS/INTRODUCTION

We investigated the relationship of circulating TSP-1 mRNA and miR-194 with diabetic kidney disease's degree.

MATERIALS AND METHODS

We enrolled 167 hospitalized type 2 diabetes patients in the endocrinology department. Patients were split into three groups according to urinary microalbumin: A, B and C. The control group comprised healthy outpatients (n = 163). The quantities of microribonucleic acid (miR)-194 and thrombospondin-1 (TSP-1) messenger ribonucleic acid (mRNA) in the participants' circulation were measured using a quantitative real-time polymerase chain reaction.

RESULTS

Circulating TSP-1 mRNA (P = 0.024) and miR-194 (P = 0.029) expressions significantly increased in type 2 diabetes patients. Circulating TSP-1 mRNA (P = 0.040) and miR-194 (P = 0.007) expression levels differed significantly among the three groups; circulating TSP-1 mRNA expression increased with urinary microalbumin. However, miR-194 declined in group B and increased in group C. Circulating TSP-1 mRNA was positively correlated with cystatin-c (r = 0.281; P = 0.021) and microalbumin/creatinine ratio (UmALB/Cr; r = 0.317; P = 0.009); miR-194 was positively correlated with UmALB/Cr (r = 0.405; P = 0.003). Stepwise multivariate linear regression analysis showed cystatin-c (β = 0.578; P = 0.021) and UmALB/Cr (β = 0.001; P = 0.009) as independent factors for TSP-1 mRNA; UmALB/Cr (β = 0.005; P = 0.028) as an independent factor for miR194. Areas under the curve for circulating TSP-1 mRNA and miR194 were 0.756 (95% confidence interval 0.620-0.893; sensitivity 0.69 and specificity 0.71, P < 0.01) and 0.584 (95% confidence interval 0.421-0.748; sensitivity 0.54 and specificity 0.52, P < 0.01), respectively.

CONCLUSIONS

Circulating TSP-1 mRNA and miR-194 expressions significantly increased in type 2 diabetes patients. The microalbumin group had lower levels of miR-194 (a risk factor that is valuable for type 2 diabetes kidney disease evaluation).

LncRNA SNHG14 silencing attenuates the progression of diabetic nephropathy via the miR-30e-5p/SOX4 axis

BACKGROUND

Diabetic nephropathy (DN) is a diabetic complication. LncRNAs are reported to participate in the pathophysiology of DN. Here, the function and mechanism of lncRNA small nucleolar RNA host gene 14 (SNHG14) in DN were explored.

METHODS

Streptozotocin (STZ)-induced DN mouse models and high glucose (HG)-treated human mesangial cells (MCs) were used to detect SNHG14 expression. SNHG14 silencing plasmids were applied to examine the function of SNHG14 on proliferation and fibrosis in HG-treated MCs. Potential targets of SNHG14 were predicted using bioinformatics tools and verified by luciferase reporter, RNA pulldown, and northern blotting assays. The functional role of SNHG14 in DN in vivo was detected by injection with adenoviral vector carrying sh-SNHG14 into DN mice. Serum creatinine, blood urea nitrogen, blood glucose, 24-h proteinuria, relative kidney weight, and renal pathological changes were examined in DN mice.

RESULTS

SNHG14 expression was elevated in the kidneys of DN mice and HG-treated MCs. SNHG14 silencing inhibited proliferation and fibrosis of HG-stimulated MCs. SNHG14 bound to miR-30e-5p to upregulate SOX4 expression. In rescue assays, SOX4 elevation diminished the effects of SNHG14 silencing in HG-treated MCs, and SOX4 silencing reversed the effects of SNHG14 overexpression. In in vivo studies, SNHG14 downregulation significantly ameliorated renal injuries and renal interstitial fibrosis in DN mice.

CONCLUSIONS

SNHG14 silencing attenuates kidney injury in DN mice and reduces proliferation and fibrotic phenotype of HG-stimulated MCs via the miR-30e-5p/SOX4 axis.

Pharmacological Activities of Plant-Derived Fraxin with Molecular Mechanisms: A Comprehensive Review

Fruits and vegetables serve not only as sources of nutrition but also as medicinal agents for the treatment of diverse diseases and maladies. These dietary components are significant resources of phytochemicals that demonstrate therapeutic properties against many illnesses. Fraxin is a naturally occurring coumarin glycoside mainly present in various species of Fraxinus genera, having a multitude of therapeutic uses against various diseases and disorders. This study focuses to investigate the pharmacological activities, botanical sources, and biopharmaceutical profile of the phytochemical fraxin based on different preclinical and non-clinical studies to show the scientific evidence and to evaluate the underlying molecular mechanisms of the therapeutic effects against various ailments. For this, data was searched and collected (as of February 15, 2024) in a variety of credible electronic databases, including PubMed/Medline, Scopus, Springer Link, ScienceDirect, Wiley Online, Web of Science, and Google Scholar. The findings demonstrated favorable outcomes in relation to a range of diseases or medical conditions, including inflammation, neurodegenerative disorders such as cerebral ischemia-reperfusion (I/R) and depression, viral infection, as well as diabetic nephropathy. The phytochemical also showed protective effects such as osteoprotective, renoprotective, pulmoprotective, hepatoprotective, and gastroprotective effects due to its antioxidant capacity. Fraxin has a great capability to diminish oxidative stress-related damage in different organs by stimulating the antioxidant enzymes, downregulating nuclear factor kappa B and NLRP3, and triggering the Nrf2/ARE signaling pathways. Fraxin exhibited poor oral bioavailability because of reduced absorption and a wide distribution into tissues of different organs. However, extensive research is required to decipher the biopharmaceutical profiles, and clinical studies are necessary to establish the efficacy of the natural compound as a reliable therapeutic agent.

CircGAB1 Facilitates Podocyte Injury Through Sponging miR-346 and Activating MAPK6 in Diabetic Nephropathy

BACKGROUND

Podocyte injury is very important process in diabetic nephropathy (DN) progression. Circular RNA (circRNA) takes part in regulating the advancement of DN. Herein, we explored the role and mechanism of circGAB1 in DN progression.

METHODS

The abundances of circGAB1, microRNA-346 (miR-346) and mitogen-activated protein kinase 6 (MAPK6) were detected by qRT-PCR in DN serum samples and podocyte HGPC. Moreover, cell viability and apoptosis were determined using CCK8 assay and flow cytometry. Also, the protein levels of MAPK6, proliferation-related markers and apoptosis-related markers were analyzed by western blot. ELISA assay was used to measure the levels of inflammatory factors, and corresponding kits were used to detect the levels of oxidative stress-related markers. The relationship between miR-346 and circGAB1 or MAPK6 was distinguished by dual-luciferase reporter assay.

RESULTS

CircGAB1 expression was increased in DN serum samples and HG-treated HGPC cells. CircGAB1 knockdown inhibited HG-induced apoptosis, inflammatory response and oxidative stress in HGPC cells. In terms of mechanism, circGAB1 sponged miR-346, and miR-346 targeted MAPK6. The inhibition effect of circGAB1 knockdown on HG-induced podocyte injury could be reversed by miR-346 inhibitor. Moreover, miR-346 overexpression repressed HG-induced podocyte injury by targeting MAPK6. CircGAB1 served as miR-346 sponge to positively regulate MAPK6.

CONCLUSION

CircGAB1 contributed to podocyte injury through mediating miR-346/MAPK6 axis, suggesting that circGAB1 might promote DN progression.

Metabolic memory: mechanisms and diseases

Metabolic diseases and their complications impose health and economic burdens worldwide. Evidence from past experimental studies and clinical trials suggests our body may have the ability to remember the past metabolic environment, such as hyperglycemia or hyperlipidemia, thus leading to chronic inflammatory disorders and other diseases even after the elimination of these metabolic environments. The long-term effects of that aberrant metabolism on the body have been summarized as metabolic memory and are found to assume a crucial role in states of health and disease. Multiple molecular mechanisms collectively participate in metabolic memory management, resulting in different cellular alterations as well as tissue and organ dysfunctions, culminating in disease progression and even affecting offspring. The elucidation and expansion of the concept of metabolic memory provides more comprehensive insight into pathogenic mechanisms underlying metabolic diseases and complications and promises to be a new target in disease detection and management. Here, we retrace the history of relevant research on metabolic memory and summarize its salient characteristics. We provide a detailed discussion of the mechanisms by which metabolic memory may be involved in disease development at molecular, cellular, and organ levels, with emphasis on the impact of epigenetic modulations. Finally, we present some of the pivotal findings arguing in favor of targeting metabolic memory to develop therapeutic strategies for metabolic diseases and provide the latest reflections on the consequences of metabolic memory as well as their implications for human health and diseases.

Prevalence of chronic kidney disease in Tunisian diabetics: the TUN-CKDD survey

BACKGROUND

In Tunisia, the prevalence of diabetes mellitus increased from 15.5% on 2016 to 23% by 2023. While Chronic Kidney Disease (CKD) stills the most dreaded complications of diabetes, studies on the prevalence of chronic kidney disease non-dialysis diet are scarce. The aim of this study was to assess the prevalence of chronic kidney disease among the Tunisian diabetic population based on investigators' specialty, demographic criteria (gender, age, duration of diabetes and geographic distribution) and diagnosis criteria (albuminuria and/or eGFR).

METHODS

This observational, multicentric, and cross-sectional study enrolled all diabetic subjects from all regions of Tunisia with at least 3 months of follow-up before the inclusion date, from 09 January to 08 February 2023. CKD diagnosis was established based on the KDIGO guidelines. The study was carried out at medical departments and ambulatory clinics of different healthcare providers. Baseline data were collected by investigators using an electronic case report form (eCRF). Continuous variables were described by means, median, standard deviation, and quartiles. Categorical data were tabulated in frequencies and percentages.

RESULTS

The overall prevalence of CKD among the 10,145 enrolled patients with diabetes mellitus was 38.7% with a 95%CI [37.8-39.6%]. 50.9% were male, with a mean age of 67.5 (± 11.3) years. The mean diabetes duration was 16.1 years (± 8.9). The highest CKD prevalence was noted among nephrologists (82.2%), while it was similar between the cardiologists and the primary care physicians (30.0%). CKD prevalence was highest among males (43.0% versus 35.1%) and increased proportionally with patients' age and diabetes duration. CKD was more frequent in the Mid-East Area when compared to other regions (49.9% versus 25.3 to 40.1% in other regions). Albuminuria was present within 6.6% of subjects with CKD, and it was found an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² within 13.3% of subjects wit h CKD. 18.9% had both criteria.

CONCLUSIONS

In Tunisia, CKD among diabetics had a prevalence of 38.7%, approaching European prevalence. The prevalence discrepancy worldwide of CKD can be improved with a larger population size and by implementing standardized practices.

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.

In silico prediction and experimental validation to reveal the protective mechanism of Puerarin against excessive extracellular matrix accumulation through inhibiting ferroptosis in diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Puerarin (PUR) isolated from the root of Pueraria lobata (Willd.) Ohwi is considered as one of the main medicines to alleviate asthenic splenonephro-yang of diabetic nephropathy (DN). Whereas, the exact mechanism of Puerarin on diabetic nephropathy is still unclear.

AIM OF STUDY

In this study, we aimed to investigate the protective effects of PUR on type 2 diabetic nephropathy in vivo, in silico and in vitro, as well as unveil the underlying mechanism through inhibiting ferroptosis.

MATERIALS AND METHODS

In vivo, blood glucose and lipid, renal function, kidney histology and immunohistochemistry analysis were used to vindicate the protective effects of PUR on diabetic nephropathy in type 2 DN rat model. In silico, pharmacophore matching and enrichment analysis were adopted to predict the potential mechanism of PUR on DN. In vitro, we utilized high glucose stress to induce impairment in glomerular mesangial cells (GMCs) as diabetic nephropathy cell model. Cell count kit-8 (CCK-8) was used to observe cell viability. qPCR, Western blot, immunofluorescence staining and flow cytometry were used to evaluate the effect of PUR on the generation of extracellular matrix (ECM), ferroptosis and iron homeostasis in vitro and in vivo.

RESULTS

PUR markedly improved glucose and lipid metabolism, as well as alleviated renal dysfunction in diabetic nephropathy rats. Pharmacophore matching and enrichment analysis predicted the anti-DN effect of PUR may correlate with ECM. Experimental validation suggested that PUR treatment could inhibit the generation of ECM to alleviate high-glucose-induced cell impairments, suppressing ROS production and excessive collagen fiber accumulation in GMSs, and reduce mesangial matrix expansion and renal fibrosis in type 2 DN rats. Further study suggested that PUR protected GMCs against ferroptosis via reducing LDH release and GSH disruption, suppressing key regulators of two pathways for ferroptosis execution. Moreover, PUR also maintained iron metabolism hemostasis by regulating iron transportation proteins, iron exporter proteins, and iron storage proteins and reducing intracellular iron in type 2 DN rats.

CONCLUSION

PUR inhibited excessive ECM accumulation to protect against type 2 diabetic nephropathy, which meditated by regulating iron homeostasis and mitigating ferroptosis. This study provides promising therapeutics for diabetic nephropathy treatment.

Roles of ubiquitin-specific proteases in inflammatory diseases

Ubiquitin-specific proteases (USPs), as one of the deubiquitinating enzymes (DUBs) families, regulate the fate of proteins and signaling pathway transduction by removing ubiquitin chains from the target proteins. USPs are essential for the modulation of a variety of physiological processes, such as DNA repair, cell metabolism and differentiation, epigenetic modulations as well as protein stability. Recently, extensive research has demonstrated that USPs exert a significant impact on innate and adaptive immune reactions, metabolic syndromes, inflammatory disorders, and infection via post-translational modification processes. This review summarizes the important roles of the USPs in the onset and progression of inflammatory diseases, including periodontitis, pneumonia, atherosclerosis, inflammatory bowel disease, sepsis, hepatitis, diabetes, and obesity. Moreover, we highlight a comprehensive overview of the pathogenesis of USPs in these inflammatory diseases as well as post-translational modifications in the inflammatory responses and pave the way for future prospect of targeted therapies in these inflammatory diseases.

Epigenetic Network in Immunometabolic Disease

Although a large amount of data consistently shows that genes affect immunometabolic characteristics and outcomes, epigenetic mechanisms are also heavily implicated. Epigenetic changes, including DNA methylation, histone modification, and noncoding RNA, determine gene activity by altering the accessibility of chromatin to transcription factors. Various factors influence these alterations, including genetics, lifestyle, and environmental cues. Moreover, acquired epigenetic signals can be transmitted across generations, thus contributing to early disease traits in the offspring. A closer investigation is critical in this aspect as it can help to understand the underlying molecular mechanisms further and gain insights into potential therapeutic targets for preventing and treating diseases arising from immuno-metabolic dysregulation. In this review, the role of chromatin alterations in the transcriptional modulation of genes involved in insulin resistance, systemic inflammation, macrophage polarization, endothelial dysfunction, metabolic cardiomyopathy, and nonalcoholic fatty liver disease (NAFLD), is discussed. An overview of emerging chromatin-modifying drugs and the importance of the individual epigenetic profile for personalized therapeutic approaches in patients with immuno-metabolic disorders is also presented.

Correlation of renal function indicators and vascular damage in T2DM patients with normal renal function

Background

This study aimed to assess the correlation between renal function-related indices and vascular damages among patients with type 2 diabetes mellitus (T2DM) and normal renal function.

Methods

We screened a cohort of eligible patients with T2DM, ultimately including 826 individuals. Utilizing multifactorial logistic regression, we conducted an in-depth analysis to explore the potential associations between renal function-related indices-specifically BUN, Cr, ALB, ACR, and eGFR-and the incidence of diabetic vascular damage. Additionally, to comprehensively understand the relationships, we employed Spearman correlation analysis to assess the connections between these indicators and the occurrence of vascular damage.

Results

In this cross-sectional study of 532 patients with carotid atherosclerosis (CA), the prevalence of CA was positively correlated with Cr (53.1%, 72.3%, 68.0%, P<0.05) and negatively correlated with eGFR (71.6%, 68.5%, 53.1%, P<0.05). the higher the Cr, the higher the predominance ratio of CA (T1: reference; T2:OR. 2.166,95%CI:1.454,3.225; T3:OR:1.677, 95%CI:1.075, 2.616; P<0.05), along with an eGFR of 66.9% and 52.0% in terms of sensitivity and specificity, with a 95% CI of 0.562-0.644.

Conclusion

Within our experimental sample, a noteworthy observation emerged: Creatinine (Cr) exhibited a positive correlation with the prevalence of individuals affected by carotid atherosclerosis (CA), underscoring a potential connection between Cr levels and CA incidence. Conversely, the estimated Glomerular Filtration Rate (eGFR) demonstrated a negative correlation with the occurrence of CA, implying that lower eGFR values might be associated with an increased likelihood of CA development.

Actoeside mitigated the renal proximal tubule cells damage triggered by high glucose through miR-766/VCAM1/NF-κB signalling pathway

CONTEXT

Diabetic nephropathy (DN) triggered by diabetes mellitus is one of the primary causes of end-stage renal failure worldwide.

OBJECTIVE

This study intends to explore the function and potential mechanism of actoeside on renal proximal tubule (HK-2) cells damage induced by high-glucose (HG).

METHODS

The DN model was established in HK-2 cells with 30 mM HG treatment. The viability, apoptosis and inflammation of HK-2 cells were analysed severally via CCK-8, flow cytomery and ELISA. The key factors related to NF-κB were detected by western blotting.

RESULTS

Actoeside attenuated the HG-induced HK-2 cells damage. The differentially expression of miR-766 and VCAM1 in DN patients was reversed by actoeside. Moreover, the increased phosphorylation levels of p65 NF-κB/IκBα induced by HG were attenuated by actoeside.

CONCLUSIONS

Actoeside promoted the growth and repressed the apoptosis and inflammation of HK-2 cells via miR-766/VCAM1/NF-κB signalling pathway, affording a promising idea for the treatment of DN.

Pathomechanisms of Diabetic Kidney Disease

The worldwide occurrence of diabetic kidney disease (DKD) is swiftly rising, primarily attributed to the growing population of individuals affected by type 2 diabetes. This surge has been transformed into a substantial global concern, placing additional strain on healthcare systems already grappling with significant demands. The pathogenesis of DKD is intricate, originating with hyperglycemia, which triggers various mechanisms and pathways: metabolic, hemodynamic, inflammatory, and fibrotic which ultimately lead to renal damage. Within each pathway, several mediators contribute to the development of renal structural and functional changes. Some of these mediators, such as inflammatory cytokines, reactive oxygen species, and transforming growth factor β are shared among the different pathways, leading to significant overlap and interaction between them. While current treatment options for DKD have shown advancement over previous strategies, their effectiveness remains somewhat constrained as patients still experience residual risk of disease progression. Therefore, a comprehensive grasp of the molecular mechanisms underlying the onset and progression of DKD is imperative for the continued creation of novel and groundbreaking therapies for this condition. In this review, we discuss the current achievements in fundamental research, with a particular emphasis on individual factors and recent developments in DKD treatment.

The Role of Autophagy in Type 2 Diabetic Kidney Disease Management

Diabetic kidney disease (DKD), or diabetic nephropathy (DN), is one of the most prevalent complications of type 2 diabetes mellitus (T2DM) and causes severe burden on the general welfare of T2DM patients around the world. While several new agents have shown promise in treating this condition and potentially halting the progression of the disease, more work is needed to understand the complex regulatory network involved in the disorder. Recent studies have provided new insights into the connection between autophagy, a physiological metabolic process known to maintain cellular homeostasis, and the pathophysiological pathways of DKD. Typically, autophagic activity plays a role in DKD progression mainly by promoting an inflammatory response to tissue damage, while both overactivated and downregulated autophagy worsen disease outcomes in different stages of DKD. This correlation demonstrates the potential of autophagy as a novel therapeutic target for the disease, and also highlights new possibilities for utilizing already available DN-related medications. In this review, we summarize findings on the relationship between autophagy and DKD, and the impact of these results on clinical management strategies.

Modeling diabetic endothelial dysfunction with patient-specific induced pluripotent stem cells

Diabetes is a known risk factor for various cardiovascular complications, mediated by endothelial dysfunction. Despite the high prevalence of this metabolic disorder, there is a lack of in vitro models that recapitulate the complexity of genetic and environmental factors associated with diabetic endothelial dysfunction. Here, we utilized human induced pluripotent stem cell (iPSC)-derived endothelial cells (ECs) to develop in vitro models of diabetic endothelial dysfunction. We found that the diabetic phenotype was recapitulated in diabetic patient-derived iPSC-ECs, even in the absence of a diabetogenic environment. Subsequent exposure to culture conditions that mimic the diabetic clinical chemistry induced a diabetic phenotype in healthy iPSC-ECs but did not affect the already dysfunctional diabetic iPSC-ECs. RNA-seq analysis revealed extensive transcriptome-wide differences between cells derived from healthy individuals and diabetic patients. The in vitro disease models were used as a screening platform which identified angiotensin receptor blockers (ARBs) that improved endothelial function in vitro for each patient. In summary, we present in vitro models of diabetic endothelial dysfunction using iPSC technology, taking into account the complexity of genetic and environmental factors in the metabolic disorder. Our study provides novel insights into the pathophysiology of diabetic endothelial dysfunction and highlights the potential of iPSC-based models for drug discovery and personalized medicine.

METTL14 promotes the development of diabetic kidney disease by regulating m6A modification of TUG1

BACKGROUND

Diabetic kidney disease (DKD) is one of the most common diabetic complications. Endoplasmic reticulum stress (ERS) is an important step for renal tubular epithelial cell apoptosis during DKD progression. Herein, the role and regulatory mechanism of METTL14 in ERS during DKD progression were investigated.

METHODS

DKD animal and cell models were established by streptozotocin (STZ) and high glucose (HG), respectively. HE and Masson staining were performed to analyze renal lesions in DKD mouse. Cell viability and proliferation were determined by MTT and EdU staining, respectively. HK2 cell apoptosis was analyzed by flow cytometry. TUG1 m6A level was determined by Me-RIP. The interaction between TUG1, LIN28B and MAPK1 was analyzed by RIP and RNA pull-down assays.

RESULTS

HG stimulation promoted apoptosis and increased ERS marker proteins (GRP78, CHOP and caspase12) expression in HK2 cells, while these changes were reversed by METTL14 knockdown. METTL14 inhibited TUG1 stability and expression level in an m6A-dependent manner. As expected, TUG1 knockdown abrogated METTL14 knockdown's inhibition on HG-induced HK2 cell apoptosis and ERS. In addition, TUG1 inactivated MAPK1/ERK signaling by binding with LIN28B. And TUG1 overexpression's repression on HG-induced HK2 cell apoptosis and ERS was abrogated by MAPK1 signaling activation. Meanwhile, METTL14 knockdown or TUG1 overexpression protected against STZ-induced renal lesions and renal fibrosis in DKD mouse.

CONCLUSION

METTL14 promoted renal tubular epithelial cell apoptosis and ERS by activating MAPK/ERK pathway through m6A modification of TUG1, thereby accelerating DKD progression.

SETD2 deficiency promotes renal fibrosis through the TGF-β/Smad signalling pathway in the absence of VHL

BACKGROUND

Renal fibrosis is the final development pathway and the most common pathological manifestation of chronic kidney disease. Epigenetic alteration is a significant intrinsic factor contributing to the development of renal fibrosis. SET domain-containing 2 (SETD2) is the sole histone H3K36 trimethyltransferase, catalysing H3K36 trimethylation. There is evidence that SETD2-mediated epigenetic alterations are implicated in many diseases. However, it is unclear what role SETD2 plays in the development of renal fibrosis.

METHODS

Kidney tissues from mice as well as HK2 cells were used as research subjects. Clinical databases of patients with renal fibrosis were analysed to investigate whether SETD2 expression is reduced in the occurrence of renal fibrosis. SETD2 and Von Hippel-Lindau (VHL) double-knockout mice were used to further investigate the role of SETD2 in renal fibrosis. Renal tubular epithelial cells isolated from mice were used for RNA sequencing and chromatin immunoprecipitation sequencing to search for molecular signalling pathways and key molecules leading to renal fibrosis in mice. Molecular and cell biology experiments were conducted to analyse and validate the role of SETD2 in the development of renal fibrosis. Finally, rescue experiments were performed to determine the molecular mechanism of SETD2 deficiency in the development of renal fibrosis.

RESULTS

SETD2 deficiency leads to severe renal fibrosis in VHL-deficient mice. Mechanically, SETD2 maintains the transcriptional level of Smad7, a negative feedback factor of the transforming growth factor-β (TGF-β)/Smad signalling pathway, thereby preventing the activation of the TGF-β/Smad signalling pathway. Deletion of SETD2 leads to reduced Smad7 expression, which results in activation of the TGF-β/Smad signalling pathway and ultimately renal fibrosis in the absence of VHL.

CONCLUSIONS

Our findings reveal the role of SETD2-mediated H3K36me3 of Smad7 in regulating the TGF-β/Smad signalling pathway in renal fibrogenesis and provide an innovative insight into SETD2 as a potential therapeutic target for the treatment of renal fibrosis.

Polymorphic variations and mRNA expression of the genes encoding interleukins as well as enzymes of oxidative and nitrative stresses as a potential risk of nephrolithiasis development

Urolithiasis is one of the most common urological diseases worldwide with an unclear aetiology. However, a growing body of evidence suggests the potential role of molecular disturbances of the inflammation as well as oxidative and nitrative stresses, in the pathogenesis of urolithiasis. Therefore, we aimed to detect the potential association between six selected single-nucleotide polymorphisms (SNPs) and the development of nephrolithiasis. Moreover, we verified the association of urolithiasis development and mRNA expression of IL-6, IL-8, SOD2, and NOS2 in peripheral blood mononuclear cells (PBMCs). Total genomic DNA and mRNA were isolated from the peripheral blood of 112 patients with urolithiasis and 114 healthy subjects. Using Taq-Man® probes, we genotyped the following SNPs: rs1800797 and rs2069845 in IL-6, rs2227307 in IL-8, rs4880 in SOD2, rs2297518 and rs2779249 in NOS2. In turn, the evaluation of mRNA expression was performed using real-time PCR and 2-ΔCt methods. We found that the C/T genotype of the c.47 T>C-SOD2 SNP increased the frequency of urolithiasis occurrence whereas the T/T homozygote of the same polymorphism decreased the risk of urolithiasis development in the Polish population. Moreover, our study confirmed that patients with urolithiasis were characterised by decreased IL-6, IL-8, and SOD2 mRNA expression levels compared to the controls. In conclusion, our results suggest that polymorphic variants and changes in mRNA expression of IL-6, IL8, SOD2, and NOS2 may be involved in the pathophysiology of urolithiasis.

Acteoside protects podocyte against apoptosis through regulating AKT/GSK-3β signaling pathway in db/db mice

BACKGROUND

Podocyte apoptosis is one of the important pathological mechanisms of diabetic kidney disease (DKD). Acteoside (Act), a major active component of Rehmannia glutinosa leaves total glycoside, has a strong renoprotective action. Our study aims to demonstrate Act's renoprotective actions in db/db mice.

METHODS

We adopted C57BLKS/J db/db mice as DKD animal models. After 8 weeks of Act administration, the 24-hour urine albumin, renal function index, and blood lipid levels were quantified using matching kits. Renal pathology was evaluated by HE and PAS staining. The podocyte damage and apoptosis-related signaling pathway were observed by using immunohistochemistry, western blot, and TUNEL staining.

RESULTS

The albuminuria of db/db mice was reduced from 391 ug/24 h to 152 ug/24 h, and renal pathology changes were alleviated after Act administration. The western blot and immunohistochemistry showed that Act treatment upregulated the synaptopodin and podocin expression compared with db/db mice, while the TUNEL staining indicated podocyte apoptosis was inhibited. The B-cell lymphoma-2 (Bcl-2) level was upregulated in the Act group, but cleaved caspase-3 and Bcl-2 associated X protein (Bax) expression declined, while the protein kinase B/glycogen synthase kinase-3β (AKT/GSK-3β) signaling pathway was repressed.

CONCLUSIONS

By inhibiting the AKT/GSK-3β signaling pathway, Act protected podocytes from apoptosis, decreasing the urine albumin of db/db mice and delaying the course of DKD.

The protective mechanism of Dehydromiltirone in diabetic kidney disease is revealed through network pharmacology and experimental validation

Background: Salvia miltiorrhiza (SM) is an effective traditional Chinese medicine for treating DKD, but the exact mechanism is elusive. In this study, we aimed to investigate and confirm the method underlying the action of the active components of SM in the treatment of DKD. Methods: Renal tissue transcriptomics and network pharmacology of DKD patients was performed to identify the active components of SM and the disease targets of DKD. Next, the point of convergence among these three groups was studied. Potential candidate genes were identified and analyzed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). The component-target networks were modelled and visualized with Cytoscape. In addition, docking studies were performed to validate our potential target predictions. Lastly, in vitro and in vivo experiments were performed to understand the role of Dehydromiltirone (DHT), the active component of SM, in the phenotypic switching of mesangial cells. Results: Transcriptomics of DKD patients' renal tissues screened 4,864 differentially expressed genes. Eighty-nine active components of SM and 161 common targets were found. Functional enrichment analysis indicated that 161 genes were enriched in apoptosis, the PI3K-AKT signaling pathway, and the AGE-RAGE signaling pathway in diabetes complications. Molecular docking and molecular dynamic simulations show that DHT can bind to functional PIK3CA pockets, thereby becoming a possible inhibitor of PIK3CA. In vitro study demonstrated that DHT reduced the expression of phenotypic switching markers α-SMA, Col-I, and FN in HMCs by downregulating the over-activation of the PI3K-AKT signaling pathway through the inhibition of PIK3CA. Furthermore, the DKD mouse model confirmed that DHT could reduce proteinuria and improve glomerular hypertrophy in vivo. Conclusion: DHT was identified as the key active component of SM, and its therapeutic effect on DKD was achieved by inhibiting the phenotypic switching of mesangial cells via the PIK3CA signaling pathway.

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

Background

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

Methods

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

Results

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

Conclusion

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

Long non-coding RNA lncMGC mediates the expression of TGF-β-induced genes in renal cells via nucleosome remodelers

Background: MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) play key roles in diabetic kidney disease (DKD). The miR-379 megacluster of miRNAs and its host transcript lnc-megacluster (lncMGC) are regulated by transforming growth factor-β (TGF-β), increased in the glomeruli of diabetic mice, and promote features of early DKD. However, biochemical functions of lncMGC are unknown. Here, we identified lncMGC-interacting proteins by in vitro-transcribed lncMGC RNA pull down followed by mass spectrometry. We also created lncMGC-knockout (KO) mice by CRISPR-Cas9 editing and used primary mouse mesangial cells (MMCs) from the KO mice to examine the effects of lncMGC on the gene expression related to DKD, changes in promoter histone modifications, and chromatin remodeling. Methods: In vitro-transcribed lncMGC RNA was mixed with lysates from HK2 cells (human kidney cell line). lncMGC-interacting proteins were identified by mass spectrometry. Candidate proteins were confirmed by RNA immunoprecipitation followed by qPCR. Cas9 and guide RNAs were injected into mouse eggs to create lncMGC-KO mice. Wild-type (WT) and lncMGC-KO MMCs were treated with TGF-β, and RNA expression (by RNA-seq and qPCR) and histone modifications (by chromatin immunoprecipitation) and chromatin remodeling/open chromatin (by Assay for Transposase-Accessible Chromatin using sequencing, ATAC-seq) were examined. Results: Several nucleosome remodeling factors including SMARCA5 and SMARCC2 were identified as lncMGC-interacting proteins by mass spectrometry, and confirmed by RNA immunoprecipitation-qPCR. MMCs from lncMGC-KO mice showed no basal or TGF-β-induced expression of lncMGC. Enrichment of histone H3K27 acetylation and SMARCA5 at the lncMGC promoter was increased in TGF-β-treated WT MMCs but significantly reduced in lncMGC-KO MMCs. ATAC peaks at the lncMGC promoter region and many other DKD-related loci including Col4a3 and Col4a4 were significantly lower in lncMGC-KO MMCs compared to WT MMCs in the TGF-β-treated condition. Zinc finger (ZF), ARID, and SMAD motifs were enriched in ATAC peaks. ZF and ARID sites were also found in the lncMGC gene. Conclusion: lncMGC RNA interacts with several nucleosome remodeling factors to promote chromatin relaxation and enhance the expression of lncMGC itself and other genes including pro-fibrotic genes. The lncMGC/nucleosome remodeler complex promotes site-specific chromatin accessibility to enhance DKD-related genes in target kidney cells.

LncRNA 1500026H17Rik knockdown ameliorates high glucose-induced mouse podocyte injuries through the miR-205-5p/EGR1 pathway

BACKGROUND

Podocyte injuries and dysfunctions contribute to the development of diabetic nephropathy (DN). This study aimed to investigate the role and novel mechanism of lncRNA 1500026H17Rik in high glucose (HG)-treated podocytes.

METHODS

DN mice were induced by streptozotocin, and DN in vitro models were constructed in mouse podocytes treated with HG. The expression of fibrosis-related proteins and early growth response protein 1 (EGR1) was detected by western blot. The expression of 1500026H17Rik, miR-205-5p and EGR1 mRNA was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell apoptosis was monitored by flow cytometry assay. Oxidative stress was assessed according to the levels of superoxide dismutase (SOD), malondialdehyde (MDA) and reactive oxygen species (ROS). Inflammatory response was assessed according to the releases of interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). The target relationship between miR-205-5p and 1500026H17Rik or EGR1 was validated by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay.

RESULTS

1500026H17Rik was upregulated in DN mice and HG-induced podocytes. 1500026H17Rik knockdown alleviated podocyte apoptosis, fibrosis, oxidative stress and inflammation induced by HG. MiR-205-5p was a target of 1500026H17Rik, and EGR1 was a downstream target of miR-205-5p. Rescue experiments presented that miR-205-5p inhibition reversed the effects of 1500026H17Rik knockdown. Moreover, miR-205-5p restoration also ameliorated HG-induced cell injuries, which were overturned by EGR1 overexpression. In addition, EGR1 overexpression recovered podocyte apoptosis, fibrosis, oxidative stress and inflammation weakened by 1500026H17Rik knockdown.

CONCLUSION

1500026H17Rik knockdown alleviated HG-induced podocyte injuries, including apoptosis, fibrosis, oxidative stress and inflammation, by governing the miR-205-5p/EGR1 pathway, thus involving in DN development.

Urinary microRNA in Diabetic Kidney Disease: A Literature Review

Diabetic kidney disease is the most common primary disease of end-stage kidney disease globally; however, a sensitive and accurate biomarker to predict this disease remains awaited. microRNAs are endogenous single-stranded noncoding RNAs that have intervened in different post-transcriptional regulations of various cellular biological functions. Previous literatures have reported its potential role in the pathophysiology of diabetic kidney disease, including regulation of Transforming Growth Factor-β1-mediated fibrosis, extracellular matrix and cell adhesion proteins, cellular hypertrophy, growth factor, cytokine production, and redox system activation. Urinary microRNAs have emerged as a novel, non-invasive liquid biopsy for disease diagnosis. In this review, we describe the available experimental and clinical evidence of urinary microRNA in the context of diabetic kidney disease and discuss the future application of microRNA in routine practice.

Epigenetics and endoplasmic reticulum in podocytopathy during diabetic nephropathy progression

Proteinuria or nephrotic syndrome are symptoms of podocytopathies, kidney diseases caused by direct or indirect podocyte damage. Human health worldwide is threatened by diabetic nephropathy (DN), the leading cause of end-stage renal disease (ESRD) in the world. DN development and progression are largely dependent on inflammation. The effects of podocyte damage on metabolic disease and inflammatory disorders have been documented. Epigenetic and endoplasmic reticulum (ER) stress are also evident in DN. Targeting inflammation pathway and ER stress in podocytes may be a prospective therapy to prevent the progression of DN. Here, we review the mechanism of epigenetics and ER stress on podocyte inflammation and apoptosis, and discuss the potential amelioration of podocytopathies by regulating epigenetics and ER stress as well as by targeting inflammatory signaling, which provides a theoretical basis for drug development to ameliorate DN.

Natural swietenine attenuates diabetic nephropathy by regulating the NF-κB/NLRP3/Caspase-1 signaling pathways: In vivo and in vitro study

Swietenine (Swi), isolated from Swietenia macrophylla King ameliorates inflammation and oxidative stress, and diabetic nephropathy has a close connection with them. So the effects of Swi on diabetic nephropathy and its mechanism of action was explored. We divided human mesangial cells into five groups and determined the expression of NF-κB and NLRP3 inflammasomes in each group. The levels of inflammatory factors IL-1β and IL-18 were also measured. To explore the relationship between NF-κB and NLRP3, we added PDTC, a specific NF-κB inhibitor, and LPS, and divided the experimental groups into seven groups. We measured the expressions of NF-κB and NLRP3, and then added MCC950, a specific inhibitor of NLRP3 and LPS, the expression of NLRP3, Caspase-1, and IL-1β and IL-18 were measured. Animals divided into four groups and administered over 8 weeks. Protein excretion, creatinine, urea nitrogen, and uric acid were measured. Swi down regulated the expression of NF-κB, NLRP3, and Caspase-1. It reduced the levels of IL-1β and IL-18. PDTC decreased the expression of NF-κB and NLRP3. Compared with the HG + PDTC group, the expression of NF-κB and NLRP3 in the HG + Swi + PDTC group decreased significantly. After adding lipopolysaccharide, the expression of NF-κB and NLRP3 increased, but this situation was reversed after adding Swi. After adding LPS, the expression of NLRP3 and Caspase-1 increased, and the levels of IL-1β and IL-18 also increased, but this situation was reversed after the addition of Swi. Swi significantly improved the renal function of mice with diabetic nephropathy and inhibited the activation of NF-κB and the NLRP3 inflammasome and reduced inflammation by regulating the NF-κB/NLRP3/Caspase-1 signaling pathway, thereby improving diabetic nephropathy.

Paeoniflorin binds to VEGFR2 to restore autophagy and inhibit apoptosis for podocyte protection in diabetic kidney disease through PI3K-AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Paeoniflorin (PF) was found to exhibit renal protection from diabetic kidney disease (DKD) in previous trials, but its specific mechanism remains to be elucidated.

AIM OF THE STUDY

This study furtherly explored the specific mechanism of PF in protect podocyte injury in DKD.

MATERIALS AND METHODS

We observed the effects of PF on renal tissue and podocytes in DKD by constructing the vitro and vivo models after measuring the pharmacokinetic characteristics of PF. Target proteins of PF were found through target prediction, and verified by molecular docking, CESTA, and SPR, and then furtherly explored the downstream regulation mechanism related to podocyte autophagy and apoptosis by network prediction and co-immunoprecipitation. Finally, by using the target protein inhibitor in vivo and knocking down the target protein gene in vitro, it was verified that PF played a role in regulating autophagy and apoptosis through the target protein in diabetic nephropathy.

RESULTS

This study found that in STZ-induced mice model, PF could improve the renal biochemical and pathological damage and podocyte injure (p < 0.05), upregulate autophagy activity (p < 0.05), but inhibit apoptosis (p < 0.01). Vascular endothelial growth factor receptor 2 (VEGFR2), predicted as the target of PF, directly bind with PF reflected by molecular docking and surface plasmon resonance detection. Animal studies demonstrated that VEGFR2 inhibitors have a protective effect similar to that of PF on DKD. Network prediction and co-immunoprecipitation further confirmed that VEGFR2 was able to bind PIK3CA to regulate PI3K-AKT signaling pathway. Furthermore, PF downregulated the phosphorylation of PI3K and AKT (p < 0.05). In vitro, similarly to autophagy inhibitors, PF was also found to improve podocyte markers (p < 0.05) and autophagy activity (p < 0.05), decrease caspase 3 protein (p < 0.05) and further inhibited VEGFR2-PI3K-AKT activity (p < 0.05). Finally, the results of VEGFR2 knockdown were similar to the effect of PF in HG-stimulated podocytes.

CONCLUSION

In conclusion, PF restores autophagy and inhibits apoptosis by targeting the VEGFR2-mediated PI3K-AKT pathway to improve renal injury in DKD, that provided a theoretical basis for PF treatment in DKD.

miRNAs as Biomarkers in Diabetes: Moving towards Precision Medicine

Diabetes mellitus (DM) is a complex metabolic disease with many specifically related complications. Early diagnosis of this disease could prevent the progression to overt disease and its related complications. There are several limitations to using existing biomarkers, and between 24% and 62% of people with diabetes remain undiagnosed and untreated, suggesting a large gap in current diagnostic practices. Early detection of the percentage of insulin-producing cells preceding loss of function would allow for effective therapeutic interventions that could delay or slow down the onset of diabetes. MicroRNAs (miRNAs) could be used for early diagnosis, as well as for following the progression and the severity of the disease, due to the fact of their pancreatic specific expression and stability in various body fluids. Thus, many studies have focused on the identification and validation of such groups or "signatures of miRNAs" that may prove useful in diagnosing or treating patients. Here, we summarize the findings on miRNAs as biomarkers in diabetes and those associated with direct cellular reprogramming strategies, as well as the relevance of miRNAs that act as a bidirectional switch for cell therapy of damaged pancreatic tissue and the studies that have measured and tracked miRNAs as biomarkers in insulin resistance are addressed.

The Latest Research Advances of Danggui Buxue Tang as an Effective Prescription for Various Diseases: A Comprehensive Review

Danggui Buxue Tang (DBT) is composed of Astragali Radix and Angelicae Sinensis Radix in a weight ratio of 5:1. The recipe of the decoction is simple, and DBT has been widely used in the treatment of blood deficiency syndrome for more than 800 years in China. Studies on its chemical constituents show that saponins, flavonoids, volatile oils, organic acids, and polysaccharides are the main components of DBT. Many techniques such as third-generation sequencing, PCR-denaturing gradient gel electrophoresis, and HPLC-MS have been used for the quality control of DBT. DBT has a wide range of biological activities, including blood enhancement, antagonizing diabetic nephropathy, cardiovascular protection, immunity stimulation, estrogen-like effect, and antifibrosis, among others. In this paper, we summarize the recent research advances of DBT in terms of its components, pharmacological activities, and possible mechanisms of action as well as provide suggestions for further research.

Hybrid molecules based on caffeic acid as potential therapeutics: A focused review

Caffeic acid-based compounds possess a high degree of structural diversity and show a variety of pharmacological properties, providing a useful framework for the discovery of new therapeutic agents. They are well-known analogues of antioxidants found in many natural products and synthetic compounds. The present review surveys the recent developments in structure-activity relationships (SAR) and mechanism of action (MOA) of various caffeic acid-containing compounds that play important roles in the design and synthesis of new bioactive molecules with antioxidant, antidiabetic, antiviral, antibacterial, anticancer, anti-inflammatory, and other properties. This review should provide inspiration to scientists in the research fields of organic synthesis and medicinal chemistry related to the development of new antioxidants with versatile therapeutic potential.

The mechanisms of glycolipid metabolism disorder on vascular injury in type 2 diabetes

Patients with diabetes have severe vascular complications, such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, and neuropathy. Devastating vascular complications lead to increased mortality, blindness, kidney failure, and decreased overall quality of life in people with type 2 diabetes (T2D). Glycolipid metabolism disorder plays a vital role in the vascular complications of T2D. However, the specific mechanism of action remains to be elucidated. In T2D patients, vascular damage begins to develop before insulin resistance and clinical diagnosis. Endothelial dysregulation is a significant cause of vascular complications and the early event of vascular injury. Hyperglycemia and hyperlipidemia can trigger inflammation and oxidative stress, which impair endothelial function. Furthermore, during the pathogenesis of T2D, epigenetic modifications are aberrant and activate various biological processes, resulting in endothelial dysregulation. In the present review, we provide an overview and discussion of the roles of hyperglycemia- and hyperlipidemia-induced endothelial dysfunction, inflammatory response, oxidative stress, and epigenetic modification in the pathogenesis of T2D. Understanding the connections of glucotoxicity and lipotoxicity with vascular injury may reveal a novel potential therapeutic target for diabetic vascular complications.

Oncoprotein DJ-1 interacts with mTOR complexes to effect transcription factor Hif1α-dependent expression of collagen I (α2) during renal fibrosis

Proximal tubular epithelial cells respond to transforming growth factor β (TGFβ) to synthesize collagen I (α2) during renal fibrosis. The oncoprotein DJ-1 has previously been shown to promote tumorigenesis and prevent apoptosis of dopaminergic neurons; however, its role in fibrosis signaling is unclear. Here, we show TGFβ-stimulation increased expression of DJ-1, which promoted noncanonical mTORC1 and mTORC2 activities. We show DJ-1 augmented the phosphorylation/activation of PKCβII, a direct substrate of mTORC2. In addition, coimmunoprecipitation experiments revealed association of DJ-1 with Raptor and Rictor, exclusive subunits of mTORC1 and mTORC2, respectively, as well as with mTOR kinase. Interestingly, siRNAs against DJ-1 blocked TGFβ-stimulated expression of collagen I (α2), while expression of DJ-1 increased expression of this protein. In addition, expression of dominant negative PKCβII and siRNAs against PKCβII significantly inhibited TGFβ-induced collagen I (α2) expression. In fact, constitutively active PKCβII abrogated the effect of siRNAs against DJ-1, suggesting a role of PKCβII downstream of this oncoprotein. Moreover, we demonstrate expression of collagen I (α2) stimulated by DJ-1 and its target PKCβII is dependent on the transcription factor hypoxia-inducible factor 1α (Hif1α). Finally, we show in the renal cortex of diabetic rats that increased TGFβ was associated with enhanced expression of DJ-1 and activation of mTOR and PKCβII, concomitant with increased Hif1α and collagen I (α2). Overall, we identified that DJ-1 affects TGFβ-induced expression of collagen I (α2) via an mTOR-, PKCβII-, and Hif1α-dependent mechanism to regulate renal fibrosis.

miRNA-486-5p: signaling targets and role in non-malignant disease

MicroRNAs (miRNAs) are short non-coding RNAs, highly conserved between species, that are powerful regulators of gene expression. Aberrant expression of miRNAs alters biological processes and pathways linked to human disease. miR-486-5p is a muscle-enriched miRNA localized to the cytoplasm and nucleus, and is highly abundant in human plasma and enriched in small extracellular vesicles. Studies of malignant and non-malignant diseases, including kidney diseases, have found correlations with circulating miR-486-5p levels, supporting its role as a potential biomarker. Pre-clinical studies of non-malignant diseases have identified miR-486-5p targets that regulate major signaling pathways involved in cellular proliferation, migration, angiogenesis, and apoptosis. Validated miR-486-5p targets include phosphatase and tensin homolog (PTEN) and FoXO1, whose suppression activates phosphatidyl inositol-3-kinase (PI3K)/Akt signaling. Targeting of Smad1/2/4 and IGF-1 by miR-486-5p inhibits transforming growth factor (TGF)-β and insulin-like growth factor-1 (IGF-1) signaling, respectively. Other miR-486-5p targets include matrix metalloproteinase-19 (MMP-19), Sp5, histone acetyltransferase 1 (HAT1), and nuclear factor of activated T cells-5 (NFAT5). In this review, we examine the biogenesis, regulation, validated gene targets and biological effects of miR-486-5p in non-malignant diseases.

Albumin-induced premature senescence in human renal proximal tubular cells and its relationship with intercellular fibrosis

The presence of senescent cells is associated with renal fibrosis. This study aims to investigate the effect of albumin-induced premature senescence on tubulointerstitial fibrosis and its possible mechanism in vitro. Different concentrations of bovine serum albumim (BSA) with or without si-p21 are used to stimulate HK-2 cells for 72 h, and SA-β-gal activity, senescence-associated secretory phenotypes (SASPs), LaminB1 are used as markers of senescence. Immunofluorescence staining is performed to characterize the G2/M phase arrest between the control and BSA groups. Alterations in the DNA damage marker γ-H2AX, fibrogenesis, and associated proteins at the G2/M phase, such as p21, p-CDC25C and p-CDK1, are evaluated. Compared with those in the control group, the SA-β-gal activity, SASP, and γ-H2AX levels are increased in the BSA group, while the level of LaminB1 is decreased. Meanwhile, HK-2 cells blocked at the G2/M phase are significantly increased under the stimulation of BSA, and the levels of p21, p-CDC25C and p-CDK1, as well as fibrogenesis are also increased. When p21 expression is inhibited, the levels of p-CDC25C and p-CDK1 are decreased and the G2/M phase arrest is improved, which decreases the production of fibrogenesis. In conclusion, BSA induces renal tubular epithelial cell premature senescence, which regulates the G2/M phase through the CDC25C/CDK1 pathway, leading to tubulointerstitial fibrosis.

A Deep Insight Into Regulatory T Cell Metabolism in Renal Disease: Facts and Perspectives

Kidney disease encompasses a complex set of diseases that can aggravate or start systemic pathophysiological processes through their complex metabolic mechanisms and effects on body homoeostasis. The prevalence of kidney disease has increased dramatically over the last two decades. CD4⁺CD25⁺ regulatory T (Treg) cells that express the transcription factor forkhead box protein 3 (Foxp3) are critical for maintaining immune homeostasis and preventing autoimmune disease and tissue damage caused by excessive or unnecessary immune activation, including autoimmune kidney diseases. Recent studies have highlighted the critical role of metabolic reprogramming in controlling the plasticity, stability, and function of Treg cells. They are also likely to play a vital role in limiting kidney transplant rejection and potentially promoting transplant tolerance. Metabolic pathways, such as mitochondrial function, glycolysis, lipid synthesis, glutaminolysis, and mammalian target of rapamycin (mTOR) activation, are involved in the development of renal diseases by modulating the function and proliferation of Treg cells. Targeting metabolic pathways to alter Treg cells can offer a promising method for renal disease therapy. In this review, we provide a new perspective on the role of Treg cell metabolism in renal diseases by presenting the renal microenvironment、relevant metabolites of Treg cell metabolism, and the role of Treg cell metabolism in various kidney diseases.

Fraxin Promotes the Activation of Nrf2/ARE Pathway via Increasing the Expression of Connexin43 to Ameliorate Diabetic Renal Fibrosis

Diabetic nephropathy (DN) is quickly becoming the largest cause of end-stage renal disease (ESRD) in diabetic patients, as well as a major source of morbidity and mortality. Our previous studies indicated that the activation of Nrf2/ARE pathway via Connexin43 (Cx43) considerably contribute to the prevention of oxidative stress in the procession of DN. Fraxin (Fr), the main active glycoside of Fraxinus rhynchophylla Hance, has been demonstrated to possess many potential pharmacological activities. Whereas, whether Fr could alleviate renal fibrosis through regulating Cx43 and consequently facilitating the activation of Nrf2/ARE pathway needs further investigation. The in vitro results showed that: 1) Fr increased the expression of antioxidant enzymes including SOD1 and HO-1 to inhibit high glucose (HG)-induced fibronectin (FN) and inflammatory cell adhesion molecule (ICAM-1) overexpression; 2) Fr exerted antioxidant effect through activating the Nrf2/ARE pathway; 3) Fr significantly up-regulated the expression of Cx43 in HG-induced glomerular mesangial cells (GMCs), while the knock down of Cx43 largely impaired the activation of Nrf2/ARE pathway induced by Fr; 4) Fr promoted the activation of Nrf2/ARE pathway via regulating the interaction between Cx43 and AKT. Moreover, in accordance with the results in vitro, elevated levels of Cx43, phosphorylated-AKT, Nrf2 and downstream antioxidant enzymes related to Nrf2 were observed in the kidneys of Fr-treated group compared with model group. Importantly, Fr significantly improved renal dysfunction pathological changes of renal fibrosis in diabetic db/db mice. Collectively, Fr could increase the Cx43-AKT-Nrf2/ARE pathway activation to postpone the diabetic renal fibrosis and the up-regulation of Cx43 is probably a novel mechanism in this process.

Circulating miRNAs in Type 2 Diabetic Patients with and without Albuminuria in Malaysia

INTRODUCTION

Diabetic kidney disease (DKD) remains the leading cause of chronic kidney disease. Dysregulation of circulating miRNAs has been reported, suggesting their pathological roles in DKD. This study aimed to investigate differentially expressed miRNAs in the sera of type 2 diabetes mellitus (T2DM) patients with and without albuminuria in a selected Malaysian population.

METHOD

Forty-one T2DM patients on follow-up at a community clinic were divided into normo-(NA), micro-(MIC), and macroalbuminuria (MAC) groups. Differential levels of miRNAs in 12 samples were determined using the pathway-focused (human fibrosis) miScript miRNA qPCR array and was validated in 33 samples, using the miScript custom qPCR array (CMIHS02742) (Qiagen GmbH, Hilden, Germany).

RESULTS

Trends of upregulation of 3 miRNAs in the serum, namely, miR-874-3p, miR-101-3p, and miR-145-5p of T2DM patients with MAC compared to those with NA. Statistically significant upregulation of miR-874-3p (p = 0.04) and miR-101-3p (p = 0.01) was seen in validation cohort. Significant negative correlations between the estimated glomerular filtration rate (eGFR) and miR-874-3p (p = 0.05), miR-101-3p (p = 0.03), and miR-145-5p (p = 0.05) as well as positive correlation between miR-874-3p and age (p = 0.03) were shown by Pearson's correlation coefficient analysis.

CONCLUSION

Upregulation of previously known miRNA, namely, miR-145-5p, and possibly novel ones, namely, miR-874-3p and miR-101-3p in the serum of T2DM patients, was found in this study. There was a significant correlation between the eGFR and these miRNAs. The findings of this study have provided encouraging evidence to further investigate the putative roles of these differentially expressed miRNAs in DKD.

Epigenetics and Beyond: Targeting Histone Methylation to Treat Type 2 Diabetes Mellitus

Diabetes mellitus is a global public health challenge with high morbidity. Type 2 diabetes mellitus (T2DM) accounts for 90% of the global prevalence of diabetes. T2DM is featured by a combination of defective insulin secretion by pancreatic β-cells and the inability of insulin-sensitive tissues to respond appropriately to insulin. However, the pathogenesis of this disease is complicated by genetic and environmental factors, which needs further study. Numerous studies have demonstrated an epigenetic influence on the course of this disease via altering the expression of downstream diabetes-related proteins. Further studies in the field of epigenetics can help to elucidate the mechanisms and identify appropriate treatments. Histone methylation is defined as a common histone mark by adding a methyl group (-CH3) onto a lysine or arginine residue, which can alter the expression of downstream proteins and affect cellular processes. Thus, in tthis study will discuss types and functions of histone methylation and its role in T2DM wilsed. We will review the involvement of histone methyltransferases and histone demethylases in the progression of T2DM and analyze epigenetic-based therapies. We will also discuss the potential application of histone methylation modification as targets for the treatment of T2DM.

Effects of acteoside on the expressions of MCP-1 and TGF-β1 in the diabetic nephropathy mice

Objective: Immune inflammatory cells and cytokines play an important role in the occurrence and development of diabetic nephropathy (DN). Acteoside has been reported to regulate the inflammation and immune response. The study aims to investigate the effects of acteoside on the expressions of MCP-1 and TGF-β1 on nephropathy in diabetic mice.

Methods: C57BL/6J mice in the model group were given a single intraperitoneal injection of STZ (150 mg/kg). Model mice were divided randomly into two groups: 5 without treatment, 5 treated with acteoside. After continuous administration for 8 weeks, serum, urine, and kidney tissue were collected, then, ralated biochemical parameters, pathological characteristics and MCP-1 and TGF-β1 mRNA or protein were detected. The NRK-52E cells were divided into three groups as follows: the normal control group (NC group), the high glucose group (HS group), the high glucose+acteoside group (HS+ACT group). The expressions of MCP-1 and TGF-β1 in the mRNA and protein levels were assessed with RT-PCR, western blot and ELISA.

Results: The expressions of MCP-1 and TGF-β1 were significantly enhanced in DN group and dramatically reduced after acteoside treatment. Compared with those in NC group, the expressions of MCP-1 and TGF-β1 in NRK-52E cell of HS group were significantly enhanced, while both were significantly decreased in HS+ACT group compared with HS group.

Conclusion: Our findings indicate that Acteoside has protective effects on DN via inhibiting the expressions of MCP-1 and TGF-β1.

Wogonin protects glomerular podocytes by targeting Bcl-2-mediated autophagy and apoptosis in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the microvascular complications of diabetes mellitus and a major cause of end-stage renal disease with limited treatment options. Wogonin is a flavonoid derived from the root of Scutellaria baicalensis Georgi, which has shown a potent renoprotective effect. But the mechanisms of action in DKD are not fully elucidated. In this study, we investigated the effects of wogonin on glomerular podocytes in DKD using mouse podocyte clone 5 (MPC5) cells and diabetic mice model. MPC5 cells were treated with high glucose (30 mM). We showed that wogonin (4, 8, 16 μM) dose-dependently alleviated high glucose (HG)-induced MPC5 cell damage, accompanied by increased expression of WT-1, nephrin, and podocin proteins, and decreased expression of TNF-α, MCP-1, IL-1β as well as phosphorylated p65. Furthermore, wogonin treatment significantly inhibited HG-induced apoptosis in MPC5 cells. Wogonin reversed HG-suppressed autophagy in MPC5 cells, evidenced by increased ATG7, LC3-II, and Beclin-1 protein, and decreased p62 protein. We demonstrated that wogonin directly bound to Bcl-2 in MPC5 cells. In HG-treated MPC5 cells, knockdown of Bcl-2 abolished the beneficial effects of wogonin, whereas overexpression of Bcl-2 mimicked the protective effects of wogonin. Interestingly, we found that the expression of Bcl-2 was significantly decreased in biopsy renal tissue of diabetic nephropathy patients. In vivo experiments were conducted in STZ-induced diabetic mice, which were administered wogonin (10, 20, 40 mg · kg^-1 · d^-1, i.g.) every other day for 12 weeks. We showed that wogonin administration significantly alleviated albuminuria, histopathological lesions, and p65 NF-κB-mediated renal inflammatory response. Wogonin administration dose-dependently inhibited podocyte apoptosis and promoted podocyte autophagy in STZ-induced diabetic mice. This study for the first time demonstrates a novel action of wogonin in mitigating glomerulopathy and podocytes injury by regulating Bcl-2-mediated crosstalk between autophagy and apoptosis. Wogonin may be a potential therapeutic drug against DKD.

Integrated analysis of potential gene crosstalk between non-alcoholic fatty liver disease and diabetic nephropathy

BACKGROUND

Growing evidence indicates that non-alcoholic fatty liver disease (NAFLD) is related to the occurrence and development of diabetic nephropathy (DN). This bioinformatics study aimed to explore optimal crosstalk genes and related pathways between NAFLD and DN.

METHODS

Gene expression profiles were downloaded from Gene Expression Omnibus. CIBERSORT algorithm was employed to analyze the similarity of infiltrating immunocytes between the two diseases. Protein-protein interaction (PPI) co-expression network and functional enrichment analysis were conducted based on the identification of common differentially expressed genes (DEGs). Least absolute shrinkage and selection operator (LASSO) regression and Boruta algorithm were implemented to initially screen crosstalk genes. Machine learning models, including support vector machine, random forest model, and generalized linear model, were utilized to further identify the optimal crosstalk genes between DN and NAFLD. An integrated network containing crosstalk genes, transcription factors, and associated pathways was developed.

RESULTS

Four gene expression datasets, including GSE66676 and GSE48452 for NAFLD and GSE30122 and GSE1009 for DN, were involved in this study. There were 80 common DEGs between the two diseases in total. The PPI network built with the 80 common genes included 77 nodes and 83 edges. Ten optimal crosstalk genes were selected by LASSO regression and Boruta algorithm, including CD36, WIPI1, CBX7, FCN1, SLC35D2, CP, ZDHHC3, PTPN3, LPL, and SPP1. Among these genes, LPL and SPP1 were the most significant according to NAFLD-transcription factor network. Five hundred twenty-nine nodes and 1,113 edges comprised the PPI network of activated pathway-gene. In addition, 14 common pathways of these two diseases were recognized using Gene Ontology (GO) analysis; among them, regulation of the lipid metabolic process is closely related to both two diseases.

CONCLUSIONS

This study offers hints that NAFLD and DN have a common pathogenesis, and LPL and SPP1 are the most relevant crosstalk genes. Based on the common pathways and optimal crosstalk genes, our proposal carried out further research to disclose the etiology and pathology between the two diseases.

Myokines: Novel therapeutic targets for diabetic nephropathy

With the increasing incidence of diabetic nephropathy (DN), there is an urgent need to find effective DN preventive and therapeutic modalities. It is widely believed that effective exercise is good for health. However, the beneficial role of exercise in kidney disease, especially in DN, and the underlying molecular mechanisms have rarely been reported. Muscle is not only an important motor organ but also an important endocrine organ, secreting a group of proteins called "myokines" into the blood circulation. Circulating myokines then move to various target organs to play different biological roles. In this review, we summarize the currently known myokines and the progress in research relating them to DN and discuss its potential as a therapeutic target for DN.

Epigenetic modifications in diabetes

Diabetes is now considered as a 'silent epidemic' that claims over four million lives every year, and the disease knows no socioeconomic boundaries. Despite extensive efforts by the National and International organizations, and cutting-edge research, about 11% world's population is expected to suffer from diabetes (and its complications) by year 2045. This life-long disease damages both the microvasculature and the macrovasculature of the body, and affects many metabolic and molecular pathways, altering the expression of many genes. Recent research has shown that external factors, such as environmental factors, lifestyle and pollutants can also regulate gene expression, and contribute in the disease development and progression. Many epigenetic modifications are implicated in the development of micro- and macro- vascular complications including DNA methylation and histone modifications of several genes implicated in their development. Furthermore, several noncoding RNAs, such as micro RNAs and long noncoding RNAs, are also altered, affecting many biochemical pathways. Epigenetic modifications, however, have the advantage that they could be passed to the next generation, or can be erased. They are now being explored as therapeutical target(s) in the cancer field, which opens up the possibility to use them for treating diabetes and preventing/slowing down its complications.

MicroRNA miR-4709-3p targets Large Tumor Suppressor Kinase 2 (LATS2) and induces obstructive renal fibrosis through Hippo signaling

Obstructive renal fibrosis is the consequence of abnormal extracellular matrix assembly, which eventually results in renal failure, acute, and end‑stage renal infection. MicroRNAs (miRNAs), a particular category of small RNAs, modulate the expression of genes post-transcriptionally and regulate biological activities, including fibrogenesis. The study probed to estimate the key functions of miR-4709-3p in obstructive renal fibrosis. This investigation used TGF-β1 stimulated HK-2 in-vitro model, unilateral ureteral occlusion (UUO) mice model, and human Diabetic nephropathy (DN) and Renal interstitial fibrosis (RIF) specimens to depict the abundance of the miR-4709-3p level using FISH and RT-qPCR. MiR-4709-3p mimics and inhibitors were utilized to evaluate the functions of miR-4709-3p in-vitro. Luciferase assay was exploited to verify miR-4709-3p and LATS2 3ʹUTR binding. Finally, to depict the functions of miR-4709-3p in-vivo, the UUO model was injected with miR-4709-3p inhibitors. Results exhibited the upregulation of miR-4709-3p in UUO-induced in-vivo model, TGF-β1 stimulated HK-2, and human RIF and DN samples. Moreover, it was determined that modulating miR-4709-3p regulated the level of fibrosis markers. Luciferase assay miR-4709-3p modulates renal fibrosis by targeting LATS2. Finally, it was found that miR-4709-3p regulates obstructive renal fibrosis through the Hippo signaling pathway. Overall, the study concludes that aberrant miR-4709-3p expression plays an essential function in the renal fibrosis progression, and miR-4709-3p overexpression could advance obstructive renal fibrosis via LATS2 targeting in Hippo signaling pathway. Therefore, miR-4709-3p inhibition may be a potential renal fibrosis therapy target.