Diabetic nephropathy: New insights into established therapeutic paradigms and novel molecular targets

LncRNA lnc-ISG20 promotes renal fibrosis in diabetic nephropathy by inducing AKT phosphorylation through miR-486-5p/NFAT5

Long non‐coding RNA (lncRNA) lnc‐ISG20 has been found aberrantly up‐regulated in the glomerular in the patients with diabetic nephropathy (DN). We aimed to elucidate the function and regulatory mechanism of lncRNA lnc‐ISG20 on DN‐induced renal fibrosis. Expression patterns of lnc‐ISG20 in kidney tissues of DN patients were determined by RT‐qPCR. Mouse models of DN were constructed, while MCs were cultured under normal glucose (NG)/high glucose (HG) conditions. The expression patterns of fibrosis marker proteins collagen IV, fibronectin and TGF‐β1 were measured with Western blot assay. In addition, the relationship among lnc‐ISG20, miR‐486‐5p, NFAT5 and AKT were analysed using dual‐luciferase reporter assay and RNA immunoprecipitation. The effect of lnc‐ISG20 and miR‐486/NFAT5/p‐AKT axis on DN‐associated renal fibrosis was also verified by means of rescue experiments. The expression levels of lnc‐ISG20 were increased in DN patients, DN mouse kidney tissues and HG‐treated MCs. Lnc‐ISG20 silencing alleviated HG‐induced fibrosis in MCs and delayed renal fibrosis in DN mice. Mechanistically, miR‐486‐5p was found to be a downstream miRNA of lnc‐ISG20, while miR‐486‐5p inhibited the expression of NFAT5 by binding to its 3'UTR. NFAT5 overexpression aggravated HG‐induced fibrosis by stimulating AKT phosphorylation. However, NFAT5 silencing reversed the promotion of in vitro and in vivo fibrosis caused by lnc‐ISG20 overexpression. Our collective findings indicate that lnc‐ISG20 promotes the renal fibrosis process in DN by activating AKT through the miR‐486‐5p/NFAT5 axis. High‐expression levels of lnc‐ISG20 may be a useful indicator for DN.

Circulating microRNA-194 levels in Chinese patients with diabetic kidney disease: a case-control study

OBJECTIVE

MicroRNAs (miRNAs) regulate gene expression and are involved in diabetic kidney disease (DKD) pathogenesis. We investigated circulating miRNA-194 levels as a biomarker of DKD prevalence and incidence, and the relationship between miRNA-194 and CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP).

METHODS

We recruited 136 type-2 diabetes mellitus (T2DM) patients at the First People's Hospital of Lianyungang and 127 healthy individuals. Circulating miRNA-194 and CHOP levels were measured using quantitative reverse transcription qRT-PCR and enzyme-linked immunosorbent assay (ELISA), respectively. Anthropometric and biochemistry measurements were also made.

RESULTS

T2DM patients showed higher circulating miRNA-194 (p = 0.029) and lower circulating CHOP (p < 0.001) levels than controls. Circulating miRNA-194 levels were significantly higher in T2DM patients with a microalbumin/creatinine ratio (UmALB/Cr) ⩾ 300 mg/g (p < 0.001). In addition, there were significant intergroup differences in the circulating CHOP concentrations (p = 0.005). Bivariate analysis revealed that circulating miR-194 levels were negatively correlated with alpha-fetoprotein and CHOP levels (r = -0.222, -0.301; p = 0.018, 0.001, respectively), but positively correlated with fasting glucose, UmALB/Cr, Cr, Cystatin C, quantitative insulin check index (QUICKI) (r = 0.193, 0.446, 0.260, 0.339, and 0.250, respectively; p = 0.036, <0.001, 0.005, <0.001, and 0.006, respectively), particularly UmALB/Cr and Cystatin C (p < 0.001). Logistic regression analysis after adjusting for covariates associated with UmALB/Cr identified duration of T2DM, systolic blood pressure, Cr, estimated glomerular filtration rate, and waist circumference as independent factors associated with T2DM patients with UmALB/Cr > 300 (p = 0.030, 0.013, <0.001, <0.001, and 0.031, respectively).

CONCLUSION

Circulating miRNA-194 levels could be a novel biomarker for DKD.

Epigenetic Histone Modifications in the Pathogenesis of Diabetic Kidney Disease

Diabetic kidney disease (DKD), as the main complication of diabetes mellitus, is the primary cause of the end-stage renal disease (ESRD) and the most common chronic kidney disease. Overall, 30-40% of patients with type 1 and type 2 diabetes eventually develop DKD. Although some diabetes patients have intensified glycemic control, they still develop diabetic kidney disease. Current treatment methods can alleviate but do not markedly halt disease development, resulting in renal failure and severe complications, even contributing to elevated morbidity and mortality rates. DKD is a disease with interactions of genes and the environment. Emerging evidence indicates that DKD-associated key genes are also regulated by the epigenetic mechanism. Recently, increasing researches involving cells and experimental animals demonstrated that histone post-translational modifications can mediate gene expression, which correlated with diabetic kidney disease. Novel therapeutic strategies for epigenetic events could be beneficial for the early detection and treatment of DKD to prevent it from developing into end-stage renal disease (ESRD). In this review, we discuss prior findings in the field of histone modifications in DKD, especially histone acetylation and histone methylation. We then focus on recent developments in histone acetylation and methylation involved in the pathogenesis of DKD.

Effect of sericin on the p38MAPK signaling pathway and NLRP3 inflammasome in the kidney of type 2 diabetic rats

The present study aimed to investigate the effects of sericin on the p38MAPK signaling pathway and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome in the kidney of rats with type 2 diabetes mellitus (T2DM). A total of 36 male Sprague-Dawley rats were randomly divided into the normal group, T2DM model group and sericin group (n=12 rats/group). A T2DM model was developed through intraperitoneal injection of streptozotocin (35 mg·kg^-1·d^-1 for 2 consecutive days), and a high-fat and high-sugar diet. The T2DM rats in the sericin group were administered 2.4 g·kg^-1·d^-1 sericin for 35 days, and rats in the other groups were administered an equal volume of normal saline for 35 days. Fasting blood glucose was measured using the glucose oxidase method. Kidney tissue morphology was observed by H&E staining. Immunohistochemistry, western blotting, ELISA and reverse transcription-quantitative PCR were used to detect the levels of MKK6, p38MAPK, phosphorylated (p)-p38MAPK, NF-κB, IL-1β, IL-6, NLRP3 and caspase-1 in rat kidney tissues. The results revealed that blood glucose concentration, and the expression levels of MKK6, p-p38MAPK, NF-κB, IL-1β, IL-6, NLRP3 and caspase-1 were significantly increased in the T2DM group compared with those in the normal group (P<0.05). In addition, obvious pathological changes were observed in the T2DM group. Conversely, glucose concentration, and the expression levels of MKK6, p-p38MAPK, NF-κB, IL-1β, IL-6, NLRP3 and caspase-1 were significantly reduced in the sericin group compared with those in the T2DM group (P<0.05). The pathological changes were also obviously reduced. Notably, there was no significant difference in p38MAPK expression among the three groups (P>0.05). Collectively, the present study revealed that sericin may downregulate the expression levels of MKK6, p-p38MAPK, NF-κB, IL-1β, IL-6, NLRP3 and caspase-1, and inhibit activation of renal p38MAPK signaling and NLRP3-associated inflammation, which in turn may protect against kidney damage caused by T2DM.

Recent advances in drug discovery for diabetic kidney disease

INTRODUCTION

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD), and 40% of patients with diabetes develop DKD. Although some pathophysiological mechanisms and drug targets of DKD have been described, the effectiveness or clinical usefulness of such treatment has not been well validated. Therefore, searching for new targets and potential therapeutic candidates has become an emerging research area.

AREAS COVERED

The pathophysiological mechanisms, new drug targets and potential therapeutic compounds for DKD are addressed in this review.

EXPERT OPINION

Although preclinical and clinical evidence has shown some positive results for controlling DKD progression, treatment regimens have not been well developed to reduce the mortality in patients with DKD globally. Therefore, the discovery of new therapeutic targets and effective target-based drugs to achieve better and safe treatment are urgently required. Preclinical screening and clinical trials for such drugs are needed.

Nephroprotective effect of Combretum micranthum G. Don in nicotinamide-streptozotocin induced diabetic nephropathy in rats: In-vivo and in-silico experiments

ETHNOPHARMACOLOGICAL RELEVANCE

Combretum micranthum G. Don (CM) is extensively used in traditional medicine throughout West Africa and commonly known as "long-life herbal tea" or "plant to heal". Further, traditional healers frequently use the title plant to mitigate of renal disorders.

AIM OF THE STUDY

To explore the nephroprotective property of standardised hydroalcoholic extract of Combretum micranthum in nicotinamide-streptozotocin induced diabetic nephropathy in rats. In addition, in-silico computational experiments were performed with bioactive compounds of the title plant against PPARα and PPARγ.

MATERIAL AND METHODS

Male rats were made diabetic by a single intraperitoneal (ip) injection of STZ (50 mg/kg), 15 min after ip administration of NA (100 mg/kg) dissolved in normal saline. The diabetic rats received CM extract (200 and 400 mg/kg p.o.) daily, for eight weeks. Body weights and blood glucose (non-fasting and fasting) of rats were measured weekly. Daily food and water consumption were also measured. After 8 weeks of treatment, urine biochemical parameters such as N-Acetyl-β-D-Glucosaminidase (NAG), urea (UR), uric acid (UA), creatinine (CRE), and serum markers of diabetes, kidney damage and liver damage such as insulin, lipid parameters), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (γGT), albumin (Alb), magnesium (Mg²⁺), calcium (Ca²⁺), phosphorus (P), were estimated. Blood glycosylated hemoglobin (HbA1_C) were also estimated. kidney and liver were used for biochemical estimation of oxidative stress markers such as lipid peroxidation, superoxide dismutase (SOD) activity and glutathione peroxidase (GPx) activity. The kidney and pancreas were used for histopathological study. Further, HPLC chemoprofiling of CM extract and in-silico molecular simulation experiments were performed.

RESULTS

At the end of eight weeks, renal damage induced by the consequence of prolong diabetic condition was confirmed by altered levels of serum and urine kidney and liver function markers, oxidative stress markers and histopathological variations in kidney. Treatment with CM extract ameliorated the diabetes mellitus-induced renal biochemical parameters and histopathological changes. Further, HPLC-UV & MS experiments revealed that CM extract contains several bioactive compounds including hyperozide (62.35 μg/mg of extract) and quercitrin (19.07 μg/mg of extract). In-silico experiment exhibited cianidanol (-17.133), epicatechin (-15.107) exhibited higher docking score against PPARα and luteoforol (-11.038), epigallocatechin (-10.736) against PPARγ. Based on docking and drug likeness score, four bioactive compounds were selected for molecular dynamic experiments. Cianidanol and epigallocatechin out of the 30 compounds are concluded as a potential candidate for the treatment of DN through activating PPARα and PPARγ target protein.

CONCLUSIONS

Taken together, the present study provided the scientific footage for the traditional use of Combretum micranthum.

USP9X prevents AGEs-induced upregulation of FN and TGF-β1 through activating Nrf2-ARE pathway in rat glomerular mesangial cells

Oxidative stress is a key pathological factor for diabetic renal fibrosis by activating TGF-β/Smad pathway in glomerular mesangial cells (GMCs) to promote the synthesis of extracellular matrix such as fibronectin (FN). Nuclear factor-E2-related factor (Nrf2)- anti-oxidant response element (ARE) anti-oxidative pathway has crucial renoprotective effects, and inhibiting ubiquitin-mediated degradation of Nrf2 delays diabetic renal fibrosis development. Ubiquitin-specific protease 9X (USP9X) has close relationship with oxidative stress and TGF-β/Smad pathway, but whether it regulate diabetic renal fibrosis remains unclarified. Here, we found that advanced glycation-end products (AGEs) dose- and time-dependently reduced the protein expression and deubiquitinase activity of USP9X in GMCs. USP9X overexpression attenuated AGEs-induced upregulation of FN, TGF-β1, and Collagen Ⅳ, three fibrosis-related marker proteins, in a deubiquitinase activity-dependent manner. While USP9X depletion with siRNAs further promoted the expressions of those proteins in AGEs-treated GMCs. Under AGEs treatment conditions, USP9X overexpression markedly increased the total and nuclear levels, ARE-binding ability, and transcriptional activity of Nrf2, upregulated the protein expressions of Nrf2 downstream genes HO-1 and NQO1, and eventually reduced the excessive production of ROS. Overexpression of the deubiquitinase catalytically inactive USP9X-C1556S mutant failed to exert such effects. Silencing Nrf2 abolished the renoprotective effects of USP9X. Further study showed that upon AGEs stimulation, Nrf2 transferred into the nucleus and the interaction between USP9X and Nrf2 was weakened. AGEs also increased Nrf2 ubiquitination level, and overexpression of USP9X, instead of USP9X-C1556S, significantly reduced the ubiquitination level of Nrf2. Taken together, USP9X reduced Nrf2 ubiquitination level and promoted Nrf2-ARE pathway activation to prevent the accumulation of extracellular matrix, eventually alleviated the pathological process of diabetic renal fibrosis.

Protective Effect and Possible Mechanisms of Astragaloside IV in Animal Models of Diabetic Nephropathy: A Preclinical Systematic Review and Meta-Analysis

Astragaloside IV (AS-IV) has a variety of biological activities and is widely used to treat kidney diseases. We conducted a systematic review of 24 animal studies including 424 animals to evaluate the efficacy of AS-IV for diabetic nephropathy (DN); all current possible mechanisms were summarized. A search strategy was applied to eight databases from inception to June 2020. The CAMARADES 10-item quality checklist and Rev-Man 5.3 software were used to analyze the risks of bias of each study and data regarding outcome measures, respectively. The mean study quality score was 5.4 points (range 3–8 points). Meta-analyses data and comparisons between groups showed that AS-IV significantly slowed the progression of pathological signs in the kidney including glomeruli and tubules, increasing creatinine clearance rate, decreasing blood urea nitrogen, serum creatinine, 24-h urinary neutrophil gelatinase-associated lipocalin and N-acetyl-β-D-glucosaminidase, 24-h urinary albumin, 24-h urinary microalbumin and HbA1c. There were no significant differences between experimental and control groups with respect to mortality or levels of alanine aminotransferase and aspartate aminotransferase. In terms of the possible mechanisms of treatment of DN, AS-IV acts through antifibrotic, antioxidant, and antiapoptotic mechanisms, thereby alleviating endoplasmic reticulum stress, inhibiting mitochondrial fission, and increasing autophagic activity. Taken together, our findings suggest that AS-IV is a multifaceted renoprotective candidate drug for DN.

Rutin ameliorates metabolic acidosis and fibrosis in alloxan induced diabetic nephropathy and cardiomyopathy in experimental rats

Diabetic nephropathy and cardiomyopathy are two major causes of mortality among patients with diabetes mellitus (DM). Since current diabetic medications are associated with various side effects, the naturally occurring plant-derived compounds are in demand. Bioflavonoids originating from vegetables and medicinal plants have beneficial effects on diabetes by improving glycemic control, lipid metabolism, and anti-oxidant status. The present study is focused on the effect of rutin against alloxan induced diabetic nephropathy and cardiomyopathy. Male albino Wistar rats were divided into four groups, each of six rats. Group I control rats received 0.9% saline as a single dose intraperitoneally. Group II rats were induced diabetes with a single dose of alloxan monohydrate (150 mg/kg body weight in 0.9% saline) intraperitoneally. Group III rats received 0.28 M of NH₄Cl in drinking water for 3 days for the experimental induction of metabolic acidosis. Group IV rats were injected with a single dose of alloxan monohydrate (150 mg/kg bodyweight) and administered rutin hydrate (100 mg/kg) for a period of 4 weeks by oral gavage. Administration of rutin prevented urinary ketone body formation and decreased serum creatinine and urea levels in alloxan induced diabetic rats. Rutin supplementation reduced the levels of serum triglycerides and cholesterol in diabetic rats. Gene expression profiling of metabolic acidosis related genes (AQP2, AQP3 and V2R) and also histopathological results demonstrated the protective effect of rutin against diabetic ketoacidodis and fibrosis. The results of the present study revealed rutin administration prevents the progression of diabetic nephropathy and cardiomyopathy through amelioration of fibrosis and metabolic acidosis.

Diabetic Kidney Disease in Older People with Type 2 Diabetes Mellitus: Improving Prevention and Treatment Options

Age-related metabolic and renal changes predispose older people to an increased risk of diabetes mellitus and diabetic kidney disease, respectively. As the prevalence of the ageing population is increasing, because of increased life expectancy, the prevalence of older people with diabetic kidney disease is likely to increase. Diabetic kidney disease is associated with an increased risk of adverse outcomes and increased costs to healthcare systems. The management includes promotion of a healthy lifestyle and control of cardiovascular risk factors such as hyperglycaemia, hypertension and dyslipidaemia. Older people are a heterogeneous group of people from a community-living fit and independent person to a fully dependent individual residing in a care home. Therefore, management in this age group should be based on a patient's functional level adopting tight metabolic control in the fit individual and relaxed targets in the frail person. However, despite the maximum available therapy, a significant number of patients with diabetic kidney disease still progress to renal failure and experience adverse cardiac outcomes. Therefore, future research is required to explore methods of early detection of diabetic kidney disease and to investigate novel therapeutic interventions to further improve the outcomes.

Exosomes from high glucose-treated macrophages activate macrophages andinduce inflammatory responses via NF-κB signaling pathway in vitro and in vivo

There is increasing evidence that macrophages play an important role in the development and pathogenesis of diabetic nephropathy (DN) by secreting inflammatory cytokines. Exosomes are a family of extracellular vesicles that are secreted from almost all types of cells and associated with cell-to-cell communications. In this article, we try to investigate whether high glucose (HG)-treated macrophages-derived exosomes could activate macrophages and induce inflammatory responses in vivo and in vitro. We incubated the exosomes from high glucose-treated Raw264.7 cells (HG-Exo) and Raw264.7 cells for 24 h. The expression levels of related inflammatory molecules and NF-κB p65 signaling pathway were identified, as well as the intracellular localization of NF-κB p65 was detected. In vivo, HG-Exo was injected into mice via tail vein and the related parameters of kidneys were detected. Compared with the exosomes from normal glucose-treated Raw264.7 cells (NG-Exo), HG-Exo contained higher concentrations of IL-1β and iNOS. HG-Exo-treated Raw264.7 cells secreted higher level of related inflammatory molecules and promoted NF-κB p65 signaling pathway expression. HG-Exo induced the production of intracellular iNOS and α-SMA. In the HG-Exo group, NF-κB p65 positive signals were mainly distributed in the nucleus area. HG-Exo treated mice kidneys displayed a significantly mesangial expansion and proliferation. NF-κB p65 protein expression levels in mice renal tissue treated with HG-Exo was significantly up-regulated. These findings suggest that high glucose treated macrophages-derived exosomes may activate macrophages and accelerate kidney injury via NF-κB p65 signaling pathway.

Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease around the globe and is one of the main complications in patients with type 1 and 2 diabetes. The standard treatment for DKD is drugs controlling hyperglycemia and high blood pressure. Renin angiotensin aldosterone system blockade and sodium glucose cotransporter 2 (SGLT2) inhibition have yielded promising results in DKD, but many diabetic patients on such treatments nevertheless continue to develop DKD, leading to kidney failure and cardiovascular comorbidities. New therapeutic options are urgently required. We review here the promising therapeutic avenues based on insights into the mechanisms of DKD that have recently emerged, including mineralocorticoid receptor antagonists, SGLT2 inhibitors, glucagon-like peptide-1 receptor agonist, endothelin receptor A inhibition, anti-inflammatory agents, autophagy activators and epigenetic remodelling. The involvement of several molecular mechanisms in DKD pathogenesis, together with the genetic and epigenetic variability of this condition, makes it difficult to target this heterogeneous patient population with a single drug. Personalized medicine, taking into account the genetic and mechanistic variability, may therefore improve renal and cardiovascular protection in diabetic patients with DKD.

Alantolactone mitigates renal injury induced by diabetes via inhibition of high glucose-mediated inflammatory response and macrophage infiltration

Background: Inflammatory response plays a crucial role in the occurrence and development of diabetic nephropathy (DN). Drugs that carry anti-inflammatory effects have the potential to treat diabetic nephropathy. It's reported that alantolactone (ALA), a natural product, has a variety of pharmacological effects against inflammation and oxidation. However, the specific effects of alantolactone on DN and the mechanisms underlying alantolactone remain elusive. Therefore, the present study aimed to probe whether ALA could mitigate inflammation as mediated by high glucose (HG) in NRK-52E cells and reduce renal injury caused by diabetic nephropathy.Materials and methods: The anti-inflammatory effect of ALA was evaluated in the present study using ELISA and RT-qPCR. Western blot and macrophage adhesion assay were then performed to confirm anti-macrophage adhesion and the protein expression of cell adhesion molecules. Finally, the effect of ALA and its underlying mechanism was evaluated in vivo.Results: Results showed that ALA curbed HG-stimulated expression of macrophage adhesion and pro-inflammatory cytokines in renal NRK-52E cells. In addition, both pro-inflammatory cytokines and NF-kappa B witnessed reduced expression or activity in oral administration with ALA in vivo, thus inhibiting the increase of serum creatinine and urea nitrogen (BUN) levels. This in consequence ameliorated fibrosis and stemmed pathological worsening of diabetic renal tissues.Conclusions: These findings suggest that ALA may hold promise in the treatment of DN, and importantly, the anti-inflammatory system may prove to be a new strategy to treat human DN.

Altered DNA methylation of TRIM13 in diabetic nephropathy suppresses mesangial collagen synthesis by promoting ubiquitination of CHOP

Background

Mesangial collagen synthesis in renal glomeruli contributes to the pathogenesis of diabetic nephropathy (DN) which is one of the most serious complications of diabetes mellitus. However, the underlying mechanism of mesangial collagen synthesis is largely unknown.

Methods

The differential expression of CHOP and TRIM13 which is a well-defined E3 ubiquitin ligase was compared in renal biopsy samples from DN/normal renal tissues, in isolated glomeruli of diabetic/control mice, as well as in high glucose (HG) or TGF-β1-stimulated renal mesangial cells. Then the relationship between TRIM13 and CHOP was explored using the ubiquitination assay.

Findings

We found that the expression of TRIM13 was downregulated in renal biopsies, isolated glomeruli of diabetic mice, and HG/TGF-β1-stimulated renal mesangial cells, while the expression of CHOP was upregulated. An increased level of TRIM13 promoter methylation contributed to the deregulation of TRIM13 in renal glomeruli of DN. The ubiquitination assay confirmed that TRIM13 promoted ubiquitination and degradation of CHOP. Meanwhile, overexpressing TRIM13 attenuated DN-induced collagen synthesis and restored renal function in vitro and in vivo via downregulating CHOP.

Interpretation

Our findings demonstrated that overexpressed TRIM13 suppresses mesangial collagen synthesis in DN by promoting ubiquitination of CHOP, suggesting TRIM13 as a potential therapeutic target in treating DN.

Research Progress on the Pathological Mechanisms of Podocytes in Diabetic Nephropathy

Diabetic nephropathy (DN) is not only an important microvascular complication of diabetes but also the main cause of end-stage renal disease. Studies have shown that the occurrence and development of DN are closely related to morphological and functional changes in podocytes. A series of morphological changes after podocyte injury in DN mainly include podocyte hypertrophy, podocyte epithelial-mesenchymal transdifferentiation, podocyte detachment, and podocyte apoptosis; functional changes mainly involve podocyte autophagy. More and more studies have shown that multiple signaling pathways play important roles in the progression of podocyte injury in DN. Here, we review research progress on the pathological mechanism of morphological and functional changes in podocytes associated with DN, to provide a new target for delaying the occurrence and development of this disorder.

LINC00462 is involved in high glucose-induced apoptosis of renal tubular epithelial cells via AKT pathway

New evidences suggest that long non-coding RNAs (lncRNAs) may play important roles in a variety of kidney diseases, including diabetic nephropathy (DN). Our present study investigated the potential function of LINC00462 in high glucose (HG)-induced apoptosis of renal tubular epithelial cells (RTEC) and to determine the underlying mechanism. The expression of LINC00462 in renal biopsy tissues was examined using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Then, a loss of function assay was performed to determine the protective effect of LINC00462 in HG-induced RTEC damage. In addition, the downstream signaling pathway of LINC00462 was also investigated. The qRT-PCR results showed that the expression of LINC00462 was significantly up-regulated in renal biopsies from DN patients. At the same time, LINC00462 was enhanced in a glucose concentration- and time-dependent manner in human kidney (HK-2 and HKC) cells subjected to HG treatment. The knockdown of LINC00462 improved the significantly reduced cell viability of HG treatment, decreased HG-induced reactive oxygen species (ROS) and malondialdehyde levels, and up-regulated the response of antioxidant systems to ROS by increasing superoxide dismutase and catalase levels. In addition, knockdown of LINC00462 inhibited HG-induced cell apoptosis and affected the expression of apoptosis-related proteins. Most importantly, we found that knockdown of LINC00462 enhanced the expression of p-AKT. Moreover, AKT-specific inhibitor LY294002 restored the effect of LINC00462 knockdown on apoptosis. In conclusion, our study demonstrated that knockdown of LINC00462 can ameliorate oxidative stress and apoptosis in HG-induced RTEC by activating the AKT pathway, suggesting that knockdown of LINC00462 may provide a potential therapeutic approach for DN.

lncRNA MEG8 Upregulates miR-770-5p Through Methylation and Promotes Cell Apoptosis in Diabetic Nephropathy

BACKGROUND

It has been reported that lncRNA MEG8 can be induced by glucose in mice model of kidney injury, indicating its role in diabetic nephropathy (DN). This study was carried out to explore the role of MEG8 in DN.

MATERIALS AND METHODS

The expression of MEG8 and miR-770-5p in plasma samples from DN patients (n = 66), diabetic patients (DM patients with no complications, n = 66) and healthy controls (n = 66) was detected by RT-qPCR. The interaction between MEG8 and miR-770-5p in podocyte cells was evaluated by transient transfections. Cell apoptosis under high-glucose treatment was detected by cell apoptosis assay.

RESULTS

MEG8 and miR-770-5p were upregulated in plasma of DM patients and were further upregulated in DN patients. MEG8 was positively correlated with miR-770-5p. In podocyte cells, high-glucose treatment resulted in increased expression levels of MEG8 and miR-770-5p. In podocyte cells, overexpression of MEG8 resulted in upregulated expression of miR-770-5p and decreased methylation of the miR-770-5p gene. Cell apoptosis analysis showed that overexpression of MEG8 and miR-770-5p resulted in increased cell apoptotic rate under glucose treatment. In addition, combined overexpression of MEG8 and miR-770-5p showed stronger effects.

CONCLUSION

MEG8 may upregulate miR-770-5p through methylation to promote DN by promoting cell apoptosis.

P-Coumaric acid alleviates experimental diabetic nephropathy through modulation of Toll like receptor-4 in rats

AIMS

Diabetic nephropathy (DN) is responsible for the occurrence of 30-47% of the incident cases of end-stage renal disease (ESRD) worldwide. DN is a chronic inflammatory disorder, which results from hyperglycemia-induced alterations and leads to renal fibrosis and ESRD. Toll like receptor-4 (TLR-4) participates in regulation of inflammatory response through controlling of innate immune system. P-Coumaric Acid (P-CA) is a natural hydroxycinnamic acid derivative and is widely present in vegetables, fruits, mushrooms and cereals. This study aimed to explore the renoprotective effect of P-CA, as anti-inflammatory and antioxidant natural compound, against experimental DN.

METHODS

DN was induced by single intraperitoneal injection of streptozotocin (45 mg/kg) in rats. In kidney homogenate, levels of TLR-4, interleukin-6 (IL-6) and transforming growth factor β1 (TGFβ1) were measured using ELISA technique. Also, kidney collagen content was determined colorimetrically.

KEY FINDINGS

Oral administration of P-CA (100 mg/kg) for 8 weeks significantly alleviated the DN. P-CA significantly reduced serum concentrations of glucose, creatinine, blood urea nitrogen (BUN) and reduced protein content in urine. Also, P-CA significantly increased superoxide dismutase (SOD) activity and significantly reduced kidney contents of malondialdehyde (MDA), TLR-4, IL-6, TGFβ1 and collagen when compared with DN group. Moreover, P-CA significantly improved DN-induced histopathological abnormalities.

SIGNIFICANCE

P-CA confers protection against the progression of DN. This renoprotective effect can be attributed to its ability to decrease the generation of inflammatory and fibrotic cytokines in addition to restoring oxidant/antioxidant balance through its ability to down-regulate TLR-4 activation.

Eriodictyol inhibits high glucose-induced extracellular matrix accumulation, oxidative stress, and inflammation in human glomerular mesangial cells

Diabetic nephropathy (DN) is one of the major complications of diabetes mellitus. The progression of DN has been found to be associated with high glucose (HG)-induced oxidative stress and inflammation in diabetes mellitus. Eriodictyol is a flavonoid that possesses antioxidant and anti-inflammatory effects. However, the effect of eriodictyol on DN remains unknown. In the present study, we evaluated the role of eriodictyol in mesangial cells (MCs) in response to HG condition. The results showed that eriodictyol repressed cell proliferation of HG-stimulated MCs. Treatment with eriodictyol attenuated oxidative stress, which was evidenced by increased superoxide dismutase activity as well as decreased production of reactive oxygen species (ROS) and malondialdehyde. Besides, eriodictyol suppressed the expressions of two NADPH oxidase (NOX) isoforms, NOX2 and NOX4, which are responsible for the generation of ROS. Eriodictyol suppressed the production of extracellular matrix proteins including fibronectin and Collagen IV, as well as the secretion of inflammatory cytokines including TNF-α, IL-1β, and IL-6 in HG-induced MCs. Moreover, the HG-induced activation of Akt/NF-κB pathway was mitigated by eriodictyol. In conclusion, eriodictyol protected MCs from HG stimulation though inhibition of Akt/NF-κB pathway.

CTRP3 Protects against High Glucose-Induced Cell Injury in Human Umbilical Vein Endothelial Cells

Aims

Inflammation was closely associated with diabetes-related endothelial dysfunction. C1q/tumor necrosis factor-related protein 3 (CTRP3) is a member of the CTRP family and can provide cardioprotection in many cardiovascular diseases via suppressing the production of inflammatory factors. However, the role of CTRP3 in high glucose- (HG-) related endothelial dysfunction remains unclear. This study evaluates the effects of CTRP3 on HG-induced cell inflammation and apoptosis.

Materials and Methods

To prevent high glucose-induced cell injury, human umbilical vein endothelial cells (HUVECs) were pretreated with recombinant CTRP3 for 1 hour followed by normal glucose (5.5 mmol/l) or high glucose (33 mmol/l) treatment. After that, cell apoptosis and inflammatory factors were determined.

Results

Our results demonstrated that CTRP3 mRNA and protein expression were significantly decreased after HG exposure in HUVECs. Recombinant human CTRP3 inhibited HG-induced accumulation of inflammatory factors and cell loss in HUVECs. CTRP3 treatment also increased the phosphorylation levels of protein kinase B (AKT/PKB) and the mammalian target of rapamycin (mTOR) in HUVECs. CTRP3 lost its inhibitory effects on HG-induced cell inflammation and apoptosis after AKT inhibition. Knockdown of endogenous CTRP3 in HUVECs resulted in increased inflammation and decreased cell viability in vitro.

Conclusions

Taken together, these findings indicated that CTRP3 treatment blocked the accumulation of inflammatory factors and cell loss in HUVECs after HG exposure through the activation of AKT-mTOR signaling pathway. Thus, CTRP3 may be a potential therapeutic drug for the prevention of diabetes-related endothelial dysfunction.

High-Mobility Group Nucleosome-Binding Protein 1 Mediates Renal Fibrosis Correlating with Macrophages Accumulation and Epithelial-to-Mesenchymal Transition in Diabetic Nephropathy Mice Model

Background/Aim: Renal fibrosis is essential for the progression of diabetic nephropathy (DN). Macrophages accumulate in diabetic kidneys and are involved in epithelial-to-mesenchymal transition (EMT), a vital mechanism leading to renal fibrosis. Recently, high-mobility group nucleosome-binding protein 1(HMGN1) was documented in promoting the recruitment and activation of antigen-presenting cells. In this study, we first reported its roles in renal fibrosis and the underlying mechanism associated with macrophage filtration and EMT. Methods: Twenty C57BL/6J mice were administered streptozotocin (STZ) to induce diabetes for 6 weeks and then divided into 4 groups: normal control group; DN group; benazepril-treated group, and insulin-treated group. Blood glucose, creatinine, and albumin in urine, hematoxylin and eosin, and Sirius red staining of kidney tissues were used to assess the renal pathology. ELISA, immunochemistry, and in situ hybridization were performed to determine the expression of HMGN1, CD68, F4/80, α-smooth muscle actin, and E-cadherin. Results: The renal expression levels of HMGN1, macrophage markers, and EMT makers were increased in DN group, and insulin treatment could reduce the overexpression of these indicators with a better effect than benazepril treatment. Both treatments could not obviously ameliorate urine albumin-to-creatinine ratio, collagen expression, and renal histological changes in STZ-induced diabetic mice. Correlation analysis indicated that there was a relationship among HMGN1, macrophage markers, EMT markers, and collagen expression in DN mice. Conclusion: HMGN1 may promote macrophages accumulation and EMT, suggesting a potential therapeutic target for preventing renal fibrosis development in DN.

Kidney Disease in Diabetes Mellitus: Cross-Linking between Hyperglycemia, Redox Imbalance and Inflammation

Chronic hyperglycemia is the key point of macro- and microvascular complications associated with diabetes mellitus. Excess glucose is responsible for inducing redox imbalance and both systemic and intrarenal inflammation, playing a critical role in the pathogenesis of diabetic kidney disease, which is currently the leading cause of dialysis in the world. The pathogenesis of the disease is complex, multifactorial and not fully elucidated; many factors and mechanisms are involved in the development, progression and clinical outcomes of the disease. Despite the disparate mechanisms involved in renal damage related to diabetes mellitus, the metabolic mechanisms involving oxidative/inflammatory pathways are widely accepted. The is clear evidence that a chronic hyperglycemic state triggers oxidative stress and inflammation mediated by altered metabolic pathways in a self-perpetuating cycle, promoting progression of cell injury and of end-stage renal disease. The present study presents an update on metabolic pathways that involve redox imbalance and inflammation induced by chronic exposure to hyperglycemia in the pathogenesis of diabetic kidney disease.

Antioxidant and nephroprotection activities of Combretum micranthum: A phytochemical, in-vitro and ex-vivo studies

Management of chronic renal failure is exceedingly expensive. Despite of encouraging experimental outcomes, there is a lack of potent nephroprotective drugable molecules in a clinics or market. To develop a nephroprotective phytomedicine, the present study was designed to do a literature survey on reported phytochemical and biological analysis of Combretum micranthum and to carry out chemoprofiling, in-vitro antioxidant and ex-vivo nephroprotective capacity of the title plant. The phytochemical and biological activity survey of C. micranthum has reveals the presence of many bioactive compounds such as flavonoids, terpenoids, steroids and alkaloids with many biological activities. Phytochemical investigation re-confirmed the presence of these compounds. Hydroalcoholic extract of C. micranthum (CM extract) showed a strong antioxidant activity by scavenging AAPH, DPPH, nitric oxide, hydrogen peroxide and chelating metal ions. CM extract exhibited significant (P < 0.001) dose dependent inhibition of ferric chloride-ascorbic acid induced lipid peroxidation. Diabetic nephropathy is a serious and common complication leading to end stage renal disease. Therefore, in the present study, glucose-induced toxicity was also studied in human embryonic kidney cells (HEK-293) as an in vitro model for diabetic nephropathy. The results showed that exposure of cells to high glucose (100 mM) for 72 h significantly reduced the cell viability resulting in morphological changes such as cell shrinkage, rounded cell shape and cytoplasmic vacuolation. Treatment with CM extract at 10 and 25 μg/mL resulted in significant improvement in cell viability from 10 to 23% compared to the high glucose control. This study demonstrated the potential antioxidant and nephroprotective properties of C. micranthum, justifying its traditional use in the treatment of various diseases.

Tannins and vascular complications of Diabetes: An update

BACKGROUND

Diabetes mellitus is a chronic metabolic disorder associated with persistent increased level of glucose in the blood. According to a report by World Health Organisation (WHO), prevalence of diabetes among adults over 18 years of age had reached to 8.5% in year 2014 which was 4.7% in 1980s. The Prolong increased level of glucose in blood leads to development of microvascular (blindness, nephropathy and neuropathy) and macrovascular (cardiovascular and stroke) degenerative complications because of uncontrolled level of glucose in blood. This also leads to the progression of oxidative stress and affecting metabolic, genetic and haemodynamic system by activation of polyol pathway, protein kinase C pathway, hexosamine pathway and increases advanced glycation end products (AGEs) formation. Diabetes mellitus and its associated complications are one of the major leading causes of mortality worldwide. Various natural products like alkaloids, glycosides, flavonoids, terpenoids and polyphenols are reported for their activity in management of diabetes and its associated diabetic complications. Tannins are systematically studied by many researchers in past few decades for their effect in diabetes and its complications.

AIM

The present review was designed to compile the data of tannins and their beneficial effects in the management of diabetic complications.

METHOD

Literature search was performed using various dataset like pubmed, EBSCO, proQuest Scopus and selected websites including the National Institutes of Health (NIH) and the World Health Organization (WHO).

RESULTS

Globally, more than 400 natural products have been investigated in diabetes and its complications. Tannins are the polyphenolic compounds present in many medicinal plants and various dietary sources like fruits, nuts, grains, spices and beverages. Various reports have shown that compounds like gallic acid, ellagic acid, catechin, epicatechin and procynidins from medicinal plants play major role in controlling progression of diabetes and its related complications by acting on molecular pathways and key targets involved in progression. Many chemists used above mentioned phyto-constituents as a pharmacophore for the developing new chemical entities having higher therapeutic benefits in management of diabetic complications.

CONCLUSION

This review focuses on the role of various tannins in prevention and management of diabetic complications like diabetic nephropathy, diabetic neuropathy, diabetic retinopathy and diabetic cardiomyopathy. It will help researchers to find some leads for the development of new cost effective therapy using dietary source for the management of diabetic complications.

Interleukin-17A blockade reduces albuminuria and kidney injury in an accelerated model of diabetic nephropathy

Diabetic nephropathy (DN) is one of the most common complications of diabetes, and currently the first end-stage renal disease worldwide. New strategies to treat DN using agents that target inflammatory pathways have attracted special interest. Recent pieces of evidences suggest a promising effect of IL-17A, the Th17 effector cytokine. Among experimental DN models, mouse strain BTBR ob/ob (leptin deficiency mutation) develops histological features similar to human DN, which means an opportunity to study mechanisms and novel therapies aimed at DN regression. We found that BTBR ob/ob mice presented renal activation of the factors controlling Th17 differentiation. The presence of IL-17A-expressing cells, mainly CD4⁺ and γδ lymphocytes, was associated with upregulation of proinflammatory factors, macrophage infiltration and the beginning of renal damage. To study IL-17A involvement in experimental DN pathogenesis, treatment with an IL-17A neutralizing antibody was carried out starting when the renal damage had already appeared. IL-17A blockade ameliorated renal dysfunction and disease progression in BTBR ob/ob mice. These beneficial effects correlated to podocyte number restoration and inhibition of NF-κB/proinflammatory factors linked to a decrease in renal inflammatory-cell infiltration. These data demonstrate that IL-17A takes part in diabetes-mediated renal damage and could be a promising therapeutic target to improve DN.

Coreopsis tinctoria Nutt ameliorates high glucose-induced renal fibrosis and inflammation via the TGF-β1/SMADS/AMPK/NF-κB pathways

BACKGROUND

Coreopsis tinctoria Nutt is an ethnomedicine widely used in Xinjiang, China. It is consumed as a herbal tea by local Uyghur people to treat high blood pressure and diarrhea. Our previous study confirmed that the ethyl acetate extract of Coreopsis tinctoria (AC) had a protective effect on diabetic nephropathy (DN) in an in vivo experiment. Here we aim to elucidate the protective mechanism of AC and marein, the main ingredient in Coreopsis tinctoria on renal fibrosis and inflammation in vitro under high glucose (HG) conditions.

METHODS

A HG-induced barrier dysfunction model in rat mesangial cells (HBZY-1) was established. The cells were exposed to AC and marein and/or HG for 24 h. Then, the renal protective effects of AC and marein via transforming growth factor-β1 (TGF-β1)/Smads, AMP-activated kinase protein (AMPK), and nuclear factor kappa beta (NF-κB) signaling were assessed.

RESULTS

Both AC and marein suppressed rat mesangial cell hyperplasia and significantly attenuated the expression of HG-disrupted fibrotic and inflammatory proteins in HBZY-1 cells. It was also confirmed that AC and marein remarkably attenuated HG-induced renal inflammation and fibrosis by regulating the AMPK, TGF-β1/Smads, and NF-κB signaling pathways.

CONCLUSION

These results indicated that AC and marein may delay the progression of DN, at least in part, by suppressing HG-induced renal inflammation and fibrosis. Marein may be one of the bioactive compounds in AC.

Predictive metabolic signatures for the occurrence and development of diabetic nephropathy and the intervention of Ginkgo biloba leaves extract based on gas or liquid chromatography with mass spectrometry

Diabetic nephropathy (DN) is one of the leading causes of death in diabetes mellitus (DM). Early warning and therapy has significant clinical value for DN. This research sought to find biomarkers to predict the occurrence and development of DN and the intervention of Ginkgo biloba leaves extract (GBE) by quantifying fatty acids, amino acids, and nucleosides and nucleobases in rat plasma. Samples were respectively collected at the weekend of 5-10 weeks after diabetic rats induced by streptozotocin were defined. Plasma fasting blood-glucose, kidney index, blood urea nitrogen, creatinine, urine albumin excretion and ultrastructural morphology of kidney were measured or observed. Fatty acids, amino acids and nucleosides and nucleobases in rat plasma were analyzed by gas chromatography or liquid phase chromatography and mass spectrometry, respectively. From the biochemical index and morphological change of kidney, the rats from the 5th to 7th week were in the stage of DM while from the begin of 8th week the rats were suggested in the early stage of DN. The results of quantitative metabolomics showed that 16 differential metabolites were related to the progression of DN, and oleic acid, glutamate and guanosine might be the potential biomarkers of kidney injury. 14 differential metabolites were related to GBE against the progression of DN, while oleic acid and glutamate might be the potential biomarkers of GBE against kidney injury. Those findings potentially promote the understanding of the pathogenic progression of DN and reveal the therapeutic mechanism of GBE against DN.

Protective effect of the ethanol extract from Ligusticum chuanxiong rhizome against streptozotocin-induced diabetic nephropathy in mice

ETHNOPHARMACOLOGY RELEVANCE

Rhizome of Ligusticum chuanxiong Hort. (Abbreviated as LC) is a frequently prescribed component in plenty of traditional Chinese medicine (TCM) formulas which are used to treat diabetic nephropathy (DN). The aims of the present study are to investigate the protective effect of the ethanol extract of LC rhizome (EEL) against DN in vivo, evaluate its potential mechanism, and find the evidence supporting its enthopharmacological use as an anti-DN agent.

MATERIALS AND METHODS

Hepa 1c1c7 murine hepatoma cells, human breast carcinoma MDA-MB-231 cells, human renal glomerular endothelial cells (HRGEC), and RAW 264.7 murine macrophages were adopted to test the effects of EEL and its active constituents on inhibitions of oxidative stress and inflammation in vitro. A streptozotocin (STZ) -induced DN C57BL/6 mice model was established and used to investigate the preventive effect of EEL against DN in vivo.

RESULTS

EEL demonstrated potential inhibitory effects against oxidative stress and inflammation in vitro. Using a STZ-induced DN mice model, it has been found that EEL treatment significantly prevented STZ-induced increases of urine production, urinary albumin excretion (UAE) and urine albumin-to-creatinine ratio (UACR), and markedly attenuated STZ-induced renal damages (e.g. glomerulosclerosis and fibrosis). The predominant bioactive constituents, Z-ligustilide (LGT), ferulic acid (FA), and tetramethylpyrazine (TMP), were inhibitors of oxidative stress and inflammation through acting with Nrf2 and NF-κB pathways.

CONCLUSIONS

EEL attenuates structural and functional damages of kidney in STZ-induced DN model in vivo, which might be related to the functions of EEL on inhibitions of oxidative stress and inflammation. These finding definitely supports the ethnopharmacological use of LC as an anti-DN agent.

Kaempferol attenuates diabetic nephropathy by inhibiting RhoA/Rho-kinase mediated inflammatory signalling

RhoA/Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK) has appeared as a potential therapeutic target in numerous diseases, because of its preventing action on various enzymes providing antioxidant and cytoprotective action. Progression and pathophysiology of diabetic nephropathy have also shown potential involvement of oxidative stress and inflammatory pathways. In the present study, we investigated the effect of kaempferol on hyperglycemia-induced activation of RhoA kinase and associated inflammatory signaling cascade. Currently there is only small literature available on the mechanism of anti-diabetic and nephroprotective action of this compound, which creates a void. Therefore, we focused here on the investigation of molecular mechanisms for kaempferol by means of in vitro testing, using rat (NRK-52E) and human renal tubular epithelial cells (RPTEC). Our findings suggest that kaempferol inhibits hyperglycemia-induced activation of RhoA and decreased oxidative stress, pro-inflammatory cytokines (TNF-α and IL-1β) and fibrosis (TGF-β1 expression, extracellular matrix protein expression) in NRK-52E and RPTEC cells. Therefore, kaempferol can be used as a potential therapeutic for the treatment of diabetic nephropathy.

Salvia miltiorrhiza protects against diabetic nephropathy through metabolome regulation and wnt/β-catenin and TGF-β signaling inhibition

Diabetic nephropathy (DN) is a complication of diabetes that is caused by uncontrolled high blood sugar. It has been reported that Salvia miltiorrhiza (SM) possesses the ability to prevent kidney damage, although the mechanisms remain unclear. The study was to investigate whether and how SM improved DN injury via regulation of metabolome and the molecular mechanisms. In this study, SD rats were fed a high glucose / high fat diet accompanied by 0.5% glucose water. Three weeks later, the rats were given one intraperitoneal injection of 30 mg/kg STZ each day for three days for DN model. The biochemical indicators and metabolomics of plasma, urine and renal tissue were analyzed. Then the western blotting analysis of renal tissue and glomerular mesangial cells were investigated. The results showed that Salvia miltiorrhiza extracts improved the renal injury and regulation of abnormal glycolipid metabolism. The metabolites in serum, urine and renal tissues have been changed significantly. The involved metabolic pathways mainly include phospholipid, arachidonic acid, and pyrimidine metabolisms. Meanwhile, SM inhibited the relative expression levels of wnt4, β-catenin and TGF-β in renal tissue and high-glucose induced glomerular mesangial cells.

Immunomodulatory Effects of the Nutraceutical Garlic Derivative Allicin in the Progression of Diabetic Nephropathy

Diabetic nephropathy (DN) is presently the primary cause of chronic kidney disease and end-stage renal disease (ESRD). It has been suggested that inflammation and oxidative stress, in addition to or in concert with the metabolic changes, plays an important role in the maintenance and progression of the disease. Therefore, attenuating or blocking these mechanisms may be a therapeutic target to delay the progression of the disease. Diallyl thiosulfinate (allicin), a compound derived from garlic, inhibits free radical formation, increases glutathione synthesis and decreases the levels of proinflammatory molecules in vitro. This research aimed to assess the effect of allicin on oxidative stress and inflammation-induced diabetes. Animals were divided into control and diabetes (streptozotocin 50 mg/kg i.p.), and maintained for 30 days. After 30 days, the group of diabetic animals was subdivided into diabetes and allicin-treated diabetes (16 mg/kg/day oral gavage). The three experimental groups were maintained for another month. We analyzed the status of renal function, oxidative stress and proinflammatory cytokines. The untreated diabetic group showed hyperglycemia and increased diuresis, creatinine clearance, proteinuria, glycosuria and urinary excretion of N-acetyl-β-d-glucosaminidase (NAG), as well as increased oxidative stress and the expression of interleukin 1β (IL-1β), IL-6, nuclear factor kappa beta (NFκβ) and transforming growth factor-β1 (TGF-β1) in plasma and kidney. In contrast, the inhibitor of NFκβ (Iκβ) is decreased in the cortex. It has been demonstrated that the allicin treatment decreases hyperglycemia, polyuria, and NAG excretion. The oxidative stress and proinflammatory cytokines were also reduced by the allicin treatment. In conclusion, allicin delays the progression of diabetic nephropathy through antioxidant and anti-inflammatory mechanisms.

Dysregulation of lncRNAs GM5524 and GM15645 involved in high‑glucose‑induced podocyte apoptosis and autophagy in diabetic nephropathy

Diabetic nephropathy (DN) is an important microvascular complication of diabetes, and one of the leading causes of end‑stage kidney disease. However, the mechanism of the DN pathogenic process remains unclear. Recently, long non‑coding (lnc)RNA dysregulation has been regarded to cause the occurrence and development of various human diseases, although the functions of lncRNAs in human DN are poorly understood. The authors' previous study using microarray analysis identified hundreds of dysregulated lncRNAs in DN, although the functions of these lncRNAs were not demonstrated. Out of those dysregulated lncRNAs, Gm5524 was significantly upregulated in response to DN, while Gm15645 was significantly downregulated in response to DN. In the present study, this result was further validated by reverse transcription‑quantitative polymerase chain reaction assays, and downregulating or overexpressing Gm5524 and Gm15645 in mouse podocytes. Notably, knockdown of Gm5524 and overexpression of Gm15645 induced mouse podocyte apoptosis and decreased cell autophagy in high‑glucose culture conditions. In conclusion, the results of the present study revealed the roles of lncRNAs Gm5524 and Gm15645 in high‑glucose induced podocyte apoptosis and autophagy during DN, which may further the understanding of the involvement of lncRNAs in DN, and provide a potential novel therapeutic target for this disease.

ERp44 depletion exacerbates ER stress and aggravates diabetic nephropathy in db/db mice

Diabetic nephropathy (DN) is a major complication of diabetes, and the dysfunction of endoplasmic reticulum (ER) plays an important role in its pathogenesis. ERp44, an ER resident chaperone protein, has been implicated in the modulation of ER stress, however, its role and mechanism in DN are not determined. Here, we show that ERp44 expression is upregulated in the glomeruli of db/db mice, a rodent model of type 2 diabetes. When ERp44 is depleted by in vivo shRNA-mediated knockdown, the features associated with DN including albuminuria level and glomerular basement membrane (GBM) thickness are aggravated, therefore suggesting a detrimental role of ERp44 depletion in DN progression. We further show that ERp44 depletion exacerbates ER stress in DN in db/db mice, and that attenuating ER stress with the chemical chaperone TUDCA remarkably diminishes the aggravated DN features caused by ERp44 depletion. These results suggest that the exacerbated ER stress is a critical factor for the detrimental effect of ERp44 depletion on DN progression in db/db mice. Thus, our study links the role of ERp44 in DN with ER stress regulation and may offer a potential therapeutic strategy to interfere DN progression.

Diabetic nephropathy: newer therapeutic perspectives

Diabetic nephropathy (DN is a dreaded consequence of diabetes mellitus, accounting for about 40% of end-stage renal disease (ESRD). It is responsible for significant morbidity and mortality, both directly by causing ESRD and indirectly by increasing cardiovascular risk. Extensive research in this field has thrown light on multiple pathways that can be pharmacologically targeted, to control or reverse the process of DN. Glomerulocentric approach of DN still continues to produce favourable results as evidenced by the recent data on SGLT-2 (sodium glucose co-transporter type 2) inhibitors. Beyond the glomerular mechanisms, numerous novel pathways have been discovered in the last decade. Some of these pathways target inflammatory and oxidative damage, while the others target more specific mechanisms such as AGE-RAGE (advanced glycation end products-receptors for advanced glycation end products), ASK (apoptotic signal-regulating kinase), and endothelin-associated pathways. As a result of the research, a handful of clinically relevant drugs have made it to the human trials which have been elucidated in the following review, bearing in the mind that there are many more to come over the next few years. Ongoing research is expected to inform the clinicians regarding the use of the newer drugs in DN. Abbreviations: USFDA: Unites States Food and Drug Administration; SGLT-2: Sodium glucose transporter type 2; GLP-1: Glucagon-like peptide-1; DDP-4: Dipeptidyl peptidase-4; UACR: urinary albumin creatinine ratio; eGFR: Estimated glomerular filtration rate; CKD: Chronic kidney disease; DN: Diabetic nephropathy; TGF: Tubuloglomerular feedback; RAAS: Renin angiotensin aldosterone system; T1DM: Type 1 diabetes mellitus; T2DM: Type 2 diabetes mellitus; RCT: Randomized controlled trial; AGE-RAGE: Advanced glycation end products-receptors for advanced glycation end products; ASK-1: Apoptotic signal-regulating kinase-1; Nrf-2: Nuclear 1 factor [erythroid derived-2]-related factor 2; ml/min/1.73m²: Millilitre/minute/1.73 square meters of body surface area; ~: Approximately.

Regulation of Carbohydrate Energy Metabolism in Drosophila melanogaster

Carbohydrate metabolism is essential for cellular energy balance as well as for the biosynthesis of new cellular building blocks. As animal nutrient intake displays temporal fluctuations and each cell type within the animal possesses specific metabolic needs, elaborate regulatory systems are needed to coordinate carbohydrate metabolism in time and space. Carbohydrate metabolism is regulated locally through gene regulatory networks and signaling pathways, which receive inputs from nutrient sensors as well as other pathways, such as developmental signals. Superimposed on cell-intrinsic control, hormonal signaling mediates intertissue information to maintain organismal homeostasis. Misregulation of carbohydrate metabolism is causative for many human diseases, such as diabetes and cancer. Recent work in Drosophila melanogaster has uncovered new regulators of carbohydrate metabolism and introduced novel physiological roles for previously known pathways. Moreover, genetically tractable Drosophila models to study carbohydrate metabolism-related human diseases have provided new insight into the mechanisms of pathogenesis. Due to the high degree of conservation of relevant regulatory pathways, as well as vast possibilities for the analysis of gene-nutrient interactions and tissue-specific gene function, Drosophila is emerging as an important model system for research on carbohydrate metabolism.

The KCa3.1 blocker TRAM34 reverses renal damage in a mouse model of established diabetic nephropathy

Despite optimal control of hyperglycaemia, hypertension, and dyslipidaemia, the number of patients with diabetic nephropathy (DN) continues to grow. Strategies to target various signaling pathways to prevent DN have been intensively investigated in animal models and many have been proved to be promising. However, targeting these pathways once kidney disease is established, remain unsatisfactory. The clinical scenario is that patients with diabetes mellitus often present with established kidney damage and need effective treatments to repair and reverse the kidney damage. In this studies, eNOS-/- mice were administered with streptozotocin to induce diabetes. At 24 weeks, at which time we have previously demonstrated albuminuria and pathological changes of diabetic nephropathy, mice were randomised to receive TRAM34 subcutaneously, a highly selective inhibitor of potassium channel KCa3.1 or DMSO (vehicle) for a further 14 weeks. Albuminuria was assessed, inflammatory markers (CD68, F4/80) and extracellular matrix deposition (type I collagen and fibronectin) in the kidneys were examined. The results clearly demonstrate that TRAM34 reduced albuminuria, decreased inflammatory markers and reversed extracellular matrix deposition in kidneys via inhibition of the TGF-β1 signaling pathway. These results indicate that KCa3.1 blockade effectively reverses established diabetic nephropathy in this rodent model and provides a basis for progressing to human studies.

CK2α promotes advanced glycation end products-induced expressions of fibronectin and intercellular adhesion molecule-1 via activating MRTF-A in glomerular mesangial cells

Advanced glycation end products' (AGEs) modification of extracellular matrix proteins induces crosslinking, which results in thickening of the basement membrane and activating several intracellular signaling cascades, eventually promoting the pathological progression of diabetic nephropathy (DN). We have previously confirmed that casein kinase 2α (CK2α) activates the nuclear factor of kappaB (NF-κB) signaling pathway to enhance high glucose-induced expressions of fibronectin (FN) and intercellular adhesion molecule-1 (ICAM-1) in glomerular mesangial cells (GMCs). However, to date, the mechanism by which CK2α regulates diabetic renal fibrosis is not fully understood. In view of the regulation of inflammation and fibrosis by myocardin-related transcription factor A (MRTF-A), we are highly concerned whether CK2α promotes AGEs-induced expressions of FN and ICAM-1 in glomerular mesangial cells via activation of MRTF-A, thus affecting the pathogenesis of DN. We found that CK2α and MRTF-A proteins were overexpressed in AGEs-induced diabetic kidneys. Inhibition of CK2α kinase activity or knockdown of CK2α protein expression suppressed the upregulation of FN and ICAM-1 expressions in GMCs induced by AGEs. MRTF-A knockdown compromised the expressions of FN and ICAM-1 in GMCs induced by AGEs. Moreover, inhibition of CK2α kinase activity or knockdown of CK2α protein expression restrained the protein expression and nuclear aggregation of MRTF-A. CK2α interacted with MRTF-A. Furthermore, knockdown of MRTF-A while overexpression of CK2α blocked the upregulation effect of CK2α on the protein expressions of FN and ICAM-1. These findings suggest that CK2α promotes diabetic renal fibrosis via activation of MRTF-A and upregulation of inflammatory genes.

Combined Detection of Urinary Micro Albumin, α1-microglobulin and N-acetyl-β-D-glucosaminidase in the Early Diagnosis of Diabetic Nephropathy

Objective:

To analyze the values of combined detection of urinary micro albumin (mAlb), α1-microglobulin (α1-MG) and N-acetyl-β-D-glucosaminidase (NAG) in the early diagnosis of diabetic nephropathy (DN).

Methods:

Ninety-four patients with early DN who were admitted to the hospital between April 2015 and April 2016 were selected and set as a DN group. Moreover, seventy-six patients with diabetes who were admitted to the hospital in the same period were selected and set as a diabetes group, and sixty-four healthy people were selected as set as a control group. The urinary mAlb, α1-MG and NAG of the three groups were detected. Moreover, the patients were divided into a favorable blood glucose control group and a poor blood glucose control group according to the blood glucose control condition of the patients. The detection results of the three groups were compared and statistically analyzed.

Results:

The urinary mAlb, α1-MG and NAG levels of the DN group were significantly higher than those of the diabetes group and control group, and the differences had statistical significance (P<0.05). The detection indicator values of the favorable blood glucose control group were much lower than those of the poor blood glucose control group, and the difference was statistically significant (P<0.05). The positive rate of the combined detection of mAlb, α1-MG and NAG levels was 90.2%, which was much higher than that of single indicator (P<0.05).

Conclusion:

Combined detection of urinary mAlb, α1-MG and NAG is sensitive in diagnosing early renal damages in DN patients.