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

The importance of paraoxonase 1 activity in chronic kidney disease

Paraoxonase 1 (PON1) is one of the most significant antioxidative enzymes associated with high-density lipoprotein (HDL). It has been proved that is involved in the pathogenesis of many diseases including chronic kidney disease (CKD). The association between PON1 and CKD seems to be mutual, such that the disease produces a significant decrease in PON1 activity levels, while the genetics of PON1 may affect the risk of susceptibility to CKD. Recent studies reveal that the decrease in serum PON1 activity observed in non-dialyzed and dialyzed CKD patients as well as in renal transplant (RT) patients is linked to an increased vulnerability to atherosclerosis. We intend to summarize current literature concerning PON1 activity in CKD, highlighting on the main determinants of PON1 activity, its association with oxidative stress, the impact of its genetic polymorphism on the disease development, the effect of drugs and nutritional state. Furthermore, evidence supporting the implication of reduced PON1 activity in the incident of cardiovascular disease in CKD patients, is also examined. It appears that despite the lack of standardization of PON1 activity measurement, PON1 remains a valuable biomarker for the researchers through the last decades, which contributes to the assessment of the antioxidant status having prognostic benefit on adverse clinical outcomes at various stages and etiologies of kidney disease.

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).

LINC01232 targeting miR-1250-3p/MSH2 axis attenuates mesangial cell proliferation and fibrosis in diabetic nephropathy

The significance of long non-coding RNA (ncRNAs) in the initiation and progression of diabetic nephropathy (DN) has attracted much interest. The purpose of this work was to ascertain the role of LINC01232 in cell models and animal models of DN. C57BL/6 J mice were administered with streptozotocin (STZ) to develop animal models of DN, and mouse glomerular mesangial cells (MCs) were exposed to high glucose (HG) to establish cell models of DN. Expression levels of LINC01232, miR-1250-3p and MSH2 were identified by quantitative real-time PCR (qPCR) or western blotting. Fibrosis-related proteins were quantified by western blotting. MC proliferative capacity was checked by EdU assay. DN progression and fibrosis level in animal models were assessed by hematoxylin and eosin (HE) and Masson staining. The potential binding sites between miR-1250-3p and LINC01232 or MSH2 were examined by dual-luciferase reporter assay. LINC01232 expression was heightened in kidney tissues of DN patients. Its overexpression in HG-treated MCs alleviated MC proliferation and fibrosis. Overexpression of LINC01232 alleviated the pathological state of glomerular hypertrophy, MC hyperplasia, basement membrane thickening, and fibrosis in the DN models. LINC01232 bound to miR-1250-3p and competed for miR-1250-3p binding sites with MSH2. LINC01232 overexpression decoyed miR-1250-3p to increase MSH2 expression, and MSH2 depletion restored LINC01232 overexpression-inhibited MC proliferation and fibrosis. LINC01232 alleviated the mesangial cell proliferation and fibrosis in the progression of DN by targeting miR-1250-3p/MSH2 pathway.

Quercetin prevented diabetic nephropathy by inhibiting renal tubular epithelial cell apoptosis via the PI3K/AKT pathway

Diabetic nephropathy (DN) is the most common and serious complication of diabetes, posing a significant threat to human health. Currently, safe and effective preventive strategies for DN are lacking. The study aimed to explore the preventive effect and the underlying mechanism of quercetin against DN. In the in vivo experiments, we established a mouse model of type 2 diabetes mellitus (T2DM) induced by a combination of high-fat diet (HFD) and streptozotocin (STZ) to explore the preventive effect of quercetin on DN and its protective role against renal tubular epithelial cell apoptosis. Subsequently, in vitro experiments using human tubular epithelial cells (HK-2 cells) were conducted to further validate the protective effects of quercetin on renal tubular epithelial cell apoptosis. Additionally, we employed RNA sequencing analysis (RNA-seq) and network pharmacology analysis to comprehensively elucidate the molecular mechanisms involved. In vivo, we observed a significant increase in the ratio of urinary microalbumin to creatinine in diabetic mice compared to control mice, accompanied by the activation of renal tubular epithelial cell apoptosis. Remarkably, all of these changes were reversed after quercetin treatment. In vitro, high-glucose-induced apoptosis in HK-2 cells was significantly attenuated by quercetin. Subsequent RNA sequencing analysis and network pharmacology analysis revealed that quercetin was most likely to inhibit high-glucose-induced HK-2 cell apoptosis through the PI3K/AKT signaling pathway. Western Blotting results further demonstrated that quercetin could inhibit the activation of the PI3K/AKT signaling pathway in HK-2 cells induced by high glucose. Our results supported that quercetin could prevent DN by inhibiting tubular epithelial cell apoptosis via the PI3K/AKT pathway. Quercetin might be a promising candidate for the prevention of DN.

Zinc oxide nanoparticles prevent the onset of diabetic nephropathy by inhibiting multiple pathways associated with oxidative stress

BACKGROUND

Zinc deficiency is strongly correlated with prolonged diabetes mellitus and diabetic nephropathy (DN). Previously, glucose-lowering, insulinomimetic, and β-cell proliferative activities of zinc oxide nanoparticles (ZON) have been reported. Considering these pleiotropic effects, we hypothesized that ZON modulates multiple cellular pathways associated with necroptosis, inflammation, and renal fibrosis, which are involved in progressive loss of renal function.

AIM

This study evaluated the effect of ZON on renal function, leading to the alleviation of DN in streptozotocin (STZ)-induced type 1 diabetic Wistar rats and proposed a probable mechanism for its activity.

METHODS

Wistar rats (n = 6/group) were used as healthy controls, diabetic controls, diabetic rats treated with ZON (1, 3, and 10 mg/kg), and insulin controls. Urine and serum biochemical parameters, glomerular filtration rate (GFR), and renal histology were also evaluated. Cultured E11 podocytes were evaluated in vitro for markers of oxidative stress, proteins associated with the loss of renal function, and genes associated with renal damage.

KEY FINDINGS

STZ-treated rats receiving oral doses of ZON showed enhanced renal function, with no histological alterations in the kidney tissue. ZON inhibited the TGF-β/Samd3 pathway in renal fibrosis; blocked Ripk1/Ripk3/Mlkl mediated necroptosis and protected against hyperglycemia-induced pyroptosis. In E11 podocytes, ZON reduced oxidative stress under high glucose conditions and retained podocyte-specific proteins.

SIGNIFICANCE

A probable mechanism by which ZON prevents DN has been proposed, suggesting its use as a complementary therapeutic agent for the treatment of diabetic complications. To the best of our knowledge, this is the first study to demonstrate the in vitro effects of ZON in cultured podocytes.

Vitamin D is involved in the effects of the intestinal flora and its related metabolite TMAO on perirenal fat and kidneys in mice with DKD

BACKGROUND

Vitamin D was shown to directly exert a protective effect on diabetic kidney disease (DKD) in our previous study. However, whether it has an effect on perirenal adipose tissue (PRAT) or the intestinal flora and its metabolites (trimethylamine N-oxide, TMAO) is unclear.

METHODS

DKD mice were received different concentrations of 1,25-(OH)2D3 for 2 weeks. Serum TNF-α levels and TMAO levels were detected. 16S rRNA sequencing was used to analyze gut microbiota. qPCR was used to detect the expression of TLR4, NF-Κb, PGC1α, and UCP-1 in kidney and adipose tissue. Histological changes in kidney and perirenal adipose tissue were observed using HE, PAS, Masson and oil red staining. Immunofluorescence and immunohistochemistry were used to detect the expression of VDR, PGC1α, podocin, and UCP-1 in kidney and adipose tissue. Electron microscopy was used to observe the pathological changes in the kidney. VDR knockout mice were constructed to observe the changes in the gut and adipose tissue, and immunofluorescence and immunohistochemistry were used to detect the expression of UCP-1 and collagen IV in the kidney.

RESULTS

1,25-(OH)2D3 could improve the dysbiosis of the intestinal flora of mice with DKD, increase the abundance of beneficial bacteria, decrease the abundance of harmful bacteria, reduce the pathological changes in the kidney, reduce fat infiltration, and downregulate the expression of TLR4 and NF-κB in kidneys. The serum TMAO concentration in mice with DKD was significantly higher than that of the control group, and was significantly positively correlated with the urine ACR. In addition, vitamin D stimulated the expression of the surface markers PGC1α, UCP-1 and VDR in the PRAT in DKD mice, and TMAO downregulated the expression of PRAT and renal VDR.

CONCLUSIONS

The protective effect of 1,25-(OH)2D3 in DKD mice may affect the intestinal flora and its related metabolite TMAO on perirenal fat and kidneys.

Glucose regulation by newly synthesized boronic acid functionalized molecules as dipeptidyl peptidase IV inhibitor: a potential compound for therapeutic intervention in hyperglycaemia

Management of type 2 diabetes mellitus (T2DM) using dipeptidyl peptidase IV (DPP IV) inhibitors is gaining precedence as this enzyme plays an indispensable role in cleaving and inactivating peptides, such as glucagon-like peptide-1 (GLP-1), incretin hormones, and glucose-dependent insulinotropic polypeptide (GIP). There are several DPP IV inhibitors used to treat T2DM, but limited by side effects such as disturbed GIT, flu-like symptoms, etc. Thus, there is an urgent need for the development of novel and better DPP IV inhibitors for the management of the same. In the present study, we investigated the effect of new boronic acid-based thiazole compounds as DPP IV inhibitors. We used substituted anilines that were progressively modified through a multi-step synthesis and then chemically characterised. These molecules have good binding affinity and molecular interactions at the active site of the DPP IV enzyme. Two boronic acid-based molecules, i.e. PC06R58 and PC06R108, were used for the assessment of their in-vitro enzymatic activities. Both molecules (PC06108 and PC06R58) exhibited potent uncompetitive DPP IV enzyme inhibition at two different concentrations of 90.9 and 15.6 nM, respectively, compared to sitagliptin having an IC50 of 17.3 nM. Furthermore, the oral glucose tolerance test suggested significantly reduced blood glucose levels at 20 mg/kg of the body weight upon administration of PC06R58 and PC06R108 molecules in rats after glucose ingestion (2 g/kg of the body weight). The compounds showed satisfactory DPP IV inhibition. Furthermore, DPP IV inhibitory activity and acceptable pre-ADME/Tox profile indicate it is a lead compound in this novel class of DPP IV inhibitors.Communicated by Ramaswamy H. Sarma.

The therapeutic effect of mesenchymal stem cells in diabetic kidney disease

Diabetes mellitus (DM) often causes chronic kidney damage despite best medical practices. Diabetic kidney disease (DKD) arises from a complex interaction of factors within the kidney and the whole body. Targeting specific disease-causing agents using drugs has not been effective in treating DKD. However, stem cell therapies offer a promising alternative by addressing multiple disease pathways and promoting kidney regeneration. Mesenchymal stem cells (MSCs) offer great promise due to their superior accessibility ratio from adult tissues and remarkable modes of action, such as the production of paracrine anti-inflammatory and cytoprotective substances. This review critically evaluates the development of MSC treatment for DKD as it moves closer to clinical application. Results from animal models suggest that systemic MSC infusion may positively impact DKD progression. However, few registered and completed clinical trials exist, and whether the treatments are effective in humans is still being determined. Significant knowledge gaps and research opportunities exist, including establishing the ideal source, dose, and timing of MSC delivery, better understanding of in vivo mechanisms, and developing quantitative indicators to obtain a more significant therapeutic response. This paper reviews recent literature on using MSCs in preclinical and clinical trials in DKD. Potent biomarkers related to DKD are also highlighted, which may help better understand MSCs' action in this disease progression. KEY MESSAGES: Mesenchymal stem cells have anti-inflammatory and paracrine effects in diabetic kidney disease. Mesenchymal stem cells alleviate in animal models having diabetic kidney disease. Mesenchymal stem cells possess promise for the treatment of diabetic kidney disease.

The therapeutic effect of mesenchymal stem cells in diabetic kidney disease

Abstract

Diabetes mellitus (DM) often causes chronic kidney damage despite best medical practices. Diabetic kidney disease (DKD) arises from a complex interaction of factors within the kidney and the whole body. Targeting specific disease-causing agents using drugs has not been effective in treating DKD. However, stem cell therapies offer a promising alternative by addressing multiple disease pathways and promoting kidney regeneration. Mesenchymal stem cells (MSCs) offer great promise due to their superior accessibility ratio from adult tissues and remarkable modes of action, such as the production of paracrine anti-inflammatory and cytoprotective substances. This review critically evaluates the development of MSC treatment for DKD as it moves closer to clinical application. Results from animal models suggest that systemic MSC infusion may positively impact DKD progression. However, few registered and completed clinical trials exist, and whether the treatments are effective in humans is still being determined. Significant knowledge gaps and research opportunities exist, including establishing the ideal source, dose, and timing of MSC delivery, better understanding of in vivo mechanisms, and developing quantitative indicators to obtain a more significant therapeutic response. This paper reviews recent literature on using MSCs in preclinical and clinical trials in DKD. Potent biomarkers related to DKD are also highlighted, which may help better understand MSCs’ action in this disease progression.

Key messages

Comprehensive Analysis of Fatty Acid Metabolism in Diabetic Nephropathy from the Perspective of Immune Landscapes, Diagnosis and Precise Therapy

Objective

Diabetic nephropathy (DN) represents the principal cause of end-stage renal diseases worldwide, lacking effective therapies. Fatty acid (FA) serves as the primary energy source in the kidney and its dysregulation is frequently observed in DN. Nevertheless, the roles of FA metabolism in the occurrence and progression of DN have not been fully elucidated.

Methods

Three DN datasets (GSE96804/GSE30528/GSE104948) were obtained and combined. Differentially expressed FA metabolism-related genes were identified and subjected to DN classification using "ConsensusClusterPlus". DN subtypes-associated modules were discovered by "WGCNA", and module genes underwent functional enrichment analysis. The immune landscapes and potential drugs were analyzed using "CIBERSORT" and "CMAP", respectively. Candidate diagnostic biomarkers of DN were screened using machine learning algorithms. A prediction model was constructed, and the performance was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). The online tool "Nephroseq v5" was conducted to reveal the clinical significance of the candidate diagnostic biomarkers in patients with DN. A DN mouse model was established to verify the biomarkers' expression.

Results

According to 39 dysregulated FA metabolism-related genes, DN samples were divided into two molecular subtypes. Patients in Cluster B exhibited worse outcomes with a different immune landscape compared with those in Cluster A. Ten potential small-molecular drugs were predicted to treat DN in Cluster B. The diagnostic model based on PRKAR2B/ANXA1 was created with ideal predictive values in early and advanced stages of DN. The correlation analysis revealed significant association between PRKAR2B/ANXA1 and clinical characteristics. The DN mouse model validated the expression patterns of PRKAR2B/ANXA1.

Conclusion

Our study provides new insights into the role of FA metabolism in the classification, immunological pathogenesis, early diagnosis, and precise therapy of DN.

Integrating network pharmacology and experimental validation to decipher the mechanism of the Chinese herbal prescription modified Shen-Yan-Fang-Shuai formula in treating diabetic nephropathy

CONTEXT

Diabetic nephropathy (DN) is the main cause of end-stage renal disease. Modified Shen-Yan-Fang-Shuai formula (M-SYFSF) has excellent clinical efficacy in treating diabetic kidney disease. However, the potential mechanism of M-SYFSF remains unknown.

OBJECTIVE

To investigate the mechanism of M-SYFSF against DN by network pharmacological analysis and biological experiments.

MATERIALS AND METHODS

Utilizing a web-based pharmacology database, the potential mechanisms of M-SYFSF against DN were identified. In vivo experiments, male SD rats were injected with streptozotocin (50 mg/kg) and got uninephrectomy to construct a model of DN. M-SYFSF (11.34 g/kg/d) was gavaged once per day for 12 weeks after model establishment. In vitro experiments, human proximal tubular cells (HK-2) were performed with advanced glycation end-products (AGEs) (100 μg/mL), then intervened with M-SYFSF freeze-dried powder. Pathological staining, WB, IHC, ELISA were conducted to explore the mechanism of M-SYFSF against DN.

RESULTS

Network pharmacological analysis showed that MAPK pathway was the potential pathway. Results showed that compared with the Model group, M-SYFSF significantly reduced 24h urine albumin, UACR, and serum creatinine levels (54.90 ± 26.67 vs. 111.78 ± 4.28, 8.87 ± 1.69 vs. 53.94 ± 16.01, 11.56 ± 1.70 vs. 118.70 ± 49.57, respectively), and improved renal pathological changes. Furthermore, the intervention of M-SYFSF reduced the expression of pro-inflammatory cytokines and inhibited the activation of MAPK pathway in AGEs-treated HK-2 cells.

DISCUSSION AND CONCLUSION

M-SYFSF is likely to reduce inflammation in DN by inhibiting the MAPK pathway. It provides a theoretical basis for the clinical application of M-SYFSF in the treatment of DN.

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.

The potential mechanism of gut microbiota-microbial metabolites-mitochondrial axis in progression of diabetic kidney disease

Diabetic kidney disease (DKD), has become the main cause of end-stage renal disease (ESRD) worldwide. Lately, it has been shown that the onset and advancement of DKD are linked to imbalances of gut microbiota and the abnormal generation of microbial metabolites. Similarly, a body of recent evidence revealed that biological alterations of mitochondria ranging from mitochondrial dysfunction and morphology can also exert significant effects on the occurrence of DKD. Based on the prevailing theory of endosymbiosis, it is believed that human mitochondria originated from microorganisms and share comparable biological characteristics with the microbiota found in the gut. Recent research has shown a strong correlation between the gut microbiome and mitochondrial function in the occurrence and development of metabolic disorders. The gut microbiome's metabolites may play a vital role in this communication. However, the relationship between the gut microbiome and mitochondrial function in the development of DKD is not yet fully understood, and the role of microbial metabolites is still unclear. Recent studies are highlighted in this review to examine the possible mechanism of the gut microbiota-microbial metabolites-mitochondrial axis in the progression of DKD and the new therapeutic approaches for preventing or reducing DKD based on this biological axis in the future.

Increased Levels of Circulating IGFBP4 and ANGPTL8 with a Prospective Role in Diabetic Nephropathy

Diabetic nephropathy (DN) is a complicated condition related to type 2 diabetes mellitus (T2D). ANGPTL8 is a hepatic protein highlighted as a risk factor for DN in patients with T2D; additionally, recent evidence from DN studies supports the involvement of growth hormone/IGF/IGF-binding protein axis constituents. The potential link between ANGPTL8 and IGFBPs in DN has not been explored before. Here, we assessed changes in the circulating ANGPTL8 levels in patients with DN and its association with IGFBP-1, -3, and -4. Our data revealed a significant rise in circulating ANGPTL8 in people with DN, 4443.35 ± 396 ng/mL compared to 2059.73 ± 216 ng/mL in people with T2D (p < 0.001). Similarly, levels of IGFBP-3 and -4 were significantly higher in people with DN compared to the T2D group. Interestingly, the rise in ANGPTL8 levels correlated positively with IGFBP-4 levels in T2DM patients with DN (p < 0.001) and this significant correlation disappeared in T2DM patients without DN. It also correlated positively with serum creatinine and negatively with the estimated glomerular filtration rate (eGFR, All < 0.05). The area under the curve (AUC) on receiver operating characteristic (ROC) analysis of the combination of ANGPTL8 and IGFBP4 was 0.76 (0.69-0.84), p < 0.001, and the specificity was 85.9%. In conclusion, our results showed a significant increase in ANGPTL8 in patients with DN that correlated exclusively with IGFBP-4, implicating a potential role of both proteins in the pathophysiology of DN. Our findings highlight the significance of these biomarkers, suggesting them as promising diagnostic molecules for the detection of diabetic nephropathy.

Role of Magnesium in Diabetic Nephropathy for Better Outcomes

Diabetic nephropathy (DN) is a major cause of end-stage renal disease worldwide, resulting from uncontrolled diabetes. Oxidative stress plays a critical role in the pathophysiology of DN, leading to cellular damage and disease progression. Magnesium, an essential mineral, has emerged as a potential therapeutic agent due to its antioxidative, anti-inflammatory, and antifibrotic properties. An extensive literature search was conducted on Medline using the keywords "Diabetic nephropathy," "Magnesium," and "Chronic Kidney Disease," and the results published after 2000 were exclusively studied to build this review. This review aims to summarize the role of magnesium in DN and explore its therapeutic potential. Magnesium acts as a cofactor for antioxidant enzymes, directly scavenges reactive oxygen species, and enhances the expression of antioxidant proteins. Furthermore, magnesium exhibits anti-inflammatory effects by suppressing pro-inflammatory cytokine production and inhibiting inflammatory signaling pathways. Magnesium supplementation has been shown to reduce oxidative stress markers and improve antioxidant enzyme activities in clinical studies. Additionally, magnesium has been found to mitigate renal fibrosis, maintain tubular integrity and function, improve endothelial function, and modulate renal hemodynamics. Although limited clinical trials suggest the renoprotective effects of magnesium in DN, further research is needed to determine the optimal dosage, duration, and long-term effects of magnesium supplementation. Despite existing drawbacks and gaps in the literature, magnesium holds promise as adjunctive therapy for DN by targeting oxidative stress and preserving renal function.

Understanding the lncRNA/miRNA-NFκB regulatory network in Diabetes Mellitus: From function to clinical translation

Diabetes mellitus (DM) and its significant ramifications make out one of the primary reasons behind morbidity worldwide. Noncoding RNAs (ncRNAs), such as microRNAs and long noncoding RNAs, are involved in regulating manifold biological processes, including diabetes initiation and progression. One of the established pathways attributed to DM development is NF-κB signaling. Neurons, β cells, adipocytes, and hepatocytes are among the metabolic tissues where NF-κB is known to produce a range of inflammatory chemokines and cytokines. The direct or indirect role of ncRNAs such as lncRNAs and miRNAs on the NF-κB signaling pathway and DM development has been supported by many studies. As a result, effective diabetes treatment and preventive methods will benefit from a comprehensive examination of the interplay between NF-κB and ncRNAs. Herein, we provide a concise overview of the role of NF-κB-mediated signaling pathways in diabetes mellitus and its consequences. The reciprocal regulation of ncRNAs and the NF-κB signaling pathway in diabetes is then discussed, shedding light on the pathogenesis of the illness and its possible therapeutic interventions.

NQO1 alleviates renal fibrosis by inhibiting the TLR4/NF-κB and TGF-β/Smad signaling pathways in diabetic nephropathy

OBJECTIVE

Diabetic nephropathy (DN) is one of the main complications of diabetes, and inflammation and fibrosis play an important role in its progression. NAD(P)H: quinone oxidoreductase 1 (NQO1) protects cells from oxidative stress and damage caused by toxic quinones. In the present study, we aimed to investigate the protective effects of NQO1 against diabetes-induced renal inflammation and fibrosis and the underlying mechanisms.

METHODS

In vivo, the kidneys of type 2 diabetes model db/db mice were infected with adeno-associated virus vectors to induce NQO1 overexpression. In vitro, human renal tubular epithelial (HK-2) cells transfected with NQO1 pcDNA3.1(+) were cultured under high-glucose (HG) conditions. Gene and protein expression was assessed by quantitative real-time PCR, Western blotting, immunofluorescence, and immunohistochemical staining. Mitochondrial reactive oxygen species (ROS) were detected with MitoSOX Red.

RESULT

Our study revealed that the expression of NQO1 was markedly downregulated and that Toll-like receptor (TLR)4 and TGF-β1 expression was upregulated in vivo and in vitro under diabetic conditions. Overexpression of NQO1 suppressed proinflammatory cytokine (IL-6, TNF-α, MCP-1) secretion, extracellular matrix (ECM) (collagen IV, fibronectin) accumulation and epithelial-mesenchymal transition (EMT) (α-SMA, E-cadherin) in the db/db mouse kidneys and HG-cultured HK-2 cells. Furthermore, NQO1 overexpression ameliorated HG-induced TLR4/NF-κB and TGF-β/Smad pathways activation. Mechanistic studies demonstrated that a TLR4 inhibitor (TAK-242) suppressed the TLR4/NF-κB signaling pathway, proinflammatory cytokine secretion, EMT and ECM-related protein expression in HG-exposed HK-2 cells. In addition, we found that the antioxidants N-acetylcysteine (NAC) and tempol increased the expression of NQO1 and decreased the expression of TLR4, TGF-β1, Nox1, and Nox4 and ROS production in HK-2 cells cultured under HG conditions.

CONCLUSIONS

These data suggest that NQO1 alleviates diabetes-induced renal inflammation and fibrosis by regulating the TLR4/NF-κB and TGF-β/Smad signaling pathways.

Yiqi Huazhuo decoction increases insulin secretion in type 2 diabetic rats by regulating the pancreatic GPR40-IP3R-1 signaling pathway

Objective: Yiqi Huazhuo Decoction (YD) reduces blood glucose, glycated hemoglobin, body weight, and insulin resistance in patients with type 2 diabetes mellitus (T2DM), but its exact mechanisms are unknown. This study investigated the therapeutic effects and mechanisms of YD on impaired insulin secretion in T2DM rats.

Methods: T2DM rats were randomized to the model, YD-lo (15 mg/kg/d YD, 10 weeks), YD-hi (30 mg/kg/d YD, 10 weeks), positive drug (TAK-875), and healthy control groups. The rats underwent an oral glucose tolerance test (OGTT), glucose-stimulated insulin secretion (GSIS) test, and serum lipid measurements. High-fat and high-glucose-injured RIN-m5f cells were treated with YD (30 or 150 mg/mL) for 48 h. GPR40 and IP3R-1 expression levels were determined by immunofluorescence, qRT-PCR, and western blot.

Results: Compared with the model group, the OGTT area under the curve (AUC) in the YD-hi group was decreased by 26.7%, the insulin release test (IRT) AUC in the YD-hi group was increased by 45.9%, and the GSIS AUC was increased by 33.9% (p &lt; 0.05). Compared with the model cells, the insulin secretion after glucose stimulation in the YD-hi group was increased by 24.5%, similar to the TAK-875 group (23.1%) (p &gt; 0.05). GPR40 and IP3R-1 mRNA in the model cells were decreased by 49.5% and 51.2% compared with the control cells (p &lt; 0.05). In the YD-hi group, GPR40 and IP3R-1 mRNA levels were increased by 58.1% and 39.3% (p &lt; 0.05), similar to the TAK-875 group. The changes in protein expression were similar to mRNA.

Conclusion: YD promotes insulin secretion from pancreatic islet β-cell in T2DM rats by regulating the GPR40-IP3R-1 pathway, thereby reducing blood glucose.

Network pharmacology analysis combined with experimental validation to explore the therapeutic mechanism of Schisandra Chinensis Mixture on diabetic nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic nephropathy (DN) is one of the most common and serious microvascular complications of Diabetes mellitus (DM). The inflammatory response plays a critical role in DN. Schisandra Chinensis Mixture (SM) has shown promising clinical efficacy in the treatment of DN while the pharmacological mechanisms are still unclear.

AIM OF THE STUDY

In this study, a network pharmacology approach and bioinformatic analysis were adopted to predict the pharmacological mechanisms of SM in DN therapy. Based on the predicted results, molecular docking and in vivo experiments were used for verification.

MATERIALS AND METHODS

In this study, the candidate bioactive ingredients of SM were obtained via Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) and supplementing according to the literature. SM putative targets and the verified targets were acquired from TCMSP and SiwssTartgetPrediction Database. DN-related target genes were collected from GeneCards, OMIM, DisGeNET databases, and microarray data analysis. Biological function and pathway analysis were performed to further explore the pharmacological mechanisms of SM in DN therapy. The protein-protein interaction (PPI) network was established to screen the hub gene. The Receiver Operating Characteristic (ROC) analysis and the molecular docking simulations were performed to validate the potential target-drug interactions. The fingerprint spectrum of multi-components of the SM was characterized by UPLC-MS/MS. The signaling pathways associated with inflammation and hub genes were partially validated in SD rats.

RESULTS

A total of 36 bioactive ingredients were contained, and 666 component-related targets were screened from SM, of which 50 intersected with DN targets and were considered potential therapeutic targets. GO analyses revealed that the 50 intersection targets were mainly enriched in the inflammatory response, positive regulation of angiogenesis, and positive regulation of phosphatidylinositol 3-kinase(PI3K) signaling. KEGG analyses indicated that the PI3K-Akt signaling pathway was considered as the most important pathway for SM antagonism to the occurrence and development of DN, with the highest target count enrichment. PPI network results showed that the top 15 protein targets in degree value, VEGFA, JAK2, CSF1R, NOS3, CCR2, CCR5, TLR7, FYN, BTK, LCK, PLAT, NOS2, TEK, MMP1 and MCL1, were identified as hub genes. The results of ROC analysis showed that VEGFA and NOS3 were valuable in the diagnosis of DN. The molecular docking confirmed that the core bioactive ingredients had well-binding affinity for VEGFA and NOS3. The in vivo experiments confirmed that SM significantly inhibited the over-release of inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor receptor (TNF)-α in DN rats, while regulating the PI3K-AKT and VEGFA-NOS3 signaling pathways.

CONCLUSION

This study revealed the multi-component, multi-target and multi-pathway characteristics of SM therapeutic DN. SM inhibited the inflammatory response and improved renal pathological damage in DN rats, which was related to the regulation of the PI3K-Akt and VEGFA-NOS3 signaling pathways.

Beneficial effects of ginsenosides on diabetic nephropathy: A systematical review and meta-analysis of preclinical evidence

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng is one of the most widely used herbs in the world for the treatment of various diseases, and ginsenoside is the representative bioactive component in ginseng. There have been many in vivo studies on ginsenoside for the treatment of diabetic nephropathy (DN), the most common diabetic microvascular complication and the main cause of diabetic morbidity and mortality.

AIM OF THE STUDY

The purpose of this study is to evaluate the efficacy of ginsenosides on DN by preclinical evidence and meta-analysis. Meanwhile, the main possible action mechanisms of ginsenosides against DN were also summarized.

MATERIALS AND METHODS

We systematically searched PubMed, WOS, Embase, Cochrane, WanFang, Cqvip, CNKI and CBM databases from January 1, 2000, to November 15, 2021, to evaluate the animal experiments of ginsenosides for the treatment of DN. Finally, 30 animal experiments were included. Twelve outcome measures, including renal function indicators (24-h urine protein, serum creatinine, urea nitrogen, creatinine clearance, uric acid, urinary albumin to creatinine ratio), oxidative stress biomarkers (GPX, MDA, SOD), inflammatory factors (IL-1, IL-6, TNF-α) were obtained by using RevMan 5.4 software for meta-analysis.

RESULTS

The results showed that except for no significant difference in CCr, other indicators such as 24h UP, SCr, blood urea nitrogen, uric acid and UACR were significantly decreased. It showed that ginsenoside could improve renal function in diabetes. Meanwhile ginsenoside significantly up-regulated antioxidant enzymes SOD and GPX, down-regulated MDA and inflammatory factors IL-1, IL-6 and TNF-α, indicating that ginsenoside may have antioxidant and anti-inflammatory effects.

CONCLUSION

Ginsenoside can protect against the renal failure in diabetes through anti-inflammation, anti-oxidation, anti-renal fibrosis, anti-apoptosis/pyroptosis, regulation of blood glucose/lipid metabolism, etc. Which provides preclinical evidence for the application of ginsenoside in the treatment of DN.

Dapagliflozin alleviates renal fibrosis in a mouse model of adenine-induced renal injury by inhibiting TGF-β1/MAPK mediated mitochondrial damage

Renal fibrosis is a common pathological outcome of various chronic kidney diseases, and as yet, there is no specific treatment. Dapagliflozin has shown renal protection in some clinical trials as a glucose-lowering drug, but its role and mechanism on renal fibrosis remain unclear. In this study, we used a 0.2% adenine diet-induced renal fibrosis mouse model to investigate whether dapagliflozin could protect renal function and alleviate renal fibrosis in this animal model. In vivo, we found that dapagliflozin's protective effect on renal fibrosis was associated with 1) sustaining mitochondrial integrity and respiratory chain complex expression, maintained the amount of mitochondria; 2) improving fatty acid oxidation level with increased expression of CPT1-α, PPAR-α, ACOX1, and ACOX2; 3) reducing inflammation and oxidative stress, likely via regulation of IL-1β, IL-6, TNF-α, MCP-1, cxcl-1 expression, and glutathione (GSH) activity, superoxide dismutase (SOD) and malondialdehyde (MDA) levels; and 4) inhibiting the activation of the TGF-β1/MAPK pathway. In HK2 cells treated with TGF-β1, dapagliflozin reduced the expression of FN and α-SMA, improved mitochondrial respiratory chain complex expression, and inhibited activation of the TGF-β1/MAPK pathway.

Effective dose/duration of natural flavonoid quercetin for treatment of diabetic nephropathy: A systematic review and meta-analysis of rodent data

BACKGROUND

Given the challenges on diabetic nephropathy (DN) treatment, research has been carried out progressively focusing on dietary nutrition and natural products as a novel option with the objective of enhancing curative effect and avoiding adverse reactions. As a representative, Quercetin (Qu) has proved to be of great value in current data.

PURPOSE

We aimed to synthetize the evidence regarding the therapeutic effect and specific mechanism of quercetin on DN via systematically reviewing and performing meta-analysis.

METHODS

Preclinical literature published prior to August 2021, was systematical retrieval and manually filtrated across four major databases including PubMed, Web of Science, EMBASE and Cochrane library. Pooled overall effect sizes of results were generated by STATA 16.0, and underlying mechanisms were summarized. Three-dimensional dose/time-effect analyses and radar maps were conducted to examine the dosage/time-response relations between Qu and DN.

RESULTS

This paper pools all current available evidence in a comprehensive way, and shows the therapeutic benefits as well as potential action mechanisms of Qu in protecting the kidney against damage. A total of 304 potentially relevant citations were identified, of which 18 studies were enrolled into analysis. Methodological quality was calculated, resulting in an average score of 7.06/10. This paper provided the preliminary evidence that consumption of Qu could induce a statistical reduction in mesangial index, Scr, BUN, 24-h urinary protein, serum urea, BG, kidney index, TC, TG, LDL-C, AST, MDA, AGE, TNF-α, TGF-β1, TGF-β1 mRNA, CTGF and IL-1β, whereas HDL-C, SOD, GSH, GSH-Px, CAT and smad-7 were significantly increased. Furthermore, Qu could remarkably improve the renal pathology. In terms of the mechanisms underlying therapy of DN, Qu exerts anti-diabetic nephropathy properties possibly through PI3K/PKB, AMPK-P38 MAPK, SCAP/SREBP2/LDLr, mtROS-TRX/TXNIP/NLRP3/IL-1β, TGF-β1/Smad, Nrf2/HO-1, Hippo, mTORC1/p70S6K and SHH pathways. Dose/time-response images predicted a modest association between Qu dosage consumption/administration length and therapeutic efficacy, with the optimal dosage at 90-150 mg/kg/d and administration length ranging from 8 weeks to 12 weeks.

CONCLUSIONS

Quercetin exhibit highly pleiotropic actions, which simultaneously contributes to prevent fundamental progression of DN, such as hyperglycemia, dyslipidemia, inflammation, fibrotic lesions and oxidative stress. The therapeutic effect becomes stronger when Qu administration at higher dosages lasts for longer durations. Taken together, quercetin could be used in patients with DN as a promising agent, which has well-established safety profiles and nontoxicity according to existing literature.

Multi-omics analysis reveals the pathogenesis of db/db mice diabetic kidney disease and the treatment mechanisms of multi-bioactive compounds combination from Salvia miltiorrhiza

Diabetic kidney disease (DKD) is a common diabetic complication. Salvia miltiorrhiza has significant therapeutic effects on diabetes complications, although the mechanism remains unclear. Here, biochemical indicators and pathological changes were used to screen out the optimal Salvia miltiorrhiza multi-bioactive compounds combination. Metabolomics, transcriptomics and proteomics were used to explore the pathogenesis of DKD. RT-PCR and parallel reaction monitoring targeted quantitative proteome analysis were utilized to investigate treatment mechanisms of the optimal Salvia miltiorrhiza multi-bioactive compounds combination. The db/db mice showed biochemical abnormalities and renal lesions. The possible metabolic pathways were steroid hormone biosynthesis and sphingolipid metabolism. The 727 differential genes found in transcriptomics were associated with biochemical indicators via gene network to finally screen 11 differential genes, which were mainly key genes of TGF-β/Smad and PI3K/Akt/FoxO signaling pathways. Salvia miltiorrhiza multi-bioactive compounds combination could significantly regulate the Egr1, Pik3r3 and Col1a1 genes. 11 differentially expressed proteins involved in the two pathways were selected, of which 9 were significantly altered in db/db mice compared to db/m mice. Salvia miltiorrhiza multi-bioactive compounds combination could callback Q9DBM2, S4R1W1, Q91Y97, P47738, A8DUK4, and A2ARV4. In summary, Salvia miltiorrhiza multi-bioactive compounds combination may ameliorate kidney injury in diabetes through regulation of TGF-β/Smad and PI3K/Akt/FoxO signaling pathways.

Immune responses in diabetic nephropathy: Pathogenic mechanisms and therapeutic target

Diabetic nephropathy (DN) is a chronic, inflammatory disease affecting millions of diabetic patients worldwide. DN is associated with proteinuria and progressive slowing of glomerular filtration, which often leads to end-stage kidney diseases. Due to the complexity of this metabolic disorder and lack of clarity about its pathogenesis, it is often more difficult to diagnose and treat than other kidney diseases. Recent studies have highlighted that the immune system can inadvertently contribute to DN pathogenesis. Cells involved in innate and adaptive immune responses can target the kidney due to increased expression of immune-related localization factors. Immune cells then activate a pro-inflammatory response involving the release of autocrine and paracrine factors, which further amplify inflammation and damage the kidney. Consequently, strategies to treat DN by targeting the immune responses are currently under study. In light of the steady rise in DN incidence, this timely review summarizes the latest findings about the role of the immune system in the pathogenesis of DN and discusses promising preclinical and clinical therapies.

Galaxaura elongata Extract (GE) Modulates Vanadyl Sulfate-Induced Renal Damage via Regulating TGF-β/Smads and Nrf2/NF-κB Pathways

Nephrotoxicity becomes a provoked problem as the kidneys are the target of many chemotherapies. For this reason, we aimed to study the protective effect of Galaxaura elongata extract (GE) against the vanadyl sulfate (Van) induced nephrotoxicity in rats. Forty Wistar albino rats (male) were divided into four groups (n = 10) as follows: control group: rats received 0.5% carboxymethyl cellulose (CMC). Galaxa group: rats received GE at a dose (100 mg/kg orally) daily for 6 weeks. Van group: rats injected with Van at a dose (50 mg/kg i.p.) once weekly for 6 successive weeks. Galaxa + Van group: rats received GE at a dose (100 mg/kg orally) daily for 6 weeks concurrently with Van at a dose (50 mg/kg i.p.) for 6 weeks. Our results showed that Van significantly raised urea and creatinine serum levels as compared to the control group as well as disordered renal oxidative/antioxidant redox. Administration of GE with Van alleviated the adverse impact of Van over the kidney tissues. Furthermore, GE administration in Galaxa + Van group downregulates angiotensin-converting enzyme (ACE1) mRNA expression, angiotensin II (Ang II) concentration, transforming growth factor β (TGF-β) mRNA expression and protein concentration and Nuclear factor κB (NF-κB) mRNA expression as compared to Van group. Also, GE administration caused a noticeable upregulation of Nrf2 and heme oxygenase-1 (HO-1) expressions with a consequent decrease of DNA fragmentation % compared to Van group. The results of the current study show that simultaneous treatment with GE can alleviate nephrotoxicity caused by Van in diabetic rats. The GE treatment of the Van treated animals restored altered renal oxidative/antioxidant redox values towards normal and lessened fibrosis. These results are consistent with these effects being caused by interactions with the TGF-B/Smads and Nrf2/NF-κB signaling pathways.

The effect of quercetin on diabetic nephropathy (DN): a systematic review and meta-analysis of animal studies

Quercetin, a flavonoid possessing numerous biological activities, is reported to improve renal injury in diabetic animals. Here, the aim of this systematic review and meta-analysis is to assess the effect of quercetin on diabetic nephropathy and summarize its possible mechanisms. We searched in four databases PubMed, Web of Sciences (WOS), Cochrane and Embase from inception to May 2021 and ultimately included 20 animal studies in this review. A total of 12 outcome measurements including renal function indexes, oxidative stress biomarkers and inflammatory cytokines were extracted for meta-analysis using RevMan 5.4 software. Apart from creatinine clearance and uric acid with no significant difference, quercetin significantly decreased the levels of renal index, serum/plasma creatinine (SCr), blood urea nitrogen (BUN), urine protein, urine albumin, malondialdehyde (MDA), tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and increased superoxide dismutase (SOD) and catalase (CAT) activity. In short, quercetin improves renal function and attenuates the renal oxidative stress level and inflammatory response in DN animal models. Its possible action mechanisms include anti-oxidation, anti-inflammation, anti-fibrosis, and regulation of renal lipid accumulation.

Aloe-Emodin Ameliorates Diabetic Nephropathy by Targeting Interferon Regulatory Factor 4

Diabetic nephropathy (DN) is one of the leading causes of end-stage renal disease and lacks effective clinical treatment for its complicated pathogenesis. In this study, the gene expression profiles downloaded from the GEO database were used to identify the key regulatory gene through bioinformatics analyses, and the potential mechanism in regulating DN was revealed via the gene set enrichment analysis, pathway analysis, and in vitro phenotype detection. The effect of the screened drug on DN was analyzed through in vitro and in vivo model experiments. Interferon regulatory factor 4 (IRF4) in DN was identified to be upregulated compared with that in normal control tissues. Further results revealed that IRF4 promoted the DN progression through inflammation, immunity, and extracellular matrix remodeling. The screening results of the TCM library showed that aloe-emodin (Ae) should be a potentially active target drug, and the in vitro and in vivo experiment results demonstrated that Ae could ameliorate DN by targeting IRF4. In conclusion, this study revealed the mechanism of the DN progression and demonstrated that Ae could be a potential target drug in ameliorating DN, providing ideas for the clinical treatments for DN.

Danhong injection represses diabetic retinopathy and nephropathy advancement in diabetic mice by upregulating microRNA-30d-5p and targeting JAK1

Danhong injection (DHI) restrains diabetic retinopathy and nephropathy (DR and DN) advancement in diabetic mice. However, the downstream mechanism of its modulation is not fully studied. Diabetic model mice (db/db mice) were intravenously injected with DHI and corresponding virus particles. MiR-30d-5p and JAK1 were detected. The body weight and fasting blood glucose mice were measured every 4 weeks. The renal tissues and serum of mice were collected, and the contents of creatinine and blood urea nitrogen were biochemically analyzed. IL-6, IFN-γ and TNF-α were detected by ELISA, with the pathological conditions of renal tissues in mice by He staining, and the adjustment conditions by TUNEL. Human retinal pigment epithelium (ARPE-19) cells were selected to induce DR model in vitro by high glucose, and exposed to DHI for treatment. The corresponding plasmids were transfected, and miR-30d-5p and JAK1 were detected, with the proliferation ability by plate cloning, apoptosis by flow cytometry, and cell migration ability by Transwell. The angiogenesis ability of cells was assessed by tube formation assay. The targeting relationship between miR-30d-5p and JAK1 was detected. The results manifested that miR-30d-5p was declined in DR and DN, while JAK1 expression was elevated. DHI was able to improve DR and renal injury. DHI could regulate the miR-30d-5p-JAK1 axis in vivo, and miR-30d-5p targeted and regulated JAK1. Upregulation of miR-30d-5p or inhibition of JAK1 could improve DR and renal injury. The results implies that DHI can repress the development of DR and DN by elevating miR-30d-5p and targeting JAK1.

Kidney microRNA Expression Pattern in Type 2 Diabetic Nephropathy in BTBR Ob/Ob Mice

Diabetic nephropathy (DN) is the main leading cause of chronic kidney disease worldwide. Although remarkable therapeutic advances have been made during the last few years, there still exists a high residual risk of disease progression to end-stage renal failure. To further understand the pathogenesis of tissue injury in this disease, by means of the Next-Generation Sequencing, we have studied the microRNA (miRNA) differential expression pattern in kidneys of Black and Tan Brachyury (BTBR) ob/ob (leptin deficiency mutation) mouse. This experimental model of type 2 diabetes and obesity recapitulates the key histopathological features described in advanced human DN and therefore can provide potential useful translational information. The miRNA-seq analysis, performed in the renal cortex of 22-week-old BTBR ob/ob mice, pointed out a set of 99 miRNAs significantly increased compared to non-diabetic, non-obese control mice of the same age, whereas no miRNAs were significantly decreased. Among them, miR-802, miR-34a, miR-132, miR-101a, and mir-379 were the most upregulated ones in diabetic kidneys. The in silico prediction of potential targets for the 99 miRNAs highlighted inflammatory and immune processes, as the most relevant pathways, emphasizing the importance of inflammation in the pathogenesis of kidney damage associated to diabetes. Other identified top canonical pathways were adipogenesis (related with ectopic fatty accumulation), necroptosis (an inflammatory and regulated form of cell death), and epithelial-to-mesenchymal transition, the latter supporting the importance of tubular cell phenotype changes in the pathogenesis of DN. These findings could facilitate a better understanding of this complex disease and potentially open new avenues for the design of novel therapeutic approaches to DN.

Rosuvastatin Induces Renal HO-1 Activity and Expression Levels as a Main Protective Mechanism against STZ-Induced Diabetic Nephropathy

Background and Objectives: Nephroprotective effect of statins is still controversial. The aim of this study was to investigate the possible hemin-like nephroprotective effect of rosuvastatin (RSV) in streptozotocin (STZ)-induced diabetic rats. Materials and Methods: DN was induced in rats via a single dose of 50 mg/kg STZ i.p., with or without RSV (10 mg/kg orally) for 30 days. To investigate hemin-like effect of RSV on renal heme oxygenase-1 (HO-1), RSV was administered in the presence or absence of an inhibitor of HO-1; zinc protoporphyrin-XI (ZnPP), in a dose of 50 µmol/kg i.p. Results: Induction of diabetes with STZ caused, as expected, significant hyperglycemia, as well as deteriorated kidney function, lipid profile and histopathological architecture. The DN group also showed renal oxidative stress, indicated by decreased superoxide dismutase, catalase, and reduced glutathione, with increased malondialdehyde, myeloperoxidase and nitric oxide. Renal expression of inflammatory marker TNF-α, and pro-apoptotic marker caspase 3, were also increased in the DN group. Administration of RSV in DN rats did not improve glucose level but succeeded in recovering kidney function and normal structure as well as improving the lipid profile. RSV also improved renal oxidative, inflammatory, and apoptotic statuses. Interestingly, the administration of RSV increased renal expression and activity of HO-1 compared to the untreated DN group. Co-administration of ZnPP blocked the effect of RSV on HO-1 and deteriorated all RSV favorable effects. Conclusions: RSV can protect against DN, at least in part, via increasing renal HO-1 expression and/or activity, which seems to be upstream to RSV antioxidant, anti-inflammatory, and anti-apoptotic effects.

Effects and Mechanism of Ganoderma lucidum Polysaccharides in the Treatment of Diabetic Nephropathy in Streptozotocin-Induced Diabetic Rats

Ganoderma lucidum polysaccharides (GLP) have renal protection effect but there was no study on the diabetic nephropathy. This study was designed to investigate its effect and mechanism using a diabetic rat model induced by streptozotocin (50 mg/kg, i.p.). The diabetic rats were treated with GLP (300 mg/kg/day) for 10 weeks. The blood glucose, glycated hemoglobin, body weight, and the levels of blood creatinine, urea nitrogen, and urine protein were assessed. And renal pathologies were assessed by the tissue sections stained with hematoxylin-eosin, Masson's trichome, and periodic acid-Schiff. The expression of phosphorylated phosphoinositide 3 kinase (p-PI3K), phosphorylated protein kinase B (p-Akt), and phosphorylated mammalian target of rapamycin (p-mTOR), the autophagy proteins beclin-1, LC3-II, LC3-I, and P62; the apoptosis-related proteins caspase-3 and caspase-9; and the inflammation markers IL-6, IL-1β, and TNF-ɑ were assessed. Results showed that GLP alleviated the impairment of renal function by reducing urinary protein excretion and the blood creatinine level and ameliorated diabetic nephropathy. The expression of p-PI3K, p-Akt, and p-mTOR in the diabetic kidney were significantly reduced in the GLP treatment group compared to the without treatment group. GLP treatment activated the autophagy indicators of beclin-1 and the ratio of LC3-II/LC3-I but reduced p62 and also inhibited the expression of caspase-3, caspase-9 and IL-6, IL-1β, and TNF-ɑ. In conclusion, the effect of GLP amelioration diabetic nephropathy may be via the PI3k/Akt/mTOR signaling pathway by inhibition of the apoptosis and inflammation and activation of the autophagy process.

Pathophysiologic Mechanisms and Potential Biomarkers in Diabetic Kidney Disease

Although diabetic kidney disease (DKD) remains the leading cause of end-stage kidney disease eventually requiring chronic kidney replacement therapy, the prevalence of DKD has failed to decline over the past 30 years. In order to reduce disease prevalence, extensive research has been ongoing to improve prediction of DKD onset and progression. Although the most commonly used markers of DKD are albuminuria and estimated glomerular filtration rate, their limitations have encouraged researchers to search for novel biomarkers that could improve risk stratification. Considering that DKD is a complex disease process that involves several pathophysiologic mechanisms such as hyperglycemia induced inflammation, oxidative stress, tubular damage, eventually leading to kidney damage and fibrosis, many novel biomarkers that capture one specific mechanism of the disease have been developed. Moreover, the increasing use of high-throughput omic approaches to analyze biological samples that include proteomics, metabolomics, and transcriptomics has emerged as a strong tool in biomarker discovery. This review will first describe recent advances in the understanding of the pathophysiology of DKD, and second, describe the current clinical biomarkers for DKD, as well as the current status of multiple potential novel biomarkers with respect to protein biomarkers, proteomics, metabolomics, and transcriptomics.

Protective effect of morin by targeting mitochondrial reactive oxygen species induced by hydrogen peroxide demonstrated at a molecular level in MDCK epithelial cells

BACKGROUND

The development of diabetic nephropathy is aided by the presence of oxidative stress. Morin, a natural flavonoid molecule, has been shown to have antioxidant and anti-diabetic properties. However, little is known about the mechanism of its protective effect in diabetic nephropathy pathogenesis caused by oxidative stress.

METHODS

Using Madin-Darby canine kidney (MDCK) cells as a working model, the current study investigates the detailed mechanism of morin's beneficial action. In hydrogen peroxide-induced oxidative stressed MDCK cells, there was a considerable rise in intracellular ROS and decreased antioxidant enzyme levels.

RESULTS

Morin has a higher binding affinity for the antioxidant receptor; according to in silico study using molecular docking and ADMET, it is predicted to be an orally active molecule. While morin administration increased SOD and CAT activity in oxidative stress-induced MDCK cells, it also reduced mitochondrial oxidative stress and apoptosis. Furthermore, the present study discovered the molecular mechanism through which morin reduced oxidative stress in MDCK cells by upregulating antioxidant enzyme molecules including GST, GPx, and GCS.

CONCLUSION

These findings suggest that morin reduces H₂O₂-induced oxidative stress, reduces DNA oxidative damage, and prevents the depletion of antioxidant genes in MDCK cells.

Trigonelline reverses high glucose-induced proliferation, fibrosis of mesangial cells via modulation of Wnt signaling pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of the end-stage renal disease (ESRD). The proliferation and apoptosis of mesangial cells induced by the activated Wnt/β-catenin pathway is crucial in DN. Trigonelline (TRL) is an alkaloid that has been shown to decrease proteinuria and protect the renal function in DN. However, the effect of TRL on the Wnt/β-catenin pathway of mesangial cells is unclear.

METHODS

As a cellular DN model, human mesangial cells (HMCs) were treated with high-glucose (HG). β-Catenin plasmid and control knockdown plasmids were transfected into HG-treated HMCs as β-catenin pcDNA and β-catenin siRNA groups, respectively. Cell viability was measured by MTT assay. Flow cytometry was used to detect the cell cycle. Cell apoptosis was evaluated by flow cytometry and terminal dUTP transferase nick end labeling (TUNEL) assay. mRNA expression of Wnt1, Wnt3a, Wnt4, Wnt5a, β-catenin, TCF4, Cyclin D1, and CDK4 were detected by qRT-PCR. Protein expression of Wnt4, Wnt5a, nucleus-β-catenin, TCF4, Cyclin D1, and CDK4 were detected by western blotting.

RESULTS

TRL significantly inhibited HG-induced HMCs viability over three-time points measured (24, 48, and 72 h). In addition, TRL suppressed the levels of fibronectin (FN) and collagen IV (Col IV) in HG-stimulated HMCs. Furthermore, TRL efficiently inhibited the activation of the Wnt/β-catenin signaling pathway in HG-stimulated HMCs. Taken together, these data indicated that TRL inhibited HG-induced HMCs proliferation and ECM expression via the modulation of the Wnt signaling pathway.

CONCLUSIONS

TRL reduces HG-induced cell injury by regulating the Wnt/β-catenin signaling pathway.

Protective effect of vanillic acid against diabetes and diabetic nephropathy by attenuating oxidative stress and upregulation of NF-κB, TNF-α and COX-2 proteins in rats

Diabetes is the most prevalent disorder in the world characterized by uncontrolled high blood glucose levels and nephropathy is one of the chief complications allied with hyperglycemia. Vanillic acid; the main bioactive compound derived from natural sources such as vegetables, fruits and plants possesses various pharmacological activities such as antioxidant, anti-inflammatory and anti-proliferative. The current study was designed to investigate the antidiabetic and renoprotective effects of vanillic acid by its various pharmacological activities. Streptozotocin (50 mg/kg)/nicotinamide (110 mg/kg) was used to induce diabetes in rats. Oral administration of vanillic acid once daily for 6 weeks (25, 50 and 100 mg/kg) significantly reduced the hyperglycemia, increased liver enzymes and normalized lipid profile that was altered in diabetic rats. Moreover, vanillic acid attenuated the impaired renal function as evidenced by a reduction in serum creatinine, urea, uric acid and urinary microproteinuria levels with a concomitant increase in urinary creatinine clearance in the nephropathic rats. Diabetic rats showed a marked increase in thiobarbituric acid reactive substances (TBARS) and superoxide anion generation (SAG) along with decreased reduced glutathione (GSH) in the renal tissue which was ameliorated in the vanillic acid-treated rats. Histopathologically, vanillic acid treatment was associated with reduced damage with normalized structural changes in renal tissue. Furthermore, treatment groups showed the suppression of upregulation of nuclear factor (NF)-κB, tumor necrosis factor (TNF)-α, cyclo-oxygenase (COX)-2 and up-regulation of Nuclear factor-erythroid 2-related factor 2 (Nrf-2) in the renal tissue. In conclusion, vanillic acid's ameliorative impact on diabetic nephropathic rats may be attributed to its powerful free radical scavenging property, down-regulation of NF-κB, TNF-α, COX-2 and up-regulation of Nrf-2 proteins in renal tissue.

A Retrospective Analysis of Hematologic Parameters in Patients with Early Diabetic Kidney Disease

OBJECTIVE

To retrospectively analyze the hematologic parameters in patients with early Diabetic Kidney Disease (DKD) to define potential biomarkers that can be used to predict early DKD.

METHODS

134 diabetic patients without nephropathy and 49 patients with early DKD were enrolled for this study and the hematologic parameters were retrospectively analyzed. Paired comparison was conducted by T-test and the predicting value of any statistically different parameter was tested using the Receiver Operating Characteristic curve (ROC) analysis model.

RESULTS

The number of Neutrophil (N) was higher (P <0.001) while monocyte (M) was lower (P <0.01) in the early DKD group than that of DM group without nephropathy. In addition, neutrophil to lymphocyte ratio (NLR) was higher while platelet to lymphocyte ratio (PLR) was significantly lower in the early DKD group(P <0.001). Results from ROC curve analysis showed the sensitivity and specificity of PLR to predict early DKD were 83.7% and 82.6%, respectively.

CONCLUSIONS

PLR may be a potential hematologic parameter that can be used to predict early DKD.

Renal outcomes with sodium-glucose cotransporters 2 inhibitors

Diabetic nephropathy (DN) is one of the most serious complications of diabetes. Therefore, delaying and preventing the progression of DN becomes an important goal in the clinical treatment of type 2 diabetes mellitus. Recent studies confirm that sodium-glucose cotransporters 2 inhibitors (SGLT2is) have been regarded as effective glucose-lowering drugs with renal protective effect. In this review, we summarize in detail the present knowledge of the effects of SGLT2is on renal outcomes by analyzing the experimental data in preclinical study, the effects of SGLT2is on estimated glomerular flitration rates (eGFRs) and urinary albumin-creatinine ratios (UACRs) from clinical trials and observational studies, and renal events (such as renal death or renal failure requiring renal replacement therapy) in some large prospective cardiovaslucar outcomes trials. The underlying mechanisms for renoprotective activity of SGLT2is have been demondtrated in multiple diabetic and nondiabetic animal models including kidney-specific effects and secondary kidney effects related to amelioration in blood glucose and blood pressure. In conclusion, these promising results show that SGLT2is act beneficially in terms of the kidney for diabetic patients.

Purinergic P2 receptors: Involvement and therapeutic implications in diabetes-related glomerular injury

The purinergic activation of P2 receptors initiates a powerful and rapid signaling cascade that contributes to the regulation of an array of physiological and pathophysiological processes in many organs, including the kidney. P2 receptors are broadly distributed in both epithelial and vascular renal cells. Disturbances of purinergic signaling can lead to impairments in renal function. A growing body of evidence indicates changes in P2 receptor expression and nucleotide metabolism in chronic renal injury and inflammatory diseases. Increasing attention has focused on purinergic P2X7 receptors, which are not normally expressed in healthy kidney tissue but are highly expressed at sites of tissue damage and inflammation. Under hyperglycemic conditions, several mechanisms that are linked to purinergic signaling and involve nucleotide release and degradation are disrupted, resulting in the accumulation of adenosine 5'-triphosphate in the bloodstream in diabetes. Dysfunction of the purinergic system might be associated with serious vascular complications in diabetes, including diabetic nephropathy. This review summarizes our current knowledge of the role of P2 receptors in diabetes-related glomerular injury and its implications for new therapeutics for diabetic nephropathy.

Brown adipose tissue transplantation ameliorates diabetic nephropathy through the miR-30b pathway by targeting Runx1

OBJECTIVE

Adipose tissue is a major source of circulating microRNAs (miRNAs) that can regulate target genes in distant organs. However, the role of brown adipose tissue (BAT) in diabetic kidney disease (DKD) is still unknown. We studied the original BAT miR-30b targeting two key fibrotic regulators, Runt-related transcription factor 1 (Runx1) and snail family zinc finger 1 (Snail1), to combat DKD.

METHODS

First, we transplanted healthy BAT from normal mouse donors into diabetic mice (induced by a high-fat diet and streptozotocin injection). In vitro, we observed extracellular vesicles (EVs) secreted from brown adipocytes. AgomiR-30b was directly administered to the BAT of diabetic mice twice weekly for 4 consecutive weeks. Next, the role of Runx1 in DKD was determined by using siRUNX1 or pCMV-RUNX1 in HK-2 cells and in diabetic mice treated with AAV9-U6-shRunx1 or AAV9-EF1a-Runx1.

RESULTS

BAT transplantation reactivated endogenous BAT activity in diabetic mice, increased circulating miR-30b levels and significantly ameliorated DKD. In TGFβ1-treated HK-2 cells, miR-30b expression was significantly suppressed. miR-30b overexpression markedly decreased fibronectin and downregulated Runx1 and Snail1 expression, while silencing of miR-30b had the opposite effects. Next, Runx1 knockdown and overexpression mimicked the above phenotype of miR-30b mimics and inhibitors, respectively, both in vitro and in vivo. Moreover, Runx1 promoted TGFβ1-induced fibrosis by upregulating the PI3K pathway.

CONCLUSION

BAT-derived miRNAs might be a promising target for kidney protection in diabetes mellitus.

Fucoxanthin regulates Nrf2 signaling to decrease oxidative stress and improves renal fibrosis depending on Sirt1 in HG-induced GMCs and STZ-induced diabetic rats

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial cellular defense factor to cope with oxidative stress. Silent information regulator T1 (Sirt1) is a deacetylase with antioxidative stress activity. Fucoxanthin is a marine-derived carotenoid. This study was conducted to investigate whether fucoxanthin could alleviate oxidative stress by activating Sirt1/Nrf2 signaling to alleviate DN. In streptozotocin-induced diabetic rats, fucoxanthin treatment effectively improved renal function, alleviated glomerulosclerosis. Fucoxanthin reversed the decreased protein levels of Sirt1 and Nrf2 in the kidney of diabetic rats and glomerular mesangial cells cultured in high glucose. Conversely, EX527, a Sirt1 inhibitor, counteracted the effect of fucoxanthin on the expression of Nrf2. Furthermore, in vivo and vitro results showed that fucoxanthin treatment reversed the low expression and activity of superoxide dismutase and heme oxygenase 1, depending on Sirt1 activation. Our results suggest that fucoxanthin improves diabetic kidney function and renal fibrosis by activating Sirt1/Nrf2 signaling to reduce oxidative stress.

Associations of Plasma Glucagon Levels with Estimated Glomerular Filtration Rate, Albuminuria and Diabetic Kidney Disease in Patients with Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is characterized by elevated fasting glucagon and impaired suppression of postprandial glucagon secretion, which may participate in diabetic complications. Therefore, we investigated the associations of plasma glucagon with estimated glomerular filtration rate (eGFR), albuminuria and diabetic kidney disease (DKD) in T2DM patients.

METHODS

Fasting glucagon and postchallenge glucagon (assessed by area under the glucagon curve [AUCgla]) levels were determined during oral glucose tolerance tests. Patients with an eGFR <60 mL/min/1.73 m2 and/or a urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g who presented with diabetic retinopathy were identified as having DKD.

RESULTS

Of the 2,436 recruited patients, fasting glucagon was correlated with eGFR and UACR (r=-0.112 and r=0.157, respectively; P<0.001), and AUCgla was also correlated with eGFR and UACR (r=-0.267 and r=0.234, respectively; P<0.001). Moreover, 31.7% (n=771) presented with DKD; the prevalence of DKD was 27.3%, 27.6%, 32.5%, and 39.2% in the first (Q1), second (Q2), third (Q3), and fourth quartile (Q4) of fasting glucagon, respectively; and the corresponding prevalence for AUCgla was 25.9%, 22.7%, 33.7%, and 44.4%, respectively. Furthermore, after adjusting for other clinical covariates, the adjusted odds ratios (ORs; 95% confidence intervals) for DKD in Q2, Q3, and Q4 versus Q1 of fasting glucagon were 0.946 (0.697 to 1.284), 1.209 (0.895 to 1.634), and 1.521 (1.129 to 2.049), respectively; the corresponding ORs of AUCgla were 0.825 (0.611 to 1.114), 1.323 (0.989 to 1.769), and 2.066 (1.546 to 2.760), respectively. Additionally, when we restricted our analysis in patients with glycosylated hemoglobin <7.0% (n=471), we found fasting glucagon and AUCgla were still independently associated with DKD.

CONCLUSION

Both increased fasting and postchallenge glucagon levels were independently associated with DKD in T2DM patients.

CDKN2B-AS1 participates in high glucose-induced apoptosis and fibrosis via NOTCH2 through functioning as a miR-98-5p decoy in human podocytes and renal tubular cells

BACKGROUND

Diabetic nephropathy (DN) is the most common causes of end-stage renal disease. Long non-coding RNA cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) is connected with the development of DN, but the role of CDKN2B-AS1 in DN has not been entirely elucidated.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was carried out to measure CDKN2B-AS1 and miR-98-5p levels. Cell viability, proliferation, and apoptosis were analyzed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) or flow cytometry assays. Protein levels were measured by western blotting. The relationship between CDKN2B-AS1 or notch homolog 2 (NOTCH2) and miR-98-5p was verified via dual-luciferase reporter assay.

RESULTS

CDKN2B-AS1 and NOTCH2 were upregulated in the serum of DN patients and high glucose-disposed human podocytes (HPCs) and human renal tubular cells (HK-2), whereas miR-98-5p was downregulated. High glucose repressed viability and accelerated apoptosis of HPCs and HK-2 cells. CDKN2B-AS1 knockdown impaired high glucose-induced apoptosis and fibrosis of HPCs and HK-2 cells. Mechanistically, CDKN2B-AS1 sponged miR-98-5p to regulate NOTCH2 expression. Also, CDKN2B-AS1 inhibition-mediated effects on apoptosis and fibrosis of high glucose-disposed HPCs and HK-2 cells were weakened by miR-98-5p inhibitor. Also, NOTCH2 knockdown partly reversed miR-98-5p inhibitor-mediated impacts on apoptosis and fibrosis of high glucose-disposed HPCs and HK-2 cells.

CONCLUSION

High glucose-induced CDKN2B-AS1 promoted apoptosis and fibrosis via the TGF-β1 signaling mediated by the miR-98-5p/NOTCH2 axis in HPCs and HK-2 cells.

Long noncoding RNA MIAT inhibits the progression of diabetic nephropathy and the activation of NF-κB pathway in high glucose-treated renal tubular epithelial cells by the miR-182-5p/GPRC5A axis

Background

Diabetic nephropathy (DN) is a common diabetic complication. Long noncoding RNAs (lncRNAs) have been identified as essential regulators in DN progression. This study is devoted to the research of lncRNA-myocardial infarction-associated transcript (MIAT) in DN.

Methods

DN cell model was established by high glucose (HG) treatment for human renal tubular epithelial cells (HK-2). Cell viability and colonizing capacity were analyzed by Cell Counting Kit-8 (CCK-8) and colony formation assay. Apoptosis was assessed via caspase-3 detection and flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used for evaluating inflammation. The protein determination was completed using western blot. MIAT, microRNA-182-5p (miR-182-5p), and G protein-coupled receptor class C group 5 member A (GPRC5A) levels were all examined via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Intergenic binding was verified using dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays.

Results

HG induced the inhibition of cell growth, but accelerated apoptosis and inflammation as well as the activation of nuclear factor kappa B (NF-κB) pathway. MIAT reestablishment prevented the HG-induced cell damages and NF-κB signal activation. Mechanistically, MIAT was proved as a miR-182-5p sponge and regulated the expression of GPRC5A that was a miR-182-5p target. The rescued experiments demonstrated that MIAT downregulation or miR-182-5p upregulation aggravated the HG-induced cell damages and activated the NF-κB pathway via the respective regulation of miR-182-5p or GPRC5A.

Conclusion

Taken together, MIAT functioned as an inhibitory factor in the pathogenesis to impede the development of DN and inactivate the NF-κB pathway via regulating the miR-182-5p/GPRC5A axis.

Activated Histone Acetyltransferase p300/CBP-Related Signalling Pathways Mediate Up-Regulation of NADPH Oxidase, Inflammation, and Fibrosis in Diabetic Kidney

Accumulating evidence implicates the histone acetylation-based epigenetic mechanisms in the pathoetiology of diabetes-associated micro-/macrovascular complications. Diabetic kidney disease (DKD) is a progressive chronic inflammatory microvascular disorder ultimately leading to glomerulosclerosis and kidney failure. We hypothesized that histone acetyltransferase p300/CBP may be involved in mediating diabetes-accelerated renal damage. In this study, we aimed at investigating the potential role of p300/CBP in the up-regulation of renal NADPH oxidase (Nox), reactive oxygen species (ROS) production, inflammation, and fibrosis in diabetic mice. Diabetic C57BL/6J mice were randomized to receive 10 mg/kg C646, a selective p300/CBP inhibitor, or its vehicle for 4 weeks. We found that in the kidney of C646-treated diabetic mice, the level of H3K27ac, an epigenetic mark of active gene expression, was significantly reduced. Pharmacological inhibition of p300/CBP significantly down-regulated the diabetes-induced enhanced expression of Nox subtypes, pro-inflammatory, and pro-fibrotic molecules in the kidney of mice, and the glomerular ROS overproduction. Our study provides evidence that the activation of p300/CBP enhances ROS production, potentially generated by up-regulated Nox, inflammation, and the production of extracellular matrix proteins in the diabetic kidney. The data suggest that p300/CBP-pharmacological inhibitors may be attractive tools to modulate diabetes-associated pathological processes to efficiently reduce the burden of DKD.

Levels of circulating GRP78 and CHOP in endoplasmic reticulum stress pathways in Chinese type 2 diabetic kidney disease patients

The current study aimed to investigate circulating glucose-regulated protein 78 (GRP78) as well as CCAAT/enhancer-binding protein homologous protein (CHOP) concentrations in Chinese type 2 diabetes mellitus (T2DM) patients, especially those with microalbuminuria. We recruited 67 patients with T2DM and 63 control subjects. We determined circulating GRP78 and CHOP concentrations by ELISA, collected anthropometric data, and measured biochemical parameters in a clinical laboratory. Compared with control groups, patients with T2DM showed decreased circulating levels of GRP78 (0.21 [0.16-0.24] vs 0.16 [0.16-0.19] ng/mL, P < .01) and CHOP ([0.29 ± 0.02] vs [0.27 ± 0.03]ng/mL, P < .01). Reduction in circulating GRP78 and CHOP levels was more pronounced in patients with more severe categories of albuminuria. Amounts of circulating GRP78 correlated directly with serum fasting c-peptide, cystatin-c (Cys-c), creatinine (Cr), blood urea nitrogen (BUN), and uric acid, and inversely with glomerular filtration rates. Circulating CHOP level was positively correlated with age, Cr, BUN, Cys-c, and urinary microalbumin/creatinine (UmALB/Cr). Circulating GRP78 was predicted independently by Cr, BUN, serum uric acid, estimated glomerular filtration rate, and Cys-c, while CHOP depended on age, Cr, BUN, estimated glomerular filtration rate, UmALB/Cr, and Cys-c. After controlling for confounding factors, circulating GRP78 and CHOP expression were significantly associated with diabetic kidney disease (binary logistic regression, P < .01). Patients with T2DM showed increased circulating GRP78 and CHOP concentrations. Receiver operating characteristic areas under the curve for predicting diabetic kidney disease based on GRP78 and CHOP were 0.686 (95% CI: 0.558-0.813) and 0.670 (0.524-0.816), respectively.

Insulin resistance in glomerular podocytes: Potential mechanisms of induction

Glomerular podocytes are a target for the actions of insulin. Accumulating evidence indicates that exposure to nutrient overload induces insulin resistance in these cells, manifested by abolition of the stimulatory effect of insulin on glucose uptake. Numerous recent studies have investigated potential mechanisms of the induction of insulin resistance in podocytes. High glucose concentrations stimulated reactive oxygen species production through NADPH oxidase activation, decreased adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, and reduced deacetylase sirtuin 1 (SIRT1) protein levels and activity. Calcium signaling involving transient receptor potential cation channel C, member 6 (TRPC6) also was demonstrated to play an essential role in the regulation of insulin-dependent signaling and glucose uptake in podocytes. Furthermore, podocytes exposed to diabetic environment, with elevated insulin levels become insulin resistant as a result of degradation of insulin receptor (IR), resulting in attenuation of insulin signaling responsiveness. Also elevated levels of palmitic acid appear to be an important factor and contributor to podocytes insulin resistance. This review summarizes cellular and molecular alterations that contribute to the development of insulin resistance in glomerular podocytes.

Early Renoprotective Effect of Ruxolitinib in a Rat Model of Diabetic Nephropathy

Diabetic kidney disease (DKD) is still one of the unresolved major complications of diabetes mellitus, which leads ultimately to end-stage renal disease in both type 1 and type 2 diabetes patients. Available drugs that suppress the renin-angiotensin system have partially minimized the disease impact. Yet, there is an unmet need for new therapeutic interventions to protect the kidneys of diabetic patients. In DN, glomerular sclerosis and tubulointerstitial fibrosis are mediated through several pathways, of which JAK/STAT is a key one. The current study explored the potential renoprotective effect of the JAK1/JAK2 inhibitor ruxolitinib (at doses of 0.44, 2.2, and 4.4 mg·kg^-1) compared to that of enalapril at a dose of 10 mg·kg^-1, in a rat model of streptozotocin-induced diabetes mellitus over 8 weeks. The effect of ruxolitinib was assessed by determining urinary albumin/creatinine ratio, serum level of cystatin, and levels of TGF-β1, NF-κB, and TNF-α in renal tissue homogenates by biochemical assays, the glomerular sclerosis and tubulointerstitial fibrosis scores by histological analysis, and fibronectin, TGF-β1, and Vimentin levels by immunohistochemical staining with the respective antibodies. Our results revealed a significant early favorable effect of a two-week ruxolitinib treatment on the renal function, supported by a decline in the proinflammatory biomarkers of DKD. This pre-clinical study suggests that the renoprotective effect of ruxolitinib in the long term should be investigated in animals, as this drug may prove to be a potential option for the treatment of diabetic kidney disease.