Treatment of diabetic kidney disease: current and future targets

Cross-Domain Text Mining of Pathophysiological Processes Associated with Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide. This study's goal was to identify the signaling drivers and pathways that modulate glomerular endothelial dysfunction in DKD via artificial intelligence-enabled literature-based discovery. Cross-domain text mining of 33+ million PubMed articles was performed with SemNet 2.0 to identify and rank multi-scalar and multi-factorial pathophysiological concepts related to DKD. A set of identified relevant genes and proteins that regulate different pathological events associated with DKD were analyzed and ranked using normalized mean HeteSim scores. High-ranking genes and proteins intersected three domains-DKD, the immune response, and glomerular endothelial cells. The top 10% of ranked concepts were mapped to the following biological functions: angiogenesis, apoptotic processes, cell adhesion, chemotaxis, growth factor signaling, vascular permeability, the nitric oxide response, oxidative stress, the cytokine response, macrophage signaling, NFκB factor activity, the TLR pathway, glucose metabolism, the inflammatory response, the ERK/MAPK signaling response, the JAK/STAT pathway, the T-cell-mediated response, the WNT/β-catenin pathway, the renin-angiotensin system, and NADPH oxidase activity. High-ranking genes and proteins were used to generate a protein-protein interaction network. The study results prioritized interactions or molecules involved in dysregulated signaling in DKD, which can be further assessed through biochemical network models or experiments.

Traditional Chinese medicine for the treatment of immune-related nephropathy: A review

Immune-related nephropathy (IRN) refers to immune-response-mediated glomerulonephritis and is the main cause of end-stage renal failure. The pathogenesis of IRN is not fully understood; therefore, treatment is challenging. Traditional Chinese medicines (TCMs) have potent clinical effects in the treatment of the IRN conditions immunoglobulin A nephropathy, lupus nephropathy, and diabetic nephropathy. The underlying mechanisms mainly include its inhibition of inflammation; improvements to renal interstitial fibrosis, oxidative stress, autophagy, apoptosis; and regulation of immunity. In this review, we summarize the clinical symptoms of the three IRN subtypes and the use of TCM prescriptions, herbs, and bioactive compounds in treating IRN, as well as the potential mechanisms, intending to provide a reference for the future study of TCM as IRN treatments.

Assessing the Effects of Modern Renoprotective Agents in Preventing Progression of Renal Composite Outcomes in Patients with Type 2 Diabetes: A Network Meta-analysis

BACKGROUND AND AIMS

Type 2 diabetes is one of the leading causes of the development and progression of diabetic kidney disease, culminating in end-stage renal disease. Approximately two decades after successful implementation of the renin-angiotensin-aldosterone blocking system, three classes of agents [sodium glucose cotransporter 2 inhibitors (SGLT-2i), glucagon-like peptide 1 receptor agonists, and nonsteroidal mineralocorticoid receptor antagonists] have shown significant potential to confer renoprotection. This network meta-analysis was undertaken to construct a hierarchy based on indirect pairwise comparisons and rankings among and within these three classes of molecules.

METHODS

A Cochrane library-based web search yielded 16 randomized controlled trials for analysis. Stata/BE 17.0 and RStudio 2022.07.1 Build 554 software were used to conduct a frequentist network meta-analysis. The effect size was assessed based on the odds ratio, and the MDS (multidimensional scaling) rank system was used to identify a hierarchy among reno-protective molecules.

RESULTS

Regarding the overall data, the SGLT-2i group of agents ranked higher than the other groups in preventing the progression of renal composite events in patients with T2D. Dapagliflozin ranked the highest among individual molecules.

CONCLUSIONS

The SGLT-2i group of agents, especially dapagliflozin, is best suited to complement metabolic control in preventing the progression of renal composite outcomes.

Therapeutic Effect of Kidney Tubular Cells-Derived Conditioned Medium on the Expression of MicroRNA-377, MicroRNA-29a, Aquapurin-1, Biochemical, and Histopathological Parameters Following Diabetic Nephropathy Injury in Rats

Background

Diabetic nephropathy (DN) is a critical complication of diabetes mellitus. This study evaluates whether administration of conditioned medium from kidney tubular cells (KTCs-CM) has the ability to be efficacious as an alternative to cell-based therapy for DN.

Materials and Methods

CM of rabbit kidney tubular cells (RK13; KTCs) has been collected and after centrifugation, filtered with 0.2 filters. Four groups of rats have been utilized, including control, DN, DN treated with CM, and sham group. After diabetes induction by streptozotocin (50 mg/kg body weight) in rats, 0.8 ml of the CM was injected to each rat three times per day for 3 consecutive days. Then, 24-h urine protein, blood urea nitrogen (BUN), and serum creatinine (Scr) have been measured through detection kits. The histopathological effects of CM on kidneys were evaluated by periodic acid-Schiff staining and the expression of microRNAs (miRNAs) 29a and 377 by using the real-time polymerase chain reaction. The expression of aquapurin-1 (AQP1) protein was also examined by Western blotting.

Results

Intravenous injections of KTCs-CM significantly reduced the urine volume, protein 24-h, BUN, and Scr, decreased the miRNA-377, and increased miRNA-29a and AQP1 in DN treated with CM rats.

Conclusion

KTCs-CM may have the potential to prevent kidney injury from diabetes by regulating the microRNAs related to DN and improving the expression of AQP1.

Glomerular filtration rate as a kidney outcome of diabetic kidney disease: a focus on new antidiabetic drugs

Diabetes has reached epidemic proportions, both in Korea and worldwide and is associated with an increased risk of chronic kidney disease and kidney failure (KF). The natural course of kidney function among people with diabetes (especially type 2 diabetes) may be complex in real-world situations. Strong evidence from observational data and clinical trials has demonstrated a consistent association between decreased estimated glomerular filtration rate (eGFR) and subsequent development of hard renal endpoints (such as KF or renal death). The disadvantage of hard renal endpoints is that they require a long follow-up duration. In addition, there are many patients with diabetes whose renal function declines without the appearance of albuminuria, measurement of the eGFR is emphasized. Many studies have used GFR-related parameters, such as its change, decline, or slope, as clinical endpoints for kidney disease progression. In this respect, understanding the trends in GFR changes could be crucial for developing clinical management strategies for the prevention of diabetic complications. This review focuses on the clinical implication of the eGFR-related parameters that have been used so far in diabetic kidney disease. We also discuss the use of recently developed new antidiabetic drugs for kidney protection, with a focus on the GFR as clinical endpoints.

ENSMUST00000147869 regulates proliferation and fibrosis of mesangial cells in diabetic nephropathy by interacting with Hspa9

AIMS

Our previous study showed that ENSMUST00000147869 was abnormally low expressed in the early stage of diabetic nephropathy (DN). ENSMUST00000147869 could inhibit the fibrosis and proliferation of mouse mesangial cells (MMCs), but the mechanism is still unclear. This study aims to explore the specific mechanism underline ENSMUST00000147869 regulates the proliferation and fibrosis of MMCs in DN.

METHODS

Nucleocytoplasmic fractionation was applied to define the location of ENSMUST00000147869 in MMCs. RNA-protein pulldown, RNA immunoprecipitation and mass spectrometry were used to identify upregulated Hspa9 directly interacting with ENSMUST00000147869. SiRNA and lentivirus packaging were used to clarify the role of Hspa9 downregulated by ENSMUST00000147869 in promoting proliferation and fibrosis in MMCs. CHX and MG132 were used to clarify the regulatory role of ENSMUST00000147869 to Hspa9. Immunoprecipitation confirmed the binding of Hspa9 and HMGB1.

RESULTS

HSPA9 was a direct binding protein of ENSMUST00000147869, and ENSMUST00000147869 could inhibit proliferation and fibrosis of MMCs by down-regulating HSPA9 through ubiquitination process. HMGB1 was the downstream binding protein of Hspa9, and ENSMUST00000147869 could inhibit the interaction between Hspa9 and HMGB1.

CONCLUSION

Our data showed that ENSMUST00000147869 regulates Hspa9 through the ubiquitin proteasome pathway, and inhibits the binding of Hspa9 and HMGB1. ENSMUST00000147869/Hspa9/HMGB1 axis may act as a diagnostic molecular marker and an effective therapeutic target for DN. This article is protected by copyright. All rights reserved.

Effects of Exosomes Derived from Kidney Tubular Cells on Diabetic Nephropathy in Rats

OBJECTIVE

One of the severe complications and well-known sources of end stage renal disease (ESRD) from diabetes mellitus is diabetic nephropathy (DN). Exosomes secreted from diverse cells are one of the novel encouraging therapies for chronic renal injuries. In this study, we assess whether extracted exosomes from kidney tubular cells (KTCs) could prevent early stage DN in vivo.

MATERIALS AND METHODS

In this experimental, exosomes from conditioned medium of rabbit KTCs (RK13) were purified by ultracentrifuge procedures. The exosomes were assessed in terms of morphology and size, and particular biomarkers were evaluated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Western blot, atomic force microscopy (AFM) and Zetasizer Nano analysis. The rats were divided into four groups: DN, control, DN treated with exosomes and sham. First, diabetes was induced in the rats by intraperitoneial (i.p.) administration of streptozotocin (STZ, 50 mg/kg body weight). Then, the exosomes were injected each week into their tail vein for six weeks. We measured 24-hour urine protein, blood urea nitrogen (BUN), and serum creatinine (Scr) levels with detection kits. The histopathological effects of the exosomes on kidneys were evaluated by periodic acid-Schiff (PAS) staining and expressions of miRNA-29a and miRNA-377 by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The KTC-Exos were approximately 50-150 nm and had a spherical morphology. They expressed the CD9 and CD63 specific markers. Intravenous injections of KTC-Exos potentially reduced urine volume (P<0.0001), and 24- hour protein (P<0.01), BUN (P<0.001) and Scr (P<0.0001) levels. There was a decrease in miRNA-377 (P<0.01) and increase in miRNA-29a (P<0.001) in the diabetic rats. KTC-Exos ameliorated the renal histopathology with regulatory changes in microRNAs (miRNA) expressions.

CONCLUSION

KTC-Exos plays a role in attenuation of kidney injury from diabetes by regulating the miRNAs associated with DN.

Changing the Concept: From the Traditional Glucose-centric to the New Cardiorenal-metabolic Approach for the Treatment of Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a chronic disease with a constantly increasing prevalence worldwide. It is well established that T2DM affects both the macro- and microvasculature, and its presence is associated with a high risk of acute and chronic cardiovascular events. Traditionally, the management of T2DM has been mainly focused on the optimization of blood glucose levels with the use of antidiabetic medications. During recent years, however, an impressive accumulation of evidence has arisen from studies designed to explore the plausible effects of new antidiabetic drugs on cardiovascular outcomes in patients with diabetes. This review article aims to emphasize the findings of these studies and to highlight the substantial role of the newer classes of antidiabetic drugs in treating T2DM in a holistic, cardiorenal-metabolic approach, thus shifting the paradigm from the traditional, simplistic, glucose-lowering approach.

Diabetic Nephropathy: Challenges in Pathogenesis, Diagnosis, and Treatment

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. Chronic hyperglycemia and high blood pressure are the main risk factors for the development of DN. In general, screening for microalbuminuria should be performed annually, starting 5 years after diagnosis in type 1 diabetes and at diagnosis and annually thereafter in type 2 diabetes. Standard therapy is blood glucose and blood pressure control using the renin-angiotensin system blockade, targeting A1c < 7%, and <130/80 mmHg. Regression of albuminuria remains an important therapeutic goal. However, there are problems in diagnosis and treatment of nonproteinuric DN (NP-DN), which does not follow the classic pattern of DN. In fact, the prevalence of DN continues to increase, and additional therapy is needed to prevent or ameliorate the condition. In addition to conventional therapies, vitamin D receptor activators, incretin-related drugs, and therapies that target inflammation may also be promising for the prevention of DN progression. This review focuses on the role of inflammation and oxidative stress in the pathogenesis of DN, approaches to diagnosis in classic and NP-DN, and current and emerging therapeutic interventions.

Is there a relationship between the prevalence of autoimmune thyroid disease and diabetic kidney disease?

Autoimmune thyroid disease (AITD) is more common among diabetes mellitus (DM) patients and may impact its microvascular complications. The present study aimed to assess the relationship between AITD and the prevalence of diabetic kidney disease (DKD) in patients with diabetes mellitus type 1 (DM1). Anthropometric parameters, parameters of metabolic control of DM, thyreometabolic status, and the UACR were assessed. DKD was diagnosed if patients' UACR level was ≥30 mg/g or eGFR level was <60 mL/min. This study involved 144 patients with DM1 aged 36.2 ± 11.7 years: 49 men and 95 women. Significant differences in creatinine, eGFR, and UACR levels were found in patients with DKD. fT3 concentration was significantly lower among DKD patients. A significantly higher probability of DKD was found in DM1 patients with lower fT3 levels. Patients with DM1 and AITD had significantly lower creatinine levels than the control group. However, the study did not show any significant relationship between AITD and the occurrence of DKD in patients with DM1. Significantly lower fT3 concentrations in DKD patients may be caused by metabolic disorders in the course of DKD and require further cohort studies in a larger population of patients with DM1 and AITD.

Severe hypoglycemia and the risk of end stage renal disease in type 2 diabetes

We investigated the association between the incidence of severe hypoglycemia and the risk of end-stage renal disease (ESRD) in patients with type 2 diabetes. Baseline and follow-up data for 988,333 participants with type 2 diabetes were retrieved from the National Health Insurance System database. The number of severe hypoglycemia episodes experienced from 2007 to 2009 was determined. The primary outcome was the development of ESRD after the baseline evaluation. Participants were followed from the baseline until death or December 31, 2016, during this period 14,545 participants (1.5%) developed ESRD. In the crude model, compared with those who experienced no severe hypoglycemia, the hazard ratios (95% confidential intervals) for developing ESRD were 4.96 (4.57–5.39), 6.84 (5.62–8.32), and 9.51 (7.14–12.66) in participants who experienced one, two, and three or more episodes of severe hypoglycemia, respectively. Further adjustment for various confounding factors attenuated the association between severe hypoglycemia and ESRD; the significance of the association between severe hypoglycemia and ESRD was maintained. Having three or more severe hypoglycemia episodes was associated with a nearly two-fold increased risk of developing ESRD. Prior episodes of severe hypoglycemia were associated with an increased risk of ESRD among Korean adults with type 2 diabetes.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

Autophagy in diabetic nephropathy: a review

Diabetes mellitus (DM) is the leading cause of end stage renal disease. 40% of the patients worldwide will require replacement therapy after 20 years of DM worldwide. Early-stage diabetic nephropathy is characterized by hyperfiltration related to hypeglycemia-induced afferent artery vasodilatation with micro-and macroalbuminuria. Later on, proteinuria with arterial hypertension may appear, culminating in glomerular filtration rate (GFR) decline and end stage renal disease. Forty percent of diabetic patients develop microvascular and macrovascular complications, with increased risk among patients with genetic predisposition, such as Haptoglobin 2-2 phenotype. The most frequent complications in the daily clinical practice are diabetic kidney disease, diabetic retinopathy and vascular disease, such as coronary artery disease and stroke. Various pathways are involved in the pathogenesis of diabetic kidney disease. Chronic systemic inflammation and the inflammatory response, such as increased circulating cytokines (Interleukins), have been recognized as main players in the development and progression of diabetic kidney disease. DM is also associated with increased oxidative stress, and alterations in carbohydrate, lipid and protein metabolism. Overexpression of the renin-angiotensin-aldosterone system (RAAS) in the kidney, the vitamin D-Vitamin D receptor-klotho axis, and autophagy. Differences in the ATG5 protein levels or ATG5 gene expression involved in the autophagy process have been associated with diabetic complications such as diabetic kidney disease. Under normal blood glucose level, autophagy is an important protective mechanism in renal epithelial cells, including podocytes, proximal tubular, mesangial and endothelial cells. Down regulation of the autophagic mechanism, as in hyperglycemic condition, can contribute to the development and progression of diabetic kidney disease.

RIPK3 blockade attenuates tubulointerstitial fibrosis in a mouse model of diabetic nephropathy

Receptor-interacting protein kinase-3 (RIPK3) is a multifunctional regulator of cell death and inflammation. RIPK3 controls cellular signalling through the formation of the domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which is recognised to mediate renal fibrogenesis. The role of RIPK3 in diabetic kidney disease (DKD) induced renal fibrosis has not been previously determined. To define the action of RIPK3 in the development of diabetic kidney disease, wild-type (WT), RIPK3 -/- and endothelium-derived nitric oxide synthase (eNOS)-/- mice were induced to develop diabetes mellitus using multiple low doses of streptozotocin and maintained for 24 weeks. RIPK3 activity and NLRP3 expression were upregulated and fibrotic responses were increased in the kidney cortex of WT mice with established diabetic nephropathy compared to control mice. Consistently, mRNA expression of inflammasome components, as well as transforming growth factor beta 1 (TGFβ1), α smooth muscle actin (α-SMA) and collagen deposition were increased in diabetic kidneys of WT mice compared to control mice. However, these markers were normalised or significantly reversed in kidneys of diabetic RIPK3 -/- mice. Renoprotection was also observed using the RIPK3 inhibitor dabrafenib in eNOS-/- diabetic mice as demonstrated by reduced collagen deposition and myofibroblast activation. These results suggest that RIPK3 is associated with the development of renal fibrosis in DKD due to the activation of the NLRP3 inflammasome. Inhibition of RIPK3 results in renoprotection. Thus, RIPK3 may be a potential target for therapeutic intervention in patients with diabetic kidney disease.

DACH1, a novel target of miR-218, participates in the regulation of cell viability, apoptosis, inflammatory response, and epithelial-mesenchymal transition process in renal tubule cells treated by high-glucose

Objective: This report was designed to assess the functional role of miR-218/dachshund family transcription factor 1 (DACH1) in diabetic kidney disease (DKD) and investigate its possible molecular mechanism.Materials and Methods: From the GEO database, we downloaded different datasets for analyzing the expression of miR-218 and DACH1 in DKD. TargetScan was adopted to predict the binding sites between miR-218 and DACH1, which was further verified by dual-luciferase reporter assays. The renal proximal tubule cells (HK-2) treated with high glucose (HG) were used as an in vitro model. QRT-PCR and western blot were used to determine the expression of DACH1 and other relative factors. Cell counting kit-8 and flow cytometer were applied to detect cell viability and apoptosis. The levels of inflammatory cytokines were determined by an ELISA assay.Results: A prominent raise of miR-218 was observed in DKD through bioinformatics analysis, which was further confirmed in the HG-induced model. DACH1 is a target of miR-218. miR-218 reduced cell viability and induced apoptosis by negatively regulating DACH1. Moreover, upregulating miR-218 in HG models increased the concentrations of pro-inflammatory cytokines TNF-α and IL-1β, reduced the level of anti-inflammatory cytokine IL-10, and promoted the epithelial-mesenchymal transition (EMT) process, which is possibly achieved by targeting DACH1. While downregulating miR-218 showed the opposite results.Conclusion: These data demonstrated that, under an in vitro HG environment, miR-218 suppressed the HK-2 cells proliferation, promoted apoptosis, caused an inflammatory response, and facilitated the EMT process largely by targeting DACH1, providing an insight into the therapeutic intervention of DKD.

Jowiseungki decoction affects diabetic nephropathy in mice through renal injury inhibition as evidenced by network pharmacology and gut microbiota analyses

Background

Jowiseungki decoction (JSD) is a prescription commonly used for the treatment of diabetic complications or diabetic nephropathy (DN) in traditional medicine clinics. However, the underlying therapeutic mechanisms of JSD are still unclear.

Methods

Streptozotocin (STZ)-induced DN mice were administered 100 and 500 mg/kg JSD for 4 weeks, and the therapeutic mechanisms and targets of JSD were analyzed by network pharmacology and gut microbiota analyses.

Results

JSD significantly decreased the increase in food and water intake, urine volume, fasting blood glucose, serum glucose and triglyceride levels, and urinary albumin excretion. JSD administration significantly increased the decrease in insulin secretion and creatinine clearance and reduced the structural damage to the kidney tissues. Moreover, JSD administration significantly inhibited the expression of protein kinase C-alpha (PKC-α), transforming growth factor beta-1 (TGF-β1), α-smooth muscle actin (α-SMA), nuclear factor-κB (NF-κB), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in the kidney tissues of DN mice, while it significantly increased the phosphorylation of insulin receptor substrate 1 (IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (Akt). In the network pharmacological analysis, JSD obviously influenced phosphatase binding, protein serine/threonine kinase, and mitogen-activated protein kinase (MAPK)-related signaling pathways. Our data suggest that JSD can improve symptoms in STZ-induced DN mice through the inhibition of kidney dysfunction, in particular, by regulating the PKCα/PI3K/Akt and NF-κB/α-SMA signaling pathways. Gut microbiota analysis can help to discover the pharmaco-mechanisms of the influence of JSD on bacterial diversity and flora structures in DN.

Conclusion

JSD can improve the symptoms of DN, and the underlying mechanism of this effect is renal protection through the inhibition of fibrosis and inflammation. JSD can also change bacterial diversity and community structures in DN.

Keap1/Nrf2/ARE signaling unfolds therapeutic targets for redox imbalanced-mediated diseases and diabetic nephropathy

Hyperglycemia/oxidative stress has been implicated in the initiation and progression of diabetic complications while the components of Keap1/Nrf2/ARE signaling are being exploited as therapeutic targets for the treatment/management of these pathologies. Antioxidant agents like drugs, nutraceuticals and pure compounds that target the proteins of this pathway and their downstream genes hold the therapeutic strength to put the progression of this disease at bay. Here, we elucidate how the modulation of Keap1/Nrf2/ARE had been exploited for the treatment/management of end-stage diabetic kidney complication (diabetic nephropathy) by looking into (1) Nrf2 nuclear translocation and phosphorylation by some protein kinases at specific amino acid sequences and (2) Keap1 downregulation/Keap1-Nrf2 protein-protein inhibition (PPI) as potential therapeutic mechanisms exploited by Nrf2 activators for the modulation of diabetic nephropathy biomarkers (Collagen IV, Laminin, TGF-β1 and Fibronectin) that ultimately lead to the amelioration of this disease progression. Furthermore, we brought to limelight the relationship between diabetic nephropathy and Keap1/Nrf2/ARE and finally elucidate how the modulation of this signaling pathway could be further explored to create novel therapeutic milestones.

A Novel Indoline Derivative Ameliorates Diabesity-Induced Chronic Kidney Disease by Reducing Metabolic Abnormalities

Both diabetes and obesity (diabesity) contribute significantly to the development of chronic kidney disease (CKD). In search of new remedies to reverse or arrest the progression of CKD, we examined the therapeutic potential of a novel compound, AN1284, in a mouse model of CKD induced by type 2 diabetes with obesity. Six-week-old BKS Cg-Dock 7^m+/+ Lepr^db/J mice with type 2 diabetes and obesity were treated with AN1284 (2.5 or 5 mg kg^-1 per day) via micro-osmotic pumps implanted subcutaneously for 3 months. Measures included renal, pancreatic, and liver assessment as well as energy utilization. AN1284 improved kidney function in BSK-db/db animals by reducing albumin and creatinine and preventing renal inflammation and morphological changes. The treatment was associated with weight loss, decreased body fat mass, increased utilization of body fat toward energy, preservation of insulin sensitivity and pancreatic β cell mass, and reduction of dyslipidemia, hepatic steatosis, and liver injury. This indoline derivative protected the kidney from the deleterious effects of hyperglycemia by ameliorating the metabolic abnormalities of diabetes. It could have therapeutic potential for preventing CKD in human subjects with diabesity.

Lipid mediators of insulin signaling in diabetic kidney disease

Diabetic kidney disease (DKD) affects ∼40% of patients with diabetes and is associated with high mortality rates. Among different cellular targets in DKD, podocytes, highly specialized epithelial cells of the glomerular filtration barrier, are injured in the early stages of DKD. Both clinical and experimental data support the role of preserved insulin signaling as a major contributor to podocyte function and survival. However, little is known about the key modulators of podocyte insulin signaling. This review summarizes the novel knowledge that intracellular lipids such as cholesterol and sphingolipids are major determinants of podocyte insulin signaling. In particular, the implications of these lipids on DKD development, progression, and treatment will be addressed.

Changes in co-morbidity pattern in patients starting renal replacement therapy in Europe-data from the ERA-EDTA Registry

Background

Patients starting renal replacement therapy (RRT) for end-stage renal disease often present with one or more co-morbidities. This study explored the prevalence of co-morbidities in patients who started RRT in Europe during the period from 2005 to 2014.

Methods

Using data from patients aged 20 years or older from all 11 national or regional registries providing co-morbidity data to the European Renal Association - European Dialysis and Transplant Association Registry, we examined the prevalence of the following co-morbidities: diabetes mellitus (DM) (primary renal disease and/or co-morbidity), ischaemic heart disease (IHD), congestive heart failure (CHF), peripheral vascular disease (PVD), cerebrovascular disease (CVD) and malignancy.

Results

Overall, 70% of 7578 patients who initiated RRT in 2014 presented with at least one co-morbidity: 39.0% presented with DM, 25.0% with IHD, 22.3% with CHF, 17.7% with PVD, 16.4% with malignancy and 15.5% with CVD. These percentages differed substantially between countries. Co-morbidities were more common in men than in women, in older patients than in younger patients, and in patients on haemodialysis at Day 91 when compared with patients on peritoneal dialysis. Between 2005 and 2014 the prevalence of DM and malignancy increased over time, whereas the prevalence of IHD and PVD declined.

Conclusions

More than two-thirds of patients initiating RRT in Europe have at least one co-morbidity. With the rising age at the start of RRT over the last decade, there have been changes in the co-morbidity pattern: the prevalence of cardiovascular co-morbidities decreased, while the prevalence of DM and malignancy increased.

Comparing the Effect of Dipeptidyl-Peptidase 4 Inhibitors and Sulfonylureas on Albuminuria in Patients with Newly Diagnosed Type 2 Diabetes Mellitus: A Prospective Open-Label Study

Diabetic kidney disease (DKD) leads to substantial morbidity in patients with type 2 diabetes mellitus (T2DM). Evidence suggests that antidiabetic drug dipeptidyl-peptidase 4 (DPP-4) inhibitors may be able to attenuate albuminuria, whereas the influence of sulfonylureas on albuminuria remains unclear. This prospective open-label study investigated the effect of DPP-4 inhibitors and sulfonylureas on urinary albumin excretion, which is a marker of renal microvascular abnormality. A total of 101 participants with newly diagnosed T2DM were enrolled. In addition to metformin therapy, 45 patients were assigned to receive DPP-4 inhibitors and 56 to receive sulfonylureas. Urinary albumin-to-creatinine ratio (ACR) was significantly reduced in recipients of DPP-4 inhibitors after 24 weeks (29.2 µg/mg creatinine vs. 14.9 µg/mg creatinine, P < 0.001), whereas urinary ACR was not significantly changed by sulfonylureas (39.9 µg/mg creatinine vs. 43.2 µg/mg creatinine, P = 0.641). The effect on albuminuria occurred even though both treatment groups had a similar change in serum glycated hemoglobin A_1c (-1.87 % vs.-2.40 %, P = 0.250). Therefore, in diabetic patients the addition of DPP-4 inhibitors lowered urinary albumin excretion compared to sulfonylureas, and attenuation of albuminuria may be a consideration when choosing between antidiabetic medications.

Adiponectin for the treatment of diabetic nephropathy

The metabolic burden caused by hyperglycemia can result in direct and immediate metabolic injuries, such as oxidative stress and tissue inflammation, in the kidney. Furthermore, chronic hyperglycemia can lead to substantial structural changes such as formation of advanced glycation end-products, glomerular and tubular hypertrophy, and tissue fibrosis. Glomerular hypertrophy renders podocytes vulnerable to increased glomerular filtration, leading to podocyte instability and loss. Thus, prevention of glomerular hypertrophy and attenuation of glomerular hyperfiltration may have therapeutic potential for diabetic nephropathy (DN). Adiponectin is an adipokine that improves insulin sensitivity in obesity-related metabolic disorders, including diabetes, but its efficacy is unknown. Moreover, the recently developed adiponectin receptor agonist, AdipoRon, shows therapeutic potential for DN. In this review, we focus on the role of glomerular hypertrophy in the pathogenesis of DN and discuss the role of adiponectin in its prevention.

Diabetic nephropathy: An update on pathogenesis and drug development

Diabetic nephropathy (DN) is a major cause of end-stage renal disease and affects a large number of individuals with diabetes. However, the development of specific treatments for DN has not yet been identified. Hence, this review is concisely designed to understand the molecular pathways leading to DN in order to develop suitable therapeutic strategies. Extensive literature search have been carried in regard with the pathogenesis and pathophysiology of DN, drug targets and updates on clinical trials, the consequences associated with DN and the potential biomarkers for diagnosis and prediction of DN are discussed in this review. DN is characterised by microalbuminuria and macroalbuminuria, and morphological changes such as glomerular thickening, interstitial fibrosis, formation of nodular glomerulosclerosis and decreased endothelial cell fenestration. Besides, the involvement of renin-angiotensin-aldosterone system, inflammation and genetic factors are the key pathways in the progression of DN. In regard with drug development drugs targeted to epidermal growth factor, inflammatory cytokines, ACTH receptor and TGFβ1 receptors are in pipeline for clinical trials whereas, several drugs have also failed in phase III and phase IV of clinical trials due to lack of efficacy and severe adverse effect. The research on DN is limited with respect to its pathogenesis and drug development. Thus, a more detailed understanding of the pathogenesis of DN is very essential to progress in the drug development process.

Triptolide Attenuates Renal Tubular Epithelial-mesenchymal Transition Via the MiR-188-5p-mediated PI3K/AKT Pathway in Diabetic Kidney Disease

Triptolide possesses the trait of renal protection. Epithelial-mesenchymal transition (EMT) is closely linked to the pathogenesis of diabetic kidney disease (DKD). MicroRNAs have recently emerged as critical regulators of DKD. However, it is poorly understood whether triptolide alleviates renal EMT by regulating microRNAs in DKD. In this study, we found that triptolide decreased albuminuria, improved the renal structure and reduced renal EMT in rats with DKD. Furthermore, activation of the PI3K/AKT signaling pathway was increased in diabetic rats, which was partly reversed by triptolide. Triptolide also alleviated glucose-induced EMT in HK-2 cells in vitro. PI3K/AKT signaling pathway activation was reduced after triptolide treatment. Moreover, triptolide decreased the increase in miR-188-5p expression stimulated by high glucose levels in HK-2 cells. miR-188-5p inhibited PTEN expression by directly interacting with the PTEN 3'-untranslated region. Additionally, downregulation of miR-188-5p, which imitates the effects of triptolide, attenuated the activation of the PI3K/AKT pathway and HG-induced EMT, whereas miR-188-5p overexpression reversed the effects of triptolide on the PI3K/AKT pathway and EMT. In conclusion, we demonstrated that triptolide ameliorates renal EMT via the PI3K/AKT signaling pathway through the interaction between miR-188-5p and PTEN, indicating that miR-188-5p may be a therapeutic target of triptolide in DKD.

AGE-RAGE axis blockade in diabetic nephropathy: Current status and future directions

Diabetic nephropathy is one of the most frequent micro-vascular complications both in type 1 and type 2 diabetic patients and is the leading cause of end-stage renal disease worldwide. Although disparate mechanisms give rise to the development of diabetic nephropathy, prevailing evidence accentuates that hyperglycemia-associated generation of advanced glycation end products (AGEs) plays a central role in the disease pathophysiology. Engagement of the receptor for AGE (RAGE) with its ligands provokes oxidative stress and chronic inflammation in renal tissues, ending up with losses in kidney function. Moreover, RAGE activation evokes the activation of different intracellular signaling pathways like PI3K/Akt, MAPK/ERK, and NF-κB; and therefore, its blockade seems to be an attractive therapeutic target in these group of patients. By recognizing the contribution of AGE-RAGE axis to the pathogenesis of diabetic nephropathy, agents that block AGEs formation have been at the heart of investigations for several years, yielding encouraging improvements in experimental models of diabetic nephropathy. Even so, recent studies have evaluated the effects of specific RAGE inhibition with FPS-ZM1 and RAGE-aptamers as novel therapeutic strategies. Despite all these promising outcomes in experimental models of diabetic nephropathy, no thorough clinical trial have ever examined the end results of AGE-RAGE axis blockade in patients of diabetic nephropathy. As most of the AGE lowering or RAGE inhibiting compounds have emerged to be non-toxic, devising novel clinical trials appears to be inevitable. Here, the current potential treatment options for diabetic nephropathy by AGE-RAGE inhibitory modalities have been reviewed.