Therapeutic modalities in diabetic nephropathy: standard and emerging approaches

Diabetic Nephropathy: Pathogenesis, Mechanisms, and Therapeutic Strategies

Diabetic nephropathy represents a predominant etiology of end-stage renal disease (ESRD) on a global scale, significantly impacting the morbidity and mortality rates of individuals with diabetes. The primary objective of this analysis is to furnish a comprehensive examination of the etiology, fundamental mechanisms, and treatment modalities for DN. The development of DN stems from a multitude of factors, encompassing a intricate interplay involving metabolic irregularities induced by hyperglycemia, alterations in hemodynamics, inflammatory responses, oxidative stress, and genetic susceptibility. Principal mechanisms encompass the generation of advanced glycation end products (AGEs), activation of protein kinase C (PKC), and overexpression of the renin-angiotensin-aldosterone system (RAAS). These processes precipitate glomerular hyperfiltration, hypertrophy, and eventually, fibrosis and scarring of the renal parenchyma. Initially, hyperglycemia triggers mesangial proliferation and thickening of the glomerular basement membrane in the incipient stages of DN, subsequently leading to progressive glomerular sclerosis and tubulointerstitial fibrosis. Inflammatory cascades, notably involving cytokines like TGF-β and NF-κB, play pivotal roles in the advancement of DN by fostering the accumulation of extracellular matrix and renal fibrosis. Inflammation pathways, particularly those involving cytokines like TGF-β and NF-κB, play essential roles in diabetic nephropathy progression by stimulating extracellular matrix accumulation and renal fibrosis. The presence of oxidative stress, worsened by dysfunctional mitochondria, contributes further to renal injury via lipid peroxidation and DNA damage. Current therapeutic approaches for diabetic nephropathy concentrate on optimizing glycemic control, controlling hypertension, and suppressing the renin-angiotensin-aldosterone system. Among antihypertensive medications, ACE inhibitors and angiotensin II receptor blockers are crucial for decelerating disease advancement.

Cinnamaldehyde ameliorates diabetes-induced biochemical impairments and AGEs macromolecules in a pre-clinical model of diabetic nephropathy

PURPOSE

Cinnamaldehyde, has various therapeutic potentials including glucose-lowering effect, and insulinotropic effect; however, its glycation inhibitory mechanism is not known yet. In this study, we explored the effects of cinnamaldehyde for its AGEs inhibitory mechanism in a streptozotocin-complete Freund's adjuvant (STZ-CFA) induced diabetic nephropathy (DN) rat model.

METHODS

Pre-clinical DN model was developed by the administration of multiple low doses of STZ-CFA in rats, mainly characterized by abnormal blood parameters and nephrotic damages. Diabetes-related systemic profile and histopathological hallmarks were evaluated using biochemical assays, microscopic imaging, immunoblot, and real-time PCR analyses, supported by cinnamaldehyde-albumin interaction assessed using STD-NMR and in silico site-directed interactions in the presence of glucose.

RESULTS

Cinnamaldehyde-treatment significantly reversed DN hallmarks, fasting blood glucose (FBG), serum insulin, glycated hemoglobin (HbA1c), urinary microalbumin, and creatinine contrasted to non-treated DN rats and aminoguanidine, a positive reference advanced glycation end products (AGEs) inhibitor. The pathological depositions of AGEs, receptor for advanced glycation end products (RAGE), and carboxymethyl lysine (CML), and transcriptional levels of AGE-RAGE targeted immunomodulatory factors (IL1β, TNF-α, NF-κB, TGF-β) were significantly improved in cinnamaldehyde treated rats as compared to aminoguanidine. Cinnamaldehyde post-treatment improved pancreatic pathology and systemic glycemic index (0.539 ± 0.01 vs. 0.040 ± 0.001, P < 0.001) in DN rats. Subsequently, in silico profiling of cinnamaldehyde defined the competitive binding inhibition with glucose in AGE and RAGE receptors that was further confirmed by in vitro STD-NMR analysis.

CONCLUSION

These findings suggest potential role of cinnamaldehyde in reversing STZ-induced diabetic nephropathic impairments; therefore, appears promising candidate for further pharmacological explorations towards diabetes-associated complications.

The Role of Selenium Nanoparticles in Addressing Diabetic Complications: A Comprehensive Study

Diabetes, as an emerging epidemic, has put forward a significant spotlight on the evolving population worldwide grounded upon the remarkable affliction of healthcare along with economical conflict. Various studies suggested that, in modern society, lack of maintenance of a healthy life style leads to the occurrence of diabetes as insulin resistant, later having a damaging effect on the pancreatic β-cells, suggesting various complications. Furthermore, diabetes management is controversial owing to different opinions based on the prevention of complications. For this purpose, nanostructured materials (NSM) like selenium nanoparticles (SeNPs) have proved their efficiency in the therapeutic management of such serious diseases. This review offers an in- -depth idea regarding the pathophysiology, diagnosis and various conventional therapeutics of type 1 and type 2 diabetes, shedding light on Diabetic Nephropathy (DN), a case study of type 1 diabetes. Moreover, this review provides an exhaustive study by highlighting the economic and healthcare burdens associated with diabetes along with the controversies associated with conventional therapeutic management and the promising role of NSM like selenium nanoparticles (SeNPs), as a novel weapon for encountering such fatal diseases.

Oxidative Stress Induced by Lipotoxicity and Renal Hypoxia in Diabetic Kidney Disease and Possible Therapeutic Interventions: Targeting the Lipid Metabolism and Hypoxia

Oxidative stress, a hallmark pathophysiological feature in diabetic kidney disease (DKD), arises from the intricate interplay between pro-oxidants and anti-oxidants. While hyperglycemia has been well established as a key contributor, lipotoxicity emerges as a significant instigator of oxidative stress. Lipotoxicity encompasses the accumulation of lipid intermediates, culminating in cellular dysfunction and cell death. However, the mechanisms underlying lipotoxic kidney injury in DKD still require further investigation. The key role of cell metabolism in the maintenance of cell viability and integrity in the kidney is of paramount importance to maintain proper renal function. Recently, dysfunction in energy metabolism, resulting from an imbalance in oxygen levels in the diabetic condition, may be the primary pathophysiologic pathway driving DKD. Therefore, we aim to shed light on the pivotal role of oxidative stress related to lipotoxicity and renal hypoxia in the initiation and progression of DKD. Multifaceted mechanisms underlying lipotoxicity, including oxidative stress with mitochondrial dysfunction, endoplasmic reticulum stress activated by the unfolded protein response pathway, pro-inflammation, and impaired autophagy, are delineated here. Also, we explore potential therapeutic interventions for DKD, targeting lipotoxicity- and hypoxia-induced oxidative stress. These interventions focus on ameliorating the molecular pathways of lipid accumulation within the kidney and enhancing renal metabolism in the face of lipid overload or ameliorating subsequent oxidative stress. This review highlights the significance of lipotoxicity, renal hypoxia-induced oxidative stress, and its potential for therapeutic intervention in DKD.

Combined detection of urinary biomarkers noninvasively predicts extent of renal injury in patients with early diabetic kidney disease with kidney qi deficiency syndrome: A retrospective investigation

Incipient diagnosis and noninvasive forecasts using urinary biomarkers are important for preventing diabetic kidney disease (DKD) progression, but they are also controversial. Previous studies have shown a potential relationship between urinary tubular biomarkers (UTBs) and traditional Chinese medicine (TCM) syndrome in patients with DKD. Thus, we further evaluated the clinical significance of combined detection of urinary biomarkers in noninvasively predicting the extent of renal damage in patients with early DKD with kidney qi deficiency syndrome, and preliminarily explored the potential biological link between UTBs and TCM syndrome in DKD. We categorized 92 patients with Type 2 diabetes mellitus into three groups as follows: 20 patients with normoalbuminuria, 50 patients with microalbuminuria, and 22 patients with macroalbuminuria. We found that, in all groups, 24 hr urinary albumin (24hUAlb) and urinary albumin-to-creatinine ratio (UACR) showed stepwise and significant increases. Urinary cystatin C (UCysC), urinary N-acetyl-β-d-glucosaminidase (UNAG), and urinary retinol-binding protein (URBP) synchronously increased gradually, consistent with the degree of albuminuria in all groups. Moreover, 24hUAlb and UACR were positively correlated with UCysC, UNAG, and URBP, respectively. In 72 patients with Type 2 DKD with albuminuria, a positive correlation was observed between UNAG and URBP, UCysC was also positively correlated with UNAG and URBP, respectively. Additionally, TCM syndrome distributional characteristics in all patients were consistent with clinical manifestations of kidney qi deficiency syndrome. Therefore, the combined detection of UCysC, UNAG, URBP, and UAlb may be used as a practical clinical technique to noninvasively forecast the extent of renal injury in patients with early Type 2 DKD with kidney qi deficiency syndrome. UTBs may be one of the biological bases of the specific TCM syndromes in DKD.

The Role of Autophagy in Type 2 Diabetic Kidney Disease Management

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

Vitamin D and Diabetic Kidney Disease

Vitamin D is a hormone involved in many physiological processes. Its active form, 1,25(OH)₂D₃, modulates serum calcium-phosphate homeostasis and skeletal homeostasis. A growing body of evidence has demonstrated the renoprotective effects of vitamin D. Vitamin D modulates endothelial function, is associated with podocyte preservation, regulates the renin-angiotensin-aldosterone system, and has anti-inflammatory effects. Diabetic kidney disease (DKD) is a leading cause of end-stage kidney disease worldwide. There are numerous studies supporting vitamin D as a renoprotector, potentially delaying the onset of DKD. This review summarizes the findings of current research on vitamin D and its role in DKD.

Autophagy and its therapeutic potential in diabetic nephropathy

Diabetic nephropathy (DN), the leading cause of end-stage renal disease, is the most significant microvascular complication of diabetes and poses a severe public health concern due to a lack of effective clinical treatments. Autophagy is a lysosomal process that degrades damaged proteins and organelles to preserve cellular homeostasis. Emerging studies have shown that disorder in autophagy results in the accumulation of damaged proteins and organelles in diabetic renal cells and promotes the development of DN. Autophagy is regulated by nutrient-sensing pathways including AMPK, mTOR, and Sirt1, and several intracellular stress signaling pathways such as oxidative stress and endoplasmic reticulum stress. An abnormal nutritional status and excess cellular stresses caused by diabetes-related metabolic disorders disturb the autophagic flux, leading to cellular dysfunction and DN. Here, we summarized the role of autophagy in DN focusing on signaling pathways to modulate autophagy and therapeutic interferences of autophagy in DN.

XIST silencing alleviated inflammation and mesangial cells proliferation in diabetic nephropathy by sponging miR-485

In this study, we investigated the role of XIST in the development of diabetic nephropathy (DN) and further explored its underlying mechanism. qRT-PCR was used to examine the level of XIST in serum of DN patients. ELISA, MTT, and flow cytometry were used to investigate the effect of XIST on biological functions of human mesangial cells (HMCs) treated with high glucose. The recovery experiments were used to explore the potential mechanism. The result showed XIST expression was elevated significantly in serums of DN patients. XIST silencing alleviated the induction of high glucose in biological behaviour of HMCs. Besides, miR-485 inhibitor revised the suppression by si-XIST in biological behaviour of high glucose induced HMCs. Furthermore, PSMB8 mimic relieved the inhibition of si-XIST in biological behaviour of high glucose induced HMCs. In short, XIST silencing could alleviate biological process and inflammation of HMCs treated with high glucose by sponging miR-485.

REDD1 Ablation Attenuates the Development of Renal Complications in Diabetic Mice

Chronic hyperglycemia contributes to development of diabetic kidney disease by promoting glomerular injury. In this study, we evaluated the hypothesis that hyperglycemic conditions promote expression of the stress response protein regulated in development and DNA damage response 1 (REDD1) in the kidney in a manner that contributes to the development of oxidative stress and renal injury. After 16 weeks of streptozotocin-induced diabetes, albuminuria and renal hypertrophy were observed in wild-type (WT) mice coincident with increased renal REDD1 expression. In contrast, diabetic REDD1 knockout (KO) mice did not exhibit impaired renal physiology. Histopathologic examination revealed that glomerular damage including mesangial expansion, matrix deposition, and podocytopenia in the kidneys of diabetic WT mice was reduced or absent in diabetic REDD1 KO mice. In cultured human podocytes, exposure to hyperglycemic conditions enhanced REDD1 expression, increased reactive oxygen species (ROS) levels, and promoted cell death. In both the kidney of diabetic mice and in podocyte cultures exposed to hyperglycemic conditions, REDD1 deletion reduced ROS and prevented podocyte loss. Benefits of REDD1 deletion were recapitulated by pharmacological GSK3β suppression, supporting a role for REDD1-dependent GSK3β activation in diabetes-induced oxidative stress and renal defects. The results support a role for REDD1 in diabetes-induced renal complications.

Ombuin ameliorates diabetic nephropathy in rats by anti-inflammation and antifibrosis involving Notch 1 and PPAR γ signaling pathways

Diabetic nephropathy (DN) is a common complication of diabetes and it is urgent to develop effective therapies for DN. In this study, high-sucrose and high-fat diet combined with streptozotocin was used to induce DN in rats to observe the effects of natural flavonoid ombuin on renal function, inflammation, and interstitial fibrosis. Immunohistochemistry and western blotting analysis were used to detect protein expression levels. Results showed that ombuin significantly improved renal function and pathological injury, inhibited accumulation of advanced glycation end-products, suppressed the release of inflammatory cytokines, and improved renal interstitial fibrosis in DN rats. Ombuin also significantly downregulated the expressions of transforming growth factor beta1 (TGF-β1), connective tissue growth factor (CTGF), fibronectin (FN), p65, phosphorylated (p)-p65, Cleaved-Notch 1, and hairy and enhancer of split 1 (Hes 1), and upregulated the expression of peroxisome proliferator-activated receptor γ (PPAR γ). When PPAR γ activity was inhibited by T0070907, the effects of ombuin on improving DN were significantly reversed, and the expressions of TGF-β1, FN, CTGF, p-p65, and p65 increased, while the expressions of Cleaved-Notch 1 and Hes 1 were not significantly affected. These results suggest that ombuin may activate PPAR γ to exert anti-inflammatory and antifibrotic effects by inhibiting Notch 1 activity in DN. It is also possible that ombuin acts on these two independent signal pathways synchronously.

Effects of L-Carnitine Treatment on Kidney Mitochondria and Macrophages in Mice with Diabetic Nephropathy

INTRODUCTION

In diabetic nephropathy (DN), mitochondrial dysfunction and leakage of mitochondrial DNA (mtDNA) are caused by the downregulation of superoxide dismutase 2 (SOD2). mtDNA induces the activation of Toll-like receptor (TLR) 9, which is present in macrophages (Mφs), and triggers their activation.

METHODS

We orally administered L-carnitine, which exerts protective effects on the mitochondria, to obesity-induced DN (db/db) mice for 8 weeks. We then investigated the effects of L-carnitine on kidney mitochondrial reactive oxygen species (mtROS) production, circulating mtDNA content, and kidney CD11bhigh/CD11blow Mφ functions.

RESULTS

In db/db mice, mtROS production increased in proximal tubular cells and kidney CD11blow Mφs; both Mφ types showed enhanced TLR9 expression. L-Carnitine treatment suppressed mtROS production in both proximal tubular cells and CD11blow Mφs (p < 0.01), with improved SOD2 expression in the kidney (p < 0.01), decreased circulating mtDNA content, and reduced albuminuria. Moreover, it suppressed Mφ infiltration into kidneys and reduced TLR9 expression in Mφs (p < 0.01), thereby lowering tumor necrosis factor-α production in CD11bhigh Mφs (p < 0.05) and ROS production by CD11blow Mφs (p < 0.01). Collectively, these changes alleviated DN symptoms.

CONCLUSION

The positive effects of L-carnitine on DN suggest its potential as a novel therapeutic agent against obesity-linked DN.

An Indole-2-Carboxamide Derivative, LG4, Alleviates Diabetic Kidney Disease Through Inhibiting MAPK-Mediated Inflammatory Responses

Aim

Elevated inflammatory signaling has been shown to play an important role in diabetic kidney disease (DKD). We previously developed a new anti-inflammatory compound LG4. In the present study, we have tested the hypothesis that LG4 could prevent DKD by suppressing inflammation and identified the underlying mechanism.

Methods

Streptozotocin-induced type 1 diabetic mice were used to develop DKD and evaluate the effects of LG4 against DKD. To identify the potential targets of LG4, biotin-linked LG4 was synthesized and subjected to proteome microarray screening. The cellular mechanism of LG4 was investigated in HG-challenged SV40MES13 cells.

Results

Although LG4 treatment had no effect on the body weight and blood glucose levels, it remarkably reversed the hyperglycemia-induced pathological changes and fibrosis in the kidneys of T1DM mice. Importantly, hyperglycemia-induced renal inflammation evidenced by NF-κB activation and TNFα and IL-6 overexpression was greatly ameliorated with LG4 treatment. Proteosome microarray screening revealed that JNK and ERK were the direct binding proteins of LG4. LG4 significantly reduced HG-induced JNK and ERK phosphorylation and subsequent NF-κB activation in vivo and in vitro. In addition, LG4 did not show further anti-inflammatory effect in HG-challenged mesangial cells with the presence of JNK or ERK inhibitor.

Conclusion

LG4 showed renoprotective activity through inhibiting ERK/JNK-mediated inflammation in diabetic mice, indicating that LG4 may be a therapeutic agent for DKD.

CDK9 inhibition improves diabetic nephropathy by reducing inflammation in the kidneys

Diabetic nephropathy (DN) is a chronic inflammatory renal disease induced by hyperglycemia. Recent studies have implicated cyclin-dependent kinase 9 (CDK9) in inflammatory responses and renal fibrosis. In this study, we explored a potential role of CDK9 in DN by using cultured mouse mesangial cell line SV40 MES-13 and streptozotocin-induced type 1 mouse model of diabetes. We inhibited CDK9 in mice and in cultured cells by a highly selective CDK9 inhibitor, LDC000067 (LDC), and evaluated inflammatory and fibrogenic outcome by mRNA and protein analyses. Our studies show that treatment of diabetic mice with LDC significantly inhibits the levels of inflammatory cytokines and fibrogenic genes in kidney specimens. These reductions were associated with improved renal function. We also found that LDC treatment suppressed MAPK-AP1 activation. We then confirmed the involvement of CDK9 in cultured SV40 MES-13 cells and showed that deficiency in CDK9 prevents glucose-induced inflammatory and fibrogenic proteins. This protection was also afforded by suppression of MAPK-AP1. Taken together, our results how that hyperglycemia activates CDK9-MAPK-AP1 axis in kidneys to induce inflammation and fibrosis, leading to renal dysfunction. Our findings also suggest that CDK9 may serve as a potential therapeutic target for DN.

Microvascular Benefits of New Antidiabetic Agents: A Systematic Review and Network Meta-Analysis of Kidney Outcomes

CONTEXT

Diabetic kidney disease affects nearly one-third of US adults with prevalent type 2 diabetes mellitus (T2DM). The use of new antidiabetic medications in the prevention and treatment of diabetic kidney disease is a growing area of research interest.

OBJECTIVE

We sought to characterize the risk of developing a composite kidney outcome among patients receiving a new antidiabetic medication of the SGLT-2i, GLP-1ra, and DPP-4i drug classes.

METHODS

We conducted a systematic literature search in MEDLINE to identify randomized trials observing kidney safety endpoints associated with the use of new antidiabetic medications. Two independent reviewers selected the 7 eligible studies for analysis. Included studies were published between January 2013 and March 2020, conducted with adult participantss, published full-text in English, and observed composite kidney outcomes. A network meta-analysis was conducted within a Bayesian framework using a fixed-effects model with uninformative priors.

RESULTS

A qualitative assessment of transitivity was conducted to ensure similar distribution of potential modifiers across studies. Included studies were generally comparable in mean age, glycated hemoglobin A1c (HbA1c), and mean duration of T2DM at baseline.

MAIN CONCLUSIONS

Compared with placebo, dapagliflozin was associated with the greatest reduction in risk of developing the composite kidney outcome (hazard ratio 0.53; 95% credible interval, 0.43-0.66) followed by empagliflozin, canagliflozin, semaglutide, and liraglutide. Linagliptin did not show a significant reduction in risk of the outcome.

LIMITATIONS

This analysis was limited by the scarcity of data for kidney safety endpoints in large, randomized clinical trials. Although the heterogeneity statistic was low, there are slight differences in study design and baseline demographic characteristics across trials.

Forsythoside A Alleviates High Glucose-Induced Oxidative Stress and Inflammation in Podocytes by Inactivating MAPK Signaling via MMP12 Inhibition

BACKGROUND

Podocyte injury serves an important role during the progression of diabetic nephropathy (DN). The aim of this study was to investigate the effects of forsythoside A (FA) on high glucose (HG)-induced podocyte injury and to identify the possible mechanisms.

METHODS

MPC-5 podocytes were cultured under HG conditions. After exposure to different doses of FA, cell viability and apoptosis were respectively evaluated with CCK-8 assay and flow cytometry. Then, the levels of oxidative stress-related markers and inflammatory factors were examined by corresponding kits. Western blot analysis was employed to detect the expression of Nox2, Nox4, COX-2, iNOS and matrix metalloproteinases 12 (MMP12). Subsequently, MMP12 was overexpressed to assess whether the effects of FA on HG-stimulated podocyte injury were mediated by MMP12 and MAPK signaling.

RESULTS

Results indicated that FA dose-dependently elevated cell viability, reduced cell apoptosis in HG-induced MPC-5 cells. Additionally, FA significantly inhibited oxidative stress, which could be certified by decreased content of malondialdehyde (MDA), enhanced activities of superoxide dismutase (SOD) and catalase (CAT), and downregulated expression of Nox2 and Nox4. Moreover, notably reduced levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were observed in FA-treated MPC-5 cells under HG conditions, accompanied by decreased COX-2 and iNOS expression. Remarkably, FA suppressed MMP12 expression in a dose-dependent manner, and the effects of FA on MPC-5 cells exposed to HG were partially counteracted by MMP12 overexpression. Mechanically, FA inactivated the expression of phospho-ERK (p-ERK), p-p38 and p-JNK, which was restored after MMP12 overexpression.

CONCLUSION

These findings demonstrate a protective mechanism of FA by inactivating MAPK signaling via MMP12 inhibition in HG-induced podocyte injury, providing a promising therapeutic candidate for the treatment of DN.

High glucose levels increase influenza-associated damage to the pulmonary epithelial-endothelial barrier

Diabetes mellitus is a known susceptibility factor for severe influenza virus infections. However, the mechanisms that underlie this susceptibility remain incompletely understood. Here, the effects of high glucose levels on influenza severity were investigated using an in vitro model of the pulmonary epithelial-endothelial barrier as well as an in vivo murine model of type II diabetes. In vitro we show that high glucose conditions prior to IAV infection increased virus-induced barrier damage. This was associated with an increased pro-inflammatory response in endothelial cells and the subsequent damage of the epithelial junctional complex. These results were subsequently validated in vivo. This study provides the first evidence that hyperglycaemia may increase influenza severity by damaging the pulmonary epithelial-endothelial barrier and increasing pulmonary oedema. These data suggest that maintaining long-term glucose control in individuals with diabetes is paramount in reducing the morbidity and mortality associated with influenza virus infections.

Enhancing kidney DDAH-1 expression by adenovirus delivery reduces ADMA and ameliorates diabetic nephropathy

Endothelial dysfunction, characterized by reduced bioavailability of nitric oxide and increased oxidative stress, is a hallmark characteristic in diabetes and diabetic nephropathy (DN). High levels of asymmetric dimethylarginine (ADMA) are observed in several diseases including DN and are a strong prognostic marker for cardiovascular events in patients with diabetes and end-stage renal disease. ADMA, an endogenous endothelial nitric oxide synthase (NOS3) inhibitor, is selectively metabolized by dimethylarginine dimethylaminohydrolase (DDAH). Low DDAH levels have been associated with cardiac and renal dysfunction, but its effects on DN are unknown. We hypothesized that enhanced renal DDAH-1 expression would improve DN by reducing ADMA and restoring NOS3 levels. DBA/2J mice injected with multiple low doses of vehicle or streptozotocin were subsequently injected intrarenally with adenovirus expressing DDAH-1 (Ad-h-DDAH-1) or vector control [Ad-green fluorescent protein (GFP)], and mice were followed for 6 wk. Diabetes was associated with increased kidney ADMA and reduced kidney DDAH activity and DDAH-1 expression but had no effect on kidney DDAH-2 expression. Ad-GFP-treated diabetic mice showed significant increases in albuminuria, histological changes, glomerular macrophage recruitment, inflammatory cytokine and fibrotic markers, kidney ADMA levels, and urinary thiobarbituric acid reactive substances excretion as an indicator of oxidative stress, along with a significant reduction in kidney DDAH activity and kidney NOS3 mRNA compared with normal mice. In contrast, Ad-h-DDAH-1 treatment of diabetic mice reversed these effects. These data indicate, for the first time, that DDAH-1 mediates renal tissue protection in DN via the ADMA-NOS3-interaction. Enhanced renal DDAH-1 activity could be a novel therapeutic tool for treating patients with diabetes.

JAK1/JAK2 inhibition by baricitinib in diabetic kidney disease: results from a Phase 2 randomized controlled clinical trial

Background

Inflammation signaled by Janus kinases (JAKs) promotes progression of diabetic kidney disease (DKD). Baricitinib is an oral, reversible, selective inhibitor of JAK1 and JAK2. This study tested the efficacy of baricitinib versus placebo on albuminuria in adults with Type 2 diabetes at high risk for progressive DKD.

Methods

In this Phase 2, double-blind, dose-ranging study, participants were randomized 1:1:1:1:1 to receive placebo or baricitinib (0.75 mg daily; 0.75 mg twice daily; 1.5 mg daily; or 4 mg daily), for 24 weeks followed by 4–8 weeks of washout.

Results

Participants (N = 129) were 63±9.1 (mean±standard deviation) years of age, 27.1% (35/129) women and 11.6% (15/129) African-American race. Baseline hemoglobin A1c (HbA1c) was 7.3±1% and estimated glomerular filtration rate was 45.0±12.1 mL/min/1.73 m² with first morning urine albumin–creatinine ratio (UACR) of 820 (407–1632) (median; interquartile range) mg/g. Baricitinib, 4 mg daily, decreased morning UACR by 41% at Week 24 compared with placebo (ratio to baseline 0.59, 95% confidence interval 0.38–0.93, P = 0.022). UACR was decreased at Weeks 12 and 24 and after 4–8 weeks of washout. Baricitinib 4 mg decreased inflammatory biomarkers over 24 weeks (urine C–X–C motif chemokine 10 and urine C–C motif ligand 2, plasma soluble tumor necrosis factor receptors 1 and 2, intercellular adhesion molecule 1 and serum amyloid A). The only adverse event rate that differed between groups was anemia at 32.0% (8/25) for baricitinib 4 mg daily versus 3.7% (1/27) for placebo.

Conclusions

Baricitinib decreased albuminuria in participants with Type 2 diabetes and DKD. Further research is required to determine if baricitinib reduces DKD progression.

Wenshen Jianpi recipe, a blended traditional Chinese medicine, ameliorates proteinuria and renal injury in a rat model of diabetic nephropathy

Background

Wenshen Jianpi recipe (WSJPR), a blended traditional Chinese medicine, is considered to have the possible beneficial effect on the progression of diabetic nephropathy (DN). This present study was designed to elucidate this protective activity in a rat model with streptozotocin (STZ)-induced DN and to explore the possible underlying mechanism.

Methods

Adult Sprague Dawley (SD) rats were induced to develop DN through intraperitoneal injection of STZ (60 mg/kg). Animals were orally administered saline, WSJPR at 7.5, 15, 30 g/kg, and valsartan (25 mg/kg) daily for 8 weeks. Blood and 24-h urine samples of each rat were collected for biochemical examination at 2-week intervals. Microcirculatory blood flow in the renal cortex and hemorheology index were also measured. At the end of 8 weeks, all rats were sacrificed to obtain the kidney tissues for histological examination and reverse transcription polymerase chain reaction (RT-PCR) was used to analyze the transcriptional levels of nephrin and podocin genes.

Results

WSJPR could improve serum total protein (TP) and albumin (ALB), reduce the excretion rates of urine-TP (U-TP), urine-ALB (U-ALB) and urine urea nitrogen (UUN) (P < 0.05), although it did not significantly alter the hyperglycemia. In addition, treatment with WSJPR could strongly reduce blood flow, erythrocyte aggregation index, and ameliorate microcirculation. In histological measurement, WSJPR-treated rats showed a significant amelioration in glomerular hypertrophy and mesangial expansion. By RT-PCR, we found WSJPR up-regulated the nephrin and podocin expression at mRNA levels.

Conclusion

This study suggested that WSJPR could effectively relieve renal damage and improve renal function of DN rats by ameliorating metabolism disorder and increasing the gene expression of nephrin and podocin, which might be a useful approach for the treatment of DN.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

A systematic review of the effects of strength training in patients with fibromyalgia: clinical outcomes and design considerations

BACKGROUND

Fibromyalgia (FM) is characterized by chronic and generalized musculoskeletal pain. There is currently no cure for FM, but palliative treatments are available. One type of treatment is strength training (ST). However, there is a need for more information on optimal training protocols, intensity, and volume needed to improve symptoms. The aim of this study was to analyze the effects of ST in the treatment of FM through a systematic review of experimental research.

METHODS

Medical Subject Headings search terms and electronic databases including Scientific Electronic Library Online, PubMed, Science Direct, Web of Science, and Physiotherapy Evidence Database were used to identify studies.

RESULTS

The inclusion criteria were met by 22 eligible studies. Most of the studies were conducted in the United States (36%), Finland (23%), Brazil (18%), and Sweden (18%). The studies showed that ST reduces the number of tender points, fatigue, depression, and anxiety, and improves sleep quality and quality of life in patients with FM. The intervention period ranged from 3 to 21 weeks, with sessions performed 2 times a week in 81.81% of the studies, at initial intensities of 40% of 1-repetition maximum. The repetitions ranged from 4 to 20, with no specific protocol defined for ST in FM.

CONCLUSION

The main results included reduction in pain, fatigue, number of tender points, depression, and anxiety, with increased functional capacity and quality of life. Current evidence demonstrates that ST is beneficial and can be used to treat FM.

TRIAL REGISTRATION

CRD42016048480.

NLRC5 deficiency ameliorates diabetic nephropathy through alleviating inflammation

NOD-like receptor family caspase recruitment domain family domain containing 5 (NLRC5) has important roles in inflammation and innate immunity. NLRC5 was highly expressed in kidney from streptozotocin-induced diabetic mice, db/ db mice and patients with diabetes. Based on that evidence, the present study was designed to explore the roles of NLRC5 in the progression of diabetic nephropathy (DN). We examined kidney injury, including inflammation and fibrosis in Nlrc5 gene knockout ( Nlrc5^-/-) and wild-type (WT) diabetic mice. We found that Nlrc5^-/- mice developed less-severe diabetic kidney injury compared with WT mice, exhibiting lower albuminuria, less fibronectin and collagen IV expression, and reduced macrophage infiltration but greater levels of podocin and nephrin in the diabetic kidney. The underlying mechanisms were further investigated in vitro with peritoneal macrophages and mesangial cells treated with high glucose. Reduced proinflammatory effect was observed in peritoneal macrophages from Nlrc5^-/- mice, associated with NF-κB pathway suppression. Knocking down of NLRC5 in mesangial cells in high-glucose conditions was also associated with reduced NF-κB and TGF-β/Smad signaling. Taken together, NLRC5 promotes inflammation and fibrosis during DN progression partly through the effects on NF-κB and TGF-β/Smad pathways. NLRC5 may, therefore, be a promising therapeutic target for DN treatment.-Luan, P., Zhuang, J., Zou, J., Li, H., Shuai, P., Xu, X., Zhao, Y., Kou, W., Ji, S., Peng, A., Xu, Y., Su, Q., Jian, W., Peng, W. NLRC5 deficiency ameliorates diabetic nephropathy through alleviating inflammation.

Distinct roles of arginases 1 and 2 in diabetic nephropathy

Diabetes is the leading cause of end-stage renal disease, resulting in a significant health care burden and loss of economic productivity by affected individuals. Because current therapies for progression of diabetic nephropathy (DN) are only moderately successful, identification of underlying mechanisms of disease is essential to develop more effective therapies. We showed previously that inhibition of arginase using S-(2-boronoethyl)-l-cysteine (BEC) or genetic deficiency of the arginase-2 isozyme was protective against key features of nephropathy in diabetic mouse models. However, those studies did not determine whether all markers of DN were dependent only on arginase-2 expression. The objective of this study was to identify features of DN that are associated specifically with expression of arginase-1 or -2. Elevated urinary albumin excretion rate and plasma urea levels, increases in renal fibronectin mRNA levels, and decreased renal medullary blood flow were associated almost completely and specifically with arginase-2 expression, indicating that arginase-2 selectively mediates major aspects of diabetic renal injury. However, increases in renal macrophage infiltration and renal TNF-α mRNA levels occurred independent of arginase-2 expression but were almost entirely abolished by treatment with BEC, indicating a distinct role for arginase-1. We therefore generated mice with a macrophage-specific deletion of arginase-1 (CD11bCre /Arg1fl/fl ). CD11bCre /Arg1fl/fl mice had significantly reduced macrophage infiltration but had no effect on albuminuria compared with Arg1fl/fl mice after 12 wk of streptozotocin-induced diabetes. These results indicate that selective inhibition of arginase-2 would be effective in preventing or ameliorating major features of diabetic renal injury.

Protective effects of allicin on streptozotocin-induced diabetic nephropathy in rats

BACKGROUND

Studies in animal models have shown that allicin, a major biologically active component of garlic, can play a role in the prevention of tissue fibrosis in the liver, lung and heart, mainly related to the inhibition of fibroblast proliferation, fibrogenic cytokine secretion and extracellular matrix synthesis. This study aimed to investigate the protective effects of allicin on renal damage in streptozotocin (STZ)-induced diabetic rats. STZ-induced diabetic rats were administered allicin (15, 30 and 45 mg · kg^-1  · day^-1 ) via daily intra-gastric gavage for 12 weeks. The levels of fasting blood glucose (FBG), blood urea nitrogen (BUN), serum creatinine (sCr), lipid and 24 h urine albumin excretion (UAE) were measured at the end of weeks 4, 8 and 12. The renal histopathology and the expression levels of collagen I, transforming growth factor β1 (TGF-β1) and phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) were measured using immunohistochemistry and/or western blotting.

RESULTS

In 12 week STZ-induced diabetic rats, severe hyperglycemia and albuminuria were markedly developed. Treatment with allicin for 12 weeks ameliorated diabetes-induced morphological alterations of the kidney and decreased FBG, BUN, sCr, triglyceride (TG) and 24 h UAE in diabetic rats. The expression levels of collagen I, TGF-β1 and p-ERK1/2 were significantly decreased by allicin treatment.

CONCLUSION

These results suggested that allicin may play a protective role in diabetic nephropathy via the TGF-β1/ERK pathway in diabetic rats. © 2016 Society of Chemical Industry.

Calcium Dobesilate Prevents Diabetic Kidney Disease by Decreasing Bim and Inhibiting Apoptosis of Renal Proximal Tubular Epithelial Cells

Apoptosis of renal proximal tubular epithelial cells (PTECs) plays a vital role in the pathogenesis and progression of diabetic kidney disease (DKD). Calcium dobesilate is a vascular protective compound used for treatment of diabetic retinopathy and chronic venous insufficiency. The aim of this study was to determine whether calcium dobesilate can protect PTECs from glucose-induced apoptosis and the potential mechanism of this effect. It is indicated that high glucose promoted abnormal apoptosis of HK2 cells, which was inhibited by treatment of calcium dobesilate, while Bim expression decreased in response to calcium dobesilate in high-glucose-treated HK2 cells. These findings confirmed the therapeutic effects of calcium dobesilate on DKD and emphasized the importance of it as a potentially crucial drug in treatment of DKD.

Corosolic acid inhibits the proliferation of glomerular mesangial cells and protects against diabetic renal damage

Diabetic nephropathy (DN) is one of the major complications of diabetes mellitus (DM). This study aimed to explore the effects of corosolic acid (CA) on the renal damage of DM and the mechanisms behind these effects. The renoprotective effect of CA was investigated in type 1 diabetic rats and db/db mice. The kidneys and glomerular mesangial cells (GMCs) were used to study the proliferation of GMCs by immunostaining and MTT assay. Further immunoblotting, siRNA, qPCR analysis, and detecting of NADPH oxidase activity and reactive oxygen species (ROS) generation were performed to explore relevant molecular mechanisms. In CA-treated diabetic animals, diabetes-induced albuminuria, increased serum creatinine and blood urea nitrogen were significantly attenuated, and glomerular hypertrophy, mesangial expansion and fibrosis were ameliorated. Furthermore, CA significantly inhibited proliferation of GMCs and phosphorylation of ERK1/2 and p38 MAPK in both diabetic animals and high glucose (HG)-induced GMCs. CA also normalized Δψm and inhibited HG-induced NADPH oxidase activity, ROS generation and NOX4, NOX2, p22(phox) and p47(phox) expression. More importantly, CA inhibited GMC proliferation mediated by NADPH/ERK1/2 and p38 MAPK signaling pathways. These findings suggest that CA exert the protective effect on DN by anti-proliferation resulted from inhibition of p38 MAPK- and NADPH-mediated inactivation of ERK1/2.

Neutrophil-lymphocyte ratio: Predicting cardiovascular and renal complications in patients with diabetes

PURPOSE

Diabetes mellitus (DM) is a growing pandemic. The cause of mortality for most patients with DM is cardiovascular or renal complications. The purpose of this article is to discuss the emerging role of the neutrophil-lymphocyte ratio (NLR) as a prognostic marker in predicting development and progression of diabetic nephropathy (DN) as well as major adverse cardiac events (MACEs), and related mortality in patients diagnosed with DM.

DATA SOURCES

A review of original research published in English identified through CINAHL and PubMed was performed.

CONCLUSIONS

Research identifies the NLR as an independent predictor of the development and progression of DN, MACE occurrence, and subsequent mortality. Studies with larger sample sizes are needed to strengthen the current evidence. Future studies must also identify specific NLR values that can be used as reference points for risk prognostication for patients.

IMPLICATIONS FOR PRACTICE

Current evidence reinforces the need to consider the use of new prognostic tools for DN and cardiovascular disease in patients with DM. The use of the NLR in clinical practice can greatly improve quality of life for those with DM by establishing more effective disease management.

The renal protective effects of Anoectochilus roxburghii polysaccharose on diabetic mice induced by high-fat diet and streptozotocin

ETHNOPHARMACOLOGICAL RELEVANCE

Anoectochilus roxburghii (Wall.) Lindl. 1832 is an herbal medicine used to treat diabetes in China. Considering that Anoectochilus roxburghii polysaccharose (ARP) is the main constituent of Anoectochilus roxburghii, the present study is aimed to investigate the renal protection of ARP and its possible mechanism in diabetic mice.

MATERIALS AND METHODS

Institute of Cancer Research (ICR) mice were induced to diabetes with high-fat diet (HFD) and low-dose streptozotocin (STZ). ARP (100, 300 mg/kg) was orally administrated to diabetic mice once a day for consecutive 15 days. The fasting glucose level, expressions of key proteins of p38 MAP kinase cascade, inflammatory factors, fibronectin (FN) and the activities of matrix metalloproteinases (MMPs) were measured. Furthermore, the histological examination of the separated kidneys was also carried out.

RESULTS

Compared with the diabetic mice, ARP administration induced a significant decrease in blood glucose level and improved the body weight of diabetic mice. In addition, ARP inhibited the expression of renal p38 MAP kinase cascade and its downstream inflammatory factors including tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), FN as well as MMP2/9. Moreover, the histological examination showed an apparent reduction of mesangial matrix deposition and damage of microvascular structure after ARP administration.

CONCLUSIONS

The protective effects of ARP on diabetic renal damage may be attributed to the inhibition of p38 MAP kinase cascade and then attenuating the inflammatory responses and high glucose-induced renal damage.

Xiaokeping mixture inhibits diabetic nephropathy in streptozotocin-induced rats through blocking TGF-β1/Smad7 signaling

Background

Diabetic nephropathy (DN) is a major cause of chronic kidney failure and characterized by excessive deposition of extracellular matrix. Evidence have shown that transforming growth factor-β1 (TGF-β1) is a key mediator in the development of DN. However, treatment of DN by blocking the TGF-β1/Smad7 pathway remains limited. Xiaokeping mixture (XKP), a traditional Chinese herbal compound, has been used for treatment in patients with DN for many years.

Methods

In the present study, TGF-β1/Smad7 pathway analysis was used to evaluate the therapeutic effect of XKP on DN rats induced by streptozotocin and to address the underlying molecular mechanism. Male rats were divided into four groups: normal control, untreated control group (fed with high fat), irbesartan-treated DN, and XKP-treated DN, respectively. Levels of serum creatinine, blood urea nitrogen, urine protein of 24 hours, and triacylglycerol were detected. Pathological changes of renal tissues were observed by hematoxylin–eosin staining. Immunohistochemical and Western blot analysis were used to detect the expressions of TGF-β1 and Smad7.

Results

The results demonstrated that XKP can effectively reduce the levels of glucose, serum creatinine, blood urea nitrogen, urine protein of 24 hours, and triacylglycerol. Further studies indicated that inhibition of DN in XKP-treated DN rats was associated with inhibition of TGF-β1/Smad7 signaling as demonstrated by downregulation of TGF-β1 but upregulation of Smad7.

Conclusion

The data obtained from the present study indicate that XKP may be a therapeutic agent for DN.

Nephroprotection by Hypoglycemic Agents: Do We Have Supporting Data?

Current therapy directed at delaying the progression of diabetic nephropathy includes intensive glycemic and optimal blood pressure control, renin angiotensin-aldosterone system blockade and multifactorial intervention. However, the renal protection provided by these therapeutic modalities is incomplete. There is a scarcity of studies analysing the nephroprotective effect of antihyperglycaemic drugs beyond their glucose lowering effect and improved glycaemic control on the prevention and progression of diabetic nephropathy. This article analyzes the exisiting data about older and newer drugs as well as the mechanisms associated with hypoglycemic drugs, apart from their well known blood glucose lowering effect, in the prevention and progression of diabetic nephropathy. Most of them have been tested in humans, but with varying degrees of success. Although experimental data about most of antihyperglycemic drugs has shown a beneficial effect in kidney parameters, there is a lack of clinical trials that clearly prove these beneficial effects. The key question, however, is whether antihyperglycemic drugs are able to improve renal end-points beyond their antihyperglycemic effect. Existing experimental data are post hoc studies from clinical trials, and supportive of the potential renal-protective role of some of them, especially in the cases of dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Dedicated and adequately powered renal trials with renal outcomes are neccessary to assess the nephrotection of antihyperglycaemic drugs beyond the control of hyperglycaemia.

Anthocyanins inhibit high-glucose-induced cholesterol accumulation and inflammation by activating LXRα pathway in HK-2 cells

The dysregulation of cholesterol metabolism and inflammation plays a significant role in the progression of diabetic nephropathy (DN). Anthocyanins are polyphenols widely distributed in food and exert various biological effects including antioxidative, anti-inflammatory, and antihyperlipidemic effects. However, it remains unclear whether anthocyanins are associated with DN, and the mechanisms involved in the reciprocal regulation of inflammation and cholesterol efflux are yet to be elucidated. In this study, we evaluated the regulation of cholesterol metabolism and the anti-inflammatory effects exerted by anthocyanins (cyanidin-3-O-β-glucoside chloride [C3G] or cyanidin chloride [Cy]) and investigated the underlying molecular mechanism of action using high-glucose (HG)-stimulated HK-2 cells. We found that anthocyanins enhanced cholesterol efflux and ABCA1 expression markedly in HK-2 cells. In addition, they increased peroxisome proliferator-activated receptor alpha (PPARα) and liver X receptor alpha (LXRα) expression and decreased the HG-induced expression of the proinflammatory cytokines intercellular adhesion molecule-1 (ICAM1), monocyte chemoattractant protein-1 (MCP1), and transforming growth factor-β1 (TGFβ1), as well as NFκB activation. Incubation with the PPARα-specific inhibitor GW6471 and LXRα shRNA attenuated the anthocyanin-mediated promotion of ABCA1 expression and cholesterol efflux, suggesting that anthocyanins activated PPARα-LXRα-ABCA1-dependent cholesterol efflux in HK-2 cells. Moreover, the knockout of LXRα abrogated the anti-inflammatory effect of anthocyanins, whereas the PPARα antagonist GW6471 does not have this effect. Further investigations revealed that LXRα might interfere with anthocyanin-induced decreased ICAM1, MCP1, and TGFβ1 expression by reducing the nuclear translocation of NFκB. Collectively, these findings suggest that blocking cholesterol deposition and inhibiting the LXRα pathway-induced inflammatory response might be one of the main mechanisms by which anthocyanins exert their protective effects in DN.

Delayed Treatment with a Small Pigment Epithelium Derived Factor (PEDF) Peptide Prevents the Progression of Diabetic Renal Injury

Our recent publication showed that a small bioactive pigment epithelium derived factor (PEDF) peptide (P78-PEDF) prevents the development of diabetic nephropathy (DN). However, its effects on the progression of established DN were not clear. Therefore, the purpose of this study was to determine the effect of P78-PEDF in the progression of DN and to compare the effects of P78-PEDF and an ACE inhibitor (ACEi), a standard of care in DN. Experiments were conducted in Ins2^Akita mice treated with P78-PEDF or captopril starting at 6 wks of age for 12 wks (early treatment) or starting at 12 wks of age for 6 wks (late treatment). We first established the optimal dose of the P78-PEDF peptide to ameliorate DN in Ins2^Akita mouse for a 6 wk study period and found that the peptide was effective at 0.1- 0.5 µg/g/day. We next showed that early or late treatment with P78-PEDF resulted in protection from DN as indicated by reduced albuminuria, kidney macrophage recruitment, histological changes, inflammatory cytokines and fibrotic markers (kidney TNF-α, fibronectin, VEGFA and EGFR), and restored nephrin expression compared with vehicle-treated Ins2^Akita mice. Interestingly, only early but not late treatment with captopril was as effective as P78-PEDF in reducing most DN complications, despite its lack of effect on nephrin, VEGFA and EGFR expression. These findings highlight the importance of P78-PEDF peptide as a potential therapeutic modality in both the development and progression of diabetic renal injury.

Macrophage-derived tumor necrosis factor-α mediates diabetic renal injury

Monocyte/macrophage recruitment correlates strongly with the progression of diabetic nephropathy. Tumor necrosis factor-alpha (TNF-α) is produced by monocytes/macrophages but the direct role of TNF-α and/or macrophage-derived TNF-α in the progression of diabetic nephropathy remains unclear. Here we tested whether inhibition of TNF-α confers kidney protection in diabetic nephropathy via a macrophage-derived TNF-α dependent pathway. Compared to vehicle-treated mice, blockade of TNF-α with a murine anti-TNF-α antibody conferred kidney protection in Ins2Akita mice as indicated by reductions in albuminuria, plasma creatinine, histopathologic changes, kidney macrophage recruitment and plasma inflammatory cytokine levels at 18 weeks of age. To assess the direct role of macrophage-derived TNF-α in diabetic nephropathy, we generated macrophage specific TNF-α deficient mice (CD11bCre/TNF-α^Flox/Flox). Conditional ablation of TNF-α in macrophages significantly reduced albuminuria, the increase in plasma creatinine and BUN, histopathologic changes and kidney macrophage recruitment compared to diabetic TNF-α^Flox/Flox control mice after 12 weeks of streptozotocin-induced diabetes. Thus, production of TNF-α by macrophages plays a major role in diabetic renal injury. Hence, blocking TNF-α could be a novel therapeutic approach for treatment of diabetic nephropathy.

Arginase inhibition: a new treatment for preventing progression of established diabetic nephropathy

Our previous publication showed that inhibition of arginase prevents the development of diabetic nephropathy (DN). However, identification of targets that retard the progression of established DN-which is more clinically relevant-is lacking. Therefore, we tested the hypothesis that arginase inhibition would prevent the progression of established DN. Effects of arginase inhibition were compared with treatment with the angiotensin-converting enzyme inhibitor captopril, a current standard of care in DN. Experiments were conducted in Ins2(Akita) mice treated with the arginase inhibitor S-(2-boronoethyl)-l-cysteine (BEC) or captopril starting at 6 wk of age for 12 wk (early treatment) or starting at 12 wk of age for 6 wk (late treatment). Early and late treatment with BEC resulted in protection from DN as indicated by reduced albuminuria, histological changes, kidney macrophage infiltration, urinary thiobarbituric acid-reactive substances, and restored nephrin expression, kidney nitrate/nitrite, kidney endothelial nitric oxide synthase phosphorylation, and renal medullary blood flow compared with vehicle-treated Ins2(Akita) mice at 18 wk of age. Interestingly, early treatment with captopril reduced albuminuria, histological changes, and kidney macrophage infiltration without affecting the other parameters, but late treatment with captopril was ineffective. These findings highlight the importance of arginase inhibition as a new potential therapeutic intervention in both early and late stages of diabetic renal injury.

Tripterygium Glycosides Tablet Ameliorates Renal Tubulointerstitial Fibrosis via the Toll-Like Receptor 4/Nuclear Factor Kappa B Signaling Pathway in High-Fat Diet Fed and Streptozotocin-Induced Diabetic Rats

Tripterygium glycosides tablet (TGT) is a Chinese traditional medicine that has been shown to protect podocytes from injury and reduce the proteinuria. The aim of this study was to assess the effect of TGT on renal tubulointerstitial fibrosis and its potential mechanism in high-fat diet fed and STZ-induced diabetic rats. Rats were randomly divided into normal control rats (NC group), diabetic rats without drug treatment (DM group), and diabetic rats treated with TGT (1, 3, or 6 mg/kg/day, respectively) for 8 weeks. The results showed that 24 h proteinuria and urinary N-acetyl-glucosaminidase (NAG) in diabetic rats were decreased by TGT treatment without affecting blood glucose. Masson's trichrome stains showed that apparent renal tubulointerstitial fibrosis was found in DM group, which was ameliorated by TGT treatment. The expression of α-SMA was significantly decreased, accompanied by increased expression of E-cadherin in TGT-treated rats, but not in untreated DM rats. Further studies showed that TGT administration markedly reduced expression of TLR4, NF-κB, IL-1β, and MCP-1 in TGT-treated diabetic rats. These results showed that TGT could ameliorate renal tubulointerstitial fibrosis, the mechanism which may be at least partly associated with the amelioration of EMT through suppression of the TLR4/NF-κB pathway.

Attenuation of diabetic nephropathy by Chaihuang-Yishen granule through anti-inflammatory mechanism in streptozotocin-induced rat model of diabetics

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medical herbs have been used in China for a long time to treat different diseases. Based on traditional Chinese medicine (TCM) principle, Chaihuang-Yishen granule (CHYS) was developed and has been employed clinically to treat chronic kidney disease including diabetic nephropathy (DN). The present study was designed to investigate its mechanism of action in treatment of DN.

MATERIALS AND METHODS

Diabetic rats were established by having a right uninephrectomy plus a single intraperitoneal injection of STZ. Rats were divided into four groups of sham, diabetes, diabetes with CHYS and diabetes with fosinopril. CHYS and fosinopril were given to rats by gavage for 20 weeks. Samples from blood, urine and kidney were collected for biochemical, histological, immunohistochemical and molecular analyses.

RESULTS

Rats treated with CHYS showed reduced 24h urinary protein excretion, decreased serum TC and TG levels, but CHYS treatment did not affect blood glucose level. Glomerular mesangial expansion and tubulointerstitial fibrosis in diabetic rats were significantly alleviated by CHYS treatment. Moreover, CHYS administration markedly reduced mRNA levels of NF-κB p65 and TGF-β1, as well as decreased protein levels of NF-κB p65, MCP-1, TNF-α and TGF-β1 in the kidney of diabetic rats.

CONCLUSIONS

CHYS ameliorates renal injury in diabetic rats through reduction of inflammatory cytokines and their intracellular signaling.

Protective role of small pigment epithelium-derived factor (PEDF) peptide in diabetic renal injury

Pigment epithelium-derived factor (PEDF) is a multifunctional protein with antiangiogenic, antioxidative, and anti-inflammatory properties. PEDF is involved in the pathogenesis of diabetic retinopathy, but its direct role in the kidneys remains unclear. We hypothesize that a PEDF fragment (P78-PEDF) confers kidney protection in diabetic nephropathy (DN). The localization of the full-length PEDF protein were determined in DBA mice following multiple low doses of streptozotocin. Using immunohistochemistry, PEDF was localized in the kidney vasculature, interstitial space, glomeruli, tubules, and renal medulla. Kidney PEDF protein and mRNA expression were significantly reduced in diabetic mice. Continuous infusion of P78-PEDF for 6 wk resulted in protection from diabetic neuropathy as indicated by reduced albuminuria and blood urea nitrogen, increased nephrin expression, decreased kidney macrophage recruitment and inflammatory cytokines, and reduced histological changes compared with vehicle-treated diabetic mice. In vitro, P78-PEDF blocked the increase in podocyte permeability to albumin and disruption of the actin cytoskeleton induced by puromycin aminonucleoside treatment. These findings highlight the importance of P78-PEDF peptide as a potential therapeutic modality in early phase diabetic renal injury.

Effects of Zishentongluo in Patients with Early-Stage Diabetic Nephropathy

The purpose of this study was to assess the efficacy of zishentongluo (ZSTL) for the treatment of diabetic nephropathy (DN) and its related mechanisms. Forty-five patients with DN were randomized to receive either ZSTL (n = 25) or benazepril (n = 20), an angiotensin converting enzyme inhibitor, for 12 weeks. Conventional biochemical tests were performed to determine fasting blood glucose (FBG), glycated hemoglobin (HbA1c), serum creatinine (SCr), endogenous creatinine clearance rate (Ccr), total cholesterol (TC), and triglyceride (TG) levels. The urinary albumin excretion rate (UAER), and endothelin 1 (ET-1), and atrial natriuretic peptide (ANP) levels were determined with a radioimmunoassay, and vascular endothelial growth factor (VEGF) was detected using an enzyme-linked immunosorbent assay. The primary endpoint was change from the baseline to post-treatment in HbA1c. Secondary endpoints were change from baseline to post-treatment in FBG, TC, TG, UAER, SCr, Ccr, VI-C, ANP, ET-1, and VEGF. ZSTL was significantly more effective at improving the primary (i.e., HbA1c) and secondary (i.e., FBG, TC, TG, UAER, SCr, ANP, ET-1, and VEGF) outcomes than benazepril (p < 0.05). These findings suggest that ZSTL is superior to benazepril at improving the metabolic and renal functioning in patients with early-stage DN, in part, by modifying ANP, ET-1, and VEGF.

Proteinuria in systemic sclerosis: reversal by ACE inhibition

In systemic sclerosis (SSc), kidney damage is a major clinical problem which can lead to a deleterious outcome. Recently, in diabetes mellitus, early detection of proteinuria and treatment with angiotensin-converting enzyme (ACE) inhibitors has been shown to slow progression of kidney disease and to improve prognosis. In this study, we investigated the spontaneous course of proteinuria in SSc and the effects of ACE inhibitor therapy. Proteinuria was determined in SSc patients with urine protein electrophoresis. SSc patients with proteinuria (n = 31) were followed over a median of 12 months. Of all 31 patients with pathologic urine protein electrophoresis investigated in this study, 9 patients (29 %) had additional microalbuminuria and 4 patients (12.9 %) showed increased total urinary protein. ACE inhibitor treatment was subsequently given to 23 patients. A total of 8 patients remained untreated for various reasons. Proteinuria resolved in 74 % of patients treated with ACE inhibitors, whereas in the untreated group, remission was observed only in 25 % (p = 0.014). Improvement of proteinuria was predominantly achieved in patients with recently diagnosed proteinuria and short disease duration. In patients with SSc and proteinuria, initiation of ACE inhibitor therapy resulted in a significant decrease in proteinuria.

Diabetic nephropathy: traditional to proteomic markers

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

Therapeutic Modalities in Diabetic Nephropathy: Future Approaches

Diabetes mellitus is the leading cause of end stage renal disease and is responsible for more than 40% of all cases in the United States. Several therapeutic interventions for the treatment of diabetic nephropathy have been developed and implemented over the past few decades with some degree of success. However, the renal protection provided by these therapeutic modalities is incomplete. More effective approaches are therefore urgently needed. Recently, several novel therapeutic strategies have been explored in treating DN patients including Islet cell transplant, Aldose reductase inhibitors, Sulodexide (GAC), Protein Kinase C (PKC) inhibitors, Connective tissue growth factor (CTGF) inhibitors, Transforming growth factor-beta (TGF-β) inhibitors and bardoxolone. The benefits and risks of these agents are still under investigation. This review aims to summarize the utility of these novel therapeutic approaches.

Stem cells as a therapeutic approach to chronic kidney diseases

Much attention recently has been focused on stem cell technology as a possible alternative modality of treatment of a variety of diseases. Chronic kidney disease is a serious health problem and most chronic kidney diseases share in common the presence of interstitial and glomerular fibrosis, regardless of the underlying cause. To date there are no specific therapies aimed at treating fibrosis in the kidney. In a novel effort to address the underlying pathology in kidney disease, researchers are demonstrating that stem cell therapy can attenuate fibrosis in chronic kidney disease in animal models. This review will focus on the recent developments in stem cell research and their possible implications to treat chronic kidney disease.