Pathophysiology of Diabetic Nephropathy: Involvement of Multifaceted Signalling Mechanism

Characteristics and risk factors for renal recovery after acute kidney injury in critically ill patients in cohorts of elderly and non-elderly: a multicenter retrospective cohort study

BACKGROUND

The purpose of this study was to explore the risk factors for renal nonrecovery among elderly and nonelderly patients with acute kidney injury (AKI) in critically ill patients.

METHODS

A multicenter retrospective cohort of 583 critically ill patients with AKI was examined. We found the best cutoff value for predicting renal recovery by age was 63 years old through logistic regression. All patients were divided into two cohorts, age <63 and age ≥63-years old; on the basis of renal recovery at 30 days after AKI, the two patient cohorts were further divided into a renal recovery group and a renal nonrecovery group. Multivariate logistic regression was used to analyze the risk factors affecting renal recovery in the two cohorts.

RESULTS

The 30-day renal recovery rate of patients aged <63 years was 70.0% (198/283), multivariate analysis showed that the independent risk factors affecting renal nonrecovery in age <63 years old included AKI stage, blood lactate level and hemoglobin level. The 30-day renal recovery rate of patients aged ≥63 years was 28.7% (86/300), multivariate analysis showed that the independent risk factors for renal nonrecovery in age ≥63-years old included diabetes mellitus, surgery with general anesthesia, AKI stage, APACHE II score, eGFR, and hemoglobin level.

CONCLUSIONS

The renal nonrecovery after AKI in critically ill patients in patients aged ≥63 years was more strongly affected by multiple risk factors, such as diabetes mellitus, surgery with general anesthesia, eGFR, and APACHE II score, in addition to hemoglobin and AKI stage.

A delve into the pharmacological targets and biological mechanisms of Paederia foetida Linn.: a rather invaluable traditional medicinal plant

Drug development from herbal medicines or botanical sources is believed to have a prominent role in the exploration of novel counteractive drugs that has sparked much interest in recent times. Paederia foetida is one such medicinal plant used in both traditional and folkloric medicine. Several parts of the herb are locally utilised as a natural curative agent for several ailments since time immemorial. Paederia foetida indeed possesses anti-diabetic, anti-hyperlipidaemic, antioxidant, nephro-protective, anti-inflammatory, antinociceptive, antitussive, thrombolytic, anti-diarrhoeal, sedative-anxiolytic, anti-ulcer, hepatoprotective activity, anthelmintic and anti-diarrhoeal activity. Furthermore, growing evidence shows many of its active constituents to be effective in cancer, inflammatory diseases, wound healing and spermatogenesis as well. These investigations shed light on possible pharmacological targets and attempts to establish a mechanism of action for these pharmacological effects. These findings contrast the significance of this medicinal plant for further research and for the exploration of novel counteractive drugs to establish a mechanism of action before being employed to healthcare. Pharmacological activities of Paederia foetida and their mechanism of action.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

Impact of SGLT2 inhibitors on the kidney in people with type 2 diabetes and severely increased albuminuria

INTRODUCTION

Diabetes is the most common cause of end stage kidney disease. Therapies such as sodium-glucose co-transporter-2 inhibitors have been identified over the last decade as effective oral hypoglycemic agents that also confer additional cardio and kidney protection. Knowledge of their mechanism of action and impact on patients with diabetes and albuminuria is vital in galvanizing prescriber confidence and increasing clinical uptake.

AREAS COVERED

This manuscript discusses the pathophysiology of diabetic kidney disease, patho-physiological mechanisms for sodium-glucose co-transporter-2 inhibitors, and their impact on patients with Type 2 diabetes mellitus and albuminuric kidney disease.

EXPERT OPINION

Sodium-glucose co-transporter-2 inhibitors reduce albuminuria with consequent benefits on cardiovascular and kidney outcomes in patients with diabetes and severe albuminuria. Whilst they have been incorporated into guidelines, the uptake of these agents into clinical practice has been slow. Increasing the uptake of these agents into clinical practice is necessary to improve outcomes for the large number of patients with diabetic kidney disease globally.

Diabetes complications and extracellular vesicle therapy

Diabetes is a chronic disorder characterized by dysregulated glycemic conditions. Diabetic complications include microvascular and macrovascular abnormalities and account for high morbidity and mortality rates in patients. Current clinical approaches for diabetic complications are limited to symptomatic treatments and tight control of blood sugar levels. Extracellular vesicles (EVs) released by somatic and stem cells have recently emerged as a new class of potent cell-free therapeutic delivery packets with a great potential to treat diabetic complications. EVs contain a mixture of bioactive molecules and can affect underlying pathological processes in favor of tissue healing. In addition, EVs have low immunogenicity and high storage capacity while maintaining nearly the same regenerative and immunomodulatory effects compared to current cell-based therapies. Therefore, EVs have received increasing attention for diabetes-related complications in recent years. In this review, we provide an outlook on diabetic complications and summarizes new knowledge and advances in EV applications. Moreover, we highlight recommendations for future EV-related research.

Isoliquiritigenin attenuates acute renal injury through suppressing oxidative stress, fibrosis and JAK2/STAT3 pathway in streptozotocin-induced diabetic rats

The aim of the current study was to evaluate the protective effects and mechanisms of isoliquiritigenin (ISO) on acute renal injury. CCK-8 assays were applied to assess the effects of ISO at different doses (20, 40, and 80 μg/mL) on oxidative damage in human renal HK-2 cells incubated with high glucose. After the diabetic nephropathy (DN) rat model was established, the model animals were randomly assigned to saline-treated control, three model groups received the 10, 20 and 40 mg/kg ISO, respectively, using the healthy Sprague-Dawley (SD) rats as normal control. The blood biochemical indexes, renal functions, oxidative stress, morphological changes, fibrosis- and JAK2/STAT3-related factors in DN model rats were all assessed. The cellular viability of the renal HK-2 cells with oxidative damages were all markedly ameliorated via the incubation of ISO between 10 and 80 μg/mL compared with negative control. In addition, the significantly down-regulated ROS content and up-regulated expression levels of GSH, SOD2, and GPX1 were all observed in ISO-treated groups. Long-term administration of ISO at different doses in DN rats effectively improved general diabetic characteristics and renal morphology. Furthermore, long-term administration of ISO could ameliorate excessive oxidation stress, down-regulate the expression levels of renal fibrosis- and inflammation-related factors, as well as inhibit the JAK2/STAT3 signaling pathway. In conclusion, ISO at all three dosages could efficiently improve the renal injury induced by STZ via ameliorating renal fibrosis, oxidative stress, and inhibiting JAK2/STAT3 signaling pathways in the DN rats.

Trimetazidine an emerging paradigm in renal therapeutics: Preclinical and clinical insights

Trimetazidine (TMZ) is a well-known anti-ischemic agent used for the treatment of angina pectoris. In the past decades, the efficacy of this drug has been tested in a wide range of kidney injuries, including drug-induced nephrotoxicity (DIN), radio-contrast agent-induced nephropathy, and surgically induced renal ischemic injury. TMZhas renoprotective effects by attenuating oxidative stress, inflammatory cytokine release, maintaining oxygen and energy balance. Moreover, TMZ administration prevented kidney graft rejection in the porcine model by suppressing the infiltration of mononuclear cells, preserving mitochondrial functions, and maintaining Ca+ homeostasis. In DIN and diabetic kidney diseases,TMZ treatment prevents renal injury by inactivating immune cells, attenuating renal fibrosis, inflammation, apoptosis, and histological abnormalities. Interestingly, the clinical therapeutic efficacy of TMZ has also been documented in pre-existing kidney disease patients undergoing contrast exposure for diagnostic intervention. However, the mechanistic insights into the TMZ mediated renoprotective effects in other forms of renal injuries, including type-2 diabetes, drug-induced nephrotoxicity, and hypertension-induced chronic kidney diseases, remain uninvestigated and incomplete. Moreover, the clinical utility of TMZ as a renoprotective agent in radio-contrast-induced nephrotoxicity needs to be tested in a large patient population. Nevertheless, the available pieces of evidence suggest that TMZ is a promising and emerging renal therapy for the treatment and management of kidney diseases of variable etiologies. This review discusses the various pre-clinical and clinical findings and provides mechanistic insights into the TMZ mediated beneficial effects in various kidney diseases.

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.

Nanomedicine in the treatment of diabetic nephropathy

Globally, diabetic nephropathy (DN) is the foremost cause of end-stage renal disease. With the incidence of diabetes increasing day by day, DN's occurrence is expected to surge to pandemic proportions. Current available therapeutic interventions associated with DN emphasize blood pressure, glycemia and lipid control while ignoring DN's progression mechanism at a molecular level. This review sheds light on the molecular insights involved in DN to help understand the initiation and progression pattern. Further, we summarize novel strategies with reported applications in developing a nanomedicine-based platform for DN-targeted drug delivery to improve drug efficacy and safety.

Polydatin-loaded chitosan nanoparticles ameliorates early diabetic nephropathy by attenuating oxidative stress and inflammatory responses in streptozotocin-induced diabetic rat

In various developed countries, diabetic nephropathy (DN) is the principal cause of end-stage kidney disease and a main reason of injury and mortality in individuals with renal morbidity worldwide. Polydatin (POL) has been evaluated as a potential antioxidant, anti-inflammatory and a nephroprotective agent. In spite of this, the possible benefits and protective effects of POL on early diabetic nephropathy are not quite clarified. For the effective clearance from the body besides safe drug delivery, biodegradable nanoparticles have interesting attraction. This work was designed to evaluate the positive effect and possible mechanisms of Polydatin-loaded Chitosan-Nanoparticles (POL-NPs) on early DN in streptozotocin-induced diabetic rats. Followed the induction of diabetes, rats classified into four groups, diabetic control and diabetic rats treated daily and orally with; POL, Polydatin-loaded chitosan-Nanoparticles (POL-NPs), plus normal control rats. Our findings showed that diabetic group presented a significant high level of the blood glucose, blood glycosylated hemoglobin (HbA1c), serum insulin, renal function related parameters, renal Advanced glycation-end products (AGEs) and lipid peroxidation level compared to normal control rats, while serum albumin level and the activities of renal antioxidant enzymes were significantly decreased. Moreover, in the kidney of diabetic rat mRNA expression of nuclear factor-kappa B (NF-κB) and cyclooxygenase-2 (Cox-2) were up-regulated. Besides, increase in serum levels of pro-inflammatory cytokines (TNF-α, IL-6 and IL-18) and decrease in anti-inflammatory cytokine (IL-10). POL and POL-NPs supplementation were significantly attenuate the above-mention results and returned the normal equilibrium between pro- and anti-inflammatory cytokines. In conclusion, POL and POL-NPs have antidiabetic effect, suppresses oxidative stress and mitigates renal inflammation through inhibition of NF-κB in diabetic kidney in early progressive DN.

Dencichine ameliorates renal injury by improving oxidative stress, apoptosis and fibrosis in diabetic rats

OBJECTIVE

To investigate protective efficacies and mechanisms of dencichine on diabetic kidney injury via in vitro and in vivo assays.

METHODS

Effects of dencichine on hydrogen peroxide (H2O2) induced oxidative damage in HK-2 renal cells were assessed by CCK-8 method. Forty streptozotocin (STZ)-induced diabetic rats with kidney injury were randomly divided into negative control group, three doses of dencichine (40, 80 and 160 mg/kg) groups. Blood biochemical and kidney related indexes as well adrenal morphological changes, apoptosis and autophagy related markers of diabetic rats were measured.

RESULTS

Cell viability of HK-2 cells with oxidative damage induced by H2O2 was significantly improved by dencichine with 160 μg/mL for 43.7% and 320 μg/mL for 52.9% compared with control. Moreover, the decreased reactive oxygen species (ROS), and increased intracellular antioxidant enzymes including GPX1, SOD2 and GSH were showed in dencichine groups. In addition, incubation of dencichine in HK-2 cells promoted the increase of p-AMPK, BCL2, LC3, decreased activation of p-mTOR, BAX and Caspase 3. Chronic treatment of dencichine improved the STZ-induced diabetic characteristics of model rats. Further histopathological examination of renal tissues revealed 12-week treatment of dencichine effectively improved the morphology of nephropathy in diabetic rats. Moreover, dencichine also ameliorated excessive oxidation stress, down-regulated renal cell apoptosis and fibrosis related proteins, thereby protected renal tissues in diabetic rats.

CONCLUSION

Dencichine ameliorated STZ-induced kidney injury mainly through inhibiting oxidative stress, reducing renal fibrosis, increasing autophagy, and reducing the renal cell apoptosis related proteins to protect nephrocytes and decrease renal tissue damage.

Cathelicidin-BF attenuate kidney injury through inhibiting oxidative stress, inflammation and fibrosis in streptozotocin-induced diabetic rats

OBJECTIVE

To investigate protective efficacies and mechanisms of Cathelicidin-BF (BF-30) peptide on streptozotocin (STZ)-induced diabetic kidney injury.

METHODS

Effects of BF-30 on hydrogen peroxide induced oxidative damage in HK-2 renal cells were assessed by CCK-8 method. Forty STZ-induced diabetic rats with kidney injury were randomly divided into model control group, BF-30 group at different doses (0.1, 0.3 and 0.9 mg/kg). Blood biochemical and kidney related indexes as well adrenal morphological changes, inflammation related markers of diabetic rats were measured.

RESULTS

Cell viability of HK-2 cells with oxidative damage induced by hydrogen peroxide were significantly improved by BF-30 with 0.8 μg/mL for 56.5% and 1.6 μg/mL for 82.3% compared with control. Moreover, the decreased reactive oxygen species (ROS), and increased intracellular antioxidant enzymes GPX1, SOD2 and GSH were showed in BF-30 treated groups. In addition, co-incubation of BF-30 in HK-2 cells promoted the increase of p-AMPK and LC3, decreased activation of p-mTOR, BAX and Caspase 3. Chronic treatment of BF-30 improved the STZ-induced diabetic characteristics of diabetic kidney disease (DKD) model rats. Further renal histopathological examination revealed 12-week treatment of BF-30 effectively improved the morphology of nephropathy in DKD rats. Moreover, BF-30 also could ameliorate excessive oxidative stress, renal cell apoptosis and fibrosis, thereby protects renal tissues.

CONCLUSION

BF-30 exerted protective effects on STZ-induced kidney injury mainly through the inhibiting oxidative stress in kidney tissue, reducing renal fibrosis, increasing autophagy, and reducing the renal cell apoptosis related proteins to decrease the cell damage and protect nephrocytes.

Tripterygium wilfordii Hook F Treatment for Stage IV Diabetic Nephropathy: Protocol for a Prospective, Randomized Controlled Trial

BACKGROUND

Diabetic nephropathy (DN) is a major cause of chronic kidney disease (CKD). There are no effective treatments to prevent or reverse the progression of DN. A preliminary study showed that Tripterygium glycosides from Tripterygium wilfordii Hook F (TwHF) with valsartan decrease proteinuria in patients with DN.

OBJECTIVES

The objective of the present study is to investigate the efficacy and safety of Tripterygium glycosides from TwHF, a traditional Chinese medicine, for the treatment of DN. Methods and Analysis. This is a prospective, single-center randomized controlled trial. Seventy participants diagnosed with DN were recruited and randomized 1 : 1 to two groups: (1) angiotensin receptor blocker (ARB) combined with TwHF and (2) ARB-only. The treatment period is 48 weeks. The primary endpoint is 24 h proteinuria decreased level (reduction of 30% vs. baseline) after 48 weeks of treatment. The secondary endpoints are (1) all-cause and cardiovascular-related mortality, (2) development of ESRD (serum creatinine > 530.4 μmol/L or estimated glomerular filtration rate (eGFR) < 15 mL/min/1.73 m2), (3) the need for renal replacement therapy, and (4) increased serum creatinine (2-fold higher than the baseline value or ≥442 μmol/L, with confirmation of the initial results after 4 weeks). A health economics analysis will be carried out. Discussion. A meta-analysis of RCTs carried out in patients with stage 4 (Mogensen classification) diabetic CKD showed that TwHF combined with an ARB was more effective than an ARB alone when considering 24 h proteinuria and serum albumin, but with an increase in adverse event (AE) frequency of 8%. This is a prospective clinical trial that may provide information on a safe and effective novel method for the treatment of DN, especially for patients with macroproteinuria. Ethics and Dissemination. The protocol is approved by the ethics committee of Beijing Hospital (2016BJYYEC-059-02). The results will be disseminated through peer-reviewed publications and international conferences. This trial is registered with ChiCTR-IOR-17010623.

The effect of A1 adenosine receptor in diabetic megalin loss with caspase-1/IL18 signaling

PURPOSE

In our previous study, exacerbation of albuminuria was observed in A1 adenosine receptor knockout (A1AR^-/-) mice with diabetic nephropathy (DN), but the mechanism was unclear. Here, we investigated the relationship of megalin loss and albuminuria, to identify the protective effect of A1AR in megalin loss associated albuminuria by inhibiting pyroptosis-related caspase-1/IL-18 signaling of DN.

METHODS

We successfully collected DN patients' samples and built diabetes mice models induced by streptozotocin. Megalin, cubilin, and A1AR expression were detected in kidney tissue samples from DN patients and mice through immunohistochemical and immunofluorescent staining. A1AR, caspase-1, interleukin-18 (IL-18) expression were analyzed using Western blotting in wild-type and A1AR ^-/- mice. Human renal proximal tubular epithelial cells (PTC) were cultured with high glucose to observe the effect of A1AR agonist and antagonist on caspase-1/IL-18 and megalin injury.

RESULTS

The loss of megalin, co-localized with A1AR at PTC, was associated with the level of albuminuria in diabetic patients and mice. The injury of megalin-cubilin was accompanied with the A1AR upregulation (1.30±0.1 vs 0.98±0.2, P=0.042), the caspase-1 (1.33±0.1 vs 1.0±0.2, P=0.036), and IL-18 (1.26±0.2 vs 0.96±0.2, P=0.026) signaling activation in mice with DN. More severe pathological injury, 24 hrs urine albumin excretion (170.8±4.1 μg/d vs 132.0±2.9 μg/d vs 17.9±2.8 μg/d, P<0.001) and megalin-cubilin loss were observed in A1AR ^-/- DN mice with more pronounced caspase-1 (1.52±0.03 vs 1.20±0.01, P=0.017) and IL-18 (1.42±0.02 vs 1.21±0.02, P=0.018) secretion. High glucose could stimulate the secretion of caspase-1 (1.72 times, P≤0.01) and IL-18 (1.64 times, P≤0.01), which was abolished by A1AR agonist and aggravated by A1AR antagonist.

CONCLUSION

A1AR played a protective role in proximal tubular megalin loss associated albuminuria by inhibiting the pyroptosis-related caspase-1/IL-18 signaling in DN.

Abelmoschus esculentus subfractions improved nephropathy with regulating dipeptidyl peptidase-4 and type 1 glucagon-like peptide receptor in type 2 diabetic rats

Abelmoschus esculentus (AE) has been used in traditional medicine to ameliorate hyperglycemia, but its mucilage increased bioassay difficulties. We have obtained a series of AE subfractions. Among them F1 and F2 regulated dipeptidyl peptidase-4 (DPP-4) and type 1 glucagon-like peptide receptor (GLP-1R), the treatment targets for type 2 diabetes. F1, F2 and fraction residues (FR) showed advantage on different aspects, which attenuates insulin resistance and metabolic disorder in vivo, and prevents renal-tubular change in vitro. In the present study, using type 2 diabetes model induced by high fat diet (HFD) and streptozotocin (STZ), we aim to investigate whether AE prevent diabetic nephropathy by regulating the putative markers. The results showed that all the subfractions ameliorated albuminuria and renal hyperfiltration (measured by creatinine clearance rate; CCr) accompanied with diabetes, while F2 acted most promptly and consistently. Histologically AE reduced renal tubular change, fibrosis and fat deposition. F2 and FR exerted significant effects to decrease DPP-4 while increase GLP-1R. Although all the subfractions were effective to reduce oxidative stress, only F2 acted on kidneys specifically. In conclusion, we have demonstrated AE has benefits to regulate DPP-4 and GLP-1R, to reduce oxidative stress and renal fibrosis, with resultant to improve renal function and prevent diabetic renal damage. Taken together, F2 could be more promising to be developed as adjuvant for diabetic nephropathy.

Rapeseed protein-derived antioxidant peptide RAP alleviates renal fibrosis through MAPK/NF-κB signaling pathways in diabetic nephropathy

Introduction

Kidney fibrosis is the main pathologic change in diabetic nephropathy (DN), which is the major cause of end-stage renal disease. Current therapeutic strategies slow down but cannot reverse the progression of renal dysfunction in DN. Plant-derived bioactive peptides in foodstuffs are widely used in many fields because of their potential pharmaceutical and nutraceutical benefits. However, this type of peptide has not yet been studied in renal fibrosis of DN. Previous studies have indicated that the peptide YWDHNNPQIR (named RAP), a natural peptide derived from rapeseed protein, has an antioxidative stress effect. The oxidative stress is believed to be associated with DN. The aim of this study was to evaluate the pharmacologic effects of RAP against renal fibrosis of DN and high glucose (HG)-induced mesangial dysfunction.

Materials and methods

Diabetes was induced by streptozotocin and high-fat diet in C57BL/6 mice and these mice were treated by subcutaneous injection of different doses of RAP (0.1 mg/kg and 0.5 mg/kg, every other day) or PBS for 12 weeks. Later, functional and histopathologic analyses were performed. Parallel experiments verifying the molecular mechanism by which RAP alleviates DN were carried out in HG-induced mesangial cells (MCs).

Results

RAP improved the renal function indices, including 24-h albuminuria, triglyceride, serum creatinine, and blood urea nitrogen levels, but did not lower blood glucose levels in DN mice. RAP also simultaneously attenuated extracellular matrix accumulation in DN mice and HG-induced MCs. Furthermore, RAP reduced HG-induced cell proliferation, but it showed no toxicity in MCs. Additionally, RAP inhibited the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signaling pathways.

Conclusion

RAP can attenuate fibrosis in vivo and in vitro by antagonizing the MAPK and NF-κB pathways.

Integrated Treatment of Prostaglandin E1 and Angiotensin-Converting Enzyme Inhibitor in Diabetic Kidney Disease Rats: Possible Role of Antiapoptosis in Renal Tubular Epithelial Cells

To investigate the therapeutic mechanisms underlying prostaglandin E1 (PGE1) and angiotensin-converting enzyme inhibitor (ACEI) on reducing urinary protein in diabetic kidney disease (DKD). DKD rats were established and randomly divided into four groups: PGE1 (10 μg/kg/day) (P group), ACEI (10 mg/kg/day) (A group), combination of PGE1 with ACEI treatment (P + A group), and saline treatment group (DKD group). Untreated rats were used as normal control (N group). Urinary albumin, endothelin-1 (ET-1), angiotensin II (AngII), TUNEL assay, Masson's trichrome staining, and immunohistochemistry staining for CD68 were evaluated in all groups. Ten days after treatment, urinary albumin was significantly decreased in the P and P + A groups (p < 0.01 vs. the DKD group). At the end of 8 weeks, the albumin was still significantly reduced in the P + A group (p < 0.05 vs. the A group). ET-1 and AngII were also significantly decreased in three treatment groups (p < 0.01 vs. the DKD group), especially in the P + A group. Few cells underwent apoptosis in glomerular regions in DKD rats, while amounts of apoptotic cells were seen in tubules regions. Further, apoptosis and the areas of fibrosis in tubulointerstitial were both decreased most in the P + A group compared with the DKD group. Apoptosis of renal tubular epithelial cells may participate in the development and progression of DKD in rats. Combination of PGE1 with AGEI remarkably protects renal function compared with PGE1 or ACEI monotherapy. The potential therapeutic mechanisms of PGE1 and AGEI might be via multiple targets and, at least in part, through inhibiting the apoptosis of renal tubular epithelial cells.

Tanshinone IIA attenuates renal damage in STZ-induced diabetic rats via inhibiting oxidative stress and inflammation

Oxidative stress and inflammation have been demonstrated to be involved in the onset and promotion of diabetic nephropathy (DN).Tanshinone IIA (Tan) possesses both antioxidant and anti-inflammatory properties. Here, the aim of the present study was to explore whether Tan could attenuate renal damage in the rats with streptozotocin (STZ)-induced diabetes and its potential mechanisms. Tan was gavaged to STZ-induced diabetic rats at the dose of 10mg/kg once a day for 12 weeks. Tan treatment significantly attenuated albuminuria and renal histopathology in diabetic rats. Besides, Tan treatment also effectively inhibited oxidative stress and inflammatory reaction in the kidneys of diabetic rats. Our study provided evidence that the protective effect of Tan on diabetes-induced renal injury is associated with inhibition of oxidative stress and inflammation. Tan may be a potential candidate for the treatment of DN.

Renoprotective and antioxidative effects of methanolic Paederia foetida leaf extract on experimental diabetic nephropathy in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Paederia foetida Linn. (Family: Rubiaceae) is widely used as a natural remedy for diabetes mellitus by the Nepali and Lepcha tribes of Sikkim and Darjeeling Himalayan region. The plant is administered to a diabetic individual in the form of leaf infusion for 2-3 weeks. Therefore, we investigated the effects of methanolic leaf extract of Paederia foetida (MEPF) on alloxan (ALX) induced diabetic renal oxidative stress and NF-kB dependent renoinflammatory events in rat. Method Effects of MEPF on blood glucose, glomerular filtration rate (GFR), serum and oxidative stress markers were evaluated in ALX induced diabetic wistar rats. Enzyme linked immunosorbent assay (ELISA) was carried out to estimate serum IL-6, IL-1β, TNF-α and renal tissue NF-kB p65 levels. MEPF treatment was given to the diabetic rats at a dose of 250 and 500mg/kg body weight (b.w.).

RESULTS & DISCUSSION

MEPF treatment significantly reduced hyperglycaemia, serum creatinine, blood urea nitrogen (BUN), bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglycerides (TRIGs), and total cholesterol (TCHOL) levels in the diabetic rats, whereas it significantly restored GFR and serum albumin level. The activity of enzymatic and non-enzymatic antioxidant machineries was remarkably augmented by MEPF treatment. Likewise, it also significantly lowered lipid peroxidation which was evidenced by decreased concentration of thiobarbituric reactive substances (malondialdehyde, MDA) in the renal tissue of treated diabetic groups. Moreover, MEPF treated animals exhibited low serum concentrations of IL-6, IL-1β and TNF-α compared to the diabetic control rats. It showed a dose dependent inhibition of NF-kB activation in the diabetic kidney, but the effects were more prominent at a dose of 500mg/kg. Histopathological examinations also confirmed its nephroprotective action during diabetes.

CONCLUSION

MEPF treatment mitigates oxidative stress and suppresses renal inflammation via inhibition of NF-kB in diabetic kidney in early progressive diabetic nephropathy.

Abelmoschus esculentus fractions potently inhibited the pathogenic targets associated with diabetic renal epithelial to mesenchymal transition

Although Abelmoschus esculentus (AE) is known for anti-hyperglycemia, few reports have addressed its target. Our recent studies have focused on diabetic renal epithelial to mesenchymal transition (EMT), which plays a critical role in fibrosis that accompanies increasing vimentin and suggested signals DPP-4/AT-1/TGF-β1. This study aimed to investigate whether AE is useful for preventing diabetic renal EMT. We used a succession of extractions and obtained the corresponding fractions F1-F5, each with its own individual properties: F1 inhibits high glucose-stimulated vimentin, AT-1, TGF-β1, and DPP-4, and recovers E-cadherin in tubular cells; F2 decreases high glucose-induced vimentin, AT-1 and DPP-4; F3-F5 do not reduce the expression of vimentin. Chemical analysis revealed that F1 is rich of flavonoid glycosides especially quercetin glucosides, and pentacyclic triterpene ester. F2 contains a large amount of carbohydrates and polysaccharides composed of uronic acid, galactose, glucose, myo-inositol etc. In conclusion, AE has the potential to serve as an adjuvant for diabetic nephropathy, with F1 and F2 especially deserving further investigation and development.

HLA class II alleles and risk for peripheral neuropathy in type 2 diabetes patients

The potential impact of human leukocyte antigen (HLA) genotype variations on development of diabetic peripheral neuropathy (DPN) is not well determined. This study aimed to identify the association of HLA class II alleles with DPN in type 2 diabetes (T2D) patients. Totally 106 T2D patients, 49 with DPN and 57 without DPN, and 100 ethnic-matched healthy controls were analyzed. Both groups of the patients were matched based on sex, age, body mass index (BMI) and duration of T2D. Polyneuropathy was diagnosed using electrodiagnostic methods. HLA-DRB1 and DQB1 genotyping was performed in all subjects by the polymerase chain reaction with sequence-specific primers (PCR-SSP) method. T2D patients with DPN showed higher frequencies of HLA-DRB1*10 and DRB1*12 alleles compared to control group (P = 0.04). HLA-DQB1*02 allele and HLA-DRB1*07-DQB1*02 haplotype were associated with a decreased risk for developing DPN in T2D patients (P = 0.02 and P = 0.05 respectively). Also, patients with severe neuropathy showed higher frequencies of DRB1*07 (P = 0.003) and DQB1*02 (P = 0.02) alleles than those with mild-to-moderate form of neuropathy. The distribution of DRB1 and DQB1 alleles and haplotypes were not statistically different between all patients and healthy controls. Our findings implicate a possible protective role of HLA-DQB1*02 allele and HLA-DRB1*07-DQB1*02 haplotype against development of peripheral neuropathy in T2D patients. Therefore, variations in HLA genotypes might be used as genetic markers for prediction and potentially management of neuropathy in T2D patients.

Insulin deficiency induces rat renal mesangial cell dysfunction via activation of IGF-1/IGF-1R pathway

AIM

Diabetic nephropathy is one of the major complications of diabetes and the major cause of end-stage renal disease. In this study we investigated the insulin deficiency (ID) induced changes in renal mesangial cells (MCs) and in the kidney of STZ-induced diabetic rats.

METHODS

Cultured rat renal MCs were incubated in ID media. Cell proliferation was analyzed using BrdU incorporation assay. The expression of insulin receptor (IR), insulin-like growth factor-1 receptor (IGF-1R), phosphorylated IGF-1R, fibronectin, and collagen IV was determined with Western blot analysis. STZ-induced diabetic rats were treated with an IGF-1R antagonist picropodophyllin (PPP, 20 mg·kg(-1)·d(-1), po) for 8 weeks. After the rats were euthanized, plasma and kidneys were collected. IGF-1 levels in renal cortex were measured with RT-PCR or ELISA. The morphological changes in the kidneys were also examined.

RESULTS

Incubation in ID media significantly increased cell proliferation, the synthesis of fibronectin and collagen IV, and the expression of IGF-1 and IGF-1R and phosphorylated IGF-1R in renal MCs. Pretreatment of the cells with PPP (50 nmol/L) blocked ID-induced increases in cell proliferation and the synthesis of fibronectin and collagen IV; knockdown of IGF-1R showed a similar effect as PPP did. In contrast, treatment of the cells with IGF-1 (50 ng/mL) exacerbated ID-induced increases in cell proliferation. In the kidneys of diabetic rats, the expression of IGF-1, IGF-1R and phosphorylated IGF-1R were significantly elevated. Treatment of diabetic rats with PPP did not lower the blood glucose levels, but significantly suppressed the expression of TGF-β, fibronectin and collagen IV in the kidneys, the plasma levels of urinary nitrogen and creatinine, and the urinary protein excretion.

CONCLUSION

Insulin deficiency increases the expression of IGF-1 and IGF-1R in renal MCs and the kidney of diabetic rats, which contributes to the development of diabetic nephropathy.

Oxidative Stress in Diabetic Nephropathy with Early Chronic Kidney Disease

The increase in the prevalence of diabetes mellitus (DM) and the secondary kidney damage produces diabetic nephropathy (DN). Early nephropathy is defined as the presence of microalbuminuria (30-300 mg/day), including normal glomerular filtration rate (GFR) or a mildly decreased GFR (60-89 mL/min/1.73 m(2)), with or without overt nephropathy. The earliest change caused by DN is hyperfiltration with proteinuria. The acceptable excretion rate of albumin in urine is <30 mg/day. Albuminuria represents the excretion of >300 mg/day. Chronic kidney disease (CKD) is characterized by abnormalities in renal function that persist for >3 months with health implications. Alterations in the redox state in DN are caused by the persistent state of hyperglycemia and the increase in advanced glycation end products (AGEs) with ability to affect the renin-angiotensin system and the transforming growth factor-beta (TGF-β), producing chronic inflammation and glomerular and tubular hypertrophy and favoring the appearance of oxidative stress. In DN imbalance between prooxidant/antioxidant processes exists with an increase in reactive oxygen species (ROS). The overproduction of ROS diminishes expression of the antioxidant enzymes (manganese superoxide dismutase, glutathione peroxidase, and catalase). The early detection of CKD secondary to DN and the timely identification of patients would permit decreasing its impact on health.

Hibiscus sabdariffa polyphenols prevent palmitate-induced renal epithelial mesenchymal transition by alleviating dipeptidyl peptidase-4-mediated insulin resistance

Diabetic nephropathy has a significant socioeconomic impact, but its mechanism is unclear and needs to be examined.

Synthesis and preliminary therapeutic evaluation of copper nanoparticles against diabetes mellitus and -induced micro- (renal) and macro-vascular (vascular endothelial and cardiovascular) abnormalities in rats

Current study synthesized and investigated the effect of low-dose copper nanoparticles (CuNPs) against diabetes mellitus and -induced experimental micro- (nephropathy) and macro-vascular (cardio and endothelium) complications.

Reactive oxygen species: friend or foe?

It is a need to define the line between pathological and physiological functions of reactive oxygen species (ROS) in order to understand their beneficial role over their injurious consequences.

Fluorofenidone offers improved renoprotection at early interventions during the course of diabetic nephropathy in db/db mice via multiple pathways

Diabetic nephropathy (DN) remains the leading cause of end-stage renal disease (ESRD), a situation that is in part attributable to the lack of effective treatments. Fluorofenidone is a newly developed reagent with anti-fibrotic activity. While fluorofenidone was previously demonstrated to possess renoprotection from DN pathogenesis in db/db mice, the protective process and its underlying mechanisms have not been well studied. To characterize fluorofenidone-derived renoprotection, we treated 5, 8, or 12-week old db/db mice with daily doses of placebo, fluorofenidone, or losartan until 24 weeks of age; the time at which diabetes and DN were fully developed in placebo-treated animals. In comparison to db/db mice receiving fluorofenidone at 12-weeks old, those treated at 5-weeks had less glomerular expansion and better preservation of renal functions, judged by serum creatinine levels, albumin to creatinine ratio, and urinary albumin excretion (mg/24 hours). These benefits of early treatment were associated with significant reductions of multiple DN-promoting events, such as decreased expression of TGF-β1 and the p22^phox subunit of NADPH oxidase as well as downregulated activation of protein kinase C-zeta (ζ), ERK and AKT. This improvement in renoprotection following early interventions is not a unique property of DN pathogenesis, as losartan does not apparently offer the same benefits and is not more renoprotective than fluorofenidone. Additionally, the enhanced renoprotection provided by fluorofenidone did not affect the diabetic process, as it did not alter serum levels of glycated serum proteins, glucose, triglyceride or cholesterol. Collectively, we provide evidence that fluorofenidone offers improved renoprotection at early stages of DN pathogenesis.

Hibiscus sabdariffa polyphenols alleviate insulin resistance and renal epithelial to mesenchymal transition: a novel action mechanism mediated by type 4 dipeptidyl peptidase

The epithelial to mesenchymal transition (EMT) is important in renal fibrosis. Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1 (S307)) is a hallmark of insulin resistance. We report that polyphenol extracts of Hibiscus sabdariffa (HPE) ameliorate diabetic nephropathy and EMT. Recently it has been observed that type 4 dipeptidyl peptidase (DPP-4) inhibitor linagliptin is effective for treating type 2 diabetes and albuminuria. We investigated if DPP-4 and insulin resistance are involved in renal EMT and explored the role of HPE. In high glucose-stimulated tubular cells, HPE, like linagliptin, inhibited DPP-4 activation, thereby regulating vimentin (EMT marker) and IRS-1 (S307). IRS-1 knockdown revealed its essential role in mediating downstream EMT. In type 2 diabetic rats, pIRS-1 (S307) abundantly surrounds the tubular region, with increased vimentin in kidney. Both the expressions were reduced by HPE. In conclusion, HPE exerts effects similar to those of linagliptin, which improves insulin resistance and EMT, and could be an adjuvant to prevent diabetic nephropathy.

Fenofibrate and dipyridamole treatments in low-doses either alone or in combination blunted the development of nephropathy in diabetic rats

Low-doses of fenofibrate and dipyridamole have pleiotropic renoprotective actions in diabetic rats. This study investigated their combined effect relative to their individual treatments and lisinopril in rats with diabetic nephropathy. Streptozotocin (55mg/kg, i.p., once)-administered diabetic rats were allowed for 10 weeks to develop nephropathy. Diabetic rats after 10 weeks developed nephropathy with discernible renal structural and functional changes as assessed in terms of increase in kidney weight to body weight ratio (KW/BW), and elevations of serum creatinine, urea and uric acid, which accompanied with elevated serum triglycerides and decreased high-density lipoproteins. Hematoxylin-eosin, periodic acid Schiff and Masson trichrome staining confirmed renal pathological changes in diabetic rats that included glomerular capsular wall distortion, mesangial cell expansion, glomerular microvascular condensation, tubular damage and degeneration and fibrosis. Low-dose fenofibrate (30mg/kg, p.o., 4 weeks) and low-dose dipyridamole (20mg/kg, p.o., 4 weeks) treatment either alone or in combination considerably reduced renal structural and functional abnormalities in diabetic rats, but without affecting the elevated glucose level. Fenofibrate, but not dipyridamole, significantly prevented the lipid alteration and importantly the uric acid elevation in diabetic rats. Lisinopril (5mg/kg, p.o., 4 weeks, reference compound), prevented the hyperglycemia, lipid alteration and development of diabetic nephropathy. Lipid alteration and uric acid elevation, besides hyperglycemia, could play key roles in the development of nephropathy. Low-doses of fenofibrate and dipyridamole treatment either alone or in combination markedly prevented the diabetes-induced nephropathy. Their combination was as effective as to their individual treatment, but not superior in preventing the development of diabetic nephropathy.

The role of aldosterone antagonism agents in diabetic kidney disease

BACKGROUND

Diabetic kidney disease is a common consequence of the development of diabetes. In the United Kingdom 18-30% of chronic kidney disease cases and 44% of end-stage renal disease cases in the United States have been attributed to complications of diabetic kidney disease. Angiotensin blockade using angiotensin converting enzyme inhibitors or angiotensin receptor blockers is the standard for slowing the progression of diabetic kidney disease. Evidence suggests that aldosterone antagonism added to standard therapy may be beneficial.

AIM OF REVIEW

This paper aims to explore the pathophysiological contribution of aldosterone in diabetic kidney disease and review available literature for aldosterone antagonism through mineralocorticoid receptor blockade.

METHODS

A comprehensive literature search was conducted. Results were analysed and summarised.

RESULTS

Nine trials evaluating a total of 535 patients with diabetic kidney disease were identified that evaluated the use of aldosterone antagonists for reducing the signs of diabetic kidney disease. All trials demonstrated a marked decrease in urinary protein excretion when compared to, or added to angiotensin converting enzyme inhibition or angiotensin receptor blockade. The most commonly reported side effect in all of the trials was hyperkalaemia, which occurred in 6.1% of all patients evaluated. Aldosterone antagonists were generally well tolerated in the evaluated patient populations.

CONCLUSION

Aldosterone antagonism may represent a safe and effective complimentary therapy to the use of angiotensin converting enzyme inhibition, or angiotensin receptor blockade, for slowing the progression of diabetic kidney disease.

A century old renin-angiotensin system still grows with endless possibilities: AT1 receptor signaling cascades in cardiovascular physiopathology

Ang II, the primary effector pleiotropic hormone of the renin-angiotensin system (RAS) cascade, mediates physiological control of blood pressure and electrolyte balance through its action on vascular tone, aldosterone secretion, renal sodium absorption, water intake, sympathetic activity and vasopressin release. It affects the function of most of the organs far beyond blood pressure control including heart, blood vessels, kidney and brain, thus, causing both beneficial and deleterious effects. However, the protective axis of the RAS composed of ACE2, Ang (1-7), alamandine, and Mas and MargD receptors might oppose some harmful effects of Ang II and might promote beneficial cardiovascular effects. Newly identified RAS family peptides, Ang A and angioprotectin, further extend the complexities in understanding the cardiovascular physiopathology of RAS. Most of the diverse actions of Ang II are mediated by AT1 receptors, which couple to classical Gq/11 protein and activate multiple downstream signals, including PKC, ERK1/2, Raf, tyrosine kinases, receptor tyrosine kinases (EGFR, PDGF, insulin receptor), nuclear factor κB and reactive oxygen species (ROS). Receptor activation via G12/13 stimulates Rho-kinase, which causes vascular contraction and hypertrophy. The AT1 receptor activation also stimulates G protein-independent signaling pathways such as β-arrestin-mediated MAPK activation and Src-JAK/STAT. AT1 receptor-mediated activation of NADPH oxidase releases ROS, resulting in the activation of pro-inflammatory transcription factors and stimulation of small G proteins such as Ras, Rac and RhoA. The components of the RAS and the major Ang II-induced signaling cascades of AT1 receptors are reviewed.

Fenofibrate and the kidney: an overview

BACKGROUND

Fenofibrate has been used for the management of atherogenic dyslipidaemia for many years. Reports of fenofibrate-associated increases in serum creatinine (SCr) levels raised concerns regarding deleterious effects on renal function.

DESIGN

In this narrative review, we discuss available literature on the effect of fenofibrate on the kidney.

RESULTS

Most clinical studies showed a rapid (within weeks) raising effect of fenofibrate on SCr levels. This was often accompanied by declined estimated glomerular filtration rate. Risk predictors of this adverse effect might include increased age, impaired renal function and high-dose treatment. Also, the concomitant use of medications affecting renal hemodynamics (e.g. angiotensin-converting enzyme-inhibitors (ACEi) and angiotensin receptor blockers) may predispose to fenofibrate-associated increased SCr levels. Interestingly, SCr increases by fenofibrate were transient and reversible even without treatment discontinuation. Furthermore, fenofibrate was associated with a slower progression of renal function impairment and albuminuria in a long-term basis. Also, fenofibrate might be protective against pathological changes in diabetic nephropathy and hypertensive glomerulosclerosis. In this context, it is uncertain whether fenofibrate-associated increase in SCr levels mirrors true renal function deterioration. Several theories have been expressed. The most dominant one involved the inhibition of renal vasodilatory prostaglandins reducing renal plasma flow and glomerular pressure. Increased creatinine secretion or reduced creatinine clearance by fenofibrate was also suggested. These hypotheses should be settled by further studies.

CONCLUSIONS

Fenofibrate may not be a nephrotoxic drug. However, a close monitoring of SCr levels is relevant especially in high-risk patients. Increases in SCr levels ≥30% can impose treatment discontinuation.

Functional implications of microRNA-215 in TGF-β1-induced phenotypic transition of mesangial cells by targeting CTNNBIP1

Mesangial cell (MC) phenotypic transition is crucial for the progression of diabetic nephropathy. A major stimulus mediating high glucose-induced MC phenotypic transition is TGF-β1. Our current study focuses on microRNA-215 (miR-215) and investigates its role in TGF-β1-mediated MC phenotypic transition. Using real-time quantitative PCR (qRT-PCR) and northern blotting, we determined that the miR-192/215 family is dramatically upregulated under diabetic conditions both in vitro and in vivo. Gain- and loss-of-function approaches demonstrated that miR-215 inhibition significantly inhibited TGF-β1-induced mouse mesangial cell (MMC) phenotypic transition, whereas miR-215 upregulation promoted MMC phenotypic transition. Interestingly, these changes were not detected in cells that were treated with TGF-β1 and miR-192 mimics or inhibitors. These results suggest that miR-215 participates in TGF-β1-induced MMC phenotypic transition. Luciferase reporter assays were used to identify whether catenin-beta interacting protein 1 (CTNNBIP1) is a direct target of miR-215, which was predicted by bioinformatic analysis. Mechanistic studies revealed that CTNNBIP1 suppresses Wnt/β-catenin signaling and that miR-215 promotes β-catenin activation and upregulates α-SMA and fibronectin expression in TGF-β1-treated MMCs by targeting CTNNBIP1. In addition, in vivo miR-215 silencing with a specific antagomir significantly increased CTNNBIP1 protein expression, resulting in reduced β-catenin activity and decreased α-SMA and fibronectin expression in db/db mouse kidney glomeruli. Taken together, our findings indicate that miR-215 plays an essential role in MC phenotypic transition by regulating the CTNNBIP1/β-catenin pathway, which is related to the pathogenesis of diabetic nephropathy.

Thioredoxin-interacting protein mediates high glucose-induced reactive oxygen species generation by mitochondria and the NADPH oxidase, Nox4, in mesangial cells

Thioredoxin-interacting protein (TxNIP) is up-regulated by high glucose and is associated with oxidative stress. It has been implicated in hyperglycemia-induced β-cell dysfunction and apoptosis. As high glucose and oxidative stress mediate diabetic nephropathy (DN), the contribution of TxNIP was investigated in renal mesangial cell reactive oxygen species (ROS) generation and collagen synthesis. To determine the role of TxNIP, mouse mesangial cells (MC) cultured from wild-type C3H and TxNIP-deficient Hcb-19 mice were incubated in HG. Confocal microscopy was used to measure total and mitochondrial ROS production (DCF and MitoSOX) and collagen IV. Trx and NADPH oxidase activities were assayed and NADPH oxidase isoforms, Nox2 and Nox4, and antioxidant enzymes were determined by immunoblotting. C3H MC exposed to HG elicited a significant increase in cellular and mitochondrial ROS as well as Nox4 protein expression and NADPH oxidase activation, whereas Hcb-19 MC showed no response. Trx activity was attenuated by HG only in C3H MC. These defects in Hcb-19 MC were not due to increased antioxidant enzymes or scavenging of ROS, but associated with decreased ROS generation. Adenovirus-mediated overexpression of TxNIP in Hcb-19 MC and TxNIP knockdown with siRNA in C3H confirmed the specific role of TxNIP. Collagen IV accumulation in HG was markedly reduced in Hcb-19 cells. TxNIP is a critical component of the HG-ROS signaling pathway, required for the induction of mitochondrial and total cell ROS and the NADPH oxidase isoform, Nox4. TxNIP is a potential target to prevent DN.

Association of Obesity and Kidney Function Decline among Non-Diabetic Adults with eGFR > 60 ml/min/1.73m2: Results from the Multi-Ethnic Study of Atherosclerosis (MESA)

Background

Obesity is associated with higher end-stage renal disease incidence, but associations with earlier forms of kidney disease remain incompletely characterized.

Methods

We studied the association of body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) with rapid kidney function decline and incident chronic kidney disease in 4573 non-diabetic adults with eGFR ≥ 60 ml/min/1.73m² at baseline from longitudinal Multi-Ethnic Study of Atherosclerosis cohort. Kidney function was estimated by creatinine and cystatin C. Multivariate analysis was adjusted for age, race, baseline eGFR, and hypertension.

Results

Mean age was 60 years old, BMI 28 kg/m², baseline eGFR_Cr 82 and eGFR_Cys 95 ml/min/1.73m². Over 5 years of follow up, 25% experienced rapid decline in renal function by eGFR_Cr and 22% by eGFR_Cys. Incident chronic kidney disease (CKD) developed in 3.3% by eGFR_Cys, 11% by eGFR_Cr, and 2.4% by both makers. Compared to persons with BMI < 25, overweight (BMI 25 – 30) persons had the lowest risk of rapid decline by eGFR_Cr (0.84, 0.71 – 0.99). In contrast, higher BMI categories were associated with stepwise higher odds of rapid decline by eGFR_Cys, but remained significant only when BMI ≥ 35 kg/m² (1.87, 1.41 – 2.48). Associations of BMI with incident CKD were insignificant after adjustment. Large WC and WHR were associated with increased risk of rapid decline only by eGFR_Cys, and of incident CKD only when defined by both filtration markers.

Conclusions

Obesity may be a risk factor for kidney function decline, but associations vary by filtration marker used.

Differential effects of low-dose fenofibrate treatment in diabetic rats with early onset nephropathy and established nephropathy

We have previously shown that low-dose fenofibrate treatment has an ability to prevent diabetes-induced nephropathy in rats. We investigated here the comparative pre- and post-treatment effects of low-dose fenofibrate (30 mg/kg/day p.o.) in diabetes-induced onset of nephropathy. Rats were made diabetics by single administration of streptozotocin (STZ, 55 mg/kg i.p.). The development of diabetic nephropathy was assessed biochemically and histologically. Moreover, lipid profile and renal oxidative stress were assessed. Diabetic rats after 8 weeks of STZ-administration developed apparent nephropathy by elevating serum creatinine, blood urea nitrogen and microproteinuria, and inducing glomerular-capsular wall distortion, mesangial expansion and tubular damage and renal oxidative stress. Fenofibrate (30 mg/kg/day p.o., 4 weeks) pretreatment (4 weeks after STZ-administration) markedly prevented diabetes-induced onset of diabetic nephropathy, while the fenofibrate (30 mg/kg/day p.o., 4 weeks) post-treatment (8 weeks after STZ-administration) was less-effective. However, both pre-and post fenofibrate treatments were effective in preventing diabetes-induced renal oxidative stress and lipid alteration in diabetic rats though the pretreatment was slightly more effective. Conversely, both pre-and post fenofibrate treatments did not alter elevated glucose levels in diabetic rats. It may be concluded that diabetes-induced oxidative stress and lipid alteration, in addition to a marked glucose elevation, play a detrimental role in the onset of nephropathy in diabetic rats. The pretreatment with low-dose fenofibrate might be a potential therapeutic approach in preventing the onset of nephropathy in diabetic subjects under the risk of renal disease induction. However, low-dose fenofibrate treatment might not be effective in treating the established nephropathy in diabetic subjects.

Global renal gene expression profiling analysis in B2-kinin receptor null mice: impact of diabetes

Diabetic nephropathy (DN), the leading cause of end-stage renal failure, is clinically manifested by albuminuria and a progressive decline in glomerular filtration rate. The risk factors and mechanisms that contribute to the development and progression of DN are still incompletely defined. To address the involvement of bradykinin B₂-receptors (B₂R) in DN, we used a genome wide approach to study the effects of diabetes on differential renal gene expression profile in wild type and B₂R knockout (B₂R^−/−) mice. Diabetes was induced with streptozotocin and plasma glucose levels and albumin excretion rate (AER) were measured at predetermined times throughout the 23 week study period. Longitudinal analysis of AER indicated that diabetic B₂R^−/−D null mice had a significantly decreased AER levels compared to wild type B₂R^+/+D mice (P = 0.0005). Results from the global microarray study comparing gene expression profiles among four groups of mice respectively: (B₂R^+/+C, B₂R^+/+D, B₂R^−/−C and B₂R^−/−D) highlighted the role of several altered pathological pathways in response to disruption of B₂R and to the diabetic state that included: endothelial injury, oxidative stress, insulin and lipid metabolism and inflammatory process with a marked alteration in the pro-apoptotic genes. The findings of the present study provide a global genomics view of biomarkers that highlight the mechanisms and putative pathways involved in DN.

PRKCB is associated with calcineurin inhibitor-induced renal dysfunction in heart transplant recipients

OBJECTIVES

Single nucleotide polymorphisms (SNPs) in the transforming growth factor-β1 gene (TGFB1) have been inconsistently associated with calcineurin inhibitor (CNI)-induced renal dysfunction following cardiac transplantation. The impact of genetic variants related to the renin-angiotensin-aldosterone system (RAAS) and natriuretic peptides, which are implicated in CNI nephrotoxicity, is unknown. The primary objective of this study was to validate the association between two common variants in TGFB1 (rs1800470, rs1800471) and postcardiac transplant renal function. The secondary objective was to investigate the effect of candidate genes related to the RAAS, natriuretic peptides, and other elements involved in the intracellular signaling of these pathways.

METHODS

We conducted a retrospective cohort study of 158 heart transplant recipients treated with CNIs, and evaluated the association between select SNPs and the estimated glomerular filtration rate as calculated by the Modification of Diet in Renal Disease simplified formula. A total of 273 SNPs distributed in 44 genes were tested.

RESULTS

No association was observed between TGFB1 variants and renal function. One polymorphism in the protein kinase C-β gene (PRKCB; rs11074606), which is implicated in the RAAS intracellular signaling, was significantly associated with post-transplant estimated glomerular filtration rate after adjusting for possible confounders (P=0.00049). This marker is in linkage disequilibrium with two variants located in putative regulatory regions of the gene (rs2283541, rs1013316).

CONCLUSION

Our results suggest that PRKCB may be a potential predictor of CNI-induced nephrotoxicity in heart transplant recipients, and could therefore be a promising candidate to identify patients who are most susceptible to this adverse drug reaction.

Fish oil and vascular endothelial protection: bench to bedside

Fish oil is recommended for the management of hypertriglyceridemia and to prevent secondary cardiovascular disorders. Fish oil is a major source of ω-3-polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Clinical studies suggest that fish oil not only prevents the incidence of detrimental cardiovascular events, but also lowers the cardiovascular mortality rate. In addition to a classic lipid-lowering action, ω-3-PUFAs in fish oil could regulate blood pressure and enhance vascular integrity and compliance. Additionally, ω-3-PUFAs have the ability to protect vascular endothelial cells by decreasing oxidative stress, halting atherosclerotic events, and preventing vascular inflammatory and adhesion cascades. Intriguingly, recent studies have demonstrated that ω-3-PUFAs improve the function of vascular endothelium by enhancing the generation and bioavailability of endothelium-derived relaxing factor (nitric oxide) through upregulation and activation of endothelial nitric oxide synthase (eNOS). This certainly opens up a new area of research identifying potential mechanisms influencing fish oil-mediated functional regulatory action on vascular endothelium. We address in this review the potential of fish oil to prevent vascular endothelial dysfunction and associated cardiovascular disorders. Moreover, the mechanisms pertaining to fish oil-mediated eNOS activation and nitric oxide generation in improving endothelial function are delineated. We finally suggest the importance of further studies to determine the dose adjustment of fish oil with an optimal ratio of EPA and DHA for achieving consistent cardiovascular protection.

Are PPAR alpha agonists a rational therapeutic strategy for preventing abnormalities of the diabetic kidney?

The uncontrolled diabetes mellitus may result in the induction of diabetic nephropathy, one of the detrimental microvascular complications of diabetes mellitus. Diabetic nephropathy is associated with glomerular hypertrophy, glomerulosclerosis, tubulointerstitial fibrosis, mesangial cell expansion, followed by albuminuria and reduction in glomerular filtration rate. Indeed, no promising therapeutic options are available in the present clinical scenario to manage efficiently the diabetic nephropathy. Nevertheless, angiotensin converting enzyme inhibitors and angiotensin-II-AT(1) receptor blockers are currently employed to improve structural and functional status of the diabetic kidney. These interventions, however, are not optimal in improving overall outcomes of diabetic nephropathy. Hence, there is a continuing need of developing promising therapeutic interventions to manage this insidious condition adequately. Recent bench and clinical studies strongly suggest the potentials of peroxisome proliferator-activated receptor alpha (PPARα) agonists in the management of diabetic nephropathy by keeping the view that renal lipid accumulation-induced lipotoxicity is one of risk factors for nephropathy during chronic diabetes mellitus. As inflammation, oxidative stress and dyslipidemia are common consequences of renal dysfunction, PPARα agonists could serve as promising therapeutic agents for controlling the progression of diabetic nephropathy. In fact, fenofibrate, a hypolipidemic agent acts as a PPARα agonist, reduced renal lipotoxicity, inflammation, fibrosis and oxidative stress, and subsequently prevented the symptoms of diabetic nephropathy. However, fenofibrate has been shown to cause renal dysfunction in established renal disorders. The present review addressed the rationale of employing PPARα agonists in the management of diabetic nephropathy.

Diabetic nephropathy amelioration by a low-dose sitagliptin in an animal model of type 2 diabetes (Zucker diabetic fatty rat)

This study was performed to assess the effect of chronic low-dose sitagliptin, a dipeptidyl peptidase 4 inhibitor, on metabolic profile and on renal lesions aggravation in a rat model of type-2 diabetic nephropathy, the Zucker diabetic fatty (ZDF) rat. Diabetic and obese ZDF (fa/fa) rats and their controls ZDF (+/+) were treated for 6 weeks with vehicle (control) or sitagliptin (10 mg/kg/bw). Blood/serum glucose, HbA1c, insulin, Total-c, TGs, urea, and creatinine were assessed, as well as kidney glomerular and tubulointerstitial lesions (interstitial fibrosis/tubular atrophy), using a semiquantitative rating from 0 (absent/normal) to 3 (severe and extensive damage). Vascular lesions were scored from 0-2. Sitagliptin in the diabetic rats promoted an amelioration of glycemia, HbA1c, Total-c, and TGs, accompanied by a partial prevention of insulinopenia. Furthermore, together with urea increment prevention, renal lesions were ameliorated in the diabetic rats, including glomerular, tubulointerstitial, and vascular lesions, accompanied by reduced lipid peroxidation. In conclusion, chronic low-dose sitagliptin treatment was able to ameliorate diabetic nephropathy, which might represent a key step forward in the management of T2DM and this serious complication.

Nuclear transport: a switch for the oxidative stress-signaling circuit?

Imbalances in the formation and clearance of reactive oxygen species (ROS) can lead to oxidative stress and subsequent changes that affect all aspects of physiology. To limit and repair the damage generated by ROS, cells have developed a multitude of responses. A hallmark of these responses is the activation of signaling pathways that modulate the function of downstream targets in different cellular locations. To this end, critical steps of the stress response that occur in the nucleus and cytoplasm have to be coordinated, which makes the proper communication between both compartments mandatory. Here, we discuss the interdependence of ROS-mediated signaling and the transport of macromolecules across the nuclear envelope. We highlight examples of oxidant-dependent nuclear trafficking and describe the impact of oxidative stress on the transport apparatus. Our paper concludes by proposing a cellular circuit of ROS-induced signaling, nuclear transport and repair.

The impact of 5,10-methenyltetrahydrofolate synthetase polymorphism on diabetic nephropathy in the Taiwanese population

Genome-wide association studies provide information implicating 5,10-methenyltetrahydrofolate synthetase (MTHFS) as a candidate gene for renal disease. In the Atherosclerosis Risk in Communities study, the intronic single-nucleotide polymorphism rs6495446 in the gene MTHFS confirmed the association between this gene and renal disease among Caucasian participants. We replicated this genetic association in a Taiwanese population with diabetic nephropathy (DN). A total of 358 Taiwanese patients with type 2 diabetes (T2D) were recruited. The case group comprised 180 T2D patients with DN, and the control group comprised the remaining patients without DN. rs6495446 in MTHFS had no significant effect on the risk of DN in Taiwanese patients with T2D. Multivariate logistic regression analysis demonstrated that being male, the duration of diabetes, plasma triglyceride level, and glycemic control were factors that predicted the development of DN.

Recognition, pathogenesis, and treatment of different stages of nephropathy in patients with type 2 diabetes mellitus

Nephropathy is a common microvascular complication among patients with type 2 diabetes mellitus and a major cause of kidney failure. It is characterized by albuminuria (≥ 300 mg/d) and a reduced glomerular filtration rate and is often present at the time of diabetes diagnosis after the kidney has been exposed to chronic hyperglycemia during the prediabetic phase. A low glomerular filtration rate (<60 mL/min/1.73 m(2)) is also an independent risk factor for cardiovascular events and death. Detection of diabetic nephropathy during its initial stages provides the opportunity for early therapeutic interventions to prevent or delay the onset of complications and improve outcomes. An intensive and multifactorial management approach is needed that targets all risk determinants simultaneously. The strategy should comprise lifestyle modifications (smoking cessation, weight loss, increased physical activity, and dietary changes) coupled with therapeutic achievement of blood glucose, blood pressure, and lipid goals that are evidence-based. Prescribing decisions should take into account demographic factors, level of kidney impairment, adverse effects, risk of hypoglycemia, tolerability, and effects on other risk factors and comorbidities. Regular and comprehensive follow-up assessments with appropriate adjustment of the therapeutic regimen to maintain risk factor control is a vital component of care, including referral to specialists, when required.

1H-NMR-based metabonomic analysis of metabolic profiling in diabetic nephropathy rats induced by streptozotocin

Elucidation of the metabolic profiling in diabetic nephropathy (DN) rats is of great assistance for understanding the pathogenesis of DN. In this study, 1H-nuclear magnetic resonance (NMR)-based metabonomics combined with HPLC measurements was used to quantitatively analyze the metabolic changes in urine and kidney extracts from diabetic 2-wk and 8-wk rats induced by streptozotocin (STZ). Pattern recognition analysis of either urine or kidney extracts indicated that the two diabetic groups were separated obviously from the control group, suggesting that the metabolic profiles of the diabetic groups were markedly different from the control. The diabetic 8-wk rats showed lower levels of creatine, dimethylamine, and higher levels of ascorbate, succinate, lactate, citrate, allantoin, 2-ketoglutarate, and 3-hydrobutyrate (3-HB) in the urine samples. Moreover, the diabetic 8-wk rats displayed lower levels of succinate, creatine, myo-inositol, alanine, lactate, and ATP, and higher levels of 3-HB and glucose in the kidney extracts. The observed metabolic changes imply the enhanced pathways of either lipid or ketone body synthesis and decreased pathways of either tricarboxylic acid cycle or glycolysis in DN rats compared with the control. Our results suggest that the energy metabolic changes are associated with the pathogenic process of DN.