Lipids and diabetic nephropathy

The role of advanced glycation end products between thyroid function and diabetic nephropathy and metabolic disorders

purpose of this study was to investigate the relationship between AGEs, TSH, metabolic metrics and DN, and to provide evidence for future intervention.

METHOD

This study selected community health service centers which had signed medical alliance agreement with the First Affiliated Hospital of Anhui Medical University and outpatints and inpatients in Anhui province. From March 2018 to July 2022, the multi-stage cluster sampling. method was used to screen residents aged 18-90 years in the above areas. Participants' blood was collected on an empty stomach to detect TSH, blood lipids, liver and kidney function and blood glucose, in addition, AGEs levels were detected by skin autofluorescence (SAF), and urine was retained to measure the ratio of urinary microalbumin to creatinine concentration by ACR. One-way ANOVA was used to compare the differences between general data, biochemical markers, and urinary ACR, association between variables.

RESULT

A total of 7000 patients who participated in community health examination and inpatients and also had no history of serious mental disorders were selected. After excluding data with missing value of more than 5%, 6921 samples were finally included, and the effective rate was 94.4%. Following health risk factors (HRFs), such as body mass index (BMI), TSH, low-density lipoprotein (LDL), TyG (triglyceride glucose index), systolic blood pressure (SBP), cholesterol (TC), and uric acid (UA) were associated with a higher incidence of urine ACR. In moderation analysis, there is an significant effect among TSH, AGEs and DN, HRFs moderate also these effect.

CONCLUSION

The findings suggest that HRFs such as HDL, TyG and TC should be prioritized when evaluating indicators related to DN to effectively reduce DN in Chinese patients with high health risk levels. Comprehensive indicators may be an effective and practical. method to evaluate the metabolic progression of DN. Optimizing thyroid function management may be a new strategy to prevent and treat DN and may help reduce the risk of AGE-related complications in people with diabetes. This study highlights the important role of AGEs in the relationship between TSH and DN. In addition, future studies should further explore how to improve the management and prevention of DN by regulating TSH.Among the leading causes of disability and death in patients with type 1 diabetes mellitus (T1DM) and type 2 diabetes (T2DM), chronic kidney disease (CKD) occupies a certain position. Multi-factor intervention targeting advanced glycation end products (AGEs), blood glucose, blood pressure and lipids can reduce the morbidity and mortality of diabetic nephropathy (DN) in T2DM patients through thyroid stimulating hormone (TSH), which plays an important role in the pathological process of metabolic diseases such as DN. AGEs, as a key factor in metabolic regulation, may affect the formation and function of the thyroid gland; However, in DN, the correlation between AGEs and TSH has not been clarified. We hypothesized that AGEs aggravated the negative effect of TSH on DN. The.

Identification of Probucol as a candidate for combination therapy with Metformin for Type 2 diabetes

Type 2 Diabetes (T2D) is often managed with metformin as the drug of choice. While it is effective overall, many patients progress to exhibit complications. Strategic drug combinations to tackle this problem would be useful. We constructed a genome-wide protein-protein interaction network capturing a global perspective of perturbations in diabetes by integrating T2D subjects' transcriptomic data. We computed a 'frequently perturbed subnetwork' in T2D that captures common perturbations across tissue types and mapped the possible effects of Metformin onto it. We then identified a set of remaining T2D perturbations and potential drug targets among them, related to oxidative stress and hypercholesterolemia. We then identified Probucol as the potential co-drug for adjunct therapy with Metformin and evaluated the efficacy of the combination in a rat model of diabetes. We find Metformin-Probucol at 5:0.5 mg/kg effective in restoring near-normal serum glucose, lipid, and cholesterol levels.

TGF-Beta as a Master Regulator of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most common complications in diabetes mellitus and the leading cause of end-stage renal disease. TGF-β is a pleiotropic cytokine and has been recognized as a key mediator of DN. However, anti-TGF-β treatment for DN remains controversial due to the diverse role of TGF-β1 in DN. Thus, understanding the regulatory role and mechanisms of TGF-β in the pathogenesis of DN is the initial step towards the development of anti-TGF-β treatment for DN. In this review, we first discuss the diverse roles and signaling mechanisms of TGF-β in DN by focusing on the latent versus active TGF-β1, the TGF-β receptors, and the downstream individual Smad signaling molecules including Smad2, Smad3, Smad4, and Smad7. Then, we dissect the regulatory mechanisms of TGF-β/Smad signaling in the development of DN by emphasizing Smad-dependent non-coding RNAs including microRNAs and long-non-coding RNAs. Finally, the potential therapeutic strategies for DN by targeting TGF-β signaling with various therapeutic approaches are discussed.

Protective Effect of Hydroxysafflor Yellow A on Nephropathy by Attenuating Oxidative Stress and Inhibiting Apoptosis in Induced Type 2 Diabetes in Rat

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus, and its prevalence has been increasing all over the world, which is also the leading cause of end-stage renal failure. Hydroxysafflor yellow A (HSYA) is the main active chemical component of Carthamus tinctorius L., and it is commonly used in patients with cardiovascular and cerebrovascular diseases in China. The aim of this study was to investigate the renal protective effects and molecular mechanisms of HSYA on high-fat diet (HFD) and streptozotocin- (STZ-) induced DN in rats. The DN rats were treated with HSYA for eight weeks. We assessed creatinine (CR), urea nitrogen (UN), glomerular volume, podocyte number, renal inflammation, oxidative stress, and cells apoptosis markers after HSYA treatment. The number of apoptotic cells was measured by the TUNEL assay, and apoptosis-related proteins BAX, caspase-3, and BCL-2 in the renal tissue were analyzed by western blot. The treatment with HSYA significantly decreased fasting blood glucose, CR, UN, and blood lipid profile, including triglyceride and total and low-density lipoprotein cholesterol, even though it did not change the rats' body weights. The western blot results indicated that HSYA reversed the upregulation of BAX and caspase-3 and significantly increased BCL-2 in renal tissue. Moreover, the levels of TNF-α and the inflammatory products, including free fatty acids (FFA) and lactic dehydrogenase (LDH) in the HSYA group, were significantly decreased. For the oxidative stress marker, the superoxide dismutase (SOD) markedly increased in the HSYA treatment group, while the malondialdehyde (MDA) in the serum and kidney tissue evidently decreased. In conclusion, HSYA treatment preserved kidney function in diabetic nephropathy in the HFD- and STZ-induced rats. The potential mechanism of renal protective effect of HSYA might be through inhibiting oxidative stress, reducing inflammatory reaction, and attenuating renal cell apoptosis. Our studies present a promising use for Hydroxysafflor yellow A in the treatment of type 2 diabetes mellitus.

Link between ACE I/D Gene Polymorphism and Dyslipidemia in Diabetic Nephropathy: A Case-control Study from Hyderabad, India

Introduction:

Diabetic nephropathy (DN) is the commonest single cause of end-stage renal failure, and dyslipidemia is a critical risk factor in the occurrence of DN. In the light of recent reports emphasizing the importance of angiotensin I-converting enzyme (ACE) in the modulation of plasma lipids, we sought to evaluate the influence of ACE I/D gene polymorphism with dyslipidemia status among type 2 diabetic (T2D) patients with and without nephropathy in the genetic predisposition and the progression to DN.

Method:

This study comprised of 600 subjects, which include patients with DN, T2D, and healthy controls (HC). Polymerase chain reaction based genotyping of ACE I/D polymorphism was performed and appropriate statistical analysis was done.

Results:

Out of the 600 subjects, 20 (10%) of the HC, 73 (36.5%) of the T2D group, and 125 (62.5%) of the DN subjects had dyslipidemia. The D allele (0.62) and DD (42.5) genotype frequencies were higher in the DN group in comparison with T2D and HC (P < 0.05). The genotypes also varied among patients with dyslipidemia (χ² 5.04; P < 0.05) but not in the non-dyslipidemia group. Under the co-dominant model, DD genotype conferred a risk of 1.26 (P < 0.001) toward DN, whereas the ID genotype offered protection from DN among the dyslipidemic subjects (OR = 0.05; P < 0.01). In addition, genotype-dependent difference was seen in the plasma lipid levels among study groups. A multiple logistic regression analysis revealed male gender, BMI, HbA1c, TG, HDL, and ACE DD genotype as independent risk factors for the development of DN.

Conclusion:

The study showed a significant predisposing association of ACE DD genotype with DN and protective effect of ID genotype on DN in the dyslipidemia subgroup.

Intensive multifactorial intervention improved renal impairment in short-duration type 2 diabetes: A randomized, controlled, 7-year follow-up trial

AIMS

To investigate the effect of multifactorial intervention on the urinary albumin to creatinine ratio (UACR) and the estimated glomerular filtration rate (eGFR) in short-duration type 2 diabetes.

METHODS

A total of 150 type 2 diabetes patients, with disease duration <1 year and with no evidence of atherosclerosis were randomized to either the intensive intervention group (IG, n = 75), or the conventional group (CG, n = 75) for 7 years. The predefined endpoint of microvascular complications was the progression of renal impairments (the development of albuminuria and the change of eGFR).

RESULTS

The incidence of progression to albuminuria (UACR ≥30 mg/g) was 12% in IG and 28% in CG (HR 0.37, 95% CI: 0.19-0.70, P = .0025). eGFR was significantly lower in IG than that in CG in the year 2 (P = .043) and 3 (P = .032) follow-up. Sex, fasting plasma glucose (FPG), HbA1c, and systolic blood pressure (SBP) were independently associated with the UACR (β = -5.112, P = .015; β = 0.908, P = .045; β = 2.087, P = .038; and β = 2.787, P = .002, respectively); aging was independently associated with eGFR (β = -0.447, P = .000).

CONCLUSIONS

Intensive multifactorial intervention delayed the progression to albuminuria, and reduced eGFR rapidly in early stage of intervention in short-duration type 2 diabetes. FPG, HbA1c, and SBP were risk factors for UACR increase; aging was a risk factor for eGFR decline.

Should we add atorvastatin to irbesartan for improving renoprotective effects in early diabetic nephropathy? A meta-analysis of randomized controlled trials

Angiotensin II receptor blocker has exhibited their renal protective benefits in diabetic nephropathy. This meta-analysis aimed to evaluate the effects of adding atorvastatin to irbesartan in early diabetic nephropathy. A systematic literature search was performed in PubMed, Embase, Cochrane Library, CNKI, VIP, and Wanfang database until March 25, 2019. Randomized controlled trials evaluating the effects of adding atorvastatin to irbesartan in early diabetic nephropathy were eligible. Primary endpoint was urinary albumin excretion rate, serum creatinine, and blood urea nitrogen. Serum level of total cholesterol, triglyceride, fasting blood glucose, interleukin-6,and C-reactive protein (CRP) as well as blood pressure were secondary endpoints. Seventeen trials involving 1,390 patients were identified. Compared with irbesartan alone, co-administration of atorvastatin and irbesartan significantly reduced urinary albumin excretion rate (weighted mean differences [WMD] -21.22 μg/min; 95% confidence interval [CI] -26.95 to -15.50), serum creatinine (WMD -6.46 μmol/L; 95%CI -8.52 to 4.39),BUN (WMD -0.46 mmol/L; 95%CI -0.64 to -0.27), total cholesterol (WMD -1.79 mmol/L; 95%CI -2.34 to -1.23), triglyceride (WMD -0.93 mmol/L; 95%CI -1.20 to -0.67),and systolic blood pressure (WMD -2.27 mmHg; 95%CI -4.01 to -0.53), CRP (standard mean difference [SMD] 1.57; 95%CI -2.24 to -0.9), and Interleukin-6 (SMD 1.53; 95%CI -2.29 to -0.78). However, there was a significantly increased risk of nausea/vomiting (risk ratio 3.15; 95% CI 1.18-8.38) on the co-administration group. In conclusion, adding atorvastatin to irbesartan achieves additional renal protective benefits in early diabetic nephropathy patients. However, these findings should be interpreted with caution due to suboptimal methodological quality of the analyzed trials.

Nelumbo nucifera leaves extract attenuate the pathological progression of diabetic nephropathy in high-fat diet-fed and streptozotocin-induced diabetic rats

Diabetic nephropathy is not only a common and severe microvascular complication of diabetes mellitus but also the leading cause of renal failure. Lotus (Nelumbo nucifera) possesses antioxidative and anticancer properties. The present study aimed to investigate the antidiabetic and renoprotective effects of N. nucifera leaf extract (NLE) in a rat model of type 2 diabetic mellitus. Male Sprague–Dawley rats with type 2 diabetes induced by a high-fat diet (HFD)/streptozotocin (STZ) were treated with NLE at dosages of 0.5% and 1% (w/w) daily for 6 weeks. At the end of the experimental period, body weight, serum glucose levels, insulin levels, and kidney function were assessed. Furthermore, antioxidant enzyme and lipid peroxide levels were determined in the kidney, and histopathological examination was performed using hematoxylin and eosin staining, periodic acid Schiff staining, and Masson trichrome staining. To shed light on the molecular mechanism underlying the functioning of NLE, mouse glomerular mesangial cells (MES-13) treated with high glucose (HG, 25 mM glucose) were chosen as a model for an examination of the signal transduction pathway of NLE. The results revealed that NLE improved diabetic kidney injury by reducing blood glucose, serum creatinine, and blood urea nitrogen levels and enhanced antioxidant enzyme activities in kidney tissue. Treatment with NLE significantly reduced the malondialdehyde and 8-hydroxy-2-deoxyguanosine levels and increased serum insulin levels; expression of renal superoxide dismutase, catalase, and glutathione peroxidase activities; and glutathione content. Histological studies have also demonstrated that NLE treatment inhibited the dilation of Bowman’s capsule, which confirmed its renoprotective action in diabetes. In addition, treatment with NLE and its major component quercetin 3-glucuronide attenuated 25 mM HG-induced suppressed nuclear factor erythroid 2-related factor 2 and antioxidant enzyme expression in MES-13 cells. Collectively, these findings indicate that NLE may have antidiabetic and renoprotective effects against HFD/STZ-induced diabetes, at least in part, through antioxidative pathways.

Glycation and HMG-CoA Reductase Inhibitors: Implication in Diabetes and Associated Complications

INTRODUCTION

Diabetes Mellitus (DM) acts as an absolute mediator of cardiovascular risk, prompting the prolonged occurrence, size and intricacy of atherosclerotic plaques via enhanced Advanced Glycation Endproducts (AGEs) formation. Moreover, hyperglycemia is associated with enhanced glyco-oxidized and oxidized Low-Density Lipoprotein (LDL) possessing greater atherogenicity and decreased the ability to regulate HMG-CoA reductase (HMG-R). Although aminoguanidine (AG) prevents the AGE-induced protein cross-linking due to its anti-glycation potential, it exerts several unusual pharmaco-toxicological effects thus restraining its desirable therapeutic effects. HMG-R inhibitors/ statins exhibit a variety of beneficial impacts in addition to the cholesterol-lowering effects.

OBJECTIVE

Inhibition of AGEs interaction with receptor for AGEs (RAGE) and glyco-oxidized-LDL by HMG-R inhibitors could decrease LDL uptake by LDL-receptor (LDL-R), regulate cholesterol synthesis via HMG-R, decrease oxidative and inflammatory stress to improve the diabetes-associated complications.

CONCLUSION

Current article appraises the pathological AGE-RAGE concerns in diabetes and its associated complications, mainly focusing on the phenomenon of both circulatory AGEs and those accumulating in tissues in diabetic nephropathy, diabetic neuropathy, and diabetic retinopathy, discussing the potential protective role of HMG-R inhibitors against diabetic complications.

Renoprotective effect of JinQi-JiangTang tablet on high-fat diet and low-dose streptozotocin-induced type 2 diabetic rats

JinQi-JiangTang tablet (JQ), a traditional Chinese patent medicine, have been commonly applied to clinical therapy in type 2 diabetic patients. The present study was undertaken to investigate the renoprotective effect of JQ on type 2 diabetic rats. The type 2 diabetic rat model was successfully induced by a high-fat and high-sugar diet combined with a single low-dose of streptozotocin. Intervention with JQ could significantly diminish the body weight loss, reduce the levels of fasting blood glucose, 24 hour urinary protein, blood urea nitrogen and serum creatinine in STZ-induced diabetic rats. JQ improved the creatinine clearance in diabetic rats. What's more, the levels of total cholesterol, triglyceride and low-density lipoprotein cholesterol were markedly reduced following JQ treatment, while the level of high-density lipoprotein cholesterol was elevated. Moreover, JQ significantly improved the activity of superoxide dismutase, catalase and glutathione peroxidase, whereas decreased the level of lipid peroxidation malondialdehyde in renal tissue of diabetic rats. Furthermore, immunohistochemical analysis showed that JQ significantly downregulated the expression of Bax, Caspase-3 and Cytochrome c and upregulated Bcl-2 protein expression in the renal tissue of diabetic rats, which was considered as the major pathogeneses of apoptosis. These data demonstrated that JQ exhibited a renoprotective effect through blood glucose control, alleviating lipid metabolism, anti-oxidative stress and anti-apoptosis activities.

Sitagliptin-Moringa oleifera coadministration did not delay the progression nor ameliorated functional and morphological anomalies in alloxan-induced diabetic nephropathy

OBJECTIVE:

Sitagliptin (ST) and Moringa oleifera (MO) Lam (Moringaceae) are used concomitantly by diabetic patients, with no study ascertaining for potential favorable or otherwise renal implications. We investigated the effect of coadministration of ST and MO leaf extract on functional and morphological biomarkers of alloxan-induced diabetic nephropathy (DN).

MATERIALS AND METHODS:

Diabetes was induced with a single dose of 150 mg/kg of alloxan intraperitoneally. Seven groups of eight rats per group were used, with Groups I, II, and VII as normal (NS), diabetic control (DC), and postprandial controls. Groups III, IV, V, and VI were diabetic rats on ST, MO, ST and MO (SM), for 42 days with 2 weeks delayed treatment in a postprandial hyperglycemic group (PPSM), respectively. Serum urea, albumin, electrolyte levels, lipid profile, and kidney tropism were determined in addition to histological examinations.

RESULTS:

There was a significant increase (P < 0.05) in kidney tropism comparing all drug-treated groups and DC to normal rats. Significant increases in serum urea were observed (P = 0.02) in DC, MO-treated, and SM-treated rats compared to normal rats and also in serum triglyceride (P < 0.05) in MO-treated and SM-treated rats compared to controls and other drug-treated groups. A mild reduction in severity of pathologic lesions was observed (glomerulosclerosis Grade 1) in SM-treated rats compared to a marked necrosis in DC (Grade 3).

CONCLUSION:

The coadministration of ST–MO did not delay the progression of functional anomalies and renal injury nor ameliorated the lesions associated with chronic DN in Wistar rats.

NaoXinTong Capsules inhibit the development of diabetic nephropathy in db/db mice

NaoXinTong Capsule (NXT), a Chinese medicine, is currently used to treat patients with cardiovascular and cerebrovascular diseases. Clinical observations indicate its anti-diabetic functions with unclear mechanisms. Herein, we report the effect of NXT on diabetic nephropathy (DN). Type 2 diabetic db/db mice were treated with NXT for 14 weeks. In the course of treatment, NXT reduced diabetes-increased glucose levels and improved renal functions. At the end of treatment, we found that NXT ameliorated serum lipid profiles and other biochemical parameters. In the kidney, NXT inhibited mesangial matrix expansion, expression of vascular endothelial growth factor A, fibronectin, advanced glycation end product and its receptor. Meanwhile, it reduced the diabetes-induced podocyte injury by increasing WT1 and nephrin expression. In addition, NXT inhibited accumulation of extracellular matrix proteins by increasing MMP2/9 expression through inactivation of TGFβ/Smad pathway and CTGF expression. Mechanically, NXT activated insulin signaling pathway by increasing expression of INSR, IRS and FGF21, phosphorylation of Akt and AMPKα in the liver, INSR phosphorylation in the kidney, and FGF21 and GLUT4 expression in adipose tissue and skeletal muscle. Taken together, our study demonstrates that NXT inhibits DN by ameliorating glucose/lipid metabolism, maintaining tissue structure integrity, and correcting diabetes-induced renal dysfunctions.

Hypolipidemic and Antioxidant Properties of Oryzanol Concentrate in Reducing Diabetic Nephropathy via SREBP1 Downregulation Rather than β-Oxidation

SCOPE

Diabetic nephropathy (DN) is a micro-vascular complication of chronic diabetes. Sterol regulatory element binding protein1 (SREBP1) participation in the development of DN is reported. Oryzanol concentrate (OC) at 0.1% and 0.3% is tested for its antioxidant and hypolipidemic effects. The aim of the work is to study the involvement of OC in the amelioration of DN in STZ-induced diabetic animal model.

METHODS AND RESULTS

Animals were grouped into starch, high-fat, and OC-treated control/diabetic groups (SFC/SFD, HFC/HFD, OFC/OFD). The markers of DN, increased glomerular filtration rate and kidney weight, were evident in HFD and reduced in OFD group by ≈1.09 and ≈1.3 fold, respectively. The amelioration of defensive antioxidant enzyme activities and lipid peroxidation, expressions of lipid-associated biomolecules (SREBP1 and FAS) were also observed. HFD showed increased ECM accumulation of glycoproteins, particularly Type IV collagen, fibronectin. SREBP1-associated gene transforming growth factor-β (TGF-β) was reduced on treatment (OFD ≈ 1.3 fold) as to HFD (≈2.7 fold).

CONCLUSION

Oryzanol concentrate, having hypolipidemic and antioxidant properties, also downregulated the lipid biosynthesis through reduced SREBP1-TGF-β interactions (EMSA) and could effectively ameliorate DN. Gene (ACC2, Cpt1, and ACOX) expression studies showed that β-oxidation was not involved in reducing DN.

Stachyose Improves Inflammation through Modulating Gut Microbiota of High-Fat Diet/Streptozotocin-Induced Type 2 Diabetes in Rats

SCOPE

The present study is undertaken to assess the effects of stachyose (STS) on type 2 diabetes in rats and changes in the gut microbiota compared to metformin (MET).

METHODS AND RESULTS

The type 2 diabetic model is successfully established via a high-fat diet /streptozotocin in Wistar rats, and STS or MET is administered for 4 weeks. Blood is collected to analyze biochemical parameters, pancreas for mRNA expression of related gene, and contents of colon for gut microbiota. STS or MET decreases serum LPS, mRNA expression of IL-6, and tumor necrosis factor-α (TNF-α). In addition, STS and MET show a similar shifting of the structure of the gut microbiota and a selective enrichment of key species. At the genus level, STS shows selective enrichment of Phascolarctobacterium, Bilophila, Oscillospira, Turicibacter, and SMB5, but MET demonstrates a selective effect on Sutterella, Prevotella, 02d06, and rc4. The correlation analysis indicates that STS and MET decrease IL-6 and TNF-α and increase Akt/PI3K expression, which are relative to key species of gut microbiota.

CONCLUSION

STS decreases pancreatic mRNA expression of IL-6 and TNF-α via key species of gut microbiota. The mechanism of this effect is similar to that of MET.

Crosstalk of Hyperglycemia and Dyslipidemia in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) is defined by the functional, structural, and clinical abnormalities of the kidney that are caused by diabetes.

Summary

One-third of both type 1 diabetes and type 2 diabetes patients suffer from DKD, which is the leading cause of end-stage renal disease, and is also associated with cardiovascular disease and high public health care costs. Serum glucose level and lipid level are key factors in the pathogenesis of DKD and are modifiable. The goal of this review is to provide an update on the roles of glucose and lipid metabolism in DKD and their crosstalk at the molecular level. We will further discuss the recent advances regarding metabolic nuclear receptors in glucose-lipid crosstalk, which may provide new potential therapeutic targets for DKD.

Key Message

AMPK, SREBP-1, and some metabolic hormone receptors including liver X receptors, farnesoid X receptors, and peroxisome proliferator-activated receptors mediate the crosstalk of hyperglycemia and dyslipidemia in diabetic kidney disease and might be potential treatment candidates.

Metformin ameliorates diabetic nephropathy in a rat model of low-dose streptozotocin-induced diabetes

The present study aimed to explore the renoprotective effect of metformin on diabetic nephropathy in type 2 diabetic rats. A rat model of type 2 diabetic nephropathy (T2DN) was successfully induced via a high-fat diet combined with a single low-dose of streptozotocin. Metformin was administered intragastrically for 13 weeks, and fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), HDL-c, LDL-c, urinary and serum creatinine levels were subsequently examined at the end of administration. Renal function was determined after the treatment protocol. Expression levels of transforming growth factor (TGF)-β1 and connective tissue growth factor (CTGF) were assessed via immunohistochemical analysis. Superoxide dismutase activity, malondialdehyde content and glutathione peroxidase levels were assessed in kidney tissues using commercially available kits. The results of the present study demonstrated that metformin administration significantly decreased the levels of serum blood urea nitrogen, serum creatinine, creatinine clearance, urinary albumin excretion and fasting blood glucose in rats with T2DN. Furthermore, TG, TC and LDL-c levels were significantly decreased following metformin treatment, whereas HDL-c was increased. Metformin treatment significantly increased SOD activity and significantly decreased malondialdehyde levels, as compared with the model group. It was also demonstrated that metformin administration significantly decreased the expression levels of TGF-β1 and attenuated the morphological changes associated with T2DN in rats. These data clearly demonstrated the renoprotective effects of metformin against the development and progression of T2DN in rats. The underlying mechanism of this protective effect may be associated with glycemic control, lipid metabolism, and anti-oxidative and anti-inflammatory functions.

Cordyceps militaris Treatment Preserves Renal Function in Type 2 Diabetic Nephropathy Mice

Diabetic nephropathy is derived from long-term effects of high blood glucose on kidney function in type 2 diabetic patients. Several antidiabetic drugs and herbal medications have failed to prevent episodes of DN. Hence, this study aimed to further investigate the renal injury-reducing effect of antidiabetic CmNo1, a novel combination of powders of fruiting bodies and mycelia of Cordyceps militaris. After being administered with streptozotocin-nicotinamide and high-fat-diet, the diabetic nephropathy mouse model displayed elevated blood glucose and renal dysfunction markers including serum creatinine and kidney-to-body weight ratio. These elevated markers were significantly mitigated following 8 weeks CmNo1 treatment. Moreover, the chronic hyperglycemia-induced pathological alteration in renal tissue were also ameliorated. Besides, immunohistochemical study demonstrated a substantial reduction in elevated levels of carboxymethyl lysine, an advanced glycation end product. Elevated collagenous deposition in DN group was also attenuated through CmNo1 administration. Moreover, the enhanced levels of transforming growth factor-β1, a fibrosis-inducing protein in glomerulus were also markedly dampened. Furthermore, auxiliary risk factors in DN like serum triglycerides and cholesterol were found to be increased but were decreased by CmNo1 treatment. Conclusively, the results suggests that CmNo1 exhibit potent and efficacious renoprotective action against hyperglycemia-induced DN.

Effects of curcumin in experimental diabetic nephropathy

Diabetic nephropathy (DN) is currently well established as the most common cause of end-stage renal disease in most parts of the world. Notwithstanding the expanding basic and clinical research in this field, the pathogenesis remains far from clear and hence the treatment of DN remains suboptimal. There is a critical need for the development of newer therapeutic strategies including alternative and complementary therapies. One of the natural products that was extensively studied in cancer and other chronic disease states such as diabetes is curcumin, an active ingredient in turmeric, a spice extensively used in India. In this manuscript, we present a critical review of the experimental and clinical evidence that supports the use of curcumin and its analogs in DN as well as the various proposed mechanisms for its biological actions in health and disease states.

Severe hypertriglyceridemia and hypercholesterolemia accelerating renal injury: a novel model of type 1 diabetic hamsters induced by short-term high-fat / high-cholesterol diet and low-dose streptozotocin

Background

Hyperlipidemia is thought to be a major risk factor for the progression of renal diseases in diabetes. Recent studies have shown that lipid profiles are commonly abnormal early on type 2 diabetes mellitus (T2DM) with diabetic nephropathy. However, the early effects of triglyceride and cholesterol abnormalities on renal injury in type 1 diabetes mellitus (T1DM) are not fully understood and require reliable animal models for exploration of the underlying mechanisms. Hamster models are important tools for studying lipid metabolism because of their similarity to humans in terms of lipid utilization and high susceptibility to dietary cholesterol and fat.

Methods

Twenty-four male Golden Syrian hamsters (100–110 g) were rendered diabetes by intraperitoneal injections of streptozotocin (STZ) on consecutive 3 days at dose of 30 mg/kg, Ten days after STZ injections, hamsters with a plasma Glu concentration more than 12 mmol/L were selected as insulin deficient ones and divided into four groups (D-C, D-HF, D-HC, and D-HFHC), and fed with commercially available standard rodent chow, high-fat diet, high-cholesterol diet, high-fat and cholesterol diet respectively, for a period of four weeks.

Results

After an induction phase, a stable model of renal injury was established with the aspects of early T1DM kidney disease, These aspects were severe hypertriglyceridemia, hypercholesterolemia, proteinuria with mesangial matrix accumulation, upgraded creatinine clearance, significant cholesterol and triglyceride deposition, and increasing glomerular surface area, thickness of basement membrane and mesangial expansion. The mRNA levels of sterol regulatory element binding protein-1c, transforming growth factors-β, plasminogen activator inhibitor-1, tumor necrosis factor-α and interleukin-6 in the D-HFHC group were significantly up-regulated compared with control groups.

Conclusions

This study presents a novel, non-transgenic, non-surgical method for induction of renal injury in hamsters, which is an important complement to existing diabetic models for pathophysiological studies in early acute and chronic kidney disease, especially hyperlipidemia. These data suggest that both severe hypertriglyceridemia and hypercholesterolemia can accelerate renal injury in the early development of T1DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0041-5) contains supplementary material, which is available to authorized users.

Role of Toll-like receptors in diabetic nephropathy

Diabetic nephropathy is the leading cause of kidney failure and its increasing prevalence and incidence has imposed global socio-economic stress on healthcare systems worldwide. Although historically considered a metabolic disorder, recent studies have established that inflammatory responses are central to the pathogenesis of diabetic nephropathy. TLRs (Toll-like receptors) are a family of pattern recognition receptors responsible for the initiation of inflammatory and immune responses. The regulation of TLR2 and TLR4 have been implicated in the pathogenesis of various kidney diseases, and emerging evidence shows their involvement in the perpetuation of inflammation in the diabetic kidney. The present review focuses on the relative contributions of TLR2 and TLR4 in recognizing endogenous ligands relevant to diabetic nephropathy and their subsequent activation of NF-κB (nuclear factor κB), which results in the synthesis and secretion of pro-inflammatory cytokines and chemokines. Moreover, we discuss the pro-inflammatory signalling pathways of TLR2 and TLR4, in which their interruption or blockade may prove to be important therapeutic targets, potentially translated into clinical treatments for diabetic nephropathy. Currently, inhibitors to TLR2 and TLR4 are undergoing clinical trials in various inflammatory models of disease, but none in patients with diabetic nephropathy. Given the existing literature, there is a fundamental necessity to undertake trials in patients with diabetic nephropathy with a focus on renal end points.

Clinical challenges in diagnosis and management of diabetic kidney disease

Diabetic kidney disease (DKD) is a major and increasing worldwide public health issue. There is a great need for implementing treatments that either prevent or significantly slow the progression of DKD. Although there have been significant improvements in management, the increasing numbers of patients with DKD illustrate that current management is not wholly adequate. The reasons for suboptimal management include the lack of early diagnosis, lack of aggressive interventions, and lack of understanding about which interventions are most successful. There are a number of challenges and controversies regarding the current management of patients with DKD. Understanding of these issues is needed in order to provide the best care to patients with DKD. This article describes some of the clinically important challenges associated with DKD: the current epidemiology and cost burden and the role of biopsy in the diagnosis of DKD. Treatment controversies regarding current pharmacologic and nonpharmacologic approaches are reviewed and recommendations based on the published literature are made.

Lipid-lowering treatment and inflammatory mediators in diabetes and chronic kidney disease

BACKGROUND

Inflammation may contribute to the high cardiovascular risk in diabetes mellitus (DM) and chronic kidney disease (CKD). Monocyte chemoattractant protein-1 (MCP-1) facilitates the recruitment of monocytes into atherosclerotic lesions and is involved in diabetic nephropathy. Interferon gamma (IFNγ) is important in atherosclerosis and increases the synthesis of chemokines including MCP-1. Lipid-lowering treatment (LLT) with statins may have anti-inflammatory effects, and ezetimibe cotreatment provides additional cholesterol lowering.

METHODS

After a placebo run-in period, the effects of simvastatin alone (S) or simvastatin + ezetimibe (S+E) were compared in a randomized, double-blind, cross-over study on inflammatory parameters. Eighteen DM patients with estimated glomerular filtration rate (eGFR) 15-59 mL/min × 1·73 m(2) (CKD stages 3-4) (DM-CKD) and 21 DM patients with eGFR > 75 mL/min (DM only) were included.

RESULTS

At baseline, monocyte chemoattractant protein 1 (MCP-1) (P = 0·03), IFNγ (P = 0·02), tumour necrosis factor-α (TNFα) (P < 0·01) and soluble vascular adhesion molecule (sVCAM) (P = 0·001) levels were elevated in DM-CKD compared with DM-only patients. LLT with S and S+E reduced MCP-1 levels (P < 0·01 by anova) and IFNγ levels (P < 0·01) in DM-CKD patients but not in DM-only patients. Reductions were most pronounced with the combination treatment.

CONCLUSIONS

DM patients with CKD stages 3-4 had increased inflammatory activity compared with DM patients with normal GFR. Lipid-lowering treatment decreased the levels of MCP-1 and IFNγ in DM patients with concomitant CKD, which may be beneficial with regard to the progression of both atherosclerosis and diabetic nephropathy.

The gut-renal axis: do incretin-based agents confer renoprotection in diabetes?

Diabetic nephropathy is the leading cause of end-stage renal disease worldwide, and is associated with a high risk of cardiovascular morbidity and mortality. Intensive control of glucose levels and blood pressure is currently the mainstay of both prevention and treatment of diabetic nephropathy. However, this strategy cannot fully prevent the development and progression of diabetic nephropathy, and an unmet need remains for additional novel therapies. The incretin-based agents--agonists of glucagon-like peptide 1 receptor (GLP-1R) and inhibitors of dipeptidyl peptidase 4 (DPP-4), an enzyme that degrades glucagon-like peptide 1--are novel blood-glucose-lowering drugs used in the treatment of type 2 diabetes mellitus (T2DM). Therapeutic agents from these two drug classes improve pancreatic islet function and induce extrapancreatic effects that ameliorate various phenotypic defects of T2DM that are beyond glucose control. Agonists of GLP-1R and inhibitors of DPP-4 reduce blood pressure, dyslipidaemia and inflammation, although only GLP-1R agonists decrease body weight. Both types of incretin-based agents inhibit renal tubular sodium reabsorption and decrease glomerular pressure as well as albuminuria in rodents and humans. In rodents, incretin-based therapies also prevent onset of the morphological abnormalities of diabetic nephropathy.

Genetic associations in diabetic nephropathy

Diabetic nephropathy is a complex disease, caused by both environmental and genetic factors. As in most complex diseases, genetic association studies in diabetic nephropathy showed inconsistent results. In retrospect, studies with small sample sizes, given what are now known to be small odds ratios, were partially responsible for this poor replication record. Furthermore, the low prior probability in complex genetics and multiple testing played a role. Results become more consistent when one only considers those that were replicated. In a large meta-analysis study including only replicated associated genetic variants, 24 genetic variants in 16 genes were found to be associated with diabetic nephropathy. These genetic variants may provide novel biological insight. In particular, rare variants with a large effect found by hypothesis-free approaches (genome-wide association scans, next-generation sequencing) may open new avenues of discovery.

Proanthocyanidin Attenuation of Oxidative Stress and NF- κ B Protects Apolipoprotein E-Deficient Mice against Diabetic Nephropathy

Hyperlipidemia and hyperglycemia result in oxidative stress and play a major role in the development of diabetic nephropathy (DN). We explored the effects of proanthocyanidin (PA) on the induction and progression of DN in apolipoprotein E-deficient mice. Diabetes Mellitus was induced in ten-week-old male apoE^−/−mice using streptozotocin (STZ). Mice were fed with a high-fat diet in presence or absence of PA. PA treatment significantly reduced the high cholesterol levels, restored renal functions, and reduced albuminuria in the PA-treated diabetic mice compared with the diabetic untreated mice. In addition, the glomerular mesangial expansion in the diabetic mice was attenuated as a result of PA supplementation. Moreover, PA treatment restored the elevated levels of MDA and CML and the reduced activity of SOD and GSH in the diabetic mice. Furthermore, PA feeding reduced the activation and translocation of NF-κB to the nucleus compared with the diabetic untreated animals. Reduction of NF-κB activation resulted in the attenuation of the expression of IL-6, TGFβ, and RAGE which protected PA-treated mice against DN. The renoprotective effects of PA were found to be time independent regardless of whether the dietary feeding with PA was started pre-, co-, or post-STZ injection. In conclusion, part of the beneficial effects of PA includes the disruption of the detrimental AGE-RAGE-NFκB pathways.

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.

An ACACB variant implicated in diabetic nephropathy associates with body mass index and gene expression in obese subjects

Acetyl coenzyme A carboxylase B gene (ACACB) single nucleotide polymorphism (SNP) rs2268388 is reproducibly associated with type 2 diabetes (T2DM)-associated nephropathy (DN). ACACB knock-out mice are also protected from obesity. This study assessed relationships between rs2268388, body mass index (BMI) and gene expression in multiple populations, with and without T2DM. Among subjects without T2DM, rs2268388 DN risk allele (T) associated with higher BMI in Pima Indian children (n = 2021; p-additive = 0.029) and African Americans (AAs) (n = 177; p-additive = 0.05), with a trend in European Americans (EAs) (n = 512; p-additive = 0.09), but not Germans (n = 858; p-additive = 0.765). Association with BMI was seen in a meta-analysis including all non-T2DM subjects (n = 3568; p-additive = 0.02). Among subjects with T2DM, rs2268388 was not associated with BMI in Japanese (n = 2912) or EAs (n = 1149); however, the T allele associated with higher BMI in the subset with BMI≥30 kg/m(2) (n = 568 EAs; p-additive = 0.049, n = 196 Japanese; p-additive = 0.049). Association with BMI was strengthened in a T2DM meta-analysis that included an additional 756 AAs (p-additive = 0.080) and 48 Hong Kong Chinese (p-additive = 0.81) with BMI≥30 kg/m(2) (n = 1575; p-additive = 0.0033). The effect of rs2268388 on gene expression revealed that the T risk allele associated with higher ACACB messenger levels in adipose tissue (41 EAs and 20 AAs with BMI>30 kg/m(2); p-additive = 0.018) and ACACB protein levels in the liver tissue (mixed model p-additive = 0.03, in 25 EA bariatric surgery patients with BMI>30 kg/m(2) for 75 exams). The T allele also associated with higher hepatic triglyceride levels. These data support a role for ACACB in obesity and potential roles for altered lipid metabolism in susceptibility to DN.

Renoprotective effect of aged garlic extract in streptozotocin-induced diabetic rats

OBJECTIVE

Aged garlic extract (AGE) has been proven to exhibit antioxidant, hypolipidemic, hypoglycemic and antidiabetic properties. However, its effect on diabetic nephropathy was unexplored. Therefore, the present study was designed to investigate the renoprotective effect of AGE in streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Albino Wistar rats were induced with diabetes by a single intraperitoneal injection of 45 mg/kg b.w. of streptozotocin. Commercially available AGE was supplemented orally at a dose of 500 mg/kg body weight/day. Aminoguanidine, which has been proven to be an anti-glycation agent was used as positive control and was supplemented at a dose of 1 g/L in drinking water. The serum and urinary biochemical parameters were analyzed in all the groups and at the end of 12 weeks follow up, the renal histological examination were performed using H & E and PAS staining.

RESULTS

The diabetic rats showed a significant change in the urine (P < 0.001) and serum (P < 0.01) constituents such as albumin, creatinine, urea nitrogen and glycated hemoglobin. In addition, the serum lipid profile of the diabetic rats were altered significantly (P < 0.05) compared to that of the control rats. However, the diabetic rats supplemented with aged garlic extract restored all these biochemical changes. The efficacy of the extract was substantiated by the histopathological changes in the kidney.

CONCLUSION

From our results, we conclude that aged garlic extract has the ability to ameliorate kidney damage in diabetic rats and the renoprotective effect of AGE may be attributed to its anti-glycation and hypolipidemic activities.

Zhenqing recipe alleviates diabetic nephropathy in experimental type 2 diabetic rats through suppression of SREBP-1c

ETHNOPHARMACOLOGICAL RELEVANCE

Zhenqing Recipe (ZQR), a Chinese herbal prescription, is used to improve renal function of patients with diabetic nephropathy. In current research, the therapeutic effects of ZQR on type 2 diabetic nephropathy and the underlying molecular mechanisms were explored.

MATERIALS AND METHODS

Animal model with diabetic nephropathy was developed by high fat/sucrose diet feeding plus streptozotocin injection for 4 weeks. The diabetic rats were then orally administered with ZQR extract at the dose of 4 g/kg, 8 g/kg body weight/day for 8 weeks.

RESULTS

Serum glucose, triglyceride and total cholesterol in untreated diabetic rats were significantly higher than that of normal control rats. ZQR treatment not only reduced serum glucose level in diabetic rats, but also decreased serum triglyceride and total cholesterol in a dose-dependent manner. Urinary albumin excretion rate, serum urea and creatinine were significantly decreased in ZQR groups compared with untreated diabetic group. Histopathological study of kidney samples showed that extracellular mesangial matrix expansion in diabetic rats was suppressed by ZQR treatment. Both mRNA and protein levels of sterol regulatory element binding-protein-1c (SREBP-1c), and its target genes including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) in renal cortex were significantly decreased in ZQR treated rats compared to untreated diabetic rats. Consequently, renal triglyceride was significantly reduced in ZQR groups. Furthermore, ZQR significantly inhibited the overexpression of transforming growth factor-β1 and fibronectin in the renal cortex of diabetic rats.

CONCLUSIONS

Oral treatment of ZQR improved diabetic nephropathy by inhibiting the overexpression of SREBP-1c and its target genes including ACC and FAS in experimental type 2 diabetic rats.

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.

Role of triglyceride-rich lipoproteins in renal injury

Dyslipidemia is implicated as a risk factor for the development of atherosclerosis. Specifically triglyceride-rich lipoproteins and their lipolysis products are shown to be proinflammatory and proapoptosis in both in vivo and in vitro studies with endothelium. However, the role of triglyceride-rich lipoproteins in the progression of kidney diseases is not clear. Epidemiology studies demonstrated a correlation between renal disease and blood lipids. Recent evidence suggests that the mechanism may involve cellular uptake of lipid and de novo lipogenesis. Further studies are needed to establish the relevance of these mechanistic studies in human pathophysiology.

α-Lipoic acid protects diabetic apolipoprotein E-deficient mice from nephropathy

AIM

Both hyperglycemia and hyperlipidemia increase oxidative stress and contribute to the development of diabetic nephropathy (DN). We investigated the effects of α-lipoic acid, a natural antioxidant and a cofactor in the multienzyme complexes, on the development of DN in diabetic apolipoprotein E-deficient mice.

METHODS

Twelve-week-old male apoE-/- mice on C57BL/6J genetic background were made diabetic with injections of streptozotocin (STZ). STZ-treated diabetic apoE-/- mice and non-diabetic control were fed with a synthetic high-fat (HF) diet with or without lipoic acid (LA) supplementation. Multiple parameters including plasma glucose, cholesterol, oxidative stress markers, cytokines, and kidney cortex gene expression, and glomerular morphology were evaluated.

RESULTS

LA supplementation markedly protected the β cells, reduced cholesterol levels, and attenuated albuminuria and glomerular mesangial expansion in the diabetic mice. Renoprotection by LA was equally effective regardless of whether the dietary supplementation was started 4 weeks before, simultaneously with, or 4 weeks after the induction of diabetes by STZ. LA supplementation significantly improved DN and oxidative stress in the diabetic mice. Severity of albuminuria was positively correlated with level of thiobarbituric acid reactive substances (TBARs) in the kidney (r(2)=0.62, P<.05). Diabetes significantly changed the kidney expression of Rage, Sod2, Tgfb1 and Ctgf, Pdp2, nephrin, and Lias. LA supplementation corrected these changes except that it further suppressed the expression of the Lias gene coding for lipoic acid synthase.

CONCLUSIONS

Our data indicate that LA supplementation effectively attenuates the development and progression of DN through its antioxidant effect as well as enhances glucose oxidation.

Glycation and biomarkers of vascular complications of diabetes

Propensity to diabetic nephropathy (DN), retinopathy (DR), and cardiovascular disease (CVD) varies between individuals. Current biomarkers such as indicators of glycemia (HbA1c), retinal examinations, and albuminuria, cannot detect early tissue damage. HbAIc also doesn't reflect most glycative and oxidative chemical pathways that cause complications, and studies of new biomarkers to measure their end-products are needed. This review proposes the study of advanced glycation end products (AGEs) and oxidation end-products (OPs) in long-term diabetes outcome studies. AGEs integrate the activity of glycation pathways that form dicarbonyls, while OPs reflect superoxides, hydroxyl radicals, and peroxides. We discuss using these biomarkers to predict risk of development and progression of DN, DR, and CVD, and to determine if they confer risk independently of the level of HbA1c. We also discuss methods and guidelines to document sample quality in such studies. These studies have the potential to validate unique biomarkers during the early stages of diabetes in those who are at high risk of diabetic complications. Information on basic mechanisms responsible for complications could also stimulate development of therapeutic approaches to delay or arrest them. The ultimate goal is to predict those requiring aggressive therapies during the earliest stages, when prevention or reversal of complications is still possible.

Effects of combined ezetimibe and simvastatin therapy as compared with simvastatin alone in patients with type 2 diabetes: a prospective randomized double-blind clinical trial

OBJECTIVE

To assess the effects of inhibited gastrointestinal cholesterol absorption in statin-treated dyslipidemic patients.

RESEARCH DESIGN AND METHODS

In a multicenter prospective randomized double-blind placebo-controlled trial, we primarily compared by ANCOVA the effect of 2-month ezetimibe (10 mg/day) or placebo therapy on LDL cholesterol serum levels in 108 type 2 diabetic patients with albuminuria <200 microg/min and total cholesterol concentrations >135 mg/dl despite simvastatin treatment (40 mg/day).

RESULTS

Unlike placebo, ezetimibe decreased LDL cholesterol from 99 +/- 31 to 66 +/- 22 mg/dl, total cholesterol from 162 +/- 36 to 124 +/- 30 mg/dl, and apolipoprotein B from 83 +/- 22 to 64 +/- 18 mg/dl (P < 0.0001 for all changes versus placebo). A total of 72 and 17% of patients on ezetimibe or placebo achieved LDL levels <70 mg/dl, respectively (P < 0.0001). Treatment was well tolerated.

CONCLUSIONS

Adding ezetimibe to simvastatin therapy helps to improve the pro-atherogenic lipoprotein profile in type 2 diabetic patients who fail to reach recommended lipid targets with statin therapy alone.

The pleiotropic actions of rosuvastatin confer renal benefits in the diabetic Apo-E knockout mouse

Diabetic nephropathy is a leading cause of end-stage renal disease. Statins may exert renoprotective effects independently of lipid-lowering properties. We investigated the pleiotropic effects of rosuvastatin on renal structure and function in streptozotocin diabetic apolipoprotein-E knockout (Apo-E(-/-)) mice, a model of progressive nephropathy in which dyslipidemia is resistant to statin treatment. These effects were compared with those observed with conventional renin-angiotensin system blockade (candesartan) or combined treatment. Nondiabetic and diabetic Apo-E(-/-) mice were randomized to no treatment or treatment with candesartan (2.5 mg/kg), rosuvastatin (5 mg/kg), or their combination per gavage for 20 wk. Urine and blood samples were collected for assessment of albuminuria, creatinine clearance, plasma lipids, glucose, and glycated hemoglobin. Renal sclerosis was analyzed on paraffin-embedded kidney sections stained with periodic acid-Schiff. Renal expression of collagen IV, fibronectin and advanced glycation end products (AGEs), receptor for advanced glycation and products (RAGE), NADPH oxidase 4 (NOX4), and nitrotyrosine was assessed by real-time PCR and/or immunohistochemistry. Diabetes-induced albuminuria was not affected by rosuvastatin and combination treatment but was prevented by candesartan. Diabetes resulted in increased creatinine clearance, which was not modified by the treatments. Rosuvastatin and/or candesartan prevented diabetes-associated renal extracellular matrix accumulation. Rosuvastatin reduced accumulation of AGEs and expression of RAGE, NOX4, and nitrotyrosine. In conclusion, in the diabetic Apo-E(-/-) mouse, rosuvastatin confers renal benefits that are independent of lipid lowering and equivalent or greater to those observed with candesartan. The combination treatment is not superior to monotherapies.

Role of triglyceride-rich lipoproteins in diabetic nephropathy

Diabetic nephropathy is an increasingly important cause of morbidity and mortality worldwide. A large body of evidence suggests that dyslipidemia has an important role in the progression of kidney disease in patients with diabetes. Lipids may induce renal injury by stimulating TGF-beta, thereby inducing the production of reactive oxygen species and causing damage to the glomeruli and glomerular glycocalyx. Findings from basic and clinical studies strongly suggest that excess amounts of a variety of lipoproteins and lipids worsens diabetes-associated microvascular and macrovascular disease, increases glomerular injury, increases tubulointerstitial fibrosis, and accelerates the progression of diabetic nephropathy. The increasing prevalence of obesity, type 2 diabetes mellitus, and diabetic nephropathy means that interventions that can interrupt the pathophysiological cascade of events induced by lipoproteins and lipids could enable major life and cost savings. This Review discusses the structural, cellular, and microscopic findings associated with diabetic nephropathy and the influence of lipoproteins, specifically triglyceride-rich lipoproteins (TGRLs), on the development and perpetuation of diabetic nephropathy. Some of the accepted and hypothesized mechanisms of renal injury relating to TGRLs are also described.

Prevalence and determinants of albuminuria in a cohort of diabetic patients in Lebanon

BACKGROUND AND OBJECTIVES

Few data are available on the extent of albuminuria in diabetic populations in the Middle East generally and in Lebanon specifically. We conducted this study to determine the prevalence of albuminuria and its major risk factors in a cohort of diabetic patients in Lebanon.

PATIENTS AND METHODS

Diabetic patients followed in the outpatient department at the American University of Beirut Medical Center (AUBMC) were included in a prospective observational study. AUBMC is a tertiary referral center and the outpatient department typically handles patients of low socioeconomic status with advanced disease. Patients were classified according to their urinary albumin-to-creatinine ratio (ACR) as having normoalbuminuria (ACR<30 mg/g creatinine), microalbuminuria (ACR=30 to <300 mg/g creatinine), or macroalbuminuria (ACR > or =300 mg/g creatinine). The three groups were compared to analyze the association between albuminuria and its risk factors. In addition, independent predictors of albuminuria were determined using multivariate logistic regression and presented as an odds ratio.

RESULTS

Microalbuminuria and macroalbuminuria were present in 33.3% and 12.7% of 222 patients (mean age 56.4 years, mean deviation of diabetes 8.6 years, 58.7% women, 43.8% obese), respectively. Factors significantly associated with microalbuminuria included glycemic control, insulin use, and total and LDL cholesterol. Those associated with macroalbuminuria included in addition to glycemic control and insulin use, duration of diabetes, hypertension, elevated mean arterial pressure (MAP), and presence of neuropathy, retinopathy and peripheral vascular disease by bivariate analysis. Only glycemic control was an independent risk factor for both in addition to MAP and retinopathy for macroalbuminuria by multivariate analysis.

CONCLUSION

Albuminuria is highly prevalent among this cohort of diabetic patients in Lebanon. Both glycemic control and blood pressure need to be better targeted in its management.

Defining human diabetic nephropathy on the molecular level: integration of transcriptomic profiles with biological knowledge

Diabetic nephropathy (DN) is the most common cause for end stage renal disease (ESRD). Next to environmental factors, genetic predispositions determine the susceptibility for DN and its rate of progression to ESRD. With the availability of genome wide expression profiling we have the opportunity to define relevant pathways activated in the individual diabetic patient, integrating both environmental exposure and genetic background. In this review we summarize current understanding of how to link comprehensive gene expression data sets with biomedical knowledge and present strategies to build a transcriptional network of DN. Information about the individual disease processes of DN might allow the implementation of a personalized molecular medicine approach with mechanism-based patient management. Web based search engines like Nephromine are essential tools to facilitate access to molecular data of genomics, proteomics and metabolomics of DN.

Prevalence and determinants of albuminuria in a cohort of diabetic patients in Lebanon

BACKGROUND AND OBJECTIVES

Few data are available on the extent of albuminuria in diabetic populations in the Middle East generally and in Lebanon specifically. We conducted this study to determine the prevalence of albuminuria and its major risk factors in a cohort of diabetic patients in Lebanon.

PATIENTS AND METHODS

Diabetic patients followed in the outpatient department at the American University of Beirut Medical Center (AUBMC) were included in a prospective observational study. AUBMC is a tertiary referral center and the outpatient department typically handles patients of low socioeconomic status with advanced disease. Patients were classified according to their urinary albumin-to-creatinine ratio (ACR) as having normoalbuminuria (ACR<30 mg/g creatinine), microalbuminuria (ACR=30 to <300 mg/g creatinine), or macroalbuminuria (ACR > or =300 mg/g creatinine). The three groups were compared to analyze the association between albuminuria and its risk factors. In addition, independent predictors of albuminuria were determined using multivariate logistic regression and presented as an odds ratio.

RESULTS

Microalbuminuria and macroalbuminuria were present in 33.3% and 12.7% of 222 patients (mean age 56.4 years, mean deviation of diabetes 8.6 years, 58.7% women, 43.8% obese), respectively. Factors significantly associated with microalbuminuria included glycemic control, insulin use, and total and LDL cholesterol. Those associated with macroalbuminuria included in addition to glycemic control and insulin use, duration of diabetes, hypertension, elevated mean arterial pressure (MAP), and presence of neuropathy, retinopathy and peripheral vascular disease by bivariate analysis. Only glycemic control was an independent risk factor for both in addition to MAP and retinopathy for macroalbuminuria by multivariate analysis.

CONCLUSION

Albuminuria is highly prevalent among this cohort of diabetic patients in Lebanon. Both glycemic control and blood pressure need to be better targeted in its management.

LR-90 prevents dyslipidaemia and diabetic nephropathy in the Zucker diabetic fatty rat

AIMS/HYPOTHESIS

Previous studies have shown that LR-90, a new inhibitor of AGE formation, prevented the development of experimental type 1 diabetic nephropathy. In this study, we examined the effects of LR-90 in the Zucker diabetic fatty (ZDF) rat, a model of type 2 diabetes and metabolic syndrome, and investigated the mechanisms by which it may protect against renal injury.

METHODS

Male ZDF rats were treated without or with LR-90 from age 13 to 40 weeks. Metabolic and kidney functions and renal histology were evaluated. AGE accumulation and the production of the receptor for AGE (AGER) were measured. Profibrotic growth factors, extracellular matrix proteins and intracellular signalling pathways associated with glomerular and tubular damage were also analysed.

RESULTS

LR-90 dramatically reduced plasma lipids in ZDF rats, with only modest effects on hyperglycaemia. Renal AGE, AGER and lipid peroxidation were all attenuated by LR-90. LR-90 significantly retarded the increase in albuminuria and proteinuria. This was associated with reduction in glomerulosclerosis and tubulointerstitial fibrosis, concomitant with marked inhibition of renal overproduction of TGF-beta1, connective tissue growth factor, fibronectin and collagen IV. Additionally, LR-90 downregulated the activation of key mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kappaB) in the renal cortex.

CONCLUSIONS/INTERPRETATION

These results support our earlier studies on the renoprotective effects of LR-90 on type 1 diabetic nephropathy and provide further evidence that LR-90, an AGE inhibitor with pleiotrophic effects, may also be beneficial for the prevention of type 2 diabetic nephropathy, where multiple risk factors, such as hyperglycaemia, dyslipidaemia, obesity, insulin resistance and hypertension, contribute to renal injury.

Future strategies to prevent renal microvascular disease complications in diabetes

Nephropathy is one of the major chronic microvascular complications of diabetes. The epidemic of Type 2 diabetes and related incidence of end-stage renal disease is progressively increasing worldwide and represents a major public health concern that will seriously challenge any healthcare provider in the world. Despite a number of improvements in patient care, we are still unable to ameliorate or prevent the progression towards end-stage renal disease in the diabetic population. Hypertension and metabolic control appear to interact, resulting in the relentless decline in renal function observed in diabetic patients. Further understanding of the underlying mechanisms, and the development of new treatments against newly identified targets, is crucial for the prevention of this deadly microvascular diabetic complication.