Effects of atorvastatin on progression of diabetic nephropathy and local RAGE and soluble RAGE expressions in rats

Methylglyoxal in Cardiometabolic Disorders: Routes Leading to Pathology Counterbalanced by Treatment Strategies

Methylglyoxal (MGO) is the major compound belonging to reactive carbonyl species (RCS) responsible for the generation of advanced glycation end products (AGEs). Its upregulation, followed by deleterious effects at the cellular and systemic levels, is associated with metabolic disturbances (hyperglycemia/hyperinsulinemia/insulin resistance/hyperlipidemia/inflammatory processes/carbonyl stress/oxidative stress/hypoxia). Therefore, it is implicated in a variety of disorders, including metabolic syndrome, diabetes mellitus, and cardiovascular diseases. In this review, an interplay between pathways leading to MGO generation and scavenging is addressed in regard to this system's impairment in pathology. The issues associated with mechanistic MGO involvement in pathological processes, as well as the discussion on its possible causative role in cardiometabolic diseases, are enclosed. Finally, the main strategies aimed at MGO and its AGEs downregulation with respect to cardiometabolic disorders treatment are addressed. Potential glycation inhibitors and MGO scavengers are discussed, as well as the mechanisms of their action.

Unraveling the Crosstalk between Lipids and NADPH Oxidases in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a serious complication of diabetes mellitus and a leading cause of end-stage renal disease. Abnormal lipid metabolism and intrarenal accumulation of lipids have been shown to be strongly correlated with the development and progression of diabetic kidney disease (DKD). Cholesterol, phospholipids, triglycerides, fatty acids, and sphingolipids are among the lipids that are altered in DKD, and their renal accumulation has been linked to the pathogenesis of the disease. In addition, NADPH oxidase-induced production of reactive oxygen species (ROS) plays a critical role in the development of DKD. Several types of lipids have been found to be tightly linked to NADPH oxidase-induced ROS production. This review aims to explore the interplay between lipids and NADPH oxidases in order to provide new insights into the pathogenesis of DKD and identify more effective targeted therapies for the disease.

Understanding the role of glycation in the pathology of various non-communicable diseases along with novel therapeutic strategies

Glycation refers to carbonyl group condensation of the reducing sugar with the free amino group of protein, which forms Amadori products and advanced glycation end products (AGEs). These AGEs alter protein structure and function by configuring a negative charge on the positively charged arginine and lysine residues. Glycation plays a vital role in the pathogenesis of metabolic diseases, brain disorders, aging, and gut microbiome dysregulation with the aid of 3 mechanisms: (i) formation of highly reactive metabolic pathway-derived intermediates, which directly affect protein function in cells, (ii) the interaction of AGEs with its associated receptors to create oxidative stress causing the activation of transcription factor NF-κB, and (iii) production of extracellular AGEs hinders interactions between cellular and matrix molecules affecting vascular and neural genesis. Therapeutic strategies are thus required to inhibit glycation at different steps, such as blocking amino and carbonyl groups, Amadori products, AGEs-RAGE interactions, chelating transition metals, scavenging free radicals, and breaking crosslinks formed by AGEs. The present review focused on explicitly elaborating the impact of glycation-influenced molecular mechanisms in developing and treating noncommunicable diseases.

L-Lysine Ameliorates Diabetic Nephropathy in Rats with Streptozotocin-Induced Diabetes Mellitus

Introduction

Diabetic nephropathy is one of the leading causes of end-stage renal disease worldwide. Uncontrolled hyperglycemia and subsequent production of glycation end-products activate the paths which lead to diabetic nephropathy. The aim of this study was to assess the effects of L-lysine on antioxidant capacity, biochemical factors, kidney function, HSP70 level, and the expression of the TGFβ, VEGF, and RAGE genes in rats with streptozocin-induced diabetes mellitus.

Methods

Thirty-two male Wistar rats were randomly allocated to four eight-rat groups, namely, a healthy group, a diabetic group treated with vehicle (DM + vehicle), a diabetic group treated with L-lysine (DM + Lys), and a healthy group treated with L-lysine (healthy + Lys). Rats in the DM + Lys and the healthy + Lys groups were treated with L-lysine 0.15%. The levels of fasting blood glucose, insulin, HbA_1C, advanced glycation end-products (AGEs), lipid profile, serum creatinine, blood urea nitrogen, glomerular filtration rate, urine microalbumin, oxidative stress parameters, kidney histology and morphology, and TGFβ, VEGF, and RAGE gene expressions were assessed. Findings. An eight-week treatment with L-lysine significantly reduced the levels of fasting blood glucose, AGEs, kidney function parameters, oxidative stress parameters, lipid profile, and the TGFβ, VEGF, and RAGE gene expression and significantly increased the levels of serum insulin and tissue HSP70.

Conclusion

Treatment with L-lysine seems to slow down the progression of diabetic nephropathy.

Olive Leaf Powder Modulate Insulin Production and Circulating Adipokines in Streptozotocin Induced Diabetic Rats

Olives (Olea europaea) have natural phytochemical compounds that are of great importance for their potential beneficially health effects. This study aimed to evaluate the effects of olive leaf powder (OLP) on insulin production and circulating adipokines in streptozotocin-induced diabetic rats. Forty Wistar-albino male rats, weighing 200-225 g were divided into four groups (n = 10); group I: Normal healthy rats received balanced diet; group II: Diabetic control rats receiving balanced diet; group III: Diabetic rats receiving balanced diet + standard antidiabetic drugs (metformin, 600 mg/bw) and group four: Diabetic rats received diet supplemented with 2.0% OLP. The experiment was conducted for four weeks. Our results showed that the consumption of 2.0% OLP decreased serum glucose, triglycerides (TG), total cholesterol (TC), and low-density lipoprotein (LDL) levels, whereas serum high density lipoprotein (HDL) level was increased. OLP supplementation also inhibited the atherogenic index [AI; log (TG/HDL-C) and atherogenic coefficient (AC)] levels relative to those of the untreated diabetic group. Moreover, OLP increased serum adiponectin concentration, and decreased serum leptin concentration. Liver and kidney functions were also attenuated by OLP. This finding also implies that OLP can play an important role in the treatment and delay of diabetic complications.

Glycosylated hemoglobin, but not advanced glycation end products, predicts severity of coronary artery disease in patients with or without diabetes

Background

The association between coronary artery disease (CAD) and diabetes mellitus (DM) is strong but the physiologic mechanisms responsible for this association remain unclear. Patients with DM exhibit high circulating levels of glycated proteins and lipoproteins called advanced glycation end products (AGEs) which have been implicated in the development of oxidative damage to vascular endothelium. We examined the relationships between the presence and extent of CAD and AGEs in patients undergoing elective coronary artery catheterization in an urban teaching hospital.

Methods

Patients with possible CAD (n = 364) were recruited prior to elective cardiac catheterization (52% male, 48% diabetic). Regression and correlation analyses were used to examine the relationship between serum AGE concentrations, soluble AGE receptor (sRAGE) concentration, HbA_1c, LDL and the presence of obstructive CAD along with the burden of CAD measured by SYNTAX and SYNTAX II scores.

Results

AGE and sRAGE levels did not significantly correlate with any of the studied coronary artery disease parameters. HbA_1c showed positive correlation with both SYNTAX and SYNTAX II scores in patients with and without diabetes.

Conclusion

In this cross-sectional study of patients with possible CAD, serum AGEs and sRAGE concentrations did not correlate with SYNTAX or SYNTAX II scores regardless of diabetic status. HbA1C correlated positively with the SYNTAX and SYNTAX II scores in both diabetic and non-diabetic populations.

Ameliorative effects of functional chalaza hydrolysates prepared from protease-A digestion on cognitive dysfunction and brain oxidative damages

Our patented protease A–digested crude chalaza hydrolysates (CCH) show antioxidant abilities in vitro. The prophylactic effects of CCH on cognitive dysfunction and brain oxidative damages were investigated via a D-galactose (DG)–injected mouse model in this study. Fifty-four mice were randomly divided into the following: (1) CON, 0.1 mL 0.9% saline (subcutaneous injection [SC] on the back)+distilled water (oral gavage); (2) DG, 100 mg/kg BW/day D-galactose (Bio-Serv Co., Flemington, NJ, USA) (SC on the back)+distilled water (oral gavage); (3) DG_LCH, 100 mg/kg BW/day D-galactose (SC on the back) + 50 mg CCH/kg BW/day in 0.1 ml distilled water (oral gavage); (4) DG_MCH, 100 mg/kg BW/day D-galactose (SC on the back) + 100 mg CCH/kg BW/day (oral gavage); (5) DG_HCH, 100 mg/kg BW/day D-galactose (SC on the back) + 200 mg CCH/kg BW/day (oral gavage); (6) DG_AG, 100 mg/kg BW/day D-galactose (SC on the back) + 100 mg aminoguanidine hydrochloride/kg BW/day (oral gavage). The experiment lasted for 84 D. CCH, containing antioxidant-free amino acids and anserine, restored (P < 0.05) DG-injected memory injury in the Morris water maze test and attenuated the neuronal degenerations and nucleus shrinkages in the dentate gyrus area. CCH supplementation also reduced amyloid β-peptide protein levels and accumulation of advanced glycation end products (AGE) in the brain of DG-injected mice, whereas the brain antioxidant capacity was reversed (P < 0.05) by supplementing CCH. Furthermore, AGE receptor (RAGE), NFκb, IL-6, and TNF-α gene expressions were downregulated (P < 0.05) by supplementing CCH. Therefore, CCH show prophylactic effects on the development of oxidative stress-induced cognitive dysfunction.

Roles of pattern recognition receptors in diabetic nephropathy

Diabetic nephropathy (DN) is currently the most common complication of diabetes. It is considered to be one of the leading causes of end-stage renal disease (ESRD) and affects many diabetic patients. The pathogenesis of DN is extremely complex and has not yet been clarified; however, in recent years, increasing evidence has shown the important role of innate immunity in DN pathogenesis. Pattern recognition receptors (PRRs) are important components of the innate immune system and have a significant impact on the occurrence and development of DN. In this review, we classify PRRs into secretory, endocytic, and signal transduction PRRs according to the relationship between the PRRs and subcellular compartments. PRRs can recognize related pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), thus triggering a series of inflammatory responses, promoting renal fibrosis, and finally causing renal impairment. In this review, we describe the proposed role of each type of PRRs in the development and progression of DN.

Crosstalk Between Lipids and Mitochondria in Diabetic Kidney Disease

PURPOSE OF REVIEW

The goal of this review is to review the role that renal parenchymal lipid accumulation plays in contributing to diabetic kidney disease (DKD), specifically contributing to the mitochondrial dysfunction observed in glomerular renal cells in the context of DKD development and progression.

RECENT FINDINGS

Mitochondrial dysfunction has been observed in experimental and clinical DKD. Recently, Ayanga et al. demonstrate that podocyte-specific deletion of a protein involved in mitochondrial dynamics protects from DKD progression. Furthermore, our group has recently shown that ATP-binding cassette A1 (a protein involved in cholesterol and phospholipid efflux) is significantly reduced in clinical and experimental DKD and that genetic or pharmacological induction of ABCA1 is sufficient to protect from DKD. ABCA1 deficiency in podocytes leads to mitochondrial dysfunction observed with alterations of mitochondrial lipids, in particular, cardiolipin (a mitochondrial-specific phospholipid). However, through pharmacological reduction of cardiolipin peroxidation DKD progression is reverted. Lipid metabolism is significantly altered in the diabetic kidney and renders cellular components, such as the podocyte, susceptible to injury leading to worsened DKD progression. Dysfunction of the lipid metabolism pathway can also lead to mitochondrial dysfunction and mitochondrial lipid alteration. Future research aimed at targeting mitochondrial lipids content and function could prove to be beneficial for the treatment of DKD.

Enhanced Therapeutic Potency of Nanoemulsified Garlic Oil Blend Towards Renal Abnormalities in Pre-diabetic Rats

The therapeutic potency of ultrasonic nanoemulsified garlic oil blend using a non-ionic surfactant (Tween 80) was assessed on pre-diabetic Wistar rats with microalbuminuria. The pre-diabetic condition was induced in male albino Wistar rats by supplementing high-fat diet. The prolonged period of the pre-diabetic state caused renal dysfunctioning, which was indicated by microalbuminuria. Treatment of pre-diabetic rats with nanoemulsified garlic oil blend significantly ameliorated the lipid profile (p < 0.001), urinary albumin (p < 0.01), microprotein (p < 0.001), urinary triglycerides (p < 0.01), serum triglycerides (p < 0.01), serum albumin (p < 0.05), and protein levels (p < 0.01) in comparison to treatment of pre-diabetic rats with garlic oil blend or atorvastatin. Similarly, histopathological investigations indicated a remarkable attenuation in the mesangial expansion and proliferation, glomerular and tubular basement membrane thickening, and the tubular lipid deposits on administering nanoemulsified garlic oil blend than garlic oil blend or atorvastatin. Moreover, nanoemulsified garlic oil blend significantly promoted renal podocin gene expression by 3.98-fold (p < 0.001) and attenuated increased urinary podocin level by 2.92-fold (p < 0.01). Thus, our study affirms that the efficacy of garlic oil blend was augmented upon nanoemulsification, which substantially ameliorated the renal abnormalities observed in the pre-diabetic condition than garlic oil blend or atorvastatin.

Metabolic dysfunction in Emirati subjects in Abu Dhabi: Relationship to levels of soluble RAGEs

BACKGROUND

The United Arab Emirates is experiencing increasing rates of type 2 diabetes (T2D) and its complications. As soluble levels of the receptor for advanced glycation end products, (sRAGE), and endogenous secretory RAGE (esRAGE), the latter an alternatively spliced form of AGER (the gene encoding RAGE), have been reported to be associated with T2D and its complications, we tested for potential relationships between these factors and T2D status in Emirati subjects.

METHODS

In a case-control study, we recruited Emirati subjects with T2D and controls from the Sheikh Khalifa Medical City in Abu Dhabi. Anthropomorphic characteristics, levels of plasma sRAGE and esRAGE, and routine chemistry variables were measured.

RESULTS

Two hundred and sixteen T2D subjects and 215 control subjects (mean age, 57.4 ± 12.1 vs. 50.7 ± 15.4 years; P < 0.0001, respectively) were enrolled. Univariate analyses showed that levels of sRAGE were significantly lower in the T2D vs. control subjects (1033.9 ± 545.3 vs. 1169.2 ± 664.1 pg/ml, respectively; P = 0.02). Multivariate analyses adjusting for age, sex, systolic blood pressure, pulse, body mass index, Waist/Hip circumference ratio, fasting blood glucose, HDL, LDL, insulin, triglycerides, Vitamin D and urea levels revealed that the difference in sRAGE levels between T2D and control subjects remained statistically-significant, P = 0.03, but not after including estimated glomerular filtration rate in the model, P = 0.14. There were no significant differences in levels of esRAGE. Levels of plasma insulin were significantly higher in the control vs. the T2D subjects (133.6 ± 149.9 vs. 107.6 ± 93.3 pg/L. respectively; P = 0.01, after adjustment for age and sex).

CONCLUSION/DISCUSSION

Levels of sRAGE, but not esRAGE, were associated with T2D status in Abu Dhabi, but not after correction for eGFR. Elevated levels of plasma insulin in both control and T2D subjects suggests the presence of metabolic dysfunction, even in subjects without diabetes.

The role of advanced glycation end-products in the development of coronary artery disease in patients with and without diabetes mellitus: a review

Background

Traditional risk factors are insufficient to explain all cases of coronary artery disease (CAD) in patients with diabetes mellitus (DM). Advanced glycation end-products (AGEs) and their receptors may play important roles in the development and progression of CAD.

Body

Hyperglycemia is the hallmark feature of DM. An increase in the incidence of both micro-and macrovascular complications of diabetes has been observed with increased duration of hyperglycemia. This association persists even after glycemic control has been achieved, suggesting an innate mechanism of “metabolic memory.” AGEs are glycated proteins that may serve as mediators of metabolic memory due to their increased production in the setting of hyperglycemia and generally slow turnover. Elevated AGE levels can lead to abnormal cross linking of extracellular and intracellular proteins disrupting their normal structure and function. Furthermore, activation of AGE receptors can induce complex signaling pathways leading to increased inflammation, oxidative stress, enhanced calcium deposition, and increased vascular smooth muscle apoptosis, contributing to the development of atherosclerosis. Through these mechanisms, AGEs may be important mediators of the development of CAD. However, clinical studies regarding the role of AGEs and their receptors in advancing CAD are limited, with contradictory results.

Conclusion

AGEs and their receptors may be useful biomarkers for the presence and severity of CAD. Further studies are needed to evaluate the utility of circulating and tissue AGE levels in identifying asymptomatic patients at risk for CAD or to identify patients who may benefit from invasive intervention.

Preventive effects of taurine against d-galactose-induced cognitive dysfunction and brain damage

Oxidative stress arising from life processes or environmental influences and its resultant cellular dysfunctions are major causes of neurodegenerative disorders. The objectives of this study were to investigate whether taurine (Tau) can prevent d-galactose-induced cognitive dysfunction and brain oxidative damage. Mice given with Tau supplementation (100 and 400 mg per kg BW per day) spent shorter (p < 0.05) time in searching target in d-galactose (100 mg per kg BW per day) treated mice in a water maze reference memory experiment. Moreover, Tau supplementation extended (p < 0.05) the searching period around the target quadrant in the probe test of the water maze, and neuronal degeneration and nucleus shrinkage in the hippocampus dentate gyrus area of d-galactose treated mice were observed to be attenuated. Tau also downregulated (p < 0.05) expression of the glial fibrillary acidic protein (Gfap) and of the cluster of differentiation marker Cd11b; meanwhile, it strengthened (p < 0.05) antioxidant capacity and lowered (p < 0.05) the accumulation of advanced glycation end-products (AGEs) in the brain. Therefore, Tau could be effective to ameliorate oxidative damage and inflammation in the brain, and apoptosis of brain cells, which further lessen the cognitive dysfunction.

Estimation of ellagic acid and/or repaglinide effects on insulin signaling, oxidative stress, and inflammatory mediators of liver, pancreas, adipose tissue, and brain in insulin resistant/type 2 diabetic rats

Even though ellagic acid has previously been valued in many models of cancer, so far its full mechanistic effect as a natural antiapoptotic agent in the prevention of type 2 diabetes complications has not been completely elucidated, which was the goal of this study. We fed albino rats a high-fat fructose diet (HFFD) for 2 months to induce insulin resistance/type 2 diabetes and then treated the rats with ellagic acid (10 mg/kg body weight, orally) and/or repaglinide (0.5 mg/kg body weight, orally) for 2 weeks. At the serum level, ellagic acid challenged the consequences of HFFD, significantly improving the glucose/insulin balance, liver enzymes, lipid profile, inflammatory cytokines, redox level, adipokines, ammonia, and manganese. At the tissue level (liver, pancreas, adipose tissue, and brain), ellagic acid significantly enhanced insulin signaling, autophosphorylation, adiponectin receptors, glucose transporters, inflammatory mediators, and apoptotic markers. Remarkably, combined treatment with both ellagic acid and repaglinide had a more pronounced effect than treatment with either alone. These outcomes give new insight into the promising molecular mechanisms by which ellagic acid modulates numerous factors induced in the progression of diabetes.

Greater efficacy of atorvastatin versus a non-statin lipid-lowering agent against renal injury: potential role as a histone deacetylase inhibitor

Statins, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors have been shown to improve diabetic nephropathy. However, whether they provide protection via Histone deacetylases (HDAC) inhibition is not clear. We conducted a comparative evaluation of Atorvastatin (AT) versus the non-statin cholesterol-lowering drug, Ezetimibe (EZT) on severity of diabetic nephropathy. Streptozotocin-treated male Wistar rats were fed a cholesterol-supplemented diet and gavaged daily with vehicle, AT or EZT. Control rats received normal diet and gavaged vehicle (n = 8-9/group). Diabetes increased blood glucose, urine albumin-to-creatinine ratio (ACR), kidney pathology and HDAC activity, and reduced renal E-cadherin levels. Both AT and EZT reduced circulating cholesterol, attenuated renal pathology, and did not lower blood glucose. However, AT was significantly more effective than EZT at reducing kidney pathology and HDAC activity. Chromatin immunoprecipitation revealed a significantly higher association of acetylated H3 and H4 with the E-cadherin promoter in kidneys from AT-, relative to EZT- or vehicle-treated rats. Moreover, we demonstrated a direct effect of AT, but not EZT, on HDAC-inhibition and, H3 and H4- acetylation in primary glomerular mesangial cells. Overall, both AT and EZT attenuated diabetic nephropathy; however, AT exhibited greater efficacy despite a similar reduction in circulating cholesterol. HDAC-inhibition may underlie greater efficacy of statins in attenuating kidney injury.

Elevated glycated albumin and reduced endogenous secretory receptor for advanced glycation endproducts levels in serum predict major adverse cardio-cerebral events in patients with type 2 diabetes and stable coronary artery disease

BACKGROUND AND AIM

Glycated albumin (GA) and the endogenous secretory receptor for advanced glycation endproducts (esRAGE) may modulate risk related to atherosclerosis. We tested the hypothesis that elevated GA and reduced esRAGE in serum are associated with adverse clinical outcomes in patients with type 2 diabetes and stable coronary artery disease (CAD).

METHODS

We determined GA and esRAGE serum levels in 576 consecutive patients with type 2 diabetes and stable CAD undergoing sirolimus-eluting stent (SES)-PCI. The primary endpoint was the incidence of major adverse cardio-cerebral events (MACCE) including cardiac death, non-fatal myocardial infarction, and non-fatal stroke during a 2-year follow-up. The secondary endpoint was the occurrence of clinically driven repeat revascularization during a 2-year follow-up. The prognostic value of GA and esRAGE was determined with the Cox-proportional hazard model after adjustment for covariates.

RESULTS

A total 40 patients (6.9%) experienced MACCE, and 108 (18.8%) patients underwent repeat coronary revascularization during the follow-up. Serum GA (HR=1.22, 95% CI 1.16-1.28; HR=1.15, 95% CI 1.11-1.19, respectively; for both p<0.001) and esRAGE (HR=0.60, 95% CI 0.40-0.87; HR=0.75, 95% CI 0.61-0.92, respectively; for both p<0.01) levels remained independent predictors of the primary and secondary endpoints after adjustment for possible confounders.

CONCLUSIONS

Serum GA and esRAGE are novel predictors of long-term clinical outcomes in patients with type 2 diabetes and stable CAD. Increased serum GA and decreased esRAGE are associated with a poor prognosis in such patients.

Effects of methanolic extracts from edible plants on endogenous secretory receptor for advanced glycation end products induced by the high glucose incubation in human endothelial cells

Background:

In diabetic populations, endogenous secretory receptor for advanced glycation end products (esRAGE) levels may be related to the degree of diabetic complications or to the protection from diabetic complications.

Objective:

We investigated the impact of 29 methanolic extracts from edible plants on esRAGE production in human umbilical vein endothelial cells (HUVECs) cultured in high (4.5 g/L) glucose.

Materials and Methods:

Edible plants were minced, and extracts were obtained with methanol overnight. The methanolic extracts from 29 edible plants were evaporated in a vacuum. For screening study purposes, HUVECs were seeded in culture dishes (1.5 × 10⁵ cells). Then, HUVECs were incubated with 1 g/L or 4.5 g/L of glucose in SFM CS-C medium treated with methanolic extracts from edible plants (MEEP) for 96 h. Determination of esRAGE production in the cell culture-derived supernatants was performed by colorimetric ELISA. The 8-hydroxydeoxyguanosine (8-OHdG) level was determined by using the 8-OHdG Check ELISA kit. Peroxynitrite-dependent oxidation of 2’, 7’-dichlorodihydrofluorescein to 2’, 7’-dichlorofluorescein was estimated based on the method described by Crow. Because MEEP were methanolic extracts, we measured their total phenolic content (TPC). TPC was measured with a modified version of the Folin–Ciocalteu method.

Results:

The results showed eight extracts increased esRAGE production. The extract from white radish sprouts showed the highest esRAGE production activity, and then eggplant, carrot peel, young sweet corn, Jew's marrow, broad bean, Japanese radish and cauliflower. In order to understand the mechanism of esRAGE production, the eight extracts were examined for DNA damage, peroxynitrite scavenging activity, and TPC in correlation with their esRAGE production. The results showed esRAGE production correlates with the peroxynitrite level and TPC.

Conclusion:

This study supports the utilization of these eight extracts in folk medicine for improved treatment of diabetic complications.

Relationship of Advanced Glycation End Products With Cardiovascular Disease in Menopausal Women

Cardiovascular disease (CVD) represents the most significant cause of death in postmenopausal women. Advanced glycation end products (AGEs) are formed by nonenzymatic modification of proteins, lipids, and nucleic acids by glucose. This review focuses on the contribution of AGEs and their receptors to the development of CVD in menopause. Advanced glycation end products circulate and activate the proinflammatory endothelial cell surface receptor called RAGE, bind to the extracellular matrix of the cardiovascular system, or bind to the circulating anti-inflammatory soluble form of RAGE (sRAGE). Data emerging from human and animal studies suggest that AGEs and both receptors (RAGE and sRAGE) are implicated in the pathophysiology of CVD. Particular emphasis has been given to the role of AGE-RAGE axis in oxidative stress, inflammation, endothelial cell toxicity, and progression of atherosclerosis in menopause. Data accruing from human and animal studies suggest that RAGE expression level and circulating sRAGE level are associated with estradiol and are correlated with CVD risk factors, such as adiposity, dyslipidemia, insulin resistance, diabetes, and metabolic syndrome. By recognizing the impact of AGEs on atherosclerosis, pharmacological strategies targeting the AGE-RAGE pathway hold therapeutic potential for CVD in menopausal women.

Renoprotective effect of atorvastatin on STZ-diabetic rats through attenuating kidney-associated dysmetabolism

Atorvastatin (AT) has been alternatively used for managing diabetic complications in clinic. However, AT-related therapeutic potentiality remains relatively unexplored, especially in diabetic nephropathy. This study aimed to investigate the underlying potentiality that AT exerted on anti-diabetic nephropathy role against streptozotocin (STZ)-induced kidney injury in rats. STZ-diabetic rats were intragastrically administered with AT (10, 20 mg/kg/d) for consecutive 8 weeks. The effects of AT on body weight, levels of blood glucose, lipometabolism, redox state, cellular metabolism, regulator factor and kidney morphological changes were monitored by routine measurement, biochemistry assay, PT-PCR analysis, ultrastructural and pathological observations, respectively. Compared with the diabetic nephropathy rats, AT elevated the body weight of diabetic nephropathy rats (P<0.01), effectively reduced the blood glucose level (P<0.01), increased the levels of insulin and high-density lipoprotein cholesterol (HDL-C) in plasma (P<0.01), and decreased the 24 h urine protein content and serum concentrations of low-density lipoprotein cholesterol (LDL-C) (P<0.01). Meanwhile, increase in kidney tissue, the intrarenal activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were enhanced, while the malonaldehyde (MDA) content was reduced (P<0.01). In addition, the expression of transforming growth factor beta 1 (TGF-β1) mRNA in kidney tissue was notably down-regulated (P<0.01). Furthermore, AT contributed to alleviating STZ-induced nephritic damages in rats. These results demonstrate that atorvastatin exerts the effective protective role against kidney injuries of STZ-induced diabetic nephropathy rat, which the underlying mechanisms are associated with ameliorating glyco, lipometabolism, enhancing antioxidant ability, and mitigating renal damage.

Novel CoQ10 antidiabetic mechanisms underlie its positive effect: modulation of insulin and adiponectine receptors, Tyrosine kinase, PI3K, glucose transporters, sRAGE and visfatin in insulin resistant/diabetic rats

As a nutritional supplement, coenzyme Q10 (CoQ10) was tested previously in several models of diabetes and/or insulin resistance (IR); however, its exact mechanisms have not been profoundly explicated. Hence, the objective of this work is to verify some of the possible mechanisms that underlie its therapeutic efficacy. Moreover, the study aimed to assess the potential modulatory effect of CoQ10 on the antidiabetic action of glimebiride. An insulin resistance/type 2 diabetic model was adopted, in which rats were fed high fat/high fructose diet (HFFD) for 6 weeks followed by a single sub-diabetogenic dose of streptozotocin (35 mg/kg, i.p.). At the end of the 7^th week animals were treated with CoQ10 (20 mg/kg, p.o) and/or glimebiride (0.5 mg/kg, p.o) for 2 weeks. CoQ10 alone opposed the HFFD effect and increased the hepatic/muscular content/activity of tyrosine kinase (TK), phosphatidylinositol kinase (PI3K), and adiponectin receptors. Conversely, it decreased the content/activity of insulin receptor isoforms, myeloperoxidase and glucose transporters (GLUT4; 2). Besides, it lowered significantly the serum levels of glucose, insulin, fructosamine and HOMA index, improved the serum lipid panel and elevated the levels of glutathione, sRAGE and adiponectin. On the other hand, CoQ10 lowered the serum levels of malondialdehyde, visfatin, ALT and AST. Surprisingly, CoQ10 effect surpassed that of glimepiride in almost all the assessed parameters, except for glucose, fructosamine, TK, PI3K, and GLUT4. Combining CoQ10 with glimepiride enhanced the effect of the latter on the aforementioned parameters. Conclusion: These results provided a new insight into the possible mechanisms by which CoQ10 improves insulin sensitivity and adjusts type 2 diabetic disorder. These mechanisms involve modulation of insulin and adiponectin receptors, as well as TK, PI3K, glucose transporters, besides improving lipid profile, redox system, sRAGE, and adipocytokines. The study also points to the potential positive effect of CoQ10 as an adds- on to conventional antidiabetic therapies.

Statins stimulate the production of a soluble form of the receptor for advanced glycation end products

The beneficial effects of statin therapy in the reduction of cardiovascular pathogenesis, atherosclerosis, and diabetic complications are well known. The receptor for advanced glycation end products (RAGE) plays an important role in the progression of these diseases. In contrast, soluble forms of RAGE act as decoys for RAGE ligands and may prevent the development of RAGE-mediated disorders. Soluble forms of RAGE are either produced by alternative splicing [endogenous secretory RAGE (esRAGE)] or by proteolytic shedding mediated by metalloproteinases [shed RAGE (sRAGE)]. Therefore we analyzed whether statins influence the production of soluble RAGE. Lovastatin treatment of either mouse alveolar epithelial cells endogenously expressing RAGE or HEK cells overexpressing RAGE caused induction of RAGE shedding, but did not influence secretion of esRAGE from HEK cells overexpressing esRAGE. Lovastatin-induced secretion of sRAGE was also evident after restoration of the isoprenylation pathway, demonstrating a correlation of sterol biosynthesis and activation of RAGE shedding. Lovastatin-stimulated induction of RAGE shedding was completely abolished by a metalloproteinase ADAM10 inhibitor. We also demonstrate that statins stimulate RAGE shedding at low physiologically relevant concentrations. Our results show that statins, due to their cholesterol-lowering effects, increase the soluble RAGE level by inducing RAGE shedding, and by doing this, might prevent the development of RAGE-mediated pathogenesis.

Dyslipidemia, kidney disease, and cardiovascular disease in diabetic patients

This article reviews the relationship between dyslipidemia, chronic kidney disease, and cardiovascular diseases in patients with diabetes. Diabetes mellitus is associated with complications in the cardiovascular and renal system, and is increasing in prevalence worldwide. Modification of the multifactorial risk factors, in particular dyslipidemia, has been suggested to reduce the rates of diabetes-related complications. Dyslipidemia in diabetes is a condition that includes hypertriglyceridemia, low high-density lipoprotein levels, and increased small and dense low-density lipoprotein particles. This condition is associated with higher cardiovascular risk and mortality in diabetic patients. Current treatment guidelines focus on lowering the low-density lipoprotein cholesterol level; multiple trials have confirmed the cardiovascular benefits of treatment with statins. Chronic kidney disease also contributes to dyslipidemia, and dyslipidemia in turn is related to the occurrence and progression of diabetic nephropathy. Different patterns of dyslipidemia are associated with different stages of diabetic nephropathy. Some trials have shown that treatment with statins not only decreased the risk of cardiovascular events, but also delayed the progression of diabetic nephropathy. However, studies using statins as the sole treatment of hyperlipidemia in patients on dialysis have not shown benefits with respect to cardiovascular risk. Diabetic patients with nephropathy have a higher risk of cardiovascular events than those without nephropathy. The degree of albuminuria and the reduction in estimated glomerular filtration rate are also correlated with the risk of cardiovascular events. Treatment with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers to reduce albuminuria in diabetic patients has been shown to decrease the risk of cardiovascular morbidity and mortality.

Cholesterol Contributes to Diabetic Nephropathy through SCAP-SREBP-2 Pathway

Diabetic nephropathy (DN) has been associated with the presence of lipid deposition. We hypothesized that the disruption of intracellular cholesterol feedback may contribute to DN. Diabetes was induced by high fat/sucrose diet and low-dose intraperitoneal injection of streptozocin (STZ) in male Sprague-Dawley rats. Then diabetic rats were randomly divided into two groups: untreated diabetic group (DM) and atorvastatin-treated group (DM + AT). We found that the levels of serum blood urea nitrogen and creatinine, as well as 24-hour urine protein and urinary neutrophil gelatinase-associated lipocalin, were significantly increased in diabetic rats. This result indicated that the diabetic rats suffered from functional renal damage. We also observed lipid droplet accumulation and increase in 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), low density lipoprotein receptor (LDLr), sterol regulatory element binding protein-2 (SREBP-2), and SREBP-cleavage activating protein (SCAP) in the kidneys of diabetic rats. However, atorvastatin ameliorated renal lipid accumulation and improved the renal function of diabetic rats despite an increase in mRNA and protein expressions of HMG-CoAR, LDLr, and SREBP-2. These results demonstrated that intracellular cholesterol feedback regulation is disrupted in rats with type 2 diabetes, thereby causing renal cholesterol accumulation. Atorvastatin ameliorated renal cholesterol accumulation by reducing renal cholesterol synthesis.

Serum advanced glycation end-products and receptors as prognostic biomarkers in diabetics undergoing coronary artery stent implantation

BACKGROUND

This study investigated the impact of elevated glycated albumin (GA) and reduced soluble receptor for advanced glycation end-products (sRAGE) and endogenous secretory receptor for advanced glycation end-products (esRAGE) levels in serum on the severity of albuminuria, occurrence of contrast-induced acute kidney injury (CI-AKI) and 1-year clinical outcome in type 2 diabetic patients undergoing sirolimus-eluting stent-based percutaneous coronary intervention.

METHODS

We compared serum levels of GA, sRAGE, esRAGE, and glycosylated hemoglobin (HbA1c), occurrence of CI-AKI, and major adverse cardiac events at 1-year clinical follow-up in 3 groups of type 2 diabetes based on 24-hour urinary albumin excretion: I = normoalbuminuria (< 30 mg; n = 190); II = microalbuminuria (30-300 mg; n = 102); and III = macroalbuminuria (≥ 300 mg; n = 86).

RESULTS

Serum levels of GA and HbA1c increased step-wise from group I to III, and serum levels of sRAGE and esRAGE were decreased in the groups with albuminuria, with the lowest values in those with microalbuminuria. GA (Pearson's r = 0.264; P < 0.001), sRAGE (Pearson's r = -0.210; P < 0.001), esRAGE (Pearson's r = -0.145; P = 0.04), and HbA1c (Pearson's r = 0.214; P < 0.001) correlated significantly with urinary albumin excretion. After adjusting for confounding factors, GA, sRAGE, esRAGE, and albuminuria status remained independently associated with both CI-AKI and 1-year major adverse cardiac events.

CONCLUSIONS

Elevated GA and reduced sRAGE and esRAGE levels in serum are associated with severity of albuminuria and postprocedural CI-AKI, and exert a negative impact on 1-year clinical outcome in patients with type 2 diabetes undergoing percutaneous coronary intervention with sirolimus-eluting stent implantation.

Glycated albumin is superior to hemoglobin A1c for evaluating the presence and severity of coronary artery disease in type 2 diabetic patients

OBJECTIVES

This study aimed to compare the value of serum glycated albumin (GA) level versus glycated hemoglobin A(1c) (HbA(1c)) for evaluating the presence and severity of coronary artery disease (CAD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Serum GA and blood HbA(1c) levels were measured in 829 consecutive T2DM patients with or without angiographically documented significant CAD (≥70% diameter stenosis).

RESULTS

Serum GA levels were higher in diabetic patients with significant CAD than in those without (20.57 ± 4.23 vs. 19.00 ± 4.48%; p < 0.001), but HbA(1c) was similar in the two groups (7.74 ± 1.34 vs. 7.51 ± 1.37% p > 0.05). Compared to HbA(1c), GA correlated more closely with the sum of significant stenotic lesions (r = 0.275, p < 0.001 and r = 0.092, p = 0.019) and the extent index (r = 0.375, p < 0.001 and r = 0.091, p = 0.019). The area under the curve of GA was larger than that of HbA(1c) for detecting the presence of significant CAD (0.637 vs. 0.568; p = 0.046) and 3-vessel disease (0.620 vs. 0.536; p = 0.039). GA, but not HbA(1c), was independently associated with significant CAD.

CONCLUSIONS

Serum GA level is a better indicator than HbA(1c) for evaluating the presence and severity of CAD and predicting major adverse cardiac events in patients with T2DM.