Suppression of RAGE as a basis of simvastatin-dependent plaque stabilization in type 2 diabetes

Uremic Toxicity of Advanced Glycation End Products in CKD

Advanced glycation end products (AGEs), a heterogeneous group of compounds formed by nonenzymatic glycation reactions between reducing sugars and amino acids, lipids, or DNA, are formed not only in the presence of hyperglycemia, but also in diseases associated with high levels of oxidative stress, such as CKD. In chronic renal failure, higher circulating AGE levels result from increased formation and decreased renal clearance. Interactions between AGEs and their receptors, including advanced glycation end product-specific receptor (RAGE), trigger various intracellular events, such as oxidative stress and inflammation, leading to cardiovascular complications. Although patients with CKD have a higher burden of cardiovascular disease, the relationship between AGEs and cardiovascular disease in patients with CKD is not fully characterized. In this paper, we review the various deleterious effects of AGEs in CKD that lead to cardiovascular complications and the role of these AGEs in diabetic nephropathy. We also discuss potential pharmacologic approaches to circumvent these deleterious effects by reducing exogenous and endogenous sources of AGEs, increasing the breakdown of existing AGEs, or inhibiting AGE-induced inflammation. Finally, we speculate on preventive and therapeutic strategies that focus on the AGE-RAGE axis to prevent vascular complications in patients with CKD.

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.

Pharmacologic Approaches Against Advanced Glycation End Products (AGEs) in Diabetic Cardiovascular Disease

Context:

Advanced Glycation End-Products (AGEs) are signaling proteins associated to several vascular and neurological complications in diabetic and non-diabetic patients. AGEs proved to be a marker of negative outcome in both diabetes management and surgical procedures in these patients. The reported role of AGEs prompted the development of pharmacological inhibitors of their effects, giving rise to a number of both preclinical and clinical studies. Clinical trials with anti-AGEs drugs have been gradually developed and this review aimed to summarize most relevant reports.

Evidence Acquisition:

Evidence acquisition process was performed using PubMed and ClinicalTrials.gov with manually checked articles.

Results:

Pharmacological approaches in humans include aminoguanidine, pyridoxamine, benfotiamine, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, statin, ALT-711 (alagebrium) and thiazolidinediones. The most recent promising anti-AGEs agents are statins, alagebrium and thiazolidinediones. The role of AGEs in disease and new compounds interfering with their effects are currently under investigation in preclinical settings and these newer anti-AGEs drugs would undergo clinical evaluation in the next years. Compounds with anti-AGEs activity but still not available for clinical scenarios are ALT-946, OPB-9195, tenilsetam, LR-90, TM2002, sRAGE and PEDF.

Conclusions:

Despite most studies confirm the efficacy of these pharmacological approaches, other reports produced conflicting evidences; in almost any case, these drugs were well tolerated. At present, AGEs measurement has still not taken a precise role in clinical practice, but its relevance as a marker of disease has been widely shown; therefore, it is important for clinicians to understand the value of new cardiovascular risk factors. Findings from the current and future clinical trials may help in determining the role of AGEs and the benefits of anti-AGEs treatment in cardiovascular disease.

AGEs and chronic subclinical inflammation in diabetes: disorders of immune system

Chronic subclinical inflammation represents a risk factor of type 2 diabetes and several diabetes complications, including neuropathy and atherosclerosis including macro-vasculopathy and micro-vasculopathy. However, the inflammatory response in the diabetic wound was shown to be remarkably hypocellular, unregulated and ineffective. Advanced glycation end products (AGEs) and one of its receptors, RAGE, were involved in inducing chronic immune imbalance in diabetic patients. Such interactions attracts immune cell into diffused glycated tissue and activates these cells to induce inflammatory damage, but disturbs the normal immune rhythm in diabetic wound. Traditional measurements of AGEs are high-performance liquid chromatography and immunohistochemistry staining, but their application faces the limitations including complexity, cost and lack of reproducibility. A new noninvasive method emerged in 2004, using skin autofluorescence as indicator for AGEs accumulation. It had been reported to be informative in evaluating the chronic risk of diabetic patients. Studies have indicated therapeutic potentials of anti-AGE recipes. These recipes can reduce AGE absorption/de novo formation, block AGE-RAGE interaction and arrest downstream signaling after RAGE activation.

Plasma advanced glycation end products are associated with incident cardiovascular events in individuals with type 2 diabetes: a case-cohort study with a median follow-up of 10 years (EPIC-NL)

Experimental data suggest a role for advanced glycation end products (AGEs) in cardiovascular disease (CVD), particularly in type 2 diabetes (T2DM). However, epidemiological evidence of an association between high plasma AGEs and increased cardiovascular risk remains inconclusive. Therefore, in a case-cohort study comprising 134 cardiovascular case subjects and a random subcohort of 218 individuals (including 65 cardiovascular case subjects), all with T2DM and nested in the European Prospective Investigation into Cancer and Nutrition in the Netherlands (EPIC-NL) study, plasma levels of protein-bound Nε-(carboxymethyl)lysine, Nε-(carboxyethyl)lysine, and pentosidine were measured with liquid chromatography. AGEs were loge-transformed, combined in a z-score, and the association with incident cardiovascular events was analyzed with Cox proportional hazard regression, adapted for case-cohort design (Prentice method). After multivariable adjustment (sex, age, cohort status, diabetes duration, total cholesterol to HDL-cholesterol ratio, smoking, systolic blood pressure, BMI, blood pressure-, cholesterol- and glucose-lowering treatment, prior cardiovascular events, and triglycerides), higher plasma AGE z-scores were associated with higher risk of incident cardiovascular events in individuals without prior cardiovascular events (hazard ratio 1.31 [95% CI: 1.06-1.61]). A similar trend was observed in individuals with prior cardiovascular events (1.37 [0.63-2.98]). In conclusion, high plasma AGEs were associated with incident cardiovascular events in individuals with T2DM. These results underline the potential importance of AGEs in development of CVD.

Carotid atherosclerotic plaque stenosis: the stabilizing role of statins

BACKGROUND

Both pathophysiology and treatments of carotid atherosclerotic plaque stenosis represent two interesting fields of strong scientific investigation. Among different drugs, safety and efficacy of statin treatment have been widely investigated and proved.

MATERIALS AND METHODS

This narrative review is based on the material searched for and obtained via MEDLINE and PubMed up to March 2014. The search terms we used were: 'carotid plaque, intima-media thickness, plaque burden, stroke' in combination with 'statins, pleiotropic effects, HMG-CoA reductase inhibitors, lipid-lowering drugs'.

RESULTS

Carotid stenosis represents both a useful parameter to evaluate the atherosclerotic burden and a target for therapeutic (medical or surgical) decisions. Statins do not only improve the lipid profile, but also induce some 'pleiotropic' anti-inflammatory activities that contribute to carotid plaque stabilization. Statin-mediated protective activities are under active investigation at subclinical levels with the potential benefit of advanced imaging techniques. However, considering that some new techniques (excepted B-mode ultrasound) remain quite expensive, they can have for the moment an important role in research, but not in the clinical field.

CONCLUSIONS

Emerging evidence suggests that statin treatment improves carotid atherosclerosis, inducing a partial regression of plaque inflammation and size. Innovative imaging techniques might also ameliorate the identification of patients at high risk of cerebrovascular and coronary events, for which preventive statin treatments might be essential.

Glyoxalase 1 overexpression does not affect atherosclerotic lesion size and severity in ApoE-/- mice with or without diabetes

AIMS

Advanced glycation end-products (AGEs) and their precursors have been associated with the development of atherosclerosis. We recently discovered that glyoxalase 1 (GLO1), the major detoxifying enzyme for AGE precursors, is decreased in ruptured human plaques, and that levels of AGEs are higher in rupture-prone plaques. We here investigated whether overexpression of human GLO1 in ApoE(-/-) mice could reduce the development of atherosclerosis.

METHODS AND RESULTS

We crossed C57BL/6 ApoE(-/-) mice with C57BL/6 GLO1 overexpressing mice (huGLO1(+/-)) to generate ApoE(-/-) (n = 16) and ApoE(-/-) huGLO1(+/-) (n = 20) mice. To induce diabetes, we injected a subset with streptozotocin (STZ) to generate diabetic ApoE(-/-) (n = 8) and ApoE(-/-) huGLO1(+/-) (n = 13) mice. All mice were fed chow and sacrificed at 25 weeks of age. The GLO1 activity was three-fold increased in huGLO1(+/-) aorta, but aortic root lesion size and phenotype did not differ between mice with and without huGLO1(+/-) overexpression. We detected no differences in gene expression in aortic arches, in AGE levels and cytokines, in circulating cells, and endothelial function between ApoE(-/-) mice with and without huGLO1(+/-) overexpression. Although diabetic mice showed decreased GLO1 expression (P < 0.05) and increased lesion size (P < 0.05) in comparison with non-diabetic mice, GLO1 overexpression also did not affect the aortic root lesion size or inflammation in diabetic mice.

CONCLUSION

In ApoE(-/-) mice with or without diabetes, GLO1 overexpression did not lead to decreased atherosclerotic lesion size or systemic inflammation. Increasing GLO1 levels does not seem to be an effective strategy to reduce glycation in atherosclerotic lesions, likely due to increased AGE formation through GLO1-independent mechanisms.

Controlling the receptor for advanced glycation end-products to conquer diabetic vascular complications

Diabetic vascular complications, such as cardiovascular disease, stroke and microangiopathy, lead to high rates of morbidity and mortality in patients with long‐term diabetes. Extensive intracellular and extracellular formation of advanced glycation end‐products (AGE) is considered a causative factor in vascular injuries in diabetes. Receptor‐dependent mechanisms are involved in AGE‐induced cellular dysfunction and tissue damage. The receptor for AGE (RAGE), originally an AGE‐binding receptor, is now recognized as a member of pattern‐recognition receptors and a pro‐inflammatory molecular device that mediates danger signals to the body. Previous animal studies have shown RAGE dependent of diabetic vascular injuries. Prophylactic and therapeutic strategies focusing on RAGE and its ligand axis will be of great importance in conquering diabetic vascular complications. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00191.x, 2012)

Methylglyoxal and glyoxalase I in atherosclerosis

Cardiovascular disease, caused predominantly by atherosclerotic plaque rupture, remains one of the leading causes of death. However, the mechanism of plaque rupture remains largely unknown. Recent studies have linked high metabolic activity in inflamed atherosclerotic plaques to the development of plaque rupture. AGEs (advanced glycation end-products) are known to be formed as a result of high metabolic activity and are higher in rupture-prone than stable plaques. Furthermore, AGEs seem to be more than mere markers of metabolic activity, as recent studies have elucidated that AGEs and their major precursor, MG (methylglyoxal), may have an important role in the progression of atherosclerosis and plaque rupture. MG can be detoxified by Glo1 (glyoxalase I), thereby preventing the accumulation of MG and MG-derived AGEs. In the present review, data concerning MG, Glo1 and AGEs in the context of plaque phenotype are discussed.

Is there a clinical role for oxidative stress biomarkers in atherosclerotic diseases?

Growing evidences suggest that reactive oxidant species (ROS) are involved in the pathogenesis and progression of the atherosclerotic diseases. Markers assessing the oxidation of LDL and formation of eicosanoids, such as isoprostanes, were among the first that were analyzed. More recently, new biomarkers, such as endogenous secretory receptor for AGEs have been suggested to play an oxidative role in specific atherosclerotic settings, such as diabetes. Unfortunately, clinical trials included cross-sectional as well as retrospective and prospective studies which provide inconclusive results. Thus, clear evidence that oxidative biomarkers can improve risk stratification in addition to the common used atherosclerotic risk factors is still lacking. The analysis of oxidative stress focused on enzymatic systems generating ROS. The most studied enzymes were NADPH oxidase and myeloperoxidase (MPO). Experimental and clinical studies suggest that both enzymes may be implicated in promoting atherosclerotic disease. Novel laboratory methodologies have been, therefore, developed to study NADPH oxidase and MPO in patients with stable atherosclerosis as well in patients with acute coronary syndrome and cerebrovascular accident. This review will report on the more relevant studies in which the clinical application of the oxidative biomarkers was evaluated.

Atorvastatin inhibits the expression of RAGE induced by advanced glycation end products on aortas in healthy Sprague-Dawley rats

BACKGROUND

Atorvastatin can downregulate the expression of receptor for advanced glycation end products (RAGE) in the aortas of diabetic rats. However, its effect on healthy rats remains unclear. The aim of this study was to observe the direct impact of atorvastatin on advanced glycation end products- (AGEs) induced RAGE expression in healthy Sprague Dawley (SD) rats.

METHODS

SD rats received AGE-BSA (20 mg/kg/day or 40 mg/kg/day), dual treatment (AGE-BSA 40 mg/kg/day and atorvastatin 20 mg/kg/day) or no treatment for 12 and 24 weeks, respectively. The deposition of AGEs and expression of RAGE in the animals' aortas were assessed by Quantitative RT-PCR, immunohistochemistry, and western-blot tests. Serum levels of AGEs were measured using ELISA.

RESULTS

AGE-BSA upregulated the serum level of AGEs, deposition of AGEs, and expression of RAGE in aortas in a time- and dose-dependent way that can accelerate the development and progression of atherosclerosis. These upregulations could be significantly attenuated by atorvastatin in the absence of its lipid-lowering effects. These data provide further evidence for the novo mechanism of atorvastatin's pleiotropic effect.

CONCLUSION

Atorvastatin has a direct inhibitory effect on AGEs-RAGE expression in healthy SD rats. These potential pleiotropic vasculoprotective effects are independent of effects on glucose and lipid control.

Simvastatin attenuates the endothelial pro-thrombotic shift in saphenous vein grafts induced by Advanced glycation endproducts

BACKGROUND

Advanced glycation endproducts (AGEs) and its receptors (RAGEs) are heterogeneous signaling proteins associated to diabetes and responsible of endothelial alterations leading to atherosclerosis progression and graft failure. The aim of this study was to investigate the role of statin in reducing AGEs related endothelial damage.

METHODS

Endothelial cell(EC) obtained from leftovers of saphenous vein grafts of non-diabetic patients were incubated with AGEs (2 and 20 μM) and subsequently treated with Simvastatin. Neutrophils (PNM) adherence, ROS production and RAGE and peroxisome proliferator-activated receptors-gamma (PPAR-γ) expression were analyzed. As clinical validation of the in vitro findings, ECs of diabetic patients in optimized glycaemic control administered with a 3 weeks Simvastatin regimen were similarly processed.

RESULTS

Simvastatin blunted the rise in PMN adhesion and ROS generation following stimulation of saphenous vein EC culture with AGEs in vitro. This effect was time dependent and was associated to an increase in PPAR-γ induction paralleled by a decrease in RAGEs expression. Parallely, data from diabetic patients administered with Simvastatin showed a similar significant reduction in PNM adhesion and ROS generation. Simvastatin treatment significantly decreased RAGEs expression in ECs from diabetic patients and determined a slight increase in PPAR-γ expression but the latter failed to reach statistical significance. Interference in the function of these two crucial pathways might be at the root of the statin antinflammatory and antithrombotic effect in the context of AGEs-associated damage.

CONCLUSIONS

Despite the recently raised warning on the use of statins in the diabetic population, this study elucidates their cornerstone position in endothelial homeostasis of saphenous grafts in patients with controlled diabetes.

Hyperoside downregulates the receptor for advanced glycation end products (RAGE) and promotes proliferation in ECV304 cells via the c-Jun N-terminal kinases (JNK) pathway following stimulation by advanced glycation end-products in vitro

Hyperoside is a major active constituent in many medicinal plants which are traditionally used in Chinese medicines for their neuroprotective, anti-inflammatory and antioxidative effects. The molecular mechanisms underlying these effects are unknown. In this study, quiescent ECV304 cells were treated in vitro with advanced glycation end products (AGEs) in the presence or absence of hyperoside. The results demonstrated that AGEs induced c-Jun N-terminal kinases (JNK) activation and apoptosis in ECV304 cells. Hyperoside inhibited these effects and promoted ECV304 cell proliferation. Furthermore, hyperoside significantly inhibited RAGE expression in AGE-stimulated ECV304 cells, whereas knockdown of RAGE inhibited AGE-induced JNK activation. These results suggested that AGEs may promote JNK activation, leading to viability inhibition of ECV304 cells via the RAGE signaling pathway. These effects could be inhibited by hyperoside. Our findings suggest a novel role for hyperoside in the treatment and prevention of diabetes.

Potential of the angiotensin receptor blockers (ARBs) telmisartan, irbesartan, and candesartan for inhibiting the HMGB1/RAGE axis in prevention and acute treatment of stroke

Stroke is a major cause of mortality and disability worldwide. The main cause of stroke is atherosclerosis, and the most common risk factor for atherosclerosis is hypertension. Therefore, antihypertensive treatments are recommended for the prevention of stroke. Three angiotensin receptor blockers (ARBs), telmisartan, irbesartan and candesartan, inhibit the expression of the receptor for advanced glycation end-products (RAGE), which is one of the pleiotropic effects of these drugs. High mobility group box 1 (HMGB1) is the ligand of RAGE, and has been recently identified as a lethal mediator of severe sepsis. HMGB1 is an intracellular protein, which acts as an inflammatory cytokine when released into the extracellular milieu. Extracellular HMGB1 causes multiple organ failure and contributes to the pathogenesis of hypertension, hyperlipidemia, diabetes mellitus, atherosclerosis, thrombosis, and stroke. This is the first review of the literature evaluating the potential of three ARBs for the HMGB1-RAGE axis on stroke therapy, including prevention and acute treatment. This review covers clinical and experimental studies conducted between 1976 and 2013. We propose that ARBs, which inhibit the HMGB1/RAGE axis, may offer a novel option for prevention and acute treatment of stroke. However, additional clinical studies are necessary to verify the efficacy of ARBs.

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.

Plasma levels of soluble receptor for advanced glycation end products and coronary atherosclerosis: possible correlation with clinical presentation

Receptor for Advanced Glycation End-products (RAGE) is a multi-ligand receptor ubiquitous present on epithelial, neuronal, vascular and inflammatory cells, usually expressed at low levels in homeostasis and to increased degrees at sites of stress or injury. The aim of the present study was to evaluate sRAGE plasma levels in patients with Acute Coronary Syndrome (ACS) and to assess its diagnostic efficacy in identification of patients with acute events. Plasma levels of sRAGE were determined in 860 patients with Coronary Artery Disease (CAD): 530 patients presented stable angina and 330 were observed during acute ischemic event (147 with unstable angina and 183 with myocardial infarction). sRAGE plasma levels were significantly lower in patients with ACS than in patients with stable angina: [median 584 pg/mL (IQR: 266–851 pg/mL) in MI patients, median 769 pg/mL (IQR: 394–987 pg/mL) in patients with unstable angina, median 834 pg/mL (IQR 630–1005 pg/mL) in patients with stable angina; P < 0.001]. sRAGE levels did not differ among ACS patients stratified by the extent of coronary artery disease. In conclusion, this study confirm the role of sRAGE in activation and progression of inflammatory process and suggests the possibility that sRAGE can be considered an indicator of destabilization of vulnerable plaque.

Current therapeutic interventions in the glycation pathway: evidence from clinical studies

The increased formation of advanced glycation endproducts (AGEs) constitutes a potential mechanism of hyperglycaemia-induced micro- and macrovascular disease in diabetes. In vitro and animal experiments have shown that various interventions can inhibit formation and/or actions of AGEs, in particular the specific AGE inhibitor aminoguanidine and the AGEs crosslink breaker alagebrium, and the B vitamins pyridoxamine and thiamine, and the latter's synthetic derivative, benfotiamine. The potential clinical value of these interventions, however, remains to be established. The present review provides, from the clinical point of view, an overview of current evidence on interventions in the glycation pathway relating to (i) the clinical benefits of specific AGE inhibitors and AGE breakers and (ii) the potential AGE-inhibiting effects of therapies developed for purposes unrelated to the glycation pathway. We found that safety and/or efficacy in clinical studies with the specific AGE inhibitor, aminoguanidine and the AGE breaker, alagebrium, appeared to be a concern. The clinical evidence on the potential AGE-inhibiting effects of B vitamins is still limited. Finally, current evidence for AGE inhibition by therapies developed for purposes unrelated to glycation is limited due to a large heterogeneity in study designs and/or measurement techniques, which have often been sub-optimal. We conclude that, clinical evidence on interventions to inhibit formation and/or action of AGEs is currently weak and unconvincing.

Perioperative statin therapy for improving outcomes during and after noncardiac vascular surgery

BACKGROUND

Patients undergoing vascular surgery are a high-risk population with widespread atherosclerosis, an adverse cardiovascular risk profile and often multiple co-morbidities. Postoperative cardiovascular complications, including myocardial infarct (MI), are common. Statins are the medical treatment of choice to reduce high cholesterol levels. Evidence is accumulating that patients taking statins at the time of surgery are protected against a range of perioperative complications, but the specific benefits for patients undergoing noncardiac vascular surgery are not clear.

OBJECTIVES

We examined whether short-term statin therapy, commenced before or on the day of noncardiac vascular surgery and continuing for at least 48 hours afterwards, improves patient outcomes including the risk of complications, pain, quality of life and length of hospital stay. We also examined whether the effect of statin therapy on these outcomes changes depending on the dose of statin received.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 7), MEDLINE via Ovid SP (1966 to August 2012), EMBASE via Ovid SP (1966 to August 2012), CINAHL via EBSCO host (1966 to August 2012) and ISI Web of Science (1946 to July 2012) without any language restriction. We used a combination of free text search and controlled vocabulary search. The results were limited to randomized controlled clinical trials (RCTs). We conducted forwards and backwards citation of key articles and searched two clinical trial Websites for ongoing trials (www.clinicaltrials.gov and http://www.controlled-trials.com).

SELECTION CRITERIA

We included RCTs that had compared short-term statin therapy, either commenced de novo or with existing users randomly assigned to different dosages, in adult participants undergoing elective and emergency noncardiac arterial surgery, including both open and endovascular procedures. We defined short-term as commencing before or on the day of surgery and continuing for at least 48 hours afterwards.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data, including information on adverse events. We contacted study authors for additional information. We performed separate analyses for the comparisons of statin with placebo/no treatment and between different doses of statin. We presented results as pooled risk ratios (RRs) with 95% confidence intervals (CIs) based on random-effects models (inverse variance method). We employed the Chi(2) test and calculated the I(2) statistic to investigate study heterogeneity.

MAIN RESULTS

We identified six eligible studies in total. The six Included studies were generally of high quality, but the largest eligible study was excluded because of concerns about its validity. Study populations were statin naive, which led to a considerable loss of eligible participants.Five RCTs compared statin use with placebo or standard care. We pooled results from three studies, with a total of 178 participants, for mortality and non-fatal event outcomes. In the statin group, 7/105 (6.7%) participants died within 30 days of surgery, as did 10/73 (13.7%) participants in the control group. Only one death in each group was from cardiovascular causes, with an incidence of 0.95% in statin participants and 1.4% in control participants, respectively. All deaths occurred in a single study population, and so effect estimates were derived from one study only. The risk ratio (RR) of all-cause mortality in statin users showed a non-significant decrease in risk (RR 0.73, 95% CI 0.31 to 1.75). For cardiovascular death, the risk ratio was 1.05 (95% CI 0.07 to 16.20). Non-fatal MI within 30 days of surgery was reported in three studies and occurred in 4/105 (3.8%) participants in the statin group and 8/73 (11.0%) participants receiving placebo, for a non-significant decrease in risk (RR 0.47, 95% CI 0.15 to 1.52). Several studies reported muscle enzyme levels as safety measures, but only three (with a total of 188 participants) reported explicitly on clinical muscle syndromes, with seven events reported and no significant difference found between statin users and controls (RR 0.94, 95% CI 0.24 to 3.63). The only participant-reported outcome was nausea in one small study,with no significant difference in risk between groups.Two studies compared different doses of atorvastatin, with a total of 145 participants, but reported data were not sufficient to allow us to determine the effect of higher doses on any outcome.

AUTHORS' CONCLUSIONS

Evidence was insufficient to allow review authors to conclude that statin use resulted in either a reduction or an increase in any of the outcomes examined. The existing body of evidence leaves questions about the benefits of perioperative use of statins for vascular surgery unanswered. Widespread use of statins in the target population means that it may now be difficult for researchers to undertake the large RCTs needed to demonstrate any effect on the incidence of postoperative cardiovascular events. However, participant-reported outcomes have been neglected and warrant further study.

Simvastatin suppresses vascular inflammation and atherosclerosis in ApoE(-/-) mice by downregulating the HMGB1-RAGE axis

AIM

High mobility group box protein 1 (HMGB1) and receptor for the advanced glycation end product (RAGE) play pivotal roles in vascular inflammation and atherosclerosis. The aim of this study was to determine whether the HMGB1-RAGE axis was involved in the actions of simvastatin on vascular inflammation and atherosclerosis in ApoE(-/-) mice.

METHODS

Five-week old ApoE(-/-) mice and wild-type C57BL/6 mice were fed a Western diet. At 8 weeks of age, ApoE(-/-) mice were administered simvastatin (50 mg·kg(-1)·d(-1)) or vehicle by gavage, and the wild-type mice were treated with vehicle. The mice were sacrificed at 11 weeks of age, and the atherosclerotic lesions in aortic sinus were assessed with Oil Red O staining. Macrophage migration was determined with scanning EM and immunohistochemistry. Human umbilical vein endothelial cells (HUVECs) were used for in vitro study. Western blots were used to quantify the protein expression of HMGB1, RAGE, vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1).

RESULTS

Vehicle-treated ApoE(-/-) mice exhibited significant increases in aortic inflammation and atherosclerosis as well as enhanced expression of HMGB1, RAGE, VCAM-1, and MCP-1 in aortic tissues as compared to the wild-type mice. Furthermore, serum total cholesterol, triglyceride and LDL levels were markedly increased, while serum HDL level was decreased in vehicle-treated ApoE(-/-) mice. Administration with simvastatin in ApoE(-/-) mice markedly attenuated the vascular inflammation and atherosclerotic lesion area, and decreased the aortic expression of HMGB1, RAGE, VCAM-1, and MCP-1. However, simvastatin did not affect the abnormal levels of serum total cholesterol, triglyceride, LDL and HDL in ApoE(-/-) mice. Exposure of HUVECs to HMGB1 (100 ng/mL) markedly increased the expression of HMGB1, RAGE and VCAM-1, whereas pretreatment of the cells with simvastatin (10 μmol/L) blocked the HMGB1-caused changes.

CONCLUSION

Simvastatin inhibits vascular inflammation and atherosclerosis in ApoE(-/-) mice, which may be mediated through downregulation of the HMGB1-RAGE axis.

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.

Inverse Association between Cardiac Troponin-I and Soluble Receptor for Advanced Glycation End Products in Patients with Non-ST-Segment Elevation Myocardial Infarction

Interaction of advanced glycation end products (AGEs) with the receptor for advanced AGEs (RAGE) results in activation of nuclear factor kappa-B, release of cytokines, expression of adhesion molecules, and induction of oxidative stress. Oxygen radicals are involved in plaque rupture contributing to thromboembolism, resulting in acute coronary syndrome (ACS). Thromboembolism and the direct effect of oxygen radicals on myocardial cells cause cardiac damage that results in the release of cardiac troponin-I (cTnI) and other biochemical markers. The soluble RAGE (sRAGE) compete with RAGE for binding with AGE, thus functioning as a decoy and exerting a cytoprotective effect. Low levels of serum sRAGE would allow unopposed serum AGE availability for binding with RAGE, resulting in the generation of oxygen radicals and proinflammatory molecules that have deleterious consequences and promote myocardial damage. sRAGE may stabilize atherosclerotic plaques. It is hypothesized that low levels of sRAGE are associated with high levels of serum cTnI in patients with ACS. The main objective of the study was to determine whether low levels of serum sRAGE are associated with high levels of serum cTnI in ACS patients. The serum levels of sRAGE and cTnI were measured in 36 patients with non-ST-segment elevation myocardial infarction (NSTEMI) and 30 control subjects. Serum levels of sRAGE were lower in NSTEMI patients (802.56 ± 39.32 pg/mL) as compared with control subjects (1311.43 ± 66.92 pg/mL). The levels of cTnI were higher in NSTEMI patients (2.18 ± 0.33 μg/mL) as compared with control subjects (0.012 ± 0.001 μg/mL). Serum sRAGE levels were negatively correlated with the levels of cTnI. In conclusion, the data suggest that low levels of serum sRAGE are associated with high serum levels of cTnI and that there is a negative correlation between sRAGE and cTnI.

Pravastatin inhibits advanced glycation end products (AGEs)-induced proximal tubular cell apoptosis and injury by reducing receptor for AGEs (RAGE) level

Advanced glycation end products (AGEs) and their receptor (RAGE) axis play a role in diabetic nephropathy. Statins have been shown to ameliorate renal function and reduce proteinuria in patients with chronic kidney disease. However, the effects of statin on AGEs-induced tubular cell damage remain unknown. We examined here whether and how pravastatin could block the AGEs-RAGE-elicited tubular cell injury in vitro. Gene expression level was evaluated by real-time reverse-transcription polymerase chain reactions. Reactive oxygen species (ROS) generation was measured with dihydroethidium staining. Apoptosis was analyzed in an enzyme-linked immunosorbent assay. Asymmetric dimethylarginine (ADMA) expression was evaluated by immunostaining. Pravastatin dose-dependently inhibited the AGEs-induced up-regulation of RAGE mRNA level, ROS generation and apoptosis in human renal proximal tubular cells. Further, AGEs decreased mRNA level of dimethylarginine dimethylaminohydrolase-2, an enzyme that mainly degrades asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase and subsequently increased ADMA generation in tubular cells, both of which were also prevented by pravastatin. Geranylgeranyl pyrophosphate (GGPP) treatment blocked all of the effects of pravastatin on tubular cells. We found that rosuvastatin also significantly blocked the AGEs-induced increase in RAGE mRNA level and ROS generation, both of which were prevented by GGPP. Our present study suggests that pravastatin could inhibit the AGEs-induced apoptosis and ADMA generation in tubular cells by suppressing RAGE expression probably via inhibition of GGPP synthesis. Pravastatin may exert beneficial effects on tubular damage in diabetic nephropathy by blocking the AGEs-RAGE axis.

Receptor for AGE (RAGE): signaling mechanisms in the pathogenesis of diabetes and its complications

The receptor for advanced glycation endproducts (RAGE) was first described as a signal transduction receptor for advanced glycation endproducts (AGEs), the products of nonenzymatic glycation and oxidation of proteins and lipids that accumulate in diabetes and in inflammatory foci. The discovery that RAGE was a receptor for inflammatory S100/calgranulins and high mobility group box 1 (HMGB1) set the stage for linking RAGE to both the consequences and causes of types 1 and 2 diabetes. Recent discoveries regarding the structure of RAGE as well as novel intracellular binding partner interactions advance our understanding of the mechanisms by which RAGE evokes pathological consequences and underscore strategies by which antagonism of RAGE in the clinic may be realized. Finally, recent data tracking RAGE in the clinic suggest that levels of soluble RAGEs and polymorphisms in the gene encoding RAGE may hold promise for the identification of patients who are vulnerable to the complications of diabetes and/or are receptive to therapeutic interventions designed to prevent and reverse the damage inflicted by chronic hyperglycemia, irrespective of its etiology.

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

OBJECTIVE

Advanced glycation end-products (AGEs) exert inflammatory and oxidative stress insults to produce diabetic nephropathy mainly through the receptor for AGEs (RAGE). This study aimed to assess the effect of atorvastatin on diabetic nephropathy via soluble RAGE (sRAGE) and RAGE expressions in the rat kidney.

METHODS

Thirty-two male Sprague-Dawley rats were divided into four groups based on the presence or absence of streptozotocin-induced diabetes with or without atorvastatin treatment (10 mg/kg for 24 weeks). Serum sRAGE and glycated albumin (GA) levels were measured with enzyme-linked immunosorbent assay (ELISA) and improved bromocresol purple methods. Renal AGEs, RAGE, endogenous secretory RAGE (esRAGE), and sRAGE were determined with reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS

Mesangial expansion and microalbuminuria were aggravated in diabetic rats, and improved with atorvastatin treatment. Serum sRAGE levels were lower in diabetic than in normal rats. After atorvastatin treatment, serum and renal sRAGE levels were up-regulated, while renal RAGE expression was decreased in diabetic rats, associated with a reduction in accumulation of AGEs, though renal esRAGE mRNA expression was not significantly increased.

CONCLUSIONS

Atorvastatin exerted a beneficial effect on diabetic nephropathy with reduced AGE accumulation, down-regulating RAGE expression and up-regulating sRAGE in the kidney.

Regulation of RAGE for attenuating progression of diabetic vascular complications

Diabetic angiopathy including micro- and macroangiopathy is concerned with high rate of morbidity and mortality in patients with long-standing diabetes. Receptor for advanced glycation end products (RAGE) and its ligands have been considered as important pathogenic triggers for the progression of the vascular injuries in diabetes. The deleterious link between RAGE and diabetic angiopathy has been demonstrated in animal studies. Preventive and therapeutic strategies focusing on RAGE and its ligand axis may be of great importance in relieving diabetic vascular complications and reducing the burden of disease.

The antioxidant N-acetylcysteine promotes atherosclerotic plaque stabilization through suppression of RAGE, MMPs and NF-κB in ApoE-deficient mice

AIMS

N-acetylcysteine (NAC) has antioxidant and anti-inflammatory properties. To explore the mechanisms underlying atherosclerotic plaque stabilization induced by NAC, we examined the effects of NAC administration in apoE-deficient mice on the expression of the receptor of advanced glycation end products (RAGE), matrix metalloproteinases (MMPs) and the activation of nuclear factor kappa B (NF-κB) in atherosclerotic plaques.

METHODS

10-week-old ApoE(-/-) mice fed with atherogenic diet were treated with NAC (200 mg/kg/ day) for 8 weeks. Serum lipid, glucose and malondialdehyde (MDA) were detected. The size and composition of atherosclerotic plaques were measured by en face analysis, Movat staining, immunofluorescence and immunohistochemistry, respectively. Reactive oxygen species (ROS) generation in aortic root was tested by DHE staining. The levels of vascular cell adhesion molecule-1(VCAM-1), NF-κB, phosphor-NF-κB, I-κB, phosphor-I-κB, RAGE, MMP2 and MMP9 in descending arteries were analyzed by Western blot.

RESULTS

ApoE(-/-) mice administrated with NAC displayed reduced serum MDA level and impaired ROS generation in aortic root. However, NAC did not affect the levels of plasma glucose, lipids and the size of atherosclerotic lesions. Analysis of plaque composition showed decreased amounts of macrophages, lipid deposition, but not smooth muscle cells, and increased collagen content in atherosclerotic lesions in apoE(-/-) mice administered with NAC. Moreover, we found that NAC down-regulated the expression of VCAM-1, MMP2 and MMP9, accompanied by inhibition of NF-κB activation and reduced expression of RAGE.

CONCLUSION

In the present study, we show novel data to suggest that NAC promotes atherosclerotic plaque stabilization through suppression of RAGE, MMPs and NF-κB in apoE(-/-) mice.

Atorvastatin exerts its anti-atherosclerotic effects by targeting the receptor for advanced glycation end products

Recent studies demonstrated the beneficial role of atorvastatin in reducing the risk of cardiovascular morbidity and mortality in patients with diabetes mellitus and/or metabolic syndrome. To investigate the mechanisms underlying the anti-atheroscleroic action of atorvastatin, we examined the expression of the receptor for advanced glycation end products (RAGE) and its downstream target gene, monocyte chemoattractant protein-1 (MCP-1) using real-time PCR. In in vitro studies, exposure to high glucose or AGE induced oxidative stress and activation of the AGE/RAGE system in human umbilical vein endothelial cells. Treatment of the cells with atorvastatin significantly released the oxidative stress by restoring the levels of glutathione and inhibited the RAGE upregulation. In diabetic Goto Kakisaki (GK) rats fed with a high-fat diet for 12weeks, RAGE and MCP-1 were upregulated in the aortas, and there was a significant correlation between RAGE and MCP-1 mRNA abundance (r=0.482, P=0.031). Treatment with atorvastatin (20mg/kg qd) significantly downregulated the expression of RAGE and MCP-1. These data thus demonstrate a novel "pleiotropic" activity of atorvastatin in reducing the risk of cardiovascular diseases by targeting RAGE expression.

Ciprofloxacin inhibits advanced glycation end products-induced adhesion molecule expression on human monocytes

BACKGROUND AND PURPOSE Advanced glycation end products (AGEs) subtypes, proteins or lipids that become glycated after exposure to sugars, can induce complications in diabetes. Among the various AGE subtypes, glyceraldehyde-derived AGE (AGE-2) and glycolaldehyde-derived AGE (AGE-3) are involved in inflammation in diabetic patients; monocytes are activated by these AGEs. Ciprofloxacin (CIP), a fluorinated 4-quinolone, is often used clinically to treat infections associated with diabetis due to its antibacterial properties. It also modulates immune responses in human peripheral blood mononuclear cells (PBMC) therefore we investigated the involvement of AGEs in these effects. EXPERIMENTAL APPROACH Expression of intercellular adhesion molecule (ICAM)-1, B7.1, B7.2 and CD40 was examined by flow cytometry. The production of tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma, prostaglandin E(2) (PGE(2)) and cAMP were determined by enzyme-linked immunosorbent assay. Cyclooxygenase (COX)-2 expression was determined by Western blot analysis. Lymphocyte proliferation was determined by [(3)H]-thymidine uptake. KEY RESULTS CIP induced PGE(2) production in monocytes, irrespective of the presence of AGE-2 and AGE-3, by enhancing COX-2 expression; this led to an elevation of intracellular cAMP in monocytes. Non-selective and selective COX-2 inhibitors, indomethacin and NS398, inhibited CIP-induced PGE(2) and cAMP production. In addition, CIP inhibited AGE-2- and AGE-3-induced expressions of ICAM-1, B7.1, B7.2 and CD40 in monocytes, the production of TNF-alpha and IFN-gamma and lymphocyte proliferation in PBMC. Indomethacin, NS398 and a protein kinase A inhibitor, H89, inhibited the actions of CIP. CONCLUSIONS AND IMPLICATIONS CIP exerts immunomodulatory activity via PGE(2), implying therapeutic potential of CIP for the treatment of AGE-2- and AGE-3-induced inflammatory responses.

Implication of the RAGE-EN-RAGE axis in endometriosis

OBJECTIVE

To investigate the involvement of the receptor gene for advanced glycation (RAGE), its ligand EN-RAGE, and COX-2 in endometriosis.

METHODS

The mRNA and protein expression of the corresponding genes were determined from endometriotic cells from 28 study patients and healthy endometrial stromal cells from 20 controls by semiquantitative RT-PCR and Western blot analysis, respectively, using beta-actin as an invariant control.

RESULTS

The expression of COX-2, RAGE, and EN-RAGE was significantly increased, as evidenced by the significantly greater mRNA and protein expression in the cells of the study patients (P<0.001). Previous treatment for endometriosis did not lessen mRNA and protein expression (P<0.001).

CONCLUSION

Our findings strengthen the hypothesis of an underlying inflammation in the pathophysiology of endometriosis and suggest exploring anti-inflammatory therapies as adjunct treatment.

Lipid-lowering agents and new onset diabetes mellitus

Statin treatment (and possibly niacin when given alone or in combination with statins) appears to be associated with a slightly increased risk of new onset diabetes mellitus (NODM). However, statin induced cardiovascular disease (CVD) risk reduction is greater in patients with DM than in non-diabetic patients in several survival studies. Thus, statin treatment outweighs any potential increase in CVD risk related to NODM and in high-risk Caucasian patients present clinical practice should not change. However, the risk/benefit ratio of treatment might not be as favourable in subjects with propensity to develop DM such as the elderly and in subjects of Asian ethnicity. Colesevelam was shown to improve both glycaemic control and lipid profile in inadequately controlled T2DM and might reduce the risk for NODM. There are no data on the incidence of NODM in fibrate-treated non-diabetic patients. Prospective studies are needed to clarify these issues.

AGEs/RAGE in CKD: irreversible metabolic memory road toward CVD?

BACKGROUND

Cardiovascular disease is the major cause of death in patients with renal insufficiency, accounting for 50% of all deaths in renal replacement therapy patients. Mortality from cardiovascular diseases in these patients is approximately 9% per year, which is about 30 times the risk in the general population. So far, intensive interventions to the general risk factors, such as high LDL-cholesterol or C-reactive protein, have not been successful in improving their cardiovascular outcomes, suggesting that the beneficial effect of risk reduction may be overwhelmed by accumulated risk memorized by long-term exposure to oxidative stress during the progression of renal failure.

DESIGN

In this review, we propose that this irreversible memory effect in renal failure may be mediated by advanced glycation end-products (AGEs).

RESULTS

The generation of AGEs has been implicated to be deeply associated with increased oxidative stress. Moreover, interaction of the receptor for AGEs (RAGE) with AGEs leads to crucial biomedical pathway generating intracellular oxidative stress and inflammatory mediators, which could result in further amplification of the pathway involved in AGE generation. Several lines of evidence suggest that AGEs/RAGE axis can profoundly be involved in cardiovascular diseases. Recent advances in AGEs and RAGE measurements led us to be capable of understanding more about the role of AGEs/RAGE axis as a risk for cardiovascular diseases in patients with renal failure.

CONCLUSION

AGEs/RAGE axis could be a crucial mediator of oxidative stress in renal failure. RAGE could be not only a useful biomarker, but also a potentially therapeutic target to overcome the accumulated adverse metabolic memory in renal failure.

Atorvastatin Reduces Macrophage Accumulation in Atherosclerotic Plaques

Background and Purpose— The object of our study was to compare the effect of high-dose vs low-dose atorvastatin vs nonstatin-based treatment (cholestyramine plus sitosterol) on cell composition of carotid plaque.

Methods— We recruited 60 hypercholesterolemic patients (total cholesterol, 5.83–7.64 mmol/L) eligible for carotid endarterectomy. Three months before surgery, patients were randomized into 3 groups (n=20) receiving atorvastatin 10 mg/day (AT-10) or atorvastatin 80 mg/day (AT-80) or cholestyramine 8 g/day plus sitosterol 2.5 g/day. Analysis of cell composition was performed on endarterectomy specimens.

Results— The 3 treatments resulted in a significant reduction of total cholesterol and low-density lipoprotein cholesterol (LDL-C), although the decrease in total cholesterol and LDL-C was of smaller magnitude in the cholestyramine plus sitosterol group. The 3 regimens did not influence the levels of inflammatory markers (including high-sensitivity C-reactive protein). Macrophage content was significantly lower in the AT-10 group plaques compared to the cholestyramine plus sitosterol group. It was further reduced in the AT-80 group plaques. These differences were no longer significant after adjustment for changes in LDL-C. No difference in lymphocyte number was observed among treatments, whereas the content of smooth muscle cells was higher in the AT- 80 group. An inverse association was observed between LDL-C changes in the 3 groups and macrophage content in the plaques.

Conclusions— Short-term treatment with high-dose statin is superior to a nonstatin lipid-lowering regimen in reducing the macrophage cell content within atherosclerotic lesions, but this effect was determined by the degree of LDL-C–lowering.

Macrophages, inflammation, and insulin resistance

Obesity induces an insulin-resistant state in adipose tissue, liver, and muscle and is a strong risk factor for the development of type 2 diabetes mellitus. Insulin resistance in the setting of obesity results from a combination of altered functions of insulin target cells and the accumulation of macrophages that secrete proinflammatory mediators. At the molecular level, insulin resistance is promoted by a transition in macrophage polarization from an alternative M2 activation state maintained by STAT6 and PPARs to a classical M1 activation state driven by NF-kappaB, AP1, and other signal-dependent transcription factors that play crucial roles in innate immunity. Strategies focused on inhibiting the inflammation/insulin resistance axis that otherwise preserve essential innate immune functions may hold promise for therapeutic intervention.

Potential role of HMG CoA reductase inhibitor on oxidative stress induced by advanced glycation endproducts in vascular smooth muscle cells of diabetic vasculopathy

Advanced glycation endproducts (AGEs)-induced vascular smooth muscle cell (VSMCs) proliferation and formation of reactive oxygen species (ROS) are emerging as one of the important mechanisms of diabetic vasculopathy but little is known about the antioxidative action of HMG CoA reductase inhibitor (statin) on AGEs. We hypothesized that statin might reduce AGEs-induced intracellular ROS of VSMCs and analyzed the possible mechanism of action of statin in AGEs-induced cellular signaling. Aortic smooth muscle cell of Sprague-Dawley rat (RASMC) culture was done using the different levels of AGEs stimulation in the presence or absence of statin. The proliferation of RASMC, ROS formation and cellular signaling was evaluated and neointimal formation after balloon injury in diabetic rats was analyzed. Increasing concentration of AGEs stimulation was associated with increased RASMC proliferation and increased ROS formation and they were decreased with statin in a dose-dependent manner. Increased NF-kappaB p65, phosphorylated ERK, phosphorylated p38 MAPK, cyclooxygenase-2, and c-jun by AGEs stimulation were noted and their expression was inhibited by statin. Neointimal formation after balloon injury was much thicker in diabetic rats than the sham-treated group but less neointimal growth was observed in those treated with statin after balloon injury. Increased ROS formation, subsequent activation of MAPK system and increased VSMC proliferation may be possible mechanisms of diabetic vasculopathy induced by AGEs and statin may play a key role in the treatment of AGEs-induced diabetic atherosclerosis.

Effect of nicotine on advanced glycation end product-induced immune response in human monocytes

The up-regulation of adhesion molecule expressions on monocytes enhances cell-to-cell interactions with T cells, leading to cytokine production. Advanced glycation end products (AGEs) are modifications of proteins/lipids that become nonenzymatically glycated after contact with aldose sugars. Among various subtypes of AGEs, glyceraldehyde-derived AGE (AGE-2) and glycolaldehyde-derived AGE (AGE-3) induce the expressions of intercellular adhesion molecule-1, B7.1, B7.2, and CD40 on monocytes, the production of interferon-gamma and tumor necrosis factor-alpha, and the lymphocyte proliferation in human peripheral blood mononuclear cells. Nicotine is reported to inhibit the activation of monocytes via nicotinic acetylcholine receptor alpha7 subunit (alpha7-nAChR). In the present study, we found that nicotine inhibited the actions of AGE-2 and AGE-3. A nonselective and selective alpha7-nAChR antagonist, mecamylamine and alpha-bungarotoxin, reversed the inhibitory effects of nicotine, suggesting the involvement of alpha7-nAChR stimulation. Nicotine induced the expression of cyclooxygenase-2, prostaglandin E(2) (PGE(2)), and cAMP in the presence and absence of AGE-2 and AGE-3. PGE(2) is known to activate the EP(2)/EP(4) receptor, increasing the cAMP level and protein kinase A (PKA) activity. The actions of nicotine were reversed in part by an EP(2)-receptor antagonist, AH6809, an EP(4)-receptor antagonist, AH23848, and a PKA inhibitor, N-[2-(p-bromocinnamyl-amino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H89). These results indicate that the mechanism of action of nicotine may be partially via endogenous PGE(2) production.

In vitro effects of atorvastatin on lipopolysaccharide-induced gene expression in endometriotic stromal cells

OBJECTIVE

To investigate the in vitro effects of atorvastatin on lipopolysaccharide (LPS)-induced gene expression in endometrial-endometriotic stromal cells.

DESIGN

In vitro experimental study using flow cytometry, ELISA, semiquantitative reverse transcriptase polymerase chain reaction, and Western blot.

SETTING

Postgraduate Institute of Medical Education and Research.

PATIENT(S)

Twenty-five women undergoing laparoscopy (n = 10) and laparotomy (n = 15).

INTERVENTION(S)

Endometriotic cyst wall (group I) and endometrial biopsy (group II) collection.

MAIN OUTCOME MEASURE(S)

The endometrial-endometriotic stromal cells were isolated from ectopic (group I) and eutopic (group II) endometrium by established methods, cultured, and stimulated with LPS (1 μg/mL), followed by atorvastatin treatment in a time- and dose-dependent manner to investigate the effects of LPS on proliferation (Ki-67) and expression of cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF), receptor for advanced glycation end products (RAGE), extracellular newly identified RAGE binding protein (EN-RAGE), peroxisome proliferator activated receptor-γ (PPAR-γ), and liver X receptor-α (LXR-α) genes in endometrial-endometriotic stromal cells and on levels of insulin-like growth factor binding protein-1 (IGFBP-1) and 17β-E(2) in endometrial-endometriotic stromal cell culture supernatant.

RESULT(S)

Significant inhibition of Ki-67 and LPS-induced expression of inflammatory and angiogenic genes (COX-2, VEGF, RAGE, and EN-RAGE) was observed in atorvastatin-treated endometrial-endometriotic stromal cells. In contrast, a significant dose- and time-dependent increase in expression of anti-inflammatory genes (PPAR-γ and LXR-α) and levels of IGFBP-1 was observed after atorvastatin treatment in both the groups. However, atorvastatin treatment had no effect on 17β-E(2) levels in endometrial/endometriotic stromal cell culture supernatant.

CONCLUSION(S)

The data of the present study provide new insights for the implication of atorvastatin treatment for endometriosis in humans.

Prostaglandin E2 inhibits advanced glycation end product-induced adhesion molecule expression, cytokine production, and lymphocyte proliferation in human peripheral blood mononuclear cells

Advanced glycation end product (AGE) subtypes, proteins or lipids that become glycated after exposure to sugars, induce complications in diabetes. Among the various AGE subtypes, glyceraldehyde-derived AGE (AGE-2) and glycolaldehyde-derived AGE (AGE-3) have been indicated to play roles in inflammation in diabetic patients. The engagement of AGEs and receptor for AGEs activates monocytes. Because the engagement of intercellular adhesion molecule-1 (ICAM-1), B7.1, B7.2, and CD40 on monocytes with their ligands on T cells plays roles in cytokine production, we investigated the effects of AGE-2 and AGE-3 on the expressions of ICAM-1, B7.1, B7.2, and CD40 on monocytes, the production of interferon gamma and tumor necrosis factor alpha, and the lymphocyte proliferation in human peripheral blood mononuclear cells and their modulation by prostaglandin E(2) (PGE(2)). AGE-2 and AGE-3 induced the expressions of adhesion molecule, the cytokine production, and the lymphocyte proliferation. PGE(2) concentration-dependently inhibited the actions of AGE-2 and AGE-3. The effects of PGE(2) were mimicked by an E-prostanoid (EP)(2)-receptor agonist, 11,15-O-dimethyl prostaglandin E(2) (ONO-AE1-259-01), and an EP(4) receptor agonist, 16-(3-methoxymethyl)phenyl-omega-tetranor-3,7-dithia prostaglandin E(1) (ONO-AE1-329). An EP(2)-receptor antagonist, 6-isopropoxy-9-oxaxanthene-2-carboxylic acid (AH6809), and an EP(4)-receptor antagonist, (4Z)-7-[(rel-1S,2S,5R)-5-(1,1'-biphenyl-4-yl)methoxy)-2-(4-morpholinyl)-3-oxocyclopentyl]-4-heptenoic acid (AH23848), inhibited the actions of PGE(2). The stimulation of EP(2) and EP(4) receptors is reported to increase cAMP levels. The effects of PGE(2) were reversed by a protein kinase A (PKA) inhibitor, H89, and mimicked by a dibutyryl cAMP and an adenylate cyclase activator, forskolin. These results as a whole indicated that PGE(2) inhibited the actions of AGE-2 and AGE-3 via EP(2)/EP(4) receptors and the cAMP/PKA pathway.

Histamine inhibits advanced glycation end products-induced adhesion molecule expression on human monocytes

Advanced glycation end products (AGEs) are modifications of proteins/lipids that become nonenzymatically glycated after contact with aldose sugars. Among various subtypes of AGEs, glyceraldehyde-derived AGE (AGE-2) and glycolaldehyde-derived AGE (AGE-3) are suggested to play roles in inflammation in diabetic patients. Because the engagement of intercellular adhesion molecule (ICAM)-1, B7.1, B7.2, and CD40 on monocytes with their ligands on T cells plays roles in cytokine production, we examined the effects of AGE-2 and AGE-3 on the expression of adhesion molecules and cytokine production in human peripheral blood mononuclear cells (PBMC) and their modulation by histamine in the present study. AGE-2 and AGE-3 induced the expressions of ICAM-1, B7.1, B7.2, and CD40 on monocytes and the production of interferon-gamma in PBMC. Histamine concentration-dependently inhibited the action of AGE-2 and AGE-3. The effects of histamine were antagonized by an H2 receptor antagonist, famotidine, and mimicked by H2/H4 receptor agonists dimaprit and 4-methylhistamine. Histamine induced cAMP production in the presence and absence of AGE-2 and AGE-3. The effects of histamine were reversed by a protein kinase A (PKA) inhibitor, N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H89), and mimicked by a dibutyryl cAMP and an adenylate cyclase activator, forskolin. These results as a whole indicated that histamine inhibited the AGE-2- and AGE-3-induced adhesion molecule expression and cytokine production via H2 receptors and the cAMP/PKA pathway.

Receptor for advanced glycation end products (RAGE) and its inflammatory ligand EN-RAGE in non-diabetic subjects with pre-mature coronary artery disease

OBJECTIVE

Inflammation participates in atherosclerosis from its inception onwards. RAGE (receptor for advanced glycation end products) and its natural pro-inflammatory ligand, EN-RAGE (extracellular newly identified RAGE-binding protein) have been implicated in various inflammatory diseases. In present study, we determined the expression of RAGE and EN-RAGE in peripheral blood mononuclear cells (PBMCs) of subjects with pre-mature coronary artery disease (CAD) for the first time.

METHODS AND RESULTS

The study patients were angiographically proven non-diabetic patients with pre-mature CAD (Group I; N=100) and control group comprised of subjects with coronary risk factors and without coronary artery lesions (Group II; N=40). Semi-quantitative RT-PCR was performed to determine transcriptional expression of RAGE and EN-RAGE in PBMCs. Soluble RAGE (sRAGE) and C-reactive protein (hsCRP) levels were determined in serum of all study subjects using immunoassays. A significantly increased transcriptional expression of RAGE and EN-RAGE in PBMCs (p<0.01) of Group I patients was observed. Increased circulating hsCRP (p<0.01) levels and decreased sRAGE (p<0.01) levels were observed in Group I as compared with the Group II subjects. Severity of disease determined by Gensini score was found to be positively correlated with transcriptional expression of RAGE (r=0.530) and EN-RAGE (r=0.323). EN-RAGE expression revealed a strong association with RAGE (r=0.326), hsCRP (r=0.251) and a negative association with sRAGE (r=-0.222).

CONCLUSIONS

Increased expression of RAGE and EN-RAGE in non-diabetic pre-mature CAD and various associations discussed may amplify several cellular perturbations and thus significantly contribute to the pathophysiology of CAD.

Microvascular reactivity and inflammatory cytokines in painful and painless peripheral diabetic neuropathy

OBJECTIVE

We investigated the association between inflammation, microvascular reactivity, and the development of peripheral diabetic neuropathy.

RESEARCH DESIGN AND METHODS

We studied three groups: 55 healthy control subjects, 80 nonneuropathic patients, and 77 neuropathic diabetic patients. We also subdivided the neuropathic patients into a subgroup of 31 subjects with painless neuropathy and 46 with painful neuropathy. We measured the foot skin endothelium-dependent and -independent vasodilation, the nerve axon reflex-related vasodilation (NARV), and inflammatory cytokines and biochemical markers of endothelial function.

RESULTS

The endothelium-dependent and -independent vasodilation and NARV were lower in the neuropathic group (P < 0.05). NARV was further reduced in the subgroup of painless neuropathy when compared to painful neuropathy (P < 0.05). Compared to the other two groups, the neuropathic group also had higher serum levels of PDGF AA/BB (P < 0.05), RANTES (P < 0.01), leptin (P < 0.0001), osteoprotegerin (P < 0.01), G-CSF (P < 0.05), sE-Selectin (P < 0.01), sICAM (P < 0.0001), sVCAM (P < 0.001), CRP (P < 0.0001), TNFalpha (P < 0.05), and fibrinogen (P < 0.05). Patients with painful neuropathy had higher sICAM-1 (P < 0.05) and CRP levels (P < 0.01) when compared to painless neuropathy. No major changes in the above results were observed in 78 diabetic patients who were seen for a second visit 21 months after the first visit.

CONCLUSIONS

Peripheral diabetic neuropathy is associated with increased biochemical markers of inflammation and endothelial dysfunction. Painful neuropathy is associated with further increase in inflammation and markers of endothelial dysfunction and preservation of the nerve axon reflex.

Potential implications of matrix metalloproteinase-9 in assessment and treatment of coronary artery disease

BACKGROUND

Matrix metalloproteinase (MMP)-9, a member of the MMP superfamily is consistently implicated in the pathophysiology of atherosclerosis and plaque rupture, the most common mechanism responsible for acute coronary syndrome (ACS).

AIM

To summarize the role of MMP-9 in atherosclerosis and its potential implications in assessment and treatment of coronary artery disease (CAD).

METHODS

We reviewed the PubMed database for relevant data regarding the role of MMP-9 in the pathophysiology of atherosclerosis. In the light of these data, we postulate potential implications of MMP-9 in the management and treatment of CAD.

RESULTS AND CONCLUSIONS

Existing data strongly support the role of MMP-9 in plaque destabilization and rupture. Based on the current knowledge, MMP-9 can potentially serve as a diagnostic biomarker in ACS and a prognostic biomarker in ACS and chronic CAD patients. MMP-9 is reduced by therapies that are associated with favourable outcome in atherosclerosis and thus may serve as a surrogate biomarker of treatment efficacy. However, large morbidity and mortality trials are still required to confirm that MMP-9 reduction is associated with improved outcome independent of the traditional risk factors (i.e. low-density lipoprotein cholesterol). Given its role in plaque rupture, inhibition of MMP-9 may promote plaque stabilization and consequently reduce cardiovascular events. Yet, the efficacy and safety of MMPs inhibitors should be first studied in preclinical models of atherosclerosis.