Atherosclerosis and diabetes: the RAGE connection

Role of sacubitril/valsartan in modulating diabetes mediated cognitive and neuronal impairment

Earlier investigations had established that Diabetes mellitus (DM) caused significant damage in the central nervous system, bringing about diabetic encephalopathy and increasing the risk of cognitive-related problems. Nonetheless, the inherent pathophysiology of cognitive dysfunctions in DM is not well understood. The current study aimed to examine the possible influences of sacubitril/valsartan (SAC/VAL), an angiotensin receptor blocker/neprilysin inhibitor (ARNI), on cognitive dysfunction associated with streptozotocin (STZ)-induced diabetic rats. SAC/VAL and VAL treatments were initiated three days after the diabetic condition was established and continued daily for eight weeks. Normal, non-diabetic rats were reserved as a control group. Both SAC/VAL and VAL treatment in diabetic rats ameliorated diabetes induced oxidative stress as indicated by reduced malondialdehyde (MDA), increased total antioxidant capacity (TAO) in hippocampal tissue and decreased serum advanced glycation end products (AGEs), also inflammatory and apoptotic changes were observed and proved by the reduction of tumor necrosis factor alpha (TNF-α) and caspase -3 in rat hippocampus. SAC/VAL administration to diabetic rats also improved neuronal damages as reflected by restored cAMP response element-binding protein (CREB), brain derived neurotrophic factor (BDNF) and pre-synaptic phosphoproteins, synapsin I and growth associated protein-43 (GAP-43) in the hippocampus of diabetic rats. Additionally, SAC/VAL treated diabetic rats markedly reduced signs of cognitive deterioration during the Morris water maze test. Collectively, these findings suggested that SAC/VAL might play a vital role in improvement of the cognitive impairment observed in diabetic rats through antioxidant, anti-inflammatory and anti-apoptotic actions.

Identification of differentially expressed miRNAs involved in vascular aging reveals pathways associated with the endocrine hormone regulation

Vascular aging refers to a series of processes where the elasticity of blood vessels diminishes, leading to stiffening, and deposition of fat components on the vessel walls, causing inflammation. Cardiovascular diseases, such as stroke and hypertension, play significant roles in morbidity and mortality rates among the elderly population. In this study, the Reactive Hyperemia Index (RHI) was measured to assess vascular endothelial function and aging-induced pathogenesis of vascular diseases in Korean subjects. We aimed to identify extracellular vesicle microRNAs (EV-miRNAs) with differential abundance between groups of individuals at the ends of a continuum in vascular aging acceleration, revealing miRNAs regulating genes in endocrine hormone regulation and tumor-related pathways. We also discovered that the principal component characterizing the global miRNA expression profile is significantly associated with clinical traits including cholesterol levels. Together, these data provide a foundation for understanding the role of miRNAs as modulators of longevity and for developing age-specific epigenetic biomarkers.

Role of the Receptor for Advanced Glycation End Products (RAGE) and Its Ligands in Inflammatory Responses

Since its discovery in 1992, the receptor for advanced glycation end products (RAGE) has emerged as a key receptor in many pathological conditions, especially in inflammatory conditions. RAGE is expressed by most, if not all, immune cells and can be activated by many ligands. One characteristic of RAGE is that its ligands are structurally very diverse and belong to different classes of molecules, making RAGE a promiscuous receptor. Many of RAGE ligands are damaged associated molecular patterns (DAMPs) that are released by cells under inflammatory conditions. Although RAGE has been at the center of a lot of research in the past three decades, a clear understanding of the mechanisms of RAGE activation by its ligands is still missing. In this review, we summarize the current knowledge of the role of RAGE and its ligands in inflammation.

Glucose-Dependent Insulinotropic Polypeptide Inhibits AGE-Induced NADPH Oxidase-Derived Oxidative Stress Generation and Foam Cell Formation in Macrophages Partly via AMPK Activation

Glucose-dependent insulinotropic polypeptide (GIP) of the incretin group has been shown to exert pleiotropic actions. There is growing evidence that advanced glycation end products (AGEs), senescent macromolecules formed at an accelerated rate under chronic hyperglycemic conditions, play a role in the pathogenesis of atherosclerotic cardiovascular disease in diabetes. However, whether and how GIP could inhibit the AGE-induced foam cell formation of macrophages, an initial step of atherosclerosis remains to be elucidated. In this study, we address these issues. We found that AGEs increased oxidized low-density-lipoprotein uptake into reactive oxygen species (ROS) generation and Cdk5 and CD36 gene expressions in human U937 macrophages, all of which were significantly blocked by [D-Ala2]GIP(1-42) or an inhibitor of NADPH oxidase activity. An inhibitor of AMP-activated protein kinase (AMPK) attenuated all of the beneficial effects of [D-Ala2]GIP(1-42) on AGE-exposed U937 macrophages, whereas an activator of AMPK mimicked the effects of [D-Ala2]GIP(1-42) on foam cell formation, ROS generation, and Cdk5 and CD36 gene expressions in macrophages. The present study suggests that [D-Ala2]GIP(1-42) could inhibit the AGE-RAGE-induced, NADPH oxidase-derived oxidative stress generation in U937 macrophages via AMPK activation and subsequently suppress macrophage foam cell formation by reducing the Cdk5-CD36 pathway.

Anti-diabetes and neuroprotection potential and primary safety studies of Isatis tinctoria L. hydroalcoholic leaf extract

PURPOSE

Natural plant raw materials, previously underestimated in therapeutics, are becoming the subject of research for new applications in medicine. In our research, the hydroalcoholic extract of Isatis tinctoria leaf, rich in flavonoid compounds such as vicenin-2 and quercetin, was examined as a potential antidiabetic and neuroprotective agent.

METHODS

The effect of the extract and its main flavonoid compounds on protein glycation, alpha-glucosidase activity, and acetylcholinesterase activity was tested. In vitro, in the mouse hippocampal neuronal cell line and in vivo, using a mouse model, the safety of the extract was screened for.

RESULTS

Our experiments demonstrated significant inhibition of protein glycation, alpha-glucosidase activity, acetylcholinesterase activity, and β-amyloid aggregation by the extract, in a concentration-dependent manner. The extract had a strong reducing effect and did not exhibit cytotoxicity up to a concentration of 25 mg/mL. Intraperitoneal administration of the extract to mice did not have negative effects on body mass, locomotor activity, coordination, and liver cell integrity.

CONCLUSIONS

Our research sheds new light on this raw material and deepens knowledge of its activity. This may result in the recognition of its therapeutic effects and even in its introduction in the modern treatment of diseases characterized by pathological changes associated with hyperglycemia, oxidation, and inflammation.

Lipid-lowering in diabetes: An update

Atherosclerotic cardiovascular disease (ASCVD) is accelerated in people with diabetes. Dyslipidemia, hyperglycemia, oxidative stress, and inflammation play a role via a variety of mechanisms operative in the artery wall. In addition, some unique features predispose people with type 1 diabetes to accelerated atherosclerosis. Various organizations have created guidelines that provide advice regarding screening, risk assessment, and roadmaps for treatment to prevent ASCVD in diabetes. Management of dyslipidemia, especially with statins, has proven to be of immense benefit in the prevention of clinical CVD. However, since many patients fail to attain the low levels of low-density lipoproteins (LDL) recommended in these guidelines, supplemental therapy, such as the addition of ezetimibe, bempedoic acid or PCSK9 inhibitors, is often required to reach LDL goals. As a result, the upfront use of combination therapies, particularly a statin plus ezetimibe, is a rational initial approach. The addition to statins of drugs that specifically lower triglyceride levels has not proven beneficial, although the addition of icosapent-ethyl has been shown to be of value, likely by mechanisms independent of triglyceride lowering. Newer treatments in development, including apoC-III and ANGPTL3 inhibitors, seem promising in further reducing apoB-containing lipoproteins.

Soluble receptor for advanced glycation end products (sRAGE) is associated with obesity rates: a systematic review and meta-analysis of cross-sectional study

BACKGROUND

Several studies have highlighted the possible positive effects of soluble receptor for advanced glycation end products (sRAGE) against obesity. However, due to their inconsistent results, this systematic review and meta-analysis aimed to quantitatively evaluate and critically review the results of studies evaluating the relationship between sRAGE with obesity among adult population.

METHODS

In the systematic search, the eligibility criteria were as follows: studies conducted with a cross-sectional design, included apparently healthy adults, adults with obesity, or obesity-related disorders, aged over 18 years, and evaluated the association between general or central obesity indices with sRAGE.

RESULTS

Our systematic search in electronic databases, including PubMed, Scopus, and Embase up to 26 October, 2023 yielded a total of 21,612 articles. After removing duplicates, screening the titles and abstracts, and reading the full texts, 13 manuscripts were included in the final meta-analysis. According to our results, those at the highest category of circulating sRAGE concentration with median values of 934.92 pg/ml of sRAGE, had 1.9 kg/m2 lower body mass index (BMI) (WMD: -1.927; CI: -2.868, -0.986; P < 0.001) compared with those at the lowest category of sRAGE concentration with median values of 481.88 pg/ml. Also, being at the highest sRAGE category with the median values of 1302.3 pg/ml sRAGE, was accompanied with near 6 cm lower waist circumference (WC) (WMD: -5.602; CI: -8.820, -2.383; P < 0.001 with 86.4% heterogeneity of I2) compared with those at the lowest category of sRAGE concentration with median values of 500.525 pg/ml. Individuals with obesity had significantly lower circulating sRAGE concentrations (WMD: -135.105; CI: -256.491, -13.72; P = 0.029; with 79.5% heterogeneity of I2). According to the subgrouping and meta-regression results, country and baseline BMI were possible heterogeneity sources. According to Begg's and Egger's tests and funnel plots results, there was no publication bias.

CONCLUSION

According to our results, higher circulating sRAGE concentrations was associated with lower BMI and WC among apparently healthy adults. Further randomized clinical trials are warranted for possible identification of causal associations.

Association between serum osteocalcin and atherosclerosis in Type-2 diabetes mellitus: a cross-sectional study

BACKGROUND

The past few decades have seen a marked increase in the macrovascular complications of Type-2 diabetes mellitus (T2DM) such as coronary heart disease, peripheral arterial disease, and cerebrovascular disease. This has been predominantly attributed to the increased atherosclerosis in these patients. Atherosclerosis usually remains an asymptomatic condition and this poses a significant challenge in its early diagnosis and timely intervention. Hence, there is an immediate need for exploring novel tools to aid in the early detection of atherosclerosis, especially in T2DM patients. Osteocalcin (OC), synthesized by osteoblasts, is a protein hormone found in the skeletal system. This protein is considered as a marker for bone density and in recent times has been gaining interest due to its protective role in cerebrovascular diseases(CVD).

METHODS

We conducted a cross-sectional study and evaluated the association between serum OC levels and atherosclerosis in 113 T2DM patients. Carotid intima-media thickness (CC-IMT) was used as an estimate of atherosclerosis and patients were divided into two groups (CC-IMT < 0.9 and ≥ 0.9). Correlation of serum OC levels and glycemic parameters and lipid profiles were studied and compared between both groups.

RESULTS

There is a significant negative correlation between the CC-IMT estimates and serum OC levels. CC-IMT also has a significant association with other biochemical parameters such as fasting blood sugar, glycated hemoglobin and high-density lipoprotein.

CONCLUSION

Although the independent association of serum OC could not be established in the T2DM patient population, overall, the results favor low serum OC as a prognostic marker for atherosclerosis.

Blood and Tissue Advanced Glycation End Products as Determinants of Cardiometabolic Disorders Focusing on Human Studies

Cardiometabolic disorders are characterised by a cluster of interactive risk determinants such as increases in blood glucose, lipids and body weight, as well as elevated inflammation and oxidative stress and gut microbiome changes. These disorders are associated with onset of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). T2DM is strongly associated with CVD. Dietary advanced glycation end products (dAGEs) attributable from modern diets high in sugar and/or fat, highly processed foods and high heat-treated foods can contribute to metabolic etiologies of cardiometabolic disorders. This mini review aims to determine whether blood dAGEs levels and tissue dAGEs levels are determinants of the prevalence of cardiometabolic disorders through recent human studies. ELISA (enzyme-linked immunosorbent assay), high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) for blood dAGEs measurement and skin auto fluorescence (SAF) for skin AGEs measurement can be used. Recent human studies support that a diet high in AGEs can negatively influence glucose control, body weight, blood lipid levels and vascular health through the elevated oxidative stress, inflammation, blood pressure and endothelial dysfunction compared with a diet low in AGEs. Limited human studies suggested a diet high in AGEs could negatively alter gut microbiota. SAF could be considered as one of the predictors affecting risks for cardiometabolic disorders. More intervention studies are needed to determine how dAGEs are associated with the prevalence of cardiometabolic disorders through gut microbiota changes. Further human studies are conducted to find the association between CVD events, CVD mortality and total mortality through SAF measurement, and a consensus on whether tissue dAGEs act as a predictor of CVD is required.

SMTP-44D Inhibits Atherosclerotic Plaque Formation in Apolipoprotein-E Null Mice Partly by Suppressing the AGEs-RAGE Axis

SMTP-44D has been reported to have anti-oxidative and anti-inflammatory reactions, including reduced expression of receptor for advanced glycation end products (RAGE) in experimental diabetic neuropathy. Although activation of RAGE with its ligands, and advanced glycation end products (AGEs), play a crucial role in atherosclerotic cardiovascular disease, a leading cause of death in diabetic patients, it remains unclear whether SMTP-44D could inhibit experimental atherosclerosis by suppressing the AGEs–RAGE axis. In this study, we investigated the effects of SMTP-44D on atherosclerotic plaque formation and expression of AGEs in apolipoprotein-E null (Apoe−/−) mice. We further studied here whether and how SMTP-44D inhibited foam cell formation of macrophages isolated from Apoe−/− mice ex vivo. Although administration of SMTP-44D to Apoe−/− mice did not affect clinical or biochemical parameters, it significantly decreased the surface area of atherosclerotic lesions and reduced the atheromatous plaque size, macrophage infiltration, and AGEs accumulation in the aortic roots. SMTP-44D bound to immobilized RAGE and subsequently attenuated the interaction of AGEs with RAGE in vitro. Furthermore, foam cell formation evaluated by Dil-oxidized low-density lipoprotein (ox-LDL) uptake, and gene expression of RAGE, cyclin-dependent kinase 5 (Cdk5) and CD36 in macrophages isolated from SMTP-44D-treated Apoe−/− mice were significantly decreased compared with those from saline-treated mice. Gene expression levels of RAGE and Cdk5 were highly correlated with each other, the latter of which was also positively associated with that of CD36. The present study suggests that SMTP-44D may inhibit atherosclerotic plaque formation in Apoe−/− mice partly by blocking the AGEs-RAGE-induced ox-LDL uptake into macrophages via the suppression of Cdk5-CD36 pathway.

Diabesity in Elderly Cardiovascular Disease Patients: Mechanisms and Regulators

Cardiovascular disease (CVD) is the leading cause of death in the world. In 2019, 550 million people were suffering from CVD and 18 million of them died as a result. Most of them had associated risk factors such as high fasting glucose, which caused 134 million deaths, and obesity, which accounted for 5.02 million deaths. Diabesity, a combination of type 2 diabetes and obesity, contributes to cardiac, metabolic, inflammation and neurohumoral changes that determine cardiac dysfunction (diabesity-related cardiomyopathy). Epicardial adipose tissue (EAT) is distributed around the myocardium, promoting myocardial inflammation and fibrosis, and is associated with an increased risk of heart failure, particularly with preserved systolic function, atrial fibrillation and coronary atherosclerosis. In fact, several hypoglycaemic drugs have demonstrated a volume reduction of EAT and effects on its metabolic and inflammation profile. However, it is necessary to improve knowledge of the diabesity pathophysiologic mechanisms involved in the development and progression of cardiovascular diseases for comprehensive patient management including drugs to optimize glucometabolic control. This review presents the mechanisms of diabesity associated with cardiovascular disease and their therapeutic implications.

The effects of metformin monotherapy and combination of metformin and glibenclamide therapy on the expression of RAGE, Sirt1, and Nrf2 genes in peripheral blood mononuclear cells of type 2 diabetic patients

Purpose

Although metformin is the first-line treatment of type 2 diabetes mellitus (T2DM), a few studies have evaluated the benefits of monotherapies (metformin) versus combination therapy (metformin and glibenclamide) for treatment of T2DM patients. The present study aimed to evaluate the effect of monotherapy with metformin compared to combination therapy with metformin and glibenclamide on the expression of RAGE, Nrf 2, and Sirt1genes.

Methods

EightyT2DM patients and 40 healthy individuals participated in this case-control study. The patients in the treatment group were divided into two groups who received either metformin alone (n = 40) or metformin in combination with glibenclamide (n = 40). FBS, HbA1c, and fructosamine were measured. The expression of RAGE, Nrf 2, and Sirt 1 genes in PBMC of all subjects were assessed using real-time PCR.

Results

RAGE gene expression in both treatment groups was significantly lower than the control (P < 0.05). RAGE gene expression was significantly reduced in the combination of metformin and glibenclamide treated group compared to metformin group (P < 0.05). Additionally, the expression of Sirt 1 and Nrf 2 genes in both treatment groups was higher than that of the control group (P < 0.05). The expression of Sirt 1 and Nrf 2 genes in metformin and glibenclamide treated group were higher than the metformin group (P < 0.05).

Conclusion

Combination therapy (metformin and glibenclamide) showed stronger effect on repression of the RAGE gene and activation of Nrf 2 and Sirt 1 genes compared to monotherapy (metformin); therefore, it can be concluded that combination therapy may have more protective effects on the T2DM patients. No significant correlation was observed between HbA1c and RAGE, Sirt 1, and Nrf 2 genes expression.

Effects of Green Tea (-)-Epigallocatechin-3-Gallate (EGCG) on Cardiac Function - A Review of the Therapeutic Mechanism and Potentials

Heart disease, the leading cause of death globally, refers to various illnesses that affect heart structure and function. Specific abnormalities affecting cardiac muscle contractility and remodeling and common factors including oxidative stress, inflammation, and apoptosis underlie the pathogenesis of heart diseases. Epidemiology studies have associated green tea consumption with lower morbidity and mortality of cardiovascular diseases, including heart and blood vessel dysfunction. Among the various compounds found in green tea, catechins are believed to play a significant role in producing benefits to cardiovascular health. Comprehensive literature reviews have been published to summarize the tea catechins' antioxidative, anti-inflammatory, and anti-apoptosis effects in the context of various diseases, such as cardiovascular diseases, cancers, and metabolic diseases. However, recent studies on tea catechins, especially the most abundant (-)-Epigallocatechin-3-Gallate (EGCG), revealed their capabilities in regulating cardiac muscle contraction by directly altering myofilament Ca2+ sensitivity on force development and Ca2+ ion handling in cardiomyocytes under both physiological and pathological conditions. In vitro and in vivo data also demonstrated that green tea extract or EGCG protected or rescued cardiac function, independent of their well-known effects against oxidative stress and inflammation. This minireview will focus on the specific effects of tea catechins on heart muscle contractility at the molecular and cellular level, revisit their effects on oxidative stress and inflammation in a variety of heart diseases, and discuss EGCG's potential as one of the lead compounds for new drug discovery for heart diseases.

Ginsenoside derivatives inhibit advanced glycation end-product formation and glucose-fructose mediated protein glycation in vitro via a specific structure-activity relationship

Ginseng (Panax ginseng and red ginseng) extract has been reported to inhibit the formation of advanced glycation end-products (AGEs); however, the potential inhibitory activity of its major constituents (ginsenosides) against AGE formation is still unknown. In the present study, we investigated the inhibitory effect of ginsenoside derivatives on AGE formation. Herein, we assessed the activity of 22 ginsenosides, most of which significantly inhibited fluorescent AGE formation. Notably, ginsenoside Rh2, ginsenoside Rh1, and compound K exhibited the most potent AGE inhibitory potential with IC₅₀ values of 3.38, 8.42, and 10.85 µM, respectively. The structure- activity relationship revealed that the presence of sugar moieties, hydroxyl groups, and their linkages, and the stereostructure of the ginsenoside skeleton played an important role in the inhibition of AGE formation. Furthermore, the inhibitory activity of the most active ginsenoside Rh2 on fructose-glucose-mediated protein glycation and oxidation of bovine serum albumin (BSA) was explored. Rh2 (0.1-12.5 µM) inhibited the formation of fluorescent AGE and non-fluorescent AGE, as well as the level of fructosamine and prevented protein oxidation by decreasing protein carbonyl formation and protein thiol group modification. Rh2 also suppressed the formation of the β-cross amyloid structure of BSA. Ginsenosides might be promising new anti-glycation agents for the prevention of diabetic complications via inhibition of AGE formation and oxidation-dependent protein damage.

N‑acetylcysteine inhibits atherosclerosis by correcting glutathione‑dependent methylglyoxal elimination and dicarbonyl/oxidative stress in the aorta of diabetic mice

In diabetic animal models, high plasma/tissue levels of methylglyoxal (MG) are implicated in atherosclerosis. N-acetylcysteine (NAC) is a cysteine prodrug that replenishes intracellular glutathione (GSH) levels, which can increase the elimination of MG in diabetes mellitus (DM). The present study investigated the anti-atherosclerotic role of NAC in DM and aimed to determine whether the mechanism involved GSH-dependent MG elimination in the aorta. Apolipoprotein-E knockdown (ApoE^−/−) mice injected with streptozotocin for 5 days exhibited enhanced atherosclerotic plaque size in the aortic root; notably, a high-lipid diet aggravated this alteration. NAC treatment in the drinking water for 12 weeks decreased the size of the atherosclerotic lesion, which was associated with a reduction in MG-dicarbonyl stress and oxidative stress, as indicated by decreased serum malondialdehyde levels, and increased superoxide dismutase-1 and glutathione peroxidase-1 levels in the diabetic aorta. Endothelial damage was also corrected by NAC, as indicated by an increase in the expression levels of phosphorylated (p-)Akt and p-endothelial nitric oxide synthase (eNOS) in the aorta, as well as nitric oxide (NO) in the serum. In addition, MG-treated human umbilical vein endothelial cells (HUVECs) exhibited increased reactive oxygen species and decreased antioxidant enzyme expression levels. NAC treatment corrected the alteration in HUVECs induced by MG, whereas the protective role of NAC was blocked via inhibition of GSH. These findings indicated that the diabetic aorta was more susceptible to atherosclerotic lesions compared with non-diabetic ApoE^−/− mice. Furthermore, NAC may offer protection against atherosclerotic development in DM by altering aortic and systemic responses via correcting GSH-dependent MG elimination, leading to decreased oxidative stress and restoration of the p-Akt/p-eNOS pathway in the aorta.

Higher levels of the soluble receptor for advanced glycation end products and lower levels of the extracellular newly identified receptor for advanced glycation end products were associated with lipid-lowering drugs in patients with type 1 diabetes: a comparative cross-sectional study

Background

The receptors for advanced glycation end products (RAGE) are increased in atherosclerotic plaques. Soluble (s)RAGE decreases, whereas the extracellular newly identified receptor for advanced glycation end products (EN-RAGE) increases inflammatory responses mediated by RAGE. The aims were to explore whether sRAGE, EN-RAGE and the EN-RAGE/sRAGE ratio, were associated with the use of lipid-lowering drugs (LLD) and/or antihypertensive drugs (AHD) in patients with type 1 diabetes (T1D).

Methods

Cross-sectional design. T1D patients were consecutively recruited from one diabetes clinic. Blood samples were collected, supplemented with data from electronic health records. sRAGE and EN-RAGE were analysed by enzyme linked immunosorbent assays. An EN-RAGE/sRAGE ratio was calculated. Adjustments were performed with inflammatory and metabolic variables, s-creatinine, depression, smoking, physical inactivity, medication, and cardiovascular complications. Multiple regression analyses were performed.

Results

In this study 283 T1D patients (men 56%, 18–59 years) were included. One-hundred and thirty LLD users compared to 153 non-users had lower levels of the EN-RAGE/sRAGE ratio (P = 0.009), and 89 AHD users compared to 194 non-users had lower levels of sRAGE (P = 0.031). The use of LLD (inversely) (B coefficient − 0.158, P = 0.033) and the use of AHD (B coefficient 0.187, P = 0.023) were associated with the EN-RAGE/sRAGE ratio. sRAGE (Lg10) (per unit) (adjusted odds ratio (AOR) = 3.5, 95% CI = 1.4–9.1, P = 0.009), EN-RAGE (Lg10) (per unit) (inversely) (AOR 0.4, 95% CI = 0.2–1.0, P = 0.046), age (P <  0.001), and triglycerides (P <  0.029), were associated with LLD. sRAGE (Lg10) (per unit) (inversely) (AOR = 0.2, 95% CI = 0.1–0.5, P = 0.001), diabetes duration, triglycerides, s-creatinine, and systolic BP (all P values < 0.043), were associated with AHD.

Conclusions

Higher sRAGE levels and lower EN-RAGE levels were linked to the use of LLD, whereas lower sRAGE levels were linked to the use of AHD. No other variables but the use of LLD and the use of AHD were linked to the EN-RAGE/sRAGE ratio. This may be of major importance as sRAGE is an inhibitor and EN-RAGE is a stimulator of inflammatory processes mediated by RAGE.

Soluble Receptor for Advanced Glycation End Products and Its Correlation with Vascular Damage in Adolescents with Obesity

OBJECTIVE

The aim of this study was to evaluate soluble receptor for advanced glycation end products (sRAGE) and advanced glycation end products (AGEs) in adolescents with and without obesity (OB) and their correlation with vascular damage.

METHODS

This is a cross-sectional study with 15-19 years old adolescents: 33 with OB and 33 with normal weight (NW), each group included 17 male and 16 female. Lipid profile, insulin, carboxymethylysine (CML), sRAGE, total AGEs, and dietary AGEs intake (dAGEs) were evaluated. Vascular damage was measured by flow-mediated vasodilation (FMD) and arterial stiffness index (Iβ). Homeostatic model assessment-insulin (HOMA-IR) and atherogenic index (AI) were calculated.

RESULTS

The group with OB had higher triglycerides (TG; p < 0.0001), AI (p < 0.001), HOMA-IR (p < 0.0001), dAGEs intake (p < 0.0001), lower CML (p = 0.05), total AGEs (p < 0.01), sRAGE (p < 0.001), and FMD (p < 0.002). In the total group, sRAGE correlated with AI (r = -0.26 p = 0.037); in the NW group, CML correlated with Iβ (r = -0.36; p = 0.037); and in the group of adolescents with OB, sRAGE correlated with FMD (r = -0.37; p = 0.037) and Iβ (r = 0.47; p = 0.006), while CML and total AGEs correlated with AI, p = 0.007 and p < 0.01, respectively).

CONCLUSIONS

The group of adolescents with OB showed higher cardiometabolic risk as shown by higher TG, AI, HOMA-IR, and lower sRAGE and FMD. sRAGE correlated negatively with FMD and positively with Iβ, so it could be suggested as a biochemical marker of impaired endothelial function.

Combating atherosclerosis with targeted Diosmin nanoparticles-treated experimental diabetes

Diabetes with poor glycemic control is accompanying with an increased risk of disease namely atherosclerotic cardiovascular. Diosmin (DSN), which is obtained from citrus fruit used to assist the treatment of hemorrhoids or chronic venous atherosclerosis diseases, has an antioxidant, anti-hyperglycemic and anti-inflammatory effect. DSN is characterized by poor water solubility which limits its absorption by the gastrointestinal tract. To overcome this limitation, this study was designed to increase DSN bioavailability and solubility, through its loading on polymeric matrix; hydroxypropyl starch (HPS) and Poly lactide-glycolide-chitin (PLGA/chitin) to prepare Diosmin nanoparticles (DSN-NPs). Two methods were used to prepare DSN- NPs; Emulsion-solvent evaporation and Acid-base neutralization followed by further assessment on diabetes induced atherosclerosis The study was conducted on 50 animals assigned into 5 groups with 10 animals in each group: Group I: Normal rats received only normal saline, Group II: Diabetic rats, Group III: diabetic rats received oral DSN, Group IV: diabetic rats received DSN loaded HPS, Group V: diabetic rats received DSN loaded PLGA/chitin. Levels of total cholesterol, triglycerides, HDL-cholesterol, insulin, MDA and NO. plasminogen activator inhibitor-1 PAI-1), Paraoxonase-1(PON1), transforming growth factor-β1 (TGF-β1), NF-ҡB and Ang II were estimated. Our study revealed that, there was statistically significant difference between DSN treated group compared with DSN loaded HPS treated group and DSN loaded PLGA/chitin. Furthermore, the results obtained clearly disclosed no statistically significant difference between DSN loaded PLGA/chitin and control group exhibited DSN loaded PLGA/chitin has the higher ability to counteract the atherosclerosis factors induced by diabetes in all rats.

Association of Glycemic Indices (Hyperglycemia, Glucose Variability, and Hypoglycemia) with Oxidative Stress and Diabetic Complications

Oxidative stress (OS) is defined as a disturbance in the prooxidant-antioxidant balance of the cell, in favor of the former, which results in the antioxidant capacity of the cell to be overpowered. Excess reactive oxygen species (ROS) production is very harmful to cell constituents, especially proteins, lipids, and DNA, thus causing damage to the cell. Oxidative stress has been associated with a variety of pathologic conditions, including diabetes mellitus (DM), cancer, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and accelerated aging. Regarding DM specifically, previous experimental and clinical studies have pointed to the fact that oxidative stress probably plays a major role in the pathogenesis and development of diabetic complications. It is postulated that hyperglycemia induces free radicals and impairs endogenous antioxidant defense systems through several different mechanisms. In particular, hyperglycemia promotes the creation of advanced glycation end-products (AGEs), the activation of protein kinase C (PKC), and the hyperactivity of hexosamine and sorbitol pathways, leading to the development of insulin resistance, impaired insulin secretion, and endothelial dysfunction, by inducing excessive ROS production and OS. Furthermore, glucose variability has been associated with OS as well, and recent evidence suggests that also hypoglycemia may be playing an important role in favoring diabetic vascular complications through OS, inflammation, prothrombotic events, and endothelial dysfunction. The association of these diabetic parameters (i.e., hyperglycemia, glucose variability, and hypoglycemia) with oxidative stress will be reviewed here.

Role of Advanced Glycation Endproduct (AGE)-Receptor for Advanced Glycation Endproduct (RAGE) Axis in Cardiovascular Disease and Its Therapeutic Intervention

Despite the early loss of glycemic differences between the original intensive therapy group and conventional treatment in the DCCT/EDIC and UKPDS 80 trials, a continued reduction in microvascular risk and risk reductions for emergency myocardial infarction and all-cause death were observed 10-30 years after the end of these trials. These observations demonstrated that so-called "metabolic memory" could cause chronic abnormalities in diabetic vessels that are not easily reversed, even by subsequent improvement in blood glucose levels, thus suggesting a long-term beneficial influence of early metabolic control; that is, legacy effects on the risk of vascular complications and death in patients with both type 1 and type 2 diabetes. Formation and accumulation of advanced glycation endproducts (AGEs) are known to progress at an accelerated rate under diabetes. Furthermore, AGEs are hardly degraded and remain for a long time in diabetic vessels even after glycemic control is improved. Therefore, AGEs could explain why former cumulative diabetic exposure could contribute to current progression of vascular complications in diabetes. Here, the clinical utility of measurement of serum and tissue accumulation levels of AGEs for evaluating the prevalence and severity of numerous types of cardiovascular disease is reviewed and novel therapeutic strategies that could target the AGE-RAGE axis in CVD are discussed.

Effect of bergenin on RANKL-induced osteoclast differentiation in the presence of methylglyoxal

Methylglyoxal (MG), a highly reactive dicarbonyl compound, is a major precursor in the formation of advanced glycation end products, which are associated with diabetes-related diseases. Bergenin, an active constituent of plants of the genus Bergenia, exhibits multiple biological activities. This study evaluated the effect of bergenin on osteoclast differentiation and determined its mechanism of action. Bergenin reversed MG-inhibited tartrate-resistant acid phosphatase (TRAP) activity and decreased the bone resorption activity of osteoclasts. Quantitative RT-PCR revealed that bergenin decreased the expression of ERK1, Akt2, MMP-9, and OSTM1 genes in the presence of MG. Bergenin pretreatment yielded significant increases in intracellular calcium concentration, mitochondrial mass, mitochondrial membrane potential, and glyoxalase I reduced by MG. Additionally, bergenin decreased the formation of mitochondrial superoxide induced by MG. Detoxification of MG by bergenin may be a viable treatment for bone disorders in patients with diabetes.

1,25-(OH)2D3 protects Schwann cells against advanced glycation end products-induced apoptosis through PKA-NF-κB pathway

AIMS

To explore the effect and mechanism of 1, 25-(OH)₂D₃ on Schwann cell apoptosis induced by advanced glycation end products.

MAIN METHODS

Schwann cells, isolated from rodent sciatic nerve were incubated with AGE-modified bovine serum albumin(AGE) to mimic diabetic conditions and 1,25-(OH)₂D₃ was used as protector. Cell apoptosis was detected by PI/Annexin-V staining, caspase 3 activity assay and western blotting for caspase 3 and PARP. The activation of protein kinase A (PKA) and nuclear factor kappa-B (NF-κB) was evaluated by western blot. Immunofluorescent staining was used for intercellular location of NF-κB. Cytokine secretion was evaluated by enzyme-linked immunosorbent assay.

KEY FINDINGS

Schwann cell apoptosis accelerated after incubating with AGE. However, if combining 1,25-(OH)₂D₃ with AGE, apoptosis decreased significantly. 1,25-(OH)₂D₃ enhanced PKA activity, but inhibited AGE-induced nuclear translocation of NF-κB. Furthermore, PKA activator (8-bromoadenoside cyclic adenoside monophosphate, 8-Br-cAMP) or NF-κB inhibitor (caffeic acid phenethyl ester, CAPE) could reduce the apoptosis, decreased cleaved caspase 3 and cleaved PARP, suggesting the involvement of PKA and NF-κB pathways in the protection of 1,25-(OH)₂D₃ on Schwann cells. Moreover, 8-Br-cAMP and CAPE could inhibit AGE-induced secretion of interleukin(IL)-1β, prostaglandin E2(PEG2) and cyclooxygenase 2(COX2). Interestingly, 8-Br-cAMP decreased phospho-NF-κB and inhibited nucleus translocation of NF-κB. It hinted at the regulation of PKA to NF-κB. Finally, a pre-treatment of H-89 (an inhibitor of PKA) could block the protection of 1,25-(OH)₂D₃ on cell apoptosis. In conclusion, 1,25-(OH)₂D₃ could protect Schwann cell against AGE-induced apoptosis through PKA/NF-κB pathway.

SIGNIFICANCE

These findings provide experimental rationales for using vitamin D for diabetic neuropathy.

Preparation and Characterization of Callus Extract from Pyrus pyrifolia and Investigation of Its Effects on Skin Regeneration

In the present study, an aqueous extract was prepared using calli from the in vitro-derived leaves of Pyrus pyrifolia cultured in Murashige and Skoog medium containing picloram for a plant growth regulator. The major biological components in the callus extract were identified as uridine (1), adenosine (2), and guanosine (3). In terms of the antioxidant activity, at 300 µg/mL, the extract exhibited free radical scavenging activity of 76.9% ± 2.88% in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, comparable to that of 44 µg/mL ascorbic acid (82.5% ± 3.63%). In addition, the IC50 values for inhibition of advanced glycation end product formation from collagen and elastin were 602 ± 2.72 and 3037 ± 102.5 µg/mL, respectively. The extract significantly promoted keratinocyte and fibroblast cell proliferation in a dose-dependent manner. Moreover, fibroblasts treated with 1.36 µg/mL extract exhibited a 1.60-fold increase in procollagen type I C-peptide level compared to controls. The in vitro wound recovery rates of keratinocytes and fibroblasts were also 75% and 38% greater, respectively, than those of serum-free controls at 9 and 36 h after extract treatment (1.36 µg/mL). Additionally, the extract flux across the human epidermis increased by 1598% after its incorporation into elastic nanoliposomes (NLs). Therefore, elastic NLs loaded with Pyrus pyrifolia callus extract have potential use as skin rejuvenators and antiaging ingredients in cosmetic formulations.

Type-2 diabetes mellitus and cardiovascular disease

The global prevalence of diabetes has risen in adults from 4.7% in 1980 to 8.5% in 2014. 90–95% of adults with diabetes have Type 2 diabetes (T2D). This paper focuses on the diagnosis and treatment of T2D patients who have or are at risk for cardiovascular disease. Hyperglycemia, insulin resistance and excess fatty acids increase oxidative stress, disrupt protein kinase C signaling and increase advanced glycation end-products that result in vascular inflammation, vasoconstriction, thrombosis and atherogenesis. Intensive T2D treatment produces a ≥10% risk reduction in major macrovascular and microvascular events. Glucose-lowering therapies must be individualized. Metformin is an optimal drug for monotherapy. If hemoglobin A1c is not at goal, a sodium-glucose cotransporter-2 inhibitor or a dipeptidyl peptidase-4 inhibitor should be considered for therapy with metformin. Coronary angioplasty/stenting is recommended for diabetic patients with acute myocardial infarctions. Coronary artery bypass grafting is recommended for symptomatic diabetic patients with multivessel disease.

Impact of the Receptor for Advanced Glycation End Products Genetic Polymorphisms on the Progression in Uterine Cervical Cancer

To date, few studies have explored the effects of single nucleotide polymorphisms (SNPs) of the receptor for advanced glycation end products (RAGE) in uterine cervical cancer. Therefore, we conducted this study to investigate the involvement of RAGE SNPs in cervical cancer. In total, 117 patients with cervical invasive cancer, 84 with precancerous lesions, and 320 normal women were recruited consecutively. Real-time polymerase chain reaction was used to examine the genotypic frequencies of RAGE SNPs. The results indicated that among the four RAGE SNPs, only the GT/TT genotype of rs184003 was distributed differently between patients with cervical neoplasias and the normal controls, with GG as a reference. Moreover, cervical cancer patients with genotypes TA/AA in rs1800624 exhibited a lower risk of parametrium invasion, moderate-to-poor cell differentiation, and pelvic lymph node metastasis. In conclusion, RAGE SNPs rs1800624 was associated with some clinicopathological variables in cervical cancer.

The Role of Advanced Glycation End Products in Aging and Metabolic Diseases: Bridging Association and Causality

Accumulation of advanced glycation end products (AGEs) on nucleotides, lipids, and peptides/proteins are an inevitable component of the aging process in all eukaryotic organisms, including humans. To date, a substantial body of evidence shows that AGEs and their functionally compromised adducts are linked to and perhaps responsible for changes seen during aging and for the development of many age-related morbidities. However, much remains to be learned about the biology of AGE formation, causal nature of these associations, and whether new interventions might be developed that will prevent or reduce the negative impact of AGEs-related damage. To facilitate achieving these latter ends, we show how invertebrate models, notably Drosophila melanogaster and Caenorhabditis elegans, can be used to explore AGE-related pathways in depth and to identify and assess drugs that will mitigate against the detrimental effects of AGE-adduct development.

Aqueous Extract of Glucoraphanin-Rich Broccoli Sprouts Inhibits Formation of Advanced Glycation End Products and Attenuates Inflammatory Reactions in Endothelial Cells

We have previously shown that sulforaphane not only inhibits formation of advanced glycation end products (AGEs) but also exerts anti-inflammatory effects on AGE-exposed human umbilical vein endothelial cells (HUVECs) and AGE-injected rat aortae. Here we examined the effects of aqueous extract of glucoraphanin-rich broccoli sprouts on formation of AGEs and then investigated whether the extract could attenuate inflammatory or oxidative stress reactions in tumor necrosis factor-alpha (TNF-α)- or AGE-exposed HUVECs. Fresh broccoli sprouts were homogenized in phosphate-buffered saline and filtered through a gauze. After centrifugation, clear extract was obtained. AGE formation was measured by enzyme-linked immunosorbent assay. Gene expression was evaluated by real-time reverse transcription-polymerase chain reaction. Reactive oxygen species (ROS) generation were measured using a fluorescent dye. Five percent broccoli sprout extract inhibited the formation of AGEs, reduced basal gene expressions of monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1,) and receptor for AGEs (RAGE), and upregulated endothelial nitric oxide synthase (eNOS) mRNA levels in HUVECs. TNF-α upregulated MCP-1, ICAM-1, and RAGE mRNA levels in HUVECs, all of which were attenuated by the treatment with 1% broccoli sprout extract. Pretreatment of 1% broccoli sprout extract prevented the ROS generation in HUVECs evoked by AGEs. The present study demonstrates that sulforaphane-rich broccoli sprout extract could inhibit the AGE-RAGE axis and exhibit anti-inflammatory actions in HUVECs. Supplementation of sulforaphane-rich broccoli sprout extract may play a protective role against vascular injury.

The Role of Advanced Glycation End Products in Diabetic Vascular Complications

In cases of chronic hyperglycemia, advanced glycation end-products (AGEs) are actively produced and accumulated in the circulating blood and various tissues. AGEs also accelerate the expression of receptors for AGEs, and they play an important role in the development of diabetic vascular complications through various mechanisms. Active interventions for glucose and related risk factors may help improve the clinical course of patients by reducing AGEs. This review summarizes recent updates on AGEs that have a significant impact on diabetic vascular complications.

Association of advanced glycation end products, evaluated by skin autofluorescence, with lifestyle habits in a general Japanese population

Objective

Accumulation of advanced glycation end products (AGEs) occurs during normal aging but markedly accelerates in people with diabetes. AGEs may play a role in various age-related disorders. Several studies have demonstrated that skin autofluorescence (SAF) reflects accumulated tissue levels of AGEs. However, very few studies have investigated SAF in the general population. The purpose of the present study was to more thoroughly evaluate the potential association among SAF, chronological age, and lifestyle habits in the general population.

Methods

A large cross-sectional survey of 10,946 Japanese volunteers aged 20 to 79 years was conducted. Volunteers completed a self-administered questionnaire and underwent SAF measurement on their dominant forearms. The associations of SAF with age and lifestyle habits were analyzed using a multiple stepwise regression analysis.

Results

Age was independently correlated with SAF. Lifestyle habits such as physical activity, nonsmoking, adequate sleep, low mental stress level, eating breakfast, and abstaining from sugary food were each independently associated with lower SAF.

Conclusions

SAF was associated with age and healthy lifestyle habits in this general Japanese population. The present study suggests that SAF measurement is a convenient tool for evaluating habitual lifestyle behaviors and may have potential for preventative health education.

Ratio of serum levels of AGEs to soluble RAGE is correlated with trimethylamine-N-oxide in non-diabetic subjects

Trimethylamine (TMA), an intestinal microflora-dependent metabolite formed from phosphatidylcholine- and L-carnitine-rich food, such as red meat, is further converted to trimethylamine-N-oxide (TMAO), which could play a role in cardiometabolic disease. Red meat-derived products are one of the major environmental sources of advanced glycation end products (AGEs) that may also contribute to the pathogenesis of cardiometabolic disorders through the interaction with receptor for AGEs (RAGE). However, the relationship among AGEs, soluble form of RAGE (sRAGE) and TMAO in humans remains unclear. Non-diabetic subjects underwent a physical examination, determination of blood chemistry and anthropometric variables, including AGEs, sRAGE, TMA and TMAO. Multiple regression analyses revealed that HbA1c, uric acid and AGEs were independently associated with log TMA, whereas log AGEs to sRAGE ratio and statin non-use were independently correlated with log TMAO. Our present findings indicated that AGEs to sRAGE ratio was correlated with log TMAO, a marker of cardiometabolic disorders.

Pathophysiological Fundamentals of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) was first recognized more than four decades ago and occurred independent of cardiovascular diseases or hypertension in both type 1 and type 2 diabetic patients. The exact mechanisms underlying this disease remain incompletely understood. Several pathophysiological bases responsible for DCM have been proposed, including the presence of hyperglycemia, nonenzymatic glycosylation of large molecules (e.g., proteins), energy metabolic disturbance, mitochondrial damage and dysfunction, impaired calcium handling, reactive oxygen species formation, inflammation, cardiac cell death, and cardiac hypertrophy and fibrosis, leading to impairment of cardiac contractile functions. Increasing evidence also indicates the phenomenon called "metabolic memory" for diabetes-induced cardiovascular complications, for which epigenetic modulation seemed to play an important role, suggesting that the aforementioned pathogenic bases may be regulated by epigenetic modification. Therefore, this review aims at briefly summarizing the current understanding of the pathophysiological bases for DCM. Although how epigenetic mechanisms play a role remains incompletely understood now, extensive clinical and experimental studies have implicated its importance in regulating the cardiac responses to diabetes, which are believed to shed insight into understanding of the pathophysiological and epigenetic mechanisms for the development of DCM and its possible prevention and/or therapy. © 2017 American Physiological Society. Compr Physiol 7:693-711, 2017.

Glycation and cardiovascular disease in diabetes: A perspective on the concept of metabolic memory

Epidemiological studies have suggested that cumulative diabetic exposure, namely prolonged exposure to chronic hyperglycemia, contributes to the increased risk of cardiovascular disease (CVD) in diabetes. The formation and accumulation of advanced glycation end-products (AGEs) have been known to progress under hyperglycemic conditions. Because AGEs-modified collagens are hardly degraded and remain in diabetic vessels, kidneys and the heart for a long time, even after glycemic control has been achieved, AGEs could become a marker reflecting cumulative diabetic exposure. Furthermore, there is a growing body of evidence that an interaction between AGEs and the receptor for AGEs (RAGE) plays a role in the pathogenesis of CVD. In addition, AGEs induce the expression of RAGE, thus leading to sustained activation of the AGEs-RAGE axis in diabetes. Herein we review the pathological role of the AGEs-RAGE axis in CVD, focusing particularly on the phenomenon of metabolic memory, and discuss the potential clinical usefulness of measuring circulating and tissue levels of AGEs accumulation to evaluate diabetic macrovascular complications.

Functional food supplements to ameliorate the secondary complications in high fructose fed diabetic rats

Poly-herbal functional food supplements inhibited high fructose induced glycation in diabetic rats and showed promise for effective management of secondary complications of diabetes such as improved lipid profile, kidney function and reduction of oxidative stress.

AGEs/sRAGE, a novel risk factor in the pathogenesis of end-stage renal disease

Interaction of advanced glycation end products (AGEs) with its cell-bound receptor (RAGE) results in cell dysfunction through activation of nuclear factor kappa-B, increase in expression and release of inflammatory cytokines, and generation of oxygen radicals. Circulating soluble receptors, soluble receptor (sRAGE), endogenous secretory receptor (esRAGE) and cleaved receptor (cRGAE) act as decoy for RAGE ligands and thus have cytoprotective effects. Low levels of sRAGE and esRAGE have been proposed as biomarkers for many diseases. However sRAGE and esRAGE levels are elevated in diabetes and chronic renal diseases and still tissue injury occurs. It is possible that increases in levels of AGEs are greater than increases in the levels of soluble receptors in these two diseases. Some new parameters have to be used which could be an universal biomarkers for cell dysfunction. It is hypothesized that increases in serum levels of AGEs are greater than the increases in the soluble receptors, and that the levels of AGEs is correlated with soluble receptors and that the ratios of AGEs/sRAGE, AGEs/esRAGE and AGEs/cRAGE are elevated in patients with end-stage renal disease (ESRD) and would serve as an universal risk marker for ESRD. The study subject comprised of 88 patients with ESRD and 20 healthy controls. AGEs, sRAGE and esRAGE were measured using commercially available enzyme linked immune assay kits. cRAGE was calculated by subtracting esRAGE from sRAGE. The data show that the serum levels of AGEs, sRAGE, cRAGE are elevated and that the elevation of AGEs was greater than those of soluble receptors. The ratios of AGEs/sRAGE, AGEs/esRAGE and AGEs/cRAGE were elevated and the elevation was similar in AGEs/sRAGE and AGEs/cRAGE but greater than AGEs/esRAGE. The sensitivity, specificity, accuracy, and positive and negative predictive value of AGEs/sRAGE and AGEs/cRAGE were 86.36 and 84.88 %, 86.36 and 80.95 %, 0.98 and 0.905, 96.2 and 94.8 %, and 61.29 and 56.67 % respectively. There was a positive correlation of sRAGE with esRAGE and cRAGE, and AGEs with esRAGE; and negative correlation between sRAGE and AGEs/sRAGE, esRAGE and AGES/esRAGE, and cRAGE and AGES/cRAGE. In conclusion, AGEs/sRAGE, AGEs/cRAGE and AGEs/esRAGE may serve as universal risk biomarkers for ESRD and that AGEs/sRAGE and AGEs/cRAGE are better risk biomarkers than AGEs/esRAGE.

DNA-aptamers raised against AGEs as a blocker of various aging-related disorders

A non-enzymatic reaction between sugars or aldehydes and the amino groups of proteins, lipids and nucleic acids contributes to the aging of macromolecules, which could impair their structural integrity and function. This process begins with the conversion of reversible Schiff base adducts, and then to more stable, covalently-bound Amadori rearrangement products. Over a course of days to weeks, these early glycation products undergo further reactions, such as rearrangements and dehydration to become irreversibly crossed-linked, fluorescent protein derivatives termed advanced glycation end products (AGEs). The formation and accumulation of AGEs have been known to progress in a physiological aging process and at an accelerated rate under hyperglycemic, inflammatory and oxidative stress conditions. There is a growing body of evidence that AGEs and their receptor RAGE interaction play a role in the pathogenesis of various devastating disorders, including cardiovascular disease, Alzheimer's disease, insulin resistance, osteoporosis and cancer growth and metastasis. Furthermore, diet has been recently recognized as a major environmental source of AGEs that could also elicit pro-inflammatory reactions, thereby being involved in organ damage in vivo. Therefore, inhibition of AGE formation and/or blockade of the interaction of AGEs with RAGE may be a novel therapeutic target for aging-related disorders. This article discusses a potential utility of DNA-aptamers raised against AGEs for preventing aging and/or diabetes-associated organ damage, especially focusing on diabetic microvascular complications, vascular remodeling, metabolic derangements, and melanoma growth and expansion in animal models.

Correlation among soluble receptors for advanced glycation end-products, soluble vascular adhesion protein-1/semicarbazide-sensitive amine oxidase (sVAP-1) and cardiometabolic risk markers in apparently healthy adolescents: a cross-sectional study

In non-diabetics, low levels of soluble receptor for advanced glycations end products (sRAGE) associate with an increased risk of development of diabetes, cardiovascular afflictions, or death. The majority of studies in non-diabetics report an inverse relationship between measures of obesity, cardiometabolic risk factors and sRAGE and/or endogenous secretory RAGE (esRAGE) levels. To elucidate whether this inconsistency is related to the metabolically healthy obese phenotype, or a different impact of the risk factors in presence and absence of obesity, we analyzed data from 2206 apparently healthy adolescents (51 % girls) aged 15-to-19 years. The association of sRAGE levels with soluble vascular adhesion protein-1/semicarbazide sensitive amine oxidase (sVAP-1/SSAO) was also investigated. Centrally obese, including metabolically healthy, adolescents present significantly lower sRAGE and esRAGE, but not sVAP-1, levels in comparison with their lean counterparts. An increasing number of cardiometabolic risk factors did not associate with significant changes in sRAGE, esRAGE or sVAP-1 levels either in lean or in obese subjects. In multivariate analyses, WHtR, hsCRP, markers of glucose homeostasis, renal function, adiponectin, and sVAP-1 associated significantly with sRAGE and esRAGE. SVAP-1 correlated significantly with glycemia, adiponectin, hsCRP, and sRAGE. Thus, in adolescents, a decline in sRAGE and esRAGE precedes the development of metabolic syndrome. When combined, standard and non-standard cardiometabolic risk factors explain only minor proportion in a variability of sRAGE and esRAGE (8 %-11 %); or sVAP-1 (12 %-20 %). Elucidation of pathogenetic mechanisms underlying early decline in sRAGE and esRAGE levels in obese adolescents and their clinical impact with regard to future cardiometabolic health requires further studies.

Phenolics from Garcinia mangostana Inhibit Advanced Glycation Endproducts Formation: Effect on Amadori Products, Cross-Linked Structures and Protein Thiols

Accumulation of Advanced Glycation Endproducts (AGEs) in body tissues plays a major role in the development of diabetic complications. Here, the inhibitory effect of bioactive metabolites isolated from fruit hulls of Garcinia mangostana on AGE formation was investigated through bio-guided approach using aminoguanidine (AG) as a positive control. Including G. mangostana total methanol extract (GMT) in the reaction mixture of bovine serum albumin (BSA) and glucose or ribose inhibited the fluorescent and non-fluorescent AGEs formation in a dose dependent manner. The bioassay guided fractionation of GMT revealed isolation of four bioactive constituents from the bioactive fraction; which were identified as: garcimangosone D (1), aromadendrin-8-C-glucopyranoside (2), epicatechin (3), and 2,3',4,5',6-pentahydroxybenzophenone (4). All the tested compounds significantly inhibited fluorescent and non-fluorescent AGEs formation in a dose dependent manner whereas compound 3 (epicatechin) was found to be the most potent. In search for the level of action, addition of GMT, and compounds 2-4 inhibited fructosamine (Amadori product) and protein aggregation formation in both glucose and ribose. To explore the mechanism of action, it was found that addition of GMT and only compound (3) to reaction mixture increased protein thiol in both glucose and ribose while compounds 1, 2 and 4 only increased thiol in case of ribose. In conclusion, phenolic compounds 1-4 inhibited AGEs formation at the levels of Amadori product and protein aggregation formation through saving protein thiol.

Diabetic Cardiovascular Disease Induced by Oxidative Stress

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with diabetes mellitus (DM). DM can lead to multiple cardiovascular complications, including coronary artery disease (CAD), cardiac hypertrophy, and heart failure (HF). HF represents one of the most common causes of death in patients with DM and results from DM-induced CAD and diabetic cardiomyopathy. Oxidative stress is closely associated with the pathogenesis of DM and results from overproduction of reactive oxygen species (ROS). ROS overproduction is associated with hyperglycemia and metabolic disorders, such as impaired antioxidant function in conjunction with impaired antioxidant activity. Long-term exposure to oxidative stress in DM induces chronic inflammation and fibrosis in a range of tissues, leading to formation and progression of disease states in these tissues. Indeed, markers for oxidative stress are overexpressed in patients with DM, suggesting that increased ROS may be primarily responsible for the development of diabetic complications. Therefore, an understanding of the pathophysiological mechanisms mediated by oxidative stress is crucial to the prevention and treatment of diabetes-induced CVD. The current review focuses on the relationship between diabetes-induced CVD and oxidative stress, while highlighting the latest insights into this relationship from findings on diabetic heart and vascular disease.

Contribution of the toxic advanced glycation end-products-receptor axis in nonalcoholic steatohepatitis-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The main etiologies of HCC are hepatitis B virus and hepatitis C virus (HCV), and non-hepatitis B/non-hepatitis C HCC (NBNC-HCC) has also been identified as an etiological factor. Although the incidence of HCV-related HCC in Japan has decreased slightly in recent years, that of NBNC-HCC has increased. The onset mechanism of NBNC-HCC, which has various etiologies, remains unclear; however, nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is known to be an important risk factor for NBNC-HCC. Among the different advanced glycation end-products (AGEs) formed by the Maillard reaction, glyceraldehyde-derived AGEs, the predominant components of toxic AGEs (TAGE), have been associated with NASH and NBNC-HCC, including NASH-related HCC. Furthermore, the expression of the receptor for AGEs (RAGE) has been correlated with the malignant progression of HCC. Therefore, TAGE induce oxidative stress by binding with RAGE may, in turn, lead to adverse effects, such as fibrosis and malignant transformation, in hepatic stellate cells and tumor cells during NASH or NASH-related HCC progression. The aim of this review was to examine the contribution of the TAGE-RAGE axis in NASH-related HCC.

Pathologic role of dietary advanced glycation end products in cardiometabolic disorders, and therapeutic intervention

Reactive derivatives from nonenzymatic glucose-protein condensation reactions, as well as lipids and nucleic acids exposed to reducing sugars, form a heterogeneous group of irreversible adducts called AGEs (advanced glycation end products). The glycation process begins with the conversion of reversible Schiff base adducts to more stable, covalently bound Amadori rearrangement products. Over the course of days to weeks, these Amadori products undergo further rearrangement and condensation reactions to form irreversibly cross-linked macroprotein derivatives known as AGEs. The formation and accumulation of AGEs have been known to progress in a physiological aging process and at an accelerated rate under hyperglycemic and oxidative stress conditions. There is growing evidence that AGEs play a pathologic role in numerous disorders. Indeed, glycation and/or cross-linking modification of circulating or organic matrix proteins by AGEs the senescence of moieties and deteriorate their physiological function and structural integrity in multiple organ systems. Moreover, AGEs elicit oxidative stress and inflammatory reactions through the interaction with the receptor for advanced glycation products in a variety of cells, thereby contributing to the development and progression of various aging- or diabetes-related disorders, such as cardiovascular disease, chronic kidney disease, insulin resistance, and Alzheimer's disease. Recently, diet has been recognized as a major environmental source of AGEs that could cause proinflammatory reactions and organ damage in vivo. Therefore, this review summarizes the pathophysiological role of dietary AGEs in health and disease, especially focusing on cardiometabolic disorders. We also discuss the potential utility in targeting exogenously derived AGEs for therapeutic intervention.

Are there new approaches for diagnosis, therapy guidance and outcome prediction of sepsis?

Beside many efforts to improve outcome, sepsis is still one of the most frequent causes of death in critically ill patients. It is the most common condition with high mortality in intensive care units. The complexity of the septic syndrome comprises immunological aspects - i.e., sepsis induced immunosuppression - but is not restricted to this fact in modern concepts. So far, exact mechanisms and variables determining outcome and mortality stay unclear. Since there is no typical risk profile, early diagnosis and risk stratification remain difficult, which hinders rapid and effective treatment initiation. Due to the heterogeneous nature of sepsis, potential therapy options should be adapted to the individual. Biomarkers like C-reactive protein and procalcitonin are routinely used as complementary tools in clinical decision-making. Beyond the acute phase proteins, a wide bunch of promising substances and non-laboratory tools with potential diagnostic and prognostic value is under intensive investigation. So far, clinical decision just based on biomarker assessment is not yet feasible. However, biomarkers should be considered as a complementary approach.

Crosstalk between red blood cells and the immune system and its impact on atherosclerosis

Atherosclerosis is a chronic multifactorial disease of the arterial wall characterized by inflammation, oxidative stress, and immune system activation. Evidence exists on a pathogenic role of oxidized red blood cells (RBCs) accumulated in the lesion after intraplaque hemorrhage. This review reports current knowledge on the impact of oxidative stress in RBC modifications with the surface appearance of senescent signals characterized by reduced expression of CD47 and glycophorin A and higher externalization of phosphatidylserine. The review summarizes findings indicating that oxidized, senescent, or stored RBCs, due to surface antigen modification and release of prooxidant and proinflammatory molecules, exert an impaired modulatory activity on innate and adaptive immune cells and how this activity contributes to atherosclerotic disease. In particular RBCs from patients with atherosclerosis, unlike those from healthy subjects, fail to control lipopolysaccharide-induced DC maturation and T lymphocyte apoptosis. Stored RBCs, accompanied by shedding of extracellular vesicles, stimulate peripheral blood mononuclear cells to release proinflammatory cytokines, augment mitogen-driven T cell proliferation, and polarize macrophages toward the proinflammatory M1 activation pathway. Collectively, literature data suggest that the crosstalk between RBCs with immune cells represents a novel mechanism by which oxidative stress can contribute to atherosclerotic disease progression and may be exploited for therapeutic interventions.

RAGE gene polymorphism and environmental factor in the risk of oral cancer

Oral squamous cell carcinoma is a common neoplasm that is known to be causally associated with genetic factors and environmental carcinogens. The receptor for advanced glycosylation endproducts (RAGE) is a transmembrane protein of the immunoglobulin superfamily with broad specificity for multiple ligands, and it has been shown to play vital roles in several pathophysiologic processes, including diabetes, Alzheimer disease, renal disease, cardiovascular disease, and cancer. The present study aimed to assess the influences of RAGE gene polymorphisms, combined with environmental carcinogens on the predisposition to oral tumorigenesis. Five polymorphisms of the RAGE gene-including -374T>A (rs1800624), -429T>C (rs1800625), 1704G>T (rs184003), Gly82Ser (rs2070600), and a 63-bp deletion allele (-407 to -345)-were examined from 592 controls and 618 patients with oral cancer. We found that individuals carrying the polymorphic allele of rs1800625 are more susceptible to oral cancer (odds ratio [OR], 1.899; 95% confidence interval [CI], 1.355 to 2.661; adjusted OR [AOR], 2.053; 95% CI, 1.269 to 3.345) after adjustment for age, sex, betel nut chewing, and tobacco consumption. Moreover, we observed a significant association of rs1800625 variants with late-stage tumors (stage III/IV, OR, 1.736; 95% CI, 1.126 to 2.677; AOR, 1.771; 95% CI, 1.101 to 2.851) and large-size tumors (>2 cm in the greatest dimension; OR, 1.644; 95% CI, 1.083 to 2.493; AOR, 1.728; 95% CI, 1.089 to 2.741). Based on behavioral exposure of environmental carcinogens, the presence of 4 RAGE single-nucleotide polymorphisms (SNPs), combined with betel quid chewing and/or tobacco use, greatly augmented the risk of oral cancer. In addition, carriers of particular haplotypes of the 4 RAGE SNPs examined are more prone to develop oral cancer. These results indicate an involvement of RAGE SNP rs1800625 in the development of oral squamous cell carcinoma and implicate the interaction between RAGE gene polymorphisms and environmental mutagens as a predisposing factor of oral carcinogenesis.

Involvement of the TAGE-RAGE system in non-alcoholic steatohepatitis: Novel treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver disease around the world. It includes a spectrum of conditions from simple steatosis to non-alcoholic steatohepatitis (NASH) and can lead to fibrosis, cirrhosis, liver failure, and/or hepatocellular carcinoma. NAFLD is also associated with other medical conditions such as obesity, diabetes mellitus (DM), metabolic syndrome, hypertension, insulin resistance, hyperlipidemia, and cardiovascular disease (CVD). In diabetes, chronic hyperglycemia contributes to the development of both macro- and microvascular conditions through a variety of metabolic pathways. Thus, it can cause a variety of metabolic and hemodynamic conditions, including upregulated advanced glycation end-products (AGEs) synthesis. In our previous study, the most abundant type of toxic AGEs (TAGE); i.e., glyceraldehyde-derived AGEs, were found to make a significant contribution to the pathogenesis of DM-induced angiopathy. Furthermore, accumulating evidence suggests that the binding of TAGE with their receptor (RAGE) induces oxidative damage, promotes inflammation, and causes changes in intracellular signaling and the expression levels of certain genes in various cell populations including hepatocytes and hepatic stellate cells. All of these effects could facilitate the pathogenesis of hypertension, cancer, diabetic vascular complications, CVD, dementia, and NASH. Thus, inhibiting TAGE synthesis, preventing TAGE from binding to RAGE, and downregulating RAGE expression and/or the expression of associated effector molecules all have potential as therapeutic strategies against NASH. Here, we examine the contributions of RAGE and TAGE to various conditions and novel treatments that target them in order to prevent the development and/or progression of NASH.

Involvement of the TAGE-RAGE system in non-alcoholic steatohepatitis: Novel treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is a major cause of liver disease around the world. It includes a spectrum of conditions from simple steatosis to non-alcoholic steatohepatitis (NASH) and can lead to fibrosis, cirrhosis, liver failure, and/or hepatocellular carcinoma. NAFLD is also associated with other medical conditions such as obesity, diabetes mellitus (DM), metabolic syndrome, hypertension, insulin resistance, hyperlipidemia, and cardiovascular disease (CVD). In diabetes, chronic hyperglycemia contributes to the development of both macro- and microvascular conditions through a variety of metabolic pathways. Thus, it can cause a variety of metabolic and hemodynamic conditions, including upregulated advanced glycation end-products (AGEs) synthesis. In our previous study, the most abundant type of toxic AGEs (TAGE); i.e., glyceraldehyde-derived AGEs, were found to make a significant contribution to the pathogenesis of DM-induced angiopathy. Furthermore, accumulating evidence suggests that the binding of TAGE with their receptor (RAGE) induces oxidative damage, promotes inflammation, and causes changes in intracellular signaling and the expression levels of certain genes in various cell populations including hepatocytes and hepatic stellate cells. All of these effects could facilitate the pathogenesis of hypertension, cancer, diabetic vascular complications, CVD, dementia, and NASH. Thus, inhibiting TAGE synthesis, preventing TAGE from binding to RAGE, and downregulating RAGE expression and/or the expression of associated effector molecules all have potential as therapeutic strategies against NASH. Here, we examine the contributions of RAGE and TAGE to various conditions and novel treatments that target them in order to prevent the development and/or progression of NASH.