The different roles for the advanced glycation end products axis in heart failure and acute coronary syndrome settings

The role of sRAGE in cardiovascular diseases

Advanced glycation end products (AGEs), by-products of glucose metabolism, have been linked to the emergence of cardiovascular disorders (CVD). AGEs can cause tissue damage in four different ways: (1) by altering protein function, (2) by crosslinking proteins, which makes tissue stiffer, (3) by causing the generation of free radicals, and (4) by activating an inflammatory response after binding particular AGE receptors, such as the receptor for advanced glycation end products (RAGE). It is suggested that the soluble form of RAGE (sRAGE) blocks ligand-mediated pro-inflammatory and oxidant activities by serving as a decoy. Therefore, several studies have investigated the possible anti-inflammatory and anti-oxidant characteristics of sRAGE, which may help lower the risk of CVD. According to the results of various studies, the relationship between circulating sRAGE, cRAGE, and esRAGE and CVD is inconsistent. To establish the potential function of sRAGE as a therapeutic target in the treatment of cardiovascular illnesses, additional studies are required to better understand the relationship between sRAGE and CVD. In this review, we explored the potential function of sRAGE in different CVD, highlighting unanswered concerns and outlining the possibilities for further investigation.

Advanced glycation end-products, cardiac function and heart failure in the general population: The Rotterdam Study

AIMS/HYPOTHESIS

The aim of this work was to assess the association of advanced glycation end-products (AGEs), measured by skin autofluorescence (SAF), with prevalent heart failure, and with systolic and diastolic cardiac function, in a large population-based cohort study.

METHODS

We assessed the cross-sectional association between SAF and prevalent heart failure among 2426 participants from the population-based Rotterdam Study, using logistic regression. Next, among individuals free of heart failure (N=2362), we examined the link between SAF (on a continuous scale) and echocardiographic parameters of left ventricular (LV) systolic and diastolic function using linear regressions. Analyses were adjusted for traditional cardiovascular risk factors.

RESULTS

Higher levels of SAF were associated with higher odds of prevalent heart failure (multivariable adjusted OR 2.90 [95% CI 1.80, 4.62] for one unit higher SAF value). Among individuals without heart failure, one unit increase in SAF was associated with 0.98% lower LV ejection fraction (mean difference [β] -0.98% [95% CI -1.45%, -0.50%]). The association was stronger among participants with diabetes (β -1.84% [95% CI -3.10%, -0.58%] and β -0.78% [95% CI -1.29%, -0.27%] among participants with and without diabetes, respectively). Associations of SAF with diastolic function parameters were not apparent, except in men with diabetes.

CONCLUSIONS/INTERPRETATION

AGE accumulation was independently associated with prevalent heart failure. Among individuals free of heart failure, AGEs were associated with cardiac function, in particular systolic function. This association was present in participants with and without diabetes and was more prominent in those with diabetes.

Emerging Biomarkers for Predicting Clinical Outcomes in Patients with Heart Disease

Cardiovascular disease is most frequently caused by the development and progression of atherosclerosis. When coronary arteries are afflicted, and the stenoses caused by atherosclerotic plaques are severe enough, the metabolic supply-and-offer balance is disturbed, leading to myocardial ischemia. If atherosclerotic plaques become unstable and local thrombosis develops, a myocardial infarction occurs. Sometimes, myocardial ischemia and infarction may result in significant and irreversible heart failure. To prevent severe complications, such as acute coronary syndromes and ischemia-related heart failure, extensive efforts have been made for developing biomarkers that would help identify patients at increased risk for cardiovascular events. In this two-part study, we attempted to provide a review of existing knowledge of blood biomarkers that may be used in this setting. The first part of this work was dedicated to conventional biomarkers, which are already used in clinical practice. In the second part, here presented, we discuss emerging biomarkers which have not yet become mainstream.

Correlation Analysis of CML, sRAGE, and esRAGE and the Measure of Atherosclerosis of Coronary Heart Disease

Objective

To investigate the correlation between CML, sRAGE, and esRAGE and the measure of atherosclerosis of coronary heart disease.

Methods

From June 2019 to December 2021, there were 100 patients in all suffering from coronary heart disease (CHD) selected as the observation group. On the basis of Gensini score, they were divided into mild group (Gensini score < 12 points), moderate group (12 points ≤ Gensini score ≤60 points), and severe group (Gensini score > 60). Apart from that, 50 normal people staying in our hospital for physical examination were chosen as the control group in the meantime. N in each group was detected and compared ε-Carboxymethyl lysine (CML), soluble advanced glycation end product receptor (sRAGE), and endogenous secretory advanced glycation end product receptor (esRAGE). Pearson correlation coefficient was adapted to assay the relevance between CML, sRAGE, and esRAGE, as well as the degree of atherosclerosis in CHD. Receiver operator characteristic (ROC) curve was applied to during the evaluation of the diagnosis of CML, sRAGE, and esRAGE, as well as their combined detection of severe atherosclerosis in CHD.

Results

In contrast with the control group, the level of serum CML together with sRAGE in the observation group was considerably elevated, while the level of esRAGE appeared in a downward trend (P < 0.05). The level of serum CML and sRAGE was directly proportional to the measure of atherosclerosis in CHD, while the level of esRAGE was inversely proportional to the measure of atherosclerosis in CHD (P < 0.05). That is to say that serum CML and sRAGE were positive in matter of the measure of atherosclerosis in CHD, while esRAGE negatively appertains to the measure of atherosclerosis in CHD (P < 0.05). Serum CML, sRAGE, and esRAGE could effectively diagnose severe atherosclerosis in CHD, and the combined detection sensitivity (89.79%), specificity (77.16%), accuracy (86.12%), positive predictive value (86.63%), negative predictive value (88.59%), and area under ROC curve (AUC) (0.924) were higher (P < 0.05).

Conclusion

CML and sRAGE, as well as esRAGE, are bound up with the degree of atherosclerosis in CHD, which is conducive to clinical diagnosis and treatment.

AGEs-RAGE axis mediates myocardial fibrosis via activation of cardiac fibroblasts induced by autophagy in heart failure

NEW FINDINGS

What is the central question of this study? Does the AGEs-RAGE axis mediate myocardial fibrosis in heart failure? What is the main finding and its importance? The AGEs-RAGE axis is involved in the pathogenesis of myocardial fibrosis through CFs activation induced by autophagy in heart failure. Inhibiting AGEs-RAGE axis attenuates dysfunction in the heart and attenuates myocardial fibrosis in mice with TAC via suppressing CFs activation.

ABSTRACT

Background: Heart failure is the end stage of cardiovascular diseases, and is a critical medical condition that poses an important therapeutic challenge for physicians due to its high morbidity and mortality. Myocardial fibrosis is part of the remodeling process that occurs in heart failure. Many studies have shown that advanced glycation end products (AGEs) and receptor for advanced glycation end products (RAGE) are implicated in fibrosis and autophagy, but the mechanism remains unclear. In this study, we elucidate the mechanism by which the AGEs-RAGE axis mediates activation of cardiac fibroblasts (CFs) in heart failure.

METHODS AND RESULTS

We used C57BL/6J wild-type (WT) mice to establish a model of heart failure by transverse aortic constriction (TAC). After 6 weeks of treatment, relevant indicators were detected. In mice subjected to TAC, AGEs were upregulated compared with sham mice. Inhibition of RAGE resulted in functional cardiac protection with reduced hypertrophy and fibrosis in mice after TAC. Of note, autophagy mediated the activation of CFs that transformed to myofibroblasts and contributed to fibrosis. In vitro, CFs were obtained from neonatal Sprague-Dawley rats and treated with AGEs-BSA and short hairpin RNA (shRNA) for RAGE, which to verify the results in vivo.

CONCLUSIONS

These results suggest that the AGEs-RAGE axis is involved in the pathogenesis of myocardial fibrosis through CF activation induced by autophagy in heart failure. Inhibiting the AGEs-RAGE axis attenuates dysfunction in the heart and attenuates myocardial fibrosis in mice with TAC via suppressing CF activation. This article is protected by copyright. All rights reserved.

Advanced Glycation End Products: A Sweet Flavor That Embitters Cardiovascular Disease

Epidemiological studies demonstrate the role of early and intensive glycemic control in the prevention of micro and macrovascular disease in both type 1 and type 2 diabetes mellitus (DM). Hyperglycemia elicits several pathways related to the etiopathogenesis of cardiovascular disease (CVD), including the generation of advanced glycation end products (AGEs). In this review, we revisit the role played by AGEs in CVD based in clinical trials and experimental evidence. Mechanistic aspects concerning the recognition of AGEs by the advanced glycosylation end product-specific receptor (AGER) and its counterpart, the dolichyl-diphosphooligosaccharide-protein glycosyltransferase (DDOST) and soluble AGER are discussed. A special focus is offered to the AGE-elicited pathways that promote cholesterol accumulation in the arterial wall by enhanced oxidative stress, inflammation, endoplasmic reticulum stress and impairment in the reverse cholesterol transport (RCT).

Soluble angiotensin-converting enzyme levels in heart failure or acute coronary syndrome: revisiting its modulation and prognosis value

The main objective was to compare the meaning of soluble angiotensin-converting enzyme-2 (sACE2) plasma levels modulation on the prognosis of two cohorts of heart failure (HF) and acute coronary syndrome (ACS). We conducted an observational clinical study where sACE2 was measured in two cohorts of HF or ACS (102 patients each), matched by age and gender. The primary endpoint (cardiac death) and the secondary endpoints (non-fatal myocardial infarction or HF readmission) were registered during a 5-year follow-up period. Association with pharmacotherapy was studied, and the effects of cardiovascular drugs on ACE isoforms expression were analysed in human umbilical vein endothelial cells (HUVEC) in vitro. The levels of sACE2 were significantly higher in the HF than ACS cohort. sACE2 was inversely related with the leukocytes number and directly with urea levels. In the ACS cohort, sACE2 was associated with age and glycaemic parameters, but in the HF cohort, the association was with N-terminal pro-B-type natriuretic peptide. The levels of sACE2 were related to long-term prognosis and confirmed as a non-independent predictor in the HF cohort. Soluble ACE2 was higher in patients treated with angiotensin receptors blockers and β-blockers, accordingly with losartan and metoprolol upregulation of ACE1 and ACE2 in HUVECs. Plasma levels of sACE2 were higher in HF than in ACS, independently of age and gender, and were related to long-term cardiac death in the HF cohort. Losartan and metoprolol, but not enalapril, upregulated ACE expression in endothelial cells, accordingly with higher levels of sACE2 in patients using these drugs.

Potential Therapeutic Benefits of Sodium-Glucose Cotransporter 2 Inhibitors in the Context of Ischemic Heart Failure: A State-Of-The-Art Review

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a class of anti-diabetic agents that block the reabsorption of glucose in the proximal convoluted tubule of the nephron, thereby contributing to glycosuria and lowering blood glucose levels. SGLT2 inhibitors have been associated with improved cardiovascular outcomes in patients with diabetes, including a reduced risk of cardiovascular death and hospitalizations for heart failure. Recently, DAPA-HF and EMPEROR REDUCED trials showed the beneficial cardiovascular effect of SGLT2 inhibitors in patients with heart failure with consistently reduced ejection fraction (HFrEF) regardless of the presence of diabetes. Moreover, some exploratory studies suggested that these drugs improve Left Ventricular (LV) systolic function and oppose LV adverse remodeling in patients with HFrEF. However, the exact mechanisms that mediated for this benefit are not fully understood. Beyond glycemic control, enhanced natriuresis, increased erythropoiesis, improved endothelial function, changes in myocardial metabolism, anti-inflammatory and anti-oxidative properties may all play an active role in SGLT2 inhibitors' cardiovascular benefits. A deep understanding of the pathophysiological interplay is key to define which HF phenotype could benefit more from SGLT2 inhibitors. Current clinical evidence on the comparison of different HF etiologies is limited to posthoc subgroup analysis of DAPA-HF and EMPEROR-REDUCED, which showed similar outcomes in patients with or without ischemic HF. On the other hand, in earlier studies of patients suffering from diabetes, rates of classic ischemic endpoints, such as myocardial infarction, stroke or coronary revascularization, did not differ between patients treated with SGLT2 inhibitors or placebo. The aim of this review is to discuss whether SGLT2 inhibitors may improve prognosis in patients with ischemic HF, not only in terms of reducing re-hospitalizations and improving left ventricular function but also by limiting coronary artery disease progression and ischemic burden.

Emergence of SGLT2 Inhibitors as Powerful Antioxidants in Human Diseases

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of oral glucose-lowering agents. Apart from their glucose-lowering effects, large clinical trials assessing certain SGLT2 inhibitors have revealed cardiac and renal protective effects in non-diabetic patients. These excellent outcomes motivated scientists and clinical professionals to revisit their underlying mechanisms. In addition to the heart and kidney, redox homeostasis is crucial in several human diseases, including liver diseases, neural disorders, and cancers, with accumulating preclinical studies demonstrating the therapeutic benefits of SGLT2 inhibitors. In the present review, we aimed to update recent advances in the antioxidant roles of SGLT2 inhibitors in common but debilitating human diseases. We anticipate that this review will guide new research directions and novel therapeutic strategies for diabetes, cardiovascular diseases, nephropathies, liver diseases, neural disorders, and cancers in the era of SGLT2 inhibitors.

Circulating Advanced Glycation End Products and Their Soluble Receptors in Relation to All-Cause and Cardiovascular Mortality: A Systematic Review and Meta-analysis of Prospective Observational Studies

Advanced glycation end products (AGEs) are involved in the development of several age-related complications. The protective role of soluble receptors for AGEs (sRAGE) against deleterious effects of AGEs has been indicated in several studies. However, findings on the association of AGEs or sRAGE with mortality are equivocal. In this meta-analysis we aimed to present a quantitative estimation of the association between circulating AGEs or sRAGE and all-cause or cardiovascular disease (CVD) mortality. A comprehensive literature search was performed to determine relevant publications through the online databases including PubMed, Scopus, and Web of Science up to 29 November 2020. Prospective observational studies assessing the association between circulating AGEs or sRAGE and all-cause or CVD mortality were included. Seven studies with a total of 3718 participants and 733 mortality cases (345 CVD deaths) were included in the meta-analysis for assessing the association between circulating AGEs and mortality. Our results showed that higher circulating AGEs were associated with increased risk of all-cause (pooled effect measure: 1.05; 95% CI: 1.01, 1.09; P = 0.018, I2 = 77.7%) and CVD mortality (pooled effect measure: 1.08; 95% CI: 1.01, 1.14; P = 0.015, I2 = 80.2%), respectively. The association between sRAGE and mortality was assessed in 14 studies with a total of 16,335 participants and 2844 mortality cases (419 CVD deaths). Serum concentrations of sRAGE were not associated with the risk of all-cause mortality (pooled effect measure: 1.01; 95% CI: 1.00, 1.01; P = 0.205, I2 = 75.5%), whereas there was a significant link between sRAGE and the risk of CVD mortality (pooled effect measure: 1.02; 95% CI: 1.00, 1.04; P = 0.02, I2 = 78.9%). Our findings showed that a higher serum AGE concentration was associated with increased risk of all-cause and CVD mortality. In addition, higher circulating sRAGE was related to increased risk of CVD mortality. This review was registered at PROSPERO as CRD42021236559.

Knockout RAGE alleviates cardiac fibrosis through repressing endothelial-to-mesenchymal transition (EndMT) mediated by autophagy

Endothelial-to-mesenchymal transition (EndMT) has been shown to contribute to cardiac fibrosis and heart failure (HF). Recent studies have demonstrated that EndMT is regulated by autophagy, and we previously showed suppression of excessive autophagy and alleviation of cardiac fibrosis in HF mice with inactivated receptor for advanced glycation end products (RAGE). Thus, we investigated whether reduced cardiac fibrosis due to RAGE knockout occurred by inhibiting EndMT mediated by excessive autophagy. We found a decrease in endothelial cells (CD31+/VE-Cadherin+) and an increase in cells co-expressing CD31 and α-smooth muscle actin (α-SMA, myofibroblast marker) at 8 weeks in heart tissue of mice subjected to transverse aortic constriction (TAC), which implied EndMT. Knockout RAGE decreased EndMT accompanied by decreased expression of autophagy-related proteins (LC3BII/I and Beclin 1), and alleviated cardiac fibrosis and improved cardiac function in TAC mice. Moreover, 3-methyladenine (3-MA) and chloroquine (CQ), inhibitors of autophagy, attenuated EndMT, and cardiac fibrosis in TAC mice. Importantly, EndMT induced by AGEs could be blocked by autophagy inhibitor in vivo and in vitro. These results suggested that AGEs/RAGE-autophagy-EndMT axis involved in the development of cardiac fibrosis and knockout RAGE ameliorated cardiac fibrosis through decreasing EndMT regulated by autophagy, which could be a promising therapeutic strategy for HF.

The use of the soluble receptor for advanced glycation-end products (sRAGE) as a potential biomarker of disease risk and adverse outcomes

The soluble receptor for advanced glycation end-products (sRAGE) has been classically considered a sink for pro-inflammatory RAGE ligands and as such has been associated with protection from inflammatory stress and disease. An alternative, though not mutually exclusive view is that high levels of sRAGE in circulation reflect the overstimulation of cell surface RAGE which if persistent, lead to the amplification of pro-inflammatory processes and the exacerbation of pathological states. With these two scenarios in mind this review focuses on the potential role of sRAGE as a prospective biomarker of disease risk and adverse outcomes.

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The prognostic value of measuring sRAGE levels in blood is subjected to debate.

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Raised sRAGE levels may result from the overstimulation of cell surface RAGE.

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Raised sRAGE may reflect chronic inflammation and multimorbidity rather than a healthy state.

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sRAGE is a promising biomarker of disease risk and adverse outcomes.

Mechanisms and Perspectives of Sodium-Glucose Co-transporter 2 Inhibitors in Heart Failure

Heart failure (HF) is a common complication or late-stage manifestation of various heart diseases. Numerous risk factors and underlying causes may contribute to the occurrence and progression of HF. The pathophysiological mechanisms of HF are very complicated. Despite accumulating advances in treatment for HF during recent decades, it remains an intractable clinical syndrome with poor outcomes, significantly reducing the quality of life and expectancy of patients, and imposing a heavy economic burden on society and families. Although initially classified as antidiabetic agents, sodium-glucose co-transporter 2 (SGLT2) inhibitors have demonstrated reduced the prevalence of hospitalization for HF, cardiovascular death, and all-cause death in several large-scale randomized controlled clinical trials. These beneficial effects of SGLT-2 inhibitors can be attributed to multiple hemodynamic, inflammatory and metabolic mechanisms, not only reducing the serum glucose level. SGLT2 inhibitors have been used increasingly in treatment for patients with HF with reduced ejection fraction due to their surprising performance in improving the prognosis. In addition, their roles and mechanisms in patients with HF with preserved ejection fraction or acute HF have also attracted attention. In this review article, we discuss the possible mechanisms and applications of SGLT2 inhibitors in HF.

SGLT2 inhibitors: mechanisms of cardiovascular benefit beyond glycaemic control

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are effective antidiabetic therapies in patients with type 2 diabetes mellitus and are associated with improved glycaemic control as well as with reductions in body mass and blood pressure. In large cardiovascular outcome trials in patients with diabetes, SGLT2 inhibitors improve cardiovascular and renal outcomes, including hospitalization for heart failure, with this benefit extending to patients without diabetes who have heart failure with reduced ejection fraction. The possible mechanisms of benefit are being extensively investigated because they are unlikely to be related to improved glycaemic control. Early natriuresis with a reduction in plasma volume, a consequent rise in haematocrit, improved vascular function, a reduction in blood pressure and changes in tissue sodium handling are all likely to have a role. Additional mechanisms of SGLT2 inhibitors that might be beneficial include a reduction in adipose tissue-mediated inflammation and pro-inflammatory cytokine production, a shift towards ketone bodies as the metabolic substrate for the heart and kidneys, reduced oxidative stress, lowered serum uric acid level, reduced glomerular hyperfiltration and albuminuria, and suppression of advanced glycation end-product signalling. Further outcome trials and mechanistic studies, including in patients with heart failure with preserved ejection fraction or non-diabetic kidney disease, might identify other possible mechanisms of benefit of SGLT2-inhibitor therapy.