A.G.E.s & My heart research

Role of advanced glycation end products in cardiovascular disease

Impact Factor: 

Level of Evidence: 1  

Study type: review article 

Sample size: N/A   

Methods: N/A   

Statistical tests: N/A   

Results: Many of the studies reviewed in this article provided experimental evidence that supports a link between serum AGE levels and the onset and progression of heart failure (HF). Given this correlation, the development of therapeutic regimes that target and reduce AGE levels may ultimately be beneficial in treating patients with HF.   

Discussion: The negative impact of AGEs on cellular functioning is likely associated with their ability to cross link intracellular and extracellular proteins, which ultimately alters the function of affected cells/tissues. With regards to the pathogenesis of HF, AGEs might have a significant role in its development and progression either via indirect mechanisms mediated through enhancing coronary artery disease or directly by inducing myocardial damage independent of vascular effects. Preliminary data suggests that targeting AGEs therapeutically may represent a novel treatment strategy in the management of DM and its cardiovascular complications. 

Hegab Z, Gibbons S, Neyses L, Mamas MA. Role of advanced glycation end products in cardiovascular disease. World J Cardiol. 2012 Apr 26;4(4):90-102. doi: 10.4330/wjc.v4.i4.90. PMID: 22558488; PMCID: PMC3342583.

Advanced glycation end-products (AGEs) and heart failure: Pathophysiology and clinical implications

Impact Factor: 11.627 (2019) 

Level of Evidence: Level V 

Type of Study and any information related to it: Literature Review 

Important Methods: Literature Review of previous published articles exploring the (current as of 2007) research of AGE’s and the pathophysiologic side effects.

Results: 

Diastolic Heart Failure: Levels of carboxymethyllysine (CML) had a correlation to diastolic function when measured with cardiac catheterization. Rat model of induced diabetes led to decreased compliance of the left ventricle. Aminoguanidine improved myocardial compliance but there was noted toxicity which raised safety issues. ALT-711 showed a significant reduction in age-related left ventricular stiffness measured by cardiac catheterization after a four week treatment. Showed improved diastolic dysfunction in humans, however study flaw in both DIAMOND trials and PEDESTAL trials due to open label design. 

Systolic Heart Failure: Reviews show that AGE-lowering treatments have no effect on systolic function but AGE-lowering therapies appear to improve systolic function in animals with systolic dysfunction. ALT-711 restored Left Ventricular systolic function and reduced aortic stiffness and left ventricle mass in diabetic dogs. Treatment with either C16 or ALT-711 in a rat design show significantly improved cardiac output, reduced total peripheral resistance and increased systemic arterial compliance. Plasma levels of CML correlate with NT-pro-BNP and NYHA functional classes and are predictive of outcome in patients with systolic heart failure. Serum pentosidine levels were a significant predictor of cardiac death and re-hospitalization.   

Discussion/Conclusion: AGE’s are suspected to be involved in diastolic and systolic heart failure but there is an overlap of evidence of underlying pathophysiology in both cases. Patients with increased afterload due to vascular dysfunction seem to be more likely to exhibit symptoms of reduced organ perfusion given a certain left ventricular ejection fraction. Eight different AGE intervention strategies are discussed: 1) Glycemic control, 2) Anti-oxidants, 3) age formation inhibitors, 4) AGE cross-link breakers, 5) Exogenous AGE’s: Smoking cessation and Low AGE diet, 6) AGE scavenging, 7) RAGE inhibition and 8) AGE signal transduction inhibition. Further research of ACE inhibitors and Angiotensin II receptor antagonists may lead to decreased AGE accumulation. 

Hartog, J. W., Voors, A. A., Bakker, S. J., Van Veldhiuisen, D. J., & Smit, A. J. (2007). Advanced glycation end-products (AGEs) and heart failure: Pathophysiology and clinical implications. European Journal of Heart Failure, 9(4), 1146-1155. doi:10.1002/ejhf.2007.9.issue-4

Do Advanced Glycation End Products and Its Receptor Play a Role in Pathophysiology of Hypertension?

Impact Factor: 

Level of Evidence: 1  

Study type: review article   

Sample size: N/A   

Methods: To establish a well-documented relationship between AGE levels and arterial stiffness, Prasad et al. reviewed a number of studies, with methodologies ranging from animal models to human clinical trials.        

Statistical tests: N/A   

Results: The reviewed studies provide evidential support for a positive correlation between plasma AGE levels and arterial stiffness. Additionally, the reviewed evidence also suggests a negative correlation between levels of soluble RAGE (sRAGE)/endogenous secretory RAGE (esRAGE) and hypertension (HTN). Because sRAGE and esRAGE act as decoys for RAGE, their presence reduces AGE-RAGE binding and, as such, decreases the production of ROS (radial oxygen species) associated with AGE-RAGE interactions. In other words, it appears that sRAGE and esRAGE may have protective effects against the development and progression of arterial stiffness commonly seen in patients with HTN.   

Discussion: Given these two correlations, therapeutic strategies that reduce plasma AGE levels and/or increase expression of sRAGE are likely to be beneficial in reducing arterial stiffness and, consequently, blood pressure. More specifically, drugs commonly used to treat cardiovascular diseases like HTN and diabetes mellitus (angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor blockers, statins, and metformin) appear to inhibit AGE formation. Results from animal studies have also revealed that systemic administration of sRAGE is correlated with AGE inhibition, suggesting that exogenous administration of recombinant sRAGE may be beneficial in patients with HTN. However, it should be noted that there is currently little to no data available on the effects of exogenous administration of sRAGE in individuals with HTN.

Prasad K, Mishra M. Do Advanced Glycation End Products and Its Receptor Play a Role in Pathophysiology of Hypertension? Int J Angiol. 2017 Mar;26(1):1-11. doi: 10.1055/s-0037-1598183. Epub 2017 Feb 3. PMID: 28255209; PMCID: PMC5330762.

High serum advanced glycation end-products predict coronary artery disease irrespective of arterial stiffness in diabetic patients

Impact Factor: 

Level of Evidence: IV   

Study type: retrospective/case-control   

Sample size: 145 consecutive patients (63±9 years, 58% men) who received a coronary angiogram for evaluation of CAD   

Methods: 44 diabetic patients and 101 non-diabetics were divided into 3 groups based on the findings of their coronary angiograms. More specifically, each participant was classified into the one of the three following groups: those with zero obstructive diseased vessels, those with 1 diseased vessel, and those with 2 or more diseased vessels. AGE serum levels and brachial-ankle pulse wave velocities (baPWV) were then obtained for all participants.     

Statistical tests: Unpaired t-tests and one-way ANOVAs were used to compare continuous variables between subgroups and a chi-square test was used to compare categorical variables between subgroups. Pearson’s correlation test was used to assess correlations and multiple regression analysis was used to assess the presence of obstructive CAD and the associations with the number of diseased vessels.     

Results: AGE serum levels were significantly higher in diabetic participants with obstructive CAD than in those without obstructive CAD (2.16±0.29 vs. 1.85±0.29 mU/mL, p=0.010). Additionally, AGE serum levels were significantly correlated with the number of diseased vessels in diabetics (r=0.504, p<0.001), but were not significantly correlated with baPWV in diabetics or non-diabetics. In multiple regression analysis, serum AGEs independently predicted obstructive CAD and were associated with the number of diseased vessels in diabetics.   

Discussion: Serum AGE levels independently predict obstructive CAD and the severity of coronary atherosclerosis independent of arterial stiffness only in diabetics. Evaluation of PWV and serum AGEs together may be more effective to identify the risk of CAD in diabetic individuals.

Won KB, Chang HJ, Park SH, Hong SY, Jang Y, Chung N. High serum advanced glycation end-products predict coronary artery disease irrespective of arterial stiffness in diabetic patients. Korean Circ J. 2012 May;42(5):335-40. doi: 10.4070/kcj.2012.42.5.335. Epub 2012 May 24. PMID: 22701499; PMCID: PMC3369965. 

Advanced glycation end products in isoproterenol-induced acute myocardial infarction

Impact Factor:  

Level of Evidence: Level VII 

Study: Rat Study  

Sample Size: 40 white male rats were randomly divided into 5 groups: sham (L1=11), control 0.9% NaCl (L2=11), and 3 groups of varying experimental analysis of myocardial infarction (L3= 6, 6 hours), (L4=6, 24 hours), and (L5=6, 7 days).  

Methods: 100 mg/kg of isoproterenol hydrochloride was injected subcutaneously. The rats were sacrificed at 6 hours, 24 hours, and at 7 days. Sample cardiac tissue was homogenized with a 0.25 M sucrose buffer. Sample was then treated with a 30 microliter Triton X-100.  The tissue was placed in the refrigerator for 30 minutes and then centrifuged at 3000 rpm for 10 minutes. Supernatant was kept at -40 degree C. The samples of blood were put into test tubes and centrifuged at 1500 rpm for 10 minutes. Glucose was measured using the ELITech assay kit (France). AGEs were measured using the Sero Luc method.   

Stats: Kolmogorov Smirnov and Shapiro-Wilk normality test, Levene’s test, Kruskal-Wallis, Mann-Whitney U-test, Spearman correlation test, p value<0.05 being significant.  

Results: All groups showed a significant difference in the serum glucose and the age level. (Glucose p=0.002 and AGE level p=0.018). The trend for serum showed there was a decrease in glucose (4.56) and AGE levels (262.20) in L3 which was 6 hours after. The glucose (7.00) and AGEs (354.30) then increased after 24 hours post-myocardial infarction which was L4. The AGE level (392.50) continued to increase, while the glucose (6.02) decreased slightly. The glucose and AGE in the homogenate (cardiac tissue) showed no significant differences. A positive correlation was found between glucose and AGEs levels in the tissue (p=0.008), however no correlation was found between serum glucose and AGEs level (p=0.283). 

Conclusion: There is a correlation between the serum and tissue variations of AGE in isoproterenol-induced ischemia. The decrease in AGE and glucose in the first 24 hours indicated that there was oxidative stress and membrane lesion exacerbation that led to elimination of both. AGE level does directly depend on the degree of oxidative stress. Therefore it does aid in making a diagnosis and identifying risk stratification for a myocardial infarction. 

Limitation: Rat Study

Timercan T, Şveţ I, Pantea V, Ambros A, Lîsîi L. Advanced glycation end products in isoproterenol-induced acute myocardial infarction. Med Pharm Rep. 2019 Jul;92(3):235-238. doi: 10.15386/mpr-1348. Epub 2019 Jul 31. PMID: 31460503; PMCID: PMC6709963. 

Implications of advanced oxidation protein products (AOPPs), advanced glycation end products (AGEs) and other biomarkers in the development of cardiovascular diseases

Impact Factor: 2.802 

Level of Evidence: III 

Study: Experimental  

Sample Size: 50 cardiovascular patients screened at Punjab Institute of Cardiology, Lahore, Pakistan. 50 healthy individuals that were the controls. Inclusion criteria was ages 20-70 with ischemic heart disease. Individuals with previous addictions and pre-diagnosis medications were not included in the study.  

Methods: 5 mL of blood from periphery was acquired and centrifuged. Different variables such as GSH, CAT, SOD, MDA, GPx, GRx, Vit-E, NO, AOPPs and AGEs by commercial kits, e-NOS through Cayman’s e-NOS ELIZA kit, TNF-a through BioVendor Human TNF-a ELIZA Kit, IL-1 a through BioVendor ELIZA kit, MMP-11 through BioVendor Human MMP-11 ELIZA Kit, and all lipid profile (TCh, TG, LDL, and HDL) through commercial Human Diagnostic Kits. The ethical committee of University of Lahore approved the study, and informed consent was acquired according to Helsinki's declaration.  

Stats: analyzed by SPSS (ver 16), Independent student’s t-test, Pearson correlation, p value<0.05 being significant.   

Results: There was a significant difference in oxidative stress and biochemical markers between the control group that did not have any cardiovascular disease and the experimental group that did. Mean serum AGE was 2.74 ± 0.25 mg/ml for CVD patients and 0.85 ± 0.04 for the control group. P value was 0.000. CVD patients also have higher AOPP (p value= 0.011), e-NOS (p value 0.004), MDA (p value= 0.018), and NO (p value= 0.011) than the control group.  The lipid profile showed that CVD patients had elevated levels of TCh, TG, and LDL, but decreased levels of HDL. Mean IL1-a, TNF-a, and MMP-11 were elevated in the CVD patients. Mean CAT, SOD, GSH, and GRx were decreased in CVD patients. GPx levels were increased in CVD patients, and Vit-E was decreased in CVD patients.  

Conclusion: AOPP has been useful in determining the oxidative damage because AOPP and AGE both induce major cardiovascular complications. AGE works by binding to RAGE receptors and has been proved to be an early sign of atherosclerosis. In addition, e-NOS uncouples and then forms more NO which can result in more peroxynitrite. There was a positive correlation between NO and GSH (r= 0.303), AGEs and NO (r=0.447) and e-NOS anad SOD (r=0.292).  

Limitation: Sample Size 

Rasool M, Malik A, Butt TT, Ashraf MAB, Rasool R, Zahid A, Waquar S, Asif M, Zaheer A, Jabbar A, Zain M, Mehmood A, Qaisrani TB, Malik IR, Khan SU, Mirza Z, Haque A, Al-Qahtani MH, Karim S. Implications of advanced oxidation protein products (AOPPs), advanced glycation end products (AGEs) and other biomarkers in the development of cardiovascular diseases. Saudi J Biol Sci. 2019 Feb;26(2):334-339. doi: 10.1016/j.sjbs.2018.08.024. Epub 2018 Aug 27. PMID: 31485173; PMCID: PMC6717110. 

Cardiac inflammation associated with a Western diet is mediated via activation of RAGE by AGEs.

Impact Factor: 3.469

Level of Evidence: VII

Sample Size/Population: n= 60; 6 different groups with 10 rats each.

Protocol: Diets high in fat represent a major endogenous source of AGEs as a result of interaction between proteins and oxidized lipids in high temperature conditions. The corresponding increase in serum AGEs and their activation of AGE receptors (RAGEs) has been associated with impaired cardiac function through damaged processes such as calcium homeostasis as well as interstitial fibrogenesis. This study compares the AGE related effects of a high-fat diet, specifically a "Western" fast food diet, to that of a standard fat diet, as well as the potentially cardioprotective effects of an AGE-reduced diet in a mouse population. Specifically, the researchers used alagebrium chloride, a known AGE-reducing agent.

Material/Methods: Two different populations of mice were examined in this study, one wildtype group and one RAGE knockout (KO) group. These two groups were further subdivided into a standard diet group, a Western-diet group, and a Western-diet + AL (alagebrium chloride) group. Variables such as cardiac hypertrophy, myocardial fibrosis, and superoxide production were measured. The level of cardiac AGE accumulation was measured through the use of indirect in-house ELISA with a monoclonal AGE antibody specific to nonfluorescent AGE carboxymethyl-lysine (CML). In addition, AGE-R1 and AGE-R3 AGE receptor expressions were assessed with RT-PCR.

Study Type: Rat study. 

Statistical Analysis: Student t-test, for 2 groups, and one-way ANOVA, for 3 or more groups, were used for statistical analysis where P<0.05 is considered significant for each. Associations between variables were also measured using Spearman's rank-order correlation. Mann-Whitney rank sum test was used to determine differences between categorical variables.  

Results: Wild-type mice fed the high fat Western diet demonstrated increased cross-sectional area of cardiac myocytes, while RAGE KO mice did not demonstrate this cardiac hypertrophy. A similar pattern was observed in regards to myocardial fibrosis, whereby the wild-type high fat diet demonstrated increased gene expression of collagen expression, while the RAGE KO mice did not. High fat diet groups demonstrated a significant increase in myocardial inflammation as compared to normal diet, however RAGE KO mice demonstrated significantly decreased levels of cardiac inflammation on the high fat diet as compared to the wild-type. Mice that were also given AL demonstrated less inflammation in both RAGE KO and wild-type groups as compared to the inflammation in their counterparts that were not given AL. Finally, RAGE KO mice did not experience the same increase in mitochondrial superoxide production that was evident in the wildtype group being fed a high fat diet. AL decreased superoxide production in both wild-type and RAGE KO groups.

The increased AGE intake in both RAGE KO and wild-type groups associated with the high fat diet, showed a small, but significant, increase in cardiac AGE accumulation. While RAGE expression was increased in high fat fed wild-type mice as compared to standard diet, there was no expression of RAGE in RAGE KO mice with any of the experimental manipulations.

Conclusion: A Western-fast food diet represents a significant source of increased AGE-related injurious effects to the heart. AGE-reducing agents such as alagebrium chloride, as well as inhibition of RAGE activation through genetic manipulation practices, are able to prevent the deleterious effects of cardiac inflammation, oxidative stress, and mitochondrial dysfunction that are related to chronic AGE activation of RAGE in mice.

Limitations: Results in rat populations may not necessarily directly translate to humans.

Tikellis C, Thomas MC, Harcourt BE, Coughlan MT, Pete J, Bialkowski K, Tan A, Bierhaus A, Cooper ME, Forbes JM. Cardiac inflammation associated with a Western diet is mediated via activation of RAGE by AGEs. Am J Physiol Endocrinol Metab. 2008 Aug;295(2):E323-30. doi: 10.1152/ajpendo.00024.2008. Epub 2008 May 13. PMID: 18477705; PMCID: PMC2652498.

Single oral challenge by advanced glycation end products acutely impairs endothelial function in diabetic and nondiabetic subjects

Impact Factor: 16.019 

Level of Evidence: III 

Type of study:  Quasi Experimental Research Design 

Sample/size population: 44 diabetic subjects and 10 healthy subjects. Of the diabetic patients, 23 had type 1 diabetes and 21 had type 2 diabetes.   

Intro: AGEs have been shown to contribute to the pathogenesis of diabetic cardiovascular disease (CVD). Diabetic patients that consume low AGE diets, with, however, persistent hyperglycemia, exhibit reduced levels of inflammatory markers and mediators including C-reactive protein, Tumor Necrosis Factor-α (TNF-α), and Vascular Cell Adhesion Molecule-1 (VCAM-1). Previous studies have demonstrated endothelial dysfunction related to high AGE diet in combination with other dietary macromolecules such as carbohydrates and fatty acids. 

Material/Methods: Subjects with pre-existing diabetes as well as individuals without diabetes were given a beverage with a high AGE content. The beverage given was a glucose-free Coca Cola light to control for carbohydrates and lipids. Serum AGE, plasminogen activator inhibitor 1 (PAI-1) and vascular cell adhesion molecule-1 (VCAM-1) levels were measured using enzyme-linked immunosorbent assays with monoclonal antibodies. Flowed-mediated dilation (FMD) was recorded by measuring the diameter of the brachial artery. 

Statistical Analysis: Paired and unpaired Student's T test, significant p-value considered p<0.05 

Results: Administration of the oral AGE beverage corresponded with significant increase in serum AGE and PAI-1 levels as well as a significant decrease in FMD in both diabetic and non-diabetic patients. 

Conclusion: Dietary AGEs decrease endothelial function in diabetic and non-diabetic human subjects acutely following a single meal. These effects, as demonstrated by the present study, do not exclusively depend on carbohydrate and lipids content of a given meal, and can be produced by AGEs alone. As endothelial dysfunction is considered to be a contributing factor to atherosclerosis, repeated acute events, such as those elicited by AGEs, can serve as important contributors to the development of such cardiovascular diseases. 

Uribarri J, Stirban A, Sander D, Cai W, Negrean M, Buenting CE, Koschinsky T, Vlassara H. Single oral challenge by advanced glycation end products acutely impairs endothelial function in diabetic and nondiabetic subjects. Diabetes Care. 2007 Oct;30(10):2579-82. doi: 10.2337/dc07-0320. Epub 2007 May 11. PMID: 17496238.

An advanced glycation endproduct cross-link breaker can reverse age-related increases in myocardial stiffness.

Impact Factor: 9.412

Level of Evidence: VII

Sample Size: 18 dogs.

Material/Methods: Dog subjects were assigned into 3 groups - 1: Young animals. 2: Old animals with treatment. 3: Old animals not receiving treatment. Group 2 received 1mg/kg dose of the ALT-711 drug, which breaks cross-links in AGEs. Subjects from the three groups were followed for 4 weeks. Left ventricular end-diastolic volume (EDV), stroke volume, and decreased end-diastolic pressure (EDP) were measured.

Statistical Tests Ran: Two-way ANOVA with a p<0.05.

Results: Dogs in Groups 2 and 3 were significantly more stiff than the dogs in Group 1. Older dogs had significantly increased EDP and significantly decreased EDV (p<0.01 in both cases). Ejection fraction, heart rate, and systemic pressure were similar among all three groups. Continued hemodynamic studies showed an increase in EDV in Group 2 (p<0.001) without EDP change with ALT-711 use. Stroke volume was significantly increased (p<0.05). LV stiffness decreased from ~57 mmHg⋅m2/mL to 33.1 mmHg⋅m2/mL  (p<0.001).

Type of Study: Animal Study - Dog Model

Results/Conclusion: This study showed the effectiveness of ALT-711 in reducing the diastolic stiffness of the left ventricle (LV) by cleaving the AGE cross-link. Over 4 weeks, it was seen that this drug significantly increased EDV. The data presented substantiates the evidence that AGE cross-links have a purpose in aging and cardiovascular state. Administration of ALT-711 demonstrated a reversal in cardiac symptoms, alleviating issues associated with AGEs. There needs to be further testing to determine whether aging in a real world setting would differ.

Asif, M., Egan, J., Vasan, S., Jyothirmayi, G. N., Masurekar, M. R., Lopez, S., Williams, C., Torres, R. L., Wagle, D., Ulrich, P., Cerami, A., Brines, M., & Regan, T. J. (2000). An advanced glycation endproduct cross-link breaker can reverse age-related increases in myocardial stiffness. Proceedings of the National Academy of Sciences of the United States of America, 97(6), 2809–2813. https://doi.org/10.1073/pnas.040558497. 

Advanced glycation end products in nondiabetic patients with coronary artery disease.

Impact Factor: 7.72

Level of Evidence: IV

Sample Size: 48 nondiabetic patients who received coronary angiography from Nara Medical University in Nara, Japan. 20 with normal glucose tolerance, 28 people with diminished glucose tolerance. 40 of the patients were men and 8 were women (age 26-83 years old). The control group consisted of 25 glucose-tolerant individuals without coronary artery disease (CAD).

Material/Methods: Patients received coronary angiography during the study for chest pain or assumed CAD. Serum AGE levels were measured as well as insulin sensitivity. Coronary angiograms were measured by having a stenosis greater than 50% diameter in one coronary artery.

Statistical Analysis: Unpaired t test or Mann-Whitney U test. Difference in percentages was assessed using the χ2 test. Spearman’s rank correlation test was employed for correlations. p<0.05. Serum concentration of AGE, fasting serum glucose, 2-hr serum glucose, fasting serum insulin, and 2-hr serum insulin were used as independent variables. Stenosed vessels was the dependent variable.

Results/Conclusion: Four groups were created depending on the number of vessels stenosed, ranging from 0, 1, 2, or 3 vessels. Plasma TGs correlated with increased number of stenosed vessels. Serum creatinine concentration increased following an increase in number of stenosed vessels. Area under the curve and 2-hr serum glucose were higher in the group with 3-vessel CAD and also correlated with the number of vessels. Serum AGEs were elevated in all individuals with CAD when compared to the control group. Serum AGEs correlated with the number of stenosed vessels (p<0.001). No correlation of serum AGEs with fasting serum glucose, 2-hr glucose, AUCglu, or the concentration of plasma creatinine.

Kanauchi M, Tsujimoto N, Hashimoto T. Advanced glycation end products in nondiabetic patients with coronary artery disease. Diabetes Care. 2001 Sep;24(9):1620-3. doi: 10.2337/diacare.24.9.1620. PMID: 11522709.

High serum levels of advanced glycation end products predict increased coronary heart disease mortality in nondiabetic women but not in nondiabetic men: a population-based 18-year follow-up study.

Impact Factor: 6.607 (2016) 

Level of Evidence: IV 

Sample Size: 1141 (535 Nondiabetic Men, 606 Nondiabetic Women). 

Statistical Analysis: SPSSX, SPCC/PC+ and SPSS 11.0.1 programs. Bivariate correlation assessed by Spearman’s relation coefficient. Chi-squared or 2-tailed t test for independent samples. Univariate and multivariate COX regression models and Kaplan-Meier survival curves.

Results: Women had higher BMI and total HDL levels but had lower total triglycerides and fasting plasma glucose. Serum levels of AGE’s were significantly higher in men than women. Subjects in the highest AGE quartile were more often current smokers (P =.009), had higher total cholesterol (P = .048), total triglycerides (P = .032) and had lower HDL cholesterol (P = .023) than those in other quartiles. AGE levels and gender had a significant interaction in effects on total mortality (P = .023) with CHD mortality (P = .012) even after adjustment for confounding variables (separating men and women). Unadjusted serum AGE’s were significantly related to total (P = .007), CVD (P < .001) and CHD (P<.001) mortality in women but not in men. In women, high AGE levels increased mortality from all causes by 1.6 fold (P = .042) and CHD mortality by 4-fold (P = .014) independently of confounding factors. Kaplan-Meier survival analysis, total (P = .032) and CHD mortality (P<.001) were significantly higher in subjects of the highest AGE quartile.

Study Type: 18 year follow-up study, Random sample with diabetic patients screened out. 

Results/Conclusion:  Finding of a significant association of AGE serum levels with CHD and CVD mortality in women might indicate an etiologic role of AGEs in atherosclerosis in patients without diabetes. Even after adjustment for hs-CRP, AGE’s probably increased mortality, at least in part, independently of inflammation in the vascular wall. Circulating AGE’s predicted mortality only in women, therefore it is possible (but more evidence is needed) that AGE’s represent an additional risk for CVD only in low-risk individuals. Serum levels of AGE’s did not correlate with fasting plasma glucose, maybe reflecting anti-AGE antibody recognizes the more heavily modified glucose compounds as well as oxidatively modified proteins. Increased AGE levels did not predict atherosclerotic events in men, which may be because of a high frequency of smoking and other risk factors. It was demonstrated that AGE serum levels predict total, CVD and CHD mortality in nondiabetic women. Measurement of serum AGE’s might Identify high-risk individuals in a low-risk population.

Kilhovd BK, Juutilainen A, Lehto S, Rönnemaa T, Torjesen PA, Birkeland KI, Berg TJ, Hanssen KF, Laakso M. High serum levels of advanced glycation end products predict increased coronary heart disease mortality in nondiabetic women but not in nondiabetic men: a population-based 18-year follow-up study. Arterioscler Thromb Vasc Biol. 2005 Apr;25(4):815-20. doi: 10.1161/01.ATV.0000158380.44231.fe. Epub 2005 Feb 3. PMID: 15692098.

Increased serum concentrations of advanced glycation end products: a marker of coronary artery disease activity in type 2 diabetic patients.

Sample Size: 30 type II diabetics with coronary artery disease, 12 without. 28 non-diabetics with coronary artery disease, 13 without; 83 total participants. 

Important methods: Serum AGE was measured via ELISA and anti-AGE keyhole limpet haemocyanin. HbA1c was also measured monthly for a median of four years.

Statistical tests ran: Student’s t-test with Dunn correction, p-value: 0.017; Linear regression analysis. 

Study Type: Cross-sectional. 

Results: Serum AGE concentrations were significantly higher in type II diabetics with CAD than all other participant groups. Serum AGE was also significantly correlated with the degree of coronary arteriosclerosis in type II diabetics with CAD. Finally, AGE levels were positively correlated with mean HbA1c.

Discussion/Conclusion: AGE levels may be associated with poor glycemic control and coronary arteriosclerosis in type II diabetics.

Kiuchi K, Nejima J, Takano T, Ohta M, Hashimoto H. Increased serum concentrations of advanced glycation end products: a marker of coronary artery disease activity in type 2 diabetic patients. Heart. 2001 Jan;85(1):87-91. doi: 10.1136/heart.85.1.87. PMID: 11119472; PMCID: PMC1729572. 

Diet low in advanced glycation end products increases insulin sensitivity in healthy overweight individuals: a double-blind, randomized, crossover trial.

Sample Size:  20 participants, 6 women and 14 men

Protocol: Diets identical in calories and macronutrients that were either high or low in AGE content were provided sequentially for a two week period with a 4-week break in between. At the beginning of each trial, dietary, plasma, and urinary AGEs were measured using mass spectrometry. Insulin sensitivity was also measured via a hyperinsulinemic- euglycemic clamp and an intravenous glucose tolerance test. 

Statistical Analysis: paired t-test, 2-factor ANOVA; p-value: 0.05. 

Study Type: Double-blind RTC

Results: Participants had significantly lower urinary AGE output during the low-AGE diet session compared to the high AGE diet session. Insulin sensitivity also significantly increased after the low-AGE diet session and decreased after the high-AGE diet.

Conclusion: A diet low in AGE content may increase insulin sensitivity and reduce the risk of Type II diabetes.  

de Courten B, de Courten MP, Soldatos G, Dougherty SL, Straznicky N, Schlaich M, Sourris KC, Chand V, Scheijen JL, Kingwell BA, Cooper ME, Schalkwijk CG, Walker KZ, Forbes JM. Diet low in advanced glycation end products increases insulin sensitivity in healthy overweight individuals: a double-blind, randomized, crossover trial. Am J Clin Nutr. 2016 Jun;103(6):1426-33. doi: 10.3945/ajcn.115.125427. Epub 2016 Mar 30. PMID: 27030534.

Association between the tissue accumulation of advanced glycation end products and exercise capacity in cardiac rehabilitation patients.

Impact factor: 2.078 

Level of evidence: Level VI 

Type of study and any information related to it: This study was a retrospective cross-sectional study investigating the relationship between advanced glycation end products (AGEs) and exercise capacity (EC) in cardiac rehabilitation patients. All subjects in the study were patients at the university hospital of the researchers. Additional data such as age, sex, smoking history, and comorbidities was collected. Specifically, the researchers were interested in the role diabetes mellitus (DM) played in reduced EC because AGE accumulation is increased in hyperglycemic conditions. 

Sample size: 319 patients with cardiovascular disease (CVD) who were 40 years of age or older and who had undergone early phase II cardiac rehabilitation (CR) had their AGEs measured between November of 2015 and September of 2017. 

Important methods: AGE levels were determined by measuring skin autofluorescence (SAF) using an AGE reading device (DiagnOptics Technologies B.V., Groningen, Netherlands). Hemoglobin A1c levels were measured from blood samples drawn after overnight fasting. Hemoglobin A1c greater than or equal to 6.5% was the threshold used to diagnose patients with DM. Exercise capacity was determined using peak oxygen uptake (VO2). Patients underwent a ramp protocol in which workload was increased 10W/min. Patients with a peak VO2 ≤14 mL/kg/min were considered to have reduced EC. Patients were broken up into high (SAF > 2.8 a.u) and low (SAF < 2.8 a.u) groups. 

Statistical tests ran: Welch’s t test was used for continuous variables and chi-squared test was used for categorical variables. Logistic regression models were used to estimate the association between reduced EC and SAF. A p-value of less than 0.05 was considered statistically significant. 

Results: This study demonstrated a significant association between high AGE levels and reduced EC in patients who underwent CR, independent of other factors such as DM (odds ratio 2.10, 95% confidence interval 1.13–4.05, P = 0.02). The high AGE group also demonstrated a significantly higher body fat percentage and higher prevalence of DM, chronic kidney disease (CKD), and history of coronary artery bypass grafting. The high AGE group was also found to have significantly lower levels of hemoglobin and albumin along with significantly higher levels of hemoglobin A1c. 

Discussion/Conclusion: This study provides evidence that elevated levels of tissue AGEs may be significantly and independently associated with reduced exercise capacity in patients. This is an important finding as EC can be an important indicator of poor prognosis in patients with CVD. Therefore, it may be useful to measure AGE levels in a clinical setting with CVD patients. Limitations in this study include a small sample size of patients with CVD who had undergone CR. The study only measures SAF which does not accurately quantify the accumulation of AGEs in cardiac tissue or in the entire body. Additionally, factors such as skin color or skin creams may decrease the accuracy of skin analysis of AGE levels. Finally, this was a single retrospective cross-sectional study with a small sample size, therefore a causal relationship between AGE levels and reduced EC cannot be established.

Kunimoto M, Shimada K, Yokoyama M, et al. Association between the tissue accumulation of advanced glycation end products and exercise capacity in cardiac rehabilitation patients. BMC Cardiovasc Disord. 2020;20(1):195. Published 2020 Apr 23. doi:10.1186/s12872-020-01484-3

Skin collagen advanced glycation endproducts (AGEs) and the long-term progression of sub-clinical cardiovascular disease in type 1 diabetes.

Impact factor: 2.45 

Type: 2.172 

Level of evidence: IV 

Summary: A study was done on Type One Diabetics to determine the correlation of coronary artery calcium deposition.  A skin biopsy was done to determine the crosslinking nature in these patients and were studied for macrovascular disease. They ran a Wilcox rank sum test and Spearman's correlations to determine the association of the crosslinking properties. The results showed that hyperglycemia put patients at an increased risk for calcium deposition due to independent glycation. They also concluded that AGEs are associated with increased intimal medial thickening despite an A1C adjustment strongly suggesting the crosslinking properties of AGE’s (p value 0.048). 

Monnier VM, Sun W, Gao X, Sell DR, Cleary PA, Lachin JM, Genuth S; DCCT/EDIC Research Group. Skin collagen advanced glycation endproducts (AGEs) and the long-term progression of sub-clinical cardiovascular disease in type 1 diabetes. Cardiovasc Diabetol. 2015 Sep 5;14:118. doi: 10.1186/s12933-015-0266-4. Erratum in: Cardiovasc Diabetol. 2015;14:138. PMID: 26341632; PMCID: PMC4560872. 

Molecular Mechanisms of AGE/RAGE-mediated fibrosis in the diabetic heart

Impact Factor: 2.12  

Level of Evidence: IV   

Study Type: Cross Sectional In Vivo Study   

Methods: This study focused on the hyperglycemia that is associated with Diabetes. The chronic hyperglycemia can then cause fibrosis within blood vessels which can lead to devastating consequences such as myocardial infarction and ventricular stiffness. The formation of advanced glycation products occurs when the glucose reacts with the proteins in the vessels further contributing to the complications. However, Rap1a can be used as a solution for these complications and how inhibition of this protein has resulted in more fibrotic changes to happen.   

Results: The inhibition of the Rap1a protein has been associated with higher levels of fibrosis and therefore a higher chance of cardiac events occurring. So now in addition to targeting the AGE part of this synthesis pathway, another portion of this process, the Rap1A protein can be used as a target in the further development of drugs for preventing the progression of myocardial events. 

Zhao J, Randive R, Stewart JA. Molecular mechanisms of AGE/RAGE-mediated fibrosis in the diabetic heart. World J Diabetes. 2014;5(6):860-867. doi:10.4239/wjd.v5.i6.860  

Advanced glycation endproducts are increased in rheumatoid arthritis patients with controlled disease.

Impact factor: 4.686 

Level of evidence: Level IV 

Type of study: cross sectional 

Sample size: 49 patients with rheumatoid arthritis who receive standard care were compared with 49 healthy controls of similar age and sex. 

Methods: AGEs determined via skin autofluorescence, disease determined via Disease Activity Score of 28 joints (DAS-28) score, and joint damage via modified Sharp-v.d. Heijde score. Endothelial activation (soluble vascular cellular adhesion molecule-1) sVCAM-1, von Willebrand factor (vWF), thrombomodulin), endothelial dysfunction (determined by small artery elasticity (SAE)) and IMT were measured in both groups. 

Statistical analysis: Two-sample t-tests, Mann-Whitney-U tests, chi-square method, Fisher's exact test. Gaussian distribution of the data was analyzed with the D'Agostino-Pearson omnibus normality test. Correlation analysis was performed by Pearson correlation when variables were distributed normally; otherwise the Spearman correlation was used. Predictor analysis for AGE accumulation was performed using multivariate linear regression with forward inclusion of variables with P < 0.10 in univariate analysis. Two-sided P-values < 0.05 were considered significant. 

Results: AGEs, sVCAM-1, and vWF levels were higher in RA patients compared to the healthy control group.  SAE was significantly decreased in the RA group compared to the control group. In multivariate analysis for both groups, smoking, glucose levels, vWF, SAE, and male gender were significantly related to the formation of AGEs. 

Conclusion: AGEs were increased in RA patients with long-standing disease and without signs of premature atherosclerosis. AGEs were related to endothelial activation and endothelial dysfunction. This supports the hypothesis that in RA, AGEs may be an early indicator of cardiovascular disease.

de Groot, L., Hinkema, H., Westra, J. et al. Advanced glycation endproducts are increased in rheumatoid arthritis patients with controlled disease . Arthritis Res Ther 13, R205 (2011). https://doi.org/10.1186/ar3538 

Advanced glycation end products in children with type 1 diabetes and early reduced diastolic heart function 

Impact factor: 2.078 

Level of evidence: IV 

Type of study: cross sectional 

Sample size: 146 T1D patients (age 8–18 years) without known diabetic complications were stratified into 2 groups based on diastolic function. 

Methods: Patients were examined with tissue Doppler imaging. A clinical examination and ultrasound of the common carotid arteries were performed. Methylglyoxal-derived hydroimidazolone-1 (MG-H1) was measured by immunoassay. 

Statistical analysis: When data was normally distributed, differences between the two groups were tested with Student’s t-test (if not normal, then with Mann-Whitney U-test). Univariate logistic regression analysis was used to see if there were independent baseline risk factors for E’ (increased stiffness of left ventricle leading to reduced peak early)/ A’ (increased peak late) ratio. Significance level of 20% was required for a variable to be included in the multivariate regression model. A manual backward stepwise elimination procedure was done using effect sizes quantified by odds ratio (OR) with its 95% confidence interval. Calibration and discrimination were used to determine the predictive accuracy of the models. The Hosmer and Lemeshow goodness-of-fit test assessed calibration, with a statistically non-significant Hosmer and Lemeshow result (p > 0.05) suggesting that on average, the model predicts accurately. Discrimination was evaluated by analysis of the area under the ROC curve. Acceptable discriminatory capability was considered as an area under the ROC curve > 0.7. 

Results: Compared to the rest of the T1D people, the participants in the low diastolic function group had higher body mass index (BMI), higher systolic blood pressure, and higher diastolic blood pressure. The distensibility coefficient was lower, Young’s modulus higher, and MG-H1 higher. There was no difference in carotid intima-media thickness between the groups, no associations between reduced diastolic function and years from diagnosis, HBA1c, mean HBA1c, CRP or calculated glycemic burden. BMI was an independent risk factor for E’/A’-ratio. BMI was a non-significant, but relatively large effect size for MG-H1 (indicating possible role for AGEs). 

Conclusion: Children in the reduced diastolic function group with T1D had higher BMI, but not higher HbA1c. They had elevated serum levels of the advanced glycation end product MG-H1, higher blood pressure, and increased stiffness of the common carotid artery, but not of statistical significance when tested in a logistic regression model. 

Brunvand, L., Heier, M., Brunborg, C. et al. Advanced glycation end products in children with type 1 diabetes and early reduced diastolic heart function. BMC Cardiovasc Disord 17, 133 (2017). https://doi.org/10.1186/s12872-017-0551-0 

Accumulation of advanced glycation end products (AGEs) is associated with the severity of aortic stenosis in patients with concomitant type 2 diabetes 

Impact factor: 5.448 

Level of evidence: IV 

Type of study: prospective study, in vivo 

Sample size: 76 patients with severe aortic stenosis (AS) and 50 age-matched type 2 diabetes mellitus (DM) patients with a median blood glucose level of 7.5 mM and glycated hemoglobin (HbA1c) of 6.8, scheduled for aortic valve replacement.  

Methods: Valvular expression of AGEs, RAGE, IL-6, and ROS induction were measured ex vivo by immunostaining, and calculated as positive immunoreactive areas/total sample area. Plasma levels of AGEs and sRAGE were assessed by ELISAs. HbA1c was determined using turbidimetric inhibition immunoassay TINIA in hemolysate prepared from whole blood, and serum fructosamine levels were measured using colorimetric assay. 

Statistical analysis: Pearson’s X^2 and two-tailed Fisher’s exact. Normality analyzed using Shapiro-Wilk test. Student’s test for normally distributed continuous variables. Differences between groups were compared via Mann-Whitney U test for non-normal continuous variables. Associations between nonparametric variables were assessed by Spearman’s tests. Multivariate analyses were performed using linear regression models adjusted for age, hypertension, hypercholesterolemia, and the use of statin and/or angiotensin-converting enzyme inhibitors. Significance was defined as P-value < 0.05. 

Results: The DM patients had increased AGE and RAGE valvular expression compared to non-DM patients. Plasma levels of AGEs and sRAGE were higher in DM patients compared to the non-DM patients. Percentage of valvular ROS-positive and not IL-6 positive areas was higher in DM patient valves than in non-RM patient valves. In DM patients, the percentage of valvular AGEs and RAGE-positive areas, as well as plasma AGEs and sRAGE levels, were correlated with HbA1c. There was an association between the amount of valvular AGE and disease severity measured as aortic valve area (AVA). DM patients who had Hba1c > 7% had AGE valvular expression that correlated with mean transvalvular pressure gradient, and all DM patients’ plasma AGE levels correlated with AVA.  

Conclusion: AGEs and RAGE accumulate within stenotic aortic valves in DM patients, the extent of which is associated with aortic stenosis severity. Plasma AGE and sRAGE levels were associated with AVA which could be considered biomarkers of AS in patients with concomitant type 2 DM.

Kopytek M, Ząbczyk M, Mazur P, Undas A, Natorska J. Accumulation of advanced glycation end products (AGEs) is associated with the severity of aortic stenosis in patients with concomitant type 2 diabetes. Cardiovasc Diabetol. 2020 Jun 17;19(1):92. doi: 10.1186/s12933-020-01068-7. PMID: 32552684; PMCID: PMC7301463. 

Correlation between advanced glycation end-products and the expression of fatty inflammatory factors in type II diabetic cardiomyopathy 

Impact factor: 2.05 

Level of evidence: IV 

Type of study: prospective study, in vivo 

Sample size: 118 total (78 type 2 DM patients, 38 of which had diabetic cardiomyopathy (DCM); 40 healthy subjects for control) 

Methods: An automatic biochemical analyser was used to measure the 10-hour fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and glycated haemoglobin (HbA1c) levels. ELISAs were used to determine the amount of leptin, APN and AGEs, and a radioimmunoassay was performed to determine the fasting insulin (FINS) level. Insulin-resistance (IR) index was calculated using the Haffner formula. 

Statistical analysis: t-tests for comparisons between 2 groups, variance analysis for comparisons of 3 groups, q tests for comparisons between any two means, and Pearson’s test for correlational analyses between indicators. Significance was described as P<0.05. 

Results: FBG, FINS, IR and HbA1c were significantly increased in the T2DM and DCM groups compared to the normal control group, while there was no significant difference between the T2DM and DCM groups. APN was significantly lower in the T2DM group compared to the normal control group, and APN was significantly lower in the DCM group compared to the D2M group. Positive correlations between AGE levels and both IR and leptin, but a negative correlation between AGE and APN. A decrease in APN and an increase in leptin were independently correlated with AGE levels. 

Conclusion: An imbalance between protective and harmful inflammatory factors is involved in the development of DCM. This study showed that APN and leptin levels were independently related to AGE levels. The results of this study could potentially play a role in the examination, treatment, evaluation, and prognostic assessment of DCM. Studying other pro-inflammatory factors and other indicators of myocardial damage, as well as studying more correlations between APN, glucose, fatty acids, leptin, glycaemia, IR, and cardiac dysfunction, need to be further explored in DCM studies. 

Guo Z, Huang D, Tang X, Han J, Li J. Correlation between advanced glycation end-products and the expression of fatty inflammatory factors in type II diabetic cardiomyopathy. Bosn J Basic Med Sci. 2015 Oct 25;15(4):15-9. doi: 10.17305/bjbms.2015.619. PMID: 26614846; PMCID: PMC4690436. 

Advanced glycation end product-mediated matrix metallo-proteinase-9 and apoptosis via renin-angiotensin system in type 2 diabetes 

Impact factor: 3.876 

Level of evidence: IV 

Type of study: in vivo, cross sectional 

Sample size: 11 autopsy specimens from the aorta and coronary arteries of patients with diabetes; 11 autopsy specimens from the aorta and coronary arteries of patients without diabetes.  

Methods: Immunohistochemistry of AGE, MMP-9, angiotensin-converting enzyme (ACE), and the receptor for AGE (RAGE). Apoptosis was determined by TUNEL staining. 

Results: The diabetic group had greater proportions of AGE accumulation, MMP-9 expression, and apoptosis in intimal areas of both aortic and coronary specimens compared to the nondiabetic group. There was a correlation between AGE accumulation and MMP-9 expression and apoptosis. RAGE was significantly increased in the diabetic group compared to the nondiabetic group. ACE expression in diabetic specimens was increased and correlated with AGE accumulation, RAGE expression, MMP-9 expression, and apoptosis in both groups. HbA1c was linearly correlated with AGE accumulation, MMP-9, apoptosis, and ACE expression as well. 

Conclusion: AGE/RAGE-related MMP-9 expression and apoptosis were correlated with ACE expression in diabetic plaques. RAS may be involved in AGE-dependent diabetic vascular complications. 

Ishibashi T, Kawaguchi M, Sugimoto K, Uekita H, Sakamoto N, Yokoyama K, Maruyama Y, Takeishi Y. Advanced glycation end product-mediated matrix metallo-proteinase-9 and apoptosis via renin-angiotensin system in type 2 diabetes. J Atheroscler Thromb. 2010 Jun 30;17(6):578-89. doi: 10.5551/jat.3590. Epub 2010 Mar 9. PMID: 20215707. 

Soluble Receptor of Advanced Glycated Endproducts Is Associated With Plaque Vulnerability in Patients With Acute Myocardial Infarction

Impact Factor: 2.540 

Level of Evidence: III 

Type of Study: Quasi-Experimental with Control 

Sample Size: 108 

Statistical tests ran: Multivariate logistic regression analysis (P < .1) and One-way ANOVA (P<.05)  

Results: Significant difference in CRP (P<.001), MMP-9 ( P<.001) and sRAGE (P<.001) levels between groups. Current smokers ID’d in multivariate analysis that might be associated with AMI (P<.1). Based on multiple logistic regression analysis, plasma levels of MMP-9 and sRAGE above the median were significantly associated with AMI, as well as being a current smoker and having a CRP >3.0mg/L.   

Discussion/Conclusion: MMP-9 and sRAGE levels above the median were significant predictors of AMI, as well as being a current smoker and having a CRP > 3.0mg/L. Findings suggest plasma level of sRAGE is positively associated with AMI and that RAGE-dependent inflammatory responses might contribute to plaque vulnerability, along with MMP-9. Plasma level of sRAGE was significantly higher in AMI group than controls. This elevation may be independently associated with plaque vulnerability in patients with AMI.

Park, H.-J., Baek, J.-Y., & Shin, W. S. (2011). Soluble Receptor of Advanced Glycated Endproducts Is Associated With Plaque Vulnerability in Patients With Acute Myocardial Infarction. Japanese Circulation Society, 75. 

Endothelial Dysfunction and Advanced Glycation End Products in Patients with Newly Diagnosed Versus Established Diabetes: From the CORDIOPREV Study 

Impact factor: 4.546 

Level of evidence: IV 

Type of study: cross sectional 

Sample size: 540 patients with T2DM and coronary heart disease from the CORDIOPREV study (350 patients had established T2DM, 190 patients had newly diagnosed T2DM) 

Methods: Anthropometric and blood laboratory tests were performed on each subject using spectrophotometry and immunoassays. Endothelial function was evaluated via ultrasonography of the brachial artery. AGEs were measured using competitive ELISA kits. 

Statistical analysis:  Kolmogorov–Smirnov normality test was performed for the evaluation of the distribution of the quantitative variables. Continuous variables were compared using t-test when comparing between two groups, or one-way analysis of variance (ANOVA) and post-hoc multiple comparisons analysis using the LSD test (homogeneous variances) or Tamhane’s statistic (non-homogeneous variances) when comparing more than two groups. Pearson chi-squared test was employed to compare categorical characteristics. One-way ANCOVA was conducted to compare MG and CML serum levels to control for age, sex, and BMI as confounders. 

Results: AGEs levels and IMT-CC were higher in patients with established vs. newly diagnosed T2DM. FMD did not differ between the two groups. Patients with established T2DM and severe endothelial dysfunction had higher serum MG levels, IMT-CC, HOMA-IR and fasting insulin levels than those with newly diagnosed T2DM and non-severe endothelial dysfunction. CML levels were greater in patients with established vs. newly diagnosed T2DM, independent of endothelial dysfunction severity.  

Conclusion: AGEs levels and IMT-CC were significantly higher in patients with established vs. newly diagnosed T2DM, demonstrating the increased risk of atherosclerotic cardiovascular disease in T2DM. 

de la Cruz-Ares S, Cardelo MP, Gutiérrez-Mariscal FM, Torres-Peña JD, García-Rios A, Katsiki N, Malagón MM, López-Miranda J, Pérez-Martínez P, Yubero-Serrano EM. Endothelial Dysfunction and Advanced Glycation End Products in Patients with Newly Diagnosed Versus Established Diabetes: From the CORDIOPREV Study. Nutrients. 2020 Jan 16;12(1):238. doi: 10.3390/nu12010238. PMID: 31963378; PMCID: PMC7019746. 

Higher plasma levels of advanced glycation end products are associated with incident cardiovascular disease and all-cause mortality in type 1 diabetes: a 12-year follow-up study 

Impact Factor: 16.02  

Level of Evidence: IV 

Type of Study: Prospective/cohort study  

Sample size: 169 individuals with diabetic neuropathy and 170 individuals with persistent normoalbuminuria who were free of CVD at study entry. 

Important Methods: The researchers prospectively followed the 169 individuals with diabetic neuropathy and 170 individuals with persistent normoalbuminuria who were free of CVD at study entry and in whom levels of N(ε)-(carboxymethyl)lysine, N(ε)-(carboxyethyl)lysine, pentosidine and other biomarkers were measured at baseline. The median follow-up duration was 12.3 (interquartile range 7.6-12.5) years. The researchers compared the plasma levels of AGEs with the incidence of cardiovascular disease and type 1 diabetes and the extent to which any such associations could be explained by endothelial and renal dysfunction, low-grade inflammation, and arterial stiffness.  

Results: During the course of follow-up, 82 individuals (24.2%) died; 85 (25.1%) suffered a fatal (n = 48) and/or nonfatal (n = 53) CVD event. The incidence of fatal and nonfatal CVD and of all-cause mortality increased with higher baseline levels of AGEs independently of traditional CVD risk factors: hazard ratio (HR) = 1.30 (95% CI = 1.03-1.66) and HR = 1.27 (1.00-1.62), respectively. These associations were not attenuated after further adjustments for markers of renal or endothelial dysfunction, low-grade inflammation, or arterial stiffness. 

Discussion/conclusion: Higher levels of AGEs are associated with incident fatal and nonfatal CVD as well as all-cause mortality in individuals with type 1 diabetes, independently of other risk factors and of several potential AGEs-related pathophysiological mechanisms. Thus, AGEs may explain, in part, the increased cardiovascular disease and mortality attributable to type 1 diabetes and constitute a specific target for treatment in these patients.

Nin JW, Jorsal A, Ferreira I, et al. Higher plasma soluble Receptor for Advanced Glycation End Products (sRAGE) levels are associated with incident cardiovascular disease and all-cause mortality in type 1 diabetes: a 12-year follow-up study. Diabetes. 2010;59(8):2027-2032. doi:10.2337/db09-1509

C16, a novel advanced glycation endproduct breaker, restores cardiovascular dysfunction in experimental diabetic rats 

Impact Factor: 5.064 (2019) 

Level of Evidence: VII (rat study)   

Type of Study:  Rat Hemodynamic Study 1 (Diabetes induced at 9–10-week-old male Wistar rats. Diabetes ran course for 12 weeks, then used in study. Divided into 4 groups: Vehicle, ALT-711, C16 25mg/kg/day or C15 50mg/kg/day). Assess exact Hemodynamic changes in LV that were caused by diabetic state. 

Rat Hemodynamic Study 2: 6 groups of diabetic rats; vehicle, 12.5mg/kg (ALT-711), or 12.5, 25 or 50 mg/kg/day of C16 for 4 weeks or 50 mg/kg/day of C16 for 2 weeks. Assess possible reversal of diabetes-induced Cardiovascular abnormalities.  

Sample Size: Hemodynamic Study 1: n=32. Hemodynamic Study 2: n = 48.  

Statistical tests ran: One-way ANOVA on SPSS. P<0.05 = statistically significant  

Results: 

Hemodynamic Study of LV (Study 1): LVSP were decreased significantly in the vehicle-treated diabetic group. C16 treatment in both 25mg and 50mg group resulted in significant increase in all 3 parameters compared to vehicle-treated diabetic rats. No difference between C16 and ALT-711 treated groups. 

Hemodynamic study of the CV System (Study 2): Cardiac Output and SAC were significantly lower in vehicle-treated diabetic rats. Treatment with C16 for 4 weeks led to dose-dependent significant increase in CO and CO index, reduction in TPR and TPR index and an increase in SAC when compared to vehicle-treated rats. Similar results were found in the ALT-711 treated rats. 

RBC-IgG assay (ELISA) had significant reduction of RBC-IgG content compared to vehicle treated diabetic rats. 

Collagen solubility assay: Tail tendon solubility of C16 rats increased significantly. ALT-711 treated rats had significant increases in collagen solubility. 

Collagen Type III/I ratio of aortic media wall tended to be greater in rats with diabetes, but C16 and ALT-711 treatment could reverse this alteration. 

Immunohistochemistry for AGE: Decreased AGE accumulation in C16 and ALT-711 treated rats. 

Discussion/Conclusion:  Demonstratable AGE-related changes in structure eventually increase the stiffness of arterial tree and myocardium, which result in functional changes. C16, a potential AGE breaker could prevent AGE accumulation in aortic media of diabetic rats and reverse Collagen Type III/I ratio. Diastolic and contractile function of the LV were restored significantly by C16. Treatment duration related to stronger effects (4-week outcomes were better than 2 week outcomes for C16). C16 exerted beneficial CV actions and restored diabetes-associated CV dysfunction. C16 has the ability to break established AGE crosslinks and reduce AGE accumulations in tissues in vivo.  

There seems to be a limitation of Hemodynamic Study 1 as there was no direct control, only a vehicle group whereas the second study did have a control group. 

Cheng, Gang, Li-li Wang, Wen-sheng Qu, Long Long, Hao Cui, Hong-ying Liu, Ying-lin Cao, & Song Li. "C16, a novel advanced glycation endproduct breaker, restores cardiovascular dysfunction in experimental diabetic rats." Acta Pharmacologica Sinica [Online], 26.12 (2005): 1460-1466. Web. 17 Apr. 2021

Clinical and prognostic value of advanced glycation end-products in chronic heart failure

Impact Factor: 5.640  

Level of Evidence:  III  

Type of Study: Longitudinal observation of Chronic Heart Failure patients  

Sample Size: 102 (101 “Caucasian” participants, 1 “Black” participants)  

Statistical tests ran: P value (two-sided) <= .05. P-values determined by linear regression for continuous variables. Chi-square for nominal variables. Jonckeheere-Terpstra tests for ordinal variables. Cox regression analysis for prognostic value of CML and CEL. Hazard ratios for quartiles. Log-Minus-log survival curves and time-dependent covariates for Cox proportional hazard assumptions.  

Results: CML levels were significantly associated with higher NYHA functional class, higher log NT-pro-BNP, older age, less smoking, lower GFR, increased BMI and higher ECV (all statistically significant). Multivariable linear regression analysis showed that GFR was the most important determinant of CML. Higher CEL levels were significantly associated with older age, less smoking, lower DBP, lower GFR and the use of B-blockade. The most important determinants of CEL levels were GFR, smoking and use of B-blockade (all statistically significant).  

Univariate Cox regression analysis revealed that CML was a significant prediction of the combined endpoint. Predictive value of CML subsided after adjustment for GFR.   

Discussion/Conclusion:  CML is associated with the severity and prognosis of patients with CHF but after adjustment of multiple variables the effects subside when considered with GFR values. It is considered that AGE’s may be increased in CHF via the progression of renal failure, DM, smoking age and increased oxidative stress. The researchers believe their results may indicate CML levels explain (partly) prognostic value of renal function in patients with CHF. However, due to the observational nature of the study, researchers could not rule out the possibility that CML acts as a marker for impaired renal function and predictive value in CHF. 

Jasper W.L. Hartog, Adriaan A. Voors, Casper G. Schalkwijk, Jean Scheijen, Tom D.J. Smilde, Kevin Damman, Stephan J.L. Bakker, Andries J. Smit, Dirk J. van Veldhuisen, Clinical and prognostic value of advanced glycation end-products in chronic heart failure, European Heart Journal, Volume 28, Issue 23, December 2007, Pages 2879–2885

Role of DJ-1 in Modulating Glycative Stress in Heart Failure

Impact Factor: 4.660  

Level of Evidence: Level VII   

Type of Study: Mice study - experimental  

Sample Size: n = 275  

Statistical tests ran:  

Assessment for normal distribution: 1) D’Agostina and Pearson Omnibus normality test, 2) One-way ANOVA with a Tukey test or Dunnett test as the post hoc analysis, 3) Two-way ANOVA with a Tukey test as the post hoc analysis for comparison of means.  

Echocardiography data: 2-way repeated measures ANOVA with a Bonferroni test for post hoc. Follow-up comparisons: 1) baseline versus post-baseline measurements, 2) differences between each groups baseline measurements, 3) differences between each groups post-baseline measurements   

Results: Echocardiography revealed that DJ-1 knockout mice exhibited LV cavity dilatation and exacerbated cardiac dysfunction following I/R when compared with WT mice. DJ-1 knockout also exhibited significantly greater cardiac enlargement, myocyte hypertrophy and fibrosis. AAV9-DJ1(delta)c significantly improved LV function, reduced hypertrophy and reduced fibrosis when compared with AAV9-GTP in the setting of I/R -induced heart failure. Hearts from DJ-1 knockout hearts displayed increased levels of Caspase-3/7 activity as well as increased number of apoptotic cells. Markers of inflammation and levels of oxidative stress were also enhanced in DJ-1 knockout hearts. Aminoguanidine reduced iNOS leves, glycative stress, cell death, inflammation and oxidative stress in both WT and DJ-1 mice. Loss of DJ-1 was sufficient to induce glycative stress and cell death under control conditions. Treatment with aminoguanidine reduced glycative stress and cell death in in siRNA-DJ1 transfected cells under both control and glucose deprivation conditions. Using LV samples obtained from end-stage heart failure patients at time of transplant, found significantly lower level sof full-length form and cleaved form of DJ-1 compared with non-failing control samples.   

Discussion/Conclusion:   In the heart, DJ-1 deficiency is associated with enhanced myocardial infarction following ischemia-reperfusion injury as well as enhanced LV dysfunction following pressure overload-induced HF and permanent myocardial ischemia. First week of reperfusion was a critical time period where signaling events are important determinants of LT functional outcome in this model of I/R-induced heart failure. Dj-1 is active during early periods following reperfusion and suppressed during the late stages of heart failure. DJ-1 can experience irreversible methionine oxidation, which induces protein unfolding and degradation. Delayed treatment of the virus was able to reduce progression of heart failure. Therapeutic overexpression of cleaved DJ-1 may serve as a viable treatment option for heart failure. Loss of DJ-1 is sufficient to induce glycative stress and by our in vivo data demonstrating that the cleaved form of DJ-1 is sufficient to oppose glycative stress following I/R injury. Deglycase would be possibly considered a repair protein due to the removal of glycation moiety from proteins. 

Shimizu Y, Nicholson CK, Polavarapu R, Pantner Y, Husain A, Naqvi N, Chin LS, Li L, Calvert JW. Role of DJ-1 in Modulating Glycative Stress in Heart Failure. J Am Heart Assoc. 2020 Feb 18;9(4):e014691. doi: 10.1161/JAHA.119.014691. Epub 2020 Feb 13. PMID: 32067589; PMCID: PMC7070196.