Nϵ-Carboxymethyl-Lysine Deteriorates Vascular Calcification in Diabetic Atherosclerosis Induced by Vascular Smooth Muscle Cell-Derived Foam Cells

Nε-carboxymethyl-lysine and inflammatory cytokines, markers and mediators of coronary artery disease progression in diabetes

This editorial refers to the article "Comparative analysis of Nε-carboxymethyl-lysine and inflammatory markers in diabetic and non-diabetic coronary artery disease patients", published in the recent issue of the World Journal of Diabetes 2023 is based on glucose metabolism, advanced glycation end products (AGEs), inflammation and adiposity on diabetes and coronary artery disease (CAD). This study has included CAD patients who were stratified according to glycosylated hemoglobin higher than 6.5 and sex-matched. A higher prevalence of hypertension, dyslipidemia, and non-vegetarian diet were found in the diabetic group. These risk factors might influence body weight and adiposity and explain the increment of the left atrium. Although this data was not supported by the study. The diet can also explain the non-enzymatic reactions on lipids, proteins, or nucleic acids and consequently an increment of AGEs. These molecules can emit fluorescence. However, one of the non-fluorescent and most abundant AGEs is Nε-carboxymethyl-lysine (CML). Its association with coronary artery stenosis and severity in the diabetic group might suggest its role as a player in CAD progression. Thus, CML, after binding with its receptor (RAGE), can induce calcification cascade through reactive oxygen species and mitogen-activated protein kinase. Moreover, this interaction AGE-RAGE can cause activation of the transcription nuclear factor-kb and induce inflammatory cytokines. It might explain the relationship between CML and pro-inflammatory cytokines in diabetic and CAD patients. Although this is a population from one center, the determination of CML and inflammatory cytokines might improve the diagnosis of severe and progressive CAD. Future and comparative studies among glycosylated hemoglobin, CML, and other AGE levels according to diagnosis and prognosis value might modify the clinical practice. Although these molecules are irreversible, they can act through a specific receptor inducing a signal transduction that might be modu-lated by inhibitors, antibodies, or siRNA. Further mechanistic studies might improve the development of future preventive therapies for diabetic patients.

Correlation analysis of lipid accumulation index, triglyceride-glucose index and H-type hypertension and coronary artery disease

Objective

The current research was designed to explore the relationship between the lipid accumulation index (LAP), coronary artery disease (CAD), and the triglyceride-glucose (TyG) index in patient with H-type hypertension.

Methods

From June 2021 to January 2022, our hospital's information management system collected data on 186 patients with essential hypertension. The participants were categorized into two groups (H-type hypertension (n = 113) and non-H-type hypertension (n = 73)) based on their homocysteine levels. Both groups' general condition, lipid accumulation index, triglyceride-glucose index, and Gensini score were compared to determine the factors influencing the severity of CAD in H-type hypertension patients.

Results

There were statistically significant differences (P < 0.05) in homocysteine (Hcy, GLP-1 and SAA) level, LAP, and TyG indexes, but not in body mass index (BMI), smoking, sex, age, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), fasting plasma glucose (FPG), diastolic blood pressure, and systolic blood pressure. Additionally, there were substantial variations between the two groups regarding the number of lesion branches, degree of stenosis, and Gensini score (P > 0.05). patient with grade III to IV lesions had substantially higher LAP and TyG indices than those with stage I to II (P < 0.05). TyG (OR = 2.687) and TyG-LAP (OR = 4.512) were the factors determining the incidence of coronary artery disease in H-type hypertension, according to multivariate logistic regression analysis. The lesion number, stenosis degree, and Gensini score (P < 0.05) varied among both groups. LAP and TyG indexes were substantially greater in patients with double and triple vessel lesions than in those without lesions or with single vessel lesions (P < 0.05); similarly, these two indexes were considerably higher in individuals with grade III to IV lesions than in patients with grade I to II lesions (P < 0.05). As per the Pearson correlation analysis, the LAP, TyG indices and SAAlevel were adversely connected to the Gensini score (r = 0.254, 0.262, 0.299, P < 0.05), the GLP-1 level was negatively correlated to the Gensini score (r = -0.291, P < 0.05). TyG (OR = 2.687) and TyG-LAP (OR = 4.512) were the factors determining the frequency of coronary artery disease in H-type hypertension, according to multivariate logistic regression analysis.

Conclusion

In conclusion, the LAP and TyG indexes were observed to be closely related to the degree of CAD in H-type individuals with hypertension, which can better understand the pathogenesis of coronary artery disease in patients with H-type hypertension and is of great significance for guiding clinical doctors to carry out personalized treatment and management.

SIRT3-and FAK-mediated acetylation-phosphorylation crosstalk of NFATc1 regulates Nε-carboxymethyl-lysine-induced vascular calcification in diabetes mellitus

BACKGROUND AND AIMS

Arterial calcification is the predictor of cardiovascular risk in diabetic patients. N^ε-carboxymethyl-lysine (CML), a toxic metabolite, is associated with accelerated vascular calcification in diabetes mellitus (DM). However, the mechanism remains elusive. This study aims to explore the key regulators involved in CML-induced vascular calcification in DM.

METHODS

We used Western blot and immuno-staining to test the expression and localization of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) in human samples, a diabetic apolipoprotein E-deficient (ApoE^-/-) mouse model, and a vascular smooth muscle cells (VSMC) model. Further, we confirmed the regulator of NFATc1 phosphorylation and acetylation induced by CML. The role of NFATc1 in VSMCs calcification and osteogenic differentiation was explored in vivo and in vitro.

RESULTS

In diabetic patients, CML and NFATc1 levels increased in the severe calcified anterior tibial arteries. CML significantly promoted NFATc1 expression and nuclear translocation in VSMCs and mouse aorta. Knockdown of NFATc1 significantly inhibited CML-induced calcification. CML promoted NFATc1 acetylation at K549 by downregulating sirtuin 3 (SIRT3), which antagonized the focal adhesion kinase (FAK) induced NFATc1 phosphorylation at the Y270 site. FAK and SIRT3 affected the nuclear translocation of NFATc1 by regulating the acetylation-phosphorylation crosstalk. NFATc1 dephosphorylation mutant Y270F and deacetylation mutant K549R had opposite effects on VSMC calcification. SIRT3 overexpression and FAK inhibitor could reverse CML-promoted VSMC calcification.

CONCLUSIONS

CML enhances vascular calcification in DM through NFATc1. In this process, CML increases NFATc1 acetylation by downregulating SIRT3 to antagonize FAK-induced NFATc1 phosphorylation.

Nε-(carboxymethyl)lysine promotes lipid uptake of macrophage via cluster of differentiation 36 and receptor for advanced glycation end products

BACKGROUND

Advanced glycation end products (AGEs) are diabetic metabolic toxic products that cannot be ignored. N^ε-(carboxymethyl)lysine (CML), a component of AGEs, could increase macrophage lipid uptake, promote foam cell formation, and thereby accelerate atherosclerosis. The receptor for AGEs (RAGE) and cluster of differentiation 36 (CD36) were the receptors of CML. However, it is still unknown whether RAGE and CD36 play key roles in CML-promoted lipid uptake.

AIM

Our study aimed to explore the role of RAGE and CD36 in CML-induced mac-rophage lipid uptake.

METHODS

In this study, we examined the effect of CML on lipid uptake by Raw264.7 macrophages. After adding 10 mmol/L CML, the lipid accumulation in macro-phages was confirmed by oil red O staining. Expression changes of CD36 and RAGE were detected with immunoblotting and quantitative real-time polymerase chain reaction. The interaction between CML with CD36 and RAGE was verified by immunoprecipitation. We synthesized a novel N-succinimidyl-4-¹⁸F-fluorobenzoate-CML radioactive probe. Radioactive receptor-ligand binding assays were performed to test the binding affinity between CML with CD36 and RAGE. The effects of blocking CD36 or RAGE on CML-promoting lipid uptake were also detected.

RESULTS

The study revealed that CML significantly promoted lipid uptake by macro-phages. Immunoprecipitation and radioactive receptor-ligand binding assays indicated that CML could specifically bind to both CD36 and RAGE. CML had a higher affinity for CD36 than RAGE. ARG82, ASN71, and THR70 were the potential interacting amino acids that CD36 binds to CML Anti-CD36 and anti-RAGE could block the uptake of CML by macrophages. The lipid uptake promotion effect of CML was significantly attenuated after blocking CD36 or RAGE.

CONCLUSION

Our results suggest that the binding of CML with CD36 and RAGE promotes macrophage lipid uptake.

Activin receptor-like kinase 7 promotes apoptosis of vascular smooth muscle cells via activating Smad2/3 signaling in diabetic atherosclerosis

Vascular smooth muscle cells (VSMCs) is a vital accelerator in the late phase of diabetic atherosclerosis, but the underlying mechanism remains unclear. The aim of our study was to investigate whether activin receptor-like kinase 7 (ALK7)-Smad2/3 pathway plays an important role in VSMC apoptosis of diabetic atherosclerosis. It was shown that ALK7 expression was obviously elevated in the aorta of ApoE−/− mice with type 2 diabetes mellitus. Inhibition of ALK7 expression significantly improved the stability of atherosclerotic plaques and reduced cell apoptosis. Further experiments showed that ALK7 knockdown stabilized atherosclerotic plaques by reducing VSMC apoptosis via activating Smad2/3. Our study uncovered the important role of ALK7-Smad2/3 signaling in VSMCs apoptosis, which might be a potential therapeutic target in diabetic atherosclerosis.

Advances in positron emission tomography tracers related to vascular calcification

Microcalcification, a type of vascular calcification, increases the instability of plaque and easily leads to acute clinical events. Positron emission tomography (PET) is a new examination technology with significant advantages in identifying vascular calcification, especially microcalcification. The use of the ¹⁸F-NaF is undoubtedly the benchmark, and other PET tracers related to vascular calcification are also currently in development. Despite all this, a large number of studies are still needed to further clarify the specific mechanisms and characteristics. This review aimed at providing a summary of the application and progress of different PET tracers and also the future development direction.

Apolipoprotein-AI and AIBP synergetic anti-inflammation as vascular diseases therapy: the new perspective

Vascular diseases (VDs) including pulmonary arterial hypertension (PAH), atherosclerosis (AS) and coronary arterial diseases (CADs) contribute to the higher morbidity and mortality worldwide. Apolipoprotein A-I (Apo A-I) binding protein (AIBP) and Apo-AI negatively correlate with VDs. However, the mechanism by which AIBP and apo-AI regulate VDs still remains unexplained. Here, we provide an overview of the role of AIBP and apo-AI regulation of vascular diseases molecular mechanisms such as vascular energy homeostasis imbalance, oxidative and endoplasmic reticulum stress and inflammation in VDs. In addition, the role of AIBP and apo-AI in endothelial cells (ECs), vascular smooth muscle (VSMCs) and immune cells activation in the pathogenesis of VDs are explained. The in-depth understanding of AIBP and apo-AI function in the vascular system may lead to the discovery of VDs therapy.

The Development of Maillard Reaction, and Advanced Glycation End Product (AGE)-Receptor for AGE (RAGE) Signaling Inhibitors as Novel Therapeutic Strategies for Patients with AGE-Related Diseases

Advanced glycation end products (AGEs) are generated by nonenzymatic modifications of macromolecules (proteins, lipids, and nucleic acids) by saccharides (glucose, fructose, and pentose) via Maillard reaction. The formed AGE molecules can be catabolized and cleared by glyoxalase I and II in renal proximal tubular cells. AGE-related diseases include physiological aging, neurodegenerative/neuroinflammatory diseases, diabetes mellitus (DM) and its complications, autoimmune/rheumatic inflammatory diseases, bone-degenerative diseases, and chronic renal diseases. AGEs, by binding to receptors for AGE (RAGEs), alter innate and adaptive immune responses to induce inflammation and immunosuppression via the generation of proinflammatory cytokines, reactive oxygen species (ROS), and reactive nitrogen intermediates (RNI). These pathological molecules cause vascular endothelial/smooth muscular/connective tissue-cell and renal mesangial/endothelial/podocytic-cell damage in AGE-related diseases. In the present review, we first focus on the cellular and molecular bases of AGE–RAGE axis signaling pathways in AGE-related diseases. Then, we discuss in detail the modes of action of newly discovered novel biomolecules and phytochemical compounds, such as Maillard reaction and AGE–RAGE signaling inhibitors. These molecules are expected to become the new therapeutic strategies for patients with AGE-related diseases in addition to the traditional hypoglycemic and anti-hypertensive agents. We particularly emphasize the importance of “metabolic memory”, the “French paradox”, and the pharmacokinetics and therapeutic dosing of the effective natural compounds associated with pharmacogenetics in the treatment of AGE-related diseases. Lastly, we propose prospective investigations for solving the enigmas in AGE-mediated pathological effects.