Accumulation of advanced glycation end products in skin and increased vascular ageing in the general population: the Malmö Offspring Study

Advanced Glycation End Products (AGEs) Webinar Meeting Report

The advanced glycation end products (AGEs) Webinar was co-hosted by Diabetes Technology Society and Kitalys Institute on August 8, 2024, with the goal of reviewing progress made in the measurement and use of AGEs in clinical practice. Meeting topics included (1) AGEs as predictors of diabetic nephropathy (DKD), (2) hemoglobin glycation index (HGI) and the glycation gap (GG), (3) formation and structure of AGEs, (4) AGEs as a risk factor of cardiovascular disease (CVD), and (5) approaches to limit or prevent AGE formation.

Effect of Mesenchymal Stem Cell-Derived Extracellular Vesicles Induced by Advanced Glycation End Products on Energy Metabolism in Vascular Endothelial Cells

Introduction

Advanced glycation end products (AGEs) play a critical role in the development of vascular diseases in diabetes. Although stem cell therapies often involve exposure to AGEs, the impact of this environment on extracellular vesicles (EVs) and endothelial cell metabolism remains unclear.

Methods

Human umbilical cord mesenchymal stem cells (MSCs) were treated with either 0 ng/ml or 100 ng/ml AGEs in a serum-free medium for 48 hours, after which MSC-EVs were isolated. The EVs were characterized by morphology, particle size, and protein markers of MSC-EVs, and microRNA (miRNA) sequencing was performed to identify differentially expressed miRNAs. MSC-EVs were cocultured with human umbilical vein endothelial cells (HUVECs) to assess effects on cell viability, metabolic activity, oxidative stress, and antioxidant capacity. Tube formation and glucose transporter protein analyses were conducted to evaluate the angiogenic ability and glucose metabolism capacity.

Results

MSC-EVs ranged from 30 to 150 nm, which is consistent with exosomal properties. AGEs treatment reduced MSC viability but had minimal effect on EV morphology and protein markers. miRNA sequencing showed downregulation of hsa-miR-223-3p and hsa-miR-126-3p_R-1, with upregulation of hsa-miR-574-5p, implicating changes in glycolytic and oxidative phosphorylation pathways. MSC-EVs treated with AGEs decreased HUVEC viability (P < 0.05), pH (P < 0.05), adenosine triphosphate (ATP) metabolism (P < 0.05), glucose metabolism (P < 0.05), while enhancing glycolysis processes, including glycolytic activity, capacity, and reserve (P < 0.05). This likely resulted from impaired mitochondrial function, including reduced ATP production, maximal respiration, basal respiration, and spare respiratory capacity (P < 0.05), or increased reactive oxygen species (ROS) (P < 0.05) and glucose-6-phosphate dehydrogenase (G6PD) activity (P < 0.05). In addition, AGEs reduced glucose transporter types 1, 3, and 4 (GLUT1, GLUT3, GLUT4), and synthesis of cytochrome c oxidase 2 expression (P < 0.05), along with angiogenic capacity (P < 0.05) in HUVECs.

Conclusion

Exposure to AGEs diminishes the therapeutic potential of MSC-derived EVs by disrupting energy metabolism and promoting metabolic reprogramming in endothelial cells. These findings suggest that adjusting the dosage or frequency of MSC-EVs may enhance their efficacy for treating diabetes-related vascular conditions. Further research is warranted to evaluate AGEs' broader impact on various cell types and metabolic pathways for improved exosome-based therapies.

Blood Pressure Regulation in Post-COVID POTS: Beyond Sinus Tachycardia

BACKGROUND

Postural orthostatic tachycardia syndrome (POTS) is a frequently diagnosed cardiovascular disorder after COVID-19 infection. POTS is characterized by the presence of excessive sinus tachycardia on standing without a fall in blood pressure (BP). We investigated the BP profile using 24-hour ambulatory BP monitoring in patients with new-onset POTS after COVID-19 compared with prepandemic population-based controls.

METHODS

We performed a case-control study in 100 patients (mean age, 40.0±12.9 years; 85% women) with verified post-COVID-19 new-onset POTS diagnosed by a positive head-up tilt testing versus 100 controls from a population-based cohort with a negative active standing test, no history of syncope, POTS, or endocrine disease (mean age, 42.3±14.0 years; 78% women). Twenty-four-hour BP profile was assessed for circadian BP variation including hypotensive systolic BP (SBP) episodes (<80, <90, and <100 mm Hg).

RESULTS

Patients with post-COVID-19 POTS had significantly higher nighttime SBP, but not daytime SBP, and more daytime SBP hypotensive episodes compared with controls. Nondipping (34% versus 19%; P<0.001) and reverse dipping patterns (9% versus 0%; P<0.001) were more frequent in post-COVID-19 POTS. In the logistic regression, patients with post-COVID-19 POTS had significantly higher mean 24-hour SBP (odds ratio, 1.08 [95% CI, 1.04-1.11]; P<0.001) and nighttime SBP (odds ratio, 1.07 [95% CI, 1.04-1.10]; P<0.001), independent of age and sex.

CONCLUSIONS

Patients with post-COVID-19 POTS demonstrate higher mean 24-hour and nighttime SBP and show disruptions of circadian BP rhythm regulation compared with population-based controls, as well as more daytime hypotensive episodes. Future studies are needed to test whether patients with post-COVID-19 POTS may benefit from tailored BP therapy.

The combined predictive power of the atherogenic index of plasma and serum glycated albumin for cardiovascular events in postmenopausal patients with acute coronary syndrome after percutaneous coronary intervention

BACKGROUND

Glycated Albumin (GA) and atherogenic index of plasma (AIP) are two important biomarkers that respectively reflect lipid and glucose levels. Previous research has revealed their roles in cardiovascular diseases (CVD) and diabetes. However, their combined predictive ability in forecasting cardiovascular events (CVE) after percutaneous coronary intervention (PCI) among postmenopausal acute coronary syndrome (ACS) patients remains insufficiently studied.

METHODS

Based on the levels of AIP (AIP-L and AIP-H) and GA (GA-L and GA-H), four groups were used to categorize the patients. The CVE assessed included cardiac death, nonfatal myocardial infarction (MI) and nonfatal stroke. To evaluate the relationship between AIP, GA, and CVE, multivariate Cox regression analyses were performed.

RESULTS

98 patients (7.5%) experienced CVE during follow-up. AIP and GA were revealed as strong independent predictors of CVE through multivariate analysis (AIP: HR 3.324, 95%CI 1.732-6.365, P = 0.004; GA: HR 1.098, 95% CI 1.023-1.177, P = 0.009). In comparison to those in the initial group (AIP-L and GA-L), the fourth group (AIP-H and GA-H) of patients exhibited the greatest CVE risk (HR 2.929, 95% CI 1.206-5.117, P = 0.018). Derived from the model of baseline risk, the combination of AIP + GA significantly enhanced the AUC, meanwhile combining AIP and GA levels maximized prognostic accuracy in the baseline risk model.

CONCLUSIONS

This study found that the combined measurement of AIP and GA significantly enhanced the predictive capability for CVE following PCI in postmenopausal ACS patients. By integrating these two biomarkers, it became possible to more accurately identify high-risk individuals and provided clinicians with new predictive tools for postmenopausal ACS patients in risk assessment and management.

Advancing the Diagnosis of Diabetic Neuropathies: Electrodiagnostic and Skin Autofluorescence Methods

INTRODUCTION

Diabetic neuropathy (DN) is a generic term for various neuropathies coexisting in a single patient. Clinical diagnosis alone can be misleading, yet routine electrodiagnostic studies in diabetes care are rare. Skin autofluorescence (SAF) is a recognized DN risk factor with potential screening value. This article highlights the diagnostic challenges and raises awareness of the often underdiagnosed neuropathic conditions in diabetes patients.

MATERIAL AND METHODS

We present common entrapment neuropathy cases from our diabetes clinic's electrodiagnosis laboratory in Iași, Romania. We selected seven type 2 diabetes patients with sensory or sensory-motor distal polyneuropathy and atypical DN presentations investigated through electroneurography (ENG) and electromyography (EMG) with the Neurosoft® EMG instrument and SAF measured by standard procedures. Subsequently, a narrative literature review was conducted.

RESULTS

Entrapment neuropathies were diagnosed in all the patients: three carpal tunnel syndromes, two ulnar neuropathies (one proximal, one distal), one peroneal neuropathy, and one case of meralgia paresthetica. The lower-limb cases showed radiculoplexopathy, and there was one case of superficial radial nerve neuropathy. The SAF values ranged from 2.5 AU to 3.4 AU.

CONCLUSIONS

Electrodiagnosis is essential for detecting focal neuropathies in patients with sensory-motor distal polyneuropathy. Elevated SAF levels may correlate with symptom severity, although further research, including large cohorts, is needed.

Associations between Skin Autofluorescence Levels with Cardiovascular Risk and Diabetes Complications in Patients with Type 2 Diabetes

Advanced Glycation End Products (AGEs) contribute to the pathophysiology of type 2 diabetes mellitus (T2DM) and cardiovascular (CV) diseases (CVDs), making their non-invasive assessment through skin autofluorescence (SAF) increasingly important. This study aims to investigate the relationship between SAF levels, cardiovascular risk, and diabetic complications in T2DM patients. We conducted a single-center, cross-sectional study at Consultmed Hospital in Iasi, Romania, including 885 T2DM patients. The assessment of SAF levels was performed with the AGE Reader™, (Diagnoptics, Groningen, The Netherlands). CVD prevalence was 13.9%, and according to CV risk category distribution, 6.1% fell into the moderate-risk, 1.13% into the high-risk, and 92.77% into the very-high-risk category. The duration of DM averaged 9.0 ± 4.4 years and the mean HbA1c was 7.1% ± 1.3. After adjusting for age and eGFR, HbA1c values showed a correlation with SAF levels in the multivariate regression model, where a 1 SD increase in HbA1c was associated with a 0.105 SD increase in SAF levels (Nagelkerke R2 = 0.110; p < 0.001). For predicting very high risk with an SAF cut-off of 2.35, sensitivity was 67.7% and specificity was 56.2%, with an AUC of 0.634 (95% CI 0.560-0.709, p = 0.001). In T2DM, elevated SAF levels were associated with higher CV risk and HbA1c values, with 2.35 identified as the optimal SAF cut-off for very high CV risk.

Advanced Glycation Endproducts: A Marker of Long-term Exposure to Glycemia

This article examines the importance of advanced glycation endproducts (AGEs) and summarizes the structure of AGEs, pathological changes associated with AGEs, the contribution of AGEs to metabolic memory, and the value of AGEs as a predictor of diabetic complications and cardiovascular disease in people with and without diabetes. As a practical focus, skin autofluorescence (SAF) is examined as an attractive approach for estimating AGE burden. The measurement of AGEs may be of significant value to specific individuals and groups, including Black and Hispanic/Latino Americans, as they appear to have higher concentrations of hemoglobin A1c (HbA1c) than would be predicted by other metrics of mean glycemia. We hypothesize that if the amount of glycation of HbA1c is greater than expected from measured glucose levels, and if AGEs are accumulating, then this accumulation of AGEs might account for the increased rate of complications of diabetes in populations with high rates of vascular disease and other complications. Thus, identifying and modifying the burden of AGEs based on measurement of AGEs by SAF may turn out to be a worthwhile metric to determine individuals who are at high risk for the complications of diabetes as well as others without diabetes at risk of vascular disease. We conclude that available evidence supports SAF as both a clinical measurement and as a means of evaluating interventions aimed at reducing the risks of vascular disease and diabetic complications.