Advanced Glycation End Products Research Articles

2-Methoxy-4-formylphenol suppresses methylglyoxal glycation mediated structural alterations and esterase activity of hemoglobin - A multi spectroscopic, biophysical and in-silico study.

Glycation is the non-enzymatic reaction of glucose or its metabolites to proteins, causing irreversible changes. Methylglyoxal, a dicarbonyl, affects the structure and function of physiologically important proteins. Being a major circulatory protein, hemoglobin is highly prone to glycation. Current research focuses on identifying potent glycation inhibitors to prevent glycation and their impact on protein structure and function. The present study investigates the Advanced Glycation Endproducts (AGEs) inhibitory effects of 2-methoxy-4-formylphenol (Vanillin) against methylglyoxal mediated glycation of hemoglobin. The hemoglobin-vanillin glycation model exhibited inhibition of AGE formation, amyloid fibrils, aggregates and reduction in esterase activity. The fluorescence spectroscopic technique revealed efficient binding of vanillin and hemoglobin, with Stern Volmer plot indicating the presence of static quenching. The conformational stability of the vanillin and hemoglobin interaction was also evident from the molecular docking and dynamics studies. The proximal orientation of residues (H2 and K82 associated in esterase activity) of hemoglobin β1 chain and vanillin, supports the noted effect of reduced esterase activity in the presence of vanillin in glycated hemoglobin and the inhibition of the overall formation of AGE of hemoglobin in the presence of vanillin.

Assessment of cardiac and skeletal muscle metabolites using 1H-MRS and chemical-shift encoded magnetic resonance imaging: Impact of diabetes, RAGE, and DIAPH1.

Diabetes affects metabolism and metabolite concentrations in multiple organs. Previous preclinical studies have shown that receptor for advanced glycation end products (RAGE, gene symbol Ager) and its cytoplasmic domain binding partner, Diaphanous-1 (DIAPH1), are key mediators of diabetic micro- and macro-vascular complications. In this study, we used 1H-Magnetic Resonance Spectroscopy (MRS) and chemical shift encoded (CSE) Magnetic Resonance Imaging (MRI) to investigate the metabolite and water-fat fraction in the heart and hind limb muscle in a murine model of type 1 diabetes (T1D) and to determine if the metabolite changes in the heart and hind limb are influenced by (a) deletion of Ager or Diaph1 and (b) pharmacological blockade of RAGE-DIAPH1 interaction in mice. Nine cohorts of male mice, with six mice per cohort, were used: wild type non-diabetic control mice (WT-NDM), WT-diabetic (WT-DM) mice, Ager knockout non-diabetic (RKO-NDM) and diabetic mice (RKO-DM), Diaph1 knockout non-diabetic (DKO-NDM), and diabetic mice (DKO-DM), WT-NDM mice treated with vehicle, WT-DM mice treated with vehicle, and WT-DM mice treated with RAGE229 (antagonist of RAGE-DIAPH1 interaction). A Point Resolved Spectroscopy (PRESS) sequence for 1H-MRS, and multi-echo gradient recalled echo (GRE) for CSE were employed. Triglycerides, and free fatty acids in the heart and hind limb obtained from MRS and MRI were compared to those measured using biochemical assays. Two-sided t-test, non-parametric Kruskal-Wallis Test, and one-way ANOVA were employed for statistical analysis. We report that the results were well-correlated with significant differences using MRI and biochemical assays between WT-NDM and WT-DM, as well as within the non-diabetic groups, and within the diabetic groups. Deletion of Ager or Diaph1, or treatment with RAGE229 attenuated diabetes-associated increases in triglycerides in the heart and hind limb in mice. These results suggest that the employment of 1H-MRS/MRI is a feasible non-invasive modality to monitor metabolic dysfunction in T1D and the metabolic consequences of interventions that block RAGE and DIAPH1.

Molecular Mechanisms of Methylglyoxal in Diabetes-related Macrovascular Complications

Diabetes mellitus (DM) is a chronic endocrine and metabolic disease indicated by the presence of hyperglycemia. It has been known that hyperglycemia and oxidative stress are the main culprit of all DM complications, including macrovascular complications. As a byproduct of lipid, protein, and carbohydrate metabolism, methylglyoxal (MGO) is a highly reactive substance which plays a positive signaling role in helping cells regain redox balance under oxidative stress circumstances. DM-related problems lead to an excess of mitochondrial superoxide in the heart and big and small vascular endothelial cells. Elevated intracellular reactive oxygen species induce impaired angiogenesis in reaction to ischemia, trigger several proinflammatory pathways, and result in enduring epigenetic modifications that propel the continuous expression of proinflammatory genes even after glucose levels return to normal. Over time, the significance of the extremely quick advanced glycation end-products (AGE) production caused by the extremely reactive MGO has been clarified. It is now evident that MGO causes vascular tissue to react maladaptively. Glyoxalase 1 (GLO1) is the primary enzyme in an organism's enzymatic glyoxalase defense mechanism, which converts MGO to D-lactate in order to counteract the harmful effects of MGO. Understanding the role of the MGO–GLO1 pathway in the etiology of vascular disease in diabetes has advanced significantly. Therefore, it can be summarized that vascular damage are linked to diabetes. The AGE precursor MGO are important in determining the connection between diabetes and vascular damage. MGO and AGEs play a role in several phases of the development of diabetes complications. MGO and AGEs may be useful therapeutic targets for diabetes's macrovascular problems.KEYWORDS: hyperglycemia, AGE, methylglyoxal, glyoxalase, D-lactate, gluthatione, oxidative stress.

Modulation of persistent bladder pain in mice: The role of macrophage migration inhibitory factor, high mobility group box-1, and downstream signaling pathways

Background: Repeated intravesical activation of protease-activated receptor-4 (PAR4) serves as a model of persistent bladder hyperalgesia (BHA) in mice, which lasts several days after the final stimulus. Spinal macrophage migration inhibitory factor (MIF) and high mobility group box 1 (HMGB1) are critical mediators in the persistence of BHA. Objective: We aimed to identify effective systemic treatments for persistent BHA using antagonists or transgenic deletions. Methods: Persistent BHA was induced through transurethral instillations of a PAR4-activating peptide (PAR4-AP; 100 μM, 1 h; scrambled peptide, control) under anesthesia, administered on Days 0, 2, and 4. Lower abdominal hypersensitivity was measured on Days 0–4 and 7–9. Systemic injections from Days 2–8 included ISO-1 (a MIF antagonist), ethyl pyruvate (an inhibitor of HMGB1 release), phosphate-buffered saline, or 10% DMSO (vehicle control) in C57BL/6 mice. To examine the role of HMGB1 receptors, Toll-like receptor-4 (TLR4)-null mice or systemic treatment with FPS-ZM1 (receptor for advanced glycation end product [RAGE] antagonist) were used. In addition, TIR-domain-containing adaptor-inducing interferon-β (TRIF)-null mice were tested to assess the involvement of TLR4 signaling pathways. Micturition volume and frequency were assessed on Day 9, and the bladder was histopathologically examined to assess inflammation and edema. Results: MIF antagonism significantly reversed persistent BHA, whereas HMGB1 antagonism led to a partial reduction of persistent BHA. TLR4 deficiency or systemic administration of FPS-ZM1 significantly mitigated persistent BHA, while TRIF-deficient mice experienced a faster onset of BHA. Only MIF or HMGB1 inhibition resulted in increased micturition volume. The histopathological examination revealed no changes in inflammation or edema. Conclusion: MIF and HMGB1, acting through TLR4 and RAGE, mediated persistent BHA, while TRIF might modulate its onset. Further exploration of downstream TLR4 signaling may uncover novel therapeutic targets for treating persistent bladder pain.

SRAGE attenuates myocardial ischemia-reperfusion injury by recruiting Tregs through chemokine CCL4

Abstract Background Immune response has recently been shown to play a crucial role in myocardial ischemia-reperfusion (MIR). Our previous studies have confirmed that soluble receptors for advanced glycation end-products (sRAGE) could reduce myocardial ischemia-reperfusion injury (MIRI) by increasing the number of regulatory T cells (Tregs). However, the precise mechanism is still incompletely understood. Purpose The present study aimed to determine which kind of chemokines play a major role in recruiting Tregs during MIRI. The potential mechanism of sRAGE on the chemokine production was further explored. Methods We modeled mice with cardiac-specific overexpression of sRAGE by crossing the floxed sRAGE mouse model with the cardiomyocyte-specific Cre transgenic mouse. Experimental models were established utilizing left anterior descending coronary artery ligation in mice and oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. Transcriptomics, quantitative real-time polymerase chain reaction, immunohistochemistry, flow cytometry, and western blotting were used to determine the chemokines and related pathways involved in the recruitment of Tregs during MIRI. Results Using transcriptomics, quantitative real-time polymerase chain reaction, and western blotting approach, we identify the chemokine CCL4 plays a crucial role during regulatory T cell recruitment in the heart after MIRI. In vivo studies show that depletion of CCL4 reduces Tregs infiltration into the ischemic myocardium, subsequently deteriorating cardiac injury post-MIR. Mechanistically, sRAGE promotes cardiomyocytes to express and secrete CCL4 via the JNK/AP-1 pathway in vitro. Selective inhibition of the JNK/AP-1 pathway could decrease CCL4 production in sRAGE overexpression cardiomyocytes. Conclusions sRAGE induces Tregs recruitment and alleviates MIRI via the JNK/AP-1/CCL4 pathway, preserving myocardial function and impeding inflammation and apoptosis, providing new perspectives for immunotherapeutic targets in MIRI treatment.

A mathematical model of glomerular fibrosis in diabetic kidney disease to predict therapeutic efficacy

BackgroundGlomerular fibrosis is a tissue damage that occurs within the kidneys of chronic and diabetic kidney disease patients. Effective treatments are lacking, and the mechanism of glomerular damage reversal is poorly understood.MethodsA mathematical model suitable for hypothesis-driven systems pharmacology of glomerular fibrosis in diabetes was developed from a previous model of interstitial fibrosis. The adapted model consists of a system of ordinary differential equations that models the complex disease etiology and progression of glomerular fibrosis in diabetes.ResultsWithin the scope of the mechanism incorporated, advanced glycation end products (AGE)—matrix proteins that are modified due to high blood glucose—were identified as major contributors to the delay in the recovery from glomerular fibrosis after glucose control. The model predicted that inhibition of AGE production is not an effective approach for accelerating the recovery from glomerular fibrosis. Further, the model predicted that treatment breaking down accumulated AGE is the most productive at reversing glomerular fibrosis. The use of the model led to the identification that glucose control and aminoguanidine are ineffective treatments for reversing advanced glomerular fibrosis because they do not remove accumulated AGE. Additionally, using the model, a potential explanation was generated for the lack of efficacy of alagebrium in treating advanced glomerular fibrosis, which is due to the inability of alagebrium to reduce TGF-β.ImpactUsing the mathematical model, a mechanistic understanding of disease etiology and complexity of glomerular fibrosis in diabetes was illuminated, and then hypothesis-driven explanations for the lack of efficacy of different pharmacological agents for treating glomerular fibrosis were provided. This understanding can enable the development of more efficacious therapeutics for treating kidney damage in diabetes.

Stachys byzantina K. Koch (Lamiaceae) as a potential ingredient for delaying skin ageing and treating hyperpigmentation disorders in pharmaceutical products.

This study aimed to investigate whether the plant species Stachys byzantina produces bioactives with the potential to delay the skin ageing process and treat hyperpigmentation conditions. The antioxidant action was assessed by 2,2-diphenyl-1-picrylhydrazylradical scavenging, Griess reaction, oxygen radical absorption capacity, and β-carotene bleaching assays. Inhibitory activities for tyrosinase, hyaluronidase, and elastase enzymes were tested. The antiglycation activity, the sun protection factor (SPF), and the toxicity to skin cells by MTT(3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide)assay were also evaluated. The ethanolic extract of S. byzantina aerial parts and all fractions obtained by solvent partition inhibited the tyrosinase enzyme at different levels. The dichloromethane fraction (DF) demonstrated the highest inhibition (IC50 = 63.5±10.9 µg/ml). DF also inhibited the hyaluronidase enzyme with IC50 = 369±11.64 μg/ml and elastase by 40% at 500 μg/ml. This fraction showed prominent antioxidant and antiglycation activities, high SPF, and no cytotoxicity at concentrations lower than 50 μg/ml. The phenolic and flavonoid contents were 116.30±6.7 (mgTAE/g) and 66.38±13.5 (mgQE/g), respectively. Chlorogenic acid (23.54±2.46mg/g) and verbascoside (203.97±19.8mg/g) were identified and quantified. Stachys byzantina is a potential source of cosmetic and therapeutic ingredients to reduce hyperpigmentation and the impacts caused by free radicals, advanced glycation end products, and sun radiation in skin ageing.

Facile fabrication of redox nanoparticles loaded with exosomal-miRNAs and resveratrol as glycation inhibitor in alleviating the progression and development of diabetic cataract.

Diabetic cataract (DC) represents a highly prevalent ocular manifestation resulting from diabetes often culminating in vision impairment among individuals with diabetes. Regrettably, the armamentarium of pharmaceutical interventions capable of both delaying and thwarting the onset of DC remains conspicuously sparse. Based on contemporary investigations, the pathogenesis of DC is prominently influenced by oxidative harm to the crystalline lens and the nonenzymatic glycosylation of lens proteins. Consequently, we have developed self-regenerating cerium oxide nanoparticles (CeO2 NPs), enveloped with resveratrol (RSV) and exosomal-microRNA (miRNA) to alleviate the effects of DC in an in vitro model. Moreover, the inclusion of RSV within CeO2 NPs serves a dual purpose. It can act as an antioxidant, minimizing glycation, and induce oxidative stress by effectively neutralizing reactive oxygen species (ROS). Additionally, it serves as a glycation inhibitor effectively preventing the cross-linking. Consequently, it helps minimize the glucose level in hemoglobin and inhibits the formation of advanced glycation end products (AGEs). Likewise, the CeO2-exosomal-miRNA when treated alone found to slightly impede the viability of human lens epithelial cells (HLEC) and induce apoptosis by suppressing the expression of α-crystalline gene (CRYAA). Particularly, miRNAs target genes associated with oxidative stress pathways, protein glycation, and the generation of AGEs, hence preventing structural damage to lens proteins. Compared with CeO2, RSV-CeO2, and miRNA-RSV-CeO2, the presence of miRNA-RSV-CeO2 led to a significant decrease in hemoglobin glycation. Remarkably, miRNA-RSV-CeO2 NPs attenuate the formation of malondialdehyde (MDA) and conjugated dienes (CD) with a relative value of 14.63 and 11.37nmol/mg. As per the report, this method presents a promising opportunity to implement the proposed material combination for attenuating diabetic cataracts.

The predictive capacity of biomarkers for clinical pulmonary oedema in patients with severe falciparum malaria is low: a prospective observational study

BackgroundPulmonary oedema is a feared and difficult to predict complication of severe malaria that can emerge after start of antimalarial treatment. Proinflammatory mediators are thought to play a central role in its pathogenesis.MethodsAn exploratory study was conducted to evaluate the predictive capacity of biomarkers for development of clinical pulmonary oedema in patients with severe falciparum malaria at two hospitals in Bangladesh. Plasma concentrations of interleukin-6 (IL-6), IL-8, tumour necrosis factor (TNF), soluble Receptor of Advanced Glycation End-products (sRAGE), surfactant protein-D (SP-D), club cell secretory protein (CC16), and Krebs von den Lungen-6 (KL-6) on admission were compared with healthy controls. Correlations between these biomarker and plasma lactate and Plasmodium falciparum histidine-rich protein 2 (PfHRP2) levels were evaluated. Receiver Operating Characteristic (ROC) curves were constructed to assess the predictive capacity for clinical pulmonary oedema of the biomarkers of interest.ResultsOf 106 screened patients with falciparum malaria, 56 were classified as having severe malaria with a mortality rate of 29%. Nine (16%) patients developed clinical pulmonary oedema after admission. Plasma levels of the biomarkers of interest were higher in patients compared to healthy controls. IL-6, IL-8, TNF, sRAGE, and CC16 levels correlated well with plasma PfHRP2 levels (rs = 0.39; P = 0.004, rs = 0.43; P = 0.001, rs = 0.54; P < 0.001, rs = 0.44; P < 0.001, rs = 0.43; P = 0.001, respectively). Furthermore, IL-6 and IL-8 levels correlated well with plasma lactate levels (rs = 0.37; P = 0.005, rs = 0.47; P < 0.001, respectively). None of the biomarkers of interest had predictive capacity for development of clinical pulmonary oedema.ConclusionsIL-6, IL-8, TNF, sRAGE, SP-D, CC16 and KL-6 cannot be used in predicting clinical pulmonary oedema in severe malaria patients.

Pathophysiological Markers of Acute Respiratory Distress Syndrome Severity Are Correlated With Ventilation-Perfusion Mismatch Measured by Electrical Impedance Tomography.

Pulmonary ventilation/perfusion (V/Q) mismatch measured by electrical impedance tomography (EIT) is associated with the outcome of patients with the acute respiratory distress syndrome (ARDS), but the underlying pathophysiological mechanisms have not been fully elucidated. The present study aimed to verify the correlation between relevant pathophysiological markers of ARDS severity and V/Q mismatch. Prospective observational study. General ICU of a university-affiliated hospital. Deeply sedated intubated adult patients with ARDS under controlled mechanical ventilation. Measures of V/Q mismatch by EIT, respiratory mechanics, gas exchange, lung imaging, and plasma biomarkers. Unmatched V/Q units were assessed by EIT as the fraction of ventilated nonperfused plus perfused nonventilated lung units. At the same time, plasma biomarkers with proven prognostic and mechanistic significance for ARDS (carbonic anhydrase 9 [CA9], hypoxia-inducible factor 1 [HIF1], receptor for advanced glycation endproducts [RAGE], angiopoietin 2 [ANG2], gas exchange, respiratory mechanics, and quantitative chest CT scans were measured. Twenty-five intubated ARDS patients were included with median unmatched V/Q units of 37.1% (29.2-49.2%). Unmatched V/Q units were correlated with plasma levels of CA9 (rho = 0.47; p = 0.01), HIF1 (rho = 0.40; p = 0.05), RAGE (rho = 0.46; p = 0.02), and ANG2 (rho = 0.42; p = 0.03). Additionally, unmatched V/Q units correlated with plateau pressure (r = 0.38; p = 0.05) and with the number of quadrants involved on chest radiograph (r = 0.73; p < 0.01). Regional unmatched V/Q units were correlated with the corresponding fraction of poorly aerated lung tissue (r = 0.62; p = 0.01) and of lung tissue weight (rho: 0.51; p = 0.04) measured by CT scan. In ARDS patients, unmatched V/Q units are correlated with pathophysiological markers of lung epithelial and endothelial dysfunction, increased lung stress, and lung edema. Unmatched V/Q units could represent a comprehensive marker of ARDS severity, reflecting the complex organ pathophysiology and reinforcing their prognostic significance.

Dietary Restriction of Advanced Glycation End-Products (AGEs) in Patients with Diabetes: A Systematic Review of Randomized Controlled Trials

Advanced Glycation End Products (AGEs) are formed through non-enzymatic reactions between reducing sugars and proteins, nucleic acids or lipids (for example through hyperoxidation). In diabetes, elevated glucose levels provide more substrate for AGEs formation. AGEs can also be ingested through the diet from foods cooked at high temperatures, or containing much sugar. The present work aimed to review all published randomized controlled trials (RCT) on low-dietary AGE (L-dAGEs) interventions in patients with diabetes. Pubmed, Scopus and Cochrane databases were searched (until 29 February 2024) with appropriate keywords (inclusion criteria: RCT, patients with diabetes, age &gt; 18 years, outcomes related to inflammation, glucose, and lipids; exclusion criteria: non-RCTs, case-series, case reports and Letter to the Editor, or animal studies). The present review was registered to the Open Science Framework (OSF). From 7091 studies, seven were ultimately included. Bias was assessed with the updated Cochrane Risk of Bias tool. A reduction in circulating AGEs was documented in 3/3 studies. No particular differences were documented in glycemic parameters after a L-dAGEs diet. Reductions in glucose levels were observed in one out of six studies (1/6), while HbA1c and HOMA did not change in any study (0/6 and 0/3, correspondingly). Lipid profile also changed in one out of four studies (1/4). More consistent results were observed for oxidative stress (beneficial effects in 3/3 studies) and inflammatory markers (beneficial effects in 4/4 studies). Other athero-protective effects, such as adiponectin increases, were reported. Limitations included the small sample size and the fact that dietary and physical activity habits were not considered in most studies. In conclusion, a L-dAGEs pattern may minimize AGEs accumulation and have beneficial effects on oxidative stress and inflammation indices, while its effects on glycemic and lipemic parameters are inconsistent and modest in patients with diabetes.

Plasma-activated water pretreatment as a promising technique to reduce the formation of heterocyclic aromatic amines and advanced glycation end products in roasted fish patties

This study investigated the efficacy of using plasma-activated water (PAW) as a novel and additive-free pretreatment in reducing the formation of free and bound heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) in roasted fish patties. PAW activated for different durations (50 s, 100 s, and 150 s), significantly decreased the levels of HAAs and AGEs. The highest inhibition rates were observed at 35.44% and 19.82% for free and bound HAAs, respectively, and 42.76% and 23.23% for free and bound AGEs, respectively. PAW pretreatment reduced the formation of HAAs and AGEs and mitigated their increase during storage. Analysis using electron paramagnetic resonance and UPLC-MS/MS showed a decrease in free radicals and reactive carbonyls (phenylglyoxal, glyoxal, and methylglyoxal), which can serve as intermediates for HAAs and AGEs. Correlation analysis indicated a significant positive correlation between HAAs/AGEs and phenylacetaldehyde, glyoxal, methylglyoxal, and the total spin number (P < 0.05). This suggests that PAW suppresses the production of reactive carbonyls by quenching free radicals, thereby inhibiting the formation of HAAs and AGEs. In conclusion, with its additive-free approach, PAW pretreatment holds promise for reducing HAAs and AGEs and improving the safety of roasted fish products.

Targeting the Receptor for Advanced Glycosylation End-Products (RAGE) in Inflammation-associated Diabetes Mellitus

Targeting the Receptor for Advanced Glycosylation End-Products (RAGE) in Inflammation-associated Diabetes Mellitus

Stability of the Glycated Amino Acid 6-(2-Formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine (Pyrraline) During Oxidation.

Food proteins may be modified during processing and storage through reactions with reducing sugars (Maillard reaction, glycation) or by reactive oxygen species (protein oxidation). Little is known about particular reactions at the interface of glycation and oxidation. In the present study, the glycated amino acid pyrraline (6-(2-formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine) and the proteinogenic amino acids tyrosine and tryptophan were subjected to different types of oxidation. The stability of the amino acids was assessed by HPLC with UV detection, whereas oxidation products were assigned by HPLC with triple quadrupole or time-of-flight mass spectrometric detection. Conditions that lead to oxidation of aromatic proteinogenic amino acids can also lead to oxidation of pyrraline. Pyrraline was particularly unstable in the presence of permanganate, hypochlorite, and under hydroxyl radical-generating conditions (iron, ethylenediaminetetraacetic acid, ascorbic acid). Evidence obtained by high-resolution mass spectrometry revealed the oxidation of pyrraline to 6-(2,5-diformyl-1-pyrrolyl)-l-norleucine, 6-(2-carboxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine, 6-(2-formyl-5-carboxy-1-pyrrolyl)-l-norleucine, and 6-(2,5-dicarboxy-1-pyrrolyl)-l-norleucine in the presence of potassium permanganate. The latter product was isolated by semipreparative HPLC and characterized by NMR. Under hydroxyl radical-generating conditions, pyrraline is hydroxylated at the ring under formation of 6-(2-formyl-4-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine or 6-(2-formyl-3-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine. This study shows that the so-called "advanced glycation end products" are no end products of the Maillard reaction, but may undergo further chemical degradation reactions.

Indigestible proteins and peptide-bound AGEs in ultra-processed foods: Dulce de leche as a model of severely transformed protein food systems

Caramel milk confectioneries, such as dulce de leche, are produced by simmering whole or reconstituted milk with sugar and alkali at temperatures ranging from 115 to 130 °C for several hours. This process triggers extensive non-enzymatic browning through the Maillard reaction, leading to significant modifications in milk proteins. Our research focused on the effects of such severe processing conditions on the structural integrity and digestibility of milk proteins, using dulce de leche as a model for severely transformed food protein systems. Due to structural modifications, covalent interchain cross-links, and sugar-derived bridging moieties, milk proteins in dulce de leche form high molecular weight aggregates that are not resolvable by SDS-PAGE. Proteomic analysis revealed that all major milk proteins are involved in the formation of these covalent molecular complexes. When subjected to static gastro-duodenal digestion using both adult and infant models, these macroaggregates showed resistance to pepsin and marginal susceptibility to duodenal proteases. High pressure liquid chromatography-tandem mass spectrometry (HPLC-MS/MS)-based peptidomic analysis of dulce de leche digests allowed identifying variously sized polypeptides bearing the hallmarks of the Maillard reaction. However, many MS signals could not be assigned due to unknown modifications. The prevalence of free and peptide-bound advanced glycated end products (AGEs) in caramel milk products and other ultra-processed foods poses significant health concerns, stressing the need for a comprehensive dedicated evaluation.

Amyloid-beta aggregation and advanced glycation end-products inhibitory activities of Pandanus amaryllifolius Roxb. alkaloids: insights from in vitro and computational investigations

Amyloid-beta aggregation and advanced glycation end-products inhibitory activities of Pandanus amaryllifolius Roxb. alkaloids: insights from in vitro and computational investigations

Soluble receptors for advanced glycation endproducts are predictors of insulin sensitivity and affected by weight loss

BackgroundMice experiments have underscored the efficacy of pharmacological inhibition of advanced glycation endproducts (AGEs) through the use of soluble receptors for advanced glycation endproducts (sRAGE) in mitigating obesity-linked metabolic disruptions and insulin resistance. However, human studies have presented conflicting findings regarding the correlation between circulating sRAGE levels and insulin resistance, as well as glucose tolerance. Here, we aimed to delve deeper into the relationship between sRAGE levels and systemic insulin sensitivity.MethodsPlasma sRAGE levels, hyperinsulinemic-euglycemic clamp, and continuous glucose monitoring were measured in two independent cross-sectional case-control studies [cohort 1 (n = 180) and cohort 2 (n = 124)]. In addition, a subgroup of 42 participants with obesity were followed for 12 months. In 14 of these participants, weight loss was achieved through bariatric surgery intervention.ResultsOur results revealed a significant association between plasma sRAGE levels and both insulin sensitivity and glycemic control parameters, even after adjustments for age, sex, and BMI. Furthermore, longitudinal analysis demonstrated that interventions aimed at weight loss led to reductions in fasting glucose and HbA1c levels, concurrently with increases in sRAGE levels.ConclusionsThese findings underscore that sRAGE levels were strongly associated with insulin sensitivity and glycemic control, suggesting a possible role of sRAGE in preserving insulin sensitivity and maintaining glycemic control, which should be confirmed in further studies.

Skin senescence—from basic research to clinical practice

The most recognizable implications of tissue aging manifest themselves on the skin. Skin laxity, roughness, pigmentation disorders, age spots, wrinkles, telangiectasia or hair graying are symptoms of physiological aging. Development of the senescent phenotype depends on the interaction between aging cells and remodeling of the skin’s extracellular matrix (ECM) that contains collagen and elastic fiber. Aging changes occur due to the combination of both endogenous (gene mutation, cellular metabolism or hormonal agents) and exogenous factors (ultraviolet light, environmental pollutants, and unsuitable diet). However, overproduction of mitochondrial reactive oxygen species (ROS) is a key factor driving cellular senescence. Aging theories have disclosed a range of diverse molecular mechanisms that are associated with cellular senescence of the body. Theories best supported by evidence include protein glycation, oxidative stress, telomere shortening, cell cycle arrest, and a limited number of cell divisions. Accumulation of the ECM damage is suggested to be a key factor in skin aging. Every cell indicates a functional and morphological change that may be used as a biomarker of senescence. Senescence-associated β-galactosidase (SA-β-gal), cell cycle inhibitors (p16INK4a, p21CIP1, p27, p53), DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS), senescence-associated heterochromatin foci (SAHF), shortening of telomeres or downregulation of lamina B1 constitute just an example of aging biomarkers known so far. Aging may also be assessed non-invasively through measuring the skin fluorescence of advanced glycation end-products (AGEs). This review summarizes the recent knowledge on the pathogenesis and clinical conditions of skin aging as well as biomarkers of skin senescence.

Increased Levels of Circulating Methylglyoxal Have No Consequence for Cerebral Microvascular Integrity and Cognitive Function in Young Healthy Mice.

Diabetes and other age-related diseases are associated with an increased risk of cognitive impairment, but the underlying mechanisms remain poorly understood. Methylglyoxal (MGO), a by-product of glycolysis and a major precursor in the formation of advanced glycation end-products (AGEs), is increased in individuals with diabetes and other age-related diseases and is associated with microvascular dysfunction. We now investigated whether increased levels of circulating MGO can lead to cerebral microvascular dysfunction, blood-brain barrier (BBB) dysfunction, and cognitive impairment. Mice were supplemented or not with 50mM MGO in drinking water for 13weeks. Plasma and cortical MGO and MGO-derived AGEs were measured with UPLC-MS/MS. Peripheral and cerebral microvascular integrity and inflammation were investigated. Cerebral blood flow and neurovascular coupling were investigated with laser speckle contrast imaging, and cognitive tests were performed. We found a 2-fold increase in plasma MGO and an increase in MGO-derived AGEs in plasma and cortex. Increased plasma MGO did not lead to cerebral microvascular dysfunction, inflammation, or cognitive decline. This study shows that increased concentrations of plasma MGO are not associated with cerebral microvascular dysfunction and cognitive impairment in healthy mice. Future research should focus on the role of endogenously formed MGO in cognitive impairment.

EXPRESS: Plasma from Type 1 Diabetes Patients Promotes Pro-atherogenic Cholesterol Transport in Human Macrophages.

Hyperglycemia, one of the major risk factors for atherosclerosis, leads to the accumulation of Advanced glycation end products (AGEs), contributing to cardiovascular complications. Such accumulation may accelerate the progression of vascular disease in patients with diabetes. Reverse cholesterol transport (RCT) protein, ATP-binding membrane cassette transporters A1 and G1 (ABCA1 and ABCG1) and cholesterol 27-hydroxylase facilitate cholesterol removal from macrophages. AGE inhibits reverse cholesterol transport by reducing the expression of ABCA1 and ABCG1. This study aimed to evaluate whether plasma from poorly controlled adolescents with type 1 diabetes (T1D) disrupts cholesterol homeostasis in human monocytes/macrophages. Twenty healthy controls (HC) and 20 patients with T1DM, 10 to 19 years old, were enrolled. Naïve THP-1 macrophages were exposed to plasma from each HC and patient with T1D. Following incubation, mRNA for cholesterol efflux (ABCA1, ABCG1, 27-hydroxylase) and cholesterol uptake (CD36, ScR-A1, lectin oxidized low-density lipoprotein (LOX)-1, CXCL16) were isolated. Foam cell formation was quantified to confirm the pro-atherogenic effects of T1D plasma on macrophages. Results showed that T1D plasma had an elevated level of CML-modified proteins and upregulated CXCL16 and, to a lesser degree, ScR-A1. This change in gene expression in the presence of T1D plasma is associated with increased lipid accumulation and foam cell formation by THP-1 macrophages. In our study, these cells' uptake of an AGE product occurred mainly through the SR-A1 and CXCL16 receptors, leading to increased intracellular oxidized LDL. We conclude that AGEs may contribute to accelerated atherosclerosis in diabetes through effects on both forward and reverse cholesterol movement.