Tobacco smoke is a source of toxic reactive glycation products

Advanced Glycation End-Products and Metabolomics Are Independently Associated With Frailty: The Longitudinal Doetinchem Cohort Study

Skin autofluorescence (SAF), reflecting advanced glycation endproducts' accumulation in tissue, has been proposed as a noninvasive aging biomarker. Yet, SAF has not been compared with well-established blood-based aging biomarkers such as MetaboHealth in association with frailty. Furthermore, no previous study determined the longitudinal association of SAF with frailty. We used 2 382 Doetinchem Cohort Study participants' (aged 46.0-85.4) cross-sectional data, of whom 1 654 had longitudinal SAF measurements. SAF was measured using the AGE Reader. MetaboHealth was calculated on 1H-NMR-metabolomics. Linear regressions were used for the associations of SAF and MetaboHealth on the 36-deficit frailty index and logistic regressions for being pre-frail or frail as determined by the frailty phenotype. Longitudinal associations were determined by an interaction term between age and SAF in a linear mixed model. SAF and MetaboHealth were associated with higher odds of pre-frailty (odd ratios per standard deviation SAF: 1.21 [1.10-1.32], MetaboHealth: 1.35 [1.24-1.49]) and frailty (SAF: 1.70 [1.41-2.06], MetaboHealth: 1.90 [1.57-2.32]). When mutually adjusted, both aging biomarkers remained associated with pre-frailty (SAF: 1.16 [1.05-1.27], MetaboHealth 1.33 [1.21-1.46]) and frailty (SAF: 1.52 [1.25-1.85], MetaboHealth: 1.75 [1.43-2.14]). Additionally, SAF and MetaboHealth were associated with higher frailty index scores (percentage increase per standard deviation SAF: 1.35 [1.00-1.70], MetaboHealth: 1.87 [1.54-2.20]), also after mutual adjustment (SAF: 1.02 [0.68-1.37], MetaboHealth: 1.69 [1.35-2.02]). SAF was also longitudinally associated with the frailty index (percentage per unit/year increase: 0.12 [0.07-0.16]). The mutual independence of SAF and MetaboHealth implies they capture distinct aspects of the aging process. Altogether, these findings emphasize SAF's clinical potential as an age-related decline biomarker, which could be further enhanced when combined with MetaboHealth.

Association of Glutathione S-transferase gene polymorphism with coronary artery disease (CAD) in North Indian population (Jammu and Kashmir): evidence from a case-control study and an updated meta-analysis

BACKGROUND

Chemicals released during cigarette smoking disrupt the structure, function and physiological capacity of the cardiovascular system. Detoxification of these harmful chemicals is done by Glutathione S-transferase (GST) isoenzymes (GSTM1 and GSTT1). GST gene polymorphisms may have a role in conferring susceptibility to coronary artery disease. This case-control study aims to evaluate the relationship between GSTM1 and GSTT1 gene polymorphisms, smoking habits, and coronary artery disease (CAD) in the Northern Indian population of Jammu and Kashmir, strengthened by a meta-analysis based on previously published studies.

METHODS

The current study involved 220 patients with CAD and 240 healthy controls from the Jammu region in the Union Territory of Jammu and Kashmir. Whole blood DNA was isolated, followed by genotyping using the polymerase chain reaction (PCR) technique.

RESULTS

Smoking, a non-vegetarian diet, and lipid levels were found to be significantly associated with coronary artery disease (CAD). The frequency of the GSTMnull genotype was significantly higher in patients than in controls (48.2% vs. 33.3%), while both groups showed comparable frequencies of the GSTTnull genotype. Combined genotype analysis indicated that the GSTM1 Tnull genotype was associated with an increased risk of CAD, with an adjusted odds ratio (AOR) of 1.70 and a 95% confidence interval (CI) of 1.30-2.27(p = 0.05). Patients who were smokers and had the GSTMnull genotype, as well as those with the GSTM1Tnull or GSTMnullT1 genotypes, were at a significantly higher risk of developing CAD. The results of the meta-analysis supported the findings of the case-control association study.

CONCLUSION

The GSTM1 null genotype, either independently or in conjunction with smoking, is linked to the incidence of CAD among North Indians in Jammu and Kashmir.

Mitochondrial DNA signals driving immune responses: Why, How, Where?

There has been a recent expansion in our understanding of DNA-sensing mechanisms. Mitochondrial dysfunction, oxidative and proteostatic stresses, instability and impaired disposal of nucleoids cause the release of mitochondrial DNA (mtDNA) from the mitochondria in several human diseases, as well as in cell culture and animal models. Mitochondrial DNA mislocalized to the cytosol and/or the extracellular compartments can trigger innate immune and inflammation responses by binding DNA-sensing receptors (DSRs). Here, we define the features that make mtDNA highly immunogenic and the mechanisms of its release from the mitochondria into the cytosol and the extracellular compartments. We describe the major DSRs that bind mtDNA such as cyclic guanosine-monophosphate-adenosine-monophosphate synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), NOD-, LRR-, and PYD- domain-containing protein 3 receptor (NLRP3), absent in melanoma 2 (AIM2) and toll-like receptor 9 (TLR9), and their downstream signaling cascades. We summarize the key findings, novelties, and gaps of mislocalized mtDNA as a driving signal of immune responses in vascular, metabolic, kidney, lung, and neurodegenerative diseases, as well as viral and bacterial infections. Finally, we define common strategies to induce or inhibit mtDNA release and propose challenges to advance the field.

Methylglyoxal mutagenizes single-stranded DNA via Rev1-associated slippage and mispairing

Methylglyoxal (MG) is a highly reactive aldehyde that is produced endogenously during metabolism and is derived from exogenous sources such as sugary food items and cigarette smoke. Unless detoxified by glyoxalases (Glo1 and Glo2), MG can readily react with all major biomolecules, including DNA and proteins, generating characteristic lesions and glycation-derived by- products. As a result, MG exposure has been linked to a variety of human diseases, including cancers. Prior studies show that MG can glycate DNA, preferentially on guanine residues, and cause DNA damage. However, the mutagenicity of MG is poorly understood in vivo. In the context of cancer, it is essential to comprehend the true contribution of MG to genome instability and global mutational burden. In the present study, we show that MG can robustly mutagenize induced single-stranded DNA (ssDNA) in yeast, within a guanine centered mutable motif. We demonstrate that genome-wide MG mutagenesis in ssDNA is greatly elevated throughout the genome in the absence of Glo1, and abrogated in the presence of the aldehyde quencher aminoguanidine. We uncovered strand slippage and mispairing as the predominant mechanism for generation of all MG-associated mutations, and demonstrate that the translesion polymerase Rev1 is necessary in this pathway. Finally, we find that the primary MG-associated mutation is enriched in a variety of sequenced tumor datasets. We discuss the genomic impact of methylglyoxal exposure in the context of mutagenesis, DNA damage, and carcinogenesis.

Genetically proxied therapeutic inhibition of antihypertensive drug targets and risk of pancreatic cancer: a mendelian randomization analysis

BACKGROUND

Conventional epidemiological studies have reported inconsistent results regarding the potential adverse effects of long-term use of antihypertensive drugs on cancer risk. Nevertheless, evidence of their impact on pancreatic cancer risk is limited and deserves further elucidation.

METHODS

We selected genetic variants from the genes encoding the target proteins (angiotensin-converting enzyme, beta-1 adrenergic receptor, and solute carrier family 12 member 3) of the examined antihypertensive drugs as instruments based on expression quantitative trait loci (eQTL) studies. Genetic summary statistics of blood pressure and pancreatic cancer were obtained from genome-wide association studies (GWASs) in Europeans and East Asians. Inverse-variance weight and MR-Egger methods were employed to estimate the effect of genetic variations in the drug targets on pancreatic cancer risk, and meta-analysis was used to combine the results from 3 independent datasets. Positive control analysis was conducted by using Wald ratio test to justify the genetic instruments of the drug by demonstrating the expected effect on the blood pressure which has an established causal relationship with the drug of interest.

RESULTS

Genetically proxied ACEIs were associated with lower pancreatic risk (OR = 0.506, 95% CI: 0.284-0.901, P = 0.021; OR = 0.265, 95% CI: 0.094-0.751, P = 0.012; OR = 0.236, 95% CI:0.078-0.712, P = 0.010, respectively) in 3 independent datasets and the combined results were validated in a meta-analysis using a random effects model (OR = 0.37, 95% CI: 0.22-0.64, P < 0.01) or fixed effects model (OR = 0.39, 95% CI: 0.25-0.62, P < 0.01). Other drug targets did not show consistent significant associations with pancreatic cancer risk in all 3 independent datasets.

CONCLUSIONS

Our study indicated that genetically proxied therapeutic inhibition of ACE was associated with a lower risk of pancreatic cancer, which may have translational potential in clinical practice. However, further long-term randomized controlled trials and observational studies are needed to clarify the effect of ACEIs on the pancreatic cancer risk.

The role of AGEs in muscle ageing and sarcopenia

Sarcopenia is an ageing-related disease featured by the loss of skeletal muscle quality and function. Advanced glycation end-products (AGEs) are a complex set of modified proteins or lipids by non-enzymatic glycosylation and oxidation. The formation of AGEs is irreversible, and they accumulate in tissues with increasing age. Currently, AGEs, as a biomarker of ageing, are viewed as a risk factor for sarcopenia. AGE accumulation could cause harmful effects in the human body such as elevated inflammation levels, enhanced oxidative stress, and targeted glycosylation of proteins inside and outside the cells. Several studies have illustrated the pathogenic role of AGEs in sarcopenia, which includes promoting skeletal muscle atrophy, impairing muscle regeneration, disrupting the normal structure of skeletal muscle extracellular matrix, and contributing to neuromuscular junction lesion and vascular disorders. This article reviews studies focused on the pathogenic role of AGEs in sarcopenia and the potential mechanisms of the detrimental effects, aiming to provide new insights into the pathogenesis of sarcopenia and develop novel methods for the prevention and therapy of sarcopenia.

Auto-antibodies against carbonyl-modified vimentin in COPD: potential role as a biomarker

COPD has many hallmarks of autoimmune dysfunction. Driving this autoimmune response are self-antigens, such as highly abundant structural proteins and cellular proteins, which can lead to the production of auto-antibodies. However, controversy surrounds the detection of some of these auto-antibodies as they have often been screened against native, unmodified proteins. Autoantigens arise as a result of a conformational change in the native protein exposing hidden epitopes or by the creation of neo-epitopes through chemical or enzymatic modifications, often caused by oxidative/carbonyl stress. In this study, we screened for auto-antibodies targeting key structural proteins modified by oxidative/carbonyl stress in peripheral blood from stable COPD patients versus control subjects using ELISA. We found an auto-antibody response against unmodified, carbonyl-modified and citrinylated vimentin, with the highest response observed against carbonyl-modified vimentin. Both the IgG and IgM antibody titres against carbonyl-modified were significantly increased in COPD patients compared to healthy non-smokers. Smokers also displayed increased antibody levels against carbonyl-modified vimentin, but only for the IgG isotype. Selectivity analysis indicated that 70% and 63% of COPD patients had higher IgM and IgG titres, respectively, compared to non-smokers. In contrast only 26% and 48% of smokers had higher IgM and IgG titres, respectively, than non-smokers. ROC analysis gave AUC values of 0.78 (p < 0.01) and 0.84 (p < 0.001) for IgM and IgG, respectively, for COPD versus non-smokers, which fell to 0.70 (p < 0.01) and 0.64 (NS), respectively, when asymptomatic smokers were included. No significant increase in antibody titre against carbonyl-modified elastin or collagen was observed in COPD patients or asymptomatic smokers. We conclude that IgM autoantibody responses against carbonyl modified vimentin could serve as a simple blood-based biomarker for COPD, reflecting the disease's pathophysiology, and could help in patient stratification and diagnosis.

A Mediterranean diet improves glycation markers in healthy people and in those with chronic diseases: a systematic review of clinical trials

CONTEXT

Consumption of the Mediterranean diet (MedDiet) has beneficial effects on cardiometabolic health and aging.

OBJECTIVE

This systematic review aimed to critically investigate the effect of the MedDiet on glycation markers in healthy or overweight individuals with type 2 diabetes or cardiovascular disease.

DATA SOURCES

MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched, using the terms "Mediterranean diet" AND "glycation end products, advanced".

DATA EXTRACTION

Three randomized and 3 nonrandomized clinical trials, containing data on 2935 adult and elderly individuals with normal weight or overweight, were included. All extracted data were compiled, compared, and critically analyzed.

DATA ANALYSIS

The authors of most of the studies demonstrated a reduction in serum concentrations of advanced glycation end products (AGEs), such as εN-carboxymethyllysine and methylglyoxal, and in skin autofluorescence levels after at least 4 weeks of adherence to the MedDiet. The MedDiet also led to positive effects on gene expression of receptors for AGEs, as RAGE and AGER1, and an enzyme involved in detoxification (glyoxalase I). There is no evidence that short-term adherence affects glycation markers.

CONCLUSIONS

Glycation markers improved in response to the MedDiet. The possible mechanisms involved may be related to the low AGE and refined sugars content of the diet, as well as its high monounsaturated fatty acid, phenolic compound, and dietary fiber contents.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021284006.

Dynamic changes of lung sRAGE in mice with chronic obstructive pulmonary disease induced by cigarette smoke exposure

OBJECTIVE

To study the changes of lung function, pathophysiology, inflammatory cytokines and related inflammatory responses in COPD mouse model, and to analyze the role of sRAGE in the pathogenesis of COPD induced by cigarette smoke (CS) exposure in mice.

METHODS

24 healthy male C57BL/6J mice aged 6 to 8 weeks were randomly divided into Smoke-Exposed (SE) group and Control group. The mice in SE group were exposed to 7 time points at 3, 7, 15, 30, 60, 90 and 120 days, while mice in control group were exposed to fresh room air, with 3 mice in each group. Lung function of mice was detected at different exposure time points, and the lung tissue sections were stained with HE to observe the lung histopathological changes of mice in each group, and the lung tissue morphological quantitative analysis was performed to evaluate the degree of emphysema. The content of inflammatory cytokines including IL-1β, IL-6 and TNF-α in the supernatant of BALF was detected by ELISA to evaluate the pulmonary inflammation of mice. The expression of sRAGE in BALF supernatant was detected by ELISA. BALF cell precipitates were classified and counted under light microscope.

RESULTS

After 90 days of exposure to cigarette smoke, the lung function of mice was significantly reduced, emphysema appeared significantly, and the expression of inflammatory cells and inflammatory cytokines in BALF was significantly increased (all P<0.05). sRAGE increased significantly in the early stage of CS exposure (7-15 days) compared with the control group, and the number of macrophages and levels of inflammatory cytokines in BALF also increased temporarily (P<0.05). With the gradual exposure of CS, sRAGE expression gradually decreased, and was significantly reduced after COPD formation compared with the control group.

CONCLUSION

In the process of the occurrence and development of chronic obstructive pulmonary disease induced by cigarette smoke exposure, the level of sRAGE in bronchoalveolar lavage fluid showed a dynamic change of first increase and then decrease. The expression of sRAGE increased in the early stage of smoke exposure and played a transient pro-inflammatory role. With long-term exposure to cigarette smoke, the inflammatory response is gradually aggravated in lung, and the expression of sRAGE is significantly decreased, and its reduction degree is closely related to the degree of reduced lung function and inflammation.

An In Vitro Study to Assess the Effect of Cigarette Smoke on Color Stability and Surface Roughness of 3D Printed, Milled, and Traditional Provisional Crown and Bridge Materials

Objectives To assess the influence of cigarette smoke (CS) on the color and surface roughness of 3D printed, milled, and traditionally fabricated provisional crown and bridge (PC&B) materials. Materials and methods 112 disc-shaped samples were made employing four techniques and materials (28 per group) to fabricate PC&B prostheses. Specimens were fabricated using standard protocols, such as 3D printing, milling, conventional bis-acrylic resin, and traditional autopolymerizing polymethyl methacrylate (PMMA) resin. After preliminary color and surface roughness recording, each group specimen was divided randomly into two subgroups (14 each). The artificial saliva acted as the storage media for the control group specimens for 30 days, and test group specimens were subjected to CS in a customized smoking chamber (10 minutes twice daily, for 30 minutes). Final color and surface roughness measurements were made. The change in color (∆E00) and surface roughness (∆Sa) were calculated, and the data was tabulated for analysis.  Statistical analysis One-way analysis of variance was used to analyze the change in color and surface roughness. Post-hoc Tukey HSD test was used for comparison between groups. Results The mean ΔE00 and ∆Sa were higher among groups exposed to CS than those exposed to artificial saliva. The maximum change in color was recorded in the autopolymerizing PMMA, whereas the 3D printed resins recorded the minimal change. The traditional bis-acrylic resin recorded the maximum mean surface roughness change, while the milled resin recorded the least change. Conclusions Within the study limitations, it can be inferred that when exposed to CS, 3D printed and milled PC&B materials have superior color stability and displayed less change in surface roughness when equated with traditional bis-acrylic and autopolymerizing PMMA resins.

Role of Receptor for Advanced Glycation End-Products in Endometrial Cancer: A Review

Endometrial cancer (EC) is the most common gynecological malignancy. EC is associated with metabolic disorders that may promote non-enzymatic glycation and activate the receptor for advanced glycation end-products (RAGE) signaling pathways. Thus, we assumed that RAGE and its ligands may contribute to EC. Of particular interest is the interaction between diaphanous-related formin 1 (Diaph1) and RAGE during the progression of human cancers. Diaph1 is engaged in the proper organization of actin cytoskeletal dynamics, which is crucial in cancer invasion, metastasis, angiogenesis, and axonogenesis. However, the detailed molecular role of RAGE in EC remains uncertain. In this review, we discuss epigenetic factors that may play a key role in the RAGE-dependent endometrial pathology. We propose that DNA methylation may regulate the activity of the RAGE pathway in the uterus. The accumulation of negative external factors, such as hyperglycemia, inflammation, and oxidative stress, may interfere with the DNA methylation process. Therefore, further research should take into account the role of epigenetic mechanisms in EC progression.

Ruxolitinib Has a Protective Effect on Ovarian and Endometrial Tissues in Diabetic Rats via STAT3 Pathway

Background: Hyperglycemia is associated with ovarian dysfunction. Advanced glycation end products (AGE) may affect ovarian function by binding to particular AGE receptors (RAGE). Hematopoiesis and immunological conditioning are both controlled by the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. Many JAK-STAT signaling inhibitors, including ruxolitinib, have been approved to treat inflammatory disorders. We aimed to examine the potential protective effect of ruxolitinib, on ovarian dysfunction by comparing biochemical, pro-inflammatory, and histological abnormalities in a diabetic rat model. Methods: 24 female Wistar albino rats were included in the study. Diabetes was induced by streptozotocin (STZ) in 16 rats. Group 1: control (no diabetes mellitus, n = 8), Group 2 (diabetic = 8, 1 mL/kg/day saline, 4 weeks), and Group 3 (diabetic, n = 8, 2 mg/kg/day ruxolitinib, 4 weeks). The animals were euthanized, and bilateral hysterectomy and ovariectomy were performed for histopathological examination. The levels of signal transducer and activator of transcription 3 (STAT3) in tissue supernatants were measured. Results: Endometrial gland, ovarian stromal, and ovarian follicle degeneration scores were higher in group 2 compared with group 3 at p < 0.001, whereas ovarian STAT3 level was significantly higher in group 2 compared with group 3 at p < 0.001. Conclusions: Ruxolitinib can be a promising candidate for providing endometrial and ovarian structure continuity by JAK-STAT inhibition in diabetes.

Pivotal role of AGE-RAGE axis in brain aging with current interventions

Brain aging is characterized by several structural, biochemical and molecular changes which can vary among different individuals and can be influenced by genetic, environmental and lifestyle factors. Accumulation of protein aggregates, altered neurotransmitter composition, low-grade chronic inflammation and prolonged oxidative stress have been shown to contribute to brain tissue damage. Among key metabolic byproducts, advanced glycation end products (AGEs), formed endogenously through non-enzymatic reactions or acquired directly from the diet or other exogenous sources, have been detected to accumulate in brain tissue, exerting detrimental effects on cellular structure and function, contributing to neurodegeneration and cognitive decline. Upon binding to signal transduction receptor RAGE, AGEs can initiate pro-inflammatory pathways, exacerbate oxidative stress and neuroinflammation, thus impairing neuronal function and cognition. AGE-RAGE signaling induces programmed cell death, disrupts the blood-brain barrier and promotes protein aggregation, further compromising brain health. In this review, we investigate the intricate relationship between the AGE-RAGE pathway and brain aging in order to detect affected molecules and potential targets for intervention. Reduction of AGE deposition in brain tissue either through novel pharmacological therapeutics, dietary modifications, and lifestyle changes, shows a great promise in mitigating cognitive decline associated with brain aging.

Skin autofluorescence and cause-specific mortality in a population-based cohort

We aimed to assess the association of SAF with cardiovascular mortality in the general population and the possible association between SAF with other disease-specific mortality rates. We evaluated 77,143 participants without known diabetes or cardiovascular disease. The cause of death was ascertained by the municipality database. The associations between SAF and all-cause mortality, cardiovascular mortality and cancer mortality were assessed with Cox proportional hazard analysis.After a median follow-up of 115 months, 1447 participants were deceased (1.9%). SAF and age-adjusted SAF-z score were higher in all mortality groups. Cox regression analysis revealed that the highest quartile of SAF was associated with increased odds of cardiovascular mortality, (HR) 12.6 (7.3-21.7) and after adjusting for age (HR 1.8 (1.0-3.2)). Significance was lost after additional adjustments for sex, smoking status, and BMI (HR 1.4 (0.8-2.5). For cancer-related mortality the highest quartile of SAF was associated with higher probability of mortality in all models (unadjusted HR 8.6 (6.6-11.3), adjusted for age HR 2.1 (1.6-2.8)), adjusted for age, sex, smoking status, and BMI HR 1.7 (1.3-2.4)). SAF is associated with all-cause mortality as well as cardiovascular and cancer-related mortality in the general population.

Glycation in the cardiomyocyte

Glycation is a protein post-translational modification that can occur on lysine and arginine residues as a result of a non-enzymatic process known as the Maillard reaction. This modification is irreversible, so the only way it can be removed is by protein degradation and replacement. Small reactive carbonyl species, glyoxal and methylglyoxal, are the primary glycating agents and are elevated in several conditions associated with an increased risk of cardiovascular disease, including diabetes, rheumatoid arthritis, smoking, and aging. Thus, how protein glycation impacts the cardiomyocyte is of particular interest, to both understand how these conditions increase the risk of cardiovascular disease and how glycation might be targeted therapeutically. Glycation can affect the cardiomyocyte through extracellular mechanisms, including RAGE-based signaling, glycation of the extracellular matrix that modifies the mechanical environment, and signaling from the vasculature. Intracellular glycation of the cardiomyocyte can impact calcium handling, protein quality control and cell death pathways, as well as the cytoskeleton, resulting in a blunted contractility. While reducing protein glycation and its impact on the heart has been an active area of drug development, multiple clinical trials have had mixed results and these compounds have not been translated to the clinic-highlighting the challenges of modulating myocyte glycation. Here we will review protein glycation and its effects on the cardiomyocyte, therapeutic attempts to reverse these, and offer insight as to the future of glycation studies and patient treatment.

Documento de consenso sobre tabaquismo y riesgo vascular

Consensus statement on smoking and vascular risk About 22% of the Spanish population are daily smokers. Men are more likely to smoke than women. In Spain, women between 15-25 years of age smoke as much or more than men. Every smoker should be assessed for: physical dependence on nicotine (Fagerström test), social and psychological dependence (Glover Nilsson test), level of motivation to quit (Richmond test), probability of therapy success (Henri-Mondor and Michael-Fiore tests), and stage of behavioral change development (Prochaska and DiClementi). Advice on smoking cessation is highly cost-effective and should always be provided. Smoking is an enhancer of cardiovascular risk because it acts as a pathogen agent in the development of arteriosclerosis and is associated with ischemic heart disease, stroke, and peripheral artery disease. Smoking increases the risk of chronic lung diseases (COPD) and is related to cancers of the lung, female genitalia, larynx, oropharynx, bladder, mouth, esophagus, liver and biliary tract, and stomach, among others. Combined oral contraceptives should be avoided in women smokers older than 35 years of age due to the risk of thromboembolism. In smoking cessation, the involvement of physicians, nurses, psychologists, etc. is important, and their multidisciplinary collaboration is needed. Effective pharmacological treatments for smoking cessation are available. Combined treatments are recommended when smoker's dependence is high. For individuals who are unable to quit smoking, a strategy based on tobacco damage management with a total switch to smokeless products could be a less dangerous alternative for their health than continuing to smoke.

Effect of advanced glycation end-products in a wide range of medical problems including COVID-19

Glycation is a physiological process that determines the aging of the organism, while in states of metabolic disorders it is significantly intensified. High concentrations of compounds such as reducing sugars or reactive aldehydes derived from lipid oxidation, occurring for example in diabetes, atherosclerosis, dyslipidemia, obesity or metabolic syndrome, lead to increased glycation of proteins, lipids and nucleic acids. The level of advanced glycation end-products (AGEs) in the body depends on rapidity of their production and the rate of their removal by the urinary system. AGEs, accumulated in the extracellular matrix of the blood vessels and other organs, cause irreversible changes in the biochemical and biomechanical properties of tissues. As a consequence, micro- and macroangiopathies appear in the system, and may contribute to the organ failure, like kidneys and heart. Elevated levels of AGEs also increase the risk of Alzheimer's disease and various cancers. In this paper, we propose a new classification due to modified amino acid residues: arginyl-AGEs, monolysyl-AGEs and lysyl-arginyl-AGEs and dilysyl-AGEs. Furthermore, we describe in detail the effect of AGEs on the pathogenesis of metabolic and old age diseases, such as diabetic complications, atherosclerosis and neurodegenerative diseases. We summarize the currently available data on the diagnostic value of AGEs and present the AGEs as a therapeutic goal in a wide range of medical problems, including SARS-CoV-2 infection and so-called long COVID.

The AGE-RAGE axis associates with chronic pulmonary diseases and smoking in the Rotterdam study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma associate with high morbidity and mortality. High levels of advanced glycation end products (AGEs) were found in tissue and plasma of COPD patients but their role in COPD and asthma is unclear.

METHODS

In the Rotterdam Study (n = 2577), AGEs (by skin autofluorescence (SAF)), FEV1 and lung diffusing capacity (DLCOc and DLCOc /alveolar volume [VA]) were measured. Associations of SAF with asthma, COPD, GOLD stage, and lung function were analyzed using logistic and linear regression adjusted for covariates, followed by interaction and stratification analyses. sRAGE and EN-RAGE associations with COPD prevalence were analyzed by logistic regression.

RESULTS

SAF associated with COPD prevalence (OR = 1.299 [1.060, 1.591]) but not when adjusted for smoking (OR = 1.106 [0.89, 1.363]). SAF associated with FEV1% predicted (β=-3.384 [-4.877, -1.892]), DLCOc (β=-0.212 [-0.327, -0.097]) and GOLD stage (OR = 4.073, p = 0.001, stage 3&4 versus 1). Stratified, the association between SAF and FEV1%predicted was stronger in COPD (β=-6.362 [-9.055, -3.670]) than non-COPD (β=-1.712 [-3.306, -0.118]). Association of SAF with DLCOc and DLCOc/VA were confined to COPD (β=-0.550 [-0.909, -0.191]; β=-0.065 [-0.117, -0.014] respectively). SAF interacted with former smoking and COPD prevalence for associations with lung function. Lower sRAGE and higher EN-RAGE associated with COPD prevalence (OR = 0.575[0.354, 0.931]; OR = 1.778[1.142, 2.768], respectively).

CONCLUSIONS

Associations between SAF, lung function and COPD prevalence were strongly influenced by smoking. SAF associated with COPD severity and its association with lung function was more prominent within COPD. These results fuel further research into interrelations and causality between SAF, smoking and COPD.

TAKE-HOME MESSAGE

Skin AGEs associated with prevalence and severity of COPD and lung function in the general population with a stronger effect in COPD, calling for further research into interrelations and causality between SAF, smoking and COPD.

A Potential Role for the Receptor for Advanced Glycation End-Products (RAGE) in the Development of Secondhand Smoke-Induced Chronic Sinusitis

Chronic sinusitis (CS) is characterized by sinonasal inflammation, mucus overproduction, and edematous mucosal tissue. CS impacts one in seven adults and estimates suggest up to 15% of the general U.S. population may be affected. This research sought to assess a potential role for receptors for advanced glycation end-products (RAGE), an inflammatory receptor expressed in tissues exposed to secondhand smoke (SHS). Human sinus tissue sections were stained for RAGE and S100s, common RAGE ligands. Wild-type mice and mice that over-express RAGE in sinonasal epithelium (RAGE TG) were maintained in room air (RA) or exposed to secondhand smoke (SHS) via a nose-only delivery system five days a week for 6 weeks. Mouse sections were stained for RAGE and tissue lysates were assayed for cleaved caspase 3, cytokines, or matrix metalloproteases. We discovered increased RAGE expression in sinus tissue following SHS exposure and in sinuses from RAGE TG mice in the absence of SHS. Cleaved caspase-3, cytokines (IL-1β, IL-3, and TNF-α), and MMPs (-9 and -13) were induced by SHS and in tissues from RAGE TG mice. These results expand the inflammatory role of RAGE signaling, a key axis in disease progression observed in smokers. In this relatively unexplored area, enhanced understanding of RAGE signaling during voluntary and involuntary smoking may help to elucidate potential therapeutic targets that may attenuate the progression of smoke-related CS.

Protein Advanced Glycation End Products and Their Implications in Pancreatic Cancer

Protein advanced glycation end products (AGE) formed by nonenzymatic glycation can disrupt the normal structure and function of proteins, and stimulate the receptor for AGEs (RAGE), triggering intricate mechanisms that are etiologically related to various chronic diseases, including pancreatic cancer. Many common risk factors of pancreatic cancer are the major sources for the formation of protein AGEs and glycative stress in the human body. Abnormal accumulation of protein AGEs can impair the cellular proteome and promote AGE-RAGE driven pro-inflammatory signaling cascades, leading to increased oxidative stress, protease resistance, protein dysregulation, transcription activity of STAT, NF-κB, and AP-1, aberrant status in ubiquitin-proteasome system and autophagy, as well as other molecular events that are susceptible for the carcinogenic transformation towards the development of neoplasms. Here, we review studies to highlight our understanding in the orchestrated molecular events in bridging the impaired proteome, dysregulated functional networks, and cancer hallmarks initiated upon protein AGE formation and accumulation in pancreatic cancer.

Follicular fluid advanced glycation end products in assisted reproduction: A systematic review

Follicular fluid (FF) advanced glycation end products (AGEs) have been associated with low oocyte quality and number, low fertilization rate, impaired embryonic development and low pregnancy rate. These findings are especially relevant in women undergoing in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), ie, assisted reproductive technology (ART). A systematic literature search was conducted to examine various AGEs including pentosidine, carboxymethyl-lysine (CML), methylglyoxal 5-hydro-5-methylimidazolones (MG-H1), toxic AGE (TAGE), and soluble receptor for AGE (sRAGE) with ART outcomes. Studies showed that total AGEs and sRAGE in FF were associated with the ovarian response, follicle number, retrieved oocyte number, mature (MII) oocyte number, fertilization rate, embryo number, embryo quality, and successful pregnancy. Although FF AGEs could be considered predictive biomarkers, population heterogeneity and differences in ovulation induction protocols make the findings less clear. This review highlights important role of AGEs in ART and necessity of evaluating AGEs in serum vs with FF to better predict ART outcomes.

Advanced glycation end products: Key mediator and therapeutic target of cardiovascular complications in diabetes

The incidence of type 2 diabetes mellitus is growing in epidemic proportions and has become one of the most critical public health concerns. Cardiovascular complications associated with diabetes are the leading cause of morbidity and mortality. The cardiovascular diseases that accompany diabetes include angina, myocardial infarction, stroke, peripheral artery disease, and congestive heart failure. Among the various risk factors generated secondary to hyperglycemic situations, advanced glycation end products (AGEs) are one of the important targets for future diagnosis and prevention of diabetes. In the last decade, AGEs have drawn a lot of attention due to their involvement in diabetic patho-physiology. AGEs can be derived exogenously and endogenously through various pathways. These are a non-homogeneous, chemically diverse group of compounds formed non-enzymatically by condensation between carbonyl groups of reducing sugars and free amino groups of protein, lipids, and nucleic acid. AGEs mediate their pathological effects at the cellular and extracellular levels by multiple pathways. At the cellular level, they activate signaling cascades via the receptor for AGEs and initiate a complex series of intracellular signaling resulting in reactive oxygen species generation, inflammation, cellular proliferation, and fibrosis that may possibly exacerbate the damaging effects on cardiac functions in diabetics. AGEs also cause covalent modifications and cross-linking of serum and extracellular matrix proteins; altering their structure, stability, and functions. Early diagnosis of diabetes may prevent its progression to complications and decrease its associated comorbidities. In the present review, we recapitulate the role of AGEs as a crucial mediator of hyperglycemia-mediated detrimental effects in diabetes-associated complications. Furthermore, this review presents an overview of future perspectives for new therapeutic interventions to ameliorate cardiovascular complications in diabetes.

Continuous low serum levels of advanced glycation end products and low risk of cardiovascular disease in patients with poorly controlled type 2 diabetes

BACKGROUND

Type 2 diabetes is associated with an increased risk of developing cardiovascular events. Previous studies have reported that advanced glycation end products (AGEs) were related to cardiovascular events in type 2 diabetes. However, data on associations between long-term AGEs and cardiovascular events in type 2 diabetes are lacking. This study aimed to determine whether a long-time shift in the levels of serum AGEs is associated with cardiovascular events in patients with poorly controlled type 2 diabetes.

METHODS

Two-time serum methyl-glyoxal-hydroimidazoline (MG-H1) levels were measured in 138 patients with type 2 diabetes whose mean glycated hemoglobin level was 10.1%. We categorized patients whose serum MG-H1 levels were < 2.8 µg/mL at both times as the continuous low MG-H1 group. The primary endpoints of this study were combined cardiovascular events, which were defined as heart disease, peripheral arterial disease, stroke, and all-cause death. Hazard ratios (HRs) for combined cardiovascular events with 95% confidence intervals (CIs) were calculated using the Cox proportional hazard models to compare the outcomes between the continuous low MG-H1 group and others.

RESULTS

The continuous low MG-H1 group was associated with a significantly lower risk than others in combined cardiovascular events after adjusting for possible confounders (HR: 0.50; 95% CI, 0.28-0.87; P = 0.02). Furthermore, the same relationship was observed in patients without a history of cardiovascular events.

CONCLUSIONS

Continuous low serum MG-H1 levels are associated with a low frequency of diabetes-related complications in patients with poorly controlled type 2 diabetes.

A Role for Advanced Glycation End Products in Molecular Ageing

Ageing is a composite process that involves numerous changes at the cellular, tissue, organ and whole-body levels. These changes result in decreased functioning of the organism and the development of certain conditions, which ultimately lead to an increased risk of death. Advanced glycation end products (AGEs) are a family of compounds with a diverse chemical nature. They are the products of non-enzymatic reactions between reducing sugars and proteins, lipids or nucleic acids and are synthesised in high amounts in both physiological and pathological conditions. Accumulation of these molecules increases the level of damage to tissue/organs structures (immune elements, connective tissue, brain, pancreatic beta cells, nephrons, and muscles), which consequently triggers the development of age-related diseases, such as diabetes mellitus, neurodegeneration, and cardiovascular and kidney disorders. Irrespective of the role of AGEs in the initiation or progression of chronic disorders, a reduction in their levels would certainly provide health benefits. In this review, we provide an overview of the role of AGEs in these areas. Moreover, we provide examples of lifestyle interventions, such as caloric restriction or physical activities, that may modulate AGE formation and accumulation and help to promote healthy ageing.

The AGE-RAGE Axis and the Pathophysiology of Multimorbidity in COPD

Chronic obstructive pulmonary disease (COPD) is a disease of the airways and lungs due to an enhanced inflammatory response, commonly caused by cigarette smoking. Patients with COPD are often multimorbid, as they commonly suffer from multiple chronic (inflammatory) conditions. This intensifies the burden of individual diseases, negatively affects quality of life, and complicates disease management. COPD and comorbidities share genetic and lifestyle-related risk factors and pathobiological mechanisms, including chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) is an important driver of chronic inflammation. Advanced glycation end products (AGEs) are RAGE ligands that accumulate due to aging, inflammation, oxidative stress, and carbohydrate metabolism. AGEs cause further inflammation and oxidative stress through RAGE, but also through RAGE-independent mechanisms. This review describes the complexity of RAGE signaling and the causes of AGE accumulation, followed by a comprehensive overview of alterations reported on AGEs and RAGE in COPD and in important co-morbidities. Furthermore, it describes the mechanisms by which AGEs and RAGE contribute to the pathophysiology of individual disease conditions and how they execute crosstalk between organ systems. A section on therapeutic strategies that target AGEs and RAGE and could alleviate patients from multimorbid conditions using single therapeutics concludes this review.

Trends in metabolic indicators and microvascular complications in Chinese adults with newly diagnosed type 2 diabetes: A retrospective, single-centre study of twenty-years

BACKGROUND

The purpose of this study is to assess metabolic indicators and trends in microvascular complications among Chinese adults with newly diagnosed type 2 diabetes during 2000-2020.

METHODS

3,907 patients were included and divided into three groups according to a time period of 7 years. This study analyzed trends in proportions of patients reached therapeutic targets of blood glucose, pressure and lipids, and trends in albuminuria, retinopathy, and peripheral neuropathy.

RESULTS

In the past 20 years, the age of adults with newly diagnosed type 2 diabetes tended to be younger, and the proportion of female patients increased. There seemed no improvements in blood glucose and pressure. The rate of awareness and treatment on target of hypertension was less than 50%. There was a significant decrease in the prevalence of retinopathy, but no changes in nephropathy or peripheral neuropathy. Complications were more common for patients who were smoker, male, or with hypertension and obesity.

CONCLUSIONS

Over the past two decades, there have been encouraging reductions in retinopathy in Chinese adults with newly diagnosed diabetes, but no significant change in albuminuria and peripheral neuropathy. It may be related to the low awareness of diabetes and insufficient controlled blood glucose, pressure and lipids on target.

Blood and Tissue Advanced Glycation End Products as Determinants of Cardiometabolic Disorders Focusing on Human Studies

Cardiometabolic disorders are characterised by a cluster of interactive risk determinants such as increases in blood glucose, lipids and body weight, as well as elevated inflammation and oxidative stress and gut microbiome changes. These disorders are associated with onset of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). T2DM is strongly associated with CVD. Dietary advanced glycation end products (dAGEs) attributable from modern diets high in sugar and/or fat, highly processed foods and high heat-treated foods can contribute to metabolic etiologies of cardiometabolic disorders. This mini review aims to determine whether blood dAGEs levels and tissue dAGEs levels are determinants of the prevalence of cardiometabolic disorders through recent human studies. ELISA (enzyme-linked immunosorbent assay), high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) for blood dAGEs measurement and skin auto fluorescence (SAF) for skin AGEs measurement can be used. Recent human studies support that a diet high in AGEs can negatively influence glucose control, body weight, blood lipid levels and vascular health through the elevated oxidative stress, inflammation, blood pressure and endothelial dysfunction compared with a diet low in AGEs. Limited human studies suggested a diet high in AGEs could negatively alter gut microbiota. SAF could be considered as one of the predictors affecting risks for cardiometabolic disorders. More intervention studies are needed to determine how dAGEs are associated with the prevalence of cardiometabolic disorders through gut microbiota changes. Further human studies are conducted to find the association between CVD events, CVD mortality and total mortality through SAF measurement, and a consensus on whether tissue dAGEs act as a predictor of CVD is required.

Oxidative Stress Biomarkers among Schizophrenia Inpatients

Background. Finding the associations between schizophrenia symptoms and the biomarkers of inflammation, oxidative stress and the kynurenine pathway may lead to the individualization of treatment and increase its effectiveness. Methods. The study group included 82 schizophrenia inpatients. The Positive and Negative Symptoms Scale (PANSS), the Brief Assessment of Cognition in Schizophrenia (BACS) and the Calgary Depression in Schizophrenia Scale were used for symptom evaluation. Biochemical analyses included oxidative stress parameters and brain-derived neurotrophic factor (BDNF). Results. Linear models revealed the following: (1) malondiadehyde (MDA), N-formylkynurenine (N-formKYN), advanced oxidation protein products (AOPP), advanced glycation end-products of proteins (AGE) and total oxidative status (TOS) levels are related to the PANSS-total score; (2) MDA, reduced glutathione (GSH) and BDNF levels are related to the PANSS-negative score; (3) TOS and kynurenine (KYN) levels are related to the PANSS-positive score; (4) levels of total antioxidant status (TAS) and AOPP along with the CDSS score are related to the BACS-total score; (5) TAS and N-formKYN levels are related to the BACS-working memory score. Conclusions. Oxidative stress biomarkers may be associated with the severity of schizophrenia symptoms in positive, negative and cognitive dimensions. The identification of biochemical markers associated with the specific symptom clusters may increase the understanding of biochemical profiles in schizophrenia patients.

Determination of the effects of advanced glycation end products receptor polymorphisms and its activation on structural cell responses and inflammation in asthma

BACKGROUND

Advanced glycation end products receptor (RAGE) is a pattern recognition receptor which attracted attention in chronic airway diseases recently. This study aimed to determine the association of RAGE with asthma and the cellular responses resulting from RAGE signaling pathway activation.

METHODS

Asthmatic (n = 362) and healthy (n = 134) children were genotyped by PCR-RFLP. Plasma sRAGE levels were determined by ELISA. Lung structural cells were stimulated with AGEs (advanced glycation end products) and control BSA. Expressions of cytokines and protein levels were determined by real-time PCR and ELISA.

RESULTS

: Gly82Ser and -374 T/A polymorphisms in RAGE gene were associated with lower plasma sRAGE levels (p < 0.001 and p < 0.025, respectively). AGE stimulation increased the expression of RAGE (p = 0.002), ICAM-1 (p = 0.010) and VCAM-1 (p = 0.002) in endothelial cells; TIMP-1 (p = 0.003) and MCP-1 (p = 0.005) in fibroblasts. AGE stimulation increased protein levels of IL-6 (p < 0.001) in endothelial cells; VEGF (p = 0.025) and IL-8 (p < 0.001) in fibroblasts; IL-1b (p < 0.001) and VEGF (p = 0.007) in epithelial cells.

DISCUSSION

Activation of RAGE pathway may contribute to asthma pathogenesis by increasing the expression of several asthmarelated genes. These findings suggest that suppression of RAGE signaling may be an alternative candidate for treating asthma.

The receptor for advanced glycation end products (RAGE) is involved in mitochondrial function and cigarette smoke-induced oxidative stress

The mechanisms underlying muscle dysfunction with Chronic Obstructive Pulmonary Disease (COPD) are poorly understood. Indirect evidence has recently suggested a role of Advanced Glycation End Products (AGEs) and their receptor (RAGE) in the pathophysiology of COPD. Accordingly, this study aimed to examine the redox balance and mitochondrial alterations in the skeletal muscle of a mouse model deficient in the receptor for AGE (RAGE-KO) and wild-type C57BL/6 exposed to cigarette smoke for 8-months using immunoblotting, spectrophotometry, and high-resolution respirometry. Cigarette smoke exposure increased by two-fold 4-HNE levels (P < 0.001), a marker of oxidative stress, and markedly downregulated contractile proteins, mitochondrial respiratory complexes, and uncoupling proteins levels (P < 0.001). Functional alterations with cigarette smoke exposure included a greater reliance on complex-I supported respiration (P < 0.01) and lower relative respiratory capacity for fatty acid (P < 0.05). RAGE knockout resulted in 47% lower 4-HNE protein levels than the corresponding WT control mice exposed to cigarette smoke (P < 0.05), which was partly attributed to increased Complex III protein levels. Independent of cigarette smoke exposure, RAGE KO decreased mitochondrial specific maximal respiration (P < 0.05), resulting in a compensatory increase in mitochondrial content measured by citrate synthase activity (P < 0.001) such that muscle respiratory capacity remained unaltered. Together, these findings suggest that knockout of RAGE protected the skeletal muscle against oxidative damage induced by 8 months of cigarette smoke exposure. In addition, this study supports a role for RAGE in regulating mitochondrial content and function and can thus serve as a potential therapeutic target.

Advanced Glycation End-Products and Their Effects on Gut Health

Dietary advanced glycation end-products (AGEs) are a heterogeneous group of compounds formed when reducing sugars are heated with proteins, amino acids, or lipids at high temperatures for a prolonged period. The presence and accumulation of AGEs in numerous cell types and tissues are known to be prevalent in the pathology of many diseases. Modern diets, which contain a high proportion of processed foods and therefore a high level of AGE, cause deleterious effects leading to a multitude of unregulated intracellular and extracellular signalling and inflammatory pathways. Currently, many studies focus on investigating the chemical and structural aspects of AGEs and how they affect the metabolism and the cardiovascular and renal systems. Studies have also shown that AGEs affect the digestive system. However, there is no complete picture of the implication of AGEs in this area. The gastrointestinal tract is not only the first and principal site for the digestion and absorption of dietary AGEs but also one of the most susceptible organs to AGEs, which may exert many local and systemic effects. In this review, we summarise the current evidence of the association between a high-AGE diet and poor health outcomes, with a special focus on the relationship between dietary AGEs and alterations in the gastrointestinal structure, modifications in enteric neurons, and microbiota reshaping.

Fluorescent advanced glycation end products in type 2 diabetes and its association with diabetes duration, hemoglobin A1c, and diabetic complications

Background

Fluorescent advanced glycation end products (fAGEs) are generated through the Maillard reaction between reducing sugars and amino compounds. fAGEs accumulation in human bodies have been confirmed to be related to many chronic diseases. To date, the correlations between serum fAGEs levels and clinical parameters or carotid intima media thickness (CIMT) in patients with T2DM remain unclear. Thus, this study aimed to investigate the relationship between serum AGEs levels and clinical parameters or CIMT in patients with T2DM.

Method

A total of 131 patients with diabetes and 30 healthy controls were enrolled. Patients were divided into three groups according to diabetes duration, including ≤5, 5-10, and ≥10 years. Serum fAGEs, protein oxidation products, clinical parameters, and CIMT were determined.

Results

The result showed that levels of fAGEs and protein oxidation products increased with the increasing duration of diabetics. Pearson correlation coefficients of fAGEs versus hemoglobin A1c (HbA1c) were >0.5 in patients with diabetes duration ≥10 years. A continued increase in fAGEs might cause the increase of HbA1c, urinary albumin/creatinine ratio (UACR) and CIMT in patients with T2DM.

Conclusion

Our study suggested that levels of fAGEs could be considered as an indicator for duration of diabetics and carotid atherosclerosis. Diabetes duration and smoking might have a synergistic effect on the increment of fAGEs levels, as evidence by the results of correlation analysis in patients with long-duration diabetics (≥10 years) and smoking. The determination of fAGEs might be helpful to advance our knowledge on the overall risk of complications in patients with T2DM.

Dietary advanced glycation end-products (dAGEs) intake and its relation to sarcopenia and frailty - The Rotterdam Study

Studies on mice have shown a relationship between dietary intake of advanced glycation end-products (dAGEs) and deterioration of musculoskeletal health, but human studies are absent. We investigated the relationship between dietary intake of carboxymethyllysine (dCML) - an AGE prototype - and risk of sarcopenia at baseline and after 5 years of follow-up and a single evaluation of physical frailty in participants from the population-based Rotterdam Study. Appendicular lean mass (ALM) was obtained using insight dual-energy X-ray absorptiometry and hand grip strength (HGS) using a hydraulic hand dynamometer. Subjects with both low ALM and weak HGS were classified as having sarcopenia. Frailty (yes/no) was defined by presence of ≥3 and pre-frailty by presence of 1 or 2 components namely, exhaustion, weakness, slowness, weight loss or low physical activity. dCML was calculated using a food frequency questionnaire and dAGE databases. Logistic regression analysis was used to evaluate the odds of physical frailty and prevalent sarcopenia at baseline and follow-up and incident sarcopenia. 2782 participants with an age 66.4 ± 9.9 years and dCML intake 3.3 ± 1.3 mg/day, had data on sarcopenia at both time points. Of whom 84 had sarcopenia at baseline and 73 developed sarcopenia at follow-up. We observed an association of one SD increase in dCML intake with prevalent sarcopenia at baseline [odds ratio, OR = 1.27 (1.01-1.59)] and no association of dCML with incident sarcopenia at 5-year follow-up [OR = 1.12 (0.86-1.44)]. For frailty we analyzed 3577 participants, of whom 1972 were pre-frail and 158 were frail. We observed no association of dCML with either pre-frailty [OR = 0.99 (0.91-1.07)] or frailty [OR = 1.01 (0.83-1.22)] when non-frail subjects were used as reference. Our results show an association of dAGEs with sarcopenia cross-sectionally but not longitudinally where inconclusive findings are observed possibly due to a very low incidence of sarcopenia. There was no association with frailty cross-sectionally.

Methylglyoxal - an advanced glycation end products (AGEs) precursor - Inhibits differentiation of human MSC-derived osteoblasts in vitro independently of receptor for AGEs (RAGE)

A major precursor of advanced glycation end-products (AGEs) - methylglyoxal (MG) - is a reactive carbonyl metabolite that originates from glycolytic pathways. MG formation and accumulation has been implicated in the pathogenesis of diabetes and age-related chronic musculoskeletal disorders. Human bone marrow-derived stromal cells (BMSCs) are multipotent cells that have the potential to differentiate into cells of mesenchymal origin including osteoblasts, but the role of MG on their differentiation is unclear. We therefore evaluated the effect of MG on proliferation and differentiation of BMSC-derived osteoblasts. Cells were treated with different concentrations of MG (600, 800 and 1000 μM). Cell viability was assessed using a Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) activity and calcium deposition assays were performed to evaluate osteoblast differentiation and mineralization. Gene expression was measured using qRT-PCR, whereas AGE specific receptor (RAGE) and collagen 1 were examined by immunocytochemistry and Western blotting. RAGE knockdown was performed by transducing RAGE specific short hairpin RNAs (shRNAs) using lentivirus. During osteogenic differentiation, MG treatment resulted in reduction of cell viability (27.7 %), ALP activity (45.5 %) and mineralization (82.3 %) compared to untreated cells. MG significantly decreased expression of genes involved in osteogenic differentiation - RUNX2 (2.8 fold), ALPL (3.2 fold), MG detoxification through glyoxalase - GLO1 (3 fold) and collagen metabolism - COL1A1 (4.9 fold), COL1A2 (6.8 fold), LOX (5.4 fold) and PLOD1 (1.7 fold). MG significantly reduced expression of collagen 1 (53.3 %) and RAGE (43.1 %) at protein levels. Co-treatment with a MG scavenger - aminoguanidine - prevented all negative effects of MG. RAGE-specific knockdown during MG treatment did not reverse the effects on cell viability, osteogenic differentiation or collagen metabolism. In conclusion, MG treatment can negatively influence the collagen metabolism and differentiation of BMSCs-derived osteoblasts through a RAGE independent mechanism.

Glycation-Associated Diabetic Nephropathy and the Role of Long Noncoding RNAs

The glycation of various biomolecules is the root cause of many pathological conditions associated with diabetic nephropathy and end-stage kidney disease. Glycation imbalances metabolism and increases renal cell injury. Numerous therapeutic measures have narrowed down the adverse effects of endogenous glycation, but efficient and potent measures are miles away. Recent advances in the identification and characterization of noncoding RNAs, especially the long noncoding RNAs (lncRNAs), have opened a mammon of new biology to explore the mitigations for glycation-associated diabetic nephropathy. Furthermore, tissue-specific distribution and condition-specific expression make lncRNA a promising key for second-generation therapeutic interventions. Though the techniques to identify and exemplify noncoding RNAs are rapidly evolving, the lncRNA study encounters multiple methodological constraints. This review will discuss lncRNAs and their possible involvement in glycation and advanced glycation end products (AGEs) signaling pathways. We further highlight the possible approaches for lncRNA-based therapeutics and their working mechanism for perturbing glycation and conclude our review with lncRNAs biology-related future opportunities.

Advanced Glycation End Products, Bone Health, and Diabetes Mellitus

Advanced glycation end products (AGEs), the compounds resulting from the non-enzymatic glycosylation between reducing sugars and proteins, are derived from food or produced de novo. Over time, more and more endogenous and exogenous AGEs accumulate in various organs such as the liver, kidneys, muscle, and bone, threatening human health. Among these organs, bone is most widely reported. AGEs accumulating in bone reduce bone strength by participating in bone structure formation and breaking bone homeostasis by binding their receptors to alter the proliferation, differentiation, and apoptosis of cells involved in bone remodeling. In this review, we summarize the research about the effects of AGEs on bone health and highlight their associations with bone health in diabetes patients to provide some clues toward the discovery of new treatment and prevention strategies for bone-related diseases caused by AGEs.

The Bright Side of Skin Autofluorescence Determination in Children and Adolescents with Newly Diagnosed Type 1 Diabetes Mellitus: A Potential Predictor of Remission?

Skin autofluorescence (SAF) is a noninvasive method reflecting tissue accumulation of advanced glycation end products (AGEs). We investigated whether, in newly diagnosed children and adolescents with type 1 diabetes (T1D), this surrogate marker of long-term glycemia is associated with markers of the early manifestation phase, residual secretion capacity of the ß-cells, and the occurrence of remission. SAF was measured in 114 children and adolescents (age: 8.0 ± 4.5 years, 44% girls) at the time of T1D diagnosis, and related to HbA1c, C-peptide, diabetic ketoacidosis, and remission. 56 patients were followed up for 1 year. Seventy-four sex- and age-matched healthy individuals served as controls. SAF was higher in the T1D group compared with controls (1.0 ± 0.2 vs. 0.9 ± 0.2, p < 0.001). At the time of diagnosis, SAF correlated with HbA1c (r = 0.285, p = 0.002), was similar in patients with and without ketoacidosis, and was lower in the remitters compared with non-remitters (0.95 ± 0.18 vs. 1.04 ± 0.26, p = 0.027). Unlike HbA1c, SAF was an independent predictor of remission (∆R² = 0.051, p = 0.004). Former studies consider SAF in diabetic patients as a tool to identify individuals at an increased risk of chronic complications. Here we show that determination of SAF at the time of T1D diagnosis might potentially predict remission, at least in children.

Contribution of Advanced Glycation End Products to PCOS Key Elements: A Narrative Review

In the last decade, data has suggested that dietary advanced glycation end products (AGEs) play an important role in both reproductive and metabolic dysfunctions associated with polycystic ovary syndrome (PCOS). AGEs are highly reactive molecules that are formed by the non-enzymatic glycation process between reducing sugars and proteins, lipids, or nucleic acids. They can be formed endogenously under normal metabolic conditions or under abnormal situations such as diabetes, renal disease, and other inflammatory disorders. Bodily AGEs can also accumulate from exogenous dietary sources particularly when ingested food is cooked and processed under high-temperature conditions, such as frying, baking, or grilling. Women with PCOS have elevated levels of serum AGEs that are associated with insulin resistance and obesity and that leads to a high deposition of AGEs in the ovarian tissue causing anovulation and hyperandrogenism. This review will describe new data relevant to the role of AGEs in several key elements of PCOS phenotype and pathophysiology. Those elements include ovarian dysfunction, hyperandrogenemia, insulin resistance, and obesity. The literature findings to date suggest that targeting AGEs and their cellular actions could represent a novel approach to treating PCOS symptoms.

Effects of conventional and heated tobacco product smoking on discoloration of artificial denture teeth

STATEMENT OF PROBLEM

Cigarette smoke can cause discoloration of artificial denture teeth. However, studies on the effects of heated tobacco product smoke on artificial denture teeth are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the effects of conventional cigarette and heated tobacco product smoke on the color stability of artificial denture teeth.

MATERIAL AND METHODS

Ninety maxillary central incisor denture teeth (Endura Anterior HC5 A3; Shofu) were randomly divided into 3 groups (n=30). Teeth in the control group were exposed to air; those in group CC were exposed to conventional cigarette (Marlboro Medium; Philip Morris) smoke, and those in group HT were exposed to heated tobacco product (IQOS 2.4 plus holder, Marlboro Heets Silver; Philip Morris) smoke. Before the experiment, the shade of the artificial denture teeth was evaluated in accordance with the Commission International de I'Eclairage (CIELab) color system by using a spectrophotometer (Shadepilot; DeguDent GmbH). The average CIELab value was estimated by scanning the entire labial surface of each specimen. To simulate smoking, standard conditions described by the Coresta Recommended Method N°22 were used-the puff duration was 2 seconds, with a 60-second interval between puffs. For each cigarette, 6 puffs and 6 intervals were simulated across 372 seconds. A total of 105 cigarettes were used based on a smoking simulation of 15 cigarettes each day for 7 days. The teeth in the control group were stored in fresh air in the smoke chamber for the same period as those in the experimental groups. After the experiment, L∗, a∗, and b∗ values were measured, and ΔE was calculated to evaluate the color change. All statistical analyses were performed with a statistical software program using a paired t test to determine discoloration after exposure to cigarette smoke. One-way ANOVA and the Tukey test were used to evaluate the significant differences between groups (α=.05).

RESULTS

Lightness was significantly lower in the CC and HT groups (P<.001). All CIELab values showed statistically significant differences in the CC group. The greatest color change was observed in the CC group (ΔE=6.93 ±0.59), whereas the HT group showed a clinically imperceptible color change (ΔE=0.79 ±0.21). Discoloration was minimal in the CC group (ΔE=0.34 ±0.13).

CONCLUSIONS

Conventional cigarette and heated tobacco product smoke can change the color of denture teeth. Heated tobacco product smoke causes less discoloration of denture teeth.

Pathophysiology of RAGE in inflammatory diseases

The receptor for advanced glycation end products (RAGE) is a non-specific multi-ligand pattern recognition receptor capable of binding to a range of structurally diverse ligands, expressed on a variety of cell types, and performing different functions. The ligand-RAGE axis can trigger a range of signaling events that are associated with diabetes and its complications, neurological disorders, cancer, inflammation and other diseases. Since RAGE is involved in the pathophysiological processes of many diseases, targeting RAGE may be an effective strategy to block RAGE signaling.

Endophytes, a Potential Source of Bioactive Compounds to Curtail the Formation–Accumulation of Advanced Glycation End Products: A Review

Endophytes, microorganisms that live in the internal tissues and organs of the plants, are known to produce numerous bioactive compounds, including, at times, some phytochemicals of their host plant. For such reason, endophytes have been quoted as a potential source for discovering bioactive compounds, particularly, of medical interest. Currently, many non-communicable diseases are threatening global human health, noticeably: diabetes, neurodegenerative diseases, cancer, and other ailment related to chronic inflammation and ageing. Intriguingly, the pathogenesis and development of these diseases have been linked to an excessive formation and accumulation of advanced glycation end products (AGEs). AGEs are a heterogeneous group of compounds that can alter the conformation, function, and lifetime of proteins. Therefore, compounds that prevent the formation and consequent accumulation of AGEs (AntiAGEs compounds) could be useful to delay the progress of some chronic diseases, and/or harmful effects of undue AGEs accumulation. Despite the remarkable ability of endophytes to produce bioactive compounds, most of the natural antiAGEs compounds reported in the literature are derived from plants. Accordingly, this work covers 26 plant antiAGEs compounds and some derivatives that have been reported as endophytic metabolites, and discusses the importance, possible advantages, and challenges of using endophytes as a potential source of antiAGEs compounds.

Perceived facial age and biochemical indicators of glycemia in adult men and women

Glycemia is linked with one of the key mechanisms underlying the aging process and inter-individual differences in biological age. Previous research showed that glucose level is linked with perceived age in elder individuals. This study aimed to verify if glycemia is related to perceived facial age in healthy adult individuals as interventions in younger and healthy cohorts are crucial for preventing the onset of age-related diseases. The study sample consisted of 116 healthy men of mean age 35.53 ± 3.54 years (29.95–44.29) and 163 healthy women of mean age 28.38 ± 2.40 (24.25–34.17) years. Glycemia was evaluated by fasting glucose, insulin, HOMA-IR, and glycated hemoglobin level. BMI, facial sexual dimorphism, estradiol, testosterone, and hsCRP levels were controlled. Perceived age was evaluated based on standardized facial photos in an online survey. Additionally perceived facial aging was calculated as a difference between perceived age and chronological age. No relationship between the levels of biochemical indicators of glycemia and perceived facial age or aging was found both in men and women, also when controlled for possible confounders. This study shows that perceived facial age in adult individuals is rather linked with body adiposity of sexual dimorphism but not with glycemic markers.

Advanced Glycation End Products in the Skin: Molecular Mechanisms, Methods of Measurement, and Inhibitory Pathways

Advanced glycation end products (AGEs) are a series of stable compounds produced under non-enzymatic conditions by the amino groups of biomacromolecules and the free carbonyl groups of glucose or other reducing sugars commonly produced by thermally processed foods. AGEs can cause various diseases, such as diabetes, atherosclerosis, neurodegeneration, and chronic kidney disease, by triggering the receptors of AGE (RAGEs) in the human body. There is evidence that AGEs can also affect the different structures and physiological functions of the skin. However, the mechanism is complicated and cumbersome and causes various harms to the skin. This article aims to identify and summarise the formation and characteristics of AGEs, focussing on the molecular mechanisms by which AGEs affect the composition and structure of normal skin substances at different skin layers and induce skin issues. We also discuss prevention and inhibition pathways, provide a systematic and comprehensive method for measuring the content of AGEs in human skin, and summarise and analyse their advantages and disadvantages. This work can help researchers acquire a deeper understanding of the relationship between AGEs and the skin and provides a basis for the development of effective ingredients that inhibit glycation.

Dietary Advanced Glycation End Products in an Elderly Population with Diabetic Nephropathy: An Exploratory Investigation

Advanced glycation end products (AGEs) are important in pathophysiology of type 2 diabetes mellitus (T2DM) and diabetic kidney disease (DKD). Dietary AGEs (dAGEs) contribute to the overall AGE pool in the body. Forty elderly T2DM patients with DKD were randomly allocated to a low-AGE (n = 20) or regular diabetic (n = 20) diet group. A three-day meal questionnaire was used to estimate average quantity of dAGEs. AGE accumulation was measured using skin autofluorescence and urine spectroscopy. sRAGE (soluble receptor AGE) was quantified using ELISA. After 8 weeks, the mean consumption of dAGEs was considerably reduced, both in the low-AGE diet (p = 0.004) and the control (p = 0.019) group. The expected urinary emission peak at 490 nm was shifted to 520 nm in some spectra. dAGEs did not correspond with urine AGE output. An AGE-limited diet for two months did not affect AGE content in skin and urine, or sRAGE concentration in the blood. The role of glycemia is likely to be greater than the impact of dAGE consumption. The unique observation of a fluorescence pattern at 520 nm warrants further examination, since it might point to genetic differences in AGE regulation, which could have clinical consequences, as AGE content depends on its formation and elimination.

RAGE signaling during tobacco smoke-induced lung inflammation and potential therapeutic utility of SAGEs

BACKGROUND

Smoke exposure culminates as a progressive lung complication involving airway inflammation and remodeling. While primary smoke poses the greatest risk, nearly half of the US population is also at risk due to exposure to secondhand smoke (SHS).

METHODS

We used WT, RAGE-/- (KO), and Tet-inducible lung-specific RAGE overexpressing transgenic (TG) mice to study the role of RAGE during short-term responses to SHS. We evaluated SHS effects in mice with and without semi-synthetic glycosaminoglycan ethers (SAGEs), which are anionic, partially lipophilic sulfated polysaccharide derivatives known to inhibit RAGE signaling. TG Mice were weaned and fed doxycycline to induce RAGE at postnatal day (PN) 30. At PN40, mice from each line were exposed to room air (RA) or SHS from three Kentucky 3R4F research cigarettes via a nose-only delivery system (Scireq Scientific, Montreal, Canada) five days a week and i.p. injections of PBS or SAGE (30 mg/kg body weight) occurred three times per week from PN40-70 before mice were sacrificed on PN70.

RESULTS

RAGE mRNA and protein expression was elevated following SHS exposure of control and TG mice and not detected in RAGE KO mice. Bronchoalveolar lavage fluid (BALF) analysis revealed RAGE-mediated influence on inflammatory cell diapedesis, total protein, and pro-inflammatory mediators following exposure. Lung histological assessment revealed indistinguishable morphology following exposure, yet parenchymal apoptosis was increased. Inflammatory signaling intermediates such as Ras and NF-κB, as well as downstream responses were influenced by the availability of RAGE, as evidenced by RAGE KO and SAGE treatment.

CONCLUSIONS

These data provide fascinating insight suggesting therapeutic potential for the use of RAGE inhibitors in lungs exposed to SHS smoke.

Advanced Glycation End-Products (AGEs): Formation, Chemistry, Classification, Receptors, and Diseases Related to AGEs

Advanced glycation end-products (AGEs) constitute a non-homogenous, chemically diverse group of compounds formed either exogeneously or endogeneously on the course of various pathways in the human body. In general, they are formed non-enzymatically by condensation between carbonyl groups of reducing sugars and free amine groups of nucleic acids, proteins, or lipids, followed by further rearrangements yielding stable, irreversible end-products. In the last decades, AGEs have aroused the interest of the scientific community due to the increasing evidence of their involvement in many pathophysiological processes and diseases, such as diabetes, cancer, cardiovascular, neurodegenerative diseases, and even infection with the SARS-CoV-2 virus. They are recognized by several cellular receptors and trigger many signaling pathways related to inflammation and oxidative stress. Despite many experimental research outcomes published recently, the complexity of their engagement in human physiology and pathophysiological states requires further elucidation. This review focuses on the receptors of AGEs, especially on the structural aspects of receptor-ligand interaction, and the diseases in which AGEs are involved. It also aims to present AGE classification in subgroups and to describe the basic processes leading to both exogeneous and endogeneous AGE formation.

Impact of Dietary Advanced Glycation End Products on Female Reproduction: Review of Potential Mechanistic Pathways

Advanced glycation end products (AGEs), a heterogenous group of products formed by the reaction between protein and reducing sugars, can form endogenously due to non-enzymatic reactions or by exogenous sources such as diet where considerable increase in AGEs is observed due to the modification of food mainly by thermal processing. Recent studies have suggested that AGEs could impact, via inducing inflammation and oxidative stress, the reproductive health and fertility in both males and females. This review presents a summary of recently published data pertaining to the pathogenesis of dietary AGEs and their receptors as well as their potential impact on female reproductive health. More specifically, it will present data pertaining to dietary AGEs’ involvement in the mechanistic pathogenesis of polycystic ovary syndrome, ovarian dysfunction, as well as the AGEs’ effect perinatally on the female offspring reproduction. Understanding the mechanistic impact of dietary AGEs on female reproduction can help contribute to the development of targeted pharmacological therapies that will help curb rising female infertility.