The association between dietary and skin advanced glycation end products: the Rotterdam Study

Association between advanced glycation end-products and fall risk in older adults: The Yakumo Study

AIM

Advanced glycation end-products (AGEs) are irreversibly and heterogeneously formed compounds during the non-enzymatic modification of macromolecules, such as proteins. Aging and lifestyle habits, such as high-fat and high-protein diets, and smoking, promote AGEs accumulation. This study aimed to investigate the relationship between fall risk and AGEs in community-dwelling older adults.

METHODS

This cross-sectional study included patients from the 2022 Yakumo Study who were evaluated for fall risk index 5-items version, locomotive syndrome stage and AGEs. AGEs were evaluated using Skin autofluorescence (SAF) measured by the AGE reader (DiagnOptics Technologies BV, Groningen, the Netherlands). We divided the participants into two groups according to the presence or absence of fall risk (fall risk index 5-items version ≥6 or not), and investigated the factors associated with fall risk.

RESULTS

The fall risk group had a higher age and SAF, and a higher proportion of locomotive syndrome stage >2 than the without fall risk group in patients aged ≥65 years (P < 0.01). The multivariate logistic regression analysis after adjustment of age, sex and body mass index showed that locomotive syndrome stage ≥2 and SAF were independent associators of fall risk in older adults (odds ratio 3.26, P < 0.01, odds ratio 2.96, P < 0.05, respectively). The optimal cutoff value of the SAF for fall risk was 2.4 (area under the curve 0.631; 95% CI 0.53-0.733; sensitivity 0.415; specificity 0.814; P < 0.05).

CONCLUSION

The accumulation of AGEs in skin tissues can be used to screen for fall risk comprehensively. Geriatr Gerontol Int 2024; 24: 517-522.

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

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

Natural autophagy activators: A promising strategy for combating photoaging

BACKGROUND

Photodamage to the skin stands out as one of the most widespread epidermal challenges globally. Prolonged exposure to sunlight containing ultraviolet radiation (UVR) instigates stress, thereby compromising the skin's functionality and culminating in photoaging. Recent investigations have shed light on the importance of autophagy in shielding the skin from photodamage. Despite the acknowledgment of numerous phytochemicals possessing photoprotective attributes, their potential to induce autophagy remains relatively unexplored.

PURPOSE

Diminished autophagy activity in photoaged skin underscores the potential benefits of restoring autophagy through natural compounds to enhance photoprotection. Consequently, this study aims to highlight the role of natural compounds in safeguarding against photodamage and to assess their potential to induce autophagy via an in-silico approach.

METHODS

A thorough search of the literature was done using several databases, including PUBMED, Science Direct, and Google Scholar, to gather relevant studies. Several keywords such as Phytochemical, Photoprotection, mTOR, Ultraviolet Radiation, Reactive oxygen species, Photoaging, and Autophagy were utilized to ensure thorough exploration. To assess the autophagy potential of phytochemicals through virtual screening, computational methodologies such as molecular docking were employed, utilizing tools like AutoDock Vina. Receptor preparation for docking was facilitated using MGLTools.

RESULTS

The initiation of structural and functional deterioration in the skin due to ultraviolet radiation (UVR) or sunlight-induced reactive oxygen species/reactive nitrogen species (ROS/RNS) involves the modulation of various pathways. Natural compounds like phenolics, flavonoids, flavones, and anthocyanins, among others, possess chromophores capable of absorbing light, thereby offering photoprotection by modulating these pathways. In our molecular docking study, these phytochemicals have shown binding affinity with mTOR, a negative regulator of autophagy, indicating their potential as autophagy modulators.

CONCLUSION

This integrated review underscores the photoprotective characteristics of natural compounds, while the in-silico analysis reveals their potential to modulate autophagy, which could significantly contribute to their anti-photoaging properties. The findings of this study hold promise for the advancement of cosmeceuticals and therapeutics containing natural compounds aimed at addressing photoaging and various skin-related diseases. By leveraging their dual benefits of photoprotection and autophagy modulation, these natural compounds offer a multifaceted approach to combatting skin aging and related conditions.

Skin autofluorescence of advanced glycation end-products relates to new cardiovascular events in type 2 diabetes: A longitudinal observational study

BACKGROUND

Cardiovascular disease is frequent in type 2 diabetes mellitus (T2DM). We investigated the relationship between skin autofluorescence (SAF) of advanced glycation end-products and later cardiovascular events (CVEs) in patients with T2DM.

RESEARCH DESIGN AND METHODS

We conducted a retrospective analysis of 504 patients hospitalized for uncontrolled and/or complicated T2DM between 2009 and 2017. SAF was measured using an AGE-Reader. Participants were followed up from admission to December 2020, for the onset of a CVE (myocardial infarction, stroke, revascularization procedures or cardiovascular death). The relationship between SAF and CVE was analyzed by multivariable Cox regression. Log-rank curves were used to compare CVE-free survival in patients whose SAF at admission was above versus below the whole-population median. The analysis was repeated in subjects without/with macroangiopathy (defined as myocardial infarction, stroke, peripheral revascularization) at baseline.

FINDINGS

During 54 months of follow-up, 69 (13.7%) patients had a CVE. Baseline SAF was significantly higher in patients with T2DM who later experienced a CVE (2.89 ± 0.70 arbitrary units versus 2.64 ± 0.62 in others, P = 0.002). This relationship was significant after adjusting for age, sex, conventional risk factors (diabetes duration, HbA1c, arterial hypertension, dyslipidemia, smoking, body mass index), vascular complications, C-reactive protein, and treatments for diabetes. The CVE-free survival curves differed between subjects whose SAF was above the whole-population median (log-rank: P = 0.002) and those whose SAF was above the macroangiopathy-free sub-population median (log-rank: P = 0.016).

CONCLUSION

SAF of advanced glycation end-products was related to a higher incidence of later CVE in patients with T2DM.

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.

The Rotterdam Study. Design update and major findings between 2020 and 2024

The Rotterdam Study is a population-based cohort study, started in 1990 in the district of Ommoord in the city of Rotterdam, the Netherlands, with the aim to describe the prevalence and incidence, unravel the etiology, and identify targets for prediction, prevention or intervention of multifactorial diseases in mid-life and elderly. The study currently includes 17,931 participants (overall response rate 65%), aged 40 years and over, who are examined in-person every 3 to 5 years in a dedicated research facility, and who are followed-up continuously through automated linkage with health care providers, both regionally and nationally. Research within the Rotterdam Study is carried out along two axes. First, research lines are oriented around diseases and clinical conditions, which are reflective of medical specializations. Second, cross-cutting research lines transverse these clinical demarcations allowing for inter- and multidisciplinary research. These research lines generally reflect subdomains within epidemiology. This paper describes recent methodological updates and main findings from each of these research lines. Also, future perspective for coming years highlighted.

Advanced glycation end products are not associated with bone mineral density, trabecular bone score, and bone turnover markers in adults with and without type 1 diabetes: a cross-sectional study

It is unclear if AGEs are involved in the bone fragility of type 1 diabetes (T1D). We evaluated whether skin AGEs by skin autofluorescence and serum AGEs (pentosidine, carboxymethyl-lysine [CML]) are independently associated with BMD by DXA (lumbar spine, hip, distal radius), trabecular bone score (TBS), serum bone turnover markers (BTMs: CTX; P1NP; osteocalcin), and sclerostin in participants with and without T1D. Linear regression models were used, with interaction terms to test effect modification by T1D status. In participants with T1D, correlations between skin and serum AGEs as well as between AGEs and 3-year HbA1C were evaluated using Spearman's correlations. Data are mean ± SD or median (interquartile range). We included individuals who participated in a cross-sectional study and had BMD and TBS assessment (106 T1D/65 controls, 53.2% women, age 43 ± 15 yr, BMI 26.6 ± 5.5 kg/m2). Participants with T1D had diabetes for 27.6 ± 12.3 yr, a mean 3-yr HbA1C of 7.5 ± 0.9% and skin AGEs of 2.15 ± 0.54 arbitrary units. A subgroup of 65 T1D/57 controls had BTMs and sclerostin measurements, and those with T1D also had serum pentosidine (16.8[8.2-32.0] ng/mL) and CML [48.0 ± 16.8] ng/mL) measured. Femoral neck BMD, TBS, and BTMs were lower, while sclerostin levels were similar in participants with T1D vs controls. T1D status did not modify the associations between AGEs and bone outcomes. Skin AGEs were significantly associated with total hip and femoral neck BMD, TBS, BTMs, and sclerostin before, but not after, adjustment for confounders. Serum AGEs were not associated with any bone outcome. There were no significant correlations between skin and serum AGEs or between AGEs and 3-yr HbA1C. In conclusion, skin and serum AGEs are not independently associated with BMD, TBS, BTMs, and sclerostin in participants with relatively well-controlled T1D and participants without 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.

Advanced Glycation End Products (AGEs) in Diet and Skin in Relation to Stool Microbiota: The Rotterdam Study

BACKGROUND

Advanced glycation end products (AGEs) are involved in age-related diseases, but the interaction of gut microbiota with dietary AGEs (dAGEs) and tissue AGEs in the population is unknown.

OBJECTIVE

Our objective was to investigate the association of dietary and tissue AGEs with gut microbiota in the population-based Rotterdam Study, using skin AGEs as a marker for tissue accumulation and stool microbiota as a surrogate for gut microbiota.

DESIGN

Dietary intake of three AGEs (dAGEs), namely carboxymethyl-lysine (CML), N-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MGH1), and carboxyethyl-lysine (CEL), was quantified at baseline from food frequency questionnaires. Following up after a median of 5.7 years, skin AGEs were measured using skin autofluorescence (SAF), and stool microbiota samples were sequenced (16S rRNA) to measure microbial composition (including alpha-diversity, beta-dissimilarity, and taxonomic abundances) as well as predict microbial metabolic pathways. Associations of both dAGEs and SAF with microbial measures were investigated using multiple linear regression models in 1052 and 718 participants, respectively.

RESULTS

dAGEs and SAF were not associated with either the alpha-diversity or beta-dissimilarity of the stool microbiota. After multiple-testing correction, dAGEs were not associated with any of the 188 genera tested, but were nominally inversely associated with the abundance of Barnesiella, Colidextribacter, Oscillospiraceae UCG-005, and Terrisporobacter, in addition to being positively associated with Coprococcus, Dorea, and Blautia. A higher abundance of Lactobacillus was associated with a higher SAF, along with several nominally significantly associated genera. dAGEs and SAF were nominally associated with several microbial pathways, but none were statistically significant after multiple-testing correction.

CONCLUSIONS

Our findings did not solidify a link between habitual dAGEs, skin AGEs, and overall stool microbiota composition. Nominally significant associations with several genera and functional pathways suggested a potential interaction between gut microbiota and AGE metabolism, but validation is required. Future studies are warranted, to investigate whether gut microbiota modifies the potential impact of dAGEs on health.

Skin Ageing: A Progressive, Multi-Factorial Condition Demanding an Integrated, Multilayer-Targeted Remedy

Of the human organs, skin is the most visible one that displays the manifestations of ageing. It has a very intricate microanatomical structure and performs several key physiological functions. The pathophysiology of cutaneous ageing is characterized by deterioration of structural stability and functional integrity, implying a continuous reduction in maximal function and reserve capacity, as a result of the accumulating damage due to both intrinsic and extrinsic factors. Elimination of unfavorable expressions associated with facial and cutaneous ageing is the key patient demand in aesthetic dermatology. Even though the progress has been made in nonsurgical therapies like fillers and lasers, non-invasive interventions by using skin care products designed for rejuvenation at an early stage are the most popular and accessible solution among people. In this review, we have scrutinized the ageing-associated cutaneous changes at molecular, cellular and tissue levels. To optimize the ageing process towards a healthy skin, we propose an integrated, multilayer-targeted intervention, which involves both topical application of anti-ageing formulations from outside and oral supplementation from inside. Additionally, several promising naturally derived ingredients are reviewed from an anti-aging perspective. Most of them possess various bioactivities and may contribute to the development of the mentioned anti-ageing remedy.

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.

Skin autofluorescence of Advanced Glycation End-products and mortality in older adults: The roles of chronic kidney disease and diabetes

BACKGROUND AND AIM

Advanced glycation end products are involved in age-related multisystem decline. They accumulate in body tissues with age, diabetes and chronic kidney disease (CKD), and can be measured non-invasively by the skin autofluorescence (SAF). We studied the relation between SAF and later mortality in old adults.

METHODS AND RESULTS

The SAF was measured using an AGE-Reader in 451 individuals from the general population aged over 75 years, and all-cause mortality was assessed during an average follow-up of 6.4 years. The association between SAF and mortality was analyzed using a multivariate Cox survival model, adjusted for age and gender. Analyses were further adjusted for diabetes and stratified on the presence of CKD due to its interaction with SAF for the risk of mortality. Participants were 82 years old on average (SD 4.1). Their mean SAF was 2.8 AU (SD 0.6). One hundred and forty-four individuals (31.9%) died during the follow-up. Adjusted for age and gender, SAF was associated with an increased risk of all-cause mortality (HR 1.44, 95%CI: 1.14-1.82 for a one-AU increase of SAF). The association was no longer significant after adjustment for diabetes. However, after stratification for the presence of CKD, higher SAF was associated with an increased risk of all-cause mortality in the participants with CKD at baseline (HR 1.68, 95%CI: 1.11-2.55), whereas there was no association among participants without CKD (HR 0.95, 95%CI: 0.63-1.44).

CONCLUSION

Skin autofluorescence is associated with increased all-cause mortality in older adults already suffering from CKD.

Research Advances on the Damage Mechanism of Skin Glycation and Related Inhibitors

Our skin is an organ with the largest contact area between the human body and the external environment. Skin aging is affected directly by both endogenous factors and exogenous factors (e.g., UV exposure). Skin saccharification, a non-enzymatic reaction between proteins, e.g., dermal collagen and naturally occurring reducing sugars, is one of the basic root causes of endogenous skin aging. During the reaction, a series of complicated glycation products produced at different reaction stages and pathways are usually collectively referred to as advanced glycation end products (AGEs). AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with aging. AGEs are also associated with a variety of age-related diseases, such as diabetes, cardiovascular disease, renal failure (uremia), and Alzheimer's disease. AGEs accumulate in the skin with age and are amplified through exogenous factors, e.g., ultraviolet radiation, resulting in wrinkles, loss of elasticity, dull yellowing, and other skin problems. This article focuses on the damage mechanism of glucose and its glycation products on the skin by summarizing the biochemical characteristics, compositions, as well as processes of the production and elimination of AGEs. One of the important parts of this article would be to summarize the current AGEs inhibitors to gain insight into the anti-glycation mechanism of the skin and the development of promising natural products with anti-glycation effects.

Possible effects of dietary advanced glycation end products on maternal and fetal health: a review

Excessive accumulation of advanced glycation end products (AGEs) in the body has been associated with many adverse health conditions. The common point of the pathologies associated at this point is oxidative stress and inflammation. Pregnancy is an important period in which many physiological, psychological, and biological changes are experienced. Along with the physiological changes that occur during this period, the mother maintaining an AGE-rich diet may cause an increase in the body's AGE pool and may increase oxidative stress and inflammation, as seen in healthy individuals. Studies have reported the negative effects of maternal AGE levels on maternal and fetal health during pregnancy. Although gestational diabetes, preeclampsia, endothelial dysfunction, and pelvic diseases constitute maternal complications, a number of pathological conditions such as intrauterine growth retardation, premature birth, neural tube defect, neurobehavioral developmental disorders, fetal death, and neonatal asphyxia constitute fetal complications. It is thought that the mechanisms of these complications have not been confirmed yet and more clinical studies are needed on this subject. The possible effects of dietary AGE levels during pregnancy on maternal and fetal health are examined in this review.

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.

Skin autofluorescence is associated with progression of kidney disease in type 2 diabetes: A prospective cohort study from the Hong Kong diabetes biobank

BACKGROUND AND AIMS

Skin autofluorescence (SAF) can non-invasively assess the accumulation of tissue AGEs. We investigated the association between SAF and kidney dysfunction in participants with T2D.

METHODS

Of 4030 participants consecutively measured SAF at baseline, 3725 participants free of end-stage kidney disease (ESKD) were included in the analyses. The association of SAF with incident ESKD or ≥30% reduction in estimated glomerular filtration rate (eGFR) was examined with Cox regression, linear mixed-effects model for the association with annual eGFR decline, and mediation analyses for the mediating roles of renal markers.

RESULTS

During a median (IQR) 1.8 (1.1-3.1) years of follow-up, 411 participants developed the outcome. SAF was associated with progression of kidney disease (hazard ratio 1.15 per SD, 95% confidence interval [CI] [1.04, 1.28]) and annual decline in eGFR (β -0.39 per SD, 95% CI [-0.71, -0.07]) after adjustment for risk factors, including baseline eGFR and urinary albumin-creatinine ratio (UACR). Decreased eGFR (12.9%) and increased UACR (25.8%) accounted for 38.7% of the effect of SAF on renal outcome.

CONCLUSIONS

SAF is independently associated with progression of kidney disease. More than half of its effect is independent of renal markers. SAF is of potential to be a prognostic marker for kidney dysfunction.

Advanced glycation end product intake during pregnancy and offspring allergy outcomes: A Prospective cohort study

BACKGROUND

Associations have been shown between concurrent assessment of dietary intake of advanced glycation end products (AGEs) and childhood allergic outcomes. We examined the association between maternal AGEs intake and development of offspring asthma, wheeze, atopic dermatitis, allergic rhinitis and food allergies, and sought to determine whether the intake of AGEs was associated with cord sera cytokines/chemokines.

METHODS

Pregnant women ≥16 years were recruited in the Healthy Start study, a prospective pre-birth cohort from Colorado (N = 1410). The analysis included 962 dyads with adequate diet (≥2 recalls) and allergy outcome details. AGEs intake was estimated for each mother by matching intakes reported using 24-h dietary recalls during pregnancy to a reference database of commonly consumed foods' AGEs values. Child diagnoses of asthma and allergies up to 8 years were obtained from electronic medical records. Cord sera cytokines and chemokines were analysed in a subset (N = 462) of children.

RESULTS

The median [IQR] AGEs intake for the overall sample was 11,919 kU/day [8293, 16,573]. Unadjusted analysis showed a positive association between maternal AGEs intake in pregnancy and rhinitis up to 8 years of age (HR = 1.03; 95% CI: 1.01, 1.06), but the association was attenuated and no longer significant in adjusted models (HR = 1.01; 95% CI: 0.98, 1.04). Both adjusted and unadjusted models showed no associations between AGEs intake in pregnancy and any of the other outcomes (p > .05). There were no significant associations between any cytokine or chemokine measured and AGEs intake or any of the outcomes studied (p > .05).

CONCLUSION

The study showed that maternal AGEs intake was not associated with offspring asthma and allergy outcomes. AGEs exposure during pregnancy may not have the same impact on child development as postnatal exposure.

Skin autofluorescence is associated with higher risk of cardiovascular events in Chinese adults with type 2 diabetes: A prospective cohort study from the Hong Kong Diabetes Biobank

AIMS

To investigate association between skin autofluorescence (SAF) and cardiovascular events (CVE) and assess its predictive value in Chinese adults with type 2 diabetes (T2D).

MATERIALS AND METHODS

SAF was measured non-invasively in 3806 Chinese adults with T2D between 2016 and 2019 with CVE as primary endpoint and individual components as secondary endpoints. Cox proportional hazard models were used to examine associations between SAF and endpoints with adjustment for conventional risk factors. C-statistic, integrated discrimination improvement (IDI), and net reclassification improvement (NRI) were performed to evaluate SAF's predictive value.

RESULTS

During a median 1.8 (interquartile range, 1.2-3.1) years of follow-up, 172 individuals experienced CVE. Multivariate Cox model showed that SAF was independently associated with CVE (HR 1.18 per SD, 95% CI [1.02, 1.37]), coronary heart disease (HR 1.29 per SD, 95% CI [1.02, 1.63]), and congestive heart failure (HR 1.53 per SD, 95% CI [1.14, 2.05]). SAF yielded additional value on CVE risk stratification with enhanced IDI (95% CI) (0.023 [0.001, 0.057]) and continuous NRI (0.377 [0.002, 0.558]) over traditional risk factors.

CONCLUSIONS

Higher SAF was independently associated with CVE in Chinese adults with T2D and yielded incremental predictive information for CVE. SAF has potential as a prognostic maker for CVE.

Habitual intake of dietary advanced glycation end products is not associated with generalized microvascular function-the Maastricht Study

BACKGROUND

Endogenously formed advanced glycation end products (AGEs) may be important drivers of microvascular dysfunction and the microvascular complications of diabetes. AGEs are also formed in food products, especially during preparation methods involving dry heat.

OBJECTIVES

We aimed to assess cross-sectional associations between dietary AGE intake and generalized microvascular function in a population-based cohort.

METHODS

In 3144 participants of the Maastricht Study (mean ± SD age: 60 ± 8 y, 51% men) the dietary AGEs Nε-(carboxymethyl)lysine (CML), Nε-(1-carboxyethyl)lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) were estimated using the combination of our ultra-performance LC-tandem MS dietary AGE database and an FFQ. Microvascular function was determined in the retina as flicker light-induced arteriolar and venular dilation and as central retinal arteriolar and venular equivalents, in plasma as a z score of endothelial dysfunction biomarkers (soluble vascular adhesion molecule 1 and soluble intracellular adhesion molecule 1, soluble E-selectin, and von Willebrand factor), in skin as the heat-induced skin hyperemic response, and in urine as 24-h albuminuria. Associations were evaluated using multiple linear regression adjusting for demographic, cardiovascular, lifestyle, and dietary factors.

RESULTS

Overall, intakes of CML, CEL, and MG-H1 were not associated with the microvascular outcomes. Although higher intake of CEL was associated with higher flicker light-induced venular dilation (β percentage change over baseline: 0.14; 95% CI: 0.02, 0.26) and lower plasma biomarker z score (β: -0.04 SD; 95% CI: -0.08, -0.00 SD), the effect sizes were small and their biological relevance can be questioned.

CONCLUSIONS

We did not show any strong association between habitual intake of dietary AGEs and generalized microvascular function. The contribution of dietary AGEs to generalized microvascular function should be further assessed in randomized controlled trials using specifically designed dietary interventions.

Bioelectrical Impedance Analysis Derived-Phase Angle as a Pragmatic Tool to Detect Protein Energy Wasting among Multi-Ethnic Hemodialysis Patients

Protein-energy wasting (PEW) is a devastating metabolic derangement that leads to increased morbidity and mortality in hemodialysis (HD) patients. This study aimed to determine the diagnostic test accuracy of bioelectrical impedance analysis derived-phase angle (PhA) in detecting PEW among HD patients. This was a multi-centre, cross-sectional study conducted amongst 152 multi-ethnic HD patients in Klang Valley, Malaysia. PEW was assessed using the International Society of Renal Nutrition and Metabolism criteria as the reference method. PhA was measured using a multi-frequency bioelectrical impedance spectroscopy at 50 kHz. Multiple and logistic regressions were used to determine factors associated with PhA and PEW diagnosis, respectively. A receiver operating characteristics curve analysis was used to establish the gender-specific PhA cut-offs to detect PEW. PEW existed in 21.1% of the HD patients. PhA was found as an independent predictor of PEW (adjOR = 0.308, p = 0.001), with acceptable to excellent discriminative performance (adjAUC_male = 0.809; adjAUC_female = 0.719). Male patients had higher PhA cut-off compared to female patients (4.26° vs. 3.30°). We concluded that PhA is a valid and pragmatic biomarker to detect PEW in multi-ethnic Malaysian HD patients and a gender-specific cut-off is necessary, attributed to the gender differences in body composition.

Methods to assess advanced glycation end-products

PURPOSE OF REVIEW

Advanced glycation end-products (AGEs) resulting from protein glycoxidation constitute biomarkers of interest in different pathological situations. Several methods for quantifying AGEs in biological fluids or tissues have been developed without any real consensus on a gold standard method. The aim of this review is to provide an overview of recent publications in the field helping to decide if these markers could find their place as diagnostic tools in clinical practice.

RECENT FINDINGS

This update shows that new AGEs are regularly discovered and new analytical methods (especially mass spectrometry-based methods) regularly described. Skin autofluorescence measurement is increasingly performed due to the practicability of the dedicated devices, in spite of its questionable specificity. In biological fluids, carboxymethyllysine remains the most frequently measured AGE. However, to date, it is still difficult to compare results obtained from different studies because measured AGEs and modes of expression are different and because no method standardization has been initiated.

SUMMARY

Despite their potential interest as biomarkers and the availability of unfortunately non-standardized assay methods, AGEs remain confined to clinical research studies without really being used in daily clinical practice. These challenges must be addressed in order to allow their implementation.

Skin auto-fluorescence as a measure of advanced glycation end-products is associated with microvascular health in patients with COPD

BACKGROUND AND OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is associated with systemic inflammation and oxidative stress. These physiological processes can lead to increased formation and accumulation of advanced glycation end-products (AGEs), that can play a role in vascular complications. In this cross-sectional study, we determined the association between skin AGEs and microvascular health in patients with COPD.

METHODS

Clinical characteristics and cardiovascular parameters, including pulmonary function, metabolic and inflammatory parameters, and blood pressure, were obtained in this observational study with patients with COPD. Skin concentrations of AGEs were assessed non-invasively by measuring skin autofluorescence (AF). Retinal vessel analysis was used as a marker of microvascular health.

RESULTS

62 patients with COPD (52% males; mean age: 64.4 ± 8.4 years; mean FEV₁: 45.0 ± 20.7%pred.) were analysed. Mean skin AF was 2.75 ± 0.64 arbitrary units. Skin AF in patients with COPD was negatively associated with retinal arteriolar diameter (β -0.021, 95% CI -0.040 to -0.002; p = 0.031) and arteriole-to-venular ratio (β -7.233, 95% CI -9.732 to -4.734; p < 0.001) and positively associated with retinal venular diameter (β 0.029, 95% CI 0.019 to 0.038; p < 0.001) after adjustment for sex, age, lung function, pack-years of smoking and conventional cardiovascular risk factors.

CONCLUSION

We document for the first time that skin AF in patients with COPD is independently associated with retinal arteriolar and venular vessel diameters, biological indicators for microvascular health. This adds to the evidence that AGEs are an accessible marker of microvascular health.

Dietary Advanced Glycation End-Products (dAGEs) Intake and Bone Health: A Cross-Sectional Analysis in the Rotterdam Study

Animal studies suggest a role for dietary advanced glycation end-products (dAGEs) in bone health, but human studies on dAGEs in relation to bone are lacking. We aimed to study whether dAGEs intake is associated with the parameters of bone strength namely, bone mineral density (BMD), prevalent vertebral (VFs), and major osteoporotic fractures (MOFs = hip, wrist, proximal humerus, and clinical VFs). 3949 participants (mean age 66.7 ± 10.5 years) were included from a Rotterdam study for whom Carboxymethyllysine (CML—a dietary AGE) was estimated from food frequency questionnaires combined with dAGEs databases. Multivariable linear and logistic regression models were performed adjusting for age, sex, energy intake, dietary quality, physical activity, diabetes, smoking, renal function, and cohort effect and for models on fractures, subsequently for BMD. We observed no association of CML with BMD at both femoral neck (β = −0.006; p = 0.70) and lumbar spine (β = −0.013; p = 0.38). A higher intake of CML was linearly associated with VFs (Odds ratio, OR = 1.16, 95% CI (1.02–1.32) and a similar but non-significant trend with MOFs (OR = 1.12 (0.98–1.27). Additional adjustment for BMD did not change the associations. Our results imply a positive association between dietary intake of CML and VFs independent of BMD. Future studies are needed in order to elucidate whether associations found are causal.