Skin autofluorescence, a measure of cumulative metabolic stress and advanced glycation end products, predicts mortality in hemodialysis patients

Skin advanced glycation end-products as indicators of the metabolic profile in diabetes mellitus: correlations with glycemic control, liver phenotypes and metabolic biomarkers

INTRODUCTION

The production of advanced glycation end-products (AGEs) is a key pathomechanism related to the complications of diabetes mellitus. The measurement of HbA1c as one of the AGEs is widely used in the clinic, but also other proteins undergo glycation in the course of diabetes. Here, we measure skin AGEs (SAGEs) in patients with diabetes type 1 (DM1) and type 2 (DM2) and correlate them with metabolic markers as well as non-invasively measured liver fibrosis and steatosis.

PATIENTS AND METHODS

In this cross-sectional study, a total of 64 patients with either DM1 or DM2 and 28 healthy controls were recruited. SAGEs were measured using autofluorescence (AGE Reader). Liver fibrosis and steatosis were quantified using transient elastography, which determines liver stiffness measurement (LSM) and controlled attenuation parameter (CAP). FGF19, FGF21 and GDF-15 were measured in blood samples using ELISA.

RESULTS

SAGEs were elevated in both groups of patients with diabetes as compared to healthy controls (both p < 0.001) and were higher in patients with DM2 in comparison to DM1 (p = 0.006). SAGEs correlated positively with HbA1c (r = 0.404, p < 0.001), CAP (r = 0.260, p = 0.016) and LSM (r = 0.356, p < 0.001), and negatively with insulin growth factor binding protein 3 (p < 0.001). We also detected a positive correlation between GDF15 and SAGEs (r = 0.469, p < 0.001).

CONCLUSIONS

SAGEs are significantly elevated in patients with both DM types 1 and 2 and correlate with metabolic markers, including HbA1c and GDF15. They might also help to detect patients with advanced liver injury in the setting of diabetes.

Association between Osteoporosis and Skeletal Muscle Mass in Men

STUDY DESIGN

Cross-sectional study.

PURPOSE

This cross-sectional study aimed to investigate the risk factors for osteoporosis in men by assessing bone mineral density (BMD), skeletal muscle mass, body fat mass, grip strength, and advanced glycation end products (AGEs).

OVERVIEW OF LITERATURE

Fewer studies have reported the correlation between BMD and skeletal muscle mass in women. Moreover, a few studies have examined the relationship between osteoporosis and skeletal muscle mass.

METHODS

This study included 99 men (mean age, 74.9 years; range, 28-93 years) who visited Qiball Clinic for BMD and body composition examinations. The osteoporosis group consisted of 24 patients (mean age, 72.5 years; range, 44-92 years), and the control group consisted of 75 individuals (mean age, 74.9 years; range, 28-93 years). Whole-body skeletal muscle mass was measured using a bioelectrical impedance analyzer. BMD was measured by dual X-ray absorptiometry. Skin autofluorescence (SAF), a marker of dermal AGE accumulation, was measured using a spectroscope. Osteoporosis was defined as a bone density T score of -2.5 or less. Physical findings, skeletal muscle mass, BMD, grip strength, and SAF were compared between the osteoporosis and control groups.

RESULTS

The osteoporosis group had significantly lower trunk muscle mass (23.1 kg vs. 24.9 kg), lower leg muscle mass (14.4 kg vs. 13.0 kg), and skeletal mass index (7.1 kg/m2 vs. 6.7 kg/m2) than the control group (all p<0.05). Lower limb muscle mass was identified as a risk factor for osteoporosis in men (odds ratio, 0.64; p=0.03).

CONCLUSIONS

Conservative treatment of osteoporosis in men will require an effective approach that facilitates the maintenance or strengthening of skeletal muscle mass, including exercise therapy with a focus on lower extremities and nutritional supplementation.

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.

Epigenetic clocks indicate that kidney transplantation and not dialysis mitigate the effects of renal ageing

BACKGROUND

Chronic kidney disease (CKD) is an age-related disease that displays multiple features of accelerated ageing. It is currently unclear whether the two treatment options for end-stage kidney disease (dialysis and kidney transplantation [KT]) ameliorate the accelerated uremic ageing process.

METHODS

Data on clinical variables and blood DNA methylation (DNAm) from CKD stage G3-G5 patients were used to estimate biological age based on blood biomarkers (phenotypic age [PA], n = 333), skin autofluorescence (SAF age, n = 199) and DNAm (Horvath, Hannum and PhenoAge clocks, n = 47). In the DNAm cohort, we also measured the change in biological age 1 year after the KT or initiation of dialysis. Healthy subjects recruited from the general population were included as controls.

RESULTS

All three DNAm clocks indicated an increased biological age in CKD G5. However, PA and SAF age tended to produce implausibly large estimates of biological age in CKD G5. By contrast, DNAm age was 4.9 years (p = 0.005) higher in the transplantation group and 5.9 years (p = 0.001) higher in the dialysis group compared to controls. This age acceleration was significantly reduced 1 year after KT, but not after 1 year of dialysis.

CONCLUSIONS

Kidney failure patients displayed an increased biological age as estimated by DNAm clocks compared to population-based controls. Our results suggest that KT, but not dialysis, partially reduces the age acceleration.

Cross-Sectional and Longitudinal Associations between Skin Autofluorescence and Tubular Injury Defined by Urinary Excretion of Liver-Type Fatty Acid-Binding Protein in People with Type 2 Diabetes

It has previously been unclear whether the accumulation of advanced glycation end products, which can be measured using skin autofluorescence (SAF), has a significant role in diabetic kidney disease (DKD), including glomerular injury and tubular injury. This study was therefore carried out to determine whether SAF correlates with the progression of DKD in people with type 2 diabetes (T2D). In 350 Japanese people with T2D, SAF values were measured using an AGE Reader®, and both urine albumin-to-creatinine ratio (uACR), as a biomarker of glomerular injury, and urine liver-type fatty acid-binding protein (uLFABP)-to-creatinine ratio (uL-FABPCR), as a biomarker of tubular injury, were estimated as indices of the severity of DKD. Significant associations of SAF with uACR (p < 0.01), log-transformed uACR (p < 0.001), uL-FABPCR (p < 0.001), and log-transformed uL-FABPCR (p < 0.001) were found through a simple linear regression analysis. Although SAF was positively associated with increasing uL-FABPCR (p < 0.05) and increasing log-transformed uL-FABPCR (p < 0.05), SAF had no association with increasing uACR or log-transformed uACR after adjusting for clinical confounding factors. In addition, the annual change in SAF showed a significant positive correlation with annual change in uL-FABPCR regardless of confounding factors (p = 0.026). In conclusion, SAF is positively correlated with uL-FABP but not with uACR in people with T2D. Thus, there is a possibility that SAF can serve as a novel predictor for the development of diabetic tubular injury.

Association between fingertip-measured advanced glycation end products and cardiovascular events in outpatients with cardiovascular disease

BACKGROUND

The accumulation of advanced glycation end products (AGEs) is associated with cardiovascular events in patients with cardiovascular disease (CVD). However, the relationship between the AGEs measured by an AGEs sensor noninvasively at the fingertip and prognosis in patients with CVD remains unclear. Therefore, this study aimed to determine the relationship between AGEs score and prognosis among patients with CVD.

METHODS

A total of 191 outpatients with CVD were included. AGEs score were measured using an AGEs sensor and the patients were classified into groups by the median value of AGEs score. The incidence of major adverse cardiovascular and cerebrovascular events (MACCE) at 30 months was compared between high- and low-AGEs score groups. In addition, receiver operating characteristic (ROC) curve analysis was used to calculate cutoff value for the AGEs score, which discriminates the occurrence of MACCE. Cox regression analysis was performed to identify the factors associated with the presence of MACCE. MACCE included cardiac death, myocardial infarction, percutaneous coronary intervention, heart failure, and stroke.

RESULTS

AGEs score was normally distributed, with a median value of 0.51. No significant intergroup differences were found in laboratory findings, physical functions, or medications. The high-AGEs score group had a significantly higher incidence of MACCE than the low-AGEs score group (27.1 vs. 10.5%, P = 0.007). A high-AGEs score was a risk factor for MACCE (hazard ratio, 2.638; 95% confidence interval, 1.271-5.471; P = 0.009). After the adjustment for confounders other than 6-min walking distance, the AGEs score remained a factor associated with the occurrence of MACCE. The best cutoff AGEs score for the detection of MACCE was 0.51 (area under the curve, 0.642; P = 0.008; sensitivity, 72.2%; specificity, 54.8%).

CONCLUSIONS

AGEs score measured at the fingertip in patients with CVD is associated with MACCE. AGEs score, which can be measured noninvasively and easily, may be useful as an assessment for the secondary prevention of CVD in patients with CVD.

Advanced glycosylation end products as metabolic predictors of systemic pro-inflammatory and prooxidant status in patients with end-stage renal disease

Controlling systemic proinflammatory and prooxidant effectors is essential for mitigating cardiovascular risk and mortality in patients with end-stage renal disease (ESRD). However, monitoring these processes is still challenging due to the high uncertainty about their determinants and predictors. Thus, we investigated the relationship between advanced glycosylation end products (AGE), proinflammatory and prooxidant effectors in ESRD patients undergoing hemodialysis (HD). In addition to nutritional profile and dialysis efficiency, AGE, cytokines, chemokines, C-reactive protein (CRP), total (TAC) and non-protein (npAC) antioxidant capacity, lipid and protein oxidation were analyzed in blood samples from 43 HD patients. AGE, CRP, cytokines, chemokines, protein carbonyl (PCn), and malondialdehyde (MDA) were upregulated, while TAC and npAC were down-regulated in HD patients compared to heath subjects. Dialysis efficiency, TAC and npAC were reduced, while leucocytes counting, pre- and post-HD urea, TNF, IL-6, IL-10, CCL-2, MIP-1β, PCn, and MDA were increased in patients with higher AGE accumulation compared to those with lower AGE levels. Serum levels of CRP, protein carbonyl, malondialdehyde, and all cytokines and chemokines analyzed were correlated with AGE circulating levels for patients with higher AGE accumulation. AGE was inversely correlated with IL-10, TAC and npAC in patients with higher AGE accumulation. AGE exhibited predictive value (determination coefficient) to explain CRP, cytokines, chemokines, PCN, MDA, TAC and npAC variability in patients with higher AGE levels. Taken together, our findings provide evidence that AGE accumulation is associated with important proinflammatory and prooxidant effectors in patients with ESRD undergoing hemodialysis. Thus, AGE monitoring may be relevant to predict systemic inflammatory stress and the balance between oxidant and antioxidant status in these patients.

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.

Association of skin autofluorescence with depressive symptoms and the severity of depressive symptoms: The prospective REACTION study

AIM

Millions of people are afflicted by depression, a highly prevalent mental illness with increased morbidity and mortality. Advanced glycation end-products (AGEs) are potential risk factors for depression. We aimed to investigate the correlation of AGEs with depressive symptoms and the severity of depressive symptoms.

METHODS

This study was nested in the prospective REACTION (Risk Evaluation of cAncers in Chinese diabeTic Individuals) study and included 4420 eligible participants. skin autofluorescence (SAF) was used to measure skin AGEs. Depressive symptoms were evaluated by the Self-Rating Depression Scale (SDS). Multiple logistic regression analysis was used to assess the association of AGEs with depressive symptoms and the severity of depressive symptoms.

RESULTS

Logistic analysis showed a significantly positive relationship between quartiles of SAF-AGEs and the risk of depressive symptoms with the OR [95% confidence interval (CI), p value] of 1.24 (95% CI: 1.03-1.50, p = 0.022), 1.39 (95% CI: 1.15-1.68, p = 0.001) and 1.57 (95% CI: 1.28-1.91, p < 0.001) for multivariable-adjusted model respectively. And SAF-AGEs were associated with the severity of depressive symptoms with the multivariable-adjusted OR (95% CI, p value) of 1.06 (95% CI:0.79-1.43, p = 0.681), 1.47 (95% CI: 1.08-1.99, p = 0.014), and 1.54 (95% CI: 1.12-2.11, p = 0.008) respectively. Stratified analyses showed that SAF-AGEs were significantly associated with the severity of depressive symptoms only in females, overweight people, individuals with hypertension, and those without diabetes and insomnia.

CONCLUSIONS

The present study showed that a higher SAF-AGEs level was associated with depressive symptoms and the severity of depressive symptoms.

Advanced glycation end-products, cardiac function and heart failure in the general population: The Rotterdam Study

AIMS/HYPOTHESIS

The aim of this work was to assess the association of advanced glycation end-products (AGEs), measured by skin autofluorescence (SAF), with prevalent heart failure, and with systolic and diastolic cardiac function, in a large population-based cohort study.

METHODS

We assessed the cross-sectional association between SAF and prevalent heart failure among 2426 participants from the population-based Rotterdam Study, using logistic regression. Next, among individuals free of heart failure (N=2362), we examined the link between SAF (on a continuous scale) and echocardiographic parameters of left ventricular (LV) systolic and diastolic function using linear regressions. Analyses were adjusted for traditional cardiovascular risk factors.

RESULTS

Higher levels of SAF were associated with higher odds of prevalent heart failure (multivariable adjusted OR 2.90 [95% CI 1.80, 4.62] for one unit higher SAF value). Among individuals without heart failure, one unit increase in SAF was associated with 0.98% lower LV ejection fraction (mean difference [β] -0.98% [95% CI -1.45%, -0.50%]). The association was stronger among participants with diabetes (β -1.84% [95% CI -3.10%, -0.58%] and β -0.78% [95% CI -1.29%, -0.27%] among participants with and without diabetes, respectively). Associations of SAF with diastolic function parameters were not apparent, except in men with diabetes.

CONCLUSIONS/INTERPRETATION

AGE accumulation was independently associated with prevalent heart failure. Among individuals free of heart failure, AGEs were associated with cardiac function, in particular systolic function. This association was present in participants with and without diabetes and was more prominent in those with diabetes.

Is the measurement of tissue advanced glycosylation products by skin autofluorescence associated with mortality in patients treated by peritoneal dialysis?

BACKGROUND

Advanced glycosylated end-products (AGEs) have been shown to cause cardiovascular disease, and tissue AGE accumulation can be measured by skin autofluorescence (SAF). AGEs are cleared by the kidney, and thus accumulate in dialysis patients. However, as the results of SAF measurements in peritoneal dialysis patients (PD) have been ambiguous, we examined the association between mortality and SAF.

METHODS

We reviewed SAF measurements in PD patients attending a university associated PD program, along with standard measurements of dialysis adequacy and peritoneal membrane function.

RESULTS

We studied 341 prevalent PD patients, 61.9% male, mean age 61.2 ± 16 years, and 31.4% of all patients died during a median follow-up of 27.2 (23.3-36.3) months. Patients who died were older, mean age 72 ± 10.5 years, were more often diabetic (60.7%), and had higher median SAF 3.8 (3.2-4.5) AU. On logistic regression, mortality was independently associated with age (odds ratio (OR) 1.1 (95% confidence limits 1.06-1.16), diabetes OR 10.1 (3.1-33.4), SAF OR 3.3 (1.8-6.2), all p < 0.001, and male gender OR 5.2 (1.6-17.4), p = 0.007; and negatively associated with weight OR 0.91 (0.86-0.95), p < 0..001, normalised nitrogen appearance rate (nPNA) OR 0.05 (0.01-0.4), p = 0.005 and mean arterial blood pressure (MAP) OR 0.96 (0.93-0.96), p = 0.03.

CONCLUSIONS

In this observational study, SAF was independently associated with mortality. However, other factors were also associated with mortality, including age, diabetes and malnutrition which have all been reported to affect SAF measurements. Thus, the additional predictive value of measuring SAF compared to standard risk factors for mortality remains to be determined.

Genome-wide association study identifies novel loci associated with skin autofluorescence in individuals without diabetes

BACKGROUND

Skin autofluorescence (SAF) is a non-invasive measure reflecting accumulation of advanced glycation endproducts (AGEs) in the skin. Higher SAF levels are associated with an increased risk of developing type 2 diabetes and cardiovascular disease. An earlier genome-wide association study (GWAS) revealed a strong association between NAT2 variants and SAF. The aim of this study was to calculate SAF heritability and to identify additional genetic variants associated with SAF through genome-wide association studies (GWAS).

RESULTS

In 27,534 participants without diabetes the heritability estimate of lnSAF was 33% ± 2.0% (SE) in a model adjusted for covariates. In meta-GWAS for lnSAF five SNPs, on chromosomes 8, 11, 15 and 16 were associated with lnSAF (P < 5 × 10^-8): 1. rs2846707 (Chr11:102,576,358,C > T), which results in a Met30Val missense variant in MMP27 exon 1 (NM_022122.3); 2. rs2470893 (Chr15:75,019,449,C > T), in intergenic region between CYP1A1 and CYP1A2; with attenuation of the SNP-effect when coffee consumption was included as a covariate; 3. rs12931267 (Chr16:89,818,732,C > G) in intron 30 of FANCA and near MC1R; and following conditional analysis 4. rs3764257 (Chr16:89,800,887,C > G) an intronic variant in ZNF276, 17.8 kb upstream from rs12931267; finally, 30 kb downstream from NAT2 5. rs576201050 (Chr8:18,288,053,G > A).

CONCLUSIONS

This large meta-GWAS revealed five SNPs at four loci associated with SAF in the non-diabetes population. Further unravelling of the genetic architecture of SAF will help in improving its utility as a tool for screening and early detection of diseases and disease complications.

Concentrations of N6-Carboxymethyllysine (CML), N6-Carboxyethyllysine (CEL), and Soluble Receptor for Advanced Glycation End-Products (sRAGE) Are Increased in Psoriatic Patients

Psoriasis is a chronic, recurrent, and often severe skin disease which is frequently associated with metabolic disorders and increased risk of cardiovascular complications. One of the postulated links is an intensified process of advanced protein glycation and/or glycoxidation. Therefore, the aim of the study was to assess concentrations of N⁶-carboxymethyllysine (CML), N⁶-carboxyethyllysine (CEL), and soluble form of receptor for advanced glycation end-products (sRAGE) in psoriasis patients at different phases of the disease activity, in comparison to healthy individuals. The study material consisted of sera from psoriasis patients in active phase, in the remission phase, and healthy controls. Concentrations of CML, CEL, and sRAGE were determined using ELISA technique. In the patients with psoriasis (in both phases of the disease), concentrations of CML, CEL and sRAGE were significantly higher than in healthy individuals but they did not correlate with psoriasis area severity index (PASI) values. The remission of the disease was followed by a significant decrease in CML, CEL, and sRAGE concentrations when compared to active patients; however, these concentrations were still significantly higher than in the controls. Our data suggest that psoriasis is accompanied by an intense glycoxidation process and that high sRAGE levels seem to reflect permanent RAGE overstimulation.

Correlation Between Skin Autofluorescence and Muscle Activities of Lower Limb in Aging Without Disease and Disability

Skin autofluorescence is a useful index to estimate the accumulation of advanced glycation end-products in human tissues. Elderly persons with higher skin autofluorescence have lower muscle mass, muscle strength and muscle power, however, little is known about the relationship between the skin autofluorescence level and each muscle activity. We measured the values of skin autofluorescence from five places on a lower limb, and the signals of surface electromyogram during isometric contractions from five muscles on that, simultaneously. The waveforms of surface electromyogram were analyzed by Daubechies-4 wavelet transformation. The value of skin autofluorescence was increased in the proximal part of the lower limb compared with the value of the distal part. The principal component of surface electromyogram activity in a time-frequency domain was lower in the proximal part compared with that of the distal part. There was a weak negative correlation between the value of skin autofluorescence on the gluteal region and the value of the mean wavelet coefficient of the surface electromyogram signals within the gluteus maximus muscle. The higher accumulation of advanced glycation end-products on the gluteal region might suggest the lower muscle activity in aging without disease and disability.

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.

Role of skin autofluorescence in managing renal and cardiac diseases in outpatient dermatology

INTRODUCTION

The accumulation of tissue-advanced glycation end products in skin results from complex and consecutive reactions and can be measured by skin autofluorescence (SAF) reader devices. This overview discusses studies evaluating the utilization of SAF in screening renal and cardiac disease.

MATERIALS AND METHODS

Literature search was performed using Google Scholar, PubMed, Springer, Ovid, and ScienceDirect.

RESULTS

SAF was an independent predictor of progression of chronic kidney disease (CKD) and was elevated in subjects on hemodialysis and peritoneal dialysis. Furthermore, SAF was significantly associated with cardiovascular events, cardiovascular mortality, and all-cause mortality in CKD patients. Other studies revealed a correlation between SAF and arterial stiffness, vascular damage, and subclinical atherosclerosis. A vegetarian diet was associated with lower SAF levels, whereas malnutrition was correlated with higher levels and increased mortality.

CONCLUSIONS

SAF measurement may be useful in managing renal and cardiac disease. Future studies are needed to clarify the specific role of SAF in the management of CKD and its noninvasive office utilization to identify comorbidities in inflammatory diseases, such as psoriasis.

Association of skin autofluorescence with low bone density/osteoporosis and osteoporotic fractures in type 2 diabetes mellitus

BACKGROUND

Advanced glycation end products (AGEs) that abnormally accumulate in diabetic patients have been reported to damage bone health. We aimed to investigate the association between skin autofluorescence (SAF)-AGE_age (SAF - AGEs × age/100) and low bone density (LBD)/osteoporosis or major osteoporotic fractures (MOFs) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This study was nested in the prospective REACTION (Risk Evaluation of Cancers in Chinese Diabetic Individuals) study and included 1214 eligible participants. SAF was used to measure skin AGEs (SAF-AGEs). Fracture events were determined by an in-person clinical follow-up. Binary logistic regression analysis, linear regression analysis, and a restricted cubic spline nested in logistic models were used to test outcomes.

RESULTS

The overall prevalence of LBD/osteoporosis in middle-aged or elderly T2DM patients was 35.7% (n = 434), and the overall incidence of MOFs was 10.5% (n = 116). Logistic analysis showed a significantly positive relationship between quartiles of SAF-AGE_age and the risk of LBD/osteoporosis (odds ratio [OR] 2.02, 95% CI 1.34-3.03; OR 3.63, CI 2.44-5.39; and OR 6.51, CI 4.34-9.78) for the multivariate-adjusted models, respectively. SAF-AGE_age was associated with MOFs with a multivariate-adjusted OR of 1.02 (CI 0.52-2.02), 2.42 (CI 1.32-4.46), and 2.70 (CI 1.48-4.91), respectively. Stratified analyses showed that SAF-AGE_age was significantly associated with MOFs only in females, nonsmokers, nondrinkers, individuals with lower body mass index, and those without LBD/osteoporosis. Linear regression analyses showed that higher SAF-AGEs were associated with a higher level of serum N-terminal propeptide of type I procollagen (s-PINP) and serum carboxy-terminal cross-linking peptide of type I collagen (s-CTX), with a multivariate-adjusted OR of 1.02 (CI 0.24-1.80) and 6.30 (CI 1.77-10.83), respectively.

CONCLUSIONS

In conclusion, SAF-AGE_age was positively associated with the prevalence of LBD/osteoporosis or MOFs in patients with T2DM. A positive association between SAF-AGEs and the level of s-PINP and s-CTX was found.

A Prospective Analysis of Skin and Fingertip Advanced Glycation End-Product Devices in Healthy Volunteers

Background: Advanced glycation end products (AGEs) have been shown to accumulate in bone and are gaining interest in connective tissue research. Aims: To investigate the intrarater reliability, two-timepoint agreement and correlations within and between two commercially available skin autofluorescence (SAF) AGE devices. Methods: Healthy volunteers were enrolled in a prospective study at a single academic institution. Each participant underwent SAF analysis by two different, commercially available devices on two occasions, 14 days apart. Upon enrollment, a general survey about the participant’s lifestyle and health status was completed and followed up on for any changes at timepoint two. Results: In total, 40 participants (F:M ratio 5:3) with an average age of 39.0 ± 12.5 years were analyzed. For the AGE reader (skin) and AGE sensor (fingertip), both intrarater reliability and two-timepoint agreement were excellent with an interclass correlation coefficient (ICC) > 0.90 and a strong correlation within both machines. However, there was no correlation between both machines for either timepoint. In total, 4 participants were identified as outliers above the +2SD. Additionally, 5 participants with dark-colored skin could not be measured with the AGE reader at timepoint one and 4 at timepoint two. In contrast, all participants were able to undergo SAF analysis with the AGE sensor, irrespective of their skin type. Conclusions: Both machines showed excellent intrarater reliability and two-timepoint agreement, but the skin AGE reader might have limited applicability in individuals with dark-colored skin. Future research on AGEs might take our findings into consideration.

Relationship Between Clinical Symptoms and Skin Autofluorescence in Hemodialysis Patients as a Measure of Advanced Glycation End-Product Accumulation

Background

The purpose of this study was to investigate the relationship between skin autofluorescence (SAF), as a measure of advanced glycation end-product (AGE) accumulation and osteoporosis and clinical symptoms in hemodialysis patients.

Methodology

The study participants were 156 hemodialysis patients (97 males, 59 females, mean = 66.9 years, range = 25-92 years) who visited our hospital between October 2019 and March 2020. The average dialysis period was 10.4 years (range = 1-40 years). Age, years of dialysis, bone mineral density, bone metabolism markers (Ca, P, intact parathyroid hormone, total N-terminal propeptide of type 1 collagen, tartrate-resistant acid phosphatase-5b), clinical symptoms, and SAF were evaluated. Clinical symptoms were evaluated using the visual analog scale (VAS) score for low back pain (LBP) and leg pain ranging from 10 mm (extreme amount of pain) to 0 mm (no pain); the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ; 0-100 points); and the Roland-Morris Disability Questionnaire (RDQ; 0-24 points). We calculated Pearson correlation coefficients to assess the correlation of SAF with age, years of hemodialysis, bone density, bone metabolism markers, clinical symptoms, and biochemical markers.

Results

The SAF of dialysis patients averaged 4.11, higher than previous reports for non-dialysis patients. Age (r = 0.435, p = 0.0001) was moderately positively correlated and hemodialysis period (r = 0.214, p = 0.00907) was weakly positively correlated with SAF. Among the clinical symptoms measured by the JOABPEQ, social life dysfunction (r = -0.257, p = 0.0108) had a weak negative correlation with SAF.

Conclusions

The level of AGEs implied by SAF was elevated in hemodialysis patients. SAF correlated with social life disorders, suggesting that SAF may be involved in disorders of activities of daily living in hemodialysis dialysis patients.

The Correlation between the Level of Skin Advanced Glycation End Products in Type 2 Diabetes Mellitus and the Stages of Diabetic Retinopathy and the Types of Traditional Chinese Medicine Syndrome

Objective

We aimed to analyze the correlation between the level of skin advanced glycation end products (AGEs) in type 2 diabetes mellitus (T2DM) patients and the diabetic retinopathy (DR) staging in different traditional Chinese medicine (TCM) syndromes.

Methods

416 T2DM patients were divided into normal group, nonproliferative diabetic retinopathy (NPDR) group (mild, moderate, and severe), and proliferative diabetic retinopathy (PDR) group according to the DR grade. Patients' height, weight, fasting blood glucose (FBG), hemoglobin A1C (HbA1c), blood lipid, renal function, and skin AGEs were measured. According to TCM syndrome differentiation criteria, 230 patients with T2DM and DR were divided into I. qi and yin deficiency, collateral stasis group; II. liver and kidney deficiency, eye collaterals loss group; and III. yin and yang deficiency, blood stasis, and phlegm coagulation group.

Results

The skin AGEs levels of different DR staging groups were statistically significant (P < 0.05), and the skin AGEs levels in the mild and moderate NPDR groups were significantly higher (P < 0.05) than those of the normal group. It was significantly higher (P < 0.05) in the severe NPDR group than in the normal group, mild and moderate NPDR groups. The skin AGEs levels of the PDR group were significantly higher (P < 0.05) than the normal group, mild and moderate NPDR groups. It was positively correlated with DR stage, HbA1c, total cholesterol (TC), low-density lipoprotein (LDL), and urine metal analysis (UMA) (r = 0.467, 0.411, 0.413, 0.503, 0.424, P < 0.05). The skin AGEs levels of the qi and yin deficiency and collaterals stasis syndrome group were significantly higher (P < 0.05) than in the liver and kidney deficiency and eye collaterals loss groups. It was also significantly higher (P < 0.05) in yin and yang deficiency, blood stasis, and phlegm coagulation syndrome groups than in qi and yin deficiency and collaterals stasis syndrome groups.

Conclusion

There is a positive correlation between skin AGEs and DR staging in T2DM patients. Skin AGEs level is predictive for the risk of DR complications in T2DM patients and is vital in assessing DR degree per TCM syndrome type.

Advanced Glycation End Products (AGEs) and Chronic Kidney Disease: Does the Modern Diet AGE the Kidney?

Since the 1980s, chronic kidney disease (CKD) affecting all ages has increased by almost 25%. This increase may be partially attributable to lifestyle changes and increased global consumption of a “western” diet, which is typically energy dense, low in fruits and vegetables, and high in animal protein and ultra-processed foods. These modern food trends have led to an increase in the consumption of advanced glycation end products (AGEs) in conjunction with increased metabolic dysfunction, obesity and diabetes, which facilitates production of endogenous AGEs within the body. When in excess, AGEs can be pathological via both receptor-mediated and non-receptor-mediated pathways. The kidney, as a major site for AGE clearance, is particularly vulnerable to AGE-mediated damage and increases in circulating AGEs align with risk of CKD and all-cause mortality. Furthermore, individuals with significant loss of renal function show increased AGE burden, particularly with uraemia, and there is some evidence that AGE lowering via diet or pharmacological inhibition may be beneficial for CKD. This review discusses the pathways that drive AGE formation and regulation within the body. This includes AGE receptor interactions and pathways of AGE-mediated pathology with a focus on the contribution of diet on endogenous AGE production and dietary AGE consumption to these processes. We then analyse the contribution of AGEs to kidney disease, the evidence for dietary AGEs and endogenously produced AGEs in driving pathogenesis in diabetic and non-diabetic kidney disease and the potential for AGE targeted therapies in kidney disease.

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 accumulation of advanced glycation end products and cardiovascular risk in Korean patients with type 2 diabetes mellitus

Background

The formation of advanced glycation end products (AGEs) takes place during normal aging; however, their production is faster in people having diabetes. The accumulated AGEs reportedly play a role in the occurrence of various age-related disorders. Furthermore, the skin autofluorescence (SAF) technique can be used to detect accumulated AGEs levels. There are few reports on the association between skin accumulation of AGEs and risk of complications in type 2 diabetes mellitus.

Methods

In this study, we aimed to describe the association between the skin accumulation of AGEs and cardiovascular risk factors in Korean patients with type 2 diabetes. A total of 310 Korean patients with diabetes were enrolled, and the levels of AGEs were measured using SAP. Levels of fasting blood glucose (FBS), triglycerides, total cholesterol, low- and high-density lipoprotein cholesterol, proteinuria, arterial pulse wave velocity (PWV), and blood vessel age were measured using an automatic waveform analyzer. General linear models were used to identify the independent effect of AGEs after adjusting for covariates (age, weight, and duration of diabetes).

Results

The skin levels of AGEs were strongly correlated with the diabetes duration. Significant independent associations were observed for AGEs with FBS (P < 0.01), proteinuria (P < 0.001), and PWV (P < 0.001). The advanced glycated product was independently associated to the arterial pulse wave conduction velocity that is used as a representative method for measuring arteriosclerosis by analysis early cardiovascular risk factors.

Conclusion

Our results show that an increase in SAF levels in Korean patients with type 2 diabetes is associated with PWV and vein age, and thereby with arterial stiffness. Therefore, our results suggest that AGEs are associated with cardiovascular risk factors. The level of AGEs can thus be used as an indicator of cardiovascular diseases in the clinical diagnosis of patients with type 2 diabetes.

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Unclear association between skin accumulation of AGEs and T2DM complication risk.

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Study Population: Korean patients with T2DM.

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Strong correlation between skin levels of AGEs and diabetes duration.

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Independent association between AGEs and arterial pulse wave conduction velocity.

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Association between increased SAF levels in with PWV, vein age, arterial stiffness.

A 2-year longitudinal study of skeletal muscle mass in women over 40 years of age with degenerative lumbar scoliosis

PURPOSE

We investigated changes in skeletal muscle mass and bone mineral density in degenerative lumbar scoliosis (DLS) patients during a 2-year follow-up following diagnosis.

METHOD

This study included 418 Japanese women, identifying 50 patients for the DLS group (mean age 76.4 years) and 368 patients for the control group (mean age 73.4 years). Whole-body skeletal muscle mass was measured using a Bioelectrical Impedance Analyzer. Bone mineral density (BMD) was measured using DXA. Skin autofluorescence (SAF), a marker of advanced glycation end products in the skin, was measured using a spectroscope. Spinal alignment, skeletal muscle mass, BMD, grip strength, and SAF were examined and the amount of change 1 and 2 years from the initial examination for each item was compared between groups.

RESULTS

Height, body fat mass, grip strength, upper limb muscle mass, and trunk muscle mass in the DLS group were significantly lower, and lumbar spine BMD was significantly greater compared to controls at the first visit (p < 0.05). There was no significant difference in spinal alignment in the DLS group after 2 years compared with baseline. Trunk muscle mass also decreased significantly more in the DLS group (-2.7%) than in the control group (-1.1%) over the 2-year follow-up (p < 0.05).

DISCUSSION

In this study, trunk muscle mass in the DLS group decreased about 2.4 times more in 2 years compared with the control group (p < 0.05). It may be possible to clarify the mechanism of kyphoscoliosis progression in the future with large-scale longitudinal studies.

A physically active lifestyle is related to a lower level of skin autofluorescence in a large population with chronic-disease (LifeLines cohort)

BACKGROUND

Physical activity (PA) has substantial health benefits and is important in combatting chronic diseases, which have been associated with elevated levels of advanced glycation endproducts (AGEs). AGEs play a role in the aging process, and an association between PA and AGEs has been reported. We aimed to investigate the relationship between PA and AGE accumulation in a general population and in a population with chronic diseases.

METHODS

This large cross-sectional population study used data from adult participants in the LifeLines project, with participant information drawn from the LifeLines database as well data from patients with diabetes mellitus or renal and/or cardiovascular diseases. Tissue AGE accumulation was assessed non-invasively by skin-autofluorescence (SAF) using an AGE reader (DiagnOptics Technologies BV, Groningen, the Netherlands). PA was assessed using the short questionnaire to assess health-enhancing physical activity (SQUASH). Multivariate linear regression analyses were adjusted for age, body mass index, sex, and smoking status.

RESULTS

Data from 63,452 participants (general population n = 59,177, chronic disease n = 4275) were analyzed. The general population was significantly younger (43.58 ± 11.77 years, mean ± SD) and had significantly lower SAF (1.90 ± 0.42 arbitrary units (AU)) compared to the population with chronic disease (age: 55.51 ± 12.07 years; SAF: 2.27 ± 0.51 AU). In the group with chronic disease, more hours of moderate to vigorous physical activities per week were associated with lower SAF (β = -0.002, 95% confidence interval (95%CI): -0.002 to -0.001). For the general population, there was no association between hours of moderate to vigorous activity and SAF (β = 3.2  × 10^-5, 95%CI: 0.000-0.001, p = 0.742). However, there was an association in the general population between total hours of PA per week and SAF (β = 4.2 × 10^-4, 95%CI: 0.000-0.001, p < 0.001), but this association was not found in the chronic disease population (β = -3.2 × 10^-4, 95%CI: -0.001 to 0.000, p = 0.347).

CONCLUSION

Our study demonstrates that an inverse relationship exists between PA and AGE accumulation in the population with chronic disease. More hours of moderate to vigorous activity is associated with a significantly decreased SAF. More PA is associated with a lower SAF, even after adjusting for the established predictors (age, body mass index, smoking status, and sex). Our findings could help to promote health and prolong longevity.

Skin optical properties in the obese and their relation to body mass index: a review

SIGNIFICANCE

Obesity is a worldwide epidemic contributing directly to several cardiovascular risk factors including hypertension and type 2 diabetes. Wearable devices are becoming better at quantifying biomarkers relevant for the management of health and fitness. Unfortunately, both anecdotal evidence and recent studies indicate that some wearables have higher levels of error when utilized by populations with darker skin tones and high body mass index (BMI). There is an urgent need for a better evaluation of the limits of wearable health technologies when used by obese individuals.

AIMS

(1) To review the current know-how on changes due to obesity in the skin epidermis, dermis, and subcutis that could affect the skin optical properties; (2) for the green wavelength range, to evaluate the difference in absorption and scattering coefficients from the abdominal skin between individuals with and without elevated BMI. The changes include alterations in layer thickness and cell size, as well as significant differences in chromophores and scatterer content, e.g., water, hemoglobin, collagen, and lipids.

APPROACH

We have summarized literature pertaining to changes in skin and its components in obesity and report the results of our search using articles published between years 1971 and 2020. A linear model was used to demonstrate the absorption and reduced scattering coefficient of the abdominal skin of individuals with and without elevated BMI in the green wavelength range (530 to 550 nm) that is typically found in most wearables.

RESULTS

The general trends indicate a decrease in absorption for both dermis and subcutis and an increase in reduced scattering for both epidermis and dermis. At 544-nm wavelength, a typical wavelength used for photoplethysmography (PPG), the absorption coefficient's relative percentage difference between high and low BMI skin, was 49% in the subcutis, 19% in the dermis, and negligible in the epidermis, whereas the reduced scattering coefficient relative difference was 21%, 29%, and 165% respectively.

CONCLUSIONS

These findings suggest that there could be significant errors in the output of optical devices used for monitoring health and fitness if changes due to obesity are not accounted for in their design.

Avenues for post-translational protein modification prevention and therapy

Non-enzymatic post-translational modifications (nPTMs) of proteins have emerged as novel risk factors for the genesis and progression of various diseases. We now have a variety of experimental and established therapeutic strategies to target harmful nPTMs and potentially improve clinical outcomes. Protein carbamylation and glycation are two common and representative nPTMs that have gained considerable attention lately as favorable therapeutic targets with emerging clinical evidence. Protein carbamylation is associated with the occurrence of cardiovascular disease (CVD) and mortality in patients with chronic kidney disease (CKD); and advanced glycation end products (AGEs), a heterogeneous group of molecules produced in a series of glycation reactions, have been linked to various diabetic complications. Therefore, reducing the burden of protein carbamylation and AGEs is an appealing and promising therapeutic approach. This review chapter summarizes potential anti-nPTM therapy options in CKD, CVD, and diabetes along with clinical implications. Using two prime examples-protein carbamylation and AGEs-we discuss the varied preventative and therapeutic options to mitigate these pathologic nPTMs in detail. We provide in-depth case studies on carbamylation in the setting of kidney disease and AGEs in metabolic disorders, with an emphasis on the relevance to reducing adverse clinical outcomes such as CKD progression, cardiovascular events, and mortality. Overall, whether specific efforts to lower carbamylation and AGE burden will yield definitive clinical improvement in humans remains largely to be seen. However, the scientific rationale for such pursuits is demonstrated herein.

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.

Pilot study to investigate differences in middle molecules, oxidative stress and markers of peripheral vascular disease in patients treated by high flux haemodialysis and haemodiafiltration

Background

Dialysis patients have an increased risk of mortality. Recently treatment with haemodiafiltration (HDF) has been reported to reduce mortality, particularly cardiovascular mortality, compared to standard high-flux haemodialysis (HD). However, why HDF may offer a survival advantage remains to be determined. So, we conducted a pilot study to explore differences in middle-molecules, inflammation and markers of vascular disease in patients treated by HD and HDF.

Methods

Observational cross-sectional study measuring serum β2-microglobulin (β2M), Advanced Glycosylation End Products (AGEs) by skin autofluorescence (SAF), oxidative stress with ischaemia modified albumin ratio (IMAR) and peripheral vascular disease assessment using Ankle-Brachial Index (ABI), and arterial stiffness using Cardio-Ankle Vascular Index (CAVI).

Results

We studied 196 patients, mean age 69.1 ± 12.4 years, 172 (87.8%) treated by HD and 24 (12.2%) by HDF. Age, body mass index, co-morbidity and dialysis vintage were not different between HD and HDF groups. Middle molecules; β₂M (31±9.9 vs 31.2±10 ug/mL) and SAF (2.99±0.72 vs 3.0±0.84 AU), ABI (1.06±0.05 vs 1.07±0.10) and CAVI (9.34±1.55 vs 9.35±1.23) were not different, but IMAR was higher in the HD patients (38.4±14.8 vs 31.3 ± 17.4, P = 0.035)

Conclusions

In this pilot observational study, we found patients treated by HDF had lower oxidative stress as measured by IMAR, with no differences in middle molecules. Lower oxidative stress would be expected to have diverse protective effects on the cardiovascular system Although we found no differences in ABI and CAVI, future studies are required to determine whether reduced oxidative stress translates into clinically relevant differences over time.

Collagen Glycation Detected by Its Intrinsic Fluorescence

Collagen’s long half-life (in skin approximately 10 years) makes this protein highly susceptible to glycation and formation of the advanced glycation end products (AGEs). Accumulation of cross-linking AGEs in the skin collagen has several detrimental effects; thus, the opportunity for non-invasive monitoring of skin glycation is essential, especially for diabetic patients. In this paper, we report using the time-resolved intrinsic fluorescence of collagen as a biomarker of its glycation. Contrary to the traditional fluorescence intensity decay measurement at the arbitrarily selected excitation and detection wavelengths, we conducted systematic wavelength- and time-resolved measurements to achieve time-resolved emission spectra. Changes in the intrinsic fluorescence kinetics, caused by both collagen aggregation and glycation, have been detected.

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.

Neuropathy - Exponent of Accelerated Involution in Uremia: The Role of Carbamylation

Premature loss of functional integrity of the nervous system in chronic renal failure (CRF) as a consequence of persistent biological activities of the general uremic milieu is almost identical to its structural and functional involution during the process of physiological ageing, but disproportionate and independent of chronological age. In the hyperuremic status of CRF (urea - carbamide), forced carbamylation, as a non-enzymatic post-translational modification (NEPTM) of proteins and amino acids, by changing their biological properties and decreasing proteolysis capacity, represents pathogenetic potential of intensified molecular ageing and accelerated, pathological involution. Physiological predisposition and the exposure of neuropathy before complications of other organs and organ systems in CRF, due to the simultaneous and mutually pathogenetically related uremic lesion and the tissue and vascular segment of the nervous system, direct interest towards proteomic analytical techniques of quantification of carbamylated products as biomarkers of uremic neurotoxicity. Hypothetically, identical to the already established applications of other NEPTM products in practice, they have the potential of clinical methodology in the evaluation of uremic neuropathy and its contribution to the general prediction, but also to the change of the conventional CRF classification. In addition, the identification and therapeutic control of the substrate of accelerated involution, responsible for the amplification of not only neurological but also general degenerative processes in CRF, is attractive in the context of the well-known attitude towards aging.

Lens fluorescence and skin fluorescence in the Copenhagen Twin Cohort Eye Study: Covariates and heritability

Lens and skin fluorescence are related to the systemic accumulation of advanced glycation end products, which is accelerated in diabetes. We have examined lens fluorescence and skin fluorescence in healthy adult twins. The study enrolled twins aged median 59 years from a national population-based registry. Diabetic individuals were excluded from analysis. The interrelatedness between fluorescence parameters and relations between fluorescence and age, current HbA1c and smoking pack years were examined using correlation tests and mixed model linear regression analyses. Broad-sense heritability was analyzed and compared for lens fluorescence, skin fluorescence and HbA1c. Lens fluorescence and skin fluorescence were crudely interrelated (R = 0.38). In linear regression analyses, age explained a larger fraction of the variance in lens fluorescence (R2 = 32%) than in skin fluorescence (R2 = 20%), whereas HbA1c explained smaller variance fractions (R2 = 3% and 8%, respectively) followed by smoking pack years (4% and 3%, respectively). In multivariate analyses, age, HbA1c and smoking pack years combined explained more of the variance in lens fluorescence (R2 = 35%) than in skin fluorescence (R2 = 21%), but the influence of HbA1c on lens fluorescence was not statistically significant (p = .2). Age-adjusted broad-sense heritability was 85% for lens fluorescence, 53% for skin fluorescence and 71% for HbA1c in best fitting heritability models. Both fluorescence parameters increased with age, current glycemia and cumulative smoking. Lens fluorescence was found to be a predominantly heritable trait, whereas skin fluorescence was more influenced by environmental factors and closer related to current glycemia. The results suggest that skin fluorophores have a faster turn-over than lens fluorophores.

Prediction of mortality among patients with chronic kidney disease: A systematic review

BACKGROUND

Chronic kidney disease (CKD) is a common medical condition that is increasing in prevalence. Existing published evidence has revealed through regression analyses that several clinical characteristics are associated with mortality in CKD patients. However, the predictive accuracies of these risk factors for mortality have not been clearly demonstrated.

AIM

To demonstrate the accuracy of mortality predictive factors in CKD patients by utilizing the area under the receiver operating characteristic (ROC) curve (AUC) analysis.

METHODS

We searched Ovid MEDLINE, EMBASE, and the Cochrane Library for eligible articles through January 2021. Studies were included based on the following criteria: (1) Study nature was observational or conference abstract; (2) Study populations involved patients with non-transplant CKD at any CKD stage severity; and (3) Predictive factors for mortality were presented with AUC analysis and its associated 95% confidence interval (CI). AUC of 0.70-0.79 is considered acceptable, 0.80-0.89 is considered excellent, and more than 0.90 is considered outstanding.

RESULTS

Of 1759 citations, a total of 18 studies (n = 14579) were included in this systematic review. Eight hundred thirty two patients had non-dialysis CKD, and 13747 patients had dialysis-dependent CKD (2160 patients on hemodialysis, 370 patients on peritoneal dialysis, and 11217 patients on non-differentiated dialysis modality). Of 24 mortality predictive factors, none were deemed outstanding for mortality prediction. A total of seven predictive factors [N-terminal pro-brain natriuretic peptide (NT-proBNP), BNP, soluble urokinase plasminogen activator receptor (suPAR), augmentation index, left atrial reservoir strain, C-reactive protein, and systolic pulmonary artery pressure] were identified as excellent. Seventeen predictive factors were in the acceptable range, which we classified into the following subgroups: predictors for the non-dialysis population, echocardiographic factors, comorbidities, and miscellaneous.

CONCLUSION

Several factors were found to predict mortality in CKD patients. Echocardiography is an important tool for mortality prognostication in CKD patients by evaluating left atrial reservoir strain, systolic pulmonary artery pressure, diastolic function, and left ventricular mass index.

Toxin Removal and Inflammatory State Modulation during Online Hemodiafiltration Using Two Different Dialyzers (TRIAD2 Study)

Uremic toxins play a pathological role in atherosclerosis and represent an important risk factor in dialysis patients. Online hemodiafiltration (HDF) has been introduced to improve the clearance of middle- and large-molecular-weight solutes (>500 Da) and has been associated with reduced cardiovascular mortality compared to standard hemodialysis. This non-randomized, open-label observational study will explore the efficacy of two dialyzers currently used for online HDF, a polysulfone-based high-flux membrane, and a cellulose triacetate membrane, in hemodialysis patients with signs of middle-molecule intoxication or intradialytic hypotension. In particular, the two filters will be evaluated for their ability in uremic toxin removal and modulation of inflammatory status. Sixteen subjects in standard chronic bicarbonate hemodialysis requiring a switch to online HDF in view of their clinical status will be enrolled and divided into two treatment arms, according to the previous history of hypersensitivity to polysulfone/polyethersulfone dialysis filters and hypersensitivity to drugs or other allergens. Group A will consist of 16 patients without a previous history of hypersensitivity and will be treated with a polysulfone filter (Helixone FX100), and group B, also consisting of 16 patients, with a previous history of hypersensitivity and will be treated with asymmetric triacetate (ATA; SOLACEA 21-H) dialyzer. Each patient will be followed for a period of 24 months, with monthly assessments of circulating middle-weight toxins and protein-bound toxins, markers of inflammation and oxidative stress, lymphocyte subsets, activated lymphocytes, and monocytes, cell apoptosis, the accumulation of advanced glycation end-products (AGEs), variations in arterial stiffens measured by pulse wave velocity (PWV), and mortality rate. The in vitro effect on endothelial cells of uremic serum collected from patients treated with the two different dialyzers will also be investigated to examine the changes in angiogenesis, cell migration, differentiation, apoptosis and proliferative potential, and gene and protein expression profile. The expected results will be a better awareness of the different effects of polysulfone gold-standard membrane for online HDF and the new ATA membrane on the removal of uremic toxins removal and inflammation due to blood-membrane interaction.

Assessment of lens autofluorescence in patients with well-controlled essential hypertension and those with renal failure secondary to hypertension undergoing hemodialysis

PURPOSE

To compare the lens autofluorescence (AF) levels among patients with end-stage renal failure and undergoing hemodialysis secondary to hypertension, patients with well-controlled hypertension, and healthy controls.

METHOD

This study was a prospective, cross-sectional, comparative study conducted between February and April 2018. Two groups of patients and a group of healthy individuals were included in the study. The first group of patients included individuals with a renal insufficiency due to essential hypertension who underwent regular hemodialysis treatment (dialysis group). The second group included patients with well-controlled essential hypertension (hypertension group). Lens autofluorescence was measured via a scanning confocal lens fluorescence biomicroscope optical system for all participants. The measurement of fluorescence ratio is given as a numerical data. The AF results were compared in all groups.

RESULTS

The study included 87 individuals. There were 29 individuals (33.3 %) in the dialysis group, 30 (34.5 %) in the hypertension group, and 28 (32.2 %) in the healthy group. The mean fluorescence ratio(FR) was 0.20 ± 0.06, 0.20 ± 0.04, and 0.17 ± 0.04 in the dialysis, hypertension, and healthy groups respectively. There was a significant difference in the mean FR measurements between the three groups (p = .004). As a result of a binary comparison, mean FR values for patients in the dialysis group were higher (0.20 ± 0.06) than for healthy individuals (0.17 ± 0.04), which was statistically significant (p = .025). Mean FR measurements of hypertensive patients were higher (0.20 ± 0.04) than healthy individuals (0.17 ± 0.04), which was also statistically significant (p = .02). However, there was no statistically significant difference among the mean FR measurements between the hypertension and dialysis groups (p = .63).

CONCLUSION

We demonstrated that lens autofluorescence increased in patients with renal failure undergoing hemodialysis and those with well-controlled hypertension. The mean lens autofluorescence levels were significantly higher in both patient groups than the healthy control group.

Plasma Catestatin Levels and Advanced Glycation End Products in Patients on Hemodialysis

Catestatin (CST) is a pleiotropic peptide involved in cardiovascular protection with its antihypertensive and angiogenic effects. Considering that patients with end-stage renal disease (ESRD) who are undergoing hemodialysis (HD) are associated with higher cardiovascular risk, the aim of this study was to investigate plasma CST levels in HD patients, compare them to healthy controls and evaluate possible CST associations with advanced glycation end products (AGEs) and laboratory, anthropometric and clinical parameters. The study included 91 patients on HD and 70 healthy controls. Plasma CST levels were determined by an enzyme-linked immunosorbent assay in a commercially available diagnostic kit, while AGEs were determined using skin autofluorescence. Plasma CST levels were significantly higher in the HD group compared to the controls (32.85 ± 20.18 vs. 5.39 ± 1.24 ng/mL, p < 0.001) and there was a significant positive correlation between CST and AGEs (r = 0.492, p < 0.001). Furthermore, there was a significant positive correlation between plasma CST levels with both the Dialysis Malnutrition Score (r = 0.295, p = 0.004) and Malnutrition-Inflammation Score (r = 0.290, p = 0.005). These results suggest that CST could be playing a role in the complex pathophysiology of ESRD/HD and that it could affect the higher cardiovascular risk of patients on HD.

Skin autofluorescence of advanced glycation end products and mortality in affective disorders in the lifelines cohort study: A mediation analysis

OBJECTIVE

Life expectancy in patients suffering from affective disorders is considerably diminished. We investigated whether skin autofluorescence (SAF), indicating concentration of advanced glycation end products in the skin and oxidative stress, mediates the association between affective disorders and excess mortality.

METHODS

Included were 81,041 participants of the Lifelines cohort study. Presence of major depressive disorder, dysthymia, generalised anxiety disorder, panic disorder or social phobia was assessed with the Mini-International Neuropsychiatric Interview. SAF was assessed as mediator in Cox proportional hazards models for all-cause or natural-cause mortality.

RESULTS

Mortality was increased in cases with major depression compared to controls (36.4 vs. 22.5 per 100,000 person years). Partial mediation by SAF of the association between affective disorders and mortality was shown (9.0-10.5%, P<.001-.002), although attenuated by cardiometabolic parameters and history of physical illness. For major depressive disorder, partial mediation by 5.5-10.3% was shown (crude model: P<.001; fully adjusted model: P=.03).

LIMITATIONS

The relatively short duration of follow-up and the relatively young cohort resulted in a lack of power to detect an association between mortality and dysthymia, social phobia and two or more comorbid disorders.

CONCLUSION

Evidence of partial mediation by SAF of the association between affective disorders and all-cause and natural-cause mortality was demonstrated, although attenuated by health factors. For major depression, mediation by SAF was largest and remained significant after adjustment for sociodemographic and health factors, identifying oxidative stress as possible determinant of premature death.

The AGE Reader: A non-invasive method to assess long-term tissue damage

AIMS

Advanced glycation endproducts (AGEs) are sugar-modified adducts which arise during non-enzymatic glycoxidative stress. These compounds may become systemically elevated in disease states, and accumulate in tissue, especially on long-lived proteins. AGEs have been implicated in various acute, and chronic diseases, stressing the need for reliable and comprehensive measuring techniques. Measurement of AGEs in tissue such as skin requires invasive skin biopsies. The AGE Reader has been developed to assess skin autofluorescence (SAF) non-invasively using the fluorescent properties of several AGEs.

RESULTS/CONCLUSION

Various studies have shown that SAF is a useful marker of disease processes associated with oxidative stress. It is prospectively associated with the development of cardiovascular events in patients with diabetes, renal or cardiovascular disease, and it predicts diabetes, cardiovascular disease, and mortality in the general population. However, when measuring SAF in individual subjects, several factors may limit the reliability of the measurement. These include endogenous factors present in the skin that absorb emission light such as melanin in dark-skinned subjects, but also factors that lead to temporal changes in SAF such as acute diseases and strenuous physical exercise associated with glycoxidative stress. Also, exogenous factors could potentially influence SAF levels inadvertently such as nutrition, and for example the application of skin care products. This review will address the AGE Reader functionality and the endogenous, and exogenous factors which potentially influence the SAF assessment in individual subjects.

Serum and Tissue Levels of Advanced Glycation End Products and Risk of Mortality in Patients on Maintenance Hemodialysis

BACKGROUND

The relation of tissue and circulating advanced glycation end products (AGEs) with mortality in hemodialysis (HD) patients remains inconclusive. We aimed to investigate the association of serum AGEs (CML) and tissue AGEs estimated by skin autofluorescence (SAF) with all-cause and cardiovascular disease (CVD) mortality, and examine the possible modifiers for the association in HD patients with by far the largest sample size in any similar studies.

METHODS

A total of 1,634 HD patients were included from the China Cooperative Study on Dialysis (CCSD), a multicenter prospective cohort study. The primary and secondary outcomes were all-cause mortality and CVD mortality, respectively.

RESULTS

The median follow-up duration was 5.2 years. Overall, there was a positive relation of baseline SAF levels with the risk of all-cause mortality (per 1 AU increment, adjusted hazard ratio (HR), 1.30; 95% confidence interval (CI): 1.12, 1.50) and CVD mortality (per 1 AU increment, adjusted HR, 1.36; 95% CI: 1.14, 1.62). Moreover, a stronger positive association between baseline SAF (per 1 AU increment) and all-cause mortality was found in participants with shorter dialysis vintage, or lower C-reactive protein levels (Both p interactions <0.05). Nevertheless, there was no significant association between serum CML and the risk of mortality.

CONCLUSIONS

In patients undergoing long-term HD, baseline SAF, but not serum CML, was significantly associated with the risk of all-cause and CVD death.

Skin intrinsic fluorescence scores are a predictor of all-cause mortality risk in type 1 diabetes: The Epidemiology of Diabetes Complications study

AIMS

We assessed the association of skin intrinsic fluorescence (SIF) scores, as a measure of advanced glycation end-products (AGE), with all-cause mortality in type 1 diabetes (T1D).

METHODS

This is an observational retrospective study of a convenience sample from the Epidemiology of Diabetes Complications (EDC) study. AGEs were measured with a SIF score between 2007 and 2014; vital status was assessed in 2020.

RESULTS

Among 245 participants, mean age was 48.6 ± 7.4 years, median diabetes duration was 39.5 years (IQR: 34.2, 44.9), and 53.5% were female. Compared to survivors, the deceased (n = 20) were older, with higher SIF scores, longer diabetes duration, lower body mass index (BMI), and an adverse risk factor profile (all p≤0.05). Univariate Cox regression showed a marginal association between SIF score and mortality (HR: 1.1, 95% CI 0.9-1.2, p = 0.06), which persisted after adjustment for multiple daily insulin shots/pump (MDI) use (HR: 1.1, 95% CI 1.0-1.2, p = 0.04). This association was attenuated after adjustment for T1D duration, A_1c months, or estimated glomerular filtration rate (eGFR).

CONCLUSIONS

In individuals with long duration T1D, SIF scores adjusted for MDI predicted all-cause mortality, although this association was attenuated after adjustments. Given the nature of sampling and small number of events, our findings require replication.

Long-Term Morbidity and Health After Early Menopause Due to Oophorectomy in Women at Increased Risk of Ovarian Cancer: Protocol for a Nationwide Cross-Sectional Study With Prospective Follow-Up (HARMOny Study)

Background

BRCA1/2 mutation carriers are recommended to undergo risk-reducing salpingo-oophorectomy (RRSO) at 35 to 45 years of age. RRSO substantially decreases ovarian cancer risk, but at the cost of immediate menopause. Knowledge about the potential adverse effects of premenopausal RRSO, such as increased risk of cardiovascular disease, osteoporosis, cognitive dysfunction, and reduced health-related quality of life (HRQoL), is limited.

Objective

The aim of this study is to assess the long-term health effects of premenopausal RRSO on cardiovascular disease, bone health, cognitive functioning, urological complaints, sexual functioning, and HRQoL in women with high familial risk of breast or ovarian cancer.

Methods

We will conduct a multicenter cross-sectional study with prospective follow-up, nested in a nationwide cohort of women at high familial risk of breast or ovarian cancer. A total of 500 women who have undergone RRSO before 45 years of age, with a follow-up period of at least 10 years, will be compared with 250 women (frequency matched on current age) who have not undergone RRSO or who have undergone RRSO at over 55 years of age. Participants will complete an online questionnaire on lifestyle, medical history, cardiovascular risk factors, osteoporosis, cognitive function, urological complaints, and HRQoL. A full cardiovascular assessment and assessment of bone mineral density will be performed. Blood samples will be obtained for marker analysis. Cognitive functioning will be assessed objectively with an online neuropsychological test battery.

Results

This study was approved by the institutional review board in July 2018. In February 2019, we included our first participant. As of November 2020, we had enrolled 364 participants in our study.

Conclusions

Knowledge from this study will contribute to counseling women with a high familial risk of breast/ovarian cancer about the long-term health effects of premenopausal RRSO. The results can also be used to offer health recommendations after RRSO.

Trial Registration

ClinicalTrials.gov NCT03835793; https://clinicaltrials.gov/ct2/show/NCT03835793.

International Registered Report Identifier (IRRID)

DERR1-10.2196/24414

Skin autofluorescence predicts new cardiovascular disease and mortality in people with type 2 diabetes

BACKGROUND

Skin autofluorescence (SAF) is a non-invasive marker of tissue accumulation of advanced glycation endproducts (AGE). Recently, we demonstrated in the general population that elevated SAF levels predict the development of type 2 diabetes (T2D), cardiovascular disease (CVD) and mortality. We evaluated whether elevated SAF may predict the development of CVD and mortality in individuals with T2D.

METHODS

We included 2349 people with T2D, available baseline SAF measurements (measured with the AGE reader) and follow-up data from the Lifelines Cohort Study. Of them, 2071 had no clinical CVD at baseline. 60% were already diagnosed with diabetes (median duration 5, IQR 2-9 years), while 40% were detected during the baseline examination by elevated fasting blood glucose ≥7.0 mmol/l) and/or HbA1c ≥6.5% (48 mmol/mol).

RESULTS

Mean (±SD) age was 57 ± 12 yrs., BMI 30.2 ± 5.4 kg/m². 11% of participants with known T2D were treated with diet, the others used oral glucose-lowering medication, with or without insulin; 6% was using insulin alone. Participants with known T2D had higher SAF than those with newly-detected T2D (SAF Z-score 0.56 ± 0.99 vs 0.34 ± 0.89 AU, p < 0.001), which reflects a longer duration of hyperglycaemia in the former group. Participants with existing CVD and T2D had the highest SAF Z-score: 0.78 ± 1.25 AU. During a median follow-up of 3.7 yrs., 195 (7.6%) developed an atherosclerotic CVD event, while 137 (5.4%) died. SAF was strongly associated with the combined outcome of a new CVD event or mortality (OR 2.59, 95% CI 2.10-3.20, p < 0.001), as well as incidence of CVD (OR 2.05, 95% CI 1.61-2.61, p < 0.001) and death (OR 2.98, 2.25-3.94, p < 0.001) as a single outcome. In multivariable analysis for the combined endpoint, SAF retained its significance when sex, systolic blood pressure, HbA1c, total cholesterol, eGFR, as well as antihypertensive and statin medication were included. In a similar multivariable model, SAF was independently associated with mortality as a single outcome, but not with incident CVD.

CONCLUSIONS

Measuring SAF can assist in prediction of incident cardiovascular disease and mortality in individuals with T2D. SAF showed a stronger association with future CVD events and mortality than cholesterol or blood pressure levels.

Percutaneously-quantified advanced glycation end-products (AGEs) accumulation associates with low back pain and lower extremity symptoms in middle-aged low back pain patients

Advanced glycation end-products (AGEs) have been reported as a possible biomarker of ageing and metabolic diseases; however, its role in the clinical progression of these diseases remains unclear. We aimed to evaluate how AGEs are associated with clinical symptoms and comorbidities in lower back pain (LBP) patients. This prospective cohort study enrolled 636 LBP patients. They were subjected to quantified AGE (qAGE) analysis using skin autofluorescence, and their clinical symptoms and comorbidities, such as diabetes, renal failure with haemodialysis treatment, and osteoporosis, were measured. LBP, lower extremity pain, and numbness were evaluated using a visual analogue scale (VAS). The measured qAGE was significantly higher in subjects with any comorbidity. Age also showed a strong positive correlation with qAGE. qAGE and VAS for leg numbness were positively correlated. Furthermore, in LBP patients under 50-years-old, qAGE was positively correlated with VAS for LBP, lower extremity pain, and numbness. In conclusion, qAGE, as measured by skin autofluorescence measurement, was significantly higher in LBP patients with diabetes and dialysis, as well as in osteoporosis patients. Furthermore, qAGE showed potential as a biomarker for LBP, lower extremity pain, and numbness in patients under 50-years-old. If accumulated AGEs are identified at a young age, researchers should be vigilant for the development of osteoporosis and LBP-related clinical symptoms later in life.

Is skin autofluorescence (SAF) representative of dermal advanced glycation endproducts (AGEs) in dark skin? A pilot study

Aims

Non-invasively assessed skin autofluorescence (SAF) measures advanced glycation endproducts (AGEs) in the dermis. SAF correlates with dermal AGEs in Caucasians and Asians, but studies in dark-skinned subjects are lacking. In this pilot we aimed to assess whether SAF signal is representative of intrinsic fluorescence (IF) and AGE accumulation in dark skin.

Methods

Skin biopsies were obtained in 12 dark-skinned subjects (6 healthy subjects, median age 22 years; 6 diabetes mellitus (DM) subjects, 65 years). SAF was measured with the AGE Reader, IF using confocal microscopy, and AGE distribution with specific antibodies. CML and MG-H1 were quantified with UPLC-MS/MS and pentosidine with HPLC and fluorescent detection.

Results

SAF correlated with IF from the dermis (405nm, r = 0.58, p < 0.05), but not with CML (r = 0.54, p = 0.07). CML correlated with IF from the dermis (405nm, r = 0.90, p < 0.01). UV reflectance and the coefficient of variation of SAF were negatively correlated (r = -0.80, p < 0.01). CML and MG-H1 were predominantly present around blood vessels, in collagen and fibroblasts in the dermis.

Conclusion

This proof of concept study is the first to compare non-invasive SAF with AGE levels measured in skin biopsies in dark-skinned subjects. SAF did not correlate with individual AGEs from biopsies, but was associated with IF. However, the intra-individual variance was high, limiting its application in dark-skinned subjects on an individual basis.

Skin autofluorescence of advanced glycation end products and course of affective disorders in the lifelines cohort study, a prospective investigation

BACKGROUND

Skin autofluorescence (SAF), indicating concentration of advanced glycation end products in the skin and oxidative stress, is cross-sectionally associated with affective disorders. Prospective studies of oxidative stress markers will help to clarify the pathophysiological role of oxidative stress.

METHODS

Data of a population-based cohort study were used. Presence of major depressive disorder, dysthymia, generalised anxiety disorder, panic disorder or social phobia was assessed at baseline and at 5-year follow-up with the Mini-International Neuropsychiatric Interview. Associations between SAF at baseline and incidence and persistence/recurrence of affective disorders were assessed with logistic regression.

RESULTS

Of 43,267 participants with no disorder at baseline, 2885 (6.7%) developed an incident disorder during follow-up. In 1360 of 3648 participants (37.3%) with an affective disorder at baseline, a persisting/recurrent disorder was present at follow-up. A modest association existed between SAF and incident affective disorders (OR=1.07 [95%CI 1.03-1.12], P<.001), specifically major depressive disorder (OR=1.11 [95%CI 1.04-1.19], P=.003); this association lost statistical significance after adjustment for sociodemographic factors. Associations between SAF and persistence/recurrence were not significant.

LIMITATIONS

Many confounders might also act as intermediate: extensive adjustment for confounders caused overfitting and possibly masked effects of SAF on course of affective disorders. Relatively small sample sizes for analyses of SAF and persistence/recurrence of affective disorders resulted in a low power.

CONCLUSIONS

Increased SAF modestly raises the odds of incident affective disorders, particularly major depressive disorder, providing evidence that oxidative stress plays a role in subsequent occurrence of affective disorders. However, significance of effects faded after adjustment for socioeconomic status.

Skin Autofluorescence and Carotid Intima-Media Thickness Evaluation Following Bariatric Surgery in Patients with Severe Obesity

PURPOSE

Advanced glycation end product (AGE) is a marker of metabolic memory. Accumulated AGEs in skin collagen measured with skin autofluorescence (SAF) was found to be associated with subclinical atherosclerosis. We aimed to evaluate SAF and carotid intima-media thickness (CIMT) and its association with clinical and biochemical parameters in severely obese patients before and after bariatric surgery.

MATERIALS AND METHODS

In this observational study, 432 morbid obese patients evaluated before and after 6 and 12 months of bariatric surgery for metabolic and anthropometric parameters, CIMT and SAF. SAF was assessed in the forearm with an AGE Reader.

RESULTS

SAF measurements were higher in diabetic (2.04 ± 0.52 AU) obese patients compared to non-diabetic (1.78 ± 0.40 AU) obese patients (p < 0.0001). Although bariatric surgery-induced weight loss resulted in a decrease in CIMT in the 6th and 12th months compared to baseline, weight loss and metabolic improvements were not associated with a parallel decrease in SAF measurements. SAF measurements were positively correlated with body mass index (r 0.527, p < 0.0001), HbA1c (r 0.362, p < 0.0001), and CIMT (r 0.319, p < 0.0001). Multivariate analysis showed the presence of diabetes (but not BMI, age, and sex) was independently associated with SAF (R² = 7.62%), and the presence of diabetes, low-density cholesterol, and systolic blood pressure were independently associated with CIMT measurements (R² = 21.7%).

CONCLUSION

Bariatric surgery-induced weight loss and metabolic improvement were found to be associated with improvement in CIMT, while skin AGE accumulation was not regressed in the first year of surgery.

Biophotonics methods for functional monitoring of complications of diabetes mellitus

The prevalence of diabetes complications is a significant public health problem with a considerable economic cost. Thus, the timely diagnosis of complications and prevention of their development will contribute to increasing the length and quality of patient life, and reducing the economic costs of their treatment. This article aims to review the current state-of-the-art biophotonics technologies used to identify the complications of diabetes mellitus and assess the quality of their treatment. Additionally, these technologies assess the structural and functional properties of biological tissues, and they include capillaroscopy, laser Doppler flowmetry and hyperspectral imaging, laser speckle contrast imaging, diffuse reflectance spectroscopy and imaging, fluorescence spectroscopy and imaging, optical coherence tomography, optoacoustic imaging and confocal microscopy. Recent advances in the field of optical noninvasive diagnosis suggest a wider introduction of biophotonics technologies into clinical practice and, in particular, in diabetes care units.