Advanced Glycation End Product Accumulation Is Associated With Low Skeletal Muscle Mass, Weak Muscle Strength, and Reduced Bone Density: The Nagahama Study

A map of glycation and glycoxidation sites in collagen I of human cortical bone: Effects of sex and type 2 diabetes

Complications of diabetes is a major health problem affecting multiple organs including bone, where the chronic disease increases the risk of fragility fractures. One hypothesis suggests a pathogenic role for hyperglycemia-induced modification of proteins, a.k.a. advanced glycation end products (AGEs), resulting in structural and functional damage to bone extracellular matrix (ECM). Evidence supporting this hypothesis has been limited by the lack of comprehensive information about the location of AGEs that accumulate in vivo at specific sites within the proteins of bone ECM. Analyzing extracts from cortical bone of cadaveric femurs by liquid chromatography tandem mass spectrometry, we generated a quantitative AGE map of human collagen I for male and female adult donors with and without diabetes. The map describes the chemical nature, sequence position, and levels of four major physiological AGEs, e.g. carboxymethyllysine, and an AGE precursor fructosyllysine within the collagen I triple-helical region. The important features of the map are: 1) high map reproducibility in the individual bone extracts, i.e. 20 male and 20 female donors; 2) localization of modifications to distinct clusters: 10 clusters containing 34 AGE sites in male donors and 9 clusters containing 28 sites in female donors; 3) significant increases in modification levels in diabetes at multiple sites: 26 out of 34 sites in males and in 17 out of 28 sites in females; and 4) generally higher modification levels in male vs. female donors. Moreover, the AGE levels at multiple individual sites correlated with total bone pentosidine levels in male but not in female donors. Molecular dynamics simulations and molecular modeling predicted significant impact of modifications on solvent exposure, charge distribution, and hydrophobicity of the triple helix as well as disruptions to the structure of collagen I fibril. In summary, the AGE map of collagen I revealed diabetes-induced, sex-specific non-enzymatic modifications at distinct triple helical sites that can disrupt collagen structure, thus proposing a specific mechanism of AGE contribution to diabetic complications in human bone.

Cellular Senescence: The Driving Force of Musculoskeletal Diseases

The aging of the world population is closely associated with an increased prevalence of musculoskeletal disorders, such as osteoporosis, sarcopenia, and osteoarthritis, due to common genetic, endocrine, and mechanical risk factors. These conditions are characterized by degeneration of bone, muscle, and cartilage tissue, resulting in an increased risk of fractures and reduced mobility. Importantly, a crucial role in the pathophysiology of these diseases has been proposed for cellular senescence, a state of irreversible cell cycle arrest induced by factors such as DNA damage, telomere shortening, and mitochondrial dysfunction. In addition, senescent cells secrete pro-inflammatory molecules, called senescence-associated secretory phenotype (SASP), which can alter tissue homeostasis and promote disease progression. Undoubtedly, targeting senescent cells and their secretory profiles could promote the development of integrated strategies, including regular exercise and a balanced diet or the use of senolytics and senomorphs, to improve the quality of life of the aging population. Therefore, our review aimed to highlight the role of cellular senescence in age-related musculoskeletal diseases, summarizing the main underlying mechanisms and potential anti-senescence strategies for the treatment of osteoporosis, sarcopenia, and osteoarthritis.

Unraveling the molecular and immunological landscape: Exploring signaling pathways in osteoporosis

Osteoporosis, characterized by compromised bone density and microarchitecture, represents a significant global health challenge, particularly in aging populations. This comprehensive review delves into the intricate signaling pathways implicated in the pathogenesis of osteoporosis, providing valuable insights into the pivotal role of signal transduction in maintaining bone homeostasis. The exploration encompasses cellular signaling pathways such as Wnt, Notch, JAK/STAT, NF-κB, and TGF-β, all of which play crucial roles in bone remodeling. The dysregulation of these pathways is a contributing factor to osteoporosis, necessitating a profound understanding of their complexities to unveil the molecular mechanisms underlying bone loss. The review highlights the pathological significance of disrupted signaling in osteoporosis, emphasizing how these deviations impact the functionality of osteoblasts and osteoclasts, ultimately resulting in heightened bone resorption and compromised bone formation. A nuanced analysis of the intricate crosstalk between these pathways is provided to underscore their relevance in the pathophysiology of osteoporosis. Furthermore, the study addresses some of the most crucial long non-coding RNAs (lncRNAs) associated with osteoporosis, adding an additional layer of academic depth to the exploration of immune system involvement in various types of osteoporosis. Finally, we propose that SKP1 can serve as a potential biomarker in osteoporosis.

Methylglyoxal reduces resistance exercise-induced protein synthesis and anabolic signaling in rat tibialis anterior muscle

Resistance exercise provides significant benefits to skeletal muscle, including hypertrophy and metabolic enhancements, supporting overall health and disease management. However, skeletal muscle responsiveness to resistance exercise is significantly reduced in conditions such as aging and diabetes. Recent reports suggest that glycation stress contributes to muscle atrophy and impaired exercise-induced muscle adaptation; however, its role in the muscle response to resistance exercise remains unclear. Therefore, in this study, we investigated whether methylglyoxal (MGO), a key factor in glycation stress, affects the acute responsiveness of skeletal muscles to resistance exercise, focusing on protein synthesis and the key signaling molecules. This study included 12 8-week-old male Sprague-Dawley rats divided into two groups: one received 0.5% MGO-supplemented drinking water (MGO group) and the other received regular water (control group). After 10 weeks, the left tibialis anterior muscle of each rat was subjected to electrical stimulation (ES) to mimic resistance exercise, with the right muscle serving as a non-stimulated control. Muscle protein-synthesis rates were evaluated with SUnSET, and phosphorylation levels of key signaling molecules (p70S6K and S6rp) were quantified using western blotting. In the control group, stimulated muscles exhibited significantly increased muscle protein synthesis and phosphorylation levels of p70S6K and S6rp. In the MGO group, these increases were attenuated, indicating that MGO treatment suppresses the adaptive response to resistance exercise. MGO diminishes the skeletal muscle's adaptive response to ES-simulated resistance exercise, affecting both muscle protein synthesis and key signaling molecules. The potential influence of glycation stress on the effectiveness of resistance exercise or ES emphasizes the need for individualized interventions in conditions of elevated glycation stress, such as diabetes and aging.

Frailty in patients on dialysis

Frailty is a condition that is frequently observed among patients undergoing dialysis. Frailty is characterized by a decline in both physiological state and cognitive state, leading to a combination of symptoms, such as weight loss, exhaustion, low physical activity level, weakness, and slow walking speed. Frail patients not only experience a poor quality of life, but also are at higher risk of hospitalization, infection, cardiovascular events, dialysis-associated complications, and death. Frailty occurs as a result of a combination and interaction of various medical issues in patients who are on dialysis. Unfortunately, frailty has no cure. To address frailty, a multifaceted approach is necessary, involving coordinated efforts from nephrologists, geriatricians, nurses, allied health practitioners, and family members. Strategies such as optimizing nutrition and chronic kidney disease-related complications, reducing polypharmacy by deprescription, personalizing dialysis prescription, and considering home-based or assisted dialysis may help slow the decline of physical function over time in subjects with frailty. This review discusses the underlying causes of frailty in patients on dialysis and examines the methods and difficulties involved in managing frailty among this group.

Prediabetes and diabetes were attributed to the prevalence and severity of sarcopenia in middle-aged and elderly adults

BACKGROUND

Sarcopenia and diabetes are both prevalent health problems worldwide. However, little is known about the relationship between prediabetes and the prevalence and severity of sarcopenia. Therefore, the current study aimed to explore the association between glucose status and the components of sarcopenia, including low muscle mass (LMM), low muscle strength (LMS) and low gait speed (LGS) in US adults.

METHODS

Data from the 1999 to 2002 National Health and Nutrition Examination Survey (NHANES) were analyzed. A total of 4002 participants aged ≥ 50 years with available information on glucose status (NGR: 1939 cases; prediabetes: 1172 cases; diabetes: 891 cases) and sarcopenia were included in this study. Sarcopenia was defined according to the Foundation for National Institute of Health criteria. Muscle mass, muscle strength and gait speed were used to evaluate sarcopenia and its severity. Weighed multivariable logistic regression were used to explore the association between glucose status and the components of sarcopenia. The hypothetical population attributable fraction (PAF) for the glucose status was also calculated.

RESULTS

The mean age of the cohort was 63.01 ± 9.89 years, with 49.4% being male. Multiple logistic regression analysis suggested that diabetes was an independent risk factor for sarcopenia (OR = 5.470, 95% CI 1.551-19.296) and showed a marginal association with severe sarcopenia (OR = 10.693, 95% CI 0.955-119.73) compared to NGR in men, but not in women. Additionally, prediabetes was independently associated with severe sarcopenia (OR = 3.647, 95% CI 1.532-8.697), LMS (OR = 1.472, 95% CI 1.018-2.127) and LGS (OR = 1.673, 95% CI 1.054-2.655) in the entire cohort. When stratifying by gender, we further observed that prediabetes was significantly associated with LMS in men (OR = 1.897, 95% CI 1.019-3.543) and related to LMM (OR = 3.174, 95% CI 1.287-7.829) and LGS (OR = 2.075, 95% CI 1.155-3.727) in women. HbA1c was positively associated with the prevalence of sarcopenia in men (OR = 1.993, 95% CI 1.511-2.629). PAF showed that diabetes accounted for 16.3% of observed sarcopenia cases. Maintaining NGR in the entire population could have prevented 38.5% of sarcopenia cases and 50.9% of severe sarcopenia cases.

CONCLUSIONS

Prediabetes and diabetes were independently associated with the prevalence and severity of sarcopenia in US population. Slowing down the progression of hyperglycemia could have prevented a significant proportion of sarcopenia cases.

Aging-Related Sarcopenia: Metabolic Characteristics and Therapeutic Strategies

The proportion of the elderly population is gradually increasing as a result of medical care advances, leading to a subsequent surge in geriatric diseases that significantly impact quality of life and pose a substantial healthcare burden. Sarcopenia, characterized by age-related decline in skeletal muscle mass and quality, affects a considerable portion of older adults, particularly the elderly, and can result in adverse outcomes such as frailty, fractures, bedridden, hospitalization, and even mortality. Skeletal muscle aging is accompanied by underlying metabolic changes. Therefore, elucidating these metabolic profiles and specific mechanisms holds promise for informing prevention and treatment strategies for sarcopenia. This review provides a comprehensive overview of the key metabolites identified in current clinical studies on sarcopenia and their potential pathophysiological alterations in metabolic activity. Besides, we examine potential therapeutic strategies for sarcopenia from a perspective focused on metabolic regulation.

Association of sarcopenia with osteoporosis in Chinese patients with type 2 diabetes

BACKGROUND

People with type 2 diabetes mellitus (T2DM) present a higher tendency to develop sarcopenia and osteoporosis compared with the normal population. Currently, osteoporosis screening has been frequently performed among T2DM patients, but sarcopenia screening is relatively less, and the association between the two diseases remains unclear. Herein, this study aims to determine the association between sarcopenia and osteoporosis in Chinese T2DM patients.

METHODS

This was a retrospective study of 678 patients with T2DM in the First Affiliated Hospital of Wenzhou Medical University. The bone mineral density (BMD) and muscle mass were measured by using dual-energy X-ray absorptiometry scanning. The diagnostic criteria of sarcopenia referred to the consensus by the Asia Working Group for Sarcopenia (AWGS).

RESULT

Among T2DM patients, the proportion of the sarcopenia population complicated with osteoporosis was higher than that of the non-sarcopenia (30.9% vs. 8.6% in men and 46.9% vs. 33.9% in women), but only significantly in men. The BMD of the hip and femoral neck was positively correlated with skeletal muscle mass index (SMI), grip strength, and gait speed (P < 0.01). After adjusting all covariates, the association between sarcopenia and BMD showed odds ratios of 0.43 (95% CI:0.28-0.66) for the femoral neck and 0.49 (95% CI:0.32-0.73) for the hip.

CONCLUSIONS

The BMD of the hip and femoral neck in T2DM patients is related to sarcopenia-related indicators and represents an independent protective factor for sarcopenia. To reduce the risk of falls, fractures, and weakness, it is necessary to take sarcopenia assessment in people with T2DM and osteopenia/osteoporosis.

Mechanism of traditional Chinese medicine in elderly diabetes mellitus and a systematic review of its clinical application

Objective: Affected by aging, the elderly diabetes patients have many pathological characteristics different from the young people, including more complications, vascular aging, cognitive impairment, osteoporosis, and sarcopenia. This article will explore their pathogenesis and the mechanism of Traditional Chinese medicine (TCM) intervention, and use the method of systematic review to evaluate the clinical application of TCM in elderly diabetes. Method: Searching for randomized controlled trials (RCTs) published from January 2000 to November 2023 in the following databases: Web of Science, Pubmed, Embase, Cochrane Library, Sinomed, China National Knowledge Internet, Wanfang and VIP. They were evaluated by three subgroups of Traditional Chinese Prescription, Traditional Chinese patent medicines and Traditional Chinese medicine extracts for their common prescriptions, drugs, adverse reactions and the quality of them. Results and Conclusion: TCM has the advantages of multi-target and synergistic treatment in the treatment of elderly diabetes. However, current clinical researches have shortcomings including the inclusion of age criteria and diagnosis of subjects are unclear, imprecise research design, non-standard intervention measures, and its safety needs further exploration. In the future, the diagnosis of elderly people with diabetes needs to be further clarified. Traditional Chinese patent medicines included in the pharmacopoeia can be used to conduct more rigorous RCTs, and then gradually standardize the traditional Chinese medicine prescriptions and traditional Chinese medicine extracts, providing higher level evidence for the treatment of elderly diabetes with traditional Chinese medicine.

Prediabetes-Associated Changes in Skeletal Muscle Function and Their Possible Links with Diabetes: A Literature Review

The skeletal muscle plays a critical role in regulating systemic blood glucose homeostasis. Impaired skeletal muscle glucose homeostasis associated with type 2 diabetes mellitus (T2DM) has been observed to significantly affect the whole-body glucose homeostasis, thereby resulting in other diabetic complications. T2DM does not only affect skeletal muscle glucose homeostasis, but it also affects skeletal muscle structure and functional capacity. Given that T2DM is a global health burden, there is an urgent need to develop therapeutic medical therapies that will aid in the management of T2DM. Prediabetes (PreDM) is a prominent risk factor of T2DM that usually goes unnoticed in many individuals as it is an asymptomatic condition. Hence, research on PreDM is essential because establishing diabetic biomarkers during the prediabetic state would aid in preventing the development of T2DM, as PreDM is a reversible condition if it is detected in the early stages. The literature predominantly documents the changes in skeletal muscle during T2DM, but the changes in skeletal muscle during prediabetes are not well elucidated. In this review, we seek to review the existing literature on PreDM- and T2DM-associated changes in skeletal muscle function.

Role of SIRT3 in bone homeostasis and its application in preventing and treating bone diseases

Bone homeostasis refers to the balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption and the maintenance of stable bone mass. SIRT3 is a class of mitochondrial protein deacetylase that influences various mitochondrial functions and is involved in the mechanisms underlying resistance to aging; regulation of bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts; and development of osteoporosis, osteoarthritis, and other bone diseases. Moreover, exercise affects bones through SIRT3. Thus, studies on SIRT3 may provide insights for the treatment of bone diseases. Although SIRT3 can exert multiple effects on bone, the specific mechanism by which it regulates bone homeostasis remains unclear. By evaluating the relevant literature, this review discusses the structure and function of SIRT3, reveals the role and associated mechanisms of SIRT3 in regulating bone homeostasis and mediating bone health during exercise, and highlights the potential pharmacological value of SIRT3 in treating bone diseases.

A comprehensive review on the risks assessment and treatment options for Sarcopenia in people with diabetes

Objectives

This comprehensive review aims to examine the reciprocal interplay between Type 2 diabetes mellitus (T2DM) and sarcopenia, identify prevailing research gaps, and discuss therapeutic approaches and measures to enhance healthcare practices within hospital settings.

Methods

A thorough literature review was conducted to gather relevant studies and articles on the relationship between T2DM and sarcopenia. Various databases were searched, including Google Scholar, PubMed, Scopus, and Science Direct databases. The search terms included T2DM, sarcopenia, inflammation, insulin resistance, advanced glycation end products, oxidative stress, muscle dimensions, muscle strength, muscle performance, aging, nutrition, hormone levels, and physical activity. The collected articles were critically analysed to extract key findings and identify gaps in current research.

Results

The prevalence and incidence of metabolic and musculoskeletal disorders, notably T2DM and sarcopenia, have surged in recent years. T2DM is marked by inflammation, insulin resistance, accumulation of advanced glycation end products, and oxidative stress, while sarcopenia involves a progressive decline in skeletal muscle mass and function. The review underscores the age-related correlation between sarcopenia and adverse outcomes like fractures, falls, and mortality. Research gaps regarding optimal nutritional interventions for individuals with T2DM and sarcopenia are identified, emphasizing the necessity for further investigation in this area.

Conclusions

The reciprocal interplay between T2DM and sarcopenia holds significant importance. Further research is warranted to address knowledge gaps, particularly in utilizing precise measurement tools during clinical trials. Lifestyle modifications appear beneficial for individuals with T2DM and sarcopenia. Additionally, practical nutritional interventions require investigation to optimize healthcare practices in hospital settings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01262-w.

Association between serum 25-hydroxyvitamin D and fasting blood glucose in osteoporosis patients

Osteoporosis (OP) is often associated with other complications, such as impaired glucose homeostasis. Vitamin D deficiency is common and has been linked to bone metabolism and the regulation of blood sugar levels. The aim of this study was to evaluate the independent relationship between serum 25-hydroxyvitamin D (25[OH]D) and fasting blood glucose levels (FBG) in a group of patients diagnosed with OP. This is a retrospective cross-sectional study from a prospectively collected database at our tertiary referral center. Consecutive 2084 OP patients who were hospitalization were finally analyzed in this study. FBG is the dependent variable, serum 25(OH)D level of OP patients is exposure variable of this study. There was a linear significantly negative association between serum 25(OH)D and FBG (β, - 0.02; 95% CI - 0.03 to - 0.01; P = 0.0011) in the fully adjusted models. Specifically, when serum 25(OH)D level was less than 23.39 ng/mL, FBG decreased by 0.04 mmol/L for every 1 ng/mL increase of serum 25(OH)D level. When serum 25(OH)D was greater than 23.39 ng/ mL, the negative association was insignificant (P = 0.9616). If the association is confirmed, the clinical management of blood glucose in OP patients with serum 25(OH)D deficiency has instructive implications.

Molecular and Cellular Mechanisms of Osteoporosis

Osteoporosis is a widespread systemic disease characterized by a decrease in bone mass and an imbalance of the microarchitecture of bone tissue. Experimental and clinical studies devoted to investigating the main pathogenetic mechanisms of osteoporosis revealed the important role of estrogen deficiency, inflammation, oxidative stress, cellular senescence, and epigenetic factors in the development of bone resorption due to osteoclastogenesis, and decreased mineralization of bone tissue and bone formation due to reduced function of osteoblasts caused by apoptosis and age-depended differentiation of osteoblast precursors into adipocytes. The current review was conducted to describe the basic mechanisms of the development of osteoporosis at molecular and cellular levels and to elucidate the most promising therapeutic strategies of pathogenetic therapy of osteoporosis based on articles cited in PubMed up to September 2023.

Associations Among Tooth Loss, Periodontitis, and Carotid Intima-Media Thickness: the Nagahama Study

AIMS

This study aimed to clarify the relationships among tooth loss, periodontal condition, and subclinical atherosclerosis from the aspect of intensity, extent, and duration of inflammation.

METHODS

This cross-sectional study included 9,778 people from the Nagahama Study, a large-scale, general population-based study conducted in Japan. The number of teeth and periodontal status, including the attachment level (AL) and pocket depth (PD) of representative teeth from six regions, were evaluated by dentists. The maximum intima-media thickness (IMT) of the common carotid artery was used as an index of atherosclerosis.

RESULTS

In the multivariate analysis adjusted for conventional risk factors, a large number of missing teeth (＜9 remaining teeth), which related to long-lasting inflammation indicative of the highest stage of periodontitis, was identified as an independent determinant of IMT in a general population (coefficient: 0.042; 95% confidence interval [CI]: 0.016 to 0.068). The presence of two or more regions with an AL ≥4 mm, which is indicative of the progressing, long-lasting stages of periodontal inflammation, was also independently associated with IMT (coefficient: 0.016; 95% CI: 0.004 to 0.028). On the contrary, PD, a measure of the early and reversible phases of periodontal inflammation, and loss of AL in the group without tooth loss were not significantly associated with IMT, because of the limited degree of accumulated periodontitis.

CONCLUSION

The present results suggest that the association between periodontitis and atherosclerosis depends on the inflammation intensity, extent, and duration.

Repurposing Drugs for Diabetes Mellitus as Potential Pharmacological Treatments for Sarcopenia - A Narrative Review

Sarcopenia, the age-related loss of muscle strength and mass or quality, is a common condition with major adverse consequences. Although the pathophysiology is incompletely understood, there are common mechanisms between sarcopenia and the phenomenon of accelerated ageing seen in diabetes mellitus. Drugs currently used to treat type 2 diabetes mellitus may have mechanisms of action that are relevant to the prevention and treatment of sarcopenia, for those with type 2 diabetes and those without diabetes. This review summarises shared pathophysiology between sarcopenia and diabetes mellitus, including the effects of advanced glycation end products, mitochondrial dysfunction, chronic inflammation and changes to the insulin signalling pathway. Cellular and animal models have generated intriguing, albeit mixed, evidence that supports possible beneficial effects on skeletal muscle function for some classes of drugs used to treat diabetes, including metformin and SGLT2 inhibitors. Most human observational and intervention evidence for the effects of these drugs has been derived from populations with type 2 diabetes mellitus, and there is a need for intervention studies for older people with, and at risk of, sarcopenia to further investigate the balance of benefit and risk in these target populations. Not all diabetes treatments will be safe to use in those without diabetes because of variable side effects across classes. However, some agents [including glucagon-like peptide (GLP)-1 receptor agonists and SGLT2 inhibitors] have already demonstrated benefits in populations without diabetes, and it is these agents, along with metformin, that hold out the most promise for further investigation in sarcopenia.

Low Muscle Mass Is Associated with Poorer Glycemic Control and Higher Oxidative Stress in Older Patients with Type 2 Diabetes

Body composition changes that occur during aging, such as loss of lean mass, are unfavorable at metabolic level and they can explain, in part, the appearance of certain age-associated diseases such as type 2 diabetes (T2D). Separately, T2D is associated with an increase in oxidative stress (OS) which negatively affects skeletal muscle. Our aim was to study the differences in clinical and nutritional parameters, disease control, and OS in a cohort of older patients with T2D classified according to the amount of lean mass they had. We included 100 adults older than 65 years with T2D. We found that women with low fat-free mass and muscle mass have worse T2D metabolic control. Moreover, the patients with a low percentile of muscle mass present a high value of OS. The study shows that the presence of low lean mass (LM) in the geriatric population diagnosed with T2D is associated with poorer glycemic control and greater OS.

PTP1B knockdown alleviates BMSCs senescence via activating AMPK-mediated mitophagy and promotes osteogenesis in senile osteoporosis

The senescence of bone marrow mesenchymal stem cells (BMSCs) is the basis of senile osteoporosis (SOP). Targeting BMSCs senescence is of paramount importance for developing anti-osteoporotic strategy. In this study, we found that protein tyrosine phosphatase 1B (PTP1B), an enzyme responsible for tyrosine dephosphorylation, was significantly upregulated in BMSCs and femurs with advancing chronological age. Therefore, the potential role of PTP1B in BMSCs senescence and senile osteoporosis was studied. Firstly, significantly upregulated PTP1B expression along with impaired osteogenic differentiation capacity was observed in D-galactose (D-gal)-induced BMSCs and naturally-aged BMSCs. Furthermore, PTP1B silencing could effectively alleviate senescence, improve mitochondrial dysfunction, and restore osteogenic differentiation in aged BMSCs, which was attributable to enhanced mitophagy mediated by PKM2/AMPK pathway. In addition, hydroxychloroquine (HCQ), an autophagy inhibitor, significantly reversed the protective effects from PTP1B knockdown. In SOP animal model, transplantation of LV^sh-PTP1B-transfected D-gal-induced BMSCs harvested double protective effects, including increased bone formation and reduced osteoclastogenesis. Similarly, HCQ treatment remarkably suppressed osteogenesis of LV^sh-PTP1B-transfected D-gal-induced BMSCs in vivo. Taken together, our data demonstrated that PTP1B silencing protects against BMSCs senescence and mitigates SOP via activating AMPK-mediated mitophagy. Targeting PTP1B may represent a promising interventional strategy to attenuate SOP.

A Role for Advanced Glycation End Products in Molecular Ageing

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

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

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

Advanced glycation end products inhibit the osteogenic differentiation potential of adipose-derived stem cells in mice through autophagy

BACKGROUND

Diabetes mellitus (DM) microenvironment will accelerate the accumulation of Advanced glycation end products (AGEs), adipose-derived stem cells (ASCs) have poor osteogenesis in the DM microenvironment. Studies suggest autophagy plays a vital role in osteogenesis, but the mechanism of the altered osteogenic potential of ASCs has not been elucidated. Bone tissue engineering by ASCs is widely used in the treatment of bone defects with diabetic osteoporosis (DOP). Therefore, it is meaningful to explore the effect of AGEs on the osteogenic differentiation potential of ASCs and its potential mechanism for the repair of bone defects in DOP.

MATERIALS AND METHODS

ASCs in C57BL/6 mice were isolated, cultured, then treated with AGEs, subsequently, cell viability and proliferation were detected through Cell Counting Kit 8 assay. 3-Methyladenine (3-MA), an autophagic inhibitor used to inhibit autophagic levels. Rapamycin (Rapa), an autophagy activator that further activated autophagy levels by inhibiting mTOR.The osteogenesis and autophagy changes of ASCs were analyzed by flow cytometry, qPCR, western blot, immunofluorescence, alkaline phosphatase (ALP) and alizarin red staining.

RESULTS

AGEs reduced the autophagy level and osteogenic potential of ASCs. After 3-MA reduced autophagy, the osteogenic potential of ASCs also decreased. AGEs co-treatment with 3-MA, the levels of osteogenesis and autophagy reduced more significantly. When autophagy was activated by Rapa, it was found that it could rescue the reduced osteogenic potential of AGEs.

CONCLUSIONS

AGEs reduce the osteogenic differentiation potential of ASCs through autophagy, and may provide a reference for the treatment of bone defects with diabetes osteoporosis.

Post-translational regulation of muscle growth, muscle aging and sarcopenia

Skeletal muscle makes up 30-40% of the total body mass. It is of great significance in maintaining digestion, inhaling and exhaling, sustaining body posture, exercising, protecting joints and many other aspects. Moreover, muscle is also an important metabolic organ that helps to maintain the balance of sugar and fat. Defective skeletal muscle function not only limits the daily activities of the elderly but also increases the risk of disability, hospitalization and death, placing a huge burden on society and the healthcare system. Sarcopenia is a progressive decline in muscle mass, muscle strength and muscle function with age caused by environmental and genetic factors, such as the abnormal regulation of protein post-translational modifications (PTMs). To date, many studies have shown that numerous PTMs, such as phosphorylation, acetylation, ubiquitination, SUMOylation, glycosylation, glycation, methylation, S-nitrosylation, carbonylation and S-glutathionylation, are involved in the regulation of muscle health and diseases. This article systematically summarizes the post-translational regulation of muscle growth and muscle atrophy and helps to understand the pathophysiology of muscle aging and develop effective strategies for diagnosing, preventing and treating sarcopenia.

Noninvasive Skin Autofluorescence of Advanced Glycation End Products for Detecting Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine

STUDY DESIGN

A single-center prospective observational study.

OBJECTIVE

The aim was to clarify the usefulness of assessing advanced glycation end products (AGEs) by noninvasive skin autofluorescence in patients with ossification of the posterior longitudinal ligament (OPLL).

SUMMARY OF BACKGROUND DATA

AGE accumulation is associated with various systemic disorders, including aging, diabetes mellitus, and obesity. AGEs have also been associated with OPLL, but their assessment by noninvasive skin autofluorescence has not been yet studied in these patients.

MATERIALS AND METHODS

We enrolled patients with degenerative spinal spondylosis and divided them into non-OPLL and OPLL groups. The OPLL group was further subdivided into cervical OPLL (C-OPLL) and thoracic OPLL (T-OPLL) groups. We compared patients' characteristics, serum laboratory data (i.e. hemoglobin A1c, total cholesterol, creatinine, and estimated glomerular filtration rate), and the skin autofluorescence intensity of AGEs (the AGE score) between the non-OPLL and OPLL groups and among the non-OPLL, C-OPLL, T-OPLL groups. Finally, the association of the AGE score with the presence of C-OPLL or T-OPLL was assessed by multinomial logistic regression.

RESULTS

Among the 240 eligible patients, 102 were in the non-OPLL group and 138 were in the OPLL group (92 with C-OPLL and 46 with T-OPLL). We observed no significant difference in the AGE score between the non-OPLL and OPLL groups, but when comparing the score among the non-OPLL, C-OPLL, and T-OPLL groups, we found that the T-OPLL group had a significantly higher AGE score. The results of multinomial regression analysis showed that a higher AGE score was significantly associated with T-OPLL (odds ratio: 1.46; 95% CI: 1.01-2.11; P=0.044).

CONCLUSION

The AGE score determined by noninvasive skin autofluorescence could help to screen for OPLL in the thoracic spine.

Metabolomics analysis reveals serum biomarkers in patients with diabetic sarcopenia

INTRODUCTION

Diabetic sarcopenia (DS) is characterized by muscle atrophy, slower nerve conduction, reduced maximum tension generated by skeletal muscle contraction, and slower contraction rate. Hence, DS can cause limb movement degeneration, slow movement, reduced balance, reduced metabolic rate, falls, fractures, etc. Moreover, the relevant early biological metabolites and their pathophysiological mechanism have yet to be characterized.

METHOD

The current cross-sectional study employed serum metabolomics analysis to screen potential noninvasive biomarkers in patients with diabetic sarcopenia. A total of 280 diabetic patients were enrolled in the study (n = 39 sarcopenia [DS], n = 241 without sarcopenia [DM]). Ten patients were randomly selected from both groups. Non-targeted metabolomic analysis was performed by ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.

RESULTS

A total of 632 differential metabolites were identified, including 82 that were significantly differentially abundant (P < 0.05, VIP > 1, FC > 1.2 or FC < 0.8). Compared with the DM group, the contents of pentadecanoic acid, 5'-methylthioadenosine (5'-MTA), N,N-dimethylarginine (asymmetric dimethylarginine, ADMA), and glutamine in the DS group were significantly increased, while that of isoxanthohumol was decreased.

DISCUSSION

Based on receiver operating characteristic curve analysis, pentadecanoic acid, 5'-MTA, ADMA, and glutamine may serve as potential biomarkers of DS. Moreover, ATP-binding cassette (ABC) transporters and the mammalian target of the rapamycin signaling pathway were found to potentially have important regulatory roles in the occurrence and development of DS (P < 0.05). Collectively, the differential metabolites identified in this study provide new insights into the underlying pathophysiology of DS and serve as a basis for therapeutic interventions.

Advanced glycation end products in skeletal muscle health and sarcopenia: A systematic review of observational studies

BACKGROUND

Advanced glycation end products (AGEs) and AGEs receptor (RAGE) may play a role in sarcopenia. This systematic review evaluated the associations between AGEs measured in tissues (skin) by autofluorescence (SAF) and/or circulation (blood, urine) and muscle health outcomes (strength, mass, function) and sarcopenia in observational studies.

METHODS

MEDLINE, Embase, Scopus and Web of Science were searched for studies reporting associations between AGEs and muscle-related outcomes in community-dwelling adults aged ≥ 30 years (until March 2022).

RESULTS

Fourteen cross-sectional and one prospective study were included in the narrative summary. SAF was negatively associated with muscle strength, mass, and physical functioning in adults aged ≥ 30 years (four studies), and muscle mass (three studies), strength, and sarcopenia (one study) in adults aged ≥ 65 years. Circulating AGEs were negatively associated with muscle strength and physical functioning (four studies) and predicted the risk of walking disability (one prospective study), and sarcopenia (one study) in older adults. The role of RAGE in muscle health was inconclusive.

CONCLUSIONS

SAF and circulating AGEs were negatively associated with muscle-related outcomes in adults aged ≥ 30 years in cross-sectional studies. This finding should be confirmed in well-designed prospective studies investigating sarcopenia, as AGEs represent a potentially modifiable target for intervention.

The association of low muscle mass with prevalence and incidence of type 2 diabetes in different BMI classes

OBJECTIVE

The aim of this study is to investigate whether muscle mass is associated with the prevalence and incidence of type 2 diabetes and whether this association differs within men and women of normal weight, overweight or obesity.

METHODS

Adult participants were included from the Lifelines cohort study. Low muscle mass was defined as < -1SD of the gender-stratified creatinine excretion rate (CER). Multivariate logistic regression analysis was used to assess the association between muscle mass and the prevalence and incidence of type 2 diabetes.

RESULTS

Muscle mass was associated with the prevalence of type 2 diabetes both in men and in women (OR 1.51 [95 %CI 1.32-1.72]; P < 0.001 and OR 1.53 [1.36 - 1.73]; P < 0.001). Incident type 2 diabetes was associated with a decreased muscle mass for both men and women (male; OR 1.22 [1.05 - 1.43]; P = 0.01 and female; OR 1.36 [1.17 - 1.59]; P < 0.001), and remained significant after adjustments in normal weight women (OR 1.77 [1.16-2.70]; P = 0.008).

CONCLUSIONS

Both a low muscle mass and loss of muscle mass are associated with the prevalence and incidence of diabetes in the general population. This association is strongest in people with normal weight, and weakens in people within higher BMI subgroups.

Prediabetes is associated with loss of appendicular skeletal muscle mass and sarcopenia

Background

Decreasing mass and metabolism in skeletal muscle are associated with increasing insulin resistance (IR) and type 2 diabetes mellitus (T2DM). The causal relation between sarcopenia and abnormal glucose metabolism may be bidirectional. This investigation is aimed to explore the detailed correlation between pre-diabetes and sarcopenia in United States (US) adults.

Methods

A total of 22,482 adults aged ≥20 years in the National Health and Nutrition Examination Survey (NHANES) were included. Generalized linear models were conducted to examine associations between diabetes status, serum glucose, glycohemoglobin (HbA1c), and sarcopenia. Generalized additive models and smooth fitting curves were used to examine the non-linear relationship between HbA1c and ASM_BMI. Sarcopenia was defined as ASM_BMI (appendicular skeletal muscle mass/body mass index) < 0.789 for males, and <0.512 for females based on the cut-off values of the Foundation for the National Institutes of Health (FNIH) Sarcopenia Project.

Results

After fully adjusting for multiple covariates, sarcopenia was directly correlated with pre-diabetes [OR (95%CI) = 1.230 (1.057, 1.431), p = 0.008] and T2DM [OR (95%CI) = 2.106 (1.625, 2.729), p < 0.001]. In non-T2DM population, HbA1c was negatively correlated with ASM_BMI [β (95%CI) = -0.009 (-0.013, -0.005), p < 0.001]. The correlations only persisted in males. Furthermore, in male non-T2DM population, the association of HbA1c and ASM_BMI presents an inverted U-shape curve with an inflection point of HbA1c 5.2%.

Conclusion

Pre-diabetes is associated with increased risk of sarcopenia. HbA1c is an independent risk factor for loss of appendicular skeletal muscle mass and sarcopenia when HbA1c greater than 5.2% in the male non-T2DM population.

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.

Role of advanced glycation end products in the longitudinal association between muscular strength and psychotic symptoms among adolescents

Muscular strength, assessed by handgrip, is a risk indicator for psychiatric disorders, including psychosis. However, the biological mechanisms underlying this association remain unclear. Since advanced glycation end products (AGEs) play a key role in skeletal muscle underdevelopment and psychosis, we examined the role of AGEs in the longitudinal association between muscular strength and psychotic symptoms among adolescents. We first evaluated the direction of the relationship between handgrip strength and urine levels of pentosidine, a representative AGEs in a population-based birth cohort of 1,542 adolescents at ages 12 and 14. Then, we examined the role of AGEs in the longitudinal association between handgrip strength and thought problems (TP), as a psychotic symptom indicator, in a subsample of 256 adolescents at ages 13 and 14. An autoregressive cross-lagged model revealed that handgrip strength at age 12 negatively predicted pentosidine levels at age 14 (β = −0.20, p < 0.001), whereas pentosidine levels at age 12 did not predict handgrip strength at age 14 (β = 0.04, p = 0.062). Moreover, pentosidine levels had a significant indirect effect on the relationship between handgrip strength and TP (standard indirect effect = −0.051, p = 0.012), which remained significant after adjusting for gender and preceded TP and pentosidine levels. Thus, adolescents with low muscular strength are at a high risk of developing psychotic symptoms, which could be mediated by AGEs. Future studies need to investigate whether interventions focused on muscular strength prevent the accumulation of AGEs and thereby prevent the development of psychosis.

Advanced glycation end products and bone - How do we measure them and how do they correlate with bone mineral density and fractures? A systematic review and evaluation of precision of measures

The role of advanced glycation end products (AGEs) in bone fragility especially in diabetic bone disease is increasingly recognized and researched. As skeletal frailty in diabetes does not correlate to bone mineral density (BMD) in the same way as in postmenopausal osteoporosis, BMD may not be a suitable measure of bone quality in persons with diabetes. Abundant research exists upon the effect of AGEs on bone, and though full understanding of the mechanisms of actions does not yet exist, there is little doubt of the clinical relevance. Thus, the measurement of AGEs as well as possible treatment effects on AGEs have become issues of interest. The aim of this report is to summarize results of measurements of AGEs. It consists of a systematic review of the existing literature on AGE measurements in clinical research, an evaluation of the precision of skin autofluorescence (SAF) measurement by AGE Reader® (Diagnoptics), and a short commentary on treatment of osteoporosis in patients with and without diabetes with respects to AGEs. We conclude that various AGE measures correlate well, both fluorescent and non-fluorescent and in different tissues, and that more than one target of measure may be used. However, pentosidine has shown good correlation with both bone measures and fracture risk in existing literature and results on SAF as a surrogate measurement is promising as some corresponding associations with fracture risk and bone measures are reported. As SAF measurements performed with the AGE Reader® display high precision and allow for a totally noninvasive procedure, conducting AGE measurements using this method has great potential and further research of its applicability is encouraged.

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.

Lens Autofluorescence Based Advanced Glycation End Products (AGEs) Measurement to Assess Risk of Osteopenia Among Individuals Under the Age of 50

INTRODUCTION

Simple non-invasive biomarker is urgently needed to detect the largely silent osteopenia in order to prevent osteoporosis-related fracture later in life. The accumulation of advanced glycation end products (AGEs) has been related to reduced bone density and osteoporotic fractures. Whether lens autofluorescence (LAF) based AGEs (LAF-AGEs) measurement could be used to assess the risk of osteopenia is aimed to investigate in this paper.

METHODS

Through routine health examination, 368 individuals under the age of 50 were enrolled. A dual-energy X-ray absorptiometry (DXA) device was used to measure bone mineral density (BMD) of the forearm and determine osteopenia. AGE levels were derived with LAF along with the other demographic and laboratory parameters. After deriving the age-adjusted AGE levels (AALs), a linear regression analysis and an ordered logistic regression analysis were applied to examine the associations between osteopenia and LAF-AGEs as well as AALs.

RESULTS

Negative correlations (Pearson r = -0.16, p < 0.001) were found between LAF-AGEs and T-scores. Higher AALs were significantly associated (p = 0.004) with escalated level of osteopenia in the ordered logistic analysis.

DISCUSSION

After reviewing the relevant studies, it is concluded that LAF-AGE is a more stable measure of long-term metabolic dysfunction than circulating AGE. LAF-AGEs are a valid, practical and non-invasive parameter for osteopenia risk evaluation. Further studies with longer follow-up will be helpful to clarify its effectiveness for osteoporosis risk assessment.

Effects of cheerleading practice on advanced glycation end products, areal bone mineral density, and physical fitness in female adolescents

Background: Exercise has been widely reported to promote bone health, but it is unknown whether is associated with a reduction in advanced glycosylation end products (AGEs). This study aimed to investigate the effects of 14 weeks of cheerleading exercise on areal bone mineral density (aBMD) and AGEs.

Methods: In this study, 46 female teenagers (age, 19.52 ± 1.21 years; body mass index, 20.15 ± 2.47 kg/m²) were randomly divided into a cheerleading group (CHE, n = 21) and a control group (CON, n = 25). The CHE group was subjected to cheerleading practice twice a week for 14 weeks; the CON group maintained their daily routine. Dual-energy X-ray absorptiometry was used to measure aBMD, and autofluorescence (AF) values were used to reflect AGEs. Physical fitness testing all-in-one machines are used to test body composition, cardiorespiratory fitness, muscle fitness and flexibility. A mixed ANOVA model was used to examine the effect of the intervention on each outcome. A multiple mediation model with covariates for physical activity and eating behaviors was performed to explore the mediators between cheerleading exercise and aBMD.

Results: After 14 weeks of cheerleading practice, 1) aBMD increased significantly in both groups with significantly higher increases in the CHE group (p < 0.05). 2) AGEs significantly decreased in the CHE group (−2.7%), but not in the CON group (p > 0.05). 3) Vertical jumps and sit-ups significantly increased in the CHE group (p < 0.05), but not in the CON group (p > 0.05). 4) ΔAF values was significantly negatively correlated with Δ aBMD (r = −0.302, p < 0.05). 5) ΔAF values mediated the effect of exercise on the aBMD (indirect effect: 0.0032, 95% CI 0.0002–0.0079).

Conclusion: Cheerleading practice improved aBMD and physical fitness and reduced AGEs accumulation in female adolescents. The effect of exercise on aBMD was partially mediated by AGEs.

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.

Polyphenols in Highland barley tea inhibit the production of Advanced glycosylation end-products and alleviate the skeletal muscle damage

SCOPE

Highland barley tea is a kind of caffeine-free cereal tea. Previous studies have shown that it was rich in polyphenol flavonoids. Here, the effect of Highland barley tea polyphenols (HBP) on the production of advanced glycosylation end-products and alleviate the skeletal muscle damage is systematically investigated.

METHODS

and results: HBP effectively inhibited the formation of AGEs in vitro, and 12 phenolic compounds were identified. In addition, D-galactose was used to construct a mouse senescence model and intervened with different doses of HBP. It was found that high doses of HBP effectively inhibited AGEs in serum and flounder muscle species and increased muscle mass in flounder muscle; also, high doses of HBP increased the expression of the mitochondrial functional protein SIRT3 and decreased the expression of myasthenia-related proteins. Furthermore, cellular experiments showed that AGEs could significantly increase oxidative stress in skeletal muscle.

CONCLUSION

These data indicate that the relationship between the biological activity and HBP properties is relevant since Highland barley could be a potential functional food to prevent AGEs-mediated skeletal muscle damage. This article is protected by copyright. All rights reserved.

Skin autofluorescence Is associated With low bone mineral density in type 2 diabetic patients

Although the risk of bone fracture is increased in type 2 diabetes (T2DM), bone mineral density (BMD) is increased rather than decreased. Accumulation of advanced glycation end products (AGEs) adversely influences the fracture resistance of bone in T2DM. We hypothesized that SAF is also associated with BMD levels in type 2 diabetic patients and aimed to evaluate the association of SAF with BMD and the presence of osteoporosis. This cross-sectional case-control study included 237 patients with T2DM (F/M: 133/104, 56.2±11.9 yrs) and 100 age- and sex-matched controls (F/M: 70/30, 54.8±8.8 yrs). Skin autofluorescence, a validated non-invasive measure of tissue AGEs, is used to detect the accumulation of AGEs in skin collagen using AGE Reader (DiagnOptics B.V., Groningen, The Netherlands). In addition, BMD was measured with DEXA (Lunar DPX-L). Patients with T2DM had higher SAF values compared to control group (2.21±0.53 AU vs. 1.79±0.33 AU, p < 0.001). Male subjects had higher SAF compared to women (2.34±0.53 AU vs. 2.11±0.50 AU, p < 0.001). Subjects with below -2.5 femoral neck or lumbar T scores had higher SAF measurements compared to subjects with normal T scores (2.46±0.53 AU vs. 2.18±0.52 AU, p = 0.006). Femoral neck BMD was lower in subjects with T2DM (0.946±0.345 g/cm² vs. 1.005±0.298 g/cm², p = 0.002). There was a negative correlation between SAF and femoral neck BMD (r=-0.24, p < 0.001), femoral neck T scores (r=-0.24, p < 0.001), L1-4 BMD (r=-0.10, p = 0.005), L1-4 T score (r=-0.16, p=0.001) and a positive correlation between SAF and age (r=0.44, p < 0.001), body mass index (r:0.16, p = 0.002) and HbA1c (r=0.37, p < 0.001). Accumulation of skin AGEs was increased, and BMD levels were decreased in diabetic patients. A negative association between SAF and BMD was detected, indicating a relationship between higher AGE accumulation and low BMD and osteoporosis in diabetic patients. Long-term prospective studies are needed to identify the practical use of SAF measurement in diabetic bone disease.

Methylglyoxal Induces Inflammation, Metabolic Modulation and Oxidative Stress in Myoblast Cells

Uremic sarcopenia is a serious clinical problem associated with physical disability and increased morbidity and mortality. Methylglyoxal (MG) is a highly reactive, dicarbonyl uremic toxin that accumulates in the circulatory system in patients with chronic kidney disease (CKD) and is related to the pathology of uremic sarcopenia. The pathophysiology of uremic sarcopenia is multifactorial; however, the details remain unknown. We investigated the mechanisms of MG-induced muscle atrophy using mouse myoblast C2C12 cells, focusing on intracellular metabolism and mitochondrial injury. We found that one of the causative pathological mechanisms of uremic sarcopenia is metabolic flow change to fatty acid synthesis with MG-induced ATP shortage in myoblasts. Evaluation of cell viability revealed that MG showed toxic effects only in myoblast cells, but not in myotube cells. Expression of mRNA or protein analysis revealed that MG induces muscle atrophy, inflammation, fibrosis, and oxidative stress in myoblast cells. Target metabolomics revealed that MG induces metabolic alterations, such as a reduction in tricarboxylic acid cycle metabolites. In addition, MG induces mitochondrial morphological abnormalities in myoblasts. These changes resulted in the reduction of ATP derived from the mitochondria of myoblast cells. Our results indicate that MG is a pathogenic factor in sarcopenia in CKD.

Higher Dietary Intake of Advanced Glycation End Products Is Associated with Faster Cognitive Decline in Community-Dwelling Older Adults

OBJECTIVE

Dietary-derived advanced glycation end products (AGEs) vary for different food types and the methods employed during their preparation may contribute to diverse chronic health conditions. The goal of this study was to investigate the associations of dietary AGEs (dAGEs) with cognitive decline in older adults.

METHODS

Non-demented older adults (n = 684) underwent annual testing with 19 cognitive tests summarized as a global cognitive score based on five cognitive domains. We modified a previously validated food frequency questionnaire designed to assess dAGE. The modified questionnaire assessed portion size and frequency of consumption of six food groups (meat, poultry, fish, cheese, spreads, and processed foods), as well as the method of their preparation (e.g., grilling, boiling). dAGE was the sum of the scores of the six food groups. Linear mixed-effect models were used to examine the association of baseline dAGE with cognitive decline. All models controlled for age, sex, education, race, and body mass index (BMI).

RESULTS

Average follow-up was 3.0 years. Higher baseline dAGEs was associated with a faster rate of global cognitive decline (Estimate = -0.003 (standard error = 0.001, p-value = 0.015). This association was driven by declines in episodic memory (-0.004 (0.002, 0.013)) and perceptual speed (-0.003 (0.001, 0.049)) but not by semantic memory, working memory, and visuospatial domains. These associations were not attenuated by controlling for cardiovascular risk factors and diseases, including diabetes. Levels of dAGE of the specific food groups were not associated with cognitive decline.

CONCLUSIONS

Higher levels of dietary AGE levels in older adults are associated with faster cognitive decline. These data lend further support for the importance of diet and that its modification may slow or prevent late-life cognitive impairment. Further clinical studies will be needed and the molecular mechanisms underlying these associations will need to be identified.

The relationship between dynapenia and vitamin D level in geriatric women with type 2 diabetes mellitus

Objective

In this study, we examined the possible relationship between dynapenia and vitamin D (VD) levels in geriatric women with type 2 diabetes mellitus (T2DM).

Methods

One hundred and twenty-two geriatric female patients aged 65-80 years with a diagnosis of T2DM were included in this prospective study. Physical examinations of the patients were performed, and biochemical tests were analyzed. The muscle strength of the patients was measured with a hand dynamometer. Dynapenia was defined as low grip strength with normal skeletal muscle mass index. In muscle strength measurements, for female patients, over 20 kg was accepted as normal and below 20 kg as decreased muscle strength. Patients were separated into three groups as <10 ng/ml, 10-30 ng/ml, and >30 ng/ml according to VD levels; according to the status of dynapenia, they were divided into two groups as dynapenic and non-dynapenic. By comparing all these parameters between these groups, the relationship between VD level and dynapenia was evaluated. In statistical analysis, significance was accepted as p<0.05.

Results

While 54 of the patients (44.3%) met the dynapenia criterion, 68 patients (55.7%) were non-dynapenic. Patients were first compared according to their dynapenia status. VD level was significantly lower in the dynapenic group (p<0.05). In the correlation analysis, a moderate positive correlation was found between muscle strength and VD (p=0.033, r: 0.23). The patients were then compared according to the VD groups. In the VD insufficient group, muscle strength (p=0.015), body mass index (p=0.025), systolic blood pressure (p<0.01), and glucose (p<0.01) were statistically significantly higher.

Conclusion

In the present study, we found a considerable relationship between VD levels and dynapenia in geriatric women with T2DM.

Association of Glycative Stress With Motor and Muscle Function

Glycative stress is a type of biological stress caused by non-enzymatic glycation reactions, which include advanced glycation end product (AGE) formation, AGE accumulation, glycation-driven dysfunction of proteins and cellular signaling, inflammation, oxidation, and tissue damage. Increased glycative stress derived from hyperglycemia and lifestyle disorders is a risk factor in metabolic and age-related diseases, such as type 2 diabetes, cardiovascular disease, cancer, Alzheimer’s disease, osteoporosis, and dementia. Studies have shown that AGE accumulation is correlated with the age-related loss of muscle mass and power output, also called sarcopenia. Mechanistically, dysfunctions of contractile proteins, myogenic capacity, and protein turnover can cause glycative stress-induced skeletal muscle dysfunction. Because the skeletal muscle is the largest metabolic organ in the body, maintaining skeletal muscle health is essential for whole-body health. Increasing awareness and understanding of glycative stress in the skeletal muscle in this review will contribute to the maintenance of better skeletal muscle function.

Skin Autofluorescence, a Noninvasive Biomarker for Advanced Glycation End-products, Is Associated With Sarcopenia

BACKGROUND

Accumulation of advanced glycation end-products (AGEs) in skeletal muscle has been implicated in development of sarcopenia.

AIM

To obtain further insight in the pathophysiology of sarcopenia, we studied its relationship with skin AGEs in the general population.

METHODS

In a cross-sectional analysis, 2744 participants of northern European background, mean age 74.1 years, were included from the Rotterdam Study. Skin AGEs were measured as skin autofluorescence (SAF) using AGE ReaderTM, appendicular skeletal mass index (ASMI) using insight dual-energy X-ray absorptiometry, hand grip strength (HGS) using a hydraulic hand dynamometer, and, in a subgroup, gait speed (GS) measured on an electronic walkway (n = 2080). We defined probable sarcopenia (low HGS) and confirmed sarcopenia (low HGS and low ASMI) based on the European Working Group on Sarcopenia in Older People (EWGSOP2) revised criteria cutoffs. Multivariate linear and logistic regression were performed adjusting for age, sex, body fat percentage, height, renal function, diabetes, and smoking status.

RESULTS

The prevalence of low ASMI was 7.7%; probable sarcopenia, 24%, slow GS, 3%; and confirmed sarcopenia, 3.5%. SAF was inversely associated with ASMI [β -0.062 (95% CI -0.092, -0.032)], HGS [β -0.051 (95% CI -0.075, -0.026)], and GS [β -0.074 (95% CI -0.116, -0.033)]. A 1-unit increase in SAF was associated with higher odds of probable sarcopenia [odds ratio (OR) 1.36 (95% CI 1.09, 1.68)] and confirmed sarcopenia [OR 2.01 (95% CI 1.33, 3.06)].

CONCLUSION

Higher skin AGEs are associated with higher sarcopenia prevalence. We call for future longitudinal studies to explore the role of SAF as a potential biomarker of sarcopenia.

Metabolic syndrome and its association with components of sarcopenia in older community-dwelling Chinese

Aging and obesity contribute to muscle dysfunction. This study aimed to determine the cross-sectional associations between components of metabolic syndrome (MetS) and sarcopenia in 251 older community-dwelling Chinese. The total fat-free mass was measured by dual-energy X-ray absorptiometry, muscle strength (handgrip strength) by a handheld dynamometer, physical performance by 4-meter walk, 5-time chair stand test, and the short physical performance battery (SPPB). MetS was defined using the International Diabetes Federation (IDF) criteria. The participants with MetS had a higher appendicular skeletal muscle mass (ASM) and relative ASM (RASM). The males with MetS had higher handgrip strength, and the females with MetS had higher SPPB scores. After adjusting for age and body mass index, the participants with an increased waist circumference had a higher ASM, and those with increased diastolic blood pressure (DBP) also had higher handgrip strength. The males with elevated fasting blood glucose (FBG) levels had a lower gait speed. Components of MetS, such as DPB and FBG, were associated with muscle strength and physical performance in older adults. These results suggest that muscle strength and function should be considered in treating older adults with MetS.

Prevalence and physical characteristics of locomotive syndrome stages as classified by the new criteria 2020 in older Japanese people: results from the Nagahama study

Background

The Japanese Orthopaedic Association (JOA) proposed the concept of locomotive syndrome (LS) in 2007 for detecting high-risk individuals with mobility limitation. In 2020, the JOA revised the clinical decision limits and introduced LS stage 3, which carried the highest-risk for LS compared to the conventional stages, 1 and 2. The purpose of this study was to characterize the prevalence, comorbidities, and physical characteristics in each LS stage, as per the LS criteria 2020.

Methods

We analyzed 2077 participants (64.9% women; mean age, 68.3 ± 5.4 years) from the Nagahama Study aged ≥60 years. Participants were classified into 4 groups, non-LS and LS stages 1, 2, and 3, based on a 25-question Geriatric Locomotive Function Scale. The prevalence of comorbidities (sarcopenia, osteoporosis, diabetes mellitus, low back pain [LBP], and knee pain) were investigated. Physical characteristics were measured based on the physical performance tests including gait speed, five-times chair-stand, single-leg stand, and short physical performance battery; muscle strength tests including grip, knee extension, hip flexion, and abduction; and body-composition analysis including muscle quantity and quality. Differences in the prevalence of comorbidities between LS stages were tested using the chi-square test. The general linear model was performed for univariate and multivariate analyses with post-hoc test to compare the differences in physical characteristics among the LS stages.

Results

The prevalence of LS increased with age, and the mean prevalence of LS stages 1, 2, and 3 were 24.4, 5.5, and 6.5%, respectively. The prevalence of comorbidities, including sarcopenia, osteoporosis, LBP, and knee pain, increased with worsening LS stage. Physical performance tests were significantly different between LS stages 2 and 3; and muscle strength differed significantly between LS stages 1 and 2. Additionally, in terms of body composition analysis, muscle quality but not muscle quantity showed significant differences among all the LS stages.

Conclusions

Our findings suggest that muscle strengthening and dynamic training, including balance training in LS stage 1 and 2, respectively, were needed for preventing the LS progression. Individuals with LS stage 3 should perform dynamic training and muscle strengthening exercises while receiving treatment for comorbidities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02440-2.

Sirt3-mediated mitophagy regulates AGEs-induced BMSCs senescence and senile osteoporosis

Senile osteoporosis (SOP) is widely regarded as one of the typical aging-related diseases due to a decrease in bone mass and the destruction in microarchitecture. The inhibition of mitophagy can promote bone marrow mesenchymal stem cells (BMSCs) senescence, and increasing studies have shown that interventions targeting BMSCs senescence can ameliorate osteoporosis, exhibiting their potential for use as therapeutic strategies. Sirtuin-3 (Sirt3) is an essential mitochondria metabolic regulatory enzyme that plays an important role in mitochondrial homeostasis, but its role in bone homeostasis remains largely unknown. This study seeks to investigate whether advanced glycation end products (AGEs) accumulation aggravated BMSCs senescence and SOP, and explored the mechanisms underlying these effects. We observed that AGEs significantly aggravated BMSCs senescence, as well as promoted mitochondrial dysfunction and inhibited mitophagy in a concentration-dependent manner. In addition, this effect could be further strengthened by Sirt3 silencing. Importantly, we identified that the reduction of Sirt3 expression and the mitophagy were vital mechanisms in AGEs-induced BMSCs senescence. Furthermore, overexpression of Sirt3 by intravenously injection with recombinant adeno-associated virus 9 carrying Sirt3 plasmids (rAAV-Sirt3) significantly alleviated BMSCs senescence and the formation of SOP in SAMP6. In conclusion, our data demonstrated that Sirt3 protects against AGEs-induced BMSCs senescence and SOP. Targeting Sirt3 to improve mitophagy may represent a potential therapeutic strategy for attenuating AGEs-associated SOP.

Age-related changes in gait speeds and asymmetry during circular gait and straight-line gait in older individuals aged 60-79 years

AIM

The present study aimed to investigate the age-related changes in gait speeds and asymmetry during circular and straight-line gaits among older adults aged 60-79 years.

METHODS

The study included 391 community-dwelling older adults aged >60 years, who participated in the Nagahama cohort study. They were assigned to four age groups: 60-64 years (early 60s), 65-69 years (late 60s), 70-74 years (early 70s) and 75-79 years (late 70s). For the circular gait test, the time required to walk twice around a 1-m diameter circle for right and left rotations were measured. The average time of the two trials was measured as the circular gait time, and the side-to-side difference in the circular gait times was calculated as an asymmetry index. Walking speed, asymmetry of step length, and asymmetry of stance duration time during straight-line gait at comfortable and maximal walking pace were measured.

RESULTS

Circular gait time in older women in the late 70s group was significantly slower than that in other age groups; however, no age-related change was observed in older men. Maximal gait speeds in the early and late 70s groups were significantly slower than those in the early 60s group.

CONCLUSIONS

Age-related decline in circular gait speed was observed in older women aged ≥75 years, but not in older men. Maximal straight-line gait speed decreased significantly in both genders after the age of 70 years. Geriatr Gerontol Int 2021; 21: 404-410.

A Narrative Review on Sarcopenia in Type 2 Diabetes Mellitus: Prevalence and Associated Factors

Type 2 diabetes mellitus (T2DM) represents a major health burden for the elderly population, affecting approximately 25% of people over the age of 65 years. This percentage is expected to increase dramatically in the next decades in relation to the increased longevity of the population observed in recent years. Beyond microvascular and macrovascular complications, sarcopenia has been described as a new diabetes complication in the elderly population. Increasing attention has been paid by researchers and clinicians to this age-related condition—characterized by loss of skeletal muscle mass together with the loss of muscle power and function—in individuals with T2DM; this is due to the heavy impact that sarcopenia may have on physical and psychosocial health of diabetic patients, thus affecting their quality of life. The aim of this narrative review is to provide an update on: (1) the risk of sarcopenia in individuals with T2DM, and (2) its association with relevant features of patients with T2DM such as age, gender, body mass index, disease duration, glycemic control, presence of microvascular or macrovascular complications, nutritional status, and glucose-lowering drugs. From a clinical point of view, it is necessary to improve the ability of physicians and dietitians to recognize early sarcopenia and its risk factors in patients with T2DM in order to make appropriate therapeutic approaches able to prevent and treat this condition.

Glycemic Control and Insulin Improve Muscle Mass and Gait Speed in Type 2 Diabetes: The MUSCLES-DM Study

OBJECTIVES

Type 2 diabetes is a risk factor for sarcopenia. Evidence on the prevention of sarcopenia using blood glucose-lowering therapy is limited. We aimed to examine the relationship between changes in glycemic control and sarcopenia and the effect of antidiabetic agents against sarcopenia in patients with type 2 diabetes.

DESIGN

We conducted an observational longitudinal study.

SETTING AND PARTICIPANTS

In total, 588 Japanese patients with diabetes of an ongoing multicenter study completed 1-year follow-up measurements for sarcopenia and clinical data.

METHODS

The data set of the Multicenter Study for Clarifying Evidence for Sarcopenia in patients with Diabetes Mellitus (the MUSCLES-DM study) was analyzed.

RESULTS

During the follow-up period, the frequency of sarcopenia marginally increased, and the means of skeletal muscle mass index (SMI), handgrip strength, and gait speed did not show any changes. However, on dividing into 5 groups depending on the degree of changes in glycated hemoglobin (HbA_1c) value, the patients with a decrease of ≥1% in HbA_1c exhibited a significant increase in SMI. Our analysis revealed similar results for gait speed but not handgrip strength. Using the multiple linear regression model, we identified that a ≥1% decrease in HbA_1c value was an independent determinant of the changes in SMI and gait speed. We also determined that insulin use at baseline was an independent factor for the changes in SMI.

CONCLUSIONS AND IMPLICATIONS

Correction of poor glycemic control and use of insulin were significantly associated with the increase in skeletal muscle mass or gait speed in Japanese patients with type 2 diabetes. The current finding increases our understanding of the importance of glycemic control for the prevention of cardiovascular diseases and sarcopenia.

Novel metabolomics markers are associated with pre-clinical decline in hand grip strength in community-dwelling older adults

BACKGROUND

Hand grip strength (HGS) has been proposed as a robust predictor for frailty and sarcopenia. Hence, identifying biomarkers for declining HGS accompanying aging could deepen our understanding of the biological underpinnings, informing pre-emptive intervention. Acylcarnitines (ACs) are metabolites generated by fatty acid metabolism in the mitochondria and are dysregulated in multiple disorders affecting the musculature. However, they have not been comprehensively profiled and examined regarding their utility in predicting variability in declining HGS, longitudinally. Thus, we aimed to: 1) validate previous findings on insignificant cross-sectional association between ACs and HGS, and 2) examine whether baseline ACs were associated with both decline and variability in HGS over 18 months, in community-dwelling older adults.

METHODS

We included participants who had HGS measured with dynamometer longitudinally (N = 121). We quantified ACs by targeted plasma metabolomics profiling. Multivariable linear regressions were then performed.

RESULTS

Cross-sectionally, ACs were not significantly associated with HGS. Longitudinally, baseline short-chain dicarboxylic and hydroxylated acylcarnitines (AC-DC/-OH) levels were inversely associated with and significantly explained the variability in 18-month decline in HGS. A specific AC species, the C4-OH, accounted for most of the variance explained.

CONCLUSIONS

We showed novel biomarkers for declining HGS, furthering molecular understanding and informing nutritional pre-emptive programs.