Advanced Glycation End-Products Induce Apoptosis of Vascular Smooth Muscle Cells: A Mechanism for Vascular Calcification

Cathepsin D inhibits AGEs-induced phenotypic transformation in vascular smooth muscle cells

This study investigates the role of Cathepsin D (CTSD) in diabetic vascular complications, particularly its impact on the phenotypic transformation of vascular smooth muscle cells (VSMCs) induced by advanced glycation end-products (AGEs), and explores its potential molecular mechanisms. CTSD was overexpressed in VSMCs using lentiviral vectors. Various methods, including CCK-8, immunofluorescence, SA-β-Gal staining, EdU assay, scratch assay, cell cycle analysis, and Western blotting, were employed to assess VSMC viability, proliferation, migration, senescence, and apoptosis. Additionally, transcriptomic and metabolomic analyses were conducted to investigate the molecular mechanisms underlying CTSD overexpression in VSMCs. AGEs treatment significantly inhibited CTSD expression in VSMCs, leading to reduced cell viability, enhanced proliferation and migration, increased senescence, and apoptosis. In contrast, overexpression of CTSD effectively inhibited AGEs-induced VSMCs proliferation, migration, senescence, and apoptosis. Combined transcriptomic and metabolomic analyses suggested that CTSD may affect VSMCs phenotypic transformation by inhibiting the glycolysis pathway. This study highlights the critical role of CTSD in the phenotypic transformation of VSMCs induced by AGEs and provides a new perspective for cardiovascular and cerebrovascular disease treatment. CTSD may emerge as a novel therapeutic target, though its specific molecular mechanisms and clinical application prospects in VSMCs phenotypic transformation require further investigation.

The role of AGEs in muscle ageing and sarcopenia

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

Effects of Exercise on Arterial Stiffness: Mechanistic Insights into Peripheral, Central, and Systemic Vascular Health in Young Men

BACKGROUND/OBJECTIVES

Arterial stiffness, a critical predictor of cardiovascular events, varies regionally across peripheral, central, and systemic arteries, necessitating targeted exercise interventions for young men. However, research on the effects of exercise on arterial stiffness in these regions among young men remains limited. This review aims to (i) examine the effects of exercise on arterial stiffness in young men across these regions, and (ii) investigate the underlying mechanisms involved.

METHODS

Database searches on PubMed, ScienceDirect, Web of Science, and Scopus were conducted up to July 2024. The keywords were: exercise, men/male, and arterial stiffness. Inclusion criteria were studies involving young men, supervised exercise, and arterial stiffness measures. Thirty-five papers were categorized into groups based on peripheral, central and systemic arterial stiffness.

RESULTS

Peripheral arterial stiffness: continuous aerobic cycling (light to high intensity), interval aerobic cycling (moderate to high intensity), and 30-s stretching exercises demonstrated positive effects, likely due to short-term changes in sympathetic nervous system activity, nitric oxide availability, and vascular tone. Central arterial stiffness: chronic high-intensity continuous and interval aerobic cycling exercises promoted vascular remodeling, including elastin preservation and collagen regulation. For systemic arterial stiffness, continuous and interval aerobic cycling and light-intensity squats with whole-body vibration exercises improve endothelial function, smooth muscle relaxation, and vascular remodeling.

CONCLUSIONS

Tailored exercise intervention can effectively reduce arterial stiffness across peripheral, central and systemic regions in young men. Improvements in peripheral stiffness are linked to short-term metabolic shifts, central stiffness responds to long-term remodeling, while systemic arterial stiffness involves both short- and long-term metabolic adaptations.

Modulation of PPAR-γ/Nrf2 and AGE/RAGE signaling contributes to the chrysin cardioprotection against myocardial damage following ischemia/reperfusion in diabetic rats

OBJECTIVE

Advanced glycation end products/receptor for AGEs (AGE/RAGE) signaling has a well-established role in the etiology of diabetic-related cardiovascular disorders. The purpose of the study was to elucidate the role of chrysin, a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, against ischemia/reperfusion (IR) injury in diabetic rats and its functional interaction with the AGE/RAGE signaling pathway.

METHODS

A single intraperitoneal injection of streptozotocin (STZ, 70 mg/kg) was administered to rats for induction of diabetes. Rats having blood glucose levels more than 300 mg/dl following a 72 hr STZ injection were classified as diabetic. PPAR-γ antagonist GW9662 (1 mg/kg, i.p.), chrysin (60 mg/kg, p.o.), or both were administered to diabetic rats for 4 weeks. On the 29th day, rats were given ischemia for 45 min and then reperfusion for 1 hr to induce myocardial infarction (MI).

KEY FINDINGS

Pretreatment with chrysin significantly improved hemodynamic status, ventricular functions, and cardiac injury markers in diabetic myocardium. Increased PPAR-γ/Nrf2 and decreased RAGE protein expressions were linked to this improvement. Chrysin pretreatment resulted in the upregulation of endogenous antioxidants and reduced TBARS levels. Moreover, chrysin significantly decreased inflammation and apoptosis in diabetic myocardium.

CONCLUSION

PPAR-γ/Nrf2 co-activation by chrysin ameliorated IR-induced MI in diabetic rats, possibly via modulating AGE/RAGE signaling.

The role and mechanism of protein post‑translational modification in vascular calcification (Review)

Vascular calcification is closely associated with morbidity and mortality in patients with chronic kidney disease, atherosclerosis and diabetes. In the past few decades, vascular calcification has been studied extensively and the findings have shown that the mechanism of vascular calcification is not merely a consequence of a high-phosphorus and high-calcium environment but also an active process characterized by abnormal calcium phosphate deposition on blood vessel walls that involves various molecular mechanisms. Recent advances in bioinformatics approaches have led to increasing recognition that aberrant post-translational modifications (PTMs) play important roles in vascular calcification. This review presents the latest progress in clarifying the roles of PTMs, such as ubiquitination, acetylation, carbamylation and glycosylation, as well as signaling pathways, such as the Wnt/β-catenin pathway, in vascular calcification.

Investigation of the Dysfunction Caused by High Glucose, Advanced Glycation End Products, and Interleukin-1 Beta and the Effects of Therapeutic Agents on the Microphysiological Artery Model

Diabetes mellitus (DM) has substantial global implications and contributes to vascular inflammation and the onset of atherosclerotic cardiovascular diseases. However, translating the findings from animal models to humans has inherent limitations, necessitating a novel platform. Therefore, herein, an arterial model is established using a microphysiological system. This model successfully replicates the stratified characteristics of human arteries by integrating collagen, endothelial cells (ECs), and vascular smooth muscle cells (VSMCs). Perfusion via a peristaltic pump shows dynamic characteristics distinct from those of static culture models. High glucose, advanced glycation end products (AGEs), and interleukin-1 beta are employed to stimulate diabetic conditions, resulting in notable cellular changes and different levels of cytokines and nitric oxide. Additionally, the interactions between the disease models and oxidized low-density lipoproteins (LDL) are examined. Finally, the potential therapeutic effects of metformin, atorvastatin, and diphenyleneiodonium are investigated. Metformin and diphenyleneiodonium mitigate high-glucose- and AGE-associated pathological changes, whereas atorvastatin affects only the morphology of ECs. Altogether, the arterial model represents a pivotal advancement, offering a robust and insightful platform for investigating cardiovascular diseases and their corresponding drug development.

Post-translational modifications in kidney diseases and associated cardiovascular risk

Patients with chronic kidney disease (CKD) are at an increased cardiovascular risk compared with the general population, which is driven, at least in part, by mechanisms that are uniquely associated with kidney disease. In CKD, increased levels of oxidative stress and uraemic retention solutes, including urea and advanced glycation end products, enhance non-enzymatic post-translational modification events, such as protein oxidation, glycation, carbamylation and guanidinylation. Alterations in enzymatic post-translational modifications such as glycosylation, ubiquitination, acetylation and methylation are also detected in CKD. Post-translational modifications can alter the structure and function of proteins and lipoprotein particles, thereby affecting cellular processes. In CKD, evidence suggests that post-translationally modified proteins can contribute to inflammation, oxidative stress and fibrosis, and induce vascular damage or prothrombotic effects, which might contribute to CKD progression and/or increase cardiovascular risk in patients with CKD. Consequently, post-translational protein modifications prevalent in CKD might be useful as diagnostic biomarkers and indicators of disease activity that could be used to guide and evaluate therapeutic interventions, in addition to providing potential novel therapeutic targets.

Smooth muscle NF90 deficiency ameliorates diabetic atherosclerotic calcification in male mice via FBXW7-AGER1-AGEs axis

Hyperglycemia accelerates calcification of atherosclerotic plaques in diabetic patients, and the accumulation of advanced glycation end products (AGEs) is closely related to the atherosclerotic calcification. Here, we show that hyperglycemia-mediated AGEs markedly increase vascular smooth muscle cells (VSMCs) NF90/110 activation in male diabetic patients with atherosclerotic calcified samples. VSMC-specific NF90/110 knockout in male mice decreases obviously AGEs-induced atherosclerotic calcification, along with the inhibitions of VSMC phenotypic changes to osteoblast-like cells, apoptosis, and matrix vesicle release. Mechanistically, AGEs increase the activity of NF90, which then enhances ubiquitination and degradation of AGE receptor 1 (AGER1) by stabilizing the mRNA of E3 ubiquitin ligase FBXW7, thus causing the accumulation of more AGEs and atherosclerotic calcification. Collectively, our study demonstrates the effects of VSMC NF90 in mediating the metabolic imbalance of AGEs to accelerate diabetic atherosclerotic calcification. Therefore, inhibition of VSMC NF90 may be a potential therapeutic target for diabetic atherosclerotic calcification.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Association between depression and macrovascular disease: a mini review

Depression and macrovascular diseases are globally recognized as significant disorders that pose a substantial socioeconomic burden because of their associated disability and mortality. In addition, comorbidities between depression and macrovascular diseases have been widely reported in clinical settings. Patients afflicted with coronary artery disease, cerebrovascular disease or peripheral artery disease exhibit an elevated propensity for depressive symptoms. These symptoms, in turn, augment the risk of macrovascular diseases, thereby reflecting a bidirectional relationship. This review examines the physiological and pathological mechanisms behind comorbidity while also examining the intricate connection between depression and macrovascular diseases. The present mechanisms are significantly impacted by atypical activity in the hypothalamic-pituitary-adrenal axis. Elevated levels of cortisol and other hormones may disrupt normal endothelial cell function, resulting in vascular narrowing. At the same time, proinflammatory cytokines like interleukin-1 and C-reactive protein have been shown to disrupt the normal function of neurons and microglia by affecting blood-brain barrier permeability in the brain, exacerbating depressive symptoms. In addition, platelet hyperactivation or aggregation, endothelial dysfunction, and autonomic nervous system dysfunction are important comorbidity mechanisms. Collectively, these mechanisms provide a plausible physiological basis for the interplay between these two diseases. Interdisciplinary collaboration is crucial for future research aiming to reveal the pathogenesis of comorbidity and develop customised prevention and treatment strategies.

Elicitation of Inhibitory Effects for AGE-Induced Oxidative Stress in Rotator Cuff-Derived Cells by Apocynin

Advanced glycation end-products (AGEs) play a critical supportive role during musculoskeletal disorders via glycosylation and oxidative stress. Though apocynin, identified as a potent and selective inhibitor of NADPH oxidase, has been reported to be involved in pathogen-induced reactive oxygen species (ROS), its role in age-related rotator cuff degeneration has not been well clarified. Therefore, this study aims to evaluate the in vitro effects of apocynin on human rotator cuff-derived cells. Twelve patients with rotator cuff tears (RCTs) participated in the study. Supraspinatus tendons from patients with RCTs were collected and cultured. After the preparation of RC-derived cells, they were divided into four groups (control group, control + apocynin group, AGEs group, AGEs + apocynin group), and gene marker expression, cell viability, and intracellular ROS production were evaluated. The gene expression of NOX, IL-6, and the receptor for AGEs (RAGE) was significantly decreased by apocynin. We also examined the effect of apocynin in vitro. The results showed that ROS induction and increasing apoptotic cells after treatment of AGEs were significantly decreased, and cell viability increased considerably. These results suggest that apocynin can effectively reduce AGE-induced oxidative stress by inhibiting NOX activation. Thus, apocynin is a potential prodrug in preventing degenerative changes of the rotor cuff.

Saturated fatty acid promotes calcification via suppressing SIRT6 expression in vascular smooth muscle cells

BACKGROUND

This study aims to investigate the effects of saturated free fatty acid on calcification and SIRT6 expression in vascular smooth muscle cells (VSMCs) and the role of SIRT6 in regulating VSMC calcification.

METHODS

Sprague-Dawley rats were randomly allocated to two groups: rats with normal diet (ND) and high-fat diet (HFD) from 4 to 12 weeks. At 12 weeks, part rats randomly selected from ND and HFD were administrated with vitamin D3 and nicotine to establish a model of vascular calcification. Thoracic aortas were collected from treatment rats at 16 weeks for assaying vascular calcification and related protein expression. Primary VSMCs isolated from Sprague-Dawley rats were used for investigating the effects of palmitic acid on VSMCs' calcification, apoptosis and target protein expression.

RESULTS

HFD-facilitated calcification in medial aorta, with decreased SIRT6 expression in VSMCs of aortas. Palmitic acid decreased SIRT6 expression while increased calcification, apoptosis and protein expression of BMP2 and RUNX2 in primary VSMCs. Overexpression of SIRT6 could, partially or completely, rescue the palmitic acid-induced elevation of calcification, apoptosis and expression of BMP2 and RUNX2.

CONCLUSION

This study demonstrated that vascular calcification induced by HFD was linked to the palmitic acid-induced downregulation of SIRT6. Overexpression of SIRT6 could decrease palmitic acid-induced calcification and apoptosis in VSMCs.

BMF-AS1/BMF Promotes Diabetic Vascular Calcification and Aging both In Vitro and In Vivo

Vascular calcification and aging often increase morbidity and mortality in patients with diabetes mellitus (DM); however, the underlying mechanisms are still unknown. In the present study, we found that Bcl-2 modifying factor (BMF) and BMF antisense RNA 1 (BMF-AS1) were significantly increased in high glucose-induced calcified and senescent vascular smooth muscle cells (VSMCs) as well as artery tissues from diabetic mice. Inhibition of BMF-AS1 and BMF reduced the calcification and senescence of VSMCs, whereas overexpression of BMF-AS1 and BMF generates the opposite results. Mechanistic analysis showed that BMF-AS1 interacted with BMF directly and up-regulated BMF at both mRNA and protein levels, but BMF did not affect the expression of BMF-AS1. Moreover, knocking down BMF-AS1 and BMF suppressed the calcification and senescence of VSMCs, and BMF knockout (BMF^-/-) diabetic mice presented less vascular calcification and aging compared with wild type diabetic mice. In addition, higher coronary artery calcification scores (CACs) and increased plasma BMF concentration were found in patients with DM, and there was a positive correlation between CACs and plasma BMF concentration. Thus, BMF-AS1/BMF plays a key role in promoting high glucose-induced vascular calcification and aging both in vitro and in vivo. BMF-AS1 and BMF represent potential therapeutic targets in diabetic vascular calcification and aging.

Glycolaldehyde, an Advanced Glycation End Products Precursor, Induces Apoptosis via ROS-Mediated Mitochondrial Dysfunction in Renal Mesangial Cells

Glycolaldehyde (GA) is a reducing sugar and a precursor of advanced glycation end products (AGEs). The role of precursor and precursor-derived AGEs in diabetes and its complications have been actively discussed in the literature. This study aimed to elucidate the mechanism of GA-induced apoptosis in renal cells. Immunoblotting results showed that GA (100 μM) caused cytotoxicity in murine renal glomerular mesangial cells (SV40 MES 13) and induced apoptosis via major modulators, decreasing Bcl-2 and increasing Bax, cytochrome c, and cleaved caspase-3/-9 expression. GA-derived AGE accumulation and receptor for AGE (RAGE) expression increased in mesangial cells; however, cells that were cotreated with aminoguanidine (AG) showed no increase in GA-derived AGE concentration. Furthermore, reactive oxygen species (ROS) production was increased by GA, while AG inhibited AGE formation, leading to a decrease in ROS levels in mesangial cells. We evaluated apoptosis through fluorescence-activated cell sorting, and used TUNEL staining to study DNA fragmentation. Additionally, we measured ATP generation and used MitoTracker staining to access changes in mitochondrial membrane potential. This study showed that GA increased AGE concentration, RAGE expression, and excessive ROS generation, leading to renal mesangial cell damage via GA-induced apoptosis pathway caused by mitochondrial dysfunction.

Insights Into the Role of Mitochondria in Vascular Calcification

Vascular calcification (VC) is a growing burden in aging societies worldwide, and with a significant increase in all-cause mortality and atherosclerotic plaque rupture, it is frequently found in patients with aging, diabetes, atherosclerosis, or chronic kidney disease. However, the mechanism of VC is still not yet fully understood, and there are still no effective therapies for VC. Regarding energy metabolism factories, mitochondria play a crucial role in maintaining vascular physiology. Discoveries in past decades signifying the role of mitochondrial homeostasis in normal physiology and pathological conditions led to tremendous advances in the field of VC. Therapies targeting basic mitochondrial processes, such as energy metabolism, damage in mitochondrial DNA, or free-radical generation, hold great promise. The remarkably unexplored field of the mitochondrial process has the potential to shed light on several VC-related diseases. This review focuses on current knowledge of mitochondrial dysfunction, dynamics anomalies, oxidative stress, and how it may relate to VC onset and progression and discusses the main challenges and prerequisites for their therapeutic applications.

Diabetic mellitus, vascular calcification and hypoxia: A complex and neglected tripartite relationship

DM (diabetic mellitus) and its common vascular complications VC (vascular calcification), are increasingly harmful to human health. In recent years, the research on the relationship between DM and VC is also deepening. Hypoxia, as one of the pathogenic factors of many disease models, is also closely related to the occurrence of DM and VC. There are some studies on the role of hypoxia in the pathogenesis of DM and VC respectively, but no one has made an in-depth summary of the systematic connection between hypoxia, DM and VC. Therefore, what we want to review in this article are the relationship between DM, VC and hypoxia, respectively, as well as the role of hypoxia in the development of DM and VC, which has little concern but is a novel and potentially target that may provide some new ideas for the prevention and treatment of DM, VC, especially diabetic VC.

AGEs-Induced Calcification and Apoptosis in Human Vascular Smooth Muscle Cells Is Reversed by Inhibition of Autophagy

Vascular calcification (VC) in macrovascular and peripheral blood vessels is one of the main factors leading to diabetes mellitus (DM) and death. Apart from the induction of vascular calcification, advanced glycation end products (AGEs) have also been reported to modulate autophagy and apoptosis in DM. Autophagy plays a role in maintaining the stabilization of the external and internal microenvironment. This process is vital for regulating arteriosclerosis. However, the internal mechanisms of this pathogenic process are still unclear. Besides, the relationship among autophagy, apoptosis, and calcification in HASMCs upon AGEs exposure has not been reported in detail. In this study, we established a calcification model of SMC through the intervention of AGEs. It was found that the calcification was upregulated in AGEs treated HASMCs when autophagy and apoptosis were activated. In the country, AGEs-activated calcification and apoptosis were suppressed in Atg7 knockout cells or pretreated with wortmannin (WM), an autophagy inhibitor. These results provide new insights to conduct further investigations on the potential clinical applications for autophagy inhibitors in the treatment of diabetes-related vascular calcification.

Longxuetongluo Capsule protects against cerebral ischemia/reperfusion injury through endoplasmic reticulum stress and MAPK-mediated mechanisms

Introduction

Longxuetongluo Capsule (LTC) is wildly applied to treat ischemic stroke in clinical practice in China. However, the pharmacological mechanism of LTC on ischemic stroke is still unstated.

Objective

Our research was designed to study the protective effect of LTC against cerebral ischemia–reperfusion (I/R) injury and reveal the underlying mechanism both in vivo and in vitro.

Methods

PC12 cells treated with glucose deprivation/reperfusion (OGD/R) were used to simulate in vitro ischemia/reperfusion (I/R) injury. The cell viability, apoptosis rate, and protein expressions of PC12 cells were evaluated. In vivo validation of the protective effect of LTC was carried out by middle cerebral artery occlusion (MCAO)/reperfusion treatment, and the underlying mechanism of its anti-apoptosis ability was further revealed by immunohistochemistry staining and Western blotting.

Results

In the current study, we observed that LTC effectively inhibited oxygen-glucose deprivation/reperfusion (OGD/R) induced apoptosis of PC12 cells through suppressing the cleavage of poly ADP-ribose polymerase (PARP), caspase-3, and caspase-9. Further investigation revealed that OGD/R insult remarkably triggered the endoplasmic reticulum stress responses (ER stress) to induce PC12 cell apoptosis. LTC treatment alleviated OGD/R induced ER stress by inhibiting the activation of protein kinase RNA (PKR)-like ER kinase (PERK)/eukaryotic translation initiation factor 2 (eIF2α) and inositol requiring enzyme 1 (IRE1)/tumor necrosis factor receptor-associated factor 2 (TRAF2) pathways. Additionally, LTC also restrained the OGD/R-induced PC12 cell apoptosis by reversing the activated mitogen-activated protein kinase (MAPK) through IRE1/TRAF2 pathway. Animal studies demonstrated LTC significantly restricted the infarct region induced by middle cerebral artery occlusion (MCAO)/reperfusion, the activation of ER stress and apoptosis of neuronal cells had also been suppressed by LTC in the penumbra region.

Conclusion

LTC protects the cerebral neuronal cell against ischemia/reperfusion injury through ER stress and MAPK-mediated mechanisms.

Arterial Remodelling in Chronic Kidney Disease: Impact of Uraemic Toxins and New Pharmacological Approaches

Chronic kidney disease (CKD) is a major public health concern that affects around 10 percent of the world's population. The severity of CKD is mainly due to the high prevalence of cardiovascular (CV) complications in this population. The aim of this review is to describe the arterial remodelling associated with CKD, to provide a quick overview of the mechanisms involved and to review the recent pharmacological approaches aimed at improving vascular health in CKD. CKD patients are exposed to metabolic and haemodynamic disorders that may affect the CV system. Large artery functional and geometric abnormalities have been well documented in CKD patients and are associated with an increase in arterial stiffness and a maladaptive remodelling. Uraemic toxins, such as indoxyl sulphate, p-cresyl sulphate, protein carbamylation and advanced glycation products, exert various effects on vascular smooth muscle cell functions. The low-grade inflammation associated with CKD may also affect arterial wall composition and remodelling. It is worth noting that the CV risk for CKD patients remains high despite the pharmacological control of traditional CV risk factors, suggesting the need for innovative therapeutic strategies. An interventional study targeting the NLRP3 inflammasome has provided some interesting preliminary results that need to be confirmed, especially in terms of safety.

Lactate accelerates vascular calcification through NR4A1-regulated mitochondrial fission and BNIP3-related mitophagy

Arterial media calcification is related to mitochondrial dysfunction. Protective mitophagy delays the progression of vascular calcification. We previously reported that lactate accelerates osteoblastic phenotype transition of VSMC through BNIP3-mediated mitophagy suppression. In this study, we investigated the specific links between lactate, mitochondrial homeostasis, and vascular calcification. Ex vivo, alizarin S red and von Kossa staining in addition to measurement of calcium content, RUNX2, and BMP-2 protein levels revealed that lactate accelerated arterial media calcification. We demonstrated that lactate induced mitochondrial fission and apoptosis in aortas, whereas mitophagy was suppressed. In VSMCs, lactate increased NR4A1 expression, leading to activation of DNA-PKcs and p53. Lactate induced Drp1 migration to the mitochondria and enhanced mitochondrial fission through NR4A1. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection showed that NR4A1 knockdown was involved in enhanced autophagy flux. Furthermore, NR4A1 inhibited BNIP3-related mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, and LC3-II co-localization with TOMM20. The excessive fission and deficient mitophagy damaged mitochondrial structure and impaired respiratory function, determined by mPTP opening rate, mitochondrial membrane potential, mitochondrial morphology under TEM, ATP production, and OCR, which was reversed by NR4A1 silencing. Mechanistically, lactate enhanced fission but halted mitophagy via activation of the NR4A1/DNA-PKcs/p53 pathway, evoking apoptosis, finally accelerating osteoblastic phenotype transition of VSMC and calcium deposition. This study suggests that the NR4A1/DNA-PKcs/p53 pathway is involved in the mechanism by which lactate accelerates vascular calcification, partly through excessive Drp-mediated mitochondrial fission and BNIP3-related mitophagy deficiency.

Combination of pathological and spectroscopic characterization to promote diagnosis of retinal pigment epithelium-Bruch's membrane complex in a diabetic rat model

Diabetic retinopathy (DR) is a common condition of diabetes, and approaches to detecting early DR using the unique characteristics of the retinal pigment epithelium-Bruch's membrane complex (RBC) have increasingly attracted attention. A diabetic model was established in Sprague-Dawley rats via streptozocin (STZ) injection for 1 (DM1) and 6 months (DM6), confirmed by weekly blood glucose measurement. Serum and retinal tissue-based advanced glycation endproducts (AGE) levels significantly elevated in diabetic rats, and RBC was evaluated by transmission electron microscopy and Raman spectroscopy. The results showed that whole Raman spectra and all marked band intensities could respectively achieve almost equal and accurate discrimination of all animal groups, along with the determination of important molecules from the band data. Further quantitative analyses indicated series of metabolic disturbance due to hyperglycemia were involved while the body self-regulation mechanism still played a role with different effects during the disease progression. Given this, Raman spectroscopy can reliably distinguish the early characterization of DR in addition to providing intrinsic key molecules that is sensitive to identify the early disease progression.

Uremic Vascular Calcification: The Pathogenic Roles and Gastrointestinal Decontamination of Uremic Toxins

Uremic vascular calcification (VC) commonly occurs during advanced chronic kidney disease (CKD) and significantly increases cardiovascular morbidity and mortality. Uremic toxins are integral within VC pathogenesis, as they exhibit adverse vascular influences ranging from atherosclerosis, vascular inflammation, to VC. Experimental removal of these toxins, including small molecular (phosphate, trimethylamine-N-oxide), large molecular (fibroblast growth factor-23, cytokines), and protein-bound ones (indoxyl sulfate, p-cresyl sulfate), ameliorates VC. As most uremic toxins share a gut origin, interventions through gastrointestinal tract are expected to demonstrate particular efficacy. The “gastrointestinal decontamination” through the removal of toxin in situ or impediment of toxin absorption within the gastrointestinal tract is a practical and potential strategy to reduce uremic toxins. First and foremost, the modulation of gut microbiota through optimizing dietary composition, the use of prebiotics or probiotics, can be implemented. Other promising strategies such as reducing calcium load, minimizing intestinal phosphate absorption through the optimization of phosphate binders and the inhibition of gut luminal phosphate transporters, the administration of magnesium, and the use of oral toxin adsorbent for protein-bound uremic toxins may potentially counteract uremic VC. Novel agents such as tenapanor have been actively tested in clinical trials for their potential vascular benefits. Further advanced studies are still warranted to validate the beneficial effects of gastrointestinal decontamination in the retardation and treatment of uremic VC.

Regulation of Vascular Calcification by Reactive Oxygen Species

Vascular calcification is the deposition of hydroxyapatite crystals in the medial or intimal layers of arteries that is usually associated with other pathological conditions including but not limited to chronic kidney disease, atherosclerosis and diabetes. Calcification is an active, cell-regulated process involving the phenotype transition of vascular smooth muscle cells (VSMCs) from contractile to osteoblast/chondrocyte-like cells. Diverse triggers and signal transduction pathways have been identified behind vascular calcification. In this review, we focus on the role of reactive oxygen species (ROS) in the osteochondrogenic phenotype switch of VSMCs and subsequent calcification. Vascular calcification is associated with elevated ROS production. Excessive ROS contribute to the activation of certain osteochondrogenic signal transduction pathways, thereby accelerating osteochondrogenic transdifferentiation of VSMCs. Inhibition of ROS production and ROS scavengers and activation of endogenous protective mechanisms are promising therapeutic approaches in the prevention of osteochondrogenic transdifferentiation of VSMCs and subsequent vascular calcification. The present review discusses the formation and actions of excess ROS in different experimental models of calcification, and the potential of ROS-lowering strategies in the prevention of this deleterious condition.

Role of SGK1 in the Osteogenic Transdifferentiation and Calcification of Vascular Smooth Muscle Cells Promoted by Hyperglycemic Conditions

In diabetes mellitus, hyperglycemia promotes the osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) to enhance medial vascular calcification, a common complication strongly associated with cardiovascular disease and mortality. The mechanisms involved are, however, still poorly understood. Therefore, the present study explored the potential role of serum- and glucocorticoid-inducible kinase 1 (SGK1) during vascular calcification promoted by hyperglycemic conditions. Exposure to high-glucose conditions up-regulated the SGK1 expression in primary human aortic VSMCs. High glucose increased osteogenic marker expression and activity and, thus, promoted the osteogenic transdifferentiation of VSMCs, effects significantly suppressed by additional treatment with the SGK1 inhibitor EMD638683. Moreover, high glucose augmented the mineralization of VSMCs in the presence of calcification medium, effects again significantly reduced by SGK1 inhibition. Similarly, SGK1 knockdown blunted the high glucose-induced osteogenic transdifferentiation of VSMCs. The osteoinductive signaling promoted by high glucose required SGK1-dependent NF-kB activation. In addition, advanced glycation end products (AGEs) increased the SGK1 expression in VSMCs, and SGK1 inhibition was able to interfere with AGEs-induced osteogenic signaling. In conclusion, SGK1 is up-regulated and mediates, at least partly, the osteogenic transdifferentiation and calcification of VSMCs during hyperglycemic conditions. Thus, SGK1 inhibition may reduce the development of vascular calcification promoted by hyperglycemia in diabetes.

Apelin-13 attenuates high glucose-induced calcification of MOVAS cells by regulating MAPKs and PI3K/AKT pathways and ROS-mediated signals

Vascular calcification (VC) is an inducement of many cardiovascular diseases. Clinic evidences have confirmed that diabetes was the independent risk factor for VC, and the mechanism has not been well explored. Apelin as a ligand molecule is widely found in the cardiovascular system and showed potential in inhibiting VC, but the inhibitory effect and mechanism of apelin-13 against high glucose-induced VC have not been investigated yet. Herein, apelin-13 was employed to inhibit high glucose-induced VC in mouse aortic vascular smooth muscle cells (MOVAS), and the underlying mechanism was explored. The results showed that apelin-13 significantly inhibited high glucose-induced cells proliferation, migration and invasion of MOVAS cells. Apelin-13 also effectively attenuated high glucose-induced calcification by inhibiting alkaline phosphatase (ALP) activity and expression. Further investigation revealed that apelin-13 dramatically suppressed high glucose-induced DNA damage through inhibiting reactive oxide species (ROS) generation. Moreover, apelin-13 also effectively improved high glucose-induced dysfunction of MAPKs and PI3K/AKT. Inhibition of ERK by inhibitor (U0126) significantly blocked high glucose-induced calcification, which further confirmed the significance of MAPKs. Taken together, these results suggested that apelin-13 had the potential to attenuate high glucose-induced calcification of MOVAS cells by inhibiting ROS-mediated DNA damage and regulating MAPKs and PI3K/AKT pathways. Our findings validated the strategy of using apelin-13 maybe a novel way in treating high glucose-mediated VC.

Advanced glycation end-products suppress autophagy by AMPK/mTOR signaling pathway to promote vascular calcification

Vascular calcification is closely linked to patients in diabetes mellitus and chronic kidney disease. Advanced glycation end-products (AGEs) are associated with osteogenic differentiation of vascular smooth muscle cell (VSMC), vascular calcification, and autophagy that takes part in the process. However, the underlying mechanism of the effects of AGEs on the phenotypic transition and autophagy of VSMCs is not clearly understood. In this study, we cultured the rat VSMC line (A7R5) and thoracic aorta organ with bovine serum albumin (BSA) or AGEs (AGEs-BSA) and detected proteins expression by Western blotting or immunofluorescence. Autophagosome was observed by transmission electron microscopy (TEM). The mineralization and calcific nodules were identified by Alizarin Red S and Von Kossa staining. AGEs significantly downregulated p-AMPKα expression and upregulated p-mTOR expression and then increased the expression of osteoblastic differentiation, while suppressing autophagy in a time-dependent pattern. Pretreatment with autophagy activator rapamycin and AMPK activator AICAR both upregulated the autophagy level and downregulated the effects of AGEs on osteoblastic differentiation of VSMCs. Moreover, the result from rat thoracic aorta culture also confirmed that AGEs promote vascular calcification in a time-dependent manner. Thus, our study showed that AGEs quicken vascular calcification and suppress autophagy associated with AMPK/mTOR signaling pathway.

Vascular Calcification: An Important Understanding in Nephrology

Vascular calcification (VC) is a life-threatening state in chronic kidney disease (CKD). High cardiovascular mortality and morbidity of CKD cases may root from medial VC promoted by hyperphosphatemia. Vascular calcification is an active, highly regulated, and complex biological process that is mediated by genetics, epigenetics, dysregulated form of matrix mineral metabolism, hormones, and the activation of cellular signaling pathways. Moreover, gut microbiome as a source of uremic toxins (eg, phosphate, advanced glycation end products and indoxyl-sulfate) can be regarded as a potential contributor to VC in CKD. Here, an update on different cellular and molecular processes involved in VC in CKD is discussed to elucidate the probable therapeutic pathways in the future.

Tumour necrosis factor superfamily members in ischaemic vascular diseases

Current treatment of ischaemic vascular diseases such as coronary and peripheral artery disease includes angioplasty and bypass grafting, as well as lipid lowering therapies and control of other cardiovascular risk factors. Numerous members of the tumour necrosis factor superfamily (TNFSF) have recently shown emerging roles in both the protection and progression of such diseases. Understanding the role TNFSF members play in ischaemic vascular disease may provide insight into the development of novel therapeutics to prevent or treat diseases relating to atherosclerosis and ischaemia. This review summarizes the most recent findings relating to TNFSF members and the mechanisms that precede ischaemic vascular disease progression, particularly endothelial dysfunction, chronic inflammation, and atherosclerotic plaque development. This review also explores recent translational research on the role of TNFSF therapies in cardiovascular disease.

Rho-associated protein kinase and cyclophilin a are involved in inorganic phosphate-induced calcification signaling in vascular smooth muscle cells

Arterial calcification, a risk factor of cardiovascular events, develops with differentiation of vascular smooth muscle cells (VSMCs) into osteoblast-like cells. Cyclophilin A (CypA) is a peptidyl-prolyl isomerase involved in cardiovascular diseases such as atherosclerosis and aortic aneurysms, and rho-associated protein kinase (ROCK) is involved in the pathogenesis of vascular calcification. CypA is secreted in a ROCK activity-dependent manner and works as a mitogen via autocrine or paracrine mechanisms in VSMCs. We examined the involvement of the ROCK-CypA axis in VSMC calcification induced by inorganic phosphate (Pi), a potent cell mineralization initiator. We found that Pi stimulated ROCK activity, CypA secretion, extracellular signal-regulated protein kinase (ERK) 1/2 phosphorylation, and runt-related transcription factor 2 expression, resulting in calcium accumulation in rat aortic smooth muscle cells (RASMCs). The ROCK inhibitor Y-27632 significantly suppressed Pi-induced CypA secretion, ERK1/2 phosphorylation, and calcium accumulation. Recombinant CypA was found to be associated with increased calcium accumulation in RASMCs. Based on these results, we suggest that autocrine CypA is mediated by ROCK activity and is involved in Pi-induced ERK1/2 phosphorylation following calcification signaling in RASMCs.

The Role of Nonenzymatic Post-translational Protein Modifications in Uremic Vascular Calcification

Considerable technological advances have enabled the identification and linkage of nonenzymatic post-translationally modified proteins to the pathogenesis of cardiovascular disease (CVD) in patients with kidney failure. Through processes such as the nonenzymatic carbamylation reaction as well as the formation of advanced glycation end products, we now know that protein modifications are invariably associated with the development of CVD beyond a mere epiphenomenon and this has become an important focus of nephrology research in recent years. Although the specific mechanisms by which protein modifications occurring in kidney failure that may contribute to CVD are diverse and include pathways such as inflammation and fibrosis, vascular calcification has emerged as a distinct pathological sequelae of protein modifications. In this review, we consider the biological mechanisms and clinical relevance of protein carbamylation and advanced glycation end products in CVD development with a focus on vascular calcification.

Advanced Glycation End Products (AGEs) Induce Apoptosis of Fibroblasts by Activation of NLRP3 Inflammasome via Reactive Oxygen Species (ROS) Signaling Pathway

Background

Type 2 diabetes impairs the healing process and induces apoptosis of fibroblasts, which are thought to be involved in this process. We investigated the possible mechanisms involved in AGEs-induced apoptosis of human dermal fibroblasts.

Material/Methods

We examined the expression of apoptosis-related proteins in fibroblasts isolated from human diabetic wounds. Human dermal fibroblasts exposed to AGEs were used to study the links among apoptosis, ROS, and NLRP3 inflammasome activation. Signaling mechanisms were evaluated by preincubating the cells with appropriate inhibitors. Cleaved caspase-8, cleaved caspase-3, BAX, Bcl-2, and NLRP3 inflammasome expression were measured by Western blot analysis. ROS generation, cell viability, and cell apoptosis were assessed.

Results

We observed a higher level of cleaved caspase-8 and cleaved caspase-3 expression in fibroblasts isolated from human diabetic wounds compared with controls. AGEs decreased the proliferation of cells in a concentration-dependent and time-dependent manner. The exposure of fibroblasts to AGEs significantly increased the number of cells in early and late apoptosis stages. AGES-induced human dermal fibroblasts showed high expressions of cleaved caspase3, cleaved caspase8, and Bax. Treatment with AGEs induced the expression of NLRP3, caspase-1, and ASC. AGES-induced apoptosis was blocked by BAY 11–7082, an inhibitor of the NLRP3 inflammasome. AGEs increased the production of ROS in fibroblasts, and its apoptogenic effect was blocked by NAC.

Conclusions

AGEs cause apoptosis of fibroblasts by inducing the generation of ROS and activating the NLRP3 inflammasome. In vivo experiments are needed to confirm these results.

The link between advanced glycation end products and apoptosis in delayed wound healing

Advanced glycation end products (AGEs) are naturally occurring molecules that start to accumulate from embryonic developmental stages and form as part of normal ageing. When reducing sugars interact with and modify proteins or lipids, AGE production occurs. AGE formation accelerates in chronic hyperglycemic conditions, and high AGE levels have been associated with the pathogenesis of various diseases. In addition, enhanced levels of AGEs have been linked to delayed wound healing as seen in patients with diabetes mellitus. Research has provided numerous ways in which a high AGE concentration results in impaired wound healing, including oxidative stress, structural and functional changes to proteins important in wound repair, an enhanced inflammatory response by activation of transcription factors, and possible exaggerated apoptosis of cells necessary to the wound repair process. Apoptosis is a naturally occurring cell death process that is significant for normal tissue functioning and plays an important role in wound repair by preventing a prolonged inflammatory response and excessive scar formation. Abnormal apoptosis affects wound healing, resulting in slow healing wounds. This review will summarize the role of AGEs in wound healing, focusing on the mechanisms by which AGEs lead to apoptosis in various cell types. The review provides the way forward for medical research and molecular studies as it focuses on the mechanisms by which AGEs induce apoptosis in various cell types, including fibroblasts, osteoblasts, neuronal cells, and endothelial cells. Reviewing the mechanisms of AGE-linked apoptosis is important in understanding the impact of high AGE levels in delayed wound healing in diabetic patients due to abnormal apoptosis of cells necessary to the wound healing process.

Clinical Significance of Skin Autofluorescence in Elderly Patients With Long-Standing Persistent Atrial Fibrillation

Background

Recent clinical studies have demonstrated the importance of skin autofluorescence as a cardiovascular risk factor. However, data regarding the relationship between skin autofluorescence and atrial fibrillation are limited. The aim of this study was to clarify the clinical significance of skin autofluorescence in elderly patients with long-standing persistent atrial fibrillation.

Methods

This cross-sectional study enrolled 112 elderly patients with long-standing persistent atrial fibrillation who were treated medically (46 men and 66 women; mean age, 81 ± 9 years). The association between skin autofluorescence and various clinical parameters was examined.

Results

Significant relationships were observed between skin autofluorescence and CHADS₂ score (r = 0.53, P < 0.001), high-sensitivity cardiac troponin T level (r = 0.43, P < 0.001), reactive oxygen metabolite levels (r = 0.52, P < 0.001), and whole blood passage time (r = 0.45, P < 0.001). Furthermore, multiple regression analyses showed that these clinical parameters were independent variables when skin autofluorescence was used as a subordinate factor. Receiver-operating characteristic curve analysis indicated that the risk values of skin autofluorescence for high CHADS₂ scores (≥ 2) or elevated high-sensitivity cardiac troponin T levels (> 0.014ng/mL) were 2.6 arbitrary units (AU) and 2.7 AU, respectively.

Conclusions

The findings of this study indicated that skin autofluorescence may be a prognostic factor in elderly patients with long-standing persistent atrial fibrillation. The risk value of skin autofluorescence was considered as 2.6 AU or 2.7 AU.

Lower serum osteocalcin concentrations in patients with type 2 diabetes and relationships with vascular risk factors among patients with coronary artery disease

BACKGROUND

Lower serum concentrations of the osteoblast-derived protein, osteocalcin, have been associated with poorer glycemic control, insulin resistance and atherosclerosis, and with the development of type 2 diabetes (T2DM).

METHODS

This study compares concentrations of two physiological forms of osteocalcin, carboxylated (cOCN) and uncarboxylated (unOCN), between participants with T2DM (n = 20) and age-, gender- and body mass index (BMI)-matched participants without T2DM (n = 40) among patients with coronary artery disease (CAD), and it explores relationships between osteocalcin concentrations and cardiovascular risk factors.

RESULTS

Concentrations of unOCN (2.71 ± 1.86 vs. 4.70 ± 2.03 ng/mL; t = -3.635, p = 0.001) and cOCN (8.70 ± 2.27 vs. 10.77 ± 3.69 ng/mL; t = -2.30, p = 0.025) were lower in participants with T2DM. In participants without T2DM, concentrations of cOCN were associated with fitness (VO_2Peak rho = 0.317, p = 0.047) and lower body fat (rho = -0.324, p = 0.041). In participants with T2DM, lower unOCN was associated with HbA1c (rho = -0.516, p = 0.020). Higher body mass was associated with higher unOCN (rho = 0.423, p = 0.009) in participants without T2DM, but with lower concentrations of both unOCN (rho = -0.590, p = 0.006) and cOCN (rho = -0.632, p = 0.003) in participants with T2DM.

CONCLUSION

In patients with CAD, lower osteocalcin concentrations were related to type 2 diabetes, and to adverse fitness, metabolic and obesity profiles.

Lactate accelerates calcification in VSMCs through suppression of BNIP3-mediated mitophagy

Arterial media calcification is one of the major complications of diabetes mellitus, which is related to oxidative stress and apoptosis. Mitophagy is a special regulation of mitochondrial homeostasis and takes control of intracellular ROS generation and apoptotic pathways. High circulating levels of lactate usually accompanies diabetes. The potential link between lactate, mitophagy and vascular calcification is investigated in this study. Lactate treatment accelerated VSMC calcification, evaluated by measuring the calcium content, ALP activity, RUNX2, BMP-2 protein levels, and Alizarin red S staining. Lactate exposure caused excessive intracellular ROS generation and VSMC apoptosis. Lactate also impaired mitochondrial function, determined by mPTP opening rate, mitochondrial membrane potential and mitochondrial biogenesis markers. Western blot analysis of LC3-II and p62 and mRFP-GFP-LC3 adenovirus detection for autophagy flux revealed that lactate blocked autophagy flux. LC3-II co-staining with LAMP-1 and autophagosome quantification revealed lactate inhibited autophagy. Furthermore, lactate inhibited mitophagy, which was confirmed by TOMM20 and BNIP3 protein levels, LC3-II colocalization with BNIP3 and TEM assays. In addition, BNIP3-mediated mitophagy played a protective role against VSMC calcification in the presence of lactate. This study suggests that lactate accelerates osteoblastic phenotype transition of VSMC and calcium deposition partly through the BNIP3-mediated mitophagy deficiency induced oxidative stress and apoptosis.

Advanced glycation end products accelerate calcification in VSMCs through HIF-1α/PDK4 activation and suppress glucose metabolism

Arterial media calcification is associated with diabetes mellitus. Previous studies have shown that advanced glycation end products (AGEs) are responsible for vascular smooth muscle cell (VSMC) calcification, but the underlying mechanisms remain unclear. Hypoxia-inducible factor-1α (HIF-1α), one of the major factors during hypoxia, and pyruvate dehydrogenase kinase 4 (PDK4), an important mitochondrial matrix enzyme in cellular metabolism shift, have been reported in VSMC calcification. The potential link among HIF-1α, PDK4, and AGEs-induced vascular calcification was investigated in this study. We observed that AGEs elevated HIF-1α and PDK4 expression levels in a dose-dependent manner and that maximal stimulation was attained at 24 h. Two important HIF-1α-regulated genes, vascular endothelial growth factor A (VEGFA) and glucose transporter 1 (GLUT-1), were significantly increased after AGEs exposure. Stabilization or nuclear translocation of HIF-1α increased PDK4 expression. PDK4 inhibition attenuated AGEs-induced VSMC calcification, which was evaluated by measuring the calcium content, alkaline phosphatase (ALP) activity and runt-related transcription factor 2 (RUNX2) expression levels and by Alizarin red S staining. In addition, the glucose consumption, lactate production, key enzymes of glucose metabolism and oxygen consumption rate (OCR) were decreased during AGEs-induced VSMC calcification. In conclusion, this study suggests that AGEs accelerate vascular calcification partly through the HIF-1α/PDK4 pathway and suppress glucose metabolism.

Association of advanced glycation end products in Dupuytren disease

BACKGROUND

Advanced glycation end products are associated with aging, hyperglycemia, and oxidative stress. Accumulation of advanced glycation end products can cause various pathological conditions; however, the association of Dupuytren's disease with advanced glycation end products has not been demonstrated yet. The aim of this study is to investigate the association of Dupuytren's disease with advanced glycation end products.

METHODS

Normal palmar fascia from five patients with carpal tunnel syndrome (control group) and Dupuytren's cords from five patients (Dupuytren's disease group) were harvested. The tissues were stained using an anti-advanced glycation end products antibody, anti-receptor for advanced glycation end products antibody, and an anti-reactive oxygen species modulator 1 antibody. The expression of nicotinamide adenine dinucleotide phosphate oxidase-1 and nicotinamide adenine dinucleotide phosphate oxidase-4 genes was also assessed using real-time PCR. For in vitro analysis, the cells harvested from the control and Dupuytren's disease groups were used. After 3 days of exposure to four types of media (control group, control + advanced glycation end products group, Dupuytren's disease group, Dupuytren's disease + advanced glycation end products group), superoxide detection reagent was detected using a total reactive oxygen species/superoxide detection kit.

RESULTS

Immunostaining of the palmar fasciae of the Dupuytren's disease group showed higher expressions of advanced glycation end products and receptor for advanced glycation end products than that in the control group. The expression of nicotinamide adenine dinucleotide phosphate oxidase oxidase-1 and nicotinamide adenine dinucleotide phosphate oxidase-4 as well as reactive oxygen species modulator 1, an oxidatively damaged protein, was also higher in the Dupuytren's disease group than in the control group. In an in vitro cell culture, the addition of advanced glycation end products to the Dupuytren's disease-derived cells produced more superoxide free radicals.

CONCLUSIONS

These data suggest that the advanced glycation end products receptor for advanced glycation end products interaction produced free radicals via nicotinamide adenine dinucleotide phosphate oxidase activation in Dupuytren's disease patients. Further studies are required to confirm these results.

The Impact of Uremic Toxins on Vascular Smooth Muscle Cell Function

Chronic kidney disease (CKD) is associated with profound vascular remodeling, which accelerates the progression of cardiovascular disease. This remodeling is characterized by intimal hyperplasia, accelerated atherosclerosis, excessive vascular calcification, and vascular stiffness. Vascular smooth muscle cell (VSMC) dysfunction has a key role in the remodeling process. Under uremic conditions, VSMCs can switch from a contractile phenotype to a synthetic phenotype, and undergo abnormal proliferation, migration, senescence, apoptosis, and calcification. A growing body of data from experiments in vitro and animal models suggests that uremic toxins (such as inorganic phosphate, indoxyl sulfate and advanced-glycation end products) may directly impact the VSMCs’ physiological functions. Chronic, low-grade inflammation and oxidative stress—hallmarks of CKD—are also strong inducers of VSMC dysfunction. Here, we review current knowledge about the impact of uremic toxins on VSMC function in CKD, and the consequences for pathological vascular remodeling.

Reactive Oxygen Species in Metabolic and Inflammatory Signaling

Reactive oxygen species (ROS) are well known for their role in mediating both physiological and pathophysiological signal transduction. Enzymes and subcellular compartments that typically produce ROS are associated with metabolic regulation, and diseases associated with metabolic dysfunction may be influenced by changes in redox balance. In this review, we summarize the current literature surrounding ROS and their role in metabolic and inflammatory regulation, focusing on ROS signal transduction and its relationship to disease progression. In particular, we examine ROS production in compartments such as the cytoplasm, mitochondria, peroxisome, and endoplasmic reticulum and discuss how ROS influence metabolic processes such as proteasome function, autophagy, and general inflammatory signaling. We also summarize and highlight the role of ROS in the regulation metabolic/inflammatory diseases including atherosclerosis, diabetes mellitus, and stroke. In order to develop therapies that target oxidative signaling, it is vital to understand the balance ROS signaling plays in both physiology and pathophysiology, and how manipulation of this balance and the identity of the ROS may influence cellular and tissue homeostasis. An increased understanding of specific sources of ROS production and an appreciation for how ROS influence cellular metabolism may help guide us in the effort to treat cardiovascular diseases.

The Impact of Type 2 Diabetes on Bone Fracture Healing

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease known by the presence of elevated blood glucose levels. Nowadays, it is perceived as a worldwide epidemic, with a very high socioeconomic impact on public health. Many are the complications caused by this chronic disorder, including a negative impact on the cardiovascular system, kidneys, eyes, muscle, blood vessels, and nervous system. Recently, there has been increasing evidence suggesting that T2DM also adversely affects the skeletal system, causing detrimental bone effects such as bone quality deterioration, loss of bone strength, increased fracture risk, and impaired bone healing. Nevertheless, the precise mechanisms by which T2DM causes detrimental effects on bone tissue are still elusive and remain poorly studied. The aim of this review was to synthesize current knowledge on the different factors influencing the impairment of bone fracture healing under T2DM conditions. Here, we discuss new approaches used in recent studies to unveil the mechanisms and fill the existing gaps in the scientific understanding of the relationship between T2DM, bone tissue, and bone fracture healing.

Advanced glycation end products and strontium ranelate promote osteogenic differentiation of vascular smooth muscle cells in vitro: Preventive role of vitamin D

Advanced glycation end products (AGE) have been demonstrated to induce the osteogenic trans-differentiation of vascular smooth muscle cells (VSMC). Strontium ranelate (SR) is an anti-osteoporotic agent that has both anti-catabolic and anabolic actions on bone tissue. However, in the last years SR has been associated with an increase of cardiovascular risk. We hypothesize that SR can increase the osteoblastic trans-differentiation of VSMC and the induction of extracellular calcifications, an effect that could be potentiated in the presence of AGE and inhibited by simultaneous administration of vitamin D. The present results of our in vitro experiments demonstrate that AGE and SR alone or in combination, stimulate L-type calcium channels, causing an increase in reactive oxygen species and activation of both ERK and NFkB, with the final effect of promoting the osteogenic shift of VSMC. Importantly, these in vitro effects of AGE and/or SR can be prevented by co-incubation with vitamin D.

TDB protects vascular endothelial cells against oxygen-glucose deprivation/reperfusion-induced injury by targeting miR-34a to increase Bcl-2 expression

Prolonged ischemia can result in apoptotic death of vascular endothelial cells and lead to ischemic vascular diseases including vascular dementia, arteriosclerosis and brain oedema. Finding protective strategies to prevent this is therefore an urgent mission. Recent studies have shown that dysregulation of microRNAs (miRNAs) can lead to imbalance of Bcl-2 family proteins and mitochondrial dysfunction, leading to further damage of vascular cells under ischemic conditions. However, whether miRNAs can be used as a drug target for treating vascular diseases is not fully understood. In this study, we observed that the natural product 2,4,5-trihydroxybenzaldehyde (TDB) could effectively inhibit vascular cell apoptosis following oxygen-glucose deprivation/reperfusion (OGD/R) by maintaining mitochondrial membrane potential (MMP) and suppressing activation of the mitochondria-dependent caspase-9/3 apoptosis pathway. Furthermore, we identified miR-34a, a crucial negative regulator of Bcl-2, as a target for the protective effect of TDB on vascular cells. TDB-induced suppression of miR-34a resulted in a significant upregulation of Bcl-2 protein, MMP maintenance, and the survival of vascular cells following OGD/R. Our findings suggest that targeting miR-34a with the natural product TDB may provide a novel strategy for the treatment of ischemic vascular injuries, and demonstrate the therapeutic potential in targeting miRNAs using appropriate small molecules.