Advanced Glycation End Products: Potential Mechanism and Therapeutic Target in Cardiovascular Complications under Diabetes

The future of diabetic wound healing: unveiling the potential of mesenchymal stem cell and exosomes therapy

Diabetes mellitus (DM) is a significant public health problem and is one of the most challenging medical conditions worldwide. It is the severe complications that make this disease more intricate. A diabetic wound is one of these complications. Patients with diabetes are at higher risk of developing diabetic foot ulcers (DFU). Due to the ineffectiveness of Conventional treatments, growth in limb amputation, morbidity, and mortality have been recognized, which indicates the need for additional treatment. Mesenchymal stem cells (MSCs) can significantly improve wound healing. However, there are some risks related to stem cell therapy. Exosome therapy is a new treatment option for diabetic wounds that has shown promising results. However, an even more advanced form called cell-free therapy using exosomes has emerged. This upgraded version of stem cell therapy offers improved efficacy and eliminates the risk of cancer progression. Exosome therapy promotes wound healing from multiple angles, unlike traditional methods that primarily rely on the body's self-healing ability and only provide wound protection. Therefore, exosome therapy has the potential to replace conventional treatments effectively. However, further research is necessary to distinguish the optimal type of stem cells for therapy, ensure their safety, establish appropriate dosing, and identify the best management trail. The present study focused on the current literature on diabetic wound ulcers, their treatment, and mesenchymal stem cell and exosome therapy potential in DFU.

Skin Autofluorescence as a Potential Adjunctive Marker for Cardiovascular Risk Assessment in Type 2 Diabetes: A Systematic Review

Diabetes mellitus (DM), due to its long-term hyperglycemia, leads to the accumulation of advanced glycation end-products (AGEs), especially in the vessel walls. Skin autofluorescence (SAF) is a non-invasive tool that measures AGEs. DM patients have a rich dietary source in AGEs, associated with high oxidative stress and long-term inflammation. AGEs represent a cardiovascular (CV) risk factor, and they are linked with CV events. Our objective was to assess whether SAF predicts future CV events (CVE) by examining its association with other CV risk factors in patients with type 2 DM (T2DM). Additionally, we assessed the strengths and limitations of SAF as a predictive tool for CVE. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology, we conducted a systematic review with CRD42024507397 protocol, focused on AGEs, T2DM, SAF, and CV risk. We identified seven studies from 2014 to 2024 that predominantly used the AGE Reader Diagnostic Optic tool. The collective number of patients involved is 8934, with an average age of 63. So, SAF is a valuable, non-invasive marker for evaluating CV risk in T2DM patients. It stands out as a CV risk factor associated independently with CVE. SAF levels are influenced by prolonged hyperglycemia, lifestyle, aging, and other chronic diseases such as depression, and it can be used as a predictive tool for CVE.

Occupational and non-occupational risk factors correlating with the severity of clinical manifestations of carpal tunnel syndrome and related work disability among workers who work with a computer

The contribution of certain occupational and personal factors to the development of carpal tunnel syndrome (CTS) is still uncertain. We investigated which specific occupational and non-occupational factors correlate with the level of clinical manifestations and work disability related to CTS. The study included 190 workers who work with a computer and have diagnosed CTS (100 men, 90 women, aged 20-65 years). Subjective experience of CTS-related impairments was assessed with the Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) of the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ). The objective, neural impairments were tested with electrodiagnostics (EDX), whereas CTS-related work disability data were collected from medical records. We found a high inter-correlation between BCTQ, EDX, and work disability data. These also showed high correlations with certain occupational factors (duration of computer-working in months and hours spent daily in computer-working, certain ergonomic, microclimatic, and other occupational conditions) and non-occupational factors (demographic and lifestyle factors: nutritional status, diet, smoking, alcohol consumption, and physical activity). Despite its limitations, our study has identified occupational and non-occupational risk factors that can aggravate CTS and work disability, but which can also be improved with workplace and lifestyle preventive and corrective measures. More research is needed, though, to establish the possible causal relationships and the independent influence of each of those risk factors.

Repurposing alagebrium for diabetic foot ulcer healing: Impact on AGEs/NFκB/NOX1 signaling

BACKGROUND

Diabetic foot ulcer (DFU) is a common diabetic complication associated with disability and reduced quality of life. Available therapeutics are not sufficient to combat the spread of DFU. Here we aim to investigate the impact of alagebrium, an advanced glycation end product (AGE)-crosslink breaker, on the healing of DFU.

METHODS

Diabetes was induced in Wistar rats by STZ, and after four weeks, wound was induced on the foot. Alagebrium (10 mg/kg) was administered orally for 14 days, and wound size was measured every 3 days. Behavioral tests i.e., hot plate and footprint tests, were performed to assess sensory function and gait. Blood was collected to assess HbA1c, serum AGEs, MDA and NOX1. Tissue was collected to assess histological changes and expression of NF-κB, iNOS, TNF-α, VEGF and EGF. In a subsequent set of experiments with similar design, alagebrium was applied topically as a film-forming gel.

RESULTS

Systemic alagebrium treatment accelerated the healing of diabetic wound, improved sensory functions and gait, and ameliorated histological changes. It also reduced serum levels of AGEs, MDA and NOX1, and the tissue expression of NF-κB, iNOS, TNF-α, and increased VEGF and EGF in diabetic rats. Topical alagebrium led to similar beneficial effects i.e., accelerated diabetic wound healing, improved wound histological changes, reduced expression of NF-κB and iNOS and increased VEGF.

CONCLUSIONS

Our findings suggest repurposing of alagebrium for the management of DFU to accelerate the healing process and improve the clinical outcomes in diabetic patients.

Vitamin B12-Induced Autophagy Alleviates High Glucose-Mediated Apoptosis of Islet β Cells

High glucose levels can lead to the apoptosis of islet β cells, while autophagy can provide cytoprotection and promote autophagic cell death. Vitamin B12, a water-soluble B vitamin, has been shown to regulate insulin secretion and increase insulin sensitivity. However, the precise mechanism of action remains unclear. In this study, we investigated the influence of vitamin B12 on high glucose-induced apoptosis and autophagy in RIN-m5F cells to elucidate how vitamin B12 modulates insulin release. Our results demonstrate that exposure to 45 mM glucose led to a significant increase in the apoptosis rate of RIN-m5F cells. The treatment with vitamin B12 reduced the apoptosis rate and increased the number of autophagosomes. Moreover, vitamin B12 increased the ratio of microtubule-associated protein 1 light chain 3 beta to microtubule-associated protein 1 light chain 3 alpha (LC3-II/LC3-I), while decreasing the amount of sequestosome 1 (p62) and inhibiting the phosphorylation of p70 ribosomal protein S6 kinase (p70S6K) under both normal- and high-glucose conditions. The additional experiments revealed that vitamin B12 inhibited high glucose-induced apoptosis. Notably, this protective effect was attenuated when the autophagy inhibitor 3-methyladenine was introduced. Our findings suggest that vitamin B12 protects islet β cells against apoptosis induced by high glucose levels, possibly by inducing autophagy.

The mechanism of ferroptosis and its related diseases

Ferroptosis, a regulated form of cellular death characterized by the iron-mediated accumulation of lipid peroxides, provides a novel avenue for delving into the intersection of cellular metabolism, oxidative stress, and disease pathology. We have witnessed a mounting fascination with ferroptosis, attributed to its pivotal roles across diverse physiological and pathological conditions including developmental processes, metabolic dynamics, oncogenic pathways, neurodegenerative cascades, and traumatic tissue injuries. By unraveling the intricate underpinnings of the molecular machinery, pivotal contributors, intricate signaling conduits, and regulatory networks governing ferroptosis, researchers aim to bridge the gap between the intricacies of this unique mode of cellular death and its multifaceted implications for health and disease. In light of the rapidly advancing landscape of ferroptosis research, we present a comprehensive review aiming at the extensive implications of ferroptosis in the origins and progress of human diseases. This review concludes with a careful analysis of potential treatment approaches carefully designed to either inhibit or promote ferroptosis. Additionally, we have succinctly summarized the potential therapeutic targets and compounds that hold promise in targeting ferroptosis within various diseases. This pivotal facet underscores the burgeoning possibilities for manipulating ferroptosis as a therapeutic strategy. In summary, this review enriched the insights of both investigators and practitioners, while fostering an elevated comprehension of ferroptosis and its latent translational utilities. By revealing the basic processes and investigating treatment possibilities, this review provides a crucial resource for scientists and medical practitioners, aiding in a deep understanding of ferroptosis and its effects in various disease situations.

Trends in metabolic dysfunction in polycystic ovary syndrome: a bibliometric analysis

Polycystic ovary syndrome (PCOS) is a very common chronic disease and causes reproductive disorders in women of childbearing age worldwide. The cause of metabolic dysfunction in PCOS is unknown, and there is a lack of systematic bibliometric analysis for this disease. This study included 3,972 articles on metabolic dysfunction in PCOS published from 2012 to 2021. We applied the VOSviewer and the CiteSpace scientometric analysis software to analyze the data regarding the publication of the articles, countries, authors, institutions, scientific categories, cited journals, and keywords. Through this analysis, we determined the research efforts and their developing trends and anticipated the progress in understanding PCOS-related metabolic dysfunction.

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

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

Investigation of the Potential Phlorotannins and Mechanism of Six Brown Algae in Treating Type II Diabetes Mellitus Based on Biological Activity, UPLC-QE-MS/MS, and Network Pharmacology

Type 2 diabetes mellitus (T2DM) has developed into an important health concern worldwide. The discovery of phlorotannins and their efficacy in the treatment of T2DM has become a hotspot for research in various fields. In this study, the potential phlorotannins and mechanism of six brown algae against T2DM were in-depth investigated using biological activity assays, LC-MS, and network pharmacology. First, the ethyl acetate fraction (EA frac.) showed high polyphenolic content and possessed significantly antioxidant and enzyme inhibitory abilities. Further, a total of fifty-nine peaks were obtained from six EA fracs. via UPLC-QE-MS/MS analysis, and fifteen of them were identified as phlorotannins and their isomers or derivatives. In detail, the chemical structures of six phlorotannins were inferred as dibenzodioxine-1,3,6,8-tetraol, bifuhalol, dioxinodehydroeckol, eckol, fucofurodiphlorethol, and fucotriphlorethol; three phlorotannin isomers were deduced to be fucophlorethol, trifucol, triphlorethol A, or triphlorethol B; and the phlorotannin derivative of m/z 263 was determined to be dibenzodioxine-1,2,3,6,8-pentanol or dibenzodioxine-1,2,4,5,7-pentanol. Moreover, 43 T2DM-related targets acted on by these chemicals were identified, and the function of phlorotannin to prevent and treat T2DM was elucidated in a holistic way based on the established compound-target-disease network, and GO function and KEGG pathway enrichment analysis.

Comparison of Protective Effects of Phenolic Acids on Protein Glycation of BSA Supported by In Vitro and Docking Studies

Several diabetic complications are associated with forming advanced glycation end products (AGEs). Different chemical and natural compounds are able to prevent the development of these products. In this study, glycosylation was induced as a model by incubating bovine serum albumin (BSA) with glucose. Consequently, BSA was treated with glucose and different concentrations (1.25, 2.5, and 5 μM) of syringic acid, gallic acid, ellagic acid, ferulic acid, paracoumaric acid, and caffeic acid for 4 and 6 weeks. Biochemical experiments comprise measurements of fluorescent AGEs, protein carbonyl contents, total thiol, hemolysis tests, and also malondialdehyde (MDA) levels in RBC. These demonstrated the antiglycating mechanism of these phenolic acids. Most of the phenolic acids used in this study reduced MDA levels and protected thiol residues in protein structures. They also inhibited the formation of fluorescent AGEs and RBC lysis, except gallic acid. Moreover, ferulic acid, paracoumaric acid, and caffeic acid proteins significantly prevent carbonylation. Molecular docking and simulation studies showed that ellagic, caffeic, gallic, and syringic acids could interact with lysine and arginine residues in the active site of BSA and stabilize its structure to inhibit the formation of AGEs. Our results suggest that phenolic acid could be used as a potential phytochemical against protein glycation and related diabetic complications.

Pharmaceutical Therapies for Necroptosis in Myocardial Ischemia-Reperfusion Injury

Cardiovascular disease morbidity/mortality are increasing due to an aging population and the rising prevalence of diabetes and obesity. Therefore, innovative cardioprotective measures are required to reduce cardiovascular disease morbidity/mortality. The role of necroptosis in myocardial ischemia-reperfusion injury (MI-RI) is beyond doubt, but the molecular mechanisms of necroptosis remain incompletely elucidated. Growing evidence suggests that MI-RI frequently results from the superposition of multiple pathways, with autophagy, ferroptosis, and CypD-mediated mitochondrial damage, and necroptosis all contributing to MI-RI. Receptor-interacting protein kinases (RIPK1 and RIPK3) as well as mixed lineage kinase domain-like pseudokinase (MLKL) activation is accompanied by the activation of other signaling pathways, such as Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), NF-κB, and JNK-Bnip3. These pathways participate in the pathological process of MI-RI. Recent studies have shown that inhibitors of necroptosis can reduce myocardial inflammation, infarct size, and restore cardiac function. In this review, we will summarize the molecular mechanisms of necroptosis, the links between necroptosis and other pathways, and current breakthroughs in pharmaceutical therapies for necroptosis.

Advanced glycation end product signaling and metabolic complications: Dietary approach

Advanced glycation end products (AGEs) are a heterogeneous collection of compounds formed during industrial processing and home cooking through a sequence of nonenzymatic glycation reactions. The modern western diet is full of heat-treated foods that contribute to AGE intake. Foods high in AGEs in the contemporary diet include processed cereal products. Due to industrialization and marketing strategies, restaurant meals are modified rather than being traditionally or conventionally cooked. Fried, grilled, baked, and boiled foods have the greatest AGE levels. Higher AGE-content foods include dry nuts, roasted walnuts, sunflower seeds, fried chicken, bacon, and beef. Animal proteins and processed plant foods contain furosine, acrylamide, heterocyclic amines, and 5-hydroxymethylfurfural. Furosine (2-furoil-methyl-lysine) is an amino acid found in cooked meat products and other processed foods. High concentrations of carboxymethyl-lysine, carboxyethyl-lysine, and methylglyoxal-O are found in heat-treated nonvegetarian foods, peanut butter, and cereal items. Increased plasma levels of AGEs, which are harmful chemicals that lead to age-related diseases and physiological aging, diabetes, and autoimmune/inflammatory rheumatic diseases such as systemic lupus erythematosus and rheumatoid arthritis. AGEs in the pathophysiology of metabolic diseases have been linked to individuals with diabetes mellitus who have peripheral nerves with high amounts of AGEs and diabetes has been linked to increased myelin glycation. Insulin resistance and hyperglycemia can impact numerous human tissues and organs, leading to long-term difficulties in a number of systems and organs, including the cardiovascular system. Plasma AGE levels are linked to all-cause mortality in individuals with diabetes who have fatal or nonfatal coronary artery disease, such as ventricular dysfunction. High levels of tissue AGEs are independently associated with cardiac systolic dysfunction in diabetic patients with heart failure compared with diabetic patients without heart failure. It is widely recognized that AGEs and oxidative stress play a key role in the cardiovascular complications of diabetes because they both influence and are impacted by oxidative stress. All chronic illnesses involve protein, lipid, or nucleic acid modifications including crosslinked and nondegradable aggregates known as AGEs. Endogenous AGE formation or dietary AGE uptake can result in additional protein modifications and stimulation of several inflammatory signaling pathways. Many of these systems, however, require additional explanation because they are not entirely obvious. This review summarizes the current evidence regarding dietary sources of AGEs and metabolism-related complications associated with AGEs.

Advanced glycation end products impair coronary artery BK channels via AMPK/Akt/FBXO32 signaling pathway

Background: Advanced glycation end products (AGEs) impair vascular physiology in Diabetes mellitus (DM). However, the underlying mechanisms remain unclear. Vascular large conductance calcium-activated potassium (BK) channels play important roles in coronary arterial function.Purpose: Our study aimed to investigate the regulatory role of AGEs in BK channels.Research Design: Using gavage of vehicle (V, normal saline) or aminoguanidine (A) for 8 weeks, normal and diabetic rats were divided into four groups: C+V group, DM+V group, C+A group, and DM+A group.Study Sample: Coronary arteries from different groups of rats and human coronary smooth muscle cells were used in this study.Data Collection and Analysis: Data were presented as mean ± SEM (standard error of mean). Student's t-test was used to compare data between two groups. One-way ANOVA with post-hoc LSD analysis was used to compare data between multiple groups.Results: Compared to the C+V group, vascular contraction induced by iberiotoxin (IBTX), a BK channel inhibitor, was impaired, and BK channel densities decreased in the DM+V group. However, aminoguanidine administration reduced the impairment. Protein expression of BK-β1, phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK), and protein kinase B (PKB or Akt) were down-regulated, while F-box protein 32 (FBXO32) expression increased in the DM+V group and in high glucose (HG) cultured human coronary smooth muscle cells. Treatment with aminoguanidine in vitro and in vivo could reverse the above protein expression. The effect of aminoguanidine on the improvement of BK channel function by inhibiting the generation of AGEs was reversed by adding MK2206 (Akt inhibitor) or Compound C (AMPK inhibitor) in HG conditions in vitro.Conclusions: AGEs aggravate BK channel dysfunction via the AMPK/Akt/FBXO32 signaling pathway.

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.

Mechanisms of diabetic foot ulceration: A review

Diabetic foot ulcers (DFUs) are associated with complex pathogenic factors and are considered a serious complication of diabetes. The potential mechanisms underlying DFUs have been increasingly investigated. Previous studies have focused on the three aspects of diabetic peripheral vascular disease, neuropathy, and wound infections. With advances in technology, researchers have been gradually conducting studies using immune cells, endothelial cells, keratinocytes, and fibroblasts, as they are involved in wound healing. It has been reported that the upregulation or downregulation of molecular signaling pathways is essential for the healing of DFUs. With a recent increase in the awareness of epigenetics, its regulatory role in wound healing has become a much sought-after trend in the treatment of DFUs. This review focuses on four aspects involved in the pathogenesis of DFUs: physiological and pathological mechanisms, cellular mechanisms, molecular signaling pathway mechanisms, and epigenetics. Given the challenge in the treatment of DFUs, we are hopeful that our review will provide new ideas for peers.

Effects of highland barley β-glucan on blood glucose and gut microbiota in streptozotocin-induced, diabetic, C57BL/6 mice on a high-fat diet

OBJECTIVES

This study aimed to investigate the hypoglycemic effect of highland barley β-glucan (HBG) on mice with type 2 diabetes (T2D), and determine whether the hypoglycemic effects are related to modulations of the gut microbiota.

METHODS

T2D was induced with a high-fat diet and streptozotocin in the mice. HBG was orally administered to mice with T2D for 4 wk, and biochemical indices were analyzed in the serum and liver. Fecal samples were collected and analyzed with high-throughput 16S ribosomal RNA sequencing.

RESULTS

Intake of HBG for 4 wk suppressed the body weight, as well as liver and heart indices, and regulated the levels of fasting blood glucose, serum insulin, blood lipid, oxidative damage, and inflammatory reaction in mice with T2D. Furthermore, HBG reversed the gut microbiota dysbiosis in mice with T2D by increasing the abundance of Lachnospiraceae_UCG-006, Streptococcaceae, and Eggerthellaceae, and by decreasing the abundance of Parasutterella.

CONCLUSIONS

Our findings indicate that the antidiabetic abilities of HBG might be related to the improvement of gut microbiota imbalance.

The Patient's Physiological Status at the Start Determines the Success of the Inpatient Cardiovascular Rehabilitation Program

Multidisciplinary inpatient rehabilitation plays an important role in the recovery of patients with cardiovascular diseases (CVDs). Lifestyle changes, achieved by exercise, diet, weight loss and patient education programs, are the first steps to a healthier life. Advanced glycation end products (AGEs) and their receptor (RAGE) are known to be involved in CVDs. Clarification on whether initial AGE levels can influence the rehabilitation outcome is important. Serum samples were collected at the beginning and end of the inpatient rehabilitation stay and analyzed for parameters: lipid metabolism, glucose status, oxidative stress, inflammation and AGE/RAGE-axis. As result, a 5% increase in the soluble isoform RAGE (sRAGE) (T₀: 891.82 ± 44.97 pg/mL, T₁: 937.17 ± 43.29 pg/mL) accompanied by a 7% decrease in AGEs (T₀: 10.93 ± 0.65 µg/mL, T₁: 10.21 ± 0.61 µg/mL) was shown. Depending on the initial AGE level, a significant reduction of 12.2% of the AGE activity (quotient AGE/sRAGE) was observed. We found that almost all measured factors improved. Summarizing, CVD-specific multidisciplinary rehabilitation positively influences disease-associated parameters, and thus provides an optimal starting point for subsequent disease-modifying lifestyle changes. Considering our observations, the initial physiological situations of patients at the beginning of their rehabilitation stay seem to play a decisive role regarding the assessment of rehabilitation success.

The Central Role of the NAD+ Molecule in the Development of Aging and the Prevention of Chronic Age-Related Diseases: Strategies for NAD+ Modulation

The molecule NAD+ is a coenzyme for enzymes catalyzing cellular redox reactions in several metabolic pathways, encompassing glycolysis, TCA cycle, and oxidative phosphorylation, and is a substrate for NAD+-dependent enzymes. In addition to a hydride and electron transfer in redox reactions, NAD+ is a substrate for sirtuins and poly(adenosine diphosphate-ribose) polymerases and even moderate decreases in its cellular concentrations modify signaling of NAD+-consuming enzymes. Age-related reduction in cellular NAD+ concentrations results in metabolic and aging-associated disorders, while the consequences of increased NAD+ production or decreased degradation seem beneficial. This article reviews the NAD+ molecule in the development of aging and the prevention of chronic age-related diseases and discusses the strategies of NAD+ modulation for healthy aging and longevity.

Cathepsin D Attenuates the Proliferation of Vascular Smooth Muscle Cells Induced by the AGE/RAGE Pathway by Suppressing the ERK Signal

BACKGROUND

In this study, we aimed to clarify the role and mechanism by which Cathepsin D (CTSD) mediates the advanced glycation end products (AGEs)-induced proliferation of vascular smooth muscle cells (VSMCs).

METHODS

We conducted a Western blotting assay and co-immunoprecipitation assay to detect the expression of target proteins and the interaction between different proteins. Cell Counting Kit-8 (CCK-8) assay and 5- ethynyl-2'-deoxyuridine (EdU) were used to evaluate the proliferation.

RESULTS

AGEs significantly promoted phenotypic switching and proliferation of VSMCs in a concentration-dependent manner. This effect of AGEs was accompanied by inhibition of CTSD. Both the proliferation of VSMCs and inhibition of CTSD induced by AGEs could be attenuated by the specific inhibitor of the receptor for advanced glycation end products (RAGE), FPS-ZM1. Overexpression of CTSD significantly alleviated these effects of AGEs on VSMCs. The mechanism of CTSD action in VSMCs was also explored. Overexpression of CTSD reduced the activation of p-ERK caused by AGEs. By contrast, the knockdown of CTSD, elicited using a plasmid containing short hairpin RNA (shRNA) against CTSD, further increased the activation of p-ERK compared to AGEs alone. Additionally, co-immunoprecipitation studies revealed an endogenous interaction between CTSD, a protease, and p-ERK, its potential substrate.

CONCLUSION

It has been demonstrated that CTSD downregulates the level of phosphorylated ERK by degrading its target, and this interaction plays a critical role in the proliferation of VSMCs induced by the AGE/RAGE axis. These results provide a novel insight into the prevention and treatment of vascular complications in diabetes.

Combined Effects of Lycopene and Metformin on Decreasing Oxidative Stress by Triggering Endogenous Antioxidant Defenses in Diet-Induced Obese Mice

Since lycopene has antioxidant activity, its combination with metformin may be useful to contrast diabetic complications related to oxidative stress. This study aimed to investigate the effects of metformin combined with lycopene on high-fat diet (HFD)-induced obese mice. Seventy-two C57BL-6J mice were divided into six groups: C (control diet-fed mice), H (HFD-fed mice for 17 weeks), H-V (HFD-fed mice treated with vehicle), H-M (HFD-fed mice treated with 50 mg/kg metformin), H-L (HFD-fed mice treated with 45 mg/kg lycopene), and H-ML (HFD-fed mice treated with 50 mg/kg metformin + 45 mg/kg lycopene). Treatments were administered for 8 weeks. Glucose tolerance, insulin sensitivity, fluorescent AGEs (advanced glycation end products), TBARS (thiobarbituric acid-reactive substances), and activities of antioxidant enzymes paraoxonase-1 (PON-1; plasma), superoxide dismutase, catalase and glutathione peroxidase (liver and kidneys) were determined. Metformin plus lycopene reduced body weight; improved insulin sensitivity and glucose tolerance; and decreased AGEs and TBARS in plasma, liver and kidneys. Combined therapy significantly increased the activities of antioxidant enzymes, mainly PON-1. Lycopene combined with metformin improved insulin resistance and glucose tolerance, and caused further increases in endogenous antioxidant defenses, arising as a promising therapeutic strategy for combating diabetic complications resulting from glycoxidative stress.

Receptor for Advanced Glycation End Product, Organ Crosstalk, and Pathomechanism Targets for Comprehensive Molecular Therapeutics in Diabetic Ischemic Stroke

Diabetes mellitus, a well-established risk factor for stroke, is related to higher mortality and poorer outcomes following the stroke event. Advanced glycation end products(AGEs), their receptors RAGEs, other ligands, and several other processes contribute to the cerebrovascular pathomechanism interaction in the diabetes-ischemic stroke combination. Critical reappraisal of molecular targets and therapeutic agents to mitigate them is required to identify key elements for therapeutic interventions that may improve patient outcomes. This scoping review maps evidence on the key roles of AGEs, RAGEs, other ligands such as Leukotriene B4 (LTB4), High-mobility group box 1 (HMGB1) nuclear protein, brain-kidney-muscle crosstalk, alternate pathomechanisms in neurodegeneration, and cognitive decline related to diabetic ischemic stroke. RAGE, HMGB1, nitric oxide, and polyamine mechanisms are important therapeutic targets, inflicting common consequences of neuroinflammation and oxidative stress. Experimental findings on a number of existing-emerging therapeutic agents and natural compounds against key targets are promising. The lack of large clinical trials with adequate follow-up periods is a gap that requires addressing to validate the emerging therapeutic agents. Five therapeutic components, which include agents to mitigate the AGE-RAGE axis, improved biomarkers for risk stratification, better renal dysfunction management, adjunctive anti-inflammatory-antioxidant therapies, and innovative neuromuscular stimulation for rehabilitation, are identified. A comprehensive therapeutic strategy that features all the identified components is needed for outcome improvement in diabetic stroke patients.

Association of glycated albumin to hemoglobin A1c ratio with all-cause and cardiovascular mortality among US adults: A population-based cohort study

AIMS

To investigate the association of glycated albumin to hemoglobin A1c (GA/HbA1c) ratio, an indicator of blood glucose fluctuations, with all-cause and cardiovascular mortality among US adults.

METHODS

This cohort study used data from the National Health and Nutrition Examination Survey 1999-2004. Participants were linked to National Death Index mortality data through December 31, 2015. Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), and restricted cubic spline (RCS) regression was conducted.

RESULTS

A total of 11,508 US adults (weighted mean age, 43.9 years; 5748 males [weighted, 48.9 %]) were included. During a median follow‑up of 13.6 years, 1963 total deaths occurred, including 383 cardiovascular deaths. After multivariable adjustments, a higher GA/HbA1c ratio was associated with a higher risk of all-cause (tertiles: P for trend < 0.001; continuous: HR 1.49 [95 % CI 1.32-1.69]) and cardiovascular (tertiles: P for trend = 0.048; continuous: HR 1.65 [95 % CI 1.27-2.14]) mortality. RCS revealed a linear relationship of GA/HbA1c ratio to mortality.

CONCLUSIONS

In the nationally representative cohort of US adults, GA/HbA1c ratio was significantly associated with the risk of all-cause and cardiovascular mortality. These findings suggest that GA/HbA1c ratio may serve as an effective indicator for identifying high-risk individuals.

The Therapeutic Roles of Cinnamaldehyde against Cardiovascular Diseases

Evidence from epidemiological studies has demonstrated that the incidence and mortality of cardiovascular diseases (CVDs) increase year by year, which pose a great threat on social economy and human health worldwide. Due to limited therapeutic benefits and associated adverse effects of current medications, there is an urgent need to uncover novel agents with favorable safety and efficacy. Cinnamaldehyde (CA) is a bioactive phytochemical isolated from the stem bark of Chinese herbal medicine Cinnamon and has been suggested to possess curative roles against the development of CVDs. This integrated review intends to summarize the physicochemical and pharmacokinetic features of CA and discuss the recent advances in underlying mechanisms and potential targets responsible for anti-CVD properties of CA. The CA-related cardiovascular protective mechanisms could be attributed to the inhibition of inflammation and oxidative stress, improvement of lipid and glucose metabolism, regulation of cell proliferation and apoptosis, suppression of cardiac fibrosis, and platelet aggregation and promotion of vasodilation and angiogenesis. Furthermore, CA is likely to inhibit CVD progression via affecting other possible processes including autophagy and ER stress regulation, gut microbiota and immune homeostasis, ion metabolism, ncRNA expression, and TRPA1 activation. Collectively, experiments reported previously highlight the therapeutic effects of CA and clinical trials are advocated to offer scientific basis for the compound future applied in clinical practice for CVD prophylaxis and treatment.

Shear Stress and Metabolic Disorders-Two Sides of the Same Plaque

Significance: Shear stress and metabolic disorder are the two sides of the same atherosclerotic coin. Atherosclerotic lesions are prone to develop at branches and curvatures of arteries, which are exposed to oscillatory and low shear stress exerted by blood flow. Meanwhile, metabolic disorders are pivotal contributors to the formation and advancement of atherosclerotic plaques. Recent Advances: Accumulated evidence has provided insight into the impact and mechanisms of biomechanical forces and metabolic disorder on atherogenesis, in association with mechanotransduction, epigenetic regulation, and so on. Moreover, recent studies have shed light on the cross talk between the two drivers of atherosclerosis. Critical Issues: There are extensive cross talk and interactions between shear stress and metabolic disorder during the pathogenesis of atherosclerosis. The communications may amplify the proatherogenic effects through increasing oxidative stress and inflammation. Nonetheless, the precise mechanisms underlying such interactions remain to be fully elucidated as the cross talk network is considerably complex. Future Directions: A better understanding of the cross talk network may confer benefits for a more comprehensive clinical management of atherosclerosis. Critical mediators of the cross talk may serve as promising therapeutic targets for atherosclerotic vascular diseases, as they can inhibit effects from both sides of the plaque. Hence, further in-depth investigations with advanced omics approaches are required to develop novel and effective therapeutic strategies against atherosclerosis. Antioxid. Redox Signal. 37, 820-841.

Glycyrrhizic Acid and Its Derivatives: Promising Candidates for the Management of Type 2 Diabetes Mellitus and Its Complications

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease, which is characterized by hyperglycemia, chronic insulin resistance, progressive decline in β-cell function, and defect in insulin secretion. It has become one of the leading causes of death worldwide. At present, there is no cure for T2DM, but it can be treated, and blood glucose levels can be controlled. It has been reported that diabetic patients may suffer from the adverse effects of conventional medicine. Therefore, alternative therapy, such as traditional Chinese medicine (TCM), can be used to manage and treat diabetes. In this review, glycyrrhizic acid (GL) and its derivatives are suggested to be promising candidates for the treatment of T2DM and its complications. It is the principal bioactive constituent in licorice, one type of TCM. This review comprehensively summarized the therapeutic effects and related mechanisms of GL and its derivatives in managing blood glucose levels and treating T2DM and its complications. In addition, it also discusses existing clinical trials and highlights the research gap in clinical research. In summary, this review can provide a further understanding of GL and its derivatives in T2DM as well as its complications and recent progress in the development of potential drugs targeting T2DM.

The mechanisms of glycolipid metabolism disorder on vascular injury in type 2 diabetes

Patients with diabetes have severe vascular complications, such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, and neuropathy. Devastating vascular complications lead to increased mortality, blindness, kidney failure, and decreased overall quality of life in people with type 2 diabetes (T2D). Glycolipid metabolism disorder plays a vital role in the vascular complications of T2D. However, the specific mechanism of action remains to be elucidated. In T2D patients, vascular damage begins to develop before insulin resistance and clinical diagnosis. Endothelial dysregulation is a significant cause of vascular complications and the early event of vascular injury. Hyperglycemia and hyperlipidemia can trigger inflammation and oxidative stress, which impair endothelial function. Furthermore, during the pathogenesis of T2D, epigenetic modifications are aberrant and activate various biological processes, resulting in endothelial dysregulation. In the present review, we provide an overview and discussion of the roles of hyperglycemia- and hyperlipidemia-induced endothelial dysfunction, inflammatory response, oxidative stress, and epigenetic modification in the pathogenesis of T2D. Understanding the connections of glucotoxicity and lipotoxicity with vascular injury may reveal a novel potential therapeutic target for diabetic vascular complications.

Association of hemoglobin glycation index and glycation gap with cardiovascular disease among US adults

AIMS

To investigate the association of hemoglobin glycation index (HGI) and glycation gap (GGap), reflecting mismatches between HbA1c and other measures of glycemia, with cardiovascular disease (CVD) in the general population.

METHODS

5966 US adult (age ≥ 20 years) participants were included from the National Health and Nutrition Examination Survey (NHANES) (1999-2004). In this cross-sectional study, predicted HbA1c was calculated based on fasting plasma glucose (FPG) and glycated albumin (GA), respectively. Multivariable binary logistic regression analysis was performed to explore the association of HGI and GGap with CVD prevalence.

RESULTS

Compared to the lowest tertile, the ORs with 95% CIs for CVD across the tertiles were 1.41 (1.01, 1.96) and 0.87 (0.58, 1.31) for HGI (P for trend = 0.535) and 1.06 (0.77, 1.47) and 1.60 (1.18, 2.17) for GGap (P for trend = 0.002) in the fully-adjusted model. Besides, the discordantly high GGap/low HbA1c group was associated with higher CVD prevalence compared with the low GGap/high HbA1c group (OR = 1.50, 95% CI, 1.04-2.16, P = 0.030).

CONCLUSIONS

GGap derived from GA is associated with CVD independent of traditional risk factors, even HbA1c, in US general adults. Considering the potential limitations of HbA1c, the introduction of GGap is warranted.

Caloric restriction-mimetics for the reduction of heart failure risk in aging heart: with consideration of gender-related differences

The literature is full of claims regarding the consumption of polyphenol or polyamine-rich foods that offer some protection from developing cardiovascular disease (CVD). This is achieved by preventing cardiac hypertrophy and protecting blood vessels through improving the function of endothelium. However, do these interventions work in the aged human hearts? Cardiac aging is accompanied by an increase in left ventricular hypertrophy, along with diastolic and systolic dysfunction. It also confers significant cardiovascular risks for both sexes. The incidence and prevalence of CVD increase sharply at an earlier age in men than women. Furthermore, the patterns of heart failure differ between sexes, as do the lifetime risk factors. Do caloric restriction (CR)-mimetics, rich in polyphenol or polyamine, delay or reverse cardiac aging equally in both men and women? This review will discuss three areas: (1) mechanisms underlying age-related cardiac remodeling; (2) gender-related differences and potential mechanisms underlying diminished cardiac response in older men and women; (3) we select a few polyphenol or polyamine rich compounds as the CR-mimetics, such as resveratrol, quercetin, curcumin, epigallocatechin gallate and spermidine, due to their capability to extend health-span and induce autophagy. We outline their abilities and issues on retarding aging in animal hearts and preventing CVD in humans. We discuss the confounding factors that should be considered for developing therapeutic strategies against cardiac aging in humans.

Inhibition of Gli1 suppressed hyperglycemia-induced meibomian gland dysfunction by promoting pparγ expression

Diabetes is one of the risk factors for meibomian gland dysfunction (MGD); however, the underlying molecular mechanism remains unknown. The current study aims to examine the effects of glioma-associated oncogene homolog 1 (Gli1), a transcription factor of the sonic hedgehog (Shh) pathway, in the modulation of diabetic-related MGD. Here, using RNA sequencing and qRT-PCR, we examined the mRNA changes of Shh pathway involving genes. mRNA sequencing analysis showed that the Shh pathway involving genes Shh and Gli1 were markedly upregulated in diabetic MG, and qRT-PCR detection of Shh pathway-associated genes found that Gli1 expression increased most significantly. Contrary to the elevation of Gli1 level, the expression of pparγ was downregulated in diabetic MG and in high glucose treated organotypic cultured mouse MG. GANT61, an inhibitor of Gli1, effectively inhibited the reduction of pparγ expression and lipid accumulation induced by high glucose, which was suppressed by pparγ inhibitor T0070907. We further demonstrated that advanced glycation end products (AGEs) treatment also promoted the expression of Gli1 and pparγ in organotypic cultured mouse MG. AGEs inhibitor Aminoguanidine suppressed high glucose caused Gli1 upregulation in organotypic cultured mouse MG. These results suggest that suppression of Gli1 may be a potentially useful therapeutic option for diabetic-related MGD.

Bioavailability of Hesperidin and Its Aglycone Hesperetin—Compounds Found in Citrus Fruits as a Parameter Conditioning the Pro-Health Potential (Neuroprotective and Antidiabetic Activity)—Mini-Review

Hesperidin and hesperetin are polyphenols that can be found predominantly in citrus fruits. They possess a variety of pharmacological properties such as neuroprotective and antidiabetic activity. However, the bioavailability of these compounds is limited due to low solubility and restricts their use as pro-healthy agents. This paper described the limitations resulting from the low bioavailability of the presented compounds and gathered the methods aiming at its improvement. Moreover, this work reviewed studies providing pieces of evidence for neuroprotective and antidiabetic properties of hesperidin and hesperetin as well as providing a detailed look into the significance of reported modes of action in chronic diseases. On account of a well-documented pro-healthy activity, it is important to look for ways to overcome the problem of poor bioavailability.

Ca2+/Calmodulin-Dependent Protein Kinase II Regulation by Inhibitor of Receptor Interacting Protein Kinase 3 Alleviates Necroptosis in Glycation End Products-Induced Cardiomyocytes Injury

Necroptosisis a regulatory programmed form of necrosis. Receptor interacting protein kinase 3 (RIPK3) is a robust indicator of necroptosis. RIPK3 mediates myocardial necroptosis through activation of calcium/calmodulin-dependent protein kinase II (CaMKII) in cardiac ischemia-reperfusion (I/R) injury and heart failure. However, the exact mechanism of RIPK3 in advanced glycation end products (AGEs)-induced cardiomyocytes necroptosis is not clear. In this study, cardiomyocytes were subjected to AGEs stimulation for 24 h. RIPK3 expression, CaMKII expression, and necroptosis were determined in cardiomyocytes after AGEs stimulation. Then, cardiomyocytes were transfected with RIPK3 siRNA to downregulate RIPK3 followed by AGEs stimulation for 24 h. CaMKIIδ alternative splicing, CaMKII activity, oxidative stress, necroptosis, and cell damage were detected again. Next, cardiomyocytes were pretreated with GSK′872, a specific RIPK3 inhibitor to assess whether it could protect cardiomyocytes against AGEs stimulation. We found that AGEs increased the expression of RIPK3, aggravated the disorder of CaMKII δ alternative splicing, promoted CaMKII activation, enhanced oxidative stress, induced necroptosis, and damaged cardiomyocytes. RIPK3 downregulation or RIPK3 inhibitor GSK′872 corrected CaMKIIδ alternative splicing disorder, inhibited CaMKII activation, reduced oxidative stress, attenuated necroptosis, and improved cell damage in cardiomyocytes.

High serum levels of N-epsilon-carboxymethyllysine are associated with poor coronary collateralization in type 2 diabetic patients with chronic total occlusion of coronary artery

Background

The formation of advanced glycation end-products (AGEs) is a crucial risk factor for the pathogenesis of cardiovascular diseases in diabetes. We investigated whether N-epsilon-carboxymethyllysine (CML), a major form of AGEs in vivo, was associated with poor coronary collateral vessel (CCV) formation in patients with type 2 diabetes mellitus (T2DM) and chronic total occlusion (CTO) of coronary artery.

Methods

This study consisted of 242 T2DM patients with coronary angiographically documented CTO. Blood samples were obtained and demographic/clinical characteristics were documented. The coronary collateralization of these patients was defined according to Rentrop or Werner classification. Serum CML levels were evaluated using ELISA assay. Receiver operating characteristic curve and multivariable regression analysis were performed.

Results

242 patients were categorized into poor CCV group or good CCV group (107 vs. 135 by the Rentrop classification or 193 vs. 49 by the Werner classification, respectively). Serum CML levels were significantly higher in poor CCV group than in good CCV group (110.0 ± 83.35 vs. 62.95 ± 58.83 ng/ml by the Rentrop classification and 94.75 ± 78.29 ng/ml vs. 40.37 ± 28.69 ng/ml by Werner classification, both P < 0.001). Moreover, these CML levels were also significantly different across the Rentrop and Werner classification subgroups (P < 0.001). In multivariable logistic regression, CML levels (P < 0.001) remained independent determinants of poor CCV according to the Rentrop or Werner classification after adjustment of traditional risk factors.

Conclusions

This study suggests that higher serum CML level is associated with poor collateralization in T2DM patients with CTO.

Development and validation of a nomogram based on the hospital information system for quantitative assessment of the risk of cardiocerebrovascular complications of diabetes

Background

Although the prevention and treatment of the cardiocerebrovascular complications (CCVCs) of diabetes have been clarified, their incidence is still high. This is largely due to the lack of predictive models to objectively assess the risk of CCVC in patients with type 2 diabetes mellitus (T2DM), reducing their treatment adherence. Despite the fact that the risk factors of CCVC in T2DM patients have been identified, no prediction model for identifying T2DM patients with the risk of CCVC is available. Therefore, the aim of this study is to establish a nomogram based on hospital information system data to quantitatively assess the risk of CCVCs in T2DM patients. This model is contributed to individualized therapeutic treatments and motivating T2DM patients to adhere to lifestyle interventions.

Methods

The medical records of 1,556 T2DM patients, comprising 1,145 cases in the training cohort and 411 in the validation cohort were retrospectively analyzed. CCVCs of diabetes, including coronary heart disease, cerebral ischemia, and intracerebral hemorrhage, were extracted from the medical records. Univariate and multivariate logistic regression analyses were performed to screen the independent correlates of CCVCs from the demographic information and laboratory test data, which were utilized to establish a nomogram for predicting the risk of CCVCs in these patients. We used internal and external validation based on the training and validation cohorts to evaluate the model performance.

Results

The incidence of CCVCs in the training cohort (26.99%) was similar to the validation cohort (25.79%). Disease duration, body mass index (BMI), systolic blood pressure (SBP), glycosylated hemoglobin (HbA1c), and uric acid (UA) levels were finally included in the established nomogram. In both the internal and external validation, the nomogram showed good discrimination [area under the curve (AUC) =0.850 and 0.825, respectively] and calibration (P=0.127 and P=0.096, respectively). Decision curve analysis showed that the nomogram produced a net benefit in both the training and validation cohorts.

Conclusions

The nomogram developed for predicting the risk of CCVC in T2DM patients may help improve treatment adherence. Further multi-center prospective investigations are required to predict the timing of CVCC in T2DM patients.

A Review of Coumarins and Coumarin-Related Compounds for Their Potential Antidiabetic Effect

Background and aims:

Worldwide, type 2 diabetes mellitus accounts for a considerable burden of disease, with an estimated global cost of >800 billion USD annually. For this reason, the search for more effective and efficient therapeutic anti-diabetic agents is continuing. Coumarins are naturally derived and synthetic molecules with a wide variety of biological actions. The most common application of these molecules in medicine is for their thrombostatic activity. This study aims to give an overview of the current knowledge about the applicability of these chemical products in the therapeutic strategy against diabetes and its complications.

Methods:

For this purpose, we searched internet databases for publications and abstracts in English that investigated the effects of coumarins or coumarin-like agents with potential anti-diabetic activity.

Results:

The result is that a variety of these agents have proven in in vitro, in silico, and simple animal models to possess properties that may reduce the glucose absorption rate in the intestines, increase the level of insulin, increase the cellular uptake of glucose or reduce the gluconeogenesis. In addition, some of these agents also reduced the level of glycation of peptides in diabetic animal models and showed antioxidant properties.

Conclusion:

In conclusion, we can summarize that coumarins and their related derivatives may be potential antidiabetic agents. Useful formulations with appropriate pharmacokinetic and pharmacodynamic properties must be developed and tested for their efficacy and toxicity in comprehensive animal models before they can enter clinical trials.

JMJD1A/NR4A1 Signaling Regulates the Procession of Renal Tubular Epithelial Interstitial Fibrosis Induced by AGEs in HK-2

Diabetic kidney disease (DKD) is one of the most serious complications of diabetic patients. Advanced glycation end products (AGEs) induce epithelial-mesenchymal transformation (EMT) of renal tubular epithelial cells (HK-2), resulting in renal tubulointerstitial fibrosis. However, the underlying epigenetic mechanisms remain to be further investigated. In this work, we investigated the functional role of JMJD1A involved in DKD progression. The molecular mechanism study was performed in AGEs-induced HK-2 cells by gene expression analysis, RNA sequencing (RNA-seq), and JMJD1A lentiviral knockdown and overexpression particle transfection. The results showed that AGEs could upregulate JMJD1A, and the expressions of related fibrotic factor were also increased. At the same time, in the DKD animal model induced by unilateral nephrectomy plus streptozotocin (STZ), IHC immunohistochemical staining showed that compared with the control group, the expressions of JMJD1A, FN, and COL1 in the model group were all increased, masson staining results also show that the model group has typical fibrotic changes. This is consistent with the results of our in vitro experiments. In order to determine the downstream pathway, we screened out JMJD1A downstream transcription factors by RNA-seq. Further analysis showed that JMJD1A overexpression could accelerate the progression of AGEs-induced renal fibrosis by reducing the expression of NR4A1 in HK-2 cells. Meanwhile, NR4A1 inhibitor can promote the expression of fibrosis-related factors such as VIM, a-SMA in HK-2 cells, and aggravate the process of fibrosis. Taken together, JMJD1A/NR4A1 signaling can regulate the procession of renal tubular epithelial interstitial fibrosis induced by AGEs in HK-2.

The role of metabolic syndrome in sudden cardiac death risk: Recent evidence and future directions

Metabolic syndrome (MetS) is a frequent condition whose deleterious effects on the cardiovascular system are often underestimated. MetS is nowadays considered a real pandemic with an estimated prevalence of 25% in general population. Individuals with MetS are at high risk of sudden cardiac death (SCD) as this condition accounts for 50% of all cardiac deaths in such a population. Of interest, recent studies demonstrated that individuals with MetS show 70% increased risk of SCD even without previous history of coronary heart disease (CHD). However, little is known about the interplay between the two conditions. MetS is a complex disease determined by genetic predisposition, unhealthy lifestyle and ageing with deleterious effects on different organs. MetS components trigger a systemic chronic low-grade pro-inflammatory state, associated with excess of sympathetic activity, cardiac hypertrophy, arrhythmias and atherosclerosis. Thus, MetS has an important burden on the cardiovascular system as demonstrated by both preclinical and clinical evidence. The aim of this review is to summarize recent evidence concerning the association between MetS and SCD, showing possible common aetiological processes, and to indicate prospective for future studies and therapeutic targets.

Mechanisms underlying the pathophysiology of type 2 diabetes: From risk factors to oxidative stress, metabolic dysfunction, and hyperglycemia

Type 2 diabetes (T2D) is a complex multifactorial disease that emerges from the combination of genetic and environmental factors, and obesity, lifestyle, and aging are the most relevant risk factors. Hyperglycemia is the main metabolic feature of T2D as a consequence of insulin resistance and β-cell dysfunction. Among the cellular alterations induced by hyperglycemia, the overproduction of reactive oxygen species (ROS) and consequently oxidative stress, accompanied by a reduced antioxidant response and impaired DNA repair pathways, represent essential mechanisms underlying the pathophysiology of T2D and the development of late complications. Mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and inflammation are also closely correlated with insulin resistance and β-cell dysfunction. This review focus on the mechanisms by which oxidative stress, mitochondrial dysfunction, ER stress, and inflammation are involved in the pathophysiology of T2D, highlighting the importance of the antioxidant response and DNA repair mechanisms counteracting the development of the disease. Moreover, we indicate evidence on how nutritional interventions effectively improve diabetes care. Additionally, we address key molecular characteristics and signaling pathways shared between T2D and Alzheimer's disease (AD), which might probably be implicated in the risk of T2D patients to develop AD.

Gallic Acid Improves Diabetic Steatosis by Downregulating MicroRNA-34a-5p through Targeting NFE2L2 Expression in High-Fat Diet-Fed db/db Mice

Type 2 diabetes mellitus (T2DM) has become epidemic worldwide and is strongly associated with nonalcoholic fatty liver disease (NAFLD). The molecular mechanisms of microRNAs in NAFLD and T2DM development and the corresponding therapies remain unclear. We performed microRNA microarray validation to determine whether hepatic miR-34a-5p was significantly upregulated in db/db mice fed with a high-fat diet (HFD), a mouse model of T2DM with steatohepatitis. The potential role of miR-34a-5p and gallic acid (GA) in regulating hepatic lipid metabolism and diabetic steatosis was explored. GA improved the activities of antioxidant enzymes and suppressed lipid accumulation in the HFD-induced steatotic liver of db/db mice. In vitro, the silencing of miR-34a-5p in hepatocyte HepG2 cells ameliorated high glucose + oleic acid/palmitic acid mixture–induced accumulation of cellular triglycerides. We identified nuclear factor erythroid-derived 2-like 2 (NFE2L2) as a direct target of miR-34a-5p. Reduction in intracellular triglyceride and the expression levels of sterol regulatory element-binding protein 1 and fatty acid synthase by GA were mediated by the inhibition of miR-34a-5p expression in HepG2 cells. The findings suggest that GA improves hepatic lipogenesis by downregulating miR-34a-5p by suppressing NFE2L2 expression, indicating the potential therapeutic role of GA or an NFE2L2-activating agent in diabetic fatty liver disease.

Towards Personalized Therapy of Aortic Stenosis

Calcific aortic stenosis (CAS) is the most common cause of acquired valvular heart disease in adults with no available pharmacological treatment to inhibit the disease progression to date. This review provides an up-to-date overview of current knowledge of molecular mechanisms underlying CAS pathobiology and the related treatment pathways. Particular attention is paid to current randomized trials investigating medical treatment of CAS, including strategies based on lipid-lowering and antihypertensive therapies, phosphate and calcium metabolism, and novel therapeutic targets such as valvular oxidative stress, coagulation proteins, matrix metalloproteinases, and accumulation of advanced glycation end products.

Structural elucidation and anti-diabetic osteoporotic activity of an arabinogalactan from Phellodendron chinense Schneid

Phellodendron chinense Schneid. was widely used as a medicinal herb for the treatment of diabetic osteoporosis in China. In this study, an arabinogalactan, named as PPCP-1, was isolated from the bark of Phellodendron chinense Schneid., and purified by DEAE-cellulose DE52 and Sephacryl S-200 HR column chromatography. The structure of PPCP-1 was characterized as a repeating unit consisting of →3)-β-d-Galp-(1→, →3,6)-β-d-Galp-(1→, →5)-α-l-Araf-(1→, →4)-α-d-Glcp-(1→, →3)-α-d-Glcp-(1→, →4)-α-d-Manp-(1→ with branches of →5)-α-l-Araf-(1→, →3,5)-α-l-Araf-(1→ and terminal α-l-Araf. Pharmacologically, the oral administration of PPCP-1 preserved osteoporosis associated with hyperglycemia by inhibiting α-glucosidase activity, improving glucose tolerance, decreasing the accumulation of advanced glycation end products (AGEs), as well as down-regulating the expression of receptor for AGEs in tibias of streptozotocin-induced diabetic rats. Collectively, the present study suggested that the arabinogalactan PPCP-1 from Phellodendron chinense Schneid. might potentially be used as functional foods for bone health and/or developed for drug discovery for alleviating diabetic osteoporosis.

Influence of Chlorhexidine and Cetylpyridine on Periodontal Status and Indicators of Oxidative Stress in Patients with Type 1 Diabetes

Objective: One of the treatment goals in type 1 diabetes and periodontitis is to address chronic inflammation to prevent the development of neurovascular complications. The aim of this study was to assess the local anti-inflammatory effects of chlorhexidine digluconate and cetylpyridine chloride on periodontal status and indicators of oxidative stress in saliva in patients with type 1 diabetes. Materials and Methods: A total of 42 subjects aged 27 (interquartile range, IQR 22–35) years, with type 1 diabetes for a duration of 12 (IQR 9–18) years, and glycated hemoglobin 8.05 (IQR 7.1–9.4)% were included. Patients were examined twice—initially, and after 14 days of using toothpaste with chlorhexidine and cetylpyridine. Clinical examination of gingival tissues was performed. Certain oxidative stress markers (TP, TEAC, TBARS, AOPP) were measured in the saliva samples. Results: There were significant changes in clinical indicators of periodontal status before and after the application of the toothpaste (API before 0.35 (0.24–0.65) vs. API after 0.265 (0.18–0.39), p = 0.03; SBI before 0.07 (0.04–0.15) vs. SBI after 0.035 (0-0.06), p = 0.002; GI before 0.88 (0.46–1) vs. GI after 0.67 (0.25–1), p = 0.0008). The concentration of saliva TBARS decreased (p = 0.00005) and TEAC increased (p = 0.09). Conclusion: Proper oral hygiene supported by antibacterial chemicals may improve the periodontal status and reduce inflammation.

Angiotensin-converting enzyme inhibitors from plants: A review of their diversity, modes of action, prospects, and concerns in the management of diabetes-centric complications

Angiotensin-converting enzyme (ACE) inhibitors are antihypertensive medications often used in the treatment of diabetes-related complications. Synthetic ACE inhibitors are known to cause serious side effects like hypotension, renal insufficiency, and hyperkalaemia. Therefore, there has been an intensifying search for natural ACE inhibitors. Many plants or plant-based extracts are known to possess ACE-inhibitory activity. In this review, articles focusing on the natural ACE inhibitors extracted from plants were retrieved from databases like Google Scholar, PubMed, Scopus, and Web of Science. We have found more than 50 plant species with ACE-inhibitory activity. Among them, Angelica keiskei, Momordica charantia, Muntingia calabura, Prunus domestica, and Peperomia pellucida were the most potent, showing comparatively lower half-maximal inhibitory concentration values. Among the bioactive metabolites, peptides (e.g., Tyr-Glu-Pro, Met-Arg-Trp, and Gln-Phe-Tyr-Ala-Val), phenolics (e.g., cyanidin-3-O-sambubioside and delphinidin-3-O-sambubioside), flavonoids ([-]-epicatechin, astilbin, and eupatorin), terpenoids (ursolic acid and oleanolic acid) and alkaloids (berberine and harmaline) isolated from several plant and fungus species were found to possess significant ACE-inhibitory activity. These were also known to possess promising antioxidant, antidiabetic, antihyperlipidemic and anti-inflammatory activities. Considering the minimal side effects and lower toxicity of herbal compounds, development of antihypertensive drugs from these plant extracts or phytocompounds for the treatment of diabetes-associated complications is an important endeavour. This review, therefore, focuses on the ACE inhibitors extracted from different plant sources, their possible mechanisms of action, present status, and any safety concerns.

Role of Advanced Glycation End-Products and Other Ligands for AGE Receptors in Thyroid Cancer Progression

To date, thyroid cancers (TCs) remain a clinical challenge owing to their heterogeneous nature. The etiopathology of TCs is associated not only with genetic mutations or chromosomal rearrangements, but also non-genetic factors, such as oxidative-, nitrosative-, and carbonyl stress-related alterations in tumor environment. These factors, through leading to the activation of intracellular signaling pathways, induce tumor tissue proliferation. Interestingly, the incidence of TCs is often coexistent with various simultaneous mutations. Advanced glycation end-products (AGEs), their precursors and receptors (RAGEs), and other ligands for RAGEs are reported to have significant influence on carcinogenesis and TCs progression, inducing gene mutations, disturbances in histone methylation, and disorders in important carcinogenesis-related pathways, such as PI₃K/AKT/NF-kB, p21/MEK/MPAK, or JAK/STAT, RAS/ERK/p53, which induce synthesis of interleukins, growth factors, and cytokines, thus influencing metastasis, angiogenesis, and cancer proliferation. Precursors of AGE (such as methylglyoxal (MG)) and selected ligands for RAGEs: AS1004, AS1008, and HMGB1 may, in the future, become potential targets for TCs treatment, as low MG concentration is associated with less aggressive anaplastic thyroid cancer, whereas the administration of anti-RAGE antibodies inhibits the progression of papillary thyroid cancer and anaplastic thyroid cancer. This review is aimed at collecting the information on the role of compounds, engaged in glycation process, in the pathogenesis of TCs. Moreover, the utility of these compounds in the diagnosis and treatment of TCs is thoroughly discussed. Understanding the mechanism of action of these compounds on TCs pathogenesis and progression may potentially be the grounds for the development of new treatment strategies, aiming at quality-of-life improvements.

Advanced glycation end products (AGEs) and its receptor, RAGE, modulate age-dependent COVID-19 morbidity and mortality. A review and hypothesis

Coronavirus Disease 2019 (COVID-19), caused by the novel virus SARS-CoV-2, is often more severe in older adults. Besides age, other underlying conditions such as obesity, diabetes, high blood pressure, and malignancies, which are also associated with aging, have been considered risk factors for COVID-19 mortality. A rapidly expanding body of evidence has brought up various scenarios for these observations and hyperinflammatory reactions associated with COVID-19 pathogenesis. Advanced glycation end products (AGEs) generated upon glycation of proteins, DNA, or lipids play a crucial role in the pathogenesis of age-related diseases and all of the above-mentioned COVID-19 risk factors. Interestingly, the receptor for AGEs (RAGE) is mainly expressed by type 2 epithelial cells in the alveolar sac, which has a critical role in SARS-CoV-2-associated hyper inflammation and lung injury. Here we discuss our hypothesis that AGEs, through their interaction with RAGE amongst other molecules, modulates COVID-19 pathogenesis and related comorbidities, especially in the elderly.

Exosomes derived from adipose-derived stem cells overexpressing glyoxalase-1 protect endothelial cells and enhance angiogenesis in type 2 diabetic mice with limb ischemia

Background

Diabetic limb ischemia is a clinical syndrome and refractory to therapy. Our previous study demonstrated that adipose-derived stem cells (ADSCs) overexpressing glyoxalase-1 (GLO-1) promoted the regeneration of ischemic lower limbs in diabetic mice, but low survival rate, difficulty in differentiation, and tumorigenicity of the transplanted cells restricted its application. Recent studies have found that exosomes secreted by the ADSCs have the advantages of containing parental beneficial factors and exhibiting non-immunogenic, non-tumorigenic, and strong stable characteristics.

Methods

ADSCs overexpressing GLO-1 (G-ADSCs) were established using lentivirus transfection, and exosomes secreted from ADSCs (G-ADSC-Exos) were isolated and characterized to coculture with human umbilical vein endothelial cells (HUVECs). Proliferation, apoptosis, migration, and tube formation of the HUVECs were detected under high-glucose conditions. The G-ADSC-Exos were injected into ischemic hindlimb muscles of type 2 diabetes mellitus (T2DM) mice, and the laser Doppler perfusion index, Masson’s staining, immunofluorescence, and immunohistochemistry assays were adopted to assess the treatment efficiency. Moreover, the underlying regulatory mechanisms of the G-ADSC-Exos on the proliferation, migration, angiogenesis, and apoptosis of the HUVECs were explored.

Results

The G-ADSC-Exos enhanced the proliferation, migration, tube formation, and anti-apoptosis of the HUVECs in vitro under high-glucose conditions. After in vivo transplantation, the G-ADSC-Exo group showed significantly higher laser Doppler perfusion index, better muscle structural integrity, and higher microvessel’s density than the ADSC-Exo and control groups by Masson’s staining and immunofluorescence assays. The underlying mechanisms by which the G-ADSC-Exos protected endothelial cells both in vitro and in vivo might be via the activation of eNOS/AKT/ERK/P-38 signaling pathways, inhibition of AP-1/ROS/NLRP3/ASC/Caspase-1/IL-1β, as well as the increased secretion of VEGF, IGF-1, and FGF.

Conclusion

Exosomes derived from adipose-derived stem cells overexpressing GLO-1 protected the endothelial cells and promoted the angiogenesis in type 2 diabetic mice with limb ischemia, which will be a promising clinical treatment in diabetic lower limb ischemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02475-7.

Chrysophyllum albidum fruit ethanol extract ameliorates hyperglycaemia and elevated blood pressure in streptozotocin-induced diabetic rats through modulation of oxidative stress, NF-κB and PPAR-γ

Oxidative stress and inflammation arising from hyperglycaemia have been identified as important targets in mitigating hyperglycaemia-induced organ dysfunction in diabetics. Chrysophyllum albidum fruit is commonly consumed as fruit snacks because of its beneficial effects in diabetes management. This study aim to evaluate the protective mechanisms of Chrysophyllum albidum fruit extract (CAFE) in streptozotocin-induced rats involving attenuation of oxidative stress, nuclear factor-kappa B (NF-κB) and peroxisome proliferator-activated receptor-gamma (PPAR-γ). CAFE was investigated for in vitro antioxidant and alpha amylase inhibitory activity. Male Wistar rats were made diabetic by single intraperitoneal injection of streptozotocin (60 mg/kg). The rats were then treated with CAFE (100 and 200 mg/kg) and pioglitazone (10 mg/kg) for two weeks. Fasting blood sugar (FBS), blood pressure parameters, lipid profile, oxidative stress parameters, NF-κB and PPAR-γ were determined. The extract showed antioxidant and alpha amylase inhibitory activities. CAFE significantly reduced STZ-induced hyperglycaemia after 7 and 14 days of treatment. CAFE also reduced STZ-induced elevation of diastolic blood pressure and mean arterial pressure and as well reduced atherogenic index in diabetic rats. It significantly decreased lipid peroxidation but increased the enzymatic and non-enzymatic antioxidant markers in the plasma, liver, kidney and pancreas. The immunohistochemical analysis revealed that CAFE significantly decreased hepatic and renal tissues NF-κB while increasing PPAR-γ gene expressions. The results of this study collectively showed the protective effect of Chrysophyllum albidum fruit extract in streptozotocin-induced diabetic rats via modulation of oxidative stress and NF-κB/ PPAR-γ expressions.

Aortic valvular stenosis: Novel therapeutic strategies

BACKGROUND

Aortic stenosis (AS) prevalence is estimated to reach 4.5 million cases worldwide by the year 2030. AS is a progressive disease without a pharmacological treatment. In the current review, we aimed to investigate novel therapeutic approaches for non-surgical AS treatment, at least in patients with mild-to-moderate AS.

MATERIALS AND METHODS

The most recent and relevant papers concerned with novel molecular pathways that have potential as therapeutic targets in AS were selected from searches of PubMed and Web of Science up to February 2021.

RESULTS

Growing evidence indicates that therapies using proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, simvastatin/ezetimibe combination, cholesteryl ester transfer protein inhibitors or antisense oligonucleotides targeting apolipoprotein(a) reduce the risk of AS progression. It has been shown that enhanced valvular lipid oxidation may drive AS development by leading to the activation of valvular interstitial cells (VICs), the most abundant valvular cells having a major contribution to valve calcification. Since VICs are able to release pro-inflammatory cytokines, clotting factors and proteins involved in calcification, strategies targeting these cell activations seem promising as therapeutic interventions. Recently, non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to inhibit activation of VICs.

CONCLUSION

Several novel molecular pathways of AS development have been identified over the past few years. Therapies using PCSK9 inhibitors, simvastatin/ezetimibe combination, lipoprotein(a)-lowering therapy are highly promising candidates as therapeutics in the prevention of mild AS progression, while preclinical studies show that NOACs may inhibit valvular inflammation and coagulation activation and slower the rate of AS progression.

Pro-inflammatory cytokine profile is present in the serum of Mexican patients with different stages of diabetic retinopathy secondary to type 2 diabetes

Aim

It’s been reported that pro-inflammatory cytokines are elevated in patients with diabetic retinopathy (DR); this may contribute to the pathophysiology of the disease. The aim of this study is to measure the concentration of various inflammatory cytokines from the main CD4+ T helper inflammatory responses in blood serum from Mexican patients with DR in different stages using cytometric bead array (CBA) technology and correlate them with the presence and severity of DR in order to find possible DR biomarkers that serve as diagnostic or therapeutic predictors.

Methods

64 subjects were included in the study, 16 in the control group, 16 in the type 2 diabetes mellitus no DR (NDR) group, 16 in the non-proliferative DR (NPDR) group and 16 in the proliferative DR (PDR) group. Cytokine concentrations of interleukin (IL) 1ß, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, IL‐12, IL‐17A, tumour necrosis factor alpha (TNFα) and interferon-gamma in serum samples were measured using Human Inflammatory and TH1/TH2/TH17 CBA Kit.

Results

IL-6, IL-12, IL-17a and TNFα were significantly higher in the patients with DR compared with the control group. The PDR group showed a slightly lower concentration of serum cytokines IL-6, IL-12 and IL-17a. TNFα showed a higher concentration compared with healthy controls, NDR and NPDR subjects. We also found a positive statistical correlation between the presence and severity of DR with the clinical parameters haemoglobin A1c, body mass index and serum creatinine and the concentration of serum cytokines IL-6 and TNFα.

Conclusion

Our findings suggest that patients with diabetes and DR have a stronger chronic inflammatory profile compared with non-diabetic subjects.