AGE/RAGE produces endothelial dysfunction in coronary arterioles in type 2 diabetic mice

Methylglyoxal induces endothelial cell apoptosis and coronary microvascular dysfunction through regulating AR-cPLA2 signaling

OBJECTIVE

Since diabetic patients with coronary microvascular dysfunction (CMD) exhibit high cardiac mortality and women have higher prevalence of non-obstructive coronary artery disease than men, we tried to expand the limited understanding about the etiology and the sex difference of diabetic CMD.

APPROACH AND RESULTS

Accumulated methylglyoxal (MGO) due to diabetes promotes vascular damage and it was used for mimicking diabetic status. Flow cytometry analysis and isometric tension measurement were performed to evaluate coronary artery endothelial injury. MGO induced apoptosis of coronary endothelial cells, accompanied by downregulation of androgen receptor (AR). Lentivirus-mediated stable expression of AR in coronary endothelial cells increased anti-apoptotic Bcl-2 expression and attenuated MGO-induced cell apoptosis. cPLA2 activation was the downstream of AR downregulation by MGO treatment. Moreover, MGO also activated cPLA2 rapidly to impair endothelium-dependent vasodilation of coronary arteries from mice. Reactive oxygen species (ROS) overproduction was demonstrated to account for MGO-mediated cPLA2 activation and endothelial dysfunction. Importantly, AR blockade increased endothelial ROS production whereas AR activation protected coronary artery endothelial vasodilatory function from the MGO-induced injury. Although galectin-3 upregulation was confirmed by siRNA knockdown in endothelial cells not to participate in MGO-induced endothelial apoptosis, pharmacological inhibitor of galectin-3 further enhanced MGO-triggered ROS generation and coronary artery endothelial impairment.

CONCLUSIONS

Our data proposed the AR downregulation-ROS overproduction-cPLA2 activation pathway as one of the mechanisms underlying diabetic CMD and postulated a possible reason for the sex difference of CMD-related angina. Meanwhile, MGO-induced galectin-3 activation played a compensatory role against coronary endothelial dysfunction.

Lindera obtusiloba Blume Alleviates Non-Alcoholic Fatty Liver Disease Promoted by Nε-(carboxymethyl)lysine

Non-alcoholic fatty liver disease (NAFLD) is a major issue because it is closely associated with metabolic diseases. Advanced glycation end products (AGEs) are implicated as risk factors for steatosis during NAFLD progression. AGEs influence NAFLD progression through a receptor-independent pathway involving AGE cross-link formation and a receptor-dependent pathway that binds to receptors like receptors for advanced glycation end products (RAGE). The objectives of this study are to examine the effect of Lindera obtusiloba Blume (LO) on NAFLD promoted by Nε-(carboxymethyl)lysine (CML), one of the most common dietary AGEs. The anti-glycation effects of LO were evaluated by inhibiting the AGEs formation and AGEs-collagen cross-links breaking. The efficacy of LO against NAFLD promoted by CML was assessed using both in vitro and in vivo models. NAFLD was induced in mice by feeding a high-fat diet and orally administering CML over a period of 12 weeks, and the effects of LO on lipid metabolism and its regulatory mechanisms were investigated. LO showed the effect of inhibited AGEs formation and breakage, and collagen cross-linking. Fed a high-fat diet with administered CML by gavage, LO administration resulted in a reduction in body weight, fat mass, serum triglycerides, total cholesterol, and low-density lipoprotein cholesterol levels. LO reduced hepatic CML accumulation and RAGE expression in mice fed a high-fat diet and orally administered CML. LO alleviated hepatic steatosis accompanied by lipid accumulation and histological damage by suppressing the expression of sterol regulatory element-binding protein 1c, carbohydrate response element binding protein, fatty acid synthase, stearoyl-CoA desaturase1, tumor necrosis factor-α, and interleukin-1β. LO alleviated the MAPK/NF-κB expression by attenuating CML and RAGE expression. Taken together, our results demonstrate that LO alleviates the progression of NAFLD by lowering the levels of AGEs by downregulating CML/RAGE expression.

Accumulation of advanced glycation end products in skin and increased vascular ageing in the general population: the Malmö Offspring Study

OBJECTIVES

Advanced glycation end product (AGE) is an established risk marker for diabetic vascular disease, and associated with the degree of diabetes complications, renal failure, and atherosclerosis in middle-aged and older individuals. The relationship between AGEs and aortic stiffness has not been thoroughly examined in the younger general population. We aimed to evaluate the association between AGEs and aortic stiffness in the general population of young and middle-aged adults.

METHODS

We analysed cross-sectionally 2518 participants from a Swedish population-based cohort, the Malmö Offspring Study (mean age 41.8 ± 14.5 years, 52.2%). Advanced glycation end-products (AGEs) were measured by a well validated, noninvasive method using skin autofluorescence with AGE-Reader. Aortic stiffness was assessed by carotid-femoral pulse wave velocity (PWV) and augmentation index (Aix) was calibrated to a standard heart rate of 75 bpm at the arteria radialis using SphygmoCor. Multivariable linear regression was performed stratified by age to analyse the association between skin AGE and aortic stiffness.

RESULTS

Increased levels of AGEs were significantly associated with higher direct measurements of aortic stiffness (vascular ageing) in younger individuals (PWV β 0.55 m/s, P  < 0.001) after adjustment for traditional cardiometabolic risk factors, however, not in older individuals (PWV β 0.23 m/s, P  = 0.10). Indirect vascular ageing was also significantly associated with higher levels of AGEs in both younger (Aix β 7.78, P  < 0.001) and older individuals (Aix β 3.69, P  < 0.001).

CONCLUSION

Higher levels of skin autofluorescence-AGEs are positively associated with increased vascular ageing in younger adults from the general population, independent of cardiometabolic risk factors.

Comorbidity Genes of Alzheimer's Disease and Type 2 Diabetes Associated with Memory and Cognitive Function

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are comorbidities that result from the sharing of common genes. The molecular background of comorbidities can provide clues for the development of treatment and management strategies. Here, the common genes involved in the development of the two diseases and in memory and cognitive function are reviewed. Network clustering based on protein-protein interaction network identified tightly connected gene clusters that have an impact on memory and cognition among the comorbidity genes of AD and T2DM. Genes with functional implications were intensively reviewed and relevant evidence summarized. Gene information will be useful in the discovery of biomarkers and the identification of tentative therapeutic targets for AD and T2DM.

Methylglyoxal-Derived Nucleoside Adducts Drive Vascular Dysfunction in a RAGE-Dependent Manner

Diabetic kidney disease (DKD) is a leading cause of death in patients with diabetes. An early precursor to DKD is endothelial cell dysfunction (ECD), which often precedes and exacerbates vascular disease progression. We previously discovered that covalent adducts formed on DNA, RNA, and proteins by the reactive metabolic by-product methylglyoxal (MG) predict DKD risk in patients with type 1 diabetes up to 16 years pre-diagnosis. However, the mechanisms by which MG adducts contribute to vascular disease onset and progression remain unclear. Here, we report that the most predominant MG-induced nucleoside adducts, N2-(1-carboxyethyl)-deoxyguanosine (CEdG) and N2-(1-carboxyethyl)-guanosine (CEG), drive endothelial dysfunction. Following CEdG or CEG exposure, primary human umbilical vein endothelial cells (HUVECs) undergo endothelial dysfunction, resulting in enhanced monocyte adhesion, increased reactive oxygen species production, endothelial permeability, impaired endothelial homeostasis, and exhibit a dysfunctional transcriptomic signature. These effects were discovered to be mediated through the receptor for advanced glycation end products (RAGE), as an inhibitor for intracellular RAGE signaling diminished these dysfunctional phenotypes. Therefore, we found that not only are MG adducts biomarkers for DKD, but that they may also have a role as potential drivers of vascular disease onset and progression and a new therapeutic modality.

Advanced glycated end-products inhibit dilation through constitutive endothelial RAGE and Nox1/4 in rat isolated skeletal muscle arteries

OBJECTIVE

This study investigated the actions of advanced glycated end-products (AGE), their receptors (RAGE), and NAD(P)H oxidase (Nox) subtypes 1, 2, and 4 on mechanisms of endothelium-dependent dilation of the rat cremaster muscle artery (CMA).

METHODS

Immunofluorescence studies were used to examine expression of RAGE in rat arteries. ROS accumulation was measured using luminescence and fluorescence assays. Functional studies were performed using pressure myography.

RESULTS

High levels of RAGE expression were shown in the endothelial cells of the CMA, compared with low endothelial expression in middle cerebral and mesenteric arteries and the aorta. Exogenous AGE (in vitro glycated bovine serum albumin) stimulated H2O2 accumulation in CMA, which was prevented by the RAGE antagonist FPS-ZM1, the NAD(P)H oxidase (Nox) inhibitor apocynin and inhibited by the Nox1/4 inhibitor setanaxib, but not the Nox2 inhibitor GSK2795039. In functional studies, AGE inhibited vasodilation of CMA stimulated by acetylcholine, sodium nitroprusside, and the BKCa activator NS1619, but not adenosine-induced dilation. FPS-ZM1, apocynin, and setanaxib prevented the inhibitory effects of AGE on responses to acetylcholine and NS-1619.

CONCLUSION

These observations suggest RAGE are constitutively expressed in the endothelium of the rat CMA and may be activated by AGE to stimulate Nox1/4 and ROS formation with resulting inhibition of NO and BKCa-mediated endothelium-dependent dilation.

High-fat diet causes endothelial dysfunction in the mouse ophthalmic artery

Obesity is a significant health concern that leads to impaired vascular function and subsequent abnormalities in various organs. The impact of obesity on ocular blood vessels, however, remains largely unclear. In this study, we examined the hypothesis that obesity induced by high-fat diet produces vascular endothelial dysfunction in the ophthalmic artery. Mice were subjected to a high-fat diet for 20 weeks, while age-matched controls were maintained on a standard diet. Reactivity of isolated ophthalmic artery segments was assessed in vitro. Reactive oxygen species (ROS) were quantified in cryosections by dihydroethidium (DHE) staining. Redox gene expression was determined in ophthalmic artery explants by real-time PCR. Furthermore, the expression of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), the receptor for advanced glycation end products (RAGE), and of the lectin-like oxidized low-density-lipoprotein receptor-1 (LOX-1) was determined in cryosections using immunofluorescence microscopy. Ophthalmic artery segments from mice on a high-fat diet exhibited impaired vasodilation responses to the endothelium-dependent vasodilator acetylcholine, while endothelium-independent responses to nitroprusside remained preserved. DHE staining intensity in the vascular wall was notably stronger in mice on a high-fat diet. Messenger RNA expression for NOX2 was elevated in the ophthalmic artery of mice subjected to high fat diet. Likewise, immunostainings revealed increased expression of NOX2 and of RAGE, but not of LOX-1. These findings suggest that a high-fat diet triggers endothelial dysfunction by inducing oxidative stress in the ophthalmic artery via involvement of RAGE and NOX2.

Pharmacological modulation of vascular ageing: A review from VascAgeNet

Vascular ageing, characterized by structural and functional changes in blood vessels of which arterial stiffness and endothelial dysfunction are key components, is associated with increased risk of cardiovascular and other age-related diseases. As the global population continues to age, understanding the underlying mechanisms and developing effective therapeutic interventions to mitigate vascular ageing becomes crucial for improving cardiovascular health outcomes. Therefore, this review provides an overview of the current knowledge on pharmacological modulation of vascular ageing, highlighting key strategies and promising therapeutic targets. Several molecular pathways have been identified as central players in vascular ageing, including oxidative stress and inflammation, the renin-angiotensin-aldosterone system, cellular senescence, macroautophagy, extracellular matrix remodelling, calcification, and gasotransmitter-related signalling. Pharmacological and dietary interventions targeting these pathways have shown potential in ameliorating age-related vascular changes. Nevertheless, the development and application of drugs targeting vascular ageing is complicated by various inherent challenges and limitations, such as certain preclinical methodological considerations, interactions with exercise training and sex/gender-related differences, which should be taken into account. Overall, pharmacological modulation of endothelial dysfunction and arterial stiffness as hallmarks of vascular ageing, holds great promise for improving cardiovascular health in the ageing population. Nonetheless, further research is needed to fully elucidate the underlying mechanisms and optimize the efficacy and safety of these interventions for clinical translation.

Mechanism of Artemisia annua L. in the treatment of acute myocardial infarction: network pharmacology, molecular docking and in vivo validation

This study was to evaluate the potential mechanism of action of Artemisia annua L. (A. annua) in the treatment of acute myocardial infarction (AMI) using network pharmacology, molecular docking and in vivo experiments. 22 active chemical compounds and 193 drug targets of A. annua were screened using the Traditional Chinese Medicine System Pharmacological (TCMSP) database. 3876 disease targets were also collected. Then 158 intersection targets between AMI and A. annua were obtained using R 4.2.0 software. String database was used to construct the protein-protein interaction (PPI) network and 6 core targets (MAPK1, TP53, HSP90AA1, RELA, AKT1, and MYC) were screened. Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed using the R package. GO enrichment results were mainly related to cell responses to chemical stress and cell membrane microregions. KEGG pathways were mainly involved in lipids, atherosclerosis and fluid shear stress. In addition, molecular docking between A. annua active compounds and core targets showed high binding activity. As for in vivo validation, A. annua extract showed significant effects on improving post-infarction ventricular function, delaying ventricular remodeling, and reducing myocardial fibrosis and apoptosis. This study has revealed the potential components and molecular mechanisms of A. annua in the treatment of AMI. Our work also showed that A. annua has great effect on reducing myocardial fibrosis and scar area after infarction.

Clinical Relevance of lncRNA and Mitochondrial Targeted Antioxidants as Therapeutic Options in Regulating Oxidative Stress and Mitochondrial Function in Vascular Complications of Diabetes

Metabolic imbalances and persistent hyperglycemia are widely recognized as driving forces for augmented cytosolic and mitochondrial reactive oxygen species (ROS) in diabetes mellitus (DM), fostering the development of vascular complications such as diabetic nephropathy, diabetic cardiomyopathy, diabetic neuropathy, and diabetic retinopathy. Therefore, specific therapeutic approaches capable of modulating oxidative milieu may provide a preventative and/or therapeutic benefit against the development of cardiovascular complications in diabetes patients. Recent studies have demonstrated epigenetic alterations in circulating and tissue-specific long non-coding RNA (lncRNA) signatures in vascular complications of DM regulating mitochondrial function under oxidative stress. Intriguingly, over the past decade mitochondria-targeted antioxidants (MTAs) have emerged as a promising therapeutic option for managing oxidative stress-induced diseases. Here, we review the present status of lncRNA as a diagnostic biomarker and potential regulator of oxidative stress in vascular complications of DM. We also discuss the recent advances in using MTAs in different animal models and clinical trials. We summarize the prospects and challenges for the use of MTAs in treating vascular diseases and their application in translation medicine, which may be beneficial in MTA drug design development, and their application in translational medicine.

The Sodium-Glucose Co-Transporter 2 (SGLT2) Inhibitor Empagliflozin Reverses Hyperglycemia-Induced Monocyte and Endothelial Dysfunction Primarily through Glucose Transport-Independent but Redox-Dependent Mechanisms

PURPOSE

Hyperglycaemia-induced oxidative stress and inflammation contribute to vascular cell dysfunction and subsequent cardiovascular events in T2DM. Selective sodium-glucose co-transporter-2 (SGLT-2) inhibitor empagliflozin significantly improves cardiovascular mortality in T2DM patients (EMPA-REG trial). Since SGLT-2 is known to be expressed on cells other than the kidney cells, we investigated the potential ability of empagliflozin to regulate glucose transport and alleviate hyperglycaemia-induced dysfunction of these cells.

METHODS

Primary human monocytes were isolated from the peripheral blood of T2DM patients and healthy individuals. Primary human umbilical vein endothelial cells (HUVECs) and primary human coronary artery endothelial cells (HCAECs), and fetoplacental endothelial cells (HPECs) were used as the EC model cells. Cells were exposed to hyperglycaemic conditions in vitro in 40 ng/mL or 100 ng/mL empagliflozin. The expression levels of the relevant molecules were analysed by RT-qPCR and confirmed by FACS. Glucose uptake assays were carried out with a fluorescent derivative of glucose, 2-NBDG. Reactive oxygen species (ROS) accumulation was measured using the H₂DFFDA method. Monocyte and endothelial cell chemotaxis were measured using modified Boyden chamber assays.

RESULTS

Both primary human monocytes and endothelial cells express SGLT-2. Hyperglycaemic conditions did not significantly alter the SGLT-2 levels in monocytes and ECs in vitro or in T2DM conditions. Glucose uptake assays carried out in the presence of GLUT inhibitors revealed that SGLT-2 inhibition very mildly, but not significantly, suppressed glucose uptake by monocytes and endothelial cells. However, we detected the significant suppression of hyperglycaemia-induced ROS accumulation in monocytes and ECs when empagliflozin was used to inhibit SGLT-2 function. Hyperglycaemic monocytes and endothelial cells readily exhibited impaired chemotaxis behaviour. The co-treatment with empagliflozin reversed the PlGF-1 resistance phenotype of hyperglycaemic monocytes. Similarly, the blunted VEGF-A responses of hyperglycaemic ECs were also restored by empagliflozin, which could be attributed to the restoration of the VEGFR-2 receptor levels on the EC surface. The induction of oxidative stress completely recapitulated most of the aberrant phenotypes exhibited by hyperglycaemic monocytes and endothelial cells, and a general antioxidant N-acetyl-L-cysteine (NAC) was able to mimic the effects of empagliflozin.

CONCLUSIONS

This study provides data indicating the beneficial role of empagliflozin in reversing hyperglycaemia-induced vascular cell dysfunction. Even though both monocytes and endothelial cells express functional SGLT-2, SGLT-2 is not the primary glucose transporter in these cells. Therefore, it seems likely that empagliflozin does not directly prevent hyperglycaemia-mediated enhanced glucotoxicity in these cells by inhibiting glucose uptake. We identified the reduction of oxidative stress by empagliflozin as a primary reason for the improved function of monocytes and endothelial cells in hyperglycaemic conditions. In conclusion, empagliflozin reverses vascular cell dysfunction independent of glucose transport but could partially contribute to its beneficial cardiovascular effects.

Central role of cardiac fibroblasts in myocardial fibrosis of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM), a main cardiovascular complication of diabetes, can eventually develop into heart failure and affect the prognosis of patients. Myocardial fibrosis is the main factor causing ventricular wall stiffness and heart failure in DCM. Early control of myocardial fibrosis in DCM is of great significance to prevent or postpone the progression of DCM to heart failure. A growing body of evidence suggests that cardiomyocytes, immunocytes, and endothelial cells involve fibrogenic actions, however, cardiac fibroblasts, the main participants in collagen production, are situated in the most central position in cardiac fibrosis. In this review, we systematically elaborate the source and physiological role of myocardial fibroblasts in the context of DCM, and we also discuss the potential action and mechanism of cardiac fibroblasts in promoting fibrosis, so as to provide guidance for formulating strategies for prevention and treatment of cardiac fibrosis in DCM.

Component Characterization, In Vitro Activities and Molecular Mechanism of Cydonia oblonga Mill. against Diabetic

Cydonia Oblonga Mill. is widely distributed in Turkey, Uzbekistan and China and commonly used by the food industry to produce jam, jelly and candies. The aim of this study was to investigate the in vitro antidiabetic activity and anti-diabetic mechanism of Cydonia Oblonga Mill. fruit (COMF). The chemical compositions were further characterized in COMF by UPLC-Q-Orbitrap/MS and 65 components including 22 flavonoids, 16 organic acids, 11 polyphenols, 5 amino acids, 3 pentacyclic triterpenoids and 8 other compounds were identified. The antioxidant activity by DPPH scavenging method and α-glucosidase inhibitory activity were tested. Furthermore, we detected the effects of COMF extract on the proliferation activity of HUVECs, cell viability of HUVECs under H₂O₂-induced oxidative stress, and NO production. Then, molecular docking activity and α-glucosidase inhibitory activity of seven key flavonoid components selected by bioinformatics analysis and literature in the COMF were studied. Among them, quercetin showed potent inhibitory activity, kaempferol, isorhamnetin, luteolin and apigenin demonstrated moderate inhibitory activity, while rutin and epicatechin exhibited poor inhibitory activity. Subsequently, the effects of quercetin, kaempferol, isorhamnetin, leteolin and apigenin on the gene expression levels of AKT1, IL-6 and VEGFA were verified by real-time fluorescence quantification (RT-qPCR). Molecular biology result showed that different active ingredients can significantly recover the levels of AKT1, IL-6 and VEGFA in HUVECs injured by high glucose.

To explore the active constituents of Sedum aizoon L in the treatment of coronary heart disease based on network pharmacology and molecular docking methodology

Background

There is a lack of effective drugs for the treatment of coronary heart disease (CHD). Sedum aizoon L (SL) has multiple effects, and there is no report on CHD in SL at present. The aim of this study is to explore the mechanisms of action of SL in the treatment of CHD based on network pharmacology and molecular docking technology.

Methods

The targets and active ingredients of SL were screened using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, and CHD-related targets were obtained by searching GeneCards and DisGeNet databases. The intersection of LS active ingredient targets and CHD targets was used to construct a "drug-ingredient-disease-target" network using the Cytoscape software. The STRING database was used to construct a protein-protein interaction (PPI) network, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. Key targets and core active ingredients were selected and molecular docking was performed using the AutoDock software.

Results

According to the predicted results, a total of 134 corresponding target genes for LS, 12 active components, 1,704 CHD-related targets, and 52 intersecting targets were obtained. GO function and KEGG pathway analysis showed that the key targets were involved with signal transducer and activator of transcription 3 (STAT3), tumor protein p53 (TP53), and vascular endothelial growth factor A (VEGFA). The molecular docking results showed that the key targets bound to the important active ingredients in a stable conformation. The core active ingredients of LS in the treatment of CHD were determined to be ursolic acid, myricetin, and beta-sitosterol.

Conclusions

SL may act on targets such as STAT3, TP53, and VEGFA through tumor necrosis factor (TNF) signaling pathway, interleukin 17A (IL-17A) signaling pathway, AGE-RAGE signaling pathway in diabetic complications, and other related pathways, thereby playing a role in preventing and treating CHD.

HIV-1 Tat Upregulates the Receptor for Advanced Glycation End Products and Superoxide Dismutase-2 in the Heart of Transgenic Mice

Cardiovascular disorder (CVD) is a common comorbidity in people living with HIV (PLWH). Although the underlying mechanisms are unknown, virotoxic HIV proteins, such as the trans-activator of transcription (Tat), likely contribute to CVD pathogenesis. Tat expression in mouse myocardium has been found to induce cardiac dysfunction and increase markers of endothelial toxicity. However, the role that Tat may play in the development of CVD pathogenesis is unclear. The capacity for Tat to impact cardiac function was assessed using AC16 human cardiomyocyte cells and adult male and female transgenic mice that conditionally expressed Tat [Tat(+)], or did not [Tat(-)]. In AC16 cardiomyocytes, Tat increased intracellular calcium. In Tat(+) mice, Tat expression was detected in both atrial and ventricular heart tissue. Tat(+) mice demonstrated an increased expression of the receptor for advanced glycation end products and superoxide dismutase-2 (SOD-2) in ventricular tissues compared to Tat(-) controls. No changes in SOD-1 or α-smooth muscle actin were observed. Despite Tat-mediated changes at the cellular level, no changes in echocardiographic measures were detected. Tat(+) mice had a greater proportion of ventricular mast cells and collagen; however, doxycycline exposure offset the latter effect. These data suggest that Tat exposure promotes cellular changes that can precede progression to CVD.

Coronary Microvascular Dysfunction in Diabetes Mellitus: Pathogenetic Mechanisms and Potential Therapeutic Options

Diabetic patients are frequently affected by coronary microvascular dysfunction (CMD), a condition consisting of a combination of altered vasomotion and long-term structural change to coronary arterioles leading to impaired regulation of blood flow in response to changing cardiomyocyte oxygen requirements. The pathogenesis of this microvascular complication is complex and not completely known, involving several alterations among which hyperglycemia and insulin resistance play particularly central roles leading to oxidative stress, inflammatory activation and altered barrier function of endothelium. CMD significantly contributes to cardiac events such as angina or infarction without obstructive coronary artery disease, as well as heart failure, especially the phenotype associated with preserved ejection fraction, which greatly impact cardiovascular (CV) prognosis. To date, no treatments specifically target this vascular damage, but recent experimental studies and some clinical investigations have produced data in favor of potential beneficial effects on coronary micro vessels caused by two classes of glucose-lowering drugs: glucagon-like peptide 1 (GLP-1)-based therapy and inhibitors of sodium-glucose cotransporter-2 (SGLT2). The purpose of this review is to describe pathophysiological mechanisms, clinical manifestations of CMD with particular reference to diabetes, and to summarize the protective effects of antidiabetic drugs on the myocardial microvascular compartment.

Receptor for Advanced Glycation End Products (RAGE): A Pivotal Hub in Immune Diseases

As a critical molecule in the onset and sustainment of inflammatory response, the receptor for advanced glycation end products (RAGE) has a variety of ligands, such as advanced glycation end products (AGEs), S100/calcium granule protein, and high-mobility group protein 1 (HMGB1). Recently, an increasing number studies have shown that RAGE ligand binding can initiate the intracellular signal cascade, affect intracellular signal transduction, stimulate the release of cytokines, and play a vital role in the occurrence and development of immune-related diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and Alzheimer’s disease. In addition, other RAGE signaling pathways can play crucial roles in life activities, such as inflammation, apoptosis, autophagy, and endoplasmic reticulum stress. Therefore, the strategy of targeted intervention in the RAGE signaling pathway may have significant therapeutic potential, attracting increasing attention. In this paper, through the systematic induction and analysis of RAGE-related signaling pathways and their regulatory mechanisms in immune-related diseases, we provide theoretical clues for the follow-up targeted intervention of RAGE-mediated diseases.

Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature

Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.

Relationships between advanced glycation end products (AGEs), vasoactive substances, and vascular function

Vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are major cell types that control vascular function, and hence dysfunction of these cells plays a key role in the development and progression of vasculopathies. Abnormal vascular responsiveness to vasoactive substances including vasoconstrictors and vasodilators has been observed in various arteries in diseases including diabetes, hypertension, chronic kidney diseases, and atherosclerosis. Several substances derived from ECs tightly control vascular function, such as endothelium-derived relaxing and contracting factors, and it is known that abnormal vascular signaling of these endothelium-derived substances is often observed in various diseases. Derangement of signaling in VSMCs and altered function influence vascular reactivity to vasoactive substances and tone, which are important determinants of vascular resistance and blood pressure. However, understanding the molecular mechanisms underlying abnormalities of vascular functions in pathological states is difficult because multiple substances interact in the development of these processes. Advanced glycation end products (AGEs), a heterogeneous group of bioactive compounds, are thought to contribute to vascular dysfunction, which in turn cause the development of several diseases including diabetes, hypertension, stroke, and atherosclerosis. A growing body of evidence suggests that AGEs could affect these cells and modulate vascular function. This study is focused on the link between AGEs and functions of ECs and VSMCs, particularly the modulative effects of AGEs on vascular reactivities to vasoactive substances.

Antioxidants in Alzheimer's Disease: Current Therapeutic Significance and Future Prospects

Alzheimer's disease (AD) rate is accelerating with the increasing aging of the world's population. The World Health Organization (WHO) stated AD as a global health priority. According to the WHO report, around 82 million people in 2030 and 152 million in 2050 will develop dementia (AD contributes 60% to 70% of cases), considering the current scenario. AD is the most common neurodegenerative disease, intensifying impairments in cognition, behavior, and memory. Histopathological AD variations include extracellular senile plaques' formation, tangling of intracellular neurofibrils, and synaptic and neuronal loss in the brain. Multiple evidence directly indicates that oxidative stress participates in an early phase of AD before cytopathology. Moreover, oxidative stress is induced by almost all misfolded protein lumps like α-synuclein, amyloid-β, and others. Oxidative stress plays a crucial role in activating and causing various cell signaling pathways that result in lesion formations of toxic substances, which foster the development of the disease. Antioxidants are widely preferred to combat oxidative stress, and those derived from natural sources, which are often incorporated into dietary habits, can play an important role in delaying the onset as well as reducing the progression of AD. However, this approach has not been extensively explored yet. Moreover, there has been growing evidence that a combination of antioxidants in conjugation with a nutrient-rich diet might be more effective in tackling AD pathogenesis. Thus, considering the above-stated fact, this comprehensive review aims to elaborate the basics of AD and antioxidants, including the vitality of antioxidants in AD. Moreover, this review may help researchers to develop effectively and potentially improved antioxidant therapeutic strategies for this disease as it also deals with the clinical trials in the stated field.

Kidney and lung in pathology: mechanisms and clinical implications

There is a close, physiological, relationship between kidney and lung that begin in the fetal age, and is aimed to keep homeostatic balance in the body. From a pathological point of view, the kidneys could be damaged by inflammatory mediators or by immune-mediated factors linked to a primary lung disease or, conversely, it could be the kidney disease that causes lung damage. Non-immunological mechanisms are frequently involved in renal and pulmonary diseases, as observed in chronic conditions. This crosstalk have clinical and therapeutic consequences. This review aims to describe the pulmonary-renal link in physiology and in pathological conditions.

Pathophysiology of Coronary Microvascular Dysfunction

Ischemic heart disease (IHD) is commonly recognized as the consequence of coronary atherosclerosis and obstructive coronary artery disease (CAD). However, a significant number of patients may present angina or myocardial infarction even in the absence of any significant coronary artery stenosis and impairment of the coronary microcirculation has been increasingly implicated as a relevant cause of IHD. The term "coronary microvascular dysfunction" (CMD) encompasses several pathogenic mechanisms resulting in functional and/or structural changes in the coronary microcirculation and determining angina and myocardial ischemia in patients with angina without obstructive CAD ("primary" microvascular angina), as well as in several other conditions, including obstructive CAD, cardiomyopathies, Takotsubo syndrome and heart failure, especially the phenotype with preserved ejection fraction. The pathogenesis of CMD is complex and involves the combination of functional and structural alterations leading to impaired coronary blood flow and resulting in myocardial ischemia. In the absence of therapies specifically targeting CMD, attention has been focused on the role of modifiable risk factors. Here, we provide updated evidence regarding the pathophysiological mechanisms underlying CMD, with a particular focus on the role of cardiovascular risk factors and comorbidities. Moreover, we discuss the specific pathogenic mechanisms of CMD across the different cardiovascular diseases, aiming to pave the way for further research and the development of novel strategies for a precision medicine approach.

A Catecholaldehyde Metabolite of Norepinephrine Induces Myofibroblast Activation and Toxicity via the Receptor for Advanced Glycation Endproducts: Mitigating Role of l-Carnosine

Monoamine oxidase (MAO) is rapidly gaining appreciation for its pathophysiologic role in cardiac injury and failure. Oxidative deamination of norepinephrine by MAO generates H2O2 and the catecholaldehyde 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL), the latter of which is a highly potent and reactive electrophile that has been linked to cardiotoxicity. However, many questions remain as to whether catecholaldehydes regulate basic physiological processes in the myocardium and the pathways involved. Here, we examined the role of MAO-derived oxidative metabolites in mediating the activation of cardiac fibroblasts in response to norepinephrine. In neonatal murine cardiac fibroblasts, norepinephrine increased reactive oxygen species (ROS), accumulation of catechol-modified protein adducts, expression and secretion of collagens I/III, and other markers of profibrotic activation including STAT3 phosphorylation. These effects were attenuated with MAO inhibitors, the aldehyde-scavenging dipeptide l-carnosine, and FPS-ZM1, an antagonist for the receptor for advanced glycation endproducts (RAGE). Interestingly, treatment of cardiac fibroblasts with a low dose (1 μM) of DOPEGAL-modified albumin phenocopied many of the effects of norepinephrine and also induced an increase in RAGE expression. Higher doses (>10 μM) of DOPEGAL-modified albumin were determined to be toxic to cardiac fibroblasts in a RAGE-dependent manner, which was mitigated by l-carnosine. Collectively, these findings suggest that norepinephrine may influence extracellular matrix remodeling via an adrenergic-independent redox pathway in cardiac fibroblasts involving the MAO-mediated generation of ROS, catecholaldehydes, and RAGE. Furthermore, since elevations in the catecholaminergic tone and oxidative stress in heart disease are linked with cardiac fibrosis, this study illustrates novel drug targets that could potentially mitigate this serious disorder.

Mice derived from in vitro αMEM-cultured preimplantation embryos exhibit postprandial hyperglycemia and higher inflammatory gene expression in peripheral leukocytes

We examined whether peripheral leukocytes of mice derived from in vitro αMEM-cultured embryos and exhibiting type 2 diabetes had higher expression of inflammatory-related genes associated with the development of atherosclerosis. Also, we examined the impact of a barley diet on inflammatory gene expression. Adult mice were produced by embryo transfer, after culturing two-cell embryos for 48 h in either α minimal essential media (α-MEM) or potassium simplex optimized medium control media. Mice were fed either a barley or rice diet for 10 weeks. Postprandial blood glucose and mRNA levels of several inflammatory genes, including Tnfa and Nox2, in blood leukocytes were significantly higher in MEM mice fed a rice diet compared with control mice. Barley intake reduced expression of S100a8 and Nox2. In summary, MEM mice exhibited postprandial hyperglycemia and peripheral leukocytes with higher expression of genes related to the development of atherosclerosis, and barley intake reduced some gene expression.

HPLC-MS and Network Pharmacology Analysis to Reveal Quality Markers of Huo-Xue-Jiang-Tang Yin, a Chinese Herbal Medicine for Type 2 Diabetes Mellitus

Huo-Xue-Jiang-Tang Yin (HXJTY) is a Chinese medicine formulation, which has been widely used for the treatment of various lipometabolism- and glycometabolism-related diseases in clinics. Currently, HXJTY is mainly prescribed to treat patients with type 2 diabetes mellitus (T2DM), yet its chemical and pharmacologic profiles remain to be elucidated. Here, the potential bioactive compound and action mechanism were investigated using chemical and network pharmacology analysis. A rapid HPLC-MS was employed to identify and quantify the component of HXJTY. On the basis of the identified chemical markers from HXJTY, a network pharmacology study, including target gene prediction and functional enrichment, was applied to screen out the main quality markers of HXJTY and explore its potential mechanism for the treatment of T2DM. The results showed that a total of 22 components were identified and quantified from HXJTY by HPLC-MS. Furthermore, 12 active components such as astragaloside IV, calycosin-7-O-β-D-glucoside, hydroxysafflor yellow A, and others were proposed as quality markers of HXJTY for treating T2DM based on network pharmacology analysis. In addition, 125 corresponding possible therapeutic target genes of T2DM were obtained. These target genes are mainly related to peptidase activity, hydrolase activity, phosphatase activity, and cofactor binding, suggesting the involvement of PI3K-Akt, MAPK, AGE-RAGE, and Rap1 signaling pathways in HXJTY-treated T2DM. Our results may provide a useful approach to identify potential quality markers and molecular mechanism of HXJTY for treating T2DM.

C-Peptide as a Therapy for Type 1 Diabetes Mellitus

Diabetes mellitus (DM) is a complex metabolic disease affecting one-third of the United States population. It is characterized by hyperglycemia, where the hormone insulin is either not produced sufficiently or where there is a resistance to insulin. Patients with Type 1 DM (T1DM), in which the insulin-producing beta cells are destroyed by autoimmune mechanisms, have a significantly increased risk of developing life-threatening cardiovascular complications, even when exogenous insulin is administered. In fact, due to various factors such as limited blood glucose measurements and timing of insulin administration, only 37% of T1DM adults achieve normoglycemia. Furthermore, T1DM patients do not produce C-peptide, a cleavage product from insulin processing. C-peptide has potential therapeutic effects in vitro and in vivo on many complications of T1DM, such as peripheral neuropathy, atherosclerosis, and inflammation. Thus, delivery of C-peptide in conjunction with insulin through a pump, pancreatic islet transplantation, or genetically engineered Sertoli cells (an immune privileged cell type) may ameliorate many of the cardiovascular and vascular complications afflicting T1DM patients.

Mechanisms and Perspectives of Sodium-Glucose Co-transporter 2 Inhibitors in Heart Failure

Heart failure (HF) is a common complication or late-stage manifestation of various heart diseases. Numerous risk factors and underlying causes may contribute to the occurrence and progression of HF. The pathophysiological mechanisms of HF are very complicated. Despite accumulating advances in treatment for HF during recent decades, it remains an intractable clinical syndrome with poor outcomes, significantly reducing the quality of life and expectancy of patients, and imposing a heavy economic burden on society and families. Although initially classified as antidiabetic agents, sodium-glucose co-transporter 2 (SGLT2) inhibitors have demonstrated reduced the prevalence of hospitalization for HF, cardiovascular death, and all-cause death in several large-scale randomized controlled clinical trials. These beneficial effects of SGLT-2 inhibitors can be attributed to multiple hemodynamic, inflammatory and metabolic mechanisms, not only reducing the serum glucose level. SGLT2 inhibitors have been used increasingly in treatment for patients with HF with reduced ejection fraction due to their surprising performance in improving the prognosis. In addition, their roles and mechanisms in patients with HF with preserved ejection fraction or acute HF have also attracted attention. In this review article, we discuss the possible mechanisms and applications of SGLT2 inhibitors in HF.

RAGE Mediates Cholesterol Efflux Impairment in Macrophages Caused by Human Advanced Glycated Albumin

We addressed the involvement of the receptor for advanced glycation end products (RAGE) in the impairment of the cellular cholesterol efflux elicited by glycated albumin. Albumin was isolated from type 1 (DM1) and type 2 (DM2) diabetes mellitus (HbA1c > 9%) and non-DM subjects (C). Moreover, albumin was glycated in vitro (AGE-albumin). Macrophages from Ager null and wild-type (WT) mice, or THP-1 transfected with siRNA-AGER, were treated with C, DM1, DM2, non-glycated or AGE-albumin. The cholesterol efflux was reduced in WT cells exposed to DM1 or DM2 albumin as compared to C, and the intracellular lipid content was increased. These events were not observed in Ager null cells, in which the cholesterol efflux and lipid staining were, respectively, higher and lower when compared to WT cells. In WT, Ager, Nox4 and Nfkb1, mRNA increased and Scd1 and Abcg1 diminished after treatment with DM1 and DM2 albumin. In Ager null cells treated with DM-albumin, Nox4, Scd1 and Nfkb1 were reduced and Jak2 and Abcg1 increased. In AGER-silenced THP-1, NOX4 and SCD1 mRNA were reduced and JAK2 and ABCG1 were increased even after treatment with AGE or DM-albumin. RAGE mediates the deleterious effects of AGE-albumin in macrophage cholesterol efflux.

RAGE and its ligands: from pathogenesis to therapeutics

Receptor for advanced glycation end products (RAGE) is an immunoglobulin-like receptor present on cell surface. RAGE binds to an array of structurally diverse ligands, acts as a pattern recognition receptor (PRR) and is expressed on cells of different origin performing different functions. RAGE ligation leads to the initiation of a cascade of signaling events and is implicated in diseases, such as inflammation, cancer, diabetes, vascular dysfunctions, retinopathy, and neurodegenerative diseases. Because of the significant involvement of RAGE in the progression of numerous diseases, RAGE signaling has been targeted through use of inhibitors and anti-RAGE antibodies as a treatment strategy and therapy. Here in this review, we have summarized the physical and physiological aspects of RAGE biology in mammalian system and the importance of targeting this molecule in the treatment of various RAGE mediated pathologies. Highlights Receptor for advanced glycation end products (RAGE) is a member of immunoglobulin superfamily of receptors and involved in many pathophysiological conditions. RAGE ligation with its ligands leads to initiation of distinct signaling cascades and activation of numerous transcription factors. Targeting RAGE signaling through inhibitors and anti-RAGE antibodies can be promising treatment strategy.

Role of peroxisome proliferators-activated receptor-gamma in advanced glycation end product-mediated functional loss of voltage-gated potassium channel in rat coronary arteries

Background

High blood glucose impairs voltage-gated K⁺ (Kv) channel-mediated vasodilation in rat coronary artery smooth muscle cells (CSMCs) via oxidative stress. Advanced glycation end product (AGE) and receptor for AGE (RAGE) axis has been found to impair coronary dilation by reducing Kv channel activity in diabetic rat small coronary arteries (RSCAs). However, its underlying mechanism remain unclear. Here, we used isolated arteries and primary CSMCs to investigate the effect of AGE incubation on Kv channel-mediated coronary dilation and the possible involvement of peroxisome proliferators-activated receptor (PPAR) -γ pathway.

Methods

The RSCAs and primary CSMCs were isolated, cultured, and treated with bovine serum albumin (BSA), AGE-BSA, alagrebrium (ALA, AGE cross-linking breaker), pioglitazone (PIO, PPAR-γ activator) and/or GW9662 (PPAR-γ inhibitor). The groups were accordingly divided as control, BSA, AGE, AGE + ALA, AGE + PIO, or AGE + PIO + GW9662. Kv channel-mediated dilation was analyzed using wire myograph. Histology and immunohistochemistry of RSCAs were performed. Western blot was used to detect the protein expression of RAGE, major Kv channel subunits expressed in CSMCs (Kv1.2 and Kv1.5), PPAR-γ, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-2 (NOX-2).

Results

AGE markedly reduced Forskolin-induced Kv channel-mediated dilation of RSCAs by engaging with RAGE, and ALA or PIO significantly reversed the functional loss of Kv channel. In both RSCAs and CSMCs, AGE reduced Kv1.2/1.5 expression, increased RAGE and NOX-2 expression, and inhibited PPAR-γ expression, while ALA or PIO treatment partially reversed the inhibiting effects of AGE on Kv1.2/1.5 expression, accompanied by the downregulation of RAGE and decreased oxidative stress. Meanwhile, silencing of RAGE with siRNA remarkably alleviated the AGE-induced downregulation of Kv1.2/1.5 expression in CSMCs.

Conclusion

AGE reduces the Kv channel expression in CSMCs and further impairs the Kv channel-mediated dilation in RSCAs. The AGE/RAGE axis may enhance oxidative stress by inhibiting the downstream PPAR-γ pathway, thus playing a critical role in the dysfunction of Kv channels.

Endothelial Dysfunction and Passive Changes in the Aorta and Coronary Arteries of Diabetic db/db Mice

Endothelial cell dysfunction and vessel stiffening are associated with a worsened prognosis in diabetic patients with cardiovascular diseases. The present study hypothesized that sex impacts endothelial dysfunction and structural changes in arteries from diabetic mice. In diabetic (db/db) and normoglycaemic (db/db+) mice, the mechanical properties were investigated in pressurized isolated left anterior descending coronary arteries and aorta segments that were subjected to tensile testing. Functional studies were performed on wire-mounted vascular segments. The male and female db/db mice were hyperglycaemic and had markedly increased body weight. In isolated aorta segments without the contribution of smooth muscle cells, load to rupture, viscoelasticity, and collagen content were decreased suggesting larger distensibility of the arterial wall in both male and female db/db mice. In male db/db aorta segments with smooth muscle cell contribution, lumen diameter was smaller and the passive stretch-tension curve was leftward-shifted, while they were unaltered in female db/db aorta segments versus control db/db+ mice. In contrast to female db/db mice, coronary arteries from male db/db mice had altered stress-strain relationships and increased distensibility. Transthoracic echocardiography revealed a dilated left ventricle with unaltered cardiac output, while aortic flow velocity was decreased in male db/db mice. Impairment of acetylcholine relaxation was aggravated in aorta from female db/db compared to control and male db/db mice, while impairment of sodium nitroprusside relaxations was only observed in aorta from male db/db mice. The remodeling in the coronary arteries and aorta suggests an adaptation of the arterial wall to the reduced flow velocity with sex-specific differences in the passive properties of aorta and coronary arteries. The findings of less distensible arteries and more pronounced endothelial dysfunction in female compared to male diabetic mice may have implications for the observed higher incidence of macrovascular complications in diabetic women.

How do Uremic Toxins Affect the Endothelium?

Uremic toxins can induce endothelial dysfunction in patients with chronic kidney disease (CKD). Indeed, the structure of the endothelial monolayer is damaged in CKD, and studies have shown that the uremic toxins contribute to the loss of cell–cell junctions, increasing permeability. Membrane proteins, such as transporters and receptors, can mediate the interaction between uremic toxins and endothelial cells. In these cells, uremic toxins induce oxidative stress and activation of signaling pathways, including the aryl hydrocarbon receptor (AhR), nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) pathways. The activation of these pathways leads to overexpression of proinflammatory (e.g., monocyte chemoattractant protein-1, E-selectin) and prothrombotic (e.g., tissue factor) proteins. Uremic toxins also induce the formation of endothelial microparticles (EMPs), which can lead to the activation and dysfunction of other cells, and modulate the expression of microRNAs that have an important role in the regulation of cellular processes. The resulting endothelial dysfunction contributes to the pathogenesis of cardiovascular diseases, such as atherosclerosis and thrombotic events. Therefore, uremic toxins as well as the pathways they modulated may be potential targets for therapies in order to improve treatment for patients with CKD.

Can advanced glycation end-products and their receptors be affected by weight loss? A systematic review

Advanced glycation end products (AGEs) have been implicated in the pathogenesis of most chronic diseases. Therefore, identification of treatments that can attenuate the effects of these compounds and prevent cardiometabolic complications is of extreme public health interest. Recently, body weight management interventions showed positive results on reducing serum AGE concentrations. Moreover, the soluble receptor for advanced glycation end products (sRAGE) is considered to be a novel biomarker to identify patients with obesity most likely to benefit from weight management interventions. This systematic review aimed to critically analyze papers evaluating the effects of weight loss on serum AGEs and its receptors in adults with excess body weight. MEDLINE, Cochrane, Scopus, and Lilacs databases were searched. Three studies evaluating the response of AGEs to energy-restricted diets and six assessing sRAGE as the primary outcome were included. Energy-restricted diets and bariatric surgery reduced serum AGE concentrations, but effects on endogenous secretory RAGE (esRAGE) and sRAGE concentrations are conflicting. These results may be associated with mechanisms related to changes in dietary intake and limiting endogenous AGE formation. Therefore, the role of energy-restricted diets and bariatric surgery on lowering serum AGE concentrations, as well as its effects on AGEs receptors, deserves further investigation.

Extracellular matrix components isolated from diabetic mice alter cardiac fibroblast function through the AGE/RAGE signaling cascade

Individuals suffering from diabetes have an increased risk of developing cardiovascular complications such as heart failure. Heart failure can be a result of the stiffening of the left ventricle, which occurs when cardiac fibroblasts become "active" and begin to remodel the extracellular matrix (ECM). Fibroblast "activation" can be triggered by the AGE/RAGE signaling cascade. Advanced Glycation End products (AGEs) are produced and accumulate in the ECM over time in a healthy individual, but under hyperglycemic conditions, this process is accelerated. In this study, we investigated how the presence of AGEs in either non-diabetic or diabetic ECM affected fibroblast-mediated matrix remodeling. In order to address this question, diabetic and non-diabetic fibroblasts were embedded in 3D matrices composed of collagen isolated from either non-diabetic or diabetic mice. Fibroblast function was assessed using gel contraction, migration, and protein expression. Non-diabetic fibroblasts displayed similar gel contraction to diabetic cells when embedded in diabetic collagen. Thus, suggesting the diabetic ECM can alter fibroblast function from an "inactive" to "active" state. Addition of AGEs increase the AGE/RAGE cascade leading to increased gel contraction, whereas inhibiting the cascade resulted in little or no gel contraction. These results indicated 1) the ECM from diabetic and non-diabetic mice differ from one another, 2) diabetic ECM can impact fibroblast function and shift them toward an "active" state, and 3) that fibroblasts can modify the ECM through activation of the AGE/RAGE signaling cascade. These results suggested the importance of understanding the impact diabetes has on the ECM and fibroblast function.

The Impact of Diabetic Conditions and AGE/RAGE Signaling on Cardiac Fibroblast Migration

Diabetic individuals have an increased risk for developing cardiovascular disease due to stiffening of the left ventricle (LV), which is thought to occur, in part, by increased AGE/RAGE signaling inducing fibroblast differentiation. Advanced glycated end-products (AGEs) accumulate within the body over time, and under hyperglycemic conditions, the formation and accumulation of AGEs is accelerated. AGEs exert their effect by binding to their receptor (RAGE) and can induce myofibroblast differentiation, leading to increased cell migration. Previous studies have focused on fibroblast migration during wound healing, in which diabetics have impaired fibroblast migration compared to healthy individuals. However, the impact of diabetic conditions as well as AGE/RAGE signaling has not been extensively studied in cardiac fibroblasts. Therefore, the goal of this study was to determine how the AGE/RAGE signaling pathway impacts cell migration in non-diabetic and diabetic cardiac fibroblasts. Cardiac fibroblasts were isolated from non-diabetic and diabetic mice with and without functional RAGE and used to perform a migration assay. Cardiac fibroblasts were plated on plastic, non-diabetic, or diabetic collagen, and when confluency was reached, a line of migration was generated by scratching the plate and followed by treatment with pharmacological agents that modify AGE/RAGE signaling. Modification of the AGE/RAGE signaling cascade was done with ERK1/2 and PKC-ζ inhibitors as well as treatment with exogenous AGEs. Diabetic fibroblasts displayed an increase in migration compared to non-diabetic fibroblasts whereas inhibiting the AGE/RAGE signaling pathway resulted in a significant increase in migration. The results indicate that the AGE/RAGE signaling cascade causes a decrease in cardiac fibroblast migration and altering the pathway will produce alterations in cardiac fibroblast migration.

Diabetes affects endothelial cell function and alters fibrin clot formation in a microvascular flow model: A pilot study

Diabetes is a proinflammatory and prothrombotic condition that increases the risk of vascular complications. The aim of this study was to develop a diabetic microvascular flow model that allows to study the complex interactions between endothelial cells, blood cells and plasma proteins and their effects on clot formation. Primary human cardiac microvascular endothelial cells from donors without diabetes or donors with diabetes (type 1 or type 2) were grown in a microfluidic chip, perfused with non-diabetic or diabetic whole blood, and clot formation was assessed by measuring fibrin deposition in real time by confocal microscopy. Clot formation in non-diabetic whole blood was significantly increased in the presence of endothelial cells from donors with type 2 diabetes compared with cells from donors without diabetes. There was no significant difference in clot formation between non-diabetic and diabetic whole blood. We present for the first time a diabetic microvascular flow model as a new tool to study clot formation as a result of the complex interactions between endothelial cells, blood cells and plasma proteins in a diabetes setting. We show that endothelial cells affect clot formation in whole blood, attributing an important role to the endothelium in the development of atherothrombotic complications.

The pivotal role of nuclear factor erythroid 2-related factor 2 in diabetes-induced endothelial dysfunction

Endothelial dysfunction (ED) is a key event in the onset and progression of vascular complications associated with diabetes. Regulation of endothelial function and the underlying signaling mechanisms in the progression of diabetes-induced vascular complications have been well established. Recent studies indicate that increased oxidative stress is an important determinant of endothelial injury and patients with hypertension display ED mediated by impaired Nitric Oxide (NO) availability. Further, oxidative stress is known to be associated with inflammation and ED in vascular remodeling and diabetes-associated hypertension. Numerous strategies have been developed to improve the function of endothelial cells and increasing number of evidences highlight the indispensable role of antioxidants in modulation of endothelium-dependent vasodilation responses. Nuclear factor Erythroid 2-related factor 2 (Nrf2), is the principal transcriptional regulator, that is central in mediating oxidative stress signal response. Having unequivocally established the relationship between type 2 diabetes mellitus (T2DM) and oxidative stress, the pivotal role of Nrf2/Keap1/ARE network, has taken the center stage as target for developing therapies towards maintaining the cellular redox environment. Several activators of Nrf2 are known to combat diabetes-induced ED and few are currently in clinical trials. Focusing on their therapeutic value in diabetes-induced ED, this review highlights some natural and synthetic molecules that are involved in the modulation of the Nrf2/Keap1/ARE network and its underlying molecular mechanisms in the regulation of ED. Further emphasis is also laid on the therapeutic benefits of directly up-regulating Nrf2-mediated antioxidant defences in regulating endothelial redox homeostasis for countering diabetes-induced ED.

A Network Pharmacology-Based Strategy For Predicting Active Ingredients And Potential Targets Of LiuWei DiHuang Pill In Treating Type 2 Diabetes Mellitus

Background

Traditional Chinese medicine (TCM) formulations have proven to be advantageous in clinical treatment and prevention of disease. LiuWei DiHuang Pill (LWDH Pill) is a TCM that was employed to treat type 2 diabetes mellitus (T2DM). However, a holistic network pharmacology approach to understanding the active ingredients and the therapeutic mechanisms underlying T2DM has not been pursued.

Methods

A network pharmacology approach including drug-likeness evaluation, oral bioavailability prediction, virtual docking, and network analysis has been used to predict the active ingredients and potential targets of LWDH Pill in the treatment of type 2 diabetes.

Results

The comprehensive network pharmacology approach was successfully to identify 45 active ingredients in LWDH Pill. 45 active ingredients hit by 163 potential targets related to T2DM. Ten of the more highly predictive components (such as :quercetin, Kaempferol, Stigmasterol, beta-sitosterol, Kadsurenone, Diosgenin, hancinone C, Hederagenin, Garcinone B, Isofucosterol) are involved in anti-inflammatory, anti-oxidative stress, and the reduction of beta cell damage. LWDH Pill may play a role in the treatment of T2DM and its complications (atherosclerosis and nephropathy) through the AGE-RAGE signaling pathway, TNF signaling pathway, and NF-kappa B signaling pathway.

Conclusion

Based on a systematic network pharmacology approach, our works successfully predict the active ingredients and potential targets of LWDH Pill for application to T2DM and helps to illustrate mechanism of action on a comprehensive level. This study provides identify key genes and pathway associated with the prognosis and pathogenesis of T2DM from new insights, which also demonstrates a feasible method for the research of chemical basis and pharmacology in LWDH Pill.

AGEs impair Kv channel-mediated vasodilation of coronary arteries by activating the NF-κB signaling pathway in ZDF rats

Excessive formation of advanced glycation end products (AGEs) impairs voltage-gated potassium (Kv) channels in rat coronary artery smooth muscle cells (CSMCs), resulting in weakened Kv-mediated coronary vasodilation. We hypothesized that induction of the nuclear factor-κB (NF-κB) signaling pathway by AGEs plays a significant role in the regulation of Kv channel-mediated vasodilation in Zucker diabetic fatty (ZDF) rats. Assays of mRNA transcripts, protein expression, and intracellular localization as well as patch-clamp experiments in cultured CSMCs revealed that AGEs significantly induced activation of the NF-κB signaling pathway, reduced Kv1.2/1.5 expression, and inhibited Kv currents. In addition, silencing of the receptor for AGEs (RAGE) or p65 with siRNA and treatment with alagrebrium (ALA) or pyrrolidine dithiocarbamate (PDTC) alleviated the AGE-induced impairment of Kv channels in CSMCs. Compared with Zucker lean (ZL) rats, the amount of AGEs, RAGE protein expression, and NF-κB activity in coronary arteries were higher in ZDF rats; whereas Kv1.2/1.5 expression was significantly lower in ZDF rats. Reduced Kv1.2/1.5 expression in coronary arteries and impaired Kv-mediated coronary relaxation tested by wire myography in ZDF rats were markedly improved by treatment with aminoguanidine (AG), ALA, or PDTC. These effects were accompanied by diminished NF-κB activity, inflammation, and oxidative stress. Taken together, these results indicate that an increased interaction between AGEs and RAGE in diabetic rats leads to impaired Kv channel-mediated coronary vasodilation. Moreover, activation of the NF-κB signaling pathway and a subsequent increase of inflammation and oxidative stress may play an important role in AGE-induced impairment of coronary vasodilation in diabetes.

Placental growth factor levels in quadriceps muscle are reduced by a Western diet in association with advanced glycation end products

In peripheral artery disease (PAD), atherosclerotic occlusion chronically impairs limb blood flow. Arteriogenesis (collateral artery remodeling) is a vital adaptive response to PAD that protects tissue from ischemia. People with type II diabetes have a high risk of developing PAD and would benefit from arteriogenesis. However, arteriogenesis is suppressed in people with diabetes by a multifaceted mechanism which remains incompletely defined. Upregulation of placental growth factor (PLGF) is a key early step in arteriogenesis. Therefore, we hypothesized that metabolic dysfunction would impair PLGF expression in skeletal muscle. We tested this hypothesis in C57BL/6J and ApoE^-/- mice of both sexes fed a Western diet (WD) for 24 wk. We first assessed baseline levels of PLGF, vascular endothelial growth factor (VEGF-A), and VEGF receptor 1 (VEGFR1) protein in hindlimb skeletal muscle. Only PLGF was consistently decreased by the WD. We next investigated the effect of 24 wk of the WD on the response of PLGF, VEGF-A, VEGFR1, and monocyte chemoattractant protein-1 (MCP-1) to the physiological stimulus of vascular occlusion. Hindlimb ischemia was induced in mice by gradual femoral artery occlusion using an ameroid constrictor. Growth factor levels were measured 3-28 days postsurgery. In C57BL/6J mice, the WD decreased and delayed upregulation of PLGF and abolished upregulation of VEGF-A and VEGFR1 but had no effect on MCP-1. In ApoE^-/- mice fed either diet, all factors tested failed to respond to occlusion. Metabolic phenotyping of mice and in vitro studies suggest that an advanced glycation end product/TNFα-mediated mechanism could contribute to the effects observed in vivo.NEW & NOTEWORTHY In this study, we tested the effect of a Western diet on expression of the arteriogenic growth factor placental growth factor (PLGF) in mouse skeletal muscle. We provide the first demonstration that a Western diet interferes with both baseline expression and hindlimb ischemia-induced upregulation of PLGF. We further identify a potential role for advanced glycation end product/TNFα signaling as a negative regulator of PLGF. These studies provide insight into one possible mechanism by which type II diabetes may limit collateral growth.

Receptor for Advanced Glycation End Products Antagonism Blunts Kidney Damage in Transgenic Townes Sickle Mice

A large proportion of adult patients with sickle cell disease (SCD) develops kidney disease and is at a high risk of mortality. The contribution of advanced glycation end products and their receptor (AGE/RAGE) axis has been established in the pathogenesis of multiple kidney diseases. The aim of the present study was to determine the implication of RAGE in the development of SCD-related kidney complications in a mouse model of SCD, as this has never been investigated. 8-week-old AA (normal) and SS (homozygous SCD) Townes mice were treated with a specific RAGE antagonist (RAP) or vehicle (NaCl). After 3 weeks of treatment, red blood cell count, hematocrit, and hemoglobin levels were significantly higher in RAP-treated SS mice. Reticulocyte count and sickle cell count were reduced in RAP-SS compared to their NaCl-treated littermates. The lower NADPH oxidase activity in the kidney of RAP-treated mice compared to NaCl-treated mice suggests limited ROS production. RAP-treated SS mice had decreased NF-κB protein expression and activation as well as reduced TNF-α mRNA expression in the kidney. Glomerular area, interstitial fibrosis, tubular iron deposits, and KIM-1 protein expression were significantly reduced after RAP treatment. In conclusion, this study provides evidence supporting the pathogenic role of RAGE in kidney injuries in sickle cell mice.

Construction and analysis of a lncRNA‑miRNA‑mRNA network based on competitive endogenous RNA reveals functional lncRNAs in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a major cause of mortality in patients with diabetes, particularly those with type 2 diabetes. Long non‑coding RNAs (lncRNAs), including terminal differentiation‑induced lncRNA (TINCR), myocardial infarction‑associated transcript (MIAT) and H19, serve a key role in the regulation of DCM. MicroRNAs (miRNAs/miRs) can inhibit the expression of mRNA at the post‑transcriptional level, whereas lncRNAs can mask the inhibitory effects of miRNAs on mRNA. Together, miRNAs and lncRNAs form a competitive endogenous non‑coding RNA (ceRNA) network that regulates the occurrence and development of various diseases. However, the regulatory role of lncRNAs in DCM is unclear. In this study, a background network containing mRNAs, miRNAs and lncRNAs was constructed using starBase and a regulatory network of DCM was screened using Cytoscape. A functional lncRNA, X‑inactive specific transcript (XIST), was identified in the disease network and the main miRNAs (miR‑424‑5p and miR‑497‑5p) that are regulated by XIST were further screened to obtain the ceRNA regulatory network of DCM. In conclusion, the results of this study revealed that lncRNAs may serve an important role in DCM and provided novel insights into the pathogenesis of DCM.

The Receptor for Advanced Glycation End Products (RAGE) and DIAPH1: Implications for vascular and neuroinflammatory dysfunction in disorders of the central nervous system

The Receptor for Advanced Glycation End Products (RAGE) is expressed by multiple cell types in the brain and spinal cord that are linked to the pathogenesis of neurovascular and neurodegenerative disorders, including neurons, glia (microglia and astrocytes) and vascular cells (endothelial cells, smooth muscle cells and pericytes). Mounting structural and functional evidence implicates the interaction of the RAGE cytoplasmic domain with the formin, Diaphanous1 (DIAPH1), as the key cytoplasmic hub for RAGE ligand-mediated activation of cellular signaling. In aging and diabetes, the ligands of the receptor abound, both in the central nervous system (CNS) and in the periphery. Such accumulation of RAGE ligands triggers multiple downstream events, including upregulation of RAGE itself. Once set in motion, cell intrinsic and cell-cell communication mechanisms, at least in part via RAGE, trigger dysfunction in the CNS. A key outcome of endothelial dysfunction is reduction in cerebral blood flow and increased permeability of the blood brain barrier, conditions that facilitate entry of activated leukocytes into the CNS, thereby amplifying primary nodes of CNS cellular stress. This contribution details a review of the ligands of RAGE, the mechanisms and consequences of RAGE signal transduction, and cites multiple examples of published work in which RAGE contributes to the pathogenesis of neurovascular perturbation. Insights into potential therapeutic modalities targeting the RAGE signal transduction axis for disorders of CNS vascular dysfunction and neurodegeneration are also discussed.

Prevention of memory impairment induced by post-traumatic stress disorder by cerebrolysin

Post-traumatic stress disorder (PTSD) may occur after exposure to stressful, fearful or troubling events. Until now, there is no curable medication for this disorder. Cerebrolysin is a neuropeptide, which has an important role in the treatment of vascular dementia. In this study, the probable protective effect of cerebrolysin on PTSD-induced memory impairment was investigated. To induce PTSD, the single prolonged stress (SPS) model was used. Rats were allocated into four groups: control (vehicle-treated), CBL (administrated cerebrolysin 2.5 ml/kg by intraperitoneal route for 4 weeks), SPS (as a model of PTSD and administered vehicle), and CBL-SPS (exposed to SPS and administered cerebrolysin for 4 weeks). Learning and memory were assessed using the radial arm water maze (RAWM). Results showed that SPS impaired both short- and long- term memories; and chronic cerebrolysin administration prevented such effect. Cerebrolysin also prevented decreases in hippocampal GSH levels and GSH/GSSG ratios, and increased GSSG and TBARs, levels induced by PTSD. In conclusion, a protective effect of cerebrolysin administration against SPS model of PTSD induced short- and long- term memory impairment was characterized. This protection could be accomplished, at least partly, by prevention of PTSD induced increase in oxidative stress in the hippocampus via the use of cerebrolysin.

Oxidant/Antioxidant Imbalance in Alzheimer's Disease: Therapeutic and Diagnostic Prospects

Alzheimer's disease (AD) is the most common cause of dementia and a great socioeconomic burden in the aging society. Compelling evidence demonstrates that molecular change characteristics for AD, such as oxidative stress and amyloid β (Aβ) oligomerization, precede by decades the onset of clinical dementia and that the disease represents a biological and clinical continuum of stages, from asymptomatic to severely impaired. Nevertheless, the sequence of the early molecular alterations and the interplay between them are incompletely understood. This review presents current knowledge about the oxidative stress-induced impairments and compromised oxidative stress defense mechanisms in AD brain and the cross-talk between various pathophysiological insults, with the focus on excessive reactive oxygen species (ROS) generation and Aβ overproduction at the early stages of the disease. Prospects for AD therapies targeting oxidant/antioxidant imbalance are being discussed, as well as for the development of novel oxidative stress-related, blood-based biomarkers for early, noninvasive AD diagnostics.

COPD as an endothelial disorder: endothelial injury linking lesions in the lungs and other organs? (2017 Grover Conference Series)

Chronic obstructive pulmonary disease (COPD) is characterized by chronic expiratory airflow obstruction that is not fully reversible. COPD patients develop varying degrees of emphysema, small and large airway disease, and various co-morbidities. It has not been clear whether these co-morbidities share common underlying pathogenic processes with the pulmonary lesions. Early research into the pathogenesis of COPD focused on the contributions of injury to the extracellular matrix and pulmonary epithelial cells. More recently, cigarette smoke-induced endothelial dysfunction/injury have been linked to the pulmonary lesions in COPD (especially emphysema) and systemic co-morbidities including atherosclerosis, pulmonary hypertension, and chronic renal injury. Herein, we review the evidence linking endothelial injury to COPD, and the pathways underlying endothelial injury and the "vascular COPD phenotype" including: (1) direct toxic effects of cigarette smoke on endothelial cells; (2) generation of auto-antibodies directed against endothelial cells; (3) vascular inflammation; (4) increased oxidative stress levels in vessels inducing increases in lipid peroxidation and increased activation of the receptor for advanced glycation end-products (RAGE); (5) reduced activation of the anti-oxidant pathways in endothelial cells; (6) increased endothelial cell release of mediators with vasoconstrictor, pro-inflammatory, and remodeling activities (endothelin-1) and reduced endothelial cell expression of mediators that promote vasodilation and homeostasis of endothelial cells (nitric oxide synthase and prostacyclin); and (7) increased endoplasmic reticular stress and the unfolded protein response in endothelial cells. We also review the literature on studies of drugs that inhibit RAGE signaling in other diseases (angiotensin-converting enzyme inhibitors and angiotensin receptor blockers), or vasodilators developed for idiopathic pulmonary arterial hypertension that have been tested on cell culture systems, animal models of COPD, and/or smokers and COPD patients.

Extracellular Matrix and Ageing

The extracellular matrix (ECM) provides the environment for many cells types within the body and, in addition to the well recognised role as a structural support, influences many important cell process within the body. As a result, age-related changes to the proteins of the ECM have far reaching consequences with the potential to disrupt many different aspects of homeostasis and healthy function. The proteins collagen and elastin are the most abundant in the ECM and their ability to function as a structural support and provide mechanical stability results from the formation of supra-molecular structures. Collagen and elastin have a long half-life, as required by their structural role, which leaves them vulnerable to a range of post-translational modifications. In this chapter the role of the ECM is discussed and the component proteins introduced. Major age-related modifications including glycation, carbamylation and fragmentation and the impact these have on ECM function are reviewed.