Homocysteine causes vascular endothelial dysfunction by disrupting endoplasmic reticulum redox homeostasis

Development and validation of a predictive model for end-stage renal disease in systemic lupus erythematosus patients

Systemic lupus erythematosus (SLE) affects many populations. This study aims to develop a predictive model and create a nomogram for assessing the risk of end-stage renal disease (ESRD) in patients diagnosed with SLE. Data from electronic health records of SLE patients treated at the Affiliated Hospital of North Sichuan Medical College between 2013 and 2023 were collected. The dataset underwent thorough cleaning and variable assignment procedures. Subsequently, variables were selected using one-way logistic regression and lasso logistic regression methods, followed by multifactorial logistic regression to construct nomograms. The model's performance was assessed using calibration, receiver operating characteristic (ROC), and decision curve analysis (DCA) curves. Statistical significance was set at P < 0.05. The predictive variables for ESRD development in SLE patients included anti-GP210 antibody presence, urinary occult blood, proteinuria, white blood cell count, complement 4 levels, uric acid, creatinine, total protein, globulin, glomerular filtration rate, pH, specific gravity, very low-density lipoprotein, homocysteine, apolipoprotein B, and absolute counts of cytotoxic T cells. The nomogram exhibited a broad predictive range. The ROC area under the curve (AUC) was 0.886 (0.858-0.913) for the training set and 0.840 (0.783-0.897) for the testing set, indicating good model performance. The model demonstrated both applicability and significant clinical benefits. The developed model presents strong predictive capabilities and considerable clinical utility in estimating the risk of ESRD in patients with SLE.

The different roles of homocysteine metabolism in hypertension among normal-weight and obese patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with hypertension. However, the differential mechanisms underlying OSA-related hypertension between normal-weight vs. obese patients is limited.

METHODS

We studied 92 patients with OSA and 24 patients with continuous positive airway pressure (CPAP) treatment. Blood pressure (BP) was measured twice during awake and continuously monitored during sleep. Obesity was defined as body mass index ≥28 kg/m2. Serum metabolite levels were assessed by metabolomics.

RESULTS

Among 59 normal-weight and 33 obese patients, 651 and 167 metabolites showed differences between hypertension and normotension or were associated with systolic and diastolic BP (SBP, DBP) after controlling confounders. These metabolites involved 16 and 12 Kyoto Encyclopedia of Genes and Genomes enrichment pathways in normal-weight and obese patients respectively, whereas 6 pathways overlapped. Among these 6 overlapping pathways, 4 were related to homocysteine metabolism and 2 were non-specific pathways. In homocysteine metabolism pathway, 13 metabolites were identified. Interestingly, the change trends of 7 metabolites associated with SBP (all interaction-p≤0.083) and 8 metabolites associated with DBP (all interaction-p≤0.033) were opposite between normal-weight and obese patients. Specifically, increased BP was associated with down-regulated folate-dependent remethylation and accelerated transsulfuration in normal-weight patients, whereas associated with enhanced betaine-dependent remethylation and reduced transsulfuration in obese patients. Similar findings were observed in ambulatory BP during sleep. After CPAP treatment, baseline low homocysteine levels predicted greater decrease in DBP among normal-weight but not obese patients.

CONCLUSIONS

Mechanisms in OSA-related hypertension differ between normal-weight and obese patients, which are explained by different changes in homocysteine metabolism.

Repeated platelet-rich plasma injections improve erectile dysfunction in a rat model of hyperhomocysteinemia

ABSTRACT

Platelet-rich plasma (PRP) shows promise as a regenerative modality for mild-to-moderate erectile dysfunction (ED). However, its efficacy in treating severe ED remains unknown. Blood samples from 8-week-old male rats were used to prepare PRP through a two-step centrifugation procedure, followed by chitosan activation and freeze‒thaw cycle. A hyperhomocysteinemia (HHcy)-related ED model was established using a methionine-enriched diet, and an apomorphine (APO) test was conducted during the 4 th week. APO-negative rats were divided into two groups and were injected with PRP or saline every 2 weeks. Erectile function and histological analyses of the corpus cavernosum were performed during the 16 th week. The results revealed that erectile function was significantly impaired in rats with HHcy-related ED compared to that in age-matched rats but was improved by repeated PRP injections. Immunofluorescence staining revealed a reduction in reactive oxygen species and additional benefits on the recovery of structures within the corpus cavernosum in rats that received PRP treatment compared to those in the saline-injected control group. Therefore, PRP could enhance functional and structural recovery in a severe HHcy-related ED model. A notable strength of the present study lies in the use of a repeated intracavernous injection method, mirroring protocols used in human studies, which offers more reliable results for translating the findings to humans.

Nicotinamide N-methyltransferase (NNMT): a novel therapeutic target for metabolic syndrome

Metabolic syndrome (MetS) represents a constellation of metabolic abnormalities, typified by obesity, hypertension, hyperglycemia, and hyperlipidemia. It stems from intricate dysregulations in metabolic pathways governing energy and substrate metabolism. While comprehending the precise etiological mechanisms of MetS remains challenging, evidence underscores the pivotal roles of aberrations in lipid metabolism and insulin resistance (IR) in its pathogenesis. Notably, nicotinamide N-methyltransferase (NNMT) has recently surfaced as a promising therapeutic target for addressing MetS. Single nucleotide variants in the NNMT gene are significantly correlated with disturbances in energy metabolism, obesity, type 2 diabetes (T2D), hyperlipidemia, and hypertension. Elevated NNMT gene expression is notably observed in the liver and white adipose tissue (WAT) of individuals with diabetic mice, obesity, and rats afflicted with MetS. Knockdown of NNMT elicits heightened energy expenditure in adipose and hepatic tissues, mitigates lipid accumulation, and enhances insulin sensitivity. NNMT catalyzes the methylation of nicotinamide (NAM) using S-adenosyl-methionine (SAM) as the donor methyl group, resulting in the formation of S-adenosyl-l-homocysteine (SAH) and methylnicotinamide (MNAM). This enzymatic process results in the depletion of NAM, a precursor of nicotinamide adenine dinucleotide (NAD+), and the generation of SAH, a precursor of homocysteine (Hcy). Consequently, this cascade leads to reduced NAD+ levels and elevated Hcy levels, implicating NNMT in the pathogenesis of MetS. Moreover, experimental studies employing RNA interference (RNAi) strategies and small molecule inhibitors targeting NNMT have underscored its potential as a therapeutic target for preventing or treating MetS-related diseases. Nonetheless, the precise mechanistic underpinnings remain elusive, and as of yet, clinical trials focusing on NNMT have not been documented. Therefore, further investigations are warranted to elucidate the intricate roles of NNMT in MetS and to develop targeted therapeutic interventions.

Unveiling potential therapeutic targets for diabetes-induced frozen shoulder through Mendelian randomization analysis of the human plasma proteome

INTRODUCTION

This study aimed to assess the causal relationship between diabetes and frozen shoulder by investigating the target proteins associated with diabetes and frozen shoulder in the human plasma proteome through Mendelian randomization (MR) and to reveal the corresponding pathological mechanisms.

RESEARCH DESIGN AND METHODS

We employed the MR approach for the purposes of establishing: (1) the causal link between diabetes and frozen shoulder; (2) the plasma causal proteins associated with frozen shoulder; (3) the plasma target proteins associated with diabetes; and (4) the causal relationship between diabetes target proteins and frozen shoulder causal proteins. The MR results were validated and consolidated through colocalization analysis and protein-protein interaction network.

RESULTS

Our MR analysis demonstrated a significant causal relationship between diabetes and frozen shoulder. We found that the plasma levels of four proteins were correlated with frozen shoulder at the Bonferroni significance level (p<3.03E-5). According to colocalization analysis, parathyroid hormone-related protein (PTHLH) was moderately correlated with the genetic variance of frozen shoulder (posterior probability=0.68), while secreted frizzled-related protein 4 was highly correlated with the genetic variance of frozen shoulder (posterior probability=0.97). Additionally, nine plasma proteins were activated during diabetes-associated pathologies. Subsequent MR analysis of nine diabetic target proteins with four frozen shoulder causal proteins indicated that insulin receptor subunit alpha, interleukin-6 receptor subunit alpha, interleukin-1 receptor accessory protein, glutathione peroxidase 7, and PTHLH might contribute to the onset and progression of frozen shoulder induced by diabetes.

CONCLUSIONS

Our study identified a causal relationship between diabetes and frozen shoulder, highlighting the pathological pathways through which diabetes influences frozen shoulder.

Exploring the pathogenesis of chronic atrophic gastritis with atherosclerosis via microarray data analysis

Although several studies have reported a link between chronic atrophic gastritis (CAG) and atherosclerosis, the underlying mechanisms have not been elucidated. The present study aimed to investigate the molecular mechanisms common to both diseases from a bioinformatics perspective. Gene expression profiles were obtained from the Gene Expression Omnibus database. Data on atherosclerosis and CAG were downloaded from the GSE28829 and GSE60662 datasets, respectively. We identified the differentially expressed genes co-expressed in CAG and atherosclerosis before subsequent analyses. We constructed and identified the hub genes and performed functional annotation. Finally, the transcription factor (TF)-target genes regulatory network was constructed. In addition, we validated core genes and certain TFs. We identified 116 common differentially expressed genes after analyzing the 2 datasets (GSE60662 and GSE28829). Functional analysis highlighted the significant contribution of immune responses and the positive regulation of tumor necrosis factor production and T cells. In addition, phagosomes, leukocyte transendothelial migration, and cell adhesion molecules strongly correlated with both diseases. Furthermore, 16 essential hub genes were selected with cytoHubba, including PTPRC, TYROBP, ITGB2, LCP2, ITGAM, FCGR3A, CSF1R, IRF8, C1QB, TLR2, IL10RA, ITGAX, CYBB, LAPTM5, CD53, CCL4, and LY86. Finally, we searched for key gene-related TFs, especially SPI1. Our findings reveal a shared pathogenesis between CAG and atherosclerosis. Such joint pathways and hub genes provide new insights for further studies.

Mitochondria-associated endoplasmic reticulum membranes as a therapeutic target for cardiovascular diseases

Cardiovascular diseases (CVDs) are currently the leading cause of death worldwide. In 2022, the CVDs contributed to 19.8 million deaths globally, accounting for one-third of all global deaths. With an aging population and changing lifestyles, CVDs pose a major threat to human health. Mitochondria-associated endoplasmic reticulum membranes (MAMs) are communication platforms between cellular organelles and regulate cellular physiological functions, including apoptosis, autophagy, and programmed necrosis. Further research has shown that MAMs play a critical role in the pathogenesis of CVDs, including myocardial ischemia and reperfusion injury, heart failure, pulmonary hypertension, and coronary atherosclerosis. This suggests that MAMs could be an important therapeutic target for managing CVDs. The goal of this study is to summarize the protein complex of MAMs, discuss its role in the pathological mechanisms of CVDs in terms of its functions such as Ca2+ transport, apoptotic signaling, and lipid metabolism, and suggest the possibility of MAMs as a potential therapeutic approach.

Caffeic acid protects against l-methionine induced reduction in neurogenesis and cognitive impairment in a rat model

l-methionine (L-met) is a substantial non-polar amino acid for normal development. L-met is converted to homocysteine that leads to hyperhomocysteinemia and subsequent excessive homocysteine in serum resulting in stimulating oxidative stress and vascular dementia. Several studies have found that hyperhomocysteine causes neuronal cell damage, which leads to memory impairment. Caffeic acid is a substrate in phenolic compound discovered in plant biosynthesis. Caffeic acid contains biological antioxidant and neuroprotective properties. The neuroprotective reaction of caffeic acid can protect against the brain disruption from hydrogen peroxide produced by oxidative stress. It also enhances GSH and superoxide dismutase activities, which protect against neuron cell loss caused by oxidative stress in the hippocampus. Hence, we investigated the protective role of caffeic acid in hippocampal neurogenesis and cognitive impairment induced by L-met in rats. Six groups of Sprague Dawley rats were assigned including control, L-met (1.7 g/kg/day), caffeic acid (20, 40 mg/kg), and L-met + caffeic acid (20, 40 mg/kg) groups. Spatial and recognition memories were subsequently examined using novel object location (NOL) and novel object recognition (NOR) tests. Moreover, the immunofluorescence technique was performed to detect Ki-67/RECA-1, bromodeoxyuridine (BrdU)/NeuN and p21 markers to represent hippocampal neurogenesis changes. The results revealed decreases in vasculature related cell proliferation and neuronal cell survival. By contrast, cell cycle arrest was increased in the L-met group. These results showed the association of the spatial and recognition memory impairments. However, the deterioration can be restored by co-administration with caffeic acid.

Lipid droplets, autophagy, and ER stress as key (survival) pathways during ischemia-reperfusion of transplanted grafts

Ischemia-reperfusion injury is an event concerning any organ under a procedure of transplantation. The early result of ischemia is hypoxia, which causes malfunction of mitochondria and decrease in cellular ATP. This leads to disruption of cellular metabolism. Reperfusion also results in cell damage due to reoxygenation and increased production of reactive oxygen species, and later by induced inflammation. In damaged and hypoxic cells, the endoplasmic reticulum (ER) stress pathway is activated by increased amount of damaged or misfolded proteins, accumulation of free fatty acids and other lipids due to inability of their oxidation (lipotoxicity). ER stress is an adaptive response and a survival pathway, however, its prolonged activity eventually lead to induction of apoptosis. Sustaining cell functionality in stress conditions is a great challenge for transplant surgeons as it is crucial for maintaining a desired level of graft vitality. Pathways counteracting negative consequences of ischemia-reperfusion are autophagy and lipid droplets (LD) metabolism. Autophagy remove damaged organelles and molecules driving them to lysosomes, digested simpler compounds are energy source for the cell. Mitophagy and ER-phagy results in improvement of cell energetic balance and alleviation of ER stress. This is important in sustaining metabolic homeostasis and thus cell survival. LD metabolism is connected with autophagy as LD are degraded by lipophagy, a source of free fatty acids and glycerol-thus autophagy and LD can readily remove lipotoxic compounds in the cell. In conclusion, monitoring and pharmaceutic regulation of those pathways during transplantation procedure might result in increased/improved vitality of transplanted organ.

Moderate Elevation of Homocysteine Induces Endothelial Dysfunction through Adaptive UPR Activation and Metabolic Rewiring

Elevation of the intermediate amino acid metabolite Homocysteine (Hcy) causes Hyperhomocysteinemia (HHcy), a metabolic disorder frequently associated with mutations in the methionine-cysteine metabolic cycle as well as with nutritional deficiency and aging. The previous literature suggests that HHcy is a strong risk factor for cardiovascular diseases. Severe HHcy is well-established to correlate with vascular pathologies primarily via endothelial cell death. Though moderate HHcy is more prevalent and associated with an increased risk of cardiovascular abnormalities in later part of life, its precise role in endothelial physiology is largely unknown. In this study, we report that moderate elevation of Hcy causes endothelial dysfunction through impairment of their migration and proliferation. We established that unlike severe elevation of Hcy, moderate HHcy is not associated with suppression of endothelial VEGF/VEGFR transcripts and ROS induction. We further showed that moderate HHcy induces a sub-lethal ER stress that causes defective endothelial migration through abnormal actin cytoskeletal remodeling. We also found that sub-lethal increase in Hcy causes endothelial proliferation defect by suppressing mitochondrial respiration and concomitantly increases glycolysis to compensate the consequential ATP loss and maintain overall energy homeostasis. Finally, analyzing a previously published microarray dataset, we confirmed that these hallmarks of moderate HHcy are conserved in adult endothelial cells as well. Thus, we identified adaptive UPR and metabolic rewiring as two key mechanistic signatures in moderate HHcy-associated endothelial dysfunction. As HHcy is clinically associated with enhanced vascular inflammation and hypercoagulability, identifying these mechanistic pathways may serve as future targets to regulate endothelial function and health.

Research Progress on the Pathogenesis of Aortic Aneurysm and Dissection in Metabolism

Aortic aneurysm and dissection are complicated diseases having both high prevalence and mortality. It is usually diagnosed at advanced stages and posing diagnostic and therapeutic challenges due to the limitations of current detecting methods for aortic dissection used in clinics. Metabonomics demonstrated its great potential capability in the early diagnosis and personalized treatment of several diseases. Emerging evidence suggests that metabolic disorders including amino acid metabolism, glycometabolism, and lipid metabolism disturbance are involved in the pathogenesis of aortic aneurysm and dissection by affecting multiple functional aortic cells. The purpose of this review is to provide new insights into the metabolism alterations and their related regulatory mechanisms with a focus on recent advances and findings and provide a theoretical basis for the diagnosis, prevention, and drug development for aortic aneurysm and dissection.

Association Between Serum Homocysteine Concentration, Aneurysm Wall Inflammation, and Aneurysm Symptoms in Intracranial Fusiform Aneurysm

RATIONALE AND OBJECTIVES

The pathophysiology of fusiform intracranial aneurysm (FIA) involves inflammatory processes, and homocysteine plays a role in the inflammatory processes in the vessel wall. Moreover, aneurysm wall enhancement (AWE) has emerged as a new imaging biomarker of aneurysm wall inflammatory pathologies. To investigate the pathophysiological mechanisms of aneurysm wall inflammation and FIA instability, we aimed to determine the associations between the homocysteine concentration, AWE, and FIAs' related symptoms.

MATERIALS AND METHODS

We retrospectively reviewed the data of 53 patients with FIA who underwent both high-resolution magnetic resonance imaging and serum homocysteine concentration measurement. FIAs' related symptoms were defined as ischemic stroke or transient ischemic attack, cranial nerve compression, brainstem compression, and acute headache. The contrast ratio of the signal intensity of the aneurysm wall to the pituitary stalk (CRstalk) was used to indicate AWE. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses were performed to determine how well the independent factors could predict FIAs' related symptoms. Predictors of CRstalk were also investigated. Spearman's correlation coefficient was used to identify the potential associations between these predictors.

RESULTS

Fifty-three patients were included, of whom 23 (43.4%) presented with FIAs' related symptoms. After adjusting for baseline differences in the multivariate logistic regression analysis, the CRstalk (odds ratio [OR]=3.207, P = .023) and homocysteine concentration (OR=1.344, P = .015) independently predicted FIAs' related symptoms. The CRstalk was able to differentiate between FIAs with and without symptoms (area under the ROC curve [AUC]=0.805), with an optimal cutoff value of 0.76. The homocysteine concentration could also differentiate between FIAs with and without symptoms (AUC=0.788), with an optimal cutoff value of 13.13. The combination of the CRstalk and homocysteine concentration had a better ability to identify symptomatic FIAs (AUC=0.857). Male sex (OR=0.536, P = .018), FIAs' related symptoms (OR=1.292, P = .038), and homocysteine concentration (OR=1.254, P = .045) independently predicted the CRstalk.

CONCLUSION

A higher serum homocysteine concentration and greater AWE indicate FIA instability. Serum homocysteine concentration may be a useful biomarker of FIA instability; however, this needs to be verified in future studies.

The Implication of a Polymorphism in the Methylenetetrahydrofolate Reductase Gene in Homocysteine Metabolism and Related Civilisation Diseases

Methylenetetrahydrofolate reductase (MTHFR) is a key regulatory enzyme in the one-carbon cycle. This enzyme is essential for the metabolism of methionine, folate, and RNA, as well as for the production of proteins, DNA, and RNA. MTHFR catalyses the irreversible conversion of 5,10-methylenetetrahydrofolate to its active form, 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. Numerous variants of the MTHFR gene have been recognised, among which the C677T variant is the most extensively studied. The C677T polymorphism, which results in the conversion of valine to alanine at codon 222, is associated with reduced activity and an increased thermolability of the enzyme. Impaired MTHFR efficiency is associated with increased levels of homocysteine, which can contribute to increased production of reactive oxygen species and the development of oxidative stress. Homocysteine is acknowledged as an independent risk factor for cardiovascular disease, while chronic inflammation serves as the common underlying factor among these issues. Many studies have been conducted to determine whether there is an association between the C677T polymorphism and an increased risk of cardiovascular disease, hypertension, diabetes, and overweight/obesity. There is substantial evidence supporting this association, although several studies have concluded that the polymorphism cannot be reliably used for prediction. This review examines the latest research on MTHFR polymorphisms and their correlation with cardiovascular disease, obesity, and epigenetic regulation.

Valsartan Attenuated Homocysteine-Induced Impaired Autophagy and ER Stress in Human Umbilical Vein Endothelial Cells

Hyperhomocysteinemia is a risk factor for various cardiovascular diseases. However, the mechanism underlying homocysteine- (Hcy-) induced vascular injury remains unclear. The purpose of the present study was to examine a potential mechanism by which Hcy induced injury in human umbilical vascular endothelial cells (HUVEC). The protein abundance of autophagy-related markers was markedly decreased after Hcy treatment, which was associated with endoplasmic reticulum (ER) stress and apoptosis in HUVECs. Protein expression level of angiotensin II type 1 receptor (AT1 receptor) was dramatically increased in response to Hcy. Valsartan, an AT1 receptor blocker, improved autophagy and prevented ER stress and apoptosis in HUVECs treated with Hcy. Consistent with this, silence of AT1 receptor with siRNA decreased the protein abundance of ER stress markers, prevented apoptosis, and promoted autophagy in HUVECs. Inhibition or knockdown of AT1 receptor was shown to be associated with suppression of p-GSK3β/GSK3β-p-mTOR/mTOR signaling pathway. Additionally, inhibition of autophagy by 3-MA aggravated Hcy-induced apoptosis, while amelioration of ER stress by 4-PBA prevented Hcy-induced injury in HUVECs. Hcy-induced HUVEC injury was likely attributed to AT1 receptor activation, leading to impaired autophagy, ER stress, and apoptosis.

The influence of redox modulation on hypoxic endothelial cell metabolic and proteomic profiles through a small thiol-based compound tuning glutathione and thioredoxin systems

Reduction in oxygen levels is a key feature in the physiology of the bone marrow (BM) niche where hematopoiesis occurs. The BM niche is a highly vascularized tissue and endothelial cells (ECs) support and regulate blood cell formation from hematopoietic stem cells (HSCs). While in vivo studies are limited, ECs when cultured in vitro at low O2 (<5%), fail to support functional HSC maintenance due to oxidative environment. Therefore, changes in EC redox status induced by antioxidant molecules may lead to alterations in the cellular response to hypoxia likely favoring HSC self-renewal. To evaluate the impact of redox regulation, HUVEC, exposed for 1, 6, and 24 h to 3% O2 were treated with N-(N-acetyl-l-cysteinyl)-S-acetylcysteamine (I-152). Metabolomic analyses revealed that I-152 increased glutathione levels and influenced the metabolic profiles interconnected with the glutathione system and the redox couples NAD(P)+/NAD(P)H. mRNA analysis showed a lowered gene expression of HIF-1α and VEGF following I-152 treatment whereas TRX1 and 2 were stimulated. Accordingly, the proteomic study revealed the redox-dependent upregulation of thioredoxin and peroxiredoxins that, together with the glutathione system, are the main regulators of intracellular ROS. Indeed, a time-dependent ROS production under hypoxia and a quenching effect of the molecule were evidenced. At the secretome level, the molecule downregulated IL-6, MCP-1, and PDGF-bb. These results suggest that redox modulation by I-152 reduces oxidative stress and ROS level in hypoxic ECs and may be a strategy to fine-tune the environment of an in vitro BM niche able to support functional HSC maintenance.

Infection with Helicobacter pylori may predispose to atherosclerosis: role of inflammation and thickening of intima-media of carotid arteries

Atherosclerosis is a major instigator of cardiovascular disease (CVD) and a main cause of global morbidity and mortality. The high prevalence of CVD calls for urgent attention to possible preventive measures in order to curb its incidence. Traditional risk factors of atherosclerosis, like age, smoking, diabetes mellitus, dyslipidemia, hypertension and chronic inflammation, are under extensive investigation. However, these only account for around 50% of the etiology of atherosclerosis, mandating a search for different or overlooked risk factors. In this regard, chronic infections, by Helicobacter pylori for instance, are a primary candidate. H. pylori colonizes the gut and contributes to several gastrointestinal diseases, but, recently, the potential involvement of this bacterium in extra-gastric diseases including CVD has been under the spotlight. Indeed, H. pylori infection appears to stimulate foam cell formation as well as chronic immune responses that could upregulate key inflammatory mediators including cytokines, C-reactive protein, and lipoproteins. These factors are involved in the thickening of intima-media of carotid arteries (CIMT), a hallmark of atherosclerosis. Interestingly, H. pylori infection was found to increase (CIMT), which along with other evidence, could implicate H. pylori in the pathogenesis of atherosclerosis. Nevertheless, the involvement of H. pylori in CVD and atherosclerosis remains controversial as several studies report no connection between H. pylori and atherosclerosis. This review examines and critically discusses the evidence that argues for a potential role of this bacterium in atherogenesis. However, additional basic and clinical research studies are warranted to convincingly establish the association between H. pylori and atherosclerosis.

Are Proton Pump Inhibitors Contributing in Emerging New Hypertensive Population?

Balancing the therapeutic advantages of a medicine with its possible risks and side effects is an important part of medical practice and drug regulation. When a drug is designed to treat a particular disease or medical condition ends up causing additional risks or side effects that lead to the development of other serious health problems, it can have detrimental consequences for patients. This article explores the correlation between persistent proton pump inhibitor (PPI) use and hypertension, a common cardiovascular ailment. While PPIs are beneficial in treating various gastrointestinal problems, their availability without a prescription has resulted in self-medication and long-term use without medical monitoring. Recent findings have revealed a link between long-term PPI usage and increased cardiovascular risks, particularly hypertension. This study investigates the intricate mechanisms underlying PPI's effects, focusing on potential pathways contributing to hypertension, such as endothelial dysfunction, disruption of nitric oxide bioavailability, vitamin B deficiency, hypocalcemia, and hypomagnesemia. The discussion explains how long-term PPI use can disrupt normal endothelial function, vascular control, and mineral balance, eventually leading to hypertension. The article emphasizes the significance of using PPIs with caution and ongoing research to better understand the implications of these medications on cardiovascular health.

Application of homocysteine as a non-invasive and effort-free measurements for risk assessment of patients with pulmonary hypertension

BACKGROUND

Current guideline-recommended multiparameters used to assess the risk levels of pulmonary arterial hypertension (PAH) are invasive hemodynamic measurements or effort-dependent exercise tests. Serum natriuretic peptide is only one kind of effort-free biomarker that has been adopted for risk assessment. This study aimed to investigate the application of homocysteine as a non-invasive and effort-free measurement for the risk assessment of patients with PAH.

METHODS

Samples of 50 patients diagnosed with PAH via right heart catheterization were obtained, and the patients were divided into low-, intermediate- and high-risk groups for further analysis. Additionally, serum N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) and homocysteine levels of monocrotaline (MCT)-induced PAH rats were analyzed at each week with progressed severity of PAH, and they were sacrificed on day 28 with pathology being assessed.

RESULTS

Hyperhomocysteinemia was an independent predictor (odds ratio [OR]: 1.256; 95% confidence interval [CI]: 1.002-1.574) and showed a linear correlation with NT-proBNP. Hyperhomocysteinemia could discriminate between low/intermediate and high-risk levels in PAH with a cut-off value in 12 μmol/L. Moreover, the elevated homocysteine levels by weeks in MCT rats also demonstrated the association between homocysteine and the severity of PAH.

CONCLUSIONS

Homocysteine can be a non-invasive and effort-free risk assessment for patients with pulmonary hypertension. Homocysteine level had a linear correlation with NT-proBNP level, and patients with hyperhomocysteinemia had a higher risk level, higher NT-proBNP level, and decreased lower diffusing capacity for carbon monoxide. The correlation between homocysteine level and PAH severity was also demonstrated in MCT rats.

Arginine, Transsulfuration, and Folic Acid Pathway Metabolomics in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

There is an increasing interest in biomarkers of nitric oxide dysregulation and oxidative stress to guide management and identify new therapeutic targets in patients with chronic obstructive pulmonary disease (COPD). We conducted a systematic review and meta-analysis of the association between circulating metabolites within the arginine (arginine, citrulline, ornithine, asymmetric, ADMA, and symmetric, SDMA dimethylarginine), transsulfuration (methionine, homocysteine, and cysteine) and folic acid (folic acid, vitamin B6, and vitamin B12) metabolic pathways and COPD. We searched electronic databases from inception to 30 June 2023 and assessed the risk of bias and the certainty of evidence. In 21 eligible studies, compared to healthy controls, patients with stable COPD had significantly lower methionine (standardized mean difference, SMD = -0.50, 95% CI -0.95 to -0.05, p = 0.029) and folic acid (SMD = -0.37, 95% CI -0.65 to -0.09, p = 0.009), and higher homocysteine (SMD = 0.78, 95% CI 0.48 to 1.07, p < 0.001) and cysteine concentrations (SMD = 0.34, 95% CI 0.02 to 0.66, p = 0.038). Additionally, COPD was associated with significantly higher ADMA (SMD = 1.27, 95% CI 0.08 to 2.46, p = 0.037), SDMA (SMD = 3.94, 95% CI 0.79 to 7.08, p = 0.014), and ornithine concentrations (SMD = 0.67, 95% CI 0.13 to 1.22, p = 0.015). In subgroup analysis, the SMD of homocysteine was significantly associated with the biological matrix assessed and the forced expiratory volume in the first second to forced vital capacity ratio, but not with age, study location, or analytical method used. Our study suggests that the presence of significant alterations in metabolites within the arginine, transsulfuration, and folic acid pathways can be useful for assessing nitric oxide dysregulation and oxidative stress and identifying novel treatment targets in COPD. (PROSPERO registration number: CRD42023448036.).

Evaluation of serum vitamin B12 levels in patients with COVID-19 infection: A case-control study

Background

COVID-19 disease affects the respiratory and cardiovascular systems. Vitamin B12 has been associated with A1AT, one of the protective factors of lung tissue, and homocysteine among the cardiovascular risk factors. Therefore we suggest that low vitamin B12 levels are associated with a disposition to COVID-19 infection. This study aims to determine whether there is a relationship between COVID-19 infection and serum vitamin B12 levels.

Methods

This research is a case-control study. Seventy-six people with COVID-19 constituted the case group. Seventy-six people without COVID-19 formed the control group. Vitamin B12 and homocysteine levels of 152 patients included in the study were analyzed.

Results

The odds ratio for vitamin B12 was 0.99 (0.978-0.995). When the value of the vitamin B12 variable decreases by one unit, the risk of COVID-19 increases by 1%. The odds ratio for homocysteine was 1.81 (1.414-2.325). When the value of the homocysteine variable increases by one unit, the risk of COVID-19 increases by 1.81 times. According to ROC analysis, when serum vitamin B12 is below 222.5 ng/L and homocysteine is above 13.7 mmol/L, it may increase the risk of COVID-19.

Conclusions

We suggest that patients with low vitamin B12 levels and high homocysteine levels are more severely affected by COVID-19 infection.

Reducing oxidative protein folding alleviates senescence by minimizing ER-to-nucleus H2 O2 release

Oxidative protein folding occurs in the endoplasmic reticulum (ER) to generate disulfide bonds, and the by-product is hydrogen peroxide (H2 O2 ). However, the relationship between oxidative protein folding and senescence remains uncharacterized. Here, we find that the protein disulfide isomerase (PDI), a key oxidoreductase that catalyzes oxidative protein folding, accumulated in aged human mesenchymal stem cells (hMSCs) and deletion of PDI alleviated hMSCs senescence. Mechanistically, knocking out PDI slows the rate of oxidative protein folding and decreases the leakage of ER-derived H2 O2 into the nucleus, thereby decreasing the expression of SERPINE1, which was identified as a key driver of cell senescence. Furthermore, we show that depletion of PDI alleviated senescence in various cell models of aging. Our findings reveal a previously unrecognized role of oxidative protein folding in promoting cell aging, providing a potential target for aging and aging-related disease intervention.

SIRT6 deficiency in endothelial cells exacerbates oxidative stress by enhancing HIF1α accumulation and H3K9 acetylation at the Ero1α promoter

BACKGROUND

SIRT6, an important NAD+ -dependent protein, protects endothelial cells from inflammatory and oxidative stress injuries. However, the role of SIRT6 in cardiac microvascular endothelial cells (CMECs) under ischemia-reperfusion injury (IRI) remains unclear.

METHODS

The HUVECs model of oxygen-glucose deprivation/reperfusion (OGD/R) was established to simulate the endothelial IRI in vitro. Endoplasmic reticulum oxidase 1 alpha (Ero1α) mRNA and protein levels in SIRT6-overexpressing or SIRT6-knockdown cells were measured by qPCR and Western blotting. The levels of H2 O2 and mitochondrial reactive oxygen species (ROS) were detected to evaluate the status of oxidative stress. The effects of SIRT6 deficiency and Ero1α knockdown on cellular endoplasmic reticulum stress (ERS), inflammation, apoptosis and barrier function were detected by a series of molecular biological experiments and functional experiments in vitro. Chromatin immunoprecipitation, Western blotting, qPCR, and site-specific mutation experiments were used to examine the underlying molecular mechanisms. Furthermore, endothelial cell-specific Sirt6 knockout (ecSirt6-/- ) mice were subjected to cardiac ischemia-reperfusion surgery to investigate the effects of SIRT6 in CMECs in vivo.

RESULTS

The expression of Ero1α was significantly upregulated in SIRT6-knockdown endothelial cells, and high Ero1α expression correlated with the accumulation of H2 O2 and mitochondrial ROS. In addition, SIRT6 deficiency increased ERS, inflammation, apoptosis and endothelial permeability, and these effects could be significantly attenuated by Ero1α knockdown. The deacetylase catalytic activity of SIRT6 was important in regulating Ero1α expression and these biological processes. Mechanistically, SIRT6 inhibited the enrichment of HIF1α and p300 at the Ero1α promoter through deacetylating H3K9, thereby antagonizing HIF1α/p300-mediated Ero1α expression. Compared with SIRT6-wild-type (SIRT6-WT) cells, cells expressing the SIRT6-H133Y-mutant and SIRT6-R65A-mutant exhibited increased Ero1α expression. Furthermore, ecSirt6-/- mice subjected to ischemia-reperfusion surgery exhibited increased Ero1α expression and ERS in CMECs and worsened injuries to microvascular barrier function and cardiac function.

CONCLUSIONS

Our results revealed an epigenetic mechanism associated with SIRT6 and Ero1α expression and highlighted the therapeutic potential of targeting the SIRT6-HIF1α/p300-Ero1α axis.

Glycyrrhizic Acid Inhibits High-Mobility Group Box-1 and Homocysteine-Induced Vascular Dysfunction

Hyperhomocysteinemia (HHcy) worsens cardiovascular outcomes by impairing vascular function and promoting chronic inflammation via release of danger-associated molecular patterns, such as high-mobility group box-1 (HMGB-1). Elevated levels of HMGB-1 have recently been reported in patients with HHcy. Therefore, targeting HMGB-1 may be a potential therapy to improve HHcy-induced cardiovascular pathologies. This study aimed to further elucidate HMGB-1's role during acute HHcy and HHcy-induced atherogenesis and to determine if inhibiting HMGB-1 with glycyrrhizic acid (Glyz) improved vascular function. Male New Zealand White rabbits (n = 25) were placed on either a standard control chow (CD; n = 15) or atherogenic diet (AD; n = 10) for 4 weeks. Rabbit serum and Krebs taken from organ bath studies were collected to quantify HMGB-1 levels. Isometric tension analysis was performed on abdominal aorta (AA) rings from CD and AD rabbits. Rings were incubated with homocysteine (Hcy) [3 mM] for 60 min to induce acute HHcy or rhHMGB-1 [100 nM]. Vascular function was assessed by relaxation to cumulative doses of acetylcholine. Markers of vascular dysfunction and inflammation were quantified in the endothelium, media, and adventitia of AA rings. HMGB-1 was significantly upregulated in serum (p < 0.0001) and Krebs (p < 0.0001) after Hcy exposure or an AD. Incubation with Hcy (p < 0.0001) or rhHMGB-1 (p < 0.0001) and an AD (p < 0.0001) significantly reduced relaxation to acetylcholine, which was markedly improved by Glyz. HMGB-1 expression was elevated (p < 0.0001) after Hcy exposure and AD (p < 0.0001) and was normalized after Glyz treatment. Moreover, markers of vascular function, cell stress and inflammation were also reduced after Glyz. These results demonstrate that HMGB-1 has a central role during HHcy-induced vascular dysfunction and inhibiting it with Glyz could be a potential treatment option for cardiovascular diseases.

Association between homocysteine level and length of stay in patients with lower extremity atherosclerotic disease: a retrospective cohort study

OBJECTIVES

Homocysteine (Hcy) level has been widely identified as a risk factor associated with adverse outcomes in patients with lower extremity atherosclerotic disease (LEAD). However, there are still some knowledge gaps in research on the association between Hcy level and downstream adverse outcomes, such as length of stay (LOS). This study aims to explore whether and to what extent Hcy level is associated with LOS in patients with LEAD.

DESIGN

Retrospective cohort study.

SETTING

China.

PARTICIPANTS, PRIMARY AND SECONDARY OUTCOMES

We conducted a retrospective cohort study of 748 patients from inpatients with LEAD between January 2014 and November 2021 at the First Hospital of China Medical University in China. We used a slew of generalised linear models to evaluate the association between Hcy level and LOS.

RESULTS

The patients' median age was 68 years and 631 (84.36%) were males. A dose-response curve with an inflection point at 22.63 µmol/L was observed between Hcy level and LOS after the adjustment of potential confounders. LOS increased before Hcy level reached the inflection point (β: 0.36; 95% CI: 0.18 to 0.55; p<0.001).ConclusionOur results show that an Hcy level <22.63 µmol/L is associated with increased LOS in patients with LEAD, which was independent of some other risk factors. This might shed light on how Hcy can be used as a key marker in the comprehensive management of patients with LEAD during hospitalisation.

Thymoquinone reverses homocysteine-induced endothelial dysfunction via inhibition of ER-stress induced oxidative stress pathway.. [DOI: 10.21203/rs.3.rs-2964177/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hyperhomocysteinemia has been linked to an increased risk of cardiovascular diseases. High levels of homocysteine (Hcy) promote endoplasmic reticulum (ER) stress that can increase reactive oxygen species (ROS), leading to endothelial dysfunction. Thymoquinone (TQ) is the major active ingredient in Nigella sativa seeds volatile oil and is shown to have a cardioprotective effect. However, no study evaluated the effect of TQ against Hcy-induced endothelial dysfunction. Thus, this study aims to investigate the effects and mechanisms of TQ in reversing Hcy-induced endothelial dysfunction. Isolated aorta from male Sprague-Dawley (SD) rats incubated with Hcy (500 µM) and co-treated with or without TQ (0.1 µM, 1 µM, and 10 µM), 20 µM TUDCA, 100 µM Apocynin or 1 mM Tempol in organ bath to study the vascular function. Additionally, human umbilical vein endothelial cells (HUVECs) were incubated with Hcy (10 mM) and various concentrations of TQ (1 and 10 𝜇M), Tempol (100 𝜇M), Apocynin (100 𝜇M), TUDCA (100 𝜇M) or H2O2 (0.25 mM) to evaluate the cell viability by using a phase contrast microscope and dye exclusion assay. Involvement of ER stress pathway, ROS and NO bioavailability were accessed via immunoassay and fluorescent staining respectively. Molecular docking was performed to evaluate the binding affinity of TQ to GRP78. Our results revealed that Hcy impaired endothelium-dependant relaxation in isolated aorta and induced apoptosis in HUVECs. These effects were reversed by TQ, TUDCA, tempol and apocynin. Treatment with TQ (10𝜇M) also reduced ROS level, improved NO bioavailability as well reduced GRP78 and NOX4 protein in HUVECs. Result from the molecular docking study showed that TQ could bind well to GRP78 through hydrogen bond and hydrophobic interaction with the amino acid at GRP78 ATP binding pocket. Taken together, the present results suggest that TQ preserved endothelial function in rat aorta and reduced apoptosis of HUVECs induced by Hcy through the inhibition of ER stress-mediated ROS and eNOS uncoupling.

Plasma Homocysteine (Hcy) Concentration Functions as a Predictive Biomarker of SPECT-Evaluated Post-Ischemic Hyperperfusion in Acute Ischemic Stroke

Introduction

Homocysteine (Hcy) concentration has been reported to be associated with ischemic stroke. In this study, we aimed to investigate the potential of plasma Hcy in the prediction of post-ischemic hyperperfusion in AIS patients, which was diagnosed with the single-photon emission computed tomography (SPECT) method.

Methods

A total of 112 ischemic stroke patients were recruited in this study. According to whether the patients were subjected to post-ischemic hyperperfusion, all recruited subjects were divided into a post-ischemic hyperperfusion (+) group (N=48) and post-ischemic hyperperfusion (-) group (N=64). The basic demographical data, clinicopathological data and laboratory biochemical data were collected and compared. Level of homocysteine (Hcy) and cystatin-C (Cys-C) and their potential as predictive biomarker are also investigated.

Results

No significant differences were spotted between the post-ischemic hyperperfusion group (+) and post-ischemic hyperperfusion (-) group in respect to the basic demographical and clinicopathological data. And the serum Hcy levels were lower in the post-ischemic hyperperfusion (+) group. Moreover, ROC analysis indicated significant relationships between Hcy levels and the onset of post-ischemic hyperperfusion.

Conclusion

In conclusion, we validated that the plasma Hcy concentration can be used as a predictive biomarker of SPECT-evaluated post-ischemic hyperperfusion in patients suffering from acute ischemic stroke.

Parkinson's Disease Risk and Hyperhomocysteinemia: The Possible Link

Parkinson's disease (PD) is one of the most common degenerative brain disorders caused by the loss of dopaminergic neurons in the substantia nigra (SN). Lewy bodies and -synuclein accumulation in the SN are hallmarks of the neuropathology of PD. Due to lifestyle changes and prolonged L-dopa administration, patients with PD frequently have vitamin deficiencies, especially folate, vitamin B6, and vitamin B12. These disorders augment circulating levels of Homocysteine with the development of hyperhomocysteinemia, which may contribute to the pathogenesis of PD. Therefore, this review aimed to ascertain if hyperhomocysteinemia may play a part in oxidative and inflammatory signaling pathways that contribute to PD development. Hyperhomocysteinemia is implicated in the pathogenesis of neurodegenerative disorders, including PD. Hyperhomocysteinemia triggers the development and progression of PD by different mechanisms, including oxidative stress, mitochondrial dysfunction, apoptosis, and endothelial dysfunction. Particularly, the progression of PD is linked with high inflammatory changes and systemic inflammatory disorders. Hyperhomocysteinemia induces immune activation and oxidative stress. In turn, activated immune response promotes the development and progression of hyperhomocysteinemia. Therefore, hyperhomocysteinemia-induced immunoinflammatory disorders and abnormal immune response may aggravate abnormal immunoinflammatory in PD, leading to more progression of PD severity. Also, inflammatory signaling pathways like nuclear factor kappa B (NF-κB) and nod-like receptor pyrin 3 (NLRP3) inflammasome and other signaling pathways are intricate in the pathogenesis of PD. In conclusion, hyperhomocysteinemia is involved in the development and progression of PD neuropathology either directly via induction degeneration of dopaminergic neurons or indirectly via activation of inflammatory signaling pathways.

Hyperhomocysteinemia in Cardiovascular Diseases: Revisiting Observational Studies and Clinical Trials

Thromboembolic manifestations are relatively frequent in patients with intermediate/severe hyperhomocysteinemia (>30 µmol/L) related to inherited disorders and deficiencies in vitamin B12 and folate. In contrast, moderate hyperhomocysteinemia (15-30 µmol/L) is a modest predictor of cardiovascular risk. The recognition of homocysteine as a cardiovascular risk factor has been challenged by some but not all randomized clinical trials. We reviewed the main data of this controversy and formulated conclusions to be translated in clinical practice.Homocysteine-lowering trials have been performed in cardiovascular subjects with moderate but not intermediate/severe hyperhomocysteinemia despite the dose-effect risk association. The first meta-analyses found no benefit and led cardiology societies not recommending homocysteine in the assessment of cardiovascular risk. This guideline challenged the need to diagnose and treat the nutritional and genetic causes of intermediate/major hyperhomocysteinemia and was not revised when larger meta-analyses concluded to a reduced risk of stroke. In a recent observational study, 84% of consecutive cardiovascular patients assessed for homocysteine had intermediate or major hyperhomocysteinemia, which was properly assessed in only half of the cases and related to B12 and/or folate deficiency and Addison/Biermer disease in 55% of these cases.In conclusion, revisiting observational studies and clinical trials suggests that cardiovascular patients should be screened for hyperhomocysteinemia, when no other risk factor is found. Patients with intermediate/major hyperhomocysteinemia should be properly assessed and treated for B vitamin deficiencies and inherited disorders according to current guidelines. Further trials are needed to assess the effect of lowering homocysteine according to hyperhomocysteinemia categories at baseline.

Emodin protects against homocysteine-induced cardiac dysfunction by inhibiting oxidative stress via MAPK and Akt/eNOS/NO signaling pathways

Elevated levels of plasma homocysteine (Hcy) causes severe cardiac dysfunction, which is closely associated with oxidative stress. Emodin, a naturally occurring anthraquinone derivative, has been shown to exert antioxidant and anti-apoptosis activities. However, whether emodin could protect against Hcy-induced cardiac dysfunction remains unknown. The current study aimed to investigate the effects of emodin on the Hcy-induced cardiac dysfunction and its molecular mechanisms. Rats were fed a methionine diet to establish the animal model of hyperhomocysteinemia (HHcy). H9C2 cells were incubated with Hcy to induce a cell model of Hcy-injured cardiomyocytes. ELISA, HE staining, carotid artery and left ventricular cannulation, MTT, fluorescence staining, flow cytometry and western blotting were used in this study. Emodin significantly alleviated the structural damage of the myocardium and cardiac dysfunction from HHcy rats. Emodin prevented apoptosis and the collapse of MMP in the Hcy-treated H9C2 cells in vitro. Further, emodin reversed the Hcy-induced apoptosis-related biochemical changes including decreased Bcl-2/Bax protein ratio, and increased protein expression of Caspase-9/3. Moreover, emodin suppressed oxidative stress in Hcy-treated H9C2 cells. Mechanistically, emodin significantly inhibited the Hcy-activated MAPK by reducing ROS generation in H9C2 cells. Furthermore, emodin upregulated NO production by promoting the protein phosphorylation of Akt and eNOS in injured cells. The present study shows that emodin protects against Hcy-induced cardiac dysfunction by inhibiting oxidative stress via MAPK and Akt/eNOS/NO signaling pathways.

Sodium tanshinone IIA sulfonate protects against hyperhomocysteine-induced vascular endothelial injury via activation of NNMT/SIRT1-mediated NRF2/HO-1 and AKT/MAPKs signaling in human umbilical vascular endothelial cells

Homocysteine (Hcy) is one of the independent risk factors of cardiovascular disease. Sodium tanshinone IIA sulfonate (STS) is a hydrophilic derivate of tanshinone IIA which is the main active constitute of Chinese Materia Medica Salviae Miltiorrhizae Radix et Rhizoma, and exhibits multiple pharmacological activities. However, whether STS could prevent from Hcy-induced endothelial cell injury is unknown. We found that STS dramatically reversed Hcy-induced cell death concentration dependently in human umbilical vascular endothelial cells (HUVECs). STS ameliorated the endothelial cell cycle progression, proliferation and cell migratory function impaired by Hcy, which might be co-related to the inhibition of intracellular oxidative stress and mitochondrial dysfunction. STS also elevated the phosphorylation of AKT and MAPKs and protein expression of sirtuin1 (SIRT1), NRF2 and HO-1 which were suppressed by Hcy. The protective effect of STS against Hcy-induced endothelial cell toxicity was partially attenuated by PI3K, AKT, MEK, ERK, SIRT1, NRF2 and HO-1 inhibitors. Besides, knockdown of SIRT1 by its siRNA dramatically decreased the endothelial protective effect of STS accompanied with suppression of SIRT1, NRF2, HO-1 and phosphorylated AKT. The activation of AKT or NRF2 partially reversed SIRT1-knockdown impaired cyto-protective effect of STS against Hcy-induced cell injury. Furthermore, STS prevented from Hcy-induced intracellular nicotinamide N-methyltransferase (NNMT) reduction along with elevation of intracellular methylnicotinamide (MNA), and MNA enhanced STS protecting against Hcy induced endothelial death. Knockdown of NNMT reduced the protective effect of STS against Hcy induced endothelial cell injury. Collectively, STS presented potent endothelial protective effect against Hcy and the underlying molecular mechanisms were involved in the suppression of intracellular oxidative stress and mitochondria dysfunction by activation of AKT/MAPKs, SIRT1/NRF2/HO-1 and NNMT/MNA signaling pathways.

The Relationship between Elevated Homocysteine and Metabolic Syndrome in a Community-Dwelling Middle-Aged and Elderly Population in Taiwan

(1) Background: Metabolic syndrome has become a serious health problem in society. Homocysteine is a biomarker for cardiovascular disease. We investigated the relationship between homocysteine levels and metabolic syndrome. (2) Methods: A total of 398 middle-aged and elderly individuals were included in our study. First, we divided the participants into two groups: the metabolic syndrome group and the nonmetabolic syndrome group. Second, according to tertiles of homocysteine levels from low to high, the participants were divided into first, second, and third groups. Pearson's correlation was then calculated for homocysteine levels and metabolic factors. Scatterplots are presented. Finally, the risk of metabolic syndrome in the second and third groups compared with the first group was assessed by multivariate logistic regression. (3) Results: In our study, the metabolic syndrome group had higher homocysteine levels, and the participants in the third group were more likely to have metabolic syndrome. Multivariate logistic regression revealed that the third group, which had the highest homocysteine level, was associated with metabolic syndrome with an odds ratio of 2.32 compared with the first group after adjusting for risk factors. (4) Conclusions: We concluded that high plasma homocysteine levels were independently associated with MetS in our study population.

Mechanism of homocysteine-mediated endothelial injury and its consequences for atherosclerosis

Homocysteine (Hcy) is an intermediate amino acid formed during the conversion from methionine to cysteine. When the fasting plasma Hcy level is higher than 15 μmol/L, it is considered as hyperhomocysteinemia (HHcy). The vascular endothelium is an important barrier to vascular homeostasis, and its impairment is the initiation of atherosclerosis (AS). HHcy is an important risk factor for AS, which can promote the development of AS and the occurrence of cardiovascular events, and Hcy damage to the endothelium is considered to play a very important role. However, the mechanism by which Hcy damages the endothelium is still not fully understood. This review summarizes the mechanism of Hcy-induced endothelial injury and the treatment methods to alleviate the Hcy induced endothelial dysfunction, in order to provide new thoughts for the diagnosis and treatment of Hcy-induced endothelial injury and subsequent AS-related diseases.

Plant homocysteine, a methionine precursor and plant's hallmark of metabolic disorders

Homocysteine (Hcy) is a sulfur-containing non-proteinogenic amino acid, which arises from redox-sensitive methionine metabolism. In plants, Hcy synthesis involves both cystathionine β-lyase and S-adenosylhomocysteine hydrolase activities. Thus, Hcy itself is crucial for de novo methionine synthesis and S-adenosylmethionine recycling, influencing the formation of ethylene, polyamines, and nicotianamine. Research on mammalian cells has shown biotoxicity of this amino acid, as Hcy accumulation triggers oxidative stress and the associated lipid peroxidation process. In addition, the presence of highly reactive groups induces Hcy and Hcy derivatives to modify proteins by changing their structure and function. Currently, Hcy is recognized as a critical, independent hallmark of many degenerative metabolic diseases. Research results indicate that an enhanced Hcy level is also toxic to yeast and bacteria cells. In contrast, in the case of plants the metabolic status of Hcy remains poorly examined and understood. However, the presence of the toxic Hcy metabolites and Hcy over-accumulation during the development of an infectious disease seem to suggest harmful effects of this amino acid also in plant cells. The review highlights potential implications of Hcy metabolism in plant physiological disorders caused by environmental stresses. Moreover, recent research advances emphasize that recognizing the Hcy mode of action in various plant systems facilitates verification of the potential status of Hcy metabolites as bioindicators of metabolism disorders and thus may constitute an element of broadly understood biomonitoring.

Epigenetic Regulation by microRNAs in Hyperhomocysteinemia-Accelerated Atherosclerosis

Increased serum levels of homocysteine (Hcy) is a risk factor for cardiovascular disease and is specifically linked to various diseases of the vasculature such as atherosclerosis. However, the precise mechanisms by which Hcy contributes to this condition remain elusive. During the development of atherosclerosis, epigenetic modifications influence gene expression. As such, epigenetic modifications are an adaptive response to endogenous and exogenous factors that lead to altered gene expression by methylation and acetylation reactions of different substrates and the action of noncoding RNA including microRNAs (miRNAs). Epigenetic remodeling modulates cell biology in both physiological and physiopathological conditions. DNA and histone modification have been identified to have a crucial role in the progression of atherosclerosis. However, the potential role of miRNAs in hyperHcy (HHcy)-related atherosclerosis disease remains poorly explored and might be essential as well. There is no review available yet summarizing the contribution of miRNAs to hyperhomocystein-mediated atherogenicity or their potential as therapeutic targets even though their important role has been described in numerous studies. Specifically, downregulation of miR-143 or miR-125b has been shown to regulate VSCMs proliferation in vitro. In preclinical studies, downregulation of miR-92 or miR195-3p has been shown to increase the accumulation of cholesterol in foam cells and increase macrophage inflammation and atherosclerotic plaque formation, respectively. Another preclinical study found that there is a reciprocal regulation between miR-148a/152 and DNMT1 in Hcy-accelerated atherosclerosis. Interestingly, a couple of studies have shown that miR-143 or miR-217 may be used as potential biomarkers in patients with HHcy that may develop atherosclerosis. Moreover, the current review will also update current knowledge on miRNA-based therapies, their challenges, and approaches to deal with Hcy-induced atherosclerosis.

Association of Serum Homocysteine with Cardiovascular and All-Cause Mortality in Adults with Diabetes: A Prospective Cohort Study

Background

Homocysteine (Hcy) was implicated in oxidative stress and diabetes biologically. However, the clinical evidence on the link between Hcy level and diabetes is limited and controversial. This study is aimed at investigating the association of serum Hcy with all-cause and cardiovascular mortality in diabetic patients.

Methods

Serum Hcy was measured among 2,286 adults with type 2 diabetes in NHANES 1999-2006. Cox proportional hazard regression was used to estimate hazard ratios (HR) and 95% CIs for the association of Hcy with all-cause and cause-specific mortality.

Results

Over a median follow-up of 11.0 (interquartile range, 8.9-13.4) years, 952 of the 2286 patients with diabetes died, covering 269 (28.3%) cardiovascular deaths and 144 (15.2%) cancer deaths. Restricted cubic spline showed the linear relationship between Hcy and all-cause mortality risk. After multivariate adjustment, higher serum Hcy levels were independently associated with increased risk of all-cause and cardiovascular mortality. Compared with participants in the bottom tertile of Hcy, the multivariate-adjusted HRs and 95% CI for participants in the top quartile were 2.33 (1.64-3.30) for all-cause mortality (p_trend < 0.001), 2.24 (1.22-4.10) for CVD mortality (p_trend = 0.017), and 2.05 (0.90-4.69) for cancer mortality (p_trend = 0.096). The association with total mortality was especially stronger among patients with albuminuria. Serum Hcy significantly improved reclassification for 10-year mortality in diabetic patients (net reclassification index = 0.253 and integrated discrimination improvement = 0.011).

Conclusions

Serum Hcy was associated with risks of all-cause and cardiovascular mortality in diabetic adults. Our results suggested that Hcy was a promising biomarker in risk stratification among diabetic patients.

Genome-wide associations of aortic distensibility suggest causality for aortic aneurysms and brain white matter hyperintensities

Aortic dimensions and distensibility are key risk factors for aortic aneurysms and dissections, as well as for other cardiovascular and cerebrovascular diseases. We present genome-wide associations of ascending and descending aortic distensibility and area derived from cardiac magnetic resonance imaging (MRI) data of up to 32,590 Caucasian individuals in UK Biobank. We identify 102 loci (including 27 novel associations) tagging genes related to cardiovascular development, extracellular matrix production, smooth muscle cell contraction and heritable aortic diseases. Functional analyses highlight four signalling pathways associated with aortic distensibility (TGF-β, IGF, VEGF and PDGF). We identify distinct sex-specific associations with aortic traits. We develop co-expression networks associated with aortic traits and apply phenome-wide Mendelian randomization (MR-PheWAS), generating evidence for a causal role for aortic distensibility in development of aortic aneurysms. Multivariable MR suggests a causal relationship between aortic distensibility and cerebral white matter hyperintensities, mechanistically linking aortic traits and brain small vessel disease.

The Protective Effects of Acetazolamide Against Homocysteine-Induced Blood-Brain-Barrier Disruption by Regulating the Activation of the Wnt/β-Catenin Signaling Pathway

Acetazolamide (AZA) is a carbonic anhydrase inhibitor (CAI) with neuroprotective effects. Hyperhomocysteinemia is associated with blood-brain-barrier (BBB) disruption in brain disorders. A previous study indicated that AZA might have a new role in brain disorders. However, its function in hyperhomocysteinemia-related BBB disruption has not been reported. Here, we aim to clarify the role of AZA in homocysteine (Hcy)-mediated BBB dysfunction using both in vivo and in vitro assays. We found that AZA improved memory and cognitive function, and reduced brain edema in Hcy-stimulated hyperhomocysteinemia model rats. This protective effect of AZA on hyperhomocysteinemia rats was accompanied by improved BBB permeability and increased expression levels of the tight junction proteins, occludin, and claudin-5. The in vitro assay results show that AZA prevented Hcy-induced cell injury and attenuated the increased permeability in Hcy-treated bEnd.3 brain endothelial cells. The Hcy-induced decrease in occludin and claudin-5, and increase in MMP-2 and MMP-9 expression levels were attenuated by AZA in bEnd.3 cells. Moreover, the Hcy-induced downregulation of the Wnt/β-catenin signaling pathway in bEnd.3 cells was abolished by AZA. Inhibition of Wnt/β-catenin by ICG-001 reversed the protective effects of AZA in Hcy-treated bEnd.3 cells. We also prove that this process is mediated by WTAP. These findings suggest that acetazolamide mitigated the Hcy-induced compromised brain vascular endothelial integrity by regulating the activation of the Wnt/β-catenin signaling pathway.

Homocysteine-targeting compounds as a new treatment strategy for diabetic wounds via inhibition of the histone methyltransferase SET7/9

In hypoxia and hyperglycemia, SET7/9 plays an important role in controlling HIF-1α methylation and regulating the transcription of HIF-1α target genes, which are responsible for angiogenesis and wound healing. Here, we report the Ir(III) complex Set7_1a bearing acetonitrile (ACN) ligands as a SET7/9 methyltransferase inhibitor and HIF-1α stabilizer. Interestingly, Set7_1a could engage SET7/9 and strongly inhibit SET7/9 activity, especially after preincubation with homocysteine (Hcy), which is elevated in diabetes. We hypothesize that Set7_1a exchanges ACN subunits for Hcy to disrupt the interaction between SET7/9 and SAM/SAH, which are structurally related to Hcy. Inhibition of SET7/9 methyltransferase activity by Set7_1a led to reduced HIF-1α methylation at the lysine 32 residue, causing increased HIF-1α level and recruitment of HIF-1α target genes that promote angiogenesis, such as VEGF, GLUT1, and EPO, in hypoxia and hyperglycemia. Significantly, Set7_1a improved wound healing in a type 2 diabetic mouse model by activating HIF-1α signaling and downstream proangiogenic factors. To our knowledge, this is the first Hcy-targeting iridium compound shown to be a SET7/9 antagonist that can accelerate diabetic wound healing. More importantly, this study opens a therapeutic avenue for the treatment of diabetic wounds by the inhibition of SET7/9 lysine methyltransferase activity.

Animal trials have demonstrated the potential of a new drug strategy to heal the wounds associated with diabetes, especially in the feet,which often lead to chronic damage, sometimes treatable only by amputation. Leung CH and Lin L at the University of Macau, China, and Ma DL at the Hong Kong Baptist University tested the new therapy on a mouse model of type 2 diabetes. The treatment uses a homocysteine-targeting metal complex that inhibits a key enzyme SET7/9 involved in the processes that cause diabetic wounds. The treatment activated a molecular signalling cascade involved in generating the new blood vessels needed for wounds to heal. It could help address the urgent need for better treatments for this serious problem.

Metabolic Changes Induced by Cerebral Ischemia, the Effect of Ischemic Preconditioning, and Hyperhomocysteinemia

1H Nuclear Magnetic Resonance (NMR) metabolomics is one of the fundamental tools in the fast-developing metabolomics field. It identifies and quantifies the most abundant metabolites, alterations of which can describe energy metabolism, activated immune response, protein synthesis and catabolism, neurotransmission, and many other factors. This paper summarizes our results of the 1H NMR metabolomics approach to characterize the distribution of relevant metabolites and their alterations induced by cerebral ischemic injury or its combination with hyperhomocysteinemia in the affected tissue and blood plasma in rodents. A decrease in the neurotransmitter pool in the brain tissue likely follows the disordered feasibility of post-ischemic neurotransmission. This decline is balanced by the increased tissue glutamine level with the detected impact on neuronal health. The ischemic injury was also manifested in the metabolomic alterations in blood plasma with the decreased levels of glycolytic intermediates, as well as a post-ischemically induced ketosis-like state with increased plasma ketone bodies. As the 3-hydroxybutyrate can act as a likely neuroprotectant, its post-ischemic increase can suggest its supporting role in balancing ischemic metabolic dysregulation. Furthermore, the 1H NMR approach revealed post-ischemically increased 3-hydroxybutyrate in the remote organs, such as the liver and heart, as well as decreased myocardial glutamate. Ischemic preconditioning, as a proposed protective strategy, was manifested in a lower extent of metabolomic changes and/or their faster recovery in a longitudinal study. The paper also summarizes the pre- and post-ischemic metabolomic changes in the rat hyperhomocysteinemic models. Animals are challenged with hyperglycemia and ketosis-like state. A decrease in several amino acids in plasma follows the onset and progression of hippocampal neuropathology when combined with ischemic injury. The 1H NMR metabolomics approach also offers a high potential for metabolites in discriminatory analysis in the search for potential biomarkers of ischemic injury. Based on our results and the literature data, this paper presents valuable findings applicable in clinical studies and suggests the precaution of a high protein diet, especially foods which are high in Met content and low in B vitamins, in the possible risk of human cerebrovascular neuropathology.

Prevalence of hyperhomocysteinemia (HHcy) and its major determinants among hypertensive patients over 35 years of age

OBJECTIVE

Hyperhomocysteinemia (HHcy) and hypertension are associated with cardiovascular events. However, effects of Hcy-lowing interventions on cardiovascular outcome were conflicting. Serum folate level was proposed to be a possible determinant of efficacy of extra folate supplementation on cardiovascular outcome. The aims of the present study were to describe representative information on the levels of serum homocysteine and folate in hypertensive patients, and to explore the major determinants of HHcy.

METHODS

11,007 participants with hypertension were analyzed in this cross-sectional study. Blood pressure and serum levels of biochemical indicators were measured. Multivariate logistic regression model was used to assess the associated factors of HHcy.

RESULTS

Geometric mean of serum total homocysteine was 14.1 (95% CI: 13.9, 14.4) μmol/L and prevalence of HHcy was 36.1 (95% CI: 34.0, 38.1) % in hypertensive patients. HHcy was strongly associated with factors including male sex, older age, elevated serum creatinine (SCr), lower serum folate and vitamin B12, and uncontrolled blood pressure in hypertensive patients. Elevated SCr attributed to HHcy with the etiologic fraction of 0.29. The change of the odds ratio of HHcy associated with folate was significantly higher in patients with elevated SCr compared with that of patients with normal SCr.

CONCLUSION

The results suggested the protection of female sex and higher levels of folate and vitamin B12 from HHcy and attribution of older age and elevated SCr to HHcy. Restoring renal function deserved attention for hypertensive patients to benefit from Hcy-lowing measures.

Cortical Short-Range Fiber Connectivity and Its Association With Deep Brain White Matter Hyperintensities in Older Diabetic People With Low Serum Vitamin B12

Although previous studies have indicated that older people with diabetes mellitus (DM) had an approximately two times larger white matter hyperintensity (WMH) load than those without DM, the influence of WMHs on cognition is uncertain and inconsistent in the literature. It is unclear whether the short-range fibers in the juxtacortical region, traditionally considered to be spared from WMH pathology, are enhanced as an adaptive response to deep WM degeneration in older diabetic people with normal cognition. Moreover, the specific effect of vitamin B₁₂ deficiency, commonly accompanied by DM, remains to be investigated. This study implemented a specialized analysis of the superficial cortical short-range fiber connectivity density (SFiCD) based on a data-driven framework in 70 older individuals with DM and low serum vitamin B₁₂. Moreover, the effects of time and vitamin B₁₂ supplementation were assessed based on a randomized placebo-controlled trial in 59 individuals. The results demonstrated a higher SFiCD in diabetic individuals with a higher deep WMH load. Additionally, a significant interaction between DWMH load and homocysteine on SFiCD was found. During the 27-month follow-up period, a longitudinal increase in the SFiCD was observed in the bilateral frontal cortices. However, the observed longitudinal SFiCD change was not dependent on vitamin B₁₂ supplementation; thus, the specific reason for the longitudinal cortical short fiber densification may need further study. Overall, these findings may help us better understand the neurobiology of brain plasticity in older patients with DM, as well as the interplay among DM, WMH, and vitamin B₁₂ deficiency.

Revealing the Phase Separation in ER Membranes of Living Cells and Tissues by In Situ NIR Ratiometric Imaging

Biomembranes in the endoplasmic reticulum (ER) play indispensable roles in various bioactivities, and therefore, visualizing the phase separation in ER membranes is crucial for the studies on the fundamental biology of the ER. However, near-infrared (NIR) ratiometric imaging of the phase behaviors of the ER in living cells with different statuses and in diverse tissues has not been investigated. Herein, we developed a polarity-responsive NIR fluorescent probe (DCA) for the visualization of the phase behavior in ER membranes. The probe displayed a large Stokes shift and was highly sensitive to polarity. By direct and native fluorescence imaging at room temperature, the ER_o and ER_d biomembranes in the ER could be clearly distinguished by dual NIR emission colors. Oxidative damage by H₂O₂ and homocystein (Hcy)-induced ER stress can efficiently induce the formation of large-scale ER_o domains in ER membranes. Moreover, we have also revealed that different tissues exhibited diverse phase behaviors in the ER membranes. The ER membranes in cardiac and skeletal muscle tissues showed no evident phase separation, while large-scale ER_o domains existed in the ER of liver tissues and formed at the ER membranes adjacent to lipid droplets (LDs) in white adipose tissues. We expect that the probe could serve as a powerful molecular tool to promote fundamental research studies on ER membranes and relative biomedical areas.

RESEARCH OF INDICATORS OF OXIDATIVE STRESS IN THE KIDNEYS OF IMMATURE RATS WITH HYPERHOMOCYSTEINEMIA

Purpose: Hyperhomocysteinemia in children can develop as a result of genetic defects, endocrine abnormalities or under the influence of dietary factors. An elevated level of homocysteine is considered a risk factor for the progression of chronic kidney disease. The aim of the work was to investigate the indicators of oxidative stress in the homogenate of the kidneys of immature rats in control and with hyperhomocysteinemia. Methods: The concentration of reduced and oxidized glutathione, the activity of superoxide dismutase, catalase and nitric oxide synthase were determined. The model of hyperhomocysteinemia was reproduced on one-month-old male rats, which were kept on a standard vivarium diet. The experimental group was intragastrically administered by D,L-thiolactone homocysteine hydrochloride in a 1% starch solution at a dose of 200 mg/kg of body weight 1 per day for 8 weeks. The corresponding volume of 1% starch solution was injected into the control group of animals. The activity of superoxide dismutase, catalase and nitric oxide synthase were determined spectrophotometrically. Concentration of reduced and oxidized glutathione by fluorometric method. Results: It was established that upon hyperhomocysteinemia the concentration of reduced glutathione, the activity of superoxide dismutase, catalase, and nitric oxide synthase was decreased against the background of an increase in the concentration of oxidized glutathione in the homogenate of the kidneys of immature rats. Conclusions: The obtained results indicate that in the kidneys of immature rats, the development of oxidative stress occurs in the direction characteristic of adult animals. The obtained results indicate that in the kidneys of immature rats the development of oxidative stress resembles the adult animals. The obtained results showed a decrease in the concentration of reduced glutathione and the activity of antioxidant defense enzymes which may indicate the development of pathological processes in the kidneys

The Influence of MTHFR Polymorphism on Gray Matter Volume in Patients With Amnestic Mild Cognitive Impairment

The methylenetetrahydrofolate reductase (MTHFR) gene has been associated with Alzheimer's disease (AD) pathogenesis. Amnestic mild cognitive impairment (aMCI) represents a prodromal stage of dementia and involves a high risk of progression into AD. Although the effects of the apolipoprotein E (APOE) gene on structural alterations in aMCI have been widely investigated, the effects of MTHFR C677T and interaction effects of MTHFR × APOE genotypes on gray matter atrophy in aMCI remain largely unknown. In the present study, 60 aMCI patients and 30 healthy controls were enrolled, and voxel-based morphometry analysis was performed to inspect the effects of diagnosis, different genotypes, and their interactions on gray matter atrophy. The results showed that aMCI patients had significant gray matter atrophy involving the bilateral hippocampus, the right parahippocampal gyrus, and the left superior temporal gyrus compared with healthy controls. Besides, a substantial reduction in gray matter volume was observed in the right hippocampus region in APOE ε4 carriers from the aMCI group, compared with APOE ε4 non-carriers. A significant interaction was found between diagnosis and MTHFR C677T genotype on the right precuneus in healthy controls and aMCI patients not carrying APOE ε4 allele. Our findings may provide new evidence substantiating the genetic effects of MTHFR C677T on brain structural alternation in patients with aMCI.

CRIF1 Deficiency Increased Homocysteine Production by Disrupting Dihydrofolate Reductase Expression in Vascular Endothelial Cells

Elevated plasma homocysteine levels can induce vascular endothelial dysfunction; however, the mechanisms regulating homocysteine metabolism in impaired endothelial cells are currently unclear. In this study, we deleted the essential mitoribosomal gene CR6 interacting factor 1 (CRIF1) in human umbilical vein endothelial cells (HUVECs) and mice to induce endothelial cell dysfunction; then, we monitored homocysteine accumulation. We found that CRIF1 downregulation caused significant increases in intracellular and plasma concentrations of homocysteine, which were associated with decreased levels of folate cycle intermediates such as 5-methyltetrahydrofolate (MTHF) and tetrahydrofolate (THF). Moreover, dihydrofolate reductase (DHFR), a key enzyme in folate-mediated metabolism, exhibited impaired activity and decreased protein expression in CRIF1 knockdown endothelial cells. Supplementation with folic acid did not restore DHFR expression levels or MTHF and homocysteine concentrations in endothelial cells with a CRIF1 deletion or DHFR knockdown. However, the overexpression of DHFR in CRIF1 knockdown endothelial cells resulted in decreased accumulation of homocysteine. Taken together, our findings suggest that CRIF1-deleted endothelial cells accumulated more homocysteine, compared with control cells; this was primarily mediated by the disruption of DHFR expression.

GPX7 Facilitates BMSCs Osteoblastogenesis via ER Stress and mTOR Pathway

Emerging evidence indicates extensive oxidative stress is a consequence of obesity which impairs bone formation. Glutathione peroxidase 7 (GPX7) is a conserved endoplasmic reticulum (ER) retention protein, lacking of which causes accumulation of reactive oxygen species (ROS) and promotes adipogenesis. Since the imbalance between osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cell (BMSC) leads to severe bone diseases such as osteoporosis, it is critical to investigate the potential protective role of Gpx7 in osteogenesis. Here, we provide evidence that deficiency of Gpx7 reduces osteogenesis, but increases adipogenesis in both human BMSCs (hBMSCs) and mouse mesenchymal stem cell line. Interestingly, further studies indicate this defect can be alleviated by the ER stress antagonist, but not the ROS inhibitor, unveiling an unexpected finding that, unlike adipogenesis, lacking of Gpx7 inhibits osteogenesis mediating by induced ER stress instead of enhanced ROS. Furthermore, the mTOR signalling pathway is found down‐regulation during osteogenic differentiation in Gpx7‐deficient condition, which can be rescued by relief of ER stress. Taken together, for the first time we identify a novel function of Gpx7 in BMSCs’ osteogenic differentiation and indicate that Gpx7 may protect against osteoporotic deficits in humans through ER stress and mTOR pathway interplay.

Sestrin2 suppression aggravates oxidative stress and apoptosis in endothelial cells subjected to pharmacologically induced endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress is an inflammatory response that contributes to endothelial cell dysfunction, a hallmark of cardiovascular diseases, in close interplay with oxidative stress. Recently, Sestrin2 (SESN2) emerged as a novel stress-inducible protein protecting cells from oxidative stress. We investigated here, for the first time, the impact of SESN2 suppression on oxidative stress and cell survival in human endothelial cells subjected to pharmacologically (thapsigargin)-induced ER stress and studied the underlying cellular pathways. We found that SESN2 silencing, though did not specifically induce ER stress, it aggravated the effects of thapsigargin-induced ER stress on oxidative stress and cell survival. This was associated with a dysregulation of Nrf-2, AMPK and mTORC1 signaling pathways. Furthermore, SESN2 silencing aggravated, in an additive manner, apoptosis caused by thapsigargin. Importantly, SESN2 silencing, unlike thapsigargin, caused a dramatic decrease in protein expression and phosphorylation of Akt, a critical pro-survival hub and component of the AMPK/Akt/mTORC1 axis. Our findings suggest that patients with conditions characterized by ER stress activation, such as diabetes, may be at higher risk for cardiovascular complications if their endogenous ability to stimulate and/or maintain expression levels of SESN2 is disturbed or impaired. Therefore, identifying novel or repurposing existing pharmacotherapies to enhance and/or maintain SESN2 expression levels would be beneficial in these conditions.

Nonocular Influencing Factors for Primary Glaucoma: An Umbrella Review of Meta-Analysis

INTRODUCTION

Glaucoma is the main cause of irreversible blindness worldwide. Still, little is known about nonocular risk factors. We use an umbrella review to examine the meta-analytic evidence of the correlation between nonocular factors and glaucoma.

METHOD

We searched PubMed and Embase databases up to July 24, 2020. Eligible meta-analyses (MAs) included cohort, case-control, and randomized controlled study designs. Two authors independently extracted the data and evaluated the methodological quality of the MAs. AMSTAR 2 was used to assess the methodological quality of each included MA.

RESULTS

This umbrella review contains 22 MAs with 22 unique nonocular factors in total. We identified 11 factors that increase the risk of glaucoma: hyperlipidemia, nocturnal dip in blood pressure, infection with Helicobacter pylori, myopia, obstructive sleep apnea syndrome, corneal properties, diabetes, hypertension, hypothyroidism, migraine, and plasma homocysteine. We identified 3 factors that reduce the risk of glaucoma: dietary intake of vitamin A, dietary intake of vitamin C, and short-term statin use. We identified 8 factors that had no association with glaucoma: dietary intake of vitamin B, dietary intake of vitamin E, cigarette smoking, Alzheimer's disease, serum folic acid, serum vitamin B6, serum vitamin B12, and serum vitamin D.

CONCLUSIONS

In this umbrella review of MAs, evidence was found for associations of various nonocular factors with glaucoma to different degrees. However, risk factors were only mildly associated, suggesting low impact of systemic risk factors. Additional higher quality studies are needed to provide robust evidence.

The regulation of Ero1-alpha in homocysteine-induced macrophage apoptosis and vulnerable plaque formation in atherosclerosis

BACKGROUND AND AIMS

Hyperhomocysteinemia (HHcy) is an independent risk factor for atherosclerosis and plaque vulnerability. Macrophage apoptosis mediated by endoplasmic reticulum (ER) stress plays an important role in the pathogenesis of HHcy-aggravated atherosclerosis. Endoplasmic reticulum oxidoreductase 1α (Ero1α) is critical for ER stress-induced apoptosis. We hypothesized that Ero1α may contribute to ER-stress induced macrophage apoptosis and plaque stability in advanced atherosclerotic lesions by HHcy.

METHODS

Apoe^-/- mice were maintained on drinking water containing homocysteine (Hcy, 1.8 g/L) to establish HHcy atherosclerotic models. The role of Ero1α in atherosclerotic plaque stability, macrophage apoptosis and ER stress were monitored in the plaque of aortic roots in HHcy Apoe^-/- mice with or without silence or overexpression of Ero1α through lentivirus. Mouse peritoneal macrophages were used to confirm the regulation of Ero1α on ER stress dependent apoptosis in the presence of HHcy.

RESULTS

Atherosclerotic plaque vulnerability and macrophage apoptosis were promoted in Apoe^-/- mice by high Hcy diet, accompanied by the upregulation of Ero1α expression and ER stress. Inhibition of Ero1α prevented macrophage apoptosis and atherosclerotic plaque vulnerability, and vice versa. Consistently, in mouse peritoneal macrophages, ER stress and apoptosis were attenuated by Ero1α deficiency, but enhanced by Ero1α overexpression.

CONCLUSIONS

Hcy, via upregulation of Ero1α expression, activates ER stress-dependent macrophage apoptosis to promote vulnerable plaque formation in atherosclerosis. Ero1α may be a potential therapeutic target for atherosclerosis induced by Hcy.

Current Status of Endoplasmic Reticulum Stress in Type II Diabetes

The endoplasmic reticulum (ER) plays a multifunctional role in lipid biosynthesis, calcium storage, protein folding, and processing. Thus, maintaining ER homeostasis is essential for cellular functions. Several pathophysiological conditions and pharmacological agents are known to disrupt ER homeostasis, thereby, causing ER stress. The cells react to ER stress by initiating an adaptive signaling process called the unfolded protein response (UPR). However, the ER initiates death signaling pathways when ER stress persists. ER stress is linked to several diseases, such as cancer, obesity, and diabetes. Thus, its regulation can provide possible therapeutic targets for these. Current evidence suggests that chronic hyperglycemia and hyperlipidemia linked to type II diabetes disrupt ER homeostasis, thereby, resulting in irreversible UPR activation and cell death. Despite progress in understanding the pathophysiology of the UPR and ER stress, to date, the mechanisms of ER stress in relation to type II diabetes remain unclear. This review provides up-to-date information regarding the UPR, ER stress mechanisms, insulin dysfunction, oxidative stress, and the therapeutic potential of targeting specific ER stress pathways.