Endothelial nitric oxide synthase enhancer AVE3085 reverses endothelial dysfunction induced by homocysteine in human internal mammary arteries

Homocysteine impairs the anticontractile/vasorelaxing activity of perivascular adipose tissue surrounding human internal mammary artery

OBJECTIVES

Perivascular adipose tissue (PVAT) surrounding human internal mammary artery (IMA) possesses anticontractile property. Its function under pathological conditions is barely studied. We previously reported that homocysteine impairs the vasodilator function of IMA through endothelium and smooth muscle-dependent mechanisms. This study investigated the effect of homocysteine on the function of PVAT and the associated mechanisms.

METHODS

Residual IMA tissues were collected from patients undergoing coronary artery bypass grafting. Vasoreactivity was studied using myograph. Adiponectin was measured by ELISA. Expressions of adiponectin receptors (AdipoRs), eNOS and p-eNOS were determined by RT-qPCR and Western blot.

RESULTS

Exposure to homocysteine augmented the contractile responses of PVAT-intact IMA to U46619 and potassium chloride, regardless with or without endothelium. Such augmentation was also observed in skeletonized IMA with transferred, homocysteine-exposed PVAT. Homocysteine attenuated the relaxant response of PVAT-intact while endothelium-denuded vessels to acetylcholine. Homocysteine lowered adiponectin content in the PVAT, downregulated the expression of AdipoR1 and AdipoR2 as well as eNOS and p-eNOS in skeletonized IMA. The relaxant response of skeletonized IMA to AdipoR agonist AdipoRon was blunted by homocysteine or eNOS inhibitor, and homocysteine significantly attenuated the inhibitory effect of eNOS inhibitor on AdipoRon-induced relaxation.

CONCLUSIONS

Homocysteine impairs the anticontractile/vasorelaxing activity of PVAT surrounding the IMA through inhibiting adiponectin/AdipoR/eNOS/nitric oxide signalling pathway.

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.).

Correlation Analysis and Diagnostic Value of Serum Homocysteine, Cystatin C and Uric Acid Levels with the Severity of Coronary Artery Stenosis in Patients with Coronary Heart Disease

Background

Coronary angiography (CAG) is an invasive examination with high risks and costs and various complications may occur. It is necessary to find a diagnostic method, non-invasiveness, inexpensive with low risk. This study aims to analyze the correlation between the levels of serum homocysteine (Hcy), cystatin C (Cys C) and uric acid (UA) and Gensini score in patients with coronary heart disease (CHD) and assess their diagnostic value for CHD.

Methods

A retrospective analysis was conducted on 1412 patients underwent CAG from October 2019 to December 2021, and we conducted this study from January to July 2022. A total of 765 patients with CHD confirmed by CAG were selected as the research group, while 647 patients revealed as non-obstructive stenosis by CAG as the control group. The serum Hcy, Cys C and UA levels were detected and the correlation between Gensini score and variables was analyzed. The receiver-operating characteristic (ROC) curve was performed to assess the diagnostic value of the Hcy, Cys C and UA for CHD.

Results

The serum Hcy, Cys C and UA levels in the research group were higher as compared with the control group (p<0.05). Spearman correlation and multivariate linear regression analysis showed that there was a significantly positive correlation between Gensini score and serum Hcy, Cys C and UA levels (p<0.05). The ROC curve analysis presented the combined Hcy and Cys C with UA having the highest specificity of diagnostic value for CHD (area under the curve (AUC)=0.768, 95% CI 0.706-0.823, specificity = 72.34%, sensitivity = 67.88%, Youden Index = 0.4022).

Conclusion

The serum Hcy, Cys C and UA levels in patients with CHD were significantly increased, positive correlation with Gensini score. The combined Hcy and Cys C with UA could be used to assess the severity of coronary artery stenosis and provide predictive and early intervention treatment values for CHD and a new way of diagnosing CHD, which is cheap, safe, effective and deserving of clinical application.

Highly Diluted Antibodies to eNOS Restore Endothelium Function in Aortic Rings From Hypertensive Rats

Background

Nitric oxide (NO) as a vaso- and cardio-protective agent could reduce vasomotor dysfunction in different cardiovascular diseases. One of the current therapeutics targeted at NO availability in the vascular wall are highly diluted antibodies to endothelial NO-synthase (eNOS). This drug has previously shown its endothelium-protective effect and effectiveness in reducing hypertension. Current study was dedicated to evaluate the direct impact of highly diluted antibodies to eNOS on the vessel constriction and dilation ex vivo.

Methods

For that purpose, we used thoracic aortas dissected from spontaneously hypertensive (SHR) rats. Endothelium-dependent relaxation in the presence of highly diluted antibodies to eNOS (1 mL) was examined after phenylephrine-induced pre-constriction of the aorta rings in response to gradually increased acetylcholine concentration (1 nM to 10 µM).

Results

Highly diluted antibodies to eNOS enhanced acetylcholine-induced relaxation in a statistically significant manner. Moreover, it was demonstrated that observed effect was similar to perindopril, a well-known angiotensin-converting-enzyme inhibitor, which works through relaxing and widening blood vessels.

Conclusions

Our findings indicate that highly diluted antibodies to eNOS restored impaired endothelium function, as demonstrated by increased relaxation of SHR rats aorta rings. The revealed results suggest beneficial effect of highly diluted antibodies to eNOS to ameliorate hypertension and related diseases.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1β monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Homocysteine alters vasoreactivity of human internal mammary artery by affecting the KCa channel family

Background

Hyperhomocysteinemia is an independent risk factor for atherosclerotic heart disease. We previously demonstrated that disruption of calcium-activated potassium (K_Ca) channel activity is involved in homocysteine-induced dilatory dysfunction of porcine coronary arteries. Recently we reported that the K_Ca channel family, including large-, intermediate-, and small-conductance K_Ca (BK_Ca, IK_Ca, and SK_Ca) subtypes, are abundantly expressed in human internal mammary artery (IMA). In this study, we further investigated whether homocysteine affects the expression and functionality of the K_Ca channel family in this commonly used graft for coronary artery bypass surgery (CABG).

Methods

Residual IMA segments obtained from patients undergoing CABG were studied in a myograph for the role of K_Ca subtypes in both vasorelaxation and vasoconstriction. The expression and distribution of K_Ca subtypes were detected by Western blot and immunohistochemistry.

Results

Both the BK_Ca channel activator NS1619 and the IK_Ca/SK_Ca channel activator NS309 evoked significant IMA relaxation. Homocysteine exposure suppressed NS1619-induced relaxation whereas showed no influence on NS309-induced response. Blockade of BK_Ca but not IK_Ca and SK_Ca subtypes significantly suppressed acetylcholine-induced relaxation and enhanced U46619-induced contraction. Homocysteine compromised the vasodilating activity of the BK_Ca subtype in IMA, associated with a lowered protein level of the BK_Ca β1-subunit. Homocysteine potentiated the role of IK_Ca and SK_Ca subtypes in mediating endothelium-dependent relaxation without affecting the expression of these channels.

Conclusions

Homocysteine reduces the expression of BK_Ca β1-subunit and compromises the vasodilating activity of BK_Ca channels in IMA. Unlike BK_Ca, IK_Ca and SK_Ca subtypes are unessential for IMA vasoregulation, whereas the loss of BK_Ca functionality in hyperhomocysteinemia enhances the role of IK_Ca and SK_Ca subtypes in mediating endothelial dilator function. Targeting BK_Ca channels may form a strategy to improve the postoperative graft performance in CABG patients with hyperhomocysteinemia who receive IMA grafting.

Antiseptic mouthwash, the nitrate-nitrite-nitric oxide pathway, and hospital mortality: a hypothesis generating review

Meta-analyses and several large cohort studies have demonstrated that antiseptic mouthwashes are associated with mortality in hospitalized patients. A clear pathogenic mechanism is lacking, leading to controversy and a reluctance to abandon or limit the use of antiseptic mouthwashes. Here, we generate the hypothesis that a disturbance in nitric oxide homeostasis by antiseptic mouthwashes may be responsible for the observed increase in mortality risk. Nitric oxide is essential in multiple physiological processes, and a reduction in nitric oxide bioavailability is associated with the occurrence or worsening of pathologies, such as atherosclerosis, diabetes, and sepsis. Oral facultative anaerobic bacteria are essential for the enterosalivary nitrate–nitrite–nitric oxide pathway due to their capacity to reduce nitrate to nitrite. Nitrate originates from dietary sources or from the active uptake by salivary glands of circulating nitrate, which is then excreted in the saliva. Because antiseptic mouthwashes eradicate the oral bacterial flora, this nitric oxide-generating pathway is abolished, which may result in nitric oxide-deficient conditions potentially leading to life-threatening complications such as ischaemic heart events or sepsis.

Serum adenosine deaminase activity and coronary artery disease: a retrospective case-control study based on 9929 participants

Background:

Adenosine deaminase (ADA) regulates purine metabolism through the conversion of adenosine to uric acid (UA). Adenosine and UA are closely associated with cardiovascular events, but the correlation between serum ADA activity and coronary artery disease (CAD) has not been defined.

Methods:

We performed a hospital-based retrospective case-control study that included a total of 5212 patients with CAD and 4717 sex- and age-matched controls. The serum activity of ADA was determined by peroxidase assays in an automatic biochemistry analyzer.

Results:

Serum ADA activity in the CAD group (10.08 ± 3.57 U/l) was significantly lower than that of the control group (11.71 ± 4.20 U/l, p < 0.001). After adjusting for conventional factors, serum ADA activity negatively correlated with the presence of CAD (odds ratio = 0.852, 95% confidence interval: 0.839–0.865, p < 0.001). Among the patients with CAD, serum ADA activity was lowest in patients with myocardial infarction (MI; 9.77 ± 3.80 U/l). Diabetes mellitus and hypertension increased the serum ADA activity in CAD patients.

Conclusions:

Serum ADA activity is significantly attenuated in patients with CAD, particularly in MI. We propose a mechanism by which the body maintains adenosine levels to protect the cardiovascular system in the event of CAD.

Calcium-activated potassium channel family in coronary artery bypass grafts

OBJECTIVES

We examined the expression, distribution, and contribution to vasodilatation of the calcium-activated potassium (K_Ca) channel family in the commonly used coronary artery bypass graft internal thoracic artery (ITA) and saphenous vein (SV) to understand the role of large conductance K_Ca (BK_Ca), intermediate-conductance K_Ca (IK_Ca), and small-conductance K_Ca (SK_Ca) channel subtypes in graft dilating properties determined by endothelium-smooth muscle interaction that is essential to the postoperative performance of the graft.

METHODS

Real-time polymerase chain reaction and western blot were employed to detect the messenger RNA and protein level of K_Ca channel subtypes. Distribution of K_Ca channel subtypes was examined by immunohistochemistry. K_Ca subtype-mediated vasorelaxation was studied using wire myography.

RESULTS

Both ITA and SV express all K_Ca channel subtypes with each subtype distributed in both endothelium and smooth muscle. ITA and SV do not differ in the overall expression level of each K_Ca channel subtype, corresponding to comparable relaxant responses to respective subtype activators. In ITA, BK_Ca is more abundantly expressed in smooth muscle than in endothelium, whereas SK_Ca exhibits more abundance in the endothelium. In comparison, SV shows even distribution of K_Ca channel subtypes in the 2 layers. The BK_Ca subtype in the K_Ca family plays a significant role in vasodilatation of ITA, whereas its contribution in SV is quite limited.

CONCLUSIONS

K_Ca family is abundantly expressed in ITA and SV. There are differences between these 2 grafts in the abundance of K_Ca channel subtypes in the endothelium and the smooth muscle. The significance of the BK_Ca subtype in vasodilatation of ITA may suggest the potential of development of BK_Ca modulators for the prevention and treatment of ITA spasm during/after coronary artery bypass graft surgery.

Vardenafil and cilostazol can improve vascular reactivity in rats with diabetes mellitus and rheumatoid arthritis co-morbidity

Endothelial dysfunction and vascular reactivity defects secondary to metabolic and immunological disorders carry risk of serious cardiovascular complications. Here, the effects of the phosphodiesterase (PDE) inhibitors vardenafil and cilostazol were examined against rheumatoid arthritis (RA)/diabetes mellitus (DM)-co-morbidity-induced endothelial dysfunction and vascular reactivity defects. After setting of RA/DM-co-morbidity model, rats were divided into a normal control group, an RA/DM-co-morbidity group, and two treatment groups receiving oral vardenafil (10 mg/kg/day) and cilostazol (30 mg/kg/day) for 21 days after RA/DM-co-morbidity induction. Aorta was isolated for biochemical estimations of the pro-inflammatory vasoconstrictor molecules angiotensin-II (Ang-II) and endothelin-1 (ET-1), the adhesion molecules P-selectin and vascular cell adhesion molecule-1 (VCAM-1), the energy sensor adenosine-5'-monophosphate-activated protein kinase (AMPK), and the vasodilator anti-inflammatory molecule vasoactive intestinal peptide (VIP) using enzyme-linked immunosorbent assay (ELISA) and western blot analysis. Immunohistochemical estimations of endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase (MMP)-2 were performed coupled with histopathological examination using routine hematoxylin and eosin (H&E) and special Masson trichrome staining. The in vitro study was conducted using aortic strips where cumulative concentration response curves were done for the endothelium-dependent relaxing factor acetylcholine and the endothelium-independent relaxing factor sodium nitroprusside after submaximal contraction with phenylephrine. Vardenafil and cilostazol significantly improved endothelial integrity biomarkers in vivo supported with histopathological findings in addition to improved vasorelaxation in vitro. Apart from their known PDE inhibition, up-regulation of vascular AMPK and eNOS coupled with down-regulation of Ang-II, ET-1, P-selectin, VCAM-1 and MMP-2 may explain vardenafil and cilostazol protective effect against RA/DM-co-morbidity-induced endothelial dysfunction and vascular reactivity defects.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.