Vasodilatory effect of nitroglycerin in Japanese subjects with different aldehyde dehydrogenase 2 (ALDH2) genotypes

Relationship Between Aldehyde Dehydrogenase 2 Gene Polymorphism and Vasodilative Effect of Nitroglycerin on Coronary Arteries

ABSTRACT

Aldehyde dehydrogenase 2 (ALDH2) is a key enzyme that facilitates the biologic metabolism of nitroglycerin. However, no study investigated the association between ALDH2 gene polymorphism and the vasodilation of coronary arteries after intracoronary administration of nitroglycerin. In this study, we enrolled 427 patients with suspected angina pectoris. ALDH2 genotyping was performed and all patients were given 200 µg nitroglycerin in the right coronary artery during the coronary angiography. The invasive hemodynamic parameters including systolic blood pressure (SBP), diastolic blood pressure, and heart rate were monitored. The reference diameter and stenosis diameter of the right coronary artery were measured with the Stenosis Analysis 1.6 software. Both wild-type and mutant-type groups exhibited significant decreases in SBP, diastolic blood pressure values, and increases in heart rate value after administration of nitroglycerin ( P < 0.05). The wild-type group showed significantly higher absolute difference values in SBP than the mutant-type group ( P < 0.05). The mutant-type group exhibited significantly lower difference values and rates of change in reference diameter than the wild-type group [0.3 ± 0.3 vs. 0.5 ± 0.2, P < 0.001 for the difference value of diameter; 9.6 ± 9.5 vs. 15.8 ± 8.5, P < 0.001 for the rate of change (%)]. Conversely, no differences were observed between the wild-type and mutant-type groups in terms of the difference value and rate of change of the stenosis diameter ( P > 0.05). In conclusion, ALDH2 gene polymorphism (Glu504Lys) is associated with changes in invasive hemodynamic parameters and coronary artery diameter after intracoronary injection of nitroglycerin.

Efficacy and safety of Shexiang Baoxin Pill in patients with angina and non-obstructive coronary arteries: A multicenter, randomized, double-blind, placebo-controlled, phase Ⅳ clinical trial

INTRODUCTION

Solid evidence generated from large studies supporting the recommendation of Shexiang Baoxin Pill (MUSKARDIA) as a promising treatment for angina and nonobstructive coronary arteries (ANOCA) populations is lacking.

OBJECTIVE

To evaluate the efficacy and safety of MUSKARDIA in patients with ANOCA.

METHODS

In this randomized, double-blind, placebo-controlled, phase IV trial, we enrolled 239 patients with ANOCA at 11 centers across China between May 2021 and July 2023. Patients were randomly assigned in a 1:1 ratio to receive MUSKARDIA or placebo (orally 4 pills thrice daily) based on conventional treatment for 12 weeks. The primary endpoint was the change in angina-related outcomes, assessed using the Seattle Angina Questionnaire (SAQ) scores for the treatment groups at week 12.

RESULTS

Among 239 randomized patients with ANOCA, 236 (MUSKARDIA group, n = 117; placebo group, n = 119) completed treatment and endpoint assessments. At week 12, patients in the MUSKARDIA group showed better angina-related outcomes, with a more rapid increase in SAQ scores, than those in the placebo group (all p < 0.0001). Statistically significant differences favoring MUSKARDIA over placebo were observed for change in angina attack frequency compared with baseline at week 12 (p < 0.0001). Meanwhile, according to the Canadian Cardiovascular Society grading of angina, the change in angina pectoris severity, compared with baseline, was significantly reduced in MUSKARDIA group compared with placebo group at week 12 (p < 0.0001). The percentage of patients who did not use sublingual nitroglycerin was noticeably higher in MUSKARDIA group than that in placebo group (84.16 % vs. 58.33 %; p < 0.001). The incidence of adverse events did not differ significantly between the two groups, and no serious adverse events occurred.

CONCLUSION

This randomized, placebo-controlled clinical trial firstly confirmed that MUSKARDIA was an effective, safe, and well-tolerated treatment for patients with ANOCA in clinical settings. This study was registered at ClinicalTrials.gov (NCT04897126).

Advances in Factors Affecting ALDH2 Activity and its Mechanisms

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme primarily involved in the detoxification of alcohol-derived aldehyde and endogenous toxic aldehydes. It exhibits widespread expression across various organs and exerts a broad and significant impact on diverse acute cardiovascular diseases, including acute coronary syndrome, acute aortic dissection, hypoxic pulmonary hypertension, and heart failure. The ALDH2 rs671 variant represents the most prevalent genetic variant in East Asian populations, with carriage rates ranging from 30 to 50% among the Chinese population. Given its widespread presence in the body, the wide range of diseases it affects, and its high rate of variation, it can serve as a crucial tool for the precise prevention and treatment of acute cardiovascular diseases, while offering individualized medication guidance. This review aims to provide a comprehensive overview of the latest advancements in factors affecting ALDH2 activity, encompassing post-transcriptional modifications, modulators of ALDH2, and relevant clinical drugs.

The effect of vitamin C on nitroglycerin-mediated vasodilation in individuals with and without the aldehyde dehydrogenase 2 polymorphism

AIMS

To mediate its pharmacodynamic effects, glyceryl trinitrate (GTN) requires bioactivation, by which it releases nitric oxide or a nitric oxide moiety. The exact mechanism of GTN bioactivation remains uncertain. Mitochondrial aldehyde dehydrogenase (ALDH-2) has been proposed as the primary enzyme responsible for this bioactivation process. Evidence for the importance of ALDH-2 in GTN bioactivation has been inconsistent, particularly in human models. An alternative hypothesis suggests that decreased ALDH-2 activity leads to accumulation of reactive cytotoxic aldehydes, which either inhibit the vasoactive product(s) of GTN or impair other enzymatic pathways involved in the bioactivation of GTN. We investigated the effect of supplemental vitamin C on vascular responses to GTN in healthy volunteers of East Asian descent, of whom 12 with and 12 without the ALDH-2 polymorphism participated.

METHODS

Subjects underwent 2 sequential brachial artery infusions of GTN at rates of 5, 11 and 22 nmol/min, separated by a 30-min washout period. The GTN infusions were carried out in the presence and absence of vitamin C using a randomized, crossover design. Venous occlusion plethysmography was used to measure forearm blood flow responses to GTN.

RESULTS

Compared to subjects with functional ALDH-2, the variant group exhibited blunted hemodynamic responses to intra-arterial GTN infusions, although this reduction in response was not statically significant. Contrary to our hypothesis, vitamin C had an inhibitory effect on GTN mediated vasodilation as compared to GTN during saline in both groups.

CONCLUSION

We conclude that vitamin C did not augment the acute vascular response to GTN in those with the ALDH-2 polymorphism.

Nitroglycerin: a comprehensive review in cancer therapy

Nitroglycerin (NTG) is a prodrug that has long been used in clinical practice for the treatment of angina pectoris. The biotransformation of NTG and subsequent release of nitric oxide (NO) is responsible for its vasodilatating property. Because of the remarkable ambivalence of NO in cancer disease, either protumorigenic or antitumorigenic (partly dependent on low or high concentrations), harnessing the therapeutic potential of NTG has gain interest to improve standard therapies in oncology. Cancer therapeutic resistance remains the greatest challenge to overcome in order to improve the management of cancer patients. As a NO releasing agent, NTG has been the subject of several preclinical and clinical studies used in combinatorial anticancer therapy. Here, we provide an overview of the use of NTG in cancer therapy in order to foresee new potential therapeutic avenues.

The Generation of Nitric Oxide from Aldehyde Dehydrogenase-2: The Role of Dietary Nitrates and Their Implication in Cardiovascular Disease Management

Reduced bioavailability of the nitric oxide (NO) signaling molecule has been associated with the onset of cardiovascular disease. One of the better-known and effective therapies for cardiovascular disorders is the use of organic nitrates, such as glyceryl trinitrate (GTN), which increases the concentration of NO. Unfortunately, chronic use of this therapy can induce a phenomenon known as "nitrate tolerance", which is defined as the loss of hemodynamic effects and a reduction in therapeutic effects. As such, a higher dosage of GTN is required in order to achieve the same vasodilatory and antiplatelet effects. Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is a cardioprotective enzyme that catalyzes the bio-activation of GTN to NO. Nitrate tolerance is accompanied by an increase in oxidative stress, endothelial dysfunction, and sympathetic activation, as well as a loss of the catalytic activity of ALDH2 itself. On the basis of current knowledge, nitrate intake in the diet would guarantee a concentration of NO such as to avoid (or at least reduce) treatment with GTN and the consequent onset of nitrate tolerance in the course of cardiovascular diseases, so as not to make necessary the increase in GTN concentrations and the possible inhibition/alteration of ALDH2, which aggravates the problem of a positive feedback mechanism. Therefore, the purpose of this review is to summarize data relating to the introduction into the diet of some natural products that could assist pharmacological therapy in order to provide the NO necessary to reduce the intake of GTN and the phenomenon of nitrate tolerance and to ensure the correct catalytic activity of ALDH2.

Glyceryl Trinitrate: History, Mystery, and Alcohol Intolerance

Glyceryl trinitrate (GTN) is one of the earliest known treatments for angina with a fascinating history that bridges three centuries. However, despite its central role in the nitric oxide (NO) story as a NO-donating compound, establishing the precise mechanism of how GTN exerts its medicinal benefit has proven to be far more difficult. This review brings together the explosive and vasodilatory nature of this three-carbon molecule while providing an update on the likely in vivo pathways through which GTN, and the rest of the organic nitrate family, release NO, nitrite, or a combination of both, while also trying to explain nitrate tolerance. Over the last 20 years the alcohol detoxification enzyme, aldehyde dehydrogenase (ALDH), has undoubtedly emerged as the front runner to explaining GTN's bioactivation. This is best illustrated by reduced GTN efficacy in subjects carrying the single point mutation (Glu504Lys) in ALDH, which is also responsible for alcohol intolerance, as characterized by flushing. While these findings are significant for anyone following the GTN story, they appear particularly relevant for healthcare professionals, and especially so, if administering GTN to patients as an emergency treatment. In short, although the GTN puzzle has not been fully solved, clinical study data continue to cement the importance of ALDH, as uncovered in 2002, as a key GTN activator.

Influence of the aldehyde dehydrogenase 2 polymorphism on the vasodilatory effect of nitroglycerin in infants with congenital heart disease and pulmonary arterial hypertension

PURPOSE

The influence of the aldehyde dehydrogenase 2 (ALDH2) gene polymorphism on the pharmacokinetics and haemodynamics of nitroglycerin (GTN) was determined in human subjects.

METHODS

Eighteen infants (nine each with and without ALDH2 gene polymorphism) with congenital heart disease and pulmonary arterial hypertension participated in this study. GTN treatment started at a dose of 2 μg/kg/min, and the dose was escalated by 1-2 μg/kg/min until pulmonary vascular resistance (PVR) was reduced by more than 30%. The plasma GTN concentration and PVR were measured at the end of each infusion period.

RESULTS

Plasma GTN concentrations were significantly higher in patients with the ALDH2 gene polymorphism than in those without the polymorphism. Conversely, the reduction in PVR was smaller in patients with the ALDH2 gene polymorphism than in those without.

CONCLUSIONS

These data suggest that the ALDH2 gene polymorphism influences the pharmacokinetics and haemodynamics of GTN in human subjects.

Assessment of endothelium-independent vasodilation: from methodology to clinical perspectives

: Vascular response to exogenously administered nitroglycerine, an index of endothelium-independent vasodilation, has been used as a control test for the assessment of endothelium-dependent vasodilation (endothelial function) in humans. However, evidence has been accumulating that not only endothelium-dependent vasodilation but also endothelium-independent vasodilation per se is impaired in individuals with cardiovascular risk factors and cardiovascular disease. Impaired endothelium-independent vasodilation is associated with structural vascular alterations and alterations in vascular smooth muscle cells. Several methods, including assessment of vascular responses to vasoactive agents using angiography in a coronary artery and vascular responses to vasoactive agents using venous occlusion plethysmography and ultrasonography in a peripheral artery, are used to assess endothelium-independent vasodilation in humans. Measurement of endothelium-independent vasodilation is also useful for assessment of atherosclerosis and may be a predictor of future cardiovascular events. In this review, we focus on assessment of endothelium-independent vasodilation from methodology aspects to clinical perspectives.

Role of Mitochondrial Aldehyde Dehydrogenase in Nitroglycerin-Mediated Vasodilation: Observations Concerning the Dose-Response Relationship

The mechanism of the bioactivation of nitroglycerin has long been controversial, with a number of suggested enzymatic pathways. More recently, aldehyde dehydrogenase-2 (ALDH-2) has been reported as the important enzyme involved in the bioactivation of nitroglycerin at therapeutically relevant concentrations. Other previously described enzyme systems can also bioactivate nitroglycerin, but only at concentrations, which are significantly higher than achieved in clinical practice. This study investigated the vascular response to nitroglycerin given over a wide range of concentrations in subjects with and without the ALDH-2 Glu504Lys polymorphism, a common genetic variant that greatly reduces the activity of ALDH-2 (n = 10 in both groups). Forearm blood flow (FBF) responses to a brachial artery infusion of nitroglycerin were assessed using venous occlusion plethysmography. Intra-arterial infusion of nitroglycerin caused a significant increase in FBF beginning at 0.464 µg/min with increasing responses seen in both groups at all infusion rates. However, there were no differences in the FBF responses to nitroglycerin in those with and without the ALDH-2 polymorphism, suggesting that ALDH-2 is not solely responsible for the bioactivation of nitroglycerin at either low (therapeutically relevant) or high concentrations of nitroglycerin.

ALDH2 and Cardiovascular Disease

Aldehyde dehydrogenase 2 (ALDH2) is a non-cytochrome P450 mitochondrial aldehyde oxidizing enzyme. It is best known for its role in the metabolism of acetaldehyde, a common metabolite from alcohol drinking. More evidences have been accumulated in recent years to indicate a greater role of ALDH2 in the metabolism of other endogenous and exogenous aldehydes, especially lipid peroxidation-derived reactive aldehyde under oxidative stress. Many cardiovascular diseases are associated with oxidative stress and mitochondria dysfunction. Considering that an estimated 560 million East Asians carry a common ALDH2 deficient variant which causes the well-known alcohol flushing syndrome due to acetaldehyde accumulation, the importance of understanding the role of ALDH2 in these diseases should be highlighted. There are several unfavorable cardiovascular conditions that are associated with ALDH2 deficiency. This chapter reviews the function of ALDH2 in various pathological conditions of the heart in relation to aldehyde toxicity. It also highlights the importance and clinical implications of interaction between ALDH2 deficiency and alcohol drinking on cardiovascular disease among the East Asians.