Regulation of angiotensin-converting enzyme production by nicotine in human endothelial cells

Nicotine: Regulatory roles and mechanisms in atherosclerosis progression

Smoking is an independent risk factor for atherosclerosis. The smoke produced by tobacco burning contains more than 7000 chemicals, among which nicotine is closely related to the occurrence and development of atherosclerosis. Nicotine, a selective cholinergic agonist, accelerates the formation of atherosclerosis by stimulating nicotinic acetylcholine receptors (nAChRs) located in neuronal and non-neuronal tissues. This review introduces the pathogenesis of atherosclerosis and the mechanisms involving nicotine and its receptors. Herein, we focus on the various roles of nicotine in atherosclerosis, such as upregulation of growth factors, inflammation, and the dysfunction of endothelial cells, vascular smooth muscle cells (VSMC) as well as macrophages. In addition, nicotine can stimulate the generation of reactive oxygen species, cause abnormal lipid metabolism, and activate immune cells leading to the onset and progression of atherosclerosis. Exosomes, are currently a research hotspot, due to their important connections with macrophages and the VSMC, and may represent a novel application into future preventive treatment to promote the prevention of smoking-related atherosclerosis. In this review, we will elaborate on the regulatory mechanism of nicotine on atherosclerosis, as well as the effects of interference with nicotine receptors and the use of exosomes to prevent atherosclerosis development.

Angiotensin II Type I Receptor Antagonism Attenuates Nicotine-Induced Cardiac Remodeling, Dysfunction, and Aggravation of Myocardial Ischemia-Reperfusion Injury in Rats

Increased exposure to nicotine contributes to the development of cardiac dysfunction by promoting oxidative stress, fibrosis, and inflammation. These deleterious events altogether render cardiac myocytes more susceptible to acute cardiac insults such as ischemia-reperfusion (I/R) injury. This study sought to elucidate the role of angiotensin II type I (AT1) receptors in cardiac injury resulting from prolonged nicotine administration in a rat model. Male Sprague-Dawley rats were given nicotine (0.6 mg/kg ip) for 28 days to induce cardiac dysfunction, alone or in combination with the AT1 receptor antagonist, irbesartan (10 mg/kg, po). Vehicle-treated rats were used as controls. Rat hearts isolated from each experimental group at study endpoint were examined for changes in function, histology, gene expression, and susceptibility against acute I/R injury determined ex vivo. Rats administered nicotine alone exhibited significantly increased cardiac expression of angiotensin II and angiotensin-converting enzyme (ACE) in addition to elevated systolic blood pressure (SBP) and heart rate. Furthermore, nicotine administration markedly reduced left ventricular (LV) performance with concomitant increases in myocardial oxidative stress, fibrosis, and inflammation. Concomitant treatment with irbesartan attenuated these effects, lowering blood pressure, heart rate, oxidative stress, and expression of fibrotic and inflammatory genes. Importantly, the irbesartan-treated group also manifested reduced susceptibility to I/R injury ex vivo. These findings suggest that AT1 receptors play an important role in nicotine-induced cardiac dysfunction, and pharmacological approaches targeting cardiac AT1 receptors may thus benefit patients with sustained exposure to nicotine.

The Association of Life's Simple 7 with Aldosterone among African Americans in the Jackson Heart Study

Background: Among African Americans (AAs), attaining higher levels of American Heart Association (AHA) ideal cardiovascular health (Life’s Simple 7 [LS7]) is associated with lower risk of diabetes and cardiovascular disease (CVD). We previously showed that aldosterone is associated with higher risk of diabetes and CVD in AAs. Thus, we investigated the association of LS7 metrics with aldosterone in the Jackson Heart Study (JHS). Methods: Ideal metrics were defined by AHA 2020 goals for health behaviors (smoking, dietary intake, physical activity, and body mass index) and health factors (total cholesterol, blood pressure, and fasting glucose). The number of ideal LS7 metrics attained at baseline were summed into a continuous score (0–7) and categorical groups (Poor: 0–1, Intermediate: 2–3, and Ideal: ≥4 ideal LS7 metrics). Multivariable linear regression was used. Results: Among 4,095 JHS participants (mean age 55 ± 13 years, 65% female), median serum aldosterone was 4.90, 4.30, and 3.70 ng/dL in the poor (n = 1132), intermediate (n = 2288) and ideal (n = 675) categories respectively. Aldosterone was 15% [0.85 (0.80, 0.90)] and 33% [0.67 (0.61, 0.75)] lower in the intermediate and ideal LS7 categories compared to the poor LS7 category. Each additional LS7 metric attained on continuous LS7 score (0–7) was associated with an 11% [0.89 (0.86, 0.91)] lower aldosterone level with variation by sex with women having a 15% lower aldosterone vs. 5% in men. Conclusions: Higher attainment of ideal LS7 metrics was associated with lower serum aldosterone among AAs with a greater magnitude of association among women compared to men.

Angiotensin-converting enzyme insertion/deletion gene polymorphism and lung cancer risk: A meta-analysis

OBJECTIVE

Angiotensin-converting enzyme (ACE) I/D polymorphism has been reported to be associated with lung cancer, but the results of previous studies are conflicting. The present study was designed to investigate the association between this polymorphism and the risk of lung cancer using a meta-analysis of the published studies.

METHODS

Two investigators independently searched the PubMed, Embase and CNKI databases. This meta-analysis covered six case-control studies, including 807 lung cancer patients and 816 healthy controls.

RESULTS

The results of this meta-analysis based on all the studies showed no significant association between ACE I/D gene polymorphism and lung cancer risk (DD vs II: OR = 1.18, 95% CI = 0.68-2.04; DI vs II: OR = 0.93, 95% CI = 0.56-1.53; DD+DI vs II: OR = 1.01, 95% CI = 0.68-1.50; DD vs II+DD: OR =1.11, 95% CI = 0.73-1.71). In the subgroup analysis by race and the larger studies (n > 200 participants), no significant associations between the ACE I/D polymorphism and risk of lung cancer were indicated. However, when the analyses were restricted to small studies (n ≤ 200 participants), a significantly higher risk was observed (DD vs II: OR = 2.57, 95% CI = 1.24-5.30).

CONCLUSIONS

This meta-analysis suggests that the ACE gene I/D polymorphism may not be associated with the risk of lung cancer, and the observed increase in the risk of lung cancer may be due to small-study bias.

Impairment of flow-mediated dilation correlates with aortic dilation in patients with Marfan syndrome

Marfan syndrome is an inherited disorder characterized by genetic abnormality of microfibrillar connective tissue proteins. Endothelial dysfunction is thought to cause aortic dilation in subjects with a bicuspid aortic valve; however, the role of endothelial dysfunction and endothelial damaging factors has not been elucidated in Marfan syndrome. Flow-mediated dilation, a noninvasive measurement of endothelial function, was evaluated in 39 patients with Marfan syndrome. Aortic diameter was measured at the aortic annulus, aortic root at the sinus of Valsalva, sinotubular junction and ascending aorta by echocardiography, and adjusted for body surface area (BSA). The mean value of flow-mediated dilation was 6.5 ± 2.4 %. Flow-mediated dilation had a negative correlation with the diameter of the ascending thoracic aorta (AscAd)/BSA (R = -0.39, p = 0.020) and multivariate analysis revealed that flow-mediated dilation was an independent factor predicting AscAd/BSA, whereas other segments of the aorta had no association. Furthermore, Brinkman index had a somewhat greater influence on flow-mediated dilation (R = -0.42, p = 0.008). Although subjects who smoked tended to have a larger AscAd compared with non-smokers (AscA/BSA: 17.3 ± 1.8 versus 15.2 ± 3.0 mm/m(2), p = 0.013), there was no significant change in flow-mediated dilation, suggesting that smoking might affect aortic dilation via an independent pathway. Common atherogenic risks, such as impairment of flow-mediated dilation and smoking status, affected aortic dilation in subjects with Marfan syndrome.

Angiotensin-converting enzyme insertion/deletion gene polymorphism in lung cancer patients

Lung cancer is a complex disease, and many factors, including environmental and occupational exposure, cigarette smoking, and genetics, contribute to its progression. Angiotensin-converting enzyme (ACE) is an important regulator of blood pressure and cardiovascular homeostasis. Plasma levels of ACE depend on an insertion/deletion (I/D) polymorphism in its gene. Current correlation data between lung cancer and the ACE I/D polymorphism are contradictory or insufficient. We investigated whether the ACE I/D polymorphism is associated with a risk for lung cancer development in the Croatian population, representing the first report in a population of Slavic origin. A total of 308 lung cancer patients and 353 control subjects were genotyped for the ACE I/D polymorphism by polymerase chain reaction. The observed distribution of genotypes and alleles showed no significant difference between total patients and controls (p>0.050). However, in a subgroup of nonsmall cell lung cancer patients with squamous cell carcinoma, a significantly higher frequency of the DD genotype (37.7% vs. 27.8%, p=0.030, OR=1.57, 95% CI=1.05-2.36) and D allele was observed compared with the control group (61.3% vs. 52.8%, p=0.015, OR=1.41, 95% CI=1.07-1.87). The DD genotype of ACE may contribute to a higher risk of developing squamous cell carcinoma in the Croatian population.

Interaction between smoking and polymorphism in the promoter region of the VEGFA gene is associated with ischemic heart disease and myocardial infarction in rheumatoid arthritis

OBJECTIVE

To determine whether variants in the vascular endothelial growth factor A (VEGFA) gene are associated with ischemic heart disease (IHD) and/or myocardial infarction (MI) in patients with rheumatoid arthritis (RA), and whether there is evidence of a gene-smoking interaction.

METHODS

PCR-RFLP assays were used to determine the genotypes of VEGFA single-nucleotide polymorphisms (SNP) including VEGFA-2578A/C (rs699947), -460C/T (rs833061), +405C/G (rs2010963), and +936C/T (rs3025039) in 418 subjects with RA. Smoking history was obtained on each patient, and IHD and MI status was recorded. Associations with IHD/MI were assessed using contingency tables and logistic regression analyses.

RESULTS

Strong linkage disequilibrium was detected among VEGFA-2578, -460, and +405. SNP located in the VEGFA promoter region (-2578, -460) were found to be associated with IHD and MI, whereas +405 and +936, in the 5'-untranslated region (UTR) and 3'-UTR, respectively, were not. Haplotype analysis suggested that the A/C/G haplotype was associated with increased risk of IHD (OR 2.37, 95% CI 1.22-4.62) and MI (OR 4.10, 95% CI 1.45-11.49). Smoking was also independently associated with IHD and MI, and evidence of interaction between smoking and the VEGFA promoter SNP was found. Multivariate analyses indicated that the strongest associations with IHD and MI were due to the combined effect of the VEGFA-2578 A allele and smoking (OR 3.52 and 7.11, respectively), independent of risk factors such as age, sex, diabetes, C-reactive protein, hypercholesterolemia, and hypertension.

CONCLUSION

Interaction between smoking and polymorphism in the VEGFA gene is associated with IHD and MI in patients with RA.

Losartan attenuates chronic cigarette smoke exposure-induced pulmonary arterial hypertension in rats: possible involvement of angiotensin-converting enzyme-2

Chronic cigarette smoking induces pulmonary arterial hypertension (PAH) by largely unknown mechanisms. Renin–angiotensin system (RAS) is known to function in the development of PAH. Losartan, a specific angiotensin II receptor antagonist, is a well-known antihypertensive drug with a potential role in regulating angiotensin-converting enzyme-2 (ACE2), a recently found regulator of RAS. To determine the effect of losartan on smoke-induced PAH and its possible mechanism, rats were daily exposed to cigarette smoke for 6 months in the absence and in the presence of losartan. Elevated right ventricular systolic pressure (RVSP), thickened wall of pulmonary arteries with apparent medial hypertrophy along with increased angiotensin II (Ang II) and decreased ACE2 levels were observed in smoke-exposed-only rats. Losartan administration ameliorated pulmonary vascular remodeling, inhibited the smoke-induced RVSP and Ang II elevation and partially reversed the ACE2 decrease in rat lungs. In cultured primary pulmonary artery smooth muscle cells (PASMCs) from 3- and 6-month smoke-exposed rats, ACE2 levels were significantly lower than in those from the control rats. Moreover, PASMCs from 6-month exposed rats proliferated more rapidly than those from 3-month exposed or control rats, and cells grew even more rapidly in the presence of DX600, an ACE2 inhibitor. Consistent with the in vivo study, in vitro losartan pretreatment also inhibited cigarette smoke extract (CSE)-induced cell proliferation and ACE2 reduction in rat PASMCs. The results suggest that losartan may be therapeutically useful in the chronic smoking-induced pulmonary vascular remodeling and PAH and ACE2 may be involved as part of its mechanism. Our study might provide insight into the development of new therapeutic interventions for PAH smokers.

The M235T polymorphism of the AGT gene modifies the risk of coronary artery disease associated with the presence of hypercholesterolemia

OBJECTIVE

Atherosclerosis is an inflammatory disease resulting from interactions between various genetic and non-genetic factors. Angiotensinogen gene (AGT) belongs to polymorphic candidate genes. Recent evidence show that many traditional risk factors of coronary artery disease (CAD) influence synthesis of AGT. This report focuses on the interactions between M235T polymorphism of AGT gene and traditional risk factors of CAD.

MATERIAL AND METHODS

255 subjects, including 158 patients with angiographically confirmed CAD and 97 blood donors without history of cardiovascular diseases were studied. M235T polymorphism of the AGT gene was genotyped using PCR-RFLP method. To determine the possible interactions of AGT genotypes and traditional risk factors of CAD the attributable proportion due to interaction (AP) and synergy models were used.

RESULTS

The frequency of 235T allele carriers was significantly higher in patients than in controls (77.8 vs. 62.9, OR = 2.20, 95% CI; 1.10-4.40, P = 0.026, in multivariate logistic regression model). We found the existence of interaction between the 235T allele carrier-state and hypercholesterolemia (total cholesterol > or = 5 mmol/l) increasing the risk of CAD (SI = 3.39, 95% CI; 1.33-8.66, AP = 0.65, 95% CI; 0.39-0.91). The 235T allele also interacted with elevated LDL cholesterol levels (> or = 3 mmol/l) (AP = 0.49, 95% CI; 0.20-0.96), but not with the hypertension, overweight/ obesity and cigarette smoking.

CONCLUSION

The 235T allele increases the risk of CAD associated with the presence of hypercholesterolemia.

The risk of coronary artery disease associated with cigarette smoking and hypercholesterolemia is additionally increased by the presence of the AT1R gene 1166C allele

Cigarette smoking and hypercholesterolemia influence the renin-angiotensin system (RAS) functions, including increased RAS-mediated vasoconstriction, mitogenic signaling, and angiotensin II type 1 receptor (AT1R) expression. We have explored the interactions of the AT1R gene 1166 A>C polymorphism and traditional risk factors using an epidemiological approach. The study cohort included 341 subjects; 172 were patients with angiographically confirmed coronary artery disease (CAD) and 169 were blood donors. The 1166 A>C polymorphism was genotyped using the PCR-RFLP method. We found a synergy of the 1166C allele with cigarette smoking (synergy indices: SI = 1.41, SIM = 1.33), LDL cholesterol levels > or = 3 mmol/l (SI = 1.25, SIM = 1.19), and elevated total cholesterol (> or =5 mmol/l) levels (SI = 1.15, SIM = 1.13). In each case, the estimated CAD risk was greater than that predicted by assuming the additivity and multiplication of effects. We conclude that the 1166C allele increases the risk of CAD associated with the presence of cigarette smoking and hypercholesterolemia.

Modification of the coronary artery disease risk associated with the presence of traditional risk factors by insertion/deletion polymorphism of the ACE gene

Cigarette smoking, hypercholesterolemia, and obesity influence the renin-angiotensin system (RAS) functions including an increased synthesis of the angiotensin I converting enzyme (ACE). Thus in the present work we explore the interactions of the ACE gene insertion/deletion (I/D) polymorphism and traditional risk factors. The study cohort included 341 subjects composed of 172 patients with angiographically confirmed CAD and 169 blood donors without a history of cardiovascular diseases. The I/D polymorphism was genotyped using polymerase chain reaction (PCR) methodology. To determine the interactions between the ACE genotypes and traditional risk factors the epidemiologic approach was used (4 x 2 tables and the synergy measures). The frequency of the DD genotype was significantly higher in patients than in controls (33.7% versus 21.3%, odds ratio [OR] = 1.88, 95% CI; 1.13-3.15, p = 0.010), but greater differences were found in males (35.7% versus 20.5%, OR = 2.15, 95% CI: 1.14-4.04, p = 0.010). We found a synergy of the DD genotype with smoking (SI = 1.88, SIM = 1.22), total cholesterol > or =5 mmol/l (SI = 2.12, SIM = 1.31) and elevated low density lipoprotein (LDL) cholesterol level (> or =3 mmol/l) (SI = 1.78, SIM = 1.14). The presence of the D allele (DD + ID subjects) also increased the risk of coronary artery disease (CAD) associated with the presence of elevated total cholesterol and LDL cholesterol (SI = 1.69, SIM = 1.18, in both cases), elevated level (> or =1.7 mmol/l) of triacylglycerols (SI = 1.81, SIM = 1.18) and overweight/obesity (SI = 4.25, SIM = 2.36). In each case the estimated CAD risk was greater than that predicted by assuming the additivity of effects (the risk increased from 69% for the D allele - total cholesterol interaction to 325% for the D allele - overweight/obesity). The statistical significance was also confirmed by a multiplicative model of synergy. The DD genotype/D allele of the ACE gene increases the risk of CAD associated with the presence of traditional risk factors.

The 242T variant of the CYBA gene polymorphism increases the risk of coronary artery disease associated with cigarette smoking and hypercholesterolemia

OBJECTIVES

Hypercholesterolemia and cigarette smoking increase superoxide anion production, which is involved in many proatherosclerotic processes. NAD(P)H oxidases are the main source of superoxides in the vasculature, and the phagocyte oxidase (p22phox) encoded by the CYBA gene is a critical component of NAD(P)H oxidases. The 242T CYBA allele is associated with an increased low-density lipoprotein oxidation and superoxide production. This report focuses on the interactions between C242T CYBA polymorphism and traditional risk factors of coronary artery disease (CAD), such as cigarette smoking and hypercholesterolemia.

METHODS

We have studied 341 individuals, including 172 patients with angiographically confirmed CAD and 169 blood donors with no known history of cardiovascular disease. The C242T CYBA polymorphism was genotyped using the PCR-restriction fragment-length polymorphism method. To determine the possible interactions between CYBA genotypes and the traditional risk factors for CAD, we used multivariate logistic regression analysis (cumulative effects) and the 4 x 2 table approach (synergistic/antagonistic effects).

RESULTS

We have found a strong cumulative effect of the 242T allele carrier state and cigarette smoking and hypercholesterolemia. The risk of CAD associated with the presence of cigarette smoking and hypercholesterolemia was stronger in 242T carriers (odds ratio=17.88, P<0.00000) than in CC homozygotes (odds ratio=3.75, P<0.00000). Estimated CAD risk associated with the presence of the 242T allele and both traditional risk factors was approximately 500% greater than the risk predicted by assuming additivity of effects (synergy index, 5.08).

CONCLUSION

The 242T allele interacts with cigarette smoking and hypercholesterolemia to increase the risk of CAD; this risk is probably associated with the cumulative/synergistic effect of the 242T allele and both the traditional risk factors.