Dietary DNA Attenuates the Degradation of Elastin Fibers in the Aortic Wall in Nicotine-Administrated Mice

Nicotine induces vasa vasorum stenosis in the aortic wall

Abdominal aortic aneurysm (AAA) is a vascular disease that involves aortic wall dilation. Cigarette smoking is an established risk factor and rupture, and nicotine may be a major contributor to the onset of AAA. In humans the condition is associated with stenosis of the vasa vasorum (VV), which may be caused by nicotine. In this study, we evaluated the effects of nicotine on VV pathology. After 4 weeks of nicotine administration to rats using an osmotic pump, the VV patency rate in the nicotine administration group was significantly lower than that in the control group. The levels of Ki-67, a cell proliferation marker, were significantly increased in the regions containing VV in the nicotine group, as were hypoxia inducible factor-α levels. Collagen levels around VV were significantly lower in the nicotine group than in the controls. Our data suggest that nicotine can cause VV stenosis by inducing abnormal proliferation of smooth muscle cells in the VV. The increased risk of AAA development due to cigarette smoking may be partially explained by nicotine-induced VV denaturation and collagen fiber degradation.

Mitochondrial quality control in abdominal aortic aneurysm: From molecular mechanisms to therapeutic strategies

Mitochondria are the energy supply sites of cells and are crucial for eukaryotic life. Mitochondrial dysfunction is involved in the pathogenesis of abdominal aortic aneurysm (AAA). Multiple mitochondrial quality control (MQC) mechanisms, including mitochondrial DNA repair, biogenesis, antioxidant defense, dynamics, and autophagy, play vital roles in maintaining mitochondrial homeostasis under physiological and pathological conditions. Abnormalities in these mechanisms may induce mitochondrial damage and dysfunction leading to cell death and tissue remodeling. Recently, many clues suggest that dysregulation of MQC is closely related to the pathogenesis of AAA. Therefore, specific interventions targeting MQC mechanisms to maintain and restore mitochondrial function have become promising therapeutic methods for the prevention and treatment of AAA.

Survey of Food Intake in Patients with Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular disease that involves asymptomatic progressive expansion of the abdominal aorta. Aneurysm rupture is associated with a high mortality rate. Dietary conditions may be associated with the development and rupture of AAA. However, the relationship between nutrition and AAA is not completely understood. In this study, a nutrition survey was conducted using a brief self-administered diet history questionnaire (BDHQ) to evaluate the relationship between AAA and dietary habits. One-hundred and twenty-six Japanese people participated in the nutrition survey. Food intake status was analyzed in four groups: the analyzed group-1 (all men), analyzed group-2 (men with smoking history), analyzed group-3 (all women) and analyzed group-4 (women without smoking history). In group-2 and group-3, the intake of citrus fruits was significantly lower in the AAA group than in the non-AAA group. In group-2, the intake of soybean and soybean products was significantly lower in the AAA group than in the non-AAA group. In analyzed group-3, the intake of other vegetables (vegetables except for green and yellow vegetables and soybeans) and seafood was significantly lower in the AAA group than in the non-AAA group. This study suggests that AAA onset may be associated with low intake of fruits, soybeans, vegetables, and seafood.

The Biological Effects of Smoking on the Formation and Rupture of Intracranial Aneurysms: A Systematic Review and Meta-Analysis

Background

Aneurysms of the cerebral vasculature are relatively common, which grow unpredictably, and even small aneurysms carry a risk of rupture. Rupture of intracranial aneurysms (IA) is a catastrophic event with a high mortality rate. Pieces of evidence have demonstrated that smoking is closely related to the formation and rupture of IA. However, the biological effect of smoking cigarettes on the formation and rupture of IA is still underrepresented.

Methods

The study protocol was prospectively registered in PROSPERO, registration number CRD42020203634. We performed a systematic search in PubMed and CNKI for studies exploring the biological effects of smoking on intracranial aneurysms published up to December 2021, and all studies were included in the analysis. The RevMan software was used for data analysis.

Results

A total of 6,196 patients were included in 14 original articles in this meta-analysis. The risk of ruptured IA in the current smoking group was significantly higher than that in the non-smoking group, with statistical significance (RR_total = 1.23, 95% CI: 1.11–1.37). After heterogeneity among cohorts was removed by the sensitivity analysis, there was still a statistically significant difference in the risk of ruptured IA between the smoking and non-smoking groups (RR total = 1.26, 95% CI: 1.18–1.34). There was no statistically significant difference in the risk of ruptured IA between the former smoking (smoking cessation) group and the non-smoking group (RR_total = 1.09, 95% CI: 0.50–2.38). After heterogeneity among cohorts was removed by sensitivity analysis, there was still no statistically significant difference in the risk of ruptured IA between the former smoking (smoking cessation) group and the non-smoking group (RRtotal = 0.75, 95% CI: 0.47–1.19). The risk of the ruptured IA in the current smoking group was significantly higher than that in the former smoking (smoking cessation) group, with a statistically significant difference (RR_total=1.42, 95%CI: 1.27–1.59).

Conclusion

Although the biological effects of smoking on the formation and rupture of IA are unknown, this study suggests that current smoking is a risk factor for ruptured IA. Quitting smoking is very important for patients with IA.

Smoking and the Pathophysiology of Peripheral Artery Disease

Smoking is one of the most important preventable factors causing peripheral artery disease (PAD). The purpose of this review is to comprehensively analyze and summarize the pathogenesis and clinical characteristics of smoking in PAD based on existing clinical, in vivo, and in vitro studies. Extensive searches and literature reviews have shown that a large amount of data exists on the pathological process underlying the effects of cigarette smoke and its components on PAD through various mechanisms. Cigarette smoke extracts (CSE) induce endothelial cell dysfunction, smooth muscle cell remodeling and macrophage phenotypic transformation through multiple molecular mechanisms. These pathological changes are the molecular basis for the occurrence and development of peripheral vascular diseases. With few discussions on the topic, we will summarize recent insights into the effect of smoking on regulating PAD through multiple pathways and its possible pathogenic mechanism.

Electronic cigarette exposure disrupts blood-brain barrier integrity and promotes neuroinflammation

Electronic cigarette (e-cigarette) use has grown substantially since inception, particularly among adolescents and combustible tobacco users. Several cigarette smoke constituents with known neurovascular effect are present in e-cigarette liquids or formed during the vapor generation. The present study establishes inhaled models of cigarette and e-cigarette use with normalized nicotine delivery, then characterizes the impact on blood-brain barrier (BBB) function. Sequencing of microvessel RNA following exposure revealed downregulation of several genes with critical roles in BBB function. Reduced protein expression of Occludin and Glut1 is also observed at the tight junction in all groups following exposure. Pro-inflammatory changes in leukocyte-endothelial cell interaction are also noted, and mice exposed to nicotine-free e-cigarettes have impaired novel object recognition performance. On this basis, it is concluded that long term e-cigarette use may adversely impact neurovascular health. The observed effects are noted to be partly independent of nicotine content and nicotine may even serve to moderate the effects of non-nicotinic components on the blood-brain barrier.

The Seed Coat Extract of Black Soybean Decreases Nicotine-Induced Vascular Fiber Degradation by Suppressing Matrix Metalloproteinase 2 Expression

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by weakening of vascular walls and progressive dilation of the abdominal aorta. Nicotine, the main component of tobacco, is reportedly associated with the development and rupture of AAA. It is desirable to attenuate the destructive effect of nicotine on vascular walls, using dietary food components. However, effective methods for preventing AAA progression using dietary food components remain unestablished. This study focuses on proanthocyanidins, well known for their potent antioxidant activity. We speculated that proanthocyanidins can suppress nicotine-induced weakening of vascular walls. To estimate the effect of black soybean seed coat extract (BSSCE), rich in proanthocyanidins, on nicotine-induced weakening of the aortic wall, mice were divided into four groups: the control diet and distilled water group (named C), BSSCE solution diet and distilled water group (named B), control diet and 0.5 mg/mL nicotine solution group (named CN), and BSSCE solution diet and 0.5 mg/mL nicotine solution group (named BN). Nicotine-induced degradation of elastin and collagen fibers were significantly suppressed in BN group. The positive areas for matrix metalloproteinase (MMP)-2 and oxidative stress in BN group were significantly decreased compared to those in CN group. These results suggest that proanthocyanidins-rich BSSCE can prevent the weakening of the aortic wall via inhibiting MMP-2 upregulation.

In times of tobacco-free nicotine consumption: The influence of nicotine on vascular calcification

BACKGROUND

Smoking remains the most important avoidable cause of global mortality. Even though the number of cigarette smokers declines in first world countries, the uses of alternative nicotine delivery products increase and may even surpass the sells of cigarettes. In this light, the explicit role of nicotine in the development of cardiovascular diseases should be elucidated.

OBJECTIVES

This narrative review attempts to connect current literature about possible effects of nicotine on the environment of the vasculature to the pathogenesis of vascular calcification, focusing on the tunica media of the vessel wall.

METHODS

For this review, papers found on Pubmed and Medline until December 2018 by searching for the keywords nicotine, vascular calcification, oxidative stress, osteoblastic transdifferentiation and matrix degradation were considered.

RESULTS

Nicotine creates an environment that probably facilitates and maybe even induces osteogenic transdifferentiation of VSMC by inflammation, endothelial dysfunction and reactive oxygen species. This process is believed to be a key event in calcification of the tunica media of the vessel wall. Furthermore, nicotine could lead to the formation of nucleation sites for hydroxyapatite by facilitating matrix vesicles and extracellular matrix degradation.

CONCLUSIONS

There is a growing body of evidence implicating that nicotine alone could impair vascular function and lead to vascular calcification. Further research is necessary to elucidate the explicit influence of nicotine on arteriosclerosis.