Smoking and the Pathophysiology of Peripheral Artery Disease

Assessment of causal associations between obesity and peripheral artery disease: a bidirectional Mendelian randomization study

Background

Several observational studies have documented a potential link between obesity and peripheral artery disease (PAD), although conflicting findings exist. The causal relationship between obesity and PAD continues to be a subject of ongoing debate in the medical community.

Objectives

In this study, we employed a bidirectional Mendelian randomization (MR) analysis to explore the potential causal relationship between obesity and the risk of PAD.

Methods

To investigate these causal relationships, we conducted bidirectional MR analysis using publicly available genome-wide association study (GWAS) data. Effect estimates were calculated using the random-effects inverse variance-weighted (IVW) method.

Results

We identified eight independent single nucleotide polymorphisms (SNPs) associated with obesity in 218,735 samples involving 16,380,465 SNPs, all of which met the genome-wide significance threshold (p < 5 × 10-⁸). The IVW analysis indicates a significant positive association between genetic obesity and multiple datasets with PAD as the outcome: Queue-1 (GWAS ID: finn-b-I9_PAD) (OR = 1.138, 95% CI: 1.027-1.261, p = 0.013), Queue-2 (GWAS ID: bbj-a-144) (OR = 1.190, 95% CI: 1.019-1.390, p = 0.028), Queue-3 (GWAS ID: ebi-a-GCST90018670) (OR = 1.174, 95% CI: 1.014-1.360, p = 0.032), and Queue-4 (GWAS ID: ebi-a-GCST90018890) (OR = 1.194, 95% CI: 1.099-1.296, p < 0.001). However, we did not observe a significant genetic-level association between obesity and PAD for Queue-5 (GWAS ID: ukb-d-I9_PAD) (OR = 1.001, 95% CI: 1.000-1.002, p = 0.071). Furthermore, we conducted a reverse causal MR analysis to explore the potential reverse causal relationship between obesity and PAD. This comprehensive analysis did not provide evidence of a reverse causal association between these two factors.

Conclusions

In summary, our study offers genetic evidence suggesting a possible causal link between obesity and PAD. While we did not find evidence supporting the "obesity paradox", prudent weight management remains crucial, as lower weight does not necessarily guarantee better outcomes. As with any study, caution is required in interpreting the findings. Further research is essential to assess the clinical relevance of weight in preventing PAD, which could inform the development of more precise intervention strategies.

Outcomes of balloon angioplasty and stent placement for iliac artery lesions classified as TASC II A, B: a single-center study

Background

Iliac artery stenosis or occlusion is a critical condition that can severely impact a patient's quality of life. The effectiveness of balloon angioplasty and intraluminal stenting for the treatment of iliac artery lesions classified as TASC II A and B was evaluated in this single-center prospective study.

Methods

Conducted between October 2016 and September 2020 at Cho Ray Hospital's Vascular Surgery Department, this prospective study involved PAD patients categorized by TASC II A and B classifications who underwent endovascular intervention. Intervention outcomes were assessed peri-procedure and during short-term and mid-term follow-ups.

Results

Of the total of 133 patients, 34.6% underwent balloon angioplasty, while 65.4% received stenting. The immediate technical success rate was 97.7%, while the clinical success rate was 62.4%. Complications were minimal, with major limb amputation reported in 1.5% of the cases. There was a significant improvement in Rutherford classification and ABI at short-term follow-up, with a patency rate of 90.2%. The mid-term post-intervention follow-up yielded similar results with an 86.1% patency rate. The mortality rates associated with arterial occlusion were 2.3% during short-term follow-up and 1.7% during mid-term follow-up.

Conclusion

Balloon angioplasty and stent placement are effective and safe interventions for TASC II A and B iliac artery occlusions with favorable short and mid-term outcomes. Further, multi-center studies with larger sample sizes are recommended for more comprehensive conclusions, including long-term follow-up assessment.

In Association with Other Risk Factors, Smoking Is the Main Predictor for Lower Transcutaneous Oxygen Pressure in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) significantly increases the risk of peripheral artery disease (PAD), and diabetes is the leading cause of nontraumatic amputations. This study investigated the risk factors for transcutaneous oxygen pressure (TcPO2) in T2DM, a noninvasive method to quantify skin oxygenation and the underlying microvascular circulation. The study included 119 T2DM patients (91 male/28 female). TcPO2 measurements were conducted with the Tina TCM4 Series transcutaneous monitor (Radiometer, Copenhagen, Sweden) and skin electrodes. Patients with TcPO2 < 40 mmHg were younger (p = 0.001), had significantly higher systolic blood pressure (SBP) (p = 0.023), glycated hemoglobin (HbA1c) (p = 0.013), fasting plasma glucose (fPG) (p = 0.038), total cholesterol (p = 0.006), LDL cholesterol (p = 0.004), and had more frequent smoking habits (p = 0.001) than those with TcPO2 ≥ 40 mmHg. The main predictors for the TcPO2 value (R2 = 0.211) obtained via stepwise regression analysis were age, smoking, SBP, HbA1c, fPG, and total and LDL cholesterol. Among all the listed predictors, smoking, HbA1c, and LDL cholesterol were found to be the most significant, with negative parameter estimates of -3.051310 (p = 0.0007), -2.032018 (p = 0.0003), and -2.560353 (p = 0.0046). The results of our study suggest that in association with other risk factors, smoking is the main predictor for lower TcPO2 in T2DM.

Sex, Endothelial Cell Functions, and Peripheral Artery Disease

Peripheral artery disease (PAD) is caused by blocked arteries due to atherosclerosis and/or thrombosis which reduce blood flow to the lower limbs. It results in major morbidity, including ischemic limb, claudication, and amputation, with patients also suffering a heightened risk of heart attack, stroke, and death. Recent studies suggest women have a higher prevalence of PAD than men, and with worse outcomes after intervention. In addition to a potential unconscious bias faced by women with PAD in the health system, with underdiagnosis, and lower rates of guideline-based therapy, fundamental biological differences between men and women may be important. In this review, we highlight sexual dimorphisms in endothelial cell functions and how they may impact PAD pathophysiology in women. Understanding sex-specific mechanisms in PAD is essential for the development of new therapies and personalized care for patients with PAD.

Comparative assessment of electronic nicotine delivery systems aerosol and cigarette smoke on endothelial cell migration: The Replica Project

Cigarette smoking is associated with impairment of repair mechanisms necessary for vascular endothelium homeostasis. Reducing the exposure to smoke toxicants may result in the mitigation of the harmful effect on the endothelium and cardiovascular disease development. Previous investigations evaluated in vitro the effect of electronic cigarette (EC) compared with cigarette smoke demonstrating a significant reduction in human umbilical vein endothelial cells (HUVECs) migration inhibition following EC aerosol exposure. In the present study, we replicated one of these studies, evaluating the effects of cigarette smoke on endothelial cell migration compared with aerosol from EC and heated tobacco products (HTPs). We performed an in vitro scratch wound assay on endothelial cells with a multi-center approach (ring-study) to verify the robustness and reliability of the results obtained in the replicated study, also testing the effect of aerosol from two HTPs on endothelial cells. Consistently with the original study, we observed a substantial reduction of the effects of aerosol from EC and HTPs on endothelial cell migration compared with cigarette smoke. While cigarette smoke reduced endothelial wound healing ability already at low concentrations (12.5%) and in a concentration-dependent manner, EC and HTPs aerosol showed no effect on endothelial cells until 80%-100% concentrations. In conclusion, our study further confirms the importance of EC and tobacco heated products as a possible harm reduction strategy for cardiovascular diseases development in smokers.

Pathological mechanisms of cigarette smoking, dietary, and sedentary lifestyle risks in vascular dysfunction: mitochondria as a common target of risk factors

In the past century, the lifespan of the human population has dramatically increased to the 80 s, but it is hindered by a limited health span to the 60 s due to an epidemic increase in the cardiovascular disease which is a main cause of morbidity and mortality. We cannot underestimate the progress in understanding the major cardiovascular risk factors which include cigarette smoking, dietary, and sedentary lifestyle risks. Despite their clinical significance, these modifiable risk factors are still the major contributors to cardiovascular disease. It is, therefore, important to understand the specific molecular mechanisms behind their pathological effects to develop new therapies to improve the treatment of cardiovascular disease. In recent years, our group and others have made a progress in understanding how these risk factors can promote endothelial dysfunction, smooth muscle dysregulation, vascular inflammation, hypertension, lung, and heart diseases. These factors, despite differences in their nature, lead to stereotypical alterations in vascular metabolism and function. Interestingly, cigarette smoking has a tremendous impact on a very distant site from the initial epithelial exposure, namely circulation and vascular cells mediated by a variety of stable cigarette smoke components which promote vascular oxidative stress and alter vascular metabolism and function. Similarly, dietary and sedentary lifestyle risks facilitate vascular cell metabolic reprogramming promoting vascular oxidative stress and dysfunction. Mitochondria are critical in cellular metabolism, and in this work, we discuss a new concept that mitochondria are a common pathobiological target for these risk factors, and mitochondria-targeted treatments may have a therapeutic effect in the patients with cardiovascular disease.

Focus on Prevention: Peripheral Arterial Disease and the Central Role of the Cardiologist

Peripheral artery disease (PAD) is a manifestation of systemic atherosclerotic disease. PAD patients have a poor prognosis with an increased risk of cardiovascular (CV) events, including myocardial infarction (MI), stroke, limb ischemia and CV death; therefore, it is important to detect and treat PAD early. PAD and coronary artery disease (CAD) share a common pathogenesis and risk factors for development; therefore, cardiologists are in a unique position to screen, diagnosis and treat PAD. Moreover, PAD and CAD also share some treatment goals, including an aggressive modification of risk factors to reduce the risk of CV events. However, PAD remains an underdiagnosed and undertreated disease with medico-legal implications. As the role of cardiologists is expanding, the purpose of this review was to awaken the clinicians to the significance of PAD.

Impact of bisoprolol and amlodipine on cardiopulmonary responses and symptoms during exercise in patients with chronic obstructive pulmonary disease

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) often have exercise intolerance. The prevalence of hypertension in COPD patients ranges from 39-51%, and β-blockers and amlodipine are commonly used drugs for these patients.

OBJECTIVES

We aimed to study the impact of β-blockers and amlodipine on cardiopulmonary responses during exercise.

METHODS

A total 81 patients with COPD were included and the patients underwent spirometry, cardiopulmonary exercise tests, and symptoms questionnaires.

RESULTS

There were 14 patients who took bisoprolol and 67 patients who did not. Patients with COPD taking ß-blockers had lower blood oxygen concentration (SpO2) and more leg fatigue at peak exercise but similar exercise capacity as compared with patients not taking bisoprolol. There were 18 patients treated with amlodipine and 63 patients without amlodipine. Patients taking amlodipine had higher body weight, lower blood pressure at rest, and lower respiratory rates during peak exercise than those not taking amlodipine. Other cardiopulmonary parameters, such as workload, oxygen consumption at peak exercise, tidal volume at rest or exercise, cardiac index at rest or exercise were not significantly different between patients with or without bisoprolol or amlodipine. Smoking status did not differ between patients with or without bisoprolol or amlodipine.

CONCLUSIONS

COPD is often accompanied by hypertension, and β-blockers and amlodipine are commonly used antihypertensive drugs for these patients. Patients with COPD taking bisoprolol had lower SpO2 and more leg fatigue during peak exercise. Patients taking amlodipine had lower respiratory rates during exercise than those not taking amlodipine. Exercise capacity, tidal volume, and cardiac index during exercise were similar between patients with and without bisoprolol or amlodipine.

A modern day perspective on smoking in peripheral artery disease

Peripheral artery disease (PAD) is associated with increased risk of cardiovascular morbidity and mortality, poor functional status, and lower quality of life. Cigarette smoking is a major preventable risk factor for PAD and is strongly associated with a higher risk of disease progression, worse post-procedural outcomes, and increased healthcare utilization. The arterial narrowing due to atherosclerotic lesions in PAD leads to decreased perfusion to the limbs and can ultimately cause arterial obstruction and limb ischemia. Endothelial cell dysfunction, oxidative stress, inflammation, and arterial stiffness are among the key events during the development of atherogenesis. In this review, we discuss the benefits of smoking cessation among patients with PAD and the use of smoking cessation methods including pharmacological treatment. Given that smoking cessation interventions remain underutilized, we highlight the importance of incorporating smoking cessation treatments as part of the medical management of patients with PAD. Regulatory approaches to reduce the uptake of tobacco product use and support smoking cessation have the potential to reduce the burden of PAD.

Real world data from a multi-centre study on the effects of cilostazol on pain symptoms and walking distance in patients with peripheral arterial disease

OBJECTIVE

to assess the effects of cilostazol on pain-free walking distance in PAD patients with IC at 3 and 6 months in a real world, prospective, observational study. We included 1015 PAD patients presenting with IC (71.3% men, 93.5% white, mean age 69.2 ± 8.7 years). Patients were followed up for 6 months by their physicians.

RESULTS

Cilostazol significantly increased pain-free walking distance by a median of 285 and 387 m at 3 and 6 months, respectively (p < 0.01 for all comparisons). This effect was significant for patients 50-74 years (but not for those aged ≥ 75 years) and independent of smoking status, changes in physical activity, comorbidities and concomitant medication for PAD (i.e., acetylsalicylic acid and clopidogrel). Furthermore, significant reductions were observed in systolic (from 139 ± 16 to 133 ± 14 mmHg; p < 0.001) and diastolic blood pressure (from 84 ± 9 mmHg to 80 ± 10 mmHg; p < 0.001). Smoking cessation and increased physical activity were reported by the majority of participants. In conclusion, cilostazol was shown to safely decrease pain symptoms and improve pain-free walking in PAD patients with IC in a real world setting. Benefits also occurred in terms of BP and lifestyle changes.

The Prognosis of Diabetic Foot Ulcer is Independent of age? A Comparative Analysis of the Characteristics of Patients with Diabetic Foot Ulcer in Different age Groups: A Cross-Sectional Study from China

Background: With younger onset age of type 2 diabetes mellitus (T2DM), the incidence of diabetic foot ulcer (DFU) in young and middle-aged adults is also increasing. Elucidating the distinctive characteristics of DFU in different ages and exploring the influence of age on the prognosis of DFU are crucial to the improvement of DFU treatments. Methods: 684 patients hospitalized for DFU in the department of endocrinology were recruited and assigned into the young and middle-aged group (age <65 years old) and the elderly group (age ≥65 years old). Demographic data and clinical features were compared between two groups. Results: Compared with the elderly group, the young and middle-aged group had higher proportion of males (72.3% vs 49.6%, P < .01) and smokers (52.5% vs 35.8%, P < .01), shorter duration of diabetes mellitus (155 months vs 196 months, P < .01), higher levels of glycosylated hemoglobin (9.3% vs 8.7%, P < .01), lower ratio of ankle-brachial index <0.9 (25.8% vs 51.1%, P < .01) and higher levels of c-reactive protein and erythrocyte sedimentation rate (14 mg/L vs 10 mg/L, P < .05; 36 mm/h vs 30 mm/h, P < .05). The prevalence of diabetic peripheral neuropathy and Wagner Grade were similar in two groups. Of note, the prognosis was similar in different age groups, as there were no significant differences in the healing rate (59.7% vs 60.1%, P > .05), healing time (30 days vs 22 days, P > .05) and minor amputation rate (11.9% vs 8.7%, P > .05). Conclusions: We found that no evidence to suggest a better prognosis with younger DFU patients. Compared with elderly ones, young and middle-aged patients were characterized by a higher proportion of smoking, worse glycemic control, higher inflammatory biomarkers but less severe lower limb ischemia, indicating that smoking cessation, strict blood glucose control and early detection of infection were crucial for improving the prognosis of young and middle-aged diabetic DFU patients.

The Genetic Architecture of the Etiology of Lower Extremity Peripheral Artery Disease: Current Knowledge and Future Challenges in the Era of Genomic Medicine

Lower extremity artery disease (LEAD), caused by atherosclerotic obstruction of the arteries of the lower limb extremities, has exhibited an increase in mortality and morbidity worldwide. The phenotypic variability of LEAD is correlated with its complex, multifactorial etiology. In addition to traditional risk factors, it has been shown that the interaction between genetic factors (epistasis) or between genes and the environment potentially have an independent role in the development and progression of LEAD. In recent years, progress has been made in identifying genetic variants associated with LEAD, by Genome-Wide Association Studies (GWAS), Whole Exome Sequencing (WES) studies, and epigenetic profiling. The aim of this review is to present the current knowledge about the genetic factors involved in the etiopathogenic mechanisms of LEAD, as well as possible directions for future research. We analyzed data from the literature, starting with candidate gene-based association studies, and then continuing with extensive association studies, such as GWAS and WES. The results of these studies showed that the genetic architecture of LEAD is extremely heterogeneous. In the future, the identification of new genetic factors will allow for the development of targeted molecular therapies, and the use of polygenic risk scores (PRS) to identify individuals at an increased risk of LEAD will allow for early prophylactic measures and personalized therapy to improve their prognosis.

Polyphenols–Gut–Heart: An Impactful Relationship to Improve Cardiovascular Diseases

A healthy gut provides the perfect habitat for trillions of bacteria, called the intestinal microbiota, which is greatly responsive to the long-term diet; it exists in a symbiotic relationship with the host and provides circulating metabolites, hormones, and cytokines necessary for human metabolism. The gut–heart axis is a novel emerging concept based on the accumulating evidence that a perturbed gut microbiota, called dysbiosis, plays a role as a risk factor in the pathogenesis of cardiovascular disease. Consequently, recovery of the gut microbiota composition and function could represent a potential new avenue for improving patient outcomes. Despite their low absorption, preclinical evidence indicates that polyphenols and their metabolites are transformed by intestinal bacteria and halt detrimental microbes’ colonization in the host. Moreover, their metabolites are potentially effective in human health due to antioxidant, anti-inflammatory, and anti-cancer effects. The aim of this review is to provide an overview of the causal role of gut dysbiosis in the pathogenesis of atherosclerosis, hypertension, and heart failure; to discuss the beneficial effects of polyphenols on the intestinal microbiota, and to hypothesize polyphenols or their derivatives as an opportunity to prevent and treat cardiovascular diseases by shaping gut eubiosis.

Immunosenescence in atherosclerosis: A role for chronic viral infections

Immune system is a versatile and dynamic body organ which offers survival and endurance of human beings in their hostile living environment. However, similar to other cells, immune cells are hijacked by senescence. The ageing immune cells lose their beneficial functions but continue to produce inflammatory mediators which draw other immune and non-immune cells to the senescence loop. Immunosenescence has been shown to be associated with different pathological conditions and diseases, among which atherosclerosis has recently come to light. There are common drivers of both immunosenescence and atherosclerosis; e.g. inflammation, reactive oxygen species (ROS), chronic viral infections, genomic damage, oxidized-LDL, hypertension, cigarette smoke, hyperglycaemia, and mitochondrial failure. Chronic viral infections induce inflammaging, sustained cytokine signaling, ROS generation and DNA damage which are associated with atherogenesis. Accumulating evidence shows that several DNA and RNA viruses are stimulators of immunosenescence and atherosclerosis in an interrelated network. DNA viruses such as CMV, EBV and HBV upregulate p16, p21 and p53 senescence-associated molecules; induce inflammaging, metabolic reprogramming of infected cells, replicative senescence and telomere shortening. RNA viruses such as HCV and HIV induce ROS generation, DNA damage, induction of senescence-associated secretory phenotype (SASP), metabolic reprogramming of infected cells, G1 cell cycle arrest, telomere shortening, as well as epigenetic modifications of DNA and histones. The newly emerged SARS-CoV-2 virus is also a potent inducer of cytokine storm and SASP. The spike protein of SARS-CoV-2 promotes senescence phenotype in endothelial cells by augmenting p16, p21, senescence-associated β-galactosidase (SA-β-Gal) and adhesion molecules expression. The impact of SARS-CoV-2 mega-inflammation on atherogenesis, however, remains to be investigated. In this review we focus on the common processes in immunosenescence and atherogenesis caused by chronic viral infections and discuss the current knowledge on this topic.

Cigarette smoke extract stimulates human pulmonary artery smooth muscle cell proliferation: Role of inflammation and oxidative stress

Objectives

Cigarette smoke may play a direct role in proliferation of human pulmonary artery smooth muscle cells (HPASMCs). However, the mechanism involved and the effect of interventions remain unclear. We aimed to evaluate the effect of cigarette smoke extract (CSE) on HPASMCs, explore the role of inflammation and oxidative stress, and the effects of Tempol and PDTC in this process.

Materials and Methods

HPASMCs were subjected to normal control (NC), CSE, CSE+Tempol (CSE+T), and CSE+PDTC (CSE+P) groups. Proliferation of HPASMCs was measured by CCK-8 and Western blot. TNF-α, IL-6, MDA, and SOD levels were determined by ELISA and commercial kits. Nuclear translocation of NF-κB p65 was evaluated by western blot.

Results

1%, 2.5%, and 5% CSE all promoted proliferation of HPASMCs, and effect of 1% CSE was the most significant, however, 7.5% and 10% CSE inhibited viability of cells (all P<0.05). Compared with the NC group, TNF-α, IL-6, and MDA levels increased, SOD activity decreased (all P<0.05), and NF-κB p65 expression in nuclei increased (P=0.04) in the CSE group. Tempol and PDTC inhibited the proliferation of HPASMCs induced by CSE (all P<0.05). And compared with the CSE group, TNF-α, IL-6, and MDA levels in CSE+T and CSE+P groups decreased, while SOD activity increased (all P<0.05). Tempol reduced the expression of NF-κB p65 in nuclei but did not achieve a significant difference (P=0.08). PDTC inhibited the nuclear translocation of NF-κB p65 (P=0.03).

Conclusion

CSE stimulates HPASMCs proliferation in a certain concentration range. The CSE-induced proliferation of HPASMCs involved excessive inflammatory response and oxidative stress. Tempol and PDTC attenuate these effects of CSE on HPASMCs.