A review of current knowledge on Pollution, Cigarette Smoking and COVID-19 diffusion and their relationship with inflammation

Smoking as a Risk or Protective Factor in Developing and Severity of COVID-19?

Background: Many studies have discussed the relationship between COVID-19 and smoking, but they include many contradictory findings. This study evaluates the relationship between smoking and the incidence and severity of COVID-19 patients in Shahroud City, Iran. Methods: We conducted a cross-sectional analytical study using COVID-19 data. All suspected cases were referred to the registered centers at Shahroud University of Medical Sciences from 21 January 2020 to 20 March 2021. Multivariable logistic regression was conducted to evaluate the relationship between smoking and SARS-COV 2 confirmed cases, and its severity. Results: Overall, it was confirmed that 22.6% of smokers had positive COVID-19 PCR tests compared to 42.1% of non-smokers. COVID-19 is a public health problem, and the results showed that there was a relationship between smoking and COVID-19 confirmed cases and severity. The results showed that smoking, adjusting for other related factors, reduces the odds of COVID-19 by 58%, but increases the odds of severe disease by 89%. Conclusions: In this study, smoking was significantly associated with a low chance of developing COVID-19 disease but higher odds of severity. These significant results were reported even in the presence of under-reporting of smoking by patients, which underestimates the association. These results should not be ignored, and further studies are needed.

Electronic Cigarette Use and the Risk of Cardiovascular Diseases

Electronic cigarettes or e-cigarettes are the most frequently used tobacco product among adolescents. Despite the widespread use of e-cigarettes and the known detrimental cardiac consequences of nicotine, the effects of e-cigarettes on the cardiovascular system are not well-known. Several in vitro and in vivo studies delineating the mechanisms of the impact of e-cigarettes on the cardiovascular system have been published. These include mechanisms associated with nicotine or other components of the aerosol or thermal degradation products of e-cigarettes. The increased hyperlipidemia, sympathetic dominance, endothelial dysfunction, DNA damage, and macrophage activation are prominent effects of e-cigarettes. Additionally, oxidative stress and inflammation are unifying mechanisms at many levels of the cardiovascular impairment induced by e-cigarette exposure. This review outlines the contribution of e-cigarettes in the development of cardiovascular diseases and their molecular underpinnings.

Proinflammatory Responses of 1-Nitropyrene against RAW264.7 Macrophages through Akt Phosphorylation and NF-κB Pathways

Air pollution is a major environmental and public health problem worldwide. A nitro-polycyclic aromatic hydrocarbon and the most abundant air pollutant in diesel engine exhaust, 1-nitropyrene (1-NP), is caused by the incomplete combustion of carbonaceous organic substances. Macrophages are effector cells of the innate immune cells that provide resistance in the peripheral tissue. The overactivation of macrophages results in inflammation. The generation of proinflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumour necrosis factor alpha, is induced by 1-NP in a concentration-dependent manner in macrophages. In this study, the production of proinflammatory mediators, such as nitrogen oxide and prostaglandin E2, was induced by 1-NP in a concentration-dependent manner through the expression of iNOS and COX2. The generation of proinflammatory cytokines, iNOS, and COX2 was induced by 1-NP through nuclear factor (NF)-κB p65 phosphorylation and the degradation of its upstream factor, IκB. Finally, Akt phosphorylation was induced by 1-NP in a concentration-dependent manner. These findings suggest that 1-NP exhibits a proinflammatory response through the NF-κB pathway activation due to Akt phosphorylation.

Vehicle emissions-exposure alters expression of systemic and tissue-specific components of the renin-angiotensin system and promotes outcomes associated with cardiovascular disease and obesity in wild-type C57BL/6 male mice

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Vehicle emission-exposure increases systemic and adipose renin-angiotensin signaling.

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Emission-exposure promotes renal, vascular, and adipocyte AT1 receptor expression.

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Diet and emission-exposure are associated with adipocyte hypertrophy and weight gain.

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Emission-exposure promotes expression of adipokines and adipose inflammatory factors.

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High-fat diet promotes an obese adipose phenotype, exacerbated by emission-exposure.

Exposure to air pollution from traffic-generated sources is known to contribute to the etiology of inflammatory diseases, including cardiovascular disease (CVD) and obesity; however, the signaling pathways involved are still under investigation. Dysregulation of the renin-angiotensin system (RAS) can contribute to CVD and alter lipid storage and inflammation in adipose tissue. Our previous exposure studies revealed that traffic-generated emissions increase RAS signaling, further exacerbated by a high-fat diet. Thus, we investigated the hypothesis that exposure to engine emissions increases systemic and local adipocyte RAS signaling, promoting the expression of factors involved in CVD and obesity. Male C57BL/6 mice (6–8 wk old) were fed either a high-fat (HF, n = 16) or low-fat (LF, n = 16) diet, beginning 30d prior to exposures, and then exposed via inhalation to either filtered air (FA, controls) or a mixture of diesel engine + gasoline engine vehicle emissions (MVE: 100 μg PM/m³) via whole-body inhalation for 6 h/d, 7 d/wk, 30d. Endpoints were assessed via immunofluorescence and RT-qPCR. MVE-exposure promoted vascular adhesion factors (VCAM-1, ICAM-1) expression, monocyte/macrophage sequestration, and oxidative stress in the vasculature, associated with increased angiotensin II receptor type 1 (AT1) expression. In the kidney, MVE-exposure promoted the expression of renin, AT1, and AT2 receptors. In adipose tissue, both HF-diet and MVE-exposure mediated increased epididymal fat pad weight and adipocyte hypertrophy, associated with increased angiotensinogen and AT1 receptor expression; however, these outcomes were further exacerbated in the MVE + HF group. MVE-exposure also induced inflammation, monocyte chemoattractant protein (MCP)-1, and leptin, while reducing insulin receptor and glucose transporter, GLUT4, expression in adipose tissue. Our results indicate that MVE-exposure promotes systemic and local adipose RAS signaling, associated with increased expression of factors contributing to CVD and obesity, further exacerbated by HF diet consumption.