Total particulate matter concentration skews cigarette smoke's gene expression profile

Live to die another day: novel insights may explain the pathophysiology behind smoker's paradox in SARS-CoV-2 infection

The severe acute respiratory coronavirus 2 (SARS-CoV-2) infection demonstrates a highly variable and unpredictable course. Several reports have claimed a smoker's paradox in coronavirus disease 2019 (COVID-19), in line with previous suggestions that smoking is associated with better survival after acute myocardial infarction and appears protective in preeclampsia. Several plausible physiological explanations exist accounting for the paradoxical observation of smoking engendering protection against SARS-CoV-2 infection. In this review, we delineate novel mechanisms whereby smoking habits and smokers' genetic polymorphism status affecting various nitric oxide (NO) pathways (endothelial NO synthase, cytochrome P450 (CYP450), erythropoietin receptor (EPOR); β-common receptor (βcR)), along with tobacco smoke modulation of microRNA-155 and aryl-hydrocarbon receptor (AHR) effects, may be important determinators of SARS-CoV-2 infection and COVID-19 course. While transient NO bioavailability increase and beneficial immunoregulatory modulations through the above-mentioned pathways using exogenous, endogenous, genetic and/or therapeutic modalities may have direct and specific, viricidal SARS-CoV-2 effects, employing tobacco smoke inhalation to achieve protection equals self-harm. Tobacco smoking remains the leading cause of death, illness, and impoverishment.

Critical window for the association between prenatal environmental tobacco smoke exposure and preterm birth

Although environmental tobacco smoke (ETS) exposure is considered to be a severe public health problem and a modifiable risk factor for preterm birth (PTB), we still lack a comprehensive understanding of the PTB risk associated with trimester-specific prenatal ETS exposure. This study aimed to examine the accumulation of risk across trimester ETS exposure and the critical window of the association between maternal ETS exposure during pregnancy and PTB. A total of 63,038 mother-child pairs were involved in the analysis of the 2017 survey of Longhua Child Cohort Study. Information about socio-demographic characteristics, prenatal ETS exposure, and birth outcomes were collected using a self-report questionnaire. A series of logistic regression models were employed to assess the associations between prenatal ETS exposure and PTB. We found that maternal ETS exposure during pregnancy significantly increased the risk of PTB and this association increased with both the average level of daily ETS exposure and the number of trimesters of ETS exposure. Moreover, mothers who were initially exposed to ETS in the 1st trimester of pregnancy had significant higher risk of PTB (OR = 1.34, 95% CI: 1.25-1.44). Furthermore, mothers exposed to ETS in the 1st trimester only (OR = 1.26, 95%CI: 1.04-1.50), in both 1st and 2nd trimester (OR = 1.35, 95%CI: 1.08-1.67) and throughout pregnancy (OR = 1.35, 95%CI: 1.24-1.46) experienced a significantly high risk of PTB. Prenatal maternal ETS exposure during only the 2nd trimester also resulted in a high risk of PTB with marginal significance (OR = 1.33, 95% CI:0.78-2.13). To conclude, the 1st and early 2nd trimester might be the critical window for prenatal ETS exposure causing PTB.

Development and validation of a mouse model of contemporary cannabis smoke exposure

Cannabis is widely used for both recreational and medicinal purposes. Inhalation of combusted cannabis smoke is the most common mode of drug consumption, exposing the lungs to the pharmacologically active ingredients, including tetrahydrocannabinol (THC) and cannabidiol (CBD). While the relationship between cannabis smoke exposure and compromised respiratory health has yet to be sufficiently defined, previous investigations suggest that cannabis smoke may dysregulate pulmonary immunity. Presently, there exist few preclinical animal models that have been extensively validated for contemporary cannabis smoke exposure.

 To address this need, we developed a mouse model with readouts of total particulate matter, serum cannabinoid and carboxyhaemoglobin levels, lung cellular responses, and immune-mediator production.

 Using a commercially available smoke exposure system and a cannabis source material of documented THC/CBD composition, we exposed mice to a mean±sd total particulate matter of 698.89±66.09 µg·L⁻¹ and demonstrate increases in serum cannabinoids and carboxyhaemoglobin. We demonstrate that cannabis smoke modulates immune cell populations and mediators in both male and female BALB/c mice. This modulation is highlighted by increases in airway and lung tissue macrophage populations, including tissue-resident alveolar macrophages, monocyte-derived alveolar macrophages, and interstitial macrophage subpopulations. No changes in airway or lung tissue infiltration of neutrophils were observed. Immune-mediator analysis indicated significant upregulation of macrophage-derived chemokine, thymus and activation-regulated chemokine, and vascular endothelial growth factor within the lung tissue of cannabis smoke-exposed mice.

 This accessible and reproducible smoke-exposure model provides a foundation to explore the impact of chronic cannabis exposures and/or co-exposures with pathogens of clinical relevance, such as influenza.

Validation of the use of contemporary cannabis available on the legal market of known THC/CBD composition in a mouse model of smoke exposure with readouts of lung inflammationhttps://bit.ly/3okHWS4

Effects of Electronic Nicotine Delivery Systems and Cigarettes on Systemic Circulation and Blood-Brain Barrier: Implications for Cognitive Decline

Electronic nicotine delivery systems (often known as e-cigarettes) are a novel tobacco product with growing popularity, particularly among younger demographics. The implications for public health are twofold, as these products may represent a novel source of tobacco-associated disease but may also provide a harm reduction strategy for current tobacco users. There is increasing recognition that e-cigarettes impact vascular function across multiple organ systems. Herein, we provide a comparison of evidence regarding the role of e-cigarettes versus combustible tobacco in vascular disease and implications for blood-brain barrier dysfunction and cognitive decline. Multiple non-nicotinic components of tobacco smoke have been identified in e-cigarette aerosol, and their involvement in vascular disease is discussed. In addition, nicotine and nicotinic signaling may modulate peripheral immune and endothelial cell populations in a highly context-dependent manner. Direct preclinical evidence for electronic nicotine delivery system-associated neurovascular impairment is provided, and a model is proposed in which non-nicotinic elements exert a proinflammatory effect that is functionally antagonized by the presence of nicotine.

Level of serum IL-33 and emphysema paraseptal in clove cigarette smoker with spontaneous pneumothorax: A case report

A young male clove cigarette smoker experienced spontaneous pneumothorax and later paraseptal emphysema was detected on high-resolution computed tomography (HRCT) scan without respiratory symptoms. Smoking is a known risk factor for emphysema. Paraseptal emphysema is a type of emphysema that rarely causes respiratory symptoms, nevertheless, usually accompanied by spontaneous pneumothorax. Interleukin 33 (IL-33) is an alarmin cytokine that belongs to the IL-1 family. The effects of IL-33 depend on its structure. In its mature form, it is a cytokine alarmin that binds to ST2 (suppression of tumorigenicity) receptors on the surface of macrophages and innate immune cells to drive Th1/Th2 immune responses, causing oxidative stress, and increased IL-33 production causes polarization of alveolar macrophages to an M2 phenotype. In this study, long-term exposure to clove cigarette smoke caused an increased serum level of IL-33 (43.72 pg/mL) and paucigranulocytic airway inflammation. In paucigranulocytic inflammation, IL-33 is involved in lung parenchymal damage presumably through oxidative stress, activation of alveolar macrophage and increased MMP12 secretion, resulting in alveolar destruction and airspace enlargement.

Identification of Drug Candidates to Suppress Cigarette Smoke-induced Inflammation via Connectivity Map Analyses

Cigarette smoking is the main risk factor for chronic obstructive pulmonary disease, and to date, existing pharmacologic interventions have been ineffective at controlling inflammatory processes associated with the disease. To address this issue, we used the Connectivity Map (cMap) database to identify drug candidates with the potential to attenuate cigarette smoke-induced inflammation. We queried cMap using three independent in-house cohorts of healthy nonsmokers and smokers. Potential drug candidates were validated against four publicly available human datasets, as well as six independent datasets from cigarette smoke-exposed mice. Overall, these analyses yielded two potential drug candidates: kaempferol and bethanechol. Subsequently, the efficacy of each drug was validated in vivo in a model of cigarette smoke-induced inflammation. BALB/c mice were exposed to room air or cigarette smoke and treated with each of the two candidate drugs either prophylactically or therapeutically. We found that kaempferol, but not bethanechol, was able to reduce cigarette smoke-induced neutrophilia, both when administered prophylactically and when administered therapeutically. Mechanistically, kaempferol decreased expression of IL-1α and CXCL5 concentrations in the lung. Our data suggest that cMap analyses may serve as a useful tool to identify novel drug candidates against cigarette smoke-induced inflammation.

The Overlap of Lung Tissue Transcriptome of Smoke Exposed Mice with Human Smoking and COPD

Genome-wide mRNA profiling in lung tissue from human and animal models can provide novel insights into the pathogenesis of chronic obstructive pulmonary disease (COPD). While 6 months of smoke exposure are widely used, shorter durations were also reported. The overlap of short term and long-term smoke exposure in mice is currently not well understood, and their representation of the human condition is uncertain. Lung tissue gene expression profiles of six murine smoking experiments (n = 48) were obtained from the Gene Expression Omnibus (GEO) and analyzed to identify the murine smoking signature. The "human smoking" gene signature containing 386 genes was previously published in the lung eQTL study (n = 1,111). A signature of mild COPD containing 7 genes was also identified in the same study. The lung tissue gene signature of "severe COPD" (n = 70) contained 4,071 genes and was previously published. We detected 3,723 differentially expressed genes in the 6 month-exposure mice datasets (FDR <0.1). Of those, 184 genes (representing 48% of human smoking) and 1,003 (representing 27% of human COPD) were shared with the human smoking-related genes and the COPD severity-related genes, respectively. There was 4-fold over-representation of human and murine smoking-related genes (P = 6.7 × 10^-26) and a 1.4 fold in the severe COPD -related genes (P = 2.3 × 10^-12). There was no significant enrichment of the mice and human smoking-related genes in mild COPD signature. These data suggest that murine smoke models are strongly representative of molecular processes of human smoking but less of COPD.

Tobacco Smoke Induces and Alters Immune Responses in the Lung Triggering Inflammation, Allergy, Asthma and Other Lung Diseases: A Mechanistic Review

Many studies have been undertaken to reveal how tobacco smoke skews immune responses contributing to the development of chronic obstructive pulmonary disease (COPD) and other lung diseases. Recently, environmental tobacco smoke (ETS) has been linked with asthma and allergic diseases in children. This review presents the most actual knowledge on exact molecular mechanisms responsible for the skewed inflammatory profile that aggravates inflammation, promotes infections, induces tissue damage, and may promote the development of allergy in individuals exposed to ETS. We demonstrate how the imbalance between oxidants and antioxidants resulting from exposure to tobacco smoke leads to oxidative stress, increased mucosal inflammation, and increased expression of inflammatory cytokines (such as interleukin (IL)-8, IL-6 and tumor necrosis factor α ([TNF]-α). Direct cellular effects of ETS on epithelial cells results in increased permeability, mucus overproduction, impaired mucociliary clearance, increased release of proinflammatory cytokines and chemokines, enhanced recruitment of macrophages and neutrophils and disturbed lymphocyte balance towards Th2. The plethora of presented phenomena fully justifies a restrictive policy aiming at limiting the domestic and public exposure to ETS.

Targeting Interleukin-17 signalling in cigarette smoke-induced lung disease: Mechanistic concepts and therapeutic opportunities

It is widely accepted that compromised lung function in chronic obstructive pulmonary disease (COPD) is, at least in part, a consequence of persistent airway inflammation caused by particles and noxious gases present in cigarette smoke and indoor air pollution from burning biomass fuel. Currently, the World Health Organization estimates that 80 million people have moderate or severe COPD worldwide. While there is a global need for effective medical treatment, current therapeutic interventions have shown limited success in preventing disease pathology and progression. This is, in large part, due to the complexity and heterogeneity of COPD, and an incomplete understanding of the molecular mechanisms governing inflammatory processes in individual patients. This review discusses recent discoveries related to the pro-inflammatory cytokine interleukin (IL)-17A, and its potential role in the pathogenesis of COPD. We propose that an intervention strategy targeting IL-17 signalling offers an exciting opportunity to mitigate inflammatory processes, and prevent the progression of tissue pathologies associated with COPD.