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Prior cigarette smoke exposure does not affect acute post-stroke outcomes in mice.

ABSTRACT: Chronic obstructive pulmonary disease (COPD) is currently the third leading cause of death globally and is characterized by airflow limitation that is progressive and not fully reversible. Cigarette smoking is the major cause of COPD. Fifty percent of deaths in the COPD population are due to a cardiovascular event and it is now recognised that COPD is a risk factor for stroke. Whether COPD increases stroke severity has not been explored. The aim of this study was to investigate whether functional and histological endpoints of stroke outcomes in mice after transient middle cerebral artery occlusion (tMCAo) were more severe in mice exposed to cigarette smoke (CS). 7-week-old male C57BL/6 mice were exposed to room air or CS generated from 9 cigarettes/day, 5 days/week for 2, 8 and 12 weeks. Following air or CS exposure, mice underwent tMCAO surgery with an ischaemic period of 30-40 min or sham surgery. Mice were euthanised 24 h following the induction of ischaemia and bronchoalveolar lavage fluid (BALF), lungs and brains collected. Mice exposed to CS for 2 weeks and subjected to a stroke had similar BALF macrophages to air-exposed and stroke mice. However, CS plus stroke mice had significantly more BALF total cells, neutrophils and lymphocytes than air plus stroke mice. Mice exposed to CS for 8 and 12 weeks had significantly greater BALF total cells, macrophages, neutrophils and lymphocytes than air-exposed mice, but stroke did not affect CS-induced BALF cellularity. Prior CS exposure did not worsen stroke-induced neurological deficit scores, reduced foregrip strength, infarct and oedema volumes. Collectively, we found that although CS exposure caused significant BALF inflammation, it did not worsen acute post-stroke outcomes in mice. This data suggests that while patients with COPD are at increased risk of stroke, it may not translate to COPD patients having more severe stroke outcomes.

SUBMITTER: Austin V

PROVIDER: S-EPMC6428410 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Prior cigarette smoke exposure does not affect acute post-stroke outcomes in mice.

Austin Victoria V Miller Alyson A Vlahos Ross R

PloS one 20190321 3

Chronic obstructive pulmonary disease (COPD) is currently the third leading cause of death globally and is characterized by airflow limitation that is progressive and not fully reversible. Cigarette smoking is the major cause of COPD. Fifty percent of deaths in the COPD population are due to a cardiovascular event and it is now recognised that COPD is a risk factor for stroke. Whether COPD increases stroke severity has not been explored. The aim of this study was to investigate whether functiona ...[more]

PMID: 30897180

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Project description:The association between cigarette smoke exposure and the acute respiratory distress syndrome in patients with the most common acute respiratory distress syndrome risk factors of sepsis, pneumonia, and aspiration has not been well studied. The goal of this study was to test the association between biomarker-confirmed cigarette smoking and acute respiratory distress syndrome in a diverse cohort.Prospective cohort.Tertiary care center.Four hundred twenty-six critically ill patients with acute respiratory distress syndrome risk factors (excluding trauma and transfusion): None.We obtained smoking histories and measured urine 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanol (a biomarker of cigarette smoke exposure) on urine samples obtained at the time of study enrollment. The association between cigarette smoke exposure and acute respiratory distress syndrome differed based on acute respiratory distress syndrome risk factor (p < 0.02 for interaction). In patients with nonpulmonary sepsis as the primary acute respiratory distress syndrome risk factor (n = 212), 39% of those with acute respiratory distress syndrome were current smokers by history compared with 22% of those without acute respiratory distress syndrome (odds ratio, 2.28; 95% CI, 1.24-4.19; p = 0.008). Likewise, cigarette smoke exposure as measured by urine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol was significantly associated with acute respiratory distress syndrome in this group. The increased risk of acute respiratory distress syndrome in nonpulmonary sepsis was restricted to patients with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol levels consistent with active smoking and was robust to adjustment for other acute respiratory distress syndrome predictors. Cigarette smoke exposure as measured by history or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol was not associated with acute respiratory distress syndrome in patients with other risk factors (e.g., pneumonia and aspiration).Cigarette smoking measured both by history and biomarker is associated with an increased risk of acute respiratory distress syndrome in patients with nonpulmonary sepsis. This finding has important implications for tobacco product regulation and for understanding the pathogenesis of acute respiratory distress syndrome.

Project description:BACKGROUND:Cognitive impairment is an important consequence of stroke and transient ischaemic attack, but its determinants are not fully understood. Simple univariable or multivariable models have not shown clinical utility for predicting cognitive impairment. Cardiovascular risk factors may influence cognition through multiple, direct, and indirect pathways, including effects on prior cognition and stroke severity. Understanding these complex relationships may help clinical teams plan intervention and follow-up strategies. METHODS:We analysed clinical and demographic data from consecutive patients admitted to an acute stroke ward. Cognitive assessment comprised Abbreviated Mental Test and mini-Montreal Cognitive Assessment. We constructed bias-corrected confidence intervals to test indirect effects of cardiovascular risk factors (hypertension, vascular disease, atrial fibrillation, diabetes mellitus, previous stroke) on cognitive function, mediated through stroke severity and history of dementia, and we assessed moderation effects due to comorbidity. RESULTS:From 594 eligible patients, we included 587 in the final analysis (age range 26-100; 45% female). Our model explained R2?=?62.10% of variance in cognitive test scores. We found evidence for an indirect effect of previous stroke that was associated with increased risk of prevalent dementia and in turn predicted poorer cognitive score (estimate?=?-?0.39; 95% bias-corrected CI, -?0.75 to -?0.13; p?=?0.02). Atrial fibrillation was associated with greater stroke severity and in turn with a poorer cognitive score (estimate?=?-?0.27; 95% bias-corrected CI, -?0.49 to -?0.05; p?=?0.02). Conversely, previous TIA predicted decreased stroke severity and, through that, lesser cognitive impairment (estimate?=?0.38; 95% bias-corrected CI, 0.08 to 0.75; p?=?0.02). Through an association with reduced stroke severity, vascular disease was associated with lesser cognitive impairment, conditional on presence of hypertension and absence of diabetes mellitus (estimate?=?0.36; 95% bias-corrected CI, 0.03 to 0.68; p?=?0.02), although the modelled interaction effects did not reach statistical significance. CONCLUSIONS:We have shown that relationships between cardiovascular risk factors and cognition are complex and simple multivariable models may be overly reductionist. Including direct and indirect effects of risk factors, we constructed a model that explained a substantial proportion of variation in cognitive test scores. Models that include multiple paths of influence and interactions could be used to create dementia prognostic tools for use in other healthcare settings.

Project description:IntroductionCigarette smoking (CS) remains a major public health concern and has recently been associated with an increased risk of developing acute respiratory distress syndrome (ARDS). Bronchoalveolar lavage (BAL) experiments in human volunteers have demonstrated that active smokers develop increased alveolar-epithelial barrier permeability to protein after inhaling lipopolysaccharide (LPS). Here we tested the hypothesis that short-term whole-body CS exposure would increase LPS-induced lung edema in mice.MethodsAdult mice were exposed in a Teague TE-10 machine to CS from 3R4F cigarettes at 100 mg/m3 total suspended particulates for 12 days, then given LPS or saline intratracheally. Control mice were housed in the same room without CS exposure. Post-mortem measurements included gravimetric lung water and BAL protein, cell counts, and lung histology. Cytokines were measured in lung homogenate by ELISA and in plasma by Luminex and ELISA.ResultsIn CS-exposed mice, intratracheal LPS caused greater increases in pulmonary edema by gravimetric measurement and histologic scoring. CS-exposed mice also had an increase in BAL neutrophilia, lung IL-6, and plasma CXCL9, a T-cell chemoattractant. Intratracheal LPS concentrated blood hemoglobin to a greater degree in CS-exposed mice, consistent with an increase in systemic vascular permeability.ConclusionsThese results demonstrate that CS exposure in endotoxin injured mice increases the severity of acute lung injury. The increased lung IL-6 in CS-exposed LPS-injured mice indicates that this potent cytokine, previously shown to predict mortality in patients with ARDS, may play a role in exacerbating lung injury in smokers and may have utility as a biomarker of tobacco-related lung injury.ImplicationsOur results suggest that short-term CS exposure at levels that cause no overt lung injury may still prime the lung for acute inflammatory damage from a "second hit", a finding that mirrors the increased risk of developing ARDS in patients who smoke. This model may be useful for evaluating the acute pulmonary toxicity of existing and/or novel tobacco products and identifying biomarkers of tobacco-related lung injury.

Project description:Although smokers have increased susceptibility and severity of seasonal influenza virus infection, there is no report about the risk of 2009 pandemic H1N1 (pdmH1N1) or avian H9N2 (H9N2/G1) virus infection in smokers. In our study, we used mouse model to investigate the effect of cigarette smoke on pdmH1N1 or H9N2 virus infection. Mice were exposed to cigarette smoke for 21 days and then infected with pdmH1N1 or H9N2 virus. Control mice were exposed to air in parallel. We found that cigarette smoke exposure alone significantly upregulated the lung inflammation. Such prior cigarette smoke exposure significantly reduced the disease severity of subsequent pdmH1N1 or H9N2 virus infection. For pdmH1N1 infection, cigarette smoke exposed mice had significantly lower mortality than the control mice, possibly due to the significantly decreased production of inflammatory cytokines and chemokines. Similarly, after H9N2 infection, cigarette smoke exposed mice displayed significantly less weight loss, which might be attributed to lower cytokines and chemokines production, less macrophages, neutrophils, CD4+ and CD8+ T cells infiltration and reduced lung damage compared to the control mice. To further investigate the underlying mechanism, we used nicotine to mimic the effect of cigarette smoke both in vitro and in vivo. Pre-treating the primary human macrophages with nicotine for 72 h significantly decreased their expression of cytokines and chemokines after pdmH1N1 or H9N2 infection. The mice subcutaneously and continuously treated with nicotine displayed significantly less weight loss and lower inflammatory response than the control mice upon pdmH1N1 or H9N2 infection. Moreover, ?7 nicotinic acetylcholine receptor knockout mice had more body weight loss than wild-type mice after cigarette smoke exposure and H9N2 infection. Our study provided the first evidence that the pathogenicity of both pdmH1N1 and H9N2 viruses was alleviated in cigarette smoke exposed mice, which might partially be attributed to the immunosuppressive effect of nicotine.

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Prior cigarette smoke exposure does not affect acute post-stroke outcomes in mice.

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Prior cigarette smoke exposure does not affect acute post-stroke outcomes in mice.

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