Cigarette smoke alters lung vascular permeability and endothelial barrier function (2017 Grover Conference Series)

In-hospital outcome and its predictors among patients with acute cardiogenic pulmonary oedema at a tertiary hospital in Harar, Eastern Ethiopia: a retrospective cohort study

Background

Acute cardiogenic pulmonary oedema is highly associated with poor in-hospital outcomes. This study aimed to determine the in-hospital outcome and its predictors among patients with acute cardiogenic pulmonary oedema at a tertiary hospital in Harar, Eastern Ethiopia, from May 1 to 20, 2023.

Methods

A retrospective cohort study was employed among 204 patients with acute cardiogenic pulmonary oedema who were admitted between 1st May 2018 and 30th April 2023. The collected data were entered into Excel, and analysed using theSTATA software version 17. The hazard ratio with its 95% confidence interval was used and a P-value < 0.05 was considered a statistically significant association.

Results

The overall mortality rate was 17.60 (95% CI: 11.59-26.72) per 1000 person-day observation with mean (±SD) time to death was 2.88 (±2.06) days. Age (AHR: 1.35; 95% CI: 1.04-1.74 for every 10 years), being smoker (AHR: 3.26; 95% CI: 1.05-10.10), having respiratory rate of ≥40 breaths per minute (AHR: 5.46; 95% CI: 1.71-17.45), and having anaemia (AHR: 4.35; 95% CI: 1.23-15.33) were significant predictors of in-hospital mortality.

Conclusion

More than one in ten patients in this study died in the hospital. Therefore, special attention needs to be considered for patients with those predictors of in-hospital mortality.

Pulmonary veno-occlusive disease: illustrative cases and literature review

Pulmonary veno-occlusive disease (PVOD), also known as "pulmonary arterial hypertension (PAH) with overt features of venous/capillary involvement", is a rare cause of PAH characterised by substantial small pulmonary vein and capillary involvement, leading to increased pulmonary vascular resistance and right ventricular failure. Environmental risk factors have been associated with the development of PVOD, such as occupational exposure to organic solvents and chemotherapy, notably mitomycin. PVOD may also be associated with a mutation in the EIF2AK4 gene in heritable forms of disease. Distinguishing PVOD from PAH is critical for guiding appropriate management. Chest computed tomography typically displays interlobular septal thickening, ground-glass opacities and mediastinal lymphadenopathy. Life-threatening pulmonary oedema is a complication of pulmonary vasodilator therapy that can occur with any class of PAH drugs in PVOD. Early referral to a lung transplant centre is essential due to the poor response to therapy when compared with other forms of PAH. Histopathological analysis of lung explants reveals microvascular remodelling with typical fibrous veno-occlusive lesions. This review covers the main features distinguishing PVOD from PAH and two clinical cases that illustrate the challenges of PVOD management.

Diagnosis and management of pulmonary veno-occlusive disease

INTRODUCTION

Pulmonary veno-occlusive disease (PVOD) is an orphan disease and uncommon etiology of pulmonary arterial hypertension (PAH) characterized by substantial small pulmonary vein and capillary involvement.

AREAS COVERED

PVOD, also known as 'PAH with features of venous/capillary involvement' in the current ESC/ERS classification.

EXPERT OPINION

In recent years, particular risk factors for PVOD have been recognized, including genetic susceptibilities and environmental factors (such as exposure to occupational organic solvents, chemotherapy, and potentially tobacco). The discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD has been a breakthrough in understanding the molecular basis of PVOD. Venous and capillary involvement (PVOD-like) has also been reported to be relatively common in connective tissue disease-associated PAH (especially systemic sclerosis), and in rare pulmonary diseases like sarcoidosis and pulmonary Langerhans cell granulomatosis. Although PVOD and pulmonary arterial hypertension (PAH) exhibit similarities, including severe precapillary PH, it is essential to differentiate between them since PVOD has a worse prognosis and requires specific management. Indeed, PVOD patients are characterized by poor response to PAH-approved drugs, which can lead to pulmonary edema and clinical deterioration. Due to the lack of effective treatments, early referral to a lung transplantation center is crucial.

Nicotine promotes e-cigarette vapour-induced lung inflammation and structural alterations

BACKGROUND

Electronic cigarette (e-cigarette) vapour is gaining popularity as an alternative to tobacco smoking and can induce acute lung injury. However, the specific role of nicotine in e-cigarette vapour and its long-term effects on the airways, lung parenchyma and vasculature remain unclear.

RESULTS

In vitro exposure to nicotine-containing e-cigarette vapour extract (ECVE) or to nicotine-free e-cigarette vapour extract (NF ECVE) induced changes in gene expression of epithelial cells and pulmonary arterial smooth muscle cells (PASMCs), but ECVE in particular caused functional alterations (e.g. a decrease in human and mouse PASMC proliferation by 29.3±5.3% and 44.3±8.4%, respectively). Additionally, acute inhalation of nicotine-containing e-cigarette vapour (ECV) but not nicotine-free e-cigarette vapour (NF ECV) increased pulmonary endothelial permeability in isolated lungs. Long-term in vivo exposure of mice to ECV for 8 months significantly increased the number of inflammatory cells, in particular lymphocytes, compared to control and NF ECV in the bronchoalveolar fluid (BALF) (ECV: 853.4±150.8 cells·mL-1; control: 37.0±21.1 cells·mL-1; NF ECV: 198.6±94.9 cells·mL-1) and in lung tissue (ECV: 25.7±3.3 cells·mm-3; control: 4.8±1.1 cells·mm-3; NF ECV: 14.1±2.2 cells·mm-3). BALF cytokines were predominantly increased by ECV. Moreover, ECV caused significant changes in lung structure and function (e.g. increase in airspace by 17.5±1.4% compared to control), similar to mild tobacco smoke-induced alterations, which also could be detected in the NF ECV group, albeit to a lesser degree. In contrast, the pulmonary vasculature was not significantly affected by ECV or NF ECV.

CONCLUSIONS

NF ECV components induce cell type-specific effects and mild pulmonary alterations, while inclusion of nicotine induces significant endothelial damage, inflammation and parenchymal alterations.

Strain-dependent lung transcriptomic differences in cigarette smoke and LPS models of lung injury in mice

Cigarette smoking increases the risk of acute respiratory distress syndrome (ARDS; Calfee CS, Matthay MA, Eisner MD, Benowitz N, Call M, Pittet J-F, Cohen MJ. Am J Respir Crit Care Med 183: 1660-1665, 2011; Calfee CS, Matthay MA, Kangelaris KN, Siew ED, Janz DR, Bernard GR, May AK, Jacob P, Havel C, Benowitz NL, Ware LB. Crit Care Med 43: 1790-1797, 2015; Toy P, Gajic O, Bacchetti P, Looney MR, Gropper MA, Hubmayr R, Lowell CA, Norris PJ, Murphy EL, Weiskopf RB, Wilson G, Koenigsberg M, Lee D, Schuller R, Wu P, Grimes B, Gandhi MJ, Winters JL, Mair D, Hirschler N, Sanchez Rosen R, Matthay MA, TRALI Study Group. Blood 119: 1757-1767, 2012) and causes emphysema. However, it is not known why some individuals develop disease, whereas others do not. We found that smoke-exposed AKR mice were more susceptible to lipopolysaccharides (LPS)-induced acute lung injury (ALI) than C57BL/6 mice (Sakhatskyy P, Wang Z, Borgas D, Lomas-Neira J, Chen Y, Ayala A, Rounds S, Lu Q. Am J Physiol Lung Cell Mol Physiol 312: L56-L67, 2017); thus, we investigated strain-dependent lung transcriptomic responses to cigarette smoke (CS). Eight-week-old male AKR and C57BL/6 mice were exposed to 3 wk of room air (RA) or cigarette smoke (CS) for 6 h/day, 4 days/wk, followed by intratracheal instillation of LPS or normal saline (NS) and microarray analysis of lung homogenate gene expression. Other groups of AKR and C57 mice were exposed to RA or CS for 6 wk, followed by evaluation of static lung compliance and tissue elastance, morphometric evaluation for emphysema, or microarray analysis of lung gene expression. Transcriptomic analyses of lung homogenates show distinct strain-dependent lung transcriptional responses to CS and LPS, with AKR mice having larger numbers of genes affected than similarly treated C57 mice, congruent with strain differences in physiologic and inflammatory parameters previously observed in LPS-induced ALI after CS priming. These results suggest that genetic differences may underlie differing susceptibility of smokers to ARDS and emphysema. Strain-based differences in gene transcription contribute to CS and LPS-induced lung injury. There may be a genetic basis for smoking-related lung injury. Clinicians should consider cigarette smoke exposure as a risk factor for ALI and ARDS.NEW & NOTEWORTHY We demonstrate that transcriptomes expressed in lung homogenates also differ between the mouse strains and after acute (3 wk) exposure of animals to cigarette smoke (CS) and/or to lipopolysaccharide. Mouse strains also differed in physiologic, pathologic, and transcriptomic, responses to more prolonged (6 wk) exposure to CS. These data support a genetic basis for enhanced susceptibility to acute and chronic lung injury among humans who smoke cigarettes.

Connexins may play a critical role in cigarette smoke-induced pulmonary hypertension

Pulmonary hypertension (PH) is a chronic progressive disease characterized by pulmonary vasoconstriction and remodeling. It causes a gradual increase in pulmonary vascular resistance leading to right-sided heart failure, and may be fatal. Chronic exposure to cigarette smoke (CS) is an essential risk factor for PH group 3; however, smoking continues to be prevalent and smoking cessation is reported to be difficult. A majority of smokers exhibit PH, which leads to a concomitant increase in the risk of mortality. The current treatments for PH group 3 focus on vasodilation and long-term oxygen supplementation, and fail to stop or reverse PH-associated continuous vascular remodeling. Recent studies have suggested that pulmonary vascular endothelial dysfunction induced by CS exposure may be an initial event in the natural history of PH, which in turn may be associated with abnormal alterations in connexin (Cx) expression. The relationship between Cx and CS-induced PH development has not yet been directly investigated. Therefore, this review will describe the roles of CS and Cx in the development of PH and discuss the related downstream pathways. We also discuss the possible role of Cx in CS-induced PH. It is hoped that this review may provide new perspectives for early intervention.

Trichloroethylene increases pulmonary endothelial permeability: implication for pulmonary veno-occlusive disease

Trichloroethylene exposure is a major risk factor for pulmonary veno-occlusive disease. We demonstrated that trichloroethylene alters the endothelial barrier integrity, at least in part, through vascular endothelial (VE)-Cadherin internalisation, and suggested that this mechanism may play a role in the development of pulmonary veno-occlusive disease.

The effects of smoking on adolescent trauma patients: a propensity-score-matched analysis

PURPOSE

Cigarettes have been demonstrated to be toxic to the pulmonary connective tissue by impairing the lung's ability to clear debris, resulting in infection and acute respiratory distress syndrome (ARDS). Approximately 8% of adolescents are smokers. We hypothesized that adolescent trauma patients who smoke have a higher rate of ARDS and pneumonia when compared to non-smokers.

METHODS

The Trauma Quality Improvement Program (2014-2016) was queried for adolescent trauma patients aged 13-17 years. Adolescent smokers were 1:2 propensity-score-matched to non-smokers based on age, comorbidities, and injury type. Data were analyzed using chi square for categorical data and Mann-Whitney U test for continuous data.

RESULTS

From 32,610 adolescent patients, 997 (3.1%) were smokers. After matching, 459 smokers were compared to 918 non-smokers. There were no differences in matched characteristics. Compared to non-smokers, smokers had an increased rate of pneumonia (3.1% vs. 1.1%, p = 0.01) but not ARDS (0.2% vs. 0%, p = 0.16). Compared to the non-smoking group, the smokers had a longer median total hospital length-of-stay (3 vs. 2 days, p = 0.01) and no difference in overall mortality (1.5% vs. 2.4%, p = 0.29).

CONCLUSION

Smoking is associated with an increased rate of pneumonia in adolescent trauma patients. Future research should target smoking cessation and/or interventions to mitigate the deleterious effects of smoking in this population.