Lung injury after cigarette smoking is particle related

Cigarette smoking decreases macrophage-dependent clearance to impact the biological effects of occupational and environmental particle exposures

The retention of occupational and environmental particles in the lung is a primary determinant of biological effects. In the distal respiratory tract, particle clearance includes phagocytosis by alveolar macrophages (AMs), migration to the terminal bronchiole, and transport of AMs and particles by the mucociliary escalator. With increasing particle exposure, a focal collection of particle-laden macrophages results at the respiratory bronchiole (RB) which is that site in the clearance pathway demanding the greatest traverse by these cells after a commencement from the alveoli. With the greatest particle doses, there is "particle overload" and impaired mobility which is reflected by an excess accumulation of particle-laden macrophages throughout the RBs, alveolar ducts, and alveoli. With deposition of fibrous particles in the distal respiratory tract, the AM is unable to extend itself to enclose fibers with a major diameter of 10-20 microns or longer resulting in "frustrated phagocytosis" and longer retention times. Clearance pathways for particles are shared. There can be a summation of particle exposures with exhaustion in the capacity of the AMs for transport. Cigarette smoking (CS) is the greatest particle challenge humans encounter. Associated with its enormous magnitude, CS profoundly impacts the clearance pathways and subsequently interacts with other particle exposures to increase biological effects. Interstitial lung disease, pulmonary function, chronic obstructive pulmonary disease, infections, lung cancer, and mortality can be altered among smokers exposed to occupational and environmental particles (e.g., silica, coal mine dust, air pollution particles, other particles, and asbestos). It is concluded that both decreasing CS and controlling particle exposures are of vital importance in occupational and environmental lung disease.

Prenatal and Postnatal Cigarette Smoke Exposure Is Associated With Increased Risk of Exacerbated Allergic Airway Immune Responses: A Preclinical Mouse Model

Increased exposure to household air pollution and ambient air pollution has become one of the world’s major environmental health threats. In developing and developed countries, environmental cigarette smoke (CS) exposure is one of the main sources of household air pollution (HAP). Moreover, results from different epidemiological and experimental studies indicate that there is a strong association between HAP, specifically CS exposure, and the development of allergic diseases that often persists into later life. Here, we investigated the impact of prenatal and postnatal CS exposure on offspring susceptibility to the development of allergic airway responses by using a preclinical mouse model. Pregnant BALB/c mice were exposed to either CS or air during pregnancy and lactation and in order to induce allergic asthma the offspring were sensitized and challenged with house dust mite (HDM). Decreased lung function parameters, like dynamic compliance and pleural pressure, were observed in PBS-treated offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. Maternal CS exposure significantly increased the HDM-induced airway eosinophilia and neutrophilia in the offspring. Prenatal and postnatal CS exposure increased the frequency of Th2 cells in the lungs of HDM-treated offspring compared to offspring born to air-exposed mothers. Offspring born to CS-exposed mothers showed increased levels of IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid compared to offspring from air-exposed mothers. Ex-vivo restimulation of lung cells isolated from HDM-treated offspring born to CS-exposed mothers also resulted in increased IL-4 production. Finally, serum immunoglobulins levels of HDM-specific IgE and HDM-specific IgG1 were significantly increased upon a HDM challenge in offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. In summary, our results reveal a biological plausibility for the epidemiological studies indicating that prenatal and postnatal CS exposure increases the susceptibility of offspring to allergic immune responses.

Impact of fossil fuel emissions and particulate matter on pulmonary health

In recent decades, several national and international legislative efforts have aimed to improve air quality standards and limit major pollutants, such as carbon monoxide, sulfur dioxide, and nitrogen dioxide, linked to several public health problems. In recent years, particulate matter sources have become an important cause of several pulmonary and systemic diseases. Specifically, several studies examining cigarette smoke particulates have discovered the important contribution that mast cells play in the pathogenesis and progression of smoking-related lung disease and other particulate matter-related lung injury. By understanding the mechanisms of activation and signaling cascades involved in cigarette smoke and mast cell activation, novel pharmacological therapies for particulate matter-induced lung diseases could be developed.

Smoking is associated with an improved short-term outcome in patients with rib fractures

BACKGROUND

Smokers with cardiovascular disease have been reported to have decreased mortality compared to non-smokers. Rib fractures are associated with significant underlying injuries such as lung contusions, lacerations, and/or pneumothoraces. We hypothesized that blunt trauma patients with rib fractures who are smokers have decreased ventilator days and risk of in-hospital mortality compared to non-smokers.

STUDY DESIGN

The Trauma Quality Improvement Program (2010-2016) was queried for patients presenting with a blunt rib fracture. Patients that died within 24 h of admission were excluded. A multivariable logistic regression model was performed.

RESULTS

From 282,986 patients with rib fractures, 57,619 (20.4%) were smokers. Compared to non-smokers with rib fractures, smokers had a higher median injury severity score (17 vs. 16, p < 0.001). Smokers had a higher rate of pneumonia (7.5% vs. 6.6%, p < 0.001), however, less ventilator days (5 vs. 6, p = 0.04), and lower in-hospital mortality rate (2.3% vs. 4.6%, p < 0.001), compared to non-smokers. After controlling for covariates, smokers with rib fractures were associated with a decreased risk for in-hospital mortality compared to non-smokers with rib fractures (OR 0.64, 0.56-0.73, p < 0.001).

CONCLUSION

Despite having more severe injuries and increased rates of pneumonia, smokers with rib fractures were associated with nearly a 40% decreased risk of in-hospital mortality and one less ventilator day compared to non-smokers. The long-term detrimental effects of smoking have been widely established. However, the biologic and pathophysiologic adaptations that smokers have may confer a survival benefit when recovering in the hospital from chest wall trauma. This study was limited by the database missing the number of pack-years smoked. Future prospective studies are needed to confirm this association and elucidate the physiologic mechanisms that may explain these findings.

Smoking-induced iron dysregulation in the lung

Iron is one of the most abundant transition elements and is indispensable for almost all organisms. While the ability of iron to participate in redox chemistry is an essential requirement for participation in a range of vital enzymatic reactions, this same feature of iron also makes it dangerous in the generation of hydroxyl radicals and superoxide anions. Given the high local oxygen tensions in the lung, the regulation of iron acquisition, utilization, and storage therefore becomes vitally important, perhaps more so than in any other biological system. Iron plays a critical role in the biology of essentially every cell type in the lung, and in particular, changes in iron levels have important ramifications on immune function and the local lung microenvironment. There is substantial evidence that cigarette smoke causes iron dysregulation, with the implication that iron may be the link between smoking and smoking-related lung diseases. A better understanding of the connection between cigarette smoke, iron, and respiratory diseases will help to elucidate pathogenic mechanisms and aid in the identification of novel therapeutic targets.

Iron Homeostasis in the Lungs-A Balance between Health and Disease

A strong mechanistic link between the regulation of iron homeostasis and oxygen sensing is evident in the lung, where both systems must be properly controlled to maintain lung function. Imbalances in pulmonary iron homeostasis are frequently associated with respiratory diseases, such as chronic obstructive pulmonary disease and with lung cancer. However, the underlying mechanisms causing alterations in iron levels and the involvement of iron in the development of lung disorders are incompletely understood. Here, we review current knowledge about the regulation of pulmonary iron homeostasis, its functional importance, and the link between dysregulated iron levels and lung diseases. Gaining greater knowledge on how iron contributes to the pathogenesis of these diseases holds promise for future iron-related therapeutic strategies.

Acute Effects of Whole-Body Vibration on Inflammatory Markers in People with Chronic Obstructive Pulmonary Disease: A Pilot Study

Whole-body vibration (WBV) has gained prominence in the rehabilitation of individuals with chronic obstructive pulmonary disease (COPD) because it is a safe and low intensity exercise that promises beneficial effects on physical performance and quality of life. However, its effects on plasma cytokine levels in COPD are still unclear. The aim of the current study was to investigate the acute effects of WBV on inflammatory biomarkers in people with COPD. Twenty-six participants, COPD people (n=13) and healthy controls (n=13), were included. Both groups performed WBV at amplitude of 2 mm and frequency of vibration of 35 Hz, during six series of 30 seconds. They were assessed for lung function, body composition, 6-minute walking test (6MWT), handgrip strength test, plasma concentrations of interleukin (IL), IL-6, IL-8, and IL-10, and soluble tumor necrosis factor alpha (TNF-α) receptors (sTNFR-1 and sTNFR-2). People with COPD had moderate disease [forced expiratory volume in the first second (FEV1) = 58.1%], as well as a worse performance in the 6MWT. The plasma cytokine profile at rest showed that participants with COPD had higher levels of IL-8 and lower levels of IL-10. After one session of WBV, we found an increased plasma IL-10 level in the COPD group, with similar levels for healthy controls. One session of WBV modified the plasma IL-10 level. No effects were found on the other investigated cytokines.

Oxidative stress and skeletal muscle dysfunction are present in healthy smokers

Chronic exposure to cigarette smoke seems to be related to an increase of pro-inflammatory cytokines, oxidative stress and changes in muscular and physical performances of healthy smokers. However, these parameters have not yet been evaluated simultaneously in previous studies. The participants of this study were healthy males divided into two groups: smokers (n=20) and non-smokers (n=20). Inflammation was evaluated by measuring plasma levels of the cytokines IL-10, IL-6 e TNF-α, and of the soluble receptors sTNFR1 and sTNFR2. Oxidative stress was evaluated by determination of thiobarbituric acid reactive substances (TBARS) plasma levels, total antioxidant capacity of plasma and erythrocytes activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase. Muscular performance was evaluated by measuring the peak torque of knee flexors and extensors, and by determining the total work of the knee extensors. Physical performance was assessed by measuring the peak oxygen uptake (VO2 peak), the maximum heart rate (HRmax) and the walking distance in the shuttle walking test. Smokers showed an increase in the levels of the sTNFR1 and TBARS and a decrease in the total antioxidant capacity of plasma, in the catalase activity and in the total work (P<0.05). IL-6, IL-10, sTNFR2, SOD, peak torque, VO2 peak, HRmax and walking distance were similar between groups. Smokers presented increased oxidative stress and skeletal muscle dysfunction, demonstrating that the changes in molecular and muscular parameters occur simultaneously in healthy smokers.

Electronic cigarette aerosol induces significantly less cytotoxicity than tobacco smoke

Electronic cigarettes (E-cigarettes) are a potential means of addressing the harm to public health caused by tobacco smoking by offering smokers a less harmful means of receiving nicotine. As e-cigarettes are a relatively new phenomenon, there are limited scientific data on the longer-term health effects of their use. This study describes a robust in vitro method for assessing the cytotoxic response of e-cigarette aerosols that can be effectively compared with conventional cigarette smoke. This was measured using the regulatory accepted Neutral Red Uptake assay modified for air-liquid interface (ALI) exposures. An exposure system, comprising a smoking machine, traditionally used for in vitro tobacco smoke exposure assessments, was adapted for use with e-cigarettes to expose human lung epithelial cells at the ALI. Dosimetric analysis methods using real-time quartz crystal microbalances for mass, and post-exposure chemical analysis for nicotine, were employed to detect/distinguish aerosol dilutions from a reference Kentucky 3R4F cigarette and two commercially available e-cigarettes (Vype eStick and ePen). ePen aerosol induced 97%, 94% and 70% less cytotoxicity than 3R4F cigarette smoke based on matched EC50 values at different dilutions (1:5 vs. 1:153 vol:vol), mass (52.1 vs. 3.1 μg/cm2) and nicotine (0.89 vs. 0.27 μg/cm2), respectively. Test doses where cigarette smoke and e-cigarette aerosol cytotoxicity were observed are comparable with calculated daily doses in consumers. Such experiments could form the basis of a larger package of work including chemical analyses, in vitro toxicology tests and clinical studies, to help assess the safety of current and next generation nicotine and tobacco products.

Cytotoxicity and mutagenicity of sidestream cigarette smoke particulate matter of different particle sizes

Sidestream cigarette smoke, the major component of environmental tobacco smoke, is a complex and reactive aerosol. The particulate matter (PM) in sidestream smoke is one of the carriers of chemical constituents. However, particle size-dependent toxicological effects of PM are poorly understood. In this study, we evaluated the relationship between the PM size and in vitro cytotoxicity and mutagenicity of sidestream cigarette smoke. A NanoMoudi-II(™) 125A was used to collect PM samples ranging from 10 nm to 10 μm. The in vitro toxicity of PM was evaluated using a neutral red cytotoxicity assay and Salmonella mutagenicity assay. The results showed that the cytotoxicity and mutagenicity of PM larger than 1 μm was significantly lower than PM sized 10 nm-1 μm. Furthermore, there was a noticeable trend that the smaller the size of the PM of sidestream cigarette smoke, the greater the toxicity. This study suggests that the toxicity of PM in sidestream cigarette smoke is size-dependent.

An evolutionary medicine approach to understanding factors that contribute to chronic obstructive pulmonary disease

Although many studies have been published on the causes and mechanisms of chronic obstructive pulmonary disease (COPD), the reason for the existence of COPD and the reasons why COPD develops in humans have hardly been studied. Evolutionary medical approaches are required to explain not only the proximate factors, such as the causes and mechanisms of a disease, but the ultimate (evolutionary) factors as well, such as why the disease is present and why the disease develops in humans. According to the concepts of evolutionary medicine, disease susceptibility is acquired as a result of natural selection during the evolutionary process of traits linked to the genes involved in disease susceptibility. In this paper, we discuss the following six reasons why COPD develops in humans based on current evolutionary medical theories: (1) evolutionary constraints; (2) mismatch between environmental changes and evolution; (3) co-evolution with pathogenic microorganisms; (4) life history trade-off; (5) defenses and their costs, and (6) reproductive success at the expense of health. Our perspective pursues evolutionary answers to the fundamental question, 'Why are humans susceptible to this common disease, COPD, despite their long evolutionary history?' We believe that the perspectives offered by evolutionary medicine are essential for researchers to better understand the significance of their work.

COPD: balancing oxidants and antioxidants

Chronic obstructive pulmonary disease (COPD) is one of the most common chronic illnesses in the world. The disease encompasses emphysema, chronic bronchitis, and small airway obstruction and can be caused by environmental exposures, primarily cigarette smoking. Since only a small subset of smokers develop COPD, it is believed that host factors interact with the environment to increase the propensity to develop disease. The major pathogenic factors causing disease include infection and inflammation, protease and antiprotease imbalance, and oxidative stress overwhelming antioxidant defenses. In this review, we will discuss the major environmental and host sources for oxidative stress; discuss how oxidative stress regulates chronic bronchitis; review the latest information on genetic predisposition to COPD, specifically focusing on oxidant/antioxidant imbalance; and review future antioxidant therapeutic options for COPD. The complexity of COPD will necessitate a multi-target therapeutic approach. It is likely that antioxidant supplementation and dietary antioxidants will have a place in these future combination therapies.

Pulmonary oxidative stress, inflammation and cancer: respirable particulate matter, fibrous dusts and ozone as major causes of lung carcinogenesis through reactive oxygen species mechanisms

Reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress in the respiratory system increase the production of mediators of pulmonary inflammation and initiate or promote mechanisms of carcinogenesis. The lungs are exposed daily to oxidants generated either endogenously or exogenously (air pollutants, cigarette smoke, etc.). Cells in aerobic organisms are protected against oxidative damage by enzymatic and non-enzymatic antioxidant systems. Recent epidemiologic investigations have shown associations between increased incidence of respiratory diseases and lung cancer from exposure to low levels of various forms of respirable fibers and particulate matter (PM), at occupational or urban air polluting environments. Lung cancer increases substantially for tobacco smokers due to the synergistic effects in the generation of ROS, leading to oxidative stress and inflammation with high DNA damage potential. Physical and chemical characteristics of particles (size, transition metal content, speciation, stable free radicals, etc.) play an important role in oxidative stress. In turn, oxidative stress initiates the synthesis of mediators of pulmonary inflammation in lung epithelial cells and initiation of carcinogenic mechanisms. Inhalable quartz, metal powders, mineral asbestos fibers, ozone, soot from gasoline and diesel engines, tobacco smoke and PM from ambient air pollution (PM₁₀ and PM₂.₅) are involved in various oxidative stress mechanisms. Pulmonary cancer initiation and promotion has been linked to a series of biochemical pathways of oxidative stress, DNA oxidative damage, macrophage stimulation, telomere shortening, modulation of gene expression and activation of transcription factors with important role in carcinogenesis. In this review we are presenting the role of ROS and oxidative stress in the production of mediators of pulmonary inflammation and mechanisms of carcinogenesis.