A 7-month cigarette smoke inhalation study in C57BL/6 mice demonstrates reduced lung inflammation and emphysema following smoking cessation or aerosol exposure from a prototypic modified risk tobacco product

Effects of electronic cigarette E-liquid and device wattage on vascular function

Electronic cigarettes (e-cigs) are customizable tobacco products that allow users to select e-liquid composition, flavors, and (in some devices) adjust wattage or heat used to generate e-cig aerosol. This study compared vascular outcomes in a conducting vessel (thoracic aorta) and a resistance artery (middle cerebral artery, MCA) in C57Bl/6 mice exposed to e-cig aerosol generated from either pure vegetable glycerin (VG) or pure propylene glycol (PG) over 60-min (Study 1), and separately the effect of using 5- vs. 30-watt settings with an exposure of 100-min (Study 2). In Study 1, aortic endothelial-dependent-dilation (EDD) was only impaired with PG- exposure (p < 0.05) compared with air. In the MCA, EDD response was impaired by ∼50% in both VG and PG groups compared with air (p < 0.05). In Study 2, the aortic EDD responses were not different for either 5- or 30-watt exposed groups compared with air controls; however, in the MCA, both 5- and 30-watt groups were impaired by 32% and 55%, respectively, compared with air controls (p < 0.05). These pre-clinical data provide evidence that chronic exposure to aerosol produced by either VG or PG, and regardless of the wattage used, leads to vascular dysfunction at multiple levels within the arterial system. For all exposures, we observed greater impairment of arterial reactivity in a resistance artery (i.e. MCA) compared with the aorta. These data could suggest the smaller arteries may be more sensitive or first to be affected, or that different mechanism(s) for impairment may be involved depending on arterial hierarchy.

Long-term e-cigarette aerosol exposure causes pulmonary emphysema in adult female and male mice

This study aimed to evaluate long-term exposure to conventional cigarette smoke (CC) and electronic cigarette (EC) aerosol in adult male and female C57BL/6 mice. Forty-eight C57BL/6 mice were used, male (n = 24) and female (n = 24), both were divided into three groups: control, CC and EC. The CC and EC groups were exposed to cigarette smoke or electronic cigarette aerosol, respectively, 3 times a day for 60 consecutive days. Afterwards, they were maintained for 60 days without exposure to cigarettes or electronic cigarette aerosol. Both cigarettes promoted an influx of inflammatory cells to the lung in males and females. All animals exposed to CC and EC showed an increase in lipid peroxidation and protein oxidation. There was an increase of IL-6 in males and females exposed to EC. The IL-13 levels were higher in the females exposed to EC and CC. Both sexes exposed to EC and CC presented tissue damage characterized by septal destruction and increased alveolar spaces compared to control. Our results demonstrated that exposure to CC and EC induced pulmonary emphysema in both sexes, and females seem to be more susceptible to EC.

Assessment of inhalation toxicity of cigarette smoke and aerosols from flavor mixtures: 5-week study in A/J mice

Most flavors used in e-liquids are generally recognized as safe for oral consumption, but their potential effects when inhaled are not well characterized. In vivo inhalation studies of flavor ingredients in e-liquids are scarce. A structure-based grouping approach was used to select 38 flavor group representatives (FGR) on the basis of known and in silico-predicted toxicological data. These FGRs were combined to create prototype e-liquid formulations and tested against cigarette smoke (CS) in a 5-week inhalation study. Female A/J mice were whole-body exposed for 6 h/day, 5 days/week, for 5 weeks to air, mainstream CS, or aerosols from (1) test formulations containing propylene glycol (PG), vegetable glycerol (VG), nicotine (N; 2% w/w), and flavor (F) mixtures at low (4.6% w/w), medium (9.3% w/w), or high (18.6% w/w) concentration or (2) base formulation (PG/VG/N). Male A/J mice were exposed to air, PG/VG/N, or PG/VG/N/F-high under the same exposure regimen. There were no significant mortality or in-life clinical findings in the treatment groups, with only transient weight loss during the early exposure adaptation period. While exposure to flavor aerosols did not cause notable lung inflammation, it caused only minimal adaptive changes in the larynx and nasal epithelia. In contrast, exposure to CS resulted in lung inflammation and moderate-to-severe changes in the epithelia of the nose, larynx, and trachea. In summary, the study evaluates an approach for assessing the inhalation toxicity potential of flavor mixtures, thereby informing the selection of flavor exposure concentrations (up to 18.6%) for a future chronic inhalation study.

Smoking status impacts treatment efficacy in smoke-induced lung inflammation: A pre-clinical study

Rationale: Smoking status and smoking history remain poorly accounted for as variables that could affect the efficacy of new drugs being tested in chronic obstructive pulmonary disease (COPD) patients. As a proof of concept, we used a pre-clinical model of cigarette smoke (CS) exposure to compare the impact of treatment during active CS exposure or during the cessation period on the anti-inflammatory effects IL-1α signaling blockade.

Methods: Mice were exposed to CS for 2 weeks, followed by a 1-week cessation, then acutely re-exposed for 2 days. Mice were treated with an anti-IL-1α antibody either during CS exposure or during cessation and inflammatory outcomes were assessed.

Results: We found that mice re-exposed to CS displayed reduced neutrophil counts and cytokine levels in the bronchoalveolar lavage (BAL) compared to mice exposed only acutely. Moreover, we found that treatment with an anti-IL-1α antibody during the initial CS exposure delayed inflammatory processes and interfered with pulmonary adaptation, leading to rebound pulmonary neutrophilia, increased BAL cytokine secretion (CCL2) and upregulated Mmp12 expression. Conversely, administration of anti-IL-1α during cessation had the opposite effect, improving BAL neutrophilia, decreasing CCL2 levels and reducing Mmp12 expression.

Discussion: These results suggest that pulmonary adaptation to CS exposure dampens inflammation and blocking IL-1α signaling during CS exposure delays the inflammatory response. More importantly, the same treatment administered during cessation hastens the return to pulmonary inflammatory homeostasis, strongly suggesting that smoking status and treatment timing should be considered when testing new biologics in COPD.

Predicting the pulmonary effects of long-term e-cigarette use: are the clouds clearing?

Commercially available since 2007, e-cigarettes are a popular electronic delivery device of ever-growing complexity. Given their increasing use by ex-smokers, smokers and never-smokers, it is important to evaluate evidence of their potential pulmonary effects and predict effects of long-term use, since there has been insufficient time to study a chronic user cohort. It is crucial to evaluate indicators of harm seen in cigarette use, and those potentially unique to e-cigarette exposure. Evaluation must also account for the vast variation in e-cigarette devices (now including at least five generations of devices) and exposure methods used in vivo and in vitroThus far, short-term use cohort studies, combined with in vivo and in vitro models, have been used to probe for the effects of e-cigarette exposure. The effects and mechanisms identified, including dysregulated inflammation and decreased pathogen resistance, show concerning overlaps with the established effects of cigarette smoke exposure. Additionally, research has identified a signature of dysregulated lipid processing, which is unique to e-cigarette exposure.This review will evaluate the evidence of pulmonary effects of, and driving mechanisms behind, e-cigarette exposure, which have been highlighted in emerging literature, and highlight the gaps in current knowledge. Such a summary allows understanding of the ongoing debate into e-cigarette regulation, as well as prediction and potential mitigation of future problems surrounding e-cigarette use.

Maternal diabetes promotes offspring lung dysfunction and inflammation in a sex-dependent manner

Exposure to maternal diabetes is increasingly recognized as a risk factor for chronic respiratory disease in children. It is currently unclear, however, whether maternal diabetes affects the lung health of male and female offspring equally. This study characterizes the sex-specific impact of a murine model of diet-induced gestational diabetes (GDM) on offspring lung function and airway inflammation. Female adult mice are fed a high-fat (45% kcal) diet for 6-weeks prior to mating. Control offspring are from mothers fed a low fat (10% kcal) diet. Offspring were weaned and fed a chow diet until 10-weeks of age, at which point lung function was measured and lung lavage was collected. Male, but not female offspring exposed to GDM had increased lung compliance and reduced lung resistance at baseline. Female offspring exposed to GDM displayed increased methacholine reactivity and elevated levels of pro-inflammatory cytokines (e.g. interleukin (IL)-1β, IL-5, and CXCL1) in lung lavage. Female GDM offspring also displayed elevated abundance of matrix metalloproteinases (MMP) within their airways, namely MMP-3 and MMP-8. These results indicate disparate effects of maternal diabetes on lung health and airway inflammation of male and female offspring exposed to GDM. Female mice may be at greater risk of inflammatory lung conditions, such as asthma, while male offspring display changes that more closely align with models of chronic obstructive pulmonary disease. In conclusion, there are important sex-based differences in the impact of maternal diabetes on offspring lung health that could signal differences in future disease risk.

Epithelial Ablation of Miro1/Rhot1 GTPase Augments Lung Inflammation by Cigarette Smoke

Mitochondrial quality control is sustained by Miro1 (Rhot1), a calcium-binding membrane-anchored GTPase during mitophagy. The exact mechanism that operates the interaction of Miro1 with mitophagy machinery and their role in cigarette smoke (CS)-induced mitochondrial dysfunction that often results in lung inflammation is unclear. We hypothesized that Miro1 plays an important role in regulating mitophagy machinery and the resulting lung inflammation by CS exposure to mice. The lung epithelial Rhot1^fl/fl (WT) and Rhot1^CreCC10 mice were exposed to mainstream CS for 3 days (acute) and 4 months (chronic). Acute CS exposure showed a notable increase in the total inflammatory cells, macrophages, and neutrophils that are associated with inflammatory mediators. Chronic exposure showed increased infiltration of neutrophils versus air controls. The effects of acute and chronic CS exposure were augmented in the Rhot1^CreCC10 group, indicating that epithelial Miro1 ablation led to the augmentation of inflammatory cell infiltration with alteration in the inflammatory mediators. Thus, Rhot1/Miro1 plays an important role in regulating CS-induced lung inflammatory responses with implications in mitochondrial quality control.

Isoforskolin, an adenylyl cyclase activator, attenuates cigarette smoke-induced COPD in rats

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by limited airflow due to pulmonary and alveolar abnormalities from exposure to cigarette smoke (CS). Current therapeutic drugs are limited and the development of novel treatments to prevent disease progression is challenging. Isoforskolin (ISOF) from the plant Coleus forskohlii is an effective activator of adenylyl cyclase (AC) isoforms. Previously we found ISOF could attenuate acute lung injury in animal models, while the effect of ISOF on COPD has not been elucidated.

PURPOSE

In this study, we aimed to evaluate the efficacy of ISOF on COPD and reveal its potential mechanisms.

METHODS

A rat model of COPD was established by long-term exposure to CS, then the rats were orally administered with ISOF (0.5, 1 and 2 mg/kg). The pulmonary function, lung morphology, inflammatory cells and cytokines in serum or bronchoalveolar lavage fluid (BALF) were evaluated. Transcriptomics, proteomics and network pharmacology analysis were utilized to identify potential mechanisms of ISOF. Droplet digital PCR was used to detect the mRNA expression of AC1-10 in donor lung tissues. AC activation was determined in recombinant human embryonic kidney 293 (HEK293) cells stably expressing human AC isoforms. In addition, ISOF caused trachea relaxation ex vivo were assessed in isolated trachea rings from guinea pigs.

RESULTS

ISOF significantly ameliorated pathological damage of lung tissue and improved pulmonary function in COPD rats. ISOF treatment decreased the number of inflammatory cells in peripheral blood, and also the levels of pro-inflammatory cytokines in serum and BALF. Consistent with omics-based analyses, ISOF markedly downregulated the mTOR level in lung tissue. Flow cytometry analysis revealed that ISOF treatment reduced the ratio of Th17/Treg cells in peripheral blood. Furthermore, the expression levels of AC1 and AC2 are relatively higher than other AC isoforms in normal lung tissues, and ISOF could potently activate AC1 and AC2 in vitro and significantly relax isolated guinea pig trachea.

CONCLUSION

Collectively, our studies suggest that ISOF exerts its anti-COPD effect by improving lung function, anti-inflammation and trachea relaxation, which may be related to AC activation, mTOR signaling and Th17/Treg balance.

Reduced Chronic Toxicity and Carcinogenicity in A/J Mice in Response to Life-Time Exposure to Aerosol From a Heated Tobacco Product Compared With Cigarette Smoke

We conducted an inhalation study, in accordance with Organisation for Economic Co-operation and Development Test Guideline 453, exposing A/J mice to tobacco heating system (THS) 2.2 aerosol or 3R4F reference cigarette smoke (CS) for up to 18 months to evaluate chronic toxicity and carcinogenicity. All exposed mice showed lower thymus and spleen weight, blood lymphocyte counts, and serum lipid concentrations than sham mice, most likely because of stress and/or nicotine effects. Unlike THS 2.2 aerosol-exposed mice, CS-exposed mice showed increased heart weight, changes in red blood cell profiles and serum liver function parameters. Similarly, increased pulmonary inflammation, altered lung function, and emphysematous changes were observed only in CS-exposed mice. Histopathological changes in other respiratory tract organs were significantly lower in the THS 2.2 aerosol-exposed groups than in the CS-exposed group. Chronic exposure to THS 2.2 aerosol also did not increase the incidence or multiplicity of bronchioloalveolar adenomas or carcinomas relative to sham, whereas CS exposure did. Male THS 2.2 aerosol-exposed mice had a lower survival rate than sham mice, related to an increased incidence of urogenital issues that appears to be related to congenital factors rather than test item exposure. The lower impact of THS 2.2 aerosol exposure on tumor development and chronic toxicity is consistent with the significantly reduced levels of harmful and potentially harmful constituents in THS 2.2 aerosol relative to CS. The totality of the evidence from this study further supports the risk reduction potential of THS 2.2 for lung diseases in comparison with cigarettes.

Respiratory Effects of Exposure to Aerosol From the Candidate Modified-Risk Tobacco Product THS 2.2 in an 18-Month Systems Toxicology Study With A/J Mice

Smoking cessation is the most effective measure for reducing the risk of smoking-related diseases. However, switching to less harmful products (modified-risk tobacco products [MRTP]) can be an alternative to help reduce the risk for adult smokers who would otherwise continue to smoke. In an 18-month chronic carcinogenicity/toxicity study in A/J mice (OECD Test Guideline 453), we assessed the aerosol of Tobacco Heating System 2.2 (THS 2.2), a candidate MRTP based on the heat-not-burn principle, compared with 3R4F cigarette smoke (CS). To capture toxicity- and disease-relevant mechanisms, we complemented standard toxicology endpoints with in-depth systems toxicology analyses. In this part of our publication series, we report on integrative assessment of the apical and molecular exposure effects on the respiratory tract (nose, larynx, and lungs). Across the respiratory tract, we found changes in inflammatory response following 3R4F CS exposure (eg, antimicrobial peptide response in the nose), with both shared and distinct oxidative and xenobiotic responses. Compared with 3R4F CS, THS 2.2 aerosol exerted far fewer effects on respiratory tract histology, including adaptive tissue changes in nasal and laryngeal epithelium and inflammation and emphysematous changes in the lungs. Integrative analysis of molecular changes confirmed the substantially lower impact of THS 2.2 aerosol than 3R4F CS on toxicologically and disease-relevant molecular processes such as inflammation, oxidative stress responses, and xenobiotic metabolism. In summary, this work exemplifies how apical and molecular endpoints can be combined effectively for toxicology assessment and further supports findings on the reduced respiratory health risks of THS 2.2 aerosol.

Role of diabetes in lung injury from acute exposure to electronic cigarette, heated tobacco product, and combustible cigarette aerosols in an animal model

BACKGROUND

Patients with diabetes are more vulnerable to the detrimental respiratory effects of combustible cigarette smoke (CS) when compared to the general population. Electronic cigarettes (ECIG) and heated tobacco products (HTP) are marketed as less harmful alternatives to CS. In this study, we compared the effects of acute ECIG, HTP and CS exposure on the lungs of type II diabetes versus non-diabetic mice in an animal model.

METHODS

Type II Diabetic (Diab) and Non-Diabetic (Non-Diab) mice were divided into Control, ECIG, HTP and CS groups. Animals were exposed for 6 hrs./day to either air, ECIG, HTP or CS for seven days. Lung injury was determined by a) histopathology, b) wet to dry ratio, c) albumin concentration in bronchoalveolar lavage fluid, d) expression of TNF-α, IL-6, and IL-1 β, e) reactive oxygen species production (ROS), and f) assessment of cellular apoptosis.

RESULTS

Lung histology revealed increased edema and inflammatory cells in diabetic mice exposed to ECIG, HTP and CS. The expression of Inflammatory mediators was, in general, more significant in the Diabetic groups as well. TNF-α expression, for example, was upregulated in Diab + ECIG but not in Non-Diab + ECIG. ROS was significantly increased in Diab + CS, less in Non-Diab + CS and weakly noted in ECIG + Diab. Significant albumin leak was observed in Diab and Non-Diab HTP-exposed animals. CS exposure worsened lung injury in Diab when compared to Non-Diab mice.

CONCLUSION

Comorbid medical conditions like diabetes may amplify ill effects of CS, ECIG or HTP exposure.

Isoforskolin Alleviates AECOPD by Improving Pulmonary Function and Attenuating Inflammation Which Involves Downregulation of Th17/IL-17A and NF-κB/NLRP3

Chronic obstructive pulmonary disease (COPD), a major cause of morbidity and mortality worldwide, is widely considered to be related to cigarette smoke (CS), and viral infections trigger acute exacerbation of COPD (AECOPD). Isoforskolin (ISOF) is a bioactive component from the plant Coleus forskohlii, native to Yunnan in China. It has been demonstrated that ISOF has anti-inflammatory effect on acute lung injury animal models. In the present study, we investigated the efficacy and mechanism of ISOF for the prevention and treatment of AECOPD. Mice were exposed to CS for 18 weeks and then infected with influenza virus A/Puerto Rico/8/34 (H1N1). ISOF (0.5, 2 mg/kg) was intragastrically administered once a day after 8 weeks of exposure to cigarette smoke when the body weight and lung function of model mice declined significantly. The viral load, pulmonary function, lung morphology, Th17 cells, and inflammatory cytokines in lung tissues were evaluated. The expression of nuclear factor κB (NF-κB) and NOD-like receptor pyrin domain–containing protein 3 (NLRP3) inflammasome pathways were detected. The results showed that ISOF treatment reduced the viral load in the lung homogenate, decreased the lung index of model mice, and lung pathological injuries were alleviated. ISOF also improved the pulmonary function with increased FEV0.1/FVC and decreased Rn and Rrs. The levels of inflammatory mediators (TNF-α, IL-1β, IL-6, IL-17A, MCP-1, MIG, IP-10, and CRP) in the lung homogenate were reduced after ISOF treatment. ISOF decreased the proportion of Th17 cells in the lung tissues by the flow cytometry test, and the protein expression levels of RORγt and p-STAT3 were also decreased. Furthermore, ISOF significantly inhibited the activation of NF-κB signaling and NLRP3 inflammasome in the lung tissues of model mice. In conclusion, ISOF alleviates AECOPD by improving pulmonary function and attenuating inflammation via the downregulation of proinflammatory cytokines, Th17/IL-17 A, and NF-κB/NLRP3 pathways.

Correlation guided Network Integration (CoNI) reveals novel genes affecting hepatic metabolism

Objective

Technological advances have brought a steady increase in the availability of various types of omics data, from genomics to metabolomics. Integrating these multi-omics data is a chance and challenge for systems biology; yet, tools to fully tap their potential remain scarce.

Methods

We present here a fully unsupervised and versatile correlation-based method – termed Correlation guided Network Integration (CoNI) – to integrate multi-omics data into a hypergraph structure that allows for the identification of effective modulators of metabolism. Our approach yields single transcripts of potential relevance that map to specific, densely connected, metabolic subgraphs or pathways.

Results

By applying our method on transcriptomics and metabolomics data from murine livers under standard Chow or high-fat diet, we identified eleven genes with potential regulatory effects on hepatic metabolism. Five candidates, including the hepatokine INHBE, were validated in human liver biopsies to correlate with diabetes-related traits such as overweight, hepatic fat content, and insulin resistance (HOMA-IR).

Conclusion

Our method's successful application to an independent omics dataset confirmed that the novel CoNI framework is a transferable, entirely data-driven, flexible, and versatile tool for multiple omics data integration and interpretation.

Impact of 6-Month Exposure to Aerosols From Potential Modified Risk Tobacco Products Relative to Cigarette Smoke on the Rodent Gastrointestinal Tract

Cigarette smoking causes adverse health effects that might occur shortly after smoking initiation and lead to the development of inflammation and cardiorespiratory disease. Emerging studies have demonstrated the role of the intestinal microbiome in disease pathogenesis. The intestinal microbiome is susceptible to the influence of environmental factors such as smoking, and recent studies have indicated microbiome changes in smokers. Candidate modified risk tobacco products (CMRTP) are being developed to provide substitute products to lower smoking-related health risks in smokers who are unable or unwilling to quit. In this study, the ApoE^–/– mouse model was used to investigate the impact of cigarette smoke (CS) from the reference cigarette 3R4F and aerosols from two CMRTPs based on the heat-not-burn principle [carbon-heated tobacco product 1.2 (CHTP 1.2) and tobacco heating system 2.2 (THS 2.2)] on the intestinal microbiome over a 6-month period. The effect of cessation or switching to CHTP 1.2 after 3 months of CS exposure was also assessed. Next-generation sequencing was used to evaluate the impact of CMRTP aerosols in comparison to CS on microbiome composition and gene expression in the digestive tract of mice. Our analyses highlighted significant gene dysregulation in response to 3R4F exposure at 4 and 6 months. The findings showed an increase in the abundance of Akkermansiaceae upon CS exposure, which was reversed upon cessation. Cessation resulted in a significant decrease in Akkemansiaceae abundance, whereas switching to CHTP 1.2 resulted in an increase in Lactobacillaceae abundance. These microbial changes could be important for understanding the effect of CS on gut function and its relevance to disease pathogenesis via the microbiome.

Puff-resolved analysis and selected quantification of chemicals in the gas phase of E-Cigarettes, Heat-not-Burn devices and conventional cigarettes using single photon ionization time-of-flight mass spectrometry (SPI-TOFMS): A comparative study

INTRODUCTION

A wide array of alternative nicotine delivery devices (ANDD) has been developed and they are often described as less harmful than combustible cigarettes. This work compares the chemical emissions of three ANDD in comparison to cigarette smoke. All the tested ANDD are characterized by not involving combustion of tobacco.

METHOD

Single photon ionization time-of-flight mass spectrometry (SPI-TOFMS) is coupled to a linear smoking machine, which allows a comprehensive, online analysis of the gaseous phase of the ANDD aerosol and the conventional cigarette smoke (CC). The following devices were investigated in this study: a tobacco cigarette with a glowing piece of coal as a heating source, an electric device for heating tobacco and a first-generation electronic cigarette. Data obtained from a standard 2R4F research cigarette are taken as a reference.

RESULTS

The puff-by-puff profile of all products was recorded. The ANDD show a substantial reduction or complete absence of known harmful and potentially harmful substances compared to the CC. In addition, tar substances (i.e. semivolatile and low volatile aromatic and phenolic compounds) are formed to a much lower extent. Nicotine, however, is supplied in comparable amounts except for the investigated electronic cigarette.

CONCLUSIONS

The data shows that consumers switching from CC to ANDD are exposed to lower concentrations of harmful and potentially harmful substances. However, toxicological and epidemiological studies must deliver conclusive results if these reduced exposures are beneficial for users.

IMPLICATION

The comparison of puff-resolved profiles of emissions from different tobacco products, traditional and alternative, may help users switch to lower emission products. Puff-resolved comparison overcomes technical changes, use modes between products and may help in their regulation.

A 6-month inhalation toxicology study in Apoe-/- mice demonstrates substantially lower effects of e-vapor aerosol compared with cigarette smoke in the respiratory tract

Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Considerable attention has been paid to the reduced harm potential of nicotine-containing inhalable products such as electronic cigarettes (e-cigarettes). We investigated the effects of mainstream cigarette smoke (CS) and e-vapor aerosols (containing nicotine and flavor) generated by a capillary aerosol generator on emphysematous changes, lung function, and molecular alterations in the respiratory system of female Apoe-/- mice. Mice were exposed daily (3 h/day, 5 days/week) for 6 months to aerosols from three different e-vapor formulations-(1) carrier (propylene glycol and vegetable glycerol), (2) base (carrier and nicotine), or (3) test (base and flavor)-or to CS from 3R4F reference cigarettes. The CS and base/test aerosol concentrations were matched at 35 µg nicotine/L. CS exposure, but not e-vapor exposure, led to impairment of lung function (pressure-volume loop area, A and K parameters, quasi-static elastance and compliance) and caused marked lung inflammation and emphysematous changes, which were confirmed histopathologically and morphometrically. CS exposure caused lung transcriptome (activation of oxidative stress and inflammatory responses), lipidome, and proteome dysregulation and changes in DNA methylation; in contrast, these effects were substantially reduced in response to the e-vapor aerosol exposure. Compared with sham, aerosol exposure (carrier, base, and test) caused a slight impact on lung inflammation and epithelia irritation. Our results demonstrated that, in comparison with CS, e-vapor aerosols induced substantially lower biological and pathological changes in the respiratory tract associated with chronic inflammation and emphysema.

Impact of whole-body versus nose-only inhalation exposure systems on systemic, respiratory, and cardiovascular endpoints in a 2-month cigarette smoke exposure study in the ApoE-/- mouse model

Cigarette smoking is one major modifiable risk factor in the development and progression of chronic obstructive pulmonary disease and cardiovascular disease. To characterize and compare cigarette smoke (CS)-induced disease endpoints after exposure in either whole-body (WB) or nose-only (NO) exposure systems, we exposed apolipoprotein E-deficient mice to filtered air (Sham) or to the same total particulate matter (TPM) concentration of mainstream smoke from 3R4F reference cigarettes in NO or WB exposure chambers (EC) for 2 months. At matching TPM concentrations, we observed similar concentrations of carbon monoxide, acetaldehyde, and acrolein, but higher concentrations of nicotine and formaldehyde in NOEC than in WBEC. In both exposure systems, CS exposure led to the expected adaptive changes in nasal epithelia, altered lung function, lung inflammation, and pronounced changes in the nasal epithelial transcriptome and lung proteome. Exposure in the NOEC caused generally more severe histopathological changes in the nasal epithelia and a higher stress response as indicated by body weight decrease and lower blood lymphocyte counts compared with WB exposed mice. Erythropoiesis, and increases in total plasma triglyceride levels and atherosclerotic plaque area were observed only in CS-exposed mice in the WBEC group but not in the NOEC group. Although the composition of CS in the breathing zone is not completely comparable in the two exposure systems, the CS-induced respiratory disease endpoints were largely confirmed in both systems, with a higher magnitude of severity after NO exposure. CS-accelerated atherosclerosis and other pro-atherosclerotic factors were only significant in WBEC.

Two Weeks of Smoking Cessation Reverse Cigarette Smoke-Induced Skeletal Muscle Atrophy and Mitochondrial Dysfunction in Mice

INTRODUCTION

Apart from its adverse effects on the respiratory system, cigarette smoking also induces skeletal muscle atrophy and dysfunction. Whether short-term smoking cessation can restore muscle mass and function is unknown. We, therefore, studied the impact of 1- and 2-week smoking cessation on skeletal muscles in a mouse model.

METHODS

Male mice were divided into four groups: Air-exposed (14 weeks); cigarette smoke (CS)-exposed (14 weeks); CS-exposed (13 weeks) followed by 1-week cessation; CS-exposed (12 weeks) followed by 2 weeks cessation to examine exercise capacity, physical activity levels, body composition, muscle function, capillarization, mitochondrial function and protein expression in the soleus, plantaris, and diaphragm muscles.

RESULTS

CS-induced loss of body and muscle mass was significantly improved within 1 week of cessation due to increased lean and fat mass. Mitochondrial respiration and protein levels of the respiratory complexes in the soleus were lower in CS-exposed mice, but similar to control values after 2 weeks of cessation. Exposing isolated soleus muscles to CS extracts reduced mitochondrial respiration that was reversed after removing the extract. While physical activity was reduced in all groups, exercise capacity, limb muscle force, fatigue resistance, fiber size and capillarization, and diaphragm cytoplasmic HIF-1α were unaltered by CS-exposure. However, CS-induced diaphragm atrophy and increased capillary density were not seen after 2 weeks of smoking cessation.

CONCLUSION

In male mice, 2 weeks of smoking cessation reversed smoking-induced mitochondrial dysfunction, limb muscle mass loss, and diaphragm muscle atrophy, highlighting immediate benefits of cessation on skeletal muscles.

IMPLICATIONS

Our study demonstrates that CS-induced skeletal muscle mitochondrial dysfunction and atrophy are significantly improved by 2 weeks of cessation in male mice. We show for the first time that smoking cessation as short as 1 to 2 weeks is associated with immediate beneficial effects on skeletal muscle structure and function with the diaphragm being particularly sensitive to CS-exposure and cessation. This could help motivate smokers to quit smoking as early as possible. The knowledge that smoking cessation has potential positive extrapulmonary effects is particularly relevant for patients referred to rehabilitation programs and those admitted to hospitals suffering from acute or chronic muscle deterioration yet struggling with smoking cessation.

Effects of E-Cigarette Aerosols with Varying Levels of Nicotine on Biomarkers of Oxidative Stress and Inflammation in Mice

To provide insights into the cause of e-cigarette (e-cig) associated lung injury, we examined the effects of propylene glycol (PG) and glycerol (G), two common solvent carriers used to deliver nicotine/flavor, on markers of oxidative stress and inflammation in female B6C3F1 mice which had been used successfully in tobacco smoke (TS)-induced lung carcinogenesis. Mice exposed to air and TS were used as negative and positive controls, respectively. Using LC-MS/MS, we showed that PG/G alone, in the absence of nicotine, significantly increased the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG or its tautomer 8-oxodG), a biomarker of DNA oxidative damage, in lung and plasma of mice; moreover, addition of nicotine (12 and 24 mg/mL) in e-cig liquid appears to suppress the levels of 8-oxodG. Exposure to e-cig aerosols or TS induced nonsignificant increases of plasma C-reactive protein (CRP), a biomarker of inflammation; nonetheless, the levels of fibronectin (FN), a biomarker of tissue injury, were significantly increased by e-cig aerosols or TS. Although preliminary, our data showed that exposure to e-cig aerosols induced a higher score of lung injury than did control air or TS exposure. Our results indicate that the B6C3F1 mouse model may be suitable for an in-depth examination of the impact of e-cig on lung injury associated with oxidative stress and inflammation and this study adds to the growing evidence that the use of e-cig can lead to lung damage.

A 7-month inhalation toxicology study in C57BL/6 mice demonstrates reduced pulmonary inflammation and emphysematous changes following smoking cessation or switching to e-vapor products

Cigarette smoking causes serious diseases, including lung cancer, atherosclerotic coronary artery disease, peripheral vascular disease, chronic bronchitis, and emphysema. While cessation remains the most effective approach to minimize smoking-related disease, alternative non-combustible tobacco-derived nicotine-containing products may reduce disease risks among those unable or unwilling to quit. E-vapor aerosols typically contain significantly lower levels of smoke-related harmful and potentially harmful constituents; however, health risks of long-term inhalation exposures are unknown. We designed a 7-month inhalation study in C57BL/6 mice to evaluate long-term respiratory toxicity of e-vapor aerosols compared to cigarette smoke and to assess the impact of smoking cessation (Cessation group) or switching to an e-vapor product (Switching group) after 3 months of exposure to 3R4F cigarette smoke (CS). There were no significant changes in in-life observations (body weights, clinical signs) in e-vapor groups compared to the Sham Control. The 3R4F CS group showed reduced respiratory function during exposure and had lower body weight and showed transient signs of distress post-exposure. Following 7 months of exposure, e-vapor aerosols resulted in no or minimal increase in pulmonary inflammation, while exposure to 3R4F CS led to impairment of lung function and caused marked lung inflammation and emphysematous changes. Biological changes observed in the Switching group were similar to the Cessation group. 3R4F CS exposure dysregulated the lung and nasal tissue transcriptome, while these molecular effects were substantially lower in the e-vapor group. Results from this study demonstrate that in comparison with 3R4F CS, e-vapor aerosols induce substantially lower biological responses including pulmonary inflammation and emphysematous changes, and that complete switching from CS to e-vapor products significantly reduces biological changes associated with CS in C57BL/6 mice.

Ceramide ratios are affected by cigarette smoke but not heat-not-burn or e-vapor aerosols across four independent mouse studies

AIMS

Smoking is an important risk factor for the development of chronic obstructive pulmonary disease and cardiovascular diseases. This study aimed to further elucidate the role of ceramides, as a key lipid class dysregulated in disease states.

MAIN METHODS

In this article we developed and validated LC-MS/MS method for ceramides (Cer(d18:1/16:0), Cer(d18:1/18:0), Cer(d18:1/24:0) and Cer(d18:1/24:1(15Z)) for the absolute quantification. We deployed it together with proteomics and transcriptomic analysis to assess the effects of cigarette smoke (CS) from the reference cigarette as well as aerosols from heat-not-burn (HnB) tobacco and e-vapor products in apolipoprotein E-deficient (ApoE^-/-) mice over several time points.

KEY FINDINGS

In the lungs, CS exposure substantially elevated the ratios of Cer(d18:1/24:0) and Cer(d18:1/24:1) to Cer(d18:1/18:0) in two independent ApoE^-/- mouse inhalation studies. Data from previous studies, in both ApoE^-/- and wild-type mice, further confirmed the reproducibility of this finding. Elevation of these ceramide ratios was also observed in plasma/serum, the liver, and-for the Cer(d18:1/24:1(15Z)) to Cer(d18:1/18:0) ratio-the abdominal aorta. Also, the levels of acid ceramidase (Asah1) and glucocerebrosidase (Gba)-lysosomal enzymes involved in the hydrolysis of glucosylceramides-were consistently elevated in the lungs after CS exposure. In contrast, exposure to HnB tobacco product and e-vapor aerosols did not induce significant changes in the ceramide profiles or associated enzymes.

SIGNIFICANCE

Our work in mice contributes to the accumulating evidence on the importance of ceramide ratios as biologically relevant markers for respiratory disorders, adding to their already demonstrated role in cardiovascular disease risk assessment in humans.

Exposure to nicotine-free and flavor-free e-cigarette vapors modifies the pulmonary response to tobacco cigarette smoke in female mice

Most of electronic cigarette (e-cigarette) users are also smoking tobacco cigarettes. Because of the relative novelty of this habit, very little is known on the impact of vaping on pulmonary health, even less on the potential interactions of dual e-cigarette and tobacco cigarette use. Therefore, we used well-established mouse models to investigate the impact of dual exposure to e-cigarette vapors and tobacco cigarette smoke on lung homeostasis. Groups of female BALB/c mice were exposed to room air, tobacco smoke only, nicotine-free flavor-free e-cigarette vapors only or both tobacco smoke and e-cigarette vapors. Moreover, since tobacco smoke and electronic cigarette vapors both affect circadian processes in the lungs, groups of mice were euthanized at two different time points during the day. We found that dual-exposed mice had altered lung circadian gene expression compared with mice exposed to tobacco smoke alone. Dual-exposed mice also had different frequencies of dendritic cells, macrophages, and neutrophils in the lung tissue compared with mice exposed to tobacco smoke alone, an observation also valid for B-lymphocytes and CD4+ and CD8+ T lymphocytes. Exposure to e-cigarette vapors also impacted the levels of immunoglobulins in the bronchoalveolar lavage and serum. Finally, e-cigarette and dual exposures increased airway resistance compared with mice exposed to room air or tobacco smoke alone, respectively. Taken together, these data suggest that e-cigarette vapors, even without nicotine or flavors, could affect how the lungs react to tobacco cigarette smoke exposure in dual users, potentially altering the pathological course triggered by smoking.

Favorable Changes in Biomarkers of Potential Harm to Reduce the Adverse Health Effects of Smoking in Smokers Switching to the Menthol Tobacco Heating System 2.2 for 3 Months (Part 2)

INTRODUCTION

Tobacco Heating System (THS) 2.2, a candidate modified-risk tobacco product, aims at offering an alternative to cigarettes for smokers while substantially reducing the exposure to harmful and potentially harmful constituents found in cigarette smoke.

METHODS

One hundred and sixty healthy adult US smokers participated in this randomized, three-arm parallel group, controlled clinical study. Subjects were randomized in a 2:1:1 ratio to menthol Tobacco Heating System 2.2 (mTHS), menthol cigarette, or smoking abstinence for 5 days in confinement and 86 subsequent ambulatory days. Endpoints included biomarkers of exposure to harmful and potentially harmful constituents (reported in our co-publication, Part 1) and biomarkers of potential harm (BOPH).

RESULTS

Compliance (protocol and allocated product exposure) was 51% and 18% in the mTHS and smoking abstinence arms, respectively, on day 90. Nonetheless, favorable changes in BOPHs of lipid metabolism (total cholesterol and high- and low-density cholesterol), endothelial dysfunction (soluble intercellular adhesion molecule-1), oxidative stress (8-epi-prostaglandin F2α), and cardiovascular risk factors (eg, high-sensitivity C-reactive protein) were observed in the mTHS group. Favorable effects in other BOPHs, including ones related to platelet activation (11-dehydrothromboxane B2) and metabolic syndrome (glucose), were more pronounced in normal weight subjects.

CONCLUSIONS

The results suggest that the reduced exposure demonstrated when switching to mTHS is associated with overall improvements in BOPHs, which are indicative of pathomechanistic pathways underlying the development of smoking-related diseases, with some stronger effects in normal weight subjects.

IMPLICATIONS

Switching to mTHS was associated with favorable changes for some BOPHs indicative of biological pathway alterations (eg, oxidative stress and endothelial dysfunction). The results suggest that switching to mTHS has the potential to reduce the adverse health effects of smoking and ultimately the risk of smoking-related diseases. Switching to mTHS for 90 days led to reductions in a number of biomarkers of exposure in smokers, relative to those who continued smoking cigarettes, which were close to those observed when stopping smoking (reported in our co-publication, Part 1). Initial findings suggest reduced levels of 8-epi-prostaglandin F2α and intercellular adhesion molecule 1, when switching to mTHS for 90 days. These changes are comparable to what is observed upon smoking cessation. In normal weight subjects, additional favorable changes were seen in 11-dehydrothromboxane B2, fibrinogen, homocysteine, hs-CRP, percentage of predicted forced expiratory volume in 1 second, systolic blood pressure, diastolic blood pressure, glucose, high-density lipoprotein, apolipoprotein A1, and triglycerides.

TRIAL REGISTRATION

NCT01989156.

The impact of periodontitis in the course of chronic obstructive pulmonary disease: Pulmonary and systemic effects

AIMS

The aim of this study was to verify the impact of periodontitis in the course of chronic obstructive pulmonary disease (COPD) in C57Bl/6J mice.

MAIN METHODS

The animals were randomly divided into four groups (n = 8): Basal, Periodontitis (P), COPD and COPD+P. COPD was induced by orotracheal instillation of 30 μl of cigarette extract 3 times/week for 7 weeks. Periodontitis was induced by ligation technique for 22 days. Euthanasia was performed on 51st day. The analyzes were total/differential cells and cytokines recovered from bronchoalveolar lavage (BAL), total/differential blood cell count, platelets, total marrow cell count, airway collagen deposition, alveolar enlargement analyzed by mean linear intercept (Lm), mucus and bone crest reabsorption. One-way ANOVA followed by the Student-Newman-Keuls was used.

KEY FINDINGS

The association COPD+P decreased macrophages (p = 0,0351), TNF-α (p = 0,0071) and INF-γ (p = 0,0004) in BAL, when compared to the COPD group maintaining emphysema levels by alveolar enlargement (p < .05) reorganization of collagen fibers (p = .001) and also mean linear intercept (lm) (p = .001) and mucus (p = .0001). The periodontitis group caused TNF-α increase (p = 0, 0001) in BAL.

SIGNIFICANCE

Periodontitis, per se, does not alter any of the parameters analyzed, except for increased TNF-α in BAL. However, its association with COPD caused macrophages TNF-α and INF-γ alterations, when compared to the COPD group maintaining emphysema levels by alveolar enlargement and reorganization of collagen fibers. It seems that periodontitis is influencing the course of Th1 profile cell, and cytokines and pulmonary alterations. Further studies are needed to clarify the regulatory process underlying these two diseases.

Cigarette smoke exposure has region-specific effects on GDAP1 expression in mouse hippocampus

Early detection markers for substance use disorders are urgently needed. Recently, an association between the methylation of Ganglioside-induced differentiation-associated protein 1 (GDAP1) and alcohol addiction was found in a US and German population. In this study, we investigate whether GDAP1 expression might be affected by cigarette smoke as well and thus might be a marker of substance addiction in general. 11 adult female C57BL/6 J mice (6 wildtype and 5 lacking the NO-sensitive guanylyl cyclase1 (NO-GC1 KO)) were exposed to cigarette smoke over a period of 5 weeks, their brains immunohistochemically stained and compared to 11 non exposed mice (5 WT and 6 KO). The deletion of NO-GC1 results in a complete loss of synaptic plasticity, therefore, addiction-related alterations might become more obvious. Co-staining of anti-GDAP1 and DAPI revealed protein in the stratum granulare of the hippocampus. Three randomized frames for dentate gyrus (DG) and three for Cornu Ammonis region 1 (CA1) were used to count GDAP1. Cigarette smoke exposure significantly influenced GDAP1 expression depending on the hippocampal region but was not influenced by guanyl cyclase. In conclusion, cigarette smoke exposure alone had an effect on GDAP1 amount in both regions. Therewith, GDAP1might be a biomarker for substance addiction in general.

E-vapor aerosols do not compromise bone integrity relative to cigarette smoke after 6-month inhalation in an ApoE-/- mouse model

Cigarette smoke (CS) exposure is one of the leading risk factors for human health. Nicotine-containing inhalable products, such as e-cigarettes, can effectively support tobacco harm reduction approaches. However, there are limited comparative data on the effects of the aerosols generated from electronic vapor products (e-vapor) and CS on bone. Here, we report the effects of e-vapor aerosols and CS on bone morphology, structure, and strength in a 6-month inhalation study. Eight-week-old ApoE^-/- mice were exposed to aerosols from three different e-vapor formulations-CARRIER (propylene glycol and vegetable glycerol), BASE (CARRIER and nicotine), TEST (BASE and flavor)-to CS from 3R4F reference cigarettes at matched nicotine concentrations (35 µg/L) or to fresh air (Sham) (N = 10 per group). Tibiae were analyzed for bone morphology by µCT imaging, biomechanics by three-point bending, and by histological analysis. CS inhalation caused a significant decrease in cortical and total bone volume fraction and bone density relative to e-vapor aerosols. Additionally, CS exposure caused a decrease in ultimate load and stiffness. In contrast, bone structural and biomechanical parameters were not significantly affected by e-vapor aerosol or Sham exposure. At the dissection time point, there was no significant difference in body weight or tibia bone weight or length among the groups. Histological findings revealed microcracks in cortical bone areas among all exposed groups compared to Sham control. In conclusion, because of the bone-preserving effect of e-vapor aerosols relative to CS exposure, e-vapor products could potentially constitute less harmful alternatives to cigarettes in situations in which bone health is of importance.

Multi-omics systems toxicology study of mouse lung assessing the effects of aerosols from two heat-not-burn tobacco products and cigarette smoke

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Multi-omics systems toxicology study, comprising five omics data modalities.

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Multi-Omics Factor Analysis and multi-modality functional network interpretation.

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Cigarettes smoke (CS) induced complex immunoregulatory interactions across molecular layers.

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Aerosols from two heat-not-burn tobacco products had less impact on lungs than CS.

Cigarette smoke (CS) causes adverse health effects and, for smoker who do not quit, modified risk tobacco products (MRTPs) can be an alternative to reduce the risk of developing smoking-related diseases. Standard toxicological endpoints can lack sensitivity, with systems toxicology approaches yielding broader insights into toxicological mechanisms. In a 6-month systems toxicology study on ApoE^−/− mice, we conducted an integrative multi-omics analysis to assess the effects of aerosols from the Carbon Heated Tobacco Product (CHTP) 1.2 and Tobacco Heating System (THS) 2.2—a potential and a candidate MRTP based on the heat-not-burn (HnB) principle—compared with CS at matched nicotine concentrations. Molecular exposure effects in the lungs were measured by mRNA/microRNA transcriptomics, proteomics, metabolomics, and lipidomics. Integrative data analysis included Multi-Omics Factor Analysis and multi-modality functional network interpretation. Across all five data modalities, CS exposure was associated with an increased inflammatory and oxidative stress response, and lipid/surfactant alterations. Upon HnB aerosol exposure these effects were much more limited or absent, with reversal of CS-induced effects upon cessation and switching to CHTP 1.2. Functional network analysis revealed CS-induced complex immunoregulatory interactions across the investigated molecular layers (e.g., itaconate, quinolinate, and miR-146) and highlighted the engagement of the heme–Hmox–bilirubin oxidative stress axis by CS. This work exemplifies how multi-omics approaches can be leveraged within systems toxicology studies and the generated multi-omics data set can facilitate the development of analysis methods and can yield further insights into the effects of toxicological exposures on the lung of mice.

Lung transcriptomic clock predicts premature aging in cigarette smoke-exposed mice

BACKGROUND

Lung aging is characterized by a number of structural alterations including fibrosis, chronic inflammation and the alteration of inflammatory cell composition. Chronic exposure to cigarette smoke (CS) is known to induce similar alterations and may contribute to premature lung aging. Additionally, aging and CS exposure are associated with transcriptional alterations in the lung. The current work aims to explore the interaction between age- and CS- associated transcriptomic perturbations and develop a transcriptomic clock able to predict the biological age and the impact of external factors on lung aging.

RESULTS

Our investigations revealed a substantial overlap between transcriptomic response to CS exposure and age-related transcriptomic alterations in the murine lung. Of particular interest is the strong upregulation of immunoglobulin genes with increased age and in response to CS exposure, indicating an important implication of B-cells in lung inflammation associated with aging and smoking. Furthermore, we used a machine learning approach based on Lasso regression to build a transcriptomic age model that can accurately predict chronological age in untreated mice and the deviations associated with certain exposures. Interestingly, CS-exposed-mice were predicted to be prematurely aged in contrast to mice exposed to fresh air or to heated tobacco products (HTPs). The accelerated aging rate associated with CS was reversed upon smoking cessation or switching to HTPs. Additionally, our model was able to predict premature aging associated with thoracic irradiation from an independent public dataset.

CONCLUSIONS

Aging and CS exposure share common transcriptional alteration patterns in the murine lung. The massive upregulation of B-cell restricted genes during these processes shed light on the contribution of cell composition and particularly immune cells to the measured transcriptomic signal. Through machine learning approach, we show that gene expression changes can be used to accurately monitor the biological age and the modulations associated with certain exposures. Our findings also suggest that the premature lung aging is reversible upon the reduction of harmful exposures.

Pulmonary hypertension in chronic obstructive pulmonary disease

Even mild pulmonary hypertension (PH) is associated with increased mortality and morbidity in patients with chronic obstructive pulmonary disease (COPD). However, the underlying mechanisms remain elusive; therefore, specific and efficient treatment options are not available. Therapeutic approaches tested in the clinical setting, including long-term oxygen administration and systemic vasodilators, gave disappointing results and might be only beneficial for specific subgroups of patients. Preclinical studies identified several therapeutic approaches for the treatment of PH in COPD. Further research should provide deeper insight into the complex pathophysiological mechanisms driving vascular alterations in COPD, especially as such vascular (molecular) alterations have been previously suggested to affect COPD development. This review summarizes the current understanding of the pathophysiology of PH in COPD and gives an overview of the available treatment options and recent advances in preclinical studies. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

The reduction of DSS-induced colitis severity in mice exposed to cigarette smoke is linked to immune modulation and microbial shifts

Exposure to cigarette smoke (CS) causes detrimental health effects, increasing the risk of cardiovascular, pulmonary diseases and carcinogenesis in exposed individuals. The impact of CS on Inflammatory Bowel Disease (IBD) has been established by a number of epidemiological and clinical studies. In fact, CS is associated with a higher risk of developing Crohn’s disease (CD) while inversely correlates with the development, disease risks, and relapse rate of ulcerative colitis (UC). To investigate the effect of CS exposure on experimental colitis, we performed a comprehensive and integrated comparative analysis of colon transcriptome and microbiome in mice exposed to dextran sodium sulfate (DSS) and CS. Colon transcriptome analysis revealed that CS downregulated specific pathways in a concentration-dependent manner, affecting both the inflammatory state and composition of the gut microbiome. Metagenomics analysis demonstrated that CS can modulate DSS-induced dysbiosis of specific bacterial genera, contributing to resolve the inflammation or accelerate recovery. The risks of smoking far outweigh any possible benefit, thus smoking cessation must always be encouraged because of its significant health benefits. However, the inverse association between active smoking and the development of UC cannot be ignored and the present study lays the foundation for investigating potential molecular mechanisms responsible for the attenuation of colitis by certain compounds of tobacco when decoupled from combustion.

Lipid-Embedded Molecular Dynamics Simulation Model for Exploring the Reverse Prostaglandin D2 Agonism of CT-133 towards CRTH2 in the Treatment of Type-2 Inflammation Dependent Diseases

Chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) has been involved in several inflammation dependent diseases by mediating the chemotaxis of pro-inflammatory cells in response to allergy and other responses through PGD2 ligation. This CRTH2-PGD2 signaling pathway has become a target for treating allergic and type 2 inflammation dependent diseases, with many inhibitors developed to target the PGD2 binding pocket. One of such inhibitors is the ramatroban analog, CT-133, which exhibited therapeutic potency cigarette smoke-induced acute lung injury in patients. Nonetheless, the molecular mechanism and structural dynamics that accounts for its therapeutic prowess remain unclear. Employing computational tools, this study revealed that although the carboxylate moiety in CT-133 and the native agonist PGD2 aided in their stability within the CRTH2 binding pocket, the tetrahydrocarbazole group of CT-133 engaged in strong interactions with binding pocket residues which could have formed as the basis of the antagonistic advantage of CT-133. Tetrahydrocarbazole group interactions also enhanced the relative stability CT-133 within the binding pocket which consequently favored CT-133 binding affinity. CT-133 binding also induced an inactive or 'desensitized' state in the helix 8 of CRTH2 which could conversely favor the recruitment of arrestin. These revelations would aid in the speedy development of small molecule inhibitors of CRTH2 in the treatment of type 2 inflammation dependent diseases.

A 6-month systems toxicology inhalation study in ApoE-/- mice demonstrates reduced cardiovascular effects of E-vapor aerosols compared with cigarette smoke

Smoking cigarettes is harmful to the cardiovascular system. Considerable attention has been paid to the reduced harm potential of alternative nicotine-containing inhalable products such as e-cigarettes. We investigated the effects of E-vapor aerosols or cigarette smoke (CS) on atherosclerosis progression, cardiovascular function, and molecular changes in the heart and aorta of female apolipoprotein E-deficient (ApoE^-/-) mice. The mice were exposed to aerosols from three different E-vapor formulations: 1) carrier (propylene glycol and vegetable glycerol), 2) base (carrier and nicotine), or 3) test (base and flavor) or to CS from 3R4F reference cigarettes for up to 6 mo. Concentrations of CS and base or test aerosols were matched at 35 µg nicotine/L. Exposure to CS, compared with sham-exposed fresh air controls, accelerated atherosclerotic plaque formation, whereas no such effect was seen for any of the three E-vapor aerosols. Molecular changes indicated disease mechanisms related to oxidative stress and inflammation in general, plus changes in calcium regulation, and altered cytoskeletal organization and microtubule dynamics in the left ventricle. While ejection fraction, fractional shortening, cardiac output, and isovolumic contraction time remained unchanged following E-vapor aerosols exposure, the nicotine-containing base and test aerosols caused an increase in isovolumic relaxation time similar to CS. A nicotine-related increase in pulse wave velocity and arterial stiffness was also observed, but it was significantly lower for base and test aerosols than for CS. These results demonstrate that in comparison with CS, E-vapor aerosols induce substantially lower biological responses associated with smoking-related cardiovascular diseases.NEW & NOTEWORTHY Analysis of key urinary oxidative stress markers and proinflammatory cytokines showed an absence of oxidative stress and inflammation in the animals exposed to E-vapor aerosols. Conversely, animals exposed to conventional cigarette smoke had high urinary levels of these markers. When compared with conventional cigarette smoke, E-vapor aerosols induced smaller atherosclerotic plaque surface area and volume. Systolic and diastolic cardiac function, as well as endothelial function, were further significantly less affected by electronic cigarette aerosols than conventional cigarette smoke. Molecular analysis demonstrated that E-vapor aerosols induce significantly smaller transcriptomic dysregulation in the heart and aorta compared with conventional cigarette smoke.

Structural, functional, and molecular impact on the cardiovascular system in ApoE-/- mice exposed to aerosol from candidate modified risk tobacco products, Carbon Heated Tobacco Product 1.2 and Tobacco Heating System 2.2, compared with cigarette smoke

AIM

To investigate the molecular, structural, and functional impact of aerosols from candidate modified risk tobacco products (cMRTP), the Carbon Heated Tobacco Product (CHTP) 1.2 and Tobacco Heating System (THS) 2.2, compared with that of mainstream cigarette smoke (CS) on the cardiovascular system of ApoE-/- mice.

METHODS

Female ApoE-/- mice were exposed to aerosols from THS 2.2 and CHTP 1.2 or to CS from the 3R4F reference cigarette for up to 6 months at matching nicotine concentrations. A Cessation and a Switching group (3 months exposure to 3R4F CS followed by filtered air or CHTP 1.2 for 3 months) were included. Cardiovascular effects were investigated by echocardiographic, histopathological, immunohistochemical, and transcriptomics analyses.

RESULTS

Continuous exposure to cMRTP aerosols did not affect atherosclerosis progression, heart function, left ventricular (LV) structure, or the cardiovascular transcriptome. Exposure to 3R4F CS triggered atherosclerosis progression, reduced systolic ejection fraction and fractional shortening, caused heart LV hypertrophy, and initiated significant dysregulation in the transcriptomes of the heart ventricle and thoracic aorta. Importantly, the structural, functional, and molecular changes caused by 3R4F CS were improved in the smoking cessation and switching groups.

CONCLUSION

Exposure to cMRTP aerosols lacked most of the CS exposure-related functional, structural, and molecular effects. Smoking cessation or switching to CHTP 1.2 aerosol caused similar recovery from the 3R4F CS effects in the ApoE-/- model, with no further acceleration of plaque progression beyond the aging-related rate.

Heated Tobacco Products: A Review of Current Knowledge and Initial Assessments

The health risks of tobacco smoking have been documented in numerous studies and smoking rates have declined in developed countries over the last 50 years. Today, we know that cigarette smoking is the major cause of preventable deaths due to tobacco smoke induced diseases. As a consequence of an increased awareness of smoking-related health risks, heated tobacco products (HTPs) are marketed as reduced toxicant alternatives to conventional tobacco products. Manufacturers claim that levels of toxicants and hazardous compounds are significantly reduced, implying that inhalation of the modified aerosol is less harmful compared to conventional cigarettes. In this manuscript, previous assessments of HTPs are briefly summarized, including a short discussion on challenges with the adaption of standard analytical methods used for tobacco smoke. The reliability of analytical data is important for risk assessment approaches that are based on reduced toxicant exposure. In order to assess a putative reduction of health risks, an integrated study design is required that should include clinical studies and epidemiology data. One manufacturer applied for a classification as a Modified Risk Tobacco Product (MRTP) in the United States, based on extensive toxicological studies that have also been published. However, data are not yet sufficient for a reliable assessment or recognition of putatively reduced health risks. Challenges regarding a classification in Europe are also discussed briefly in this review.

NPA: an R package for computing network perturbation amplitudes using gene expression data and two-layer networks

Background

High-throughput gene expression technologies provide complex datasets reflecting mechanisms perturbed in an experiment, typically in a treatment versus control design. Analysis of these information-rich data can be guided based on a priori knowledge, such as networks of related proteins or genes. Assessing the response of a specific mechanism and investigating its biological basis is extremely important in systems toxicology; as compounds or treatment need to be assessed with respect to a predefined set of key mechanisms that could lead to toxicity. Two-layer networks are suitable for this task, and a robust computational methodology specifically addressing those needs was previously published.

The NPA package (https://github.com/philipmorrisintl/NPA) implements the algorithm, and a data package of eight two-layer networks representing key mechanisms, such as xenobiotic metabolism, apoptosis, or epithelial immune innate activation, is provided.

Results

Gene expression data from an animal study are analyzed using the package and its network models. The functionalities are implemented using R6 classes, making the use of the package seamless and intuitive. The various network responses are analyzed using the leading node analysis, and an overall perturbation, called the Biological Impact Factor, is computed.

Conclusions

The NPA package implements the published network perturbation amplitude methodology and provides a set of two-layer networks encoded in the Biological Expression Language.

A six-month systems toxicology inhalation/cessation study in ApoE-/- mice to investigate cardiovascular and respiratory exposure effects of modified risk tobacco products, CHTP 1.2 and THS 2.2, compared with conventional cigarettes

Smoking is one of the major modifiable risk factors in the development and progression of chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD). Modified-risk tobacco products (MRTP) are being developed to provide substitute products for smokers who are unable or unwilling to quit, to lessen the smoking-related health risks. In this study, the ApoE-/- mouse model was used to investigate the impact of cigarette smoke (CS) from the reference cigarette 3R4F, or aerosol from two potential MRTPs based on the heat-not-burn principle, carbon heated tobacco product 1.2 (CHTP1.2) and tobacco heating system 2.2 (THS 2.2), on the cardiorespiratory system over a 6-month period. In addition, cessation or switching to CHTP1.2 after 3 months of CS exposure was assessed. A systems toxicology approach combining physiology, histology and molecular measurements was used to evaluate the impact of MRTP aerosols in comparison to CS. CHTP1.2 and THS2.2 aerosols, compared with CS, demonstrated lower impact on the cardiorespiratory system, including low to absent lung inflammation and emphysematous changes, and reduced atherosclerotic plaque formation. Molecular analyses confirmed the lower engagement of pathological mechanisms by MRTP aerosols than CS. Both cessation and switching to CHTP1.2 reduced the observed CS effects to almost sham exposure levels.

Electronic cigarettes: a task force report from the European Respiratory Society

There is a marked increase in the development and use of electronic nicotine delivery systems or electronic cigarettes (ECIGs). This statement covers electronic cigarettes (ECIGs), defined as "electrical devices that generate an aerosol from a liquid" and thus excludes devices that contain tobacco. Database searches identified published articles that were used to summarise the current knowledge on the epidemiology of ECIG use; their ingredients and accompanied health effects; second-hand exposure; use of ECIGs for smoking cessation; behavioural aspects of ECIGs and social impact; in vitro and animal studies; and user perspectives.ECIG aerosol contains potentially toxic chemicals. As compared to conventional cigarettes, these are fewer and generally in lower concentrations. Second-hand exposures to ECIG chemicals may represent a potential risk, especially to vulnerable populations. There is not enough scientific evidence to support ECIGs as an aid to smoking cessation due to a lack of controlled trials, including those that compare ECIGs with licenced stop-smoking treatments. So far, there are conflicting data that use of ECIGs results in a renormalisation of smoking behaviour or for the gateway hypothesis. Experiments in cell cultures and animal studies show that ECIGs can have multiple negative effects. The long-term effects of ECIG use are unknown, and there is therefore no evidence that ECIGs are safer than tobacco in the long term. Based on current knowledge, negative health effects cannot be ruled out.

Lung Function Decline after 24 Weeks of Moxa Smoke Exposure in Rats

OBJECTIVE

Moxibustion is a complementary therapy that has been used for thousands of years. Burning moxa produces smoke and inhalable particulates. Recent research has indicated that smoke inhalation is associated with negative lung effects. This study aimed to evaluate the lung function of rats after moxa smoke exposure at different concentrations.

METHODS

Using a randomised block experiment design, 28 male Wistar rats were randomly divided into three moxa smoke groups (opacity) (n=7): low concentration (27.45 mg/m3), medium concentration (168.76 mg/m3), and high concentration (384.67 mg/m3) with a control group. Rats in the moxa smoke groups were exposed in an automatic dynamic exposure device separately with different concentrations for 20 min/d, 6d/week, for 24 weeks. Rats in the control group were exposed in the same space without moxa smoke. Lung function was evaluated by the AniRes 2005 animal pulmonary function analysing system. Statistical Product and Service Solutions 18.0 software was used for data analysis.

RESULTS

In the study, no deaths were found in any group. There was no difference of forced expiratory volume in one second/forced vital capacity percentage (FEV1/FVC%), inspiratory resistance (Ri), and expiratory resistance (Re) among each group after 24 weeks of moxa smoke exposure (P>0.05). Compared with the control group (0.33 ml/cmH20), dynamic compliance (Cdyn) was reduced in the medium (0.29 ml/cmH20) and high (0.25 ml/cmH20) concentration groups (P<0.05); however, Cdyn in the low concentration group (0.29 ml/cmH20) was not significantly affected.

CONCLUSION

Moxa smoke exposure at low concentrations did not affect the rat's lung function. Moxa smoke of medium and high concentrations destroyed the lung function represented by decreased Cdyn. However, moxa smoke of low concentrations (27.45 mg/m3) is much higher than the concentration in a regular moxibustion clinic (3.54 mg/m3). Moxa smoke at higher concentrations might destroy the lung function. The safety evaluation of moxa smoke requires further research.

CRTH2 antagonist, CT‑133, effectively alleviates cigarette smoke-induced acute lung injury

AIMS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), characterized by overwhelming lung inflammation, are associated with high mortality. Cigarette smoke (CS) is one of the major causes of ALI/ARDS. Since high expression of prostaglandin (PG) D2 has been observed in CS-induced lung injury. Currently, no effective pharmacological therapies are available to treat ALI, and supportive therapies remain the mainstay of treatment. Therefore, we investigated the protective effect of CT‑133, a newly discovered selective CRTH2 antagonist, on CS-induced ALI in vivo and in vitro.

MAIN METHODS

CT‑133 (10 and 30 mg/kg), dexamethasone (1 mg/kg) and normal saline were intratracheally administrated 1 hr prior to whole-body CS-exposure for seven consecutive days to study the key characteristics of ALI. Subsequently, CSE (4%)- and PGD2-stimulated RAW 264.7 macrophages were used to evaluate the protective effect of CT‑133.

KEY FINDINGS

CT‑133 remarkably attenuated infiltration of inflammatory cells, neutrophils, and macrophages in the BALF, albumin contents, expression of IL‑1β, IL‑6, TNF‑α and KC, lung myeloperoxidase (MPO) activity and lung histopathological alterations caused by CS exposure in mice. Moreover, CT‑133 not only reversed the uncontrolled secretion of IL‑1β, IL-6, TNF‑α and KC from CSE- and PGD2-stimulated RAW 264.7 macrophages but also augmented IL-10 production in both in vivo and in vitro studies. Additionally, CT‑133 alleviated in vitro neutrophil migration chemoattracted by PGD2.

SIGNIFICANCE

Our results provide the first evidence that targeting CRTH2 could be a new potential therapeutic option to treat CS-induced ALI.

[Systematic analysis of the scientific literature on heated tobacco]

INTRODUCTION

The tobacco industry (TI) reports that heated tobacco reduces risk of tobacco use and will replace cigarettes. An analysis of the scientific literature was conducted in order to enlighten professionals and decision-makers.

METHOD

After a Medline query in February 2018, a systematic analysis was conducted.

RESULTS

Of the 100 papers published in 2008-2018, 75 have authors affiliated or linked to TI. Emissions contain gases, droplets and solid particles, so are smokes. The main products are: THS2.2 (Iqos®) which heats mini-cigarettes at 340°C, the THP1.0 (Glo®) which heats at 240°C sticks delivering about half as much nicotine, Ploom® which uses reconstituted tobacco microcapsules heated at 180°C. Under the experimental conditions, there is a reduction of toxic emissions and biological effects, but the expected risk reduction is not demonstrated. Symptoms related to passive smoking are described. The 4 epidemiological articles report that heated tobacco is used in 10 to 45% of cases by non-smokers and demonstrate the effectiveness of TI promotion campaigns. Thus, the THS2.2 is more a gateway to smoking (20%) than an exit door (11%); moreover, it is not expected risk reduction among the 69% who are mixed users.

CONCLUSIONS

While reducing emissions is documented, reducing the risk to the smoker who switches to heated-tobacco remains to be demonstrated. On the other hand, the worsening of the global tobacco risk related to the promotion of the products by the TI is anticipated, justifying that the authorities take the appropriate measures to control the promotion of heated tobacco.

Heparin-binding EGF-like growth factor attenuates lung inflammation and injury in a murine model of pulmonary emphysema

Pulmonary inflammation and progressive lung destruction are the major causes of chronic obstructive pulmonary disease (COPD), resulting in emphysema and irreversible pulmonary dysfunction. Heparin-binding EGF-like growth factor (HB-EGF), is known to play a protective role in the process of various inflammatory diseases. However, its effect on COPD is poorly understood. This study was designed to determine the effect of HB-EGF on lung inflammation and injury in a murine model of pulmonary emphysema. HB-EGF promoted percent survival and body weight, attenuated lung injury, inflammatory cells, and cytokines infiltration, and prevented lung function decline. Additionally, treatment of rHB-EGF suppressed the nuclear translocation of nuclear factor κB (NF-κB)/p65, decreased TUNEL-positive cells and the expression of caspase 3, and increased the expression of PCNA, HB-EGF, and EGF receptor (EGFR). We conclude that HB-EGF attenuates lung inflammation and injury, probably through the activation of EGFR, followed by suppression of NF-ΚB signalling, promotion of cell proliferation, and inhibition of apoptosis.

In vitro systems toxicology-based assessment of the potential modified risk tobacco product CHTP 1.2 for vascular inflammation- and cytotoxicity-associated mechanisms promoting adhesion of monocytic cells to human coronary arterial endothelial cells

Cigarette smoking causes cardiovascular diseases. Heating tobacco instead of burning it reduces the amount of toxic compounds in the aerosol and may exert a reduced impact on health compared with cigarette smoke. Aqueous extract from the aerosol of a potential modified risk tobacco product, the Carbon Heated Tobacco Product (CHTP) 1.2, was compared in vitro with aqueous extract from the smoke of a 3R4F reference cigarette for its impact on the adhesion of monocytic cells to artery endothelial cells. Human coronary artery endothelial cells (HCAEC) were treated for 4 h with conditioned media from human monocytic Mono Mac 6 (MM6) cells exposed to CHTP1.2 or 3R4F extracts for 2 h or directly with those extracts freshly generated. In vitro monocyte-endothelial cell adhesion was measured concomitantly with inflammatory, oxidative stress, cytotoxicity, and death markers. Furthermore, transcriptomics analyses enabled to quantify the level of perturbation in HCAECs, and provide biological interpretation for the underlying molecular changes following exposure to 3R4F or CHTP1.2 extract. Our systems toxicology study demonstrated that approximately 10-15-fold higher concentrations of the CHTP 1.2 aerosol extract were needed to elicit similar effects as the 3R4F smoke extract on cardiovascular disease-relevant inflammation and cytotoxicity-related mechanisms and markers investigated in vitro.

A 90-day OECD TG 413 rat inhalation study with systems toxicology endpoints demonstrates reduced exposure effects of the aerosol from the carbon heated tobacco product version 1.2 (CHTP1.2) compared with cigarette smoke. I. Inhalation exposure, clinical pathology and histopathology

Within the framework of a systems toxicology approach, the inhalation toxicity of aerosol from a novel tobacco-heating potentially modified risk tobacco product (MRTP), the carbon-heated tobacco product (CHTP) 1.2, was characterized and compared with that of mainstream smoke (CS) from the 3R4F reference cigarette in a 90-day nose-only rat inhalation study in general accordance with OECD TG 413. CHTP1.2 is a heat-not-burn product using a carbon heat source to produce an aerosol that contains nicotine and tobacco flavor. At equal or twice the nicotine concentration in the test atmospheres, inhalation of CHTP1.2 aerosol led to a significantly lower exposure to harmful constituents and induced less respiratory tract irritation, systemic, and pathological effects compared with CS. Nasal epithelial changes were less pronounced in the CHTP1.2- than in the CS-exposed groups and reverted in the nicotine concentration-matched group after a recovery period. Lung inflammation was minimal in the CHTP1.2-treated groups compared with the moderate extent seen in the 3R4F groups. Many other toxicological endpoints evaluated did not show CHTP1.2 aerosol exposure-related effects, and no effects not seen for 3R4F were observed. These observations were consistent with findings from previous studies in which rats were exposed to MRTP aerosols containing similar nicotine concentrations.

Secondhand Smoke Induces Inflammation and Impairs Immunity to Respiratory Infections

Despite advocacy to reduce smoking-related diseases, >1 billion people worldwide continue to smoke. Smoking is immunosuppressive and an important etiological factor in the development of several human disorders including respiratory diseases like chronic obstructive pulmonary disease. However, there is a critical gap in the knowledge of the role of secondhand smoke (SHS) in inflammation and immunity. We therefore studied the influence of SHS on pulmonary inflammation and immune responses to respiratory infection by nontypeable Haemophilus influenzae (NTHI) recurrently found in chronic obstructive pulmonary disease patients. Chronic SHS-exposed mice were chronically infected with NTHI and pulmonary inflammation was evaluated by histology. Immune cell numbers and cytokines were measured by flow cytometry and ELISA, respectively. Chronic SHS exposure impaired NTHI P6 Ag-specific B and T cell responses following chronic NTHI infection as measured by ELISPOT assays, reduced the production of Abs in serum and bronchoalveolar lavage, and enhanced albumin leak into the bronchoalveolar lavage as determined by ELISA. Histopathological examination of lungs revealed lymphocytic accumulation surrounding airways and bronchovasculature following chronic SHS exposure and chronic infection. Chronic SHS exposure enhanced the levels of inflammatory cytokines IL-17A, IL-6, IL-1β, and TNF-α in the lungs, and impaired the generation of adaptive immunity following either chronic infection or P6 vaccination. Chronic SHS exposure diminished bacterial clearance from the lungs after acute NTHI challenge, whereas P6 vaccination improved clearance equivalent to the level seen in air-exposed, non-vaccinated mice. Our study provides unequivocal evidence that SHS exposure has long-term detrimental effects on the pulmonary inflammatory microenvironment and immunity to infection and vaccination.

A 90-day OECD TG 413 rat inhalation study with systems toxicology endpoints demonstrates reduced exposure effects of the aerosol from the carbon heated tobacco product version 1.2 (CHTP1.2) compared with cigarette smoke. II. Systems toxicology assessment

Modified risk tobacco products (MRTPs) have the potential to reduce smoking-related health risks. The Carbon Heated Tobacco Product 1.2 (CHTP1.2) is a potential MRTP that uses a pressed carbon heat source to generate an aerosol by heating tobacco. Here, we report the results from the systems toxicology arm of a 90-day rat inhalation study (OECD test guideline 413) to assess the effects of CHTP1.2 aerosol compared with cigarette smoke (CS). Transcriptomics, proteomics, and lipidomics analyses complemented the standard endpoints. In the respiratory nasal epithelium, CS induced an adaptive tissue and inflammatory response, which was much weaker after CHTP1.2 aerosol exposure, mostly limited to the highest CHTP1.2 concentration (at twice the 3R4F CS concentration: 50 vs. 23 μg nicotine/L), in female rats. In the lungs, the effects of CS exposure included inflammatory and cellular stress responses, which were absent or much lower after CHTP1.2 aerosol exposure. Outside of the respiratory tract, CS and CHTP1.2 aerosol induced effects that were previously associated with exposure to any nicotine-containing aerosol, e.g., lower lipid concentrations in serum. Overall, this systems toxicology analysis complements and confirms the results from classical toxicological endpoints and further suggests potentially reduced respiratory health risks of CHTP1.2.

Tandem mass tags labeled quantitative proteomics to study the effect of tobacco smoke exposure on the rat lung

BACKGROUND

The causal link between tobacco smoke exposure (TSE) and numerous severe respiratory system diseases (RSD), including chronic bronchitis, chronic obstructive pulmonary disease, and lung cancer, is well established. However, the pathogenesis of TSE-induced RSD remains incompletely understood. This research aims to detect the pathogenetic mechanisms and potential therapeutic targets of TSE-induced RSD.

METHODS

This study employed TSE model which rats were exposed to a concentration of 60% tobacco smoke in a toxicant exposure system for four weeks. Tandem mass tags (TMT) labeled quantitative proteomics combined with off-line high pH reversed-phase fractionation, and nano-liquid chromatography-mass spectrometry method (off-line high pH RPF-nano-LC-MS/MS) were adopted to detect differentially expressed proteins (DEPs) in the lung tissues of the TSE model rats and to compare them with those in control. The accuracy of the results was verified by western blot.

RESULTS

Compared with the control group, 33 proteins in the TSE model group's lung tissues showed significant differential expression. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that, several biological pathways, such as the steroid biosynthesis pathway, were involved and played significant roles in the pathogenesis of the experimental group's TSE.

CONCLUSIONS

These findings make a crucial contribution to the search for a comprehensive understanding of TSE-induced RSD's pathogenesis, and furthermore provide guidance for the diagnosis and treatment of TSE-induced RSD.

Effects of Switching to the Menthol Tobacco Heating System 2.2, Smoking Abstinence, or Continued Cigarette Smoking on Clinically Relevant Risk Markers: A Randomized, Controlled, Open-Label, Multicenter Study in Sequential Confinement and Ambulatory Settings (Part 2)

Introduction

Modified-risk tobacco products are expected to reduce exposure to harmful and potentially harmful constituents of cigarette smoke, and ultimately reduce the health burden of smoking-related diseases. Clinically relevant risk markers of smoking-related diseases inform about the risk profile of new tobacco products in the absence of in-market epidemiological data. The menthol Tobacco Heating System 2.2 (mTHS) is a modified-risk tobacco product in development as an alternative to cigarettes (conventional cigarettes [CCs]).

Methods

In this parallel-group study, Japanese adult smokers (23-65 years; ≥10 mCCs/day) were randomized to mTHS, menthol CCs (mCC), or smoking abstinence (SA) for 5 days in confinement and 85 days in ambulatory settings. Endpoints included biomarkers of exposure to harmful and potentially harmful constituents and clinically relevant risk markers of smoking-related diseases.

Results

One-hundred and sixty participants were randomized to the mTHS (n = 78), mCC (n = 42), and SA (n = 40) groups. Switching to the mTHS was associated with reductions in biomarkers of exposure compared with continuing mCCs. Reductions in 8-epi-prostaglandin F2α (biomarker of oxidative stress), 11-dehydro-thromboxane B2 (biomarker of platelet activation), soluble intracellular adhesion molecule-1 (biomarker of endothelial function), and an increase in high-density lipoprotein cholesterol (biomarker of lipid metabolism) and forced expiratory volume in 1 second (biomarker of lung function) occurred in the mTHS group compared with the mCC group. The changes in the mTHS group approached those in the SA group.

Conclusions

Switching from mCCs to mTHS was associated with improvements in clinically relevant risk markers linked to mechanistic pathways involved in smoking-related diseases.

Implications

In this three-way randomized study, switching from menthol cigarettes to mTHS for 5 days in confinement and 85 days in ambulatory settings was associated with reductions in biomarkers of exposure to cigarette smoke, and changes were observed in clinically relevant biomarkers of oxidative stress (8-epi-prostaglandin F2α), platelet activity (11-dehydro-thromboxane B2), endothelial function (soluble intracellular adhesion molecule-1), lipid metabolism (high-density lipoprotein cholesterol) and lung function (forced expiratory volume in 1 second), similar to the SA group. The results suggest that switching to the mTHS has the potential to reduce the adverse health effects of conventional cigarettes.

Exploring the microbiome in health and disease

The analysis of human microbiome is an exciting and rapidly expanding field of research. In the past decade, the biological relevance of the microbiome for human health has become evident. Microbiome comprises a complex collection of microorganisms, with their genes and metabolites, colonizing different body niches. It is now well known that the microbiome interacts with its host, assisting in the bioconversion of nutrients and detoxification, supporting immunity, protecting against pathogenic microbes, and maintaining health. Remarkable new findings showed that our microbiome not only primarily affects the health and function of the gastrointestinal tract but also has a strong influence on general body health through its close interaction with the nervous system and the lung. Therefore, a perfect and sensitive balanced interaction of microbes with the host is required for a healthy body. In fact, growing evidence suggests that the dynamics and function of the indigenous microbiota can be influenced by many factors, including genetics, diet, age, and toxicological agents like cigarette smoke, environmental contaminants, and drugs. The disruption of this balance, that is called dysbiosis, is associated with a plethora of diseases, including metabolic diseases, inflammatory bowel disease, chronic obstructive pulmonary disease, periodontitis, skin diseases, and neurological disorders. The importance of the host microbiome for the human health has also led to the emergence of novel therapeutic approaches focused on the intentional manipulation of the microbiota, either by restoring missing functions or eliminating harmful roles. In the present review, we outline recent studies devoted to elucidate not only the role of microbiome in health conditions and the possible link with various types of diseases but also the influence of various toxicological factors on the microbial composition and function.

The administration of surfactant decreased oxidative stress in lungs of mice exposed to cigarette smoke

The alveolar surfactant, which composition consists of a unique and complex mixture of lipids and proteins, has immunomodulatory action. This study aimed to evaluate the effects of exogenous surfactant on pulmonary inflammatory response in mice exposed to cigarette smoke (CS). Twenty-four mice C57BL/6 were divided into four groups: control group exposed to ambient air (CG); surfactant treated group (SG); CS exposed group (CSG) and CS exposed group treated with surfactant (CSSG). For five days, CSG and CSSG were exposed to 12 commercial cigarettes/day and SG and CSSG received the surfactant by intranasal instillation. At the end of the experiment, the animals were euthanatized for the collection of bronchoalveolar lavage fluid (BALF) and lungs. The total number of leukocytes in BALF increased in CSG compared to CG, however, there was a decrease in CSSG compared to CSG. There was an increase in lipid peroxidation in SG and CSG compared to CG while there was a decrease in CSSG compared to CSG. Regarding the antioxidant enzymes, the catalase (CAT) activity increased in all groups compared to CG and the superoxide dismutase (SOD) activity decreased in CSG compared to the CG and SG. There was an increase in TNF in SG, CSG and CSSG compared to CG. There was an increase in IL-17 in CSSG compared to CG. There was an increase in CCL5 in SG and CSSG compared to CG. Therefore, our results demonstrated that the administration of exogenous surfactant was able to decrease the oxidative processes in the lungs of mice induced by short-term exposure to CS.