Cigarette smoke alters inflammatory genes and the extracellular matrix - investigations on viable sections of peripheral human lungs

Airway Spatial Transcriptomics in Smoking

Background

Cigarette smoking has a significant impact on global health. Although cessation has positive health benefits, some molecular changes to intercellular communications may persist in the lung. In this study we created a framework to generate hypotheses by predicting altered cell-cell communication in smoker lungs using single-cell and spatial transcriptomic data.

Methods

We integrated publicly available lung single-cell transcriptomic data with spatial transcriptomic data from never-smoker and current-smoker lung tissue samples to create spatial transcriptomic data at virtual single-cell resolution by mapping individual cells from our lung scRNA-seq atlas to spots in the spatial transcriptomic data. Cell-cell communications altered in smoking were identified using the virtual single-cell transcriptomic data.

Results

We identified pathways altered in the three current-smoker samples compared with the three never-smoker samples, including the up-regulated collagen pathway. We observed increased collagen pathway activity involving the ligands COL1A1 and COL1A2 in adventitial fibroblasts and decreased activity involving COL1A2 and COL6A3 in pericytes and myofibroblasts, respectively. We also identified other pathways with structural (e.g. Fibronectin-1), immune-related (e.g. MHC-II), growth factor (e.g. Pleiotrophin) and immunophilin (e.g. Cyclophilin A) roles.

Conclusions

In this study we inferred spatially proximal cell-cell communication between interacting cell types from spatial transcriptomics at virtual single-cell resolution to identify lung intercellular signaling altered in smoking. Our findings further implicate several pathways previously identified, and provide additional molecular context to inform future functional experiments and therapeutic avenues to mitigate pathogenic effects of smoking.

Medwakh smoking induces alterations in salivary proteins and cytokine expression: a clinical exploratory proteomics investigation

BACKGROUND

Medwakh smoking has radically expanded among youth in the Middle East and around the world. The rising popularity of medwakh/dokha usage is linked to the onset of several chronic illnesses including cardiovascular diseases and cancers. Medwakh smoking is reported to increase the risk of inflammation in the lower respiratory tract owing to oxidative burden. To date, there are no reported studies investigating the impact of medwakh smoking on salivary protein profile. The current study aims to elucidate alterations in the salivary proteome profile of medwakh smokers.

METHODS

Saliva samples collected from 33 medwakh smokers and 30 non-smokers were subjected to proteomic analysis using UHPLC-ESI-QTOF-MS. Saliva samples were further subjected to validatory experiments involving analysis of inflammatory cytokine profile using LEGENDplex™ Human Essential Immune Response Panel.

RESULTS

Statistical analysis revealed alterations in the abundance of 74 key proteins including immune mediators and inflammatory markers in medwakh smokers (Accession: PXD045901). Proteins involved in building oxidative stress, alterations in cell anchorage, and cell metabolic processes were enhanced in medwakh smokers. Salivary immune response evaluation further validated the proteome findings, revealing significantly higher levels of IL-1β, IL-12p70, IL-23, IFN-γ (Th1 cytokines), IL-6 (Th2 cytokine), and MCP-1 (chemokine) in medwakh smokers. In addition, a substantial increase in abundance of involucrin suggesting a plausible stratified squamous cell differentiation and increased cell lysis in the oral cavity of medwakh smokers akin to chronic obstructive pulmonary diseases (COPD). The protein-metabolite joint pathway analysis further showed significantly enriched differentially expressed proteins and metabolites of glycolysis/gluconeogenesis, pentose phosphate, fructose and mannose, nicotinate and nicotinamide, and glutathione metabolism pathways among medwakh smokers.

CONCLUSIONS

The findings of the study provide valuable insights on potential perturbations in various key immune molecules, cytokines, and signaling pathways among medwakh smokers. Medwakh smokers displayed elevated inflammation, increased oxidative stress and defective antioxidant responses, dysregulated energy metabolism, and alterations in proteins related to cell adhesion, migration, differentiation, and proliferation. The findings of study underscore the urgent need for comprehensive public health interventions among youth by raising awareness, implementing effective smoking cessation programs, and promoting healthy lifestyle to safeguard the well-being of individuals and communities worldwide.

Therapeutic effects of melatonin on the lungs of rats exposed to passive smoking

BACKGROUND

Passive smoke has a significant impact on lung function and constitutes a critical public health issue, as smoking generates free radicals that damage the lungs and other tissues. Currently, limited research exists on whether the antioxidant melatonin can mitigate lung damage caused by smoking. This study aims to investigate the mechanisms through which melatonin alleviates acute lung disease induced by passive smoking.

METHODS

Rats were divided into five groups (n = 6): a control group and three groups exposed to low, medium, and high concentrations of smoke, and a melatonin treatment group.

RESULTS

Data indicated that in the high concentration passive smoking group, the alveolar structure of the lung tissue was destroyed, and the total antioxidant capacity in lung tissue diminished as the concentration of smoke increased. The expressions of TNF-α, IL-6, and IL-1β exhibited similar results. The anti-apoptotic factors Bcl-2 and Bcl-xL mRNA level significantly decreased in the high concentration smoking group, while no significant changes were observed in the medium and low concentration groups. Conversely, the high concentration passive smoking increased the pro-apoptotic factors Bax and Caspase-3 mRNA levels. Additionally, endogenous melatonin levels in lung tissue gradually decreased following exposure to smoke, whereas the exogenous melatonin alleviated the changes in inflammatory factors and apoptosis-related factors in lung tissue. Furthermore, at high smoking concentrations, the mRNA levels of lung cancer-related genes vascular endothelial growth factor (VEGF), cytochromeP450 1A1 (CYP1A1), and cytochrome P450 1B1 (CYP1B1) were significantly increased, while exogenous melatonin reduced the expression of these genes in lung tissue.

CONCLUSIONS

These findings suggest that melatonin can diminish lung tissue damage, apoptosis, and inflammatory responses induced by passive smoking, as well as decrease the expression of lung cancer-related genes. Further experimental investigations involving exogenous melatonin treatments will be needed.

Precision Cut Lung Slices: Emerging Tools for Preclinical and Translational Lung Research. An Official American Thoracic Society Workshop Report

The urgent need for effective treatments for acute and chronic lung diseases underscores the significance of developing innovative preclinical human research tools. The 2023 ATS Workshop on Precision Cut Lung Slices (PCLS) brought together 35 experts to discuss and address the role of human tissue-derived PCLS as a unique tool for target and drug discovery and validation in pulmonary medicine. With increasing interest and usage, along with advancements in methods and technology, there is a growing need for consensus on PCLS methodology and readouts. The current document recommends standard reporting criteria and emphasizes the requirement for careful collection and integration of clinical metadata. We further discuss current clinically relevant readouts that can be applied to PCLS and highlight recent developments and future steps for implementing novel technologies for PCLS modeling and analysis. The collection and correlation of clinical metadata and multiomic analysis will further advent the integration of this preclinical platform into patient endotyping and the development of tailored therapies for lung disease patients.

Association between α-klotho levels and adults with COPD in the United States

Purpose

Chronic obstructive pulmonary disease (COPD) is accompanied by increased inflammation, persistent lung function decline, and extensive lung injury. Klotho, a well-known antiaging protein, has anti-inflammatory and antioxidative effects. However, the effects of klotho on COPD have yet to be thoroughly elucidated. This study examined the association among COPD adults and their α-klotho level.

Patients and methods

Data were collected from the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES). A total of 676 participants were analyzed and divided into COPD (n = 403) and non-COPD (n = 273) groups. The two groups were compared with respect to clinical characteristics. Logistic regression analysis and a generalized additive model were used to estimate the association between COPD incidence and serum α-klotho concentration. All COPD participants were stratified according to the levels of α-klotho (Q1: <687 pg./mL; Q2: 687-900 pg./mL; Q3: ≥900 pg./mL), and clinical characteristics were compared.

Results

Non-COPD individuals had higher α-klotho levels than did COPD individuals (863.09 ± 267.13 vs. 817.51 ± 302.20, p < 0.05). Logistic regression analysis revealed that the Q2 and Q3 layers had a lower risk of COPD than did the Q1 layer, with odds ratios (ORs) of 0.73 (0.50, 0.99) for Q2 and 0.58 (0.41, 0.86) for Q3 (p < 0.001). The generalized additive model showed that the risk of COPD gradually decreased with increasing α-klotho concentration when the α-klotho concentration < 1,500 pg./mL, while the risk of COPD increased as the α-klotho concentration increased to ≥1,500 pg./mL. Compared with individuals in the Q2 or Q3 groups, individuals with COPD in the Q1 group were more likely to be current smokers, have lower levels of erythrocytes, and have higher levels of creatinine and leukocytes.

Conclusion

Increased α-klotho levels were negatively correlated with the risk of COPD in participants over 40 years old with α-klotho <1,500 pg./mL. When α-klotho was ≥1,500 pg./mL, the risk of COPD increased as α-klotho levels increased. Pulmonary ventilation function and the number of hemocytes differed among COPD patients with different levels of α-klotho.

Precision cut lung slices: an integrated ex vivo model for studying lung physiology, pharmacology, disease pathogenesis and drug discovery

Precision Cut Lung Slices (PCLS) have emerged as a sophisticated and physiologically relevant ex vivo model for studying the intricacies of lung diseases, including fibrosis, injury, repair, and host defense mechanisms. This innovative methodology presents a unique opportunity to bridge the gap between traditional in vitro cell cultures and in vivo animal models, offering researchers a more accurate representation of the intricate microenvironment of the lung. PCLS require the precise sectioning of lung tissue to maintain its structural and functional integrity. These thin slices serve as invaluable tools for various research endeavors, particularly in the realm of airway diseases. By providing a controlled microenvironment, precision-cut lung slices empower researchers to dissect and comprehend the multifaceted interactions and responses within lung tissue, thereby advancing our understanding of pulmonary pathophysiology.

The activation of the AIM2 inflammasome after cigarette smoke exposure leads to an immunosuppressive lung microenvironment

Cigarette smoke is widely known as contributing to chronic inflammation underlying several airway diseases, such as chronic obstructive pulmonary disease (COPD) and lung cancer. In our previous studies we found that the lung of both COPD and cancer patients were characterized by the presence and activation of the AIM2 inflammasome. Here, we wanted to investigate the upstream step during the establishment of chronic lung inflammation after cigarette smoke exposure. We took advantage of a mouse model of smoking exposure and public scRNAseq data. We found that AIM2 mRNA was expressed in both alveolar type II, B cells, T regulatory (Treg) and macrophages detected in the lung of non-smokers (n = 4) and smokers (n = 3). The activation of AIM2 in smoking mice by using PolydA:dT did not alter cigarette-smoke-induced alveoli enlargement and mucus production, rather it induced higher recruitment of immunosuppressive cells, such as non-active dendritic cells (DCs), Arginase I+ macrophages, myeloid-derived suppressor cells (MDSC) and Tregs. In addition, the inflammatory environment after AIM2 activation in smoking mice was characterized by higher levels of IL-1α, IL-1β, IL-33, TNFα, LDH, IL-10 and TGFβ. This scenario was not altered after the pharmacological inhibition of both caspase-1 and STING pathway. In conclusion, these data suggest that chronic inflammation after cigarette smoke exposure is associated with AIM2 activation, which could lead towards cigarette smoke-associated lung diseases.

Genetic association between smoking and DLCO in idiopathic pulmonary fibrosis patients

BACKGROUND

Observational studies have shown that smoking is related to the diffusing capacity of the lungs for carbon monoxide (DLCO) in individuals with idiopathic pulmonary fibrosis (IPF). Nevertheless, further investigation is needed to determine the causal effect between these two variables. Therefore, we conducted a study to investigate the causal relationship between smoking and DLCO in IPF patients using two-sample Mendelian randomization (MR) analysis.

METHODS

Large-scale genome-wide association study (GWAS) datasets from individuals of European descent were analysed. These datasets included published lifetime smoking index (LSI) data for 462,690 participants and DLCO data for 975 IPF patients. The inverse-variance weighting (IVW) method was the main method used in our analysis. Sensitivity analyses were performed by MR‒Egger regression, Cochran's Q test, the leave-one-out test and the MR-PRESSO global test.

RESULTS

A genetically predicted increase in LSI was associated with a decrease in DLCO in IPF patients [ORIVW = 0.54; 95% CI 0.32-0.93; P = 0.02].

CONCLUSIONS

Our study suggested that smoking is associated with a decrease in DLCO. Patients diagnosed with IPF should adopt an active and healthy lifestyle, especially by quitting smoking, which may be effective at slowing the progression of IPF.

Assessing the Efficacy of Fenugreek Saponin Nanoparticles in Attenuating Nicotine-Induced Hepatotoxicity in Male Rats

During smoking, nicotine, the most bountiful compound in cigarettes, is absorbed into the body by the lungs and quickly metabolized in the liver, causing three major adverse impacts such as toxic, neoplastic, and immunomodulatory effects. Saponins extracted from several plants are reported to exhibit various biological actions, such as anticancer effects. So, the potential protective effect of fenugreek saponin and nanofenugreek saponin against toxicity induced by nicotine in male rats was investigated in this study. Animals were exposed to nicotine (1.5 mg/kg/day) and/or treated with fenugreek saponin (25, 50, and 100 mg/kg/day) and nanofenugreek saponin (20, 40, and 80 mg/kg/day). Comet assays, histopathological examination, and analyses for the expression levels of glutamate aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) genes in liver tissues as well as the activity of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were conducted. The results revealed that nicotine treatment induced a significant increase in DNA damage, decrease in the expression levels of (GLAST) and (GLT-1) genes, and increase in histopathological alterations in liver tissues. Moreover, nicotine treatment induced a significant reduction in the activity of antioxidant enzymes GPx and GST. On the other hand, administration of fenugreek saponin or nanofenugreek saponin with nicotine significantly decreased the DNA damage, increased the expression levels of (GLAST) and (GLT-1) genes, and decreased histopathological alterations in liver tissues. Additionally, a significant increase in the activities of GPx and GST was observed. The results suggested that DNA damage and histological injuries induced by nicotine were decreased by the administration of fenugreek saponin or nanofenugreek saponin; thus, fenugreek saponin and nanofenugreek saponin can be used as ameliorative agents against nicotine toxicity.

The COPD GWAS gene ADGRG6 instructs function and injury response in human iPSC-derived type II alveolar epithelial cells

Emphysema and chronic obstructive pulmonary disease (COPD) most commonly result from the effects of environmental exposures in genetically susceptible individuals. Genome-wide association studies have implicated ADGRG6 in COPD and reduced lung function, and a limited number of studies have examined the role of ADGRG6 in cells representative of the airway. However, the ADGRG6 locus is also associated with DLCO/VA, an indicator of gas exchange efficiency and alveolar function. Here, we sought to evaluate the mechanistic contributions of ADGRG6 to homeostatic function and disease in type 2 alveolar epithelial cells. We applied an inducible CRISPR interference (CRISPRi) human induced pluripotent stem cell (iPSC) platform to explore ADGRG6 function in iPSC-derived AT2s (iAT2s). We demonstrate that ADGRG6 exerts pleiotropic effects on iAT2s including regulation of focal adhesions, cytoskeleton, tight junctions, and proliferation. Moreover, we find that ADGRG6 knockdown in cigarette smoke-exposed iAT2s alters cellular responses to injury, downregulating apical complexes in favor of proliferation. Our work functionally characterizes the COPD GWAS gene ADGRG6 in human alveolar epithelium.

Menthol flavoring in e-cigarette condensate causes pulmonary dysfunction and cytotoxicity in precision cut lung slices

E-cigarette consumption is under scrutiny by regulatory authorities due to concerns about product toxicity, lack of manufacturing standards, and increasing reports of e-cigarette- or vaping-associated acute lung injury. In vitro studies have demonstrated cytotoxicity, mitochondrial dysfunction, and oxidative stress induced by unflavored e-cigarette aerosols and flavoring additives. However, e-cigarette effects on the complex lung parenchyma remain unclear. Herein, the impact of e-cigarette condensates with or without menthol flavoring on functional, structural, and cellular responses was investigated using mouse precision cut lung slices (PCLS). PCLS were exposed to e-cigarette condensates prepared from aerosolized vehicle, nicotine, nicotine + menthol, and menthol e-fluids at doses from 50 to 500 mM. Doses were normalized to the glycerin content of vehicle. Video-microscopy of PCLS revealed impaired contractile responsiveness of airways to methacholine and dampened ciliary beating following exposure to menthol-containing condensates at concentrations greater than 300 mM. Following 500 mM menthol-containing condensate exposure, epithelial exfoliation in intrabronchial airways was identified in histological sections of PCLS. Measurement of lactate dehydrogenase release, mitochondrial water-soluble-tetrazolium salt-1 conversion, and glutathione content supported earlier findings of nicotine or nicotine + menthol e-cigarette-induced dose-dependent cytotoxicity and oxidative stress responses. Evaluation of PCLS metabolic activity revealed dose-related impairment of mitochondrial oxidative phosphorylation and glycolysis after exposure to menthol-containing condensates. Taken together, these data demonstrate prominent menthol-induced pulmonary toxicity and impairment of essential physiological functions in the lung, which warrants concerns about e-cigarette consumer safety and emphasizes the need for further investigations of molecular mechanisms of toxicity and menthol effects in an experimental model of disease.

Electronic Cigarette Exposure Increases the Severity of Influenza a Virus Infection via TRAIL Dysregulation in Human Precision-Cut Lung Slices

The use of electronic nicotine dispensing systems (ENDS), also known as electronic cigarettes (ECs), is common among adolescents and young adults with limited knowledge about the detrimental effects on lung health such as respiratory viral infections and underlying mechanisms. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a protein of the TNF family involved in cell apoptosis, is upregulated in COPD patients and during influenza A virus (IAV) infections, but its role in viral infection during EC exposures remains unclear. This study was aimed to investigate the effect of ECs on viral infection and TRAIL release in a human lung precision-cut lung slices (PCLS) model, and the role of TRAIL in regulating IAV infection. PCLS prepared from lungs of nonsmoker healthy human donors were exposed to EC juice (E-juice) and IAV for up to 3 days during which viral load, TRAIL, lactate dehydrogenase (LDH), and TNF-α in the tissue and supernatants were determined. TRAIL neutralizing antibody and recombinant TRAIL were utilized to determine the contribution of TRAIL to viral infection during EC exposures. E-juice increased viral load, TRAIL, TNF-α release and cytotoxicity in IAV-infected PCLS. TRAIL neutralizing antibody increased tissue viral load but reduced viral release into supernatants. Conversely, recombinant TRAIL decreased tissue viral load but increased viral release into supernatants. Further, recombinant TRAIL enhanced the expression of interferon-β and interferon-λ induced by E-juice exposure in IAV-infected PCLS. Our results suggest that EC exposure in human distal lungs amplifies viral infection and TRAIL release, and that TRAIL may serve as a mechanism to regulate viral infection. Appropriate levels of TRAIL may be important to control IAV infection in EC users.