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Background: Waterpipe tobacco (WPT) smoking is associated with deleterious effects on cardio-pulmonary systems which may have adverse repercussions in pathophysiology and progression of chronic lung and cardiovascular diseases. We compared the biomarkers of systemic inflammation, lipid mediators, injury/repair and oxidative stress between groups of non-smokers (NS), exclusive WPT smokers (WPS), exclusive cigarette smokers (CS) and dual WPS and CS (DS)., Methods: Two cohorts were recruited. Cohort I consisted of WPS (n=12), CS (n=26), DS (n=10) and NS (n=25). Cohort II consisted of WPS (n=33) and NS (n=24). Plasma and urine samples were collected and analysed for various systemic biomarkers., Results: Compared with NS, plasma levels of inflammatory mediators (interleukin (IL)-6, IL-8, IL1β and tumor necrosis factor-α) were significantly higher in WPS and CS, and were further augmented in DS. Endothelial biomarkers (intracellular adhesion molecule-1, prostaglandin E-2 and metalloproteinase-9) were significantly higher in CS. Most notably, pro-resolving lipid mediator (resolvin E1) and biomarkers of immunity, tissue injury, and repair were significantly lower in WPS and CS. Urinary levels of 8-isoprostane were significantly higher in all smoking groups in cohort I, while 8-isoprostane, myeloperoxidase, receptor for advanced glycation end products (RAGE), En-RAGE and matrix metalloproteinase-9 were significantly higher in all smoking groups in cohort II., Conclusions: Biomarkers of inflammation, oxidative stress, immunity, tissue injury and repair were elevated in WPS and CS groups. Furthermore, concurrent use of WPT and cigarettes is more harmful than cigarette or WPT smoking alone. These data may help inform the public and policy-makers about the dangers of WPT smoking and dual use of tobacco products., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

E-cigarette flavored pods are increasing in use among young adults. Although marketed as a safer alternative to conventional cigarettes, the health effects of e-cigarette flavored pods are unknown. We hypothesized that e-cigarette flavored pods would cause oxidative stress, barrier dysfunction, and an inflammatory response in monocytes and lung epithelial cells. JUUL pod flavors (Fruit Medley, Virginia Tobacco, Cool Mint, Crème Brulee, Cool Cucumber, Mango, and Classic Menthol) and similar pod flavors (Just Mango-Strawberry Coconut and Caffé Latte) were tested. These pod flavors generated significant amounts of acellular ROS and induced significant mitochondrial superoxide production in bronchial epithelial cells (16-HBE). Lung epithelial cells (16-HBE, BEAS-2B) and monocytes (U937) exposed to various pod aerosols resulted in increased inflammatory mediators, such as IL-8 or PGE 2 . JUUL pod flavors, Crème Brulee and Cool Cucumber, caused epithelial barrier dysfunction in 16-HBE cells. Moreover, tested flavors also showed DNA damage upon exposure in monocytes. We determined the chemical constituents present in various flavors. Our data suggest that these constituents in flavored pods induce oxidative stress, inflammation, epithelial barrier dysfunction, and DNA damage in lung cells. These data provide insights into the regulation of e-cigarette flavored pods, as well as constituents in these flavors.

Electronic-cigarettes (e-cigs) represent a significant and increasing proportion of tobacco product consumption, which may pose an oral health concern. Oxidative/carbonyl stress via protein carbonylation is an important factor in causing inflammation and DNA damage. This results in stress-induced premature senescence (a state of irreversible growth arrest which re-enforces chronic inflammation) in gingival epithelium, which may contribute to the pathogenesis of oral diseases. We show that e-cigs with flavorings cause increased oxidative/carbonyl stress and inflammatory cytokine release in human periodontal ligament fibroblasts, Human Gingival Epithelium Progenitors pooled (HGEPp), and epigingival 3D epithelium. We further show increased levels of prostaglandin-E2 and cycloxygenase-2 are associated with upregulation of the receptor for advanced glycation end products (RAGE) by e-cig exposure-mediated carbonyl stress in gingival epithelium/tissue. Further, e-cigs cause increased oxidative/carbonyl and inflammatory responses, and DNA damage along with histone deacetylase 2 (HDAC2) reduction via RAGE-dependent mechanisms in gingival epithelium. A greater response is elicited by flavored e-cigs. Increased oxidative stress, pro-inflammatory and pro-senescence responses (DNA damage and HDAC2 reduction) can result in dysregulated repair due to proinflammatory and pro-senescence responses in periodontal cells. These data highlight the pathologic role of e-cig aerosol and its flavoring to cells and tissues of the oral cavity in compromised oral health.

Sirtuin 1 (SIRT1) regulates inflammation, aging (life span and health span), calorie restriction/energetics, mitochondrial biogenesis, stress resistance, cellular senescence, endothelial functions, apoptosis/autophagy, and circadian rhythms through deacetylation of transcription factors and histones. SIRT1 level and activity are decreased in chronic inflammatory conditions and aging, in which oxidative stress occurs. SIRT1 is regulated by a NAD(+)-dependent DNA repair enzyme, poly(ADP-ribose) polymerase-1 (PARP1), and subsequent NAD(+) depletion by oxidative stress may have consequent effects on inflammatory and stress responses as well as cellular senescence. SIRT1 has been shown to undergo covalent oxidative modifications by cigarette smoke-derived oxidants/aldehydes, leading to posttranslational modifications, inactivation, and protein degradation. Furthermore, oxidant/carbonyl stress-mediated reduction of SIRT1 leads to the loss of its control on acetylation of target proteins including p53, RelA/p65, and FOXO3, thereby enhancing the inflammatory, prosenescent, and apoptotic responses, as well as endothelial dysfunction. In this review, the mechanisms of cigarette smoke/oxidant-mediated redox posttranslational modifications of SIRT1 and its roles in PARP1 and NF-κB activation, and FOXO3 and eNOS regulation, as well as chromatin remodeling/histone modifications during inflammaging, are discussed. Furthermore, we have also discussed various novel ways to activate SIRT1 either directly or indirectly, which may have therapeutic potential in attenuating inflammation and premature senescence involved in chronic lung diseases., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Sirtuin1 (SIRT1), a type III protein deacetylase, is considered as a novel anti-aging protein involved in regulation of cellular senescence/aging and inflammation. SIRT1 level and activity are decreased during lung inflammaging caused by oxidative stress. The mechanism of SIRT1-mediated protection against inflammaging is associated with the regulation of inflammation, premature senescence, telomere attrition, senescence associated secretory phenotype, and DNA damage response. A variety of dietary polyphenols and pharmacological activators are shown to regulate SIRT1 so as to intervene the progression of type 2 diabetes, cancer, cardiovascular diseases, and chronic obstructive pulmonary disease associated with inflammaging. However, recent studies have shown the non-specific regulation of SIRT1 by the aforementioned pharmacological activators and polyphenols. In this perspective, we have briefly discussed the role of SIRT1 in regulation of cellular senescence and its associated secretory phenotype, DNA damage response, particularly in lung inflammaging and during the development of chronic obstructive pulmonary diseases. We have also discussed the potential directions for future translational therapeutic avenues for SIRT1 in modulating lung inflammaging associated with senescence in chronic lung diseases associated with increased oxidative stress., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Nuclear factor (NF)-κB inducing kinase (NIK) is a central player in the non-canonical NF κB pathway, which phosphorylates IκB kinase α (IKKα) resulting in enhancement of target gene expression. We have recently shown that IKKα responds to a variety of stimuli including oxidants and cigarette smoke (CS) regulating the histone modification in addition to its role in NF-κB activation. However, the primary signaling mechanism linking CS-mediated oxidative stress and TNFα with histone acetylation and pro-inflammatory gene transcription is not well understood. We hypothesized that CS and TNFα increase NIK levels causing phosphorylation of IKKα, which leads to histone acetylation., Methodology: To test this hypothesis, we investigated whether NIK mediates effects of CS and TNFα on histone acetylation in human lung epithelial cells in vitro and in lungs of mouse exposed to CS in vivo. CS increased the phosphorylation levels of IKKα/NIK in lung epithelial cells and mouse lungs. NIK is accumulated in the nuclear compartment, and is recruited to the promoters of pro-inflammatory genes, to induce posttranslational acetylation of histones in response to CS and TNFα. Cells in which NIK is knocked down using siRNA showed partial attenuation of CSE- and TNFα-induced acetylation of histone H3 on pro-inflammatory gene promoters. Additional study to determine the role of IKKβ/NF-κB pathway in CS-induced histone acetylation suggests that the canonical pathway does not play a role in histone acetylation particularly in response to CS in mouse lungs., Conclusions: Overall, our findings provide a novel role for NIK in CS- and TNFα-induced histone acetylation, especially on histone H3K9.

Nrf2, a redox sensitive transcription factor, plays a pivotal role in redox homeostasis during oxidative stress. Nrf2 is sequestered in cytosol by an inhibitory protein Keap1 which causes its proteasomal degradation. In response to electrophilic and oxidative stress, Nrf2 is activated, translocates to nucleus, binds to antioxidant response element (ARE), thus upregulates a battery of antioxidant and detoxifying genes. This function of Nrf2 can be significant in the treatment of diseases, such as cancer, neurodegenerative, cardiovascular and pulmonary complications, where oxidative stress causes Nrf2 derangement. Nrf2 upregulating potential of phytochemicals has been explored, in facilitating cure for various ailments while, in cancer cells, Nrf2 upregulation causes chemoresistance. Therefore, Nrf2 emerges as a key regulator in oxidative stress-mediated diseases and Nrf2 silencing can open avenues in cancer treatment. This review summarizes Nrf2-ARE stress response mechanism and its role as a control point in oxidative stress-induced cellular dysfunctions including chronic inflammatory diseases.

The cyclin-dependent kinase inhibitor p21(CIP1/WAF1/SDI1) (p21) is an important inhibitory checkpoint regulator of cell cycle progression in response to oxidative and genotoxic stresses. It is known that p21 potentiates inflammatory response and inhibits apoptosis and proliferation, leading to cellular senescence. However, the role of endogenous p21 in regulation of lung inflammatory and injurious responses by cigarette smoke (CS) or other pro-inflammatory stimuli is not known. We hypothesized that p21 is an important modifier of lung inflammation and injury, and genetic ablation of p21 will confer protection against CS and other pro-inflammatory stimuli (lipopolysacchride [LPS] and N-formyl-methionyl-leucyl-phenylalanine [fMLP])-mediated lung inflammation and injury. To test this hypothesis, p21-deficient (p21-/-) and wild-type mice were exposed to CS, LPS, or fMLP, and the lung oxidative stress and inflammatory responses as well as airspace enlargement were assessed. We found that targeted disruption of p21 attenuated CS-, LPS-, or fMLP-mediated lung inflammatory responses in mice. CS-mediated oxidative stress and fMLP-induced airspace enlargement were also decreased in lungs of p21-/- mice compared with wild-type mice. The mechanism underlying this finding was associated with decreased NF-kappaB activation, and reactive oxygen species generation by decreased phosphorylation of p47(phox) and down-modulating the activation of p21-activated kinase. Our data provide insight into the mechanism of pro-inflammatory effect of p21, and the loss of p21 protects against lung oxidative and inflammatory responses, and airspace enlargement in response to multiple pro-inflammatory stimuli. These data may have ramifications in CS-induced senescence in the pathogenesis of chronic obstructive pulmonary disease/emphysema.

Vascular endothelial growth factor (VEGF) induces phosphorylation of VEGF receptor-2 (VEGFR-2) and activates the downstream signaling pathway resulting in endothelial cell migration, proliferation, and survival. Cigarette smoking is associated with abnormal vascular and endothelial function, leading to airspace enlargement. Herein, we investigated the mechanism of cigarette smoke (CS) -induced endothelial dysfunction by studying the VEGF-VEGFR-2 signaling in mouse lung and human endothelial cells. CS exposure caused oxidative stress, as shown by increased levels of 4-hydroxy-2-nonenal-adducts in mouse lung and reactive oxygen species generation in human lung microvascular endothelial cells (HMVEC-Ls). Inhibition of VEGFR-2 by a specific kinase inhibitor (NVP-AAD777) enhanced the CS-induced oxidative stress, causing augmented inflammatory cell influx and proinflammatory mediators release in mouse lung. The levels of endothelial nitric oxide synthase (eNOS) and phosphorylated (p) -eNOS in the lungs of mice exposed to CS and/or treated with VEGFR-2 inhibitor were decreased. CS down-regulated VEGFR-2 expression, eNOS levels, and VEGF-induced VEGFR-2 phosphorylation in HMVEC-Ls, resulting in impaired VEGF-induced endothelial cell migration and angiogenesis. Overall, these data show that inhibition of VEGFR-2 augmented CS-induced oxidative stress and inflammatory responses leading to endothelial dysfunction. This explains the mechanism of endothelial dysfunction in smokers and has implications in understanding the pathogenesis of pulmonary and cardiovascular diseases.

Cigarette smoke (CS) induces abnormal and sustained lung inflammation; however, the molecular mechanism underlying sustained inflammation is not known. It is well known that activation of I kappaB kinase beta (IKK beta) leads to transient translocation of active NF-kappaB (RelA/p65-p50) in the nucleus and transcription of pro-inflammatory genes, whereas the role of IKK alpha in perpetuation of sustained inflammatory response is not known. We hypothesized that CS activates IKK alpha and causes histone acetylation on the promoters of pro-inflammatory genes, leading to sustained transcription of pro-inflammatory mediators in mouse lung in vivo and in human monocyte/macrophage cell line (MonoMac6) in vitro. CS exposure to C57BL/6J mice resulted in activation of IKK alpha, leading to phosphorylation of ser10 and acetylation of lys9 on histone H3 on the promoters of IL-6 and MIP-2 genes in mouse lung. The increased level of IKK alpha was associated with increased acetylation of lys310 RelA/p65 on pro-inflammatory gene promoters. The role of IKK alpha in CS-induced chromatin modification was confirmed by gain and loss of IKK alpha in MonoMac6 cells. Overexpression of IKK alpha was associated with augmentation of CS-induced pro-inflammatory effects, and phosphorylation of ser10 and acetylation of lys9 on histone H3, whereas transfection of IKK alpha dominant-negative mutants reduced CS-induced chromatin modification and pro-inflammatory cytokine release. Moreover, phosphorylation of ser276 and acetylation of lys310 of RelA/p65 was augmented in response to CS extract in MonoMac6 cells transfected with IKK alpha. Taken together, these data suggest that IKK alpha plays a key role in CS-induced pro-inflammatory gene transcription through phospho-acetylation of both RelA/p65 and histone H3.

Reactive oxygen species (ROS) play a key role in enhancing the inflammation through the activation of NF-kappaB and AP-1 transcription factors, and nuclear histone acetylation and deacetylation in various inflammatory diseases. Such undesired effects of oxidative stress have been found to be controlled by the antioxidant and/or anti-inflammatory effects of dietary polyphenols such as curcumin (diferuloylmethane, a principal component of turmeric) and resveratrol (a flavonoid found in red wine). The phenolic compounds in fruits, vegetables, tea and wine are mostly derivatives, and/or isomers of flavones, isoflavones, flavonols, catechins, tocopherols, and phenolic acids. Polyphenols modulate important cellular signaling processes such as cellular growth, differentiation and host of other cellular features. In addition, they modulate NF-kappaB activation, chromatin structure, glutathione biosynthesis, nuclear redox factor (Nrf2) activation, scavenge effect of ROS directly or via glutathione peroxidase activity and as a consequence regulate inflammatory genes in macrophages and lung epithelial cells. However, recent data suggest that dietary polyphenols can work as modifiers of signal transduction pathways to elicit their beneficial effects. The effects of polyphenols however, have been reported to be more pronounced in vitro using high concentrations which are not physiological in vivo. This commentary discusses the recent data on dietary polyphenols in the control of signaling and inflammation particularly during oxidative stress, their metabolism and bioavailability.

Changes in the ratio of intracellular reduced and disulfide forms of glutathione (GSH/GSSG) can affect signaling pathways that participate in various physiological responses from cell proliferation to gene expression and apoptosis. It is also now known that many proteins have a highly conserved cysteine (sulfhydryl) sequence in their active/regulatory sites, which are primary targets of oxidative modifications and thus important components of redox signaling. However, the mechanism by which oxidants and GSH/protein-cysteine-thiols actually participate in redox signaling still remains to be elucidated. Initial studies involving the role of cysteine in various proteins have revealed that cysteine-SH may mediate redox signaling via reversible or irreversible oxidative modification to Cys-sulfenate or Cys-sulfinate and Cys-sulfonate species, respectively. Oxidative stress possibly via the modification of cysteine residues activates multiple stress kinase pathways and transcription factors nuclear factor-kappaB and activator protein-1, which differentially regulate the genes for proinflammatory cytokines as well as the protective antioxidant genes. Understanding the redox signaling mechanisms for differential gene regulation may allow for the development of novel pharmacological approaches that preferentially up-regulate key antioxidants genes, which, in turn, reduce or resolve inflammation and injury. This forum article features the current knowledge on the role of GSH in redox signaling, particularly the regulation of transcription factors and downstream signaling in lung inflammation.

Nicotine inhalation via electronic cigarettes (e-cigs) is an emerging concern. However, little is known about the acute toxicity in the lungs following inhalation of nicotine-containing e-cig aerosols. We hypothesized that acute exposure to aerosolized nicotine causes lung toxicity by eliciting inflammatory and dysregulated repair responses. Adult C57BL/6J mice were exposed 2 h daily for 3 days to e-cig aerosols containing propylene glycol (PG) with or without nicotine. Acute exposure to nicotine-containing e-cig aerosols induced inflammatory cell influx (neutrophils and CD8a+ T-lymphocytes), and release of pro-inflammatory cytokines in bronchoalveolar lavage fluid in a sex-dependent manner. Inhalation of e-cig aerosol containing PG alone significantly augmented the lung levels of various homeostasis/repair mediators (PPARγ, ADRP, ACTA2, CTNNB1, LEF1, β-catenin, E-cadherin, and MMP2) in a sex-dependent manner when compared to air controls. These findings were accompanied by an increase in protein abundance and altered gene expression of lipogenic markers (PPARγ, ADRP) and myogenic markers (fibronectin, α-smooth muscle actin and β-catenin), suggesting a dysregulated repair response in mouse lungs. Furthermore, exposure to nicotine containing e-cig aerosols or PG alone differentially affected the release of pro-inflammatory cytokines in healthy and COPD human 3D EpiAirway tissues. Overall, acute exposure to nicotine containing e-cig aerosols was sufficient to elicit a pro-inflammatory response and altered mRNA and protein levels of myogenic, lipogenic, and extracellular matrix markers in mouse lung in a sex-dependent manner. Thus, acute exposure to inhaled nicotine via e-cig leads to dysregulated repair and inflammatory responses, which may lead to airway remodeling in the lungs.

Emerging epidemiological evidence indicates perfluorooctane sulfonic acid (PFOS) is increasingly associated with asthma and respiratory viral infections. Animal studies suggest PFOS disrupts lung development and immuno-inflammatory responses, but little is known about the potential consequences on respiratory health and disease risk. Importantly, PFOS exposure during the critical stages of lung development may increase disease risk later in life. Thus, we hypothesized that developmental PFOS exposure will affect lung inflammation and alveolar/airway development in a sex-dependent manner. To address this knowledge gap, timed pregnant Balb/cJ dams were orally dosed with a PFOS (1.0 or 2.0 mg/kg/d) injected mealworm or a vehicle control daily from gestational day (GD) 0.5 to postnatal day (PND) 21, and offspring were sacrificed at PND 22-23. PFOS-exposed male offspring displayed increased alveolar septa thickness. Occludin was also downregulated in the lungs after PFOS exposure in mice, indicative of barrier dysfunction. BALF macrophages were significantly elevated at 2.0 mg/kg/d PFOS in both sexes compared with vehicles, whereas BALF cytokines (TNF-α, IL-6, KC, MIP-1α, MIP-1β, and MCP-1) were suppressed in PFOS-exposed male offspring compared with vehicle controls. Multiplex nucleic acid hybridization assay showed male-specific downregulation of cytokine gene expression in PFOS-exposed mice compared with vehicle mice. Overall, these results demonstrate PFOS exposure exhibits male-specific adverse effects on lung development and inflammation in juvenile offspring, possibly predisposing them to later-in-life respiratory disease. Further research is required to elucidate the mechanisms underlying the sex-differentiated pulmonary toxicity of PFOS. [ABSTRACT FROM AUTHOR]

Oral nicotine pouches (ONPs) are a modern form of smokeless tobacco products sold by several brands in the U.S., which comprise a significant portion of non-combustible nicotine-containing product (NCNP) sales to date. ONPs are available in various flavors and may contain either tobacco-derived nicotine (TDN) or tobacco-free nicotine (TFN). The growth in popularity of these products has raised concerns that flavored ONPs may cause adverse oral health effects and promote systemic toxic effects due to nicotine and other ONP by-products being absorbed into the circulatory system through oral mucosa. We hypothesized that flavored ONPs are unsafe and likely to cause oral and pulmonary inflammation in oral and respiratory epithelial cells. Before analyzing the effects of ONPs, we first classified ONPs sold in the U.S. based on their flavor and the flavor category to which they belonged using a wheel diagram. Human gingival epithelial cells (HGEP) were treated with flavored ONP extracts of tobacco (original, smooth), menthol (wintergreen and cool cider), and fruit flavor (americana and citrus), each from the TDN and TFN groups. The levels of ONP-induced inflammatory cytokine release (TNF-α, IL-6, and IL-8) by ELISA, cellular reactive oxygen species (ROS) production by CellRox Green, and cytotoxicity by lactate dehydrogenase (LDH) release assay in HGEP cells were assessed. Flavored ONP extracts elicited differential toxicities in a dose- and extract-dependent manner in HGEP cells 24 h post-treatment. Both fruit TDN and TFN extracts resulted in the greatest cytotoxicity. Tobacco- and fruit-flavored, but not menthol-flavored, ONPs resulted in increased ROS production 4 h post-treatment. Flavored ONPs led to differential cytokine release (TNF-α, IL-6, and IL-8) which varied by flavor (menthol, tobacco, or fruit) and nicotine (TDN vs. TFN) 24 h post-treatment. Menthol-flavored ONPs led to the most significant TNF-α release; fruit TFN resulted in the most significant IL-6 release; and fruit TDN and tobacco TFN led to the highest release of IL-8. Subsequently, human bronchial epithelial cells (16-HBE and BEAS-2B) were also treated with flavored ONP extracts, and similar assays were evaluated. Here, the lowest concentration treatments displayed increased cytotoxicity. The most striking response was observed among cells treated with spearmint and tobacco flavored ONPs. Our data suggest that flavored ONPs are unsafe and likely to cause systemic and local toxicological responses during chronic usage. [ABSTRACT FROM AUTHOR]

Flavoring chemicals in electronic nicotine delivery systems have been shown to cause cellular inflammation; meanwhile, the effects of fruit and tobacco flavors on lung inflammation by nose-only exposures to mice are relatively unknown. We hypothesized that exposure to flavored e-cigarettes would cause lung inflammation in C57BL/6 J mice. The mice were exposed to air, propylene glycol/vegetable glycerin, and flavored e-liquids: Apple, Cherry, Strawberry, Wintergreen, and Smooth & Mild Tobacco, one hour per day for three days. Quantification of flavoring chemicals by proton nuclear magnetic resonance spectroscopy (1H NMR), differential cell counts by flow cytometry, pro-inflammatory cytokines/chemokines by ELISA, and matrix metalloproteinase levels by western blot were performed. Exposure to PG/VG increased neutrophil cell count in lung bronchoalveolar lavage fluid (BALF). KC and IL6 levels were increased by PG/VG exposure and female mice exposed to Cherry flavored e-cigarettes, in lung homogenate. Mice exposed to PG/VG, Apple, Cherry, and Wintergreen increased MMP2 levels. Our results revealed flavor- and sex-based e-cigarette effects in female mice exposed to cherry-flavored e-liquids and male mice exposed to tobacco-flavored e-liquids, namely, increased lung inflammation. [ABSTRACT FROM AUTHOR]

Background: Tobacco smoking is known to be involved in the pathogenesis of several cardiopulmonary diseases. Additionally, smokers are highly susceptible to infectious agents due to weakened immunity. However, the progression of lung injury based on SARS-CoV-2-mediated COVID-19 pathogenesis amongst smokers and those with pre-existing pulmonary diseases is not known. We determined the systemic levels and activity of COVID-19 associated proteins, cytokine/chemokines, and lipid mediators (lipidomics) amongst COVID-19 patients with and without a history of smoking to understand the underlying susceptible factor in the pathogenesis of COVID-19. Methods: We obtained serum from healthy (CoV−), COVID-19 positive (CoV+), and COVID-19 recovered (CoV Rec) subjects with and without a history of smoking. We conducted a Luminex multiplex assay (cytokine levels), LC/MS (eicosanoids or oxylipin panel), and ACE2 enzymatic activity assays on the serum samples to determine the systemic changes in COVID-19 patients. Results: On comparing the levels of serum ACE2 amongst COVID-19 (positive and recovered) patients and healthy controls, we found a pronounced increase in serum ACE2 levels in patients with COVID-19 infection. Furthermore, ACE2 enzyme activity was significantly increased amongst COVID-19 patients with a smoking history. Also, we analyzed the levels of Angiotensin 1–7 (Ang1–7) peptide, the product of enzymatic action of ACE2, in the serum samples. We found significantly high levels of Ang1–7 in the serum of both CoV+ and CoV Rec patients. Our data further demonstrated a smoking-induced increase in serum furin and inflammatory cytokine [IFNγ(p = 0.0836), Eotaxin (p < 0.05), MCP-1 (p < 0.05), and IL-9 (p = 0.0991)] levels in COVID-19 patients as compared to non-smoking controls. Overall, our results show that smoking adversely affects the levels of systemic inflammatory markers and COVID-19 associated proteins, thus suggesting that COVID-19 infection may have severe outcomes amongst smokers. [ABSTRACT FROM AUTHOR]

Chronic airway inflammation from recurring exposures to noxious environmental stimuli results in a progressive and irreversible airflow limitation and the lung parenchymal damage that characterizes chronic obstructive pulmonary disease (COPD). The large variability observed in the onset and progression of COPD is primarily driven by complex gene-environment interactions. The transcriptomic and epigenetic memory potential of lung epithelial and innate immune cells drive responses, such as mucus hyperreactivity and airway remodeling, that are tightly regulated by various molecular mechanisms, for which several candidate susceptibility genes have been described. However, the recently described noncoding RNA species, in particular the long noncoding RNAs, may also have an important role in modulating pulmonary responses to chronic inhalation of toxic substances and the development of COPD. This review outlines the features of long noncoding RNAs that have been implicated in regulating the airway inflammatory responses to cigarette smoke exposure and their possible association with COPD pathogenesis. As COPD continues to debilitate the increasingly aging population and contribute to higher morbidity and mortality rates worldwide, the search for better biomarkers and alternative therapeutic options is pivotal. [ABSTRACT FROM AUTHOR]

The oral cavities of tobacco smokers and users of smokeless tobacco products are exposed to high concentrations of nicotine. A limited number of animal studies have assessed the effect of nicotine on osseointegration. Results from experimental studies have reported a statistically significant decrease, at 4 weeks of follow-up, in bone-to-implant contact among rats exposed to nicotine compared with unexposed rats. Nicotine increases the production of inflammatory cytokines (such as interleukin-6 and tumor necrosis factor-alpha) by osteoblasts. Waterpipe, pipe, and cigarette smokers are at increased risk of developing oral cancer, periodontal disease, and alveolar bone loss. One explanation for this is that smokers (regardless of the type of tobacco product) are exposed to similar chemicals, such as nicotine, tar, oxidants, polyaromatic hydrocarbons, and carbon monoxide. Moreover, raised levels of proinflammatory cytokines have been identified in the gingival crevicular fluid of cigarette smokers with peri-implant diseases. Therefore, it is hypothesized that nicotine and chemicals in tobacco smoke induce a state of oxidative stress in peri-implant tissues (gingiva and alveolar bone), thereby increasing the likelihood of peri-implant disease development via an inflammatory response, which if left uncontrolled, will result in implant failure/loss. In this regard, tobacco smoking (including cigarettes, waterpipe, and pipe) is a significant risk factor for peri-implant diseases. The impact of vaping electronic cigarettes using nicotine-containing e-juices remains unknown. Habitual use of smokeless tobacco products is associated with oral inflammatory conditions, such as oral precancer, cancer, and periodontal disease. However, the effect of habitual use of smokeless tobacco products on the success and survival of dental implants remains undocumented. [ABSTRACT FROM AUTHOR]

Cigarette smoke (CS) affects DNA damage and cellular senescence signaling pathways in the pathogenesis of chronic obstructive pulmonary disease (COPD). p16INK4a (p16: a cyclin-dependent kinase inhibitor) is a key marker of cellular senescence, which is induced by CS in lung cells. It is thought that removal of p16 attenuates premature aging by removing senesced cells. However, the role of p16 in CS-induced stress-induced premature senescence (SIPS) and senescence-associated secretory phenotype (SASP) during the development of COPD/emphysema is not known. We hypothesize that p16 regulates cellular senescence and DNA damage/repair molecular signaling targets during chronic CS–induced inflammation and airspace enlargement in mouse models of COPD. We used p16 global knockout (KO) and p16 lung epithelial cell–specific KO (p16CreCC10) mice to determine whether p16 removal in lung epithelium augments or protects against cellular senescence (SIPS and SASP) in chronic CS– and elastase-induced development of COPD/emphysema in mice. p16 KO mice exposed to chronic CS and p16 lung epithelial cell–specific KO mice exposed to elastase did not show attenuation of lung inflammation, altered lung function, or airspace enlargement. p16 KO and p16CreCC10 exposed to CS and elastase showed increases in lung senescence-associated β-galactosidase activity. Thus, removal of p16-positive cells did not protect against airspace enlargement and decline in lung function induced in COPD mouse models. Our findings suggest that p16 is not the only key player associated with CS-induced cellular senescence phenotypes (SIPS and SASP), decline in lung function, and airspace enlargement in COPD/emphysema. [ABSTRACT FROM AUTHOR]

Background: The respiratory health effects of inhalation exposure to e-cigarette flavoring chemicals are not well understood. We focused our study on the immuno-toxicological and the oxidative stress effects by these e-cigarette flavoring chemicals on two types of human monocytic cell lines, Mono Mac 6 (MM6) and U937. The potential to cause oxidative stress by these flavoring chemicals was assessed by measuring the production of reactive oxygen species (ROS). We hypothesized that the flavoring chemicals used in e-juices/e-liquids induce an inflammatory response, cellular toxicity, and ROS production. Methods: Two monocytic cell types, MM6 and U937 were exposed to commonly used e-cigarette flavoring chemicals; diacetyl, cinnamaldehyde, acetoin, pentanedione, o-vanillin, maltol and coumarin at different doses between 10 and 1,000 μM. Cell viability and the concentrations of the secreted inflammatory cytokine interleukin 8 (IL-8) were measured in the conditioned media. Cell-free ROS produced by these commonly used flavoring chemicals were also measured using a 2',7'dichlorofluorescein diacetate probe. These DCF fluorescence data were expressed as hydrogen peroxide (H2O2) equivalents. Cytotoxicity due to the exposure to selected e-liquids was assessed by cell viability and the IL-8 inflammatory cytokine response in the conditioned media. Results: Treatment of the cells with flavoring chemicals and flavored e-liquid without nicotine caused cytotoxicity dose-dependently. The exposed monocytic cells secreted interleukin 8 (IL-8) chemokine in a dose-dependent manner compared to the unexposed cell groups depicting a biologically significant inflammatory response. The measurement of cell-free ROS by the flavoring chemicals and e-liquids showed significantly increased levels of H2O2 equivalents in a dose-dependent manner compared to the control reagents. Mixing a variety of flavors resulted in greater cytotoxicity and cell-free ROS levels compared to the treatments with individual flavors, suggesting that mixing of multiple flavors of e-liquids are more harmful to the users. Conclusions: Our data suggest that the flavorings used in e-juices can trigger an inflammatory response in monocytes, mediated by ROS production, providing insights into potential pulmonary toxicity and tissue damage in e-cigarette users. [ABSTRACT FROM AUTHOR]

Antagonism of CXCR2 receptors, predominately located on neutrophils and critical for their immunomodulatory activity, is an attractive pharmacological therapeutic approach aimed at reducing the potentially damaging effects of heightened neutrophil influx into the lung. The role CXCR2 in lung inflammation in response to cigarette smoke (CS) inhalation using the mutant mouse approach is not known. We hypothesized that genetic ablation of CXCR2 would protect mice against CS-induced inflammation and DNA damage response. We used CXCR2-/-deficient/mutant (knock-out, KO) mice, and assessed the changes in critical lung inflammatory NF-ΚB-driven chemokines released from the parenchyma of CS-exposed mice. The extent of tissue damage was assessed by the number of DNA damaging γH2AX positive cells. CXCR2 KO mice exhibited protection from heightened levels of neutrophils measured in BALF taken from mice exposed to CS. IL-8 (KC mouse) levels in the BALF from CS-exposed CXCR2 KO were elevated compared to WT. IL-6 levels in BALF were refractory to increase by CS in CXCR2 KO mice. There were no significant changes to MIP-2, MCP-1, or IL-1β. Total levels of NF-ΚB were maintained at lower levels in CS-exposed CXCR2 KO mice compared to WT mice exposed to CS. Finally, CXCR2 KO mice were protected from lung cells positive for DNA damage response and senescence marker γH2AX. CXCR2 KO mice are protected from heightened inflammatory response mediated by increased neutrophil response as a result of acute 3 day CS exposure. This is also associated with changes in pro-inflammatory chemokines and reduced incursion of γH2AX indicating CXCR2 deficient mice are protected from lung injury. Thus, CXCR2 may be a pharmacological target in setting of inflammation and DNA damage in the pathogenesis of COPD. [ABSTRACT FROM AUTHOR]

Background: There is a dearth of studies that have compared clinical and radiologic markers of periodontal inflammation between water-pipe smokers (WPs) and cigarette smokers (CSs). The aim of the present study is to compare the clinical and radiographic periodontal status between habitual WPs and CSs.Methods: In total, 200 males (50 WPs, 50 CSs, and 100 controls) with comparable mean age and education were included. Demographic information was recorded using a questionnaire. Periodontal parameters (plaque index [PI], bleeding on probing [BOP], probing depth [PD], clinical attachment loss [AL], and marginal bone loss [MBL]) and numbers of missing teeth (MT) were recorded.Results: The duration of each smoking session for WPs and CSs was 50.2 ± 6.7 and 15.3 ± 0.4 minutes, respectively. Number of MT [P <0.0001], PI [P <0.0001], AL [P <0.0001], PD ≥4 mm [P <0.0001], and MBL [P <0.0001]) was significantly higher among WPs and CSs than controls. BOP was significantly higher among controls than WPs (P <0.0001) and CSs (P <0.0001). There was no statistically significant difference in the aforementioned parameters between WPs and CSs.Conclusions: Males in a Saudi Arabian community who were CSs or WPs had more MT and poorer periodontal condition than never smokers. The periodontal condition of WPs was equally as poor as CSs. Additional clinical observational studies with emphasis on sex and sociodemographic characteristics are needed. [ABSTRACT FROM AUTHOR]

Patients with obstructive lung diseases display abnormal circadian rhythms in lung function. We determined the mechanism whereby environmental tobacco/cigarette smoke (CS) modulates expression of the core clock gene BMAL1, through Sirtuinl (SIRT1) deacetylase during lung inflammatory and injurious responses. Adult C57BL6/J and various mice mutant for SIRT1 and BMAL1 were exposed to both chronic (6 mo) and acute (3 and 10 d) CS, and we measured the rhythmic expression of clock genes, circadian rhythms of locomotor activity, lung function, and inflammatory and emphysematous responses in the lungs. CS exposure (100-300 mg/m³ particulates) altered clock gene expression and reduced locomotor activity by disrupting the central and peripheral docks and increased lung inflammation, causing emphysema in mice. BMAL1 was acetylated and degraded in the lungs of mice exposed to CS and in patients with chronic obstructive pulmonary disease (COPD), compared with lungs of the nonsmoking controls, linking it mechanistically to CS-induced reduction of SIRT1. Targeted deletion of Bmal1 in lung epithelium augmented inflammation in response to CS, which was not attenuated by the selective SIRT1 activator SRT1720 (EC50 = 0.16 µM) in these mice. Thus, the circadian clock, specifically the enhancer BMAL1 in epithelium, plays a pivotal role, mediated by SIRT1-dependent BMAL1, in the regulation of CS-induced lung inflammatory and injurious responses. [ABSTRACT FROM AUTHOR]

Histone deacetylase 2 (HDAC2) is a class I histone deacetylase that regulates various cellular processes, such as cell cycle, senescence, proliferation, differentiation, development, apoptosis, and glucocorticoid function in inhibiting inflammatory response. HDAC2 has been shown to protect against DNA damage response and cellular senescence/premature aging via an epigenetic mechanism in response to oxidative stress. These phenomena are observed in patients with chronic obstructive pulmonary disease (COPD). HDAC2 is posttranslationally modified by oxidative/carbonyl stress imposed by cigarette smoke and oxidants, leading to its reduction via an ubiquitination-proteasome dependent degradation in lungs of patients with COPD. In this perspective, we have discussed the role of HDAC2 posttranslational modifications and its role in regulation of inflammation, histone/DNA epigenetic modifications, DNA damage response, and cellular senescence, particularly in inflammaging, and during the development of COPD. We have also discussed the potential directions for future translational research avenues in modulating lung inflammaging and cellular senescence based on epigenetic chromatin modifications in diseases associated with increased oxidative stress. [ABSTRACT FROM AUTHOR]

Background: Nuclear factor (NF)-kB inducing kinase (NIK) is a central player in the non-canonical NF kB pathway, which phosphorylates IkB kinase a (IKKa) resulting in enhancement of target gene expression. We have recently shown that IKKa responds to a variety of stimuli including oxidants and cigarette smoke (CS) regulating the histone modification in addition to its role in NF-kB activation. However, the primary signaling mechanism linking CS-mediated oxidative stress and TNFa with histone acetylation and pro-inflammatory gene transcription is not well understood. We hypothesized that CS and TNFa increase NIK levels causing phosphorylation of IKKa, which leads to histone acetylation. Methodology: To test this hypothesis, we investigated whether NIK mediates effects of CS and TNFa on histone acetylation in human lung epithelial cells in vitro and in lungs of mouse exposed to CS in vivo. CS increased the phosphorylation levels of IKKa/NIK in lung epithelial cells and mouse lungs. NIK is accumulated in the nuclear compartment, and is recruited to the promoters of pro-inflammatory genes, to induce posttranslational acetylation of histones in response to CS and TNFa. Cells in which NIK is knocked down using siRNA showed partial attenuation of CSE- and TNFa-induced acetylation of histone H3 on pro-inflammatory gene promoters. Additional study to determine the role of IKKb/NF-kB pathway in CS-induced histone acetylation suggests that the canonical pathway does not play a role in histone acetylation particularly in response to CS in mouse lungs. Conclusions: Overall, our findings provide a novel role for NIK in CS- and TNFa-induced histone acetylation, especially on histone H3K9. [ABSTRACT FROM AUTHOR]

Abstract: Chronic obstructive pulmonary disease (COPD) is a global health problem. The current therapies for COPD are poorly effective and the mainstays of pharmacotherapy are bronchodilators. A better understanding of the pathobiology of COPD is critical for the development of novel therapies. In the present review, we have discussed the roles of oxidative/aldehyde stress, inflammation/immunity, and chromatin remodeling in the pathogenesis of COPD. An imbalance of oxidants/antioxidants caused by cigarette smoke and other pollutants/biomass fuels plays an important role in the pathogenesis of COPD by regulating redox-sensitive transcription factors (e.g., NF-κB), autophagy and unfolded protein response leading to chronic lung inflammatory response. Cigarette smoke also activates canonical/alternative NF-κB pathways and their upstream kinases leading to sustained inflammatory response in lungs. Recently, epigenetic regulation has been shown to be critical for the development of COPD because the expression/activity of enzymes that regulate these epigenetic modifications have been reported to be abnormal in airways of COPD patients. Hence, the significant advances made in understanding the pathophysiology of COPD as described herein will identify novel therapeutic targets for intervention in COPD. [Copyright &y& Elsevier]

Peroxiredoxin 6 (Prdx6) exerts its protective role through peroxidase activity against H2O2 and phospholipid hydroperoxides. We hypothesized that targeted disruption of Prdx6 would lead to enhanced susceptibility to cigarette smoke (CS)-mediated lung inflammation and/or emphysema in mouse lung. Prdx6 null (Prdx6−/−) mice exposed to acute CS showed no significant increase of inflammatory cell influx or any alterations in lung levels of proinflammatory cytokines compared to wild-type (WT) mice. Lung levels of antioxidant enzymes were significantly increased in acute CS-exposed Prdx6−/− compared to WT mice. Overexpressing (Prdx6+/+) mice exposed to acute CS showed significant decrease in lung antioxidant enzymes associated with increased inflammatory response compared to CS-exposed WT mice or air-exposed Prdx6−/− mice. However, chronic 6 months of CS exposure resulted in increased lung inflammatory response, mean linear intercept (Lm), and alteration in lung mechanical properties in Prdx6−/− when compared to WT mice exposed to CS. These data show that targeted disruption of Prdx6 does not lead to increased lung inflammatory response but is associated with increased antioxidants, suggesting a critical role of lung Prdx6 and several compensatory mechanisms during acute CS-induced adaptive response, whereas this protection is lost in chronic CS exposure leading to emphysema. [ABSTRACT FROM AUTHOR]

Sirtuin1 (SIRT1) deacetylase levels are decreased in chronic inflammatory conditions and aging where oxidative stress occurs. We determined the mechanism of SIRT1 redox post-translational modifications leading to its degradation. Human lung epithelial cells exposed to hydrogen peroxide (150-250µM), aldehyde-acrolein (10-30µM), and cigarette smoke extract (CSE; 0.1-1.5%) in the presence of intracellular glutathione-modulating agents at 1-24 h, and oxidative post-translational modifications were assayed in cells, as well as in lungs of mice lacking and overexpressing glutaredoxin-1 (Glrx1), and wild-type (WT) mice in response to cigarette smoke (CS). CSE and aldehydes dose and time dependently decreased SIRT1 protein levels, with EC50 of 1% for CSE and 30µM for acrolein at 6 h, and >80% inhibition at 24 h with CSE, which was regulated by modulation of intracellular thiol status of the cells. CS decreased the lung levels of SIRT1 in WT mice, which was enhanced by deficiency of Glrx1 and prevented by overexpression of Glrx1. Oxidants, aldehydes, and CS induced carbonyl modifications on SIRT1 on cysteine residues concomitant with decreased SIRT1 activity. Proteomics studies revealed alkylation of cysteine residue on SIRT1. Our data suggest that oxidants/aldehydes covalently modify SIRT1, decreasing enzymatic activity and marking the protein for proteasomal degradation, which has implications in inflammatory conditions. [ABSTRACT FROM AUTHOR]

Abstract: Histone deacetylase 2 (HDAC2) mediates the repression of pro-inflammatory genes by deacetylating core histones, RelA/p65 and the glucocorticoid receptor. Reduced level of HDAC2 is associated with steroid resistant inflammation caused by cigarette smoke (CS)-derived oxidants and aldehydes. However, the molecular mechanisms regulating HDAC2 in response to CS and aldehydes is not known. Here, we report that CS extract, and aldehyde acrolein induced phosphorylation of HDAC2 which was abolished by mutations at serine sites S394, S411, S422 and S424. HDAC2 phosphorylation required direct interaction with serine-phosphorylated protein kinase CK2α and involved reduced HDAC2 deacetylase activity. Furthermore, HDAC2 phosphorylation was required for HDAC2 interaction with transcription factors, co-repressor complex formation, CBP recruitment, acetylation on lysine residues and modulates transrepression activity. Thus, phospho-acetylation of HDAC2 negatively regulates its deacetylase activity which has implications in steroid resistance in chronic inflammatory conditions. [Copyright &y& Elsevier]

Background: Chronic obstructive pulmonary disease is associated with numerous vascular effects including endothelial dysfunction, arterial stiffness and atherogenesis. It is also known that a decline in lung function is associated with increased cardiovascular comorbidity in smokers. The mechanism of this cardiopulmonary dual risk by cigarette smoke (CS) is not known. We studied the molecular mechanisms involved in development of emphysema in atherosclerosis-prone apolipoprotein E-deficient (ApoE-/-) mice in response to CS exposure. Methods: Adult male and female wild-type (WT) mice of genetic background C57BL/6J and ApoE-/- mice were exposed to CS, and lung inflammatory responses, oxidative stress (lipid peroxidation products), mechanical properties as well as airspace enlargement were assessed. Results and Discussion: The lungs of ApoE-/- mice showed augmented inflammatory response and increased oxidative stress with development of distal airspace enlargement which was accompanied with decline in lung function. Interestingly, the levels and activities of matrix metalloproteinases (MMP-9 and MMP-12) were increased, whereas the level of eNOS was decreased in lungs of CS-exposed ApoE-/- mice as compared to air-exposed ApoE-/- mice or CS-exposed WT mice. Conclusion: These findings suggest that CS causes premature emphysema and a decline of lung function in mice susceptible to cardiovascular abnormalities via abnormal lung inflammation, increased oxidative stress and alterations in levels of MMPs and eNOS. [ABSTRACT FROM AUTHOR]

Abstract: Glutathione (γ-glutamyl-cysteinyl-glycine, GSH) is the most abundant intracellular antioxidant thiol and is central to redox defense during oxidative stress. GSH metabolism is tightly regulated and has been implicated in redox signaling and also in protection against environmental oxidant-mediated injury. Changes in the ratio of the reduced and disulfide form (GSH/GSSG) can affect signaling pathways that participate in a broad array of physiological responses from cell proliferation, autophagy and apoptosis to gene expression that involve H2O2 as a second messenger. Oxidative stress due to oxidant/antioxidant imbalance and also due to environmental oxidants is an important component during inflammation and respiratory diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and asthma. It is known to activate multiple stress kinase pathways and redox-sensitive transcription factors such as Nrf2, NF-κB and AP-1, which differentially regulate the genes for pro-inflammatory cytokines as well as the protective antioxidant genes. Understanding the regulatory mechanisms for the induction of antioxidants, such as GSH, versus pro-inflammatory mediators at sites of oxidant-directed injuries may allow for the development of novel therapies which will allow pharmacological manipulation of GSH synthesis during inflammation and oxidative injury. This article features the current knowledge about the role of GSH in redox signaling, GSH biosynthesis and particularly the regulation of transcription factor Nrf2 by GSH and downstream signaling during oxidative stress and inflammation in various pulmonary diseases. We also discussed the current therapeutic clinical trials using GSH and other thiol compounds, such as N-acetyl-l-cysteine, fudosteine, carbocysteine, erdosteine in environment-induced airways disease. [Copyright &y& Elsevier]

A variety of mouse models have been used to study the pathogenesis of pulmonary emphysemal chronic obstructive pulmonary disease. The effect of cigarette smoke (CS) is believed to be strain dependent, because certain mouse strains are more susceptible or resistant to development of emphysema. However, the molecular basis of susceptibility of mouse strains to effects of CS is not known. We investigated the effect of CS on lungs of most of the commonly used mouse strains to study the molecular mechanism of susceptibility to effects of CS. C57BL/6J, A/J, AKR/J, CD-1, and 129SvJ mice were exposed to CS for 3 consecutive days, and various parameters of inflammatory and oxidative responses were assessed in lungs of these mice. We found that the C57BL/6J strain was highly susceptible, the A/J, AKR/J, and CD-1 strains were moderately susceptible, and the 129SvJ strain was resistant to lung inflammatory and oxidant responses to CS exposure. The mouse strain that was more susceptible to effects of CS showed augmented lung inflammatory cell influx, activation of NF-κB and p38 MAPK, and increased levels of matrix metalloproteinase-9 and NF-κB-dependent proinflammatory cytokines compared with resistant mouse strains. Similarly, decreased levels of glutathione were associated with increased levels of lipid peroxidation products in susceptible mouse strains compared with resistant strains. Hence, we identified the susceptible and resistant mouse strains on the basis of the pattern of inflammatory and oxidant responses. Identification of sensitive and resistant mouse strains could be useful for studying the molecular mechanisms of effects of CS on inflammation and pharmacological interventional studies in CS-exposure mouse models. [ABSTRACT FROM AUTHOR]

Abstract: Asthma and chronic obstructive pulmonary disease (COPD) are inflammatory lung diseases that are characterized by systemic and chronic localized inflammation and oxidative stress. Sources of oxidative stress arise from the increased burden of inhaled oxidants, as well as elevated amounts of reactive oxygen species (ROS) released from inflammatory cells. Increased levels of ROS, either directly or via the formation of lipid peroxidation products, may play a role in enhancing the inflammatory response in both asthma and COPD. Moreover, in COPD it is now recognized as the main pathogenic factor for driving disease progression and increasing severity. ROS and lipid peroxidation products can influence the inflammatory response at many levels through its impact on signal transduction mechanisms, activation of redox-sensitive transcriptions factors, and chromatin regulation resulting in pro-inflammatory gene expression. It is this impact of ROS on chromatin regulation by reducing the activity of the transcriptional co-repressor, histone deacetylase-2 (HDAC-2), that leads to the poor efficacy of corticosteroids in COPD, severe asthma, and smoking asthmatics. Thus, the presence of oxidative stress has important consequences for the pathogenesis, severity, and treatment of asthma and COPD. However, for ROS to have such an impact, it must first overcome a variety of antioxidant defenses. It is likely, therefore, that a combination of antioxidants may be effective in the treatment of asthma and COPD. Various approaches to enhance the lung antioxidant screen and clinical trials of antioxidant compounds are discussed. [Copyright &y& Elsevier]

Oxidative stress is the hallmark of various chronic inflammatory lung diseases. Increased concentrations of reactive oxygen species (ROS) in the lungs of such patients are reflected by elevated concentrations of oxidative stress markers in the breath, airways, lung tissue and blood. Traditionally, the measurement of these biomarkers has involved invasive procedures to procure the samples or to examine the affected compartments, to the patient's discomfort. As a consequence, there is a need for less or non-invasive approaches to measure oxidative stress. The collection of exhaled breath condensate (EBC) has recently emerged as a non-invasive sampling method for real-time analysis and evaluation of oxidative stress biomarkers in the lower respiratory tract airways. The biomarkers of oxidative stress such as H2O2, F2-isoprostanes, malondialdehyde, 4-hydroxy-2-nonenal, antioxidants, glutathione and nitrosative stress such as nitrate/nitrite and nitrosated species have been successfully measured in EBC. The reproducibility, sensitivity and specificity of the methodologies used in the measurements of EBC oxidative stress biomarkers are discussed. Oxidative stress biomarkers also have been measured for various antioxidants in disease prognosis. EBC is currently used as a research and diagnostic tool in free radical research, yielding information on redox disturbance and the degree and type of inflammation in the lung. It is expected that EBC can be exploited to detect specific levels of biomarkers and monitor disease severity in response to appropriate prescribed therapy/treatment. [ABSTRACT FROM AUTHOR]

Recently, there has been an outbreak of a condition named e-cigarette or vaping products-associated lung injury (EVALI). The primary components of vaping products include tetrahydrocannabinol (THC), vitamin E acetate (VEA) and medium-chain triglycerides (MCT), may be responsible for acute lung toxicity. Currently, little information is available on the physiological and biological effects of exposure to these products. We hypothesized that these CBD/counterfeit vape cartridges and their constituents (VEA and MCT) induce pulmonary toxicity, mediated by oxidative damage and inflammatory responses, leading to acute lung injury. We studied the potential mechanisms of CBD/counterfeit vape cartridge aerosol induced inflammatory response by evaluating the generation of reactive oxygen species by MCT, VEA, and cartridges and their effects on the inflammatory state of pulmonary epithelium and immune cells both in vitro and in vivo. Cells exposed to these aerosols generated reactive oxygen species, caused cytotoxicity, induced epithelial barrier dysfunction, and elicited an inflammatory response. Using a murine model, the parameters of acute toxicity to aerosol inhalation were assessed. Infiltration of neutrophils and lymphocytes was accompanied by significant increases in IL-6, eotaxin, and G-CSF in the bronchoalveolar lavage fluid (BALF). In mouse BALF, eicosanoid inflammatory mediators, leukotrienes, were significantly increased. Plasma from e-cig users also showed increased levels of hydroxyeicosatetraenoic acid (HETEs) and various eicosanoids. Exposure to CBD/counterfeit vape cartridge aerosols showed the most significant effects and toxicity compared to MCT and VEA. In addition, we determined SARS-CoV-2 related proteins and found no impact associated with aerosol exposures from these tested cartridges. Overall, this study demonstrates acute exposure to specific CBD/counterfeit vape cartridges induces in vitro cytotoxicity, barrier dysfunction, and inflammation and in vivo mouse exposure induces acute inflammation with elevated proinflammatory markers in the pathogenesis of EVALI. [ABSTRACT FROM AUTHOR]

Daily oscillations of pulmonary function depend on the rhythmic activity of the circadian timing system. Environmental tobacco/cigarette smoke (CS) disrupts circadian clock leading to enhanced inflammatory responses. Infection with influenza A virus (IAV) increases hospitalization rates and death in susceptible individuals, including patients with Chronic Obstructive Pulmonary Disease (COPD). We hypothesized that molecular clock disruption is enhanced by IAV infection, altering cellular and lung function, leading to severity in airway disease phenotypes. C57BL/6J mice exposed to chronic CS, BMAL1 knockout (KO) mice and wild-type littermates were infected with IAV. Following infection, we measured diurnal rhythms of clock gene expression in the lung, locomotor activity, pulmonary function, inflammatory, pro-fibrotic and emphysematous responses. Chronic CS exposure combined with IAV infection altered the timing of clock gene expression and reduced locomotor activity in parallel with increased lung inflammation, disrupted rhythms of pulmonary function, and emphysema. BMAL1 KO mice infected with IAV showed pronounced detriments in behavior and survival, and increased lung inflammatory and pro-fibrotic responses. This suggests that remodeling of lung clock function following IAV infection alters clock-dependent gene expression and normal rhythms of lung function, enhanced emphysematous and injurious responses. This may have implications for the pathobiology of respiratory virus-induced airway disease severity and exacerbations. [ABSTRACT FROM AUTHOR]