Effects of cigarette smoke condensate on proliferation and wound closure of bronchial epithelial cells in vitro: role of glutathione

Release of IL-1β and IL-18 in human primary bronchial epithelial cells exposed to cigarette smoke is independent of NLRP3

Cigarette smoke (CS) is a major risk factor for chronic lung diseases and promotes activation of pattern recognition receptors in the bronchial epithelium. NOD-like receptor family, pyrin domain-containing 3 (NLRP3) is a pattern recognition receptor whose activation leads to caspase-1 cleavage, maturation/release of IL-1β and IL-18, and eventually pyroptosis. Whether the NLRP3 inflammasome participates in CS-induced inflammation in bronchial epithelial cells is still unclear. Herein, we evaluated the involvement of NLRP3 in CS-induced inflammatory responses in human primary bronchial epithelial cells. To this purpose, human primary bronchial epithelial cells were stimulated with CS extracts (CSE) and lytic cell death, caspase activation (-1, -8, -3/7), cytokine release (IL-1β, IL-18, and IL-8), NLRP3, pro-IL-1β/pro-IL-18 mRNA, and protein expression were measured. The impact of inhibitors of NLRP3 (MCC950), caspases, and the effect of the antioxidant N-acetyl cysteine were evaluated. We found that CSE increased pro-IL-1β expression and induced activation of caspase-1 and release of IL-1β and IL-18. These events were independent of NLRP3 and we found that NLRP3 was not expressed. N-acetyl cysteine reverted CSE-induced caspase-1 activation. Overall, our findings support that the bronchial epithelium may play a central role in the release of IL-1 family cytokines independently of NLRP3 in the lungs of smokers.

Formoterol Exerts Anti-Cancer Effects Modulating Oxidative Stress and Epithelial-Mesenchymal Transition Processes in Cigarette Smoke Extract Exposed Lung Adenocarcinoma Cells

Lung cancer frequently affects patients with Chronic Obstructive Pulmonary Disease (COPD). Cigarette smoke (CS) fosters cancer progression by increasing oxidative stress and by modulating epithelial-mesenchymal transition (EMT) processes in cancer cells. Formoterol (FO), a long-acting β2-agonist widely used for the treatment of COPD, exerts antioxidant activities. This study explored in a lung adenocarcinoma cell line (A549) whether FO counteracted the effects of cigarette smoke extract (CSE) relative to oxidative stress, inflammation, EMT processes, and cell migration and proliferation. A549 was stimulated with CSE and FO, ROS were evaluated by flow-cytometry and by nanostructured electrochemical sensor, EMT markers were evaluated by flow-cytometry and Real-Time PCR, IL-8 was evaluated by ELISA, cell migration was assessed by scratch and phalloidin test, and cell proliferation was assessed by clonogenic assay. CSE significantly increased the production of ROS, IL-8 release, cell migration and proliferation, and SNAIL1 expression but significantly decreased E-cadherin expression. FO reverted all these phenomena in CSE-stimulated A549 cells. The present study provides intriguing evidence that FO may exert anti-cancer effects by reverting oxidative stress, inflammation, and EMT markers induced by CS. These findings must be validated in future clinical studies to support FO as a valuable add-on treatment for lung cancer management.

Cigarette smoke restricts the ability of mesenchymal cells to support lung epithelial organoid formation

Adequate lung epithelial repair relies on supportive interactions within the epithelial niche, including interactions with WNT-responsive fibroblasts. In fibroblasts from patients with chronic obstructive pulmonary disease (COPD) or upon in vitro cigarette smoke exposure, Wnt/β-catenin signalling is distorted, which may affect interactions between epithelial cells and fibroblasts resulting in inadequate lung repair. We hypothesized that cigarette smoke (CS), the main risk factor for COPD, interferes with Wnt/β-catenin signalling in fibroblasts through induction of cellular stress responses, including oxidative- and endoplasmic reticulum (ER) stress, and thereby alters epithelial repair support potential. Therefore, we assessed the effect of CS-exposure and the ER stress inducer Thapsigargin (Tg) on Wnt/β-catenin signalling activation in MRC-5 fibroblasts, and on their ability to support lung epithelial organoid formation. Exposure of MRC-5 cells for 15 min with 5 AU/mL CS extract (CSE), and subsequent 6 h incubation induced oxidative stress (HMOX1). Whereas stimulation with 100 nM Tg increased markers of both the integrated stress response (ISR - GADD34/PPP1R15A, CHOP) and the unfolded protein response (UPR - XBP1spl, GADD34/PPP1R15A, CHOP and HSPA5/BIP), CSE only induced GADD34/PPP1R15A expression. Strikingly, although treatment of MRC-5 cells with the Wnt activator CHIR99021 upregulated the Wnt/β-catenin target gene AXIN2, this response was diminished upon CSE or Tg pre-exposure, which was confirmed using a Wnt-reporter. Furthermore, pre-exposure of MRC-5 cells to CSE or Tg, restricted their ability to support organoid formation upon co-culture with murine pulmonary EpCam+ cells in Matrigel at day 14. This restriction was alleviated by pre-treatment with CHIR99021. We conclude that exposure of MRC-5 cells to CSE increases oxidative stress, GADD34/PPP1R15A expression and impairs their ability to support organoid formation. This inhibitory effect may be restored by activating the Wnt/β-catenin signalling pathway.

Cigarette Smoke-Induced Reactive Oxygen Species Formation: A Concise Review

Smoking is recognized as a significant risk factor for numerous disorders, including cardiovascular diseases, respiratory conditions, and various forms of cancer. While the exact pathogenic mechanisms continue to be explored, the induction of oxidative stress via the production of excess reactive oxygen species (ROS) is widely accepted as a primary molecular event that predisposes individuals to these smoking-related ailments. This review focused on how cigarette smoke (CS) promotes ROS formation rather than the pathophysiological repercussions of ROS and oxidative stress. A comprehensive analysis of existing studies revealed the following key ways through which CS imposes ROS burden on biological systems: (1) ROS, as well as radicals, are intrinsically present in CS, (2) CS constituents generate ROS through chemical reactions with biomolecules, (3) CS stimulates cellular ROS sources to enhance production, and (4) CS disrupts the antioxidant system, aggravating the ROS generation and its functions. While the evidence supporting these mechanisms is chiefly based on in vitro and animal studies, the direct clinical relevance remains to be fully elucidated. Nevertheless, this understanding is fundamental for deciphering molecular events leading to oxidative stress and for developing intervention strategies to counter CS-induced oxidative stress.

Cigarette Smoke Impairs Airway Epithelial Wound Repair: Role of Modulation of Epithelial-Mesenchymal Transition Processes and Notch-1 Signaling

Cigarette smoke (CS) induces oxidative stress and chronic inflammation in airway epithelium. It is a major risk factor for respiratory diseases, characterized by epithelial injury. The impact of CS on airway epithelial repair, which involves epithelial-mesenchymal transition (EMT) and the Notch-1 pathway, is incompletely understood. In this study, we used primary bronchial epithelial cells (PBECs) to evaluate the effect of CS on epithelial repair and these mechanisms. The effect of CS and/or TGF-beta1 on wound repair, various EMT and Notch-1 pathway markers and epithelial cell markers (TP63, SCGB1A) was assessed in PBECs cultured submerged, at the air–liquid interface (ALI) alone and in co-culture with fibroblasts. TGF-beta1 increased epithelial wound repair, activated EMT (shown by decrease in E-cadherin, and increases in vimentin, SNAIL1/SNAIL2/ZEB1), and increased Notch-1 pathway markers (NOTCH1/JAGGED1/HES1), MMP9, TP63, SCGB1A1. In contrast, CS decreased wound repair and vimentin, NOTCH1/JAGGED1/HES1, MMP9, TP63, SCGB1A1, whereas it activated the initial steps of the EMT (decrease in E-cadherin and increases in SNAIL1/SNAIL2/ZEB1). Using combined exposures, we observed that CS counteracted the effects of TGF-beta1. Furthermore, Notch signaling inhibition decreased wound repair. These data suggest that CS inhibits the physiological epithelial wound repair by interfering with the normal EMT process and the Notch-1 pathway.

Dysregulated mitochondrial metabolism upon cigarette smoke exposure in various human bronchial epithelial cell models

Exposure to cigarette smoke (CS) is the primary risk factor for developing chronic obstructive pulmonary disease. The impact of CS exposure on the molecular mechanisms involved in mitochondrial quality control in airway epithelial cells is incompletely understood. Undifferentiated or differentiated primary bronchial epithelial cells were acutely/chronically exposed to whole CS (WCS) or CS extract (CSE) in submerged or air-liquid interface conditions. Abundance of key regulators controlling mitochondrial biogenesis, mitophagy and mitochondrial dynamics was assessed. Acute exposure to WCS or CSE increased the abundance of components of autophagy and receptor-mediated mitophagy in all models. Although mitochondrial content and dynamics appeared to be unaltered in response to CS, changes in both the molecular control of mitochondrial biogenesis and a shift toward an increased glycolytic metabolism were observed in particular in differentiated cultures. These alterations persisted, at least in part, after chronic exposure to WCS during differentiation and upon subsequent discontinuation of WCS exposure. In conclusion, smoke exposure alters the regulation of mitochondrial metabolism in airway epithelial cells, but observed alterations may differ between various culture models used. This article has an associated First Person interview with the joint first authors of the paper.

Method of Preparation of Cigarette Smoke Extract to Assess Lung Cancer-Associated Changes in Airway Epithelial Cells

Smoking tobacco is a major risk factor for the development of lung cancer, COPD, and other lung pathologies in smokers. Cigarette smoke (CS), which is comprised of several toxic components, is known to cause oxidative stress and inflammation-induced lung damage. Since airway epithelial cells act as the primary barrier, they protect the lung tissues from environmental insults, including CS. Upon exposure to these insults, airway epithelial cells act as the initial site of injury and orchestrate the pathophysiology of lung cancer. Scientists have been using cigarette smoke extract (CSE) in the preclinical model of in vitro cell culture to understand the effect of CS on the cellular, biochemical, and molecular changes in the lung epithelial cells. However, the standard procedure to prepare the CSE in the laboratory with a low-cost assembly and obtaining a reproducible quality of CSE in different batches is a challenge. Here, in this chapter, we delineate the method for the preparation of CSE using a discontinuous puff-based system which is an economical and reproducible method to prepare CSE in the laboratory. This method is suitable for studying CSE-induced molecular changes in lung diseases, including lung cancer, using in vitro models of lung adenocarcinoma cells.

Airway epithelial dysfunction and mesenchymal transition in chronic obstructive pulmonary disease: Role of Oct-4

The airway epithelium is a dynamic tissue that undergoes slow but constant renewal. Dysregulation of airway epithelial function related to cigarette smoke exposure plays an important role in the pathophysiology of COPD. Oct4 is a transcription factor responsible for maintaining cellular self-renewal and regeneration, and CD146 and CD105/Endoglin are adhesion molecules involved in cell proliferation, differentiation, epithelial-mesenchymal-transition and tissue remodeling. Bronchial biopsy specimens (BBs) were obtained from 7 healthy controls (HC) and 10 COPD and subjected to paraffin embedding; BBs from HC were also used for epithelial cell expansion and pHBEC/ALI (air-liquid interface) culture. pHBEC/ALI were exposed to cigarette smoke extract (CSE) for 7, 14 and 21 days. In BBs, Oct4, CD146 and CD105 were evaluated by immunohistochemistry. In pHBEC/ALI, the expression of Oct4, CD146, CD105 and acetyl-αtubulin was evaluated by Western Blot, MUC5AC and IL-8 measurements by ELISA. The Oct4 epithelial immunoreactivity was lower in COPD than in HC, whilst CD146 and CD105 expression was higher in COPD than in HC. In pHBEC/ALI, Transepithelial Electrical Resistance values, measured over 7 to 21 days of differentiation, decreased by 18% (2.5% CSE) and 29% (5% CSE) compared to untreated samples. Oct4 and acetyl-αtubulin were induced after one-week differentiation and downregulated by CSE in reconstituted epithelium; CD146, CD105, MUC5AC and IL-8 were increased by CSE. Oct4 de-regulation and CD146 and CD105 overexpression, induced by cigarette smoke exposure, might play a role in airway epithelial dysfunction by causing changes in self-renewal and mesenchymal transition mechanisms, leading to alteration of epithelium homeostasis and abnormal tissue remodeling involved in progression of COPD.

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

Chronic obstructive pulmonary disease (COPD) is a complex chronic respiratory disorder often caused by cigarette smoke. Cigarette smoke contains hundreds of toxic substances. In our study, we wanted to identify initial mechanisms of cigarette smoke induced changes in the distal lung. Viable slices of human lungs were exposed 24 h to cigarette smoke condensate, and the dose–response profile was analyzed. Non-toxic condensate concentrations and lipopolysaccharide were used for further experiments. COPD-related protein and gene expression was measured. Cigarette smoke condensate did not induce pro-inflammatory cytokines and most inflammation-associated genes. In contrast, lipopolysaccharide significantly induced IL-1α, IL-1β, TNF-α and IL-8 (proteins) and IL1B, IL6, and TNF (genes). Interestingly, cigarette smoke condensate induced metabolism- and extracellular matrix–associated proteins and genes, which were not influenced by lipopolysaccharide. Also, a significant regulation of CYP1A1 and CYP1B1, as well as MMP9 and MMP9/TIMP1 ratio, was observed which resembles typical findings in COPD. In conclusion, our data show that cigarette smoke and lipopolysaccharide induce significant responses in human lung tissue ex vivo, giving first hints that COPD starts early in smoking history.

Wood Smoke Extract Promotes Extracellular Matrix Remodeling in Normal Human Lung Fibroblasts

Wood smoke (WS) contains many harmful compounds, including polycyclic aromatic hydrocarbons (PAHs). WS induces inflammation in the airways and lungs and can lead to the development of various acute and chronic respiratory diseases. Pulmonary fibroblasts are the main cells involved in the remodeling of the extracellular matrix (ECM) during the WS-induced inflammatory response. Although fibroblasts remain in a low proliferation state under physiological conditions, they actively participate in ECM remodeling during the inflammatory response in pathophysiological states. Consequently, we used normal human lung fibroblasts (NHLFs) to assess the potential effects of the PAHs-containing wood smoke extract (WSE) on the growth rate, total collagen synthesis, and the expression levels of collagen I and III, matrix metalloproteinase (MMP)-1, MMP-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2, and the transforming growth factor (TGF)-β1. We also assessed MMPs activity. The results showed that WSE induced a trimodal behavior in the growth rate curves in NHLFs; the growth rate increased with 0.5-1 % WSE and decreased with 2.5% WSE, without causing cell damage; 5-20% WSE inhibited the growth and induced cell damage. After 3 hours of exposure, 2.5% WSE induced an increase in total collagen synthesis and upregulation of TGF-β1, collagen I and III, MMP-1, TIMP-1, and TIMP-2 expression. However, MMP-2 expression was downregulated and MMP-9 was not expressed. The gelatinase activity of MMP-2 was also increased. These results suggest that WSE affects the ECM remodeling in NHLFs and indicate the potential involvement of PAHs in this process.

GYY4137 protected the integrity of the blood-brain barrier via activation of the Nrf2/ARE pathway in mice with sepsis

Injury to the blood-brain barrier (BBB) plays a vital role in sepsis-associated encephalopathy (SAE), which is one of the most common complications of sepsis. GYY4137, a new synthetic compound of hydrogen sulfide (H₂ S), has extensive biological benefits. In this study, we focused on the protective effects of GYY4137 on the BBB in septic mice and the underlying mechanisms. The results suggested that whether administrated at the same time or 3 hours after LPS injection, GYY4137 both significantly alleviated the clinical symptoms and the long-term prognosis. Besides, GYY4137 improved the pathological abnormalities of septic mice. Moreover, the degradation of tight junctions in the BBB was considerably inhibited by GYY4137. In addition, GYY4137 significantly attenuated inflammation and apoptosis in the brain. Furthermore, GYY4137 activated the Nrf2/ARE pathway through the sulfhydrylation of Keap1 and inhibited oxidative stress. ML385, the specific inhibitor of Nrf2, significantly reversed the protective effects of GYY4137 in sepsis mice. In conclusion, this study indicated that through the sulfhydrylation of Keap1, GYY4137 activated the Nrf2/ARE pathway and exerted anti-inflammatory, anti-apoptotic and antioxidant effects in septic mice that consequently protected the integrity of the BBB and improved the clinical outcome of sepsis. Our findings suggest that GYY4137 might be a promising agent for the treatment of SAE.

Involvement of TRPC1 and Cyclin D1 in Human Pulmonary Artery Smooth Muscle Cells Proliferation Induced by Cigarette Smoke Extract

Cigarette smoking contributes to the development of pulmonary artery hypertension (PAH). As the basic pathological change of PAH, pulmonary vascular remodeling is considered to be related to the abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs). However, the molecular mechanism underlying this process remains not exactly clear. The aim of this research was to study the molecular mechanism of PASMCs proliferation induced by smoking. Human PASMCs (HPASMCs) were divided into 6 groups: 0% (control group), cigarette smoking extract (CSE)-treated groups at concentrations of 0.5%, 1%, 2%, 5%, 10% CSE respectively. HPASMCs proliferation was observed after 24 h. HPASMCs were divided into two groups: 0 (control group), 0.5% CSE group. The mRNA and protein expression levels of transient receptor potential channel 1 (TRPC1) and cyclin D1 in HPASMCs after CSE treatment were respectively detected by RT-PCR and Western blotting. The intracellular calcium ion concentration was measured by the calcium probe in each group. In the negative control group and TRPC1-siRNA transfection group, the proliferation of HPASMCs and the expression of cyclin D1 mRNA and protein were detected. Data were compared with one-way ANOVA (for multiple-group comparison) and independent t-test (for two-group comparison) followed by the least significant difference (LSD) test with the computer software SPSS 17.0. It was found that 0.5% and 1% CSE could promote the proliferation of HPASMCs (P<0.05), and the former was more effective than the latter (P<0.05), while 3% and above CSE had inhibitory effect on HPASMCs (P<0.05). The mRNA and protein expression levels of TRPC1 and cyclin D1 in 0.5% and 1% CSE groups were significantly higher than those in the control group (P<0.05), while those in 3% CSE group were significantly decreased (P<0.05). Moreover, the proliferation of HPASMCs and the expression of cyclin D1 mRNA and protein in TRPC1-siRNA transfection group were significantly reduced as compared with those in the negative control group (P<0.05). It was concluded that low concentration of CSE can promote the proliferation of HPASMCs, while high concentrations of CSE inhibit HPASMCs proliferation. These findings suggested that CSE induced proliferation of HPASMCs at least in part via TRPC1-mediated cyclin D1 expression.

Zingerone [4-(3-Methoxy-4-hydroxyphenyl)-butan-2] Attenuates Lipopolysaccharide-Induced Inflammation and Protects Rats from Sepsis Associated Multi Organ Damage

The present investigation aimed to evaluate the protective effect of Zingerone (ZIN) against lipopolysaccharide-induced oxidative stress, DNA damage, and cytokine storm in rats. For survival study the rats were divided into four groups (n = 10). The control group was treated with normal saline; Group II received an intraperitoneal (i.p) injection (10 mg/kg) of LPS as disease control. Rats in Group III were treated with ZIN 150 mg/kg (p.o) 2 h before LPS challenge and rats in Group IV were given ZIN only. Survival of the rats was monitored up to 96 h post LPS treatment. In another set, the animals were divided into four groups of six rats. Animals in Group I served as normal control and were treated with normal saline. Animals in Group II were treated with lipopolysaccharide (LPS) and served as disease control. Group III animals were treated with ZIN 2 h before LPS challenge. Group IV served as positive control and were treated with ZIN (150 mg/kg orally). The blood samples were collected and used for the analysis of biochemical parameters like alanine transaminase (ALT), alkaline phosphatase (ALP), aspartate transaminase (AST), blood urea nitrogen (BUN), Cr, Urea, lactate dehydrogenase (LDH), albumin, bilirubin (BIL), and total protein. Oxidative stress markers malondialdehyde (MDA), glutathione peroxidase (GSH), myeloperoxidase (MPO), and (DNA damage marker) 8-OHdG levels were measured in different organs. Level of nitric oxide (NO) and inflammatory markers like TNF-α, IL-1ß, IL-1α, IL-2, IL-6, and IL-10 were also quantified in plasma. Procalcitonin (PCT), a sepsis biomarker, was also measured. ZIN treatment had shown significant (p < 0.5) restoration of plasma enzymes, antioxidant markers and attenuated plasma proinflammatory cytokines and sepsis biomarker (PCT), thereby preventing the multi-organ and tissue damage in LPS-induced rats also confirmed by histopathological studies of different organs. The protective effect of ZIN may be due to its potent antioxidant potential. Thus ZIN can prevent LPS-induced oxidative stress as well as inflammatory and multi-organ damage in rats when administered to the LPS treated animals.

Airborne PAHs inhibit gap junctional intercellular communication and activate MAPKs in human bronchial epithelial cell line

Inhalation exposures to polycyclic aromatic hydrocarbons (PAHs) have been associated with various adverse health effects, including chronic lung diseases and cancer. Using human bronchial epithelial cell line HBE1, we investigated the effects of structurally different PAHs on tissue homeostatic processes, namely gap junctional intercellular communication (GJIC) and MAPKs activity. Rapid (<1 h) and sustained (up to 24 h) inhibition of GJIC was induced by low/middle molecular weight (MW) PAHs, particularly by those with a bay- or bay-like region (1- and 9-methylanthracene, fluoranthene), but also by fluorene and pyrene. In contrast, linear low MW (anthracene, 2-methylanthracene) or higher MW (chrysene) PAHs did not affect GJIC. Fluoranthene, 1- and 9-methylanthracene induced strong and sustained activation of MAPK ERK1/2, whereas MAPK p38 was activated rather nonspecifically by all tested PAHs. Low/middle MW PAHs can disrupt tissue homeostasis in human airway epithelium via structure-dependent nongenotoxic mechanisms, which can contribute to their human health hazards.

Modulation of Airway Epithelial Innate Immunity and Wound Repair by M(GM-CSF) and M(M-CSF) Macrophages

Airway epithelial cells and macrophages participate in inflammatory responses to external noxious stimuli, which can cause epithelial injury. Upon injury, epithelial cells and macrophages act in concert to ensure rapid restoration of epithelial integrity. The nature of the interactions between these cell types during epithelial repair is incompletely understood. We used an in vitro human coculture model of primary bronchial epithelial cells cultured at the air-liquid interface (ALI-PBEC) and polarized primary monocyte-derived macrophages. Using this coculture, we studied the contribution of macrophages to epithelial innate immunity, wound healing capacity, and epithelial exposure to whole cigarette smoke (WCS). Coculture of ALI-PBEC with lipopolysaccharide (LPS)-activated M(GM-CSF) macrophages increased the expression of DEFB4A, CXCL8, and IL6 at 24 h in the ALI-PBEC, whereas LPS-activated M(M-CSF) macrophages only increased epithelial IL6 expression. Furthermore, wound repair was accelerated by coculture with both activated M(GM-CSF) and M(M-CSF) macrophages, also following WCS exposure. Coculture of ALI-PBEC and M(GM-CSF) macrophages resulted in increased CAMP expression in M(GM-CSF) macrophages, which was absent in M(M-CSF) macrophages. CAMP encodes LL-37, an antimicrobial peptide with immune-modulating and repair-enhancing activities. In conclusion, dynamic crosstalk between ALI-PBEC and macrophages enhances epithelial innate immunity and wound repair, even upon concomitant cigarette smoke exposure.

Identification of apoptosis-associated protein factors distinctly expressed in cigarette smoke condensate-exposed airway bronchial epithelial cells

Smoking is associated with an increased risk of respiratory diseases, including lung cancer and asthma. However, the mechanisms or diagnostic markers for smoking-related diseases remain largely unknown. Here we investigated the role of cigarette smoke condensate (CSC) in the regulation of human bronchial epithelial cell (BEAS-2B) behavior. We found that exposure to CSC significantly inhibited BEAS-2B cell viability, impaired cell morphology, induced cell apoptosis, triggered oxidative damage, and promoted inflammatory response, which suggests a deleterious effect of CSC on bronchial epithelial cells. In addition, CSC markedly altered the expression of apoptosis-associated protein factors, including p21, soluble tumor necrosis factor receptor 1, and Fas ligand. In sum, our study identified a panel of novel protein factors that may mediate the actions of CSC on bronchial epithelial cells and have a predictive value for the development and progression of smoking-related diseases, thus providing insights into the development of potential diagnostic and therapeutic strategies against these diseases.

Cigarette Smoke Condensate Exposure Changes RNA Content of Extracellular Vesicles Released from Small Airway Epithelial Cells

Exposure to environmental tobacco smoke (ETS) is a known risk factor for the development of chronic lung diseases, cancer, and the exacerbation of viral infections. Extracellular vesicles (EVs) have been identified as novel mediators of cell–cell communication through the release of biological content. Few studies have investigated the composition/function of EVs derived from human airway epithelial cells (AECs) exposed to cigarette smoke condensate (CSC), as surrogates for ETS. Using novel high-throughput technologies, we identified a diverse range of small noncoding RNAs (sncRNAs), including microRNA (miRNAs), Piwi-interacting RNA (piRNAs), and transfer RNA (tRNAs) in EVs from control and CSC-treated SAE cells. CSC treatment resulted in significant changes in the EV content of miRNAs. A total of 289 miRNAs were identified, with five being significantly upregulated and three downregulated in CSC EVs. A total of 62 piRNAs were also detected in our EV preparations, with five significantly downregulated and two upregulated in CSC EVs. We used TargetScan and Gene Ontology (GO) analysis to predict the biological targets of hsa-miR-3913-5p, the most represented miRNA in CSC EVs. Understanding fingerprint molecules in EVs will increase our knowledge of the relationship between ETS exposure and lung disease, and might identify potential molecular targets for future treatments.

Apoptotic effects of cigarette smoke extracts on mouse embryonic stem cells via oxidative stress

Previous studies have reported that cigarette smoke and cigarette smoke extract (CSE) have negative effects on embryonic development. However, no studies have investigated the mechanism through which CSE affects the cellular signaling pathway leading to apoptosis and oxidative stress in embryonic cells, or how the two pathways are cross-linked. Thus, we studied the effects of CSE on apoptosis and oxidative stress in mouse embryonic stem cells (mESCs). Specifically, we measured changes in cell viability in response to CSEs (3R4F and two domestic cigarettes CSE 1 and 2) using a water soluble tetrazolium (WST) assay and a neutral red uptake (NRU) assay, which revealed that cell viability decreased in a concentration-dependent manner. Western blot analysis revealed that the expression of cyclin D1 and cyclin E1 was decreased and that of p21 and p27 was increased by CSE. Additionally, the number of terminal deoxynucleotidyl transferase (TUNEL)-stained cells was increased by CSE, while the levels of Bax and Caspase-3 increased and Bcl-2 decreased. Moreover, a 2',7'-dichlorofluorescin diacetate (DCF-DA) assay and reactive oxygen species (ROS)-Glo H2 O2 assay confirmed that ROS were generated in response to CSE and that they were associated with up-regulated Keaf-1 and CHOP. Overall, the results revealed that cigarette smoke extract (CSE) inhibited cell proliferation by regulating cell cycle-related protein expression and increased oxidative stress by regulating the expression of Kelch-like ECH-associated protein 1 (Keap-1) and CCAAT/enhancer-binding protein homologous protein (CHOP), resulting in apoptosis in mESCs.

Budesonide, Aclidinium and Formoterol in combination limit inflammaging processes in bronchial epithelial cells exposed to cigarette smoke

Inflammation and cellular senescence (also called inflammaging) are involved in the pathogenesis of premature lung aging, a key driver of chronic obstructive pulmonary disease (COPD). Downregulation of histone deacetylases and FoxO3 expression, activation of the ERK 1/2 pathway and IL-8 increase are hallmarks of lung inflammaging. The effects of Budesonide (BUD), Aclidinium (ACL) and Formoterol (FO) on lung inflammaging are unknown. This study was aimed to assess the effects of BUD, ACL and FO in bronchial epithelial cells exposed to cigarette smoke extract (CSE) by evaluating: a) Expression of TLR4 and survivin and LPS binding by flow cytometry; b) expression of HDAC2, HDAC3, SIRT1 and FoxO3 and activation of the ERK 1/2 pathway by western blot; c) IL-8 mRNA levels and release by Real Time-PCR and ELISA, respectively. Reported results show that CSE increased TLR4 and survivin, LPS binding, ERK 1/2 activation, IL-8 release and mRNA levels but decreased SIRT1, HDAC2, HDAC3 and FoxO3 nuclear expression. Combined therapy with BUD, ACL and FO counteracted the effects of CSE on LPS binding, FoxO3 nuclear expression, ERK 1/2 activation, survivin and IL-8 release and mRNA levels. These findings suggest a new role of combination therapy with BUD, ACL and FO in counteracting inflammaging processes induced by cigarette smoke exposure.

Differential expression of heat shock proteins and activation of mitogen-activated protein kinases in A549 alveolar epithelial cells exposed to cigarette smoke extract

NEW FINDINGS

What is the central question of this study? What is the effect of cigarette smoke on cell death, oxidative damage, expression of heat shock proteins (HSPs) and activation of mitogen-activated protein kinases (MAPKs) in A549 alveolar epithelial cells? What is the main finding and its importance? Cigarette smoke induces cytotoxicity and oxidative damage to A549 cells, increases expression of different HSPs and activates MAPK signalling pathways. This could be related to inflammatory response and apoptosis observed in lungs of patients with smoking-related diseases.

ABSTRACT

Cigarette smoking is one of the main risk factors for development of chronic obstructive pulmonary disease (COPD). We previously reported that cigarette smoke (CS) induces damage to proteins and their ineffective degradation. Here, we hypothesize that CS could induce oxidative stress and cytotoxicity in lung epithelial cells through alterations of heat shock protein (HSP) expression and mitogen-activated protein kinase (MAPK) signalling pathways. We exposed A549 alveolar epithelial cells to various concentrations of cigarette smoke extract (CSE). Higher concentrations of CSE caused apoptosis of A549 cells after 4 h, while after 24 h cell viability was decreased, and lactate dehydrogenase in cell culture medium was increased as well as the number of necrotic cells. Concentrations of malondialdehyde (MDA) were elevated, while total thiol groups were decreased. Changes in the expression of HSPs (HSP70, HSP32 and HSP27) were time-dependent. After 6 h, CSE caused an increase in the expression of HSP70 and HSP32, while after 8 h all examined HSPs were up-regulated and remained increased up to 48 h. Treatment of A549 cells with CSE stimulated phosphorylation of extracellular signal-regulated kinase and p38 in a dose-dependent manner, while c-Jun N-terminal kinase activation was not detected. By using specific inhibitors, we demonstrated that MAPKs and HSPs interplay in CSE effects. In conclusion, our results show that MAPKs and HSPs are involved in the mechanism underlying CSE-induced cytotoxicity and oxidative damage to A549 alveolar epithelial cells. These processes could be related to inflammatory response and apoptosis observed in lungs of patients with smoking-related diseases, such as COPD.

Extracellular Hsp70 modulates the inflammatory response of cigarette smoke extract in NCI-H292 cells

NEW FINDINGS

What is the central question of this study? Does extracellular heat shock protein 70 (eHsp70) alter cigarette smoke extract (CSE)-induced inflammatory responses in NCI-H292 bronchial epithelial cells? What is the main finding and its importance? eHsp70 modulates inflammatory responses and TLR2, TLR4 and Hsp70 gene expression, and protects NCI-H292 cells against CSE-induced cytotoxicity. eHsp70 might be implicated in development of inflammatory diseases affected by cigarette smoke, such as COPD.

ABSTRACT

One of the major risk factors for development of chronic obstructive pulmonary disease (COPD) is cigarette smoke. Extracellular Hsp70 (eHsp70) is increased in sera of COPD patients, and can act as damage-associated molecular pattern (DAMP). In this study, we explored inflammatory parameters (cytokine concentrations, Toll-like receptor (TLR) 2 and 4 and Hsp70 expression, mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB) activation, and cytotoxicity) after exposure of bronchial-epithelial NCI-H292 cells to cigarette smoke extract (CSE) alone (2.5 and 15%) and in combinations with recombinant human (rh) Hsp70 (0.3, 1 and 3 μg ml^-1 ). We applied specific MAPKs, NF-κB and Hsp70 inhibitors to elucidate rhHsp70 inflammation-associated responses. CSE alone and combinations of 15% CSE with rhHsp70 stimulated IL-1α, IL-6 and IL-8 release. However, rhHsp70 applied with 2.5% CSE decreased secretion of cytokines indicating antagonistic effects. Individual and combined treatments with 2.5% CSE suppressed TLR2 expression. CSE at 15% induced TLR2 and TLR4 gene expression, whereas rhHsp70 abolished that effect. rhHsp70 and 15% CSE alone reduced, while their combination increased, intracellular Hsp70 mRNA level. CSE alone and in combination with rhHsp70 activated extracellular signal-regulated kinase and p38 MAPKs, while inhibition of MAPKs, NF-κB and Hsp70 attenuated IL-6 and IL-8 secretion. CSE at 15% reduced cell viability and induced apoptosis, as shown by MTS and caspases-3/7 assays. CSE at 2.5% alone stimulated lactate dehydrogenase release, but cellular membrane integrity remained intact in co-treatments with rhHsp70. rhHsp70 might modulate the inflammatory response of CSE and could also protect NCI-H292 cells against CSE cytotoxicity. Those effects are implemented via MAPK and NF-κB signalling pathways.

Long-Term Cigarette Smoke Exposure and Changes in MiRNA Expression and Proteome in Non-Small-Cell Lung Cancer

Chronic exposure to cigarette smoke markedly increases the risk for lung cancer. Regulation of gene expression at the post-transcriptional level by miRNAs influences a variety of cancer-related interactomes. Yet, relatively little is known on the effects of long-term cigarette smoke exposure on miRNA expression and gene regulation. NCI-H292 (H292) is a cell line sensitive to cigarette smoke with mucoepidermoid characteristics in culture. We report, in this study, original observations on long-term (12 months) cigarette smoke effects in the H292 cell line, using microarray-based miRNA expression profiling, and stable isotopic labeling with amino acids in cell culture-based quantitative proteomic analysis. We identified 112 upregulated and 147 downregulated miRNAs (by twofold) in cigarette smoke-treated H292 cells. The liquid chromatography-tandem mass spectrometry analysis identified 3,959 proteins, of which, 303 proteins were overexpressed and 112 proteins downregulated (by twofold). We observed 39 miRNA target pairs (proven targets) that were differentially expressed in response to chronic cigarette smoke exposure. Gene ontology analysis of the target proteins revealed enrichment of proteins in biological processes driving metabolism, cell communication, and nucleic acid metabolism. Pathway analysis revealed the enrichment of phagosome maturation, antigen presentation pathway, nuclear factor erythroid 2-related factor 2-mediated oxidative stress response, and cholesterol biosynthesis pathways in cigarette smoke-exposed cells. In conclusion, this report makes an important contribution to knowledge on molecular changes in a lung cell line in response to long term cigarette smoke exposure. The findings might inform future strategies for drug target, biomarker and diagnostics innovation in lung cancer, and clinical oncology. These observations also call for further research on the extent to which continuing or stopping cigarette smoking in patients diagnosed with lung cancer translates into molecular and clinical outcomes.

Exposure to cigarette smoke extract and lipopolysaccharide modifies cytoskeleton organization in bronchial epithelial cells

The integrity of the respiratory epithelium is crucial for airway homeostasis. Tobacco smoke exposure and recurrent infections of the airways play a crucial role in the progression and in the decline of the respiratory function in chronic obstructive pulmonary disease (COPD). The aim of this study was to detect differentially expressed proteins in a bronchial epithelial cell line (16-HBE) stimulated with cigarette smoke extract (CSE) and lipopolysaccharide (LPS), a constituent of gram-negative bacteria, alone and/or in combination, by using two-dimensional electrophoresis (2DE) analysis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Western blot analysis was applied to confirm the expression of significantly modulated proteins. Flow cytometry and immunofluorescence were used to assess F-actin polimerization by phalloidin method. Fourteen proteins, with significant (p < 0.05) changes in intensity, were identified at various experimental points: 6 were up-regulated and 8 were down-regulated. As expected, bioinformatic analysis revealed that most of these proteins are involved in anti-oxidant and immune responses and in cytoskeleton stability. Western blot analysis confirmed that: Proteasome activator complex subunit 2 (PSME2), Peroxiredoxin-6 (PRDX6), Annexin A5 (ANXA5) and Heat shock protein beta-1 (HSPB1) were reduced and Coactosin-like protein (COTL-1) was increased by co-exposure of CSE and LPS. Furthermore, LPS and CSE increased actin polimerization. In conclusion, although further validation studies are needed, our findings suggest that, CSE and LPS could contribute to the progressive deterioration of lung function, altering the expression of proteins involved in metabolic processes and cytoskeleton rearrangement in bronchial epithelial cells.

Evaluation of whole cigarette smoke induced oxidative stress in A549 and BEAS-2B cells

Cigarette smoke is a complex and oxidative aerosol. Previous researches on the hazards of cigarette smoke mainly focused on the adverse bioeffects induced by its condensates or gas vapor phase, which ignored the dynamic processes of smoking and the cigarette smoke aging. To overcome these disadvantages, we performed air-liquid interface exposure of whole smoke, which used native and unmodified smoke and ensured the exposure similar to physiological inhalation. Our results indicated that whole cigarette smoke induced lung epithelial cells (A549) and bronchial epithelial cells (BEAS-2B) damages in cytotoxicity assays (methyl thiazoly tetrazolium and neutral red uptake assays). In addition, A549 and BEAS-2B cells showed oxidative damages in whole smoke exposure, with concentration change of several biomarkers (reduced and oxidized glutathione, malondialdehyde, 4-hydroxyhydroxy-2-nonenal, extracellular superoxide dismutase, and 8-hydroxyl deoxyguanosine). These results indicate that whole smoke-induced oxidative stress occurs in two different kinds of cells at air-liquid interface.

Chronic Cigarette Smoke Mediated Global Changes in Lung Mucoepidermoid Cells: A Phosphoproteomic Analysis

Proteomics analysis of chronic cigarette smoke exposure is a rapidly emerging postgenomics research field. While smoking is a major cause of lung cancer, functional studies using proteomics approaches could enrich our mechanistic understanding of the elusive lung cancer global molecular signaling and cigarette smoke relationship. We report in this study on a stable isotope labeling by amino acids in cell culture-based quantitative phosphoproteomic analysis of a human lung mucoepidermoid carcinoma cell line, H292 cells, chronically exposed to cigarette smoke. Using high resolution Orbitrap Velos mass spectrometer, we identified the hyperphosphorylation of 493 sites, which corresponds to 341 proteins and 195 hypophosphorylated sites, mapping to 142 proteins upon smoke exposure (2.0-fold change). We report differential phosphorylation of multiple kinases, including PAK6, EPHA4, LYN, mitogen-activated protein kinase, and phosphatases, including TMEM55B, PTPN14, TIGAR, among others, in response to chronic cigarette smoke exposure. Bioinformatics analysis revealed that the molecules differentially phosphorylated upon chronic exposure of cigarette smoke are associated with PI3K/AKT/mTOR and CDC42-PAK signaling pathways. These signaling networks are involved in multiple cellular processes, including cell polarity, cytoskeletal remodeling, cellular migration, protein synthesis, autophagy, and apoptosis. The present study contributes to emerging proteomics insights on cigarette smoke mediated global signaling in lung cells, which in turn may aid in development of precision medicine therapeutics and postgenomics biomarkers.

Formoterol and fluticasone propionate combination improves histone deacetylation and anti-inflammatory activities in bronchial epithelial cells exposed to cigarette smoke

BACKGROUND

The addition of long-acting beta2-agonists (LABAs) to corticosteroids improves asthma control. Cigarette smoke exposure, increasing oxidative stress, may negatively affect corticosteroid responses. The anti-inflammatory effects of formoterol (FO) and fluticasone propionate (FP) in human bronchial epithelial cells exposed to cigarette smoke extracts (CSE) are unknown.

AIMS

This study explored whether FP, alone and in combination with FO, in human bronchial epithelial cellline (16-HBE) and primary bronchial epithelial cells (NHBE), counteracted some CSE-mediated effects and in particular some of the molecular mechanisms of corticosteroid resistance.

METHODS

16-HBE and NHBE were stimulated with CSE, FP and FO alone or combined. HDAC3 and HDAC2 activity, nuclear translocation of GR and NF-κB, pERK1/2/tERK1/2 ratio, IL-8, TNF-α, IL-1β mRNA expression, and mitochondrial ROS were evaluated. Actin reorganization in neutrophils was assessed by fluorescence microscopy using the phalloidin method.

RESULTS

In 16-HBE, CSE decreased expression/activity of HDAC3, activity of HDAC2, nuclear translocation of GR and increased nuclear NF-κB expression, pERK 1/2/tERK1/2 ratio, and mRNA expression of inflammatory cytokines. In NHBE, CSE increased mRNA expression of inflammatory cytokines and supernatants from CSE exposed NHBE increased actin reorganization in neutrophils. FP combined with FO reverted all these phenomena in CSE stimulated 16-HBE cells as well as in NHBE cells.

CONCLUSIONS

The present study provides compelling evidences that FP combined with FO may contribute to revert some processes related to steroid resistance induced by oxidative stress due to cigarette smoke exposure increasing the anti-inflammatory effects of FP.

Dung biomass smoke activates inflammatory signaling pathways in human small airway epithelial cells

Animal dung is a biomass fuel burned by vulnerable populations who cannot afford cleaner sources of energy, such as wood and gas, for cooking and heating their homes. Exposure to biomass smoke is the leading environmental risk for mortality, with over 4,000,000 deaths each year worldwide attributed to indoor air pollution from biomass smoke. Biomass smoke inhalation is epidemiologically associated with pulmonary diseases, including chronic obstructive pulmonary disease (COPD), lung cancer, and respiratory infections, especially in low and middle-income countries. Yet, few studies have examined the mechanisms of dung biomass smoke-induced inflammatory responses in human lung cells. Here, we tested the hypothesis that dung biomass smoke causes inflammatory responses in human lung cells through signaling pathways involved in acute and chronic lung inflammation. Primary human small airway epithelial cells (SAECs) were exposed to dung smoke at the air-liquid interface using a newly developed, automated, and reproducible dung biomass smoke generation system. The examination of inflammatory signaling showed that dung biomass smoke increased the production of several proinflammatory cytokines and enzymes in SAECs through activation of the activator protein (AP)-1 and arylhydrocarbon receptor (AhR) but not nuclear factor-κB (NF-κB) pathways. We propose that the inflammatory responses of lung cells exposed to dung biomass smoke contribute to the development of respiratory diseases.

Cigarette Smoke Modulates Repair and Innate Immunity following Injury to Airway Epithelial Cells

Cigarette smoking is the main risk factor associated with chronic obstructive pulmonary disease (COPD), and contributes to COPD development and progression by causing epithelial injury and inflammation. Whereas it is known that cigarette smoke (CS) may affect the innate immune function of airway epithelial cells and epithelial repair, this has so far not been explored in an integrated design using mucociliary differentiated airway epithelial cells. In this study, we examined the effect of whole CS exposure on wound repair and the innate immune activity of mucociliary differentiated primary bronchial epithelial cells, upon injury induced by disruption of epithelial barrier integrity or by mechanical wounding. Upon mechanical injury CS caused a delayed recovery in the epithelial barrier integrity and wound closure. Furthermore CS enhanced innate immune responses, as demonstrated by increased expression of the antimicrobial protein RNase 7. These differential effects on epithelial repair and innate immunity were both mediated by CS-induced oxidative stress. Overall, our findings demonstrate modulation of wound repair and innate immune responses of injured airway epithelial cells that may contribute to COPD development and progression.

Role of mitogen-activated protein kinase pathways in migration of gingival epithelial cells in response to stimulation by cigarette smoke condensate and infection by Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Previous studies have shown that cigarette smoke (CS) and periodontal pathogens could alter wound healing responses of gingival epithelial cells. To elucidate molecular mechanisms leading to these epithelial changes, we studied the signaling pathway involved in the modulation of cell migration by CS condensate (CSC) and the infection by a prominent periodontal pathogen, Porphyromonas gingivalis.

MATERIAL AND METHODS

Human gingival epithelial cells (Ca9-22) were treated with CSC or vehicle control for 24 h. Activation of mitogen-activated protein kinases (MAPK) in cells with or without infection by P. gingivalis was assessed by polymerase chain reaction array and immunoblotting using phospho-specific antibodies. Cell migration was assessed using in vitro wound closure model, and specific pharmacologic inhibitors of MAPK pathways were used to characterize further the extent of involvement of the MAPK pathways.

RESULTS

Polymerase chain reaction array showed that gene expression of several members of the MAPK, particularly p38 and JNK, was upregulated more than twofold in Ca9-22 cells stimulated with 10 μg/mL CSC. Coincubation with P. gingivalis induced a different pattern of gene expression for MAPK pathways, but it did not suppress the MAPK-related genes upregulated by CSC. A significant phosphorylation of ERK1/2 and p38 was observed in cells stimulated with 10 μg/mL CSC (p < 0.05), whereas coincubation with a higher concentration of CSC (250 μg/mL) evoked no such activation. P. gingivalis infection resulted in a tendency to reduce the phosphorylation of ERK1/2 and p38, which had been enhanced by stimulation with 10 μg/mL CSC. Incubation with ERK1/2 and p38 inhibitors significantly reduced the wound closure of CSC-stimulated cells, by approximately 43% and 46%, respectively (p < 0.05).

CONCLUSION

CSC exerts effects on the migration of human gingival epithelial cells through the activation of the MAPK ERK1/2 and p38 signaling pathways. P. gingivalis infection attenuates the CSC-induced migration at least partly by suppressing the phosphorylation of ERK1/2 and p38, but other pathways are likely to be involved in this modulatory process.

Mitochondrial Transplantation Attenuates Airway Hyperresponsiveness by Inhibition of Cholinergic Hyperactivity

Increased cholinergic activity has been highlighted in the pathogenesis of airway hyperresponsiveness, and alternations of mitochondrial structure and function appear to be involved in many lung diseases including airway hyperresponsiveness. It is crucial to clarify the cause-effect association between mitochondrial dysfunction and cholinergic hyperactivity in the pathogenesis of airway hyperresponsiveness. Male SD rats and cultured airway epithelial cells were exposed to cigarette smoke plus lipopolysaccharide administration; mitochondria isolated from airway epithelium were delivered into epithelial cells in vitro and in vivo. Both the cigarette smoke plus lipopolysaccharide-induced cholinergic hyperactivity in vitro and the airway hyperresponsiveness to acetylcholine in vivo were reversed by the transplantation of exogenous mitochondria. The rescue effects of exogenous mitochondria were imitated by the elimination of excessive reactive oxygen species or blockage of muscarinic M₃ receptor, but inhibited by M receptor enhancer. Mitochondrial transplantation effectively attenuates cigarette smoke plus lipopolysaccharide-stimulated airway hyperresponsiveness through the inhibition of ROS-enhanced epithelial cholinergic hyperactivity.

Acute stimulation of mesenchymal stem cells with cigarette smoke extract affects their migration, differentiation, and paracrine potential

Mesenchymal stem cells (MSCs) are known to play a key role in tissue regeneration, while smoking cigarettes is described to impair it. This work focuses on the effect cigarette smoke extract (CSE) has on the migration, differentiation, and paracrine potential of human adipose derived MSCs (AdMSCs). To mimic native conditions in vitro, AdMSCs were cultured in either monolayer or three-dimensional pellet cultures. While constant exposure to high concentrations of CSE had lethal effects on AdMSCs, lower concentrations of CSE impaired cell migration when compared to control conditions. The secretion of key interleukins was downregulated when CSE was exposed to the cells at low concentrations. Moreover, in this work AdMSCs were exposed to CSE while simultaneously being induced to differentiate into adipocytes, osteoblasts, and chondrocytes to determine the effect of CSE on the cells potential to differentiate. While adipogenic differentiation showed no significant variation, AdMSCs exposed to osteogenic and chondrogenic supplements showed both early and late genetic level variation when acutely exposed to low concentrations of CSE. Our results indicate that even a small amount of cigarette smoke can have detrimental effects on the regenerative potential of MSCs.

Apocynin and ebselen reduce influenza A virus-induced lung inflammation in cigarette smoke-exposed mice

Influenza A virus (IAV) infections are a common cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Oxidative stress is increased in COPD, IAV-induced lung inflammation and AECOPD. Therefore, we investigated whether targeting oxidative stress with the Nox2 oxidase inhibitors and ROS scavengers, apocynin and ebselen could ameliorate lung inflammation in a mouse model of AECOPD. Male BALB/c mice were exposed to cigarette smoke (CS) generated from 9 cigarettes per day for 4 days. On day 5, mice were infected with 1 × 10(4.5) PFUs of the IAV Mem71 (H3N1). BALF inflammation, viral titers, superoxide production and whole lung cytokine, chemokine and protease mRNA expression were assessed 3 and 7 days post infection. IAV infection resulted in a greater increase in BALF inflammation in mice that had been exposed to CS compared to non-smoking mice. This increase in BALF inflammation in CS-exposed mice caused by IAV infection was associated with elevated gene expression of pro-inflammatory cytokines, chemokines and proteases, compared to CS alone mice. Apocynin and ebselen significantly reduced the exacerbated BALF inflammation and pro-inflammatory cytokine, chemokine and protease expression caused by IAV infection in CS mice. Targeting oxidative stress using apocynin and ebselen reduces IAV-induced lung inflammation in CS-exposed mice and may be therapeutically exploited to alleviate AECOPD.

TNF-α and IL-1β-activated human mesenchymal stromal cells increase airway epithelial wound healing in vitro via activation of the epidermal growth factor receptor

Background

Mesenchymal stromal cells (MSCs) are investigated for their potential to reduce inflammation and to repair damaged tissue. Inflammation and tissue damage are hallmarks of chronic obstructive pulmonary disease (COPD) and MSC infusion is a promising new treatment for COPD. Inflammatory mediators attract MSCs to sites of inflammation and affect their immune-modulatory properties, but little is known about their effect on regenerative properties of MSCs. This study investigates the effect of the pro-inflammatory cytokines TNF-α and IL-1β on the regenerative potential of MSCs, using an in vitro wound healing model of airway epithelial cells.

Methods

Standardized circular wounds were created by scraping cultures of the airway epithelial cell line NCI-H292 and primary bronchial epithelial cells cultured at the air-liquid interface (ALI-PBEC), and subsequently incubated with MSC conditioned medium (MSC-CM) that was generated in presence or absence of TNF-α/IL-1β. Remaining wound size was measured up to 72 h. Phosphorylation of ERK1/2 by MSC-CM was assessed using Western blot. Inhibitors for EGFR and c-Met signaling were used to investigate the contribution of these receptors to wound closure and to ERK1/2 phosphorylation. Transactivation of EGFR by MSC-CM was investigated using a TACE inhibitor, and RT-PCR was used to quantify mRNA expression of several growth factors in MSCs and NCI-H292.

Results

Stimulation of MSCs with the pro-inflammatory cytokines TNF-α and IL-1β increased the mRNA expression of various growth factors by MCSs and enhanced the regenerative potential of MSCs in an in vitro model of airway epithelial injury using NCI-H292 airway epithelial cells. Conditioned medium from cytokine stimulated MSCs induced ERK1/2 phosphorylation in NCI-H292, predominantly via EGFR; it induced ADAM-mediated transactivation of EGFR, and it induced airway epithelial expression of several EGFR ligands. The contribution of activation of c-Met via HGF to increased repair could not be confirmed by inhibitor experiments.

Conclusion

Our data imply that at sites of tissue damage, when inflammatory mediators are present, for example in lungs of COPD patients, MSCs become more potent inducers of repair, in addition to their well-known immune-modulatory properties.

Pathogenic mechanisms of lung adenocarcinoma in smokers and non-smokers determined by gene expression interrogation

Cigarette smoking is the leading risk factor for lung cancer, which accounts for the highest number of cancer-related mortalities worldwide in men and women. Individuals with a history of smoking are 15-30 times more likely to develop lung cancer compared with those who do not smoke. However, our understanding of the underlying molecular mechanisms that contribute to lung tumorigenesis in smokers versus non-smokers remains incomplete. In order to investigate such mechanisms, the present study aimed to systemically interrogate microarray datasets from tumor biopsies and matching normal tissues from stage I and II lung adenocarcinoma patients who had never smoked or were current smokers. The gene expression analysis identified 422 (99 upregulated and 323 downregulated) and 534 (174 upregulated and 360 downregulated) differentially-expressed genes from the never-smokers and current smokers, respectively, and the two groups shared 277 genes that exhibited similar trends of alteration. These genes encode regulators that are involved in a variety of cellular functions, including collagen metabolism and homeostasis of caveolae plasma membranes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes characterization indicated that biological pathways, including extracellular matrix-receptor interaction and cell migration and proliferation, were all affected in the lung cancer patients regardless of the smoking status. However, smoking induced a unique gene expression pattern characterized by upregulation of cell cycle regulators (CDK1, CCNB1 and CDC20), as well as significantly affected biological networks, including p53 signaling pathways. Taken together, these findings suggest novel mechanistic insights, and provide an improved understanding of the smoking-induced molecular alterations that contribute to the pathogenesis of lung adenocarcinoma.

Application of CE-MS to a metabonomics study of human urine from cigarette smokers and non-smokers

BACKGROUND

Novel biomarkers of exposure and early adverse effects are needed for comparative studies of combustible and non-combustible tobacco products for regulatory authority evaluation. Metabolic biomarkers reflect both gene and environmental effects.

RESULTS

CE-MS has been applied to human urine samples from non-smokers and smokers of cigarettes at two tar levels. Validated chemometric models were able to separate smokers from non-smokers, with discrimination mainly based on the presence of nicotine metabolites. With these removed, it still proved possible to discriminate smokers from non-smokers with models now based on endogenous metabolites. The biochemical relevance of these biomarkers is discussed.

CONCLUSION

This proof-of-principle metabonomics study illustrates the potential of CE-MS to discover novel biomarkers in urine from tobacco users.

MD2 expression is reduced in large airways of smokers and COPD smokers

Toll-like receptor 4 (TLR4) signaling requires a number of accessory proteins to initiate a signal. MD-2 is one of the accessory proteins with a relevant role in lipopolysaccharide responses. Although cigarette smoke increases TLR4 expression, TLR4 signaling is altered in smokers and in smokers COPD patients. The main aims of this study were to explore whether MD2 is altered in large and small airways of COPD and of smokers without COPD. The expression of MD2 ex vivo was assessed by immunohistochemistry in surgical specimens from current smokers COPD (s-COPD; n = 14), smokers without COPD (S; n = 7), and from non-smoker non-COPD subjects (C; n = 11. The in vitro effects of cigarette smoke extracts on the MD2 expression in a human bronchial epithelial cell line (16-HBE) were also assessed by flow cytometry. MD2 is reduced in the epithelium and in the submucosa in large airways but not in the epithelium and in the submucosa in small airways of smokers and of s-COPD. The expression of MD2 in the submucosa of the large airways is significantly higher in comparison to the submucosa of the small airways in all the studied groups. In vitro, cigarette smoke is able to increase TLR4 but it reduces MD2 in a dose-dependent manner in bronchial epithelial cells. Cigarette smoke may alter innate immune responses reducing the expression of the MD2, a molecule with an important role in TLR4 signaling.

Cigarette smoke condensate modulates migration of human gingival epithelial cells and their interactions with Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

Epithelial cells are recognized as the first line of defense against bacterial infection and environmental harmful stimuli such as cigarette smoke (CS). Although previous studies explored the effects of nicotine on host cells, mechanisms by which CS affects cellular functions remain uncertain. The present study investigated the effects of CS condensate (CSC) on in vitro wound closure of gingival epithelial cells and their potential interactions with a major periodontal pathogen, Porphyromonas gingivalis.

MATERIAL AND METHODS

Human gingival epithelial cells (Ca9-22) were treated with CSC for 24 h. Cell proliferation was determined using a WST-1 assay. Cell migration was assessed using a wound closure model. The expression of integrins was analyzed by confocal scanning laser microscopy and real-time PCR. Intracellular invasion of P. gingivalis was evaluated by confocal scanning laser microscopy and an antibiotic protection assay.

RESULTS

Low concentrations (1-10 μg/mL) of CSC showed no significant effect on cell proliferation. CSC demonstrated dual effects on epithelial wound closure of Ca9-22 cells: high concentrations (i.e. 250 μg/mL) significantly inhibited the wound closure whereas low concentrations (i.e. 10 μg/mL) promoted it (p < 0.01). CSC induced distinct changes in cytoskeleton. When CSC-exposed cells were infected with P. gingivalis for 2 h, a significant inhibition of wound closure was observed concurrent with a decrease in integrin α3 expression near the wound area. A significantly increased P. gingivalis invasion into Ca9-22 was observed when exposed to low concentrations of CSC.

CONCLUSION

Low concentrations of CSC increased invasion of human gingival epithelial cells by P. gingivalis and induced changes in cytoskeleton and integrin expression, thereby modulating the cell migration.

Inhibition of FHL1 inhibits cigarette smoke extract-induced proliferation in pulmonary arterial smooth muscle cells

Cigarette smoke can induce pulmonary vascular remodeling, which involves pulmonary artery smooth muscle cell (PASMC) proliferation, resulting in pulmonary hypertension in chronic obstructive pulmonary disease. FHL1 is a member of the FHL subfamily, characterized by an N‑terminal half LIM domain, followed by four complete LIM domains, and has been suggested to be critical in cell proliferation. However, the effects of FHL1 on cigarette smoke‑induced PASMC proliferation and the precise molecular mechanism remain to be elucidated. The present study demonstrated that the protein expression of FHL1 correlated with cigarette smoke extract (CSE)‑induced PASMC proliferation. Knockdown of the expression of FHL1 using siRNA significantly suppressed cell proliferation and inhibited the cell cycle transition between the G1 and S phase by regulating the cyclin‑dependent kinase pathway at the basal level and following CSE stimulation. By contrast, overexpressing FHL1 using an adenovirus increased cell proliferation and promoted the cell cycle transition between the G1 and S phase. Furthermore, CSE significantly increased the protein expression of FHL1, however, exerted no effect on the mRNA expression levels. This alteration was due to the prolonged FHL1 half‑life, leading to the antagonizing of protein degradation. Collectively, these data suggested that FHL1 may be involved in excessive cell proliferation and may represent a potential therapeutic target for pulmonary hypertension.

Cytotoxicity of chronic exposure to 4 cigarette smoke condensates in 2 cell lines

Tobacco use is the leading preventable cause of death. The cytotoxicity of cigarette smoke condensate (CSC), the particulate fraction of cigarette smoke without the vapor phase, has mostly been tested in short-term in vitro studies lasting from a few hours to a few days. Here, we assessed the toxicity of CSCs from 2 reference cigarettes, 3R4F and CM6, using a primary human small airway epithelial (PSAE) cell line by quantifying adenosine 5'-triphosphate (ATP), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), total glutathione (reduced glutathione [GSH] + oxidized glutathione [GSSG]), and lactate dehydrogenase (LDH) release over the course of 28 days. The CSCs, 0.3 to 10 μg/mL, promoted cell proliferation at 120 hours of exposure, but demonstrated cytotoxicity at days 14 and 28. Interestingly, CSCs, 0.3 to 3 μg/mL, showed a cell death effect at day 14 but induced cell proliferation at day 28. Consistently, transformation associated with morphological changes began by day 14 and the transformed cells grew dramatically at day 28. The LDH assay appeared to be sensitive for assessing early cell damage, whereas the ATP, MTS, and GSH assays were more suitable for determining later stage CSCs-induced cytotoxicity. The ATP assay showed greater sensitivity than the MTS and GSH assays. We also assessed the toxicity of CSCs in an human Telomerase Reverse Transcriptase (hTERT)-immortalized Barrett esophagus cell line (CP-C). The CP-C cells demonstrated dose- and time-dependent cytotoxicity over the course of 28 days but displayed higher resistance to CSCs than PSAE cells. This study demonstrates that CSCs cause cytotoxicity and induce transformation related to cell resistance and cell invasion properties.

A systems biology approach reveals the dose- and time-dependent effect of primary human airway epithelium tissue culture after exposure to cigarette smoke in vitro

To establish a relevant in vitro model for systems toxicology-based mechanistic assessment of environmental stressors such as cigarette smoke (CS), we exposed human organotypic bronchial epithelial tissue cultures at the air liquid interface (ALI) to various CS doses. Previously, we compared in vitro gene expression changes with published human airway epithelia in vivo data to assess their similarities. Here, we present a follow-up evaluation of these in vitro transcriptomics data, using complementary computational approaches and an integrated mRNA-microRNA (miRNA) analysis. The main cellular pathways perturbed by CS exposure were related to stress responses (oxidative stress and xenobiotic metabolism), inflammation (inhibition of nuclear factor-κB and the interferon gamma-dependent pathway), and proliferation/differentiation. Within post-exposure periods up to 48 hours, a transient kinetic response was observed at lower CS doses, whereas higher doses resulted in more sustained responses. In conclusion, this systems toxicology approach has potential for product testing according to "21st Century Toxicology".

Expression variations of connective tissue growth factor in pulmonary arteries from smokers with and without chronic obstructive pulmonary disease

Cigarette smoking contributes to the development of pulmonary hypertension (PH) complicated with chronic obstructive pulmonary disease (COPD), and the pulmonary vascular remodeling, the structural basis of PH, could be attributed to abnormal proliferation of pulmonary artery smooth muscle cells (PASMCs).In this study, morphometrical analysis showed that the pulmonary vessel wall thickness in smoker group and COPD group was significantly greater than in nonsmokers. In addition, we determined the expression patterns of connective tissue growth factor (CTGF) and cyclin D1 in PASMCs harvested from smokers with normal lung function or mild to moderate COPD, finding that the expression levels of CTGF and cyclin D1 were significantly increased in smoker group and COPD group. In vitro experiment showed that the expression of CTGF, cyclin D1 and E2F were significantly increased in human PASMCs (HPASMCs) treated with 2% cigarette smoke extract (CSE), and two CTGF siRNAs with different mRNA hits successfully attenuated the upregulated cyclin D1 and E2F, and significantly restored the CSE-induced proliferation of HPASMCs by causing cell cycle arrest in G0. These findings suggest that CTGF may contribute to the pathogenesis of abnormal proliferation of HPASMCs by promoting the expression of its downstream effectors in smokers with or without COPD.

Basal cells contribute to innate immunity of the airway epithelium through production of the antimicrobial protein RNase 7

Basal cells play a critical role in the response of the airway epithelium to injury and are recently recognized to also contribute to epithelial immunity. Antimicrobial proteins and peptides are essential effector molecules in this airway epithelial innate immunity. However, little is known about the specific role of basal cells in antimicrobial protein and peptide production and about the regulation of the ubiquitous antimicrobial protein RNase 7. In this study, we report that basal cells are the principal cell type producing RNase 7 in cultured primary bronchial epithelial cells (PBEC). Exposure of submerged cultured PBEC (primarily consisting of basal cells) to the respiratory pathogen nontypeable Haemophilus influenzae resulted in a marked increase in expression of RNase 7, although this was not observed in differentiated air-liquid interface cultured PBEC. However, transient epithelial injury in air-liquid interface-cultured PBEC induced by cigarette smoke exposure led to epidermal growth factor receptor-mediated expression of RNase 7 in remaining basal cells. The selective induction of RNase 7 in basal cells by cigarette smoke was demonstrated using confocal microscopy and by examining isolated luminal and basal cell fractions. Taken together, these findings demonstrate a phenotype-specific innate immune activity of airway epithelial basal cells, which serves as a second line of airway epithelial defense that is induced by airway epithelial injury.

Inhibitory effects of Stemona tuberosa on lung inflammation in a subacute cigarette smoke-induced mouse model

BACKGROUND

Stemona tuberosa has long been used in Korean and Chinese medicine to ameliorate various lung diseases such as pneumonia and bronchitis. However, it has not yet been proven that Stemona tuberosa has positive effects on lung inflammation.

METHODS

Stemona tuberosa extract (ST) was orally administered to C57BL/6 mice 2 hr before exposure to CS for 2 weeks. Twenty-four hours after the last CS exposure, mice were sacrificed to investigate the changes in the expression of cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), chemokines such as keratinocyte-derived chemokine (KC) and inflammatory cells such as macrophages, neutrophils, and lymphocytes from bronchoalveolar lavage fluid (BALF). Furthermore, we compared the effect of ST on lung tissue morphology between the fresh air, CS exposure, and ST treatment groups.

RESULTS

ST significantly decreased the numbers of total cells, macrophages, neutrophils, and lymphocytes in the BALF of mice that were exposed to CS. Additionally, ST reduced the levels of cytokines (TNF-α, IL-6) and the tested chemokine (KC) in BALF, as measured by enzyme-linked immunosorbent assay (ELISA). We also estimated the mean alveolar airspace (MAA) via morphometric analysis of lung tissues stained with hematoxylin and eosin (H&E). We found that ST inhibited the alveolar airspace enlargement induced by CS exposure. Furthermore, we observed that the lung tissues of mice treated with ST showed ameliorated epithelial hyperplasia of the bronchioles compared with those of mice exposed only to CS.

CONCLUSIONS

These results indicate that Stemona tuberosa has significant effects on lung inflammation in a subacute CS-induced mouse model. According to these outcomes, Stemona tuberosa may represent a novel therapeutic herb for the treatment of lung diseases including COPD.

Effects in cigarette smoke stimulated bronchial epithelial cells of a corticosteroid entrapped into nanostructured lipid carriers

BACKGROUND

Nanomedicine studies have showed a great potential for drug delivery into the lung. In this manuscript nanostructured lipid carriers (NLC) containing Fluticasone propionate (FP) were prepared and their biocompatibility and effects in a human bronchial epithelial cell line (16-HBE) stimulated with cigarette smoke extracts (CSE) were tested.

RESULTS

Biocompatibility studies showed that the NLC did not induce cell necrosis or apoptosis. Moreover, it was confirmed that CSE increased intracellular ROS production and TLR4 expression in bronchial epithelial cells and that FP-loaded NLC were more effective than free drug in modulating these processes. Finally, the nanoparticles increased GSH levels improving cell protection against oxidative stress.

CONCLUSIONS

The present study shows that NLC may be considered a promising strategy to improve corticosteroid mediated effects in cellular models associated to corticosteroid resistance. The NLC containing FP can be considered good systems for dosage forms useful for increasing the effectiveness of fluticasone decreasing its side effects.

Alterations of bronchial epithelial metabolome by cigarette smoke are reversible by an antioxidant, O-methyl-L-tyrosinyl-γ-L-glutamyl-L-cysteinylglycine

Human bronchial epithelial cells (HBECs) have first-line contact with harmful substances during smoking, and changes in their metabolism most likely represent a defining factor in coping with the stress and development of airway diseases. This study was designed to determine the dynamics of metabolome changes in HBECs treated with cigarette smoke condensate (CSC), and to test whether normal metabolism can be restored by synthetic antioxidants. Principal component analysis, based on untargeted mass spectra, indicated that treatment of CSC-exposed HBECs with O-methyl-L-tyrosinyl-γ-L-glutamyl-L-cysteinylglycine (UPF1) acted faster than did N-acetylcysteine to revert the effect of CSC. The maximum effect of 10 μg/ml CSC itself on HBEC cell line, BEAS-2B, metabolism was seen at 2 hours after treatment, with return to the baseline level by 7 hours. In primary HBECs, the initial maximum effect was seen at 1 hour after CSC exposure. Certain metabolites associated with redox pathways and energy production were affected by CSC. Subsequent restoration of their content by UPF1 supports the hypothetical protective capacity of UPF1 against the oxidative stress and increased energy demand, respectively. Furthermore, UPF1 up-regulated the contents of phospholipid species identified as phosphatidylcholines and phosphatidylethanolamines in the CSC-exposed HBECs, indicating possible suppression of inflammatory processes along with an increase in spermidine as an endogenous cytoprotector. In conclusion, with this dynamic metabolomics study, we characterize the durability of the CSC-induced metabolic changes in BEAS-2B line cells and primary HBECs, and demonstrate the ability of UPF1 to significantly accelerate the recovery of HBECs from CSC insult.

Continual exposure to cigarette smoke extracts induces tumor-like transformation of human nontumor bronchial epithelial cells in a microfluidic chip

INTRODUCTION

Heavy cigarette smoking-related chronic obstructive pulmonary disease is an independent risk factor for lung squamous carcinoma. However, the mechanisms underlying the malignant transformation of bronchial epithelial cells are unclear.

METHODS

In our study, human tumor-adjacent bronchial epithelial cells were obtained from 10 cases with smoking-related chronic obstructive pulmonary disease and lung squamous carcinoma and cultured in an established microfluidic chip for continual exposure to cigarette smoke extracts (CSE) to investigate the potential tumor-like transformation and mechanisms. The integrated microfluidic chip included upstream concentration gradient generator and downstream cell culture chambers supplied by flowing medium containing different concentrations of CSE.

RESULTS

Our results showed that continual exposure to low doses of CSE promoted cell proliferation whereas to high doses of CSE triggered cell apoptosis. Continual exposure to CSE promoted reactive oxygen species production in human epithelial cells in a dose-dependent manner. More importantly, continual exposure to low dose of CSE promoted the epithelial-to-mesenchymal transition process and anchorage-independent growth, and increased chromosome instability in bronchial epithelial cells, accompanied by activating the GRP78, NF-κB, and PI3K pathways.

CONCLUSIONS

The established microfluidic chip is suitable for primary culture of human tumor-adjacent bronchial epithelial cells to investigate the malignant transformation. Continual exposure to low doses of CSE promoted tumor-like transformation of human nontumor bronchial epithelial cells by inducing reactive oxygen species production and activating the relevant signaling.