Diesel exhaust particle exposure exacerbates ciliary and epithelial barrier dysfunction in the multiciliated bronchial epithelium models.

Airway epithelium, the first defense barrier of the respiratory system, facilitates mucociliary clearance against inflammatory stimuli, such as pathogens and particulates inhaled into the airway and lung. Inhaled particulate matter 2.5 (PM2.5) can penetrate the alveolar region of the lung, and it can develop and exacerbate respiratory diseases. Although the pathophysiological effects of PM2.5 in the respiratory system are well known, its impact on mucociliary clearance of airway epithelium has yet to be clearly defined. In this study, we used two different 3D in vitro airway models, namely the EpiAirway-full-thickness (FT) model and a normal human bronchial epithelial cell (NHBE)-based air-liquid interface (ALI) system, to investigate the effect of diesel exhaust particles (DEPs) belonging to PM2.5 on mucociliary clearance. RNA-sequencing (RNA-Seq) analyses of EpiAirway-FT exposed to DEPs indicated that DEP-induced differentially expressed genes (DEGs) are related to ciliary and microtubule function and inflammatory-related pathways. The exposure to DEPs significantly decreased the number of ciliated cells and shortened ciliary length. It reduced the expression of cilium-related genes such as acetylated α-tubulin, ARL13B, DNAH5, and DNAL1 in the NHBEs cultured in the ALI system. Furthermore, DEPs significantly increased the expression of MUC5AC, whereas they decreased the expression of epithelial junction proteins, namely, ZO1, Occludin, and E-cadherin. Impairment of mucociliary clearance by DEPs significantly improved the release of epithelial-derived inflammatory and fibrotic mediators such as IL-1ß, IL-6, IL-8, GM-CSF, MMP-1, VEGF, and S100A9. Taken together, it can be speculated that DEPs can cause ciliary dysfunction, hyperplasia of goblet cells, and the disruption of the epithelial barrier, resulting in the hyperproduction of lung injury mediators. Our data strongly suggest that PM2.5 exposure is directly associated with ciliary and epithelial barrier dysfunction and may exacerbate lung injury.

Hsa_circ_0008833 promotes COPD progression via inducing pyroptosis in bronchial epithelial cells.

Purpose: Chronic obstructive pulmonary disease (COPD) is a common respiratory disorder. Pyroptosis represents a distinctive form of inflammatory cell death that is mediated through the activation of Caspase-1 and inflammasomes. CircRNAs have emerged as a novel class of biomolecules with implications in various human diseases. This study aims to investigate the circRNAs profile of in COPD progression and identify pivotal circRNAs associated with the development of this disease. Methods: he expression profiles of circRNAs in peripheral blood mononuclear cells of COPD patients were assessed by circRNA microarray. Furthermore, flag-labeled vectors were constructed to assess the potential protein-coding capacity of has-circ-0008833. 16HBE cells were stably transfected with lentivirus approach, and cell proliferation and death were assessed to clarify the functional roles of has-circ-0008833 and its encoded protein circ-0008833aa. Additionally, western blot analysis was furthered performed to determine the level of Caspase-1, IL-18, IL-1ß, NLRP3, ASC, and cleaved GSDMD regulated by has-circ-0008833 and circ-0008833-57aa. Results: Initially, we screened the expression profiles of human circRNAs in peripheral blood mononuclear cells of COPD patients, and found that has-circ-0008833 exhibited a significant increase in COPD mononuclear cells. Subsequently, we demonstrated that has-circ-0008833 carried an open reading frame (ORF), which encoded a functional protein, referred to as circ-0008833-57aa. By employing gain-of-function approaches, our results suggested that both circ-0008833 and circ-0008833-57aa inhibited proliferation, but accelerated the rate of 16HBE cell death. Finally, we discovered that circ-0008833 and circ-0008833-57aa promoted the expression of Caspase-1, IL-18, IL-1ß, NLRP3, ASC, and cleaved GSDMD in 16HBE cells. Conclusions: Upregulation of circ-0008833 might promote COPD progression by inducing pyroptosis of bronchial epithelial cells through the encoding of a 57-amino acid peptide.

Disruption of phosphofructokinase activity and aerobic glycolysis in human bronchial epithelial cells by atmospheric ultrafine particulate matter.

Exposure to ambient ultrafine particulate matter (UPM) causes respiratory disorders; however, the underlying molecular mechanisms remain unclear. In this study, we synthesized simulated UPM (sUPM) with controlled physicochemical properties using the spark-discharge method. Subsequently, we investigated the biological effects of sUPM using BEAS-2B human bronchial epithelial cells (HBECs) and a mouse intratracheal instillation model. High throughput RNA-sequencing and bioinformatics analyses revealed that dysregulation of the glycolytic metabolism is involved in the inhibited proliferation and survival of HBECs by sUPM treatment. Furthermore, signaling pathway and enzymatic analyses showed that the treatment of BEAS-2B cells with sUPM induces the inactivation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, also known as AKT), resulting in the downregulation of phosphofructokinase 2 (PFK2) S483 phosphorylation, PFK enzyme activity, and aerobic glycolysis in HBECs in an oxidative stress-independent manner. Additionally, intratracheal instillation of sUPM reduced the phosphorylation of ERK, AKT, and PFK2, decreased proliferation, and increased the apoptosis of bronchial epithelial cells in mice. The findings of this study imply that UPM induces pulmonary toxicity by disrupting aerobic glycolytic metabolism in lung epithelial cells, which can provide novel insights into the toxicity mechanisms of UPM and strategies to prevent their toxic effects.

Methyl lucidone inhibits airway inflammatory response by reducing TAK1 activity in human bronchial epithelial NCI-H292 cells.

Background: Methyl lucidone (ML), a methyl derivative of lucidone, has anti-inflammatory properties. However, the molecular mechanisms that reduce the inflammatory effect of ML in human lung epithelial cells remain unkown. This study aimed to elucidate the molecular mechanisms underlying the anti-inflammatory effect of ML. Methods: Four compounds (ML, methyl linderone, kanakugiol, and linderone) from Lindera erythrocarpa Makino were evaluated for their ability to reduce MUC5AC secretion levels in phorbol-12-myristate-13-acetate (PMA)-stimulated NCI-H292 cells using ELISA. The expression and secretion levels of inflammatory response-related proteins were analyzed using quantitative reverse transcription-PCR, ELISA, and western blotting. To determine whether ML directly regulates TGF-ß-activated kinase 1 (TAK1), we performed an in vitro kinase assay. Results: ML treatment effectively reduced the levels of inflammatory cytokines, including interleukin-1ß and TNF-α, increased by stimulation. Furthermore, ML downregulated the pathway cascade of both IκB kinase (IKK)/NF-κB and p38 mitogen-activated protein (MAP) kinase/CREB by inhibiting the upstream kinase TAK1. An in vitro kinase analysis confirmed that ML treatment significantly reduced the kinase activity of TAK1. Conclusion: ML pretreatment repressed the PMA-stimulated inflammation reaction by reducing the TAK1-mediated IKK/NF-κB and p38 MAP kinase/CREB signaling. These findings suggest that ML may improve respiratory health and can be used as a dietary supplement or functional food to prevent inflammatory lung diseases.

A study on specific factors related to inflammation and autophagy in BEAS-2B cells induced by urban particulate matter (PM, 1648a) and histological evaluation of PM-induced bronchial asthma model in mice.

As particulate matter (PM) poses an increasing risk, research on its correlation with diseases is active. However, researchers often use their own PM, making it difficult to determine its components. To address this, we investigated the effects of PM with known constituents on BEAS-2B cells, examining cytokine levels, reactive oxygen species ROS production, DNA damage, and MAPK phosphorylation. Additionally, we evaluated the effects of PM on normal and OVA-induced asthmatic mice by measuring organ weight, cytokine levels, and inflammatory cells in bronchoalveolar lavage fluid, and examining histological changes. PM markedly increased levels of IL-6, GM-CSF, TNF-α, ROS, nitric oxide, and DNA damage, while surprisingly reducing IL-8 and MCP-1. Moreover, PM increased MAPK phosphorylation and inhibited mTOR and AKT phosphorylation. In vivo, lung and spleen weights, IgE, OVA-specific IgE, IL-4, IL-13, total cells, macrophages, lymphocytes, mucus generation, and LC3II were higher in the asthma group. PM treatment in asthmatic mice increased lung weight and macrophage infiltration, but decreased IL-4 and IL-13 in BALF. Meanwhile, PM treatment in the Nor group increased total cells, macrophages, lymphocytes, and mucus generation. Our study suggests that PM may induce and exacerbate lung disease by causing immune imbalance via the MAPK and autophagy pathways, resulting in decreased lung function due to increased smooth muscle thickness and mucus generation.

Silencing of GRHL2 induces epithelial­to­mesenchymal transition in lung cancer cell lines with different effects on proliferation and clonogenic growth.

Grainyhead-like 2 (GRHL2) is a transcription factor that suppresses epithelial-to-mesenchymal transition (EMT). It has been previously shown that GRHL2 can confer both oncogenic and tumor-suppressive roles in human cancers, including breast, pancreatic and colorectal cancers. However, its role in lung cancer remains elusive. In the present study, a meta-analysis of multiple gene expression datasets with clinical data revealed that GRHL2 expression was increased in lung cancer compared with that in the normal tissues. Copy number analysis of GRHL2, performed using datasets of whole exome sequencing involving 151 lung cancer cell lines, revealed frequent amplifications, suggesting that the increased GRHL2 expression may have resulted from gene amplification. A survival meta-analysis of GRHL2 using The Cancer Genome Atlas (TCGA) dataset showed no association of GRHL2 expression with overall survival. GRHL2 expression was found to be associated with EMT status in lung cancer in TCGA dataset and lung cancer cell lines. GRHL2 knockdown induced partial EMT in the hTERT/Cdk4-immortalized normal lung epithelial cell line HBEC4KT without affecting proliferation measured by CCK-8 assays. In addition, GRHL2 silencing caused three lung cancer cell lines, H1975, H2009 and H441, to undergo partial EMT. However, the proliferative effects differed significantly. GRHL2 silencing promoted proliferation but not colony formation in H1975 cells whilst suppressing colony formation without affecting proliferation in H2009 cells, but it did not affect proliferation in H441 cells. These results suggest cell type-dependent effects of GRHL2 knockdown. Downstream, GRHL2 silencing enhanced the phosphorylation of AKT and ERK, assessed by western blotting with phospho-specific antibodies, in HBEC4KT, H1975 and H2009 cell lines but not in the H441 cell line. By contrast, transient GRHL2 overexpression did not affect A549 cell proliferation, which lack detectable endogenous expression of the GRHL2 protein. However, GRHL2 overexpression did suppress E-cadherin expression in A549 cells. These results suggested that GRHL2 does not only function as a tumor suppressor of EMT but can also behave as an oncogene depending on the lung cancer cell-type context.

Flavored E-cigarette product aerosols induce transformation of human bronchial epithelial cells.

OBJECTIVES: E-cigarettes are the most commonly used nicotine containing products among youth. In vitro studies support the potential for e-cigarettes to cause cellular stress in vivo; however, there have been no studies to address whether exposure to e-liquid aerosols can induce cell transformation, a process strongly associated with pre-malignancy. We examined whether weekly exposure of human bronchial epithelial cell (HBEC) lines to e-cigarette aerosols would induce transformation and concomitant changes in gene expression and promoter hypermethylation. MATERIALS AND METHODS: An aerosol delivery system exposed three HBEC lines to unflavored e-liquid with 1.2% nicotine, 3 flavored products with nicotine, or the Kentucky reference cigarette once a week for 12 weeks. Colony formation in soft agar, RNA-sequencing, and the EPIC Beadchip were used to evaluate transformation, genome-wide expression and methylation changes. RESULTS: Jamestown e-liquid aerosol induced transformation of HBEC2 and HBEC26, while unflavored and Blue Pucker transformed HBEC26. Cigarette smoke aerosol transformed HBEC4 and HBEC26 at efficiencies up to 3-fold greater than e-liquids. Transformed clones exhibited extensive reprogramming of the transcriptome with common and distinct gene expression changes observed between the cigarette and e-liquids. Transformation by e-liquids induced alterations in canonical pathways implicated in lung cancer that included axonal guidance and NRF2. Gene methylation, while prominent in cigarette-induced transformed clones, also affected hundreds of genes in HBEC2 transformed by Jamestown. Many genes with altered expression or epigenetic-mediated silencing were also affected in lung tumors from smokers. CONCLUSIONS: These studies show that exposure to e-liquid aerosols can induce a pre-malignant phenotype in lung epithelial cells. While the Food and Drug Administration banned the sale of flavored cartridge-based electric cigarettes, consumers switched to using flavored products through other devices. Our findings clearly support expanding studies to evaluate transformation potency for the major categories of e-liquid flavors to better inform risk from these complex mixtures.

Hexavalent chromium induces γH2AX and RAD51 involved in DNA damage repair in BEAS-2B cells by modulating LNC-DHFR-4:1.

Hexavalent chromium [Cr(VI)] is rarely found in nature. Its occurrence in the environment is mainly due to anthropogenic sources. Our previous studies have shown that Cr(VI) exposure could change the expression profile of long noncoding RNAs (lncRNAs). However, the relationship between lncRNAs and genetic damage induced by Cr(VI) remains unclear. In this study, RT-qPCR was used to verify the expression of genes and lncRNAs involved in DNA damage repair in BEAS-2B cells exposed to different Cr(VI) concentrations. After screening out LNC-DHFR-4:1, overexpression and knockdown models of BEAS-2B cells were used to further identify the relationship between the lncRNA and RAD51. RT-qPCR and indirect immunofluorescence were used to detect expression. Our results revealed that with increasing Cr(VI) concentration, γH2AX expression was increased, while the expression of RAD51 was decreased. Meanwhile, LNC-DHFR-4:1 acted as a competitive endogenous RNA to regulate the expression of γH2AX and RAD51, which further affected DNA damage repair. The overexpression of LNC-DHFR-4:1 induced a twofold decrease in γH2AX and a onefold increase in RAD51, and its knockdown showed the opposite results. These results suggested that LNC-DHFR-4:1 might be a potential biomarker of Cr(VI)-induced DNA damage repair in BEAS-2B cells.

The quorum sensing com system regulates pneumococcal colonisation and invasive disease in a pseudo-stratified airway tissue model.

BACKGROUND: The effects of the com quorum sensing system during colonisation and invasion of Streptococcus pneumoniae (Spn) are poorly understood. METHODS: We developed an ex vivo model of differentiated human airway epithelial (HAE) cells with beating ciliae, mucus production and tight junctions to study Spn colonisation and translocation. HAE cells were inoculated with Spn wild-type TIGR4 (wtSpn) or its isogenic ΔcomC quorum sensing-deficient mutant. RESULTS: Colonisation density of ΔcomC mutant was lower after 6 h but higher at 19 h and 30 h compared to wtSpn. Translocation correlated inversely with colonisation density. Transepithelial electric resistance (TEER) decreased after pneumococcal inoculation and correlated with increased translocation. Confocal imaging illustrated prominent microcolony formation with wtSpn but disintegration of microcolony structures with ΔcomC mutant. ΔcomC mutant showed greater cytotoxicity than wtSpn, suggesting that cytotoxicity was likely not the mechanism leading to translocation. There was greater density- and time-dependent increase of inflammatory cytokines including NLRP3 inflammasome-related IL-18 after infection with ΔcomC compared with wtSpn. ComC inactivation was associated with increased pneumolysin expression. CONCLUSIONS: ComC system allows a higher organisational level of population structure resulting in microcolony formation, increased early colonisation and subsequent translocation. We propose that ComC inactivation unleashes a very different and possibly more virulent phenotype that merits further investigation.

Anemoside B4 prevents chronic obstructive pulmonary disease through alleviating cigarette smoke-induced inflammatory response and airway epithelial hyperplasia.

BACKGROUND: Cigarette smoke (CS) is one of the major risk factors for chronic obstructive pulmonary disease (COPD) and increases the risk of lung cancer (LC). Anemoside B4 (B4) is the main bioactive ingredient in Pulsatilla chinensis (P. chinensis), a traditional medicinal herb for various diseases. It has a wide range of anti-inflammatory, anti-oxidation and anti-cancer activities. However, in recent years, there is no relevant literature report on the therapeutic effect of B4 on COPD, and the anti-inflammatory and inhibitory effects of anemoside B4 on basal cell hyperplasia in CS-induced COPD have not been clearly established. PURPOSE: In the present study, we investigated whether anemoside B4 could alleviate CS or cigarette smoke extract (CSE) induced inflammation of COPD and further prevent basal cell hyperplasia, hoping to find its possible mechanism. METHODS: In this study, a COPD mouse model was established in C57BL mice by CS exposure 3 months. Bronchial pathology and basal cell hyperplasia were observed by HE staining and immunostaining. The contents of glutathione peroxidase catalase (GSH-PX), malondialdehyde (MDA) and superoxide dismutase (MPO) were determined by GSH-PX, MDA and SOD assay kits, respectively. 16HBE cells were cultured with 5% CSE with or without treatment with B4 (1, 10, 100 µM) or DEX (20 µM) in vitro. Cell viability was assessed by a cell counting kit 8 (CCK-8). Reactive oxygen species (ROS) generation was tested by DCFH-DA. Moreover, anti-inflammatory mechanism of anemoside B4 was further determined by pro-inflammatory cytokines production using RT-PCR. Protein expression levels of MAPK/AP-1/TGF-ß signaling pathway were measured by western blot. RESULTS: Anemoside B4 improved the lung function of mice, relieved lung inflammation and reduced the MDA, MPO and GSH-Px in the plasma. At the same time, B4 repressed the oxidative stress response and played a role in balancing the levels of protease and anti-protease. During the process of bronchial basal cell hyperplasia, B4 alleviated the degree of cell hyperplasia, and prevented further deterioration of hyperplasia through increased P53 and inhibited FHIT protein. In addition, B4 reduced ROS levels in human bronchial epithelial cells stimulated by CSE in vitro study. Meanwhile, B4 treatment also significantly attenuated increased IL-1ß, TGF-ß, IL-8 and TNF-α from CSE treated human bronchial epithelial cells. The expression of p-P38, AP-1(c-fos, and c-Jun), TGF-ß proteins in MAPK/AP-1/TGF-ß signaling pathway were decreased and the signal cascade reaction was blocked. CONCLUSION: Anemoside B4 protects against CS-induced COPD. These findings indicated that B4 may have therapeutic potential for the prevention and treatment of COPD.

Comparison of immune response to human rhinovirus C and respiratory syncytial virus in highly differentiated human airway epithelial cells.

BACKGROUND: Human rhinovirus C (HRV-C) accounts for a large proportion of HRV-related illnesses, but the immune response to HRV-C infection has not been elucidated. Our objective was to assess the effect of HRV-C on cytokine secretion in human bronchial epithelial (HBE) cells grown at air-liquid interface (ALI) and compare it with that of respiratory syncytial virus (RSV). METHODS: HBE cells were differentiated at ALI culture and the full-length cDNA clones of HRV-C651 and HRV-C15, clinical isolates of HRV-C79 and HRV-C101, and two RSV isolates were inoculated in the HBE cells. The effect of HRV-C on cytokine secretion was assessed and compared with that of RSV. RESULTS: HRV-Cs infect and propagate in fully differentiated HBE cells and significantly increase the secretion of IFN-λ1, CCL5, IP10, IL-6, IL-8, and MCP-1. The virus loads positively correlated with the levels of the cytokines. HRV-C induced lower secretion of CCL5 (P = 0.048), IL-6 (P = 0.016), MCP-1 (P = 0.008), and IL-8 (P = 0.032), and similar secretion of IP10 (P = 0.214) and IFN-λ1 (P = 0.214) when compared with RSV. CONCLUSION: HBE ALI culture system supported HRV-C infection and propagation and HRV-C induced relatively weaker cytokine expression than RSV.

Effects of Antioxidant on Oxidative Stress and Autophagy in Bronchial Epithelial Cells Exposed to Particulate Matter and Cigarette Smoke Extract.

BACKGROUND: We evaluated the effect of particulate matter (PM) and cigarette smoke extract (CSE) on bronchial epithelial cell survival, as well as oxidative stress and autophagy levels. Moreover, we aimed to assess the effect of the antioxidant N-acetylcysteine (NAC) on the adverse effects of PM and CSE exposure. METHODS: Normal human bronchial epithelial cells (BEAS-2B cells) were exposed to urban PM with or without CSE, after which cytotoxic effects, including oxidative stress and autophagy levels, were measured. After identifying the toxic effects of urban PM and CSE exposure, the effects of NAC treatment on cell damage were evaluated. RESULTS: Urban PM significantly decreased cell viability in a concentration-dependent manner, which was further aggravated by simultaneous treatment with CSE. Notably, pretreatment with NAC at 10 mM for 1 hour reversed the cytotoxic effects of PM and CSE co-exposure. Treatment with 1, 5, and 10 mM NAC was shown to decrease reactive oxygen species levels induced by exposure to both PM and CSE. Additionally, the autophagy response assessed via LC3B expression was increased by PM and CSE exposure, and this also attenuated by NAC treatment. CONCLUSION: The toxic effects of PM and CSE co-exposure on human bronchial epithelial cells, including decreased cell viability and increased oxidative stress and autophagy levels, could be partly prevented by NAC treatment.

miR-558 Reduces the Damage of HBE Cells Exposed to Cigarette Smoke Extract by Targeting TNFRSF1A and Inactivating TAK1/MAPK/NF-κB Pathway.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a chronic smoking-related lung disease associated with higher mortality and morbidity. Herein, we attempted to investigate the function of miR-558/TNF Receptor Superfamily Member 1A (TNFRSF1A) in the progression of COPD. METHODS: GEO database was applied to filtrate the differentially expressed mRNAs and miRNAs. KEGG enrichment was used to select the meaningful pathway related to the differentially expressed genes. TargetScan was used to predict the upstream regulator of TNFRSF1A, which was further affirmed by dual luciferase assay. HBE cells were stimulated by 20 µg/mL cigarette smoke extract (CSE) to mimic the COPD in vitro. The activity, apoptosis and inflammatory factors of HBE cells were evaluated by biological experiments. The levels of proteins related to TAK1/MAPK/NF-κB pathway were measured by Western blot. RESULTS: TNFRSF1A is found to be highly expressed in COPD samples and enriched in TNF signaling pathway through bioinformatics analysis. miR-558 was verified as an upstream regulator of TNFRSF1A and negatively regulated TNFRSF1A expression. Up-regulation of miR-558 alleviated CSE-induced damage on HBE cells. The alleviative effect of miR-558 mimic on CSE-induced damage was suppressed by TNFRSF1A overexpression. The elevated expression of p-TAK1/p-p38 MAPK/p-NF-κB P65 in CSE condition was suppressed by miR-558 up-regulation. However, the results were reversed by TNFRSF1A overexpression. TAK1 inhibitor blocked the activation of TAK1/MAPK/NF-κB pathway, which was consistent with the results from miR-558 up-regulation. CONCLUSIONS: Up-regulation of miR-558 relieved the damage of HBE cells-triggered by CSE via reducing TNFRSF1A and inactivating TAK1/MAPK/NF-κB pathway, affording novel molecules for COPD treatment.

Knockdown of long noncoding RNA growth arrest-specific transcript 5 regulates forkhead box O3 to inhibit lipopolysaccharide-induced human bronchial epithelial cell pyroptosis.

Pyroptosis is a novel proinflammatory programmed cell death process. This study was designed to investigate the functional mechanisms of long noncoding RNA growth arrest-specific transcript 5 (lncRNA GAS5) on lipopolysaccharide (LPS)-induced human bronchial epithelial cell (HBEC) pyroptosis. LPS was used to induce pyroptosis in HBECs, followed by the detection of the expression of GAS5, forkhead box O3 (FOXO3), and nuclear factor E2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling pathway-related factors. Cell viability was evaluated using CCK-8 assay, lactate dehydrogenase (LDH) release was assessed by LDH assay kit and caspase-1 activity by flow cytometry. Furthermore, expression of NOD-like receptor family pyrin domain containing 3 and pyroptosis-related proteins was evaluated using Western blot analysis, while enzyme-linked immunosorbent assay was used to determine the levels of inflammatory factors. The interaction between GAS5 and FOXO3 was confirmed using bioinformatic prediction, RNA immunoprecipitation assay, RNA pull-down, and dual-luciferase reporter gene assay. Treatment of HBECs with LPS upregulated the expression of GAS5 and FOXO3, resulting in the inactivation of the Nrf2/HO-1 signaling pathway. On the other hand, inhibition of both GAS5 and FOXO3 promoted cell viability, reduced LDH release, pyroptosis, and inflammatory response in LPS-induced HBECs. Furthermore, FOXO3 could interact with GAS5, while FOXO3 overexpression reversed the inhibitory effect of GAS5 knockdown on cell pyroptosis. Thus, mechanistically, inhibition of FOXO3 activates the Nrf2/HO-1 pathway to suppress LPS-induced pyroptosis in HBECs. This study revealed that GAS5 knockdown attenuates FOXO3 expression thereby activating the Nrf2/HO-1 pathway to inhibit LPS-induced pyroptosis in HBECs. These findings may contribute to identifying novel targets that inhibit pyroptosis in HBECs.

MicroRNA-567 inhibits cell proliferation and induces cell apoptosis in A549 NSCLC cells by regulating cyclin-dependent kinase 8.

MicroRNA-567 (miR-567) plays a decisive role in cancers whereas its role in non-small cell lung cancer (NSCLC) is still unexplored. This study was therefore planned to explore the regulatory function of miR-567 in A549 NSCLC cells and investigate its possible molecular mechanism that may help in NSCLC treatment. In the current study, miR-567 expression was examined by quantitative real time-polymerase chain reaction (qRT-PCR) in different NSCLC cell lines in addition to normal cell line. A549 NSCLC cells were transfected by miR-567 mimic, miR-567 inhibitor, and negative control siRNA. Cell proliferation was evaluated by MTT and 5-bromo-2'deoxyuridine assays. Cell cycle distribution and apoptosis were studied by flow cytometry. Bioinformatics analysis programs were used to expect the putative target of miR-567. The expression of cyclin-dependent kinase 8 (CDK8) gene at mRNA and protein levels were evaluated by using qRT-PCR and western blotting. Our results found that miR-567 expressions decreased in all the studied NSCLC cells as compared to the normal cell line. A549 cell proliferation was suppressed by miR-567 upregulation while cell apoptosis was promoted. Also, miR-567 upregulation induced cell cycle arrest at sub-G1 and S phases. CDK8 was expected as a target gene of miR-567. MiR-567 upregulation decreased CDK8 mRNA and protein expression while the downregulation of miR-567 increased CDK8 gene expression. These findings revealed that miR-567 may be a tumor suppressor in A549 NSCLC cells through regulating CDK8 gene expression and may serve as a novel therapeutic target for NSCLC treatment.

Curcumin protects BEAS­2B cells from PM2.5­induced oxidative stress and inflammation by activating NRF2/antioxidant response element pathways.

Fine particulate matter (PM2.5) with an average aerodynamic diameter of <2.5 µm can cause severe lung injury. Oxidative stress and inflammation are considered the main outcomes of PM2.5 exposure. Curcumin is a well­known antioxidant; however, its effect on PM2.5­induced oxidative injury in airway epithelial cells remains unclear. In the present study, it was demonstrated that pre­treatment with curcumin significantly reduced the PM2.5­induced apoptosis of BEAS­2B human bronchial epithelial cells by decreasing the level of intercellular reactive oxygen species. Western blot analysis revealed that curcumin increased the expression of nuclear factor erythroid 2­related factor 2 (NRF2) and regulated the transcription of downstream genes, particularly those encoding antioxidant enzymes. Moreover, curcumin reduced the PM2.5­induced expression and production of inflammatory factors, and induced the expression of the anti­inflammatory factors, interleukin (IL)­5 and IL­13. Taken together, the present study demonstrates that curcumin protects BEAS­2B cells against PM2.5­induced oxidative damage and inflammation, and prevents cell apoptosis by increasing the activation of NRF2­related pathways. It is thus suggested that curcumin may be a potential compound for use in the prevention of PM2.5­induced tissue injury.

Sustained high expression of NRF2 and its target genes induces dysregulation of cellular proliferation and apoptosis is associated with arsenite-induced malignant transformation of human bronchial epithelial cells.

In arsenic toxicity, activation of the erythroid 2-related factor 2 (NRF2) pathway is regarded as a driver of cancer development and progression; however, the mechanisms by which NRF2 gene expression regulates cell cycle progression and mediates pathways of cellular proliferation and apoptosis in arsenic-induced lung carcinogenesis are poorly understood. In this study, we explored the regulatory functions of NRF2 expression and its target genes in immortalized human bronchial epithelial (HBE) cells continuously exposed to 1.0 µM sodium arsenite over approximately 43 passages (22 weeks). The experimental treatment induced malignant transformation in HBE cells, characterized by increased cellular proliferation and soft agar clone formation, as well as cell migration, and accelerated cell cycle progression from G0/G1 to S phase with increased levels of cyclin E-CDK2 complex,decreased cellular apoptosis rate. Moreover, we observed a sustained increase in NRF2 protein levels and those of its target gene products (NQO1, BCL-2) with concurrently decreased expression of apoptosis-related proteins (BAX, Cleaved-caspase-3/Caspase-3 and CHOP) and increased expression of the anti-apoptotic protein MCL-1. Silencing NRF2 expression with small interfering RNA (siRNA) in arsenite-transformed (T-HBE) cells was shown to reverse the malignant phenotype. Further, siRNA silencing of NQO1 significantly decreased levels of the cyclin E-CDK2 complex, inhibiting G0/G1 to S phase cell cycle progression and transformation to the T-HBE phenotypes. This study demonstrated a novel role for the NRF2/NQO1 signaling pathway in mediating arsenite-induced cell transformation by increasing the expression of cyclin E-CDK2, and accelerating the cell cycle and cell proliferation. Arsenite promotes activation of the NRF2/BCL-2 signaling pathway inhibited CHOP increasing cellular resistance to apoptosis and further promoting malignant transformation.

Tiotropium/Olodaterol treatment reduces cigarette smoke extract-induced cell death in BEAS-2B bronchial epithelial cells.

BACKGROUND: Cigarette smoking is a critical risk factor for the destruction of lung parenchyma or the development of emphysema, which is characteristic of COPD. Disruption of epithelial layer integrity may contribute to lung injury following cigarette smoke extract (CSE) exposure. Tiotropium/olodaterol acts as a bronchodilator for COPD treatment; however, the effect of dual bronchodilators on epithelial cell injury and its underlying mechanism remain unclear. In this study, we evaluated the effect of tiotropium/olodaterol on CSE-mediated cell death and the underlying mechanisms. METHODS: Cell viability was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis, necrosis, and autophagy were evaluated using flow cytometry. Autophagy-related protein, phosphorylated ERK, expression was determined using Western blotting. RESULTS: Tiotropium/olodaterol significantly inhibited CSE-induced cell death, mitochondria dysfunction, and autophagy, which had no significant effect on apoptosis or necrosis in BEAS-2B human bronchial epithelial cells. Moreover, tiotropium/olodaterol attenuated CSE-induced upregulation of JNK. CONCLUSIONS: CSE induced cell death and caused consistent patterns of autophagy and JNK activation in BEAS-2B human bronchial epithelial cells. Tiotropium/olodaterol treatment protected bronchial epithelial cells from CSE-induced injury and inhibited activation of autophagy and upregulation of JNK phosphorylation. These results indicate that tiotropium/olodaterol may protect epithelial cells from the deleterious effects of CSE exposure, which is associated with the regulation of autophagy and JNK activation.

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.

Distinct infection process of SARS-CoV-2 in human bronchial epithelial cell lines.

Coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), leads to a series of clinical symptoms of respiratory and pulmonary inflammatory reactions via unknown pathologic mechanisms related to the viral infection process in tracheal or bronchial epithelial cells. Investigation of this viral infection in the human bronchial epithelial cell line (16HBE) suggests that SARS-CoV-2 can enter these cells through interaction between its membrane-localized S protein with the angiotensin-converting enzyme 2 molecule on the host cell membrane. Further observation indicates distinct viral replication with a dynamic and moderate increase, whereby viral replication does not lead to a specific cytopathic effect but maintains a continuous release of progeny virions from infected cells. Although messenger RNA expression of various innate immune signaling molecules is altered in the cells, transcription of interferons-α (IFN-α), IFN-ß, and IFN-γ is unchanged. Furthermore, expression of some interleukins (IL) related to inflammatory reactions, such as IL-6, IL-2, and IL-8, is maintained at low levels, whereas that of ILs involved in immune regulation is upregulated. Interestingly, IL-22, an IL that functions mainly in tissue repair, shows very high expression. Collectively, these data suggest a distinct infection process for this virus in respiratory epithelial cells, which may be linked to its clinicopathological mechanism.