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.

mtDNA amplifies beryllium sulfate-induced inflammatory responses via the cGAS-STING pathway in 16HBE cells.

Beryllium sulfate (BeSO4) can cause inflammation through the mechanism, which has not been elucidated. Mitochondrial DNA (mtDNA) is a key contributor of inflammation. With mitochondrial damage, released mtDNA can bind to specific receptors (e.g., cGAS) and then activate related pathway to promote inflammatory responses. To investigate the mechanism of mtDNA in BeSO4-induced inflammatory response in 16HBE cells, we established the BeSO4-induced 16HBE cell inflammation model and the ethidium bromide (EB)-induced ρ016HBE cell model to detect the mtDNA content, oxidative stress-related markers, mitochondrial membrane potential, the expression of the cGAS-STING pathway, and inflammation-related factors. Our results showed that BeSO4 caused oxidative stress, decline of mitochondrial membrane potential, and the release of mtDNA into the cytoplasm of 16HBE cells. In addition, BeSO4 induced inflammation in 16HBE cells by activating the cGAS-STING pathway. Furthermore, mtDNA deletion inhibited the expression of cGAS-STING pathway, IL-10, TNF-α, and IFN-ß. This study revealed a novel mechanism of BeSO4-induced inflammation in 16HBE cells, which contributes to the understanding of the molecular mechanism of beryllium and its compounds-induced toxicity.

Hydrogen sulfide alleviates beryllium sulfate-induced ferroptosis and ferritinophagy in 16HBE cells.

Beryllium sulfate (BeSO4 ) can result to lung injuries, such as leading to lipid peroxidation and autophagy, and the treatment of beryllium disease has not been well improved. Ferroptosis is a regulated cell death process driven by iron-dependent and lipid peroxidation, while ferritinophagy is a process mediated by nuclear receptor coactivator 4 (NCOA4), combined with ferritin heavy chain 1 (FTH1) degradation and release Fe2+ , which regulated intracellular iron metabolism and ferroptosis. Hydrogen sulfide (H2 S) has the effects of antioxidant, antiautophagy, and antiferroptosis. This study aimed to investigate the effect of H2 S on BeSO4 -induced ferroptosis and ferritinophagy in 16HBE cells and the underlying mechanism. In this study, BeSO4 -induced 16HBE cell injury model was established based on cellular level and pretreated with deferoxamine (DFO, a ferroptosis inhibitor), sodium hydrosulfide (NaHS, a H2 S donor), or NCOA4 siRNA and, subsequently, performed to detect the levels of lipid peroxidation and Fe2+ and the biomarkers of ferroptosis and ferritinophagy. More importantly, our research found that DFO, NaHS, or NCOA4 siRNA alleviated BeSO4 -induced ferroptosis and ferritinophagy by decreasing the accumulation of Fe2+ and lipid peroxides. Furthermore, the relationship between ferroptosis, ferritinophagy, H2 S, and beryllium disease is not well defined; therefore, our research is innovative. Overall, our results provided a new theoretical basis for the prevention and treatment of beryllium disease and suggested that the application of H2 S, blocking ferroptosis, and ferritinophagy may be a potential therapeutic direction for the prevention and treatment of beryllium disease.

[Inhibition of GMA-induced ubiquitination process in 16HBE malignantly transformed cells on protein CD44 and MMP14].

OBJECTIVE: To observe the effect of the ubiquitination process on the expression of CD44 antigen(CD44) and matrix metalloproteinase-14(MMP14) in human bronchial epithelial(16HBE) malignantly transformed cells induced by glycidyl methacrylate(GMA). METHODS: Successfully resuscitated 16HBE cells were cultured using a final concentration of 8 µg/mL GMA as the treatment group and 1 µg/mL dimethyl sulfoxide as the solvent control group, each time stained for 72 h, and then stained again after an interval of 24 h. After repeating the staining three times, the cells were cultured in passages respectively. The 40th generation(P40) GMA-treated group and the same-generation solvent control group were subjected to soft agar colony formation assay and concanavalin A(ConA) agglutination test to confirm that the 40th generation of GMA-induced malignant transformed 16HBE cells possessed malignant transformed cell characteristics.5, 10, 20, 40, 60 µmol/L anacardic acid were used to inhibit the ubiquitination process of GMA-induced malignant transformed 16HBE cells. The protein expression of CD44 and MMP14 were detected by western blotting, while the transcript levels of CD44, MMP14, and TFAP2A were assessed by real-time fluorescence quantitative PCR(qPCR). RESULTS: (1) In the soft agar colony formation assay, the number of clones formed by the cells in the solvent control group was 22, and the number of clones created by the malignantly transformed cells in the GMA-treated group was 208. In the ConA agglutination test, the cells in the solvent control group were uniformly dispersed in ConA solution, and no obvious agglutination occurred for 30 min, whereas the cells in the GMA-treated group were agglutinated in the 5th min, and the agglutinated cells were larger and more rapidly agglutinated. The agglomerates were more significant and faster, and the sensitivity of agglutination was increased. (2) After differential inhibition of GMA-induced ubiquitination in malignantly transformed 16HBE cells, the expression levels of CD44 and MMP14 were reduced in GMA-induced malignantly transformed 16HBE cells compared with the control group(P<0.05). The transcript levels of MMP14 and CD44 decreased with increasing inhibitor concentration(P<0.05), and the transcript levels of the upstream transcription factor TFAP2A were also simultaneously reduced(P<0.05). CONCLUSION: Inhibition of the cellular ubiquitination process mediates the down-regulation of protein expression and transcriptional expression of CD44 and MMP14 in GMA-induced malignantly transformed 16HBE cells.

Repeated exposure of bronchial epithelial cells to particular matter increases allergen-induced cytokine release and permeability.

Long term particulate matter (PM) exposure has been associated with an increased incidence of respiratory diseases. Here, an in vitro model was developed to study how long term diesel exhaust particle (DEP) exposure might predispose to the development of allergic reactions. Airway epithelial (16HBE) cells were exposed to low concentrations of diesel exhaust particle (DEP) for 4 days after which they were challenged with house dust mite (HDM) extract (24 h). Compared to acute exposure (24 h), 4 days DEP exposure to 16HBE cells further reduced the transepithelial electrical resistance (TEER) and increased CXCL-8 release. DEP pre-exposure aggravated HDM-induced loss of TEER, increased tracer flux across the barrier and reduced CLDN-3 expression in these 16HBE cells. HDM-induced cytokine (IL-6, CCL-22, IL-10 and CXCL-8) release was significantly increased after DEP pre-exposure. In the current study an in vitro model with long term PM exposure was presented, which might be helpful for further understanding the interplay between long term PM exposure and allergic responses.

Knockdown of circ_0038467 alleviates lipopolysaccharides-induced 16HBE cell injury by regulating the miR-545-3p/TRAF1 axis in neonatal pneumonia.

BACKGROUND: Neonatal pneumonia is a common illness in the neonatal period with a high fatality rate. Accumulating proofs have attested to the crucial role of circular RNAs (circRNAs) in pneumonia. This study was intended to expound on the function of circ_0038467 and the underlying mechanism in lipopolysaccharide (LPS)-stimulated 16HBE cell injury in neonatal pneumonia. METHODS: 16HBE cells were exposed to LPS to establish an in vitro neonatal pneumonia cell model. Quantitative real-time polymerase chain reaction (qRT-PCR) was implemented for detecting the levels of circ_0038467, microRNA-545-3p (miR-545-3p), and tumor necrosis factor receptor-associated factor 1 (TRAF1) in neonatal pneumonia serums and LPS-treated 16HBE cells. Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and flow cytometry assays were used to examine cell viability, proliferation, and apoptosis, respectively. The protein abundances of proliferation/apoptosis/inflammation-correlated makers and TRAF1 were tested by Western blot. RNase R and Actinomycin D assays were implemented to determine the features of circ_0038467. The mutual effect between miR-545-3p and circ_0038467 or TRAF1 was affirmed by a dual-luciferase reporter and RNA pull-down assay assays. RESULTS: Circ_0038467 was upregulated in neonatal pneumonia serum specimens and LPS-triggered 16HBE cells. LPS administration restrained 16HBE cell proliferation and promoted apoptosis and inflammation, whereas circ_0038467 silence recovered these influences. Meanwhile, miR-545-3p was targeted by circ_0038467, and circ_0038467 could modulate LPS-treated 16HBE cell injury through absorbing miR-545-3p. Furthermore, circ_0038467 controlled TRAF1 level via segregating miR-545-3p. Moreover, TRAF1 overexpression relieved the suppressive impact of circ_0038467 silence in LPS-triggered 16HBE cell detriment. CONCLUSION: Circ_0038467 knockdown mitigated LPS-exposed 16HBE cell damage through regulating miR-545-3p/PPARA axis.

Whole transcriptome analysis of long noncoding RNA in beryllium sulfate-treated 16HBE cells.

Beryllium and its compounds can cause pulmonary interstitial fibrosis through mechanisms that are not yet clear. Long non-coding RNA (lncRNA) is implicated in various diseases. The molecular toxicity of beryllium sulfate (BeSO4) was investigated through the RNA-seq analysis of the lncRNA and mRNA whole-transcriptome of BeSO4-treated 16HBE cells. A total of 1014 lncRNAs (535 upregulated and 479 downregulated) and 4035 mRNAs (2224 upregulated and 1811 downregulated) were found to be significantly dysregulated (|logFC| ≥> 2.0, p < 0.05) in the BeSO4-treated groups when compared with the control group. Five differentially expressed lncRNAs and mRNAs were verified by qRT-PCR. KEGG analysis showed that lncRNA regulates the ECM receiver interaction and PI3K/AKT signaling pathways, etc. In addition, H19:17, lnc-C5orf13-1:1, lnc-CRYAA-17:1, lnc-VSTM5-1:11, and lnc-THSD7A-7:1 may regulate BeSO4-induced 16HBE cytotoxicity through ceRNA mechanism. The results of this study will provide some theoretical support for the study of the toxic mechanism of beryllium and its compounds.

Hydrogen sulfide alleviates apoptosis and autophagy induced by beryllium sulfate in 16HBE cells.

Beryllium and its compounds are systemic toxicants that are widely applied in many industries. Hydrogen sulfide has been found to protect cells. The present study aimed to determine the protective mechanisms involved in hydrogen sulfide treatment of 16HBE cells following beryllium sulfate-induced injury. 16HBE cells were treated with beryllium sulfate doses ranging between 0 and 300 µM BeSO4 . Additionally, 16HBE cells were subjected to pretreatment with either a 300 µM dose of sodium hydrosulfide (a hydrogen sulfide donor) or 10 mM DL-propargylglycine (a cystathionine-γ-lyase inhibitor) for 6 hr before then being treated with 150 µM beryllium sulfate for 48 hr. This study illustrates that beryllium sulfate induces a reduction in cell viability, increases lactate dehydrogenase (LDH) release, and increases cellular apoptosis and autophagy in 16HBE cells. Interestingly, pretreating 16HBE cells with sodium hydrosulfide significantly reduced the beryllium sulfate-induced apoptosis and autophagy. Moreover, it increased the mitochondrial membrane potential and alleviated the G2/M-phase cell cycle arrest. However, pretreatment with 10 mM DL-propargylglycine promoted the opposite effects. PI3K/Akt/mTOR and Nrf2/ARE signaling pathways are also activated following pretreatment with sodium hydrosulfide. These results indicate the protection provided by hydrogen sulfide in 16HBE cells against beryllium sulfate-induced injury is associated with the inhibition of apoptosis and autophagy through the activation of the PI3K/Akt/mTOR and Nrf2/ARE signaling pathways. Therefore, hydrogen sulfide has the potential to be a promising candidate in the treatment against beryllium disease.

Streptococcus strain C17T as a potential probiotic candidate to modulate oral health.

In the microbiome, probiotics modulate oral diseases. In this study, Streptococcus strain C17T was isolated from the oropharynx of a 5-year-old healthy child, and its potential probiotic properties were analysed using human bronchial epithelial cells (16-HBE) used as an in vitro oropharyngeal mucosal model. The results demonstrated that the C17T strain showed tolerance to moderate pH ranges of 4-5 and 0·5-1% bile. However, it was more tolerant to 0·5% bile than 1% bile. It also demonstrated an ability to accommodate maladaptive oropharyngeal conditions (i.e. tolerating lysozyme at 200 µg ml-1 ). It was also resistant to hydrogen peroxide at 0·8 mM. In addition, we found out that the strain possesses inhibitory activities against various common pathogenic bacteria. Furthermore, C17T was not cytotoxic to 16-HBE cells at different multiplicities of infection. Scanning electron microscopy disclosed that C17T adhesion to 16-HBE cells. Competition, exclusion and displacement assays showed that it had good anti-adhesive effect against S. aureus. The present study revealed that Streptococcus strain C17T is a potentially efficacious oropharyngeal probiotic.

Potent necrosis effect of methanethiol mediated by METTL7B enzyme bioactivation mechanism in 16HBE cell.

Methanethiol is a widely existing malodorous pollutant with health effects on the human population. However, the cytotoxicity mechanism of methanethiol in vitro and its metabolic transformation (bioactivation or detoxification) have not been fully elucidated. Herein, the metabolites of methanethiol during cell culture and the cytotoxicity of methanethiol in human bronchial epithelial (16HBE) cells were investigated. Results indicate that methanethiol (10-50 µM) was partially converted into dimethyl sulfide, mainly catalyzed by thiol S-methyltransferase in the 16HBE cells, and then it induced potent cytotoxicity and cell membrane permeability. Moreover, methanethiol induced intracellular reactive oxygen species (ROS) up to 50 µM and further activated the tumor necrosis factor (TNF) signaling pathway, which eventually led to the decline in the mitochondrial membrane potential (MMP) and cell necrosis. However, all these effects were significantly alleviated with gene silencing of the methyltransferase-like protein 7B (METTL7B). These results indicate that methanethiol may induce cell necrosis in human respiratory tract cells mainly mediated by S-methyltransferase with interfering TNF and ROS induction. Non-target metabolomics results suggest that methanethiol potently affects expression of endogenous small molecule metabolites in 16HBE cells. To some extent, this work shows the possible conversion path and potential injury mechanism of human respiratory tract cells exposed to methanethiol.

The expression profile and bioinformatics analysis of microRNAs in human bronchial epithelial cells treated by beryllium sulfate.

Beryllium and its compounds are systemic toxicants that mainly accumulate in the lungs. As a regulator of gene expression, microRNAs (miRNAs) were involved in some lung diseases. This study aimed to analyze the levels of some inflammatory cytokine and the differential expressions of miRNAs in human bronchial epithelial cells (16HBE) induced by beryllium sulfate (BeSO4 ) and to further explore the biological functions of differentially expressed miRNAs. The profile of miRNAs in 16HBE cells was detected using the high-throughput sequencing between the control groups (n = 3) and the 150 µmol/L of BeSO4 -treated groups (n = 3). Bioinformatics analysis of differentially expressed miRNAs was performed, including the prediction of target genes, Gene Ontology (GO) analysis, and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to verify some damage-related miRNAs. We found that BeSO4 can increase the levels of some inflammatory cytokine such as interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), interferon-γ (IFN-γ), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). And BeSO4 altered miRNAs expression of 16HBE cells and a total of 179 differentially expressed miRNAs were identified, including 88 upregulated miRNAs and 91 downregulated miRNAs. The target genes predicted by 28 dysregulated miRNAs were mainly involved in the transcription regulation, signal transduction, MAPK, and VEGF signaling pathway. The qRT-PCR verification results were consistent with the sequencing results. miRNA expression profiling in 16HBE cells exposed to BeSO4 provides new insights into the toxicity mechanism of beryllium exposure.

Expression of long non-coding RNA LUCAT1 in patients with chronic obstructive pulmonary disease and its potential functions in regulating cigarette smoke extract-induced 16HBE cell proliferation and apoptosis.

BACKGROUND: Chronic obstructive pulmonary disease (COPD), characterized by persistent airflow limitation, was a disease mediated by a combination of inflammatory factors, immune cells, and immune mediators. COPD was an inflammatory and autoimmune disease involving T-lymphocytes triggered by cigarette smoke and other factors that progressively affected the bronchi, lung parenchyma, and pulmonary blood vessels. LncRNAs were reported to be implicated in COPD pathogenesis and development. METHODS: Non-smokers, smokers (non-COPD), and COPD patients were randomly selected in an established COPD surveillance cohort. Demographic and clinical information of all subjects were collected. Pulmonary function was measured by post-bronchodilator testing. qRT-PCR and ELISA assays were performed to detect the expression levels of lncRNA LUCAT1, miR-181a-5p, and inflammatory cytokines. An in vitro exposure model was constructed using cigarette smoke extract (CSE)-induced human bronchial epithelial (16HBE) cells. The dual-luciferase reporter and RNA pull-down assays were used to detect the binding relationship between lncRNA LUCAT1 and miR-181a-5p; meanwhile, Spearman's correlation assay was used to verify the correlation between lncRNA LUCAT1 and miR-181a-5p. Afterward, the lncRNA LUCAT1 silencing plasmid was constructed and co-transfected with a miR-181a-5p inhibitor to evaluate the effects on CSE-induced 16HBE cell proliferation and apoptosis. Finally, a Western blot assay was utilized to determine the mechanism of lncRNA LUCAT1/miR-181a-5p/Wnt/ß-catenin axis in COPD. RESULTS: LncRNA LUCAT1 was upregulated in the serums of COPD patients. Correlation analysis further confirmed the strong correlation between LUCAT1 expression and inflammatory cytokines IL-1ß, IL-6, and TNF-α. Receiver operating characteristic (ROC) analysis verified the potential of LUCAT1 in COPD diagnosis. After treatment with CSE, LUCAT1 was significantly increased while its target miR-181a-5p was decreased in 16HBE cells. Cell proliferation and apoptosis assays showed that LUCAT1 silencing alleviated CSE's effects on 16HBE cell proliferation and apoptosis. Mechanically, rescue assays demonstrated that miR-181a-5p inhibition could partially counteract the impact of LUCAT1 on COPD progression through the Wnt/ß-catenin pathway. CONCLUSIONS: LncRNA LUCAT1 may be a valuable indicator for differentiating COPD. Moreover, LncRNA LUCAT1/miR-181-5p/Wnt/ß-catenin axis behaved as a critical role in COPD development, shedding new sights for clinical treatment.

Long non-coding RNA MEG3 regulates CSE-induced apoptosis and inflammation via regulating miR-218 in 16HBE cells.

Chronic obstructive pulmonary disease (COPD) is a prevalent disease worldwide, mainly caused by cigarette smoking. Maternally expressed gene 3 (MEG3) functions as the lncRNA and is upregulated in COPD patients and human bronchial epithelial cells after fine particulate matter (PM2.5) treatment. However, the molecular mechanism of MEG3 in COPD remains unknown. The expression of MEG3 and miR-218 in COPD tissues and cigarette smoke extract (CSE)-treated 16HBE cells was detected by RT-qPCR. The effects of MEG3 and miR-218 on proliferation and apoptosis in (CSE)-treated 16HBE cells were analyzed by CCK-8 and flow cytometry assay, respectively. The protein levels of inflammatory cytokines (IL-1ß IL-6 and TNF-α) were detected in 16HBE cells by ELISA. MEG3 and miR-218 binding interaction was predicted by LncBase Predicted v.2 and further confirmed by dual luciferase reporter assay and RNA Immunoprecipitation (RIP) assay. MEG3 was upregulated in COPD tissues and inversely related to FEV1%. MEG3 was upregulated in (CSE)-treated 16HBE cells, and knockdown of MEG3 mitigated CSE-repressed proliferation and CSE-triggered apoptosis or inflammation. MiR-218 was demonstrated as a target miRNA of MEG3. MiR-218 was downregulated in COPD tissues and (CSE)-treated or MEG3 overexpressed 16HBE cells. MiR-218 overexpression attenuated CSE-blocked proliferation and CSE-induced apoptosis or inflammation. Deficiency of MEG3 counteracted CSE-blocked proliferation CSE-induced apoptotic rate and inflammatory cytokine (IL-1ß IL-6 and TNF-α) levels, while introduction of anti-miR-218 reversed these effects. MEG3 regulated CSE-inhibited proliferation and CSE-induced apoptosis or inflammation by targeting miR-218, providing a possible therapeutic target for treatment of CSE-induced COPD.

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.

Atractylenolide III reduces NLRP3 inflammasome activation and Th1/Th2 imbalances in both in vitro and in vivo models of asthma.

Paediatric asthma is a common inflammatory disease in children. Atractylenolide III is an active component of the Atractylodes rhizome, an herbal medicine that has been used as an asthma treatment. This study aimed to explore the effects and underlying mechanisms of atractylenolide III in IL-4-induced 16HBE cells and ovalbumin-induced asthmatic mice. The results showed that IL-4 stimulation significantly decreased, and atractylenolide III treatment increased, growth and apoptosis of 16HBE cells. In 16HBE cells, administration of atractylenolide III also significantly suppressed the IL-4-induced increases in the expression of cleaved caspase-1; apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC); and nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3). Moreover, the numbers of total leukocytes, neutrophils, eosinophils, and macrophages significantly increased in ovalbumin-induced mice, and then decreased after atractylenolide III treatment. In ovalbumin-induced asthmatic mice, atractylenolide III treatment also significantly inhibited NLRP3 inflammasome activation and restored the Th1/Th2 balance. These results indicate that atractylenolide III reduced NLRP3 inflammasome activation and regulated the Th1/Th2 balance in IL-4 induced 16HBE cells and ovalbumin-induced asthmatic mice, suggesting it has a protective effect that may be useful in the treatment of paediatric asthma.

Carbon black nanoparticles induce HDAC6-mediated inflammatory responses in 16HBE cells.

Long-term inhalation of carbon black nanoparticles (CBNPs) leads to pulmonary inflammatory diseases. Histone deacetylase 6 (HDAC6) has been identified as an important regulator in the development of inflammatory disorders. However, the direct involvement of HDAC6 in CBNPs-induced pulmonary inflammatory responses remains unclear. To explore whether HDAC6 participates in CBNPs-induced pulmonary inflammation, human bronchial epithelial cell line (16HBE cells) was transfected with HDAC6 small interference RNA (siRNA) and then exposed to CBNPs at concentrations of 0, 25, and 50 µg/ml for 24 h. Intracellular HDAC6 and intraflagellar transport protein 88 (IFT88) mRNA and protein were determined by real-time polymerase chain reaction and Western blot, respectively. The secretions of inflammatory cytokines including interleukin (IL)-8, tumor necrosis factor (TNF)-α, IL-6, and IL-1ß were measured by enzyme-linked immunosorbent assay. CBNPs induced a significant increase in the expressions of IL-8 and IL-6, accompanied by a high level of intracellular HDAC6 mRNA when compared with a blank control group (p < 0.05). However, there were no significant changes in the levels of TNF-α secretion, intracellular HDAC6 and IFT88 protein induced by CBNPs (p > 0.05). The HDAC6 mRNA expression was significantly suppressed in HDAC6 siRNA-transfected cells (p < 0.05). The secretions of IL-8, TNF-α, and IL-6 were significantly less in HDAC6 siRNA-transfected cells than that in normal 16HBE cells with exposure to 25 or 50 µg/ml of CBNPs, but intracellular IFT88 mRNA expression was markedly increased in HDAC6 siRNA-transfected cells when compared with normal 16HBE cells exposed to 50 µg/ml of CBNPs (all p < 0.05). Downregulation of the HDAC6 gene inhibits CBNPs-induced inflammatory responses in bronchial epithelial cells, partially through regulating IFT88 expression. It is suggested that CBNPs may trigger inflammatory responses in bronchial epithelial cells by an HDAC6/IFT88-dependent pathway.

CXCL16/CXCR6 is involved in LPS-induced acute lung injury via P38 signalling.

Although several chemokines play key roles in the pathogenesis of acute lung injury (ALI), the roles of chemokine (C-X-C motif) ligand 16 (CXCL16) and its receptor C-X-C chemokine receptor type 6 (CXCR6) in ALI pathogenesis remain to be elucidated. The mRNA and protein expression of CXCL16 and CXCR6 was detected after lipopolysaccharide (LPS) stimulation with or without treatment with the nuclear factor-κB (NF-κB) inhibitor pyrrolidine dithiocarbamate (PDTC). Lung injury induced by LPS was evaluated in CXCR6 knockout mice. CXCL16 level was elevated in the serum of ALI patients (n = 20) compared with healthy controls (n = 30). CXCL16 treatment (50, 100, and 200 ng/mL) in 16HBE cells significantly decreased the epithelial barrier integrity and E-cadherin expression, and increased CXCR6 expression, reactive oxygen species (ROS) production, and p38 phosphorylation. Knockdown of CXCR6 or treatment with the p38 inhibitor SB203580 abolished the effects of CXCL16. Moreover, treatment of 16HBE cells with LPS (5, 10, 20 and 50 µg/mL) significantly increased CXCL16 release as well as the mRNA and protein levels of CXCL16 and CXCR6. The effects of LPS treatment (20 µg/mL) were abolished by treatment with PDTC. The results of the luciferase assay further demonstrated that PDTC treatment markedly inhibited the activity of the CXCL16 promoter. In conclusion, CXCL16, whose transcription was enhanced by LPS, may be involved in ROS production, epithelial barrier dysfunction and E-cadherin down-regulation via p38 signalling, thus contributing to the pathogenesis of ALI. Importantly, CXCR6 knockout or inhibition of p38 signalling may protect mice from LPS-induced lung injury by decreasing E-cadherin expression.

Protein carbonylation in human bronchial epithelial cells exposed to cigarette smoke extract.

Cigarette smoke is a well-established exogenous risk factor containing toxic reactive molecules able to induce oxidative stress, which in turn contributes to smoking-related diseases, including cardiovascular, pulmonary, and oral cavity diseases. We investigated the effects of cigarette smoke extract on human bronchial epithelial cells. Cells were exposed to various concentrations (2.5-5-10-20%) of cigarette smoke extract for 1, 3, and 24 h. Carbonylation was assessed by 2,4-dinitrophenylhydrazine using both immunocytochemical and Western immunoblotting assays. Cigarette smoke induced increasing protein carbonylation in a concentration-dependent manner. The main carbonylated proteins were identified by means of two-dimensional electrophoresis coupled to MALDI-TOF mass spectrometry analysis and database search (redox proteomics). We demonstrated that exposure of bronchial cells to cigarette smoke extract induces carbonylation of a large number of proteins distributed throughout the cell. Proteins undergoing carbonylation are involved in primary metabolic processes, such as protein and lipid metabolism and metabolite and energy production as well as in fundamental cellular processes, such as cell cycle and chromosome segregation, thus confirming that reactive carbonyl species contained in cigarette smoke markedly alter cell homeostasis and functions.

Evaluation of in vitro toxicity of silica nanoparticles (NPs) to lung cells: Influence of cell types and pulmonary surfactant component DPPC.

Cultured human lung epithelial cells, particularly A549 cells, are commonly used as the in vitro model to evaluate the inhalational toxicity of nanoparticles (NPs). However, A549 cells are cancer cells that might not reflect the response of normal tissues to NP exposure. In addition, the possible influence of pulmonary surfactant also should be considered. This study used silica NPs as model NPs, and evaluated the toxicity of silica NPs to both 16HBE human bronchial epithelial cells and A549 adenocarcinomic cells, with or without the presence of pulmonary surfactant component dipalmitoyl phosphatidylcholine (DPPC). We found that silica NPs induced cytotoxicity at the concentration of 128 µg/mL in 16HBE cells but not A5490 cells, and the cytotoxicity of silica NPs to 16HBE cells was inhibited by DPPC. Intracellular reactive oxygen species (ROS) was only induced in 16HBE cells, accompanying with decreased thiol levels. Moreover, 16HBE cells internalized more silica NPs compared with A549 cells, and the internalization was reduced with the presence of DPPC in both types of cells. The retention of ABC transporter substrate Calcein was only significantly induced by silica NPs at high concentrations in 16HBE cells, and was partially reduced due to the presence of DPPC. In addition, ABC transporter inhibitor MK571 increased the toxicity of silica NPs to both types of cells, with 16HBE cells being more sensitive. Our data revealed that the cell types and pulmonary surfactant components could influence the toxicological consequences of silica NPs to human lung cells. Therefore, it is recommended that in vitro studies should carefully select suitable models to evaluate the inhalational toxicity of NPs.

[Analysis of the potential role of SET in chromium-induced malignant transformation cells based on quantitative proteomics].

Objective: To investigate alteration of proteins profile in malignant transformation bronchial epithelial cells(16HBE-T) induced by hexavalent chromium[(Cr(VI))] and analyze the expression level of SET protein, then to provide some new insights for the carcinogenesis mechanism of Cr(VI). Methods: Total protein was extracted from 16HBE cells and was alkylated and desalinated before digested into peptides. The products were labeled with Tandem Mass Tag (TMT) and identified using LC-ESI-MS/MS. Results: A total of 3 517 proteins were found, expression differences greater than 1.5 or less 0.67 times were to found have 185 and 201 proteins, respectively. Gene enrichment analysis revealed that differential proteins were mainly involved in autophagy, DNA damage repair, RNA processing and other biological processes. Western blot results showed the expression level of SET was significantly increased while downregulated in histone H3K18/27 acetylation and p53 protein. Conclusion: Proteins involved in multiple biological processes altered in 16HBE-T cells and regulation mode of SET inhibiting histone H3K18/27 acetylation regulating transcriptional activity of p53 may paly an important role in Cr(VI)-association carcinogenesis.