Cigarette smoke and its component acrolein augment IL-8/CXCL8 mRNA stability via p38 MAPK/MK2 signaling in human pulmonary cells

Interleukin-8 (IL-8/CXCL8) is an important neutrophil chemoattractant known to be elevated in the airways of cigarette smokers and in patients with chronic obstructive pulmonary disease (COPD). We examined the acute effect of aqueous cigarette smoke extract (CSE) on IL-8 expression in primary human pulmonary cells, in particular in normal human bronchial smooth muscle cells (HBSMCs). IL-8 mRNA levels increased upon CSE exposure in a concentration- and time-dependent manner, and such an effect was accompanied by IL-8 secretion. CSE-evoked elevation of IL-8 mRNA was mimicked by its component acrolein. Both CSE and acrolein induced p38 mitogen-activated protein kinase (MAPK) phosphorylation, accompanied by the phosphorylation of MAPK-activated kinase 2 (MK2), a known downstream substrate of the p38 MAPK, both in HBSMCs and in human airway epithelial cells. Furthermore, pharmacological inhibition of p38 MAPK or MK2 strongly accelerated the decay of IL-8 mRNA levels upon stimulation with CSE or acrolein and subsequent blockade of mRNA neosynthesis with actinomycin D in pulmonary structural cells (HBSMCs and airways epithelial cells) as well as in human alveolar macrophages. Conversely, pharmacological inhibition of ERK1/2 signaling inhibited CSE-induced steady-state levels of IL-8 mRNA without affecting mRNA stability, thus suggesting inhibition at the transcriptional level. In sum, p38 MAPK/MK2 signaling is an important posttranscriptional mechanism underlying upregulation of IL-8 mRNA levels elicited by CSE and acrolein. Given the pivotal role of IL-8 in neutrophil chemotaxis and activation, our results shed light on the mechanisms through which cigarette smoke can initiate inflammation in the lung.

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TLR5-mediated activation of p38 MAPK regulates epithelial IL-8 expression via posttranscriptional mechanism

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00503.2002 ◽

2003 ◽

Vol 285 (2) ◽

pp. G282-G290 ◽

Cited By ~ 85

Author(s):

Yimin Yu ◽

Hui Zeng ◽

Sean Lyons ◽

Adam Carlson ◽

Didier Merlin ◽

...

Keyword(s):

P38 Mapk ◽

Mrna Stability ◽

Mrna Translation ◽

Mrna Levels ◽

Dependent Manner ◽

Maximal Inhibition ◽

Mapk Activation ◽

Intestinal Epithelia ◽

Tnf Α ◽

Sb 203580

Toll-like receptors (TLRs) activate antimicrobial gene expression in response to detection of specific bacterial products. Relatively little is known about TLR5, the only TLR thought to be preferentially expressed by epithelial cells, beyond that it confers activation of the transcription factor NF-κB in a MyD-88 dependent manner in response to flagellin. Because TLRs, in general, are also thought to signal through members of the MAPK family, we examined flagellin-induced MAPK activation (via examining its phosphorylation status) and its subsequent role in expression of the chemokine IL-8 in polarized intestinal epithelia. Flagellin, like other proinflammatory stimuli (TNF-α, Salmonella typhimurium), activated p38 MAPK in a TLR5-dependent manner, whereas aflagellate bacteria or EGF did not activate this kinase. Although ERK1 and -2 were also observed to be activated in response to flagellin, their activation was not restricted to proinflammatory stimuli because they were also potently activated by aflagellate bacteria ( S. typhimurium or Escherichia coli) and EGF (neither of which activate NF-κB in these cells). Pharmacological inhibition of p38 MAPK (by SB-203580) potently (IC50 = 10 nM) reduced expression of IL-8 protein (maximal inhibition, 75%) but had no effect on NF-κB activation, only slightly attenuated upregulation of IL-8 mRNA levels in response to flagellin, and did not effect IL-8 mRNA stability. Together, these results indicate that epithelial TLR5 mediates p38 activation and subsequently regulates flagellin-induced IL-8 expression independently of NF-κB, probably by influencing IL-8 mRNA translation.

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Mechanism of dexamethasone-mediated interleukin-8 gene suppression in cultured airway epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2001.280.1.l107 ◽

2001 ◽

Vol 280 (1) ◽

pp. L107-L115 ◽

Cited By ~ 36

Author(s):

Mary Mann-Jong Chang ◽

Maya Juarez ◽

Dallas M. Hyde ◽

Reen Wu

Keyword(s):

Gene Expression ◽

Protein Synthesis ◽

Epithelial Cells ◽

Actinomycin D ◽

Airway Epithelial Cells ◽

Interleukin 8 ◽

Transcriptional Level ◽

Dependent Manner ◽

Airway Epithelial ◽

New Protein

The effects of dexamethasone, a glucocorticoid analog, on interleukin 8 (IL-8) gene expression were studied in cultures of primary human tracheobronchial epithelial cells and an immortalized human bronchial epithelial cell line, HBE1 cells. Dexamethasone inhibited IL-8 mRNA and protein expression in a concentration- and time-dependent manner. The inhibition did not occur at the transcriptional level since both nuclear run-on activity and IL-8 promoter-reporter gene expression assay revealed no significant effect. Instead, there was a change in IL-8 mRNA stability in dexamethasone-treated cultures. Under actinomycin D treatment, IL-8 mRNA was quite stable in dexamethasone-depleted cultures, while in dexamethasone-pretreated cultures, IL-8 message was rapidly degraded within the first hour, then leveled off. When dexamethasone and actinomycin D were added simultaneously to dexamethasone-depleted cultures, IL-8 mRNA remained rather stable. When cycloheximide was used to inhibit new protein synthesis, dexamethasone-dependent inhibition was not observed. These results suggest that a posttranscriptional mechanism, which requires dexamethasone-dependent new protein synthesis, is involved in the regulation of IL-8 mRNA by dexamethasone in airway epithelial cells.

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Down-regulation of Cytokine-induced Interleukin-8 Requires Inhibition of p38 Mitogen-activated Protein Kinase (MAPK) via MAPK Phosphatase 1-dependent and -independent Mechanisms

Journal of Biological Chemistry ◽

10.1074/jbc.m110.205724 ◽

2011 ◽

Vol 286 (18) ◽

pp. 15998-16007 ◽

Cited By ~ 25

Author(s):

Nurlan Dauletbaev ◽

Daniel Eklove ◽

Nadir Mawji ◽

Michele Iskandar ◽

Sergio Di Marco ◽

...

Keyword(s):

Protein Kinase ◽

Epithelial Cells ◽

P38 Mapk ◽

Mrna Stability ◽

Airway Epithelial Cells ◽

Mitogen Activated Protein Kinase ◽

Airway Epithelial ◽

Down Regulation ◽

Mitogen Activated Protein ◽

Mapk Phosphatase

Down-regulation of overabundant interleukin (IL)-8 present in cystic fibrosis (CF) airways could ease excessive neutrophil burden and its deleterious consequences for the lung. IL-8 production in airway epithelial cells, stimulated with e.g. inflammatory cytokines IL-1β and tumor necrosis factor (TNF)-α, is regulated by several signaling pathways including nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). We previously demonstrated that the anti-inflammatory drugs dexamethasone and ibuprofen suppress NF-κB; however, only dexamethasone down-regulates cytokine-induced IL-8, highlighting the importance of non-NF-κB mechanisms. Here, we tested the hypothesis that down-regulation of cytokine-induced IL-8 requires modulation of the MAPK phosphatase (MKP)-1/p38 MAPK/mRNA stability pathway. The effects of dexamethasone (5 nm) and ibuprofen (480 μm) on this pathway and IL-8 were studied in CF (CFTE29o−, CFBE41o−) and non-CF (1HAEo−) airway epithelial cells. We observed that dexamethasone, but not ibuprofen, destabilizes IL-8 mRNA and up-regulates MKP-1 mRNA. Further, siRNA silencing of MKP-1, via p38 MAPK, leads to IL-8 overproduction and diminishes the anti-IL-8 potential of dexamethasone. However, MKP-1 overexpression does not significantly alter IL-8 production. By contrast, direct inhibition of p38 MAPK (inhibitor SB203580) efficiently suppresses IL-8 with potency comparable with dexamethasone. Similar to dexamethasone, SB203580 decreases IL-8 mRNA stability. Dexamethasone does not affect p38 MAPK activation, which excludes its effects upstream of p38 MAPK. In conclusion, normal levels of MKP-1 are necessary for a full anti-IL-8 potential of pharmacological agents; however, efficient pharmacological down-regulation of cytokine-induced IL-8 also requires direct effects on p38 MAPK and mRNA stability independently of MKP-1.

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TNF-α inhibits SP-A gene expression in lung epithelial cells via p38 MAPK

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00470.2001 ◽

2002 ◽

Vol 283 (2) ◽

pp. L418-L427 ◽

Cited By ~ 25

Author(s):

Olga L. Miakotina ◽

Jeanne M. Snyder

Keyword(s):

Gene Expression ◽

Epithelial Cells ◽

P38 Mapk ◽

Mapk Pathway ◽

Lung Epithelial Cells ◽

Mitogen Activated Protein Kinase ◽

Mrna Levels ◽

Dependent Manner ◽

Tnf Α ◽

Lung Epithelial

Surfactant protein A (SP-A), the major lung surfactant-associated protein, mediates local defense against pathogens and modulates inflammation in the alveolus. Tumor necrosis factor (TNF)-α, a proinflammatory cytokine, inhibits SP-A gene expression in lung epithelial cells. Inhibitors of the phosphatidylinositol 3-kinase pathway, i.e., wortmannin, LY-294002, and rapamycin, did not block the inhibitory effects of TNF-α on SP-A mRNA levels. An inhibitor of the p44/42 mitogen-activated protein kinase (MAPK) pathway, PD-98059, was also ineffective. PD-169316 and SB-203580, inhibitors of p38 MAPK, blocked the TNF-α-mediated inhibition of SP-A mRNA levels. TNF-α increased the phosphorylation of p38 MAPK within 15 min. Anisomycin, an activator of p38 MAPK, increased p38 MAPK phosphorylation and decreased SP-A mRNA levels in a dose-dependent manner. Finally, TNF-α increased the phosphorylation of ATF-2, a transcription factor that is a p38 MAPK substrate. We conclude that TNF-α downregulates SP-A gene expression in lung epithelial cells via the p38 MAPK signal transduction pathway.

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Endotoxin-Induced Tissue Factor in Human Monocytes is Dependent upon Protein Kinase C Activation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649673 ◽

1993 ◽

Vol 70 (05) ◽

pp. 800-806 ◽

Cited By ~ 29

Author(s):

C Ternisien ◽

M Ramani ◽

V Ollivier ◽

F Khechai ◽

T Vu ◽

...

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Tissue Factor ◽

Factor Ix ◽

Transcriptional Level ◽

Mrna Levels ◽

Dependent Manner ◽

Human Monocytes ◽

Kinase C ◽

Pkc Activation

SummaryTissue factor (TF) is a transmembrane receptor which, in association with factors VII and Vila, activates factor IX and X, thereby activating the coagulation protease cascades. In response to bacterial lipopolysaccharide (LPS) monocytes transcribe, synthesize and express TF on their surface. We investigated whether LPS-induced TF in human monocytes is mediated by protein kinase C (PKC) activation. The PKC agonists phorbol 12- myristate 13-acetate (PMA) and phorbol 12, 13 dibutyrate (PdBu) were both potent inducers of TF in human monocytes, whereas 4 alpha-12, 13 didecanoate (4 a-Pdd) had no such effect. Both LPS- and PMA-induced TF activity were inhibited, in a concentration dependent manner, by three different PKC inhibitors: H7, staurosporine and calphostin C. TF antigen determination confirmed that LPS-induced cell-surface TF protein levels decreased in parallel to TF functional activity under staurosporine treatment. Moreover, Northern blot analysis of total RNA from LPS- or PMA-stimulated monocytes showed a concentration-dependent decrease in TF mRNA levels in response to H7 and staurosporine. The decay rate of LPS-induced TF mRNA evaluated after the arrest of transcription by actinomycin D was not affected by the addition of staurosporine, suggesting that its inhibitory effect occurred at a transcriptional level. We conclude that LPS-induced production of TF and its mRNA by human monocytes are dependent on PKC activation.

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Cigarette Smoke Stimulates SARS-CoV-2 Internalization by Activating AhR and Increasing ACE2 Expression in Human Gingival Epithelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms22147669 ◽

2021 ◽

Vol 22 (14) ◽

pp. 7669

Author(s):

Cassio Luiz Coutinho Almeida-da-Silva ◽

Harmony Matshik Dakafay ◽

Kaitlyn Liu ◽

David M. Ojcius

Keyword(s):

Epithelial Cells ◽

Oral Cavity ◽

Cigarette Smoke ◽

Large Body ◽

Receptor Expression ◽

Host Cells ◽

Dependent Manner ◽

Gingival Epithelial Cells ◽

Human Gingival Epithelial Cells ◽

Oral Cells

A large body of evidence shows the harmful effects of cigarette smoke to oral and systemic health. More recently, a link between smoking and susceptibility to coronavirus disease 2019 (COVID-19) was proposed. COVID-19 is due to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which uses the receptor ACE2 and the protease TMPRSS2 for entry into host cells, thereby infecting cells of the respiratory tract and the oral cavity. Here, we examined the effects of cigarette smoke on the expression of SARS-CoV-2 receptors and infection in human gingival epithelial cells (GECs). We found that cigarette smoke condensates (CSC) upregulated ACE2 and TMPRSS2 expression in GECs, and that CSC activated aryl hydrocarbon receptor (AhR) signaling in the oral cells. ACE2 was known to mediate SARS-CoV-2 internalization, and we demonstrate that CSC treatment potentiated the internalization of SARS-CoV-2 pseudovirus in GECs in an AhR-dependent manner. AhR depletion using small interference RNA decreased SARS-CoV-2 pseudovirus internalization in CSC-treated GECs compared with control GECs. Our study reveals that cigarette smoke upregulates SARS-CoV-2 receptor expression and infection in oral cells. Understanding the mechanisms involved in SARS-CoV-2 infection in cells of the oral cavity may suggest therapeutic interventions for preventing viral infection and transmission.

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Caveolin-1 aggravates cigarette smoke extract-induced MUC5AC secretion in human airway epithelial cells

International Journal of Molecular Medicine ◽

10.3892/ijmm.2015.2133 ◽

2015 ◽

Vol 35 (5) ◽

pp. 1435-1442 ◽

Cited By ~ 8

Author(s):

QIAO YU ◽

XI CHEN ◽

XIA FANG ◽

QIONG CHEN ◽

CHENGPING HU

Keyword(s):

Epithelial Cells ◽

Cigarette Smoke ◽

Cigarette Smoke Extract ◽

Airway Epithelial Cells ◽

Airway Epithelial ◽

Caveolin 1 ◽

Human Airway ◽

Human Airway Epithelial Cells

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Nitric oxide increases IL-8 gene transcription and mRNA stability to enhance IL-8 gene expression in lung epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00165.2004 ◽

2004 ◽

Vol 287 (4) ◽

pp. L764-L773 ◽

Cited By ~ 34

Author(s):

Loretta Sparkman ◽

Vijayakumar Boggaram

Keyword(s):

Gene Expression ◽

Nitric Oxide ◽

Protein Kinase ◽

Epithelial Cells ◽

Gene Transcription ◽

Mrna Stability ◽

Inflammatory Responses ◽

Lung Epithelial Cells ◽

Mrna Levels ◽

Lung Epithelial

Interleukin (IL)-8, a C-X-C chemokine, is a potent chemoattractant and an activator for neutrophils, T cells, and other immune cells. The airway and respiratory epithelia play important roles in the initiation and modulation of inflammatory responses via production of cytokines and surfactant. The association between elevated levels of nitric oxide (NO) and IL-8 in acute lung injury associated with sepsis, acute respiratory distress syndrome, respiratory syncytial virus infection in infants, and other inflammatory diseases suggested that NO may play important roles in the control of IL-8 gene expression in the lung. We investigated the role of NO in the control of IL-8 gene expression in H441 lung epithelial cells. We found that a variety of NO donors significantly induced IL-8 mRNA levels, and the increase in IL-8 mRNA was associated with an increase in IL-8 protein. NO induction of IL-8 mRNA was due to increases in IL-8 gene transcription and mRNA stability. NO induction of IL-8 mRNA levels was not inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and KT-5823, inhibitors of soluble guanylate cyclase and protein kinase G, respectively, and 8-bromo-cGMP did not increase IL-8 mRNA levels. This indicated that NO induces IL-8 mRNA levels independently of changes in the intracellular cGMP levels. NO induction of IL-8 mRNA was significantly reduced by inhibitors of extracellular regulated kinase and protein kinase C. IL-8 induction by NO was also reduced by hydroxyl radical scavengers such as dimethyl sulfoxide and dimethylthiourea, indicating the involvement of hydroxyl radicals in the induction process. NO induction of IL-8 gene expression could be a significant contributing factor in the initiation and induction of inflammatory response in the respiratory epithelium.

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