C-C Motif Chemokine Receptor 3-Mediated Extracellular Signal-Regulated Kinase 1/2 and p38 Mitogen-Activated Protein Kinase Signaling: Promising Targets for Human Airway Epithelial Mucin 5AC Induction by Eotaxin-2 and Eotaxin-3.

INTRODUCTION: Eotaxin-2 and -3 of the C-C chemokine subfamily function as potent chemoattractant factors for eosinophil recruitment and various immune responses in allergic and inflammatory airway diseases. Mucin 5AC (MUC5AC), a major gel-forming secretory mucin, is overexpressed in airway inflammation. However, the association between mucin secretion and eotaxin-2/3 expression in the upper and lower airway epithelial cells has not been fully elucidated. Therefore, in this study, we investigated the effects of eotaxin-2/3 on MUC5AC expression and its potential signaling mediators. METHODS: We analyzed the effects of eotaxin-2 and -3 on NCI-H292 human airway epithelial cells and primary human nasal epithelial cells (HNEpCs) via reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and western blotting. Along with immunoblot analyses with specific inhibitors and small interfering RNA (siRNA), we explored the signaling pathway involved in MUC5AC expression following eotaxin-2/3 treatment. RESULTS: In HCI-H292 cells, eotaxin-2/3 activated the mRNA expression and protein production of MUC5AC. A specific inhibitor of C-C motif chemokine receptor 3 (CCR3), SB328437, suppressed eotaxin-2/3-induced MUC5AC expression at both the mRNA and protein levels. Eotaxin-2/3 induced the phosphorylation of extracellular signal-regulated kinase (ERK)-1/2 and p38, whereas pretreatment with a CCR3 inhibitor significantly attenuated this effect. Induction of MUC5AC expression with eotaxin-2/3 was decreased by U0126 and SB203580, specific inhibitors of ERK1/2 and p38 mitogen-activated protein kinase (MAPK), respectively. In addition, cell transfection with ERK1/2 and p38 siRNAs inhibited eotaxin-2/3-induced MUC5AC expression. Moreover, specific inhibitors (SB328437, U0126, and SB203580) attenuated eotaxin-2/3-induced MUC5AC expression in HNEpCs. CONCLUSION: Our results imply that CCR3-mediated ERK1/2 and p38 MAPK are involved in the signal transduction of eotaxin-2/3-induced MUC5AC overexpression.

Crushed Septal Cartilage-Covered Diced Cartilage Glue (CCDG) Graft: A Hybrid Technique of Crushed Septal Cartilage.

BACKGROUND: Diced cartilage glue (DG) grafts have been widely used in dorsal augmentation but can induce dorsal irregularities. The authors evaluated the postoperative feasibility of a crushed septal cartilage-covered diced cartilage glue (CCDG) graft. METHODS: The medical records of 38 patients who underwent dorsal augmentation rhinoplasty with an open approach were retrospectively reviewed. DG graft was used in 18 patients (47.4%), and CCDG graft was used in 20 patients (52.6%). Surgical outcomes were assessed by comparing anthropometric data on facial photographs and satisfaction questionnaires on aesthetic outcomes and palpable irregularities on nasal dorsum before and after surgery. RESULTS: Both groups showed successful aesthetic outcomes. Dorsal height, radix height, and tip projection were all increased postoperatively in both groups. Tip rotation did not significantly increase (p > 0.05). Both groups showed similar outcomes in terms of aesthetic satisfaction but a significant difference in palpable irregularity. CCDG graft group showed significantly better (p = 0.04) satisfaction with dorsal irregularities (4.15 ± 0.75) than the DG graft group (3.56 ± 0.92). CCDG graft group also showed significantly better mean values (p = 0.048) in the degree of irregularity by two surgeons (3.85 ± 0.65) than the DG graft group (3.25 ± 0.97). No patient had significant complaints about irregular dorsum, and none of them underwent a revision rhinoplasty. CONCLUSION: CCDG graft can be a complementary option for avoiding postoperative irregular dorsum complications. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266 .

Diesel exhaust particles elevate MUC5AC and MUC5B expression via the TLR4-mediated activation of ERK1/2, p38 MAPK, and NF-κB signaling pathways in human airway epithelial cells.

Exposure to diesel exhaust particles (DEPs) is known to cause serious health problems, owing to a steady increase in the number of diesel vehicles worldwide. DEPs comprise approximately 90% particle mass existing in the fine size range (≤2.5 µm) and are mainly absorbed in the respiratory tract. However, limited information is available on the effects of DEP exposure on the respiratory tract in humans. Here, we investigated the effect and signaling pathways of DEPs on the expression of mucin, especially MUC5AC and MUC5B, in human airway epithelial cells by reverse-transcriptase polymerase chain reaction (PCR), real-time PCR, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence staining. The signaling pathways activated following DEP-induced expression of MUC5AC and MUC5B in airway epithelial cells were analyzed by evaluating Toll-like receptor 4 (TLR4), mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2 [ERK1/2] and p38), and nuclear factor kappa B (NF-κB) phosphorylation with western blot and small-interfering RNA (siRNA) analyses. DEPs significantly increased MUC5AC and MUC5B expression in human airway epithelial cells that was closely related to TLR4, MAPK (ERK 1/2 and p38), and NF-κB pathway activation. This is the first report to demonstrate the DEP-mediated increase in MUC5AC and MUC5B expression via the TLR4-mediated activation of ERK1/2, p38 MAPK, and NF-κB signaling pathways in human airway epithelial cells.

Allethrin and prallethrin stimulates MUC5AC expression through oxidative stress in human airway epithelial cells.

Pyrethroids, including allethrin and prallethrin, have been widely used as major components of the common commercial insecticides. The toxicity of allethrin and prallethrin were well established that it interfered with the way that the nerves and brain function. However, limited information was available regarding respiratory effects in humans following inhalation exposure to allethrin and prallethrin. Therefore, we demonstrated effect of allethrin and prallethrin, and the mechanism involved, on the mucin expressions in human airway epithelial cells. In human airway NCI-H292 epithelial cells, the effects of allethrin and prallethrin and its signaling pathway for airway mucin, especially MUC5AC, were investigated by reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, and enzyme-linked immunosorbent assay (ELISA). The mechanism of allethrin and prallethrin-induced MUC5AC expression in airway epithelial cells was studied in terms of reactive oxygen species (ROS) by flow cytometry analysis. Allethrin and prallethrin significant increased MUC5AC expression in human airway NCI-H292 epithelial cells. We also demonstrated allethrin and prallethrin induced a marked rise of ROS production. In addition, NAC (ROS scavenger) and DPI (NADPH oxidase inhibitor) inhibited allethrin and prallethrin-induced MUC5AC expression. These results are first to describe that allethrin and prallethrin-induced MUC5AC expression through ROS in human airway epithelial cells.

Resistin upregulates MUC5AC/B mucin gene expression in human airway epithelial cells.

Adipokines, a group of proteins including leptin, visfatin, resistin, and adiponectin, are produced by adipocytes. Among adipokines, resistin is implicated in insulin resistance and inflammatory response modulation. Mucus hypersecretion has been greatly linked to airway diseases, such as asthma, chronic obstructive pulmonary disease, and rhinosinusitis. Increasing evidence has indicated that adipokines, such as leptin and visfatin, play important regulatory roles in various biological processes involved in mucus secretion. However, the effects of resistin on mucin expression in human airway epithelial cells, as well as the underlying mechanisms, have not been investigated yet. We showed that resistin affected mucin expression in human airway epithelial cells via the mitogen-activated protein kinase/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. Resistin increased MUC5AC and MUC5B expression in NCI-H292 and primary human nasal epithelial cells. Additionally, it significantly increased the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38, and NF-κB. ERK1/2 and p38 specific inhibitors significantly attenuated resistin-induced MUC5AC/5B expression; however, NF-κB inhibitor reduced resistin-induced MUC5AC, but not MUC5B, expression. Knockdown of ERK1, ERK2, and p38 by ERK1, ERK2, and p38 small interfering RNA (siRNA), respectively, significantly blocked resistin-induced MUC5AC and MUC5B mRNA expression. In addition, NF-κB siRNA attenuated resistin-induced MUC5AC, but not MUC5B, expression. These results suggested that resistin induced MUC5AC and MUC5B expression via activation of different signaling pathways in human airway epithelial cells.

Effect of titanium dioxide nanoparticles (TiO2 NPs) on the expression of mucin genes in human airway epithelial cells.

OBJECTIVE: Titanium dioxide nanoparticles (TiO2 NPs) are utilized with growing frequency for a wide variety of industrial applications. Recently, acute and chronic exposures to TiO2 NPs have been found to induce inflammatory response in the human respiratory tract. However, the effect and mechanism underlying the induction of major airway mucins by TiO2 NPs have not been elucidated. This study was conducted to characterize the effect of TiO2 NPs, and the mechanism involved, on the expressions of airway mucins in human airway epithelial cells. MATERIALS AND METHODS: In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effects of TiO2 NPs and signaling pathway for airway mucin genes were investigated by reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassays and immunoblot analysis using several specific inhibitors and small interfering RNAs (siRNAs). RESULTS: TiO2 NPs increased MUC5B expression and activated the phosphorylations of extracellular signal-related kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). U0126 (an ERK1/2 MAPK inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited TiO2 NPs-induced MUC5B expression. And knockdown of ERK1, ERK2 and p38 MAPK using siRNAs significantly blocked TiO2 NPs-induced MUC5B mRNA expression. Furthermore, Toll-like receptor 4 (TLR4) mRNA expression was increased by TiO2 NPs, and knockdown by TLR4 siRNA significantly attenuated TiO2 NPs-induced MUC5B mRNA expression and the TiO2 NPs-induced phosphorylations of ERK1/2 and p38 MAPK. DISCUSSION AND CONCLUSIONS: These results demonstrate for the first time that TiO2 NPs induce MUC5B expression via TLR4-dependent ERK1/2 and p38 MAPK signaling pathways in respiratory epithelium.

Effect of thymic stromal lymphopoietin on MUC5B expression in human airway epithelial cells.

Thymic stromal lymphopoietin (TSLP) is an interleukin 7-like cytokine and a potent factor for B- and T-cell growth and differentiation. Recent studies have demonstrated an association of TSLP with allergic and inflammatory airway diseases. However, no study on the effect of TSLP on expression of mucin genes in airway epithelial cells has been reported. Therefore, the effects and brief signaling pathways of TSLP on expression of mucin genes in human airway epithelial cells were investigated in this study. In mucin-producing human NCI-H292 airway epithelial cells and primary cultures of normal nasal epithelial cells, the effect and signaling pathway of TSLP on expression of mucin genes were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA). In human NCI-H292 airway epithelial cells, TSLP increased MUC5B expression. TSLP significantly activated phosphorylation of ERK1/2 and p38 mitogen-activated protein kinase (MAPK). U0126 (ERK1/2 MAPK inhibitor) and SB203580 (p38 MAPK inhibitor) significantly attenuated TSLP-induced MUC5B mRNA expression. Knockdown of ERK1, ERK2, and p38 MAPK by ERK1, ERK2, and p38 MAPK siRNA significantly blocked TSLP-induced MUC5B mRNA expression. In the primary cultures of normal nasal epithelial cells, TSLP significantly increased MUC5B mRNA expression, which was significantly attenuated after pretreatment with U0126 and SB203580. These results suggest that TSLP induces MUC5B expression via the ERK1/2 and p38 MAPK signaling pathway in human airway epithelial cells.

Visfatin induces MUC8 and MUC5B expression via p38 MAPK/ROS/NF-κB in human airway epithelial cells.

BACKGROUND: Among a variety of inflammatory mediators, visfatin is a proinflammatory adipocytokine associated with inflammatory reactions in obesity, metabolic syndrome, chronic inflammatory disease, and autoimmune disease. However, the biological role of visfatin in secretion of major mucins in human airway epithelial cells has not been reported. Therefore, this study was conducted in order to investigate the effect and the brief signaling pathway of visfatin on MUC8 and MUC5B expression in human airway epithelial cells. RESULTS: Visfatin significantly induced MUC8 and MUC5B expression. Visfatin significantly activated phosphorylation of p38 MAPK. Treatment with SB203580 (p38 MAPK inhibitor) and knockdown of p38 MAPK by siRNA significantly blocked visfatin-induced MUC8 and MUC5B expression.Visfatin significantly increased ROS formation. Treatment with SB203580 significantly attenuated visfatin-induced ROS formation. Treatment with NAC (ROS scavenger) and DPI (NADPH oxidase inhibitor) significantly attenuated visfatin-induced MUC8 and MUC5B expression. However, treatment with NAC and DPI did not attenuate visfatin-activated phosphorylation of p38 MAPK. Visfatin significantly activated the phosphorylation of NF-κB. Treatment with PDTC (NF-κB inhibitor) significantly attenuated visfatin-induced MUC8 and MUC5B expression. CONCLUSIONS: These results suggest that visfatin induces MUC8 and MUC5B expression through p38 MAPK/ROS/NF-κB signaling pathway in human airway epithelial cells.

The effect of Epigallocatechin-3-gallate in allergic airway inflammation.

BACKGROUND: The variety of beneficial effects of green tea has been reported. Epigallocatechin-3-gallate (EGCG) is a major component of green tea extract. The biological activity of EGCG includes anti-allergic and anti-inflammatory activities. However, the precise effect of EGCG on the allergic airway inflammation has not been fully defined. METHODOLOGY: In lung tissues of an asthma model-mouse, and nasal epithelial cells of patients with allergic rhinitis, the effect and brief signaling pathway of EGCG on MUC5B expression were investigated using real-time polymerase chain reaction, immunohistochemical, and immunoblot analysis. RESULTS: In the asthma model-mouse, mucus production, MUC5B expression, p38 mitogen-activated protein kinase (MAPK) and matrix metalloprotease (MMP)-9 expression of the asthma group were significantly higher than in the control group. Extracellular signal related kinase (ERK)1/2 MAPK expression did not change. Mucus production, MUC5B expression, p38 MAPK expression, and MMP-9 expression of the asthma + EGCG group were significantly lower than in the asthma group. In the nasal epithelial cells of patients with allergic rhinitis, EGCG significantly decreased phorbol 12-myristate 13-acetate (PMA)-induced MUC5B and MMP-9 expression. CONCLUSION: These results suggest that EGCG reduces mucin expression in the asthma model-mouse and nasal epithelial cells of patients with allergic inflammation.

E-cigarettes exacerbate allergic inflammation via cytokine induction and MUC5AC/5B expression in a murine asthma model.

The effects of electronic cigarettes (e-cigarettes) vapor on inflammation and mucin secretion on asthmatics remain insufficiently explored. This study investigated the effects of e-cigarette vapor on allergic inflammation, cytokine production, and MUC5AC/5B expression in murine asthma model. Airway hyperresponsiveness was significantly higher in the e-cigarette-exposed ovalbumin (OVA) sensitization group than in the control, e-cigarette exposure, and OVA sensitization groups. The e-cigarette-exposed OVA sensitization group showed significantly greater infiltration of inflammatory cells and Th2-mediated inflammatory cytokines (interleukin-4 and -5) compared to the control, e-cigarette exposure, and OVA sensitization groups. MUC5AC mucin levels were significantly elevated in the e-cigarette exposure, OVA sensitization, and e-cigarette-exposed OVA sensitization groups, whereas MUC5B mucin levels were significantly elevated in the OVA sensitization and e-cigarette-exposed OVA sensitization groups. The results may suggest that the exposure to e-cigarette vapor in an asthmatics promoted allergic inflammation and increased mucin secretion, ultimately leading to the exacerbation of asthma.

Insulin-like growth factor-1 induces MUC8 and MUC5B expression via ERK1 and p38 MAPK in human airway epithelial cells.

The biologic actions of insulin-like growth factor-1(IGF-1) are associated with cell growth, differentiation, migration, and survival. IGF-1 constitutes the pathogenic factor in formation of nasal polyps and the regulatory factor in expression of mucins. However, the effect of IGF-1 on MUC8 and MUC5B expression has not been reported. Therefore, in this study, the effect and brief signaling pathway of IGF-1 on MUC8 and MUC5B expression were investigated in human airway epithelial cells. In mucin-producing human NCI-H292 airway epithelial cells and the primary cultures of normal human nasal epithelial cells, the effect and signaling pathway of IGF-1 on MUC8 and MUC5B expression were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with specific inhibitors and small interfering RNA (siRNA) for mitogen-activated protein kinase (MAPK). IGF-1 induced MUC8 and MUC5B expression, and activated phosphorylation of ERK1/2 and p38 MAPK. U0126 (ERK1/2 inhibitor) and SB203580 (p38 MAPK inhibitor) inhibited IGF-1 induced MUC8 and MUC5B mRNA expression. In addition, the knockdown of ERK1 and p38 MAPK by siRNA significantly blocked IGF-1 induced MUC8 and MUC5B mRNA expression; the knockdown of ERK2 MAPK by siRNA did not. These results demonstrate for the first time that IGF-1 induced MUC8 and MUC5B expression is regulated by activation of the ERK1 and p38 MAPK signaling pathway in human airway epithelial cells.

Ghrelin Downregulates Lipopolysaccharide/ Leptin-Induced MUC5AC Expression in Human Nasal Epithelial Cells.

OBJECTIVES: Obesity, which induces chronic low-grade systemic inflammation in the human body, is a known risk factor for various diseases. Recent studies have shown associations between various otorhinolaryngological diseases and obesity. In particular, inflammatory sinonasal diseases have been found to be strongly associated with obesity-related proinflammatory mediators. Many studies have been conducted to identify therapeutic agents for controlling obesity-related inflammatory airway diseases. Ghrelin, an endogenous peptide from the stomach, has anti-inflammatory and antioxidative effects in a wide range of tissues. However, the effect of ghrelin on the regulation of mucus secretion has not yet been studied in the human nasal mucosa. Therefore, we investigated the effects of ghrelin on lipopolysaccharide (LPS)/leptin-mediated MUC5AC expression and mechanisms involved in human nasal epithelial cells (HNEpCs). METHODS: In HNEpCs, the effect and signaling pathways of ghrelin on LPS/leptin-induced MUC5AC expression were examined using reverse transcription polymerase chain reaction, real-time polymerase chain reaction, enzyme immunoassays, Western blotting, and immunofluorescence staining. RESULTS: Growth hormone secretagogue receptor 1a (GHSR1a) was expressed in the HNEpCs. Ghrelin downregulated LPS/leptin-induced MUC5AC expression, which was abolished by D-Lys-3-growth hormone-releasing peptide 6 (D-Lys-3-GHRP-6). Ghrelin significantly inhibited LPS/leptin-activated extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinases (MAPKs). These ghrelin-mediated changes in MAPK activation were abolished by D-Lys-3-GHRP-6. These. RESULTS: showed that ghrelin inhibits LPS/leptin-induced MUC5AC overexpression by modulating the ERK1/2 and p38 MAPK pathways in HNEpCs. CONCLUSION: These findings suggest that ghrelin is a potential therapeutic agent for treating obesity-related inflammatory sinonasal diseases.

Complete response of metastatic BRAF V600-mutant anaplastic thyroid cancer following adjuvant dabrafenib and trametinib treatment: A case report.

BACKGROUND: Anaplastic thyroid cancer (ATC) is a rare but aggressive type of thyroid carcinoma. BRAF V600E-mutation, which is found in 10%-50% of ATCs, is associated with poor prognosis. A recent clinical trial reported a substantial clinical benefit of concomitant treatment of dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) for treating BRAF V600E-mutant ATC. However, reports on patients with ATC treated with this regimen following surgery are lacking. CASE SUMMARY: We report the case of a 63-year-old female patient diagnosed with BRAF V600E-mutant ATC. Following three surgeries-total thyroidectomy, total laryngectomy, and neck dissection-she was diagnosed with lung metastasis during follow-up. The metastatic ATC was successfully treated with dabrafenib and trametinib. The patient achieved a complete response at the 32-mo follow-up. CONCLUSION: Adjuvant chemotherapy with dabrafenib plus trametinib is efficacious for treatment and prevention of recurrent ATC with BRAF mutation following surgery.

Diallyl disulfide induces MUC5B expression via ERK2 in human airway epithelial cells.

Garlic has been shown to have antimicrobial, hypolipidemic, antithrombotic, antitumor and immunostimulatory properties. The medicinal effects of garlic are derived from the flavonoid and organosulfur components. Diallyl disulfide (DADS), an organosulfur, is the main component responsible for the diverse biological effects of garlic. However, the effects of DADS on mucin gene expression in airway epithelial cells have not been reported to date. Therefore, this study was performed to investigate the effects and brief signaling pathway of DADS associated with MUC5B expression in NCI-H292 epithelial cells using RT-PCR, ELISA, western blot, immunocytochemistry and cell transfection with siRNA. DADS induced MUC5B expression and activated the phosphorylation of ERK1/2 MAPK. In addition, U0126 inhibited DADS-induced MUC5B expression and DADS-activated phosphorylation of ERK1/2 MAPK. Moreover, the immunopositive cells for MUC5B protein did not appear after treatment of DADS with U0126, and the knockdown of ERK2 MAPK by ERK2 MAPK siRNA significantly blocked DADS-induced MUC5B mRNA expression. However, DADS did not activate the phosphorylation of p38 MAPK, and SB203580 did not inhibit DADS-induced MUC5B expression. This is the first study to show that DADS-induced MUC5B expression appears to be regulated by activation of the ERK2 MAPK signaling pathway in human NCI-H292 airway epithelial cells.

Saponin attenuates diesel exhaust particle (DEP)-induced MUC5AC expression and pro-inflammatory cytokine upregulation via TLR4/TRIF/NF-κB signaling pathway in airway epithelium and ovalbumin (OVA)-sensitized mice.

Background: Diesel exhaust particle (DEP) is a harmful kind of particulate matter known to exacerbate pre-existing respiratory diseases. Although their adverse effects on airway pathologies have been widely studied, the mechanistic analysis of signaling pathways and potential targets in reducing DEP-induced mucin secretion and pro-inflammatory cytokine production remain elusive. We, for the first time, investigated the effects of Korean Red Ginseng (KRG) extracts on mucin overproduction and airway inflammation induced by DEP. Methods: The effects of KRG and saponin on DEP-induced expression of MUC5AC and interleukin (IL)-6/8 were examined by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) in human airway epithelial NCI-H292 cells. We conducted Western blotting analysis to analyze the associated signaling pathways. To evaluate the effects of saponin treatment on DEP-induced MUC5AC expression and inflammatory cell infiltrations in ovalbumin (OVA)-sensitized mice, immunohistochemical (IHC) staining and real-time PCR were implemented. Results: The KRG extracts markedly attenuated DEP-induced MUC5AC expression in vitro by inhibiting the TLR4/TRIF/NF-κB pathway. Furthermore, KRG and saponin inhibited DEP-induced pro-inflammatory cytokine IL-6/8 production. The in vivo study revealed that saponin blocked DEP-induced inflammation, mucin production and MUC5AC expression. Conclusion: Our study revealed that KRG extracts have inhibitory effects on DEP-induced expression of MUC5AC and the production of pro-inflammatory cytokines. This finding provides novel insights into the mechanism by which saponin alleviates diesel-susceptible airway inflammation, elucidating its potential as a phytotherapeutic agent for inflammatory pathologies of airway.

SARS-CoV-2 Induces Expression of Cytokine and MUC5AC/5B in Human Nasal Epithelial Cell through ACE 2 Receptor.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a novel infectious respiratory disease called COVID-19, which is threatening public health worldwide. SARS-CoV-2 spike proteins connect to the angiotensin converting enzyme 2 (ACE2) receptor through the receptor binding domain and are then activated by the transmembrane protease serine subtype 2 (TMPRSS2). The ACE2 receptor is highly expressed in human nasal epithelial cells. Nasal ciliated cells are primary targets for SARS-CoV-2 replication. However, the effect of SARS-CoV-2 on the upper respiratory tract remains unknown, thus leading to the purpose of our study. We investigate the effects of SARS-CoV-2 on cytokines and mucin expression in human nasal epithelial cells. Methods: We investigated the effects of the SARS-CoV-2 spike protein receptor binding domain (RBD) on cytokines (IL-1ß, IL-6, and IL-8) and MUC5AC/5B expression via real-time PCR, ELISA, periodic acid-Schiff (PAS) staining, and immunofluorescence staining in cultured human nasal epithelial cells. Results: The mRNA expression and protein production of cytokines (IL-1ß, IL-6, and IL-8) and MUC5AC/5B were increased by SARS-CoV-2 spike protein RBD. ACE2 receptor inhibitor suppressed the expression of cytokines (IL-1ß, IL-6, and IL-8) and MUC5AC/5B induced by SARS-CoV-2 spike protein RBD. Conclusions: SARS-CoV-2 induced cytokines (IL-1ß, IL-6, and IL-8) and MUC5AC/5B expression through the ACE 2 receptor in human nasal epithelial cells. Therefore, ACE2 receptor inhibitors can be an effective therapeutic option for SARS-CoV-2 infection.

AMPK induces MUC5B expression via p38 MAPK in NCI-H292 airway epithelial cells.

Adenosine monophosphate-activated protein kinase (AMPK) is a well-known serine/threonine kinase that has been implicated in modulation of glucose and fatty acid metabolism. Recent reports have also implicated AMPK in modulation of mucin secretion. In this study, the effects and signaling pathways of AMPK on MUC5B expression were investigated in human NCI-H292 airway epithelial cells. Metformin, as an activator of AMPK, induced MUC5B expression in a dose-dependent manner. Compound C, as an inhibitor of AMPK, inhibited metformin-induced MUC5B expression in a dose-dependent manner. Metformin significantly activated phosphorylation of AMPK; compound C inhibited metformin-activated phosphorylation of AMPK. Without treatment with metformin, there was no difference in MUC5B mRNA expression between Ad-dnAMPK transfected and wild-type adenovirus transfected NCI-H292 cells. However, after treatment with metformin, MUC5B mRNA expression was increased in wild-type adenovirus transfected NCI-H292 cells; MUC5B mRNA expression was significantly decreased in Ad-dnAMPK transfected NCI-H292 cells. Metformin activated phosphorylation of p38 mitogen-activated protein kinase (MAPK); compound C inhibited metformin-activated phosphorylation of p38 MAPK. SB203580, as an inhibitor of p38 MAPK, significantly inhibited metformin-induced MUC5B mRNA expression, while U0126, as an inhibitor of ERK1/2 MAPK, had no effect. In addition, knockdown of p38 MAPK by p38 MAPK siRNA significantly blocked metformin-induced MUC5B mRNA expression. In conclusion, results of this study show that AMPK induces MUC5B expression through the p38 MAPK signaling pathway in airway epithelial cells.

Pepsin exposure in a non-acidic environment upregulates mucin 5AC (MUC5AC) expression via matrix metalloproteinase 9 (MMP9)/nuclear factor κB (NF-κB) in human airway epithelial cells.

BACKGROUND: Gastric reflux (GR) is a backflow of gastric content to the aerodigestive tract. GR was previously found to be associated with inflammatory airway diseases and a potential cause of airway remodeling. Chronic exposure to gastric content may induce damage from nose to lung, because digestive enzymes and acidity are toxic to airway epithelial cells. Recently, the toxicity of pepsin in a non-acidic environment was found to increase proinflammatory cytokines and receptors in the epithelium of the aerodigestive tract. However, the effect of pepsin in non-acidic conditions on mucin expression has not been investigated in human airway epithelial cells. The purpose of this study was to evaluate the effect of pepsin on mucin 5AC (MUC5AC) expression in upper and lower airway epithelial cells as an important potential factor of non-acidic GR-related airway inflammation. METHODS: In NCI-H292 cells and human nasal epithelial cells (HNEpCs), the effects and signaling pathways of pepsin on MUC5AC expression were examined using reverse-transcription polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, zymography, Western blot, and immunofluorescence staining. RESULTS: Pepsin increased MUC5AC expression in non-acidic condition of NCI-H292 cells and HNEpCs. Further, pepsin activated matrix metalloproteinase 9 (MMP9) and phosphorylated nuclear factor κB (NF-κB). Moreover, inhibitors of MMP9 and NF-κB significantly attenuated pepsin-induced MUC5AC expression, and the knockdown of NF-κB by small interfering RNA (siRNA) significantly blocked pepsin-induced MUC5AC expression in human airway epithelial cells. CONCLUSION: These findings suggest that pepsin increased MUC5AC expression in non-acidic conditions via the activation of MMP9 and NF-κB in human airway epithelial cells.

Glyoxal and Methylglyoxal as E-cigarette Vapor Ingredients-Induced Pro-Inflammatory Cytokine and Mucins Expression in Human Nasal Epithelial Cells.

BACKGROUND: Glyoxal (GO), and methylglyoxal (MGO) are among the most toxic compounds emitted by electronic cigarette (E-cig) and regular tobacco cigarette smoke. Airway diseases presented mucus over production as their major pathophysiologic feature. However, the effects of GO and MGO on pro-inflammatory cytokines and mucin expression in human nasal epithelial cells, as well as the underlying signaling pathway, have not yet been studied. OBJECTIVE: This study is to determine whether GO and MGO induce pro-inflammatory cytokines, and MUC5AC/5B expression via mitogen-activated protein kinase (MAPK)s and nuclear factor-kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways. METHODS: The effect of GO, and MGO on pro-inflammatory cytokines, mucins expression and the signalling pathway of GO and MGO were investigated using water-soluble tetrazolium salt-1, enzyme immunoassays, and immunoblot analysis with specific inhibitors and small interfering RNA. RESULTS: GO and MGO did not affect cell viability up to 2 mM in human nasal epithelial cells. GO and MGO increased production of pro-inflammatory such as interleukin (IL)-1ß and IL-6) and MUC5AC/5B. Additionally, GO and MGO significantly activated extracellular signal-regulated kinase 1/2 (ERK1/2), p38 MAPK, and NF-κB. Whether ERK1/2, p38 MAPK, and NF-κB signaling pathway were involved in GO and MGO-induced production of pro-inflammatory cytokines (IL-1ß and IL-6) and MUC5AC/5B, we used specific inhibitors and siRNA transfection. These significantly repressed GO- and MGO-induced expression of pro-inflammatory cytokines (IL-1ß and IL-6) and MUC5AC/5B. CONCLUSIONS: GO and MGO induced pro-inflammatory cytokines and MUC5AC/5B expression via ERK1/2, p38 MAPK, and NF-κB in human nasal epithelial cells. These results suggested that GO and MGO may be involved in mucus hypersecretion-related airway diseases.

Changes in Mucin Production in Human Airway Epithelial Cells After Exposure to Electronic Cigarette Vapor With or Without Nicotine.

OBJECTIVES: The emergence of electronic cigarettes (e-cigarettes) has created new perceptions of the tobacco market. Unlike traditional tobacco, the greatest advantage of e-cigarettes is that they have less smell and are convenient and inexpensive. Most e-cigarette smokers believe that e-cigarette smoking is less harmful than traditional smoking. Information on the effects of e-cigarettes on human health is limited, and the issue remains controversial. METHODS: We studied the effects of e-cigarette vapor on mucin (MUC5AC and MUC5B) and the change of MUC5AC and MUC5B from e-cigarette liquid with or without nicotine in respiratory epithelial cells. The effects of e-cigarette vapor with or without nicotine on mucin, along with the involved signaling pathways, were investigated using reverse transcriptase-polymerase chain reaction (PCR), real-time PCR, enzyme immunoassays, and immunoblot analysis with several specific inhibitors and small interfering RNA. RESULTS: E-cigarette vapor with or without nicotine stimulated MUC5AC, but not MUC5B, expression in respiratory epithelial cells. In addition, we showed that e-cigarette vapor with and without nicotine induced MUC5AC expression via activation of the mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase [ERK] 1/2 and p38) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathways in human airway epithelial cells. CONCLUSION: E-cigarette vapor with and with nicotine significantly increased MUC5AC expression in human airway epithelial cells.