MUC5AC Protein Expression Research Articles

InflammAging at Ocular Surface: Clinical and Biomolecular Analyses in Healthy Volunteers

To assess the ocular surface in volunteers who consider themselves as healthy, in order to evaluate how para-inflammatory mechanisms fail with age, and thus investigate the phenomenon of "InflammAging." In this observational prospective cohort study, volunteers were categorized into three groups according to age: young (19-40 years), middle-aged (41-60 years), and older adults (61-93 years). Clinical assessments included tear breakup time (T-BUT) and Schirmer test type I. Dry eye symptoms were evaluated by the Ocular Surface Disease Index (OSDI) questionnaire. Conjunctival mRNA and protein expression of intercellular adhesion molecule-1 (ICAM-1), MUC5AC, and IL-8 were measured by real-time PCR and immunofluorescence. A total of 82 volunteers (38 males and 44 females) were enrolled. T-BUT decreased significantly with increasing age (young: 11.13 ± 0.18 seconds; middle-aged: 10.83 ± 0.56 seconds; older: 9.00 ± 1.00 seconds, P < 0.05). Schirmer test values decreased significantly with age (young: 20.6 ± 1.0 mm; middle-aged: 19.2 ± 1.2 mm; older: 16.0 ± 1.1 mm, P < 0.05). OSDI scores increased with age in both groups, but they were substantially higher in women. Conjunctival expression of inflammatory markers ICAM-1, IL-8, and MUC5AC increased with age. Clinical signs, symptoms, and biomarkers of chronic inflammation increased with age in a cohort of volunteers who considered themselves healthy, indicating an age-related progressive impairment of ocular surface system function.

Polyhexamethylene guanidine phosphate-induced upregulation of MUC5AC via activation of the TLR-p38 MAPK and JNK axis

Epidemiological and toxicological studies indicate that polyhexamethylene guanidine phosphate (PHMG-p) is a guanidine-based cationic disinfectant strongly associated with interstitial lung diseases. As individuals exposed to aerosolized PHMG-p complain of respiratory problems (asthma and rhinitis), whether PHMG-p can cause respiratory diseases other than interstitial fibrosis should be investigated. MUC5AC, the predominant mucin gene expressed in airways, is associated with obstructive respiratory disease pathogenesis. Therefore, in this study, we elucidated the relationship between PHMG-p and MUC5AC overexpression. First, in immunofluorescence studies, the bronchial epithelia of mice intratracheally administrated PHMG-p appeared to be sloughing and tethered by MUC5AC. Second, Calu-3 cells exposed to PHMG-p showed concentration-dependent increases in MUC5AC mRNA and protein expression. c-Jun N-terminal kinase (JNK), p38, and c-jun were phosphorylated in cells exposed to PHMG-p. SP600125 and SB203580, JNK and p38 inhibitors, respectively, reduced the upregulation of MUC5AC by PHMG-p in Calu-3 cells. When toll-like receptor (TLR)2, 4, and 6 were silenced, PHMG-p-induced JNK and p38 phosphorylation decreased. Furthermore, TLR2-, 4-, and 6-silenced cells showed reduced levels of MUC5AC mRNA and protein induced by PHMG-p, with TLR6 knockdown showing the greatest effect. In conclusion, PHMG-p induced MUC5AC overexpression via activation of the TLR-p38 MAPK and JNK axis.

Louqin Zhisou Decoction Inhibits Mucus Hypersecretion for Acute Exacerbation of Chronic Obstructive Pulmonary Disease Rats by Suppressing EGFR-PI3K-AKT Signaling Pathway and Restoring Th17/Treg Balance.

Airway mucus hypersecretion is the main pathogenic factor in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and the control of mucus secretion is closely associated with survival. Louqin Zhisou decoction (LQZS) has been found to improve lung function and reduce sputum in AECOPD patients, but the mechanism remains unclear. This study aimed to explore the mechanism of LQZS against mucus hypersecretion in lung tissues of rat AECOPD model. Wistar rats were used to establish AECOPD model by intratracheal instillation of LPS in combination with the continuous cigarette smoking. Rats were administrated LQZS/clarithromycin (CAM)/distilled water via gavage every day and all rats were sacrificed after 30 days. BALF and lung tissues were obtained. Lung morphology, cytokines levels, MUC5AC mRNA transcription and protein expression, phosphorylation of the EGFR-PI3K-AKT signaling pathway, and molecules involved in Th17/Treg balance were evaluated. The results demonstrated that LQZS protected rats from decline in pulmonary function and ameliorated lung injury. LQZS treatment decreased the number of goblet cells in airway and suppressed MUC5AC mRNA and protein expression of lung tissues. Furthermore, LQZS attenuated the level of phospho-EGFR, phospho-PI3K and phospho-AKT in AECOPD rats. In addition, LQZS could inhibit the production of proinflammatory cytokines in BALF, including IL-6 and IL-17A and downregulate the secretion of NE and MCP-1, indicating that LQZS could limit inflammatory responses in AECOPD. Moreover, LQZS reversed RORγt and Foxp3 expression, the key transcription factors of Th17 and Treg, respectively. In conclusion, this research demonstrated the inhibitory effects of LQZS against mucus hypersecretion in AECOPD via suppressing EGFR-PI3K-AKT signaling pathway and restoring Th17/Treg balance.

Eucalyptol protects lungs against bacterial invasion through attenuating ciliated cell damage and suppressing MUC5AC expression.

This study was conducted to investigate whether eucalyptol plays a role in influencing bacterial growth in cigarette smoke-exposed lungs. Rats were exposed to air (control) and cigarette smoke (smoking) in the presence and absence of eucalyptol (260 mg/day). Morphological analysis of lung structures and status of airway mucous production were observed under microscope. Pathological changes of ciliated columnar epithelium in airways were examined using transmission electron microscopy. MUC5AC protein and messenger RNA (mRNA) expression in bronchoalveolar lavage fluid (BALF) and lungs were determined. Application of eucalyptol reduced pulmonary bullae formation and airway mucus overproduction in the smoke-exposed lungs. Treatment with eucalyptol attenuated ciliated cell damage in cigarette smoke-exposed lungs. Bacterial colonies of lungs were obviously lower in the eucalyptol-treated rats than that in the smoking rats (p < 0.01). Treatment with eucalyptol reduced the counts of bacterial colonization residing in the challenged lungs (p < 0.01). Application of eucalyptol not only decreased MUC5AC protein expression in BALF and tobacco-exposed lungs but also suppressed its mRNA expression in the lungs (all p < 0.05). Intervention of eucalyptol benefits elimination of bacterial organisms from tobacco-exposed lungs through attenuating ciliated cell damage and suppressing MUC5AC expression in the lungs.

Clarithromycin suppresses IL-13-induced goblet cell metaplasia via the TMEM16A-dependent pathway in guinea pig airway epithelial cells.

Transmembrane protein 16A (TMEM16A) is associated with mucus secretion and ion transport in asthma. Clarithromycin (CAM) is reported to inhibit IL-13-induced goblet cell metaplasia. However, the effect of CAM on TMEM16A function and expression remains unclear. Tracheal epithelial cells from guinea pigs were cultured for ~14 days at an air-liquid interface in medium containing IL-13 (10 ng/ml) in the absence or presence of CAM (20 µg/ml) or a TMEM16A inhibitor, T16Ainh-A01 (10 µg/ml). Electrophysiological studies were performed by Ussing׳s short-circuit technique. The cells were used for immunofluorescence staining with antibodies against TMEM16A, MUC5AC, and α-tubulin. The cells were also examined by transmission electron microscopy. TMEM16A protein levels in the cell lysates were determined by ELISA. For the in vivo study, guinea pigs were treated intratracheally with IL-13 in the absence or presence of CAM or T16Ainh-A01. CAM decreased the MUC5AC-positive cells and reduced TMEM16A expression in them and increased the α-tubulin-positive cells. CAM inhibited TMEM16A protein levels in a dose-dependent manner, and decreased UTP-induced Cl ion transport. In cells treated with IL-13 for 24 h, TMEM16A appeared prior to MUC5AC protein expression, and was inhibited by CAM. In the in vivo study, CAM inhibited IL-13-induced goblet cell metaplasia and TMEM16A expression. The inhibitory effects of CAM were similar to those of T16Ainh-A01. CAM inhibited IL-13-induced TMEM16A expression, Cl ion transport and goblet cell metaplasia both in vitro and in vivo. CAM may thus improve airway mucociliary differentiation by attenuating TMEM16A expression in IL-13-related asthma.

The dopamine D1 receptor is expressed and induces CREB phosphorylation and MUC5AC expression in human airway epithelium

Dopamine receptors comprise two subgroups, Gs protein-coupled “D1-like” receptors (D1, D5) and Gicoupled “D2-like” receptors (D2, D3, D4). In airways, both dopamine D1 and D2 receptors are expressed on airway smooth muscle and regulate airway smooth muscle force. However, functional expression of the dopamine D1 receptor has never been identified on airway epithelium. Activation of Gs-coupled receptors stimulate adenylyl cyclase leading to cyclic AMP (cAMP) production, which is known to induce mucus overproduction through the cAMP response element binding protein (CREB) in airway epithelial cells. We questioned whether the dopamine D1 receptor is expressed on airway epithelium, and whether it promotes CREB phosphorylation and MUC5AC expression. We evaluated the protein expression of the dopamine D1 receptor on native human airway epithelium and three sources of cultured human airway epithelial cells including primary cultured airway epithelial cells, the bronchial epithelial cell line (16HBE14o-), and the pulmonary mucoepidermoid carcinoma cell line (NCI-H292) using immunohistochemistry and immunoblotting. To characterize the stimulation of cAMP through the dopamine D1 receptor, 16HBE14o- cells and NCI-H292 cells were treated with dopamine or the dopamine D1 receptor agonists (SKF38393 or A68930) before cAMP measurements. The phosphorylation of CREB by A68930 in both 16HBE14o- and NCI-H292 cells was measured by immunoblot. The effect of dopamine or A68930 on the expression of MUC5AC mRNA and protein in NCI-H292 cells was evaluated by real-time PCR and immunofluorescence staining, respectively. The dopamine D1 receptor protein was detected in native human airway epithelium and three sources of cultured human airway epithelial cells. Dopamine or the dopamine D1-like receptor agonists stimulated cAMP production in 16HBE14o- cells and NCI-H292 cells, which was reversed by the selective dopamine D1-like receptor antagonists (SCH23390 or SCH39166). A68930 significantly increased phosphorylation of CREB in both 16HBE14o- and NCI-H292 cells, which was attenuated by the inhibitors of PKA (H89) and MEK (U0126). Expression of MUC5AC mRNA and protein were also increased by either dopamine or A68930 in NCI-H292 cells. These results suggest that the activation of the dopamine D1 receptor on human airway epithelium could induce mucus overproduction, which could worsen airway obstructive symptoms.

Salvianolic acid B improves airway hyperresponsiveness by inhibiting MUC5AC overproduction associated with Erk1/2/P38 signaling

Salvianolic acid B (SalB) is one of the main water-soluble composites from Chinese medicine Dansen (Radix miltiorrhiza). It is used for clinical treatment of various diseases including cardiovascular, lung, Liver, renal and cancers. However, the effects of SalB to allergy induced airway mucin hypersecretion, inflammation and hyperresponsiveness (AHR) remains not clear. Overproduction of airway MUC5AC is a central effector of inflammation that is strongly associated with AHR in asthmatic attack. In this study, we investigated the anti-asthmatic activity and mechanism of SalB in a murine model and human epithelial cells by monitoring changes in mucin expression and secretion, airway inflammation, AHR, and signaling pathways. SalB was administered by intragastric administration (i.g) daily for a week, starting at 21 days after sensitization of ovalbumin (OVA). All examinations were performed 24h after the last antigen challenge. We found that treatments with SalB significantly inhibited increase in the tracheobronchial secretion, glycosaminoglycan levels, interleukin (IL)−13, IL-4, and IL-5 cytokines mRNA and protein expression, and decrease in mucociliary clearance in lung tissues. Histological results demonstrated that SalB attenuated OVA-induced eosinophil infiltration, airway goblet cell hyperplasia, and MUC5AC and MUC5B mRNA and protein expression in lung tissues. SalB exhibited protective effects against AHR in OVA-challenged animals. In vitro, SalB significantly inhibited IL-13-induced MUC5AC and MUC5B mRNA and protein expression in human epithelial cells. These effects were blocked by SalB by downregulating the Erk1/2 and P38 signaling pathways. Taken together, these data indicate that treatment with SalB may improve AHR by inhibiting MUC5AC overproduction.

LPS Exposure in Early Life Protects Against Mucus Hypersecretion in Ovalbumin-Induced Asthma by Down-Regulation of the IL-13 and JAK-STAT6 Pathways

Background/Aims: Previous studies have shown that lipopolysaccharide (LPS) exposure may have a protective effect on asthma by reducing airway hyper-responsiveness, airway inflammation and serum IgE levels. However, there are few studies investigating the effect of LPS on mucous secretion in asthma. In this study, we evaluate the relationship between LPS pre-treatment in infant mice and airway mucus hypersecretion in an OVA (ovalbumin)-induced asthma model, and further explore the mechanisms behind this effect. Methods: Mice were pre-treated with LPS by intranasal instillation (i.n.) from the 3^rd day of life for 10 consecutive days before the OVA-induced asthma model was established. In order to detect mucus secretion, periodic acid-Schiff (PAS) staining was carried out, and the expression of Muc5ac was detected. The IL-13 levels in Bronchoalveolar lavage fluid (BALF) and lung tissue were also detected. In vitro, the expression of Muc5ac mRNA and protein was quantified in IL-13-stimulated 16HBE cells with or without LPS pre-treatment. In addition, proteins in the JAK2/STAT6 pathway, transcription factors (forkhead box transcription factor A2 (FOXA2), activation protein-1(AP-1), NF-κB), and the levels of reactive oxygen species (ROS) were also measured in vivo and in vitro. Results: LPS pre-treatment reduced mucus secretion, as demonstrated by decreased PAS staining and muc5ac expression. Further exploration of the underlying mechanisms of this phenomenon revealed that LPS pre-treatment decreased the production of IL-13, IL-13 induced ROS synthesis was reduced, and the JAK2/STAT6 pathway was inhibited. Decreased stat6 increased transcription factor FOXA2, and the relatively increased FOXA2 further decreased the level of Muc5ac and mucous hypersecretion in OVA-induced asthma. Conclusions: LPS pre-treatment ameliorated mucus hypersecretion in an OVA-induced asthma model by inhibition of IL-13 production and by further inhibiting the JAK2/STAT6 pathway and ROS activity, and up-regulating expression of FOXA2.

Identification of trans Protein QTL for Secreted Airway Mucins in Mice and a Causal Role for Bpifb1.

Mucus hyper-secretion is a hallmark feature of asthma and other muco-obstructive airway diseases. The mucin proteins MUC5AC and MUC5B are the major glycoprotein components of mucus and have critical roles in airway defense. Despite the biomedical importance of these two proteins, the loci that regulate them in the context of natural genetic variation have not been studied. To identify genes that underlie variation in airway mucin levels, we performed genetic analyses in founder strains and incipient lines of the Collaborative Cross (CC) in a house dust mite mouse model of asthma. CC founder strains exhibited significant differences in MUC5AC and MUC5B, providing evidence of heritability. Analysis of gene and protein expression of Muc5ac and Muc5b in incipient CC lines (n = 154) suggested that post-transcriptional events were important regulators of mucin protein content in the airways. Quantitative trait locus (QTL) mapping identified distinct, trans protein QTL for MUC5AC (chromosome 13) and MUC5B (chromosome 2). These two QTL explained 18 and 20% of phenotypic variance, respectively. Examination of the MUC5B QTL allele effects and subsequent phylogenetic analysis allowed us to narrow the MUC5B QTL and identify Bpifb1 as a candidate gene. Bpifb1 mRNA and protein expression were upregulated in parallel to MUC5B after allergen challenge, and Bpifb1 knockout mice exhibited higher MUC5B expression. Thus, BPIFB1 is a novel regulator of MUC5B.

Inhibition of IL-13-induced periostin in airway epithelium attenuates cellular protein expression of MUC5AC.

Serum periostin is increased in asthma and serves as a surrogate marker for IL-13 activity in the lung. Serum levels of periostin are the most robust biomarker predicting a favourable response to the anti-IL-13 drug, lebrikizumab. We investigated the mechanisms of IL-13 stimulation of periostin, the polarized secretion of periostin and whether periostin would have a direct effect on mucin secretion by airway cells. Normal human bronchial epithelial (NHBE) cells were cultured at air-liquid interface (ALI) in the presence of IL-13, and we evaluated the effect of the specific inhibitors, leflunomide (Janus kinase (JAK)/signal transducer and activator of transcription factor 6 (STAT6) inhibitor) or PD98059 (MEK/extracellular regulated protein kinase (ERK) inhibitor), on periostin production. We examined MUC5AC secretion from NHBE cells exposed to recombinant human (rh) periostin or IL-13 in the presence and absence of OC-20, a periostin-neutralizing antibody. IL-13 induced periostin protein which was predominantly secreted towards the basal surface of the cells. Periostin production was much greater from goblet cells than ciliated cells (P < 0.001). Periostin production after exposure to IL-13 was attenuated by both leflunomide (P < 0.001) and PD98059 (P < 0.001). The addition of exogenous periostin modestly increased MUC5AC secretion (P < 0.01), but did not visibly change cell morphology. IL-13-induced MUC5AC secretion was attenuated by OC-20 (P < 0.01). Periostin production in differentiated airway cells is mediated by JAK/STAT6 and MEK/ERK pathways. Periostin secretion is much greater from immunologically active goblet cells. IL-13-driven mucin production is partially inhibited by OC-20.

Suppression of MUC5AC expression in human bronchial epithelial cells by interferon-γ

BackgroundExcessive mucin secretion in the airway is an important feature of airway inflammatory diseases. MUC5AC expression is regulated by a variety of stimuli such as cytokines. Little is known about the role of interferon (IFN)-γ in MUC5AC expression in human bronchial epithelial cells. MethodsHuman pulmonary mucoepidermoid carcinoma cell line (NCI-H292) and normal human bronchial epithelial (NHBE) cells were used to assess the effects of IFN-γ on MUC5AC transcription. ResultsTransforming growth factor (TGF)-α and double-stranded RNA (polyI:C)-induced MUC5AC mRNA and protein expression was repressed by IFN-γ in a concentration-dependent manner. IFN-γ showed limited effects on TGF-α and polyI:C-induced activation of epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK). A chromatin immunoprecipitation assay indicated that Sp1 bound to its cognate sequence located on the MUC5AC promoter. The Sp1 inhibitor mithramycin A inhibited MUC5AC mRNA expression, implying a critical role for Sp1 in MUC5AC induction. Importantly, IFN-γ impeded Sp1 binding to the MUC5AC promoter. ConclusionsThese results suggest that IFN-γ represses MUC5AC expression, disturbing binding of Sp1 to its target sequences.

Effect of methyleugenol on expression of MUC5AC in nasal mucosa of rats with allergic rhinitis

Objective: To investigate the effect of methyleugenol on expression of MUC5AC in nasal mucosa of rats with allergic rhinitis (AR). Methods: Seventy-two Wistar rats were randomly divided into 6 groups:normal control group, AR group, loratadine group, low-dose methyleugenol group, middle-dose methyleugenol group and high-dose methyleugenol group with 12 rats in each group. AR was induced by intraperitoneal injection of ovalbumin in latter 5 groups. 10 mg loratadine q.d was given to rats in loratadine group by gavage; and 10 mg/kg, 20 mg/kg and 40 mg/kg methyleugenol were given by gavege q.d to rats in low-, middle-and high-dose methyleugenol groups, respectively. Nasal mucosa samples were obtained from rats at 1, 2, 4 and 6 weeks after drug intervention. The expression of MUC5AC protein and mRNA in nasal mucosa was detected by immunohistochemistry and real-time fluorescence quota PCR (RT-PCR), respectively. Results: Compared with AR, the percentage of cells staining positively for MUC5AC protein and the relative quantity of MUC5AC mRNA in middle-and high-dose methyleugenol groups were significantly decreased after 2 and 4 weeks of drug intervention (P<0.05), but no such decrease was observed in low-dose methyleugenol group at all time points (P>0.05). The percentage of cells with positive expression of MUC5AC protein and mRNA in loratadine group were significantly decreased after 1 week of administration (P<0.05). The percentage of cells with positive MUC5AC protein in middle-dose methyleugenol group was higher than that in loratadine group (P<0.05) after 6 week of drug intervention, but the difference was not seen in high-dose group (P>0.05). There was no significant difference in relative quantities of MUC5AC mRNA after 4 weeks of administration between high-and middle-dose methyeugenol groups and loratadine group (P>0.05). Conclusion: Methyleugenol can attenuate AR through inhibiting the expression of MUC5AC mRNA and protein in nasal mucosa of AR rats.

Cold-inducible RNA binding protein regulates mucin expression induced by cold temperatures in human airway epithelial cells

Mucus overproduction is an important manifestation of chronic airway inflammatory diseases, however, the mechanisms underlying the association between cold air and mucus overproduction remain unknown. We found that the expression of the cold-inducible RNA binding protein (CIRP) was increased in patients with chronic obstructive pulmonary disease (COPD). In the present study, we tested whether CIRP was involved in inflammatory factors and mucin5AC (MUC5AC) expression after cold stimulation and investigated the potential signaling pathways involved in this process. We found that CIRP was highly expressed in the bronchi of COPD patients. The expression of CIRP, interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) were increased, and the CIRP was localized in cytoplasm after cold stimulation. MUC5AC mRNA and protein expression levels were elevated in a temperature- and time-dependent manner after cold stimulation and were associated with the phosphorylation of ERK and NF-κB, which reflected their activation. These responses were suppressed by knockdown of CIRP with a specific siRNA or the ERK and NF-κB inhibitors. These results demonstrated that CIRP was expressed in the bronchi of human COPD patients and was involved in inflammatory factors and MUC5AC expression after cold stimulation through the ERK and NF-κB pathways.

Inhibition of suppressor of cytokine signaling 1 on lipopolysaccharide-induced mucin5AC hypersecretion and the mechanism in human bronchial epithelial cells

To explore the inhibitory role of suppressor of cytokine signaling 1 (SOCS1) in lipopolysaccharide (LPS)-induced mucin5AC (MUC5AC) hypersecretion and the potential mechanism involved in this process. The human bronchial epithelial cells 16HBE were divided into 0, 0.5, 1, 6, 12 and 24 h groups according to the time of LPS challenge. In gain- and loss- of functions experiments, wild-type SOCS1 and SOCS1-targeted siRNA (SOCS1-siRNA) were synthesized to identify the function of SOCS1 in LPS-mediated MUC5AC hypersecretion, and named wild-type SOCS1 group and SOCS1-siRNA group, respectively, and the non-transfected group and non-targeted siRNA group were used as controls. In Filgotinib group, the specific inhibitor of Janus kinase 1 (JAK1), Filgotinib, was used to detect the role of JAK1/signal transducer and activator of transcription 1 (STAT1) signaling pathway in LPS challenge, and the aqueous physiological buffer group was used as the control. The production of MUC5AC protein was measured by enzyme linked immunosorbent assay (ELISA), and the amount of MUC5AC protein was normalized to the total protein in cell lysates and was expressed as μg/mg cell lysates. The proteins expressions of SOCS1, phosphorylation of JAK1 and STAT1 were measured by Western blot, and the total expression of its protein (for JAK1 and STAT1) or β-actin (for SOCS1) was used as the loading control. Compared to 0 h group, LPS induced a robust induction in MUC5AC expression, the expression levels of MUC5AC in 0, 0.5, 1, 6, 12 and 24 h groups were (2.86±0.20), (3.42±0.29), (3.43±0.12), (10.22±0.96), (14.56±1.12), (14.15±1.34) μg/mg, in association with a decrease of SOCS1 expression. And in 6 h group, the expressions of MUC5AC and SOCS1 were both medium up-regulated (all P<0.05). Consequently, the application of LPS for 6 h was selected as the optimal responses period in the ensuing experiments. Compared to the expression of MUC5AC protein in non-transfected group, high level of SOCS1 in wild-type SOCS1 group led to a reduced phosphorylation of JAK1/STAT1, as well as Filgotinib did, thereby suppressing excessive MUC5AC production in wild-type SOCS1 group and Filgotinib group [(4.04±0.65), (7.02±0.83) vs (10.37±1.00) μg/mg] (all P<0.05). Conversely, compared to the expression of MUC5AC in non-targeted siRNA group, down-regulation of SOCS1 in SOCS1-siRNA group promoted the phosphorylation of JAK1/STAT1, and then further increased MUC5AC production [(13.69±1.32) vs (11.01±1.41) μg/mg] (all P<0.05). These results show that SOCS1 suppresses LPS-promoted MUC5AC hypersecretion through the inhibition of JAK1/STAT1 signaling pathway.

Glucagon Like Peptide-1 (GLP-1) Modulates OVA-Induced Airway Inflammation and Mucus Secretion Involving a Protein Kinase A (PKA)-Dependent Nuclear Factor-κB (NF-κB) Signaling Pathway in Mice.

Asthma is a common chronic pulmonary inflammatory disease, featured with mucus hyper-secretion in the airway. Recent studies found that glucagon like peptide-1 (GLP-1) analogs, including liraglutide and exenatide, possessed a potent anti-inflammatory property through a protein kinase A (PKA)-dependent signaling pathway. Therefore, the aim of current study was to investigate the value of GLP-1 analog therapy liraglutide in airway inflammation and mucus secretion in a murine model of ovalbumin (OVA)-induced asthma, and its underlying molecular mechanism. In our study, BALB/c mice were sensitized and challenged by OVA to induce chronic asthma. Pathological alterations, the number of cells and the content of inflammatory mediators in bronchoalveolar lavage fluid (BALF), and mucus secretion were observed and measured. In addition, the mRNA and protein expression of E-selectin and MUC5AC were analyzed by qPCR and Western blotting. Then, the phosphorylation of PKA and nuclear factor-κB (NF-κB) p65 were also measured by Western blotting. Further, NF-κB p65 DNA binding activity was detected by ELISA. OVA-induced airway inflammation, airway mucus hyper-secretion, the up-regulation of E-selectin and MUC5AC were remarkably inhibited by GLP-1 in mice (all p < 0.01). Then, we also found that OVA-reduced phosphorylation of PKA, and OVA-enhanced NF-κB p65 activation and NF-κB p65 DNA binding activity were markedly improved by GLP-1 (all p < 0.01). Furthermore, our data also figured out that these effects of GLP-1 were largely abrogated by the PKA inhibitor H-89 (all p < 0.01). Taken together, our results suggest that OVA-induced asthma were potently ameliorated by GLP-1 possibly through a PKA-dependent inactivation of NF-κB in mice, indicating that GLP-1 analogs may be considered an effective and safe drug for the potential treatment of asthma in the future.

Mo1973 Immunohistochemical Markers Differentiating Colonic Sessile Serrated Adenomas/Polyps (SSA/Ps) From Hyperplastic Polyps

Differentiating SSA/Ps from hyperplastic polyps (HPs), with little or no risk for progression to cancer, can be a major challenge using conventional endoscopic and histological examinations. SSA/Ps are frequently right sided, flat and have a mucus cap. The goal of this study was identifying potential immunohistochemical (IHC) markers that help to differentiate SSA/ Ps from HPs. Methods: We compared RNA sequencing transcriptional signatures of SSA/Ps (n=15) and control (n=20) colonic mucosa from patients undergoing screening colonoscopy. Reads from the analysis were aligned to the GRCh37/Hg19 human reference genome and filtered for high quality alignments (http://novocraft.com). Hierarchical clustering of log2 ratios comparing SSA/Ps and controls were performed and mined for candidate IHC targets. IHC analysis was performed on formalin-fixed paraffin-embedded sections of 12 SSA/Ps, 10 HPs, 5 adenomas, 5 colon cancers and 5 control colon specimens to assess staining for selected antigens. Expression of MUC5AC and TFF1 protein were quantified with ImageJ software. Results: Bioinformatics analysis identified 1,294 (≥1.5-fold change) differentially expressed annotated genes (false discovery rate (FDR) <0.05) in SSA/Ps as compared to normal controls. The dataset was mined for the most highly expressed genes and genes with possible biological functions related to SSA/Ps. A total of 249 genes were overexpressed ≥5fold in SSA/Ps compared to controls. SSA/Ps markedly overexpressed MUC5AC (582-fold), a component of the gastric mucus layer, and a secretory protein that may stabilize mucin layers, trefoil factor 1 (TFF1, 79-fold). Neither protein is typically expressed in normal colonic mucosa. SSA/Ps exhibited strong co-localized staining for both proteins (Fig. 1 and 2). Intense MUC5AC staining was primarily seen in the serrated crypts, whereas expression in adjacent non-serrated mucosa was identical to controls. Conversely, HPs showed only weak patchy staining of MUC5AC and variable TFF1 staining that was infrequently colocalized. Normal colon had no detectable MUC5AC staining and minimal TFF1 staining. Conventional adenomas showed trace MUC5AC and TFF1 staining. Conclusions: RNA-seq and IHC analysis showed markedly increased expression of two mucin-associated genes/ proteins in SSA/Ps, MUC5AC and TFF1, which are not typically expressed in normal colonic mucosa or adenomas. There was also intense co-localization of MUC5AC and TFF1 in SSA/ Ps but not in HPs. These results identify intense co-localized expression of MUC5AC and TFF1 as a possible diagnostic marker that would aid differentiating SSA/Ps from HPs. Further studies will be needed with larger numbers of SSA/Ps. Since MUC5AC has been linked to signaling related to bacteria, these findings suggest that luminal factors may play a role in the formation or progression of SSA/Ps.

Naringenin may block RSV-induced mucous hypersecretion in A549 cell via JNK/AP-1 signaling pathway

Naringenin has been reported to attenuate Mucin (MUC) 5AC secretion in many pathological models. Many stimuli activate MUC5AC expression through JNK/AP-1 signaling pathways. We hypothesized that naringenin may have inhibitory effects on mucous hypersecretion by modulating MUC5AC production and inhibiting JNK/AP-1 signaling pathways. The cell model of mucous hypersecretion was made by human lung adenocarcinoma epithelial (A549) cells stimulated by RSV. A549 cells were subcultured and then randomly divided into 7 groups, which were designated as group C (cell control group), groups R1-3 (cells were infected with RSV at the multiplication of infection (MOI) of 0. 5, 1. 0, 5. 0), groups N1-2 (cells infected with viruses in presence of Nar 30 - 100 mol/L), groups N3-4 (uninfected cells treated with Nar 30 - 100 µmol/L), group D (DMSO), group S (cells infected with viruses in presence of SP600125). After incubating for 24 hrs, the expression of MUC5AC at mRNA and protein level in the groups were determined by real-time quantitative PCR and enzyme-linked immunosorbent assay (ELISA). The protein expression changes of JNK, p-JNK and AP-1 were measured by Western blotting. The expressions of MUC5AC protein and mRNA in all RSV infected groups were significantly higher than that in group C in a dose-dependent manner (all P <0. 05). Nar of 30 and 100 µmol/L significantly and dose-dependently decreased RSV-induced secretion of MUC5AC protein in cell supernatant and expression of MUC5AC mRNA (P <0. 05). The relative content of p-JNK, AP-l in R2 groups were 3. 31 ± 0. 34 and 1. 94 ± 0. 05. Theyfrweremtgnificanty increased as compared with group C (both 1. 00 ± 0. 00) (all P <0. 05). The levels of p-JNK in N2 and S groups were 2. 10 ± 0. 20. 27 and 1.±97 ± 0. 16. The levels of AP-1 in N2 and S groups were 1. 40 ± 0. 03, 1. 36 ± 0. 05. Nar and SP600125 led to a largest decrease in levels of p-JNK and AP-1 when compared with group R2 (P <0. 05). The MUC5AC protein in group R2 was (48. 19 ± 0. 47) µg/L. The protein expression of MUC5AC in group R2 was significantly higher than that in group C [(36. 67 ± 1. 50) g/L] with a statistically significant difference (P <0. 05). The protein expression of MUC5AC in groups N2 and S were(43. 17 ± 1. 06) µg/L, (44.±02 ± 0. 99) µg/L, Nar and SP600125 remarkably inhibited RSV-induced secretion of MUC5AC in supernatant of A549 cells (P < 0. 05). Naringenin might be able to block RSV-induced mucous

MUC5AC hypomethylation is a predictor of microsatellite instability independently of clinical factors associated with colorectal cancer.

Colorectal cancers (CRC) with microsatellite instability (MSI) display unique clinicopathologic features including a mucinous pattern with frequent expression of the secreted mucins MUC2 and MUC5AC. The mechanisms responsible for this altered pattern of expression remain largely unknown. We quantified DNA methylation of mucin genes (MUC2, MUC5AC, MUC4) in colonic cancers and examined the association with clinicopathological characteristics and molecular (MSI, KRAS, BRAF, and TP53 mutations) features. A control cohort was used for validation. We detected frequent hypomethylation of MUC2 and MUC5AC in CRC. MUC2 and MUC5AC hypomethylation was associated with MUC2 and MUC5AC protein expression (p = 0.004 and p < 0.001, respectively), poor differentiation (p = 0.001 and p = 0.007, respectively) and MSI status (p < 0.01 and p < 0.001, respectively). Interestingly, MUC5AC hypomethylation was specific to MSI cancers. Moreover, it was significantly associated with BRAF mutation and CpG island methylator phenotype (p < 0.001 and p < 0.001, respectively). All these results were confirmed in the control cohort. In the multivariate analysis, MUC5AC hypomethylation was a highly predictive biomarker for MSI cancers. MUC5AC demethylation appears to be a hallmark of MSI in CRC. Determination of MUC5AC methylation status may be useful for understanding and predicting the natural history of CRC.

Effects of tumor necrosis factor-α converting enzyme on mucous hypersecretion in inflammatory airway

To investigate the effect of tumor necrosis factor-α converting enzyme (TACE) on mucous hypersecretion in inflammatory airway. Mucous hypersecretion model of human lung adenocarcinoma cells A549 was induced by human neutrophil elastase (HNE), and TNF-α converting enzyme inhibitor-1 (TAPI-1), an inhibitor of TACE, was chosen for the inference study. The expression of MUC5AC and TACE was examined. Th e cells were divided into 5 groups: a negative control group, HNE1 (15 nmol/L) group, HNE2 (25 nmol/L) group, HNE3 (50 nmol/L) group and TAPI-1 group. RT-PCR was used to examine MUC5AC and TACE mRNA expression. The protein expression of TACE and MUC5AC was examined by Western blot and ELISA, respectively. HNE induced the TACE and MUC5AC mRNA and protein expression in a dose-dependent manner. Compared with the control group, the increases were all significantly increased in the three dosages of HNE group (P< 0.01). The HNE-induced TACE and MUC5AC mRNA and protein expression were dramatically attenuated in the presence of TAPI-1, an inhibitor of TACE (P< 0.01). TACE participated cell signalling pathway of airway mucous hypersecretion, and could down regulation the level of inflammation airway mucous hypersecretion.

Macrolides Attenuate Phorbol Ester-Induced Tumor Necrosis Factor-α and Mucin Production from Human Airway Epithelial Cells

Background/Aims: Macrolide antibiotics are effective drugs in chronic bronchiolitis and chronic rhinosinusitis with mucus hypersecretion. However, the mechanism of action is unclear. This study was designed to investigate the effect of azithromycin (AZM; 15-membered) and midecamycin acetate (MDM; 16-membered) on MUC5AC and MUC2 gene expression and secretion from human airway epithelial cells. The effects of the two macrolides on tumor necrosis factor-α (TNF-α) release were also examined. Methods: Confluent NCI-H292 human mucoepidermoid airways epithelial cells were pretreated with AZM or MDM for 2 h and then stimulated with 200 nmol/l phorbol 12-myristate 13-acetate (PMA) for 8 h. The MUC5AC and MUC2 gene expression was measured by real-time quantitative RT-PCR. Total mucin in culture supernatants was measured using enzyme-linked lectin assay. Enzyme-linked immunosorbent assay was used to determine MUC5AC, MUC2 and TNF-α released by the cells. Results: AZM and MDM attenuated PMA-induced MUC5AC and MUC2 gene and protein expression in NCI-H292 cells. They also suppressed PMA-mediated TNF-α in the cells. Conclusion: The present study demonstrates that AZM and MDM suppress the synthesis of mucin and TNF-α from human airway epithelial cells.