This Key Event Relationship is licensed under the Creative Commons BY-SA license. This license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. If you remix, adapt, or build upon the material, you must license the modified material under identical terms.

Relationship: 2858


A descriptive phrase which clearly defines the two KEs being considered and the sequential relationship between them (i.e., which is upstream, and which is downstream). More help

Increase, goblet cell number leads to Increase, Mucin production

Upstream event
The causing Key Event (KE) in a Key Event Relationship (KER). More help
Downstream event
The responding Key Event (KE) in a Key Event Relationship (KER). More help

Key Event Relationship Overview

The utility of AOPs for regulatory application is defined, to a large extent, by the confidence and precision with which they facilitate extrapolation of data measured at low levels of biological organisation to predicted outcomes at higher levels of organisation and the extent to which they can link biological effect measurements to their specific causes.Within the AOP framework, the predictive relationships that facilitate extrapolation are represented by the KERs. Consequently, the overall WoE for an AOP is a reflection in part, of the level of confidence in the underlying series of KERs it encompasses. Therefore, describing the KERs in an AOP involves assembling and organising the types of information and evidence that defines the scientific basis for inferring the probable change in, or state of, a downstream KE from the known or measured state of an upstream KE. More help

AOPs Referencing Relationship

AOP Name Adjacency Weight of Evidence Quantitative Understanding Point of Contact Author Status OECD Status
EGFR Activation Leading to Decreased Lung Function adjacent High Moderate Karsta Luettich (send email) Under development: Not open for comment. Do not cite Under Development

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) that help to define the biological applicability domain of the KER.In general, this will be dictated by the more restrictive of the two KEs being linked together by the KER.  More help
Term Scientific Term Evidence Link
Homo sapiens Homo sapiens NCBI
Mus musculus Mus musculus NCBI
Rattus norvegicus Rattus norvegicus NCBI
Mustela furo Mustela putorius furo NCBI

Sex Applicability

An indication of the the relevant sex for this KER. More help
Sex Evidence

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
Not Otherwise Specified

Key Event Relationship Description

Provides a concise overview of the information given below as well as addressing details that aren’t inherent in the description of the KEs themselves. More help

An increase in goblet cell numbers arises from proliferation of this particular cell population (goblet cell hyperplasia) and/or from transdifferentiation of other specialized cell types, such as ciliated cells and club cells, into goblet cells (goblet cell metaplasia; Reader et al, 2003; Evans et al., 2004; Tesfaigzi, 2006). Goblet cell hyperplasia (GCH) is a common feature of airway epithelia in asthma and other respiratory diseases and can arise from airway injury following exposure to, for example, allergens, pathogens, or cigarette smoke (Miyabara et al., 1998; Nagao et al., 2003; Saetta et al., 2000; Walter et al., 2002; Hao et al., 2012, 2013, 2014; Lukacs et al., 2010; Yageta et al., 2014; Hegab et al., 2007; Silva and Bercik, 2012; Kim et al., 2016). Goblet cell metaplasia (GCM) is a key feature of remodeled airways observed in both asthma and chronic obstructive pulmonary disease (COPD; Kato et al., 2020; Kuchibhotla and Heijink, 2020; Nie et al., 2012). Since goblet cells are mucin-producing cells, an increase in goblet cell numbers will consequently lead to an increase (from basal levels) in mucin production, in fact methods for goblet cell detection and quantification include measurement of mucin levels with specific antibodies or staining of mucous glycoconjugates (Alcian Blue/periodic acid Schiff (AB/PAS) stain). Correlation and co-incidence between increase in goblet cell numbers and increased mucin production is shown in multiple studies.  

Evidence Collection Strategy

Include a description of the approach for identification and assembly of the evidence base for the KER. For evidence identification, include, for example, a description of the sources and dates of information consulted including expert knowledge, databases searched and associated search terms/strings.  Include also a description of study screening criteria and methodology, study quality assessment considerations, the data extraction strategy and links to any repositories/databases of relevant references.Tabular summaries and links to relevant supporting documentation are encouraged, wherever possible. More help

The relevant research articles supporting this KER were identified using keywords: “goblet“ AND “mucin” or “mucus” or “MUC5AC”. Referenced articles within retrieved studies and reviews were also consulted. Not all retrieved articles were included as a support for this KER since they generally repeat the same conclusions listed in the evidence texts below. 

Evidence Supporting this KER

Addresses the scientific evidence supporting KERs in an AOP setting the stage for overall assessment of the AOP. More help

This KER is inferred in that goblet cells are specialized mucin production cells and widely accepted measurement methods for counting goblet cells are based on staining of mucous glycoconjugates. There is indirect evidence demonstrating an increase in mucin production along the presence of GCH or GCM in airway epithelia following stressor exposures, judged by increased MUC5AC mRNA and protein expression, histopathological examination, increase in AB/PAS staining, and/or MUC5AC-positive antibody staining (Alimam et al, 2000; Hegab et al., 2007; An et al., 2013; Zhou et al., 2016). Increase in goblet cell number and mucin overproduction are also linked experimentally through genetic modification. For example, conditional deletion of transcription factor Foxa2 in respiratory epithelial cells of the developing mouse lung results in goblet cell hyperplasia in bronchi and bronchioles at post-natal day 16 and later (evidenced by histology), which was accompanied by extensive AB/PAS and MUC5AC staining (Wan et al., 2004). Similarly, Muc1-knockout rats exposed to cigarette smoke were protected from goblet cell metaplasia and MUC5AC overproduction (Kato et al., 2020). 

Biological Plausibility
Addresses the biological rationale for a connection between KEupstream and KEdownstream.  This field can also incorporate additional mechanistic details that help inform the relationship between KEs, this is useful when it is not practical/pragmatic to represent these details as separate KEs due to the difficulty or relative infrequency with which it is likely to be measured.   More help

This KER is inferred from the functional characteristic of the goblet cells whose primary role is mucin production, hence the assumption that increase in goblet cell numbers also increases mucin production is highly plausible. Studies in human cells, mice and rats demonstrate that mucin content or MUC5AC mRNA and protein expression increase in the presence of histologically confirmed GCH or GCM. While both events are measured in parallel and causal evidence is missing, our confidence remains high for the plausibility of this relationship. 

Uncertainties and Inconsistencies
Addresses inconsistencies or uncertainties in the relationship including the identification of experimental details that may explain apparent deviations from the expected patterns of concordance. More help

MUC5B, mainly present in submucosal glands, is the other main mucin found in human airways (Rose and Voynow, 2002). MUC5AC and MUC5B often both increase with goblet cell numbers increase in patients with respiratory diseases (Burgel et al., 200). However, depending on the causative agent, dominant MUC5B immunophenotypes are observed with no induction in MUC5AC (Silva and Bercik, 2012). Sprague-Dawley rats receiving one intratracheal dose of LPS developed GCH in their terminal bronchioles that was not MUC5AC and PAS-positive. An analysis in human bronchus epithelial cells confirmed that when challenged with supernatant from LPS-stimulated macrophages, goblet cells induced MUC5B levels but MUC5AC was inhibited. 

Known modulating factors

This table captures specific information on the MF, its properties, how it affects the KER and respective references.1.) What is the modulating factor? Name the factor for which solid evidence exists that it influences this KER. Examples: age, sex, genotype, diet 2.) Details of this modulating factor. Specify which features of this MF are relevant for this KER. Examples: a specific age range or a specific biological age (defined by...); a specific gene mutation or variant, a specific nutrient (deficit or surplus); a sex-specific homone; a certain threshold value (e.g. serum levels of a chemical above...) 3.) Description of how this modulating factor affects this KER. Describe the provable modification of the KER (also quantitatively, if known). Examples: increase or decrease of the magnitude of effect (by a factor of...); change of the time-course of the effect (onset delay by...); alteration of the probability of the effect; increase or decrease of the sensitivity of the downstream effect (by a factor of...) 4.) Provision of supporting scientific evidence for an effect of this MF on this KER. Give a list of references.  More help
Response-response Relationship
Provides sources of data that define the response-response relationships between the KEs.  More help

The following examples all describe the parallel increase in goblets cells and mucin production after exposure to a noxious agent. In some of these examples, the response-response relationship is reinforced by the use of an antagonist or inhibitor treatment that attenuates or blocks the stressor-induced goblet cell proliferation and concomitantly reduces mucin mRNA and protein expression. 

  • Intranasal instillation of 0.1 mg LPS (E.coli 0111:B4) once a day for 3 consecutive days induced GCM in rat nasal epithelium (as judged by histopathology), with an approx. 50% increase in AB/PAS-stained epithelium compared to untreated controls. A treatment (intraperitoneal (i. p.) injection of 1 or 10 mg/kg) with of the epithelial growth factor receptor (EGFR) inhibitor AG1478 one hour before each LPS administration significantly inhibited LPS-induced GCM (histology assessment) and mucus production. Intranasal instillation of AG1478 one hour after LPS instillation resulted in a similar inhibition of both GCM and mucus production (Takezawa et al., 2016).  

  • Intratracheal instillation of agarose plugs (0.7- to 0.8-mm diameter; 4% agarose type II) in male Fischer 344 rats caused GHC, evidenced by histology and AB/PAS staining. In the airways containing the plugs, goblet cell numbers increased from 0 cells/mm basal lamina to 13.1±5.6, 25.7±15.0, and 51.5±9.0 cells/mm basal lamina after 24, 48, and 72 h, respectively. The percentage of the total length of epithelium staining positively with AB/PAS increased from 0.1 ± 0.1% in control animals to 4.7 ± 1.4, 13.3 ± 0.7, and to 19.1 ± 0.7% at 24, 48, and 72 h, respectively. Muc5ac gene expression was found preferentially in cells that were AB/PAS-positive and increased in a time-dependent manner (Lee et al., 2000).   

  • Analysis of lungs from BALB/c mice sensitized with five i. p. injections of 100 µg ovalbumin (OVA) followed by intranasal instillation of 100 µg OVA, as well as from BALB/c mice treated with 5 µg IL-13 (intranasal instillation on three consecutive days) revealed clear airway GCM 24 h post treatment. Marked MUC5AC mRNA and protein expression (apomucin and glycosylated mucin) were observed in lungs from OVA- and IL-13-treated mice but not in lungs from control saline-treated mice (Alimam et al. 2000). 

  • BALB/c mice were sensitized to OVA with 4 i. p. injections (20 µg each) administered at weekly intervals. They were subsequently exposed for 30 min to an aerosol containing 2.5% OVA. At 3 days post challenge, ca. 60% of the cells in proximal airways were AB-PAS-positive. The number of these cells peaked at day 7 (> 30-fold increase compared with unsensitized controls). The volume density of mucin concomitantly increased on day 3 post challenge with peak measures on day 7 (15-fold increase over baseline) (Evans et al., 2004). 

  • Brown–Norway rats were sensitized by an i. p. injection with 1 mg OVA and 200 mg Al(OH)3 in 1mL of sterile saline on days 0 and 7. The rats were then exposed to aerosolized 1% (w/v) OVA or sterile saline for 30 min on days 14–16. Distinct GCH (evidenced by AB/PAS staining) was observed in the epithelium throughout the airways of the OVA-sensitized and -challenged rats 24 h after the final OVA challenge (on day 17), and the staining progressed to 7-fold increase further on day 24. Marked MUC5AC immunoreactivity was observed in goblet cells similar to the AB/PAS staining pattern. (Takeyama et al., 2008). 

  • Oropharyngeal inspiration of neutrophil elastase (50 µg (43.75 units/40 µl PBS)) by BALB/c mice on day 1, 4, and 7, resulted in GCM as observed on days 8, 11 and 14. The histological mucus index (HMI, defined a grading system of PAS-positive staining, from 0 (no PAS staining) to 4 (>75% of airways epithelium stained) increased from 1 (25% stained area) on day 8 to ca. 2 (26-50%) on day 11, then decreased to 1.3 on day 14, while the HMI remained close to 0 in controls. Muc5ac mRNA expression qualitatively corresponded to AB/PAS histology evolving form 1.64 ± 0,49 on day 8, to 13.53 ± 3.28 on day 11, and 8.62 ± 1.48 on day 14. Muc5ac protein expression followed the same trend (Voynow et al., 2004). 

  • Lungs of C57BL6/J mice treated with house dust mite (HDM) extract (intranasal instillation of 50 µg HDM, 5 days per week for 3 weeks) showed increase in goblet cell number as judged by increased PAS staining in the airway epithelium with concurrent ca. 10-fold increase in Muc5ac expression (Habibovic et al., 2016). 

  • Pyocyanin, a redox-active exotoxin of Pseudomonas aeruginosa, caused increase in goblet cell numbers in mouse airways after 3-week daily intranasal inoculation (25 µg/day). Development of GCM in small terminal bronchioles (88-fold more PAS-stained cells) was paralleled with a 6.4-fold and a 11.4-fold increase in MUC5B-positive cells in large bronchi and terminal bronchioles respectively (Hao et al., 2012). 

  • Male Sprague–Dawley rats that were exposed to 3 ppm acrolein for 6 h a day, for 2 x 5 days separated by a 2-day rest, developed GCM (as judged by histopathology), increasing the % AB/PAS-positive stained epithelium from ca. 5% (in air controls) to 35%. This was accompanied by a nearly 15% increase in Muc5ac-positive stained cells, a ca. 3-fold increase in Muc5ac mRNA expression and a ca. 4-fold increase in protein expression. A treatment with simvastatin, a statin inhibitor of EGFR and extracellular signal-regulated kinase (ERK) activation one day prior exposure to acrolein, significantly inhibited the increase of AB/PAS staining in airway epithelium in a dose-dependent matter. The number of Muc5ac-positive cells was also significantly attenuated, as well as the Muc5ac protein levels in lung homogenates (Chen et al., 2010). 

  • Exposure of female Sprague-Dawley rats to wood smoke (total of 40 g of China fir sawdust smoldered) for 1 h four times per day, five days per week, for three months caused GCM in the airways (as judged by histopathology), a 2-fold increase in Muc5ac gene expression, an increase in the % AB/PAS-positive stained epithelium from approx. 6% (air controls) to ca. 17%, an increase in Muc5ac-positive stained cells from approx. 5% (air controls) to ca. 25%  (Huang et al., 2017). 

  • In Sprague-Dawley rats that were whole-body exposed to 4% (v/v air) cigarette smoke (CS) for 1 h daily, for 56 days, the number of goblet cells in the bronchial epithelium significantly increased (ca. 10 cells/mm epithelium in air controls vs 60 cells/mm in CS-treated animals), and the number of Muc5ac-positive cells increased from ca. 20 cells/mm to ca. 80 cells/mm. A treatment with (-)-Epigallocatechin-3-gallate (EGCG, major catechin in green tea, 50 mg/kg oral gavage every other day) significantly reduced the number of goblet cells (PAS-stained) as well as the number of MUC5AC positive cells (Liang et al., 2017). 

  • Bronchial biopsies and epithelial brushings of smokers revealed a significantly larger number of goblet cells compared with healthy control subjects, leading to a 2.2-fold increase in the volume of stored mucin in the epithelium per surface area of basal lamina (4.32 ± 0.55 µm3/µm2 vs 1.94 ± 0.31 µm3/µm2 in controls) (Innes et al., 2006). 

  • The large airways of mice that were whole body exposed to CS of 10 cigarettes (160–180 mg/m3 TPM; TE-10, Teague Enterprises) for 2 h a day, 5 days a week, for up to 12 weeks, exhibited GCH and increased mucus production, evidenced by histology and increases in the numbers of PAS-positive goblet cells (approx. 15% compared to control), Mu5ac mRNA expression (approx. 5-fold increase compared to controls), and Muc5ac-positive cells (approx. 50% compared to control; Zhou et al., 2016). 

  • Ferrets that were exposed to CS (3R4F reference cigarette) for 1 h, twice daily for 6 months developed GCH and GCM in medium and small airways, evidenced by histopathological examination of AB/PAS-stained lung tissues. Mucus expression measured by PAS-positive goblet cell area, normalized by the size of the airway lumen to account for cell variation due to airway diameter, was 60% (0.042% ± 0.025% smoke vs. 0.025% ± 0.013% air control; P = 0.06) higher in smoke-exposed airways than in control airways. Muc5b and Muc5ac staining was greater in smoke-exposed ferrets, but patchy staining made quantification impossible (Raju et al., 2016). 

  • In primary human bronchial epithelial cells differentiated at the air-liquid interface, basolateral treatment with 10 ng/mL IL-13 increased the number of goblet cells from 0.2 ± 0.1 to 15.9 ± 1.1, the number of PAS-positive cells from 2.5 ± 1.5 to 28.2 ± 0.7, and the number of MUC5AC-positive cells from 0.1 ± 0.1 to 25.7 ± 1.0. Reversely, addition of clarithromycin to the IL-13 treatment reduced in a dose dependent manner (maximum with 32 µg/mL) the number of goblet cells from 15.9 ± 1.1 to 4.1 ± 2.5, the number of PAS-positive cells from 28.2 ± 0.7 to 10.7 ± 3.6, and the number of MUC5AC-positive cells from 25.7 ± 1.0 to 5.2 ± 2.9 (Tanabe et al., 2011). 

  • Similarly, a treatment of 3D bronchial organotypic cultures with 5 ng/mL IL-13 for 14 days induced GCH (histopathology assessment). MUC5AC mRNA expression significantly increased (ca. 10-fold) compared with cells treated with DMSO, and MUC5AC protein concentration measured in the supernatant also increased (1.8-fold) compared with DMSO-treated control (Mishina et al., 2015). 

  • In nasal polyp tissues from 8 patients with nasal polyposis, hyperplastic epithelium occupied a mean of 75% (range, 44%-100%). Nasal polyp tissue contained a significantly greater percentage of AB/PAS-and MUC5AC-stained area (approx. 51%) than in control epithelium (approx. 20 %). In nasal polyps, hyperplastic epithelium contained significantly larger numbers of MUC5AC-stained areas (ca. 40%) than in normal pseudostratified epithelium (ca. 15%; Burgel et al., 2000).  

  • Similarly, increase in goblet cell numbers was seen in nasal polyp tissues from 25 patients but not in healthy controls, as evidenced by more PAS-positive epithelial cells (PAS staining index 1.9 [1.3, 2.2] vs 0.7 [0.4, 1.2] in controls). This was accompanied by increased MUC5AC staining, with a mean staining score of 2.2 [1.7, 3.0] in polyp tissues vs 0.6 [0.4, 1.1] in normal controls, and increased MUC5AC gene expression, with levels of 4.4 [2.3, 6.3] in polyp tissues vs 1.2 [0.4, 2.2] in normal controls (Xia et al., 2014). 

  • In patients with COPD, goblet cell increase in lung tissues was confirmed with DAB/PAS staining, a staining specifically targeting mucosubstances such as mucin in cells, (goblet cell rate 0.20 ± 0.10% vs 0.13 ± 0.06% in healthy controls). The rate of MUC5AC expression was also significantly higher in COPD patients (0.27 ± 0.09%) than in healthy control (0.20 ± 0.10%) (Ma et al., 2005). 

  • Healthy smokers had greater goblet cell density (9.80±3.49 cells/mm) than nonsmokers (2.31±1.81 cells/mm) revealed by PAS staining in endobronchial mucosal biopsies. Healthy smokers also had a greater mucin volume density (26.35±10.96 μL/mm2) compared with nonsmokers (5.77±4.34 μL/mm2) (Kim et al., 2015). 

  • Intragastric administration in Sprague-Dawley rats of the thromboxane A2 receptor antagonist seratrodast prior exposure to CS (1h/day, 6 days/week for 4 weeks) significantly attenuated the CS-induced increase in AB/PAS-stained goblets cells and Muc5ac expression in airways (An et al., 2015). 

  • An i. p. treatment of AG1478 (EGFR inhibitor) or/and niflumic acid (calcium activated chloride channels (CLCAs) inhibitor) inhibited CS (6 non-filtered cigarettes/day, 5 days/week, for 2 to 28 days) -induced increase in percentage area of goblet cells (measured by mucin staining) and MUC5AC mRNA expression in rat respiratory epithelium (Hegab et al, 2007) 

  • Airway GCM induced by intratracheal instillation of LPS (200-300 µg) in Sprague-Dawley rats was significantly reduced by daily gavage of a matrix metalloproteinase inhibitor (MMPI, 20 mg/kg) starting 3 days prior of LPS administration and until euthanasia. Area of AB/PAS-stained goblet cells was 3.37 ± 2.36% in control, 71.6 ± 2.56% in LPS and 14.7 ± 4.33% in LPS + MMPI groups. MUC5AC expression was also significantly reduced (6.5-fold) in LPS+MMPI group compared with the LPS group (Kim et al., 2004). 

  • In Sprague-Dawley rats, CS (5 cig twice daily for 4 weeks)- induced increase in goblet cells significantly decreased with i. p. hydrogen-rich saline treatments applied 30 min prior to CS exposure. The AB/PAS-stained area as well as MUC5AC levels were decreased by approx. 50% by hydrogen-rich saline pretreatment (Ning et a., 2013). 

  • CS exposure (5 cig twice daily for 4 weeks) increased goblet cell numbers in mouse airways as shown by an increased area of AB/PAS-staining and Muc5ac-positive staining. Berberine, a strong anti-inflammatory plant alkaloid, administered i. p. every other day (5 and 10 mg/kg) significantly attenuated CS-induced effects on goblets cells and mucin production (Xu et al., 2015). 

  • C57BL/6 wild-type mice exposed to CS (10 cig daily for 4 days) and intranasally inoculated with 50PFU of influenza A/PR8/34 virus showed significantly increased AB/PAS–positive area in the bronchial epithelium. Administration of carbocisteine (mucoregulatory drug) significantly reduced both the AB/PAS-positive areas in bronchial epithelium, and MUC5AC levels in bronchoalveolar lavage (BAL) fluids compared with CS/virus exposed mice (Yageta et al., 2013).  

Information regarding the approximate time-scale of the changes in KEdownstream relative to changes in KEupstream (i.e., do effects on KEdownstream lag those on KEupstream by seconds, minutes, hours, or days?). More help
Known Feedforward/Feedback loops influencing this KER
Define whether there are known positive or negative feedback mechanisms involved and what is understood about their time-course and homeostatic limits. More help

Domain of Applicability

A free-text section of the KER description that the developers can use to explain their rationale for the taxonomic, life stage, or sex applicability structured terms. More help

Increase in goblet cell numbers and concomitant increased mucin production developing after exposure to noxious agents, such as allergens, cigarette smoke, pollution, or pathogens has been described in human independently of sex and age. Experimental models exist in mice, rats, guinea pigs, rabbits, dogs, and ferrets.   


List of the literature that was cited for this KER description. More help

Alimam, M. Z., Piazza, F. M., Selby, D. M., Letwin, N., Huang, L., Rose, M. C. (2000). Muc-5/5ac mucin messenger RNA and protein expression is a marker of goblet cell metaplasia in murine airways. Am. J. Resp. Cell Mol. Biol. 22, 253-260. 

An, J., Li, J.-Q., Wang, T., Li, X.-O., Guo, L.-L., et al. (2013). Blocking of thromboxane A2 receptor attenuates airway mucus hyperproduction induced by cigarette smoke. Eur. J. Pharmacol. 703, 11-17. 

Atherton, H. C., Jones, G., Danahay, H. (2003). IL-13-induced changes in the goblet cell density of human bronchial epithelial cell cultures: MAP kinase and phosphatidylinositol 3-kinase regulation. Am. J. Physiol. Lung Cell. Mol. Physiol. 285, L730-L739. 

Burgel, P.-R., Escudier, E., Coste, A., Dao-Pick, T., Ueki, I.F., et al. (2000). Relation of epidermal growth factor receptor expression to goblet cell hyperplasia in nasal polyps. J. Allergy Clin. Immunol. 106, 705-712. 

Chen, Y.-J., Chen, P., Wang, H.-X., Wang, T., Chen, L., et al. (2010). Simvastatin attenuates acrolein-induced mucin production in rats: involvement of the Ras/extracellular signal-regulated kinase pathway. Intl. Immunopharmacol. 10, 685-693. 

Curran, D. R., and Cohn, L. (2010). Advances in mucous cell metaplasia. A plug for mucus as a therapeutic focus in chronic airway disease. Am. J. Resp. Cell Mol. Biol. 42, 268-275. 

Evans, C.M., Williams, O.W., Tuvim, M.J., Nigam, R., Mixides, G.P., et al. (2004). Mucin is produced by Clara cells in the proximal airways of antigen-challenged mice. Am. J. Respir. Cell Mol. Biol. 31, 382-394.  

Habibovic, A., Hristova, M., Heppner, D.E., Danyal, K., Ather, J.L., et al. (2016). DUOX1 mediates persistent epithelial EGFR activation, mucous cell metaplasia, and airway remodeling during allergic asthma. JCI Insight 1, e88811. 

Hao, Y., Kuang, Z., Walling, B. E., Bhatia, S., Sivaguru, M., et al. (2012). Pseudomonas aeruginosa pyocyanin causes airway goblet cell hyperplasia and metaplasia and mucus hypersecretion by inactivating the transcriptional factor FoxA2. Cell. Microbiol. 14, 401-415. 

Hao, Y., Kuang, Z., Xu, Y., Walling, B.E., Lau, G.W. (2013). Pyocyanin-induced mucin production is associated with redox modification of FOXA2. Respir. Res. 14, 82-82.  

Hao, Y., Kuang, Z., Jing, J., Miao, J., Mei, L.Y., et al. (2014). Mycoplasma pneumoniae modulates STAT3-STAT6/EGFR-FOXA2 signaling to induce overexpression of airway mucins. Infect. Immun. 82, 5246–5255. 

Harkema, J. R., and Hotchkiss, J. A. (1993) Ozone- and endotoxin-induced mucous cell metaplasias in rat airway epithelium: Novel animal models to study toxicant-induced epithelial transformation in airways. Toxicol. Lett. 68, 251-263. 

Hegab, A.E., Sakamoto, T., Nomura, A., Ishii, Y., Morishima, Y., et al. (2007). Niflumic acid and AG-1478 reduce cigarette smoke-induced mucin synthesis: The role of hCLCA1. Chest 131, 1149-1156. 

Huang, L., Pu, J., He, F., Liao, B., Hao, B., et al. (2017). Positive feedback of the amphiregulin-EGFR-ERK pathway mediates PM2.5 from wood smoke-induced MUC5AC expression in epithelial cells. Sci. Rep. 7, 11084.  

Kato, K., Chang, E. H., Chen, Y., Lu, W., Kim, M. M., Niihori, M., et al. (2020). MUC1 contributes to goblet cell metaplasia and MUC5AC expression in response to cigarette smoke in vivo. Am. J. Physiol. Lung Cell Mol. Physiol. 319, L82-L90. 

Kim, B.-G., Lee, P.-H., Lee, S.-H., Kim, Y.-E., Shin, M.-Y., et al. (2016). Long-term effects of diesel exhaust particles on airway inflammation and remodeling in a mouse model. Allergy Asthma Immunol. Res. 8, 246-256. 

Kim, J.H., Lee, S.Y., Bak, S.M., Suh, I.B., Lee, S.Y., et al. (2004). Effects of matrix metalloproteinase inhibitor on LPS-induced goblet cell metaplasia. Am. J. Physiol. Lung Cell. Mol. Physiol. 287, L127-L133.  

Kim, V., Oros, M., Durra, H., Kelsen, S., Aksoy, M., et al. (2015). Chronic bronchitis and current smoking are associated with more goblet cells in moderate to severe COPD and smokers without airflow obstruction. PLoS ONE 10, e0116108.  

Kuchibhotla, V.N.S., and Heijink, I.H. (2020). Join or Leave the Club: Jagged1 and Notch2 Dictate the Fate of Airway Epithelial Cells. Am. J. Respir. Cell Mol. Biol. 63, 4-6. 

Innes A. L., Woodruff, P. G., Ferando, R. E., Donelly, S., Dolganov, G. M., et al. (2006). Epithelial mucin stores are increased in the large airways of smokers with airflow obstruction. CHEST 130, 1102-1108. 

Le Cras, T.D., Acciani, T.H., Mushaben, E.M., Kramer, E.L., Pastura, P.A., et al. (2011). Epithelial EGF receptor signaling mediates airway hyperreactivity and remodeling in a mouse model of chronic asthma. Am. J. Physiol. Lung Cell. Mol. Physiol. 300, L414-L421. 

Lee, H.-M., Takeyama, K., Dabbagh, K., Lausier, J.A., Ueki, I.F., Nadel, J.A. (2000). Agarose plug instillation causes goblet cell metaplasia by activating EGF receptors in rat airways. Am. J. Physiol. Lung Cell. Mol. Physiol. 278, L185-L192. 

Lee, S.Y., Kang, E.J., Hur, G.Y., Jung, K.H., Jung, H.C., et al. (2006). The inhibitory effects of rebamipide on cigarette smoke-induced airway mucin production. Respir. Med. 100, 503-511. 

Liang, Y., Liu, K.W., Yeung, S.C., Li, X., Ip, M.S. Mak, J.C. (2017). (-)-Epigallocatechin-3-gallate reduces cigarette smoke-induced airway neutrophilic inflammation and mucin hypersecretion in rats. Front. Pharmacol. 8, 618. 

Lukacs, N.W., Smit, J.J., Nunez, G., Lindell, D.M. (2010). Respiratory Virus-induced TLR7 activation controls IL-17 associated Increase in mucus via IL-23 regulation: Respiratory virus induced immune environment relies on TLR7-mediated pathways to preserve a non-pathogenic response and regulates IL-17 production. J. Immunol. 185, 2231-2239. 

Ma, R., Wang, Y., Cheng, G., Zhang, H., Wan, H., Huang, S. (2005). MUC5AC expression up-regulation goblet cell hyperplasia in the airway of patients with chronic obstructive pulmonary disease. Chin. Med. Sci. J. 20, 181-184. 

Mishina, K., Shinkai, M., Shimokawaji, T., Nagashima, A., Hashimoto, Y., et al. (2015). HO-1 inhibits IL-13-induced goblet cell hyperplasia associated with CLCA1 suppression in normal human bronchial epithelial cells. Int. Immunopharmacol. 29, 448-453. 

Miyabara, Y., Ichinose, T., Takano, H., Lim, H. B., Sagai, M. (1998). Effects of diesel exhaust on allergic airway inflammation in mice. J. Allergy Clin. Immunol. 102, 805-812. 

Munkholm, M., and Mortensen, J. (2014). Mucociliary clearance: pathophysiological aspects. Clin. Physiol. Funct. Imaging 34, 171-177. 

Nagao, K., Tanaka, H., Komai, M., Masuda, T., Narumiya, S., Nagai, H. (2003). Role of prostaglandin I2 in airway remodeling induced by repeated allergen challenge in mice. Am. J. Respir. Cell Mol. Biol. 29, 314-320. 

Nie, Y.-C., Wu, H., Li, P.-B., Luo, Y.-L., Zhang, C.-C., et al. (2012). Characteristic comparison of three rat models induced by cigarette smoke or combined with LPS: to establish a suitable model for study of airway mucus hypersecretion in chronic obstructive pulmonary disease. Pulm. Pharmacol. Ther. 25, 349-356. 

Ning, Y., Shang, Y., Huang, H., Zhang, J., Dong, Y., et al. (2013). Attenuation of cigarette smoke-induced airway mucus production by hydrogen-rich saline in rats. PLoS One. 8, e83429. 

Ordoñez, C.L., Khashayar, R., Wong, H.H., Ferrando, R., Wu, R., et al. (2001). Mild and moderate asthma is associated with airway goblet cell hyperplasia and abnormalities in mucin gene expression. Am. J. Respir. Crit. Care Med. 163, 517-523. 

Park, J.-A., Sharif, A. S., Shiomi, T., Kobzik, L., Kasahara, D. I., et al. (2013). Human  neutrophil elastase-mediated goblet cell metaplasia is attenuated in TACE-deficient mice. Am. J. Physiol. Lung Cell Mol. Physiol. 304, L701-L707. 

Raju, S.V., Kim, H., Byzek, S.A., Tang, L.P., Trombley, J.E., et al. (2016). A ferret model of COPD-related chronic bronchitis. JCI insight 1, e87536. 

Reader, J. R., Tepper, J. S., Schelegle, E. S., Aldrich, M. C., Putney, L. F., et al. (2003). Pathogenesis of mucous metaplasia in a murine asthma model. Am. J. Pathol. 162, 2069-2078. 

Rose, M.C., and Voynow, J.A. (2006). Respiratory tract mucin genes and mucin glycoproteins in health and disease. Physiol. Rev. 86, 245-278. 

Saetta, M., Turato, G., Baraldo, S., Zanin, A., Braccioni, F., et al. (2000). Goblet Cell Hyperplasia and epithelial inflammation in peripheral airways of smokers with both symptoms of chronic bronchitis and chronic airflow limitation. Am. J. Respir. Crit. Care Med. 161, 1016-1021. 

Silva, M. A., and Bercik, P. (2012). Macrophages are related to goblet cell hyperplasia and induce MUC5B but not MUC5AC in human bronchus epithelial cells. Lab Invest. 92, 937-948. 

Takeyama, K., Tamaoki, J., Kondo, M., Isono, K., Nagai, A. (2008). Role of epidermal growth factor receptor in maintaining airway goblet cell hyperplasia in rats sensitized to allergen. Clin. Exp. Allergy 38, 857-865. 

Takezawa, K., Ogawa, T., Shimizu, S., Shimizu, T. (2016). Epidermal growth factor receptor inhibitor AG1478 inhibits mucus hypersecretion in airway epithelium. Am. J. Rhinol. Allergy 30, e1-e6. 

Tanabe, T., Kanoh, S., Tsushima, K., Yamazaki, Y., Kubo, K., Rubin, B. K. (2011). Clarithromycin inhibits interleukin-13–induced goblet cell hyperplasia in human airway cells. Am. J. Respir. Cell Mol. Biol. 45, 1075-1083. 

Tesfaigzi, Y. (2006). Roles of apoptosis in airway epithelia. Am. J. Respir. Cell Mol. Biol. 34, 537-547.  

Van Hove, C. L., Maes, T., Cataldo, D. D., Guéders, M. M., Palmans, E., et al. (2009). Comparison of acute inflammatory and chronic structural asthma-like responses between C57BL/6 and BALB/c mice. Int. Arch. Allergy Immunol. 149, 195-207. 

Voynow, J. A., Fischer, B. M., Malarkey, D. E., Burch, L. H., Wong, T., et al. (2004). Neutrophil elastase induces mucus cell metaplasia in mouse lung. Am. J. Physiol. Lung Cell Mol. Physiol. 287, L1293-L1302. 

Walter, M.J., Morton, J.D., Kajiwara, N., Agapov, E., Holtzman, M.J. (2002). Viral induction of a chronic asthma phenotype and genetic segregation from the acute response. J. Clin. Invest. 110, 165-175. 

Wan, H., Kaestner, K.H., Ang, S.-L., Ikegami, M., Finkelman, F.D., et al. (2004). Foxa2 regulates alveolarization and goblet cell hyperplasia. Development 131, 953–964. 

Yageta, Y., Ishii, Y., Morishima, Y., Ano, S., Ohtsuka, S., et al. (2014). Carbocisteine reduces virus-induced pulmonary inflammation in mice exposed to cigarette smoke. Am. J. Respir. Cell Mol. Biol. 50, 963-973. 

Xia, W., Bai, J., Wu, X., Wei, Y., Feng, S., et al. (2014). Interleukin-17A promotes MUC5AC expression and goblet cell hyperplasia in nasal polyps via the Act1-mediated pathway. PLoS One 9, e98915. 

Xu, D., Wan, C., Wang, T., Tian, P., Li, D., et al. (2015). Berberine attenuates cigarette smoke-induced airway inflammation and mucus hypersecretion in mice. Int. J. Clin. Exp. Med. 8, 8641. 

Zhou, J.-S., Zhao, Y., Zhou, H.-B., Wang, Y., Wu, Y.-F., et al. (2016). Autophagy plays an essential role in cigarette smoke-induced expression of MUC5AC in airway epithelium. Am. J. Physiol. Lung Cell. Mol. Physiol. 310, L1042-L1052.