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: 965


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

Activation, EGFR leads to Occurrence, Transdifferentiation of ciliated epithelial cells

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

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
mouse Mus musculus Moderate NCBI
human Homo sapiens High NCBI
rat Rattus norvegicus Low NCBI

Sex Applicability

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

Life Stage Applicability

An indication of the the relevant life stage(s) for this KER.  More help
Term Evidence
Adult Moderate

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

Airway epithelial injury can be caused by various inhalation exposures (e.g. cigarette smoke, sulfur dioxide, endotoxin, viruses). Subsequent tissue repair processes are thought to initiate the transdifferentiation process, whereby ciliated epithelial cells first dedifferentiate and then redifferentiate to goblet cells, without an apparent increase in the total number of epithelial cells (Lumsden et al., 1984; Shimizu et al., 1996; Reader et al., 2003). EGFR was shown to be a key player in this process in both murine and human airway epithelia (Tyner et al., 2006; Hao et al., 2011; Habibovic et al., 2016).

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

Evidence Supporting this KER

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

Transdifferentiation was shown to occur following the activation of EGFR-mediated anti-apoptotic signaling in ciliated epithelial cells (Tyner et al., 2006). Subsequent stimulation by proinflammatory stimuli such as the Th2 cytokines interleukin (IL)-4 and IL-13 then promotes transdifferentiation of ciliated cells into goblet cells, thereby increasing the number of goblet cells (“second hit hypothesis”) in mouse tracheal epithelium and airway epithelia of COPD patients (Curran & Cohn, 2010).

EGFR can be activated by ROS or IL-13 to lead to ciliated cell transdifferentiation. IL-13 stimulates transdifferentiation of ciliated epithelial cells to goblet cells through EGFR activation increasing MMP/ADAM activity and MAPK activation (Casalino-Matsuda et al., 2006; Yoshisue and Hasegawa, 2004; Tyner et al., 2006).

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

Two studies showed EGFR involvement in a decrease in goblet cell and increase in ciliated cell numbers or cell-specific marker expression (Yoshisue and Hasegawa, 2004; Casalino-Matsuda et al., 2006). Other studies demonstrated ciliated cell transdifferentiation in response to IL13 in an EGFR-dependent manner in a mouse viral infection model and mouse tracheal epithelial cells in vitro (Tyner et al., 2006), rat nasal epithelial cells (Lee et al., 2000), and human airway epithelial cells (Kim et al., 2002; Hao et al., 2011).

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

It is not well-known how ciliated cell transdifferentiation occurs in humans. Under normal conditions, lung epithelial cells (except basal cells) are terminally differentiated (Donnelly et al., 1982; Breuer et al., 1990; Rawlins and Hogan, 2008), and which signals initiate the dedifferentiation/redifferentiation process is not well-understood. The available evidence is indirect or correlative. It also is not in agreement with other studies, which showed that ciliated cells do not give rise to goblet cells during airway remodeling in rodents and humans and with studies that provide evidence for increased goblet cell proliferation and goblet cell hyperplasia (Pardo-Sargenta et al., 2013; Hays et al., 2006; Lawson et al., 2002; Tesfaigzi et al., 2004; Taniguchi et al., 2011; Park et al., 2006; Turner et al., 2011).

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

Daily 30-minute treatment of primary human bronchial epithelial cells at the air-liquid interface with 0.6 mM xanthine and 0.5 units xanthine oxidase for 3 days resulted in goblet cell metaplasia as evidenced by an increase in the numbers of MUC5AC-positive cells from 3.3 ± 1.2%to 21.6 ± 3.4% and a decrease in ciliated cell numbers. This effect could be inhibited by EGFR blockade with neutralizing antibodies (Casalino-Matsuda et al., 2006).

Cigarette smoke exposure at 8 cigarettes per day for 5 days markedly increased AB-PAS staining in airway epithelia and goblet cell numbers from 40 ± 19 to 167 ± 19 cells/mm of epithelium, while decreasing the number of ciliated cells (not quantified). Treatment with the EGFR inhibitor BIBX1522 during exposure dose-dependently decreased goblet cell numbers, with a maximal decrease seen for 3 mg/kg inhibitor (51 ± 19 cells/mm epithelium) (Takeyama et al., 2001).

Induction of airway inflammation with 50 µg house dust mite (1.27 endotoxin units/mg) for 5 days/week for 3 weeks resulted in a 3-fold increase of pEGFR-positive cells in the bronchiolar epithelium of C57Bl/6 mice. Six-week treatment led to goblet cell metaplasia as evidenced by extensive AB staining and an approx. 10-fold increase in Clca3-positive cells in the animals' airways. Concomitant treatment with 100 mg/kg erlotinib six times a week for 6 weeks reduced the number of Clca3-positive cells by ca. 5-fold (Le Cras et al., 2011). Using the same model with a 3-week treatment demonstrated goblet cell metaplasia as judged by increased PAS staining in the airway epithelium and ca. 10-, 5-, and 4-fold increases in expression of goblet cell metaplasia-related genes Muc5ac, Clca1, and Postn, respectively (Habibovic et al., 2016).

Pyocyanin, a redox-active exotoxin of Pseudomonas aeruginosa, caused goblet cell metaplasia in C57Bl/6 mice after 3-week treatment (25 µg/day). PAS staining increased by ca. 30%; the percentage of Muc5ab-positive cell in bronchial epithelium increased 6.4-fold and in bronchiolar epithelium 11.4-fold. This was accompanied by increased EGFR phosphorylation coincident with AB/PAS staining. Moreover, 24-h pyocyanin treatment of H292 lung cancer cells and immortlaized human bronchial epithelial 16-HBE cells with physiologically relevant concentrations from 1.3 to 25 µg/mL pyocyanin significantly increased MUC5B mRNA expression 3.8- to 13.4-fold and increased levels of pEGFR 11.8- to 18.3-fold (1.6 to 12.5 µg/mL pyocyanin) (Hao et al., 2012).

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

Induction of airway inflammation with 50 µg house dust mite (1.27 endotoxin units/mg) for 5 days/week for 3 weeks resulted in a 3-fold increase of pEGFR-positive cells in the bronchiolar epithelium of C57Bl/6 mice. Six-week treatment led to goblet cell metaplasia as evidenced by extensive AB staining and an approx. 10-fold increase in Clca3-positive cells in the animals' airways. Concomitant treatment with 100 mg/kg erlotinib six times a week for 6 weeks reduced the number of Clca3-positive cells by ca. 5-fold (Le Cras et al., 2011). Using the same model with a 3-week treatment demonstrated goblet cell metaplasia as judged by increased PAS staining in the airway epithelium and ca. 10-, 5-, and 4-fold increases in expression of goblet cell metaplasia-related genes Muc5ac, Clca1, and Postn, respectively (Habibovic et al., 2016).

Instillation of agarose plugs (0.7-0.8 mm diameter, 4% agarose II) in Fischer rats caused a time-dependent increase in goblet cell area (by AB/PAS staining), which was detectable as early as 24 h and was greatest 72 h post-instillation. The AB/PAS-stained area 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 post-instillation, respectively. Goblet cell numbers increased from 0 to 13.1 ± 5.6, 25.7 ± 15.0, and 51.5 ± 9.0 cells/mm basal lamina at 24, 48, and 72 h post-instillation, respectively. Treatment of the animals prior and after instillation with 80 mg/kg/day BIBX1522 resulted in a marked decrease in the AB/PAS-stained area (<5% at 72 h). Of note, the AB/PAS staining in the airway epithelia coincided with EGFR staining  (Lee et al., 2000).

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

Two mouse studies demonstrated ciliated cell transdifferentiation and goblet metaplasia in response to virus and/or IL13 (Tyner et al., 2006; Fujisawa et al., 2008). Indirect evidenc is also available from rat studies and studies on human cells and clinical samples.


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

Breuer, R., Zajicek, G., Christensen, T.G., Lucey, E.C., and Snider, G.L. (1990). Cell Kinetics of Normal Adult Hamster Bronchial Epithelium in the Steady State. Am. J. Respir. Cell Mol. Biol. 2, 51–58.

Casalino-Matsuda, S., Monzón, M., and Forteza, R. (2006). Epidermal Growth Factor Receptor Activation by Epidermal Growth Factor Mediates Oxidant-Induced Goblet Cell Metaplasia in Human Airway Epithelium. Am. J. Respir. Cell Mol. Biol. 34, 581–591.

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. Respir. Cell Mol. Biol. 42, 268-275.

Donnelly, G.M., Haack, D.G., and Heird, C.S. (1982). Tracheal epithelium: cell kinetics and differentiation in normal rat tissue. Cell Tissue Kinet. 15, 119–130.

Fujisawa, T., Ide, K., Suda, T., Suzuki, K., Kuroishi, S., Chida, K., et al. (2008). Involvement of the p38 MAPK pathway in IL‐13‐induced mucous cell metaplasia in mouse tracheal epithelial cells. Respirology 13, 191-202.

Habibovic, A., Hristova, M., Heppner, D.E., Danyal, K., Ather, J.L., Janssen-Heininger, Y.M., Irvin, C.G., Poynter, M.E., Lundblad, L.K., and Dixon, A.E. (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., Chen, Y., Gaskins, H.R. and Lau, G.W. (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.

Hays, S.R., and Fahy, J.V. (2006). Characterizing mucous cell remodeling in cystic fibrosis: relationship to neutrophils. Am. J. Respir. Crit. Care Med. 174, 1018-1024.

Kim, S., Shim, J., Burgerl, P., Ueki, I., Dao-Pick, T., Tam, D., and Nadel, J. (2002). IL-13-induced Clara cell secretory protein expression in airway epithelium: role of EGFR signaling pathway. Am. J. Physiol. Lung Cell. Mol. Physiol. 283, L67–L75.

Kim, J.H., Lee, S.Y., Bak, S.M., Suh, I.B., Lee, S.Y., Shin, C., Shim, J.J., In, K.H., Kang, K.H., and Yoo, S.H. (2004). Effects of matrix metalloproteinase inhibitor on LPS-induced goblet cell metaplasia. Am. J. Physiol. Lung Cell. Mol. Physiol. 287, L127-L133.

Lawson, G.W., Van Winkle, L.S., Toskala, E., Senior, R.M., Parks, W.C., and Plopper, C.G. (2002). Mouse strain modulates the role of the ciliated cell in acute tracheobronchial airway injury-distal airways. Am. J. Pathol. 160, 315–327.

Le Cras, T.D., Acciani, T.H., Mushaben, E.M., Kramer, E.L., Pastura, P.A., Hardie, W.D., Korfhagen, T.R., Sivaprasad, U., Ericksen, M., Gibson, A.M. and Holtzman, M.J., 2010. 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., and 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.

Lumsden, A.B., McLean, A., and Lamb, D. (1984). Goblet and Clara cells of human distal airways: evidence for smoking induced changes in their numbers. Thorax 39, 844-849.

Pardo-Saganta, A., Law, B.M., Gonzalez-Celeiro, M., Vinarsky, V., and Rajagopal, J. (2013). Ciliated cells of pseudostratified airway epithelium do not become mucous cells after ovalbumin challenge. Am. J. Respir. Cell Mol. Biol. 48, 364–373.

Park, K.-S., Wells, J.M., Zorn, A.M., Wert, S.E., Laubach, V.E., Fernandez, L.G., and Whitsett, J.A. (2006). Transdifferentiation of ciliated cells during repair of the respiratory epithelium. Am. J. Respir. Cell Mol. Biol. 34, 151–157.

Rawlins, E.L., and Hogan, B.L.M. (2008). Ciliated epithelial cell lifespan in the mouse trachea and lung. Am. J. Physiol. Lung Cell. Mol. Physiol. 295, L231–L234.

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

Shim, J.J., Dabbagh, K., Ueki, I.F., Dao-Pick, T., Burgel, P.R., Takeyama, K., Tam, D.C., and Nadel, J.A. (2001). IL-13 induces mucin production by stimulating epidermal growth factor receptors and by activating neutrophils. Am. J. Physiol. Lung Cell. Mol. Physiol. 280, L134–L140.

Shimizu, T., Takahashi, Y., Kawaguchi, S., and Sakakura, Y. (1996). Hypertrophic and metaplastic changes of goblet cells in rat nasal epithelium induced by endotoxin. Am. J. Respir. Crit. Care Med. 153, 1412-1418.

Taniguchi, K., Yamamoto, S., Aoki, S., Toda, S., Izuhara, K., and Hamasaki, Y. (2011). Epigen is induced during the interleukin-13–stimulated cell proliferation in murine primary airway epithelial cells. Exp. Lung Res. 37, 461-470.

Tesfaigzi, Y., Harris, J.F., Hotchkiss, J.A., and Harkema, J.R. (2004). DNA synthesis and Bcl-2 expression during development of mucous cell metaplasia in airway epithelium of rats exposed to LPS. Am. J. Physiol. Lung Cell. Mol. Physiol. 286, L268-L274.

Turner, J., Roger, J., Fitau, J., Combe, D., Giddings, J., Heeke, G.V., and Jones, C.E. (2011). Goblet cells are derived from a FOXJ1-expressing progenitor in a human airway epithelium. Am. J. Respir. Cell Mol. Biol. 44, 276–284.

Tyner, J., Tyner, E., Ide, K., Pelletier, M., Roswit, W., Morton, J., Battaile, J., Patel, A., Patterson, G., Castro, M., et al. (2006). Blocking airway mucous cell metaplasia by inhibiting EGFR antiapoptosis and IL-13 transdifferentiation signals. J. Clin. Invest. 116, 309–321.

Yoshisue, H., and Hasegawa, K. (2004). Effect of MMP/ADAM inhibitors on goblet cell hyperplasia in cultured human bronchial epithelial cells. Biosci. Biotechnol. Biochem. 68, 2024–2031.