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Key Event Title
Increase, Mucin production
|Level of Biological Organization|
Key Event Components
Key Event Overview
AOPs Including This Key Event
Key Event Description
Mucin production in healthy airway provides an important role in trapping and removing bacterial and viral pathogens and particulates. The major gel-forming mucins of the airways, MUC5AC and MUC5AB, are primarily involved in this function (Lillehoj et al., 2013). Various stimuli increase mucin production by goblet cells including cigarette smoke, phorbol 12-myristate 13-acetate (PMA), 2,3,7,8-tetrachlorodibenzodioxin (TCDD), ozone, acrolein, and sulfur dioxide (Lamb and Reid, 1968; Shao et al., 2004; Takeyama et al., 2001; Yu et al., 2011; Casalino-Matsuda et al., 2009; Hewson et al., 2004; Lee et al., 2011; Wagner et al., 2003) as well as bacteria and viruses (Dohrman et al., 1998; Hao et al., 2014; Zhu et al., 2009). Many of these stimuli specifically induce MUC5AC mRNA and protein production through activation of the EGFR pathway (Nadel, 2013). However, other signaling pathways, not necessarily requiring EGFR activation, via STAT6, FOXA2, SPDEF or NFkB have also been implicated in MUC5AC overexpression (reviewed by Turner and Jones, 2009).
How It Is Measured or Detected
To our knowledge, no validated method for the determination of mucin overproduction exists. In the literature, increased mucin production is frequently equated with increased MUC5AC mRNA and protein expression and much less frequently with changes in MUC5AB mRNA and protein levels.
Alterations in MUC5AC mRNA expression in cell and tissue lysates are commonly assessed by RT-PCR or RT-qPCR, whereas Northern blotting is less frequently used. Changes in MUC5AC protein levels can be detected by ELISA or Western blot in cell and tissue lysates and secretions or by immunocyto/histochemistry/immunofluorescence in cytological preparations or histological tissue sections with an appropriate antibody. It is worth noting here that some antibodies are not suitable for ELISA or Western blot, because extensive glycosylation of mucins may mask epitopes or block access of the antibody to the epitope (Rose and Voynow, 2006). Alternatively, labeled and label-free mass spectrometry-based approaches could be utilized for targeted identification of mucins and their quantification in cell and tissue samples. For in vivo studies and clinical samples, an experienced pathologist may judge the presence and severity of mucin production on histological tissue sections stained with hematoxylin/eosin and Alcian blue and/or periodic acid Schiff stains. A grading or scoring system may enable semi-quantitative assessment, but remains subjective at best since corresponding standards are currently lacking.
Domain of Applicability
The MUC5AC gene is conserved in Rhesus monkey, dog, cow, mouse, rat, zebrafish, and frog, and the MUC5B gene is conserved in dog, mouse, rat, and chicken. Evidence in support of this KE primarily derives from in vitro studies with human cell systems, while corroborating in vivo evidence comes from studies in small rodents (mouse or rat).
Evidence for Perturbation by Stressor
Exposure of Sprague-Dawley rats to 3 ppm acrolein for 6 h a day, for 12 days significantly increased lung Muc5ac gene and protein expression (Chen et al., 2013).
Bronchoalveolar lavage fluid mucin content as well as Muc5ac gene and protein expression were significantly increased in the lungs of Sprague-Dawley rats that were exposed to 3 ppm of acrolein for 6 h a day, 7 days a week, for up to 2 weeks (Liu et al., 2009).
Exposure of Sprague Dawley rats to 3 ppm acrolein for 6 h a day, 5 days a week, for up to 12 days significantly increased Muc5ac gene expression in trachea and lung (Borchers et al., 1998).
Exposure of Sprague Dawley rats to 3 ppm acrolein for 3 h a day, 7 days a week, for up to 4 days significantly increased Muc5ac gene and protein expression in the lungs (Wang et al., 2009).
Treatment of primary normal human bronchial epithelial cells and immortalized human bronchial epithelial HBE1 cells with 10 nM TCDD for up to 48 h increased MUC5AC gene expression in a time-dependent manner. TCDD treatment (10 nM) of primary normal human bronchial epithelial cells also significantly increased MUC5AC protein levels (Lee et al., 2011).
In the tracehas of rats that were nose-only exposed to smoke from burning Douglas fir wood (25 g) for up to 20 min, Muc5ac gene expression was increased at 24 h post-exposure (Bhattacharyya etal., 2004).
Treatment of immortalized human bronchial epithelial 16HBE cells with cigarette smoke extract increased MUC5AC gene and protein expression in a concentration-dependent manner (Yu et al., 2011; Yu et al., 2015). Treatment of NCI-H292 lung cancer cells with cigarette smoke extract increased MUC5AC gene and protein expression in a concentration- and time-dependent manner (Takeyama et al., 2001; Shao et al., 2004; Baginski et al., 2006; Lee et al., 2006; Montalbano et al., 2014). Cigarette smoke extract treatment of A549 lung cancer cells (2 h) and primary human bronchial epithelial cells differentiated at the air-liquid interface (6 h and 16 h) increased MUC5AC gene and protein expression (Di et al., 2012).
Whole-body exposure (TE-10 Teague Enterprises, Davis, CA) of rats to smoke from 1R1 research cigarettes (University of Kentucky; increasing dose between 123 to 323 mg/m3 total smoking particulate matter) for 2 h per day, 5 days per week, for 8 weeks significantly elevated Muc5ac levels in the bronchoalveolar fluid (Kato et al., 2020).
Muc5ac gene expression increased in the lungs of male Sprague-Dawley rats that were whole-body exposed to the smoke of 5 cigarettes a day, for 5 consecutive days (Takeyama et al., 2001).
Baginski, T.K., Dabbagh, K., Satjawatcharaphong, C., and Swinney, D.C. (2006). Cigarette smoke synergistically enhances respiratory mucin induction by proinflammatory stimuli. Am. J. Respir. Cell Mol. Biol. 35, 165-174.
Bhattacharyya, S.N., Dubick, M.A., Yantis, L.D., Enriquez, J.I., Buchanan, K.C., Batra, S.K., et al. (2004). In vivo effect of wood smoke on the expression of two mucin genes in rat airways. Inflammation 28, 67-76.
Borchers, M.T., Wert, S.E., and Leikauf, G.D. (1998). Acrolein-induced MUC5ac expression in rat airways. Am. J. Physiol. Lung Cell. Mol. Physiol. 274, L573-L581.
Casalino-Matsuda, S., Monzon, M., Day, A., and Forteza, R. (2009). Hyaluronan fragments/CD44 mediate oxidative stress-induced MUC5B up-regulation in airway epithelium. Am. J. Respir. Cell Mol. Biol. 40, 277–285.
Chen, P., Deng, Z., Wang, T., Chen, L., Li, J., Feng, Y., et al. (2013). The potential interaction of MARCKS-related peptide and diltiazem on acrolin-induced airway mucus hypersecretion in rats. Int. Immunopharmacol. 17, 625-632.
Di, Y.P., Zhao, J., and Harper, R. (2012). Cigarette smoke induces MUC5AC protein expression through the activation of Sp1. J. Biol. Chem. 287, 27948-27958.
Dohrman, A., Miyata, S., Gallup, M., Li, J.D., Chapelin, C., Coste, A., Escudier, E., Nadel, J., and Basbaum, C. (1998). Mucin gene (MUC 2 and MUC 5AC) upregulation by Gram-positive and Gram-negative bacteria. Biochim. Biophys. Acta 1406, 251–259.
Hao, Y., Kuang, Z., Jing, J., Miao, J., Mei, L.Y., Lee, R.J., Kim, S., Choe, S., Krause, D.C., and Lau, G.W. (2014). Mycoplasma pneumoniae Modulates STAT3-STAT6/EGFR-FOXA2 Signaling To Induce Overexpression of Airway Mucins. Infect. Immun. 82, 5246–5255.
Hewson, C., Edbrooke, M., and Johnston, S. (2004). PMA induces the MUC5AC respiratory mucin in human bronchial epithelial cells, via PKC, EGF/TGF-alpha, Ras/Raf, MEK, ERK and Sp1-dependent mechanisms. J. Mol. Biol. 344, 683–695.
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.
Lamb, D., and Reid, L. (1968). Mitotic rates, goblet cell increase and histochemical changes in mucus in rat bronchial epithelium during exposure to sulphur dioxide. J. Pathol. Bacteriol. 96, 97–111.
Lee, S.Y., Kang, E.J., Hur, G.Y., Jung, K.H., Jung, H.C., Lee, S.Y., et al. (2006). The inhibitory effects of rebamipide on cigarette smoke-induced airway mucin production. Respir. Med. 100, 503-511.
Lee, Y.C., Oslund, K.L., Thai, P., Velichko, S., Fujisawa, T., Duong, T., Denison, M.S., and Wu, R. (2011). 2,3,7,8-Tetrachlorodibenzo-p-dioxin–Induced MUC5AC Expression. Am. J. Respir. Cell Mol. Biol. 45, 270–276.
Lillehoj, E. P., Kato, K., Lu, W., & Kim, K. C. (2013). Cellular and Molecular Biology of Airway Mucins. Int. Rev. Cell Mol. Biol. 303, 139–202.
Liu, D.-S., Liu, W.-J., Chen, L., Ou, X.-M., Wang, T., Feng, Y.-L., et al. (2009). Rosiglitazone, a peroxisome proliferator-activated receptor-γ agonist, attenuates acrolein-induced airway mucus hypersecretion in rats. Toxicology 260, 112-119.
Montalbano, A.M., Albano, G.D., Anzalone, G., Bonanno, A., Riccobono, L., Di Sano, C., et al. (2014). Cigarette smoke alters non-neuronal cholinergic system components inducing MUC5AC production in the H292 cell line. Eur. J. Pharmacol. 736, 35-43.
Nadel, J.A. (2013). Mucous hypersecretion and relationship to cough. Pulm. Pharmacol. Therap. 26, 510-513.
Rose, M.C., and Voynow, J.A. (2006). Respiratory tract mucin genes and mucin glycoproteins in health and disease. Physiol. Rev. 86, 245-278.
Shao, M., Nakanaga, T., and Nadel, J. (2004). Cigarette smoke induces MUC5AC mucin overproduction via tumor necrosis factor-alpha-converting enzyme in human airway epithelial (NCI-H292) cells. Am. J. Physiol. Lung Cell. Mol. Physiol. 287, L420–L427.
Takeyama, K., Jung, B., Shim, J., Burgerl, P., Dao-Pick, T., Ueki, I., Protin, U., Kroschel, P., and Nadel, J. (2001). Activation of epidermal growth factor receptors is responsible for mucin synthesis induced by cigarette smoke. Am. J. Physiol. Lung Cell. Mol. Physiol. 280, L165–L172.
Turner, J., and Jones, C.E. (2009). Regulation of mucin expression in respiratory diseases (Portland Press Limited).
Wang, T., Liu, Y., Chen, L., Wang, X., Hu, X.-R., Feng, Y.-L., et al. (2009). Effect of sildenafil on acrolein-induced airway inflammation and mucus production in rats. Eur. Resp. J. 33, 1122-1132.
Yu, H., Li, Q., Zhou, X., Kolosov, V., and Perelman, J. (2011). Role of hyaluronan and CD44 in reactive oxygen species-induced mucus hypersecretion. Mol. Cell. Biochem. 352, 65–75.
Yu, H., Li, Q., Kolosov, V.P., Perelman, J.M., and Zhou, X. (2012). Regulation of cigarette smoke‐mediated mucin expression by hypoxia‐inducible factor‐1α via epidermal growth factor receptor‐mediated signaling pathways. J. Appl. Toxicol. 32, 282-292.
Zhu, L., Lee, P., Lee, W., Zhao, Y., Yu, D., & Chen, Y. (2009). Rhinovirus-Induced Major Airway Mucin Production Involves a Novel TLR3-EGFR–Dependent Pathway. Am. J. Resp. Cell Mol. Biol. 40, 610–619.