scholarly journals Mucin granules are degraded in the autophagosome-lysosome pathway as a means of resolving airway mucous cell metaplasia

2020 ◽  
Author(s):  
JM Sweeter ◽  
K Kudrna ◽  
K Hunt ◽  
P Thomes ◽  
BF Dickey ◽  
...  
Keyword(s):  
Mucous Cell ◽  
Airway Disease ◽  
Airway Epithelial Cells ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Mtor Inhibition ◽  
Airway Diseases ◽  
Obstructive Airway Diseases ◽  
Deficient Mice

AbstractExacerbations of muco-obstructive airway diseases such as COPD and asthma are associated with epithelial changes termed mucous cell metaplasia (MCM). The molecular pathways triggering MCM have been identified; however, the factors that regulate resolution are less well understood. We hypothesized that the autophagosome-lysosome pathway is required for resolution of MCM by degrading cytoplasmic mucins. We found increased intracellular levels of Muc5ac and Muc5b in autophagy-deficient mice. This difference was not due to defective mucin secretion. Instead, we found that Lamp1-labeled lysosomes surrounded mucin granules of mucous cells indicating that granules were being degraded. Using a model of resolution of mucous cell metaplasia in mice, we found increased lysosomal proteolytic activity that peaked in the days after inflammation. Autophagy-deficient mice had persistent accumulation of mucin granules that failed to decline due to reduced mucin degradation. We applied these findings in vitro to human airway epithelial cells (AECs). Activation of autophagy by mTOR inhibition led to degradation of mucin granules in AECs. Our findings indicate that during peak and resolution phases of MCM, mucin granules can be degraded by autophagy. The addition of mucin degradation to the existing paradigm of production and secretion may more fully explain how the secretory cells handle excess amounts of cytoplasmic mucin and offers a therapeutic target to speed resolution of MCM in airway disease exacerbations.Abstract Figure

scholarly journals MyD88 controls airway epithelial Muc5ac expression during TLR activation conditions from agricultural organic dust exposure

2019 ◽  
Vol 316 (2) ◽  
pp. L334-L347 ◽  
Author(s):  
John D. Dickinson ◽  
Jenea M. Sweeter ◽  
Elizabeth B. Staab ◽  
Amy J. Nelson ◽  
Kristina L. Bailey ◽  
...  
Keyword(s):  
Mucous Cell ◽  
Airway Epithelial Cells ◽  
Dust Exposure ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Organic Dust ◽  
Protein Levels ◽  
Activation Conditions ◽  
Deficient Mice

Inflammation from airborne microbes can overwhelm compensatory mucociliary clearance mechanisms, leading to mucous cell metaplasia. Toll-like receptor (TLR) activation via myeloid differentiation factor 88 (MyD88) signaling is central to pathogen responses. We have previously shown that agricultural organic dust extract (ODE), with abundant microbial component diversity, activates TLR-induced airway inflammation. With the use of an established model, C57BL/6J wild-type (WT) and global MyD88 knockout (KO) mice were treated with intranasal inhalation of ODE or saline, daily for 1 wk. ODE primarily increased mucin (Muc)5ac levels relative to Muc5b. Compared with ODE-challenged WT mice, ODE-challenged, MyD88-deficient mice demonstrated significantly increased Muc5ac immunostaining, protein levels by immunoblot, and expression by quantitative PCR. The enhanced Muc5ac levels in MyD88-deficient mice were not explained by differences in the differentiation program of airway secretory cells in naïve mice. Increased Muc5ac levels in MyD88-deficient mice were also not explained by augmented inflammation, IL-17A, or neutrophil elastase levels. Furthermore, the enhanced airway mucins in the MyD88-deficient mice were not due to defective secretion, as the mucin secretory capacity of MyD88-KO mice remained intact. Finally, ODE-induced Muc5ac levels were enhanced in MyD88-deficient airway epithelial cells in vitro. In conclusion, MyD88 deficiency enhances airway mucous cell metaplasia under environments with high TLR activation.

scholarly journals Autophagy of mucin granules contributes to resolution of airway mucous metaplasia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. M. Sweeter ◽  
K. Kudrna ◽  
K. Hunt ◽  
P. Thomes ◽  
B. F. Dickey ◽  
...  
Keyword(s):  
Regulatory Protein ◽  
Airway Disease ◽  
Airway Epithelial Cells ◽  
Secretory Cells ◽  
Airway Epithelial ◽  
Mtor Inhibition ◽  
Mucin Production ◽  
Mucous Metaplasia ◽  
Autophagy Pathway ◽  
Secretion Pathways

AbstractExacerbations of muco-obstructive airway diseases such as COPD and asthma are associated with epithelial changes termed mucous metaplasia (MM). Many molecular pathways triggering MM have been identified; however, the factors that regulate resolution are less well understood. We hypothesized that the autophagy pathway is required for resolution of MM by eliminating excess non-secreted intracellular mucin granules. We found increased intracellular levels of mucins Muc5ac and Muc5b in mice deficient in autophagy regulatory protein, Atg16L1, and that this difference was not due to defects in the known baseline or stimulated mucin secretion pathways. Instead, we found that, in mucous secretory cells, Lc3/Lamp1 vesicles colocalized with mucin granules particularly adjacent to the nucleus, suggesting that some granules were being eliminated in the autophagy pathway rather than secreted. Using a mouse model of MM resolution, we found increased lysosomal proteolytic activity that peaked in the days after mucin production began to decline. In purified lysosomal fractions, Atg16L1-deficient mice had reduced proteolytic degradation of Lc3 and Sqstm1 and persistent accumulation of mucin granules associated with impaired resolution of mucous metaplasia. In normal and COPD derived human airway epithelial cells (AECs), activation of autophagy by mTOR inhibition led to a reduction of intracellular mucin granules in AECs. Our findings indicate that during peak and resolution phases of MM, autophagy activity rather than secretion is required for elimination of some remaining mucin granules. Manipulation of autophagy activation offers a therapeutic target to speed resolution of MM in airway disease exacerbations.

scholarly journals MiR-223 is increased in lungs of patients with COPD and modulates cigarette smoke-induced pulmonary inflammation

2021 ◽  
Author(s):  
Mirjam P. Roffel ◽  
Tania Maes ◽  
Corry-Anke Brandsma ◽  
Maarten van den Berge ◽  
Bart M. Vanaudenaerde ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cigarette Smoke ◽  
Pulmonary Inflammation ◽  
Airway Epithelial Cells ◽  
Negative Regulator ◽  
Stage Ii ◽  
Airway Epithelial ◽  
Copd Patients ◽  
Deficient Mice

Since microRNA (miR)-223-3p modulates inflammatory responses and COPD is associated with amplified pulmonary inflammation, we hypothesized that miR-223-3p plays a role in COPD pathogenesis. Expression of miR-223-3p was measured in lung tissue of 2 independent cohorts with COPD GOLD stage II-IV patients, never smokers and smokers without COPD. The functional role of miR-223-3p was studied in deficient mice and upon overexpression in airway epithelial cells from COPD and controls. We observed higher miR-223-3p levels in patients with COPD stage II-IV compared to (non)-smoking controls, and levels were associated with higher neutrophil numbers in bronchial biopsies of COPD patients. MiR-223-3p expression was also increased in lungs and bronchoalveolar lavage of cigarette smoke (CS)-exposed mice. CS-induced neutrophil and monocyte lung infiltration was stronger in miR-223 deficient mice upon acute (5 days) exposure, but attenuated upon sub-chronic (4 weeks) exposure. Additionally, miR-223 deficiency attenuated acute and sub-chronic CS-induced lung infiltration of dendritic cells and T lymphocytes. Finally, in vitro overexpression of miR-223-3p in non-COPD airway epithelial cells suppressed CXCL8 and GM-CSF secretion and gene expression of the pro-inflammatory transcription factor TRAF6. Importantly, this suppressive effect of miR-223-3p was compromised in COPD-derived cultures. In conclusion, we demonstrate that miR-223-3p is increased in lungs of COPD patients and CS-exposed mice, and is associated with neutrophilic inflammation. In vivo data indicate that miR-223 acts as negative regulator of acute CS-induced neutrophilic and monocytic inflammation. In vitro data suggests that miR-223-3p does so by suppressing pro-inflammatory airway epithelial responses, which is less effective in COPD epithelium.

Immunity, Inflammation, and Remodeling in the Airway Epithelial Barrier: Epithelial-Viral-Allergic Paradigm

2002 ◽  
Vol 82 (1) ◽  
pp. 19-46 ◽  
Author(s):  
Michael J. Holtzman ◽  
Jeffrey D. Morton ◽  
Laurie P. Shornick ◽  
Jeffrey W. Tyner ◽  
Mary P. O'Sullivan ◽  
...  
Keyword(s):  
Immune System ◽  
Airway Inflammation ◽  
Inflammatory Disease ◽  
Adaptive Immune System ◽  
Airway Disease ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Initial Stimulus ◽  
Airway Diseases ◽  
Airway Function

The concept that airway inflammation leads to airway disease has led to a widening search for the types of cellular and molecular interactions responsible for linking the initial stimulus to the final abnormality in airway function. It has not yet been possible to integrate all of this information into a single model for the development of airway inflammation and remodeling, but a useful framework has been based on the behavior of the adaptive immune system. In that paradigm, an exaggeration of T-helper type 2 (Th2) over Th1 responses to allergic and nonallergic stimuli leads to airway inflammatory disease, especially asthma. In this review, we summarize alternative evidence that the innate immune system, typified by actions of airway epithelial cells and macrophages, may also be specially programmed for antiviral defense and abnormally programmed in inflammatory disease. Furthermore, this abnormality may be inducible by paramyxoviral infection and, in the proper genetic background, may persist indefinitely. Taken together, we propose a new model that highlights specific interactions between epithelial, viral, and allergic components and so better explains the basis for airway immunity, inflammation, and remodeling in response to viral infection and the development of long-term disease phenotypes typical of asthma and other hypersecretory airway diseases.

scholarly journals Roxithromycin Inhibits Cytokine Production by and Neutrophil Attachment to Human Bronchial Epithelial Cells In Vitro

1998 ◽  
Vol 42 (6) ◽  
pp. 1499-1502 ◽  
Author(s):  
Shin Kawasaki ◽  
Hajime Takizawa ◽  
Takayuki Ohtoshi ◽  
Naonobu Takeuchi ◽  
Tadashi Kohyama ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cytokine Production ◽  
Inflammatory Cells ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Airway Diseases ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Local Recruitment

ABSTRACT We evaluated the effect of roxithromycin on cytokine production and neutrophil attachment to human airway epithelial cells. Roxithromycin suppressed production of interleukin 8 (IL-8), IL-6, and granulocyte-macrophage colony-stimulating factor. It inhibited neutrophil adhesion to epithelial cells. Roxithromycin modulates local recruitment and activation of inflammatory cells, which may have relevance to its efficacy in airway diseases.

scholarly journals Mucus Release and Airway Constriction by TMEM16A May Worsen Pathology in Inflammatory Lung Disease

2021 ◽  
Vol 22 (15) ◽  
pp. 7852
Author(s):  
Raquel Centeio ◽  
Jiraporn Ousingsawat ◽  
Inês Cabrita ◽  
Rainer Schreiber ◽  
Khaoula Talbi ◽  
...  
Keyword(s):  
Goblet Cell ◽  
Airway Disease ◽  
Airway Epithelial Cells ◽  
Mucus Secretion ◽  
Airway Epithelial ◽  
Mucus Production ◽  
Airway Constriction ◽  
Goblet Cell Differentiation

Activation of the Ca2+ activated Cl- channel TMEM16A is proposed as a treatment in inflammatory airway disease. It is assumed that activation of TMEM16A will induce electrolyte secretion, and thus reduce airway mucus plugging and improve mucociliary clearance. A benefit of activation of TMEM16A was shown in vitro and in studies in sheep, but others reported an increase in mucus production and airway contraction by activation of TMEM16A. We analyzed expression of TMEM16A in healthy and inflamed human and mouse airways and examined the consequences of activation or inhibition of TMEM16A in asthmatic mice. TMEM16A was found to be upregulated in the lungs of patients with asthma or cystic fibrosis, as well as in the airways of asthmatic mice. Activation or potentiation of TMEM16A by the compounds Eact or brevenal, respectively, induced acute mucus release from airway goblet cells and induced bronchoconstriction in mice in vivo. In contrast, niclosamide, an inhibitor of TMEM16A, blocked mucus production and mucus secretion in vivo and in vitro. Treatment of airway epithelial cells with niclosamide strongly inhibited expression of the essential transcription factor of Th2-dependent inflammation and goblet cell differentiation, SAM pointed domain-containing ETS-like factor (SPDEF). Activation of TMEM16A in people with inflammatory airway diseases is likely to induce mucus secretion along with airway constriction. In contrast, inhibitors of TMEM16A may suppress pulmonary Th2 inflammation, goblet cell metaplasia, mucus production, and bronchoconstriction, partially by inhibiting expression of SPDEF.

scholarly journals NAD(P)H quinone oxidoreductase 1 regulates neutrophil elastase-induced mucous cell metaplasia

2012 ◽  
Vol 303 (3) ◽  
pp. L181-L188 ◽  
Author(s):  
Marisa L. Meyer ◽  
Erin N. Potts-Kant ◽  
Andrew J. Ghio ◽  
Bernard M. Fischer ◽  
W. Michael Foster ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Neutrophil Elastase ◽  
Mucous Cell ◽  
Airway Epithelial Cells ◽  
Interleukin 4 ◽  
Airway Epithelial ◽  
Wild Type ◽  
Quinone Oxidoreductase

Mucous cell metaplasia (MCM) and neutrophil-predominant airway inflammation are pathological features of chronic inflammatory airway diseases. A signature feature of MCM is increased expression of a major respiratory tract mucin, MUC5AC. Neutrophil elastase (NE) upregulates MUC5AC in primary airway epithelial cells by generating reactive oxygen species, and this response is due in part to upregulation of NADPH quinone oxidoreductase 1 (NQO1) activity. Delivery of NE directly to the airway triggers inflammation and MCM and increases synthesis and secretion of MUC5AC protein from airway epithelial cells. We hypothesized that NE-induced MCM is mediated in vivo by NQO1. Male wild-type and Nqo1-null mice (C57BL/6 background) were exposed to human NE (50 μg) or vehicle via oropharyngeal aspiration on days 1, 4, and 7. On days 8 and 11, lung tissues and bronchoalveolar lavage (BAL) samples were obtained and evaluated for MCM, inflammation, and oxidative stress. MCM, inflammation, and production of specific cytokines, granulocyte-macrophage colony-stimulating factor, macrophage inflammatory protein-2, interleukin-4, and interleukin-5 were diminished in NE-treated Nqo1-null mice compared with NE-treated wild-type mice. However, in contrast to the role of NQO1 in vitro, we demonstrate that NE-treated Nqo1-null mice had greater levels of BAL and lung tissue lipid carbonyls and greater BAL iron on day 11, all consistent with increased oxidative stress. NQO1 is required for NE-induced inflammation and MCM. This model system demonstrates that NE-induced MCM directly correlates with inflammation, but not with oxidative stress.

scholarly journals Eosinophil Responses at the Airway Epithelial Barrier during the Early Phase of Influenza a Virus Infection in C57BL/6 Mice

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 509 ◽  
Author(s):  
Meenakshi Tiwary ◽  
Robert J. Rooney ◽  
Swantje Liedmann ◽  
Kim S. LeMessurier ◽  
Amali E. Samarasinghe
Keyword(s):  
Epithelial Cells ◽  
Influenza A Virus ◽  
Early Phase ◽  
Influenza A ◽  
Airway Epithelial Cells ◽  
Epithelial Barrier ◽  
Virus Infectivity ◽  
Airway Epithelial ◽  
In Vivo Models

Eosinophils, previously considered terminally differentiated effector cells, have multifaceted functions in tissues. We previously found that allergic mice with eosinophil-rich inflammation were protected from severe influenza and discovered specialized antiviral effector functions for eosinophils including promoting cellular immunity during influenza. In this study, we hypothesized that eosinophil responses during the early phase of influenza contribute to host protection. Using in vitro and in vivo models, we found that eosinophils were rapidly and dynamically regulated upon influenza A virus (IAV) exposure to gain migratory capabilities to traffic to lymphoid organs after pulmonary infection. Eosinophils were capable of neutralizing virus upon contact and combinations of eosinophil granule proteins reduced virus infectivity through hemagglutinin inactivation. Bi-directional crosstalk between IAV-exposed epithelial cells and eosinophils occurred after IAV infection and cross-regulation promoted barrier responses to improve antiviral defenses in airway epithelial cells. Direct interactions between eosinophils and airway epithelial cells after IAV infection prevented virus-induced cytopathology in airway epithelial cells in vitro, and eosinophil recipient IAV-infected mice also maintained normal airway epithelial cell morphology. Our data suggest that eosinophils are important in the early phase of IAV infection providing immediate protection to the epithelial barrier until adaptive immune responses are deployed during influenza.

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