Journal articles on the topic 'Airway epithelium'
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1
Burch, L. H., C. R. Talbot, M. R. Knowles, C. M. Canessa, B. C. Rossier, and R. C. Boucher. "Relative expression of the human epithelial Na+ channel subunits in normal and cystic fibrosis airways." American Journal of Physiology-Cell Physiology 269, no. 2 (August 1, 1995): C511—C518. http://dx.doi.org/10.1152/ajpcell.1995.269.2.c511.
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The availability of the newly cloned subunits (alpha, beta, gamma) of the epithelial Na+ channel (ENaC) permits molecular studies of the pathogenesis of the abnormal Na+ transport rates of cystic fibrosis (CF) airway epithelia. Northern analyses of airway epithelia showed that both normal and CF airway epithelia express ENaC subunit mRNAs in a ratio of alpha > beta > gamma. In situ hybridization studies revealed expression of all three ENaC subunits in the superficial epithelium and the alpha- and beta-subunits in the gland ductular and acinar epithelium of both normal and CF airways. Ribonuclease protection assays revealed that the steady-state levels of alpha-, beta-, and gamma-ENaC mRNAs were similar in CF and normal airway superficial epithelia. These findings indicate that 1) Na+ transport defects in CF airways disease may be expressed in glandular acinar and ductal epithelium as well as superficial epithelium, and 2) the molecular pathogenesis of Na+ hyperabsorption in CF airways does not reflect increased levels of Na+ channel mRNAs, and probably number, but reflects an absence of the normal inhibitory regulation of Na+ channels by CF transmembrane conductance regulator proteins.
2
Inoue, Hideki, Kaho Akimoto, Tetsuya Homma, Akihiko Tanaka, and Hironori Sagara. "Airway Epithelial Dysfunction in Asthma: Relevant to Epidermal Growth Factor Receptors and Airway Epithelial Cells." Journal of Clinical Medicine 9, no. 11 (November 18, 2020): 3698. http://dx.doi.org/10.3390/jcm9113698.
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Airway epithelium plays an important role as the first barrier from external pathogens, including bacteria, viruses, chemical substances, and allergic components. Airway epithelial cells also have pivotal roles as immunological coordinators of defense mechanisms to transfer signals to immunologic cells to eliminate external pathogens from airways. Impaired airway epithelium allows the pathogens to remain in the airway epithelium, which induces aberrant immunological reactions. Dysregulated functions of asthmatic airway epithelium have been reported in terms of impaired wound repair, fragile tight junctions, and excessive proliferation, leading to airway remodeling, which contributes to aberrant airway responses caused by external pathogens. To maintain airway epithelium integrity, a family of epidermal growth factor receptors (EGFR) have pivotal roles in mechanisms of cell growth, proliferation, and differentiation. There are extensive studies focusing on the relation between EGFR and asthma pathophysiology, which describe airway remodeling, airway hypermucus secretion, as well as immunological responses of airway inflammation. Furthermore, the second EGFR family member, erythroblastosis oncogene B2 (ErbB2), has been recognized to be involved with impaired wound recovery and epithelial differentiation in asthmatic airway epithelium. In this review, the roles of the EGFR family in asthmatic airway epithelium are focused on to elucidate the pathogenesis of airway epithelial dysfunction in asthma.
3
White, Steven R. "Apoptosis and the Airway Epithelium." Journal of Allergy 2011 (December 13, 2011): 1–21. http://dx.doi.org/10.1155/2011/948406.
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The airway epithelium functions as a barrier and front line of host defense in the lung. Apoptosis or programmed cell death can be elicited in the epithelium as a response to viral infection, exposure to allergen or to environmental toxins, or to drugs. While apoptosis can be induced via activation of death receptors on the cell surface or by disruption of mitochondrial polarity, epithelial cells compared to inflammatory cells are more resistant to apoptotic stimuli. This paper focuses on the response of airway epithelium to apoptosis in the normal state, apoptosis as a potential regulator of the number and types of epithelial cells in the airway, and the contribution of epithelial cell apoptosis in important airways diseases.
4
Sparrow, M. P., H. W. Mitchell, and T. I. Omari. "The epithelial barrier and airway responsiveness." Canadian Journal of Physiology and Pharmacology 73, no. 2 (February 1, 1995): 180–90. http://dx.doi.org/10.1139/y95-027.
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Epithelial injury and bronchial hyperresponsiveness are commonly associated with airway disease, and are widely considered to occur as the result of inflammatory changes in the airway wall. Mechanistically, the airway epithelium may influence the sensitivity of the airways to provocative stimuli through its primary function as a cellular barrier between the air and the interstitium, or by liberating a variety of bronchoactive mediators, e.g., lipoxygenase and cyclooxygenase products, nitric oxide, and an epithelium-derived relaxing factor (EpDIF). Much attention has focused on the latter function of the epithelium, particularly the putative EpDIF, which has an action considered to be analogous to that of endothelium-derived relaxing factor in blood vessels. The modulation of airway calibre by the epithelium has recently been investigated in vitro using tubular preparations of bronchi, where removal of, or damage to, the epithelium increases the sensitivity to agonists by several orders of magnitude. This contrasts with the effect of removing the epithelium on strips or rings of airway wall, where the increase in sensitivity is small and rather variable, but this has been the primary observation for proposing a putative EpDIF. This review evaluates the barrier or protective function of the airway epithelium and the major role it plays in the modulation of airway responsiveness. A role of a putative EpDIF seems, at best, to be of minor functional significance.Key words: epithelial barrier, bronchial hyprresponsiveness, airway smooth muscle, epithelial permeability, epithelium-derived inhibitory factor.
5
Gallos, George, Elizabeth Townsend, Peter Yim, Laszlo Virag, Yi Zhang, Dingbang Xu, Matthew Bacchetta, and Charles W. Emala. "Airway epithelium is a predominant source of endogenous airway GABA and contributes to relaxation of airway smooth muscle tone." American Journal of Physiology-Lung Cellular and Molecular Physiology 304, no. 3 (February 1, 2013): L191—L197. http://dx.doi.org/10.1152/ajplung.00274.2012.
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Chronic obstructive pulmonary disease and asthma are characterized by hyperreactive airway responses that predispose patients to episodes of acute airway constriction. Recent studies suggest a complex paradigm of GABAergic signaling in airways that involves GABA-mediated relaxation of airway smooth muscle. However, the cellular source of airway GABA and mechanisms regulating its release remain unknown. We questioned whether epithelium is a major source of GABA in the airway and whether the absence of epithelium-derived GABA contributes to greater airway smooth muscle force. Messenger RNA encoding glutamic acid decarboxylase (GAD) 65/67 was quantitatively measured in human airway epithelium and smooth muscle. HPLC quantified GABA levels in guinea pig tracheal ring segments under basal or stimulated conditions with or without epithelium. The role of endogenous GABA in the maintenance of an acetylcholine contraction in human airway and guinea pig airway smooth muscle was assessed in organ baths. A 37.5-fold greater amount of mRNA encoding GAD 67 was detected in human epithelium vs. airway smooth muscle cells. HPLC confirmed that guinea pig airways with intact epithelium have a higher constitutive elution of GABA under basal or KCl-depolarized conditions compared with epithelium-denuded airway rings. Inhibition of GABA transporters significantly suppressed KCl-mediated release of GABA from epithelium-intact airways, but tetrodotoxin was without effect. The presence of intact epithelium had a significant GABAergic-mediated prorelaxant effect on the maintenance of contractile tone. Airway epithelium is a predominant cellular source of endogenous GABA in the airway and contributes significant prorelaxant GABA effects on airway smooth muscle force.
6
Vanoni, Simone, Giada Scantamburlo, Silvia Dossena, Markus Paulmichl, and Charity Nofziger. "Interleukin-Mediated Pendrin Transcriptional Regulation in Airway and Esophageal Epithelia." International Journal of Molecular Sciences 20, no. 3 (February 9, 2019): 731. http://dx.doi.org/10.3390/ijms20030731.
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Pendrin (SLC26A4), a Cl−/anion exchanger, is expressed at high levels in kidney, thyroid, and inner ear epithelia, where it has an essential role in bicarbonate secretion/chloride reabsorption, iodide accumulation, and endolymph ion balance, respectively. Pendrin is expressed at lower levels in other tissues, such as airways and esophageal epithelia, where it is transcriptionally regulated by the inflammatory cytokines interleukin (IL)-4 and IL-13 through a signal transducer and activator of transcription 6 (STAT6)-mediated pathway. In the airway epithelium, increased pendrin expression during inflammatory diseases leads to imbalances in airway surface liquid thickness and mucin release, while, in the esophageal epithelium, dysregulated pendrin expression is supposed to impact the intracellular pH regulation system. In this review, we discuss some of the recent findings on interleukin-mediated transcriptional regulation of pendrin and how this dysregulation impacts airway and esophagus epithelial homeostasis during inflammatory diseases.
7
Hyde, Dallas M., David J. Magliano, and Charles G. Plopper. "Morphometric Assessment of Pulmonary Toxicity in the Rodent Lung." Toxicologic Pathology 19, no. 4_part_1 (November 1991): 428–46. http://dx.doi.org/10.1177/0192623391019004-112.
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An overview of the epithelial and interstitial composition of rat respiratory airways shows complexity and variability. Airway epithelium varies in 1) different airway levels; 2) the types and ultrastructure of cells present; and 3) the abundance, type, and composition of stored secretory product. Unbiased sampling of airways is done using airway microdissection with a specific binary numbering system for airway generation. Vertical sections of selected airways are used to sample epithelium and interstitium. We determine the ratios of the volume of epithelial or interstitial cells to the total epithelial or interstitial volume (Vv). The surface of the epithelial basal lamina to the total epithelial or interstitial volume (Sv) is determined using point and intersection counting with a cycloid grid. Using the selector method on serial plastic sections, we determine the number of epithelial or interstitial cells per volume (Nv) of total epithelium or interstitium. We calculate the number of epithelial or interstitial cells per surface of epithelial basal lamina (Ns) by dividing Nv by Sv where the volumes are the same compartment. We calculate average cell volumes (v̄) for specific epithelial and interstitial cells by dividing the absolute nuclear volume by the ratio of the nucleus to cell volume (Vv). By multiplying the average cell volume (v̄) by the ratio of organellar volume to cell volume (Vv), we calculate the average organellar volume per cell. These unbiased stereological approaches are critical in a quantitative evaluation of toxicological injury of rat tracheobronchial airways.
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Dey, R. D., J. B. Altemus, I. Zervos, and J. Hoffpauir. "Origin and colocalization of CGRP- and SP-reactive nerves in cat airway epithelium." Journal of Applied Physiology 68, no. 2 (February 1, 1990): 770–78. http://dx.doi.org/10.1152/jappl.1990.68.2.770.
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A combination of neuroanatomic techniques was used to examine the origin and neuropeptide content of nerve fibers in the airway epithelium of adult cats. By the use of immunocytochemical methods, the peptides substance P (SP) and calcitonin gene-related peptide (CGRP) were colocalized in airway epithelial nerve fibers. Two days after wheat germ agglutinin (WGA) was injected into the nodose ganglion, fibers containing WGA immunoreactivity (IR) were detected in the airway epithelium. SP-like immunoreactivity (LI) and CGRP-LI were demonstrated separately in the WGA-IR fibers, establishing their origin from nerve cell bodies of nodose ganglion. Vagal transection inferior to the nodose ganglion reduced the number of SP- and CGRP-IR fibers by greater than 90% in ipsilateral airways. In contralateral airways, SP-IR fibers were substantially reduced, whereas the effect on CGRP-IR fibers was not statistically significant. Vagotomy superior to the nodose ganglion did not alter the density of peptide-IR fibers. The results prove that SP- and CGRP-IR nerve fibers of cat airway epithelium originate from nerve cell bodies in the nodose ganglion and that SP- and CGRP-like peptides may be stored together in some nerve fibers of the airway epithelium.
9
Flodby, Per, Janice M. Liebler, Mitsuhiro Sunohara, Dan R. Castillo, Alicia M. McConnell, Manda S. Krishnaveni, Agnes Banfalvi, et al. "Region-specific role for Pten in maintenance of epithelial phenotype and integrity." American Journal of Physiology-Lung Cellular and Molecular Physiology 312, no. 1 (January 1, 2017): L131—L142. http://dx.doi.org/10.1152/ajplung.00005.2015.
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Previous studies have demonstrated resistance to naphthalene-induced injury in proximal airways of mice with lung epithelial-specific deletion of the tumor-suppressor gene Pten, attributed to increased proliferation of airway progenitors. We tested effects of Pten loss following bleomycin injury, a model typically used to study distal lung epithelial injury, in conditional PtenSFTPC-cre knockout mice. Pten-deficient airway epithelium exhibited marked hyperplasia, particularly in small bronchioles and at bronchoalveolar duct junctions, with reduced E-cadherin and β-catenin expression between cells toward the luminal aspect of the hyperplastic epithelium. Bronchiolar epithelial and alveolar epithelial type II (AT2) cells in PtenSFTPC-cre mice showed decreased expression of epithelial markers and increased expression of mesenchymal markers, suggesting at least partial epithelial-mesenchymal transition at baseline. Surprisingly, and in contrast to previous studies, mutant mice were exquisitely sensitive to bleomycin, manifesting rapid weight loss, respiratory distress, increased early mortality (by day 5), and reduced dynamic lung compliance. This was accompanied by sloughing of the hyperplastic airway epithelium with occlusion of small bronchioles by cellular debris, without evidence of increased parenchymal lung injury. Increased airway epithelial cell apoptosis due to loss of antioxidant defenses, reflected by decreased expression of superoxide dismutase 3, in combination with deficient intercellular adhesion, likely predisposed to airway sloughing in knockout mice. These findings demonstrate an important role for Pten in maintenance of airway epithelial phenotype integrity and indicate that responses to Pten deletion in respiratory epithelium following acute lung injury are highly context-dependent and region-specific.
10
Soleas, John P., Ana Paz, Paula Marcus, Alison McGuigan, and Thomas K. Waddell. "Engineering Airway Epithelium." Journal of Biomedicine and Biotechnology 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/982971.
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Airway epithelium is constantly presented with injurious signals, yet under healthy circumstances, the epithelium maintains its innate immune barrier and mucociliary elevator function. This suggests that airway epithelium has regenerative potential (I. R. Telford and C. F. Bridgman, 1990). In practice, however, airway regeneration is problematic because of slow turnover and dedifferentiation of epithelium thereby hindering regeneration and increasing time necessary for full maturation and function. Based on the anatomy and biology of the airway epithelium, a variety of tissue engineering tools available could be utilized to overcome the barriers currently seen in airway epithelial generation. This paper describes the structure, function, and repair mechanisms in native epithelium and highlights specific and manipulatable tissue engineering signals that could be of great use in the creation of artificial airway epithelium.
11
Chen, Jiawen, Seyed Mohammad Mir, Maria R. Hudock, Meghan R. Pinezich, Panpan Chen, Matthew Bacchetta, Gordana Vunjak-Novakovic, and Jinho Kim. "Opto-electromechanical quantification of epithelial barrier function in injured and healthy airway tissues." APL Bioengineering 7, no. 1 (March 1, 2023): 016104. http://dx.doi.org/10.1063/5.0123127.
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The airway epithelium lining the luminal surface of the respiratory tract creates a protective barrier that ensures maintenance of tissue homeostasis and prevention of respiratory diseases. The airway epithelium, unfortunately, is frequently injured by inhaled toxic materials, trauma, or medical procedures. Substantial or repeated airway epithelial injury can lead to dysregulated intrinsic repair pathways and aberrant tissue remodeling that can lead to dysfunctional airway epithelium. While disruption in the epithelial integrity is directly linked to degraded epithelial barrier function, the correlation between the structure and function of the airway epithelium remains elusive. In this study, we quantified the impact of acutely induced airway epithelium injury on disruption of the epithelial barrier functions. By monitoring alternation of the flow motions and tissue bioimpedance at local injury site, degradation of the epithelial functions, including mucociliary clearance and tight/adherens junction formation, were accurately determined with a high spatiotemporal resolution. Computational models that can simulate and predict the disruption of the mucociliary flow and airway tissue bioimpedance have been generated to assist interpretation of the experimental results. Collectively, findings of this study advance our knowledge of the structure–function relationships of the airway epithelium that can promote development of efficient and accurate diagnosis of airway tissue injury.
12
Varner, Victor D., Jason P. Gleghorn, Erin Miller, Derek C. Radisky, and Celeste M. Nelson. "Mechanically patterning the embryonic airway epithelium." Proceedings of the National Academy of Sciences 112, no. 30 (July 13, 2015): 9230–35. http://dx.doi.org/10.1073/pnas.1504102112.
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Collections of cells must be patterned spatially during embryonic development to generate the intricate architectures of mature tissues. In several cases, including the formation of the branched airways of the lung, reciprocal signaling between an epithelium and its surrounding mesenchyme helps generate these spatial patterns. Several molecular signals are thought to interact via reaction-diffusion kinetics to create distinct biochemical patterns, which act as molecular precursors to actual, physical patterns of biological structure and function. Here, however, we show that purely physical mechanisms can drive spatial patterning within embryonic epithelia. Specifically, we find that a growth-induced physical instability defines the relative locations of branches within the developing murine airway epithelium in the absence of mesenchyme. The dominant wavelength of this instability determines the branching pattern and is controlled by epithelial growth rates. These data suggest that physical mechanisms can create the biological patterns that underlie tissue morphogenesis in the embryo.
13
Winter, Michael C., Sandra S. Shasby, Dana R. Ries, and D. Michael Shasby. "PAR2 activation interrupts E-cadherin adhesion and compromises the airway epithelial barrier: protective effect of β-agonists." American Journal of Physiology-Lung Cellular and Molecular Physiology 291, no. 4 (October 2006): L628—L635. http://dx.doi.org/10.1152/ajplung.00046.2006.
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The airway epithelium is an important barrier between the environment and subepithelial tissues. The epithelium is also divided into functionally restricted apical and basolateral domains, and this restriction is dependent on the elements of the barrier. The protease-activated receptor-2 (PAR2) receptor is expressed in airway epithelium, and its activation initiates multiple effects including enhanced airway inflammation and reactivity. We hypothesized that activation of PAR2 would interrupt E-cadherin adhesion and compromise the airway epithelial barrier. The PAR2-activating peptide (PAR2-AP, SLIGRL) caused an immediate ∼50% decrease in the transepithelial resistance of primary human airway epithelium that persisted for 6–10 min. The decrease in resistance was accompanied by an increase in mannitol flux across the epithelium and occurred in cystic fibrosis transmembrane conductance receptor (CFTR) epithelium pretreated with amiloride to block Na and Cl conductances, confirming that the decrease in resistance represented an increase in paracellular conductance. In parallel experiments, activation of PAR2 interrupted the adhesion of E-cadherin-expressing L cells and of primary airway epithelial cells to an immobilized E-cadherin extracellular domain, confirming the hypothesis that activation of PAR2 interrupts E-cadherin adhesion. Selective interruption of E-cadherin adhesion with antibody to E-cadherin decreased the transepithelial resistance of primary airway epithelium by >80%. Pretreatment of airway epithelium or the E-cadherin-expressing L cells with the long-acting β-agonist salmeterol prevented PAR2 activation from interrupting E-cadherin adhesion and compromising the airway epithelial barrier. Activation of PAR2 interrupts E-cadherin adhesion and compromises the airway epithelial barrier.
14
Gochuico, Bernadette R., Kathleen M. Miranda, Edith M. Hessel, Joris J. De Bie, Antoon J. M. Van Oosterhout, William W. Cruikshank, and Alan Fine. "Airway epithelial Fas ligand expression: potential role in modulating bronchial inflammation." American Journal of Physiology-Lung Cellular and Molecular Physiology 274, no. 3 (March 1, 1998): L444—L449. http://dx.doi.org/10.1152/ajplung.1998.274.3.l444.
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Epithelium-derived Fas ligand is believed to modulate inflammation within various tissues. In this paper, we report findings that suggest a similar immunoregulatory role for Fas ligand in the lung. First, Fas ligand was localized to nonciliated, cuboidal airway epithelial cells (Clara cells) throughout the airways in the normal murine lung by employing nonisotopic in situ hybridization and immunohistochemistry. Second, gldmutant mice, which express a dysfunctional Fas ligand protein, were noted to develop prominent infiltration of inflammatory cells in submucosal and peribronchial regions of the upper and lower airways. Third, during allergic airway inflammation induced by ovalbumin in mice, cell-associated staining for Fas ligand mRNA and protein was markedly reduced in the airway epithelium. These data suggest that Clara cell-derived Fas ligand may control immune activity in the airway; thus alterations in this protective mechanism may be involved in the pathogenesis of certain inflammatory conditions of the airway, such as asthma.
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Castellani, Stefano, Sante Di Gioia, Lorena di Toma, and Massimo Conese. "Human Cellular Models for the Investigation of Lung Inflammation and Mucus Production in Cystic Fibrosis." Analytical Cellular Pathology 2018 (November 15, 2018): 1–15. http://dx.doi.org/10.1155/2018/3839803.
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Chronic inflammation, oxidative stress, mucus plugging, airway remodeling, and respiratory infections are the hallmarks of the cystic fibrosis (CF) lung disease. The airway epithelium is central in the innate immune responses to pathogens colonizing the airways, since it is involved in mucociliary clearance, senses the presence of pathogens, elicits an inflammatory response, orchestrates adaptive immunity, and activates mesenchymal cells. In this review, we focus on cellular models of the human CF airway epithelium that have been used for studying mucus production, inflammatory response, and airway remodeling, with particular reference to two- and three-dimensional cultures that better recapitulate the native airway epithelium. Cocultures of airway epithelial cells, macrophages, dendritic cells, and fibroblasts are instrumental in disease modeling, drug discovery, and identification of novel therapeutic targets. Nevertheless, they have to be implemented in the CF field yet. Finally, novel systems hijacking on tissue engineering, including three-dimensional cocultures, decellularized lungs, microfluidic devices, and lung organoids formed in bioreactors, will lead the generation of relevant human preclinical respiratory models a step forward.
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Guo, Tony J. F., Gurpreet K. Singhera, Janice M. Leung, and Delbert R. Dorscheid. "Airway Epithelial-Derived Immune Mediators in COVID-19." Viruses 15, no. 8 (July 29, 2023): 1655. http://dx.doi.org/10.3390/v15081655.
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The airway epithelium, which lines the conducting airways, is central to the defense of the lungs against inhaled particulate matter and pathogens such as SARS-CoV-2, the virus that causes COVID-19. Recognition of pathogens results in the activation of an innate and intermediate immune response which involves the release of cytokines and chemokines by the airway epithelium. This response can inhibit further viral invasion and influence adaptive immunity. However, severe COVID-19 is characterized by a hyper-inflammatory response which can give rise to clinical presentations including lung injury and lead to acute respiratory distress syndrome, viral pneumonia, coagulopathy, and multi-system organ failure. In response to SARS-CoV-2 infection, the airway epithelium can mount a maladaptive immune response which can delay viral clearance, perpetuate excessive inflammation, and contribute to the pathogenesis of severe COVID-19. In this article, we will review the barrier and immune functions of the airway epithelium, how SARS-CoV-2 can interact with the epithelium, and epithelial-derived cytokines and chemokines and their roles in COVID-19 and as biomarkers. Finally, we will discuss these immune mediators and their potential as therapeutic targets in COVID-19.
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Singh, Sabita, Joytri Dutta, Archita Ray, Atmaja Karmakar, and Ulaganathan Mabalirajan. "Airway Epithelium: A Neglected but Crucial Cell Type in Asthma Pathobiology." Diagnostics 13, no. 4 (February 20, 2023): 808. http://dx.doi.org/10.3390/diagnostics13040808.
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The features of allergic asthma are believed to be mediated mostly through the Th2 immune response. In this Th2-dominant concept, the airway epithelium is presented as the helpless victim of Th2 cytokines. However, this Th2-dominant concept is inadequate to fill some of the vital knowledge gaps in asthma pathogenesis, like the poor correlation between airway inflammation and airway remodeling and severe asthma endotypes, including Th2-low asthma, therapy resistance, etc. Since the discovery of type 2 innate lymphoid cells in 2010, asthma researchers started believing in that the airway epithelium played a crucial role, as alarmins, which are the inducers of ILC2, are almost exclusively secreted by the airway epithelium. This underscores the eminence of airway epithelium in asthma pathogenesis. However, the airway epithelium has a bipartite functionality in sustaining healthy lung homeostasis and asthmatic lungs. On the one hand, the airway epithelium maintains lung homeostasis against environmental irritants/pollutants with the aid of its various armamentaria, including its chemosensory apparatus and detoxification system. Alternatively, it induces an ILC2-mediated type 2 immune response through alarmins to amplify the inflammatory response. However, the available evidence indicates that restoring epithelial health may attenuate asthmatic features. Thus, we conjecture that an epithelium-driven concept in asthma pathogenesis could fill most of the gaps in current asthma knowledge, and the incorporation of epithelial-protective agents to enhance the robustness of the epithelial barrier and the combative capacity of the airway epithelium against exogenous irritants/allergens may mitigate asthma incidence and severity, resulting in better asthma control.
18
Gohy, Sophie T., Cloé Hupin, Chantal Fregimilicka, Bruno R. Detry, Caroline Bouzin, Héloïse Gaide Chevronay, Marylène Lecocq, et al. "Imprinting of the COPD airway epithelium for dedifferentiation and mesenchymal transition." European Respiratory Journal 45, no. 5 (March 5, 2015): 1258–72. http://dx.doi.org/10.1183/09031936.00135814.
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In chronic obstructive pulmonary disease (COPD), epithelial changes and subepithelial fibrosis are salient features in conducting airways. Epithelial-to-mesenchymal transition (EMT) has been recently suggested in COPD, but the mechanisms and relationship to peribronchial fibrosis remain unclear. We hypothesised that de-differentiation of the COPD respiratory epithelium through EMT could participate in airway fibrosis and thereby, in airway obstruction.Surgical lung tissue and primary broncho-epithelial cultures (in air–liquid interface (ALI)) from 104 patients were assessed for EMT markers. Cell cultures were also assayed for mesenchymal features and for the role of transforming growth factor (TGF)-β1.The bronchial epithelium from COPD patients showed increased vimentin and decreased ZO-1 and E-cadherin expression. Increased vimentin expression correlated with basement membrane thickening and airflow limitation. ALI broncho-epithelial cells from COPD patients also displayed EMT phenotype in up to 2 weeks of culture, were more spindle shaped and released more fibronectin. Targeting TGF-β1 during ALI differentiation prevented vimentin induction and fibronectin release.In COPD, the airway epithelium displays features of de-differentiation towards mesenchymal cells, which correlate with peribronchial fibrosis and airflow limitation, and which are partly due to a TGF-β1-driven epithelial reprogramming.
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Vermeer, Paola D., Lacey Panko, Philip Karp, John H. Lee, and Joseph Zabner. "Differentiation of human airway epithelia is dependent on erbB2." American Journal of Physiology-Lung Cellular and Molecular Physiology 291, no. 2 (August 2006): L175—L180. http://dx.doi.org/10.1152/ajplung.00547.2005.
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A clinical case documented a reversible change in airway epithelial differentiation that coincided with the initiation and discontinuation of trastuzumab, an anti-erbB2 antibody. This prompted the investigation into whether blocking the erbB2 receptor alters differentiation of the airway epithelium. To test this hypothesis, we treated an in vitro model of well-differentiated human airway epithelia with trastuzumab or heregulin-α, an erbB ligand. In addition, coculturing with human lung fibroblasts tested whether in vivo subepithelial fibroblasts function as an endogenous source of ligands able to activate erbB receptors expressed by the overlying epithelial cells. Epithelia were stained with hematoxylin and eosin and used for morphometric analysis. Trastuzumab treatment decreased the ciliated cell number by 49% and increased the metaplastic, flat cell number by 640%. Heregulin-α treatment increased epithelial height and decreased the number of metaplastic and nonciliated columnar cells, whereas it increased the goblet cell number. We found that normal human lung fibroblasts express transforming growth factor-α, heparin-binding epidermal-like growth factor, epiregulin, heregulin-α, and amphiregulin, all of which are erbB ligands. Cocultures of airway epithelia with primary fibroblasts increased epithelial height comparable to that achieved following heregulin-α treatment. These data show that erbB2 stimulation is required for maintaining epithelial differentiation. Furthermore, the mesenchyme underlying the airway epithelium secretes a variety of erbB ligands that may direct various pathways of epithelial differentiation.
20
Hyde, Dallas M., Jack R. Harkema, Charles G. Plopper, and Judith A. St George. "Morphometric approaches to the cell biology of normal and injured pulmonary epithelium." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 288–89. http://dx.doi.org/10.1017/s0424820100135046.
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A comparative overview of the epithelial composition of the respiratory airways emphasizes the complexity and diversity found in different species of mammals. Airway epithelium varies in (1) types of cells present, (2) the same airway level in different species, (3) different airway levels in the same species, (4) abundance and type of both secretory cell and stored secretory product, (5) composition of secretory product, (6) organization at the terminal respiratory bronchiole and alveolar duct junction, and (7) ultrastructure of the same cell type in different species. It is unclear what impact this diversity in the airways of different species has, but it strongly suggests the potential for wide variation in the cellular response to injury. These data emphasize the necessity for careful selection of model species and a thorough knowledge of species-specific cellular morphometric and morphologic characteristics when studying the tracheobronchial epithelium.A critical step in obtaining these data is the use of morphometric and electron microscopic techniques. Fixation and sampling are critical aspects of any morphometric study of the lung.
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Hamilton, Nick J. I., Dani Do Hyang Lee, Kate H. C. Gowers, Colin R. Butler, Elizabeth F. Maughan, Benjamin Jevans, Jessica C. Orr, et al. "Bioengineered airway epithelial grafts with mucociliary function based on collagen IV- and laminin-containing extracellular matrix scaffolds." European Respiratory Journal 55, no. 6 (May 22, 2020): 1901200. http://dx.doi.org/10.1183/13993003.01200-2019.
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Current methods to replace damaged upper airway epithelium with exogenous cells are limited. Existing strategies use grafts that lack mucociliary function, leading to infection and the retention of secretions and keratin debris. Strategies that regenerate airway epithelium with mucociliary function are clearly desirable and would enable new treatments for complex airway disease.Here, we investigated the influence of the extracellular matrix (ECM) on airway epithelial cell adherence, proliferation and mucociliary function in the context of bioengineered mucosal grafts. In vitro, primary human bronchial epithelial cells (HBECs) adhered most readily to collagen IV. Biological, biomimetic and synthetic scaffolds were compared in terms of their ECM protein content and airway epithelial cell adherence.Collagen IV and laminin were preserved on the surface of decellularised dermis and epithelial cell attachment to decellularised dermis was greater than to the biomimetic or synthetic alternatives tested. Blocking epithelial integrin α2 led to decreased adherence to collagen IV and to decellularised dermis scaffolds. At air–liquid interface (ALI), bronchial epithelial cells cultured on decellularised dermis scaffolds formed a differentiated respiratory epithelium with mucociliary function. Using in vivo chick chorioallantoic membrane (CAM), rabbit airway and immunocompromised mouse models, we showed short-term preservation of the cell layer following transplantation.Our results demonstrate the feasibility of generating HBEC grafts on clinically applicable decellularised dermis scaffolds and identify matrix proteins and integrins important for this process. The long-term survivability of pre-differentiated epithelia and the relative merits of this approach against transplanting basal cells should be assessed further in pre-clinical airway transplantation models.
22
Carson, Johnny L., William Reed, Thomas Lucier, Luisa Brighton, Todd M. Gambling, Chien-Hui Huang, and Albert M. Collier. "Axonemal dynein expression in human fetal tracheal epithelium." American Journal of Physiology-Lung Cellular and Molecular Physiology 282, no. 3 (March 1, 2002): L421—L430. http://dx.doi.org/10.1152/ajplung.00147.2001.
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Ciliogenesis in human fetal airway epithelium occurs from 11 to 24 gestational weeks. Using genetic and antigenic markers specific for human axonemal dynein heavy chain 9, we characterized temporal aspects of axonemal dynein expression associated with large airway epithelial ciliogenesis during human fetal development. Late in the first trimester, an undifferentiated columnar epithelium is characteristic of the large airways, and immunocytochemical studies exhibited focal localization of axonemal dynein antigen on luminal epithelial cell borders at sites consistent with emergent ciliary beds. From 12 to 22 wk, immunocytochemical labeling of new ciliary beds was prominent, and localization within the cytoplasm of epithelial cells suggested avid synthesis of axonemal dynein in advance of ciliogenic events. Quantitative RT-PCR of tracheal RNA and in situ hybridization studies compared favorably with immunocytochemical findings with the earliest expression of axonemal dynein at 9–10 wk gestation. These studies have documented that axonemal dynein is expressed early in human fetal life during airway epithelial maturation and well before histological or ultrastructural evidence of ciliogenesis is apparent.
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Widdicombe, Jonathan. "Airway Epithelium." Colloquium Series on Integrated Systems Physiology: From Molecule to Function 4, no. 5 (November 15, 2012): 1–148. http://dx.doi.org/10.4199/c00063ed1v01y201206isp036.
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Ferrante, S., T. Hackett, C. Hoptay, J. Engelhardt, J. Ingram, Y. Zhang, S. Alcala, et al. "9: AN IN VIVO MODEL OF HUMAN AIRWAYS FOR INVESTIGATING FIBROSIS." Journal of Investigative Medicine 64, no. 3 (February 25, 2016): 802.2–803. http://dx.doi.org/10.1136/jim-2016-000080.9.
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Purpose of StudyLimited models exist to investigate the airway epithelium's role in repair, regeneration, and pathology of chronic obstructive lung diseases. We introduce a human asthmatic airway epithelial xenograft system integrating a proliferating and differentiating airway epithelium with an actively remodeling rodent mesenchyme in an immunocompromised murine host. We hypothesized that epithelial regeneration in asthma induces underlying matrix fibrosis.Methods UsedHuman airway epithelial cells from asthmatic and non-asthmatic donors (n=5 per group) were seeded into decellularized rat tracheas. Tracheas were ligated to a sterile tubing cassette and implanted subcutaneously in the flanks of athymic nude mice. Grafts were harvested at 2, 4, or 6 weeks for analysis of tissue histology, fibrillar collagen deposition, and TGFβ1 activation. Non-transplantable human lungs from asthmatic and non-asthmatic donor FFPE sections were analyzed using similar methods.Summary of ResultsGrafted epithelial cells generated a differentiated epithelium with basal, ciliated, and mucus cells. By 4 weeks post-engraftment, asthmatic-derived epithelia showed decreased numbers of ciliated cells and E-cadherin expression compared to non-asthmatic controls, similar to human lung biopsy tissue. While there was no evidence of matrix remodeling in acellular xenografts, grafts seeded with asthmatic-derived epithelial cells had 3 times as much fibrillar collagen at 6 weeks post-engraftment as non-asthmatic epithelial seeded grafts. This was accompanied by a >2-fold induction of matrix TGFβ1 [with evidence of pSMAD3 activity] in asthmatic grafts at 4 weeks (positive pixels/total field pixels=0.12±0.001 vs. 0.05±0.001; p=0.003) and 6 weeks (0.09±0.02 vs. 0.04±0.01; p=0.044) post-engraftment.ConclusionsWe show in this model that asthmatic epithelium alone is sufficient to drive aberrant mesenchymal remodeling, specifically with fibrillar collagen deposition in asthmatic-derived xenografts.These xenografts are a major advance over current animal models of asthma in that they permit direct assessment of the epithelial-mesenchymal trophic unit.
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Moody, Mark, Carey Pennington, Carsten Schultz, Ray Caldwell, Carlo Dinkel, Michael W. Rossi, Sharon McNamara, Jonathan Widdicombe, Sherif Gabriel, and Alexis E. Traynor-Kaplan. "Inositol polyphosphate derivative inhibits Na+ transport and improves fluid dynamics in cystic fibrosis airway epithelia." American Journal of Physiology-Cell Physiology 289, no. 3 (September 2005): C512—C520. http://dx.doi.org/10.1152/ajpcell.00591.2004.
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Amiloride-sensitive, epithelial Na+ channel (ENaC)-mediated, active absorption of Na+ is elevated in the airway epithelium of cystic fibrosis (CF) patients, resulting in excess fluid removal from the airway lumen. This excess fluid/volume absorption corresponds to CF transmembrane regulator-linked defects in ENaC regulation, resulting in the reduced mucociliary clearance found in CF airways. Herein we show that INO-4995, a synthetic analog of the intracellular signaling molecule, d- myo-inositol 3,4,5,6-tetrakisphosphate, inhibits Na+ and fluid absorption across CF airway epithelia, thus alleviating this critical pathology. This conclusion was based on electrophysiological studies, fluid absorption, and 22Na+ flux measurements in CF airway epithelia, contrasted with normal epithelia, and on electrophysiological studies in Madin-Darby canine kidney cells and 3T3 cells overexpressing ENaC. The effects of INO-4995 were long-lasting, dose-dependent, and more pronounced in epithelia from CF patients vs. controls. These findings support preclinical development of INO-4995 for CF treatment and demonstrate for the first time the therapeutic potential of inositol polyphosphate derivatives.
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Tan, Wen, Jilei Lin, Yaping Wang, Li Yan, Linyan Ying, Jihong Dai, Zhou Fu, and Jingyue Liu. "Vitamin A–regulated ciliated cells promote airway epithelium repair in an asthma mouse model." Allergologia et Immunopathologia 51, no. 1 (January 1, 2023): 116–25. http://dx.doi.org/10.15586/aei.v51i1.700.
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Background: Asthma is a chronic inflammatory airway disease that causes damage to and exfo-liation of the airway epithelium. The continuous damage to the airway epithelium in asthma cannot be repaired quickly and generates irreversible damage, repeated attacks, and aggravation. Vitamin A (VA) has multifarious biological functions that include maintaining membrane stability and integrity of the structure and function of epithelial cells. Our research explored the role of VA in repairing the airway epithelium and provided a novel treatment strategy for asthma. Methods: A mouse asthma model was established by house dust mite (HDM) and treated with VA by gavage. Human bronchial epithelial (16HBE) cells were treated with HDM and all-trans retinoic acid (ATRA) in vitro. We analyzed the mRNA and protein expression of characteristic markers, such as acetyl-α-tubulin (Ac-TUB) and FOXJ1 in ciliated cells and MUC5AC in secretory cells, mucus secretion, airway inflammation, the morphology of cilia, and the integrity of the airway epithelium. Results: Findings showed destruction of airway epithelial integrity, damaged cilia, high mucus secretion, increased MUC5AC expression, and decreased Ac-TUB and FOXJ1 expression in asth-matic mice. The VA intervention reversed the effect on Ac-TUB and FOXJ1 and promoted ciliated cells to repair the damage and maintain airway epithelial integrity. In 16HBE cells, we could confirm that ATRA promoted the expression of Ac-TUB and FOXJ1. Conclusion: These results demonstrated that VA-regulated ciliated cells to repair the damaged airway epithelium caused by asthma and maintain airway epithelial integrity. VA intervention is a potential adjunct to conventional treatment for asthma.
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Munakata, M., I. Huang, W. Mitzner, and H. Menkes. "Protective role of epithelium in the guinea pig airway." Journal of Applied Physiology 66, no. 4 (April 1, 1989): 1547–52. http://dx.doi.org/10.1152/jappl.1989.66.4.1547.
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We developed an in vitro system to assess the role of the epithelium in regulating airway tone using the intact guinea pig trachea (J. Appl. Physiol. 64: 466–471, 1988). This method allows us to study the response of the airway when its inner epithelial surface or its outer serosal surface is stimulated independently. Using this system we evaluated how the presence of intact epithelium can affect pharmacological responsiveness. We first examined responses of tracheae with intact epithelium to histamine, acetylcholine, and hypertonic KCl when stimulated from the epithelial or serosal side. We then examined the effect of epithelial denudation on the responses to these agonists. With an intact epithelium, stimulation of the inner epithelial side always caused significantly smaller changes in diameter than stimulation of the outer serosal side. After mechanical denudation of the epithelium, these differences were almost completely abolished. In the absence of intact epithelium, the trachea was 35-fold more sensitive to histamine and 115-fold more sensitive to acetylcholine when these agents were applied to the inner epithelial side. In addition, the presence of an intact epithelium almost completely inhibited any response to epithelial side challenge with hypertonic KCl. These results indicate that the airway epithelial layer has a potent protective role in airway responses to luminal side stimuli, leading us to speculate that changes in airway reactivity measured in various conditions including asthma may result in part from changes in epithelial function.
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Calvén, Jenny, Elisabeth Ax, and Madeleine Rådinger. "The Airway Epithelium—A Central Player in Asthma Pathogenesis." International Journal of Molecular Sciences 21, no. 23 (November 24, 2020): 8907. http://dx.doi.org/10.3390/ijms21238907.
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Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction in response to a wide range of exogenous stimuli. The airway epithelium is the first line of defense and plays an important role in initiating host defense and controlling immune responses. Indeed, increasing evidence indicates a range of abnormalities in various aspects of epithelial barrier function in asthma. A central part of this impairment is a disruption of the airway epithelial layer, allowing inhaled substances to pass more easily into the submucosa where they may interact with immune cells. Furthermore, many of the identified susceptibility genes for asthma are expressed in the airway epithelium. This review focuses on the biology of the airway epithelium in health and its pathobiology in asthma. We will specifically discuss external triggers such as allergens, viruses and alarmins and the effect of type 2 inflammatory responses on airway epithelial function in asthma. We will also discuss epigenetic mechanisms responding to external stimuli on the level of transcriptional and posttranscriptional regulation of gene expression, as well the airway epithelium as a potential treatment target in asthma.
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Sadik, Sunusi, Yanhong Lu, Shaoxuan Zhu, Jiayu Cai, and Lan Lan Mi. "Group 2 innate lymphoid cells (ILC2s): The spotlight in asthma pathogenesis and lung tissue injury." Allergologia et Immunopathologia 49, no. 2 (March 1, 2021): 208–16. http://dx.doi.org/10.15586/aei.v49i2.29.
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Asthma is a heterogeneous disease with ranging etiology and severity. Asthma is a disease of chronic inflammation of the airways, with clinical symptoms of wheezing, breathlessness, cough, and chest tightness manifested as chronic fixed or variable airflow obstruction and airway hyperresponsiveness that predispose the airway epithelium to repeated injury, repair, and regeneration. In recent years, innate lymphoid cells (ILC1, ILC2, and ILC3) have been discovered. The predominant ILC type found in the lung tissue is group 2 innate lymphoid cells (ILC2s). Upon damage to the airway epithelium mediating the release of epithelial cytokines (TSLP, IL-33, and IL-25) ensued the activation of ILC2 in an antigen-independent manner. Activated ILC2 produces a significant amount of type 2 cytokines (IL-4, IL-5, IL-9, and IL-13), altogether contributing to type 2 inflammation in the airways. ILC2s are mediators of type 2 immunity for many type 2 inflammatory diseases such as asthma, since ILC2s were reported to play an important role in asthma pathogenesis. Here we discuss the role of ILC2 in the development of asthma and ILC2 effector cytokines (IL-4, IL-5, and IL-13) contributing to airway epithelial structural changes.
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Mo, Yiqun, Jing Chen, Connie F. Schlueter, and Gary W. Hoyle. "Differential susceptibility of inbred mouse strains to chlorine-induced airway fibrosis." American Journal of Physiology-Lung Cellular and Molecular Physiology 304, no. 2 (January 15, 2013): L92—L102. http://dx.doi.org/10.1152/ajplung.00272.2012.
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Chlorine is a reactive gas that is considered a chemical threat agent. Humans who develop acute lung injury from chlorine inhalation typically recover normal lung function; however, a subset can experience chronic airway disease. To examine pathological changes following chlorine-induced lung injury, mice were exposed to a single high dose of chlorine, and repair of the lung was analyzed at multiple times after exposure. In FVB/NJ mice, chlorine inhalation caused pronounced fibrosis of larger airways that developed by day 7 after exposure and was associated with airway hyperreactivity. In contrast, A/J mice had little or no airway fibrosis and had normal lung function at day 7. Unexposed FVB/NJ mice had less keratin 5 staining (basal cell marker) than A/J mice in large intrapulmonary airways where epithelial repair was poor and fibrosis developed after chlorine exposure. FVB/NJ mice had large areas devoid of epithelium on day 1 after exposure leading to fibroproliferative lesions on days 4 and 7. A/J mice had airways covered by squamous keratin 5-stained cells on day 1 that transitioned to a highly proliferative reparative epithelium by day 4 followed by the reappearance of ciliated and Clara cells by day 7. The data suggest that lack of basal cells in the large intrapulmonary airways and failure to effect epithelial repair at these sites are factors contributing to the development of airway fibrosis in FVB/NJ mice. The observed differences in susceptibility to chlorine-induced airway disease provide a model in which mechanisms and treatment of airway fibrosis can be investigated.
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Delplanque, A., C. Coraux, R. Tirouvanziam, I. Khazaal, E. Puchelle, P. Ambros, D. Gaillard, and B. Peault. "Epithelial stem cell-mediated development of the human respiratory mucosa in SCID mice." Journal of Cell Science 113, no. 5 (March 1, 2000): 767–78. http://dx.doi.org/10.1242/jcs.113.5.767.
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We have developed an in vivo assay for progenitor cells of the human tracheobronchial epithelium relying on the transplantation of human prenatal respiratory tissues into severe combined immunodeficiency mice. Engrafted embryonic or fetal open tracheobronchial rudiments are rapidly closed at each end by a neoformed membrane that we named the operculum. After 2–4 weeks, differentiated human respiratory epithelium covers both the native airway matrix and the new operculum. Human epithelial cells dissociated from either emerging embryonic lung primordia or mature xenografts were seeded in host human airway grafts, of which native epithelium had been eliminated by several cycles of freezing and thawing. All grafts seeded with donor epithelial cells and implanted back into SCID mice recovered a surface mucociliary epithelium expressing expected markers and secreting mucus. Spontaneous epithelium regrowth was never observed in control unseeded, denuded grafts. In some experiments, donor epithelial cells and host denuded airway were sex-mismatched and the donor origin of newly formed epithelial structures was confirmed by sex chromosome detection. After two rounds of seeding and reimplantation, a normal epithelium was observed to line the 3rd generation operculum. These observations substantiate a functional assay for human candidate airway epithelium stem cells.
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O'Reilly, Megan, Stuart B. Hooper, Beth J. Allison, Sharon J. Flecknoe, Ken Snibson, Richard Harding, and Foula Sozo. "Persistent bronchiolar remodeling following brief ventilation of the very immature ovine lung." American Journal of Physiology-Lung Cellular and Molecular Physiology 297, no. 5 (November 2009): L992—L1001. http://dx.doi.org/10.1152/ajplung.00099.2009.
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Children and adults who were mechanically ventilated following preterm birth are at increased risk of reduced lung function, suggesting small airway dysfunction. We hypothesized that short periods of mechanical ventilation of very immature lungs can induce persistent bronchiolar remodeling that may adversely affect later lung function. Our objectives were to characterize the effects of brief, positive-pressure ventilation per se on the small airways in very immature, surfactant-deficient lungs and to determine whether the effects persist after the cessation of ventilation. Fetal sheep (0.75 of term) were mechanically ventilated in utero with room air (peak inspiratory pressure 40 cmH2O, positive end-expiratory pressure 4 cmH2O, 65 breaths/min) for 6 or 12 h, after which tissues were collected; another group was studied 7 days after 12-h ventilation. Age-matched unventilated fetuses were controls. The mean basement membrane perimeter of airways analyzed was 548.6 ± 8.5 μm and was not different between groups. Immediately after ventilation, 21% of airways had epithelial injury; in airways with intact epithelium, there was more airway smooth muscle (ASM) and less collagen, and the epithelium contained more mucin-containing and apoptotic cells and fewer proliferating cells. Seven days after ventilation, epithelial injury was absent but the epithelium was thicker, with greater cell turnover; there were increased amounts of bronchiolar collagen and ASM and fewer alveolar attachments. The increase in ASM was likely due to cellular hypertrophy rather than hyperplasia. We conclude that brief mechanical ventilation of the very immature lung induces remodeling of the bronchiolar epithelium and walls that lasts for at least 7 days; such changes could contribute to later airway dysfunction.
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de Fays, Charlotte, François M. Carlier, Sophie Gohy, and Charles Pilette. "Secretory Immunoglobulin A Immunity in Chronic Obstructive Respiratory Diseases." Cells 11, no. 8 (April 13, 2022): 1324. http://dx.doi.org/10.3390/cells11081324.
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Chronic obstructive pulmonary disease (COPD), asthma and cystic fibrosis (CF) are distinct respiratory diseases that share features such as the obstruction of small airways and disease flare-ups that are called exacerbations and are often caused by infections. Along the airway epithelium, immunoglobulin (Ig) A contributes to first line mucosal protection against inhaled particles and pathogens. Dimeric IgA produced by mucosal plasma cells is transported towards the apical pole of airway epithelial cells by the polymeric Ig receptor (pIgR), where it is released as secretory IgA. Secretory IgA mediates immune exclusion and promotes the clearance of pathogens from the airway surface by inhibiting their adherence to the epithelium. In this review, we summarize the current knowledge regarding alterations of the IgA/pIgR system observed in those major obstructive airway diseases and discuss their implication for disease pathogenesis.
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Guembe, Laura, and Ana C. Villaro. "Immunohistochemical Mapping of Endothelin in the Developing and Adult Mouse Lung." Journal of Histochemistry & Cytochemistry 49, no. 10 (October 2001): 1301–9. http://dx.doi.org/10.1177/002215540104901013.
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Endothelins (ET) are a family of regulatory peptides displaying, among other abilities, potent constrictor actions. We studied the perinatal time course expression and distribution of ET in the mouse airway epithelium. In fetal mouse, ET-immunoreactivity (IR) appeared earlier (gestational Day 18) in the epithelium of upper (bronchi and large bronchioles) than in lower airways, being scarce and mainly located in the apical cytoplasm. As the lung developed, ET-IR became gradually stronger and extended throughout the cell in both bronchi and bronchioles. ET-IR was found in most airway epithelial cells. Clara cells were positive for ET, whereas ciliated and endocrine cells were not. In adult lungs, part of the myocytes and parenchymal cells also showed ET-IR. In both developing and adult mouse lungs, the cell distribution of ET-IR in the epithelium is compatible with apical and/or basal secretion. The presence of ET in mouse airway epithelium during the perinatal period may indicate a role for ET as a growth factor in lung development and its involvement in control of lung ventilation at birth.
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Heguy, Adriana, Ben-Gary Harvey, Philip L. Leopold, Igor Dolgalev, Tina Raman, and Ronald G. Crystal. "Responses of the human airway epithelium transcriptome to in vivo injury." Physiological Genomics 29, no. 2 (April 2007): 139–48. http://dx.doi.org/10.1152/physiolgenomics.00167.2006.
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To identify genes participating in human airway epithelial repair, we used bronchoscopy and brushing to denude the airway epithelium of healthy individuals, sequentially sampled the same region 7 and 14 days later, and assessed gene expression by Affymetrix microarrays with TaqMan RT-PCR confirmation. Histologically, the injured area was completely covered by a partially redifferentiated epithelial layer after 7 days; by 14 days the airway epithelium was very similar to the uninjured state. At day 7 compared with resting epithelium, there were substantial differences in gene expression pattern, with a distinctive airway epithelial “repair transcriptome” of actively proliferating cells in the process of redifferentiation. The repair transcriptome at 7 days was dominated by cell cycle, signal transduction, metabolism and transport, and transcription genes. Interestingly, the majority of differentially expressed cell cycle genes belonged to the G2 and M phases, suggesting that the proliferating cells were relatively synchronized 1 wk following injury. At 14 days postinjury, the expression profile was similar to that of resting airway epithelium. These observations provide a baseline of the functional gene categories participating in the process of normal human airway epithelial repair that can be used in future studies of injury and repair in airway epithelial diseases.
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Bartlett, Jennifer, Lokesh Gakhar, Jon Penterman, Pradeep Singh, Rama K. Mallampalli, Edith Porter, and Paul B. McCray. "PLUNC: a multifunctional surfactant of the airways." Biochemical Society Transactions 39, no. 4 (July 20, 2011): 1012–16. http://dx.doi.org/10.1042/bst0391012.
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PLUNC (palate, lung and nasal epithelium clone) protein is an abundant secretory product of epithelia throughout the mammalian conducting airways. Despite its homology with the innate immune defence molecules BPI (bactericidal/permeability-increasing protein) and LBP (lipopolysaccharide-binding protein), it has been difficult to define the functions of PLUNC. Based on its marked hydrophobicity and expression pattern, we hypothesized that PLUNC is an airway surfactant. We found that purified recombinant human PLUNC exhibited potent surfactant activity by several different measures, and experiments with airway epithelial cell lines and primary cultures indicate that native PLUNC makes a significant contribution to the overall surface tension in airway epithelial secretions. Interestingly, we also found that physiologically relevant concentrations of PLUNC-inhibited Pseudomonas aeruginosa biofilm formation in vitro without acting directly as a bactericide. This finding suggests that PLUNC protein may inhibit biofilm formation by airway pathogens, perhaps through its dispersant properties. Our data, along with reports from other groups on activity against some airway pathogens, expand on an emerging picture of PLUNC as a multifunctional protein, which plays a novel role in airway defences at the air/liquid interface.
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Sugiyama, T., M. Yamamoto-Hino, K. Wasano, K. Mikoshiba, and M. Hasegawa. "Subtype-specific expression patterns of inositol 1,4,5-trisphosphate receptors in rat airway epithelial cells." Journal of Histochemistry & Cytochemistry 44, no. 11 (November 1996): 1237–42. http://dx.doi.org/10.1177/44.11.8918898.
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We investigated the immunohistochemical localization of inositol 1,4,5-trisphosphate receptor (IP3R) Types 1, 2, and 3 in rat airway epithelium using the monoclonal antibodies KM1112, KM1083, and KM1082 specific for each type of IP3R. The epithelium from trachea to distal intrapulmonary airways (bronchioles) showed positive immunoreactivity for all types of IP3R. However, cell type as well as subcellular site immunoreactivity for each type of IP3R varied. IP3R Type 1 was found only in the apical thin cytoplasmic area of ciliated cells throughout all airway levels. IP3R Type 2 was exclusively localized to the entire cytoplasm of ciliated cells from the trachea to bronchioles. IP3R Type 3 was expressed mainly in the supranuclear cytoplasm not only of ciliated cells at all airway levels but also in Clara cells of the bronchiolar epithelium. Double fluorescent staining using combinations of KM1083 and Wisteria floribunda lectin or anti-rat 10-KD Clara cell-specific protein antibody confirmed that the IP3R Type 2-positive cells were neither seromucous cells nor Clara cells. These results indicate that the expression of three types of IP3Rs in different cell types and subcellular sites may reflect diverse physiological functions of IP3Rs within airway epithelial cells. The double staining studies suggested that the anti-IP3R Type 2 monoclonal antibody KM1083 would be a specific cell marker for ciliated cells of the airway epithelium.
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El Mays, Tamer Y., Mahmoud Saifeddine, Parichita Choudhury, Morley D. Hollenberg, and Francis H. Y. Green. "Carbon dioxide enhances substance P-induced epithelium-dependent bronchial smooth muscle relaxation in Sprague–Dawley rats." Canadian Journal of Physiology and Pharmacology 89, no. 7 (July 2011): 513–20. http://dx.doi.org/10.1139/y11-052.
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Hypocapnia and hypercapnia constrict and relax airway smooth muscle, respectively, through pH- and calcium (Ca2+)-mediated mechanisms. In this study we explore a potential role for the airway epithelium in these responses to carbon dioxide (CO2). Contractile and relaxant responses of isolated rat bronchial rings were measured under hypocapnic, eucapnic, and hypercapnic conditions. Substance P was added to methacholine precontracted bronchial rings with and without epithelium. The role of Ca2+ was assessed using Ca2+-free solutions and a Ca2+ channel blocker, nifedipine. The effects of pH were assessed in solutions with HEPES buffer. Hypocapnic challenge increased the organ bath’s pH and increased bronchial smooth muscle resting tension. This effect was abolished with HEPES buffer and partially inhibited by nifedipine. Hypocapnic conditions suppressed substance P-induced epithelium-dependent relaxation, whereas hypercapnia augmented the response. The epithelial hypocapnic effect was pH dependent, whereas the hypercapnic effect was pH independent. CO2 had no effect on the epithelial independent smooth muscle agonists methacholine and isoproterenol. In conclusion our data indicate that, in addition to the effects of pH and Ca2+, CO2 affects airway smooth muscle by a pH-independent, epithelium-mediated mechanism. These findings could potentially lead to new treatments for asthma involving CO2-sensing receptors in the airways.
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Zhou, Jian, Martha B. Alvarez-Elizondo, Elliot Botvinick, and Steven C. George. "Local small airway epithelial injury induces global smooth muscle contraction and airway constriction." Journal of Applied Physiology 112, no. 4 (February 15, 2012): 627–37. http://dx.doi.org/10.1152/japplphysiol.00739.2011.
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Small airway epithelial cells form a continuous sheet lining the conducting airways, which serves many functions including a physical barrier to protect the underlying tissue. In asthma, injury to epithelial cells can occur during bronchoconstriction, which may exacerbate airway hyperreactivity. To investigate the role of epithelial cell rupture in airway constriction, laser ablation was used to precisely rupture individual airway epithelial cells of small airways (<300-μm diameter) in rat lung slices (∼250-μm thick). Laser ablation of single epithelial cells using a femtosecond laser reproducibly induced airway contraction to ∼70% of the original cross-sectional area within several seconds, and the contraction lasted for up to 40 s. The airway constriction could be mimicked by mechanical rupture of a single epithelial cell using a sharp glass micropipette but not with a blunt glass pipette. These results suggest that soluble mediators released from the wounded epithelial cell induce global airway contraction. To confirm this hypothesis, the lysate of primary human small airway epithelial cells stimulated a similar airway contraction. Laser ablation of single epithelial cells triggered a single instantaneous Ca2+ wave in the epithelium, and multiple Ca2+ waves in smooth muscle cells, which were delayed by several seconds. Removal of extracellular Ca2+ or decreasing intracellular Ca2+ both blocked laser-induced airway contraction. We conclude that local epithelial cell rupture induces rapid and global airway constriction through release of soluble mediators and subsequent Ca2+-dependent smooth muscle shortening.
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Lan, Bo, Jennifer A. Mitchel, Michael J. O’Sullivan, Chan Young Park, Jae Hun Kim, William C. Cole, James P. Butler, and Jin-Ah Park. "Airway epithelial compression promotes airway smooth muscle proliferation and contraction." American Journal of Physiology-Lung Cellular and Molecular Physiology 315, no. 5 (November 1, 2018): L645—L652. http://dx.doi.org/10.1152/ajplung.00261.2018.
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During acute bronchoconstriction, the airway epithelium becomes mechanically compressed, as airway smooth muscle contracts and the airway narrows. This mechanical compression activates airway epithelium to promote asthmatic airway remodeling. However, whether compressed airway epithelium can feed back on the cause of bronchoconstriction has remained an open question. Here we examine the potential for epithelial compression to augment proliferation and contraction of airway smooth muscle, and thus potentiate further bronchoconstriction and epithelial compression. Well-differentiated primary human bronchial epithelial (HBE) cells maintained in air-liquid interface culture were mechanically compressed to mimic the effect of bronchoconstriction. Primary human airway smooth muscle (HASM) cells were incubated with conditioned media collected from mechanically compressed HBE cells to examine the effect of epithelial-derived mediators on HASM cell proliferation using an EdU assay and HASM cell contraction using traction microscopy. An endothelin receptor antagonist, PD-145065, was employed to probe the role of HBE cell-derived endothelin-1 on the proliferation and contraction of HASM cells. Conditioned media from compressed HBE cells increased HASM cell proliferation, independent of the endothelin-1 signaling pathway. However, conditioned media from compressed HBE cells significantly increased HASM cell basal contraction and histamine-induced contraction, both of which depended on the endothelin-1 signaling pathway. Our data demonstrate that mechanical compression of bronchial epithelial cells contributes to proliferation and basal contraction of airway smooth muscle cells and that augmented contraction depends on epithelial cell-derived endothelin-1. By means of both airway smooth muscle remodeling and contractility, our findings suggest a causal role of epithelial compression on asthma pathogenesis.
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Muggeo, Anaëlle, Christelle Coraux, and Thomas Guillard. "Current concepts on Pseudomonas aeruginosa interaction with human airway epithelium." PLOS Pathogens 19, no. 3 (March 30, 2023): e1011221. http://dx.doi.org/10.1371/journal.ppat.1011221.
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Pseudomonas aeruginosa is a major, but opportunistic, respiratory pathogen, which rarely infects healthy individuals, mainly due to the barrier effect of the human airway epithelium (HAE). This review explores the interaction of P. aeruginosa with HAE and the progression of the infection. The basolateral part of the epithelium, which includes the basolateral membrane of the epithelial cells and the basement membrane, is inaccessible in normal tight epithelia with intact junctions. We highlight how P. aeruginosa exploits weaknesses in the HAE barrier to gain access to the basolateral part of the epithelium. This access is crucial to initiate respiratory infection and is mainly observed in the injured epithelium, in repairing or chronically remodeled epithelium, and during extrusion of senescent cells or cell multiplication during normal epithelium renewal. The subsequent adhesion of the bacteria and cytotoxic action of virulence factors, including the toxins delivered by the type 3 secretion system (T3SS), lead to retractions and cell death. Eventually, P. aeruginosa progressively reaches the basement membrane and propagates radially through the basal part of the epithelium to disseminate using twitching and flagellar motility.
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McNEER, R. Richard, Daming HUANG, L. Nevis FREGIEN, and L. Kermit CARRAWAY. "Sialomucin complex in the rat respiratory tract: a model for its role in epithelial protection." Biochemical Journal 330, no. 2 (March 1, 1998): 737–44. http://dx.doi.org/10.1042/bj3300737.
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The pulmonary epithelium has a multitude of specialized functions, which depend on regulated growth and differentiation of several cell types. One such function is the synthesis and secretion of mucins, which offer the epithelium protection from and a means for removal of noxious environmental factors. Sialomucin complex (SMC) is a heterodimeric glycoprotein consisting of a mucin subunit (ASGP-1, ascites sialoglycoprotein-1) and a transmembrane protein (ASGP-2) with two epidermal-growth-factor-like domains. SMC was originally discovered in a highly metastatic rat mammary adenocarcinoma and has been implicated in metastasis and in the protection of the tumour cells from natural killer cells. It can also act as a ligand for the receptor tyrosine kinase 185neu, suggesting that it is bifunctional as well as heterodimeric. SMC is expressed on the epithelium of rat conducting airways, with the highest levels occurring in the proximal trachea and progressively decreasing into the bronchioles. Airway SMC consists of two forms: a soluble form that lacks the C-terminal cytoplasmic and transmembrane domains and accounts for about 70% of the total, and a membrane-associated form that has the C-terminal domains. Immunocytochemical analyses show that SMC is predominantly present on the apical surfaces of the airway epithelium, but not in goblet cells. Soluble form can be removed from the trachea by rinsing, suggesting that a fraction of the protein is adsorbed to the apical surface. Based on these results, we propose a protective mechanism in which membrane and soluble forms of SMC are produced by airway luminal epithelial cells to provide a cell-associated epithelial glycoprotein barrier that also serves as an interface with flowing mucus. In support of this mechanism, we demonstrated secretion of soluble SMC by primary cultures of tracheal epithelial cells. This model suggests that SMC is a critical element in the protective barrier of the airway epithelium.
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Sparrow, M. P., P. K. McFawn, T. I. Omari, and H. W. Mitchell. "Activation of smooth muscle in the airway wall, force production, and airway narrowing." Canadian Journal of Physiology and Pharmacology 70, no. 4 (April 1, 1992): 607–14. http://dx.doi.org/10.1139/y92-078.
Full textAbstract:
Airway narrowing depends on smooth muscle force production and muscle shortening, but the structural and geometric properties exhibited by individual generations of the bronchial tree largely determine the extent and characteristics of airway narrowing. Properties of major importance include the nature and integrity of the epithelium, the structural and mechanical properties of the airway wall, as well as airway diameter. The influence of these properties on airway narrowing measured as flow or flow resistance in large and small diameter segments of airways from pig lung is described using a novel preparation, the perfused bronchial segment.Key words: airway narrowing, bronchi, smooth muscle, epithelium.
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De Rose, Virginia, Kevin Molloy, Sophie Gohy, Charles Pilette, and Catherine M. Greene. "Airway Epithelium Dysfunction in Cystic Fibrosis and COPD." Mediators of Inflammation 2018 (2018): 1–20. http://dx.doi.org/10.1155/2018/1309746.
Full textAbstract:
Cystic fibrosis is a genetic disease caused by mutations in the CFTR gene, whereas chronic obstructive pulmonary disease (COPD) is mainly caused by environmental factors (mostly cigarette smoking) on a genetically susceptible background. Although the etiology and pathogenesis of these diseases are different, both are associated with progressive airflow obstruction, airway neutrophilic inflammation, and recurrent exacerbations, suggesting common mechanisms. The airway epithelium plays a crucial role in maintaining normal airway functions. Major molecular and morphologic changes occur in the airway epithelium in both CF and COPD, and growing evidence suggests that airway epithelial dysfunction is involved in disease initiation and progression in both diseases. Structural and functional abnormalities in both airway and alveolar epithelium have a relevant impact on alteration of host defences, immune/inflammatory response, and the repair process leading to progressive lung damage and impaired lung function. In this review, we address the evidence for a critical role of dysfunctional airway epithelial cells in chronic airway inflammation and remodelling in CF and COPD, highlighting the common mechanisms involved in the epithelial dysfunction as well as the similarities and differences of the two diseases.
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Shamsuddin, A. K. M., and Paul M. Quinton. "Concurrent absorption and secretion of airway surface liquids and bicarbonate secretion in human bronchioles." American Journal of Physiology-Lung Cellular and Molecular Physiology 316, no. 5 (May 1, 2019): L953—L960. http://dx.doi.org/10.1152/ajplung.00545.2018.
Full textAbstract:
Although small airways account for the largest fraction of the total conducting airway surfaces, the epithelial fluid and electrolyte transport in small, native airway epithelia has not been well characterized. Investigations have been limited, no doubt, by the complex tissue architecture as well as by its inaccessibility, small dimensions, and lack of applicable assays, especially in human tissues. To better understand how the critically thin layer of airway surface liquid (ASL) is maintained, we applied a “capillary”-Ussing chamber (area ≈1 mm2) to measure ion transport properties of bronchioles with diameters of ~2 mm isolated from resected specimens of excised human lungs. We found that the small human airway, constitutively and concurrently, secretes and absorbs fluid as observed in porcine small airways (50). We found that the human bronchiolar epithelium is also highly anion selective and constitutively secretes bicarbonate ([Formula: see text]), which can be enhanced pharmacologically by cAMP as well as Ca2+-mediated agonists. Concurrent secretion and absorption of surface liquid along with [Formula: see text] secretion help explain how the delicate volume of the fluid lining the human small airway is physiologically buffered and maintained in a steady state that avoids desiccating or flooding the small airway with ASL.
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Fischer, Bernard M., Jessica K. Wong, Simone Degan, Apparao B. Kummarapurugu, Shuo Zheng, Prashamsha Haridass, and Judith A. Voynow. "Increased expression of senescence markers in cystic fibrosis airways." American Journal of Physiology-Lung Cellular and Molecular Physiology 304, no. 6 (March 15, 2013): L394—L400. http://dx.doi.org/10.1152/ajplung.00091.2012.
Full textAbstract:
Cystic Fibrosis (CF) is a chronic lung disease characterized by chronic neutrophilic airway inflammation and increased levels of neutrophil elastase (NE) in the airways. We have previously reported that NE treatment triggers cell cycle arrest. Cell cycle arrest can lead to senescence, a complete loss of replicative capacity. Importantly, senescent cells can be proinflammatory and would perpetuate CF chronic inflammation. By immunohistochemistry, we evaluated whether airway sections from CF and control subjects expressed markers of senescence, including p16INK4a(p16), a cyclin-dependent kinase inhibitor, phospho-Histone H2A.X (γH2A.X), and phospho-checkpoint 2 kinase (phospho-Chk2), which are also DNA damage response markers. Compared with airway epithelium from control subjects, CF airway epithelium had increased levels of expression of all three senescence markers. We hypothesized that the high load of NE in the CF airway triggers epithelial senescence by upregulating expression of p16, which inhibits cyclin-dependent kinase 4 (CDK4). Normal human bronchial epithelial (NHBE) cells, cultured in air-liquid interface were treated with NE (0, 200, and 500 nM) to induce visible injury. Total cell lysates were collected and evaluated by Western analysis for p16 protein expression and CDK4 kinase activity. NE significantly increased p16 expression and decreased CDK4 kinase activity in NHBE cells. These results support the concept that NE triggers expression of senescence markers in CF airway epithelial cells.
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Colvin, Jennifer S., Andrew C. White, Stephen J. Pratt, and David M. Ornitz. "Lung hypoplasia and neonatal death inFgf9-null mice identify this gene as an essential regulator of lung mesenchyme." Development 128, no. 11 (June 1, 2001): 2095–106. http://dx.doi.org/10.1242/dev.128.11.2095.
Full textAbstract:
Mammalian lung develops as an evagination of ventral gut endoderm into the underlying mesenchyme. Iterative epithelial branching, regulated by the surrounding mesenchyme, generates an elaborate network of airways from the initial lung bud. Fibroblast growth factors (FGFs) often mediate epithelial-mesenchymal interactions and mesenchymal Fgf10 is essential for epithelial branching in the developing lung. However, no FGF has been shown to regulate lung mesenchyme. In embryonic lung, Fgf9 is detected in airway epithelium and visceral pleura at E10.5, but is restricted to the pleura by E12.5. We report that mice homozygous for a targeted disruption of Fgf9 exhibit lung hypoplasia and early postnatal death. Fgf9−/− lungs exhibit reduced mesenchyme and decreased branching of airways, but show significant distal airspace formation and pneumocyte differentiation. Our results suggest that Fgf9 affects lung size by stimulating mesenchymal proliferation. The reduction in the amount of mesenchyme in Fgf9−/− lungs limits expression of mesenchymal Fgf10. We suggest a model whereby FGF9 signaling from the epithelium and reciprocal FGF10 signaling from the mesenchyme coordinately regulate epithelial airway branching and organ size during lung embryogenesis.
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Martens, Katleen, Brecht Steelant, and Dominique M. A. Bullens. "Taste Receptors: The Gatekeepers of the Airway Epithelium." Cells 10, no. 11 (October 26, 2021): 2889. http://dx.doi.org/10.3390/cells10112889.
Full textAbstract:
Taste receptors are well known for their role in the sensation of taste. Surprisingly, the expression and involvement of taste receptors in chemosensory processes outside the tongue have been recently identified in many organs including the airways. Currently, a clear understanding of the airway-specific function of these receptors and the endogenous activating/inhibitory ligands is lagging. The focus of this review is on recent physiological and clinical data describing the taste receptors in the airways and their activation by secreted bacterial compounds. Taste receptors in the airways are potentially involved in three different immune pathways (i.e., the production of nitric oxide and antimicrobial peptides secretion, modulation of ciliary beat frequency, and bronchial smooth muscle cell relaxation). Moreover, genetic polymorphisms in these receptors may alter the patients’ susceptibility to certain types of respiratory infections as well as to differential outcomes in patients with chronic inflammatory airway diseases such as chronic rhinosinusitis and asthma. A better understanding of the function of taste receptors in the airways may lead to the development of a novel class of therapeutic molecules that can stimulate airway mucosal immune responses and could treat patients with chronic airway diseases.
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Kolesnikova, Larissa, Sonja Heck, Tatyana Matrosovich, Hans-Dieter Klenk, Stephan Becker, and Mikhail Matrosovich. "Influenza virus budding from the tips of cellular microvilli in differentiated human airway epithelial cells." Journal of General Virology 94, no. 5 (May 1, 2013): 971–76. http://dx.doi.org/10.1099/vir.0.049239-0.
Full textAbstract:
The epithelium of conducting airways represents the main target for influenza virus in mammals. However, the peculiarities of virus interactions with differentiated airway epithelial cells remain largely unknown. Here, influenza virus budding was studied in differentiated cultures of human tracheobronchial epithelial cells using transmission electron microscopy. Budding of spherical and filamentous virions was observed on the apical surfaces of cells with no association with cilia and secretory granules. Quantitative analysis of the distribution of viral buds on the cell surface indicated that the tips of the microvilli represented a prominent site of influenza virus budding in the human airway epithelium. As the microvilli of differentiated cells are involved in many fundamental cell functions, these data will prompt further studies on the biological significance of microvilli-associated budding for virus replication, transmission and pathogenicity.
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Davis, M. L., J. O. Ford, and R. F. Dodson. "Ultrastructure of Major Conducting Airway Epithelium in the Guinea Pig." Proceedings, annual meeting, Electron Microscopy Society of America 43 (August 1985): 566–67. http://dx.doi.org/10.1017/s0424820100119612.
Full textAbstract:
Guinea pigs have served as experimental models in a variety of pulmonary research including that concerned with asbestos related disease which is of particular interest in our laboratory. A search of the literature revealed several papers concerned with various characteristics of airway epithelium in both normal and experimentally manipulated guinea pigs, yet no studies could be found which systematically addressed the epithelial structure and organization in major airways. The present study was undertaken to fully characterize these areas at the electron microscopic level in order to provide data from healthy animals which can act as baseline information in experimental studies of airway epithelium. Initial findings from the trachea and main bronchi are presented here.