scholarly journals The Role of Hippo/YAP Signaling in Alveolar Repair and Pulmonary Fibrosis

2021 ◽  
Vol 8 ◽  
Author(s):  
Jason J. Gokey ◽  
Saawan D. Patel ◽  
Jonathan A. Kropski
Keyword(s):  
Pulmonary Fibrosis ◽  
Respiratory Function ◽  
Alveolar Epithelium ◽  
Current Evidence ◽  
Alveolar Type ◽  
Effective Strategies ◽  
Matrix Deposition ◽  
Alveolar Development ◽  
Activated Fibroblasts

Pulmonary fibrosis is characterized by loss of normal alveoli, accumulation of pathologic activated fibroblasts, and exuberant extracellular matrix deposition that over time can lead to progressive loss of respiratory function and death. This loss of respiratory function is associated with the loss of alveolar type 1 cells (AT1) that play a crucial role in gas exchange and the depletion of the alveolar type 2 cells (AT2) that act as progenitor cells to regenerate the AT1 and AT2 cell populations during repair. Understanding the mechanisms that regulate normal alveolar repair and those associated with pathologic repair is essential to identify potential therapeutic targets to treat or delay progression of fibrotic diseases. The Hippo/YAP developmental signaling pathway has been implicated as a regulator of normal alveolar development and repair. In idiopathic pulmonary fibrosis, aberrant activation of YAP/TAZ has been demonstrated in both the alveolar epithelium and activated fibroblasts associated with increased fibrotic remodeling, and there is emerging interest in this pathway as a target for antifibrotic therapies. In this review, we summarize current evidence as to the role of the Hippo-YAP/TAZ pathway in alveolar development, homeostasis, and repair, and highlight key questions that must be resolved to determine effective strategies to modulate YAP/TAZ signaling to prevent progressive pulmonary fibrosis and enhance adaptive alveolar repair.

scholarly journals Fibrinolytic niche is requested for alveolar type 2 cell-mediated alveologenesis and injury repair

2020 ◽  
Author(s):  
Ali Gibran ◽  
Runzhen Zhao ◽  
Mo Zhang ◽  
Krishan G. Jain ◽  
Jianjun Chang ◽  
...  
Keyword(s):  
Alveolar Epithelium ◽  
Influenza Viruses ◽  
Alveolar Type ◽  
Differential Rate ◽  
Alveolar Epithelial ◽  
Proliferation And Differentiation ◽  
Marked Suppression

ABSTRACTCOVID-19, SARS, and MERS are featured by fibrinolytic dysfunction. To test the role of the fibrinolytic niche in the regeneration of alveolar epithelium, we compared the self-renewing capacity of alveolar epithelial type 2 (AT2) cells and its differentiation to AT1 cells between wild type (wt) and fibrinolytic niche deficient mice (Plau−/− and Serpine1Tg). A significant reduction in both proliferation and differentiation of deficient AT2 cells was observed in vivo and in 3D organoid cultures. This decrease was mainly restored by uPA derived A6 peptide, a binding fragment to CD44 receptors. The proliferative and differential rate of CD44+ AT2 cells was greater than that of CD44− controls. There was a reduction in transepithelial ion transport in deficient monolayers compared to wt cells. Moreover, we found a marked suppression in total AT2 cells and CD44+ subpopulation in lungs from brain dead patients with acute respiratory distress syndrome (ARDS) and a mouse model infected by influenza viruses. Thus, we demonstrate that the fibrinolytic niche can regulate AT2-mediated homeostasis and regeneration via a novel uPA-A6-CD44+-ENaC cascade.

scholarly journals The Crucial Role of NLRP3 Inflammasome in Viral Infection-Associated Fibrosing Interstitial Lung Diseases

2021 ◽  
Vol 22 (19) ◽  
pp. 10447
Author(s):  
Wiwin Is Effendi ◽  
Tatsuya Nagano
Keyword(s):  
Viral Infection ◽  
Nlrp3 Inflammasome ◽  
Lung Diseases ◽  
Alveolar Epithelium ◽  
Interstitial Lung Diseases ◽  
Molecular Signaling ◽  
Intrinsic Factors ◽  
Matrix Deposition ◽  
Age Related

Idiopathic pulmonary fibrosis (IPF), one of the most common fibrosing interstitial lung diseases (ILD), is a chronic-age-related respiratory disease that rises from repeated micro-injury of the alveolar epithelium. Environmental influences, intrinsic factors, genetic and epigenetic risk factors that lead to chronic inflammation might be implicated in the development of IPF. The exact triggers that initiate the fibrotic response in IPF remain enigmatic, but there is now increasing evidence supporting the role of chronic exposure of viral infection. During viral infection, activation of the NLRP3 inflammasome by integrating multiple cellular and molecular signaling implicates robust inflammation, fibroblast proliferation, activation of myofibroblast, matrix deposition, and aberrant epithelial-mesenchymal function. Overall, the crosstalk of the NLRP3 inflammasome and viruses can activate immune responses and inflammasome-associated molecules in the development, progression, and exacerbation of IPF.

scholarly journals Role of CCR2+ Myeloid Cells in Inflammation Responses Driven by Expression of a Surfactant Protein-C Mutant in the Alveolar Epithelium

2021 ◽  
Vol 12 ◽  
Author(s):  
Alessandro Venosa ◽  
Sophie Cowman ◽  
Jeremy Katzen ◽  
Yaniv Tomer ◽  
Brittnie S. Armstrong ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Mrna Expression ◽  
Protein C ◽  
Cell Activation ◽  
Surfactant Protein ◽  
Chronic Obstructive ◽  
Alveolar Type ◽  
Genetic Ablation ◽  
Surfactant Protein C

Acute inflammatory exacerbations (AIE) represent precipitous deteriorations of a number of chronic lung conditions, including pulmonary fibrosis (PF), chronic obstructive pulmonary disease and asthma. AIEs are marked by diffuse and persistent polycellular alveolitis that profoundly accelerate lung function decline and mortality. In particular, excess monocyte mobilization during AIE and their persistence in the lung have been linked to poor disease outcome. The etiology of AIEs remains quite uncertain, but environmental exposure and genetic predisposition/mutations have been identified as two contributing factors. Guided by clinical evidence, we have developed a mutant model of pulmonary fibrosis leveraging the PF-linked missense isoleucine to threonine substitution at position 73 [I73T] in the alveolar type-2 cell-restricted Surfactant Protein-C [SP-C] gene [SFTPC]. With this toolbox at hand, the present work investigates the role of peripheral monocytes during the initiation and progression of AIE-PF. Genetic ablation of CCR2+ monocytes (SP-CI73TCCR2KO) resulted in improved lung histology, mouse survival, and reduced inflammation compared to SP-CI73TCCR2WT cohorts. FACS analysis of CD11b+CD64-Ly6Chi monocytes isolated 3 d and 14 d after SP-CI73T induced injury reveals dynamic transcriptional changes associated with “Innate Immunity’ and ‘Extracellular Matrix Organization’ signaling. While immunohistochemical and in situ hybridization analysis revealed comparable levels of tgfb1 mRNA expression localized primarily in parenchymal cells found nearby foci of injury we found reduced effector cell activation (C1q, iNOS, Arg1) in SP-CI73TCCR2KO lungs as well as partial colocalization of tgfb1 mRNA expression in Arg1+ cells. These results provide a detailed picture of the role of resident macrophages and recruited monocytes in the context of AIE-PF driven by alveolar epithelial dysfunction.

scholarly journals Chaotic activation of developmental signalling pathways drives idiopathic pulmonary fibrosis

2020 ◽  
Vol 29 (158) ◽  
pp. 190140
Author(s):  
Antoine Froidure ◽  
Emmeline Marchal-Duval ◽  
Meline Homps-Legrand ◽  
Mada Ghanem ◽  
Aurélien Justet ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Transforming Growth Factor ◽  
Cell Transformation ◽  
Alveolar Epithelium ◽  
Transforming Growth Factor Β ◽  
Lung Parenchyma ◽  
Current Evidence ◽  
Cell Hyperplasia ◽  
Aberrant Expression

Idiopathic pulmonary fibrosis (IPF) is characterised by an important remodelling of lung parenchyma. Current evidence indicates that the disease is triggered by alveolar epithelium activation following chronic lung injury, resulting in alveolar epithelial type 2 cell hyperplasia and bronchiolisation of alveoli. Signals are then delivered to fibroblasts that undergo differentiation into myofibroblasts. These changes in lung architecture require the activation of developmental pathways that are important regulators of cell transformation, growth and migration. Among others, aberrant expression of profibrotic Wnt-β-catenin, transforming growth factor-β and Sonic hedgehog pathways in IPF fibroblasts has been assessed. In the present review, we will discuss the transcriptional integration of these different pathways during IPF as compared with lung early ontogeny. We will challenge the hypothesis that aberrant transcriptional integration of these pathways might be under the control of a chaotic dynamic, meaning that a small change in baseline conditions could be sufficient to trigger fibrosis rather than repair in a chronically injured lung. Finally, we will discuss some potential opportunities for treatment, either by suppressing deleterious mechanisms or by enhancing the expression of pathways involved in lung repair. Whether developmental mechanisms are involved in repair processes induced by stem cell therapy will also be discussed.

scholarly journals Ion Transport by Pulmonary Epithelia

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
Monika I. Hollenhorst ◽  
Katrin Richter ◽  
Martin Fronius
Keyword(s):  
Ion Transport ◽  
Fluid Layer ◽  
Alveolar Epithelium ◽  
Cell Types ◽  
Transport Processes ◽  
Alveolar Type ◽  
Type I ◽  
Basal Cells ◽  
Epithelial Ion Transport

The lung surface of air-breathing vertebrates is formed by a continuous epithelium that is covered by a fluid layer. In the airways, this epithelium is largely pseudostratified consisting of diverse cell types such as ciliated cells, goblet cells, and undifferentiated basal cells, whereas the alveolar epithelium consists of alveolar type I and alveolar type II cells. Regulation and maintenance of the volume and viscosity of the fluid layer covering the epithelium is one of the most important functions of the epithelial barrier that forms the outer surface area of the lungs. Therefore, the epithelial cells are equipped with a wide variety of ion transport proteins, among which Na+, Cl−, and K+channels have been identified to play a role in the regulation of the fluid layer. Malfunctions of pulmonary epithelial ion transport processes and, thus, impairment of the liquid balance in our lungs is associated with severe diseases, such as cystic fibrosis and pulmonary oedema. Due to the important role of pulmonary epithelial ion transport processes for proper lung function, the present paper summarizes the recent findings about composition, function, and ion transport properties of the airway epithelium as well as of the alveolar epithelium.

scholarly journals Resetting proteostasis with ISRIB promotes epithelial differentiation to attenuate pulmonary fibrosis

2021 ◽  
Vol 118 (20) ◽  
pp. e2101100118
Author(s):  
Satoshi Watanabe ◽  
Nikolay S. Markov ◽  
Ziyan Lu ◽  
Raul Piseaux Aillon ◽  
Saul Soberanes ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Lung Fibrosis ◽  
Alveolar Epithelium ◽  
Protein Translation ◽  
Alveolar Type ◽  
Fatal Disease ◽  
Epithelial Repair ◽  
Old Mice

Pulmonary fibrosis is a relentlessly progressive and often fatal disease with a paucity of available therapies. Genetic evidence implicates disordered epithelial repair, which is normally achieved by the differentiation of small cuboidal alveolar type 2 (AT2) cells into large, flattened alveolar type 1 (AT1) cells as an initiating event in pulmonary fibrosis pathogenesis. Using models of pulmonary fibrosis in young adult and old mice and a model of adult alveologenesis after pneumonectomy, we show that administration of ISRIB, a small molecule that restores protein translation by EIF2B during activation of the integrated stress response (ISR), accelerated the differentiation of AT2 into AT1 cells. Accelerated epithelial repair reduced the recruitment of profibrotic monocyte-derived alveolar macrophages and ameliorated lung fibrosis. These findings suggest a dysfunctional role for the ISR in regeneration of the alveolar epithelium after injury with implications for therapy.

scholarly journals Mesenchymal stromal cells attenuate alveolar type 2 cells senescence through regulating NAMPT-mediated NAD metabolism

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiaofan Lai ◽  
Shaojie Huang ◽  
Sijia Lin ◽  
Lvya Pu ◽  
Yaqing Wang ◽  
...  
Keyword(s):  
Pulmonary Fibrosis ◽  
Therapeutic Potential ◽  
Alveolar Type ◽  
Therapeutic Effects ◽  
Protective Effects ◽  
Nad Metabolism

Abstract Background Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive deadly fibrotic lung disease with high prevalence and mortality worldwide. The therapeutic potential of mesenchymal stem cells (MSCs) in pulmonary fibrosis may be attributed to the strong paracrine, anti-inflammatory, anti-apoptosis and immunoregulatory effects. However, the mechanisms underlying the therapeutic effects of MSCs in IPF, especially in terms of alveolar type 2 (AT2) cells senescence, are not well understood. The purpose of this study was to evaluate the role of MSCs in NAD metabolism and senescence of AT2 cells in vitro and in vivo. Methods MSCs were isolated from human bone marrow. The protective effects of MSCs injection in pulmonary fibrosis were assessed via bleomycin mouse models. The senescence of AT2 cells co-cultured with MSCs was evaluated by SA-β-galactosidase assay, immunofluorescence staining and Western blotting. NAD+ level and NAMPT expression in AT2 cells affected by MSCs were determined in vitro and in vivo. FK866 and NAMPT shRNA vectors were used to determine the role of NAMPT in MSCs inhibiting AT2 cells senescence. Results We proved that MSCs attenuate bleomycin-induced pulmonary fibrosis in mice. Senescence of AT2 cells was alleviated in MSCs-treated pulmonary fibrosis mice and when co-cultured with MSCs in vitro. Mechanistic studies showed that NAD+ and NAMPT levels were rescued in AT2 cells co-cultured with MSCs and MSCs could suppress AT2 cells senescence mainly via suppressing lysosome-mediated NAMPT degradation. Conclusions MSCs attenuate AT2 cells senescence by upregulating NAMPT expression and NAD+ levels, thus exerting protective effects in pulmonary fibrosis.

scholarly journals Role of CXCL16 in BLM-induced epithelial–mesenchymal transition in human A549 cells

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhenzhen Ma ◽  
Chunyan Ma ◽  
Qingfeng Zhang ◽  
Yang Bai ◽  
Kun Mu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Pulmonary Fibrosis ◽  
Epithelial Mesenchymal Transition ◽  
A549 Cells ◽  
Alveolar Epithelial Cells ◽  
Alveolar Type ◽  
Mesenchymal Transition ◽  
Alveolar Epithelial ◽  
Tgf Β1

AbstractAlveolar epithelial cells play an essential role in the initiation and progression of pulmonary fibrosis, and the occurrence of epithelial–mesenchymal transition (EMT) may be the early events of pulmonary fibrosis. Recent studies have shown chemokines are involved in the complex process of EMT, and CXC chemokine ligand 16 (CXCL16) is also associated with many fibrosis-related diseases. However, whether CXCL16 is dysregulated in alveolar epithelial cells and the role of CXCL16 in modulating EMT in pulmonary fibrosis has not been reported. In this study, we found that CXCL16 and its receptor C-X-C motif chemokine receptor 6 (CXCR6) were upregulated in bleomycin induced EMT in human alveolar type II-like epithelial A549 cells. Synergistic effect of CXCL16 and bleomycin in promoting EMT occurrence, extracellular matrix (ECM) excretion, as well as the pro-inflammatory and pro-fibrotic cytokines productions in A549 cells were observed, and those biological functions were impaired by CXCL16 siRNA. We further confirmed that CXCL16 regulated EMT in A549 cells via the TGF-β1/Smad3 pathways. These results indicated that CXCL16 could promote pulmonary fibrosis by promoting the process of EMT via the TGF-β1/Smad3 signaling pathway.

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