Project description:Pulmonary research requires models that represent the physiology of alveolar epithelium but concerns with reproducibility, consistency and the technical and ethical challenges of using primary or stem cells has resulted in widespread use of continuous cancer or other immortalized cell lines. The A549 ‘alveolar’ cell line has been available for over four decades but there is an inconsistent view as to its suitability as an appropriate model for primary alveolar type II (ATII) cells. Since most work with A549 cells involves short term culture of proliferating cells, we postulated that culture conditions that reduced proliferation of the cancer cells would promote a more differentiated ATII cell phenotype. We examined A549 cell growth in different media over long term culture and then used microarray analysis to investigate temporal regulation of pathways involved in cell cycle and ATII differentiation; we also made comparisons with gene expression in freshly isolated human ATII cells. Analyses indicated that long term culture in Ham’s F12 resulted in substantial modulation of cell cycle genes to result in a quiescent population of cells with significant up-regulation of autophagic, differentiation and lipidogenic pathways. There were also increased numbers of up- and down-regulated genes shared with primary cells suggesting adoption of ATII characteristics and multilamellar body (MLB) development. Subsequent Oil Red-O staining and Transmission Electron Microscopy confirmed MLB expression in the differentiated A549 cells. This work defines a set of conditions for promoting ATII differentiation characteristics in A549 cells that may be advantageous for studies with this cell line.
Project description:Pulmonary research requires models that represent the physiology of alveolar epithelium but concerns with reproducibility, consistency and the technical and ethical challenges of using primary or stem cells has resulted in widespread use of continuous cancer or other immortalized cell lines. The A549 ‘alveolar’ cell line has been available for over four decades but there is an inconsistent view as to its suitability as an appropriate model for primary alveolar type II (ATII) cells. Since most work with A549 cells involves short term culture of proliferating cells, we postulated that culture conditions that reduced proliferation of the cancer cells would promote a more differentiated ATII cell phenotype. We examined A549 cell growth in different media over long term culture and then used microarray analysis to investigate temporal regulation of pathways involved in cell cycle and ATII differentiation; we also made comparisons with gene expression in freshly isolated human ATII cells. Analyses indicated that long term culture in Ham’s F12 resulted in substantial modulation of cell cycle genes to result in a quiescent population of cells with significant up-regulation of autophagic, differentiation and lipidogenic pathways. There were also increased numbers of up- and down-regulated genes shared with primary cells suggesting adoption of ATII characteristics and multilamellar body (MLB) development. Subsequent Oil Red-O staining and Transmission Electron Microscopy confirmed MLB expression in the differentiated A549 cells. This work defines a set of conditions for promoting ATII differentiation characteristics in A549 cells that may be advantageous for studies with this cell line.
Project description:Long Term Culture of the A549 Cell Line Promotes Differentiation Towards an Alveolar Type II (ATII) Phenotype Comparison of A549 cells with Primary ATII Cells
Project description:A549 epithelial cells grown under two different conditions were compared. A549s grown in rotating wall vessel cultures display a more in-vivo like phenotype. The data here describe the transcriptional differences between the two culture methods when infected with Francisella tularensis SchuS4 over a 22 hour time-course 1 colour; Cy3 labelled, 6 biological replicates for each culture condition and time-point, A549s grown in RWVs (RWV) compared to A549 grown in monolayers (mono), Infected vs. NaM-CM-/ve
Project description:A549 epithelial cells grown under two different conditions were compared. A549s grown in rotating wall vessel cultures display a more in-vivo like phenotype. The data here describe the transcriptional differences between the two culture methods when infected with Francisella tularensis SchuS4 over a 22 hour time-course
Project description:Resident stem/progenitor cells in the lung are important for tissue homeostasis and repair. However, a progenitor population for alveolar type II (ATII) cells in adult human lungs have not been identified. Here we isolated alveolar epithelial progenitor cells (AEPCs) from adult human lungs. AEPCs showed mesenchymal stem cell (MSC)-like characteristics combined with ATII cell-phenotypes. AEPCs had the capability for self-renewal and the potential to generate ATII cells in vitro. Furthermore, cells expressing similar markers were present within alveolar walls in normal lungs and these cells were significantly increased in ATII cell hyperplasias. These results suggest that adult human lungs contain a progenitor population for ATII cells.
Project description:Idiopathic pulmonary fibrosis (IPF) is the prototypic progressive fibrotic lung disease with a median survival of 2-4 years. Injury to and/or dysfunction of alveolar epithelium are strongly implicated in IPF disease initiation, but what factors determine why fibrosis progresses rather than normal tissue repair occurs remain poorly understood. We previously demonstrated that ZEB1-mediated epithelial-mesenchymal transition (EMT) in human alveolar epithelial type II (ATII) cells augments TGF-β-induced profibrogenic responses in underlying lung fibroblasts by paracrine signalling. Here we investigated bi-directional epithelial-mesenchymal crosstalk and its potential to drive fibrosis progression. RNA sequencing (RNA-seq) of lung fibroblasts exposed to conditioned media from ATII cells undergoing RAS-induced EMT identified many differentially expressed genes including those involved in cell migration and extracellular matrix (ECM) regulation. We confirmed that paracrine signalling between AS-activated ATII cells and fibroblasts augmented fibroblast recruitment and demonstrated that this involved a ZEB1-tissue plasminogen activator (tPA) axis. In a reciprocal fashion, paracrine signalling from TGF-β-activated lung fibroblasts or IPF fibroblasts induced RAS activation in ATII cells, at least partially via the secreted protein, SPARC. Together these data identify that aberrant bi-directional epithelial-mesenchymal crosstalk in IPF drives a chronic feedback loop that maintains a wound-healing phenotype and provides self-sustaining pro-fibrotic signals.
Project description:Resident stem/progenitor cells in lungs are important for tissue homeostasis and repair. We isolated human lung progenitor cells and named alveolar epithelial progenitor cells (AEPCs)(Fujino N, et al. 2011. Lab Invest. 91:363). AEPCs have phenotypes of both alveolar epithelial type II (ATII) cells and mesenchymal stem cells. AEPCs had the potential to generate ATII-like cells in vitro. ATII-like cells derived from AEPCs expressed protein and mRNA of pulmonary surfactant, and displayed lamellar bodies containing the surfactants. However, it has not been evaluated whether global gene expression of the ATII-like cells from AEPCs was similar to that of mature ATII cells isolated from human lung tissues. This study demonstrated gene expression profiles of ATII-like cells from AEPCs. In addition, transcriptomes in AEPCs and mature ATII cells were deposited in the GEO website (GSE21095 and GSE29133, respectively). We isolated AEPCs from tissue samples obtained from patients who underwent lung resection at Department of Thoracic Surgery, Tohoku University Hospital. We induced differentiation of AEPCs to ATII-like cells on extracellular matrix with medium containing KGF, cAMP and IBMX, as previously described (Fujino N, et al. 2011. Lab Invest. 91:363). We profiled the gene expression in three different batches of the ATII-like cells. We extracted total RNA from the differentiated cells. This study was approved by the Ethics Committee at Tohoku University School of Medicine. All subjects gave informed consent.
Project description:Emphysema is a major pathological phenotype of chronic obstructive pulmonary disease (COPD) that is characterized by progressive and irreversible alveolar tissue destruction caused by several stressors, such as tobacco smoke and air pollution. It remains incurable in part due to an incomplete understanding of cellular and molecular mechanisms underlying the failure of tissue repair. Here, we have generated a single cell RNA sequencing dataset of enriched epithelial cells from emphysematous parenchymal lung tissue of COPD patients and from healthy controls.Using this dataset, we performed high resolution analysis of 78,699 ATII cells and reveal novel ATII cell subsets in severe emphysema and health. These include two ATII sub-clusters expressing various secretoglobin mRNAs (SCGBpos) in COPD that present distinct transcriptomic profiles compared to healthy sub-clusters. These ATII sub-clusters that are present in human COPD are also found in a mouse emphysema model. Importantly, the COPD specific ATII cells from both species demonstrate airway origins and fail to undergo alveolar differentiation in organoid cultures, thereby suggesting that a common mechanism in emphysema pathogenesis.