Project description:To comprehensively study the heterogeneity within distal airway epithelium, we performed single cell transcriptomic analysis of the naive lung samples. Our analysis reveals that distal lung airway epithelial cells are highly heterogenous. We employed supervised clustering to identify a rare group of cells with transcriptional similiarities to embryonic distal lung bud tip progenitors. This approach identified a quiescent progenitor population of airway cells that accounted for all in vitro regenerative activity. Furthermore, these cells were also required for in vivo transplantation, reconstitution of alveoli, and functional recovery of injured mice. These findings indicate that small subpopulations of specialized stem/progenitors are required for effective lung regeneration and could potentially be used as therapeutic adjuncts after major lung injury.
Project description:To comprehensively study the heterogeneity within distal airway epithelium, we performed single cell transcriptomic analysis of the naive lung samples. Our analysis reveals that distal lung airway epithelial cells are highly heterogenous. We employed supervised clustering to identify a rare group of cells with transcriptional similiarities to embryonic distal lung bud tip progenitors. This approach identified a quiescent progenitor population of airway cells that accounted for all in vitro regenerative activity. Furthermore, these cells were also required for in vivo transplantation, reconstitution of alveoli, and functional recovery of injured mice. These findings indicate that small subpopulations of specialized stem/progenitors are required for effective lung regeneration and could potentially be used as therapeutic adjuncts after major lung injury.
Project description:The proximal-distal patterning program determines unique structural and functional properties of proximal and distal airways in the adult lung. Based on the knowledge that remod-eling of distal airways is the major pathologic feature of chronic obstructive pulmonary disease (COPD), and that small airway epithelium (SAE), which covers distal airways, is the primary site of the initial smoking-induced changes relevant to COPD pathogenesis, we hypothesized that in COPD smokers, the SAE transcriptome loses its region-specific biologic identity and takes on the transcriptional pattern of the proximal airways. By analyzing human airway epithelium col-lected by bronchoscopic brushings from proximal and distal airways of healthy smokers, proxi-mal and distal airway epithelial transcriptome signatures were identified. Dramatic smoking-dependent suppression of distal signature paralleled by acquisition of the proximal airway epithe-lial phenotype was found in the SAE of COPD smokers. Distal-proximal re-patterning observed in the SAE of smokers in vivo was reproduced in vitro by stimulating SAE basal cells (BC), the stem/progenitor cells of the SAE, with EGF, a growth factor up-regulated in airway epithelium by smoking. Together, this study identifies distal-proximal SAE re-patterning as a characteristic feature of small airway disordering in COPD smokers potentially driven by EGF/EGFR-mediated reprogramming of SAE BC stem/progenitor cells.
Project description:To comprehensively study the heterogeneity within distal airway epithelium, we performed single cell transcriptomic analysis of the normal human donor lung samples. Our analysis reveals that secretory (club) and basal cells in the distal lung airway epithelial cells are highly heterogenous. Further interrogation of secretory cells identified a subpopulation with potential for alveolar differentiation in vitro, implicating distal lung airway secretory cells as new candidates in alveolar repair and regeneration.
Project description:Although airway epithelia are primarily devoted to gas exchange, they have to fulfil a number of different tasks including organ maintenance and the epithelial immune response to fight airborne pathogens. These different tasks are at least partially accomplished by specialized cell types in the epithelium. In addition, a proximal to distal gradient mirroring the transition from airflow conduction to real gas exchange, is also operative. We analysed the airway system of larval Drosophila melanogaster with respect to region-specific expression in the proximal to distal axis. The larval airway system is made of epithelial cells only. Previously, it had been anticipated that these cells are very similar in their functional and transcript properties. We found differential expression between primary trunks of the airways and more distal ones comprising secondary and tertiary ones. Among these genes are especially those involved in signal transduction. A more detailed analysis was performed using DNA-microarray analyses to identify cohorts of genes that are either predominantly expressed in the primary or in the secondary/tertiary parts of the airways. Genes, including a putative mucin and the neuropeptide FMRFamide are predominantly found in primary branches, whereas the wnt- and the TGF-beta signalling pathways appear to be overrepresented in the secondary/tertiary ones. This differential expression is indicative for a proximal to distal transcriptional regionalization presumably reflecting functional differences in these parts of the flyM-bM-^@M-^Ys airway system. Trachea of wildtype L3 larvae were dissected and primary branches were processed seperately from secondary and tertiary branches. 3 biological replicates were included per group.
Project description:Down-regulation of the Notch Differentiation Pathway in the Human Airway Epithelium in Normal Smokers and Smokers with Chronic Obstructive Lung Disease; In cigarette smokers, the toxic components of smoke place the epithelium under the constant stress of a variety of mechanisms of injury, with consequent modulation of airway epithelial regeneration and disordered differentiation. Based on the underlying hypothesis that these airway epithelial changes must involve quantitative changes in genes involved with the regulation of differentiation, we assessed the expression of the Notch pathway, a signaling pathway known to play a fundamental role in the embryonic lung as a gatekeeper for differentiation, in the small airway epithelium of non-smokers, normal smokers, and smokers with COPD. Microarray analysis demonstrated that 45 of the 55 Notch pathway-related genes are expressed in the human adult small airway epithelium and TaqMan quantitative PCR confirmed the expression of key genes in the pathway. TaqMan quantitative PCR analysis of the normal small airway epithelium demonstrated that Delta-like ligand 1 is the most highly expressed Notch ligand, Notch2 and 3 the most highly expressed receptor genes, and Hes1 the predominant downstream effector gene. TaqMan PCR was used to compare gene expression in nonsmokers vs healthy smokers vs smokers with COPD. The data show that some key genes in the ligands, receptors and downstream effectors in the Notch pathway are differentially expressed in smokers, with significant downregulation of a greater number of Notch-related genes in smokers with COPD compared to healthy smokers. These observations are consistent with the hypothesis that the Notch pathway, known to play an important role in lung morphogenesis, also likely plays a role in the adult human airway epithelium, with at least some of the Notch pathway gene expression dysregulated in association with smoking and its related disorder, COPD. Experiment Overall Design: Gene expression in airway epithelial cells of normal non-smokers.