Project description:Background: Basal cells within the human airway epithelium constitute the stem/progenitor cells for other epithelial cell types. Basal cells respond to mucosal injury and damage to the airway mucosa in an ordered sequence of spreading, migration, proliferation and phenotype shifting (differentiation) to other needed cell types. However, dynamic gene transcription in the early events of injury and repair has not been examined in these cells. Methodology and findings: Airway epithelial cells were obtained from donated lungs and grown in submersion culture on pliable membranes to obtain a pure population of basal cells. Microarrays were used to assess the transcriptome of basal cells 8 and 24 hr after mechanical injury (MI), or to cyclic stretch (CS) in a Flexcell system (0.5 Hz, 20% distension), or both treatments. We identified 121 signature genes with > 2-fold higher differential expression (DE) 8 hr after MI; expression of nearly all of these genes returned to baseline at 24 hr after injury. In cells subjected to CS, little change in DE was noted at 8 hr, whereas at 24 hr a CS signature of 1430 DE genes were identified. The MI signature was characterized by genes encoding growth factor receptors related to the EGF pathway, IL-6, IL-8 and IL-33, extracellular matrix components, and NF-kB and p38-MAPK signaling pathways, whereas the CS signature was characterized by a broad range of genes that did not identify specific signaling pathways. Combined MI and CS at 8 hr elicited DE of down-regulated genes not seen with either stimulus alone, and at 24 hr elicited DE that was similar to that seen with CS alone. Conclusion and significance: The human airway basal epithelial cell transcription signature in the first hours after MI, after CS, and after both stimuli identifies unique differentially expressed genes and pathways that may be important in the early molecular response and biology to airway injury. Total RNA obtained from primary (AEC) and differentiated (dAEC) human airway epithelial cells subjected to 8 or 24 hours in vitro mechanical or cyclic stretch or both injuries compared to sham control as well as to type of injury. Cells were collected from four donated lungs and cultured separated in submission or air liquid interface condition prior to injury for various durations.
Project description:Background. The human airway epithelium consists of 4 major cell types: ciliated, secretory, columnar and basal cells. During natural turnover and in response to injury, the airway basal cells function as stem / progenitor cells for the other airway cell types. The objective of this study is to better understand basal cell biology by defining the subset of expressed genes that characterize the signature of human airway epithelial basal cells. Methodology / Principal Findings. Microarrays were used to assess the transcriptome of basal cells purified from the airway epithelium of healthy nonsmokers obtained by bronchial brushings in comparison to the transcriptome of the complete differentiated airway epithelium. This analysis identified the “human airway basal cell signature” as 1,161 unique genes with >5-fold higher expression level in basal cells compared to the differentiated epithelium. The basal cell signature was suppressed when the basal cells differentiated into a ciliated airway epithelium in vitro. The human airway basal cell signature displayed extensive overlap with genes expressed in basal cells from other human tissues and murine airway basal cells. Consistent with self-modulation as well as signaling to other airway cell types, the airway basal cell signature was characterized by genes encoding extracellular matrix components, and growth factors and growth factor receptors, including genes related to EGFR and VEGFR signaling. However, while human airway basal cells share similarity with basal-like cells of other organs, the human airway basal cell signature has features not previously associated with this cell type, including a unique pattern of genes encoding extracellular matrix components, integrins, G protein-coupled receptors, neuroactive ligands and receptors, and ion channels. Conclusion / Significance. The human airway epithelial basal cells signature identified in the present study provides novel insights into the ontogeny, molecular phenotype and biology of the stem / progenitor cells of the human airway epithelium. This study was designed to distinguish the transcriptome of the airway epithelium basal cell from that of differentiated airway epithelium. A basal cell signature was derived and analyzed for functional significance. The signature was also evaluated as basal cells differentiated into ciliated epithelium in vitro.
Project description:Background. The human airway epithelium consists of 4 major cell types: ciliated, secretory, columnar and basal cells. During natural turnover and in response to injury, the airway basal cells function as stem / progenitor cells for the other airway cell types. The objective of this study is to better understand basal cell biology by defining the subset of expressed genes that characterize the signature of human airway epithelial basal cells. Methodology / Principal Findings. Microarrays were used to assess the transcriptome of basal cells purified from the airway epithelium of healthy nonsmokers obtained by bronchial brushings in comparison to the transcriptome of the complete differentiated airway epithelium. This analysis identified the “human airway basal cell signature” as 1,161 unique genes with >5-fold higher expression level in basal cells compared to the differentiated epithelium. The basal cell signature was suppressed when the basal cells differentiated into a ciliated airway epithelium in vitro. The human airway basal cell signature displayed extensive overlap with genes expressed in basal cells from other human tissues and murine airway basal cells. Consistent with self-modulation as well as signaling to other airway cell types, the airway basal cell signature was characterized by genes encoding extracellular matrix components, and growth factors and growth factor receptors, including genes related to EGFR and VEGFR signaling. However, while human airway basal cells share similarity with basal-like cells of other organs, the human airway basal cell signature has features not previously associated with this cell type, including a unique pattern of genes encoding extracellular matrix components, integrins, G protein-coupled receptors, neuroactive ligands and receptors, and ion channels. Conclusion / Significance. The human airway epithelial basal cells signature identified in the present study provides novel insights into the ontogeny, molecular phenotype and biology of the stem / progenitor cells of the human airway epithelium.
Project description:Background: Basal cells within the human airway epithelium constitute the stem/progenitor cells for other epithelial cell types. Basal cells respond to mucosal injury and damage to the airway mucosa in an ordered sequence of spreading, migration, proliferation and phenotype shifting (differentiation) to other needed cell types. However, dynamic gene transcription in the early events of injury and repair has not been examined in these cells. Methodology and findings: Airway epithelial cells were obtained from donated lungs and grown in submersion culture on pliable membranes to obtain a pure population of basal cells. Microarrays were used to assess the transcriptome of basal cells 8 and 24 hr after mechanical injury (MI), or to cyclic stretch (CS) in a Flexcell system (0.5 Hz, 20% distension), or both treatments. We identified 121 signature genes with > 2-fold higher differential expression (DE) 8 hr after MI; expression of nearly all of these genes returned to baseline at 24 hr after injury. In cells subjected to CS, little change in DE was noted at 8 hr, whereas at 24 hr a CS signature of 1430 DE genes were identified. The MI signature was characterized by genes encoding growth factor receptors related to the EGF pathway, IL-6, IL-8 and IL-33, extracellular matrix components, and NF-kB and p38-MAPK signaling pathways, whereas the CS signature was characterized by a broad range of genes that did not identify specific signaling pathways. Combined MI and CS at 8 hr elicited DE of down-regulated genes not seen with either stimulus alone, and at 24 hr elicited DE that was similar to that seen with CS alone. Conclusion and significance: The human airway basal epithelial cell transcription signature in the first hours after MI, after CS, and after both stimuli identifies unique differentially expressed genes and pathways that may be important in the early molecular response and biology to airway injury.
Project description:Basal airway epithelial cells (AEC) constitute stem/progenitor cells within the central airways and respond to mucosal injury in an ordered sequence of spreading, migration, proliferation, and dif-ferentiation to needed cell types. However, dynamic gene transcription in the early events after mucosal injury has not been studied in AEC. We examined gene expression using microarrays following mechanical injury (MI) in primary human AEC grown in submersion culture to generate basal cells and in the air-liquid interface to generate differentiated AEC (dAEC) that include goblet and ciliated cells. A select group of ~150 genes was in differential expression (DE) within 2 - 24 hr after MI, and enrichment analysis of these genes showed over-representation of functional categories related to inflammatory cytokines and chemokines. Network-based gene prioritization and network reconstruction using the PINTA heat kernel diffusion algorithm demonstrated highly connected networks that were richer in differentiated AEC compared to basal cells. Similar ex-periments done in basal AEC collected from asthmatic donor lungs demonstrated substantial changes in DE genes and functional categories related to inflammation compared to basal AEC from normal donors. In dAEC, similar but more modest differences were observed. We demon-strate that the AEC transcription signature after MI identifies genes and pathways that are im-portant to the initiation and perpetuation of airway mucosal inflammation. Gene expression oc-curs quickly after injury and is more profound in differentiated AEC, and is altered in AEC from asthmatic airways. Our data suggest that the early response to injury is substantially different in asthmatic airways, particularly in basal airway epithelial cells.
Project description:Human airway epithelial cells cultured in vitro at air-liquid interface (ALI) form a pseudostratified epithelium that forms tight junctions and cilia, and produces mucin, and are widely used as a model of differentiation, injury, and repair. To assess how closely the transcriptome of ALI epithelium matches that of in vivo airway epithelial cells, we used microarrays to compare the transcriptome of human large airway epithelial cells cultured at ALI with the transcriptome of large airway epithelium obtained via bronchoscopy and brushing. Gene expression profiling showed global gene expression correlated well between ALI cells and brushed cells, but there were some differences. Gene expression patterns mirrored differences in proportions of cell types (ALI have higher percentages of basal cells, brushed cells have higher percentages of ciliated cells), with ALI cells expressing higher levels of basal cell-related genes and brushed cells expressing higher levels of cilia-related genes. Pathway analysis showed ALI cells had increased expression of cell cycle and proliferation genes, while brushed cells had increased expression of cytoskeletal organization and humoral immune response genes. Overall, ALI cells are a good representation of the in vivo airway epithelial transcriptome, but for some biologic questions, the differences in the in vitro vs in vivo environments need to be considered. Affymetrix arrays were used to assess the gene expression of large airway cells cultured in vitro at air-liquid interface (12 samples) and large airway epithelial cells obtained by fiberoptic bronchoscopy of 20 healthy nonsmokers. *** Air-liquid interface Samples not provided in this Series. ***
Project description:In the process of seeking novel lung host defense regulators by analyzing genome-wide RNA sequence data from normal human airway epithelium, we detected expression of POU2AF1, a known transcription co-factor previously thought to be expressed only in lymphocytes. Lymphocyte contamination of human airway epithelial samples obtained by bronchoscopy and brushing was excluded by immunohistochemistry staining, the observation of up-regulation of POU2AF1 in purified airway basal stem/progenitor cells undergoing differentiation and analysis of differentiating single basal cell clones. Lentivirus-mediated up-regulation of POU2AF1 in airway basal cells induced up-regulation of host defense genes, including MX1, IFIT3, IFITM and known POU2AF1 downstream genes HLA-DRA, ID2, ID3, IL6, BCL6. Interestingly, expression of these genes paralleled changes of POU2AF1 expression during airway epithelium differentiation in vitro, suggesting POU2AF1 helps to maintain a "host defense tone" even in pathogen-free condition. Cigarette smoke, a known risk factor for airway infection, suppressed POU2AF1 expression both in vivo in humans and in vitro in human airway epithelial cultures, accompanied by deregulation of POU2AF1 downstream genes. Finally, enhancing POU2AF1 expression in human airway epithelium attenuated the suppression of host defense genes by smoking. Together, these findings suggest a novel function of POU2AF1 as a potential regulator of host defense genes in the human airway epithelium. Methods: Massive parallel RNA sequencing was used to compare the transcriptome of lentivirus mediated POU2AF1 or RFP (control) gene expression in human primary airway epithelial cells (3 samples per group). Uninfected basal cell was used as a further control. Conclusions: The genes up-regulated by POU2AF1 in human airway epithelial cells are mainly related to the intracellular or extracellular anti-pathogen response, suggesting POU2AF1 plays a role in airway epithelial host defense. This Series represents samples complementary to those in GSE60989.