Acute Lung Inflammation Induces Differential Gene Expression Changes in the Airway Stem Cell Niche of the Neuroepithelial Body Microenvironment

Abstract

Own and literature data point out that the neuroepithelial body (NEB) microenvironment (ME) may harbor stem cell characteristics in healthy postnatal mouse lungs1. Furthermore, the NEB ME has been suggested to be implicated in airway development and adult airway epithelial repair after severe injury. The NEB ME consists of strongly innervated groups of pulmonary neuroepithelial endocrine cells that are specifically covered by a unique population of so‐called Clara‐like cells (CLCs). The airway epithelium, including the NEB ME, reveals a very low turnover rate in the absence of injury. We recently showed that CLCs can be selectively activated following lipopolysaccharide (LPS) induced mild lung inflammation2.A GAD67‐GFP mouse model, with GFP fluorescent NEB cells, allows selective laser microdissection (LMD) of the NEB ME in cryostat sections of postnatal mouse lungs, and is compatible with high‐end PCR techniques1. RNA was isolated from LMD‐collected samples, both of the NEB ME and control airway epithelium (CAE) of untreated controls (NEB MEctrl; CAEctrl) and of LPS‐challenged mice (NEB MELPS; CAELPS). A panel of more than 600 genes from a set of stem cell‐related PCR arrays 1 was used to evaluate gene expression changes.Both up‐ and downregulation (two‐fold threshold) of the gene expression levels, between the NEB ME and CAE and between LPS‐treated and control mice, were analyzed to find out which pathways might be involved in activation of the NEB ME. In LPS‐challenged mouse lungs, 231 (38.4%) of the 601 analyzed stem cell‐related genes showed a differential expression in the NEB MELPS compared to CAELPS, of which 141 (23.4%) were upregulated and 90 (15.0%) were downregulated in the NEB MELPS. Comparably, in healthy control animals1, 218 (36.3%) genes were differentially expressed in the NEB MEctrl/CAEctrl, of which 168 (28.0%) were upregulated and 50 (8.3%) were downregulated. Importantly, multiple genes showed a differential expression in the activated NEB MELPS compared to the non‐activated NEB MEctrl; 238 (39.6%) genes showed an at least two‐fold shift in expression, 136 (22.6%) of which were upregulated and 102 (17.0%) were downregulated in the NEB MELPS. Expression data further revealed that Stem Cell, Cancer Stem Cell and the TGFβ/BMP pathway arrays harbored the highest numbers of differentially expressed genes in the NEB MELPS/NEB MEctrl, and that several genes that are involved in development‐ and regeneration‐related pathways, such as BMP, Notch and Wnt, appeared to change expression following LPS treatment.These observations support the interpretation that, in our LPS‐induced lung inflammation model, the selective proliferation of CLCs in the NEB ME results from the activation of stem cells in this niche. The observed extensive differential expression of stem cell related genes is likely involved in regulating and maintaining a balance between stem cell silencing/proliferation and commitment of daughter cells to differentiate and restore airway epithelial integrity.Support or Funding InformationUA grant GOA BOF 2015 (30729 to DA)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.