GSE137363
PERICYTE-LIKE CELLS UNDERGO TRANSCRIPTIONAL REPROGRAMMING AND DISTINCT FUNCTIONAL ADAPTATIONS IN ACUTE LUNG INJURY
Background: We previously reported on the role of pericyte-like cells as functional sentinel immune cells in lung injury. However, much about the biology of pericytes in lung injury remains unknown. Lung pericyte-like cells are well-positioned to sense disruption to the epithelial barrier and coordinate local inflammatory responses due to their anatomic niche within the alveoli. In this report, we characterized transcriptional responses and functional changes in pericyte-like cells following activation by alveolar components from injured and uninjured lungs. Methods: We purified pericyte-like cells from lung digests using PDGFR_ as a selection marker and expanded them in culture as previously described (1). We induced sterile acute lung injury in mice with recombinant human Fas ligand (rhFasL) instillation followed by mechanical ventilation (1). We then collected bronchoalveolar lavage fluid (BALF) from injured and uninjured mice. Purified pericyte-like cells in culture were exposed to growth media only (control), BALF from uninjured mice, and BALF from injured mice for 6 and 24 h. RNA collected from pericyte-like cells for each of these treatment conditions underwent genome-wide sequencing using RNA-seq. Targets of interest identified by bioinformatics analysis of RNA-seq data were validated using in vitro and in vivo assays. Results: We observed robust global transcriptional changes in pericyte-like cells following treatment with uninjured and injured BALF at 6 h, but this response persisted for 24 h only after exposure to injured BALF. Functional enrichment analysis of pericytes treated with injured BALF revealed activation of immuno-inflammatory, cell migration and angiogenesis-related pathways, whereas processes associated with tissue development and remodeling were down-regulated. We validated select targets in the inflammatory, angiogenesis-related, and cell migratory pathways using functional assays in vitro and in vivo. Conclusion: Lung pericyte-like cells are highly responsive to alveolar compartment content from both uninjured and injured lungs, but injured BALF elicits a more sustained response. The inflammatory, angiogenic, and migratory changes exhibited by activated pericyte-like cells underscore the phenotypic plasticity of these specialized stromal cells in the setting of acute lung injury. Overall design: Mouse lung pericyte-like cell mRNA profiles from culutre after exposure to injured BALF (6h, 24h; n = 6 per time point), uninjured BALF (6h, 24h; n = 6 per time point) or media only (6h, 24h; n = 6 per time point)  were generated by deep sequencing using Illumina HiSeq.