Defining the Activated Fibroblast Population in Lung Fibrosis Using Single Cell Sequencing

In brief, we have applied a novel and unbiased approach to identify distinct and dynamic cell populations, including an in-depth analysis of the fibroblast population, in lung fibrosis. We found that while fibroblast number did not increase after injury, a population of activated fibroblasts can be identified in the fibrotic mouse lung. Using expression profiles of 1,945 lung fibroblasts we redefine the molecular characteristics of activated fibroblasts, finding that they are not a separate population but rather exhibit a similar, yet amplified, gene expression pattern to non-activated cells. Overall design: A bolus of Bleomycin (2.8 U/kilogram (kg); 1.75 milligram (mg)/kg) or 0.9% sterile saline at 2ml/kg volume was dosed into mouth of each C57BL/6 male mouse (12-13 weeks) near the larynx to induce lung fibrosis. 3 Groups: Saline Control, Bleomycin, and Bleomycin+60mg/kg Nintedanib treatment was started concomitantly with the administration of bleomycin and single cell isolations were performed on day 11.