GSE191208
Comparative transcriptional analysis of lung fibroblasts from young and aged mice identifies PIM1/NFATc1 axis as a driver of persistent fibrosis
Idiopathic pulmonary fibrosis (IPF) is an aging-associated disease characterized by the accumulation of myofibroblasts leading to the progressive scarring of the lung. To identify transcriptional gene programs driving persistent fibrosis in aged lungs, we performed a comparative RNA-seq analysis of fibroblasts freshly isolated from young and aged mouse lungs 30 days post-bleomycin injury. We discovered that lung fibroblasts isolated from young animals at this time point post-injury were transcriptionally similar to those isolated from uninjured mice. In contrast, aged lung fibroblasts isolated at the same time point exhibited a sustained pro-fibrotic state characterized by the elevated expression of genes implicated in inflammation, extracellular matrix remodeling, and cell survival. We identified the protein kinase pro-viral integration site of Moloney murine leukemia virus 1 (PIM1) and its direct target Nuclear Factor of Activated T Cells-1 (NFATc1) as putative drivers of the sustained profibrotic gene signatures observed in aged lung fibroblasts post-injury. PIM1 and NFATc1 transcripts were highly enriched in a pathogenic fibroblast population recently discovered in IPF lungs, and their protein expression was detected in fibroblastic foci. Overexpression of PIM1 in normal human lung fibroblasts potentiated their fibrogenic activation and this effect was dependent on NFATc1. Pharmacological inhibition of PIM1 in IPF-derived lung fibroblasts attenuated their activation and sensitized them to apoptotic stimuli. Finally, inhibition of PIM1 strongly reduced the expression of ECM remodeling and pro-survival genes and blocked the secretion of collagen in IPF lung explants ex vivo. Targeting PIM1/NFATc1 axis in pathogenic lung fibroblasts may represent a therapeutic strategy to limit their activation and promote fibrosis resolution in IPF. Overall design: Aged (18 months) Col1a1-GFP mice were given 1 dose of saline or bleomycin intratracheally. After 30 days, lungs from aged sham (n=4), aged bleo (n=5) were digested into single cell suspension and flow sorted for GFP+, CD45-, CD31-, and Epcam- cells. Cells were sorted directly into lysis buffer and used for RNA isolation and RNA sequencing.