PT  - JOURNAL ARTICLE
AU  - Jason J Gokey
AU  - John Snowball
AU  - Jenna Green
AU  - Marion Waltamath
AU  - Jillian J Spinney
AU  - Katharine E Black
AU  - Lida P Hariri
AU  - Yan Xu
AU  - Anne Karina Perl
TI  - Pretreatment of aged mice with retinoic acid supports alveolar regeneration via upregulation of reciprocal PDGFA signalling
AID  - 10.1136/thoraxjnl-2020-214986
DP  - 2021 May 01
TA  - Thorax
PG  - 456--467
VI  - 76
IP  - 5
4099  - http://thorax.bmj.com/content/76/5/456.short
4100  - http://thorax.bmj.com/content/76/5/456.full
SO  - Thorax2021 May 01; 76
AB  - Objectives Idiopathic pulmonary fibrosis (IPF) primarily affects the aged population and is characterised by failure of alveolar regeneration, leading to loss of alveolar type 1 (AT1) cells. Aged mouse models of lung repair have demonstrated that regeneration fails with increased age. Mouse and rat lung repair models have shown retinoic acid (RA) treatment can restore alveolar regeneration. Herein, we seek to determine the signalling mechanisms that become activated on RA treatment prior to injury, which support alveolar differentiation.Design Partial pneumonectomy lung injury model and next-generation sequencing of sorted cell populations were used to uncover molecular targets regulating alveolar repair. In vitro organoids generated from epithelial cells of mouse or patient with IPF co-cultured with young, aged or RA-pretreated murine fibroblasts were used to test potential targets.Main outcome measurements Known alveolar epithelial cell differentiation markers, including HOPX and AGER for AT1 cells, were used to assess outcome of treatments.Results Gene expression analysis of sorted fibroblasts and epithelial cells isolated from lungs of young, aged and RA-pretreated aged mice predicted increased platelet-derived growth factor subunit A (PDGFA) signalling that coincided with regeneration and alveolar epithelial differentiation. Addition of PDGFA induced AT1 and AT2 differentiation in both mouse and human IPF lung organoids generated with aged fibroblasts, and PDGFA monoclonal antibody blocked AT1 cell differentiation in organoids generated with young murine fibroblasts.Conclusions Our data support the concept that RA indirectly induces reciprocal PDGFA signalling, which activates regenerative fibroblasts that support alveolar epithelial cell differentiation and repair, providing a potential therapeutic strategy to influence the pathogenesis of IPF.Data are available in a public, open access repository. GEO: GSE157440.