IPF occurs predominantly in men over the age of 60 years and in women after the onset of menopause, implying a role for sex hormones in disease development. Bleomycin mice model studies suggest that estradiol affects PF pathogenesis. However, research in human type 2 alveolar epithelial (AT2) cells, the main cell type implicated in IPF, is lacking. We hypothesize that human AT2 cells respond to estradiol, influencing AT2 cell development and response to injury and that this phenomena can be modelled using human iPSC derived AT2 cells (iAT2s).

Non-diseased iAT2 cells were treated for 6 hours with vehicle control or 10 nM of estradiol. RNA was harvested and expression of typical AT2 marker genes, sex hormone receptors, pro-inflammatory and pro-fibrotic genes were measured by RT-qPCR. After optimising of treatment time and concentration, bulk RNA sequencing was carried out to investigate iAT2 response to estradiol.

Analogous to published IHC results of primary lung tissue, RT-qPCR showed no significant expression of estrogen receptor ? (ER?). ER? was expressed in iAT2 and significantly downregulated following treatment. No significant difference was detected in the expression of AT2 markers SFTPC and ABCA3, pro-inflammatory gene IL6 or pro-fibrotic genes TGF-? or CTGF after estradiol treatment.

This is the first report of estradiol treatment of human iAT2 cells and explores the effect of this sex hormone on typical cell expression markers and disease pathways. Our preliminary data shows a down regulation of ER? without the loss of typical AT2 cell markers. Selected pro-inflammatory and fibrotic genes were not affected by treatment.