Estrogen Receptor Status and Effect of Estrogen on Alpha-1-Antitrypsin Expression in Non-CF Cell Lines

The cystic fibrosis (CF) lung is characterised by chronic neutrophilic inflammation. Neutrophil elastase (NE) is a serine protease that is released from neutrophils and is present at excessive levels in the CF lung. This overwhelms the neutralising abilities of antiproteases, particularly α-1-antitrypsin (A1AT), which predisposes the CF airways to NE-mediated destruction. A CF gender gap has been described, with females experiencing a more aggressive lung disease and having a lower median age of survival than males. The main female sex hormone, estrogen, has been implicated in these gender differences, however, the full range of estrogen’s effects in female CF lung inflammation remain to be determined. microRNAs are negative regulators of gene expression that are implicated in the development and progression of disease. This project assessed a novel potential aspect of the CF gender gap by investigating the effect of 17β-estradiol (E2) on A1AT expression in a hepatocytic cell line and measuring estrogen receptor (ER) expression in selected hepatocytic and monocytic cell lines. An in silico analysis of miRNAs predicted to target A1AT was also conducted. E2 significantly reduced A1AT production in HepG2 cells. Both male (HepG2) and female (HepaRG) hepatocytes expressed greater quantities of ERα mRNA versus ERβ. However, ERα and ERβ expression at protein level was similar between the male and female hepatocytes. All monocytes tested (THP-1, U937 and HL-60) expressed greater quantities of ERβ mRNA versus ERα. Female monocytes (HL-60) expressed the highest quantities of ERα and ERβ protein. The miRNAs: hsa-miR-24-3p, hsa-miR-190b and hsa-miR-625-5p are predicted to target the A1AT 3’ untranslated region and are E2-sensitive. These results not only provide insight into another molecular aspect of the CF gender gap, but may also aid the development of novel miRNA-targeted therapies that drive A1AT expression and could be used to control inflammation levels in CF.