Steroids improve liver fibrosis by regulating macrophage expression in biliary atresia [Oral presentation]

Abstract

<div><p><strong>Purpose: </strong>This study aims to investigate the mechanism of steroids to improve liver fibrosis in Biliary Atresia (BA) by regulating macrophage expression using animal models and single-cell analysis.</p><p><strong>Methods: </strong>BA mice (n=24) were created by injection of Rhesus Rotavirus (RRV) virus on day 1 of life. They were randomized to receive placebo (n=12, Phosphate-buffered saline) or steroids (n=12) starting on day 21 of life. All BA mice were sacrificed on Day 21/28/34 as study time points. Liver samples were harvested for Immunohistochemical (IHC) staining, Hematoxylin-Eosin (HE) staining, Sirus Red staining to observe ductular proliferation, necrosis and fibrosis. Single cells were cultured from these liver samples and sequencing analyses were performed. Macrophage subtype biomarkers were used to test their expression through IHC staining.</p><p><strong>Results: </strong>On day 28 and 34, there were less or no ductular proliferation, necrosis and fibrosis in steroid group compared with placebo group. On day 28, M1 macrophages (pro-inflammatory) represented over 5% of total liver macrophages in the PBS group, whereas they are largely absent in the steroid group; M2 macrophages (anti-inflammatory) were largely absent in the PBS group, representing just 0.27% of total liver macrophages, whereas they represented the largest macrophage population in the steroid group, constituting 87 % of total liver macrophages. On day 34, the M1 macrophage population represented 20% of the total liver macrophages in the PBS group, whereas this was reduced to 13% of total liver macrophages in the steroid group; M2 macrophages represented only 0.7% of total liver macrophages in the PBS group, whereas the proportion of M2 macrophages was higher in the steroid group, representing 2.5% of total liver macrophages.</p><p><strong>Conclusions: </strong>A distinct pattern of macrophage expression could be observed at different time points. Steroids have the potential to reverse liver fibrosis by regulating macrophages’ expression in BA.</p></div>