Abstract

Background: IL-17 signaling is implicated in the pathogenesis of alcohol-associated liver disease (AALD) leading to steatosis, fibrosis and hepatocellular carcinoma (HCC). We recently demonstrated that the specific deletion of IL-17RA in hepatocytes protects from steatosis, fibrosis and HCC in high fat diet plus ethanol (HFD+EtOH)-fed in MUP uPA mice (model that express urokinase-type plasminogen activator driven by a hepatocyte promoter for major urinary protein). As an alternative approach, the conjugation of antisense oligonucleotides to N-acetylgalactosamine (GalNAc) has been shown to efficiently target the liver via high-affinity binding to the asialoglycoprotein receptor expressed at the surface of hepatocytes. We hypothesize that the suppression of IL-17RA with GalNAc-IL-17RA siRNA therapeutical dosing in hepatocytes is sufficient to ameliorate AALD-induced steatosis, fibrosis, and HCC in mice. As a novel therapeutic approach, here we aim to treat AALD by selectively blocking IL-17RA in hepatocytes using GalNAc siRNA delivery system.

Methods: MUP uPA mice were fed with HFD+EtOH or HFD only (Pair-fed) for 18 weeks. From week 9 to week 18, the mice were weekly treated, subcutaneously, with 10mg/kg of GalNAc siRNA IL17-RA or Control. The liver function, and the extent of steatosis, fibrosis and HCC were measured after 18 weeks.

Results: The therapeutical dosing of GalNAc siRNA decreased the mRNA levels of IL-17RA by 60% in total liver, the downregulation of IL17-RA protein levels was also confirmed by western blot. Despite the number of tumors were not changed between groups, the tumors sizes were remarkably reduced (5x) in mice treated with GalNAc siIL-17RA. Interestingly, the therapeutically treatment in AALD mice also suppressed steatosis and fibrosis by 50%. In corroboration with our previous findings using an IL-17RA hepatocyte specific KO mice, we saw downregulation of target genes involved in ER stress-related and de novo lipogenesis (Caspase 2, Srepb1, Srebp2, Dhcr7, Acca, Fasn). In addition to these, the serum levels of ALT were decreased by 50% on GalNAc siIL-17RA treated mice in comparison to control, indicating an improvement of the liver function.

Conclusion: Downregulation of IL-17RA in hepatocytes using GalNAc siRNA therapeutical approach, suppressed steatosis, fibrosis and remarkably reduced HCC growth in AALD mouse model. Targeting IL-17RA therapeutically using GalNAc, delivery system may become an efficient alternative to treat AALD.