CD47-SIRPa axis blockade in NASH promotes necroptotic hepatocyte clearance by liver macrophages and decreases hepatic fibrosis

Necroptosis contributes to hepatocyte death (HC) in non-alcoholic steatohepatitis (NASH), but the fate and roles of necroptotic hepatocytes (necHCs) in NASH remain unknown. We show here that the accumulation of necHCs is associated with worsening NASH in humans and in mice with diet-induced NASH and that NASH liver showed evidence of impaired necHC clearance by liver macrophages. Further, the "don't-eat-me" ligand CD47 on HCs and its receptor, SIRPa, on liver macrophages, were markedly upregulated in human and mouse NASH. In vitro, anti-CD47 or anti-SIRPa promoted necHC engulfment by primary liver macrophages. In a proof-of-concept mouse model of inducible HC necroptosis, anti-CD47 increased necHC uptake by liver macrophages and inhibited hepatic stellate cell (HSC) activation, which is responsible for liver fibrogenesis. Most importantly, treatment of two mouse models of diet-induced NASH with anti-CD47 or anti-SIRPa increased the uptake of necHC by liver macrophages and decreased HSC activation and liver fibrosis. These findings provide evidence that impaired clearance of necHCs by liver macrophages due to CD47-SIRPa upregulation contributes to fibrotic NASH and suggest therapeutic blockade of the CD47-SIRPa axis as a strategy to decrease the accumulation of necHCs in NASH liver and dampen the progression of hepatic fibrosis. Overall design: Male C57BL/6J mice were fed the Fructose-Palmitate-Cholesterol diet (FPC, Envigo, #TD. 160785 PWD) for 16 weeks to provoke NASH. Between weeks 8 and 16, mice received IgG or anti-CD47 (Bio-X-Cell, #BE0283, 200 µg/mouse) through intraperitoneal injection (n = 7-8 mice/group). Liver tissue were used for RNA-sequencing.