Spermidine suppresses the activation of hepatic stellate cells to cure liver fibrosis through autophagy activator MAP1S

Abstract Background and Aims Liver diseases present a wide range of fibrosis, from fatty liver with no inflammation to steatohepatitis with varying degrees of fibrosis, to established cirrhosis leading to HCC. In a multivariate analysis, serum levels of spermidine were chosen as the top metabolite from 237 metabolites and its levels were drastically reduced along with progression to advanced steatohepatitis. Our previous studies that showed spermidine supplementation helps mice prevent liver fibrosis through MAP1S have prompted us to explore the possibility that spermidine can alleviate or cure already developed liver fibrosis. Methods We collected tissue samples from patients with liver fibrosis to measure the levels of MAP1S. We treated wild‐type and MAP1S knockout mice with CCl 4 ‐induced liver fibrosis with spermidine and isolated HSCs in culture to test the effects of spermidine on HSC activation and liver fibrosis. Results Patients with increasing degrees of liver fibrosis had reduced levels of MAP1S. Supplementing spermidine in mice that had already developed liver fibrosis after 1 month of CCl 4 induction for an additional 3 months resulted in significant reductions in levels of ECM proteins and a remarkable improvement in liver fibrosis through MAP1S. Spermidine also suppressed HSC activation by reducing ECM proteins at both the mRNA and protein levels, and increasing the number of lipid droplets in stellate cells. Conclusions Spermidine supplementation is a potentially clinically meaningful approach to treating and curing liver fibrosis, preventing cirrhosis and HCC in patients.