Tirzepatide reduces diet-induced senescence and NETosis-mediated liver fibrosis in mice

Lipofuscin, a protein-lipid complex that progressively accumulates in senescent cells, was commonly observed in the liver biopsies from patients with liver fibrosis or cirrhosis regardless of the etiological insults. However, whether and how lipofuscin contributes to the development of liver fibrosis remains unknown. Using a mouse model of liver fibrosis induced by choline-deficient L-amino acid-defined high-fat diet (HFD), we found that lipofuscin accumulation preceded the emergence of liver fibrosis. A significant, positive and strong correlation was observed between the hepatic lipofuscin levels and liver fibrosis severity. Neutrophils were recruited to the liver in mice fed HFD, and those that were in close proximity to lipofuscin-laden hepatocytes displayed higher susceptibility to produce neutrophil extracellular traps (NETs). We revealed that lipofuscin-laden hepatocytes generated CXCL5, which promoted NETosis. When mice defective in NETosis (Vav1-Cre Padi4fl/fl) were fed HFD, they had significantly less collagen deposition in the liver, indicating the critical role of NETs in the development of liver fibrosis associated with lipofuscin accumulation. Notably, we showed that tirzepatide, the latest glucagon-like peptide-1 receptor and glucose-dependent insulinotropic polypeptide receptor dual agonist recently approved for type 2 diabetes, attenuated NETosis-dependent liver fibrosis by preventing hepatic lipofuscin accumulation, and reduced other hepatic senescence signatures as well. In summary, our study unveiled the pathogenic, NETosis-enhancing effect of lipofuscin in liver fibrosis, and demonstrated the potential of repurposing tirzepatide for combating liver fibrosis associated with lipofuscin and for preventing organ senescence.