Stimulation of Liver Fibrosis by N2 Neutrophils in Wilson's Disease

Wilson's disease is an inherited hepatoneurologic disorder caused by mutations in the copper transporter ATP7B. Liver disease from Wilson's disease is one leading cause of cirrhosis in adolescents. Current copper chelators and zinc salt treatments improve hepatic presentations but frequently worsen neurologic symptoms. In this study, we showed the function and machinery of neutrophil heterogeneity using a zebrafish/murine/cellular model of Wilson's disease.

We investigated the neutrophil response in atp7b^-/- zebrafish by live imaging, movement tracking, and transcriptional analysis in sorted cells. Experiments were conducted to validate liver neutrophil heterogeneity in Atp7b^-/- mice. In vitro experiments were performed in ATP7B-knockout human hepatocellular carcinomas G2 cells and isolated bone marrow neutrophils to reveal the mechanism of neutrophil heterogeneity.

Recruitment of neutrophils into the liver is observed in atp7b^-/- zebrafish. Pharmacologic stimulation of neutrophils aggravates liver and behavior defects in atp7b^-/- zebrafish. Transcriptional analysis in sorted liver neutrophils from atp7b^-/- zebrafish reveals a distinct transcriptional profile characteristic of N2 neutrophils. Furthermore, liver N2 neutrophils also were observed in ATP7B-knockout mice, and pharmacologically targeted transforming growth factor β1, DNA methyltransferase, or signal transducer and activator of transcription 3 reduces liver N2 neutrophils and improves liver function and alleviates liver inflammation and fibrosis in ATP7B-knockout mice. Epigenetic silencing of Socs3 expression by transforming growth factor β1 contributes to N2-neutrophil polarization in isolated bone marrow neutrophils.

Our findings provide a novel prospect that pharmacologic modulation of N2-neutrophil activity should be explored as an alternative therapeutic to improve liver function in Wilson's disease.