Prevention of Portal-Tract Fibrosis in Zfyve19 -/- Mouse Model with Adeno-Associated Virus Vector Delivering ZFYVE19 .

Zinc finger FYVE-type containing 19 (ZFYVE19) deficiency, caused by biallelic ZFYVE19 complete loss-of-function variants, is a recently identified chronic hepatobiliary disorder characterized by obvious portal-tract fibrosis, increased numbers of bile ducts with malformations, and abnormal levels of serum markers of hepatobiliary injury. As liver-targeted adeno-associated virus (AAV) gene therapy has been used successfully in hepatobiliary diseases, liver-targeted gene therapy has been explored in a mouse model of this disorder. Three ZFYVE19 AAV vectors (AAV- hZFYVE19 , AAV- hZFYVE19-m , and AAV- hZFYVE19-co ) were constructed and injected into Zfyve19-/- mice, which were treated with alpha-naphthyl isothiocyanate (ANIT), a hepatobiliary toxin. Hematoxylin/eosin (H&E), immunohistochemical (IHC) staining, immunofluorescence (IF) staining, Sirius red staining, RT-qPCR, and western blotting (WB) of liver tissue, along with serum hepatobiliary injury markers analyses, were performed to evaluate the effects of gene therapy. AAV- hZFYVE19 decreased serum hepatobiliary injury markers, portal-tract inflammation, ductal hyperplasia, and portal-tract fibrosis in Zfyve19-/- model mice most substantially at a relatively low dose (1 × 1011 vg/kg), whereas AAV- hZFYVE19 at a higher dose gradually lost the above-mentioned benefits and even caused deterioration at the highest dose of 5 × 1012 vg/kg. These observations verified the pathogenicity of ZFYVE19 deficiency and suggested that the ZFYVE19 gene needs to function well at an optimal level of expression; both too low or too high ZFYVE19 expression may be harmful.