Hacia, J. G. | Search bioRxiv

bioRxiv2026

Clinically relevant AAV8-PEX1 gene therapy preserves retinal integrity and function long-term in a murine model of Zellweger spectrum disorder

Inherited retinal diseases (IRDs) are a heterogeneous group of genetic disorders that cause progressive vision loss. A subset of IRDs is associated with ubiquitously expressed genes involved in fundamental cellular processes, often resulting in multisystem disease. Among these is Zellweger spectrum disorder (ZSD), caused by pathogenic variants in PEX genes required for peroxisome biogenesis and function. There are no proven targeted disease-modifying treatments for ZSD, and it is unclear whether localized restoration of peroxisome function is sufficient to mitigate retinal degeneration. We previously demonstrated that HsPEX1 retinal gene augmentation therapy in a mouse model of mild ZSD homozygous for the murine equivalent (PEX1-p.[Gly844Asp]) of the most common deleterious allele in patients (PEX1-c.[2528G>A], PEX1-p.[Gly843Asp]), improved retinal electrophysiological response. Here, we present a comprehensive, dose-range evaluation of a re-designed, clinically relevant AAV8-delivered HsPEX1 subretinal gene therapy, employing expanded outcome measures. We observed a marked improvement in functional vision, retinal response, photoreceptor structure, retinal pigment epithelium integrity, subretinal inflammation, and peroxisomal metabolites, durable to the endpoint of 6 months post single subretinal injection. These studies provide preclinical proof-of-concept that localized retinal gene replacement can mitigate vision loss in peroxisome-mediated IRD.

genetics↗

bioRxiv2025

Longitudinal study of liver disease progression in the PEX1-Gly844Asp mouse model of mild Zellweger Spectrum Disorder

IntroductionZellweger spectrum disorder (ZSD) is an autosomal recessive disorder caused by mutations in any of 13 PEX genes encoding proteins required for peroxisome assembly and function. Chronic liver disease is one of the major clinical manifestations in patients and impacts quality of life and survival. However, the pathophysiology of liver disease is ZSD remains largely unknown, and current interventions are limited. To further study the liver disease mechanism, we use the PEX1-Gly844Asp (G844D) mouse model for mild ZSD, which was previously shown to develop hepatomegaly and cholestasis, similar to ZSD patients. MethodsThe natural history of hepatopathy was broadly characterized in PEX1-G844D mice and littermate controls from 1 to 18 months of age using liver histology, electron microscopy, cultured hepatocytes and blood. Metabolite and mechanism analysis included liver functions, respiratory chain dynamics, lipidomics, peroxisome metabolites, gene and protein expression assays. ResultsPEX1-G844D mice featured liver disease progression from hepatomegaly (1 month) to cluster cell death (4 months), hepatosteatosis (6 months), inflammation (8 months), fibrosis, and hepatic cancer (12 and 15 months). Hepatocyte proliferation and reduced glycogen was observed across all ages. Measurement of peroxisomal functions showed defective peroxisomal import and secondary mitochondrial defects in cultured hepatocytes. In blood and liver, plasmalogens were decreased, and C26:0 lyso-phosphatidylcholine and C27 bile acid intermediates were elevated. In liver, we observed accumulation of triglycerides and cholesterol, and reduced membrane phospholipids and sphingolipids. In contrast, in serum we observed reduced triglycerides, cholesterol and membrane lipids. Gene expression profiles confirmed by immunoblotting supported reduced hepatic de novo lipogenesis, increased hepatic lipid uptake and oxidation, PPAR activation, and modulated glucose and glycogen metabolism. Liver X receptor agonist (T0901317) applied to cultured hepatocytes enhanced hepatic lipogenesis and lipid secretion, but aggravated steatosis. ConclusionTaken together, these results suggested the following mechanisms of hepatopathy progression. We propose that global peroxisome dysfunction (1) causes PPAR activation, leading to chronic hyperplasia and partially contributing to disrupted hepatic lipid homeostasis with hepatosteatosis, and (2) underlies chronic hypoglycemia, causing hypoinsulinemia and contributing to reduced hepatic lipogenesis and systemic lipid deficiency. Growth restriction in the mouse model and in ZSD patients could be attributable to systemic lipid deficiency. Our mechanistic delineation of the pathophysiology provides other additional novel potential therapeutic targets to halt liver disease in ZSD.

pathology↗