Biology subjects

Di Pietro, E.

Publications and source records attributed to Di Pietro, E..

3 recordsLinked to original sources

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↗

bioRxiv2024

Geographic characterization of RPE structure and lipid changes in the PEX1-p.Gly844Asp mouse model for Zellweger spectrum disorder.

Peroxisome Biogenesis Disorders-Zellweger Spectrum (PBD-ZSD) are a heterogenous group of autosomal recessive disorders caused by defects in PEX genes whose proteins are required for peroxisome assembly and function. Peroxisomes are ubiquitous organelles that play a critical role in complex lipid metabolism. Dysfunctional peroxisomes in ZSD cause multisystem effects, with progressive retinal degeneration (RD) leading to childhood blindness being one of the most frequent clinical findings. Despite progress in understanding the role of peroxisomes in normal cellular functions, much remains unknown about how their deficiency causes RD, and there is no treatment. To study RD pathophysiology in this disease, we used the knock-in PEX1-p.GlyG844Asp (G844D) mouse model of milder ZSD, which represents the common human PEX1-p.Gly843Asp allele. We previously reported diminished retinal function, functional vision, and neural retina structural defects in this model. Beyond the neural retina, structural defects in retinal pigment epithelium (RPE) have been reported in ZSD patients and murine models with single peroxisome enzyme deficiency, suggesting that RPE degeneration may contribute to overall RD progression in this disease. Here, we investigate the RPE phenotype in our PEX1-G844D mouse model, observing morphological, inflammatory, and lipid changes at 1, 3, and 6 months of age. We report that RPE cell degeneration appears at 3 months of age and worsens with time, starts in the dorsal pole, and is accompanied by subretinal inflammatory cell infiltration. We match these events with lipid remodelling using imaging mass spectrometry which allowed regional analysis specific to the RPE cell layer. We identified 47 lipid alterations that precede structural changes, 10 of which are localized to the dorsal pole. 32 of these lipid alterations persist to 3 months, with remodelling of the lipid signature at the dorsal pole. 14 new alterations occur concurrent with histological changes. Changes in peroxisome-dependent lipids detected by liquid chromatography tandem mass spectrometry (reduced docosahexanoic acid and increased very long chain lysophosphatidylcholines) are exacerbated over time. This study represents the first characterization of RPE in any animal model of ZSD, and the first in situ lipid analysis in any peroxisome-deficient tissue. Our findings reveal candidate lipid drivers that could be targeted to alleviate RD progression in ZSD, as well as candidate biomarkers that could be used to evaluate retinopathy progression and response to therapy.

pathology↗