Apolipoprotein A-V gene therapy for disease prevention/treatment:a critical analysis

Apolipoprotein（apo） A-V is a novel member of the class of exchangeable apo＇s involved in triacylglycerol（TG）homeostasis.Whereas a portion of hepatic-derived apoA-V is secreted into plasma and functions to facilitate lipoprotein Iipase-mediated TG hydrolysis,another portion is recovered intracellularly,in association with cytosolic lipid droplets.Loss of apo A-V function is positively correlated with elevated plasma TG and increased risk of cardiovascular disease.Single nucleotide polymorphisms（SNP） in the APOA5 locus can affect transcription efficiency or introduce deleterious amino acid substitutions.Likewise,rare mutations in APOA5 that compromise functionality are associated with increased plasma TG and premature myocardial infarction.Genetically engineered mouse models and human population studies suggest that,in certain instances,supplementation with wild type（WT） apoA-V may have therapeutic benefit.It is hypothesized that individuals that manifest elevated plasma TG owing to deleterious APOA5 SNPs or rare mutations would respond to WT apoA-V supplementation with improved plasma TG clearance.On the other hand,subjects with hypertriglyceridemia of independent origin（unrelated to apoA-V function） may not respond to apoA-V augmentation in this manner.Improvement in the ability to identify individuals predicted to benefit,advances in gene transfer technology and the strong connection between HTG and heart disease,point to apoA-V supplementation as a viable disease prevention / therapeutic strategy.Candidates would include individuals that manifest chronic TG elevation,have low plasma apoA-V due to an APOA5 mutation/polymorphism and not have deleterious mutations/polymorphisms in other genes known to influence plasma TG levels.

Evaluation of cardiolipin nanodisks as lipid replacement therapy for Barth syndrome

Barth syndrome（BTHS） is a mitochondrial disorder characterized by cardiomyopathy and skeletal muscle weakness. Disease results from mutations in the tafazzin（TAZ） gene, encoding a phospholipid transacylase. Defective tafazzin activity results in an aberrant cardiolipin（CL） profile. The feasibility of restoring the intracellular CL profile was tested by in vivo administration of exogenous CL in nanodisk（ND） delivery particles. Ninety mg/kg CL（as ND）was administered to doxycycline-inducible taz shRNA knockdown（KD） mice once a week. After 10 weeks of CLND treatment, the mice were sacrificed and tissues harvested. Liquid chromatography-mass spectrometry of extracted lipids revealed that CL-ND administration failed to alter the CL profile of taz KD or WT mice. Thus, although CL-ND were previously shown to be an effective means of delivering CL to cultured cells, this effect does not extend to an in vivo setting. We conclude that CL-ND administration is not a suitable therapy option for BTHS.