Hypoxia inducible factor 1α inhibitor PX-478 reduces atherosclerosis in mice
Background and Aims: Hypoxia-inducible factor 1α (HIF1α) plays a key role in atherosclerosis, as shown by studies in endothelial-targeted HIF1α-deficient mice. However, the potential of pharmacological inhibitors of HIF1α as treatments for atherosclerosis has not been explored. PX-478 is a selective HIF1α inhibitor that has shown efficacy in reducing cancer and obesity in animal models. In this study, we investigated whether PX-478 could be used to inhibit atherosclerosis.
Methods: We first evaluated PX-478 in human aortic endothelial cells (HAEC) and found that it significantly reduced the expression of HIF1α and its target genes, including Collagen I. We then tested PX-478 in two independent atherosclerosis models: C57BL/6 mice treated with AAV-PCSK9 and ApoE-/- mice. Both models were fed a Western diet for 3 months and treated bi-weekly with PX-478 (40 mg/kg) or saline.
Results: PX-478 treatment significantly reduced atherosclerotic plaque burden in the aortic trees in both mouse models. In the AAV-PCSK9 model, plaque burden in the aortic sinus was also reduced, but this effect was not observed in the ApoE-/- mice. Russell-Movat’s Pentachrome and Picrosirius Red staining revealed significant reductions in extracellular matrix remodeling and collagen maturation in PX-478-treated mice. Additionally, PX-478 treatment reduced diet-induced weight gain and abdominal adipocyte hypertrophy. Notably, PX-478 reduced plasma LDL cholesterol by 69% in AAV-PCSK9 mice and by 30% in ApoE-/- mice. To investigate the mechanisms underlying this cholesterol-lowering effect, we performed RNA sequencing on liver tissues from ApoE-/- mice treated with PX-478. The analysis revealed 450 upregulated genes and 381 downregulated genes, with gene ontology analysis indicating that PX-478 upregulated fatty acid and lipid catabolic pathways while downregulating lipid biosynthesis and plasma lipoprotein particle remodeling. Among the most downregulated genes were Cfd, Elovl3, and Insig2, which are involved in fat storage, fatty acid elongation, and cholesterol metabolism. The downregulation of these genes was further confirmed by qPCR in the liver tissues of PX-478-treated ApoE-/- mice.
Conclusions: These findings suggest that PX-478 could be a promising anti-atherogenic drug, targeting both the vascular endothelium and hepatic cholesterol pathways.