Silencing hepatic PCSK9 via novel chimeric AAV8 mitigates the progression of atherosclerosis by inhibiting inflammation in ApoE

Adeno-associated virus (AAV) is the most widely utilized vector for gene therapy. Proprotein convertase subtilisin/kexin type 9 (PCSK9), predominantly expressed in the liver, plays a crucial role in lipid regulation and atherosclerosis progression. Here, we developed a novel chimeric AAV8.P-PCSK9 short hairpin RNA (shRNA) vector that incorporates a cross-species specific shRNA targeting PCSK9 to assess its effects on lipid levels and atherosclerosis in mice. AAV8.P demonstrated superior transduction efficiency and safety, achieving about 90% liver transduction and maintaining transgene expression for up to a year. The AAV8.P-PCSK9 shRNA exhibited typical liver-tropism and effectively silenced hepatic PCSK9. Moreover, it significantly lowered serum cholesterol and triglyceride levels while increasing LDL-R level without causing hepatotoxicity in wild-type mice. Additionally, it decreased PCSK9 expression and elevated low-density lipoprotein receptor expression in Apolipoprotein E-deficient mice, leading to early changes in lipid profiles but lacking a sustained impact on circulating lipids. Importantly, silencing PCSK9 resulted in reduced plaque areas with enhanced stability, decreased inflammatory macrophage infiltration, and lower levels of vascular and systemic inflammatory markers. These findings indicate that targeted silencing of hepatic PCSK9 significantly reduces lipid levels and effectively mitigates atherosclerosis progression by inhibiting inflammatory responses via the AAV8.P-PCSK9 shRNA vector, thereby providing critical support for its clinical translation.