PROTAC-mediated PCSK9 degradation attenuates atherosclerosis and improves plaque composition via suppression of...

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a critical therapeutic target for managing hyperlipidemia and atherosclerosis. We developed Cadd4, a synthetic proteolysis-targeting chimera (PROTAC) engineered to selectively induce proteasomal degradation of the PCSK9 protein. In this study, we investigate Cadd4's anti-atherosclerotic properties and concurrently evaluate the feasibility and safety of its long-term therapeutic administration.

Cadd4-mediated PCSK9 degradation was assessed in mouse monocyte-macrophage leukemia cells(RAW264.7), mouse aortic vascular smooth muscle cells (MOVAS) and human umbilical vein endothelial cells (HUVECs) using immunofluorescence. Its anti-inflammatory effects were examined in lipopolysaccharide (LPS)-stimulated cells via quantitative real‑time PCR (qRT-PCR) and western blot. In vivo efficacy was assessed in apolipoprotein E-deficient (ApoE^-/-) mice maintained on a high-fat diet (HFD). Animals received intraperitoneal injections of Cadd4 (20 mg/kg every two days) or subcutaneous injections of alirocumab (3 mg/kg weekly) for 12 consecutive weeks.

Cadd4 induced dose-dependent PCSK9 degradation in all three cell types tested and significantly attenuated LPS-induced inflammatory responses. Notably, a 2-week intraperitoneal administration of Cadd4 led to a marked reduction in PCSK9 expression in both the liver and aorta of treated mice. In HFD-fed ApoE^-/- mice, 12-week administration of Cadd4 significantly decreased atherosclerotic plaque area, enhanced collagen deposition within plaques and suppressed intra-plaque inflammation. Importantly, compared with alirocumab, Cadd4 demonstrated superior efficacy in suppressing matrix metalloproteinase (MMP) expression and increasing collagen content, effects that are likely mediated via inhibition of the NF-κB/TNF-α signaling pathway. Of note, Cadd4 mediated PCSK9 modulation did not alter plasma lipid profiles in this model. Collectively, these anti-atherosclerotic effects underscore the lipid-independent anti-inflammatory activity and plaque composition-improving capacity of Cadd4.

Cadd4 potently induces PCSK9 degradation in arterial tissues, mitigates atherosclerotic progression and improves plaque composition via lipid-independent inhibition of the NF-κB/TNF-α pathway. These findings underscore the therapeutic promise of Cadd4 as a candidate for managing atherosclerotic cardiovascular disease.