PCSK9 genetic variants, carotid atherosclerosis and vascular remodelling

Background Circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) is a crucial regulator of cholesterol metabolism. Loss-of-function variants in PCSK9 are associated with lower levels of circulating low-density lipoprotein cholesterol (LDL-C) and reduced cardiovascular disease (CVD) risk, while gain-of-function variants correlate with elevated LDL-C concentrations and increased CVD risk. This study investigated whether genetically determined LDL-C levels, proxied by four PCSK9 genetic variants, influence common carotid artery atherosclerosis. Methods The analysis included 3040 European participants (mean age 64.2±5.4 years; 45.8% men) at high cardiovascular risk from the IMPROVE Study, alongside 49088 individuals of white British ancestry (mean age 55.2±7.6 years; 47.9% men) from the UK Biobank (UKB). Ultrasonographic measurements of common carotid intima-media thickness (CC-IMTmean, CC-IMTmax, CC-IMTmean-max) were obtained. Four lipid-level affecting genetic variants in the PCSK9 locus were selected for analysis, both individually and in a standardised Lipid-Lowering Allelic Score (LLAS), to assess their effects on LDL-C and PCSK9 levels in the IMPROVE cohort and on ultrasonographic measures in both IMPROVE and UKB. Results In the IMPROVE cohort, PCSK9 variants (rs11206510, rs2479409, rs11591147, rs11583680) exhibited expected effect directions, although not all statistically significant, on LDL-C and PCSK9 levels. The LLAS was negatively correlated with CC-IMTmean, CC-IMTmax and CC-IMTmean-max among women in IMPROVE, and among men and overall in UKB (all p<0.05). Effect sizes were comparable between cohorts. Conclusions Genetic variants in the PCSK9 locus influence LDL-C levels and CC-IMT, in keeping with proven benefits of PCSK9 inhibitors on atherosclerotic cardiovascular events.