# Genetic association between PCSK9 and coronary artery calcification mediated by inflammatory cytokines

## TL;DR

This study shows that PCSK9 inhibition may reduce coronary artery calcification, with FGF23 playing a key role in the process.

## Contribution

The study identifies PCSK9 as a therapeutic target for CAC and reveals FGF23 as a partial mediator in the PCSK9-CAC relationship.

## Key findings

- Genetic proxies for ApoB and LDL-C are positively associated with increased CAC severity.
- PCSK9 inhibition reduces calcification-related proteins and FGF23 expression in animal and cell experiments.
- FGF23 mediates 13.86% of the effect of PCSK9 on CAC.

## Abstract

Coronary artery calcification (CAC), a hallmark of coronary atherosclerosis, links closely to dysregulated lipid metabolism and chronic inflammation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors exert potent lipid-lowering and anti-inflammatory effects, holding translational potential for vascular calcification intervention. However, evidence on PCSK9 inhibition's impact on vascular calcification remains inconsistent. Here, we combined genetic causal analysis with in vivo/in vitro experiments to explore the therapeutic efficacy of PCSK9 inhibition against CAC and the mediating role of fibroblast growth factor 23 (FGF23) in this process.

First, we used two-sample Mendelian randomization (MR) and multivariable Mendelian randomization to identify lipid profiles genetically associated with coronary artery calcification. Subsequently, we investigated the value of the PCSK9 gene as a potential therapeutic target for CAC through drug target MR and colocalization analysis, and screened for potential inflammatory mediators via Mediation MR analyses. Following the completion of the aforementioned analyses, we verified the beneficial effect of PCSK9 inhibitors on delaying vascular calcification through animal experiments and cell experiments.

MR analysis revealed that genetic proxies for apolipoprotein B (ApoB) (OR=1.64; 95%CI: 1.42–1.90; p < 0.001) and low-density lipoprotein cholesterol (LDL-C) (OR=1.78; 95%CI: 1.50–2.51; p < 0.001) were positively causally associated with increased coronary artery calcification (CAC) severity. Drug target MR analysis identified PCSK9 as a promising CAC therapeutic target (OR=1.19; 95%CI: 1.11–1.27; p < 0.001), and colocalization analysis confirmed shared genetic causality between PCSK9 expression and CAC susceptibility. Mediation MR analysis suggested FGF23 as a partial mediator in the PCSK9-CAC axis (mediated effect=0.024; mediation proportion=13.86%). In animal experiments, calcification upregulated PCSK9 levels (p < 0.001), calcification-related proteins (BMP2, BMP4, RUNX2) (p < 0.001), and FGF23 expression (p < 0.05) versus controls, with all indicators reduced by evolocumab treatment (p < 0.001, p < 0.05, p < 0.05, respectively). In HASMCs, calcification elevated PCSK9 levels (p < 0.001), calcification-related proteins (p < 0.05), and FGF23 expression (p < 0.001), whereas siRNA reversed these changes (p < 0.001, p < 0.01, p < 0.05, respectively).

Inhibition of PCSK9 may effectively slow the progression of coronary artery calcification, with inflammatory mediators such as FGF23 playing key regulatory roles in this process.