Causal Inference of CLEC5A and ISG20 in Atherosclerosis: Integrating Mendelian Randomization and eQTL Evidence

Background: Atherosclerosis (AS) is a vascular disease driven by lipid deposition and chronic inflammation, with pathogenesis linked to genetic and immune dysregulation. This study aimed to systematically identify AS-associated genes, elucidate their molecular mechanisms, and explore therapeutic targets by integrating multi-omics analyses and experimental validation. Methods: AS-associated genes were screened through differential gene expression analysis of Gene Expression Omnibus (GEO) datasets and expression quantitative trait loci (eQTL)-based Mendelian randomization (MR) analysis to infer causal relationships. Functional insights were derived from Gene Ontology (GO) and Gene Set Enrichment Analysis (GSEA). Experimental validation included quantitative real-time PCR (qPCR), Western blotting, and immunohistochemistry in oxidized low-density lipoprotein (ox-LDL)-stimulated macrophages and apolipoprotein E-deficient (ApoE-/-) mouse models. Results: CLEC5A and ISG20 were significantly upregulated in AS patients, with MR confirming their positive causal associations with AS risk (CLEC5A: OR=1.001, P=0.047; ISG20: OR=1.001, P=0.030), while HOXA2 showed a negative association.Functional enrichment linked CLEC5A and ISG20 to immune activation, inflammatory pathways, and lipid metabolism.Experimental validation revealed marked ISG20 upregulation in ox-LDL-stimulated macrophages (P< 0.01) and aortic tissues of ApoE-/- mice, with immunohistochemistry localizing its high expression to endothelial layers and macrophage-rich regions of AS plaques. Conclusions: This study identifies ISG20 as a novel pro-atherogenic factor and potential therapeutic target, while CLEC5A and HOXA2 underscore the genetic-immune interplay in AS pathogenesis. These findings advance mechanistic insights and provide a foundation for targeted interventions.