Abstract 150: Decoding The Variant-to-function Relationship For LIPA , A Risk Locus For Cad

Abstract

Background: Genome-wide association studies (GWASs) link genetic variation in the LIPA (lysosomal acid lipase) gene to coronary artery disease (CAD). Quantitative Trait Loci (QTL) studies indicate higher LIPA mRNA and enzyme activity in the monocytes of risk alleles carriers. Yet, the mechanism whereby this locus confers disease etiology has not been fully established. Herein, we aim to establish the variant-to-function relationship and elucidate how increased LIPA impacts atherosclerosis. Methods: Employing post-GWAS pipelines (eQTL, enzyme activity-QTL, Tri-HiC, luciferase assay, allele-specific binding, motif analysis, and mobility shift assay), we connect functional variants to target genes in causal myeloid cells. Myeloid-specific Lipa overexpression mice ( Lipa Tg ) on Ldlr -/- background were generated and characterized. Results: Post-GWAS pipelines support LIPA as the candidate causal gene at this locus. In human monocyte-derived macrophages, risk allele carriers of GWAS CAD variants exhibit higher LIPA mRNA, protein, and enzyme activity. Tri-HiC and luciferase assay identified an intronic region within LIPA , housing GWAS CAD noncoding variants and exhibiting monocyte-specific enhancer activity. Within the enhancer region, 1412445 and rs1320496 were identified as the two potential causal variants, with the risk alleles having increased enhancer activity in luciferase assay and increased binding to PU.1 in mobility shift assay. Collectively, the above data suggest that the risk alleles of CAD variants lead to increased LIPA in monocytes/macrophages. Consistently, Lipa Tg , Ldlr -/- mice fed a Western diet showed significantly increased lesion size and lesion macrophage area compared to Ctl, Ldlr -/- mice. scRNA-seq analysis followed by functional validation demonstrated that Lipa Tg macrophages had higher free cholesterol yet lower neutral lipid accumulation, accompanied by a transcriptomic signature of increased interferon signaling. Lipa overexpression also increased monocyte infiltration into the plaque. Conclusions: We established that the risk alleles of common noncoding variants at the LIPA locus drive increased myeloid LIPA expression and aggravate atherosclerosis.