A Functional Variant of CYP4V2 Contributes to Asthma Susceptibility Through Methylation-Mediated Regulation of the Arachidonic Acid Pathway

Xiangran Chen,1 Terence Yin Weng Lam,1 Yang Yie Sio,1 Yee-How Say,1– 3 Kavita Reginald,2 Fook Tim Chew11Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore City, Singapore; 2Department of Biomedical Sciences, Sir Jeffrey Cheah Sunway Medical School, Faculty of Medical and Life Sciences, Sunway University, Petaling Jaya, SEL, Malaysia; 3Department of Biomedical Science, Faculty of Science, Universiti Tunku Abdul Rahman Kampar Campus, Kampar, PER, MalaysiaCorrespondence: Fook Tim Chew, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore City, 117543, Singapore, Tel +65 6516 1685, Fax +65 6779 2486, Email dbscft@nus.edu.sgBackground: CYP4V2 is involved in lipid metabolism, but its contribution to asthma is poorly understood. This study aimed to investigate genetic polymorphisms and regulatory features of CYP4V2 in asthma development.Methods: We performed an integrative multi-omics analysis combining transcriptomic, genetic, and epigenetic data from peripheral blood mononuclear cells (PBMCs) of individuals in the Singapore/Malaysia Cross-Sectional Genetics and Epidemiological Study (SMCSGES) cohort. The influence of CYP4V2 expression on asthma risk and expression of genes involved in arachidonic acid (AA) pathway were evaluated, followed by expression quantitative trait locus (eQTL) analysis to identify regulatory variants. DNA methylation analyses were conducted to assess epigenetic regulation of CYP4V2, and promoter reporter assays were used to functionally validate candidate regulatory CpG sites.Results: The upregulation of CYP4V2 in PBMCs was associated with an increased risk of asthma and inversely associated with PTGER2 and ALOX5AP in the AA pathway. The SNP rs2276921 was identified as the only expression quantitative trait locus (eQTL) associated with both increased CYP4V2 expression and asthma risk (FDR-adjusted p < 0.05; OR = 1.24, 95% CI = 1.10– 1.40). The minor allele G of rs2276921 was associated with low methylation at cg23232844 (p = 3.94 × 10− 3) and cg11969330 (p = 4.25 × 10− 2), located in the promoters of the protein-coding and non-coding CYP4V2 isoforms respectively. Promoter assays indicated that these two CpG sites inhibited CYP4V2 expression, supporting the regulatory effect of rs2276921 on CYP4V2 expression may be mediated through methylation.Conclusion: This study identified rs2276921 and CpG sites cg23232844 and cg11969330 that regulate CYP4V2 expression. CYP4V2 potentially modulates the AA metabolism and contributes to asthma susceptibility. These findings suggest CYP4V2 as a potential biomarker and therapeutic target in asthma.Keywords: asthma, CYP4V2, SMCSGES, eQTL, DNA methylation, PBMC