Identifying potential macrophage polarization-related causal genes in sepsis through multi-omics mendelian randomization analysis and experimental validation

Abstract

The genetic associations between macrophage polarization-related genes (MPGs) and sepsis remain unclear. This study aimed to identify sepsis-associated MPGs. Based on blood-derived methylation quantitative trait loci (mQTL), expression QTL (eQTL), and protein QTL (pQTL) data for 731 MPGs identified from the GeneCards database, this study employed a summary-data-based Mendelian randomization (SMR) design to investigate their associations with sepsis. Genome-wide association study (GWAS) data related to sepsis from the UK Biobank served as the discovery cohort. Validation was conducted using GWAS data from six sepsis subtypes in the FinnGen database. Colocalization analysis was performed to identify shared genetic variants between traits. Targeted CpG methylation editing and functional assays were performed in THP-1-derived macrophages. SMR analyses identified 76 mQTLs, 5 eQTLs, and 1 pQTL associated with sepsis risk. Integrative mQTL and eQTL analysis revealed BMP4 and NEU1 as critical genes. Hypermethylation at BMP4 CpG sites (cg05928290 and cg05923197) was associated with increased gene expression and elevated sepsis risk. In contrast, hypomethylation at the NEU1 CpG site cg00397479 was linked to decreased NEU1 expression and increased sepsis susceptibility. These findings implicate methylation-mediated regulation of BMP4 and NEU1 in sepsis. Experimental validation showed that BMP4 CpG methylation increased gene expression and inflammatory cytokine production in macrophages. NEU1 -targeted manipulation increased NEU1 expression and reduced cytokine levels. Both interventions were associated with changes in macrophage polarization markers. Integrative multi-omics analysis identifies BMP4 and NEU1 as potential MPGs associated with sepsis. These findings suggest that DNA methylation-related regulation may contribute to sepsis and provide potential biomarkers and therapeutic targets. not applicable.