Integrating single-cell transcriptomics and epigenetics in a multi-omics MR framework identifies PARK7 as a causal gene in streptococcal septicemia
摘要
Streptococcal septicemia is associated with high mortality and morbidity, yet the underlying epigenetic mechanisms, particularly those involving mitochondrial genes, remain poorly understood. This study employed a multi-omics Mendelian randomization (MR) framework to investigate the causal role of mitochondrial gene regulation in streptococcal septicemia, with an emphasis on epigenetic influences.
MethodsWe utilized genetic instruments—including cis-methylation quantitative trait loci (mQTLs), cis-expression QTLs (eQTLs), and cis-protein QTLs (pQTLs)—for 1,136 mitochondrial-related genes from MitoCarta3.0. These were analyzed for causal associations with streptococcal septicaemia (FinnGen R12: 3,239 cases, 439,048 controls). Epigenetic and transcriptomic data were integrated with MR analyses of 731 immune cell traits. Single-cell RNA sequencing (GSE175453: 4 sepsis patients, 5 controls) and bulk transcriptomic data (GSE57065: 28 septic shock patients, 25 controls) were used for validation. Additionally, single-cell eQTLs for PARK7 across 14 immune cell types were applied in MR to evaluate cell-type-specific causality.
ResultsMR analyses identified 280 mQTLs, 79 eQTLs, and 29 pQTLs with causal links to streptococcal septicemia. Integrative multi-omics analysis revealed PARK7 as the only gene consistently implicated across epigenetic, transcriptomic, and proteomic levels. Epigenetic regulation via mQTLs was notably prominent. Single-cell RNA sequencing demonstrated significant PARK7 upregulation in T and NK cells from sepsis patients, corroborated by elevated PARK7 expression in septic shock patients across multiple timepoints. Temporal correlation analyses indicated that PARK7 levels inversely correlated with depleted CD8 + T cells, naive CD4 + T cells, and resting NK cells. Critically, sc-eQTL MR confirmed that genetically predicted PARK7 upregulation in two immune subsets—CD4 + KLRB1+ T cells and CD4 + KLRB1- T cells—causally increased septicemia risk.
ConclusionOur multi-omics genetic approach establishes PARK7 as a causal gene in streptococcal septicemia, mediated in part by epigenetic mechanisms. PARK7 upregulation in specific T and NK cell subsets contributes to susceptibility, linking mitochondrial epigenetic regulation to immune dysfunction and underscoring its potential as a therapeutic target.