Genetically Linked Metabolites of Sepsis Severity and Mortality - Sepsis and its consequences such as organ dysfunction and failure remain significant human health problems. We have identified blood metabolites (small molecular weight compounds) including a by-product of mitochondrial fatty acid β-oxidation, acetylcarnitine (C2), that are associated with sepsis-induced organ dysfunction and mortality. Additional preliminary data suggest that blood levels of C2 during sepsis is associated with single nucleotide polymorphisms (SNPs) in the OCTN2 gene (SLC22A5; rs2631367,- 207C>G), the transporter that shuttles C2 out of cells. A SNP that is inconsequential in health, this gene and several master metabolic regulator genes may have biological relevance in disease. Furthering understanding of the associations between genetic variants and sepsis metabolite levels will bring insights to the mechanisms that enhance or attenuate sepsis severity (organ dysfunction) and mortality as well as aid in identifying drug target opportunities. Using the BioLINCC R21 mechanism we propose to conduct a preliminary metabolomics- genome-wide association study (GWAS) by leveraging DNA and plasma biospecimens from The Crystalloid Liberal Or Vasopressor Early Resuscitation in Sepsis (CLOVERS) trial. We will use the requested BioLINCC stored plasma and paired DNA specimens from 600 CLOVERS participants to generate metabolomics and GWAS data, respectively. We will test the central hypothesis that master metabolic regulator gene SNPs are associated with metabolite blood levels that contribute to sepsis-induced organ dysfunction and mortality via the following aims: Aim 1: Identify the genomic and patient level-factors that contribute to acetylcarnitine blood levels in patients with sepsis. We will test associations between 114 SNPs of metabolic regulation, fatty acid β-oxidation, and acylcarnitine transport and acetylcarnitine blood levels. Our working hypothesis is that SNPs in genes involved in the regulation of fatty acid β-oxidation and the transport of acylcarnitines contribute to the broad dynamic range of acetylcarnitine blood levels in patients with sepsis. Aim 2: Determine genetic associations of differentiating metabolites of sepsis-induced organ dysfunction. We will use our entire metabolomics data set which covers a broad range of different classes of metabolites, many of which are expected to be associated with organ function. Using the wealth of genomic data from the GWAS, we will test associations between each SNP and each differentiating metabolite. Our working hypothesis is that there are genetic variant-metabolite associations that contribute to sepsis severity. We expect to identify 1) SNPs associated with sepsis-induced increases in acetylcarnitine levels and 2) additional genetic variant-metabolite associations linked to sepsis outcomes. Collectively, this work will advance understanding of molecular mechanisms that underlie sepsis-induced amplification or attenuation of metabolic processes that contribute to sepsis. The findings will also generate testable hypotheses for planned future R01 applications that will use the entire CLOVERS cohort to generate whole genome sequencing and temporal metabolomics data.
