title: Plasma Mitochondrial DNA--a Novel DAMP in Pediatric Sepsis.
abstract: Mitochondrial DNA (mtDNA) is a novel danger-associated molecular pattern that on its release into the extracellular milieu acts via toll-like receptor-9, a pattern recognition receptor of the immune system. We hypothesized that plasma mtDNA concentrations will be elevated in septic children, and these elevations are associated with an increase in the severity of illness. In a separate set of in vitro experiments, we test the hypothesis that exposing peripheral blood mononuclear cells (PBMC) to mtDNA activates the immune response and induces tumor necrosis factor (TNF) release. Children with sepsis/systemic inflammatory response syndrome or control groups were enrolled within 24  h of admission to the pediatric intensive care unit. Mitochondrial gene cytochrome c oxidase 1 (COX1) concentrations were measured by real-time quantitative PCR in the DNA extracted from plasma. PBMCs were treated with mtDNA (10  μg/mL) and supernatant TNF levels were measured. The median plasma mtDNA concentrations were significantly elevated in the septic patients as compared with the critically ill non-septic and healthy control patients [1.75E+05 (IQR 6.64E+04-3.67E+05) versus 5.73E+03 (IQR 3.90E+03-1.28E+04) and 6.64E+03 (IQR 5.22E+03-1.63E+04) copies/μL respectively]. The median concentrations of plasma mtDNA were significantly greater in patients with MOF as compared with patients without MOF (3.2E+05 (IQR 1.41E+05-1.08E+06) vs. 2.9E+04 (IQR 2.47E+04-5.43E+04) copies/μL). PBMCs treated with mtDNA demonstrated higher supernatant TNF levels as compared with control cells (6.5 ± 1.8 vs. 3.5 ± 0.5  pg/mL, P > 0.05). Our data suggest that plasma mtDNA is a novel danger-associated molecular pattern in pediatric sepsis and appears to be associated with MOF.
authors.affiliation: *Department of Critical Care Medicine, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania †University at Buffalo, State University of New York at Buffalo, Buffalo, New York ‡Department of Chemistry, Carnegie Mellon University §Departments of Critical Care Medicine and Pediatrics, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh, Pittsburgh ||Department of Pediatrics, Division of Pediatric Critical Care Medicine, Penn State Hershey Children's Hospital, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Valentina
authors.initials: V
authors.lastname: Di Caro
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Walko
authors.forename: R Aaron
authors.initials: RA
authors.lastname: Bola
authors.forename: John D
authors.initials: JD
authors.lastname: Hong
authors.forename: Diana
authors.initials: D
authors.lastname: Pang
authors.forename: Victor
authors.initials: V
authors.lastname: Hsue
authors.forename: Alicia K
authors.initials: AK
authors.lastname: Au
authors.forename: E Scott
authors.initials: ES
authors.lastname: Halstead
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Carcillo
authors.forename: Robert S B
authors.initials: RS
authors.lastname: Clark
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Aneja
mesh_terms: D000293:Adolescent; D000067531:Alarmins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D016638:Critical Illness; D004272:DNA, Mitochondrial / Q000097:blood*; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D010949:Plasma / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D018805:Sepsis / Q000097:blood* / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000067531:Alarmins; D004272:DNA, Mitochondrial; D014409:Tumor Necrosis Factor-alpha; D003576:Electron Transport Complex IV