title: Neutrophil derived microparticles increase mortality and the counter-inflammatory response in a murine model of sepsis.
abstract: Although advances in medical care have significantly improved sepsis survival, sepsis remains the leading cause of death in the ICU. This is likely due to a lack of complete understanding of the pathophysiologic mechanisms that lead to dysfunctional immunity. Neutrophil derived microparticles (NDMPs) have been shown to be the predominant microparticle present at infectious and inflamed foci in human models, however their effect on the immune response to inflammation and infection is sepsis has not been fully elucidated. As NDMPs may be a potential diagnostic and therapeutic target, we sought to determine the impact NDMPs on the immune response to a murine polymicrobial sepsis. We found that peritoneal neutrophil numbers, bacterial loads, and NDMPs were increased in our abdominal sepsis model. When NDMPs were injected into septic mice, we observed increased bacterial load, decreased neutrophil recruitment, increased expression of IL-10 and worsened mortality. Furthermore, the NDMPs express phosphatidylserine and are ingested by F4/80 macrophages via a Tim-4 and MFG-E8 dependent mechanism. Finally, upon treatment, NDMPs decrease macrophage activation, increase IL-10 release and decrease macrophage numbers. Altogether, these data suggest that NDMPs enhance immune dysfunction in sepsis by blunting the function of neutrophils and macrophages, two key cell populations involved in the early immune response to infection. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States.
authors.forename: Bobby L
authors.initials: BL
authors.lastname: Johnson
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States.
authors.forename: Emily F
authors.initials: EF
authors.lastname: Midura
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States.
authors.forename: Priya S
authors.initials: PS
authors.lastname: Prakash
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States.
authors.forename: Teresa C
authors.initials: TC
authors.lastname: Rice
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States; Institute of Anatomy, University of Luebeck, Luebeck, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Kunz
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States; Institute of Anatomy, University of Luebeck, Luebeck, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Kalies
authors.affiliation: Division of Research, Department of Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, United States. Electronic address: charles.caldwell@uc.edu.
authors.forename: Charles C
authors.initials: CC
authors.lastname: Caldwell
mesh_terms: D000818:Animals; D058491:Bacterial Load; D055252:Cell-Derived Microparticles / Q000276:immunology* / Q000473:pathology / Q000637:transplantation; D004195:Disease Models, Animal; D006801:Humans; D016753:Interleukin-10 / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000276:immunology; D051379:Mice; D009504:Neutrophils / Q000276:immunology* / Q000473:pathology; D010718:Phosphatidylserines / Q000276:immunology; D018805:Sepsis / Q000276:immunology* / Q000382:microbiology / Q000473:pathology
chemical_list: C556062:IL10 protein, mouse; D008565:Membrane Proteins; D010718:Phosphatidylserines; C500399:TIM-4 protein, mouse; D016753:Interleukin-10
keywords: Bacterial load; Innate immunology; Microparticles; Sepsis