title: Inhibition of Neutrophil Extracellular Trap Formation after Stem Cell Transplant by Prostaglandin E2.
abstract: BACKGROUND
  Autologous and allogeneic hematopoietic stem cell transplant (HSCT) patients are susceptible to pulmonary infections, including bacterial pathogens, even after hematopoietic reconstitution. We previously reported that murine bone marrow transplant (BMT) neutrophils overexpress cyclooxygenase-2, overproduce prostaglandin E2 (PGE2), and exhibit defective intracellular bacterial killing. Neutrophil extracellular traps (NETs) are DNA structures that capture and kill extracellular bacteria and other pathogens.
  
  
  OBJECTIVE
  To determine whether NETosis was defective after transplant and if so, whether this was regulated by PGE2 signaling.
  
  
  METHODS
  Neutrophils isolated from mice and humans (both control and HSCT subjects) were analyzed for NETosis in response to various stimuli in the presence or absence of PGE2 signaling modifiers.
  
  
  RESULTS
  NETs were visualized by immunofluorescence or quantified by Sytox Green fluorescence. Treatment of BMT or HSCT neutrophils with phorbol 12-myristate 13-acetate or rapamycin resulted in reduced NET formation relative to control cells. NET formation after BMT was rescued both in vitro and in vivo with cyclooxygenase inhibitors. Additionally, the EP2 receptor antagonist (PF-04418948) or the EP4 antagonist (AE3-208) restored NET formation in neutrophils isolated from BMT mice or HSCT patients. Exogenous PGE2 treatment limited NETosis of neutrophils collected from normal human volunteers and naive mice in an exchange protein activated by cAMP- and protein kinase A-dependent manner.
  
  
  CONCLUSIONS
  Our results suggest blockade of the PGE2-EP2 or EP4 signaling pathway restores NETosis after transplantation. Furthermore, these data provide the first description of a physiologic inhibitor of NETosis.
authors.affiliation: 1 Immunology Graduate Program.
authors.forename: Racquel
authors.initials: R
authors.lastname: Domingo-Gonzalez
authors.affiliation: 1 Immunology Graduate Program.
authors.forename: Giovanny J
authors.initials: GJ
authors.lastname: Martínez-Colón
authors.affiliation: 2 Summer Undergraduate Research Program.
authors.forename: Alana J
authors.initials: AJ
authors.lastname: Smith
authors.affiliation: 1 Immunology Graduate Program.|3 Systemic Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland; and.
authors.forename: Carolyne K
authors.initials: CK
authors.lastname: Smith
authors.affiliation: 4 Pulmonary, Allergy, Critical Care and Sleep Division, Department of Internal Medicine, The Ohio State University, Columbus, Ohio.
authors.forename: Megan N
authors.initials: MN
authors.lastname: Ballinger
authors.affiliation: 5 Biostatistics Department, School of Public Health.
authors.forename: Meng
authors.initials: M
authors.lastname: Xia
authors.affiliation: 5 Biostatistics Department, School of Public Health.
authors.forename: Susan
authors.identifier: http://orcid.org/0000-0003-4387-7673
authors.initials: S
authors.lastname: Murray
authors.affiliation: 3 Systemic Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland; and.
authors.forename: Mariana J
authors.initials: MJ
authors.lastname: Kaplan
authors.affiliation: 6 Department of Pediatrics, Division of Hematology-Oncology, Medical School.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Yanik
authors.affiliation: 7 Pulmonary and Critical Care Medicine Division, Department of Internal Medicine, and.|8 Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Bethany B
authors.identifier: http://orcid.org/0000-0003-3051-745X
authors.initials: BB
authors.lastname: Moore
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D015232:Dinoprostone / Q000276:immunology* / Q000494:pharmacology; D065206:Extracellular Traps / Q000187:drug effects / Q000276:immunology*; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D055815:Young Adult
chemical_list: D015232:Dinoprostone
keywords: NETosis; bacteria; granulocyte; prostaglandin; transplant