title: Inhibition of the lymphocyte metabolic switch by the oxidative burst of human neutrophils.
abstract: Activation of the phagocytic NADPH oxidase-2 (NOX-2) in neutrophils is a critical process in the innate immune system and is associated with elevated local concentrations of superoxide, hydrogen peroxide (H2O2) and hypochlorous acid. Under pathological conditions, NOX-2 activity has been implicated in the development of autoimmunity, indicating a role in modulating lymphocyte effector function. Notably, T-cell clonal expansion and subsequent cytokine production requires a metabolic switch from mitochondrial respiration to aerobic glycolysis. Previous studies demonstrate that H2O2 generated from activated neutrophils suppresses lymphocyte activation but the mechanism is unknown. We hypothesized that activated neutrophils would prevent the metabolic switch and suppress the effector functions of T-cells through a H2O2-dependent mechanism. To test this, we developed a model co-culture system using freshly isolated neutrophils and lymphocytes from healthy human donors. Extracellular flux analysis was used to assess mitochondrial and glycolytic activity and FACS analysis to assess immune function. The neutrophil oxidative burst significantly inhibited the induction of lymphocyte aerobic glycolysis, caused inhibition of oxidative phosphorylation and suppressed lymphocyte activation through a H2O2-dependent mechanism. Hydrogen peroxide and a redox cycling agent, DMNQ, were used to confirm the impact of H2O2 on lymphocyte bioenergetics. In summary, we have shown that the lymphocyte metabolic switch from mitochondrial respiration to glycolysis is prevented by the oxidative burst of neutrophils. This direct inhibition of the metabolic switch is then a likely mechanism underlying the neutrophil-dependent suppression of T-cell effector function.
authors.affiliation: Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Kramer
authors.affiliation: Department of Medicine, Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: Lynn
authors.initials: L
authors.lastname: Prichard
authors.affiliation: Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: Balu
authors.initials: B
authors.lastname: Chacko
authors.affiliation: Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: Saranya
authors.initials: S
authors.lastname: Ravi
authors.affiliation: Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Medicine, Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: E Turner
authors.initials: ET
authors.lastname: Overton
authors.affiliation: Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Medicine, Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A.
authors.forename: Sonya L
authors.initials: SL
authors.lastname: Heath
authors.affiliation: Mitochondrial Medicine Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, U.S.A. Darley@uab.edu.
authors.forename: Victor
authors.initials: V
authors.lastname: Darley-Usmar
mesh_terms: D002478:Cells, Cultured; D018920:Coculture Techniques; D006019:Glycolysis / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007113:Immunity, Innate / Q000276:immunology; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D009285:Naphthoquinones / Q000494:pharmacology; D018375:Neutrophil Activation / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D016897:Respiratory Burst / Q000502:physiology*; D013481:Superoxides / Q000378:metabolism; D013491:Suppressor Factors, Immunologic / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology
chemical_list: D009285:Naphthoquinones; D013491:Suppressor Factors, Immunologic; D013481:Superoxides; C063002:2,3-dimethoxy-1,4-naphthoquinone; D006861:Hydrogen Peroxide; D009195:Peroxidase
keywords: T-cells; glycolysis; hydrogen peroxide; oxidative phosphorylation