title: Tempol, an intracellular antioxidant, inhibits tissue factor expression, attenuates dendritic cell function, and is partially protective in a murine model of cerebral malaria.
abstract: BACKGROUND
  The role of intracellular radical oxygen species (ROS) in pathogenesis of cerebral malaria (CM) remains incompletely understood.
  
  
  RESULTS
  We undertook testing Tempol--a superoxide dismutase (SOD) mimetic and pleiotropic intracellular antioxidant--in cells relevant to malaria pathogenesis in the context of coagulation and inflammation. Tempol was also tested in a murine model of CM induced by Plasmodium berghei Anka infection. Tempol was found to prevent transcription and functional expression of procoagulant tissue factor in endothelial cells (ECs) stimulated by lipopolysaccharide (LPS). This effect was accompanied by inhibition of IL-6, IL-8, and monocyte chemoattractant protein (MCP-1) production. Tempol also attenuated platelet aggregation and human promyelocytic leukemia HL60 cells oxidative burst. In dendritic cells, Tempol inhibited LPS-induced production of TNF-α, IL-6, and IL-12p70, downregulated expression of co-stimulatory molecules, and prevented antigen-dependent lymphocyte proliferation. Notably, Tempol (20 mg/kg) partially increased the survival of mice with CM. Mechanistically, treated mice had lowered plasma levels of MCP-1, suggesting that Tempol downmodulates EC function and vascular inflammation. Tempol also diminished blood brain barrier permeability associated with CM when started at day 4 post infection but not at day 1, suggesting that ROS production is tightly regulated. Other antioxidants-such as α-phenyl N-tertiary-butyl nitrone (PBN; a spin trap), MnTe-2-PyP and MnTBAP (Mn-phorphyrin), Mitoquinone (MitoQ) and Mitotempo (mitochondrial antioxidants), M30 (an iron chelator), and epigallocatechin gallate (EGCG; polyphenol from green tea) did not improve survival. By contrast, these compounds (except PBN) inhibited Plasmodium falciparum growth in culture with different IC50s. Knockout mice for SOD1 or phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (gp91(phox-/-)) or mice treated with inhibitors of SOD (diethyldithiocarbamate) or NADPH oxidase (diphenyleneiodonium) did not show protection or exacerbation for CM.
  
  
  CONCLUSIONS
  Results with Tempol suggest that intracellular ROS contribute, in part, to CM pathogenesis. Therapeutic targeting of intracellular ROS in CM is discussed.
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Ivo M B
authors.initials: IM
authors.lastname: Francischetti
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Emile
authors.initials: E
authors.lastname: Gordon
authors.affiliation: Laboratory of Experimental Immunology, Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Bruna
authors.initials: B
authors.lastname: Bizzarro
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Gera
authors.affiliation: Laboratory of Parasitic Diseases, NIAID/NIH, Bethesda, Maryland, United States of America.
authors.forename: Bruno B
authors.initials: BB
authors.lastname: Andrade
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Fabiano
authors.initials: F
authors.lastname: Oliveira
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Dongying
authors.initials: D
authors.lastname: Ma
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Teresa C F
authors.initials: TC
authors.lastname: Assumpção
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: José M C
authors.initials: JM
authors.lastname: Ribeiro
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Mirna
authors.initials: M
authors.lastname: Pena
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Chen-Feng
authors.initials: CF
authors.lastname: Qi
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Ababacar
authors.initials: A
authors.lastname: Diouf
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Moretz
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Carole A
authors.initials: CA
authors.lastname: Long
authors.affiliation: Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Hans C
authors.initials: HC
authors.lastname: Ackerman
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Pierce
authors.affiliation: Laboratory of Experimental Immunology, Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Anderson
authors.initials: A
authors.lastname: Sá-Nunes
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America ; University of Virginia, Department of Pathology, Charlottesville, Virginia, United States of America.
authors.forename: Michael
authors.initials: M
authors.lastname: Waisberg
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D003497:Cyclic N-Oxides / Q000494:pharmacology* / Q000627:therapeutic use; D003713:Dendritic Cells / Q000187:drug effects* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D016779:Malaria, Cerebral / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013113:Spin Labels; D013925:Thromboplastin / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D018932:Chemokine CCL2; D003497:Cyclic N-Oxides; D015850:Interleukin-6; D016209:Interleukin-8; D017382:Reactive Oxygen Species; D013113:Spin Labels; D013925:Thromboplastin; C001803:tempol