title: 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine inhibit TNF-α and CXCL10 production from activated primary murine microglia via A2A receptors.
abstract: BACKGROUND
  Some cells, tissues and organs release 2',3'-cAMP (a positional isomer of 3',5'-cAMP) and convert extracellular 2',3'-cAMP to 2'-AMP plus 3'-AMP and convert these AMPs to adenosine (called the extracellular 2',3'-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2',3'-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2',3'-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia.
  
  
  METHODS
  Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 μM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N(6)-cyclopentyladenosine (CCPA) (10 μM; selective A1 agonist), 5'-N-ethylcarboxamide adenosine (NECA) (10 μM; agonist for all adenosine receptor subtypes) and CGS21680 (10 μM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production.
  
  
  RESULTS
  (1) 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; (2) DPSPX nearly eliminated the inhibitory effects of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; (3) CCPA did not affect LPS-induced TNF-α and CXCL10; (4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production.
  
  
  CONCLUSIONS
  2',3'-cAMP and its metabolites (3'-AMP, 2'-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases.
authors.affiliation: Department of Critical Care Medicine, Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: elizabeth-newell@uiowa.edu.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Newell
authors.affiliation: Department of Critical Care Medicine, Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: jnnfrx0@gmail.com.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Exo
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: jdv17@pitt.edu.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Verrier
authors.affiliation: Department of Critical Care Medicine, Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: tcj10@pitt.edu.
authors.forename: Travis C
authors.initials: TC
authors.lastname: Jackson
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: dgg3@pitt.edu.
authors.forename: Delbert G
authors.initials: DG
authors.lastname: Gillespie
authors.affiliation: Department of Critical Care Medicine, Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: JaneskoKL@anes.upmc.edu.
authors.forename: Keri
authors.initials: K
authors.lastname: Janesko-Feldman
authors.affiliation: Department of Critical Care Medicine, Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: kochanekpm@ccm.upmc.edu.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Kochanek
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA. Electronic address: edj@pitt.edu.
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Jackson
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism*; D000241:Adenosine / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D054357:Chemokine CXCL10 / Q000096:biosynthesis*; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000378:metabolism*; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D000227:Adenine Nucleotides; D054357:Chemokine CXCL10; C485433:Cxcl10 protein, mouse; D043705:Receptor, Adenosine A2A; D014409:Tumor Necrosis Factor-alpha; D000249:Adenosine Monophosphate; C010565:2',3'-cyclic AMP; D000241:Adenosine
keywords: 2′,3′-cAMP; 2′-AMP; 3′-AMP; A(2A) receptors; Adenosine; Adenosine receptors; CXCL10; Primary microglia; TNF