title: A2Badenosine receptors stimulate IL-6 production in primary murine microglia through p38 MAPK kinase pathway.
abstract: The hallmark of neuroinflammation is the activation of microglia, the immunocompetent cells of the CNS, releasing a number of proinflammatory mediators implicated in the pathogenesis of neuronal diseases. Adenosine is an ubiquitous autacoid regulating several microglia functions through four receptor subtypes named A1, A2A, A2Band A3(ARs), that represent good targets to suppress inflammation occurring in CNS. Here we investigated the potential role of ARs in the modulation of IL-6 secretion and cell proliferation in primary microglial cells. The A2BAR agonist 2-[[6-Amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]-2-pyridinyl]thio]-acetamide (BAY60-6583) stimulated IL-6 increase under normoxia and hypoxia, in a dose- and time-dependent way. In cells incubated with the blockers of phospholipase C (PLC), protein kinase C epsilon (PKC-ε) and PKC delta (PKC-δ) the IL-6 increase due to A2BAR activation was strongly reduced, whilst it was not affected by the inhibitor of adenylyl cyclase (AC). Investigation of cellular signalling involved in the A2BAR effect revealed that only the inhibitor of p38 mitogen activated protein kinase (MAPK) was able to block the agonist's effect on IL-6 secretion, whilst inhibitors of pERK1/2, JNK1/2 MAPKs and Akt were not. Stimulation of p38 by BAY60-6583 was A2BAR-dependent, through a pathway affecting PLC, PKC-ε and PKC-δ but not AC, in both normoxia and hypoxia. Finally, BAY60-6583 increased microglial cell proliferation involving A2BAR, PLC, PKC-ε, PKC-δ and p38 signalling. In conclusion, A2BARs activation increased IL-6 secretion and cell proliferation in murine primary microglial cells, through PLC, PKC-ε, PKC-δ and p38 pathways, thus suggesting their involvement in microglial activation and neuroinflammation.
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Merighi
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Bencivenni
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Vincenzi
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Varani
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy.
authors.forename: Pier Andrea
authors.initials: PA
authors.lastname: Borea
authors.affiliation: Department of Medical Sciences, University of Ferrara, Ferrara 44121, Italy. Electronic address: gss@unife.it.
authors.forename: Stefania
authors.initials: S
authors.lastname: Gessi
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000631:Aminopyridines / Q000494:pharmacology; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D000860:Hypoxia / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D043704:Receptor, Adenosine A2B / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000631:Aminopyridines; C518875:BAY 60-6583; D015850:Interleukin-6; D043704:Receptor, Adenosine A2B; C577686:interleukin-6, mouse; D048051:p38 Mitogen-Activated Protein Kinases; D000241:Adenosine
keywords: Adenosine receptors; IL-6; Inflammation; Microglial cells; Proliferation; Signalling pathway