title: Toll-like receptors 2, -3 and -4 prime microglia but not astrocytes across central nervous system regions for ATP-dependent interleukin-1β release.
abstract: Interleukin-1β (IL-1β) is a crucial mediator in the pathogenesis of inflammatory diseases at the periphery and in the central nervous system (CNS). Produced as an unprocessed and inactive pro-form which accumulates intracellularly, release of the processed cytokine is strongly promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with lipopolysaccharide (LPS), a Toll-like receptor (TLR) 4 ligand. Microglia are central to the inflammatory process and a major source of IL-1β when activated. Here we show that purified (>99%) microglia cultured from rat cortex, spinal cord and cerebellum respond robustly to ATP-dependent IL-1β release, upon priming with a number of TLR isoform ligands (zymosan and Pam3CSK4 for TLR2, poly(I:C) for TLR3). Cytokine release was prevented by a P2X7R antagonist and inhibitors of stress-activated protein kinases. Enriched astrocytes (≤ 5% microglia) from these CNS regions displayed responses qualitatively similar to microglia but became unresponsive upon eradication of residual microglia with the lysosomotropic agent Leu-Leu-OMe. Activation of multiple TLR isoforms in nervous system pathology, coupled with elevated extracellular ATP levels and subsequent P2X7R activation may represent an important route for microglia-derived IL-1β. This phenomenon may have important consequences for neuroinflammation and its position to the common pathology of CNS diseases.
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Facci
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Barbierato
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Marinelli
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Argentini
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Skaper
authors.affiliation: Department of Pharmaceutical and Pharmacological Sciences, University of Padua, 35131 Padua, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Giusti
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism*; D008024:Ligands; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D011804:Quinolines / Q000494:pharmacology; D051381:Rats; D015398:Signal Transduction; D013116:Spinal Cord / Q000378:metabolism; D013312:Stress, Physiological; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000378:metabolism*; D051196:Toll-Like Receptor 3 / Q000819:agonists / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000378:metabolism*
chemical_list: C515928:(N-(1-(((cyanoimino)(5-quinolinylamino) methyl) amino)-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide); D000081:Acetamides; D053583:Interleukin-1beta; D008024:Ligands; D011804:Quinolines; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D000255:Adenosine Triphosphate