title: P2X7 receptor differentially couples to distinct release pathways for IL-1beta in mouse macrophage.
abstract: The proinflammatory IL-1 cytokines IL-1alpha, IL-1beta, and IL-18 are key mediators of the acute immune response to injury and infection. Mechanisms underlying their cellular release remain unclear. Activation of purinergic P2X(7) receptors (P2X(7)R) by extracellular ATP is a key physiological inducer of rapid IL-1beta release from LPS-primed macrophage. We investigated patterns of ATP-mediated release of IL-1 cytokines from three macrophage types in attempts to provide direct evidence for or against distinct release mechanisms. We used peritoneal macrophage from P2X(7)R(-/-) mice and found that release of IL-1alpha, IL-18, as well as IL-1beta, by ATP resulted exclusively from activation of P2X(7)R, release of all these IL-1 cytokines involved pannexin-1 (panx1), and that there was both a panx1-dependent and -independent component to IL-1beta release. We compared IL-1-release patterns from LPS-primed peritoneal macrophage, RAW264.7 macrophage, and J774A.1 macrophage. We found RAW264.7 macrophage readily release pro-IL-1beta independently of panx1 but do not release mature IL-1beta because they do not express apoptotic speck-like protein with a caspase-activating recruiting domain and so have no caspase-1 inflammasome activity. We delineated two distinct release pathways: the well-known caspase-1 cascade mediating release of processed IL-1beta that was selectively blocked by inhibition of caspase-1 or panx1, and a calcium-independent, caspase-1/panx1-independent release of pro-IL-1beta that was selectively blocked by glycine. None of these release responses were associated with cell damage or cytolytic effects. This provides the first direct demonstration of a distinct signaling mechanism responsible for ATP-induced release of pro-IL-1beta.
authors.affiliation: Faculty of Life Science, University of Manchester, Manchester, United Kingdom.
authors.forename: Pablo
authors.initials: P
authors.lastname: Pelegrin
authors.forename: Consuelo
authors.initials: C
authors.lastname: Barroso-Gutierrez
authors.forename: Annmarie
authors.initials: A
authors.lastname: Surprenant
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D020170:Caspase 1 / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D017630:Connexins / Q000276:immunology / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000276:immunology / Q000378:metabolism; D020382:Interleukin-18 / Q000276:immunology / Q000378:metabolism; D053582:Interleukin-1alpha / Q000276:immunology / Q000378:metabolism*; D053583:Interleukin-1beta / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000276:immunology / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7
chemical_list: D051017:Apoptosis Regulatory Proteins; D053468:CARD Signaling Adaptor Proteins; D017630:Connexins; D003598:Cytoskeletal Proteins; D020382:Interleukin-18; D053582:Interleukin-1alpha; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D009419:Nerve Tissue Proteins; C546469:P2rx7 protein, mouse; C503631:Panx1 protein, mouse; C498534:Pycard protein, mouse; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate; D020170:Caspase 1