Browsing by Subject "Inflammasoma"

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    Dynamics of macrophage polarization reveal new mechanism to inhibit IL-1beta release through pyrophosphates
    (EMBO Press, 2009) Pelegrin, Pablo; Surprenant, Annmarie; Bioquímica y Biología Molecular B e Inmunología
    In acute inflammation extracellular ATP activates P2X7 ion channel receptors (P2X7R) on M1 polarized macrophages to release pro-inflammatory IL-1bvia activation of the caspase-1/Nucleotide-binding domain and Leucine-rich repeat receptor containing Pyrin domain 3 (NLRP3) inflammasome. In contrast, M2 polarized macrophages are critical to the resolution of inflammation but neither actions of P2X7R on these macrophages, nor mechanisms by which macrophages switch from pro-inflammatory to anti-inflammatory phenotypes, are known. Here we investigated extracellular ATP signaling over a dynamic macrophage polarity gradient from M1 through M2 phenotypes. In macrophages polarized towards, but not at, M2 phenotype, where intracellular IL-1b remains high and the inflammasome is intact, P2X7R activation selectively uncouples to the NLRP3-inflammasome activation but not to upstream ion channel activation. In these intermediate M1/M2 polarized macrophages, extracellular ATP now acts via its pyrophosphate chains, independently of other purine receptors, to inhibit IL-1b release by other stimuli via two independent mechanisms: inhibition of ROS production and trapping of the inflammasome complex via intracellular clustering of actin filaments.
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    Open Access
    Inflammasome-dependent IL-1β release depends upon membrane permeabilisation
    (Nature, 2016) Diamon, Catherine; Zeitler, Marcel; Gomez-Sanchez, Ana; Baroja-Mazo, Alberto; Bagnall, James; Spiller, David; White, Michael; Daniels, Michael J. D.; Mortellaro, Alessandra; Peñalver, Marcos; Paszek, Pawel; Steringer, Julia P.; Nickel, Walter; Brough, David; Martín Sánchez, María Rosario Fátima; Pelegrín Vivancos, Pablo; Bioquímica y Biología Molecular B e Inmunología
    Interleukin (IL)-1β is a critical regulator of the inflammatory response. IL-1β is not secreted through the conventional ER-Golgi route of protein secretion and to-date its mechanism of release has been unknown. Crucially its secretion depends upon the processing of a precursor form following the activation of the multi-molecular inflammasome complex. Using a novel and reversible pharmacological inhibitor of the IL-1β release process, in combination with biochemical, biophysical and real-time single-cell confocal microscopy with macrophage cells expressing Venus labelled IL-1β, we have discovered that the secretion of IL-1β after inflammasome activation requires membrane permeabilisation, and occurs in parallel with the death of the secreting cell. Thus in macrophages the release of IL-1β in response to inflammasome activation appears to be a secretory process independent of non-specific leakage of proteins during cell death. The mechanism of membrane permeabilisation leading to IL-1β release is distinct from the unconventional secretory mechanism employed by its structural homologues FGF2 or IL-1α, a process that involves the formation of membrane pores but does not result in cell death. These discoveries reveal key processes at the initiation of an inflammatory response and deliver new insights into mechanisms of protein release.