title: Priming of macrophages with lipopolysaccharide potentiates P2X7-mediated cell death via a caspase-1-dependent mechanism, independently of cytokine production.
abstract: ATP stimulation of cell surface P2X7 receptors results in cytolysis and cell death of macrophages. Activation of this receptor in bacterial lipopolysaccharide (LPS)-activated macrophages or monocytes also stimulates processing and release of the cytokine interleukin-1beta(IL-1beta) through activation of caspase-1. The cytokine interleukin 18 (IL-18) is also cleaved by caspase-1 and shares pro-inflammatory characteristics with IL-1beta. The objective of the present study was to test the hypothesis that IL-1beta, IL-18, and/or caspase-1 activation contribute directly to macrophage cell death induced by LPS and ATP. Macrophages were cultured from normal mice or those in which genes for the P2X7 receptor, IL-1beta, IL-1alpha, IL-18, or caspase-1 had been deleted. Our data confirm the importance of the P2X7 receptor in ATP-stimulated cell death and IL-1beta release from LPS-primed macrophages. We demonstrate that prolonged stimulation with ATP leads to cell death, which is partly dependent on LPS priming and caspase-1, but independent of cytokine processing and release. We also provide evidence that LPS priming of macrophages makes them highly susceptible to the toxic effects of brief exposure to ATP, which leads to rapid cell death by a mechanism that is dependent on caspase-1 but, again, independent of cytokine processing and release.
authors.affiliation: School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom. Rosalind.a.Le-feuvre@man.ac.uk
authors.forename: Rosalind A
authors.initials: RA
authors.lastname: Le Feuvre
authors.forename: David
authors.initials: D
authors.lastname: Brough
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Iwakura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takeda
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Rothwell
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D020170:Caspase 1 / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004926:Escherichia coli; D005260:Female; D007375:Interleukin-1 / Q000096:biosynthesis; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008070:Lipopolysaccharides / Q000633:toxicity*; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D018345:Mice, Knockout; D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins; D018048:Receptors, Purinergic P2 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D054789:Ribosome Inactivating Proteins, Type 1
chemical_list: D007375:Interleukin-1; D008070:Lipopolysaccharides; C546469:P2rx7 protein, mouse; D010940:Plant Proteins; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D054789:Ribosome Inactivating Proteins, Type 1; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D009699:N-Glycosyl Hydrolases; C024275:pokeweed antiviral protein; D020170:Caspase 1