title: P2X7Deficiency Blocks Lesional Inflammasome Activity and Ameliorates Atherosclerosis in Mice.
abstract: BACKGROUND
  Extracellular adenosine triphosphate (ATP) binds as a danger signal to purinergic receptor P2X7and promotes inflammasome assembly and interleukin-1β expression. We hypothesized a functional role of the signal axis ATP-P2X7in inflammasome activation and the chronic inflammation driving atherosclerosis.
  
  
  METHODS
  P2X7-competent and P2X7-deficient macrophages were isolated and stimulated with lipopolysaccharide, ATP, or both. To assess whether P2X7may have a role in atherosclerosis, P2X7expression was analyzed in aortic arches from low density lipoprotein receptor-/-mice consuming a high-cholesterol or chow diet. P2X7+/+and P2X7-/-low density lipoprotein receptor-/-mice were fed a high-cholesterol diet to investigate the functional role of P2X7knockout in atherosclerosis. Human plaques were derived from carotid endarterectomy and stained against P2X7.
  
  
  RESULTS
  Lipopolysaccharide or ATP stimulation alone did not activate caspase 1 in isolated macrophages. However, priming with lipopolysaccharide, followed by stimulation with ATP, led to an activation of caspase 1 and interleukin-1β in P2X7-competent macrophages. In contrast, P2X7-deficient macrophages showed no activation of caspase 1 after sequential stimulation while still expressing a basal amount of interleukin-1β. P2X7receptor was higher expressed in murine atherosclerotic lesions, particularly by lesional macrophages. After 16 weeks of a high-cholesterol diet, P2X7-deficient mice showed smaller atherosclerotic lesions than P2X7-competent mice (0.162 cm2±0.023 [n=9], P2X7-/-low density lipoprotein receptor-/-: 0.084 cm2±0.01 [n=11],P=0.004) with a reduced amount of lesional macrophages. In accord with our in vitro findings, lesional caspase 1 activity was abolished in P2X7-/-mice. In addition, intravital microscopy revealed reduced leukocyte rolling and adhesion in P2X7-deficient mice. Last, we observe increased P2X7expression in human atherosclerotic lesions, suggesting that our findings in mice are relevant for human disease.
  
  
  CONCLUSIONS
  P2X7deficiency resolved plaque inflammation by inhibition of lesional inflammasome activation and reduced experimental atherosclerosis. Therefore, P2X7represents an interesting potential new target to combat atherosclerosis.
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany. peter.stachon@universitaets-herzzentrum.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Stachon
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Adrian
authors.initials: A
authors.lastname: Heidenreich
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Merz
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Hilgendorf
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Wolf
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Willecke
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Sunaina
authors.initials: S
authors.lastname: von Garlen
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Albrecht
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Carmen
authors.initials: C
authors.lastname: Härdtner
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ehrat
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Hoppe
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Reinöhl
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: von Zur Mühlen
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Bode
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Idzko
authors.affiliation: From Department of Cardiology and Angiology I, Heart Center Freiburg University, Germany (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., A.Z.); and Faculty of Medicine (P.S., A.H., J.M., I.H., D.W., F.W., S.v.G., P.A., C.H., N.H., J.R., C.v.z.M., C.B., M.I., A.Z.) and Faculty of Biology (J.M.) and Department of Pneumology (N.E., M.I.), University of Freiburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zirlik
mesh_terms: D000255:Adenosine Triphosphate / Q000633:toxicity; D000818:Animals; D050197:Atherosclerosis / Q000139:chemically induced / Q000378:metabolism* / Q000517:prevention & control*; D006801:Humans; D058847:Inflammasomes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D058486:Receptors, Purinergic P2X7 / Q000172:deficiency*
chemical_list: D058847:Inflammasomes; D008070:Lipopolysaccharides; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate
keywords: P2X7; atherosclerosis; inflammasome; inflammation; macrophages