title: Immunosuppression via adenosine receptor activation by adenosine monophosphate released from apoptotic cells.
abstract: Apoptosis is coupled with recruitment of macrophages for engulfment of dead cells, and with compensatory proliferation of neighboring cells. Yet, this death process is silent, and it does not cause inflammation. The molecular mechanisms underlying anti-inflammatory nature of the apoptotic process remains poorly understood. In this study, we found that the culture supernatant of apoptotic cells activated the macrophages to express anti-inflammatory genes such as Nr4a and Thbs1. A high level of AMP accumulated in the apoptotic cell supernatant in a Pannexin1-dependent manner. A nucleotidase inhibitor and A2a adenosine receptor antagonist inhibited the apoptotic supernatant-induced gene expression, suggesting AMP was metabolized to adenosine by an ecto-5'-nucleotidase expressed on macrophages, to activate the macrophage A2a adenosine receptor. Intraperitoneal injection of zymosan into Adora2a- or Panx1-deficient mice produced high, sustained levels of inflammatory mediators in the peritoneal lavage. These results indicated that AMP from apoptotic cells suppresses inflammation as a 'calm down' signal. DOI: http://dx.doi.org/10.7554/eLife.02172.001.
authors.affiliation: Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Maruyama
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Urade
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Nagata
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D017630:Connexins / Q000378:metabolism; D015870:Gene Expression; D007108:Immune Tolerance / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000378:metabolism
chemical_list: D017630:Connexins; D009419:Nerve Tissue Proteins; C503631:Panx1 protein, mouse; D000249:Adenosine Monophosphate; D020169:Caspases
keywords: adenosine receptors; apoptosis; inflammation; macrophage