title: CB2 receptor-mediated effects of pro-inflammatory macrophages influence survival of cardiomyocytes.
abstract: OBJECTIVE
  The endocannabinoid system and cannabinoid receptor 2 (CB2 receptor) have been associated with modulation of inflammatory response and myocardial adaptation after ischemic injury. In order to elucidate CB2 receptor-related effects during cellular interactions, we investigated cardiomyocyte survival and macrophage function in vitro.
  
  
  METHODS
  Murine embryonic (eCM) and adult (CM) cardiomyocytes, murine macrophages (MO), and their subtypes M1 (M1-MO) and M2 (M2-MO) were derived from wildtype- (WT) and CB2 receptor-deficient (Cnr2(-/-)) mice. Cells were cultured separately or in co-culture under normoxia or hypoxia (2% O2) and pro-inflammatory stimulation using interferon (IFN)γ. Besides immunohistochemistry, we also measured mRNA expression (Taqman®) and performed FACS-analysis of cardiomyocytes. Macrophage migration was assessed using Boyden chamber assay.
  
  
  RESULTS
  We found a significant induction of CB2 receptor mRNA and protein in murine eCM as well as M1- and M2-MO in vitro following cultivation under hypoxia or stimulation with IFNγ. A significantly higher amount of apoptotic Cnr2(-/-)-CMs was found after incubation under hypoxia when compared to WT-CMs. We observed a significantly stronger migration potential in Cnr2(-/-)-M1-MOs towards the supernatant of apoptotic CM, than in corresponding WT-cells. Co-culture revealed a significantly higher loss of eCMs and induction of their apoptosis after cultivation with Cnr2(-/-)-M1-MOs. Production of TNF-α in M1-MOs was dependent on CB2 receptor stimulation by anandamide.
  
  
  CONCLUSIONS
  Our data provide novel insights into CB2 receptor-mediated protection of cardiomyocytes during hypoxia and pro-inflammatory stimulation. We show CB2 receptor-dependent effects on migration and function of M1-MOs in interaction with cardiomyocytes, thereby influencing their survival.
authors.affiliation: Department of Cardiac Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Jan C
authors.initials: JC
authors.lastname: Heinemann
authors.affiliation: Department of Cardiac Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Georg D
authors.initials: GD
authors.lastname: Duerr
authors.affiliation: Department of Cardiac Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Keppel
authors.affiliation: Institute of Physiology I, Life&Brain Center, University of Bonn, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Breitbach
authors.affiliation: Institute of Physiology I, Life&Brain Center, University of Bonn, Germany.
authors.forename: Bernd K
authors.initials: BK
authors.lastname: Fleischmann
authors.affiliation: Institute of Molecular Psychiatry, Life&Brain Center, University of Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zimmer
authors.affiliation: Department of General, Visceral, Thoracic and Vascular Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Wehner
authors.affiliation: Department of Cardiac Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Welz
authors.affiliation: Department of Cardiac Surgery, University Clinical Center Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. Electronic address: o.dewald@uni-bonn.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Dewald
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D063386:Cannabinoid Receptor Agonists / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D007249:Inflammation / Q000473:pathology*; D007371:Interferon-gamma / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D018345:Mice, Knockout; D032383:Myocytes, Cardiac / Q000187:drug effects*; D061251:Primary Cell Culture; D043885:Receptor, Cannabinoid, CB2 / Q000187:drug effects* / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D063386:Cannabinoid Receptor Agonists; D043885:Receptor, Cannabinoid, CB2; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma
keywords: CB2 receptor; Cardiomyocytes; Endocannabinoids; Inflammation; Macrophages