title: Azithromycin alters macrophage phenotype.
abstract: OBJECTIVE
  To investigate the in vitro effects of azithromycin on macrophage phenotype. Utilizing a mouse macrophage cell line (J774), we examined the effect of azithromycin on the properties that define classical macrophage activation (M1) and alternative macrophage activation (M2).
  
  
  METHODS
  J774 cells were cultured in the presence of azithromycin and stimulated with classical activation [interferon-gamma (IFNgamma)] and alternative activation [interleukin (IL)-4 and IL-13] cytokines along with lipopolysaccharide (LPS). Macrophages were analysed for inflammatory cytokine production, surface receptor expression, inducible nitric oxide synthase (iNOS) protein expression and arginase activity.
  
  
  RESULTS
  Azithromycin altered the overall macrophage phenotype. Azithromycin-treated J774 macrophages demonstrated a significantly reduced production of the pro-inflammatory cytokines IL-12 and IL-6, increased production of the anti-inflammatory cytokine IL-10 and decreased the ratio of IL-12 to IL-10 by 60%. Receptor expression indicative of the M2 phenotype (mannose receptor and CD23) was increased, and receptor expression typically up-regulated in M1 cells (CCR7) was inhibited. The presence of azithromycin increased arginase (M2 effector molecule) activity 10-fold in cells stimulated with IFNgamma and LPS, and iNOS protein (M1 effector molecule) concentrations were attenuated by the drug.
  
  
  CONCLUSIONS
  These data provide evidence that azithromycin affects the inflammatory process at the level of the macrophage and shifts macrophage polarization towards the alternatively activated phenotype. This recently defined M2 phenotype has been described in conditions in which pulmonary inflammation and fibrosis are major determinants of clinical outcome, but the concept of antibiotics altering macrophage phenotype has not yet been critically evaluated.
authors.affiliation: Department of Internal Medicine, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY 40536, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Murphy
authors.forename: Vidya
authors.initials: V
authors.lastname: Sundareshan
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Cory
authors.forename: Don
authors.initials: D
authors.lastname: Hayes
authors.forename: Michael I
authors.initials: MI
authors.lastname: Anstead
authors.forename: David J
authors.initials: DJ
authors.lastname: Feola
mesh_terms: D000818:Animals; D017963:Azithromycin / Q000494:pharmacology*; D002460:Cell Line; D002461:Cell Line, Transformed; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D016130:Immunophenotyping; D008264:Macrophages / Q000145:classification / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D016207:Cytokines; D017963:Azithromycin