title: Azithromycin distinctively modulates classical activation of human monocytes in vitro.
abstract: OBJECTIVE
  Azithromycin has been reported to modify activation of macrophages towards the M2 phenotype. Here, we have sought to identify the mechanisms underlying this modulatory effect of azithromycin on human monocytes, classically activated in vitro.
  
  
  METHODS
  Human blood monocytes were primed with IFN-γ for 24 h and activated with LPS for 24 h. Azithromycin, anti-inflammatory and lysosome-affecting agents were added 2 h before IFN-γ. Cytokine and chemokine expression was determined by quantitative PCR and protein release by ELISA. Signalling molecules were determined by Western blotting and transcription factor activation quantified with a DNA-binding ELISA kit.
  
  
  RESULTS
  Azithromycin (1.5-50 µM) dose-dependently inhibited gene expression and/or release of M1 macrophage markers (CCR7, CXCL 11 and IL-12p70), but enhanced CCL2, without altering TNF-α or IL-6. Azithromycin also enhanced the gene expression and/or release of M2 macrophage markers (IL-10 and CCL18), and the pan-monocyte marker CD163, but inhibited that of CCL22. The Toll-like receptor (TLR) 4 signalling pathway was modulated, down-regulating NF-κB and STAT1 transcription factors. The inhibitory profile of azithromycin differed from that of dexamethasone, the phosphodiesterase-4 inhibitor roflumilast and the p38 kinase inhibitor SB203580 but was similar to that of the lysosomotropic drug chloroquine. Effects of concanamycin and NH4Cl, which also act on lysosomes, differed significantly.
  
  
  CONCLUSIONS
  Azithromycin modulated classical activation of human monocytes by inhibition of TLR4-mediated signalling and possible effects on lysosomal function, and generated a mediator expression profile that differs from that of monocyte/macrophage phenotypes so far described.
authors: GlaxoSmithKline Research Centre Zagreb Limited, Zagreb, Croatia. mila.vrancic@glpg.com
authors: M
authors: M
authors: Vrančić
authors: M
authors: M
authors: Banjanac
authors: K
authors: K
authors: Nujić
authors: M
authors: M
authors: Bosnar
authors: T
authors: T
authors: Murati
authors: V
authors: V
authors: Munić
authors: D
authors: D
authors: Stupin Polančec
authors: D
authors: D
authors: Belamarić
authors: M J
authors: MJ
authors: Parnham
authors: V
authors: V
authors: Eraković Haber
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000235:genetics / Q000378:metabolism; D017963:Azithromycin / Q000494:pharmacology*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D054422:Chemokine CCL22 / Q000235:genetics / Q000378:metabolism; D019742:Chemokines, CC / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D000098902:CD163 Antigen
chemical_list: D000893:Anti-Inflammatory Agents; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; C111792:CCL18 protein, human; C111835:CCL2 protein, human; C515482:CCL22 protein, human; D000098902:CD163 Antigen; D018932:Chemokine CCL2; D054422:Chemokine CCL22; D019742:Chemokines, CC; C508609:IL10 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011956:Receptors, Cell Surface; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D007371:Interferon-gamma; D017963:Azithromycin