title: Among human macrophages polarised to different phenotypes, the M-CSF-oriented cells present the highest pro-inflammatory response to the rheumatoid arthritis-specific immune complexes containing ACPA.
abstract: OBJECTIVE
  In the inflamed synovium of patients with rheumatoid arthritis (RA), autoantibodies to citrullinated proteins (ACPA) probably form immune complexes (IC) on deposits of citrullinated fibrin. We showed that in vitro such ACPA-IC activate a pro-inflammatory cytokine response in M-CSF-differentiated macrophages. Our objective was to evaluate how macrophage polarisation influences this response.
  
  
  METHODS
  CD14-positive monocytes from healthy donors were cultured in the presence of M-CSF, IFN-γ, interleukin (IL)-4 or IL-10. Expression of markers specific for polarised macrophages was analysed by flow cytometry. Their cytokine secretion was prompted by in vitro generated autoantibodies to citrullinated proteins immune complexes (ACPA-IC) and assayed in the culture supernatants.
  
  
  RESULTS
  IFN-γ-polarised cells exhibited high levels of CD64 and CD80. Low expression of CD14 and high expression of CD206 characterised the IL-4-polarised cells. Exposure to IL-10 or M-CSF raised the expression of CD14, CD32 and CD163. The two cell types lacked CD80 and exhibited similar expression of CD64, CD200R and CD206. In response to ACPA-IC, the secretion of IL-1β, IL-6 and IL-8 was similar among cells exposed to IFN-γ, IL-4 or IL-10. However, the later cells were associated with the highest IL-1Ra:IL-1β ratio and the lowest tumour necrosis factor (TNF)-α:IL-10 ratio. Conversely, M-CSF-exposed cells secreted the highest levels of pro-inflammatory cytokines, exhibited a high TNF-α:IL-10 ratio and the lowest IL-1Ra:IL-1β ratio.
  
  
  CONCLUSIONS
  Despite their phenotypic similarity, IL-10-polarised and M-CSF-polarised macrophages clearly differ in their cytokine response to ACPA-IC. M-CSF-polarised cells exhibit the highest pro-inflammatory potential. Since M-CSF is abundant in the RA synovium, therein it probably drives macrophages towards a strong pro-inflammatory cytokine response to the locally formed ACPA-IC.
authors.affiliation: INSERM Unité 1056, Toulouse, France.|CNRS Unité Mixte de Recherche 5165, Toulouse, France.|Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Université de Toulouse, Université Paul Sabatier, Toulouse, France.|Laboratory of Cell Biology and Cytology, Centre Hospitalier Universitaire (CHU) de Toulouse, Institut Fédératif de Biologie, Toulouse, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Clavel
authors.affiliation: INSERM Unité 1056, Toulouse, France.|CNRS Unité Mixte de Recherche 5165, Toulouse, France.|Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Université de Toulouse, Université Paul Sabatier, Toulouse, France.
authors.forename: Laurie
authors.initials: L
authors.lastname: Ceccato
authors.affiliation: INSERM Unité 1056, Toulouse, France.|CNRS Unité Mixte de Recherche 5165, Toulouse, France.|Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Université de Toulouse, Université Paul Sabatier, Toulouse, France.
authors.forename: Florence
authors.initials: F
authors.lastname: Anquetil
authors.affiliation: INSERM Unité 1056, Toulouse, France.|CNRS Unité Mixte de Recherche 5165, Toulouse, France.|Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Université de Toulouse, Université Paul Sabatier, Toulouse, France.|Laboratory of Cell Biology and Cytology, Centre Hospitalier Universitaire (CHU) de Toulouse, Institut Fédératif de Biologie, Toulouse, France.
authors.forename: Guy
authors.initials: G
authors.lastname: Serre
authors.affiliation: INSERM Unité 1056, Toulouse, France.|CNRS Unité Mixte de Recherche 5165, Toulouse, France.|Laboratory of Epidermis Differentiation and Rheumatoid Autoimmunity, Université de Toulouse, Université Paul Sabatier, Toulouse, France.
authors.forename: Mireille
authors.initials: M
authors.lastname: Sebbag
mesh_terms: D000936:Antigen-Antibody Complex / Q000378:metabolism*; D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001323:Autoantibodies / Q000378:metabolism*; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D064368:Healthy Volunteers; D006801:Humans; D018950:Lipopolysaccharide Receptors; D016173:Macrophage Colony-Stimulating Factor / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*; D010456:Peptides, Cyclic / Q000276:immunology
chemical_list: D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D016207:Cytokines; D018950:Lipopolysaccharide Receptors; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D016173:Macrophage Colony-Stimulating Factor
keywords: Ant-CCP; Cytokines; Rheumatoid Arthritis; Synovitis; TNF-alpha