title: From osteoarthritic synovium to synovial-derived cells characterization: synovial macrophages are key effector cells.
abstract: BACKGROUND
  The aim of the study was to characterize synovial cells from OA synovium with low-grade and moderate-grade synovitis and to define the role of synovial macrophages in cell culture.
  
  
  METHODS
  Synovial tissue explants were analyzed for the expression of typical markers of synovial fibroblasts (SF), synovial macrophages (SM) and endothelial cells. Synovial cells at passage 1 (p.1) and 5 (p.5) were analyzed for different phenotypical markers by flow cytometric analysis, inflammatory factors by multiplex immunoassay, anabolic and degradative factors by qRT-PCR. P.1 and p.5 synovial cells as different cell models were co-cultured with adipose stem cells (ASC) to define SM effects.
  
  
  RESULTS
  Synovial tissue showed a higher percentage of CD68 marker in moderate compared with low-grade synovitis. Isolated synovial cells at p.1 were positive to typical markers of SM (CD14, CD16, CD68, CD80 and CD163) and SF (CD55, CD73, CD90, CD105, CD106), whereas p.5 synovial cells were positive only to SF markers and showed a higher percentage of CD55 and CD106. At p.1 synovial cells released a significantly higher amount of all inflammatory (IL6, CXCL8, CCL2, CCL3, CCL5) and some anabolic (IL10) factors than those of p.5. Moreover, p.1 synovial cells also expressed a higher amount of some degradative factors (MMP13, S100A8, S100A9) than p.5 synovial cells. Co-culture experiments showed that the amount of SM in p.1 synovial cells differently induced or down-modulated some of the inflammatory (IL6, CXCL8, CCL2, CCL3, CCL5) and degradative factors (ADAMTS5, MMP13, S100A8, S100A9).
  
  
  CONCLUSIONS
  We found that p.1 (mix of SM and SF) and p.5 (only SF) synovial cells represent two cell models that effectively reproduce the low- or moderate-grade synovitis environment. The presence of SM in culture specifically induces the modulation of the different factors analyzed, confirming that SM are key effector cells.
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy.|SD Laboratorio RAMSES, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Manferdini
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Paolella
authors.affiliation: SD Laboratorio RAMSES, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Gabusi
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy.
authors.forename: Ylenia
authors.initials: Y
authors.lastname: Silvestri
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Gambari
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Cattini
authors.affiliation: Clinica Ortopedica e Traumatologica II, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Filardo
authors.affiliation: EFS-Pyrénéés-Méditerranéé, Toulouse, F-31300, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Fleury-Cappellesso
authors.affiliation: SC Laboratorio di Immunoreumatologia e Rigenerazione Tissutale, Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, Bologna, 40136, Italy. gina.lisignoli@ior.it.|SD Laboratorio RAMSES, Istituto Ortopedico Rizzoli, Bologna, 40136, Italy. gina.lisignoli@ior.it.
authors.forename: Gina
authors.initials: G
authors.lastname: Lisignoli
mesh_terms: D000368:Aged; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D005347:Fibroblasts / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D008264:Macrophages / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000276:immunology* / Q000473:pathology; D016133:Polymerase Chain Reaction; D013583:Synovial Membrane / Q000276:immunology* / Q000473:pathology
keywords: Degradative factors; Inflammatory factors; Osteoarthritis; Synovial fibroblasts; Synovial macrophages