title: Regulation of osteoarthritis-associated key mediators by TNFα and IL-10: effects of IL-10 overexpression in human synovial fibroblasts and a synovial cell line.
abstract: Synovial fibroblasts (SF) contribute to the pathogenesis of osteoarthritis (OA), but the effects of intra-articular cytokines on SF are not completely understood. The aim of this study was to characterize the interplay between tumor necrosis factor (TNF)α and the anti-inflammatory interleukin (IL)-10. Non-immortalized human SF and SF of the human cell line K4IM were stimulated with recombinant TNFα, IL-10, or TNFα + IL-10 (10 ng/ml each) for 24 h or transduced with an adenoviral vector overexpressing human IL-10 (hIL-10) and subsequently treated with 10 ng/ml TNFα for 24 h. Effects on the gene expression and protein synthesis of IL-6, IL-10, matrix metalloproteinases (MMP)-1, -3, type I collagen, β1-integrin, and CD44 were investigated via real-time detection polymerase chain reaction, immunofluorescence labeling, flow cytometry, and Western blotting. IL-10 release by transduced SF was confirmed with enzyme-linked immunosorbent assay. Both cell populations were activated by TNFα and by TNFα + IL-10, increasing their gene expression and protein synthesis of IL-6, IL-10, MMP-1, and MMP-3 and altering the synthesis of type I collagen, β1-integrin, and CD44. hIL-10 overexpression greatly elevated the gene expression and protein synthesis of IL-10. However, transduction did not significantly affect the gene expression of IL-6, MMP-1, and MMP-3 in SF. The increased expression of pro-inflammatory and catabolic mediators in TNFα-activated SF indicates their role in OA pathogenesis, suggesting they are a potential therapeutic target. Although the vigorousness of the responses of non-immortalized SF and K4IM clearly differ, the K4IM cell line seems to be a suitable model for non-immortalized human SF.
authors.affiliation: Department for Orthopaedic, Trauma and Reconstructive Surgery, Charité-University of Medicine, Campus Benjamin Franklin, FEM Garystrasse 5, 14195, Berlin, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Mrosewski
authors.forename: N
authors.initials: N
authors.lastname: Jork
authors.forename: K
authors.initials: K
authors.lastname: Gorte
authors.forename: C
authors.initials: C
authors.lastname: Conrad
authors.forename: E
authors.initials: E
authors.lastname: Wiegand
authors.forename: B
authors.initials: B
authors.lastname: Kohl
authors.forename: W
authors.initials: W
authors.lastname: Ertel
authors.forename: T
authors.initials: T
authors.lastname: John
authors.forename: A
authors.initials: A
authors.lastname: Oberholzer
authors.forename: C
authors.initials: C
authors.lastname: Kaps
authors.forename: G
authors.initials: G
authors.lastname: Schulze-Tanzil
mesh_terms: D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis* / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism; D010003:Osteoarthritis / Q000378:metabolism* / Q000473:pathology; D013583:Synovial Membrane / Q000378:metabolism* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D020782:Matrix Metalloproteinases