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We examined the hypothesis that stromal fibroblasts modulate the ability of endothelial cells (EC) to recruit lymphocytes in a site-specific manner. PBL were perfused over HUVEC that had been cultured with fibroblasts isolated from the inflamed synovium or the skin of patients with rheumatoid arthritis or osteoarthritis, or from normal synovium, with or without exposure to the inflammatory cytokines TNF-alpha+IFN-gamma. Fibroblasts from inflamed synovium, but no others, caused unstimulated HUVEC to bind flowing lymphocytes. This adhesion was supported by alpha(4)beta(1)-VCAM-1 interaction and stabilised by activation of PBL through CXCR4-CXCL12. Antibody neutralisation of IL-6 during co-culture effectively abolished the ability of EC to bind lymphocytes. Cytokine-stimulated EC supported high levels of lymphocyte adhesion, through the presentation of VCAM-1, E-selectin and chemokine(s) acting through CXCR3. Interestingly, co-culture with dermal fibroblasts caused a marked reduction in cytokine-induced adhesion, while synovial fibroblasts had variable effects depending on their source. In the dermal co-cultures, neutralisation of IL-6 or TGF-beta caused partial recovery of cytokine-induced lymphocyte adhesion; this was complete when both were neutralised. Exogenous IL-6 was also found to inhibit response to TNF-alpha+IFN-gamma. Normal stromal fibroblasts appear to regulate the cytokine-sensitivity of vascular endothelium, while fibroblasts associated with chronic inflammation bypass this and develop a directly inflammatory phenotype. Actions of IL-6 might be pro-inflammatory or anti-inflammatory, depending on the local milieu.

Original publication

DOI

10.1002/eji.200838232

Type

Journal article

Journal

Eur J Immunol

Publication Date

01/2009

Volume

39

Pages

113 - 125

Keywords

Antiviral Agents, Cell Adhesion, Cell Movement, Cells, Cultured, Chemokine CXCL12, Coculture Techniques, E-Selectin, Endothelial Cells, Fibroblasts, Humans, Inflammation, Interferon-gamma, Interleukin-6, Lymphocytes, Oligonucleotide Array Sequence Analysis, Receptors, CXCR3, Receptors, CXCR4, Synovial Membrane, Transforming Growth Factor beta, Tumor Necrosis Factor-alpha, Vascular Cell Adhesion Molecule-1