Inflammation is a host protective response to noxious stimuli, and excessive production of pro-inflammatory mediators by macrophages (m phi) can lead to numerous pathological conditions. In this study, immunomodulatory effects of immobilized and soluble glycosaminoglycans (GAGs) on mouse-bone-marrow-derived m phi were compared by measuring nitric oxide (NO). We demonstrate here that all GAGs studied except for heparin were able to modulate interferon-gamma/lipopolysaccharide (IFN-gamma/LPS)-induced NO release by imp to varying extents after 24 h of incubation. In particular, the modulatory activities of soluble chondroitin-6-sulfate (C6S), hyaluronic acid and heparan sulfate altered markedly after covalent immobilization. Of these, soluble C6S exhibited the strongest NO inhibitory activity, and the inhibition was dose- and time-dependent. Moreover, C6S significantly reduced pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha production by IFN-gamma/LPS- or LPS-activated m phi. Specifically, the C6S-mediated suppression of my) pro-inflammatory phenotype was accompanied by an increase in the IL-10 level, suggesting a possible switch towards anti-inflammatory/wound healing M2 state. In addition, the highest magnitude of inhibitory effects was obtained when cells were pre-treated with C6S prior to IFN-gamma/LPS or LPS challenge, suggesting an additional role for C6S in protection against microbial infection. Further investigations reveal that the anti-inflammatory effects of C6S on activated my may be ascribed at least in part to suppression of NF-kappa B nuclear translocation. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.