Fig. 8

Effects of soluble biglycan (sBGN) on HEK-hTLR4 secreted embryonic alkaline phosphatase (SEAP) production and chondrocyte production of nitric oxide (NO) compared with control groups. a In primary chondrocytes, sBGN increased NO. Lipopolysaccharide (LPS) was used as a positive control. b In cartilage explants, sBGN increased NO only in grade I osteoarthritis (OA) without a difference between mild and severe OA. c Addition of polymyxin B had no effect on the sBGN-induced NO production, while proteinase K restored NO production to levels seen in controls, indicating that there was no endotoxin contamination of sBGN. Addition of Toll-like receptor 2 (TLR2)–neutralising antibody caused no significant reduction of sBGN-mediated NO production, while TLR4 neutralisation impaired NO production. Samples were run as technical duplicates, and each experiment was done using samples from at least six different donors (biological replicates). d Effect of sBGN, soluble decorin (sDCN) and LPS on TLR4 activity. An SEAP assay was used to determine nuclear factor (NF)-κB activity following sBGN, sDCN or LPS stimulation of HEK-hTLR4. The results are from three independent experiments. All results are expressed as mean ± SD. **p < 0.01, ***p < 0.001 vs. non-stimulated controls