Figure 6.

MyD88 mediates ADAMTS5 release and maturation to hypertrophy in chondrocytes in response to transfection of hyal2 and HMGB1. Immature mouse chondrocytes isolated from MyD88^−/− and congenic WT mice were transfected with either hyal2 or HMGB1, with an empty vector plasmid DNA used as a control. Forty-eight hours after transfection, the cells were placed onto poly-HEME coated plates. Release of ADAMTS5 (A) and type × collagen protein expression (B) were determined from conditioned media after two more days and cell lysates after three more days, respectively, by Western blot analyses. The mRNA expression of type II and type × collagen, MMP-13 and Runx2 (C–F) were analyzed by quantitative RT-PCR after two more days. Data for release of ADAMTS5 and type × collagen protein expression in A and B were representative of 3 individual experiments. Data for mRNA expression of type II and type × collagen, MMP-13 and Runx2 (C–F) were from chondrocytes (n=3). Statistics for type II mRNA expression in C, *p<0.02 and #p<0.01 for WT chondrocytes transfected with hyal2 and HMGB1 relative to WT chondrocytes transfected with the vector control, respectively; **, ##P<0.01 comparing MyD88^−/− with WT chondrocytes in response to transfection with hyal2 and HMGB1, respectively. For mRNA expression of type × collagen, MMP-13, and Runx2, *,# p<0.05 (Figure D), *,#p<0.001 (Figure E), and *,#p<0.02 (Figure F) comparing MyD88^−/− with WT chondrocytes in response to transfection with hyal2 and HMGB1, respectively.