Zhang Q, Hui W, Litherland G J, Barter M J, Davidson R, Darrah C, Donell S T, Clark I M, Cawston T E, Robinson J H, Rowan A D, Young D A
Musculoskeletal Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
Ann Rheum Dis. 2008 Nov;67(11):1633-41. doi: 10.1136/ard.2007.079574. Epub 2008 Feb 7.
To characterise the catabolic response of osteoarthritic chondrocytes to Toll-like receptor (TLR) ligands.
Induction of the collagenases, matrix metalloproteinase (MMP)1 and MMP13, by TLR ligands was assessed in chondrocytes by real-time reverse transcriptase (RT)-PCR. TLR signalling pathway activation and their involvement in collagenase induction were confirmed by immunoblotting and use of pathway inhibitors and siRNA. TLR expression was compared in the femoral head cartilage of normal controls and patients with osteoarthritis (OA) by real-time RT-PCR.
Ligands for TLR6/2 and TLR3 showed the greatest upregulation of MMP1 and MMP13 respectively, although all TLR ligands upregulated these MMPs. MMP1 and MMP13 induction by TLR3 and TLR1/2 or TLR6/2 ligands were dependent on Trif and MyD88, respectively. These inductions were dependent upon the nuclear factor (NF)kappaB pathway, but were differentially inhibited by various mitogen-activated protein kinase inhibitors, with MMP13 induction most reliant on the extracellular signal-regulated kinase pathway. In addition, ligands for TLR1/2 and TLR6/2, but not TLR3, induced significant collagenolysis in a cartilage resorption assay. Finally, TLR2 was significantly downregulated and TLR3 upregulated in OA, compared to normal, cartilage.
Activation of chondrocyte TLRs leads to differential collagenase gene activation. Treatment of chondrocytes with TLR1/2 or TLR6/2 ligands resulted in collagen resorption. The modulated expression of chondrocyte TLR2 and TLR3 in OA cartilage, compared to normal, may reflect a response to repair cartilage or prevent further extracellular matrix destruction. These data suggest modulation of TLR-mediated signalling as a potential therapeutic strategy for the treatment of OA.
描述骨关节炎软骨细胞对Toll样受体（TLR）配体的分解代谢反应。
通过实时逆转录酶（RT）-PCR评估TLR配体对软骨细胞中胶原酶、基质金属蛋白酶（MMP）1和MMP13的诱导作用。通过免疫印迹以及使用信号通路抑制剂和小干扰RNA（siRNA）来确认TLR信号通路的激活及其在胶原酶诱导中的作用。通过实时RT-PCR比较正常对照者和骨关节炎（OA）患者股骨头软骨中TLR的表达。
TLR6/2和TLR3的配体分别显示出对MMP1和MMP13的最大上调作用，尽管所有TLR配体均上调了这些MMP。TLR3和TLR1/2或TLR6/2配体对MMP1和MMP13的诱导分别依赖于Trif和MyD88。这些诱导作用依赖于核因子（NF）κB通路，但受到各种丝裂原活化蛋白激酶抑制剂的不同程度抑制，其中MMP13的诱导最依赖于细胞外信号调节激酶通路。此外，在软骨吸收试验中，TLR1/2和TLR6/2的配体而非TLR3的配体诱导了显著的胶原溶解。最后，与正常软骨相比，OA软骨中TLR2显著下调而TLR3上调。
软骨细胞TLR的激活导致不同的胶原酶基因激活。用TLR1/2或TLR6/2配体处理软骨细胞会导致胶原吸收。与正常情况相比，OA软骨中软骨细胞TLR2和TLR3的表达调节可能反映了对修复软骨或防止细胞外基质进一步破坏的反应。这些数据表明调节TLR介导的信号传导作为治疗OA的潜在治疗策略。
