Inhibition of CDK9 prevents mechanical injury-induced inflammation, apoptosis and matrix degradation in cartilage explants.
Inhibition of CDK9 prevents mechanical injury-induced inflammation, apoptosis and matrix degradation in cartilage explants.
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CDK9 的抑制可防止机械损伤引起的软骨外植体炎症、细胞凋亡和基质降解。
DOI：
10.22203/ecm.v030a14
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发表时间：
2016
影响因子：
3.1
通讯作者：
Haudenschild DR
中科院分区：
文献类型：
--
作者：
Hu Z;Yik JH;Cissell DD;Michelier PV;Athanasiou KA;Haudenschild DR
关节损伤常导致创伤后骨关节炎（pta）。创伤的急性损伤反应诱导促炎细胞因子和分解代谢酶的产生，从而促进软骨细胞凋亡和软骨降解，从而增强PTOA的发展。最近的研究表明，损伤反应基因转录激活的限速步骤是由细胞周期蛋白依赖性激酶9 （cyclin-dependent kinase 9, CDK9）控制的，因此它是限制损伤反应的一个有吸引力的靶点。在这里，我们确定了CDK9抑制在抑制机械损伤软骨外植体损伤反应中的作用。以30%应变、100% /s的单次压缩载荷损伤牛软骨外植体，然后用CDK9抑制剂黄匹吡醇处理。为了评估急性损伤反应，我们通过RT-PCR检测了促炎细胞因子、分解代谢酶和凋亡基因的mRNA表达，并通过TUNEL染色检测了软骨细胞活力和凋亡。对于长期结果，通过可溶性糖胺聚糖释放和瞬时模量和松弛模量测定力学性能来评估软骨基质降解。我们的数据显示CDK9抑制剂显著降低损伤诱导的炎症细胞因子和分解代谢基因的表达。CDK9抑制剂还能减轻软骨细胞凋亡和软骨基质降解。最后，用CDK9抑制剂保护损伤外植体的力学性能。我们的研究结果提供了从机械冲击、急性损伤反应到随后诱导软骨细胞凋亡和软骨基质退化的一系列事件的时间概况。因此，CDK9是一种潜在的疾病调节剂，可以预防或延缓膝外伤后的损伤反应。
Joint injury often leads to post-traumatic osteoarthritis (PTOA). Acute injury responses to trauma induce production of pro-inflammatory cytokines and catabolic enzymes, which promote chondrocyte apoptosis and degrade cartilage to potentiate PTOA development. Recent studies show that the rate-limiting step for transcriptional activation of injury response genes is controlled by cyclin-dependent kinase 9 (CDK9), and thus it is an attractive target for limiting the injury response. Here, we determined the effects of CDK9 inhibition in suppressing the injury response in mechanically-injured cartilage explants. Bovine cartilage explants were injured by a single compressive load of 30 % strain at 100 %/s, and then treated with the CDK9 inhibitor Flavopiridol. To assess acute injury responses, we measured the mRNA expression of pro-inflammatory cytokines, catabolic enzymes, and apoptotic genes by RT-PCR, and chondrocyte viability and apoptosis by TUNEL staining. For long-term outcome, cartilage matrix degradation was assessed by soluble glycosaminoglycan release, and by determining the mechanical properties with instantaneous and relaxation moduli. Our data showed CDK9 inhibitor markedly reduced injury-induced inflammatory cytokine and catabolic gene expression. CDK9 inhibitor also attenuated chondrocyte apoptosis and reduced cartilage matrix degradation. Lastly, the mechanical properties of the injured explants were preserved by CDK9 inhibitor. Our results provide a temporal profile connecting the chain of events from mechanical impact, acute injury responses, to the subsequent induction of chondrocyte apoptosis and cartilage matrix deterioration. Thus, CDK9 is a potential disease-modifying agent for injury response after knee trauma to prevent or delay PTOA development.