Department of Orthopedics, The Affiliated Zhangjiagang Hospital of Soochow University, Zhangjiagang, China.
Eur Rev Med Pharmacol Sci. 2021 Feb;25(3):1233-1241. doi: 10.26355/eurrev_202102_24827.
Mechanical-stress has been reported to trigger cartilage fibrosis, in which transforming growth factor (TGF)-β and connective tissue growth factor (CCN2) are involved. However, the function of integrin-α5β1, a cytomembrane receptor, on mechanical-stress related fibrosis has not yet been elucidated. This study aims to reveal the interaction of TGF-β1/CCN2/integrin-α5β1 in the mechanical-stress induced chondrocyte (CH) fibrosis.
We used different levels (5% and 10%) of cyclic tension simulation (CTS) to stretch CHs and observed the gene expression of TGF-β1/CCN2/integrin-α5β1 as well as the fibrous related genes containing collagen I/II/III, Runx2, MMP13, and ADAMTS-5 by real-time polymerase chain reaction (RT-PCR) or immunofluorescence. We used the siRNA or the corresponding antagonist of TGF-β1, CCN2, integrin-α5β1 during the CTS to clear the effect of them in the fibrosis progress. In addition, to verify the crosstalk between TGF-β1, CCN2, and integrin-α5β1, we used the recombinant human (rh)-TGF-β1 and CCN2 to culture CHs without CST.
24 hours-10% CTS was sufficient to induce a decrease of collagen II and increase the collagen I/III, Runx2, MMP13, and ADAMTS-5 gene expression. Under CTS, TGF-β1 silencing resulted in a decline of CCN2, integrin-α5β1, and alleviated the CHs fibrosis. Apart from this, blocking CCN2 or integrin-α5β1 expression also contributed to the suppression of 10% CTS induced CHs fibrosis. Meanwhile, the exogenic protein supplement raised the cellular TGF-β1 or CCN2 expression and increased the integrin-α5β1 mRNA level. However, the downregulation of TGF-β1 or CCN2 did not affect integrin-α5β1 expression, whether the CTS exited or not.
High mechanical-stress induces CHs fibrosis via the activation of TGF-β1/CCN2/integrin-α5β1 signaling, and interrupting the TGF-β1, CCN2, or integrin-α5β1 expression can alleviate the fibrous process.
机械应力已被报道可引发软骨纤维化，其中转化生长因子 (TGF)-β 和结缔组织生长因子 (CCN2) 参与其中。然而，细胞外基质受体整合素-α5β1 在机械应力相关纤维化中的作用尚未阐明。本研究旨在揭示 TGF-β1/CCN2/整合素-α5β1 在机械应力诱导的软骨细胞 (CH) 纤维化中的相互作用。
我们使用不同水平（5%和 10%）的循环张力模拟 (CTS) 拉伸 CHs，并通过实时聚合酶链反应 (RT-PCR) 或免疫荧光观察 TGF-β1/CCN2/整合素-α5β1 的基因表达以及包含胶原 I/II/III、Runx2、MMP13 和 ADAMTS-5 的纤维相关基因。我们在 CTS 期间使用 TGF-β1、CCN2、整合素-α5β1 的 siRNA 或相应拮抗剂来清除它们在纤维化进展中的作用。此外，为了验证 TGF-β1、CCN2 和整合素-α5β1 之间的串扰，我们使用重组人 (rh)-TGF-β1 和 CCN2 在没有 CST 的情况下培养 CHs。
24 小时 10% CTS 足以诱导胶原 II 减少和胶原 I/III、Runx2、MMP13 和 ADAMTS-5 基因表达增加。在 CTS 下，TGF-β1 沉默导致 CCN2、整合素-α5β1 减少，并减轻 CHs 纤维化。除此之外，阻断 CCN2 或整合素-α5β1 的表达也有助于抑制 10% CTS 诱导的 CHs 纤维化。同时，外源性蛋白补充提高了细胞 TGF-β1 或 CCN2 的表达，并增加了整合素-α5β1 mRNA 水平。然而，无论 CTS 是否存在，TGF-β1 或 CCN2 的下调都不会影响整合素-α5β1 的表达。
高机械应力通过激活 TGF-β1/CCN2/整合素-α5β1 信号通路诱导 CHs 纤维化，阻断 TGF-β1、CCN2 或整合素-α5β1 的表达可以减轻纤维化过程。
