Sasaki Hiroshi, Takayama Koji, Matsushita Takehiko, Ishida Kazunari, Kubo Seiji, Matsumoto Tomoyuki, Fujita Norifumi, Oka Shinya, Kurosaka Masahiro, Kuroda Ryosuke
Kobe University Graduate School of Medicine, Kobe, Japan.
Arthritis Rheum. 2012 Jun;64(6):1920-8. doi: 10.1002/art.34323. Epub 2011 Dec 6.
Autophagy, an evolutionarily conserved process for the bulk degradation of cytoplasmic components, serves as a cell survival mechanism. The purpose of this study was to elucidate the role of autophagy in human chondrocytes and pathophysiology of osteoarthritis (OA).
Autophagy in articular cartilage and primary chondrocytes was assessed using antibodies for the autophagy markers light chain 3 and beclin 1. The states of autophagy under catabolic and nutritional stresses were examined. We also examined the effects of inhibition or induction of autophagy under stimulation with interleukin-1β. Autophagy was inhibited by small interfering RNA targeting ATG5, and autophagy was induced by rapamycin. The effects of inhibition or induction of autophagy were examined by real-time polymerase chain reaction for aggrecan, COL2A1, MMP13, and ADAMTS5 messenger RNA. To further examine the mechanism of autophagy regulation in OA human chondrocytes, we investigated whether autophagy modulates apoptosis and reactive oxygen species (ROS).
Autophagy was increased in OA chondrocytes and cartilage. Catabolic and nutritional stresses increased autophagy. In addition, the inhibition of autophagy caused OA-like gene expression changes, while the induction of autophagy prevented them. Furthermore, the inhibition of autophagy increased the amount of cleaved poly(ADP-ribose) polymerase and cleaved caspase 9, while the induction of autophagy inhibited these increases. ROS activity was also decreased by induction of autophagy.
These observations suggested that increased autophagy is an adaptive response to protect cells from stresses, and that autophagy regulates OA-like gene expression changes through the modulation of apoptosis and ROS. Further studies about autophagy in chondrocytes will provide novel insights into the pathophysiology of OA.
自噬是一种进化上保守的细胞质成分大量降解过程，作为一种细胞存活机制。本研究的目的是阐明自噬在人软骨细胞中的作用以及骨关节炎（OA）的病理生理学。
使用自噬标志物轻链3和贝林1的抗体评估关节软骨和原代软骨细胞中的自噬。检查分解代谢和营养应激下的自噬状态。我们还研究了白细胞介素-1β刺激下自噬抑制或诱导的作用。通过靶向ATG5的小干扰RNA抑制自噬，用雷帕霉素诱导自噬。通过实时聚合酶链反应检测聚集蛋白聚糖、COL2A1、MMP13和ADAMTS5信使RNA来研究自噬抑制或诱导的作用。为了进一步研究OA人软骨细胞中自噬调节的机制，我们研究了自噬是否调节细胞凋亡和活性氧（ROS）。
OA软骨细胞和软骨中的自噬增加。分解代谢和营养应激增加自噬。此外，自噬抑制导致OA样基因表达变化，而自噬诱导可防止这些变化。此外，自噬抑制增加了裂解的聚（ADP-核糖）聚合酶和裂解的半胱天冬酶9的量，而自噬诱导抑制了这些增加。自噬诱导也降低了ROS活性。
这些观察结果表明，自噬增加是一种适应性反应，可保护细胞免受应激，并且自噬通过调节细胞凋亡和ROS来调节OA样基因表达变化。关于软骨细胞中自噬的进一步研究将为OA的病理生理学提供新的见解。
