Takagi Michiaki, Tamaki Yasunobu, Hasegawa Hiroshi, Takakubo Yuya, Konttinen Liisa, Tiainen Veli-Matti, Lappalainen Reijo, Konttinen Yrjö T, Salo Jari
Department of Orthopaedic Surgery, Yamagata University School of Medicine, Yamagata 990-9585, Japan.
J Biomed Mater Res A. 2007 Jun 15;81(4):1017-26. doi: 10.1002/jbm.a.31235.
Toll-like receptors (TLRs) have been known to act as sensors of innate immunity and respond to ligands of microbial and endogenous components. Tissues and cells typical for interface membrane of foreign body reaction were analyzed to evaluate potential role of TLRs in the pathogenesis of the so called "aseptic loosening of total hip replacement." Fourteen cases of interface membrane around aseptic loose total hip replacement implants were stained by single and double immunohistochemical methods to examine cellular localization of toll-like receptor (TLR)-4 and TLR-9. Osteoarthritic synovium was used as control tissues. Cultured macrophages were used to study TLR-4 and TLR-9 mRNA levels by quantitative reverse transcriptase-polymerase chain reaction. The effect of titanium particle stimulation on macrophages was also examined in the culture. Extensive immunolocalization of TLR-4 and TLR-9 positive cells was observed in the synovial membrane-like interface membrane of foreign body granulomas compared with control synovial membranes. TLR and CD68 double staining demonstrated that the TLR positive cells in aseptic loosening were mostly monocyte/macrophages and foreign body giant cells. TLR-4 and TLR-9 mRNA expression was also found in macrophage-colony stimulating factor treated rat macrophages, but this expression decreased (p < 0.05 or less) upon stimulation with titanium particles although matrix metalloproteinase (MMP)-9 mRNA levels used as macrophage activation marker were increased (p = 0.01). The interface membrane around loosening total hip replacement implants is apparently well equipped with TLRs and, thus, probably very sensitive to various structural components of microbes and to endogenous TLR ligands. This seems to be due to recruitment of monocyte/macrophages as particles per se seemed to down-regulate some of the key TLRs. This suppression after particle phagocytosis might prevent excessive and harmful host responses, and injury to innocent bystander cells/tissues.
Toll样受体（TLRs）已知作为天然免疫的传感器，对微生物和内源性成分的配体作出反应。分析异物反应界面膜典型的组织和细胞，以评估TLRs在所谓“全髋关节置换无菌性松动”发病机制中的潜在作用。采用单免疫组化和双免疫组化方法对14例无菌性松动全髋关节置换植入物周围的界面膜进行染色，以检测Toll样受体（TLR）-4和TLR-9的细胞定位。骨关节炎滑膜用作对照组织。培养的巨噬细胞用于通过定量逆转录聚合酶链反应研究TLR-4和TLR-9 mRNA水平。还在培养物中检测了钛颗粒刺激对巨噬细胞的影响。与对照滑膜相比，在异物肉芽肿的滑膜样界面膜中观察到TLR-4和TLR-9阳性细胞的广泛免疫定位。TLR和CD68双重染色表明，无菌性松动中的TLR阳性细胞主要是单核细胞/巨噬细胞和异物巨细胞。在巨噬细胞集落刺激因子处理的大鼠巨噬细胞中也发现了TLR-4和TLR-9 mRNA表达，但在用钛颗粒刺激后这种表达降低（p<0.05或更低），尽管用作巨噬细胞活化标志物的基质金属蛋白酶（MMP）-9 mRNA水平升高（p = 0.01）。松动的全髋关节置换植入物周围的界面膜显然富含TLRs，因此可能对微生物的各种结构成分和内源性TLR配体非常敏感。这似乎是由于单核细胞/巨噬细胞的募集，因为颗粒本身似乎下调了一些关键的TLRs。颗粒吞噬后的这种抑制作用可能会防止过度和有害的宿主反应以及对无辜旁观者细胞/组织的损伤。
