Ishizuka Yasuyuki, Moriwaki Sawako, Kawahara-Hanaoka Miyuki, Uemura Yasunori, Serizawa Isao, Miyauchi Mutsumi, Shibata Shunichi, Kanaya Toshimichi, Takata Takashi, Taniguchi Naoyuki, Niida Shumpei
Applied Cell Biotechnologies, Yokohama, Kanagawa, Japan.
J Bone Miner Res. 2007 Dec;22(12):1933-42. doi: 10.1359/jbmr.070726.
The effectiveness of a new antibody treatment on arthritis-associated osteolysis was studied by using CIA mice. GGT, a newly identified bone-resorbing factor, was upregulated in arthritic joints. We generated monoclonal antibodies against GGT and injected them into CIA mice. Mice treated with antibodies showed a reduction in osteoclast number and bone erosion.
Gamma-glutamyl transpeptidase (GGT) acts as a bone-resorbing factor that stimulates osteoclast formation. GGT expression has been detected in active lymphocytes that accumulate at inflammation sites, such as rheumatoid arthritis (RA). We hypothesize that GGT is an effective target for suppression of arthritis-related osteoclastogenesis and joint destruction. Here, we describe the therapeutic effect of neutralizing antibodies against GGT on joint destruction using a collagen-induced arthritis (CIA) mouse model.
GGT expression in the synovium of RA patients and CIA mice was determined by immunohistochemistry and RT-PCR. Monoclonal antibodies were generated against recombinant human GGT (GGT-mAbs) using BALB/c mice. Antibody treatment was performed by intraperitoneal injections of GGT-mAbs into CIA mice. Effects of antibody treatment on arthritis and bone erosion were evaluated by incidence score, arthritis score, and histopathological observations. The role of GGT in osteoclast development was examined by using the established osteoclastogenic culture system.
GGT expression was significantly upregulated in inflamed synovium. Immunohistochemistry revealed that GGT was present in lymphocytes, plasma cells, and macrophages, as well as capillaries. Injection of GGT-mAbs significantly decreased the number of osteoclasts and attenuated the severity of joint destruction in CIA mice. In vitro examination showed that GGT enhanced RANKL-dependent osteoclast formation. GGT stimulated the expression of RANKL in osteoblasts and its receptor RANK in osteoclast precursors, respectively.
This study indicates that inflamed synovial tissue-derived GGT acts as a risk factor for joint destruction and that the antibody-mediated inhibition of GGT significantly decreases osteoclast number and bone erosion in CIA mice. GGT antagonists might be novel therapeutic agents for attenuating joint destruction in RA patients.
通过使用胶原诱导的关节炎（CIA）小鼠研究了一种新的抗体治疗对关节炎相关骨质溶解的有效性。γ-谷氨酰转肽酶（GGT）是一种新发现的骨吸收因子，在关节炎关节中上调。我们制备了针对GGT的单克隆抗体并将其注射到CIA小鼠体内。用抗体治疗的小鼠破骨细胞数量减少，骨侵蚀减轻。
γ-谷氨酰转肽酶（GGT）作为一种骨吸收因子，刺激破骨细胞形成。在类风湿关节炎（RA）等炎症部位积聚的活化淋巴细胞中已检测到GGT表达。我们假设GGT是抑制关节炎相关破骨细胞生成和关节破坏的有效靶点。在此，我们使用胶原诱导的关节炎（CIA）小鼠模型描述了针对GGT的中和抗体对关节破坏的治疗效果。
通过免疫组织化学和逆转录-聚合酶链反应（RT-PCR）测定RA患者和CIA小鼠滑膜中GGT的表达。使用BALB/c小鼠制备针对重组人GGT的单克隆抗体（GGT-mAbs）。通过向CIA小鼠腹腔注射GGT-mAbs进行抗体治疗。通过发病率评分、关节炎评分和组织病理学观察评估抗体治疗对关节炎和骨侵蚀的影响。使用已建立的破骨细胞生成培养系统研究GGT在破骨细胞发育中的作用。
在炎症滑膜中GGT表达显著上调。免疫组织化学显示GGT存在于淋巴细胞、浆细胞、巨噬细胞以及毛细血管中。注射GGT-mAbs显著减少了CIA小鼠破骨细胞数量，并减轻了关节破坏的严重程度。体外检查表明GGT增强了RANKL依赖性破骨细胞形成。GGT分别刺激成骨细胞中RANKL及其在破骨细胞前体中的受体RANK的表达。
本研究表明，炎症滑膜组织来源的GGT是关节破坏的危险因素，抗体介导的GGT抑制显著减少了CIA小鼠的破骨细胞数量和骨侵蚀。GGT拮抗剂可能是减轻RA患者关节破坏的新型治疗药物。
