Department of Orthopedics, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, P.R. China.
College of Information Engineering, Nanchang University, Nanchang, Jiangxi 330031, P.R. China.
Mol Med Rep. 2018 Mar;17(3):3821-3828. doi: 10.3892/mmr.2017.8304. Epub 2017 Dec 18.
Effective therapeutic methods for osteoarthritis (OA) are lacking. γ‑glutamyl carboxylase (GGCX) is a key enzyme that regulates carboxylation of cartilage matrix Gla protein (MGP). Whether GGCX overexpression protects against OA remains unknown. The aim of the present study was to explore the effects of GGCX overexpression on anterior cruciate ligament transection (ACLT)‑induced OA and its mechanisms in Japanese white rabbits. ACLT surgery was used to establish an OA model in rabbits. A total of 48 rabbits were randomly divided into 4 groups: Sham, OA model + GGCX overexpression plasmid, OA model + saline and OA model + empty vector. The expression of uncarboxylated MGP (ucMGP), carboxylated MGP (cMGP), matrix metalloproteinase (MMP)‑13, collagen type X, collagen type II, tumor necrosis factor (TNF)‑α and interleukin (IL)‑1β were detected by ELISA, immunohistochemistry, reverse transcription‑quantitative polymerase chain reaction and western blotting. Morphological changes to tibial cartilage were assessed by Giemsa and safranin O‑fast green staining, respectively. Compared with the Sham control, GGCX expression was significantly decreased in the OA Model group. GGCX expression was increased by injection of a lentivirus‑carried overexpression plasmid that encoded GGCX. GGCX overexpression ameliorated ATLC‑induced damage in articular cartilage. OA Model rabbits exhibited significantly decreased expression levels of cMGP and collagen type II, and increased expression of ucMGP, collagen type X, MMP‑13, IL‑1β and TNF‑α. Notably, these expression levels were reversed by GGCX overexpression in OA Model rabbits. Results from the present study indicated that GGCX expression was decreased in OA Model rabbits, whereas overexpression of GGCX was able to promote carboxylation of MGP, reduce inflammation, decrease MMP‑13 expression and regulate collagen expression. The results also indicated that GGCX may serve as a therapeutic target for OA.
治疗骨关节炎（OA）的有效方法仍然缺乏。γ-谷氨酰羧化酶（GGCX）是调节软骨基质 Gla 蛋白（MGP）羧化的关键酶。GGCX 过表达是否能预防 OA 尚不清楚。本研究旨在探讨 GGCX 过表达对前交叉韧带切断（ACLT）诱导的 OA 的影响及其在日本大白兔中的机制。采用 ACLT 手术建立兔 OA 模型。将 48 只兔子随机分为 4 组：假手术组、OA 模型+GGCX 过表达质粒组、OA 模型+生理盐水组和 OA 模型+空载体组。采用 ELISA、免疫组化、逆转录-定量聚合酶链反应和 Western blot 检测未羧化 MGP（ucMGP）、羧化 MGP（cMGP）、基质金属蛋白酶（MMP）-13、X 型胶原、II 型胶原、肿瘤坏死因子（TNF）-α和白细胞介素（IL）-1β的表达。通过 Giemsa 和 safranin O-快绿染色分别评估胫骨软骨的形态变化。与 Sham 对照组相比，OA 模型组 GGCX 表达明显降低。注射携带 GGCX 过表达质粒的慢病毒后 GGCX 表达增加。GGCX 过表达改善了 ACLT 诱导的关节软骨损伤。OA 模型兔 cMGP 和 II 型胶原表达降低，ucMGP、X 型胶原、MMP-13、IL-1β和 TNF-α表达增加。值得注意的是，OA 模型兔中 GGCX 过表达逆转了这些表达水平。本研究结果表明，OA 模型兔 GGCX 表达降低，而过表达 GGCX 能够促进 MGP 羧化，减少炎症，降低 MMP-13 表达，调节胶原表达。研究结果还表明，GGCX 可能成为 OA 的治疗靶点。
