Li Lei, Pang Yiqun, Zhang Linlin, Li Meng, Zhu Chen, Fang Shiyuan, Yin Zongsheng
Department of Orthopaedics,the First Affiliated Hospital of University of Science and Technology of China, #17 Lujiang Road, Hefei, Anhui, China.
Department of Orthopaedics, the First Affiliated Hospital of Anhui Medical University, #269 Jixi Road, Hefei, Anhui, China.
Iran J Basic Med Sci. 2020 Jun;23(6):819-825. doi: 10.22038/ijbms.2020.43634.10252.
Previous study has indicated that triiodothyronine (T3) facilitated cartilage degeneration in osteoarthritis (OA). This study aimed to investigate the effects of T3 on angiogenesis-related factor expression in human osteoblasts of OA subchondral bone.
The subchondral bone specimens were obtained from OA patients and healthy participants. The expressions of VEGF, HIF-1α, AKT, and phosphorylated AKT was detected by immunohistochemistry, Western blotting, and RT-qPCR in OA. Angiogenesis-related factor expression in OA osteoblasts was measured by treating different concentrations of T3. The hypoxia model and PX-478 (HIF-1α inhibitor) were employed to confirm the regulative role of HIF-1α for VEGF expression. The level of VEGF secretion was examined in osteoblasts supernatant using ELISA.
Immunohistochemistry showed strong staining of VEGF and HIF-1α in OA subchondral bone. The expression of VEGF, HIF-1α, and p-AKT in OA osteoblasts was higher than that of normal osteoblasts at protein and mRNA levels. The physiological concentration of T3 (10-7 M) in OA osteoblasts up-regulated the expression of VEGF, HIF-1α, and p-AKT after 24 hr and 48 hr culture, while a higher dose of T3 displayed the adverse effects. Additionally, VEGF and p-AKT expression was down-regulated when PX-478 inhibited HIF-1α protein.
Our results suggested that local T3 could effectively increase angiogenesis-related factor expression by PI3K/AKT signaling pathway, and HIF-1α regulated the VEGF expression in OA osteoblasts.
既往研究表明，三碘甲状腺原氨酸（T3）促进骨关节炎（OA）中的软骨退变。本研究旨在探讨T3对OA软骨下骨人成骨细胞中血管生成相关因子表达的影响。
从OA患者和健康参与者获取软骨下骨标本。通过免疫组织化学、蛋白质印迹法和RT-qPCR检测OA中血管内皮生长因子（VEGF）、缺氧诱导因子-1α（HIF-1α）、蛋白激酶B（AKT）和磷酸化AKT的表达。通过用不同浓度的T3处理来检测OA成骨细胞中血管生成相关因子的表达。采用缺氧模型和PX-478（HIF-1α抑制剂）来证实HIF-1α对VEGF表达的调节作用。使用酶联免疫吸附测定法检测成骨细胞上清液中VEGF的分泌水平。
免疫组织化学显示OA软骨下骨中VEGF和HIF-1α染色强烈。OA成骨细胞中VEGF、HIF-1α和磷酸化AKT在蛋白质和mRNA水平的表达高于正常成骨细胞。OA成骨细胞中生理浓度的T3（10-7 M）在培养24小时和48小时后上调VEGF、HIF-1α和磷酸化AKT的表达，而更高剂量的T3则显示出不利影响。此外，当PX-478抑制HIF-1α蛋白时，VEGF和磷酸化AKT表达下调。
我们的结果表明，局部T3可通过磷脂酰肌醇-3激酶/AKT信号通路有效增加血管生成相关因子的表达，且HIF-1α调节OA成骨细胞中VEGF的表达。
