Zhang Zhenzhen, Zeng Jing, Li Yang, Liao Qing, Huang Dongdong, Zou Yucong, Liu Gang
Department of Rehabilitation Medicine, The Third Affiliated Hospital of Southern Medical University, Guangzhou, Guangdong 510000, P.R. China.
Department of Rehabilitation Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
Exp Ther Med. 2021 Sep;22(3):965. doi: 10.3892/etm.2021.10397. Epub 2021 Jul 7.
Ankylosing spondylitis (AS), characterized by inflammatory lesions and osteophyte formation, is a common immune rheumatic disease affecting the sacroiliac and axial joints. A high-intensity mechanical load is known to accelerate the heterotopic ossification associated with enthesitis in AS. Thus, the present study explored whether decreased mechanical load could delay the heterotopic ossification in AS. First, 24-week-old female BALB/c mice were induced with proteoglycan (PG) to establish an AS model. The AS-induced pathological and bone morphological changes of the sacroiliac joint were confirmed by hematoxylin and eosin staining and microCT analysis, respectively. Subsequently, the mice were treated with interventions of different mechanical loads. Using reverse transcription-quantitative PCR, it was revealed that expression levels of the osteogenesis-related genes bone morphogenetic protein-2, runt-related transcription factor 2 and osteocalcin were significantly reduced in sacroiliac bone tissue after intervention with a reduced mechanical load. The level of mechanosensory microRNA (miR)-103 increased in response to reduced mechanical loads. Consistently, in groups with reduced mechanical load, proteins with mechanical functions, including ρ-associated coiled-coil-containing protein kinase 1 (ROCK1), phosphorylated (p)-Erk1/2 and β-catenin, were reduced compared with the PG control. A dual-luciferase assay verified that miR-103 binds to the 3'-untranslated region end of mRNA, thus negatively regulating the activity of and affecting pathological ossification during AS. However, immunohistochemical staining indicated that the expression of dickkopf Wnt signaling pathway inhibitor 1, an inhibitor of the Wnt/β-catenin pathway, was increased in sacroiliac tissues. The results indicated that tail suspension decreased the mechanical load, thus reducing the bone formation in AS mice. Furthermore, tail suspension could inhibit the activation of mechanical kinase ROCK1 and p-Erk1/2 in the MAPK signaling pathway by upregulating miR-103, thereby inhibiting the classical osteogenesis-related Wnt/β-catenin pathway in AS. In summary, the present study uncovered the ameliorative effect of suspension on AS and its therapeutic potential for AS.
强直性脊柱炎（AS）以炎症性病变和骨赘形成为特征，是一种影响骶髂关节和中轴关节的常见免疫性风湿疾病。已知高强度机械负荷会加速AS中与肌腱端炎相关的异位骨化。因此，本研究探讨了机械负荷降低是否能延缓AS中的异位骨化。首先，用蛋白聚糖（PG）诱导24周龄雌性BALB/c小鼠建立AS模型。分别通过苏木精-伊红染色和显微CT分析证实了AS诱导的骶髂关节病理和骨形态学变化。随后，对小鼠进行不同机械负荷的干预处理。通过逆转录定量PCR发现，机械负荷降低干预后，骶髂骨组织中骨形态发生蛋白-2、 runt相关转录因子2和骨钙素等成骨相关基因的表达水平显著降低。机械感觉微小RNA（miR）-103的水平随着机械负荷降低而升高。同样，在机械负荷降低的组中，与PG对照组相比，包括ρ相关卷曲螺旋蛋白激酶1（ROCK1）、磷酸化（p）-Erk1/2和β-连环蛋白在内的具有机械功能的蛋白质减少。双荧光素酶报告基因检测证实miR-103与mRNA的3'-非翻译区末端结合，从而负向调节其活性并影响AS期间的病理性骨化。然而，免疫组化染色表明，Wnt/β-连环蛋白通路抑制剂Dickkopf Wnt信号通路抑制因子1在骶髂组织中的表达增加。结果表明，尾部悬吊降低了机械负荷，从而减少了AS小鼠的骨形成。此外，尾部悬吊可通过上调miR-103抑制丝裂原活化蛋白激酶（MAPK）信号通路中机械激酶ROCK1和p-Erk1/2的激活，从而抑制AS中经典的成骨相关Wnt/β-连环蛋白通路。总之，本研究揭示了悬吊对AS的改善作用及其治疗AS的潜力。
