Department of Orthopedics, Ningxia Medical University General Hospital, Ningxia Hui Autonomous Region 750000, P.R. China.
Clinical Medical College, Xi'an Medical College, Xi'an, Shanxi 710000, P.R. China.
Int J Mol Med. 2022 Apr;49(4). doi: 10.3892/ijmm.2022.5103. Epub 2022 Feb 9.
Osteoarthritis (OA) is condition which poses a main concern to the aging population and its severity is expected to increase with the increasing life expectancy. In the future, several possible targets for OA treatment need to be defined. Dickkopf‑related protein 3 (DKK3) is an atypical member of the Wnt‑antagonistic dickkopf‑related protein (DKK) family. The availability of research into the role of DKK3 in the abnormal remodeling of subchondral bone in human knee joints is currently limited. Thus, the aim of the present study was the evaluation of DKK3 expression in the abnormal bone remodeling of subchondral bone in human knee OA in order to clarify the role of DKK3 in subchondral bone remodeling and to acknowledge its potential relevance to β‑catenin. In total, 38 specimens were collected from osteotomies of the medial tibial plateau of the human knee. The patient samples were then divided into the normal, mild, moderate and severe symptom groups, according to the Osteoarthritis Research Society International (OARSI) score. Following hematoxylin and eosin (H&E) and Safranin O‑fast green staining for alkaline phosphatase (AZO method), changes in the distribution and number of osteocytes in the subchondral bone and the degree of sclerosis of the subchondral bone were observed. Immunohistochemical staining, immunofluorescence, western blot analysis and reverse‑transcription quantitative PCR (RT‑qPCR) were used for the detection of DKK3 and β‑catenin expression level changes in osteoblasts in the subchondral bone of the medial tibial plateau. H&E and alkaline phosphatase staining revealed that the total number of osteocytes in the subchondral bone increased with the severity of the disease. The samples were also evaluated using Safranin O‑Fast Green staining and were attributed a score according to the OARSI scoring system: The scoring number and cartilage damage increased along with OA severity. Immunohistochemistry and immunofluorescence assays demonstrated that β‑catenin expression in osteocytes increased from mild to moderate, whereas DKK3 expression decreased with the development of arthritis from normal, mild to moderate. According to the results of western blot analysis, β‑catenin expression was higher in moderate OA and then decreased in severe OA. On the other hand, the DKK3 levels decreased along with the progression from normal, mild to moderate OA. The results of RT‑qPCR demonstrated that β‑catenin and DKK3 gene expression differed with the degree of OA. On the whole, the present study demonstrates that DKK3 and β‑catenin may play opposite roles in OA subchondral bone remodeling.
骨关节炎（OA）是一种主要困扰老年人群体的疾病，随着预期寿命的延长，其严重程度预计将会增加。未来，需要确定 OA 治疗的几个可能靶点。Dickkopf 相关蛋白 3（DKK3）是 Wnt 拮抗 Dickkopf 相关蛋白（DKK）家族的一个非典型成员。目前，关于 DKK3 在人类膝关节软骨下骨异常重塑中的作用的研究可用的资料有限。因此，本研究旨在评估 DKK3 在人类膝骨关节炎软骨下骨异常重塑中的表达，以阐明 DKK3 在软骨下骨重塑中的作用，并承认其与 β-连环蛋白的潜在相关性。总共从人类膝关节内侧胫骨平台的截骨术中收集了 38 个标本。然后根据骨关节炎研究协会国际（OARSI）评分，将患者样本分为正常、轻度、中度和重度症状组。在苏木精和伊红（H&E）以及番红 O-快绿碱性磷酸酶染色（AZO 法）后，观察软骨下骨中骨细胞的分布和数量以及软骨下骨硬化程度的变化。采用免疫组织化学染色、免疫荧光、western blot 分析和逆转录定量 PCR（RT-qPCR）检测软骨下骨内侧胫骨平台成骨细胞中 DKK3 和 β-连环蛋白表达水平的变化。H&E 和碱性磷酸酶染色显示，软骨下骨中总骨细胞数量随疾病严重程度的增加而增加。还使用番红 O-快绿染色对样本进行了评估，并根据 OARSI 评分系统对样本进行了评分：评分数量和软骨损伤随着 OA 严重程度的增加而增加。免疫组织化学和免疫荧光检测显示，β-连环蛋白在骨细胞中的表达从轻度到中度增加，而 DKK3 的表达随着关节炎从正常、轻度到中度的发展而减少。根据 western blot 分析的结果，中度 OA 时 β-连环蛋白表达较高，然后在重度 OA 时减少。另一方面，随着正常、轻度到中度 OA 的进展，DKK3 水平降低。RT-qPCR 结果表明，β-连环蛋白和 DKK3 基因表达随 OA 程度不同而不同。总的来说，本研究表明 DKK3 和 β-连环蛋白可能在 OA 软骨下骨重塑中发挥相反的作用。
