脂联素通过促进类风湿关节炎滑膜组织中骨桥蛋白的产生而加重骨侵蚀。

Adiponectin aggravates bone erosion by promoting osteopontin production in synovial tissue of rheumatoid arthritis.

机构信息

Department of Rheumatology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, 210029, China.

Department of Rheumatology, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, China.

出版信息

Arthritis Res Ther. 2018 Feb 8;20(1):26. doi: 10.1186/s13075-018-1526-y.

DOI:10.1186/s13075-018-1526-y

PMID:29422077

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC5806355/

Abstract

BACKGROUND

We have previously reported that adiponectin (AD), an adipokine that is secreted by adipocytes, correlates well with progressive bone erosion in rheumatoid arthritis (RA). The exact mechanism of AD in promoting joint destruction remains unclear. Osteopontin (OPN) is required for osteoclast recruitment. We hypothesized that AD exacerbates bone erosion by inducing OPN expression in synovial tissue. This study aimed to evaluate a novel role for AD in RA.

METHODS

The serum levels of AD and OPN were determined in 38 patients with RA, 40 patients with osteoarthritis (OA), and 20 healthy controls using enzyme-linked immunosorbent assay (ELISA). AD and OPN production were measured by double immunofluorescence in RA and OA synovial tissue. Quantitative real-time PCR and immunofluorescence were used to evaluate the mRNA and protein expression levels of OPN in RA synovial fibroblasts (RASFs) and OA synovial fibroblasts after pre-incubation with AD, respectively. Migration of the RAW264.7 osteoclast precursor cell line was assessed using the Transwell migration assay and co-culture system. Bone destruction and osteoclastogenesis were assessed by immunohistochemical staining, microcomputed tomography and tartrate-resistant acid phosphatase (TRAP) staining in AD-treated collagen-induced arthritis (CIA) mice with or without OPN silencing. The expression levels of OPN and integrin αβ in the ankle joint tissues of the mice were examined by double immunofluorescence.

RESULTS

Our results indicated that the AD and OPN expression levels increased noticeably and were associated with each other in the RA serum. The AD distribution was coincident with that of OPN in the RA synovial tissue. AD stimulation of RASFs increased OPN production in a dose-dependent manner. AD-treated RASFs promoted RAW264.7 cell migration, and the effect was blocked with a specific antibody against OPN. Silencing of OPN using lentiviral-OPN short hairpin RNA reduced the number of TRAP-positive osteoclasts and the extent of bone erosion in the AD-treated CIA mice. When bound to integrin αβ, OPN functions as a mediator of AD and osteoclasts.

CONCLUSIONS

Our study provides new evidence of AD involvement in bone erosion. AD induces the expression of OPN, which recruits osteoclasts and initiates bone erosion. These data highlight AD as a novel target for RA treatment.

摘要

背景

我们之前的研究表明，脂联素（AD）是一种由脂肪细胞分泌的脂肪因子，与类风湿关节炎（RA）的进行性骨侵蚀密切相关。AD 促进关节破坏的确切机制尚不清楚。骨桥蛋白（OPN）是破骨细胞募集所必需的。我们假设 AD 通过诱导滑膜组织中 OPN 的表达而加重骨侵蚀。本研究旨在评估 AD 在 RA 中的新作用。

方法

采用酶联免疫吸附试验（ELISA）检测 38 例 RA 患者、40 例骨关节炎（OA）患者和 20 例健康对照者血清 AD 和 OPN 水平。采用双免疫荧光法检测 RA 和 OA 滑膜组织中 AD 和 OPN 的产生。用 AD 预孵育 RA 滑膜成纤维细胞（RASFs）和 OA 滑膜成纤维细胞后，采用实时定量 PCR 和免疫荧光法分别检测 OPN 的 mRNA 和蛋白表达水平。采用 Transwell 迁移实验和共培养系统评估 RAW264.7 破骨细胞前体细胞系的迁移。用 AD 处理胶原诱导性关节炎（CIA）小鼠，并用或不用 OPN 沉默来评估骨破坏和破骨细胞生成，并用免疫组化染色、微计算机断层扫描和抗酒石酸酸性磷酸酶（TRAP）染色进行评估。用双免疫荧光法检测小鼠踝关节组织中 OPN 和整合素 αβ 的表达水平。

结果

我们的结果表明，AD 和 OPN 的表达水平明显增加，并在 RA 血清中相互关联。AD 分布与 RA 滑膜组织中的 OPN 分布一致。AD 刺激 RASFs 以剂量依赖性方式增加 OPN 的产生。AD 处理的 RASFs 促进 RAW264.7 细胞迁移，而特异性 OPN 抗体可阻断该作用。用慢病毒-OPN 短发夹 RNA 沉默 OPN 可减少 AD 处理的 CIA 小鼠中 TRAP 阳性破骨细胞的数量和骨侵蚀程度。当与整合素 αβ 结合时，OPN 作为 AD 和破骨细胞的介质发挥作用。