Discipline of Pathology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, North Terrace, Level 3 Medical School North Building, Frome Road, Adelaide, SA 5005, Australia.
Rheumatol Int. 2012 Feb;32(2):535-40. doi: 10.1007/s00296-010-1733-6. Epub 2011 Jan 23.
The objective of the study was to determine whether cartilage expression of the bone regulating molecules receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) varies between the different grades of osteoarthritis (OA). Cartilage samples were obtained from 30 patients undergoing total hip/knee replacement surgery. Tissue sections were stained with Safranin O and graded. Immunohistochemical staining was then performed, and levels of RANKL and OPG expression were assessed using a semi-quantitative scoring system. In addition, levels of mRNA encoding for RANKL and OPG were determined by a relative real-time reverse transcription-polymerase chain reaction technique. We found that expression of RANKL protein, mRNA expression, and the ratio of RANKL: OPG mRNA was greater in grade 2 cartilage in comparison with grade 0 cartilage (P < 0.05). Increased RANKL staining in the grade 2 cartilage was predominantly in the peri-cellular region of the middle and deep zones as well as in the matrix of the superficial zone. OPG mRNA expression was greater in grade 3 cartilage in comparison with grade 0 cartilage (P < 0.05). Cartilage and subchondral bone are in close proximity and soluble proteins produced in the cartilage are likely to move from one compartment to the other. Our finding of increased expression of RANKL in grade 2 OA cartilage might explain the increase in bone turnover reported in the subchondral bone of OA patients. The changes seen in the different grades of tissue may also indicate that this effect occurs during the early stages of OA development.
本研究旨在确定骨调节分子核因子κB 配体（RANKL）和骨保护素（OPG）在不同程度的骨关节炎（OA）之间的软骨表达是否存在差异。从 30 例接受全髋关节/膝关节置换手术的患者中获取软骨样本。用番红 O 染色并对组织切片进行分级。然后进行免疫组织化学染色，使用半定量评分系统评估 RANKL 和 OPG 表达水平。此外，通过相对实时逆转录-聚合酶链反应技术确定编码 RANKL 和 OPG 的 mRNA 水平。我们发现，与 0 级软骨相比，2 级软骨的 RANKL 蛋白表达、mRNA 表达和 RANKL:OPG mRNA 比值更高（P < 0.05）。2 级软骨中 RANKL 染色增加主要位于中深层的细胞周围区域以及浅层的基质中。与 0 级软骨相比，3 级软骨的 OPG mRNA 表达更高（P < 0.05）。软骨和软骨下骨紧密相邻，软骨中产生的可溶性蛋白可能从一个隔室转移到另一个隔室。我们在 2 级 OA 软骨中发现 RANKL 表达增加，这可能解释了 OA 患者软骨下骨中骨转换增加的原因。不同组织分级中观察到的变化也可能表明这种效应发生在 OA 发展的早期阶段。
