Laboratory of Cell Biology, Department of Orthopaedic Surgery, University Hospital of Tübingen, Tübingen, Germany.
Medical Faculty of the University of Tübingen, Tübingen, Germany.
J Orthop Res. 2020 Oct;38(10):2170-2180. doi: 10.1002/jor.24699. Epub 2020 Apr 25.
During osteoarthritis, chondrocytes change their spatial arrangement from single to double strings, then to small and big clusters. This change in pattern has recently been established as an image-based biomarker for osteoarthritis. The pericellular matrix (PCM) appears to degrade together alongside cellular reorganization. The aim of this study was to characterize this PCM-degradation based on different cellular patterns. We additionally wanted to identify the earliest time point of PCM-breakdown in this physiopathological model. To this end, cartilage samples were selected according to their predominant cellular pattern. Qualitative analysis of PCM degradation was performed immunohistochemically by analysing five main PCM components: collagen type VI, perlecan, collagen type III, biglycan, and fibrillin-1 (n = 6 patients). Their protein content was quantified by enzyme-linked immunosorbent assay (127 patients). Accompanying spatial cellular rearrangement, the PCM is progressively destroyed, with a pericellular signal loss in fluorescence microscopy for collagen type VI, perlecan, and biglycan. This loss in protein signal is accompanied by a reduction in total protein content from single strings to big clusters (P < .001 for collagen type VI, P = .003 for perlecan, and P < .001 for biglycan). As a result of an increase in the number of cells from single strings to big clusters, the amount of protein available per cell also decreases for collagen type III and fibrillin-1, where total protein levels remain constant. Biochemical changes of the PCM and cellular rearrangement are thus highly interconnected hallmarks of osteoarthritis. Interestingly, the earliest point in time for a relevant PCM impairment appears to be at the transition to small clusters.
在骨关节炎中，软骨细胞的空间排列从单个变为双串，然后变为小簇和大簇。这种模式的变化最近被确立为骨关节炎的基于图像的生物标志物。细胞外基质（PCM）似乎与细胞重排一起降解。本研究的目的是根据不同的细胞模式来描述这种 PCM 降解。我们还希望确定在这种生理病理模型中 PCM 破坏的最早时间点。为此，根据主要细胞模式选择软骨样本。通过分析五种主要 PCM 成分（胶原 VI 型、核心蛋白聚糖、胶原 III 型、聚糖和原纤维蛋白 1）对 PCM 降解进行免疫组织化学定性分析（n=6 例患者）。通过酶联免疫吸附试验（127 例患者）定量分析其蛋白含量。伴随着空间细胞重排，PCM 逐渐被破坏，胶原 VI 型、核心蛋白聚糖和聚糖的荧光显微镜下出现细胞周信号丢失。这种蛋白信号的丢失伴随着从小簇到大簇的总蛋白含量减少（胶原 VI 型 P<0.001，核心蛋白聚糖 P=0.003，聚糖 P<0.001）。由于从小串到大簇的细胞数量增加，胶原 III 型和原纤维蛋白 1 的每个细胞的蛋白含量也减少，而总蛋白水平保持不变。因此，PCM 的生化变化和细胞重排是骨关节炎的高度相互关联的特征。有趣的是，PCM 相关损伤的最早时间点似乎是从小簇向大簇转变的过渡时期。
