Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Rheumatology and Molecular Skeletal Biology, Department of Clinical Sciences Lund, Faculty of Medicine, Lund University, Lund, Sweden.
Arthritis Res Ther. 2022 Jun 10;24(1):137. doi: 10.1186/s13075-022-02828-4.
Post-traumatic osteoarthritis (PTOA) does not currently have clinical prognostic biomarkers or disease-modifying drugs, though promising candidates such as dexamethasone (Dex) exist. Many challenges in studying and treating this disease stem from tissue interactions that complicate understanding of drug effects. We present an ex vivo human osteochondral model of PTOA to investigate disease effects on cartilage and bone homeostasis and discover biomarkers for disease progression and drug efficacy.
Human osteochondral explants were harvested from normal (Collins grade 0-1) ankle talocrural joints of human donors (2 female, 5 male, ages 23-70). After pre-equilibration, osteochondral explants were treated with a single-impact mechanical injury and TNF-α, IL-6, and sIL-6R ± 100 nM Dex for 21 days and media collected every 2-3 days. Chondrocyte viability, tissue DNA content, and glycosaminoglycan (sGAG) percent loss to the media were assayed and compared to untreated controls using a linear mixed effects model. Mass spectrometry analysis was performed for both cartilage tissue and pooled culture medium, and the statistical significance of protein abundance changes was determined with the R package limma and empirical Bayes statistics. Partial least squares regression analyses of sGAG loss and Dex attenuation of sGAG loss against proteomic data were performed.
Injury and cytokine treatment caused an increase in the release of matrix components, proteases, pro-inflammatory factors, and intracellular proteins, while tissue lost intracellular metabolic proteins, which was mitigated with the addition of Dex. Dex maintained chondrocyte viability and reduced sGAG loss caused by injury and cytokine treatment by 2/3 overall, with donor-specific differences in the sGAG attenuation effect. Biomarkers of bone metabolism had mixed effects, and collagen II synthesis was suppressed with both disease and Dex treatment by 2- to 5-fold. Semitryptic peptides associated with increased sGAG loss were identified. Pro-inflammatory humoral proteins and apolipoproteins were associated with lower Dex responses.
Catabolic effects on cartilage tissue caused by injury and cytokine treatment were reduced with the addition of Dex in this osteochondral PTOA model. This study presents potential peptide biomarkers of early PTOA progression and Dex efficacy that can help identify and treat patients at risk of PTOA.
创伤后骨关节炎（PTOA）目前尚无临床预后生物标志物或疾病修饰药物，尽管有地塞米松（Dex）等有前途的候选药物。研究和治疗这种疾病存在许多挑战，这源于使药物作用复杂化的组织相互作用。我们提出了一种体外人骨软骨 PTOA 模型，以研究疾病对软骨和骨稳态的影响，并发现疾病进展和药物疗效的生物标志物。
从人类供体（2 名女性，5 名男性，年龄 23-70 岁）正常（柯林斯分级 0-1）踝关节距骨关节中采集人骨软骨标本。在预平衡后，用单次冲击机械损伤和 TNF-α、IL-6 和 sIL-6R ± 100 nM Dex 处理骨软骨标本 21 天，并每隔 2-3 天收集一次培养基。使用线性混合效应模型比较未处理对照，测定软骨细胞活力、组织 DNA 含量和糖胺聚糖（sGAG）向培养基的百分比损失。对软骨组织和混合培养基进行质谱分析，并使用 R 包 limma 和经验贝叶斯统计确定蛋白质丰度变化的统计显著性。对 sGAG 损失和 Dex 对 sGAG 损失的衰减与蛋白质组学数据进行偏最小二乘回归分析。
损伤和细胞因子处理导致基质成分、蛋白酶、促炎因子和细胞内蛋白的释放增加，而组织失去了细胞内代谢蛋白，Dex 的添加减轻了这种情况。Dex 通过将损伤和细胞因子处理引起的 sGAG 损失总体减少 2/3，同时对供体特异性 Dex 衰减效应存在差异，维持了软骨细胞活力并降低了 sGAG 损失。骨代谢生物标志物的作用混杂，疾病和 Dex 治疗均使 II 型胶原合成抑制 2-5 倍。确定了与 sGAG 损失增加相关的半胱氨酸肽。促炎体液蛋白和载脂蛋白与较低的 Dex 反应相关。
在这种骨软骨 PTOA 模型中，添加 Dex 可减轻损伤和细胞因子处理对软骨组织的分解代谢作用。本研究提出了早期 PTOA 进展和 Dex 疗效的潜在肽生物标志物，有助于识别和治疗 PTOA 风险患者。
