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.

中文翻译：

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创伤后骨关节炎的人骨软骨模型中的组织分解代谢和供体特异性地塞米松反应


创伤后骨关节炎 (PTOA) 目前尚无临床预后生物标志物或疾病缓解药物，但存在诸如地塞米松 (Dex) 等有希望的候选药物。研究和治疗这种疾病的许多挑战源于组织相互作用，这使得对药物作用的理解变得复杂。我们提出了 PTOA 的离体人类骨软骨模型，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。人类骨软骨外植体取自人类捐赠者（2 名女性，5 名男性，年龄 23-70 岁）的正常（柯林斯 0-1 级）踝距小关节。预平衡后，用单次冲击机械损伤和 TNF-α、IL-6 和 sIL-6R ± 100 nM Dex 处理骨软骨外植体 21 天，每 2-3 天收集一次培养基。使用线性混合效应模型测定软骨细胞活力、组织 DNA 含量和糖胺聚糖 (sGAG) 损失百分比，并与未处理的对照进行比较。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着性。对蛋白质组数据进行 sGAG 损失和 sGAG 损失的 Dex 衰减的偏最小二乘回归分析。损伤和细胞因子治疗导致基质成分、蛋白酶、促炎因子和细胞内蛋白的释放增加，而组织丢失细胞内代谢蛋白，添加Dex可以减轻这种情况。 Dex 维持了软骨细胞活力，并将由损伤和细胞因子治疗引起的 sGAG 损失减少了 2/3，并且 sGAG 衰减效应存在供体特异性差异。骨代谢的生物标志物具有混合效应，疾病和 Dex 治疗均抑制 II 型胶原蛋白合成 2 至 5 倍。鉴定出与 sGAG 损失增加相关的半胰蛋白酶肽。促炎体液蛋白和载脂蛋白与较低的 Dex 反应相关。在骨软骨 PTOA 模型中添加 Dex 可以减少损伤和细胞因子治疗对软骨组织造成的分解代谢影响。这项研究提出了早期 PTOA 进展的潜在肽生物标志物和 Dex 功效，可以帮助识别和治疗有 PTOA 风险的患者。