Du Sa, Liang Chao, Sun Yujie, Ma Bowen, Gao Wenmo, Geng Wei
Department of Dental Implant Center, Beijing Stomatological Hospital, School of Stomatology, Capital Medical University, Beijing, China.
Front Pharmacol. 2021 Dec 14;12:752734. doi: 10.3389/fphar.2021.752734. eCollection 2021.
Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease with a complex and multifactorial etiology. An increased intrajoint pressure or weakened penetration can exacerbate the hypoxic state of the condylar cartilage microenvironment. Our group previously simulated the hypoxic environment of TMJOA . Low-intensity pulsed ultrasound (LIPUS) stimulation attenuates chondrocyte matrix degradation a hypoxia-inducible factor (HIF) pathway-associated mechanism, but the mode of action of LIPUS is currently poorly understood. Moreover, most recent studies investigated the pathological mechanisms of osteoarthritis, but no biomarkers have been established for assessing the therapeutic effect of LIPUS on TMJOA with high specificity, which results in a lack of guidance regarding clinical application. Here, tandem mass tag (TMT)-based quantitative proteomic technology was used to comprehensively screen the molecular targets and pathways affected by the action of LIPUS on chondrocytes under hypoxic conditions. A bioinformatic analysis identified 902 and 131 differentially expressed proteins (DEPs) in the <1% oxygen treatment group compared with the control group and in the <1% oxygen + LIPUS stimulation group compared with the <1% oxygen treatment group, respectively. The DEPs were analyzed by gene ontology (GO), KEGG pathway and protein-protein interaction (PPI) network analyses. By acting on extracellular matrix (ECM)-associated proteins, LIPUS increases energy production and activates the FAK signaling pathway to regulate cell biological behaviors. DEPs of interest were selected to verify the reliability of the proteomic results. In addition, this experiment demonstrated that LIPUS could upregulate chondrogenic factors (such as Sox9, Collagen Ⅱ and Aggrecan) and increase the mucin sulfate content. Moreover, LIPUS reduced the hydrolytic degradation of the ECM by decreasing the MMP3/TIMP1 ratio and vascularization by downregulating VEGF. Interestingly, LIPUS improved the migration ability of chondrocytes. In summary, LIPUS can regulate complex biological processes in chondrocytes under hypoxic conditions and alter the expression of many functional proteins, which results in reductions in hypoxia-induced chondrocyte damage. ECM proteins such as thrombospondin4, thrombospondin1, IL1RL1, and tissue inhibitors of metalloproteinase 1 play a central role and can be used as specific biomarkers determining the efficacy of LIPUS and viable clinical therapeutic targets of TMJOA.
颞下颌关节骨关节炎（TMJOA）是一种病因复杂且多因素的退行性疾病。关节内压力升高或渗透减弱会加剧髁突软骨微环境的缺氧状态。我们团队之前模拟了TMJOA的缺氧环境。低强度脉冲超声（LIPUS）刺激通过一种与缺氧诱导因子（HIF）途径相关的机制减轻软骨细胞基质降解，但目前对LIPUS的作用模式了解甚少。此外，最近的大多数研究都在探究骨关节炎的病理机制，但尚未建立具有高特异性的生物标志物来评估LIPUS对TMJOA的治疗效果，这导致在临床应用方面缺乏指导。在此，基于串联质谱标签（TMT）的定量蛋白质组学技术被用于全面筛选在缺氧条件下LIPUS作用于软骨细胞所影响的分子靶点和途径。生物信息学分析分别在1%氧气处理组与对照组相比以及1%氧气 + LIPUS刺激组与1%氧气处理组相比中鉴定出902个和131个差异表达蛋白（DEP）。通过基因本体（GO）、KEGG途径和蛋白质 - 蛋白质相互作用（PPI）网络分析对这些DEP进行分析。通过作用于细胞外基质（ECM）相关蛋白，LIPUS增加能量产生并激活FAK信号通路以调节细胞生物学行为。选择感兴趣的DEP来验证蛋白质组学结果的可靠性。此外，本实验表明LIPUS可上调软骨形成因子（如Sox9、胶原蛋白Ⅱ和聚集蛋白聚糖）并增加硫酸粘蛋白含量。此外，LIPUS通过降低MMP3/TIMP1比值减少ECM的水解降解，并通过下调VEGF减少血管生成。有趣的是，LIPUS提高了软骨细胞的迁移能力。总之，LIPUS可在缺氧条件下调节软骨细胞中的复杂生物学过程并改变许多功能蛋白的表达，从而减少缺氧诱导的软骨细胞损伤。血小板反应蛋白4、血小板反应蛋白1、IL1RL1和金属蛋白酶组织抑制剂1等ECM蛋白起着核心作用，可作为确定LIPUS疗效的特异性生物标志物和TMJOA可行的临床治疗靶点。
