Department of Pharmaceutical Sciences, Washington State University College of Pharmacy and Pharmaceutical Sciences, Spokane, WA, United States.
Center for Computational Biology and Bioinformatics, Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India.
Front Immunol. 2022 Aug 10;13:928436. doi: 10.3389/fimmu.2022.928436. eCollection 2022.
O-GlcNAcylation is a reversible post-translational modification that regulates numerous cellular processes, including embryonic development as well as immune responses. However, its role in inflammation remains ambiguous. This study was designed to examine the role of O-GlcNAcylation in rheumatoid arthritis (RA) and its regulation using human RA patient-derived synovial fibroblasts (RASFs). The efficacy of penta-O-galloyl-beta-D-glucose (PGG), a potent anti-inflammatory molecule, in regulating inflammatory processes in human RASFs was also evaluated. Human synovial tissues and RASFs exhibited higher expression of O-GlcNAcylation compared to their non-diseased counterparts. Pretreatment of RASFs with Thiamet G, an inhibitor of O-GlcNAcase, markedly increased the O-GlcNAc-modified proteins and concomitantly inhibited the IL-1β-induced IL-6 and IL-8 production in human RASFs Pretreatment of human RASFs with PGG (0.5-10 µM) abrogated IL-1β-induced IL-6 and IL-8 production in a dose-dependent manner. Immunoprecipitation analysis showed that PGG inhibited O-GlcNAcylation of TAB1 to reduce its association with TGF β-activated kinase 1 (TAK1) and its autophosphorylation, an essential signaling step in IL-1β-induced signaling pathways. Molecular docking studies shows that PGG occupies the C174 position, an ATP-binding site in the kinase domain to inhibit TAK1 kinase activity. Oral administration of PGG (25 mg/kg/day) for 10 days from disease onset significantly ameliorated rat adjuvant-induced (AIA) in rats. PGG treatment reduced the phosphorylation of TAK1 in the treated joints compared to AIA joints, which correlated with the reduced disease severity and suppressed levels of serum IL-1β, GM-CSF, TNF-α, and RANKL. These findings suggest O-GlcNAcylation as a potential therapeutic target and provide the rationale for testing PGG or structurally similar molecule for their therapeutic efficacy.
O-GlcNAc ylation 是一种可逆的翻译后修饰，可调节许多细胞过程，包括胚胎发育和免疫反应。然而，它在炎症中的作用尚不清楚。本研究旨在探讨 O-GlcNAc ylation 在类风湿关节炎（RA）中的作用及其在人 RA 患者来源的滑膜成纤维细胞（RASFs）中的调节作用。还评估了 penta-O- 没食子酰基-β-D-葡萄糖（PGG），一种有效的抗炎分子，在调节人 RASFs 中炎症过程的功效。与非疾病对照相比，人滑膜组织和 RASFs 表现出更高的 O-GlcNAc ylation 表达。用 O-GlcNAcase 的抑制剂 Thiamet G 预处理 RASFs 显着增加了 O-GlcNAc 修饰的蛋白质，并同时抑制了人 RASFs 中 IL-1β 诱导的 IL-6 和 IL-8 的产生。用 PGG（0.5-10 μM）预处理人 RASFs 可剂量依赖性地阻断 IL-1β 诱导的 IL-6 和 IL-8 的产生。免疫沉淀分析表明，PGG 抑制 TAB1 的 O-GlcNAc ylation 以减少其与 TGF β 激活激酶 1（TAK1）及其自身磷酸化的结合，这是 IL-1β 诱导的信号通路中的一个重要信号步骤。分子对接研究表明，PGG 占据 C174 位，即激酶结构域中的 ATP 结合位点，以抑制 TAK1 激酶活性。疾病发作后 10 天每天口服给予 PGG（25mg/kg）可显着改善大鼠佐剂诱导的（AIA）大鼠。与 AIA 关节相比，PGG 治疗可降低治疗关节中 TAK1 的磷酸化，这与疾病严重程度降低和血清中 IL-1β、GM-CSF、TNF-α和 RANKL 的水平降低相关。这些发现表明 O-GlcNAc ylation 是一种潜在的治疗靶标，并为测试 PGG 或结构类似物的治疗功效提供了依据。
