Department of Rheumatism, Beijing Luhe Hospital, Capital Medical University, Beijing, China.
Eur Rev Med Pharmacol Sci. 2018 Apr;22(7):2126-2133. doi: 10.26355/eurrev_201804_14746.
Rheumatoid Arthritis (RA) is a chronic systemic autoimmune disease, whereas its cause still remains elusive. Typical pathological manifestations of RA include persistent synovitis and bone degeneration in the surrounding joints. Although the incidence of RA is high in population, currently there have been no effective cures for it. The purpose of this study is to investigate the therapeutic effects and main mechanism of IKKε (inhibitor of nuclear factor kappa-B kinase ε) in collagen II induced- Rheumatoid Arthritis (CIA) mice model.
IKKε-/- and wild-type (WT) littermate control mice were intraperitoneally injected with 5 mg/kg collagen II monoclonal antibody cocktail (Cab) for 5 days. After that, the nociception threshold and clinical rheumatoid arthritis articular damage score of mice were evaluated. After 5 days-CAb treatment, serum levels of a series of inflammatory cytokines including interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α) and interferon (IFN) were detected with enzyme-linked immunosorbent assay (ELISA) in both groups. Besides, Real-time reverse transcription polymerase chain reaction (Real-time RT-PCR) was used to evaluate the expression of these inflammatory cytokines in plantar tissues. In addition, Western blot was performed to investigate the protein levels of NF-κB (nuclear factor kappa-light-chain-enhancer of activated B) signaling pathway. Moreover, WT mice receiving CAb were further applied with or without IKK inhibitor amlexanox (25 mg/kg) to investigate the expression of the above-mentioned inflammatory cytokines.
Our work showed that IKKε-/- mice with CIA displayed less nociception and suppressed inflammatory response than WT mice. Meanwhile, the clinical rheumatoid arthritis articular damage scores were significantly decreased in IKKε-/- mice. The levels of TNF-α, IL-1β, IL-6 in serum and plantar tissues in IKKε-/- mice were significantly lower than those in WT mice. Besides, NF-κB expression in IKKε-/- mice was significantly decreased. Similarly, the same phenotype was observed in WT mice administrated with IKKε inhibitor amlexanox as that of IKKε-/- mice, indicating that inflammatory and nociception responses were remarkably decreased than those of the negative controls.
IKKε plays an important role in promoting nociception and inflammatory response in CIA. Our research demonstrated that knockout of IKKε may serve as a new direction for clinical prevention and treatment of rheumatoid arthritis. IKKε inhibitor amlexanox may become a new drug for the treatment of rheumatoid arthritis.
类风湿关节炎（RA）是一种慢性系统性自身免疫性疾病，其病因仍不清楚。RA 的典型病理表现包括周围关节持续的滑膜炎和骨退化。尽管 RA 在人群中的发病率很高，但目前尚无有效的治疗方法。本研究旨在探讨 IKKε（核因子 kappa-B 激酶 ε 抑制剂）在胶原 II 诱导的类风湿关节炎（CIA）小鼠模型中的治疗作用及其主要机制。
采用腹腔注射 5mg/kg 胶原 II 单克隆抗体鸡尾酒（Cab）的方法对 IKKε-/-和野生型（WT）同窝对照小鼠进行 5 天处理。然后，评估小鼠的痛觉阈值和临床类风湿关节炎关节损伤评分。在 5 天-CAb 处理后，用酶联免疫吸附试验（ELISA）检测两组血清中一系列炎症细胞因子的水平，包括白细胞介素-6（IL-6）、白细胞介素-1β（IL-1β）、肿瘤坏死因子-α（TNF-α）和干扰素（IFN）。此外，采用实时逆转录聚合酶链反应（Real-time RT-PCR）检测足底组织中这些炎症细胞因子的表达。此外，还进行了 Western blot 以研究 NF-κB（核因子 kappa-轻链增强子的激活 B）信号通路的蛋白水平。此外，用 IKK 抑制剂 amlexanox（25mg/kg）进一步处理接受 CAb 的 WT 小鼠，以研究上述炎症细胞因子的表达。
我们的工作表明，CIA 小鼠的 IKKε-/-小鼠表现出较低的痛觉和抑制炎症反应，而 WT 小鼠则表现出较高的痛觉和炎症反应。同时，IKKε-/-小鼠的临床类风湿关节炎关节损伤评分明显低于 WT 小鼠。IKKε-/-小鼠血清和足底组织中 TNF-α、IL-1β、IL-6 水平明显低于 WT 小鼠。此外，IKKε-/-小鼠中 NF-κB 的表达明显降低。同样，在给予 IKKε 抑制剂 amlexanox 的 WT 小鼠中也观察到与 IKKε-/-小鼠相似的表型，表明炎症和痛觉反应明显低于阴性对照。
IKKε 在 CIA 中促进痛觉和炎症反应中起重要作用。我们的研究表明，IKKε 敲除可能成为类风湿关节炎临床预防和治疗的新方向。IKKε 抑制剂 amlexanox 可能成为治疗类风湿关节炎的新药。
