Analysis of the mechanism of abnormal B cell activation characteristic of various autoimmune diseases

多种自身免疫性疾病B细胞异常活化特征机制分析

• 批准号: 06670500
• 负责人: HIROHATA Shunsei
• 金额: $ 1.41万
• 依托单位: Teikyo University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06670500/
• 关键词: B cells; cell cycle; IL-2; IL-10; cyclin A; mRNA; apoptosis; mizoribine; Staphylococcus aureus; GMP; T細胞; サイクリン; 免疫グロブリン; 免疫抑制剤

The current studies were undertaken to explore the mechanisms of abnormal B cell activation in autoimmune disease. For this purpose, special attention was paid to the regulation of cell cycle progression of human B cells and the influences of cytokines, including IL-10 and IL-2. First, we examined in detail the regulation of the survival of human peripheral blood B cells by IL-10 and its relevance to the Ig production. Highly purified B cells from healthy adult individuals were cultured with Staphylococcus aureus Cowan I (SA) in the presence or absense of IL-10. When IL-10 was present during the initial activation of B cells with SA,IL-10 faciliated the apoptosis of SA activated B cells, thus resulting in the very modest IgM production. IL-2 prevented the IL-10-mediated progression of the apoptosis of SA activated B cells during the initial activation, and thus restored the further differentiation of these B cells into Ig secreting cells. By contrast, IL-10 rather rescued SA activated … More B cells from apoptosis and thus supported the differentiation of these B cells without any influences of IL-2, when it was added after 72h of cultures. These results indicate that the effects of IL-10 are different depending on the state of activation of B cells after ligation of antigen receptors.Recent clinical trials have demonstrated the efficacy of mizoribine in rheumatoid arthritis and lupus nephritis, in which abnormalities of B cell functions are also involved. We therefore examined the effects of mizoribine on the in vitro function of human B cells. IgM production was induced from highly purified B cells obtained from healthy donors by stimulation with Staphylococcus aureus Cown I (SA) plus IL-2. Mizoribine suppressed the production of IgM at its pharmacologically attainable concentrations (0.3-3mug/ml) in a dose-dependent manner. Time kinetics study revealed that mizoribine was requied to be present within the first 120 hr after the initiation of cultures to exert its suppressive effects on B cell responses. Cell cycle analysis by staining with propidium iodide disclosed that mizoribine suppressed the G1-S transition of activated B cells. The suppressive effects of mizoribine on the IgM production was not reversed by repletion of GTP with supplementation of GMP.Althogh mizoribine did not suppress the expression of CD25 and cdc2 kinase in B cells, mizoribine markedly suppressed the expression of cyclin A in SA activated B cells at the mRNA levels. These results indicate that mizoribine suppresses the production of IgM by directly inhibiting B clls with out interfering with the initial phase of activation. Moreover, the data demonstrate that mizoribine inhibits the G1-S transition of activated B cells in the cell cycle by suppressing the expression of cyclin A by a mechanism distinct from guanine ribonucleotide depletion. Less

本研究旨在探讨自身免疫性疾病中B细胞异常活化的机制。为此，人们特别关注人B细胞细胞周期进程的调节以及细胞因子（包括IL-10和IL-2）的影响。首先，我们详细研究了IL-10对人外周血B细胞存活的调节及其与IG产生的相关性。将来自健康成人个体的高度纯化的B细胞与金黄色葡萄球菌科万I（SA）在存在或不存在IL-10的情况下培养。当IL-10存在于SA初始激活B细胞期间时，IL-10促进SA激活的B细胞的凋亡，从而导致非常适度的IgM产生。IL-2阻止了SA激活的B细胞在初始激活过程中IL-10介导的凋亡进程，从而恢复了这些B细胞向分泌IG的细胞的进一步分化。相比之下，IL-10反而挽救了SA激活， ...更多信息 当在培养72小时后加入IL-2时，可抑制B细胞凋亡，从而支持这些B细胞的分化，而不受IL-2的任何影响。这些结果表明，IL-10的作用根据抗原受体连接后B细胞的活化状态而不同，最近的临床试验证明咪唑立宾对类风湿性关节炎和狼疮性肾炎有效，其中也涉及B细胞功能异常。因此，我们研究了咪唑立宾对人B细胞体外功能的影响。通过用金黄色葡萄球菌Cown I（SA）加IL-2刺激从健康供体获得的高度纯化的B细胞诱导IgM产生。咪唑立宾在其可达到的浓度（0.3- 3 μ g/ml）以剂量依赖的方式抑制IgM的产生。时间动力学研究表明咪唑立宾需要在培养开始后的前120小时内存在才能发挥其对B细胞反应的抑制作用。用碘化丙啶染色的细胞周期分析揭示咪唑立宾抑制活化的B细胞的G1-S转换。咪唑立宾对SA激活的B细胞中CD 25和cdc 2激酶的表达无明显抑制作用，但对SA激活的B细胞中cyclin A的表达有明显抑制作用。这些结果表明咪唑立宾通过直接抑制B cls而不干扰活化的初始阶段来抑制IgM的产生。此外，数据表明咪唑立宾通过与鸟嘌呤核糖核苷酸消耗不同的机制抑制细胞周期中细胞周期蛋白A的表达来抑制活化的B细胞的G1-S转换。少

项目成果

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