Institute of Biochemistry and Molecular Cell Biology, Rheinisch-Westfälisch Technical University (RWTH) Aachen, D-52074 Aachen, Germany;
Department of Pediatrics, Rheinisch-Westfälisch Technical University (RWTH) Aachen, D-52074 Aachen, Germany;
J Immunol. 2014 Jun 1;192(11):5273-84. doi: 10.4049/jimmunol.1302209. Epub 2014 Apr 23.
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with chemokine-like functions that plays a pivotal role in the pathogenesis of inflammatory diseases by promoting leukocyte recruitment. We showed that MIF promotes the atherogenic recruitment of monocytes and T cells through its receptors CXCR2 and CXCR4. Effects of MIF on B cell recruitment have not been addressed. In this study, we tested the involvement of MIF in B cell chemotaxis and studied the underlying mechanism. We show that MIF promotes primary murine B cell chemotaxis in a dose-dependent manner, comparable to the B cell chemokines CXCL13 and CXCL12. Splenic B cells express CXCR4 and the receptor CD74 but not CXCR2. Inhibition of CXCR4 or CD74 or a genetic deficiency of Cd74 in primary B cells fully abrogated MIF-mediated B cell migration, implying cooperative involvement of both receptors. MIF stimulation of B cells resulted in a rapid increase in intracellular Ca(2+) mobilization and F-actin polymerization. Intriguingly, the tyrosine kinase ZAP-70 was activated upon MIF and CXCL12 treatment in a CXCR4- and CD74-dependent manner. Pharmacological inhibition of ZAP-70 resulted in abrogation of primary B cell migration. Functional involvement of ZAP-70 was confirmed by small interfering RNA-mediated knockdown in Ramos B cell migration. Finally, primary B cells from ZAP-70 gene-deficient mice exhibited ablated transmigration in response to MIF or CXCL12. We conclude that MIF promotes the migration of B cells through a ZAP-70-dependent pathway mediated by cooperative engagement of CXCR4 and CD74. The data also suggest that MIF may contribute to B cell recruitment in vivo (e.g., in B cell-related immune disorders).
巨噬细胞移动抑制因子（MIF）是一种前炎性细胞因子，具有趋化因子样功能，通过促进白细胞募集，在炎症性疾病的发病机制中发挥关键作用。我们表明，MIF 通过其受体 CXCR2 和 CXCR4 促进单核细胞和 T 细胞的动脉粥样硬化募集。MIF 对 B 细胞募集的影响尚未得到解决。在这项研究中，我们测试了 MIF 在 B 细胞趋化中的作用，并研究了潜在的机制。我们表明，MIF 以剂量依赖的方式促进原代小鼠 B 细胞趋化，与 B 细胞趋化因子 CXCL13 和 CXCL12 相当。脾 B 细胞表达 CXCR4 和受体 CD74，但不表达 CXCR2。CXCR4 或 CD74 的抑制或原代 B 细胞中 Cd74 的基因缺失完全阻断了 MIF 介导的 B 细胞迁移，这表明两种受体的协同参与。MIF 刺激 B 细胞导致细胞内 Ca(2+)动员和 F-肌动蛋白聚合的快速增加。有趣的是，ZAP-70 酪氨酸激酶在 MIF 和 CXCL12 处理下以 CXCR4 和 CD74 依赖的方式被激活。ZAP-70 的药理学抑制导致原代 B 细胞迁移的阻断。通过小干扰 RNA 介导的 Ramos B 细胞迁移中的 knockdown 证实了 ZAP-70 的功能参与。最后，ZAP-70 基因缺陷型小鼠的原代 B 细胞对 MIF 或 CXCL12 的反应表现出跨迁移的缺失。我们得出结论，MIF 通过协同参与 CXCR4 和 CD74 的 ZAP-70 依赖性途径促进 B 细胞的迁移。该数据还表明，MIF 可能有助于体内 B 细胞的募集（例如，在 B 细胞相关免疫疾病中）。
