Department of Physiology, National University of Singapore, Singapore.
Mol Immunol. 2010 May;47(9):1839-47. doi: 10.1016/j.molimm.2009.11.010. Epub 2010 Mar 26.
Expression of CD137, a member of the tumor necrosis factor receptor family, is inducible on vascular endothelial cells by proinflammatory stimuli. Its ligand is expressed as a transmembrane protein on the surface of monocytes, and transmits activating signals into monocytes (reverse signaling) inducing monocyte migration. These findings led to the hypothesis that CD137 expression on activated endothelial cells facilitates recruitment of monocytes into inflammatory tissues including atherosclerotic lesions. Data from this study demonstrate that CD137 expression is inducible on endothelial cells by TNF stimulation. Recombinant CD137 protein and CD137 expressed on activated endothelial cells enhance ICAM-1-mediated adhesion of monocytes under defined flow conditions in vitro. CD137 seems not to play a role in tethering of monocytes since this activity is completely E-selectin-dependent. In addition, LFA-1 affinity and clustering on monocytic cells is enhanced by CD137. In summary, CD137 expression is induced on vascular endothelial cells by proinflammatory mediators and strengthens ICAM-1 and LFA-1-mediated adhesion of monocytes. These data support a role for CD137 in the recruitment of monocytes to inflammatory tissues.
CD137 表达，肿瘤坏死因子受体家族的一个成员，可被促炎刺激诱导血管内皮细胞表达。其配体作为单核细胞表面的跨膜蛋白表达，并将激活信号传递到单核细胞（反向信号）诱导单核细胞迁移。这些发现导致了这样的假设，即在激活的内皮细胞上表达的 CD137 有助于将单核细胞募集到包括动脉粥样硬化病变在内的炎症组织中。本研究的数据表明，TNF 刺激可诱导内皮细胞表达 CD137。重组 CD137 蛋白和激活的内皮细胞上表达的 CD137 增强了在体外定义的流动条件下 ICAM-1 介导的单核细胞黏附。CD137 似乎在单核细胞的拴系中不起作用，因为这种活性完全依赖于 E-选择素。此外，CD137 增强了单核细胞上 LFA-1 的亲和力和聚集。总之，促炎介质可诱导血管内皮细胞表达 CD137，并增强 ICAM-1 和 LFA-1 介导的单核细胞黏附。这些数据支持 CD137 在单核细胞募集到炎症组织中的作用。
