Khandoga Andrej, Hanschen Marc, Kessler Julia S, Krombach Fritz
Institute for Surgical Research, Ludwig-Maximilians-University of Munich, Germany.
Hepatology. 2006 Feb;43(2):306-15. doi: 10.1002/hep.21017.
The mechanisms by which T cells contribute to the hepatic inflammation during antigen-independent ischemia/reperfusion (I/R) are not fully understood. We analyzed the recruitment of T cells in the postischemic hepatic microcirculation in vivo and tested the hypothesis that T cells interact with platelets and activate sinusoidal endothelial cells, resulting in microvascular dysfunction followed by tissue injury. Using intravital videofluorescence microscopy, we show in mice that warm hepatic I/R (90/30-140 min) induces accumulation and transendothelial migration of CD4+, but not CD8+ T cells in sinusoids during early reperfusion. Simultaneous visualization of fluorescence-labeled CD4+ T cells and platelets showed that approximately 30% of all accumulated CD4+ T cells were colocalized with platelets, suggesting an interaction between both cell types. Although interactions of CD4+/CD40L-/- T cells with CD40L-/- platelets in wild-type mice were slightly reduced, they were almost absent if CD4+ T cells and platelets were from CD62P-/- mice. CD4 deficiency as well as CD40-CD40L and CD28-B7 disruption attenuated postischemic platelet adherence in the same manner as platelet inactivation with a glycoprotein IIb/IIIa antagonist and reduced neutrophil transmigration, sinusoidal perfusion failure, and transaminase activities. Treatment with an MHC class II antibody, however, did not affect I/R injury. In conclusion, we describe the type, kinetic, and microvascular localization of T cell recruitment in the postischemic liver. CD4+ T cells interact with platelets in postischemic sinusoids, and this interaction is mediated by platelet CD62P. CD4+ T cells activate endothelium, increase I/R-induced platelet adherence and neutrophil migration via CD40-CD40L and CD28-B7-dependent pathways, and aggravate microvascular/hepatocellular injury.
T细胞在抗原非依赖性缺血/再灌注（I/R）期间导致肝脏炎症的机制尚未完全阐明。我们分析了体内缺血后肝脏微循环中T细胞的募集情况，并验证了T细胞与血小板相互作用并激活窦状内皮细胞，导致微血管功能障碍继而引发组织损伤这一假说。通过活体视频荧光显微镜检查，我们发现小鼠肝脏在热缺血90/30 - 140分钟后再灌注早期，诱导CD4⁺而非CD8⁺T细胞在肝血窦内积聚并发生跨内皮迁移。荧光标记的CD4⁺T细胞与血小板的同步可视化显示，所有积聚的CD4⁺T细胞中约30%与血小板共定位，提示这两种细胞类型之间存在相互作用。尽管野生型小鼠中CD4⁺/CD40L⁻/⁻T细胞与CD40L⁻/⁻血小板之间的相互作用略有减少，但如果CD4⁺T细胞和血小板均来自CD62P⁻/⁻小鼠，则几乎不存在这种相互作用。CD4缺陷以及CD40 - CD40L和CD28 - B7阻断与用糖蛋白IIb/IIIa拮抗剂使血小板失活一样，以相同方式减弱缺血后血小板黏附，并减少中性粒细胞迁移、肝血窦灌注衰竭及转氨酶活性。然而，用II类主要组织相容性复合体抗体治疗并不影响I/R损伤。总之，我们描述了缺血后肝脏中T细胞募集的类型、动力学及微血管定位。CD4⁺T细胞在缺血后肝血窦中与血小板相互作用，且这种相互作用由血小板CD62P介导。CD4⁺T细胞激活内皮细胞，通过CD40 - CD40L和CD28 - B7依赖性途径增加I/R诱导的血小板黏附和中性粒细胞迁移，并加重微血管/肝细胞损伤。
