Ludwig Ralf J, Hardt Katja, Hatting Max, Bistrian Roxana, Diehl Sandra, Radeke Heinfried H, Podda Maurizio, Schön Michael P, Kaufmann Roland, Henschler Reinhard, Pfeilschifter Josef M, Santoso Sentot, Boehncke Wolf-Henning
Department of Dermatology, Clinic of the J.W. Goethe University, Frankfurt am Main, Germany.
Immunology. 2009 Oct;128(2):196-205. doi: 10.1111/j.1365-2567.2009.03100.x.
Junctional adhesion molecule-A (JAM-A), JAM-B and JAM-C have been implicated in leucocyte transmigration. As JAM-B binds to very late activation antigen (VLA)-4, a leucocyte integrin that contributes to rolling and firm adhesion of lymphocytes to endothelial cells through binding to vascular cell adhesion molecule (VCAM)-1, we hypothesized that JAM-B is also involved in leucocyte rolling and firm adhesion. To test this hypothesis, intravital microscopy of murine skin microvasculature was performed. Rolling interactions of murine leucocytes were significantly affected by blockade of JAM-B [which reduced rolling interactions from 9.1 +/- 2.6% to 3.2 +/- 1.2% (mean +/- standard deviation)]. To identify putative ligands, T lymphocytes were perfused over JAM-B-coated slides in a dynamic flow chamber system. JAM-B-dependent rolling and sticking interactions were observed at low shear stress [0.3 dyn/cm(2): 220 +/- 71 (mean +/- standard deviation) versus 165 +/- 88 rolling (P < 0.001; Mann-Whitney rank sum test) and 2.6 +/- 1.3 versus 1.0 +/- 0.7 sticking cells/mm(2)/min (P = 0.026; Mann-Whitney rank sum test) on JAM-B- compared with baseline], but not at higher shear forces (1.0 dyn/cm(2)). As demonstrated by antibody blocking experiments, JAM-B-mediated rolling and sticking of T lymphocytes was dependent on alpha4 and beta1 integrin, but not JAM-C expression. To investigate whether JAM-B-mediated leucocyte-endothelium interactions are involved in a disease-relevant in vivo model, adoptive transfer experiments in 2,4,-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity reactions were performed in mice in the absence or in the presence of a function-blocking JAM-B antibody. In this model, JAM-B blockade during the sensitization phase impaired the generation of the immune response to DNFB, which was assessed as the increase in ear swelling in untreated, DNFB-challenged mice, by close to 40% [P = 0.037; analysis of variance (anova)]. Overall, JAM-B appears to contribute to leucocyte extravasation by facilitating not only transmigration but also rolling and adhesion.
连接黏附分子A（JAM-A）、JAM-B和JAM-C与白细胞迁移有关。由于JAM-B与极晚期活化抗原（VLA）-4结合，VLA-4是一种白细胞整合素，通过与血管细胞黏附分子（VCAM）-1结合，有助于淋巴细胞与内皮细胞的滚动和牢固黏附，我们推测JAM-B也参与白细胞的滚动和牢固黏附。为了验证这一假设，对小鼠皮肤微血管进行了活体显微镜检查。JAM-B的阻断显著影响了小鼠白细胞的滚动相互作用[滚动相互作用从9.1±2.6%降至3.2±1.2%（平均值±标准差）]。为了确定假定的配体，在动态流动腔系统中，将T淋巴细胞灌注在包被有JAM-B的载玻片上。在低剪切应力下[0.3达因/平方厘米：220±71（平均值±标准差），而滚动为165±88（P<0.001；曼-惠特尼秩和检验），JAM-B上的黏附细胞为2.6±1.3，而基线时为1.0±0.7（P=0.026；曼-惠特尼秩和检验）]观察到了JAM-B依赖性的滚动和黏附相互作用，但在较高剪切力（1.0达因/平方厘米）下未观察到。抗体阻断实验表明，JAM-B介导的T淋巴细胞滚动和黏附依赖于α4和β1整合素，但不依赖于JAM-C的表达。为了研究JAM-B介导的白细胞-内皮细胞相互作用是否参与了与疾病相关的体内模型，在存在或不存在功能阻断性JAM-B抗体的情况下，对小鼠进行了2,4-二硝基氟苯（DNFB）诱导的接触性超敏反应的过继转移实验。在这个模型中，可以通过未处理的、经DNFB激发的小鼠耳部肿胀的增加来评估免疫反应的产生，在致敏阶段阻断JAM-B会使免疫反应受损近40%[P=0.037；方差分析（anova）]。总体而言，JAM-B似乎不仅通过促进迁移，还通过促进滚动和黏附来促进白细胞外渗。
