Graesser D, Mahooti S, Haas T, Davis S, Clark R B, Madri J A
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Lab Invest. 1998 Nov;78(11):1445-58.
Previous studies have suggested that surface expression of alpha4 integrin by autoreactive T-cell clones is necessary for the clones to induce experimental autoimmune encephalomyelitis (EAE), a mouse model for human multiple sclerosis. To provide direct evidence for this phenomenon, we have transfected alpha4 integrin into C19alpha4-LO, a myelin basic protein-reactive T-cell clone that does not express alpha4 integrin and does not induce EAE when adoptively transferred into a susceptible mouse strain. Transfection of alpha4 integrin converted this clone to an alpha4 integrin-expressing clone that induced EAE. We then examined potential mechanisms by which alpha4 integrin may facilitate the disease process. C19 T-cell clones adhered equally to a monolayer of microvascular endothelial cells, regardless of level of alpha4 integrin expression. However, in contrast to T-cell clones that do not express alpha4 integrin, T-cell clones that express alpha4 integrin (endogenously or by transfection) transmigrated through an endothelial cell layer and subendothelial matrix at an enhanced rate and adhered to recombinant vascular cell adhesion molecule-1 (rVCAM-1) and the CS1 fragment of fibronectin, and after adhesion to these ligands, a matrix-degrading metalloproteinase (MMP-2) was induced and activated. The clones were also shown to constitutively express the membrane-type matrix metalloproteinase (MT1-MMP), an enzyme that activates MMP-2. GM6001 and UK-221,316, inhibitors of metalloproteinases, reduced alpha4 integrin-mediated transmigration and EAE induction by C19 T-cell clones. In addition, we studied a second EAE-inducing T-cell clone, MM4, which constitutively expresses alpha4 integrin and MMP-2. Engagement of alpha4 integrin on the MM4 clone up-regulated the expression and activation of MMP-2, without changing the expression of MT1-MMP. MMP inhibitors also reduced transmigration of and EAE induction by the MM4 T-cell clone. These studies demonstrate directly that expression of alpha4 integrin by autoreactive T-cell clones is required for adoptive transfer of EAE in this model. We also define a role for alpha4 integrin in the disease process in mediating the induction and coordinate activation of a matrix metalloproteinase (MMP-2), which facilitates T-cell transmigration.
先前的研究表明，自身反应性T细胞克隆表面表达α4整合素是这些克隆诱导实验性自身免疫性脑脊髓炎（EAE，一种人类多发性硬化症的小鼠模型）所必需的。为了为这一现象提供直接证据，我们已将α4整合素转染到C19α4-LO中，C19α4-LO是一种髓鞘碱性蛋白反应性T细胞克隆，不表达α4整合素，当将其过继转移到易感小鼠品系中时不会诱导EAE。α4整合素的转染将该克隆转化为表达α4整合素的克隆，后者可诱导EAE。然后，我们研究了α4整合素可能促进疾病进程的潜在机制。C19 T细胞克隆与微血管内皮细胞单层的黏附程度相同，与α4整合素的表达水平无关。然而，与不表达α4整合素的T细胞克隆不同，表达α4整合素（内源性表达或通过转染表达）的T细胞克隆以更快的速率穿过内皮细胞层和内皮下基质进行迁移，并与重组血管细胞黏附分子-1（rVCAM-1）和纤连蛋白的CS1片段黏附，在与这些配体黏附后，诱导并激活一种基质降解金属蛋白酶（MMP-）。这些克隆还显示组成性表达膜型基质金属蛋白酶（MT1-MMP），一种激活MMP-的酶。金属蛋白酶抑制剂GM6001和UK-221,316可减少α4整合素介导的C19 T细胞克隆的迁移和EAE诱导。此外，我们研究了另一个诱导EAE的T细胞克隆MM4，其组成性表达α4整合素和MMP-。MM4克隆上α4整合素的结合上调了MMP-的表达和激活，而不改变MT1-MMP的表达。MMP抑制剂也减少了MM4 T细胞克隆的迁移和EAE诱导。这些研究直接证明，在该模型中，自身反应性T细胞克隆表达α4整合素是EAE过继转移所必需的。我们还确定了α4整合素在疾病进程中的作用，即介导基质金属蛋白酶（MMP-）的诱导和协同激活，这有助于T细胞迁移。 22
