NOVEL ANGIOGENIC CYTOKINE INDUCED ENDOTHELIAL ANTIGEN

血管生成或新血管生长在动脉粥样硬化、肿瘤生长和类风湿关节炎(RA)等疾病中是一个重要的过程。我们以前已经证明，白介素8是一种强大的巨噬细胞衍生的血管生成介质(Koch等人，Science 258：1798,1992)。我们还发现，可溶性内皮细胞黏附分子、可溶性E-选择素(sE-选择素)和可溶性血管细胞黏附分子-1在诱导血管生成中的作用类似于细胞因子(Koch，et al，Natural 376：517,1995)。我们证明了Se-选择素介导血管生成的机制是通过其内皮配体sialyl-Lewis(sialyl-lex)实现的。目前，我们主要研究一种新的内皮(EC)分子4A11，它是用本实验室研制的单抗4A11检测到的。这种抗原实际上是内皮特异性的，也是内皮选择性的，主要在正常滑膜、淋巴组织、胸腺和皮肤的EC上表达，提示可能在这些区域的细胞归巢中发挥作用。4A11抗原在体外是细胞因子诱导的，在人类RA滑膜组织受影响的关节和人类毒藤接触性皮炎模型中上调。此外，用单抗4A11检测到的抗原存在于Lewis-6(Ley)和H-5-2(H-2)中。LEY属于新的碳水化合物家族，其中包括唾液酸-Lex，这是一种Se-选择素配体，Se-选择素通过它介导血管生成。我们最近发现，可溶性4A11抗原介导了血管生成。本研究的目的是确定4A11抗原介导血管生成和参与细胞黏附的机制，以及4A11抗原在疾病中的作用。我们建议使用体外和体内血管生成试验来证实4A11抗原的血管生成活性。我们将确定4A11抗原是否介导EC黏附分子和EC或白细胞黏附的上调。我们将描述这种抗原在疾病中的作用。由于4A11抗原的合成是由岩藻糖基转移酶调节的，我们将检查在岩藻糖基转移酶缺陷的“基因敲除”小鼠中是否出现血管生成缺陷。我们将确定与亲代对照相比，这些小鼠的角膜血管生成、伤口修复、其他血管生成介质的表达是否减少，或血管生成关节炎反应是否减少。这些研究应该会拓宽我们对这种新型血管生成介质作用模式的理解，它可能会增强我们在以持续性新生血管为特征的情况下抑制血管生成的能力。

Angiogenesis, or new blood vessel growth, is an important process in conditions such as atherosclerosis, tumor growth, and rheumatoid arthritis (RA). We have shown previously that interleukin-8 is a potent macrophage-derived mediator of angiogenesis (Koch, et al, Science 258: 1798, 1992). We have also shown that soluble endothelial cell adhesion molecules soluble E-selectin (sE-selectin), and soluble vascular cell adhesion molecule-1 can function in a manner similar to cytokines in inducing angiogenesis (Koch, et al, Nature 376:517, 1995). We demonstrated that the mechanism by which sE-selectin mediates angiogenesis is via its endothelial ligand sialyl-Lewis (sialyl-Lex). Currently, we focus on a novel endothelial (EC) molecule, 4A11, detected by monoclonal antibody (mAb) 4A11 produced in our laboratory. This antigen is virtually endothelial-specific, as well as endothelial selective, being expressed mainly on EC in normal synovium, lymphoid tissues, thymus, and skin, suggesting a possible role in cell homing to these areas. The 4A11 antigen is cytokine-inducible in vitro and is upregulated in human RA synovial tissue lining affected joints and in a human poison ivy model of contact dermatitis. Moreover, the antigen detected by monoclonal antibody 4A11 is contained in both Lewisy-6 (Ley) and H-5-2 (H-2). Ley is within the new family of carbohydrates which includes sialyl-Lex, the sE-selectin ligand through which the sE- selectin mediates angiogenesis. We have recently found that the soluble 4A11 antigen mediates angiogenesis. The aim of this proposal is to determine the mechanism by which the 4A11 antigen mediates angiogenesis and participates in cell adhesion, and the role of the 4A11 antigen in disease. We propose to confirm the angiogenic activity of the 4A11 antigen using in vitro and in vivo angiogenesis assays. We will determine whether the 4A11 antigen mediates upregulation of EC adhesion molecules and EC or leukocyte adhesion. We will characterize the role of this antigen in disease. Since the synthesis of the 4A11 antigen is regulated by fucosyltransferases, we will examine whether a defect in angiogenesis occurs in "knockout" mice deficient in fucosyltransferase. We will determine whether these mice have decreased corneal angiogenesis, wound repair, expression of other angiogenic mediators, or angiogenic arthritic responses compared to parental controls. These studies should broaden our understanding of the mode of action of this novel angiogenic mediator which may increase our ability to curb angiogenesis in conditions characterized by persistent neovascularization.