Beacham D A, Tran L P, Shapiro S S
The Cardeza Foundation for Hematologic Research, Department of Medicine, Jefferson Medical College of Thomas Jefferson University, Philadelphia, PA 19107-5099, USA.
Blood. 1997 Jun 1;89(11):4071-7.
Endothelial cells (EC) possess at least two membrane receptors for von Willebrand factor (vWF), the vitronectin receptor (VNR, alpha(v)beta3), which recognizes an Arg-Gly-Asp (RGD) sequence in the C-terminus of vWF, and glycoprotein Ib alpha (GP Ib alpha), which interacts with a region in the N-terminal A1 domain of vWF. In the absence of added cytokines, EC attachment to a vWF substratum is mediated largely through the alpha(v)beta3, with a smaller contribution by GP Ib alpha. In the present study, we have examined the effect of cytokines on the receptor specificity of EC attachment to wild-type vWF (WT-vWF) and to vWF, which had been mutated in the C-terminal RGDS sequence (RADS-vWF). Exposure of human umbilical vein EC (HUVEC) to tumor necrosis factor-alpha (TNF-alpha) or to TNF-alpha in combination with interferon-gamma (IFN-gamma), but not to interleukin-1beta (IL-1), increased attachment to RADS-vWF by about twofold. The TNF-alpha-induced increase in EC attachment was accompanied by an increase in cell surface GP Ib alpha expression; GP Ib alpha surface expression was not increased by IL-1. Attachment of untreated HUVEC to WT-vWF could be inhibited 60% to 70% by a monoclonal antibody (MoAb) (LM609) to the VNR and 30% to 40% by the A1 fragment of vWF (containing the GP Ib alpha binding domain). The pattern of inhibition of attachment to WT-vWF was largely unchanged after TNF-alpha treatment of HUVEC. In contrast, the attachment to WT-vWF of HUVEC, treated with TNF-alpha +IFN-gamma was completely inhibited by vWF-A1 and inhibited only 35% by the anti-VNR antibody LM609. Two MoAbs to GP Ib alpha produced similar, but incomplete, inhibition. Pretreatment of HUVEC with the combination of TNF-alpha + IFN-gamma produced a dramatic decrease in VNR expression, confirming previous findings of Defilippi et al. These results suggest that in the presence of the inflammatory cytokines TNF-alpha + IFN-gamma, the endothelial GP Ib complex is a major determinant of HUVEC adhesion to surface-bound vWF.
内皮细胞（EC）拥有至少两种针对血管性血友病因子（vWF）的膜受体，即玻连蛋白受体（VNR，α(v)β3），它识别vWF C末端的精氨酸 - 甘氨酸 - 天冬氨酸（RGD）序列，以及糖蛋白Ibα（GP Ibα），它与vWF N末端A1结构域中的一个区域相互作用。在没有添加细胞因子的情况下，EC与vWF基质的附着主要通过α(v)β3介导，GP Ibα的作用较小。在本研究中，我们研究了细胞因子对EC附着于野生型vWF（WT - vWF）和C末端RGDS序列发生突变的vWF（RADS - vWF）的受体特异性的影响。人脐静脉内皮细胞（HUVEC）暴露于肿瘤坏死因子 - α（TNF - α）或TNF - α与干扰素 - γ（IFN - γ）联合作用下，但不暴露于白细胞介素 - 1β（IL - 1）时，与RADS - vWF的附着增加约两倍。TNF - α诱导的EC附着增加伴随着细胞表面GP Ibα表达的增加；IL - 1未增加GP Ibα的表面表达。未处理的HUVEC与WT - vWF的附着可被针对VNR的单克隆抗体（MoAb）（LM609）抑制60%至70%，被vWF的A1片段（包含GP Ibα结合结构域）抑制30%至40%。HUVEC经TNF - α处理后，对WT - vWF附着的抑制模式基本不变。相反，经TNF - α + IFN - γ处理的HUVEC与WT - vWF的附着被vWF - A1完全抑制，被抗VNR抗体LM609仅抑制35%。两种针对GP Ibα的MoAb产生了相似但不完全的抑制作用。用TNF - α + IFN - γ组合预处理HUVEC导致VNR表达显著降低，证实了德菲利皮等人先前的发现。这些结果表明，在炎性细胞因子TNF - α + IFN - γ存在的情况下，内皮GP Ib复合物是HUVEC与表面结合的vWF黏附的主要决定因素。
