Reinhardt P H, Elliott J F, Kubes P
Immunology Research Group, University of Calgary, Alberta, Canada.
Blood. 1997 May 15;89(10):3837-46.
In this study we investigated the possibility that an alternative pathway exists for neutrophil recruitment, namely an alpha4beta1-dependent pathway. A parallel plate chamber was used to investigate whether neutrophils could tether, roll, and adhere to tumor necrosis factor alpha (TNF alpha)-stimulated endothelium via alpha4beta1. alpha4beta1-integrin was induced on neutrophils using dihydrocytochalasin B and either an endogenous (endothelial-derived) chemotactic agent or an exogenous chemotactic molecule. alpha4beta1-expressing neutrophils could stably adhere under shear force (2 dyne/cm2) to TNF alpha-stimulated endothelium independent of the beta2-integrin. The firm adhesion was entirely abolished by antibodies directed against either the alpha4 or beta1-integrin subunits. However, the rolling interaction was not dependent on alpha4beta1 but was abolished by antiselectin therapy. Neutrophils expressing alpha4beta1 could also tether to the endothelium in the presence of antiselectin therapy, but at shear stresses less than 2 dyne/cm2. alpha4beta1-expressing neutrophils also tethered to and stably adhered (no rolling) to VCAM-1- but not to ICAM-1-transfected L cells. The interaction only occurred at shear stress less than 2 dyne/cm2. A cell line (Ramos) known to express high quantities of alpha4beta1-integrin interacted with VCAM-1-transfected L cells at very similar shear conditions. alpha4beta1-expressing neutrophils were also able to adhere to a second alpha4-integrin ligand, fibronectin; however, this interaction only occurred under static conditions. These data suggest that, under certain conditions, neutrophils can adhere independently of the beta2-integrin pathway and adhere via the alpha4beta1-integrin. This study refutes the concept that alpha4beta1-integrin adhesion is restricted to mononuclear leukocytes and is not functional on human neutrophils.
在本研究中，我们调查了中性粒细胞募集存在另一种途径的可能性，即α4β1依赖性途径。使用平行板流动腔来研究中性粒细胞是否能够通过α4β1与肿瘤坏死因子α（TNFα）刺激的内皮细胞发生栓系、滚动和黏附。使用二氢细胞松弛素B以及内源性（内皮细胞衍生的）趋化剂或外源性趋化分子在中性粒细胞上诱导α4β1整合素。表达α4β1的中性粒细胞能够在剪切力（2达因/平方厘米）作用下稳定黏附于TNFα刺激的内皮细胞，且不依赖于β2整合素。针对α4或β1整合素亚基的抗体可完全消除牢固黏附。然而，滚动相互作用不依赖于α4β1，但抗选择素治疗可将其消除。在抗选择素治疗存在的情况下，表达α4β1的中性粒细胞也能够与内皮细胞发生栓系，但剪切应力小于2达因/平方厘米。表达α4β1的中性粒细胞也可与血管细胞黏附分子-1（VCAM-1）转染的L细胞发生栓系并稳定黏附（无滚动），但不与细胞间黏附分子-1（ICAM-1）转染的L细胞发生上述情况。这种相互作用仅在剪切应力小于2达因/平方厘米时发生。已知表达大量α4β1整合素的细胞系（Ramos）在非常相似的剪切条件下与VCAM-1转染的L细胞相互作用。表达α4β1的中性粒细胞也能够黏附于另一种α4整合素配体纤连蛋白；然而，这种相互作用仅在静态条件下发生。这些数据表明，在某些条件下，中性粒细胞能够独立于β2整合素途径发生黏附，并通过α4β1整合素发生黏附。本研究反驳了α4β1整合素黏附仅限于单核白细胞且对人中性粒细胞无功能的观点。
