Brooks Anne M, Bates Mary Ellen, Vrtis Rose F, Jarjour Nizar N, Bertics Paul J, Sedgwick Julie B
Department of Medicine, Allergy, Immunology and Pulmonary Unit, University of Wisconsin, Madison, USA.
Am J Respir Cell Mol Biol. 2006 Oct;35(4):503-11. doi: 10.1165/rcmb.2006-0113OC. Epub 2006 May 25.
Eosinophils migrate from the vascular circulation to the inflamed airways during asthma exacerbations. While the mechanism(s) of this process is not known, the expression of urokinase-type plasminogen activator receptor (uPAR) has been found to modulate neutrophil adhesion and migration to inflammatory sites. We hypothesized that increased expression of uPAR and its ligand, uPA, enhance eosinophil adhesion in patients with asthma. Patients with allergic asthma underwent segmental bronchoprovocation with allergen; 48 h later, peripheral blood and airway (from bronchoalveolar lavage fluid) eosinophils were isolated. uPA and uPAR protein expression were measured by flow cytometry and Western blot; mRNA was quantified by real-time PCR. Eosinophil adhesion to intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 was assessed by eosinophil peroxidase activity. Airway eosinophils expressed significantly more uPA and uPAR protein and uPAR mRNA than peripheral blood eosinophils. Removal of cell-bound uPA and/or addition of exogenous uPA had no effect on blood eosinophil adhesion to ICAM-1 or VCAM-1. In contrast, exogenous uPA stimulated ICAM and VCAM adhesion of airway eosinophils. N-formyl-methionyl-leucyl-phenylalanine-activated airway eosinophil adherence to VCAM-1 and ICAM-1 (VCAM-1, 52.8 +/- 4.7%; ICAM-1, 49.2 +/- 5.3%) was increased over blood eosinophil adhesion (VCAM-1, 38.4 +/- 3.6%; ICAM-1, 27.7 +/- 4.9%; P < 0.05). Removal of cell-bound uPA from airway eosinophils decreased adhesion to blood cell levels; reintroduction of exogenous uPA completely restored adhesion levels. These data suggest that constitutive uPA primes, and exogenous uPA can activate, airway eosinophil adhesion following segmental allergen challenge and that increased uPA expression may be a mechanism of increased eosinophil infiltration and function in asthma.
在哮喘发作期间，嗜酸性粒细胞从血管循环迁移至炎症气道。虽然这一过程的机制尚不清楚，但已发现尿激酶型纤溶酶原激活物受体（uPAR）的表达可调节中性粒细胞向炎症部位的黏附和迁移。我们推测，uPAR及其配体uPA表达的增加会增强哮喘患者嗜酸性粒细胞的黏附。过敏性哮喘患者接受变应原节段性支气管激发试验；48小时后，分离外周血和气道（支气管肺泡灌洗液）嗜酸性粒细胞。通过流式细胞术和蛋白质印迹法检测uPA和uPAR蛋白表达；通过实时PCR对mRNA进行定量。通过嗜酸性粒细胞过氧化物酶活性评估嗜酸性粒细胞与细胞间黏附分子（ICAM）-1和血管细胞黏附分子（VCAM）-1的黏附。气道嗜酸性粒细胞表达的uPA和uPAR蛋白及uPAR mRNA明显多于外周血嗜酸性粒细胞。去除细胞结合的uPA和/或添加外源性uPA对血液嗜酸性粒细胞与ICAM-1或VCAM-1的黏附无影响。相反，外源性uPA刺激气道嗜酸性粒细胞与ICAM和VCAM的黏附。N-甲酰甲硫氨酰亮氨酰苯丙氨酸激活的气道嗜酸性粒细胞与VCAM-1和ICAM-1的黏附（VCAM-1，52.8±4.7%；ICAM-1，49.2±5.3%）高于血液嗜酸性粒细胞的黏附（VCAM-1，38.4±3.6%；ICAM-1，27.7±4.9%；P<0.05）。从气道嗜酸性粒细胞中去除细胞结合的uPA可使其黏附降至血细胞水平；重新引入外源性uPA可完全恢复黏附水平。这些数据表明，组成性uPA可引发，外源性uPA可激活节段性变应原激发后气道嗜酸性粒细胞的黏附，且uPA表达增加可能是哮喘中嗜酸性粒细胞浸润和功能增强的一种机制。
