Lum H, Gibbs L, Lai L, Malik A B
Department of Pharmacology, Rush Medical College/Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612.
J Leukoc Biol. 1994 Jan;55(1):58-63. doi: 10.1002/jlb.55.1.58.
We examined the hypothesis that neutrophil (PMN)-mediated injury of the vascular endothelium is dependent on adhesion of PMNs to endothelial cells via the leukocyte adhesion glycoprotein CD11/CD18. We compared the PMN activation responses [i.e. adhesion to cultured endothelial cells, superoxide (O2-) production, degranulation, and cytosolic [Ca2+] ([Ca2+]i)] and endothelial injury elicited by opsonized zymosan (OZ, which is phagocytosed by PMNs) or phorbol 12-myristate 13-acetate (PMA, a protein kinase C activator). The basal adherence of nonstimulated PMNs to bovine pulmonary artery endothelial cells (BPAEC) was 9.0 +/- 1.1 PMN/field. PMA and OZ increased PMN adherence to BPAEC (to 31.1 +/- 1.4 and 39.8 +/- 3.8 PMN/field, respectively), which in both cases was inhibited by anti-CD18 monoclonal antibody (mAb) IB4. Stimulation of PMNs with PMA or OZ produced injury to 73% and 53% of BPAEC examined, respectively, which corresponded to 6.8-fold and 3.5-fold increases in transendothelial 125I-albumin permeability from baseline. Pretreatment of PMNs with mAb IB4 prevented endothelial injury in both cases. Both PMA and OZ increased the production of O2- (by 7.6-fold and 3.1-fold over control, respectively) and promoted the release of myeloperoxidase (5.2-fold and 9.1-fold over control, respectively) (P < .01). IB4 did not inhibit the PMA- or OZ-induced increases in O2-. IB4 did not inhibit the PMA-induced myeloperoxidase release but reduced by approximately 29% the OZ-induced myeloperoxidase release. Stimulation of PMNs layered on BPAEC with OZ (0.5 mg/ml) caused an approximately 7-fold increase in PMN [Ca2+]i over baseline, which decayed to a steady-state level above baseline at 10 min. IB4 (10 micrograms/ml) alone did not alter baseline [Ca2+]i and did not inhibit the OZ-induced increase in [Ca2+]i. In contrast to OZ, stimulation of PMNs with PMA did not increase [Ca2+]i. The results indicate that the protective effects of the anti-CD18 mAb IB4 were associated predominantly with its antiadherence property. Therefore, CD18 integrin-mediated PMN adhesion to the endothelium is a critical determinant of endothelial injury irrespective of the PMN-activating stimulus.
中性粒细胞（PMN）介导的血管内皮损伤依赖于PMN通过白细胞黏附糖蛋白CD11/CD18与内皮细胞的黏附。我们比较了PMN的激活反应[即对培养的内皮细胞的黏附、超氧化物（O2-）生成、脱颗粒以及胞质[Ca2+]（[Ca2+]i）]，以及经调理的酵母聚糖（OZ，被PMN吞噬）或佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA，一种蛋白激酶C激活剂）引发的内皮损伤。未刺激的PMN对牛肺动脉内皮细胞（BPAEC）的基础黏附率为9.0±1.1个PMN/视野。PMA和OZ均增加了PMN对BPAEC的黏附（分别增至31.1±1.4和39.8±3.8个PMN/视野），在这两种情况下，抗CD18单克隆抗体（mAb）IB4均能抑制这种黏附。用PMA或OZ刺激PMN分别导致所检测的BPAEC中73%和53%受损，这分别对应于跨内皮125I-白蛋白通透性较基线增加6.8倍和3.5倍。用mAb IB4预处理PMN在两种情况下均能防止内皮损伤。PMA和OZ均增加了O2-的生成（分别比对照增加7.6倍和3.1倍），并促进了髓过氧化物酶的释放（分别比对照增加5.2倍和9.1倍）（P<0.01）。IB4未抑制PMA或OZ诱导的O2-增加。IB4未抑制PMA诱导的髓过氧化物酶释放，但使OZ诱导的髓过氧化物酶释放减少了约29%。用OZ（0.5mg/ml）刺激铺在BPAEC上的PMN导致PMN的[Ca2+]i比基线增加约7倍，在10分钟时降至高于基线的稳态水平。单独的IB4（10μg/ml）未改变基线[Ca2+]i，也未抑制OZ诱导的[Ca2+]i增加。与OZ相反，用PMA刺激PMN未增加[Ca2+]i。结果表明，抗CD18 mAb IB4的保护作用主要与其抗黏附特性相关。因此，无论PMN激活刺激因素如何，CD18整合素介导的PMN与内皮的黏附都是内皮损伤的关键决定因素。
