Witting P K, Zeng B, Wong M, McMahon A C, Rayner B S, Sapir A J, Lowe H C, Freedman S B, Brieger D B
Vascular Biology Group, ANZAC Research Institute, Concord, NSW 2139, Australia.
Thromb Res. 2008;122(5):674-82. doi: 10.1016/j.thromres.2007.12.013. Epub 2008 Apr 16.
Mice lacking plasminogen (PG-/-) require alternative pathways of fibrinolysis for survival. This may depend on polymorphonuclear leukocytes (PMN) that can clear soluble and insoluble fibrin(ogen) through PG-independent processes. Our objective was to demonstrate that PMNs from PG-/- mice exhibit increased Mac-1 dependent phagocytic activity, which may explain their increased fibrin(ogen)lytic activity compared with wild type (PG+/+) mice.
Phagocytic activity of PMNs from PG-/- and PG+/+ mice was compared following exposure to Staphylococcus aureus (S. aureus) particles and the expression of Mac-1 was assessed in parallel by flow cytometric analysis. Resistance to phorbol-12-myristate-13-acetate (PMA)-induced cell death was compared between PMNs from the different genotypes.
Stimulation of PG-/- PMNs by opsonized S. aureus diluted in PG-/- plasma significantly increased phagocytosis (15-fold) compared with stimulation of PG+/+ PMNs in PG+/+ plasma. Incubation of PG-/- PMNs with PG+/+ plasma (control) or PG-/- plasma supplemented with human PG inhibited this increased phagocytic activity. Mac-1 cell surface density increased 6.2+/-1.0-fold in PG-/- PMNs versus 2.9+/-0.6-fold in PG+/+ PMNs (P < 0.01) indicating that Mac-1 may be associated with increased phagocytic activity. Supporting this, treatment of PG-/- PMNs with an anti-Mac-1 antibody in PG-/- plasma inhibited phagocytic activity. In addition, physiologic PG blocked Mac-1 accessibility at the surface of PMNs. Addition of PMA resulted in 33% death of PMNs from PG-/- mice versus 68% in PG+/+ controls (P < 0.001).
PMNs from PG-/- mice exhibit a Mac-1 dependent increase in phagocytic activity that is suppressed with human PG, an anti-Mac-1 antibody or the plasma from PG+/+ mice. The propensity for PMNs from PG-/- mice to be activated in response to PMA together with their relative resistance to PMA-toxicity may contribute to increased PMN half-life and enhanced fibrin(ogen) clearance in the setting of PG deficiency.
缺乏纤溶酶原的小鼠(PG-/-)需要替代性纤维蛋白溶解途径才能存活。这可能取决于多形核白细胞(PMN),其可通过不依赖纤溶酶原的过程清除可溶性和不溶性纤维蛋白(原)。我们的目的是证明PG-/-小鼠的PMN表现出增加的Mac-1依赖性吞噬活性,这可能解释了它们与野生型(PG+/+)小鼠相比纤维蛋白(原)溶解活性增加的原因。
在暴露于金黄色葡萄球菌(S. aureus)颗粒后比较PG-/-和PG+/+小鼠的PMN的吞噬活性,并通过流式细胞术分析平行评估Mac-1的表达。比较不同基因型的PMN对佛波酯-12-肉豆蔻酸酯-13-乙酸酯(PMA)诱导的细胞死亡的抗性。
与PG+/+血浆中PG+/+PMN的刺激相比,用PG-/-血浆稀释的调理金黄色葡萄球菌刺激PG-/-PMN显著增加吞噬作用(15倍)。用PG+/+血浆(对照)或补充人纤溶酶原的PG-/-血浆孵育PG-/-PMN可抑制这种增加的吞噬活性。PG-/-PMN中Mac-1细胞表面密度增加6.2±1.0倍,而PG+/+PMN中增加2.9±0.6倍(P<0.01),表明Mac-1可能与吞噬活性增加有关。支持这一点的是,在PG-/-血浆中用抗Mac-1抗体处理PG-/-PMN可抑制吞噬活性。此外,生理性纤溶酶原阻断了PMN表面Mac-1的可及性。添加PMA导致PG-/-小鼠的PMN有33%死亡,而PG+/+对照中有68%死亡(P<0.001)。
PG-/-小鼠的PMN表现出Mac-1依赖性吞噬活性增加,用人纤溶酶原、抗Mac-1抗体或PG+/+小鼠的血浆可抑制这种活性。PG-/-小鼠的PMN对PMA作出反应而被激活的倾向及其对PMA毒性的相对抗性可能有助于在纤溶酶原缺乏的情况下增加PMN的半衰期并增强纤维蛋白(原)清除。