Viswanathan Kasinath, Richardson Jakob, Togonu-Bickersteth Babajide, Dai Erbin, Liu Liying, Vatsya Pracha, Sun Yun-ming, Yu Jeff, Munuswamy-Ramanujam Ganesh, Baker Henry, Lucas Alexandra R
Vascular Biology Research Group, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada.
J Leukoc Biol. 2009 Mar;85(3):418-26. doi: 10.1189/jlb.0808506. Epub 2008 Dec 3.
Serp-1 is a secreted myxoma viral serine protease inhibitor (serpin) with proven, highly effective, anti-inflammatory defensive activity during host cell infection, as well as potent immunomodulatory activity in a wide range of animal disease models. Serp-1 binds urokinase-type plasminogen activator (uPA) and the tissue-type PA, plasmin, and factor Xa, requiring uPA receptor (uPAR) for anti-inflammatory activity. To define Serp-1-mediated effects on inflammatory cell activation, we examined the association of Serp-1 with monocytes and T cells, effects on cellular migration, and the role of uPAR-linked integrins and actin-binding proteins in Serp-1 cellular responses. Our results show that Serp-1 associates directly with activated monocytes and T lymphocytes, in part through interaction with uPAR (P<0.001). Serp-1, but not mammalian serpin PA inhibitor-1 (PAI-1), attenuated cellular adhesion to the extracellular matrix. Serp-1 and PAI-1 reduced human monocyte and T cell adhesion (P<0.001) and migration across endothelial monolayers in vitro (P<0.001) and into mouse ascites in vivo (P<0.001). Serp-1 and an inactive Serp-1 mutant Serp-1(SAA) bound equally to human monocytes and T cells, but a highly proinflammatory mutant, Serp-1(Ala(6)), bound less well to monocytes. Serp-1 treatment of monocytes increased expression of filamin B actin-binding protein and reduced CD18 (beta-integrin) expression (P<0.001) in a uPAR-dependent response. Filamin colocalized and co-immunoprecipitated with uPAR, and short interference RNA knock-down of filamin blocked Serp-1 inhibition of monocyte adhesion. We report here that the highly potent, anti-inflammatory activity of Serp-1 is mediated through modification of uPAR-linked beta-integrin and filamin in monocytes, identifying this interaction as a central regulatory axis for inflammation.
Serp-1是一种分泌型黏液瘤病毒丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂），在宿主细胞感染期间具有经证实的高效抗炎防御活性，并且在多种动物疾病模型中具有强大的免疫调节活性。Serp-1结合尿激酶型纤溶酶原激活剂（uPA）、组织型PA、纤溶酶和因子Xa，其抗炎活性需要uPA受体（uPAR）。为了确定Serp-1对炎症细胞激活的介导作用，我们研究了Serp-1与单核细胞和T细胞的关联、对细胞迁移的影响，以及uPAR连接的整合素和肌动蛋白结合蛋白在Serp-1细胞反应中的作用。我们的结果表明，Serp-1直接与活化的单核细胞和T淋巴细胞结合，部分是通过与uPAR相互作用（P<0.001）。Serp-1而非哺乳动物丝氨酸蛋白酶抑制剂PA抑制剂-1（PAI-1）减弱了细胞与细胞外基质的黏附。Serp-1和PAI-1降低了人单核细胞和T细胞的黏附（P<0.001）以及体外跨内皮单层的迁移（P<0.001）和体内向小鼠腹水的迁移（P<0.001）。Serp-1和无活性的Serp-1突变体Serp-1(SAA)与人单核细胞和T细胞的结合程度相同，但高度促炎的突变体Serp-1(Ala(6))与单核细胞的结合较差。Serp-1处理单核细胞可增加细丝蛋白B肌动蛋白结合蛋白的表达，并在uPAR依赖性反应中降低CD18（β整合素）的表达（P<0.001）。细丝蛋白与uPAR共定位并共免疫沉淀，细丝蛋白的短发夹RNA敲低阻断了Serp-1对单核细胞黏附的抑制作用。我们在此报告，Serp-1的高效抗炎活性是通过修饰单核细胞中uPAR连接的β整合素和细丝蛋白介导的，确定这种相互作用是炎症的核心调节轴。
