Department of Medicine, Institute for Biochemistry, Justus Liebig University, D-35392 Giessen, Germany.
J Immunol. 2012 Mar 15;188(6):2858-65. doi: 10.4049/jimmunol.1103029. Epub 2012 Feb 3.
Severe tissue injury results in early activation of serine protease systems including the coagulation and complement cascade. In this context, little is known about factor VII-activating protease (FSAP), which is activated by substances released from damaged cells such as histones and nucleosomes. Therefore, we have measured FSAP activation in trauma patients and have identified novel FSAP substrates in human plasma. Mass spectrometry-based methods were used to identify FSAP binding proteins in plasma. Anaphylatoxin generation was measured by ELISA, Western blotting, protein sequencing, and chemotaxis assays. Plasma samples from trauma patients were analyzed for FSAP Ag and activity, nucleosomes, C5a, and C3a. Among others, we found complement components C3 and C5 in FSAP coimmunoprecipitates. C3 and C5 were cleaved by FSAP in a dose- and time-dependent manner generating functional C3a and C5a anaphylatoxins. Activation of endogenous FSAP in plasma led to increased C5a generation, but this was not the case in plasma of a homozygous carrier of Marburg I single nucleotide polymorphism with lower FSAP activity. In multiple trauma patients there was a large increase in circulating FSAP activity and nucleosomes immediately after the injury. A high correlation between FSAP activity and C5a was found. These data suggest that activation of FSAP by tissue injury triggers anaphylatoxin generation and thereby modulates the posttraumatic inflammatory response in vivo. A strong link between C5a, nucleosomes, and FSAP activity indicates that this new principle might be important in the regulation of inflammation.
严重的组织损伤会导致丝氨酸蛋白酶系统的早期激活，包括凝血和补体级联。在这种情况下，人们对因子 VII 激活蛋白酶（FSAP）知之甚少，该酶被受损细胞释放的物质（如组蛋白和核小体）激活。因此，我们测量了创伤患者中的 FSAP 激活情况，并在人血浆中鉴定了新型 FSAP 底物。基于质谱的方法用于鉴定血浆中的 FSAP 结合蛋白。通过 ELISA、Western blot、蛋白测序和趋化性测定来测量过敏毒素的生成。分析创伤患者的血浆样本以检测 FSAP Ag 和活性、核小体、C5a 和 C3a。除其他外，我们在 FSAP 共沉淀中发现了补体成分 C3 和 C5。C3 和 C5 被 FSAP 以剂量和时间依赖的方式切割，产生功能性 C3a 和 C5a 过敏毒素。内源性 FSAP 在血浆中的激活导致 C5a 的生成增加，但在 FSAP 活性较低的 Marburg I 单核苷酸多态性纯合子的血浆中则不是这种情况。在多发伤患者中，损伤后立即出现循环 FSAP 活性和核小体的大量增加。发现 FSAP 活性与 C5a 之间存在高度相关性。这些数据表明，组织损伤激活 FSAP 会触发过敏毒素的生成，从而调节体内创伤后的炎症反应。C5a、核小体和 FSAP 活性之间的紧密联系表明，这一新原理可能在炎症调节中具有重要意义。
