凝血酶原酶Fgl2调控程序性炎症消退的机制研究

In the development of inflammatory diseases, thrombin is a key factor in the activation of blood clotting and inflammation. Prothrombin activation is dependent on the catalysation of prothrombinase Fgl2. Fgl2 includes 2 distinct forms, i.e. transmembrane (mFgl2) and soluble (sFgl2): mFgl2 directly cleaves prothrombin into thrombin, which subsequently activates clotting; sFgl2 plays an immunosuppressor role. Inflammation resolution is an active programmed process. It has been reported that Fgl2 can promote the onset of a variety types of inflammation, but its impact on inflammation resolution is unclear. Our preliminary experiments found that Fgl2 was upregulated in the plasma of patients with clinical sepsis; the peritonitis in Fgl2 knockout mice is more severe than in wild-type mice, sFgl2 can promote 15-LOX, a key enzyme in the synthesis of specialized pro-resolving lipid mediators, in macrophages. Hence we propose the hypothesis that mFgl2 and sFgl2 may play a different role in the inflammation resolution, mFgl2 is pro-inflammatory via its procoagulant role, while sFgl2 can induce the synthesis of the SPM and promote inflammation resolution. This paper intends to elucidate the role and regulatory mechanism of Fgl2 in the programmed onset and resolution of inflammation, thereby provide novel targets for eliciting resolution and new ideas for clinical anti-sepsis treatment.

在炎症性疾病发生发展过程中，凝血酶是启动凝血与炎症的关键因子之一。凝血酶原的激活依赖凝血酶原酶Fgl2的催化。Fgl2包括跨膜型(mFgl2)和可溶型(sFgl2)两类：mFgl2能直接催化凝血酶原转变为凝血酶，快速启动凝血；sFgl2则发挥免疫抑制作用。炎症消退是主动的程序化过程，已知Fgl2可促进多种炎症启动，但其对炎症消退的影响尚不清楚。我们前期预实验发现Fgl2在临床败血症患者血浆中表达上调，Fgl2敲除小鼠的腹膜炎较野生小鼠更严重，sFgl2可促进巨噬细胞表达促消退脂类介质合成的关键酶15-LOX，从而推测mFgl2和sFgl2在炎症消退中可能发挥不同的作用，mFgl2通过促凝血而促炎，而sFgl2可诱导SPM的合成而促进炎症消退。本课题拟阐明Fgl2对炎症的程序化启动和和消退过程的调控及具体机制，为启动炎症消退提供新的靶点，为临床抗败血症治疗提供新思路。

在炎症性疾病发生发展过程中，凝血酶是启动凝血与炎症的关键因子之一。凝血酶原的激活依赖凝血酶原酶Fgl2的催化。Fgl2包括跨膜型(mFgl2)和可溶型(sFgl2)两类：mFgl2能直接催化凝血酶原转变为凝血酶，快速启动凝血；sFgl2则发挥免疫抑制作用。炎症消退是主动的程序化过程，已知Fgl2可促进多种炎症启动，但其对炎症消退的影响尚不清楚。本课题使用临床脓毒症患者样本、小鼠腹膜炎模型、盲肠结扎穿孔模型揭示了sFgl2和mFgl2在炎症启动和消退过程中的实时差异性变化，明确了sFgl2和mFgl2均与脓毒症预后和炎症消退快慢密切相关；发现Fgl2的表达和分泌受miR-466l和金属蛋白酶ADAM10/17的调控；体内敲除Fgl2可促进炎症启动并阻碍炎症消退；鉴定了小鼠自限性腹膜炎多不饱和脂肪酸的代谢产物，发现Fgl2敲除可抑制促消退脂类介质如LXA4和RvDp5的产生；发现sFgl2依赖FcγRIIB抑制中性粒细胞浸润、促进其凋亡和被巨噬细胞清除，延长脓毒症小鼠生存时间；Fgl2敲除将导致巨噬细胞分化成熟障碍，且产生SPM的关键酶12/15-LOX下调，而sFgl2可逆转该作用，回补促消退脂质RvDp5和LXA4；鉴定了RvDp5的受体为脂氧素受体ALX/FPR2；发现RvDp5可通过活化ALX/FPR2促进ADAM17介导的sFgl2产生，抑制mFgl2的表达；RvDp5和sFgl2可协同促进巨噬细胞吞噬凋亡细胞，促进小鼠腹膜炎消退和改善CLP小鼠生存。本研究从程序性炎症消退的崭新视角阐明了Fgl2在败血症和腹膜炎中的作用机制，明确了mFgl2和sFgl2对炎症启动和消退作用的差异，为启动炎症消退提供了新的靶点，并为临床抗脓毒症治疗提供了新思路。