FGL2在脑出血继发性脑损伤中的作用和机制研究

There is no effective treatment for intracerebral hemorrhage (ICH) until now. There is much evidence that high concentrations of thrombin mediate ICH-induced brain injury. Recent studies showed that membrane bound FGL2 is a new type of prothrombinase capable of directly cleaving prothrombin to thrombin; and secreted FGL2 (sFGL2) plays a regulatory role in the inflammation and immune process. Accordingly, we hypothesize that FGL2 may be involved in the pathogenesis of secondary brain injury form ICH. Recent publications and our preliminary experiments showed that the expression of FGL2 in the brain tissue was elevated after ICH; and our results further showed that the over-expression of FGL2 aggravated the brain edema and neurological dysfunction of ICH mice, which proved that FGL2 is involved in the process of secondary brain injury of ICH. However, it still needs to be elucidated the detailed function and mechanism of FGL2 in the pathogenesis of ICH and its clinical implications. Therefore, in current study we would perform a clinical study to learn the serum level of sFGL2 in ICH patients as compared to ischemic stroke patients and healthy controls and its correlation with hematoma volume and brain edema volume. We would also perform animal studies to demonstrate the effect of over-expression/knock-down of FGL2 on the brain edema, blood-brain barrier permeability and neurological dysfunction and the effect on different cells of neurological and immunological systems. We would further clarify whether the effect of FGL2 in the pathogenesis of ICH was dependent on MAPK signaling pathway. Our study will provide important preliminary results in elucidating the neuro-protective function and mechanism of FGL2 in ICH and might be of great clinical value in finding new targets of the treatment of ICH.

脑出血尚无有效治疗，凝血酶大量释放在脑出血继发性脑损害中起重要作用。膜型FGL2可直接将凝血酶原剪切为凝血酶，分泌型FGL2（sFGL2）具有炎症和免疫调节作用，由此可推测FGL2参与脑出血损伤过程。最新文献及我们预实验均显示脑出血后脑组织中FGL2表达升高，且我们预实验进一步表明过表达FGL2加重小鼠脑出血后脑水肿和神经功能缺损，证实FGL2参与脑出血继发性脑损伤过程，但目前尚不清楚FGL2在脑出血中的具体作用机制及其临床意义，故本课题将通过临床研究阐明脑出血患者血清sFGL2的变化及其与脑血肿体积和临床指标的相关性；通过动物研究阐明过表达/敲除FGL2对小鼠脑出血后脑水肿、血脑屏障通透性及神经功能缺损的影响及对不同神经细胞和免疫细胞的作用，并研究FGL2对脑出血损伤的作用是否依赖于MAPK通路。我们将通过以上研究初步阐明FGL2在脑出血中的作用和机制，对寻找新的治疗靶点具有积极意义。

背景：血脑屏障破坏和脑水肿是脑出血继发性脑损伤的两大重要机制。蛋白酶激活受体1（PAR1）拮抗剂通过多种机制对脑出血继发性脑损伤起到保护作用。纤维蛋白原样蛋白2（FGL2）是一个新型凝血酶原酶，膜型FGL2（mFGL2）可直接将凝血酶原剪切为凝血酶，分泌型FGL2（sFGL2）具有炎症和免疫调节作用，由此可推测FGL2参与脑出血损伤过程。本研究将探索FGL2在脑出血损伤中的作用及其与PAR1拮抗剂及的相互作用机制。.研究内容：通过成年雄性小鼠（C57BL/6）纹状体注射凝血酶制备脑出血小鼠模型。通过调控FGL2和TLR4的表达研究两者在脑出血中的治疗作用。并且通过上调或下调FGL2或TLR4，来发现两者对PAR1拮抗剂在脑出血中的治疗作用的影响。通过Evans blue染色、脑水肿的测量、神经功能缺损评分和脑切片染色来评估脑出血的严重程度。.关键数据:脑出血后脑组织中FGL2和TLR4的表达升高,磷酸化的JNK,ERK和p38 MAPK的表达也升高。抑制FGL2和TLR4可以改善脑出血小鼠的脑组织水肿、血脑屏障破坏，并下调p-JNK,p-ERK,p-p38 MAPK和p-IKKα的表达；而上调FGL2和TLR4可起到相反的作用。PAR1拮抗剂对脑出血的保护作用在FGL2或TLR4过表达后受到了抑制。 .科学意义: PAR1拮抗剂对脑出血的治疗作用可能是通过FGL2和TLR4发挥作用。因此FGL2和TLR4可能是治疗脑出血的新靶点。