脂氧素受体FPR2介导辛伐他汀促中性粒细胞凋亡减轻脑出血炎症的机制研究

Inflammation plays a key role in the development of secondary brain injury after intracerebral hemorrhage (ICH), and infiltration of polymorphonuclear neutrophil (PMN) is one of the most important factors that attributing to ICH inflammation. However, there is no effective treatment. Previous studies have confirmed that simvastatin can promote peripheral PMN apoptosis, reduce perihematomal PMN infiltration, and improve the prognosis of ICH rats, but the underlying mechanism remains unclear. Previous studies have shown that inhibition of p38MAPK signaling pathway down-regulates anti-apoptotic protein myeloid leukemia factor-1 (Mcl-1) and accelerated PMN apoptosis. Recent studies have shown that activation of lipoxin receptor (FPR2) could inhibit p38MAPK phosphorylation. Our preliminary experiment showed that FPR2 antagonist effectively blocked simvastatin-induced apoptosis of PMN and increased PMN infiltration around the hematoma. Accordingly, we speculate that simvastatin may inhibit the phosphorylation of p38MAPK by activating FPR2, thus promoting PMN apoptosis to reduce PMN brain infiltration, alleviate inflammation and brain injury. This programme will use methods of in vitro and in vivo experiments to explore the role of FPR2 in simvastatin-induced pro-PMN apoptosis and anti-neuroinflammatory effects following ICH, and lay the foundation for simvastatin in clinical treatment of ICH patients.

炎症是脑出血（ICH）后继发性脑损伤的关键环节，而病灶周围中性粒细胞（PMN）浸润是加重ICH炎症的重要因素之一，目前尚无有效治疗方法。我们前期研究证实：辛伐他汀能够促进外周PMN凋亡，减少脑血肿周围PMN浸润，改善ICH大鼠预后，但潜在机制不清。既往研究表明抑制p38MAPK信号通路能够下调抗凋亡蛋白髓细胞白血病因子-1（Mcl-1）加速PMN凋亡，最近研究发现激活脂氧素受体（FPR2）能够抑制p38MAPK磷酸化。我们预实验结果显示：FPR2拮抗剂能有效阻断辛伐他汀促PMN凋亡效应，增加血肿周围PMN浸润。据此我们推测：辛伐他汀可能通过激活FPR2抑制p38MAPK磷酸化，进而促使外周PMN凋亡，减少PMN脑组织浸润，最终发挥抗炎脑保护作用。本项目拟结合离体和在体实验，探讨FPR2介导辛伐他汀促PMN凋亡减轻ICH炎症的机制，为辛伐他汀应用于ICH患者临床治疗奠定基础。

本研究立足于前期研究基础，通过干预FPR2/P38MAKP/Mcl-1通路，探讨辛伐他汀在脑出血后发挥促中性粒细胞凋亡和抗炎效应的潜在机制，为脑出血后脑损伤防治提供新的靶点。. 1.我们在脑出血大鼠的循环血检测中发现，中性粒细胞（PMNs）计数和中性粒细胞/淋巴细胞比值显著升高。辛伐他汀治疗可显著减轻脑出血后PMNs的脑浸润及随后的神经炎症反应，部分原因是通过扰乱凋亡相关蛋白的表达，加速了外周血PMNs的凋亡。. 2.辛伐他汀显著提高了ICH早期血浆中脂氧素LXA4(内源性FPR2激动剂)的水平。给予外源性LXA4治疗有效促进了中性粒细胞凋亡，降低了外周血及血肿周围区域PMNs计数，改善了脑出血后神经炎症及脑损伤，其治疗效果与辛伐他汀相当。提示辛伐他汀和脂氧素对ICH均有潜在的药物价值。.3.进一步通路研究发现，辛伐他汀可能通过上调LXA4 活化脂氧素受体 FPR2，抑制 p38MAPK磷酸化，诱导胞内抗凋亡蛋白 Mcl-1 降解加速 PMN 凋亡，减少 PMN 脑组织浸润， 发挥了抗炎脑保护作用。提示，“对中性粒细胞早期凋亡的调控”有望成为潜在的脑出血后脑保护新策略。