HMGB1信号通路在大鼠脑出血后7-14天促进神经血管再生的作用机制研究

Rencent studies showed that high-mobility group box 1(HMGB1) activates several receptors, such as receptor for advanced glycation end products (RAGE), toll-like receptor-2, and toll-like receptor-4, thereby promoting neurogenesis and angiogenesis. HMGB1 likely involve interactions among the protein and the brain microenvironment, various activated neuronal cells, numerous growth factors, and specific receptors in the neurovascular unit. Our studies suggested that in a rat model of collagenase-induced intracerebral hemorrhage (ICH), levels of cytoplasmic HMGB1 increased within a few days of ICH induction, and the levels continued to rise 7-14 days later. The later increases in HMGB1 levels were associated with increases in NGF and VEGF, as well as the number of DCX- and BrdU-positive cells around the hematoma.These findings suggest that HMGB1 may promote angiogenesis and neurogenesis in the late phase of ICH. Moreover, our study showed that matrix metalloproteinases-9 (MMP-9) might promote neurogenesis and angiogenesis during recovery from ICH. Some studies suggested that HMGB1 promoted the expression and activity of MMP-9 in acute cerebral infarction and tumor model by activating downstream receptors. This study surveys the content of HMGB1, relevant receptors, MMP-9, growth factors, new neurons, and blood vessels, which prove HMGB1 signal pathway promotes the repair of brain tissue in 7-14 days after ICH in rats.

相关研究显示高迁移率族蛋白1（high-mobility group box 1, HMGB1）主要通过糖基化终末产物受体（RAGE）和Toll样受体2/4（TLR2/4)作用于细胞外基质，为神经血管再生提供生长空间,增加或者激活生长因子及特殊的受体，为新生神经元和血管提供生长动力。我们前期的研究提示HMGB1在大鼠脑出血后1到14天呈现逐渐增加的趋势，在7到14天伴随着NGF和VEGF的增加，及DCX和BrdU阳性细胞的增加，提示HMGB1在7到14天大鼠脑出血中可能促进神经和血管的再生。同时我们的研究也提示基质金属蛋白酶-9（MMP-9）具有促进神经和血管再生的作用。在急性脑梗死、肿瘤等模型中HMGB1通过下游受体增加MMP-9的表达和活性。本研究拟测定HMGB1、相关受体、MMP-9、生长因子、新生神经元和血管等探索HMGB1在大鼠脑出血后7-14天促进脑组织修复的信号通路。

我们的研究发现大鼠脑出血后high-mobility group box 1 protein （HMGB1）从细胞核中释放到细胞浆中，1、3、7天和14天的HMGB1含量呈现逐渐递增的趋势，HMGB1的含量在第7天和第14天（恢复期）明显地高于第1天和第3天（急性期）。在脑出血后HMGB1、晚期糖基化终末产物(advanced glycation end-products,RAGE）、 toll样受体4(toll-like receptor 4,TLR4）和TLR2、脑源性营养因子(brain-derived neurotrophic factor ,BDNF)，基质金属蛋白酶9(matrix metalloproteinase-9,MMP-9)较假手术组也明显地增高，并且伴随Brdu或DCX阳性细胞及CD31阳性细胞增多。给予EP显著减少脑出血诱导的除TLR4和TLR2以外的上述因子表达增加。给予RAGE特异性抑制剂FPS-ZM1观察到DCX-阳性细胞和Brdu-阳性细胞， BDNF、VEGF和MMP9等也减少。提示在大鼠脑出血后HMGB1可能促进神经血管再生，HMGB1可能通过RAGE信号通路促进下游的因子的表达，从而促进神经血管单元修复。另外，体外实验同时也发现外源性HMGB1对原代培养的神经干细胞有刺激其增殖与促进向神经元分化的有利影响，并且伴随有RAGE、TLR2、MMP-9、NGF等生长因子的增高。