趋化因子受体CXCR4和“同胞”CXCR7在缺氧致视网膜新生血管中的作用及机制研究

Hypoxia-induced retinal neovascularization is a common cause of blindness. Stromal cell derived factor-1 (SDF-1) belongs to chemokine CXC family. Lots of responses are induced after SDF-1 combining with G protein coupled receptors (GPCR) CXCR4, participating in cellular migrations and chemotaxis. Discovery of CXCR4's “sib” CXCR7 breaks the specific binding of SDF-1/CXCR4. Studies suggest there are commonalities and differences that CXCR4 and CXCR7 act. Our previous works found that blocking recptors CXCR4 and CXCR7 by vitreous-injection of antagonist AMD3100 can reduce retinal neovascularization in oxygen-induce retinopathy (OIR) mice. But which receptor’s role in neovascularization is more primary is not clear. Our study aims to detect human retinal microvasular endothelial cells (HRMVECs) survivings under hypoxia, and poliferations, migrations to SDF-1, after knocking down CXCR4/CXCR7 by shRNA, and their downstreams MAPK and β-arrestin signal pathways, productions of neovascular-related cytokines. Also RNV will be evaluated in OIR mice after knocking down CXCR4 or CXCR7 in retina respectively. We will deduce the distinct role of CXCR4 and CXCR7 in RNV, and discuss their therapy prospects.

缺氧所致视网膜新生血管（RNV）是致盲重要原因。基质细胞衍生因子-1（SDF-1）属趋化因子CXC家族，与G蛋白偶联受体胞膜受体CXCR4结合可导致细胞迁移趋化等活动。近来，CXCR7的发现打破了SDF-1/CXCR4结合的特异性，作为其“同胞”被SDF-1激活，但过程存在共性和差异。前期发现氧诱导视网膜病变（OIR）小鼠球内注射CXCR4/CXCR7双效阻断剂AMD3100抑制了缺氧致RNV，但两者在RNV中的地位关系有待发掘。本研究拟观察低氧HRMECs敲低CXCR4或CXCR7后，细胞存活增殖、迁移，下游MAPK和β-arrestin信号通路及新生血管因子表达水平；观察OIR小鼠球内注射敲低视网膜CXCR4或CXCR7后，RNV、下游MAPK和β-arrestin信号和新生血管细胞因子表达。评估两种受体在缺氧致RNVs形成中的作用和可能机制，探讨两受体的差异和联系。

本课题组通过对缺氧HUVEC细胞和OIR小鼠新生血管模型的研究，对CXCR4和CXCR7敲低后缺氧HUVEC生物学特征、OIR小鼠模型视网膜新生血管情况进行了系统检测，发现“同胞受体”CXCR4和CXCR7在缺氧致新生血管发病机制中所起到的不同作用。缺氧状态下，HUVEC在SDF-1/CXCR4和CXCR7轴被活化，两种受体合成增多，细胞自分泌SDF-1。SDF-1/CXCR4下游与MEK/ERK相关，促进VEGF表达，SDF-1/CXCR7下游与PI3K/Akt信号相关，促进β-arrestin-2信号激活。缺氧下的HUVEC增殖能力和迁移活动主要是通过CXCR4，而不是CXCR7受体下游所介导；细胞抗调亡作用主要通过CXCR7传导。OIR小鼠模型上分别干扰CXCR4和CXCR7表达均可抑制视网膜新生血管形成，而干扰CXCR4表达的对视网膜新生血管的抑制作用更大，可能与VEGF表达减少相关。上述结果为缺氧致视网膜新生血管疾病机制的研究提供实验依据。