慢性缺血性脑白质病变易感基因及其机制的遗传影像学研究

Chronic ischemic white matter changes (WMC) is a frequent finding on magnetic resonance imaging and computed tomography in the old, acting as a kind of small vessel disease and substantial factor for vascular cognitive impairment. Genetic factors appears to play a significant role, with a heritability ranging from 55% to 80%. In a small vessel disease cohort, taking gene region with susceptible loci reported by previous genome-wide association analysis (GWAS) studies and potential genes as target region, we will perform a prospective study to explore common and rare genomic variations related to WMC by target region high-throughput sequencing and elucidate the relationship between genes with WMC progression and its related cognitive impairment with 18 months follow-up. On the other hand, a series of molecular biological methods will be utilized to investigate the effects of those variations on gene expression and regulation. Our project will provide new insight for WMC progression and offer new strategies for prevention and treatment of WMC and vascular cognitive impairment.

慢性缺血性脑白质病变（WMC）是老年人中常见的小血管病，可引起血管性认知功能损害，其遗传度高达55%-80%。本项目拟在临床队列中，运用高通量测序技术,将前期全基因组关联研究(GWAS）报道的WMC相关位点作为目标区域,进行深度测序,搜寻WMC相关的常见变异和低频罕见变异,结合已报道的易感基因,全面发掘与WMC直接相关的遗传变异；动态随访18个月，脑MRI定量测量WMC体积并评估认知功能，明确易感基因与WMC体积进展及其血管性认知功能损害之间的相关性。另外，在细胞水平，运用分子生物学方法深入研究这些遗传变异对基因表达调控的影响，进一步阐明其参与WMC发生发展的可能生物学机制。本课题旨在为WMC的发生发展机制提供新思路，也为WMC及其血管性认知功能损害的防治提供新策略与技术支持。

慢性缺血性脑白质病变（WMC）是老年人中常见的小血管病，可引起血管性认知功能损害，其遗传度高达55%-80%。课题组连续性入组了200例小血管病患者，运用MRI上评估WMC严重程度，其中112例为WMC患者，88例为无WMC患者。运用高通量二代测序技术,将前期全基因组关联研究(GWAS）报道的WMC相关位点作为目标区域,进行深度测序，获得了WMC遗传变异信息，发现Chr1 rs154409434及rs156202173，Chr6 rs1040970，rs1053878， rs1054022及Chr17 rs73831016， rs73839137， rs73840668与WMC密切相关；动态随访18个月，运用60分钟NINDS-CSN全套神经心理学量表动态评估了患者的认知功能，发现Chr6 rs1040970可能与患者认知功能变化相关。进一步建立了双侧颈动脉狭窄（BCAS）脑白质病变的小鼠模型，观察了Chr6 rs1040970位点在慢性脑缺血WMC双侧颈动脉狭窄（BCAS）模型上引起WMC的病理生理机制，发现小鼠胼胝体的髓鞘脱失持续存在，神经纤维也出现损伤；在造模4周和8周时，整个胼胝体LDLR的mRNA含量分别减少了67.5%和72.6%，LDLR蛋白分别降低至对照组的27.1%和28.1%。并进一步探索了LDLR髓鞘保护作用的上下游分子机制，明确了BCAS小鼠胼胝体区持续升高的miRNAs，小鼠miR-344e-3p在BCAS造模后持续升高，并且与LDLR降低的表现一致，升高的miR-344e-3p主要来源于成熟少突。在体外造模细胞中，通过对miRNA的表达进行检测证实了慢性缺氧环境会导致大鼠少突胶质细胞miR-410-3p（miR-344e-3p的同源miRNA）的显著升高。综上，本课题通过二代深度测序明确了WMC的易感基因，并从动物模型及细胞水平发现了基因可能通过降低中枢内少突胶质细胞内LDLR蛋白水平及miR-344e-3p的升高可能导致WMC发生，这将为WMC及其血管性认知功能损害的防治提供新策略与技术支持。