BRD4通过超级增强子调控巨噬细胞分化及其在慢性排斥反应中的作用

Chronic rejection is the main reason of late graft loss. M2 macrophages play a key role in chronic rejection, but the underlying mechanism of graft-infiltrating M2 differentiation remains unclear. Our preliminary results indicate that BRD4 inhibitor can suppress chronic rejection and lead to graft long-term survival. Additionally, BRD4 inhibition also impairs the differentiation of M2 within graft. Furthermore, M2-specific genes are regulated by BRD4-mediated super enhancers. Therefore, we hypothesize that BRD4 enhances M2 differentiation through mediating M2-specific gene-related super enhancers, and then M2 promotes chronic rejection. To verify our hypothesis, firstly we will investigate the protective effect of BRD4 inhibition on chronic rejection with LysMcre Brd4f/f mice and BRD4 inhibitor, and to verify this effect is dependent on macrophages. Secondly, we will investigate the underlying mechanism of BRD4 regulating M2 differentiation through super enhancers with next-generation sequencing, BDR4 inhibitors and BRD4 knockout mice. Our project will provide new ideas for treatment of chronic rejection.

慢性排斥反应(CR)是后期移植物丢失的主要原因。M2巨噬细胞在CR中起关键作用，但M2在移植物中分化机制尚不清楚。我们前期研究发现：(1)BRD4信号阻断可以抑制CR，促进移植物长期存活；(2)且BRD4抑制剂可以抑制移植物中M2分化；(3)此外，M2特异性基因存在由BRD4所介导的超级增强子(SE)。因此，我们推测BRD4通过SE调控M2分化从而介导CR的发生。本项目拟运用BRD4巨噬细胞特异性敲除小鼠和BRD4抑制剂研究BRD4信号阻断对CR的保护作用，并验证其保护作用对M2的依赖性；然后运用二代测序、抑制剂、BRD4敲除小鼠等阐明BRD4通过SE调控M2分化的机制。本课题研究成果将为器官移植后CR的防治提供新思路。

慢性排斥反应(CR)是后期移植物丢失的主要原因。M2巨噬细胞在CR中起关键作用，但M2在移植物中分化机制尚不清楚。我们前期研究发现：(1)BRD4信号阻断可以抑制CR，促进移植物长期存活；(2)且BRD4抑制剂可以抑制移植物中M2分化；(3)此外，M2特异性基因存在由BRD4所介导的超级增强子(SE)。因此，我们推测BRD4通过SE调控M2分化从而介导CR的发生。本项目构建了小鼠心脏移植模型，运用BRD4抑制剂，综合运用流式细胞术、RNA-seq等技术，发现BRD4抑制剂可显著抑制慢性排斥反应，延长移植物存活期限，其机制主要是通过抑制移植物中M2巨噬细胞的分化来抑制慢性排斥反应的。此外，课题组还证实了BRD4抑制剂可以减轻小鼠肝脏缺血再灌注损伤，在肝移植领域具有潜在的应用价值。课题组还证实了血吸虫可溶性虫卵蛋白可以抑制皮肤移植排斥反应，存进皮肤移植物存活时间延长。本课题研究成果将为器官移植后CR的防治提供新思路。