Foxp1介导IL-b/Lox-1调节内皮细胞/单核巨噬细胞交互作用 在动脉粥样硬化发生发展中的作用

Atherosclerosis is a chronic progressive inflammatory disease manifested by activation of endothelial cells (ECs) and smooth muscle cells (SMCs), recruitment of monocytes and inflammatory cells. The transcriptional factor Foxp1 is expressed in these cells, but how Foxp1 regulates these processes in vivo is poorly characterized..EC specific Foxp1 knockout (Foxp1 ECKO) or monocyte/macrphage specific Foxp1 knockout (Foxp1 MacKO) mice bred onto Apoe deficient (Apoe-KO) hyperlipidemic mouse model to study the effect of EC and macrophage specific Foxp1 on atherogenesis. Foxp1 expression is observed in ECs and macrophages, and down-regulated in ECs of atherosclerotic plaque. Foxp1 ECKO:ApoeKO, Foxp1 MacKO:ApoeKO mutant mice display significant increases in lesion formation in aortas and aortic roots with more CD11b positive macrophages and SMA positive SMCs. .Endothelial loss of Foxp1 increases adhesion and migration of monocyte, as well as proliferation and migration of SMCs, which were pro-inflammatory e.g., with higher Mcp1 expression. IL-1β is identified as a direct target of Foxp1, and the expression of IL-1β is increased in Foxp1-deficient endothelium. Both siRNA-mediated and pharmacological inhibition of IL-1β in Foxp1-deficient endothelium might reverse the increased monocyte adhesion to ECs, migration of macrophages, proliferation and migration of SMCs and higher Mcp1 expression of SMCs. Moreover, pharmacological inhibition of IL-1β will reverse the increased atherosclerotic lesion formation in Foxp1 ECKO:ApoeKO mice..Monocyte /macrophage loss of Foxp1 increases Lox-1 (Lectin-like oxidized low-density lipoprotein receptor) expression, these residential macrophages uptake more oxLDL and are polarized to pro-inflammatory cells which secrete more cytokines, MMPs (matrix metalloproteinase) and ROS (reactive oxygen species). Lox-1 is identified as a direct target of Foxp1. siRNA-mediated inhibition of Lox-1 in Foxp1-deficient macrophage might reverse the increased uptake of oxLDL and further reverse the polarization of macrophages to pro-inflammatory cells..In conclusions, these data are the first in vivo experimental validation of an atheroprotective role for cell specific function of Foxp1 in atherogenesis, most likely through 1) regulation of monocyte adhesion, macrophage migration and smooth muscle cell proliferation and migration in atherosclerosis via IL-1β pathway; 2) regulation of macrophage uptake of oxLDL and polarization to pro-inflammatory cells via Lox-1 pathway. It advances our understanding of atherogenesis, meanwhile provides opportunities for therapeutic intervention of atherosclerotic diseases.

动脉粥样硬化是慢性进展性血管炎症病变，以激活内皮细胞和单核/巨噬细胞及转录因子Foxp1表达异常为特征，但其机制及交互作用尚不清楚。我们新近发现内皮和单核/巨噬细胞Foxp1特异缺失小鼠动脉粥样斑块形成明显增加，高通量RNA-seq提示内皮Foxp1缺失增加IL-1β表达，而单核/巨噬细胞Foxp1缺失导致Lox-1和MMPs显著增加，提示Foxp1在不同细胞通过不同通路调节内皮-巨噬细胞交互作用，共同参与动脉粥样硬化形成。本项目在此基础上，通过Foxp1条件敲除小鼠研究：内皮细胞Foxp1介导的IL-1β调节平滑肌细胞迁移增殖和炎症表型的转变以及单核/巨噬细胞粘附迁移；单核巨噬细胞Foxp1介导的Lox-1调节巨噬细胞摄取ox-LDL，极化成促炎细胞，上调炎症因子、MMPs和ROS；抑制IL-1β或Lox-1是否逆转Foxp1基因缺失的表型，揭示动脉粥样硬化的病理机制和治疗新靶点。

动脉粥样硬化是一种血管慢性炎症性疾病，功能障碍的血管内皮细胞 (ECs) 促进单核/巨噬细胞浸润到血管壁形成富含脂质的促炎泡沫细胞，导致动脉粥样硬化的形成和发展，最终阻断血流造成脏器缺血甚至梗死，是全球人群死亡的主要原因。.我们发现动脉粥样硬化部位和动脉粥样硬化易感的血管分叉涡流部位内皮细胞转录因子Foxp1 (Forkhead box protein p1) 表达显著降低，血管内皮细胞特异敲除Foxp1导致动脉粥样硬化斑块明显增加，斑块内F4/80+单核/巨噬细胞显著增加，进一步机制研究发现内皮 Foxp1结合并调节炎症小体 Nlrp-Caspase-1-IL1β 通路控制单核/巨噬细胞-内皮粘附和迁移，血管内皮细胞特异敲除 Foxp1激活 Nlrp炎症小体产生 IL1β 增加单核/巨噬细胞-内皮粘附和迁移到血管壁导致动脉粥样硬化斑块的增加。转录因子Klf2 (Kruppel-like factor 2) 是一个血流调控基因，在调节血管内皮细胞功能稳态中起重要作用。进一步研究发现血管内皮 Klf2 调节 Foxp1 表达，继而激活炎症小体产生 IL-1β 调节单核/巨噬细胞血管的浸润和泡沫细胞形成而影响动脉粥样硬化斑块形成和发展。他汀 (Statins) 是一个广泛使用的降脂抗动脉粥样硬化的药物，研究发现辛伐他丁是血管内皮细胞 Klf2 表达的强诱导剂，辛伐他丁诱导动脉粥样硬化易感部位内皮细胞 Klf2 高表达，上调 Foxp1，减少炎症小体激活，降低血管单核/巨噬细胞浸润和促炎泡沫细胞形成，最终减少动脉粥样硬化斑块的形成。本项目揭示了 Klf2-Foxp1 转录因子网络调控血管壁炎性小体激活在动脉粥样硬化发生发展中新机制，阐明了他汀抗动脉粥样硬化的新机制，为今后动脉粥样硬化预防提供了新思路。目前该项结果已发表于Circulation Research杂志中。

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