Department of Infection, Immunity and Cardiovascular Disease, Bateson Centre for Lifecourse Biology, INSIGNEO Institute for Cardiovascular Medicine, Faculty of Medicine Dentistry and Health, Beech Hill Road, University of Sheffield, Sheffield S10 2RX, UK.
Cardiovasc Res. 2020 Jun 1;116(7):1300-1310. doi: 10.1093/cvr/cvz235.
Atherosclerosis develops near branches and bends of arteries that are exposed to disturbed blood flow which exerts low wall shear stress (WSS). These mechanical conditions alter endothelial cells (EC) by priming them for inflammation and by inducing turnover. Homeobox (Hox) genes are developmental genes involved in the patterning of embryos along their anterior-posterior and proximal-distal axes. Here we identified Hox genes that are regulated by WSS and investigated their functions in adult arteries.
EC were isolated from inner (low WSS) and outer (high WSS) regions of the porcine aorta and the expression of Hox genes was analysed by quantitative real-time PCR. Several Hox genes (HoxA10, HoxB4, HoxB7, HoxB9, HoxD8, HoxD9) were significantly enriched at the low WSS compared to the high WSS region. Similarly, studies of cultured human umbilical vein EC (HUVEC) or porcine aortic EC revealed that the expression of multiple Hox genes (HoxA10, HoxB9, HoxD8, HoxD9) was enhanced under low (4 dyn/cm2) compared to high (13 dyn/cm2) WSS conditions. Gene silencing studies identified Hox genes (HoxB9, HoxD8, HoxD9) that are positive regulators of inflammatory molecule expression in EC exposed to low WSS, and others (HoxB9, HoxB7, HoxB4) that regulated EC turnover. We subsequently focused on HoxB9 because it was strongly up-regulated by low WSS and, uniquely, was a driver of both inflammation and proliferation. At a mechanistic level, we demonstrate using cultured EC and murine models that bone morphogenic protein 4 (BMP4) is an upstream regulator of HoxB9 which elicits inflammation via induction of numerous inflammatory mediators including TNF and downstream NF-κB activation. Moreover, the BMP4-HoxB9-TNF pathway was potentiated by hypercholesterolaemic conditions.
Low WSS induces multiple Hox genes that control the activation state and turnover of EC. Notably, low WSS activates a BMP4-HoxB9-TNF signalling pathway to initiate focal arterial inflammation, thereby demonstrating integration of the BMP and Hox systems in vascular pathophysiology.
动脉粥样硬化发生于易受血流紊乱影响的动脉分支和弯曲处，这种血流紊乱会导致壁面切应力（WSS）降低。这些机械条件通过使内皮细胞（EC）炎症前体化和诱导其更新来改变内皮细胞。同源盒（Hox）基因是参与胚胎前后和近-远轴模式形成的发育基因。在此，我们鉴定了受 WSS 调控的 Hox 基因，并研究了它们在成年动脉中的功能。
从猪主动脉的内（低 WSS）部和外（高 WSS）部分离 EC，并通过定量实时 PCR 分析 Hox 基因的表达。与高 WSS 区域相比，几个 Hox 基因（HoxA10、HoxB4、HoxB7、HoxB9、HoxD8、HoxD9）在低 WSS 区域显著富集。同样，对培养的人脐静脉内皮细胞（HUVEC）或猪主动脉内皮细胞的研究表明，多个 Hox 基因（HoxA10、HoxB9、HoxD8、HoxD9）的表达在低（4 dyn/cm2）WSS 条件下比高（13 dyn/cm2）WSS 条件下增强。基因沉默研究确定了 Hox 基因（HoxB9、HoxD8、HoxD9），它们是在低 WSS 下暴露的 EC 中炎症分子表达的正调节剂，其他（HoxB9、HoxB7、HoxB4）调节 EC 更新。随后，我们将重点放在 HoxB9 上，因为它受低 WSS 的强烈上调，并且是炎症和增殖的双重驱动因素。在机制水平上，我们使用培养的 EC 和小鼠模型证明，骨形态发生蛋白 4（BMP4）是 HoxB9 的上游调节剂，通过诱导包括 TNF 在内的众多炎症介质，并激活下游 NF-κB，引发炎症。此外，在高胆固醇血症条件下，BMP4-HoxB9-TNF 通路被增强。
低 WSS 诱导多个 Hox 基因，这些基因控制 EC 的激活状态和更新。值得注意的是，低 WSS 通过激活 BMP4-HoxB9-TNF 信号通路引发局部动脉炎症，从而证明了 BMP 和 Hox 系统在血管病理生理学中的整合。
