肽酶抑制蛋白16通过调控血管紧张素Ⅱ-1型受体抑制高血压及血管重构的作用和机制研究

Activation of angiotensin-aldosterone system is an important cause of hypertension and related vascular remodeling. There are still many unknown pathogenesis, and the existing drug treatment has its limitations. Our previous study found for the first time that serum peptidase inhibitor 16 (PI16) levels in patients with hypertension were significantly lower than those in the normal population, suggesting that PI16 may be closely related to hypertension. In vivo experiments show that overexpression of PI16 can significantly reduce AngII-induced hypertension and vascular remodeling, and PI16 can bind to angiotensin II type 1 receptor (AT1R). However, its specific mechanism of action is still unclear. To this end, we hypothesized that PI16, by binding to AT1R, inhibits the activity of AT1R, blocks the activation of the AngII/AT1R pathway from upstream, and exerts a role in lowering blood pressure and improving vascular remodeling. In order to verify this hypothesis, we will clarify the specific mechanism of PI16 inhibiting AT1R through PI16 transgenic mice, smooth muscle-specific knockout PI16 mice and primary isolated mouse smooth muscle cells, and synthesize short peptides that bind PI1 to AT1R. To validate its biological effects and provide clues for exploring new peptide drugs for the treatment of hypertension and vascular remodeling.

血管紧张素-醛固酮系统激活是引起高血压及相关血管重构的重要原因，其发病机制仍存在许多未知，现有药物治疗效果有其局限性。我们前期研究首次发现高血压患者血清肽酶抑制蛋白16（PI16）含量显著低于正常人群，提示PI16可能与高血压疾病关系密切。在体实验表明过表达PI16能够显著降低AngⅡ诱导的高血压和血管重构，且PI16可以与血管紧张素Ⅱ-1型受体（AT1R）结合。但其具体作用机制尚不清楚。为此我们提出假说：PI16通过与AT1R结合，抑制AT1R的活性，从上游阻断AngⅡ/AT1R通路的激活，发挥降低血压以及改善血管重构的作用。为了验证这一假说我们将通过PI16转基因小鼠、平滑肌特异性敲除PI16小鼠及原代分离的小鼠平滑肌细胞等层面，阐明PI16抑制AT1R具体机制，并通过合成PI16与AT1R结合的短肽验证其生物学效应，为探索新的治疗高血压及血管重构的多肽类药物提供线索。

高血压已成为全球患病率第一的慢性非传染性疾病，是很多临床高发心血管疾病的共同危险因素，其引起的大动脉硬化与高血压本身相辅相成，但其机制尚不明确。肽酶抑制蛋白16（peptidase inhibitor 16，PI16）在高血压及大动脉重构中的作用尚不清楚。本研究旨在探讨PI16在高血压及大血管重构中的作用以及PI16调控血管紧张素II 1型受体（angiotensin II type 1 receptor，AT1R）表达的分子机制。我们采用ELISA法测定高血压和非高血压患者血清中PI16的水平，结果显示高血压患者血浆PI16水平下降，并与脉搏波速度（pulse wave velocity，PWV）呈负相关。与WT小鼠相比，PI16转基因（Tg）小鼠的主动脉厚度、胶原沉积及纤维相关标志物结缔组织生长因子（CTGF）、胶原水平显著降低，而PI16敲除（PI16-/-）小鼠Ang II输注后，其CTGF、胶原水平显著升高。机制上，PI16通过氨基酸41-50直接与AT1R相互作用，从而促进AT1R对β-arrestin的募集，增加AT1R内化。进一步PI16通过促进内化后AT1R的泛素化修饰，下调AT1R的表达。给予Ang II诱导的小鼠及自发性高血压大鼠人工合成的PI16与AT1R结合域的短肽后，血压水平及主动脉重构程度均得到显著改善。综上所述，PI16通过氨基酸41-50基序与AT1R发生相互作用，下调AT1R的表达水平，从而改善高血压及血管重构。PI16-AT1R-β-arrestin轴可能为高血压和主动脉重构提供潜在的治疗靶点，PI16和AT1R的结合域短肽可能成为临床上治疗高血压和大动脉硬化的潜在药物。