肠道细菌AKK通过上调2-AG调控血管周围脂肪组织炎症抑制动脉粥样硬化的机制研究

Atherosclerosis (AS) is a low-grade chronic inflammatory vascular disease. Gut microbiota dysbiosis tightly correlated with chronic inflammation of AS, but little is known about the specific gut bacterium that regulates AS development and the mechanism involved. In previous work, we found that the levels of Akkermansia muciniphila (AKK) in fecal samples of AS patients and high fat diet-fed apoE-/- mice were obviously lower than those in normal subjects and normal chow diet-fed apoE-/- mice. While in high fat diet-fed apoE-/- mice, AKK given by daily oral gavage induced 2-arachidonoylglycerol (2-AG) expression in intestinal mucosa, inhibited perivascular adipose tissue (PVAT) inflammation, accelerated PVAT browning, and attenuated AS lesion. Based on these, this project tries to: 1. Study whether AKK inhibits high fat diet-fed apoE-/- mice AS development, and whether it regulates plaque inflammation. 2. Demonstrate how AKK regulates PVAT differentiation, inflammatory cells infiltration, adipokine and cytokine secretion. And detect whether AKK protects against AS by regulating PVAT inflammation and paracrine function using PVAT implantation technique. 3. Clarify the rate-limiting role of 2-AG in AKK protecting intestinal barrier function, inhibiting LPS enters into the body, and inhibiting AS development by up-regulating and down-regulating 2-AG in vivo and in vitro. This project is trying to disclose the role of AKK in inhibiting AS development and the mechanism involved, which might uncover a new target for AS prevention and treatment.

动脉粥样硬化（AS）是一种慢性炎症性血管疾病，肠道菌群失调与AS炎症密切相关，但调控AS的具体肠道菌及相关机制所知甚少。课题组发现AS患者粪便中肠道细菌Akkermansia muciniphila（AKK）量明显减少，而apoE-/-小鼠在高脂饮食基础上灌胃给予AKK可促进内源性大麻素2-arachidonoylglycerol（2-AG）在肠粘膜中的表达，抑制血管周围脂肪组织（PVAT）炎症，促进其棕色化，并抑制AS发展。基于此，本项目拟：1.研究AKK对apoE-/-小鼠AS进展和炎症浸润的调控作用；2.研究AKK对PVAT形态、棕色化、炎症浸润和功能的调控作用，应用PVAT移植技术明确AKK是否通过调控PVAT炎症和棕色化保护AS；3.通过体内和体外过表达和抑制2-AG表达，阐明2-AG在AKK保护肠道屏障功能，阻断LPS进入体内，抑制AS发展中发挥限速功能，为AS防治提供新方向。

动脉粥样硬化（AS）是一种慢性炎症性血管疾病，肠道菌群失调与AS炎症密切相关，但调控AS的具体肠道菌及相关机制所知甚少。青海大部分地区属于高原地区，藏族人群世居于此地区。本项目完成了肠道菌Akkermansia muciniphila（AKK）对apoE-/-小鼠AS进展和炎症浸润调控作用以及其对血管周围脂肪组织（PVAT）形态、棕色化、炎症浸润和功能调控作用的研究。比较了高原世居藏族和不同海拔居住汉族冠心病（CHD）患者和高血压患者肠道菌群的特征以及CHD患者肠道菌群特征与饮食结构之间的关系。除此之外，我们还研究了无毒型B. fragilis对apoE-/-小鼠外周血中CD4+T细胞亚群的调控作用。结果表明：1）AKK抑制apoE-/-小鼠AS进展和局部炎症因子浸润，抑制apoE-/-小鼠血糖升高，但是对小鼠血脂和外周血CD4+T细胞比例的变化无调控作用。而且AKK抑制apoE-/-小鼠PVAT棕色化和PVAT局部炎症浸润，并诱导肠粘膜2-AG表达；2）高原世居藏族CHD患者肠道菌群呈现出保护性特征并与其饮食构成相关；3）高原世居藏族高血压患者肠道菌群呈现出一定特征；4）无毒型B. fragilis降低高脂饮食apoE-/-小鼠循环中Th1和Th17细胞比例及其功能性细胞因子的表达，诱导Treg细胞比例升高及其功能性细胞因子的表达。通过本项目的研究，我们初步阐明了AKK调控AS进程的机制，AKK有望作为治疗AS相关性疾病的生物活性药物应用于临床。无毒型B. fragilis也有潜在的抑制CD4+T细胞亚群相关炎症性疾病的可能性。而我们初次对高原世居CHD和高血压患者肠道菌群独特特征的描述，具有地域特征，为高原医学的发展舔砖加瓦。