脂肪因子chemerin通过ChemR23依赖性途径对动脉粥样硬化发生、发展和斑块稳定性影响及其作用机制的研究

Chemerin was a recently identified novel adipokine that has a role in adaptive and innate immunity and is known to function as a chemoattractant that promotes recruitment of immune cells to sites of injury. Interestingly, the chemoattractant function of chemerin completely depends on chemerin R, and disappeared in ChemR23-/- mice. In previous studies, we found that ChemR23 were expressed in endothelial cells (ECs), smooth muscle cells (SMCs) and macrophages. Chemerin and ChemR23 were both demonstrated in atherosclerotic plaque in ApoE-/- mice. And a higher level was found in plaque with more prone to rupture, suggesting the potential role of chemerin and ChemR23 in the development of AS and in the instability of atherosclerotic plaque.. Although accumulating studies suggest a plausible role of chemerin in metabolic disorders, its role in AS still remains unclear. We presume that the plausible mechanisms of the relationship between chemerin and AS could be as follows: 1) The high level of chemerin in atherosclerotic lesion could attract more immune cells through ChemR23 dependent signal pathway with contribute to the remodeling of the blood vessel wall, 2) The alteration of insulin sensitivity and glucose uptake in adipocytes and other vascular cells could contribute to development of AS, 3) Chemerin could directly affect the inflammatory status in vacular ECs and SMCs as well as macrophages via ChemR23 dependent signal pathway. . To explore the effect of chemerin on AS and plaque instability and to clarify the effect is ChemR23 dependent, we will use ApoE-/- and ApoE-/-/ChemR23-/- mice to construct atherosclerotic model in vivo. Further, we will explore the effect of chemerin/chemR23 on the cultured ECs, SMCs and macrophages in vitro.

Chemerin是近年来发现的一种在先天性免疫和固有免疫中均发挥作用的脂肪因子，具有趋化免疫细胞向损伤部位聚集的作用。而且，这种趋化作用是具有受体依赖性的。我们在前期研究中发现，ChemR23作为chemerin的一种受体在血管内皮细胞、平滑肌细胞及巨噬细胞中均有表达；更有意思的是chemerin、chemR23在动脉粥样硬化(AS)斑块中也均表达，且在易损斑块中表达更高。我们拟通过构建ApoE-/-小鼠和ApoE-/-/ChemR23-/-双敲小鼠AS斑块形成及斑块不稳定模型，同时对其给予chemerin干预的方式，明确chemerin/ChemR23在AS及斑块稳定性中的作用；体外拟通过分别对培养的巨噬细胞、内皮和平滑肌细胞进行chemerin和ChemR23干预的方式，明确chemerin/ChemR23在上述细胞中的作用和信号通路，以期进一步明确二者在AS及斑块稳定性中的作用机制。

Chemerin 是近年来发现的一种在先天性免疫和固有免疫中均发挥作用的脂肪因子，具有趋化免疫细胞向损伤部位聚集的作用。研究发现，这种趋化作用是具有受体依赖性的，在ChemR23-/-缺失的小鼠中这种趋化作用消失。本研究的主要目的是探讨Chemerin/ChemR23在动脉粥样硬化斑块的发生、发展及其稳定性中的作用，分为体内和体外两部分实验。在体外实验中我们采用重组Chemerin分别刺激血管内皮细胞、平滑肌细胞、单核细胞-巨噬细胞的方式，发现Chemerin能够促进内皮细胞的通透性，诱导其NO的释放，该作用是通过激活ChemR23/PI3K/AKT/eNOS信号通路实现的；Chemerin/ChemR23能够诱发平滑肌细胞的增殖，促进细胞迁移，同时降低该细胞的葡萄糖摄取能力；Chemerin/ChemR23能够促进单核细胞的趋化-粘附，增加巨噬细胞炎性因子分泌和吞噬能力，却未对巨噬细胞的凋亡产生明显影响。在体内实验中，采用高脂喂养的方式构建小鼠主动脉粥样硬化斑块模型，分别于高脂后4周、6周、8周及12周末对ChemR23-/-小鼠、ApoE-/-小鼠和ChemR23-/-ApoE-/-小鼠的主动脉斑块进行比较。结果发现高脂4周后各组小鼠体内的Chemerin水平较各自对照组均有明显升高，此升高一直维持至至12周末。高脂喂养未能引起ChemR23-/-敲基因小鼠主动脉斑块的形成，而ApoE-/-小鼠和ChemR23-/-ApoE-/-小鼠斑块形成明显, 但两组斑块在形态、大小上却未存在明显差异。在斑块稳定性实验中，我们采用8周龄小鼠，高脂喂养2周后对其行颈动脉套管，继续高脂喂养10周的方式构建颈动脉斑块模型。结果发现ApoE-/-小鼠和ChemR23-/-小鼠颈动脉斑块形成明显；两组斑块在大小上未存在显著性差异，但较ApoE-/-小鼠而言，ChemR23-/-ApoE-/-小鼠斑块内平滑肌细胞数量明显增多，巨噬细胞数量和脂质核心的面积明显减少，斑块内炎性因含量降低。结论：（1）Chemerin/ChemR23在动脉粥样硬化斑块的发生、发展未发挥明显作用；（2）Chemerin/ChemR23能够降低动脉粥样硬化斑块稳定性。本课题的意义在于明确了Chemerin/ChemR23途径在动脉粥样硬化发生、发展和稳定性中的作用，为日后的相关研究奠定了基础。