氢分子调控巨噬细胞炎性极化和胆固醇代谢转运的分子机制

The pathological lesion of atherosclerosis (As) is characterized by the arterial intimal macrophage and cholesterol accumulation. We have found that molecular hydrogen (H2) treatment promotes high-density lipoprotein (HDL)-mediated cholesterol efflux from macrophage-derived foam cells in golden hamster model and patients with metabolic syndrome or hyperlipidemia. Further, we have confirmed H2 inhibits atherosclerotic plaque formation and increases the plaque stability in mice, which is attributable to the inhibitory effects of H2 on inflammation and macrophage accumulation, whereas the molecular mechanism remains unknown. Therefore, we hypothesize that H2 may modulate the pathways of macrophage polarization and cholesterol metabolism by regulating membrane lipids. In this project, by using animal and macrophage models, we aimed to determine the effects of H2 on vascular macrophage phenotype, cholesterol metabolism，and lipidome of cell membrane, lipid rafts and non-rafts. We will focus on the regulatory effects of H2 on inflammatory signal pathway, scavenger receptors (SRs) and ABC transproters A1 and G1 pathway in response to lipid homeostasis, cell membrane lipidome, the distribution of membrane receptors, and changes of HDL particle component and its biological function to promote cholesterol efflux from macrophages. The accomplishment of this project will help to clarify the primary target of H2 and provide the experimental basis for the application of H2 in preventing and treating atherosclerotic vascular disease.

动脉内膜巨噬细胞(Mφ)和胆固醇聚集是粥样硬化(As)及易损斑块形成的重要病理特征。我们前期发现，氢气分子在金黄地鼠模型、代谢综合征和高脂血症患者中皆促进巨噬源性泡沫细胞胆固醇溢出；且氢气在小鼠模型中明显抑制斑块处炎症反应和Mφ聚集，从而减少早期斑块形成和增加晚期斑块稳定性。但其分子机制仍不清楚。我们设想氢分子可通过膜脂保护调节Mφ炎性极化信号通路和胆固醇代谢转运途径。故本项目使用As动物模型和多种Mφ模型，通过液相色谱串联质谱、同位素标记、流式细胞分选、免疫荧光共定位等方法，观察氢气对Mφ极化、胆固醇代谢、胞膜脂筏和非脂筏区脂质组成及受体分布的影响，以阐明氢气在调控氧化低密度脂蛋白等介导的炎症信号通路、胆固醇代谢转运途径和泡沫细胞形成，以及影响HDL介导泡沫细胞胆固醇溢出的分子机制，并明确氢气相关作用的关键生物分子靶点。期待为氢气应用于As病变的防治提供新的思路和依据。

动脉内膜巨噬细胞(Mφ)和胆固醇聚集是粥样硬化(As)及易损斑块形成的重要病理特征。我们前期发现，氢气分子在金黄地鼠模型、代谢综合征和高脂血症患者中皆促进巨噬源性泡沫细胞胆固醇溢出；且氢气在小鼠模型中明显抑制斑块处炎症反应和Mφ聚集，从而减少早期斑块形成和增加晚期斑块稳定性。但其分子机制及氢分子对其他代谢相关疾病的作用仍不清楚。本项目发现，1）H2能够抑制炎症诱导的TLR4受体的脂筏易位，沉默TLR4基因表达可阻断炎症状态下的NF-κB激活，以及巨噬细胞向M1表型极化，说明TLR4受体在AS炎症反应中起着重要的作用，同时H2可通过调节胞膜脂质组成，干扰炎症信号传导通路中最上游的信号分子TLR4受体的脂筏易位，从而抑制炎症状态下的巨噬细胞M1极化。2）本项目发现，氢气显著降低T2DM患者胰岛素抵抗指数，增加胰岛素敏感性，降低空腹胰岛素水平，并改善T2DM患者HDL功能，包括抗炎、抗氧化、抗凋亡、促胆固醇逆向转运、促骨骼肌摄取葡萄糖等。进一步分析发现，氢气改善HDL功能与其减少糖化HDL和氧化HDL相关，氢气增加T2DM模型胰岛素敏感性与其诱导葡萄糖利用器官自噬反应有关。3）短时吸入氢氧混合气能显著增加健康人面部和手部皮肤血流灌注量，可以改善T2DM小鼠皮肤、胰腺微循环功能障碍。4）高浓度氢气吸入可改善非酒精性脂肪肝患者肝功能，降低其血胆固醇水平，增强HDL功能，并改善血浆炎症状态。