单核细胞来源的微颗粒通过PPAR-α-SR-BI途径促进RAW264.7泡沫细胞形成的研究

Monocyte-derived microparticles promote RAW264.7 foam cell formation via the PPAR-α-SR-BI pathway

目的研究单核细胞来源微颗粒对泡沫细胞形成的影响。方法用氧化低密度脂蛋白或者低密度脂蛋白刺激RAW264.7细胞形成泡沫细胞,采用油红染色法对阳性的泡沫细胞进行染色,通过real-time PCR和Western印迹法测定微颗粒对RAW264.7细胞的受体或酶CD36、SR-A、ACAT1、nCEH、ABCA1、ABCG1、SR-BI的影响。结果单核细胞来源的微颗粒影响RAW264.7细胞的活力;单核细胞来源的微颗粒可促进RAW264.7细胞的泡沫化形成;低浓度(20μl/ml)微颗粒可轻微促进巨噬细胞对低密度脂蛋白的吞噬,但对氧化低密度脂蛋白的吞噬却没有影响;过氧化物酶体增殖物激活受体-α(PPAR-α)的激动剂可增强泡沫细胞形成,拮抗剂作用相反。单核细胞来源微颗粒可下调SR-BI在mRNA和蛋白质水平的表达。PPAR-α激动剂可下调单核细胞来源微颗粒对RAW264.7巨噬细胞中SR-BI蛋白表达,PPAR-α拮抗剂没有影响。结论单核细胞来源的微颗粒通过引起过氧化物酶体增殖物激活受体-α的表达,进而使巨噬细胞表面SR-BI的表达降低,从而促进RAW264.7泡沫细胞形成。

Objective To investigate the role o f the monocyte-derived microparticles （mono-MPs） in the formation of foam c e l ls. Methods Mouse macrophage RAW264. 7 cells were stimulated with oxidized low density lipoprotein or low density lipoprotein to form foam c e l ls. Positive foam c e l ls were stained with oi l red staining. Real-time PCR and Western blotting were used to determine RAW264. 7 Cell receptor or enzyme CD36, SR- A , ACAT1 , nCEH, ABCA1 , ABCG1 , SR- B I. Results Mono- MPs affected the activity of RAW264. 7 c e l ls. Mono-MPs promoted the formation o f RAW264. 7 foam cells; low concentration （20 μl/ml） microparticles slightly promoted the phagocytosis o f macrophages to low-density lipoproteins, but did not affect the intake o f oxidized low-density lipoproteins. Peroxisome proliferator-activated receptor-alpha （PPAR- α ） agonists enhanced foam cel ls formation, while the e f fe c t of PPAR-a antagonist was reversed. Mono-MPs reduced the expression o f SR-BI mRNA and protein le v e ls. PPAR-a agonists reduced the expression o f SR-BI protein in RAW264. 7 macrophages, while PPAR-α antagonist had no effect. Conclusion The mono-M P s, causing activation of the PPAR- α , induce the RAW264. 7 foam c e l l formation via lipid uptake and the PPAR- α - SR-BI pathway.