钙离子信使通路在溶血卵磷脂促进巨噬泡沫细胞胆固醇外流中的作用

Effect of Calcium Signaling Pathway on Cholesterol Efflux Promoted by Lysophosphatidylcholine from Macrophage Foam Cells

探讨溶血卵磷脂对巨噬泡沫细胞胆固醇外流影响及第二信使细胞内钙在这一效应中所起的作用 ,为动脉粥样硬化的有效防治提供理论依据。分离培养小鼠腹腔巨噬细胞 ,用乙酰化低密度脂蛋白负载使之形成巨噬泡沫细胞 ;酶学荧光法检测细胞胆固醇外流 ,荧光分光光度法检测细胞内钙 ,分别螯合细胞外钙和抑制蛋白激酶C活性后检测溶血卵磷脂对巨噬泡沫细胞胆固醇外流的影响。结果发现 ,在 10～ 80 μmol/L浓度范围内 ,各剂量溶血卵磷脂组培养基中游离胆固醇浓度明显高于对照组。各剂量溶血卵磷脂引起胞内钙离子浓度升高 ,当用EGTA螯合细胞外钙后 ,溶血卵磷脂不引起胞内钙离子浓度升高 ,以及不再促进巨噬泡沫细胞胆固醇外流。当蛋白激酶C活性受抑制后 ,溶血卵磷脂不再促进细胞胆固醇外流。溶血卵磷脂在 10～ 80 μmol/L浓度范围内能够促进巨噬泡沫细胞胆固醇外流 ,这一效应与胞内第二信使细胞内钙浓度升高有关 ,而且钙离子 -蛋白激酶C这一信使通路介导了溶血卵磷脂促进巨噬泡沫细胞胆固醇外流效应。

Aim To explore the effect of lysophosphatidylcholine on cholesterol efflux from macrophage foam cells, and the function of calcium signaling pathway on this effect. Methods Macrophage foam cells were harvested from female mice weighing 25～30 g. Human LDL was separated from healthy subjects and isolated by differential ultracentrifugation. LDL was acytylated to ac-LDL to convert macrophage to foam cells. Cholesterol mass of medium and cells were quantified by enzymetic fluorometry. Intracellular calcium concentration was measured by fluorometry. Involvement of intracellular calcium and PKC on effect of cholesterol efflux from macrophages by LPC was measured by applying EGTA and H 7 to adduct extracellular calcium and to inhibit the activity of PKC, then observed whether cholesterol efflux could occur. Results Within the dosage of 10～80 μmol/L, LPC obviously promoted cholesterol efflux from macrophage foam cells, and LPC increased intracellular calcium concentration. When extracellular calcium was cleared by EGTA or PKC activity was inhibited by H 7, LPC could not promote cholesterol efflux from macrophage foam cells. Conclusions LPC could promote cholesterol efflux from macrophage foam cells within the dosage of 10～80 μmol/L, this effect is related to influx of intracellular calcium. Calcium-PKC signaling pathway induced LPC's effect on cholesterol efflux from macrophage foam cells.