人oxLDL自身免疫复合物的体外致动脉粥样硬化作用

目的：观察oxLDL自身免疫复合物对U937巨噬样细胞泡沫化和活化的影响，以探讨oxLDL免疫学反应致动脉粥样硬化的机制。方法：采用密度离心法从健康人血浆中提取低密度脂蛋白（LDL），用铜离子氧化成oxLDL；用亲和层析法从136例住院患者血清中提取oxLDL自身抗体。在体外制成2种形式不同的免疫复合物：聚乙二醇沉淀的不溶性免疫复合物（PEG-IC）和RBC吸附的可溶性免疫复合物（RBC-IC），把这2种免疫复合物加至U937巨噬样细胞的培养基中，以oxLDL作阳性对照，并用热聚合人γ球蛋白（HAGG）封闭Fcγ受体作阻断对照，检测干预后的各组U937巨噬样细胞内胆固醇和胆固醇酯及培养基中基质金属蛋白酶-1（MMP-1）的水平。结果：RBC-IC干预组与RBC吸附oxLDL（RBC-oxLDL）干预组比较，U937巨噬样细胞培养基中MMP-1蛋白表达［（0.769±0.030) ng/ml vs (0.513±0.034) ng/ml，P＜0.01］和细胞内胆固醇酯蓄积［（20.271±1.668) μg/mg vs (17.226±1.298) μg/mg，P＜0.05］明显升高；而在PEG-IC组这种作用则更为明显，且呈剂量依赖性。用10mg/ml的HAGG封闭Fcγ受体后，MMP-1的水平下降约71%，其对巨噬样细胞泡沫化和活化的作用都受到明显的抑制。结论：oxLDL自身免疫复合物能够促进巨噬细胞泡沫化和活化， 其参与动脉粥样硬化的过程可能是通过Fcγ受体途径来实现的。

Proatherogenic effects of immune complexes of human oxLDL in vitro

OBJECTIVE: To observe the effects of immune complexes (IC) prepared from human oxidized density lipoprotein (oxLDL) antibodies and human oxLDL on the foam cell forming and the macrophage activation, and to further uncover the possible mechanisms of immune complexes contributing to the atherosclerosis occurrence. METHODS: The immune complexes of human oxLDL and purified human oxLDL antibodies were added to culture U937 cells by protocols: polyethylene glycol-precipitated insoluble IC (PEG-IC) and IC immobilized by absorption to red blood cells (RBC-IC). With oxLDL as controls and heat-aggregated gamma globulin as an inhibitor of Fc gamma receptor, we measured the cholesterol ester, total cholesterol of the cellular extracts, and quantified the secreted MMP-1 of supernatants from U937 cells. RESULTS: A significant increase of MMP-1 release (0.769 +/- 0.030) ng/ml vs (0.513 +/- 0.034) ng/ml, P < 0.01] and a higher level of cholesterol ester accumulation (20.271 +/- 1.668) microg/mg protein vs (17. 226 +/- 1.298 ) microg/mg protein, P < 0.05] in U937 cells incubated with RBC-IC were observed, compared with those incubated with RBC-oxLDL. However, the above quantative difference between the cholesterol ester accumulation induced by oxLDL and insoluble PEG-IC was even more striking, and cholesterol ester accumulation was dosage-dependent. Heat-aggregated gamma globulin (10 mg/ml) as an inhibitor of Fc gamma receptors competitively inhibited cholesterol ester accumulation and decreased PEG-IC stimulating MMP-1 secretion to 71%. CONCLUSION: Immune complexe of ox-LDL can transform macrophages into foam cells and activted macrophages. The immunological function of oxLDL is involved in the process of atherosclerosis occurrence.