中文摘要：

目的 探讨低密度脂蛋白循环免疫复合物（LDL-IC）对U937细胞基质金属蛋白酶-1（MMP-1）及其抑制物组织金属蛋白酶抑制剂-1（TIMP-1）mRNA表达的影响。方法 分别采用不同浓度的天然低密度脂蛋白（N-LDL）、氧化低密度脂蛋白（Ox-LDL）及其免疫复合物作用U937细胞，通过半定量RT-PCR分析U937细胞中MMP-1和TIMP-1基因表达的变化。结果 正常U937细胞几乎不表达MMP-1，而高表达TIMP-1。N-LDL对细胞MMP-1和TIMP-1 mRNA表达没有影响。Ox-LDL能引起MMP-1轻度表达，但显著地下调TIMP的表达；而天然、氧化LDL的循环免疫复合物均非常显著地增加MMP-1和降低TIMP-1的mRNA表达（P〈0．001），且较Ox-LDL对MMP-1的作用更为显著（P〈0．001），并具剂量效应。结论 N-LDL-IC和Ox-LDL-IC增强U937细胞MMP-1 mRNA表达，下调其抑制物TIMP-1的表达。

英文摘要：

Objective To explore the effects of low density lipoprotein （LDL） containing immune complexes （IC） on the mRNA expression of matrix metalloproteinase-1 （ MMP-1 ） and matrix metalloproteinase-1 （ TIMP-1 ） in U937 cells. Methods U937 cells were incu- bated with native LDL,oxidized LDL or LDL-IC ,respectively. mRNA expression of matrix metalloproteinase-1 （MMP-1） and tissue inhibitor of metalloproteinase-1 （TIMP-1） in U937 cells were measured by reverse transcriptase polymerase chain reaction （PT-PCR）. Results Normal U937 cells hardly expressed MMP-1 ,but highly expressed TIMP-1. N-LDL had no effect on the expression of MMP-1 and TIMP-1 mRNA. Ox-LDL can induce slightly expression of MMP-1 and markedly down-regulate expression of TIMP-1. Similarly, nature and oxidized LDL-IC had significantly more effect on the mRNA expressions of MMP-1 and TIMP-1 than that of control （ P 〈 0.001 ）. Conclusion LDL-IC stimulated the expression of MMP-1 mRNA and down-regulated the expression of TIMP-I mRNA in U937 cells.