转化生长因子β1对巨噬细胞清道夫受体-A表达的影响

目的　探讨转化生长因子β1(TGF β1)对巨噬细胞清道夫受体 A(ScR A)的影响。 方法　利用鼠单克隆抗人TGF β1抗体 (AntiTGF β1Ab) ,细胞培养 ,受体摄取配体及Northernblot印迹方法 ,观察AntiTGF β1Ab对人类单核细胞株 (THP 1细胞 )由来巨噬细胞受体摄取乙酰化LDL(Ac LDL)以及对ScR AmRNA表达的影响。结果　巨噬细胞对Ac LDL的摄取随AntiTGF β1Ab浓度的增加而增加。Ac LDL结合量 (ng mgprotein)与对照组 (36 89± 1 31)比较 ,投用 1 0、3 0 μg mlAntiTGF β1Ab ,其Ac LDL结合量分别为 45 5 6± 0 81(P <0 0 5 ) ,6 0 94± 1 17(P <0 0 1)。摄入量 (ng mgprotein)与对照组 (35 0 5 9± 6 0 3)比较 ,分别为 40 3 48± 4 37(P <0 0 5 ) ,5 0 3 6 1± 11 77(P <0 0 1)。降解量 (ng mgprotein)与对照组 (1382 0 6± 3 0 9)比较 ,分别为 16 17 71± 39 0 8,1934 84± 42 6 7(P<0 0 1)。巨噬细胞ScR AmRNA表达随AntiTGF β1Ab浓度的增加而增强。与空白对照组比较 ,投用 1 0、3 0 μg mlAntiTGF β1Ab ,其ScR AmRNA表达分别增强 15 7%和 38 2 %。结论　TGF β1抑制THP 1细胞由来巨噬细胞ScR A的表达。TGF β1的这种作用可能参与了动脉硬化形成和发展的病理过程     

血浆脂蛋白(a)对巨噬细胞摄取乙酰化低密度脂蛋白的影响

目的　研究血浆脂蛋白 (a) [lipoprotein(a) ,Lp(a) ]对巨噬细胞结合 ,摄入及降解乙酰化低密度脂蛋白 (acetylatedlowdensitylipoprotein ,Ac LDL) ,清道夫受体 A (scavengerreceptor A ,ScR A)和ScR B的影响。方法　利用人类单核细胞株 (THP 1细胞 )源的巨噬细胞培养 ,受体摄取配体及Northern印迹方法 ,观察Lp(a)对巨噬细胞受体摄取Ac LDL以及对巨噬细胞ScR A和ScR BmRNA表达的影响。结果　THP 1细胞源的巨噬细胞对Ac LDL的结合量随Lp(a)浓度 (0 ,10 ,2 5 ,5 0及 10 0 μg/ml)的增加而增加 ,而天然LDL对此无影响。与对照组比较 [Lp(a)非投用组 ],投用 5 0μg/mlLp(a)时 ,巨噬细胞对Ac LDL结合量 (binding)增加 2 6 9.2 5 %(P <0 .0 1) ,对Ac LDL的摄入量 (uptake)增加5 9.46 %(P <0 .0 1) ,对Ac LDL的降解量 (degradation)增加 5 5 .77%(P<0 .0 1) ,且巨噬细胞ScR AmRNA表达明显增强 ,与对照组 [Lp(a)非投用组 ]比较增强 43.5 6 %,而Lp(a)并不影响ScR BmRNA的表达。结论　Lp(a)可增加THP 1细胞源的巨噬细胞结合、摄入及降解Ac LDL ,这种作用可能通过Lp(a)增强巨噬细胞ScR A基因的表达来实现。     

肺炎衣原体通过上调清道夫受体A1诱导THP-1源性泡沫细胞形成

目的观察清道夫受体A1和CD36在肺炎衣原体诱导THP-1源性泡沫细胞形成中的作用。方法给予不同浓度的肺炎衣原体(1×105～1×106IFU)感染THP-1源性巨噬细胞0～72h。运用油红O染色观察细胞质内脂滴的变化,酶荧光学法检测细胞内胆固醇酯含量的变化。分别运用逆转录聚合酶链反应和Western-Blot检测清道夫受体A1和CD36的mRNA和蛋白表达。结果高浓度的肺炎衣原体(5×105和1×106IFU)感染负荷低密度脂蛋白的THP-1源性巨噬细胞48h后,细胞质内的脂滴明显增多,胆固醇酯占总胆固醇百分比明显增加(>50%)。在负荷低密度脂蛋白的THP-1源性巨噬细胞上,肺炎衣原体感染呈浓度和时间依赖性地上调道夫受体A1 mRNA和蛋白表达,但不影响CD36 mRNA和蛋白表达。结论清道夫受体A1表达上调是肺炎衣原体诱导THP-1源性泡沫细胞形成的机制之一,这可能为进一步阐明肺炎衣原体感染促进动脉粥样硬化发生发展提供一个新的理论依据。     

辣椒来源外泌体样纳米囊泡通过ERK1/2通路拮抗巨噬细胞向泡沫细胞转化

目的]研究辣椒来源外泌体样纳米囊泡(CDELN)抑制氧化型低密度脂蛋白(ox-LDL)诱导THP-1源性巨噬细胞泡沫化的作用机制。 [方法]通过组织破碎、差速/超速离心及蔗糖密度梯度离心等步骤,分离提纯CDELN。利用ox-LDL刺激THP-1源性巨噬细胞24 h建立泡沫细胞模型,并进一步研究CDELN对巨噬细胞泡沫化的作用及其机制。采用激光共聚焦显微镜检测THP-1源性巨噬细胞对CDELN和人DiL标记乙酰化低密度脂蛋白(DiL-ac-LDL)的摄取;采用油红O染色检测细胞内胆固醇含量,通过分析细胞油红O染色阳性面积评估细胞内脂质累积影响;RT-qPCR和Western blot检测清道夫受体A(SRA)、脂肪酸转运蛋白(CD36)、凝集素样氧化型低密度脂蛋白受体1(LOX-1)、ATP结合盒转运体A1/G1(ABCA1/G1)以及丝裂原活化蛋白激酶(MAPK)通路p-ERK、p-p38 MAPK和p-c-Jun的mRNA和蛋白表达水平。 [结果]CDELN是大小均一、具有双层膜结构、富含蛋白质和核酸的外泌体样纳米囊泡,能被巨噬细胞摄取。DiL-ac-LDL摄取实验提示CDELN可抑制巨噬细胞的胆固醇摄取。油红O染色实验提示CDELN可减轻ox-LDL诱导下的胞内胆固醇蓄积。RT-qPCR及Western blot显示,CDELN能够显著降低ox-LDL诱导的THP-1源性巨噬细胞基质金属蛋白酶9(MMP-9)、SRA、CD36、LOX-1的mRNA水平,以及降低p-ERK、SRA、CD36、LOX-1蛋白水平。加入p-ERK激动剂Yoda1后,CDELN的保护作用被明显逆转。[结论]CDELN可显著抑制巨噬细胞泡沫化,该作用可能与抑制MAPK通路ERK1/2的磷酸化水平有关。     

CD36, serves as a receptor for advanced glycation endproducts (AGE)

Interaction of advanced glycation endproducts (AGE) with AGE receptors induces several cellular phenomena relating potentially to diabetic complications. Five AGE receptors identified so far are receptor for AGE (RAGE), 80 K-H, OST-48, galectin-3, and macrophage scavenger receptor, types I and II (SR-A) [Eur. J. Biochem. 230 (1995) 408; Nature 386 (1997) 292.]. Since SR-A is known to belong to the class A scavenger receptor family and the scavenger receptor collectively represents a family of multiligand lipoprotein receptors, it is possible that CD36 belonging to class B scavenger receptor family (SR-B) can recognize AGE proteins as a ligand. This was tested in the present study at the cellular level by using Chinese hamster ovary (CHO) cells overexpressing human CD36 (CHO-CD36 cells). 125I-AGE-bovine serum albumin (BSA) was endocytosed in a dose-dependent fashion and underwent lysosomal degradation by CHO-CD36, but not wild-type CHO cells. Endocytic uptake of 125I-AGE-BSA by these cells was inhibited 50% by oxidized low-density lipoprotein (Ox-LDL) and 60% by FA6-152, an anti-CD36 antibody inhibiting cellular binding of Ox-LDL. Our results indicate that CD36 expressed by these cells mediates endocytic uptake and subsequent intracellular degradation of AGE proteins. Since CD36 is one of the major Ox-LDL receptors and is up-regulated in macrophage- and smooth muscle cell-derived foam cells in human atherosclerotic lesions, the present results suggest that, like Ox-LDL, AGE proteins generated in situ are recognized by CD36, which might contribute to the pathogenesis of diabetic macrovascular complications.     

TGF-beta reduced binding of high-density lipoproteins in murine macrophages and macrophage-derived foam cells

The expression of macrophage scavenger receptors is regulated by intracellular cholesterol levels, as well as by cytokines affecting macrophage effector functions. CD36, a member of the type B scavenger receptor family, will bind a variety of nonlipoprotein and lipoprotein ligands including high-density lipoprotein (HDL). Transforming growth factor-beta (TGF-beta) has been demonstrated to modulate macrophage effector functions and is present within atherosclerotic lesions. In the present study, the effect of TGF-beta on HDL binding by both macrophages and macrophage-derived foam cells was evaluated. TGF-beta, in a dose-dependent manner, reduced the binding of flurochrome-labeled HDL to both macrophages and foam cells. These effects were observed in macrophages derived from nonatherosclerotic (BALB/c) as well as from macrophages obtained from both apolipoprotein E and low-density lipoprotein receptor knockout mice. The decrease in HDL binding was consistent with a significant reduction in CD36 message levels. The effect of TGF-beta on type B scavenger receptor expression was not limited to CD36 as SR-BI message was also downregulated, although the effect was more modest. A similar reduction in HDL binding and CD36 message was also observed with the immunosuppressive glucocorticoid dexamethasone. These results suggest that within the microenvironment of an atherosclerotic lesion, TGF-beta and other agents that inhibit macrophage inflammatory responses may impact lesion progression through mechanisms that include the modulation of HDL-foam cell interactions.     

CD36介导氧化型低密度脂蛋白诱导U937细胞泡沫化和凋亡

为探讨清道夫受体ＣＤ３６在氧化型低密度脂蛋白诱导Ｕ９３７细胞泡沫化和凋亡中的作用,用氧化型低密度脂蛋白温育Ｕ９３７细胞,观察Ｕ９３７细胞泡沫化过程中ＣＤ３６的表达时序和泡沫细胞的凋亡;用ＣＤ３６单克隆抗体阻断Ｕ９３７细胞的吞噬作用,观察Ｕ９３７细胞吞噬蓄积胆固醇和细胞凋亡的改变。细胞胆固醇以修饰的酶荧光法测定;用流式细胞术检测异硫氰酸荧光素－抗ＣＤ３６单克隆抗体特异标记的ＣＤ３６和细胞的凋亡情况;用逆转录聚合酶链反应检测ＣＤ３６ｍＲＮＡ的表达。结果发现,８０ｍｇ／Ｌ氧化型低密度脂蛋白与Ｕ９３７细胞温育２４ｈ可增加细胞内总胆固醇,４８ｈ时可形成典型的泡沫细胞;ＣＤ３６表达呈现时序性改变,６ｈ即可检出ＣＤ３６表达增高,２４ｈ达到最高值,４８ｈ表达略有降低,ＣＤ３６ｍＲＮＡ的转录与ＣＤ３６的表达一致。用２００ｍｇ／Ｌ     

Macrophage foam-cell formation in streptozotocin-induced diabetic mice: stimulatory effect of glucose

BACKGROUND: Diabetes is associated with an increased risk for atherosclerosis. We investigated the effect of diabetes induction on atherogenesis and on macrophage-foam cell formation. METHODS AND RESULTS: Atherosclerotic apolipoprotein-E-deficient mice were converted into diabetic mice by streptozotocin injection. Aortic atherosclerotic lesion area was significantly enhanced by 67% and 106% in mice that were diabetic for 1 and 3 months, respectively, compared to the non-diabetic mice. Moreover, mouse peritoneal macrophages (MPM) from diabetic mice for 1 and 3 months exhibit higher lipid peroxides content by 55% and 63%, respectively, in association with the MPM glucose content. Oxidized LDL (Ox-LDL) uptake by MPM obtained from diabetic mice for 1 and 3 months was significantly increased by 36% and 45%, respectively, in association with the increased macrophage cholesterol content. To determine whether the accelerated foam cell formation in diabetic mice could result from a direct effect of glucose on macrophages, J-774-A.1 macrophages were incubated with increasing glucose concentrations (2.5-62 mM). Glucose-enriched macrophages exhibit dose-dependent higher peroxides content up to 7.5-fold and increased Ox-LDL cellular uptake associated with up-regulation of the scavenger receptor CD36 at the mRNA level. CONCLUSION: Induction of diabetes in atherosclerotic mice led to an accelerated atherosclerosis and macrophage-derived foam cell formation, probably by involving a glucose-dependent related mechanism.     

辛伐他汀对THP-1巨噬细胞源性泡沫细胞胆固醇代谢和SR-A表达的影响

目的探讨不同浓度辛伐他汀对THP-1巨噬细胞源性泡沫细胞胆固醇代谢和SR-A表达的影响。方法以50 nmol/L佛波酯诱导THP-1细胞分化成巨噬细胞,氧化型低密度脂蛋白（ox-LDL）诱导巨噬细胞建立泡沫细胞模型,通过不同浓度辛伐他汀干预后,油红O染色观察细胞内脂质堆积情况,高效液相色谱检测细胞内游离胆固醇和胆固醇酯含量,W estern b lot检测SR-A蛋白的表达。结果与ox-LDL组比较,辛伐他汀处理组巨噬细胞的油红O染色阳性细胞数和细胞内胆固醇酯含量均显著减少（P均〈0.01）,同时SR-A蛋白表达明显下降（P〈0.01）,呈剂量依赖性。结论辛伐他汀可抑制ox-LDL诱导的THP-1巨噬细胞泡沫化,可能与辛伐他汀抑制SR-A的表达,从而减弱巨噬细胞对ox-LDL的摄取有关。     

乙酰化低密度脂蛋白促进胆固醇酰基转移酶活性升高的机制研究

目的 :研究乙酰化低密度脂蛋白 (Ac LDL)对人THP 1单核细胞 (MC)分化的巨噬细胞 (MP)酰基辅酶A、胆固醇酰基转移酶 1(ACAT 1)活性的影响及其机制。方法 :体外培养人THP 1单核细胞系 ,由佛波酯 (PMA)作用使其分化为MP ,后者再由乙酰化低密度脂蛋白Ac LDL进行脂质负荷转变为泡沫细胞。该过程中以放射性同位素标记底物法检测ACAT 1酶活性的变化 ,并用Westernblot法检测ACAT 1酶蛋白的表达及RT PCR法检测A CAT 1mRNA的水平。结果 :在MC分化为MP的过程中ACAT 1酶活性升高了 2倍 ,差异有统计学意义 (P <0 .0 5 ) ,酶蛋白及mRNA水平呈现类似变化趋势 ;Ac LDL作用于巨噬细胞 ,使ACAT1酶活性、酶蛋白及mRNA进一步升高 ,差异有统计学意义 (P <0 .0 5 )。结论 :MC分化为MP的过程中ACAT 1表达上调 ,使ACAT 1活性增强 ,而Ac LDL可进一步促进ACAT 1基因表达增加 ,升高ACAT 1活性。     

不对称二甲基精氨酸对THP-1巨噬细胞源性泡沫细胞内胆固醇含量的影响

目的 观察不对称二甲基精氨酸（ADMA）对THP-1巨噬细胞源性泡沫细胞内胆固醇含量的影响.方法 THP-1单核细胞给予160nmol/L佛波酯（PMA）孵育48h,诱导分化成巨噬细胞,与80mg/L氧化型低密度脂蛋白（ox-LDL）孵育24h,使巨噬细胞转化为泡沫细胞,用油红O染色在光镜下鉴定泡沫细胞形态及变化.再以不同浓度ADMA（1μmol/L、5μmol/L、10μmol/L、20μmol/L、30μmol/L）作用泡沫细胞24h,以20μmol/L ADMA作用泡沫细胞不同时间（0h,6h,12h,24h,48h）,酶比色法检测泡沫细胞内胆固醇的含量.结果 ①单核细胞加人PMA诱导48h后,分化为巨噬细胞,再经ox-LDL诱导24h后转化为泡沫细胞.②与对照组相比,5μmol/L、10μmol/L、20μmol/L,30μmol/L的ADMA作用于,THP-1巨噬细胞源性泡沫细胞24h后,细胞内胆固醇含量均明显增加（P＜0.01）,③与对照组相比,20μmol/L的ADMA作用于THP-1巨噬细胞源性泡沫细胞12h,24h,48h,细胞内胆固醇含量均明显增加（P＜0.01）.结论 ①单核细胞株THP-1经PMA诱导后,可分化为巨噬细胞,再经ox-LDL诱导后,可转化为泡沫细胞.②ADMA可以增加THP-1巨噬细胞源性泡沫细胞内胆固醇的含量.     

Chronic urotensin II infusion enhances macrophage foam cell formation and atherosclerosis in apolipoprotein E-knockout mice

OBJECTIVE: Our recent studies have indicated that urotensin II, the most potent vasoconstrictor peptide identified to date, potentiates human macrophage foam cell formation and vascular smooth muscle cell proliferation, and its levels are increased in the plasma of hypertensive patients with carotid atherosclerotic plaques. In the present study, we investigated the enhancing effect of urotensin II on atherosclerosis in apolipoprotein E-knockout mice and its suppression by 4-aminoquinoline, an urotensin II receptor-selective antagonist. METHODS: Urotensin II, urotensin II + 4-aminoquinoline, or vehicle was infused for 4 weeks through an osmotic mini-pump into 9-week-old apolipoprotein E-knockout mice on a high-fat diet. Aortic atherosclerosis and foam cell formation in exudate peritoneal macrophages were examined. RESULTS: Atherosclerotic lesions as well as plasma levels of urotensin II, reactive oxygen species, and oxidized low-density lipoprotein and oxidized low-density lipoprotein-induced foam cell formation were significantly greater in urotensin II-infused mice than vehicle-infused controls. Western blotting analysis showed increased expression of scavenger receptors (CD36 and scavenger receptor class A) and acyl-CoA:cholesterol acyltransferase-1 in these macrophages. Increases in these parameters were significantly reduced by addition of 4-aminoquinoline. In apolipoprotein E-knockout mice even without urotensin II infusion, the treatment with 4-aminoquinoline for 8 weeks significantly prevented the development of atherosclerotic lesions. CONCLUSION: Our results provide the first evidence that increased plasma urotensin II level stimulates oxidized low-density lipoprotein and reactive oxygen species production and macrophage foam cell formation via increased expression of CD36, scavenger receptor class A, and acyl-CoA:cholesterol acyltransferase-1, contributing to the development of atherosclerosis in apolipoprotein E-deficient mice. Urotensin II receptor antagonism may be a promising therapeutic strategy against atherosclerosis.     

Synergically increased expression of CD36, CLA-1 and CD68, but not of SR-A and LOX-1, with the progression to foam cells from macrophages

Several species of scavenger receptors have so far been identified. However, it remains unclear which receptors are more crucial for the foam cell formation and progression. In the present study, we compared five major scavenger receptors (SR-A, CD36, CLA-1, CD68, and LOX-1) in their levels of expression at the different stages of foam cells derived from THP-1 cells. The expression of all scavenger receptors examined was up-regulated by the stimulation with TPA for 48 hours, despite the expressions of SR-A, CD36 and LOX-1 being very low before the treatment with TPA. Four to 7 days after the removal of TPA, the levels of CD36, CLA-1 and CD68 were increased significantly. In contrast, the expression of SR-A was suppressed significantly, and no change was observed in that of LOX-1. Furthermore, when the transformed macrophages were incubated with oxidized LDL, in which the uptake of [3H] cholesteryl oleoyl ether-labeled OxLDL was linear up to 7 days after the addition of OxLDL, the expression of CD36, CLA-1 and CD68 were greatly enhanced. This enhancement was more prominent than that without oxidized LDL, and the enhancement was sustained throughout the experimental period. On the other hand, SR-A was not up-regulated, and LOX-1 was down-regulated. We thus propose that CD36, CLA-1 and CD68, but not SR-A and LOX-1, may play crucial roles in the progression of macrophages to foam cells, which is a key step for the initiation of atherosclerosis.     

Angiotensin II administration to atherosclerotic mice increases macrophage uptake of oxidized ldl: a possible role for interleukin-6

The goal of the present study was to elucidate mechanisms for angiotensin II (Ang II) induction of oxidized low density lipoprotein (Ox-LDL) uptake by macrophages, the hallmark of early atherosclerosis. Compared with placebo treatment, Ang II injections (0.1 mL, 10(-7) mol/L per day) for 2 weeks to apolipoprotein E-deficient mice significantly increased Ox-LDL degradation, CD36 mRNA expression, and CD36 protein expression by their peritoneal macrophages (MPMs). These effects were abolished by treatment with losartan (5 to 50 mg/kg per day) before Ang II administration. Because no such effect was obtained in vitro, the ex vivo effect of Ang II on macrophage uptake of Ox-LDL could be mediated by a factor that is not expressed at a significant level in vitro. Because Ang II stimulates cellular production of interleukin-6 (IL-6), we analyzed the possible role of IL-6 as a mediator of Ang II-mediated cellular uptake of Ox-LDL by using several approaches. First, incubations of IL-6 with MPM or IL-6 administration in mice increased macrophage Ox-LDL degradation and CD36 mRNA expression. Second, injection of IL-6 receptor antibodies in mice during Ang II treatment reduced macrophage Ox-LDL uptake and CD36 expression compared treatment with Ang II alone. Finally, Ang II treatment of IL-6-deficient mice did not affect their MPM Ox-LDL uptake and CD36 protein levels. Thus, we conclude that a novel mechanism for Ang II atherogenicity, related to macrophage cholesterol accumulation and foam cell formation, may involve its stimulatory effect on macrophage uptake of Ox-LDL, a process mediated byIL-6.     

Role of platelet secretory products in modified lipoprotein metabolism in macrophages

Macrophage-derived foam cells and platelets are found in many lesions of atherosclerosis. Macrophages possess scavenger receptors that take up modified low density lipoproteins (LDL) like acetylated or acetoacetylated LDL (aLDL, aaLDL) resulting in accumulation of esterified cholesterol (EC) and acquisition of the characteristics of foam cells. We obtained a certain platelet secretory product from washed platelet-rich plasma which had been frozen and thawed three times (PSP alpha). We studied the effect of PSP alpha in modified lipoprotein metabolism in macrophages. When mouse or human macrophages were incubated with aaLDL and PSP alpha, much more EC was accumulated than with aaLDL only. Though the increase in EC of macrophages was dependent on the concentration of PSP alpha, it declined in high concentrations of PSP alpha. PSP alpha moderately increased 125I-aaLDL binding and cellular metabolism. PSP alpha also affected 125I-oxidized LDL binding and cellular metabolism, but it did not affect the metabolism of 125I beta-migrating very low density lipoprotein (beta VLDL). These results suggest that substances shed by activated platelets play a role in atherosclerosis as potent mediators of EC accumulation in macrophages and by affecting the receptor-mediated endocytosis of modified lipoproteins.     

Lipoprotein uptake in primary cell cultures of rabbit atherosclerotic lesions. A fluorescence microscopic and flow cytometric study

To characterize the lipoprotein metabolism of lipid-filled cells of atherosclerotic lesions, uptake of 3,3'-dioctadecylindocarbocyanine (DiI)-labelled low density lipoprotein (LDL), acetylated LDL (Ac-LDL) and beta-very low density lipoprotein (beta-VLDL) was studied by fluorescence microscopy and flow cytometry in primary cultures of enzymatically dispersed aortic cells from cholesterol-fed rabbits. Most of the foam cells were identified as macrophages on the basis of Fc-receptors and high activities of nonspecific esterase and acid lipase, although cholesteryl ester (CE) inclusions were found by filipin staining also in smooth muscle cells (SMCs). During the culture only SMCs proliferated and were confluent in about 1 week. After incubation with DiI-Ac-LDL most macrophage foam cells were brightly fluorescent, but also many SMCs accumulated fluorescence. In SMCs, an excess of LDL inhibited the uptake of DiI-beta-VLDL and DiI-LDL, indicating that these lipoproteins were taken up by the apoB,E receptor; the activity of this receptor was low 2 days after cell isolation but increased considerably during SMC proliferation. DiI-beta-VLDL was not taken up by the macrophage foam cells until after 7 days' culture, when their CE content had decreased, reflecting a feed-back regulation of these receptors as well. Our results indicate that, in primary cultures of enzyme-dispersed cells from rabbit atherosclerotic lesions, most of the foam cells have lipoprotein receptors resembling those described in macrophages and that also many SMCs accumulate Ac-LDL.     

与动脉粥样硬化密切相关的清道夫受体

清道夫受体是一类结构多样化的糖蛋白受体，具有广泛的配体谱和功能。已知清道夫受体与动脉粥样硬化、宿主防御、细胞粘附、细胞增殖以及细胞凋亡等均有不同程度的关系。已经发现的清道夫受体分为A、B、C、D、E、F、G几大类型，其中清道夫受体A型（SR-AI，SR-AII）和清道夫受体B型（SR-BI，CD36）研究的较多，并且已被证明与动脉粥样硬化密切相关。SR-A和CD36被认为是主要的致动脉粥样硬化受体；而SR-BI作为高密度脂蛋白受体参与胆固醇酯的逆转运过程，是重要的抗动脉粥样硬化的受体。本文主要综述这几类清道夫受体的结构、功能、信号转导、表达调控以及以它们为靶点进行的药物研究。     

白细胞介素10对人THP-1源巨噬细胞泡沫化过程中SR-A表达的影响

目的:本研究旨在观察白细胞介素-10(IL-10)对人THP-1源巨噬细胞泡沫化过程中清道夫受体A(SR-A)表达的影响,探讨在动脉粥样硬化形成中IL-10对氧化型低密度脂蛋白(ox-LDL)诱导巨噬细胞泡沫化的干预作用。方法:体外建立泡沫细胞培养体系,将细胞分为5组即THP-1单核细胞组,巨噬细胞组,IL-10刺激巨噬细胞组,ox-LDL刺激巨噬细胞组(泡沫细胞组),ox-LDL和IL-10联合刺激巨噬细胞组。采用RT-PCR和Westernbloting分别检测SR-A的mRNA和蛋白表达变化,脂质油红O化学染色方法检测各组细胞脂质摄取量的情况。结果:当THP-1分化为巨噬细胞时,SR-A开始大量表达;IL-10刺激可显著抑制巨噬细胞组SR-A的表达,其mRNA和蛋白分别下降为未刺激前的0.6倍和0.7倍,泡沫细胞形成率也下降为未刺激前的0.6倍。巨噬细胞经ox-LDL刺激形成泡沫细胞时,SR-A的表达进一步升高,其mRNA和蛋白分别增加为巨噬细胞组的1.5倍和1.4倍,泡沫细胞形成率提高为巨噬细胞组的1.7倍。在此过程中加入IL-10联合刺激,观察到SR-A的表达量有显著降低,其mRNA和蛋白均下降为单用ox-LDL刺激巨噬细胞组的0.4倍,ox-LDL的摄取量也下降为单用ox-LDL刺激巨噬细胞组的0.3倍。结论:IL-10抑制巨噬细胞SR-A表达,IL-10对ox-LDL诱导巨噬细胞SR-A的表达具明显干预作用。IL-10通过抑制SR-A表达可能在抗动脉粥样硬化的发生中发挥重要作用。