牛磺酸下调单核-巨噬细胞ACAT-1表达

目的:观察牛磺酸对THP-1及THP-1源性巨噬细胞酰基辅酶A:胆固醇酰基转移酶1(ACAT-1)表达及活性的影响。方法:将THP-1细胞与PMA孵育48h使之分化为巨噬细胞,在有或无干扰素-γ(IFN-γ)的条件下,用不同浓度的牛磺酸与THP-1持续作用不同的时间,RTPCR检测ACAT-1mRNA水平,WesternBlot检测其蛋白表达,并测定其酶活性。结果:牛磺酸显著下调THP1及THP1源性巨噬细胞的ACAT1mRNA和蛋白表达水平以及ACAT-1活性(P<0.05～0.01,n=3);IFNγ促进ACAT1mRNA和蛋白表达、增强ACAT-1活性(P<0.05,n=3)的作用被牛磺酸部分抑制(P<0.05,n=3)。结论:牛磺酸不但能降低单核巨噬细胞ACAT-1的基础表达和活性,而且能抑制由IFN-γ诱导的ACAT-1表达和活性,这可能是其抗动脉粥样硬化的机制之一。     

内脂素对人单核细胞株源性巨噬细胞ATP结合盒转运蛋白A1的调控

目的:观察过氧化物酶体增殖物激活受体γ(PPARγ)信号转导通路在内脂素调控人单核细胞株(THP-1)源性巨噬细胞ATP结合盒转运蛋白A1(ABCA1)表达中的作用,探讨内脂素诱导泡沫细胞形成的机制和途径。方法:THP-1单核细胞诱导分化为巨噬细胞,随机分组,给予不同浓度和不同作用时间的内脂素进行干预,分别运用油红O染色观察细胞浆脂滴变化,反转录聚合酶链反应(RT-PCR)法和蛋白免疫印迹(Westernblot)法检测各组细胞PPARγ及ABCA1mRNA和蛋白表达,酶荧光学法检测细胞内TC和游离胆固醇(FC)含量,TC与FC之差为胆固醇酯(CE)含量。结果:与对照组比较,内脂素干预组细胞浆脂滴明显增多,细胞内FC和CE含量增加(P<0.05),PPARγ及ABCA1mRNA和蛋白表达降低(P<0.05);相关分析显示,内脂素呈浓度和时间依赖性下调PPARγ及ABCA1mRNA和蛋白的表达。结论:内脂素可能通过PPARγ信号转导通路下调ABCA1表达,减少细胞内FC流出,使细胞内CE合成增加,从而诱导泡沫细胞形成。这可能为内脂素致动脉粥样硬化发病机制的研究提供了一个新的理论依据。     

铁离子螯合剂去铁胺对巨噬细胞、泡沫细胞细胞外基质金属蛋白酶诱导因子表达的影响

目的:观察铁负荷过低对巨噬细胞、泡沫细胞细胞外基质金属蛋白酶诱导因子(EMMPRIN)表达的影响。方法: 体外诱导THP-1单核细胞转化为巨噬细胞、泡沫细胞。实验细胞分为3组:对照组（正常巨噬细胞、泡沫细胞）、铁离子螯合剂去铁胺(DFO)刺激组、柠檬酸铁和DFO共刺激组。应用RT-PCR和Western blot测定巨噬细胞、泡沫细胞中EMMPRIN基因和蛋白的表达。用Western blot测定MMP-9蛋白的表达。用明胶酶谱法测定MMP-9的活性。结果: DFO刺激组中EMMPRIN基因及蛋白的水平、MMP-9蛋白表达的水平及活性均明显高于对照组（P<0.05,P<0.01）。柠檬酸铁逆转了DFO对EMMPRIN表达的上调作用。结论: 铁负荷过低可增加巨噬细胞及泡沫细胞中炎症因子的表达及活性,可能会促进心血管事件的发生。     

罗格列酮对THP-1源性泡沫细胞ABCA1、Caveolin-1蛋白水平的影响

目的 观察罗格列酮干预THP-1源性泡沫细胞腺苷三磷酸结合盒转运体A1(ABCA1)蛋白、小凹蛋白-1(Caveolin-1蛋白)表达变化,以探讨罗格列酮防治动脉粥样硬化(AS)的可能机制.方法 培养THP-1细胞,佛波脂(PAM)使之巨噬化,氧化型低密度脂蛋白(ox-LDL)使巨噬细胞形成泡沫细胞,罗格列酮和泡沫细胞孵育48 h,用流式细胞技术检测ABCA1蛋白、Caveolin-1蛋白的水平.结果 ①ox-LDL处理巨噬细胞后,经油红O染色阳性细胞百分数增加(P＜0.05),罗格列酮可显著缓解ox-LDL所致的泡沫细胞阳性数(P＜0.05).②罗格列酮组均增加ABCA1蛋白、Caveolin-1蛋白的表达,与泡沫细胞组相比,均有显著性差异(P＜0.05).结论 ABCA1、Caveolin-1蛋白的增加可能是罗格列酮抗AS的机制之一.     

葛根素对巨噬细胞表达C-反应蛋白的影响

目的:观察葛根素对巨噬细胞分泌和表达C-反应蛋白(CRP)的影响。方法:将人单核细胞系THP-1来源的巨噬细胞与不同浓度的葛根素进行培养,采用逆转录多聚酶链式反应(RT-PCR)和酶联免疫吸附测定(ELISA)方法分别检测巨噬细胞CRP基因和蛋白质表达。结果:葛根素对人单核细胞系THP-1来源的巨噬细胞CRP及其蛋白质表达呈浓度依赖性,随着葛根素的浓度的增加,CRPmRNA及其蛋白质表达逐渐减少。结论:葛根素可以通过调节巨噬细胞表达CRP途径,发挥稳定动脉粥样硬化斑块的作用。     

葡萄糖对THP-1源性巨噬细胞酰基辅酶A:胆固醇酰基转移酶1表达的影响

研究葡萄糖对人THP-1单核分化巨噬细胞酰基辅酶A：胆固醇酰基转移酶1（ACAT-1）表达的影响。发现高糖作用下，巨噬细胞ACAT-1的mRNA及蛋白表达增加，这可能是糖尿病血管病变机制之一。     

松龄血脉康对THP-1源性泡沫细胞ABCA1蛋白表达及细胞内胆固醇含量的影响

目的 观察松龄血脉康对THP-1源性泡沫细胞腺苷三磷酸结合盒转运体A1(ABCA1)蛋白表达及细胞内胆固醇含量的影响及其防治动脉粥样硬化(AS)的可能机制.方法 培养THP-1细胞,160 nmol/L佛波脂(PAM)使之巨噬化,用50 mg/L氧化型低密度脂蛋白使巨噬细胞形成泡沫细胞.0.81 mg/L松龄血脉康、10 μmol/L罗格列酮分别和泡沫细胞孵育6、12、24 h;0.40、0.81、1.6 mg/L的松龄血脉康、1、10、20 μmol/L的罗格列酮与泡沫细胞孵育24 h.用流式细胞技术检测ABCA1蛋白表达的水平,并测定各组细胞内胆固醇含量.结果 松龄血脉康组、罗格列酮组均增加ABCA1蛋白的表达,而细胞内胆固醇含量减少,与对照组相比,均有显著性差异(P＜0.05),且有浓度、时间依赖性.松龄血脉康组与罗格列酮组无显著性差异(P>0.05).结论 松龄血脉康具有与罗格列酮增加ABCA1蛋白及降低胆固醇含量相似的作用.增加ABCA1蛋白表达,降低细胞内胆固醇含量可能是中药松龄血脉康抗AS的机制之一.     

二甲双胍对脂多糖诱导的THP-1细胞相关炎症因子及凋亡的影响

目的 通过观察二甲双胍对脂多糖诱导的人单核细胞(THP-1)相关炎症因子分泌及凋亡影响的剂量效应关系,探讨二甲双胍的直接抗炎作用.方法 体外培养人THP-1细胞,以1μg/ml脂多糖和不同浓度二甲双胍分别孵育6、24和48 h,收集细胞及培养液上清进行检测.应用乳酸脱氢酶微量释放法检测不同浓度二甲双胍对THP-1细胞的毒性作用,酶联免疫吸附法检测上清白细胞介素(IL)-1β、IL-6、IL-8和肿瘤坏死因子α(TNF-α)水平,流式细胞仪Annexin V/碘化丙啶双染色法测定THP-1细胞早期凋亡率.结果 二甲双胍可剂量依赖性地降低上清IL-1β、IL-6、IL-8和TNF-α水平,且48 h作用最为显著.1和5 mmol/L二甲双胍显著降低脂多糖刺激的IL-1β、IL-6、IL-8和TNF-α的分泌(P＜0.05或P＜0.01).并且二甲双胍可剂量依赖性地减少THP-1细胞早期凋亡数目(F=4.696,P=0.036);1、5 mmol/L二甲双胍组细胞早期凋亡率明显低于脂多糖组(37.47％、33.35％对49.90％,P＜0.05或P＜0.01).结论 二甲双胍可剂量依赖地降低脂多糖诱导的THP-1细胞炎症因子分泌及早期凋亡率,提示其有一定的直接抗炎作用.     

巴西日圆线虫虫体蛋白体外诱导THP-1来源巨噬细胞极化的研究

目的　分析巴西日圆线虫虫体蛋白体外诱导人单核细胞白血病THP?1细胞来源巨噬细胞的极化方向,探索机体对巴西日圆线虫感染的免疫应答机制。方法　建立并维持巴西日圆线虫培养的实验室循环,无菌条件下收集L3和L5虫体,分别制备虫体蛋白;建立THP?1细胞体外培养体系,经500 ng/mL佛波酯（PMA）刺激培养后呈贴壁状态的M0型细胞分别采用500 ng/mL脂多糖（LPS）+ 100 ng/mL γ?干扰素（IFN?γ）、白细胞介素4（IL?4）+ IL?13（浓度均为100 ng/mL）、L3及L5虫体蛋白（浓度均为5 mg/mL）进行刺激,同时设不加任何刺激的阴性对照组。通过显微镜镜检观察刺激后细胞形态、实时荧光定量PCR（qPCR）检测M1/M2型巨噬细胞特异性基因mRNA表达水平、流式细胞术检测巨噬细胞表面标志物及酶联免疫吸附试验（ELISA）检测M1/M2型巨噬细胞分泌的细胞因子含量,观察巴西日圆线虫虫体蛋白体外诱导THP?1来源巨噬细胞的极化方向。结果　THP?1细胞经PMA刺激培养呈贴壁的M0型细胞后,经LPS + IFN?γ刺激培养后呈特征性M1型极化;经IL?4 + IL?13刺激培养后呈特征性M2型极化;经L3和L5蛋白刺激培养后均呈特征性M2型极化。阴性对照组、LPS + IFN?γ刺激组、IL?4 + IL?13刺激组、L3蛋白刺激组、L5蛋白刺激组间M1型巨噬细胞比例差异有统计学意义（[χ2] = 3 721.00,P < 0.001）,其中LPS + IFN?γ刺激组M1型巨噬细胞比例最高;各组间M2型巨噬细胞比例差异有统计学意义（[χ2] = 105.43,P < 0.001）。各组间C?C基序趋化因子配体2（CCL2）、肿瘤坏死因子α（TNF?α）、IL?12b、过氧化物酶体增殖物激活受体γ（PPARγ）、IL?10、甘露糖受体C型1（Mrc1）基因mRNA表达水平差异均有统计学意义（F = 191.95、129.95、82.89、11.30、9.51、12.35,P均< 0.001）,各组间CD86、CD206阳性率差异均有统计学意义（[χ2] = 24 004.33、832.50,P均< 0.001）。LPS + IFN?γ刺激组IL?1β、TNF?α表达水平均显著高于IL?4 + IL?13刺激组、L3蛋白刺激组及L5蛋白刺激组（P均< 0.001）;IL?4 + IL?13刺激组、L3蛋白刺激组和L5蛋白刺激组TGF?β1、IL?10表达水平均显著高于阴性对照组和LPS + IFN?γ刺激组（P均< 0.05）。结论　巴西日圆线虫L3和L5虫体蛋白体外均可诱导THP?1来源巨噬细胞向M2型极化。     

Phospholipid transfer between plasma and platelets in vitro

Washed rabbit platelets were resuspended in plasma in which all of the major phospholipids had been isotopically labeled by injection of 32PO4 into rabbits. At certain time intervals during a 6-hr incubation at 37 degrees C, aliquots were removed from the incubation mixture and the platelets were isolated and subjected to lipid extraction and phospholipid analysis. A continuous rise in platelet non-lipid-bound and lipid-bound radioactivity was observed through-out the incubation period. Two platelet phospholipids, lecithin and lysolecithin, were significantly labeled, whereas little or no labeling of the other phospholipids was found. There was no detectable change in total or individual platelet phospholipid content. At 6 hr, 4% of total platelet phospholipid, 43% of platelet lysolecithin, and 7% of platelet lecithin were labeled. Platelets incubated in plasma from rabbits with diet- induced hyperlipidemia took up and incorporated significantly more label into their phospholipids than did platelets in normal plasma. Labeling of both platelet lysolecithin and lecithin could be due to uptake and metabolism of plasma lysolecithin by platelets. However, labeling of platelet lecithin could at least in part be the result of direct exchange of this phospholipid with the plasma. Uptake and incorporation of endogenous plasma lysolecithin by platelets and, possibly, direct exchanged of platelet lecithin may be important mechanisms in the modification by plasma lipids of platelet membrane phospholipid fatty acid composition and platelet function.     

Differential uptake of subfractions of triglyceride-rich lipoproteins by THP-1 macrophages

It is well known that raised plasma triglycerides (TG) are positively linked to the development of coronary heart disease. However, triglycerides circulate in a range of distinct lipoprotein subfractions and the relative atherogenicity of these subfractions is not clear. In this study, three fractions of triglyceride rich lipoprotein (TRL) were isolated from normolipidaemic males according to their differing Svedberg flotation (S_f) rates: chylomicron (CM, S_f > 400), very low-density lipoprotein (VLDL)-1 (S_f 60–400) and VLDL-2 (S_f 20–60). These fractions were incubated with THP-1 monocyte-derived macrophages for determination of cholesterol and TG accumulation, in the presence and absence of the lipoprotein lipase (LPL) inhibitor orlistat. Expression of LDL receptor related protein (LRP) and apolipoprotein B48 receptor (apoB48R) was also examined in both differentiating monocytes, and monocyte-derived macrophages, incubated with TRL.

VLDL-1 caused a significantly greater accumulation of TG within macrophages compared to VLDL-2. Binding studies also tended to show a greater preference for VLDL-1. No change in expression of LRP or apoB48R was observed in fully differentiated macrophages incubated with VLDL-1, VLDL-2 or CM, although a greater expression of LRP mRNA was observed in differentiating monocytes exposed to VLDL-1, compared to those incubated with CM or VLDL-2. TG loading in response to all three TRL fractions was blocked by orlistat, suggesting that it is likely that the major pathway for uptake of TG was hydrolysis by LPL. Calculations suggested that direct uptake of particles accounts for between 12 and 25% of total TAG uptake. In conclusion, THP monocyte-derived macrophages demonstrate a preference for VLDL-1, both through the LPL pathway and by direct uptake of whole particles.     

薯蓣皂苷元对THP-1巨噬细胞ABCA1表达及胆固醇流出的影响

目的　探讨薯蓣皂苷元（Dgn）对巨噬细胞ATP结合盒转运体A1（ABCA1）表达及其介导胆固醇流出的影响。方法　用Dgn或结合ABCA1小干扰RNA（siRNA）处理THP-1源性巨噬细胞24　h后,Western　blot检测ABCA1蛋白水平,HPLC检测胞内总胆固醇（TC）、游离胆固醇（FC）及胆固醇酯（CE）含量,液体闪烁计数仪检测胞内胆固醇流出,油红O染色观察胞内脂滴情况。结果　Dgn呈浓度依赖性上调巨噬细胞ABCA1的表达,促进胞内胆固醇流出,降低胞内TC、FC和CE含量,抑制胞内脂质蓄积和泡沫细胞形成。而ABCA1　siRNA与Dgn共处理细胞后,明显抑制Dgn促胆固醇流出作用,胞内脂质蓄积和泡沫细胞形成明显加剧。结论　Dgn通过促进巨噬细胞ABCA1表达和胆固醇流出,抑制胞内脂质蓄积和泡沫细胞形成。     

大肠杆菌感染诱导THP-1细胞凋亡的研究

目的观察大肠杆菌对THP-1细胞是否具有凋亡诱导作用。方法当细胞与细菌浓度比为1∶10时,分别于诱导后10min2、0min3、0min6、0min及90min时用Giemsa染色观察细胞形态学改变,并用AnnexinVFITC/PI流式细胞仪进行凋亡定量分析。结果大肠杆菌感染后10min及20min时偶见细胞凋亡,感染30min、60min及90min时可见许多细胞出现核固缩、核断裂及凋亡小体形成等形态学变化,流式细胞仪测定表明细胞凋亡率增高,且显示一定的时间效应。且二种方法所得结果一致。结论大肠杆菌以时间依赖方式诱导THP-1细胞发生凋亡。     

Phospholipid methylation in macrophages is inhibited by chemotactic factors

Chemotaxis by human monocytes has been shown to require methylation mediated by S-adenosyl-L-methionine(AdoMet), but the specific transmethylation reaction necessary for this function was not elucidated. In an attempt to define the methylation requirement for chemotaxis, we examined the effect of chemotactic agonists and antagonists on protein carboxy-O-methylation of protein and methylation of phospholipid in guinea pig macrophages. Chemotactic agents tested over a wide dose and time range produced no alteration in carboxy-O-methylation. However, these agents did produce an effect on the methylation of phosphatidylethanolamine by macrophages. AdoMet-mediated phospholipid methylation was inhibited by as much as 73% by chemotactic factors, and there was excellent correlation (r = 0.99) between their concentrations for producing half-maximal chemotactic responses and for inhibiting phospholipid methylation. The inhibition of methylation by chemotactic factors was observed at all incubation times and could not be explained by an increased turnover of membrane phospholipid. Neither the chemotaxis antagonist fPhe-Met nor the nonchemotactic tripeptide Met-Met-Met significantly depressed phospholipid methylation. Immune phagocytosis by macrophages similarly did not alter phospholipid methylation. The chemotactic factors produced no alteration in total macrophage phospholipid synthesis or in the phospholipid methylation in a nonchemotactic cell type. The formation of newly methylated derivatives of phosphatidylethanolamine in macrophages was decreased by a biologically active dose of chemotactic factor. These findings indicate that chemotactic factors are capable of altering the methylation of phosphatidylethanolamine in chemotactically responsive cells. The inhibition of phospholipid methylation by chemotactic factors may be necessary for the translation of a chemotactic signal on the surface of the cell into directional cell movement.     

Phospholipid transfer activity of microsomal triglyceride transfer protein produces apolipoprotein B and reduces hepatosteatosis while maintaining low plasma lipids in mice

Microsomal triglyceride transfer protein (MTP), essential for apolipoprotein B (apoB) biosynthesis, evolved as a phospholipid transfer protein and acquired triglyceride transfer activity during a transition from invertebrates to vertebrates. But it is unknown whether MTP directly transfers lipids onto apoB in vivo and, if it does, whether both neutral and polar lipid transfer activities of MTP are critical for lipoprotein assembly. The molecular bases for differences in lipid transfer activities with respect to distinct domains in Drosophila MTP (dMTP) and human MTP (hMTP) are not obvious because both proteins have very similar primary, secondary, and tertiary structures. We used an in vivo approach to delineate physiological significance of these distinct lipid transfer activities by expressing dMTP (transfers phospholipids) and hMTP (transfers phospholipids and triglycerides) orthologs using adenoviruses in liver-specific MTP-deficient (L-MTP(-/-)) mice that have low plasma and high hepatic lipids. Both orthologs improved plasma lipids but plasma triglycerides were lower in dMTP mice due to lower hepatic triglyceride and apoB production. Hepatosteatosis in L-MTP(-/-) mice was ameliorated to similar levels by both. Attenuation of hepatosteatosis upon dMTP expression pertained to enhanced β-oxidation with no changes in lipogenesis. Phospholipid transfer activity of MTP promoted biogenesis of both apoB48 and apoB100-containing very low density lipoprotein in addition to a phospholipid-rich apoB48-containing high-density lipoprotein particle. Triglyceride transfer activity augmented the biosynthesis of triglyceride-rich lipoproteins by increasing the formation of these particles in the lumen of the endoplasmic reticulum. CONCLUSION: Based on these findings, we posit that the selective inhibition of MTP triglyceride transfer activity might reduce hyperlipidemia while protecting liver from excess lipid accumulation.     

Inhibition of protein geranylgeranylation induces apoptosis in myeloma plasma cells by reducing Mcl-1 protein levels

HMG-CoA reductase is the rate-limiting enzyme of the mevalonate pathway leading to the formation of cholesterol and isoprenoids such as farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP). The inhibition of HMG-CoA reductase by lovastatin induced apoptosis in plasma cell lines and tumor cells from patients with multiple myeloma. Here we show that cotreatment with mevalonate or geranylgeranyl moieties, but not farnesyl groups, rescued myeloma cells from lovastatin-induced apoptosis. In addition, the inhibition of geranylgeranylation by specific inhibition of geranylgeranyl transferase I (GGTase I) induced the apoptosis of myeloma cells. Apoptosis triggered by the inhibition of geranylgeranylation was associated with reduction of Mcl-1 protein expression, collapse of the mitochondrial transmembrane potential, expression of the mitochondrial membrane protein 7A6, cytochrome c release from mitochondria into the cytosol, and stimulation of caspase-3 activity. These results imply that protein geranylgeranylation is critical for regulating myeloma tumor cell survival, possibly through regulating Mcl-1 expression. Our results show that pharmacologic agents such as lovastatin or GGTase inhibitors may be useful in the treatment of multiple myeloma.