Inhibitory effect of dexamethasone palmitate-low density lipoprotein complex on low density lipoprotein-induced macrophage foam cell formation

We used low density lipoprotein (LDL) as a carrier of site-specific delivery of drugs to atherosclerotic lesions, prepared a dexamethasone palmitate (DP)-LDL complex, and examined the effect of the DP-LDL complex on foam cell formation of macrophages in vitro. LDL was isolated from human plasma and the DP-LDL complex was prepared by incubation in the presence of Celite 545. The complex contained about 50 mol of DP in 1 mol of LDL. When macrophages were incubated with LDL for 48 h, cholesterol ester was accumulated in the macrophages, indicating foam cell formation. This accumulation of cholesterol ester was significantly inhibited by incubation with the DP-LDL complex. The potency of the DP-LDL complex was similar to that of dexamethasone alone. The DP-LDL complex also significantly attenuated the accumulation of cholesterol ester induced by incubation with LDL prior to the incubation with the DP-LDL complex. These findings indicated that the DP-LDL complex showed similar characteristics to LDL, and the DP-LDL complex inhibited the foam cell formation of macrophages in in vitro experiments. This DP-LDL complex has a possibility as a drug-carrier complex for use in atherosclerosis.     

Cellular uptake of a dexamethasone palmitate-low density lipoprotein complex by macrophages and foam cells

To evaluate the utility of a dexamethasone palmitate (DP)-low density lipoprotein (LDL) complex to transport drug into foam cells, the cellular uptake of DP-LDL complex by macrophages and foam cells was examined. The DP-LDL complex was prepared by incubation with DP and LDL, and the DP-LDL complex and murine macrophages were incubated. No cellular uptake of the DP-LDL complex by macrophages was found until 6 h after the start of incubation, but this gradually increased from 12 to 48 h. On the other hand, the cellular uptake of the oxidized DP-LDL complex was already apparent at 3 h after the start incubation, and then markedly increased until 48 h incubation along with that of the lipid emulsion (LE) containing DP (DP-LE). The cellular uptake of DP-LE by foam cells was significantly lower than that by macrophages. However, the cellular uptake of DP-LDL complex by foam cells was similar to that by macrophages. These findings suggest that the DP-LDL complex is oxidatively modified, and then incorporated into macrophages and foam cells through the scavenger receptor pathway. Since selective delivery of drugs into foam cells in the early stage of atherosclerosis is a useful protocol for antiatherosclerosis treatment, the DP-LDL complex appears to be a potentially useful drug-carrier complex for future antiatherosclerotic therapy.     

Effect of dexamethasone palmitate-low density lipoprotein complex on cholesterol ester accumulation in aorta of atherogenic model mice

In order to confirm the efficacy of dexamethasone palmitate (DP)-low density lipoprotein (LDL) complex on experimental atherosclerosis in vivo, we examined whether DP-LDL complex could be effective for cholesterol ester accumulation in the aorta of atherogenic mice. Nonatherogenic and atherogenic mice were fed with normal and atherogenic diet for 14 weeks, respectively. Dexamethasone (DEX), lipid emulsion containing DP (DP-LE), or DP-LDL complex was intravenously injected once a week from 8 to 14 weeks. Cholesterol levels in serum and aorta in the atherogenic mice were significantly higher than those of nonatherogenic mice. Injection of DP-LDL complex significantly reduced cholesterol ester (CE) accumulation in the aorta of atherogenic mice. The reduction of CE accumulation in aorta treated with DP-LDL complexes was 10 and 100 times more potent than that with DP-LE and DEX, respectively. The radioactivity in the aorta of atherogenic mice treated with 3H-DP-LDL complex was significantly higher than that with 3H-DP-LE and 3H-DEX at 24 h after injection. Even 7 d after injection, a significant amount of radioactivity was present only in the aorta of atherogenic mice treated with DP-LDL complex. This result suggests that DP-LDL complex is selectively delivered to the atherogenic lesions in the aorta of atherogenic mice, and then DP released from the complex inhibits CE accumulation in the aortic intima. Therefore, DP-LDL complex may be a good drug-carrier in drug delivery system for atherosclerosis.     

Effects of low density lipoprotein and oxidized low density lipoprotein on the cytotoxic activity of Asp-hemolysin to murine macrophages

We examined the effects of human low density lipoprotein (LDL) and oxidized LDL (Ox-LDL) on the cytotoxic activity of Asp-hemolysin from Aspergillus fumigatus Fresenius-Muramatsu strain to mouse peritoneal macrophages (M phi). The inhibitory effects of LDL and Ox-LDL on the cytotoxic activity of Asp-hemolysin to M phi increased in a dose-dependent manner, and the effect of Ox-LDL was greater than the inhibitory effect of LDL. Furthermore, the binding of Asp-hemolysin to LDL or Ox-LDL was observed by western blot analysis of the culture medium. These results suggest that the inhibition by LDL or Ox-LDL on the cytotoxic activity of Asp-hemolysin to M phi was due to the binding of LDL or Ox-LDL to Asp-hemolysin in the culture medium.     

Uptake of dexamethasone incorporated into liposomes by macrophages and foam cells and its inhibitory effect on cellular cholesterol ester accumulation

To confirm the efficacy of dexamethasone incorporated into liposomes in the treatment of atherosclerosis, the uptake of dexamethasone-liposomes by macrophages and foam cells and its inhibitory effect on cellular cholesterol ester accumulation in these cells were investigated in-vitro. Dexamethasone-liposomes were prepared with egg yolk phosphatidylcholine, cholesterol and dicetylphosphate in a lipid molar ratio of 7/2/1 by the hydration method. This was adjusted to three different particle sizes to clarify the influence of particle size on the uptake by the macrophages and foam cells, and the inhibitory effect on cellular cholesterol ester accumulation. The distribution of particle sizes of dexamethasone-liposomes were 518.7+/-49.5 nm (L500), 202.2+/-23.1 nm (L200), and 68.6+/-6.5 nm (L70), respectively. For each size, dexamethasone concentration and dexamethasone/lipid molar ratio in dexamethasone-liposome suspension were 1 mg dexamethasone mL-1 and 0.134 mol dexamethasone mol-1 total lipids, respectively. The zeta potential was approximately -70 mV for all sizes. Dexamethasone-liposomes or free dexamethasone were added to the macrophages in the presence of oxidized low density lipoprotein (oxLDL) and foam cells, and then incubated at 37 degrees C. The uptake amount of dexamethasone by the macrophages and foam cells after a 24-h incubation was L500>L200>free dexamethasone>L70. The macrophages in the presence of oxLDL and foam cells were incubated with dexamethasone-liposomes or free dexamethasone for 24 h at 37 degrees C to evaluate the inhibitory effect on the cellular cholesterol ester accumulation. The cellular cholesterol ester level in the macrophages treated with oxLDL was significantly increased compared with that in macrophages without additives. L500, L200 and free dexamethasone significantly inhibited this cholesterol ester accumulation. L500, L200 and free dexamethasone also significantly reduced cellular cholesterol ester accumulation in foam cells. In addition, the relationship between the area under the uptake amount of dexamethasone-time curve (AUC) and the inhibition rate of cholesterol ester accumulation in macrophages and foam cells was evaluated. The inhibition rate of cholesterol ester accumulation (%) was related to the AUC in both types of cell. These results suggested that dexamethasone-liposomes would be a useful approach to the development of a novel drug delivery system for atherosclerotic therapy. Furthermore, the prediction of the inhibitory effect of dexamethasone on cellular cholesterol ester accumulation may become possible by using the results of this study.     

Activation of membrane outward currents by human low density lipoprotein in mouse peritoneal macrophages

Summary The aim of the present study was to search for electrophysiological effects of human lipoproteins on membrane currents in mouse peritoneal macrophages which had been cultured for 5 to 20 days. Whole-cell currents were recorded by using a voltage-clamp technique.Low density lipoprotein (LDL, 100 g/ml) increased a slowly activating nonspecific cation current (i_so) in the positive potential range to 244 ± 23% of the reference (test potential + 55 mV, n = 13, P < 0.005). Augmentation of current resulted out of a negative shift of the activation curve along the voltage axis (–22 mV) and an increase of maximally available current.Furthermore, LDL increased a rapidly activating outward current (i_fo) at test potentials positive to the potassium equilibrium potential. At +55 mV i_fo-amplitude increasedto 165 ± 14% ofreference (n = 16, P < 0.005). LDL-induced effects on i_fo-current could be mimicked by application of the calcium ionophore A 23187 (1 mol/l) which led to an increase of i_fo-current to 161 ± 25% of the reference (test potential + 55 mV, n = 11, P < 0.005).Acetylated-LDL (100 g/ml, 5–15 min) produced no significant effect on the membrane currents under investigation. Correspondence to U. Borchard at the above address     

Berberine-induced inhibition of adipocyte enhancer-binding protein 1 attenuates oxidized low-density lipoprotein accumulation and foam cell formation in phorbol 12-myristate 13-acetate-induced macrophages

The phagocytosis of oxidized low-density lipoprotein (oxLDL) by monocyte-derived macrophages and the subsequent differentiation of macrophages into foam cells are the key steps in atherogenesis. Scavenger receptors, such as CD36 and lectin-like low-density lipoprotein receptor 1 (LOX-1), are responsible for the uptake of oxLDL. Adipocyte enhancer-binding protein 1 (AEBP1) regulates many key genes associated with intracellular cholesterol efflux. The present study investigated the function of berberine, a compound isolated from Rhizoma coptidis, on foam cell formation, and explored the possible underlying mechanism. We found that berberine inhibited the oxLDL uptake of macrophages and reduced foam cell formation in a dose-dependent manner. Moreover, AEBP1 expression in macrophages increased and decreased after oxLDL and berberine treatments in a dose-dependent manner, respectively. Berberine reduced the expression of scavenger receptors CD36 and LOX-1, but did not affect the expression of CD68 in oxLDL-stimulated macrophages. Overall, berberine reduced foam cell formation by a dual mechanism, which decreased oxLDL internalization via the suppression of CD36 and LOX-1, and increased cholesterol efflux by inhibiting AEBP1 expression in macrophages.     

重组人肿瘤坏死因子受体融合蛋白治疗大鼠佐剂性关节炎的作用及对巨噬细胞功能的影响

目的:研究重组人肿瘤坏死因子受体融合蛋白(RhTNFR:Fc)对佐剂性关节炎(AA)大鼠模型的治疗作用及对巨噬细胞产生细胞因子的影响。方法:完全弗氏佐剂免疫SD大鼠诱导AA模型,随机分为正常组、模型组、RhTNFR:Fc低、中、高剂量组(1,3,9 mg.kg-1)和阴性对照组(IgG-Fc 9 mg.kg-1)。记录全身评分、关节炎指数、足爪肿胀度、关节肿胀数等整体评价指标、足爪X线摄片、踝关节病理检查及评分,ELISA试剂盒测定腹腔巨噬细胞(PMφ)上清中细胞因子白细胞介素1β(IL-1β),IL-6和肿瘤坏死因子α(TNF-α)水平。结果:RhTNFR:Fc给药组能不同程度地降低AA大鼠升高的全身评分、关节炎指数、足爪肿胀度和关节肿胀数等整体评价指标,减轻AA大鼠的关节炎症,改善AA大鼠X线摄片评分和关节病理学变化,下调PMφ的IL-1β,IL-6和TNF-α的分泌水平。结论:RhTNFR:Fc对大鼠AA的关节炎症具有治疗作用,且抑制腹腔巨噬细胞促炎性细胞因子的表达。     

灵芝多糖对小鼠腹腔巨噬细胞蛋白激酶C活性的影响

目的　观察灵芝多糖在体外对小鼠腹腔巨噬细胞(MΦ)蛋白激酶C(PKC)活性是否有影响。方法　采用反相离子对高效液相色谱法测定PKC活力。结果　灵芝多糖GLB7( 40mg·L-1)能引起小鼠腹腔MΦ中PKC活性明显升高 ,30min达峰值 ,2h恢复到基础水平 ;GLB7还可引起MΦ中PKC发生质膜转位 ,并拮抗Staurosporine对MΦ中PKC的抑制作用。结论　灵芝多糖的免疫增强作用与其增强PKC活性有关     

Inhibitory effect of acyl-CoA:cholesterol acyltransferase inhibitor-low density lipoprotein complex on experimental atherosclerosis

KV-2920 is a novel acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor. To confirm the efficacy of KV-2920-low density lipoprotein (LDL) complex (KV-LDL complex) as a drug-carrier complex on experimental atherosclerosis, we examined its inhibitory effects in vitro and in vivo. LDL was isolated from human plasma and the KV-LDL complex was prepared by incubation in the presence of Celite 545. The complex contained about 800 mol KV-2920 in 1 mol LDL. The cholesterol levels in the serum and aorta of atherogenic mice after 14 weeks of feeding were significantly higher than those of nonatherogenic mice. With the intravenous injection of KV-LDL complex, although the cholesterol levels in the serum were not influenced, the level of cholesterol ester in the aorta of atherogenic mice was significantly reduced. The concentration of cholesterol ester in the macrophages derived from ICR mice was predominantly increased by incubation with LDL for 48 h, this increase was significantly inhibited by incubation with KV-LDL complex. Moreover, the complex also inhibited the increase of cholesterol ester in macrophages following incubation with oxidized LDL. These findings suggest that KV-LDL complex inhibits the foam cell formation of macrophages though action of KV-2920 as an ACAT inhibitor, and prevents the accumulation of cholesterol ester in the aorta of atherogenic mice. Therefore, KV-LDL complex may be useful as a drug-carrier complex in antiatherosclerotic therapy.     

Antioxidative effect of schisanhenol on human low density lipoprotein and its quantum chemical calculation

AIM: To investigate the effect of schisanhenol (Sal) on copper ion-induced oxidative modulation of human low density lipoprotein (LDL). METHODS: The antioxidative activity of eight schisandrins (DCL) on microsome lipid peroxidation induced by Vit C/NADPH system was first observed, and then, the effect of Sal on Cu^2 -induced human LDL oxidation was studied. The generation of malondialdehyde (MDA), lipofuscin, reactive oxygen species (ROS), consumption of α-tocopherol as well as electrophoretic mobility of LDL were determined as criteria of LDL oxidation. Finally, the quantum chemical method was used to calculate the theoretical parameters of eight DCL for elucidating the difference of their antioxidant ability. RESULTS: Sal was shown to be the most active one among eight schizandrins in inhibiting microsome lipid oxidation induced by Vit C/NADPH. Sal 100, 50, and 10 μmol/L inhibited production of MDA, lipofuscin and ROS as well as the consumption of α-tocopherol in Cu^2 -induced oxidation of human LDL in a dose-dependent manner. Sal also reduced electrophoretic mobility of the oxidized human LDL. Further study of quantum chemistry found that Sal was the strongest one among eight DCL to scavenge O^-.2, R‘, RO‘, and ROO radicals. CONCLUSION: Sal has antioxidative effect on human LDL oxidation. The mechanism of Sal against LDL oxidation may be through scavenging free radicals.     

甲壳胺体外对小鼠巨噬细胞PKC和DAG的作用研究

目的 观察甲壳胺体外对小鼠腹腔巨噬细胞蛋白激酶C(PKC)活性和二酰基甘油(DAG)合成的影响。方法分别采用反相离子对高效液相色谱法与放射免疫测定技术测定PKC活力和DAG含量。结果 ①甲壳胺剂量依赖性引起巨噬细胞中PKC活性明显增强并使之发生质膜转位,达峰时间为25min,1.5 h恢复到基础水平;②甲壳胺促进巨噬细胞中DAG的合成,达峰时间为30 s,3 min恢复到基础水平。结论 甲壳胺的免疫增强作用与其增强巨噬细胞中PKC活性和DAG合成有关,DAG/PKC信号途径参与了其对巨噬细胞的活化过程。     

3，4—二苯基—3—吡咯啉—2—酮衍生物对小鼠腹腔巨噬细胞环氧酶1和2的抑制作用

目的:建立腹腔巨噬细胞模型评价化合物对环氧酶1和2的抑制作用.方法:放免法测定calcimycin、脂多糖刺激细胞将内源性花生四烯酸转化为6-keto-PGF_(1α)或PGE_2的量.GAPDH和环氧酶1/2的RNA用RT-PCR测定.结果:Rofecoxib选择性抑制脂多糖诱导的PGE_2合成,IC_(50)为(4.7±0.5)nmol/L,而抑制calcimycin诱导的6-keto-PGF_(1α)合成最大抑制率为17.3％.吲哚美辛对环氧酶1和2的IC_(50)分别为(4.7±1.1)nmol/L和(7.1±1.2)nmol/L.17个化合物中,系列Ⅱ化合物的活性与rofecoxib相当.磺酰胺基和内酰胺环的相对位置对抑制环氧酶2的活性很重要.结论:模型适用于药物设计的体外评价.3,4-二苯基-3-吡咯啉-2-酮衍生物有望成为新的环氧酶2选择性抑制剂.     

Effect of in vivo administration of T-2 toxin on peritoneal murine macrophages

We investigated the effect of in vivo administration of T-2 toxin, a 12,13-epoxytrichothecene produced by several Fusarium species, on murine macrophage metabolism. Cytoplasmic and lysosomal enzyme levels, generation and release of superoxide anion, phagocytosis and intracellular killing of Salmonella typhi and murine P815 tumour cell lysis were measured under different experimental conditions. When T-2 toxin was administered to mice at sublethal doses (0.50-1.00 mg/kg/24 hr), the levels of lysosomal and cytoplasmic enzyme activity and the generation of superoxide anion were significantly enhanced as compared to controls. This correlated with increased phagocytosis and intracellular killing of S. typhi. Cytotoxic activity against murine P815 mastocytoma cells exhibited by macrophages isolated from mice treated with T-2 toxin was inhibited in a dose-dependent manner. In vivo administration of T-2 toxin may result in the activation of specific metabolic pathways of peritoneal macrophages, while inhibiting other paths.     

灵芝多糖体外对小鼠腹腔巨噬细胞pH的影响

目的　探讨灵芝多糖（ＧＬＰ）对免疫细胞信号转导过程的影响。方法　采用激光扫描共聚焦显微镜技术,动态监测ＧＬＰ均一体组分ＧＬＢ７对小鼠腹腔巨噬细胞（ＭΦ）胞内ｐＨ（［ｐＨ］ｉ）的影响。结果　ＧＬＢ７引起小鼠腹腔ＭΦ［ｐＨ］ｉ明显升高,［ｐＨ］ｉ的升高与Ｎａ＋／Ｈ＋交换系统及细胞［Ｃａ２＋］ｉ有关。结论　ＭΦ是灵芝多糖作用的靶细胞,ＧＬＢ７引起ＭΦ［ｐＨ］ｉ快速升高的现象,是灵芝多糖产生作用的重要途径。     

灵芝多糖对小鼠腹腔巨噬细胞活性氧自由基的影响

为进一步探讨灵芝多糖 ( GLP)免疫调节作用机理 ,采用激光扫描共聚焦显微镜技术 ,动态监测灵芝多糖均一体 GLB7对小鼠腹腔巨噬细胞 ( M )活性氧自由基含量的影响 .以 GLB7( 2 0 mg· L-1)刺激 M ,发现探针 DCHF- DA的荧光强度明显下降 ,与静息水平相比 ,平均下降 ( 36± 6) % ( n=6,P<0 .0 5) ;同时还能拮抗 PMA引起的 M 呼吸爆发 ,荧光强度下降幅度为 ( 1 9± 4) % ( n=6,P<0 .0 5) .结果证明 :GLB7能减少 M 内活性氧自由基的生成 ,具有清除活性氧的作用 ,这也是 GLB7产生免疫增强和抗衰老作用的重要途径 .     

Comparative cellular uptake and cytotoxicity of a complex of daunomycin-low density lipoprotein in human squamous lung tumour cell monolayers

In an attempt to target cytotoxic drugs to tumour cells daunomycin-low density lipoprotein (LDL) complexes were synthesised. Human squamous lung tumour cells in vitro have large numbers of high affinity cell surface LDL receptors (Vmax = 19 ng LDL/micrograms cell protein per 24 hr; Km = 23 micrograms/ml). Cellular uptake of daunomycin and LDL-daunomycin was rapid and approached equilibrium by approximately 3 hr. Intracellular daunomycin concentrations were similar at each time point regardless of whether free drug or the complex was used. The degree of intracellular drug metabolism differed markedly with significantly higher production of daunomycinol following exposure to free daunomycin for 90 min. Daunomycin and LDL-daunomycin were equally cytotoxic in vitro (respective clonogenic ID90s of 1 microgram/ml and 0.7 microgram/ml). Fluorescence microscopy indicated that both free daunomycin and LDL-daunomycin have a punctate, granular distribution within the cytoplasm.     

Effect of lindane on mouse peritoneal macrophages.

Among the effects of lindane in vitro on mouse peritoneal macrophages, the inhibition of uridine incorporation correlated with the reduction of intracellular uridine pool was the most pronounced. This decrease was significant at a concentration of 10(-4) M after 12 h of treatment. The rate of leucine incorporation did not show any change during the 24-h study. The decrease in pinocytosis rate and acid phosphatase activity occurred with lindane concentrations superior to 10(-4) M or after treatment of more than 12 h. Pinocytosis inhibition may have been associated with cytoplasm vacuolation. The high lindane doses necessary to inhibit some of these macrophage functions belong to the range of concentrations exerting biological effects unrelated to its insecticidal effects, which involves stereochemical specificity. The effects of lindane on mouse peritoneal macrophages, similar to the effects of anesthetics, seemed to be determined by its lipophilicity, which may exert disordering effects in the lipid domains of the membrane. Such perturbations could involve changes in the conformation of transport sites as well as in the integrity of the membrane and cytoskeleton structures which govern the processes of pinocytosis and lysosomal fusion.