胆固醇逆向转运关键蛋白介导药物和小分子调控脂代谢的机制研究

胆固醇逆向转运(RCT)异常导致脂代谢紊乱是动脉粥样硬化发病重要环节,探讨介导RCT的关键蛋白在脂代谢中的作用及调控机制对阐明动脉粥样硬化发病的分子机制具有重要意义。本期专题收集的论文探讨了利拉鲁肽、苦瓜素以及生长分化因子11对细胞胆固醇流出及介导RCT中关键蛋白三磷酸腺苷结合盒转运体A1(ABCA1)、ABCG1和B类Ⅰ型清道夫受体表达的影响,分别从不同角度阐释RCT关键蛋白参与药物或小分子物质调控胆固醇流出的分子机制。     

ATP结合ABCA1在动脉粥样硬化性疾病发生发展中的作用机制研究进展

动脉粥样硬化(As)是导致各种血管疾病的主要原因,而过多的胆固醇在巨噬细胞中积累形成泡沫细胞是As的主要原因之一,ATP结合盒转运体A1(ABCA1)是高密度脂蛋白(HDL)和胆固醇逆转运(RCT)的重要调节因子。综述ABCA1在As性疾病发生发展中的作用机制发现,ABCA1可以抑制As的炎症反应,引起血管内皮细胞变化,参与氧化应激反应,通过多种代谢通路影响As。     

亲环素A对THP-1源性泡沫细胞ABCA1表达及胆固醇流出的影响及机制

目的观察亲环素A(CypA)对THP-1源性泡沫细胞三磷酸腺苷结合盒转运体A1(ABCA1)表达和胆固醇流出的影响及机制。方法 160 nmol/L佛波酯诱导人THP-1单核细胞分化为巨噬细胞,与50 mg/L氧化型低密度脂蛋白(ox-LDL)共孵育,使其荷脂形成泡沫细胞,常规体外培养细胞;实验分为对照组和Cyp A处理组;液体闪烁计数仪检测细胞胆固醇流出水平,高效液相色谱检测细胞内脂质成分,实时荧光定量PCR和Western blot检测ABCA1表达,Western blot检测核因子κB(NF-κB)核转位水平;NF-κB抑制剂小白菊内酯抑制NF-κB活化;脂质体2000转染CD147 siRNA至THP-1源性泡沫细胞。结果 CypA显著抑制THP-1源性泡沫细胞胆固醇流出,促进NF-κB核转位,下调ABCA1表达;NF-κB抑制剂小白菊内酯拮抗CypA对ABCA1表达及胆固醇流出的抑制作用;用siRNA干扰CD147后,显著抑制Cyp A诱导的NF-κB核转位,上调ABCA1表达,促进胆固醇流出。结论 CypA可能通过CD147激活NF-κB,下调ABCA1表达,抑制THP-1源性泡沫细胞胆固醇流出。     

参与负性调控胆固醇逆向转运的microRNA

加强胆固醇逆向转运(RCT)具有抗动脉粥样硬化作用,microRNA(miRNA)参与多种生物学过程的调控,研究发现多个miRNA参与RCT调控,其通过对RCT的关键蛋白ATP结合盒转运体A1(ABCA1)和受体B类Ⅰ型清道夫受体(SR-BⅠ)的调控而发挥作用。目前已发现多种miRNA可抑制ABCA1和SR-BⅠ蛋白表达水平,进而抑制RCT和胆固醇流出,本文拟就负性调控RCT的miRNA进行综述。     

Toll样受体4在幽门螺旋杆菌感染致动脉粥样硬化中的作用

动脉粥样硬化(As)是一种慢性炎症反应性疾病,幽门螺旋杆菌(Hp)感染与As性疾病的相关性研究日益引起关注,其促进As进展的具体机制尚未完全阐明。Toll样受体4(TLR4)是天然免疫反应的重要受体,在微生物致病因子及其产物引起宿主主动和被动免疫中有重要作用,参与动脉硬化的发生和发展。TLR4在As形成的多种细胞均有表达。TLR4通过捕获Hp的致病因子脂多糖后启动细胞内信号途径,进而引起核因子κB依赖的转录,引起一系列细胞因子及化学因子的释放,增强炎症反应而致病。本文就Hp、TLR4信号通路及其在As中的作用作一综述,为As疾病的防治提供新思路。     

核因子-κB对血管紧张素Ⅱ诱导THP-1源性泡沫细胞ATP结合盒转运子A1表达的影响

目的:探讨核因子-κB(NF-κB)对血管紧张素Ⅱ(AngⅡ)诱导THP-1源性泡沫细胞ATP结合盒转运子A1(ABCA1)表达的影响及在胆固醇流出中的作用。方法:THP-1源性泡沫细胞分别给予10-5mol/LAngⅡ(AngⅡ组)、10μmol/LNF-κB特异性抑制剂TPCK预孵(TPCK组)。采用夹心酶联免疫分析法检测泡沫细胞内NF-κB的活化程度。通过透射电镜和荧光分光光度计、酶化学法,检测泡沫细胞内胆固醇含量的变化。利用闪烁计数法测量泡沫细胞内胆固醇流出率。用逆转录-聚合酶链反应法和免疫印迹法半定量分析泡沫细胞ABCA1的表达。结果:TPCK组NF-κB活化核易位则无明显高峰,维持在较低的水平。TPCK组泡沫细胞内胆固醇含量较AngⅡ组降低24.1%(P<0.05),胆固醇流出率较AngⅡ组显著升高41.1%(P<0.05),ABCA1mR-NA和蛋白表达较AngⅡ组升高30%和19%(P<0.05)。结论:AngⅡ可经NF-κB介导下调THP-1源性泡沫细胞ABCA1的表达,致泡沫细胞内胆固醇流出减少,增加泡沫细胞内胆固醇含量,加速动脉粥样硬化。     

黄芪多糖在动脉粥样硬化发展过程中保护性作用的研究

目的:通过研究黄芪多糖(APS)对肿瘤坏死因子α(TNF-α)诱导的人急性单核白血病细胞(THP-1)源性泡沫细胞胆固醇流出率、细胞内总胆固醇含量以及细胞膜上脂质流出通道ATP-结合盒转运子A1(ABCA1)表达水平的影响,探讨APS在动脉粥样硬化发展过程中的保护作用。方法:将培养的THP-1源性巨噬细胞分为4组:对照组、单纯TNF-α组、TNF-α+APS组和单纯APS组。分别用RT-PCR法、Western blotting法检测ABCA1的mRNA及蛋白表达水平,闪烁计数法计算胆固醇流出率,酶化学法检测细胞内脂质含量,酶联免疫吸附法(ELISA法)测核因子-κB(NF-κB)的水平。结果:单纯TNF-α组ABCA1的mRNA和蛋白表达量、胆固醇流出率显著低于对照组(P<0.01),细胞内总胆固醇含量、NF-κB的水平显著高于对照组(P<0.05),而单纯APS组与对照组在上述指标上差异无统计学意义(P>0.05);与单纯TNF-α组比较,TNF-α+APS组ABCA1的mRNA和蛋白表达量、胆固醇流出率显著升高(P<0.01),细胞内总胆固醇含量、NF-κB的水平显著降低(P<0.01)。结论:APS能够使泡沫细胞ABCA1的表达及胆固醇流出率上升,而细胞内总胆固醇含量显著下降,并能够减弱泡沫细胞中NF-κB的活化水平。这些发现提示APS能够拮抗TNF-α对于ABCA1的下调作用,从而发挥抗动脉粥样硬化作用。     

ABCA1促胆固醇流出防治动脉粥样硬化的机制及调控

动脉血管的炎症反应和胆固醇的积累是动脉粥样硬化形成的高危因素,因此抑制巨噬细胞炎症反应和促进胆固醇流出已成为治疗动脉粥样硬化的有效途径。三磷酸腺苷结合盒转运体A1（ATP binding cassette transporter A1,ABCA1）能将细胞内游离胆固醇转运给贫脂的载脂蛋白A-I,从而促进高密度脂蛋白的形成,介导胆固醇的流出。miRNA（microRNA,miRNA） 作为一种非编码的微小RNA,通过降解靶基因mRNA或阻碍其翻译,发挥ABCA1转录后的调控作用。因此探究ABCA1的作用机制及调控有利于动脉粥样硬化的有效防治。     

以ABCA1为靶点防治动脉粥样硬化

动脉粥样硬化(atherosclerosis,As)是一个多因素参与的复杂疾病,其中血管壁胆固醇蓄积和炎症反应是其发生发展的两个关键环节,而两者又相互促进。三磷酸腺苷结合盒转运体A1(ATP binding cassette transporterA1,ABCA1)是一种膜整合蛋白,通过与载脂蛋白AⅠ(apoAⅠ)结合,促进细胞内胆固醇流出并抑制血管壁炎症反应。人类ABCA1基因突变导致血浆高密度脂蛋白(HDL)水平降低,并增加心血管疾病的风险。ABCA1基因敲除动物不仅表现出低的血浆HDL水平,还表现出胰腺β细胞功能紊乱、体内促炎状态和As斑块的形成。多种促As的炎症因子和代谢产物可能通过下调ABCA1的表达,从而促进As相关心血管疾病的发展。因此,ABCA1有望成为心血管疾病和糖尿病新的治疗靶标和研究方向。     

核转录因子与动脉粥样硬化关系的研究进展

核转录因子(NF-κB)是细胞浆内的快反应转录因子，能够调节多种炎症和免疫基因的表达。研究结果表明，NF-κB与多种慢性炎症性疾病的病理过程有关。动脉粥样硬化(As)是一种慢性炎症性疾病，NF-κB的激活及导致的炎症基因的表达在As发生发展中起重要作用。     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Presence of immunoreactive growth hormone and prolactin in the ovine pineal gland

Abstract: The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL-like ir-material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH-like immunoreactivity. Gel chromatography of the GH-like immunoreactivity (Sephadex G-100) indicated the presence of several GH-like fragments ranging in the M_r range of 7,000 to 55,000. Analyses of the PRL-like ir-material found in pineal tissue on HPLC using a TSK 545-DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir-peak from the TSK 545-DEAE column. The PRL-like ir-material inhibited the binding of [¹²⁵I]ovine PRL-S14 to anti-ovine PRL antibodies without showing an affinity for binding to anti-rat PRL or anti-bovine GH antibodies. Scatchard analysis of the binding of pineal PRL-like ir-material and pituitary ovine PRL-S14 to liver membranes from day-20 pregnant rats revealed similar affinity constants (K_a of 4.7 ± 0.2 × 10⁹ M^-1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones. The pineal PRL-like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of M_r 24,000. The functional status of PRL-and GH-like ir-material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the rat pineal responded to circulating concentrations of PRL.     

Microbiology of human immunodeficiency virus anorectal disease

PURPOSE: Individuals who are seropositive for the human immunodeficiency virus are at high risk for opportunistic infection and anorectal disorders. Little prospective information is available regarding anorectal pathogens in these patients. METHODS: One hundred sixty-three HIV-seropositive patients presented to the colorectal clinic between 1989 and 1992. Forty-seven (29 percent) patients were thought to have an infectious process and were prospectively studied using a standardized multiculture protocol. RESULTS: Mean age was 33 (range, 19–59) years. All were male; high-risk behavior accounted for 87 percent of HIV transmissions. Presenting complaints included anorectal pain (79 percent), pus per anum (28 percent), and blood per anum (26 percent). Examination revealed perianal tenderness (60 percent), condyloma (38 percent), perianal ulcers (38 percent), and anal fissures (34 percent). Sixty-six sets of cultures were performed; 28 patients had one set, 15 had two sets, and 4 had three sets. Thirty-two of these 47 patients (68 percent) had positive cultures including herpes (50 percent), cytomegalovirus (25 percent),Neisseria gonorrhoeae (16 percent), chlamydia (16 percent), acidfast bacilli (2 percent), and others (9 percent). Six of 32 patients with positive cultures had more than one organism cultured. Sixteen (50 percent) patients with positive cultures were treated medically, 8 (25 percent) were treated surgically and 8 (25 percent) were treated with both modalities. Sixty-one procedures were performed on 17 patients for condylomata. Eighteen patients had 20 procedures for abscesses, 50 percent of whom had positive cultures for other than common bowel flora; all improved. Fourteen patients underwent 33 procedures for perianal fistulas.Mycobacterium fortuitum was cultured from one patient who required 13 procedures for abscesses and fistulas. Forty-five (96 percent) patients were followed for an average of 12.5 months ±2.9 SEM (range, 1–94 months). Symptoms were improved or resolved in 22 of 32 (69 percent) patients with positive cultures and in 11 of 13 (84 percent) with negative cultures. CONCLUSIONS: Specific pathogens may often be identified in human immunodeficiency virus-seropositive patients with anorectal disorders if aggressively sought. Although patients without specific pathogens identified may be expected to improve with planned empiric treatment, positive identification allows more directed therapy.