Binding and biological effects of insulin,insulin analogues and insulin-like growth factors in rat aortic smooth muscle cells. Comparison of maximal growth promoting activities

Summary Binding and growth promoting effects of insulin, insulin analogues modified in the B chain, proinsulin, insulin-like growth factor-I and -II were studied in cultured rat aortic smooth muscle cells. Specific binding of¹²⁵I-insulin was 0.9±0.2% of total ¹²⁵I-insulin added, and the IC₅₀-value was estimated to 8.9 pmol/1. The insulin analogue B10 Asp tended to be more potent than insulin in displacing ¹²⁵I-insulin, B28 Asp was equipotent, B9 Asp/B27 Glu was approximately 100 times less potent and insulin-like growth factor-I more than 1000 times less potent than insulin. Specific binding of ¹²⁵I-insulin-like growth factor-I after 4 h incubation at 10 °C was five times higher than the specific binding of insulin (4.4±0.4% of total ¹²⁵I-insulin-like growth factor-I added), and the IC₅₀-value was 0.3 nmol/l. Insulin was approximately 500 times less potent than insulin-like growth factor-I in displacing ¹²⁵I-insulin-like growth factor-I. The insulin analogue B10 Asp was slightly more potent and analogue B28 Asp was equipotent with insulin. Analogue B9 Asp/B27 Glu was ten times less potent and proinsulin was more than ten times less potent than insulin. The order of potency was similar for ³H-thymidine incorporation into DNA: insulin-like growth factor-I > B10 Asp > insulin-like growth factor-II > insulin > B28 Asp > B9 Asp/B27 Glu > proinsulin. The maximal effect of insulin-like growth factor-I on ³H-thymidine incorporation was 71±16% higher than the maximal effect of insulin. The maximal effect of insulin-like growth factor-II was at least as high as the effect of insulin-like growth factor-I. Furthermore, the maximal effect of B10 Asp was 62±10% higher than the maximal effect of insulin. Insulin-like growth factor-I and B10 Asp tended to increase cell number more than insulin. In conclusion, this study shows that insulin analogues interact with different potencies with receptors for insulin and insulin-like growth factor-I in vascular smooth muscle cells and that insulin-like growth factors and the insulin analogue B10 Asp have more pronounced growth effects than insulin. Substitution of the amino acid Asp for His at position B10 in insulin makes the molecule more similar to insulin-like growth factor-I, chemically and probably also biologically.     

Effect of insulin on growth of cultured human arterial smooth muscle cells

Summary The effect of insulin (10–10000 mU/l) on the proliferation of cultured human arterial smooth muscle cells was studied. Smooth muscle cells were cultivated by explantation. Cells from the third to the fifth subculture were used. Proliferation was studied by growth curve experiments. Insulin stimulated cell proliferation in all concentrations (p <0.001). Growth was however stimulated more by a medium containing 10% fetal calf serum. The highest concentration of insulin produced only 35% of the effect of 10% fetal calf serum. Our results support the hypothesis that insulin may play a role in atherosclerosis.     

Expression and function of receptors for insulin-like growth factor-I and insulin in human coronary artery smooth muscle cells

Aims/hypothesis Hyperinsulinaemia and insulin resistance, as well as low IGF-I, have been implicated in the pathogenesis of cardiovascular disease. Little is known about direct effects of IGF-I and insulin on human coronary artery smooth muscle cells (HCASMCs). Our aim was to characterise the expression and function of IGF-I receptor (IGF-IR) and insulin receptor (IR) in HCASMCs.Materials and methods Cultured HCASMCs were used. mRNA expression was measured by quantitative real-time RT-PCR analysis. Receptor proteins, phosphorylation of -subunits and the presence of hybrid IR/IGF-IR were analysed by immunoprecipitation and western blotting. DNA synthesis and glucose metabolism were assessed using [³H]thymidine incorporation and d-[U-¹⁴C]glucose accumulation respectively.Results The mRNA expression of IGF-IR was approximately eight-fold higher than that of IR in HCASMCs. The presence of IGF-IR and IR could be demonstrated by immunoprecipitation and western blot analysis. Phosphorylation of the IGF-IR -subunit was obtained by IGF-I at 10^–10–10^–8 mol/l and insulin at 10^–8 mol/l. Insulin and IGF-I at 10^–10–10^–9 mol/l phosphorylated the IR -subunit. When immunoprecipitated with monoclonal anti-IR -subunit or IGF-IR -subunit antibodies, we found bands in slightly different positions, suggesting the presence of hybrid IR/IGF-IR. IGF-I at 10^–9–10^–8 mol/l significantly stimulated [³H]thymidine incorporation and at a concentration of 10^–9–10^–7 mol/l also d-[U-¹⁴C]glucose accumulation in HCASMCs. Insulin at 10^–9–10^–7 mol/l had no effect on DNA synthesis, but increased glucose accumulation at 10^–7 mol/l.Conclusions/interpretation Our study provides experimental evidence that IGF-IR and possibly hybrid IR/IGF-IR play a role in HCASMCs.     

胰岛素类似物的潜在致癌作用

近年来，越来越多的糖尿病患者使用胰岛素类似物控制血糖，联用超短效和超长效胰岛素类似物能更好地模拟生理性胰岛素释放，使血糖更平稳，但胰岛素类似物结构上的改变也导致了其生物学效应的改变，它们与胰岛素样生长因子-1（IGF-1）受体的亲和力也有异于普通胰岛素，其促有丝分裂活性的改变可能影响乳腺和肠道等部位恶性肿瘤的发生率。     

胰岛素样生长因子-1与胰岛素敏感性的关系

目的探讨胰岛素样生长因子1(IGF1)与胰岛素敏感性(IS)的关系。方法40例非糖尿病患者和68例新诊断的2型糖尿病患者参加研究,收集这些受试者的一般资料和生化特征资料。结果IGF1浓度与年龄、体重指数(BMI)、甘油三酯(TG)水平和收缩压及舒张压成负相关。IGF1浓度与高密度脂蛋白胆固醇(HDLC)和胰岛素敏感性的稳态评估(HOMAIR)成正相关。在包括性别、年龄、BMI、收缩压和舒张压、HDLC和甘油三酯等胰岛素敏感性调节因子在内的逐步线性回归分析发现,IGF1浓度独立的与胰岛素敏感性相关。符合世界卫生组织(WHO)定义的代谢综合征个体与非代谢综合征个体相比,IGF1浓度明显降低(P<0.01)。结论IGF1具有作为胰岛素抵抗综合征标志物的特征。较低的IGF1水平可能是一个确定具有心血管疾病风险个体的有用的标志物。     

Angiotensin AT1 receptor upregulates expression of basic fibroblast growth factor,basic fibroblast growth factor receptor and coreceptor in human coronary smooth muscle cells

Abstract. Autocrine stimulation and paracrine interaction between coronary smooth muscle cells (cSMC) and endothelial cells (EC) act as regulators of the vascular angiogenesis. Basic fibroblast growth factor (bFGF), its receptor FGF-R1, and coreceptor heparansulfate proteoglycan (HSPG) are important components involved in this angiogenic process. We investigated the influence of angiotensin (Ang) II on this trimolecular bFGF complex, the underlying signaling and the proliferative process in human cSMC. Ang II induces an AT1 receptor-dependent expression of bFGF and also upregulates the FGF-R1 and HSPG expression which is suppressed by losartan, the AT1 receptor blocker. AT1 receptor signaling which is characterized by phosphorylation of p42-mitogen-activated protein kinase (MAPK) is involved in Ang II-induced bFGF, FGF-R1 and HSPG upregulation and DNA synthesis in human cSMC. In contrast, inhibition of the AT2 receptor by PD123,319 has no influence on these Ang II-stimulated and via the MAPK cascade-mediated proangiogenic effects. Finally, our data show that the Ang II-induced DNA synthesis in cSMC is mediated via the bFGF expression. In conclusion, our results suggest that the Ang II-induced angiogenic effects in the vessel wall are supported by the AT1 receptor-stimulated and MAPK pathway-mediated upregulation of the autocrine/paracrine trimolecular bFGF complex in cSMC.     

血管内膜平滑肌细胞增殖状态下的凋亡细胞标记

目的探讨动脉损伤后内膜平滑肌细胞增殖状态下的凋亡细胞的水平及其出现的时间的部位,深入地研究血管成形术后再狭窄的形成机制,为抑制再狭窄的形成提供可能的干预措施。方法和结果应用球囊导管损伤小型猪髂动脉制备成内膜增殖所致的血管狭窄模型,采用计算机彩色图像分析系统动态观察损伤后１天、３天、６天、１２天和３０天的内膜平滑肌细胞增殖状况,并用末端转移酶介导的ｄＵＴＰ标记在ＤＮＡ３′－ＯＨ的方法（ＴＵＮＥＬ）来标记凋亡细胞。结果表明,损伤后６天以内,未出现凋亡细胞,从１２天起,仅在增殖的内膜中出现了较低水平的凋亡,即１２天（１．９４±０．４２）％和３０天（１．３６±０．３１）％,后二者差异无显著性。可以认为,较低水平的凋亡细胞可能是再狭窄形成过程中的病理学特征。结论平滑肌细胞的凋亡是血管损伤后狭窄形成过程中的一个重要的病理学特征,相比大量增殖的内膜平滑肌细胞,较低水平的凋亡可能是血管狭窄形成的机制之一,这提示,对低水平的凋亡进行适时适量的诱导,可能为抑制再狭窄提供新的选择。     

胰岛素对猪主动脉平滑肌细胞的增殖和前列环素合成的影响

以体外培养的猪主动脉平滑肌细胞为实验模型，研究了不同浓度胰岛素对其细胞增殖、前列环素合成的影响。结果显示胰岛素抑制平滑肌细胞的前列环素合成、促进细胞增殖都呈现剂量依赖性，提示高胰岛素血症可能是致动脉粥样样硬化的重要因素之一。     

固醇调节元件结合蛋白1c对骨骼肌细胞胰岛素受体底物1表达调控的影响

目的 探讨固醇调节元件结合蛋白1c（SREBP-1c）对大鼠骨骼肌细胞胰岛素受体底物1（IRS-1）表达调控的影响.方法 采用酶联合消化法取2～3 d SPF级雄性SD大鼠原代骨骼肌细胞,将原代细胞分为对照组（C）、对照＋胰岛素组（C＋I）、高脂组（PA）及高脂＋胰岛素组（PA＋I）.将表达SREBP-1c腺病毒转染L6细胞,根据感染复数（MOI）分为含绿色荧光蛋白阴性载体（GFP）组、MOI值为5、50、100、200组.将靶基因为SREBP-1c的干扰RNA （siRNA）转染L6细胞,并分为空白对照组、阴性siRNA组及SREBP-1c siRNA组.Western blotting和实时定量聚合酶链反应（RT-PCR）检测SREBP-1c、IRS-1、蛋白激酶B（Akt）基因及蛋白表达,油红O染色法检测细胞内脂质沉积情况.多组资料比较采用方差分析,两两比较采用最小显著差异法.结果 与C组相比,PA组SREBP-1c基因和蛋白水平升高（分别为2.72±0.08比1.00±0.18,3.02 ±0.19比1.00±0.05,t=15.240、18.289,均P＜0.05）,IRS-1基因和蛋白水平降低（分别为0.71 ±0.04比1.00 ±0.05,0.82 ±0.04比1.00±0.04,t=-7.960、-6.052,均P＜0.05）,丝氨酸磷酸化IRS-1蛋白表达升高,丝氨酸磷酸化Akt（p-Akt）蛋白表达下降（t=20.987、-5.869,均P＜0.05）.与GFP组相比,MOI值为50、100和200组的SREBP-1c基因和蛋白表达呈剂量依赖性上升（均P＜0.05）,IRS-1基因和蛋白表达水平呈剂量依赖性下降（均P＜0.05）.与空白对照组和阴性siRNA组相比,SREBP-1c siRNA组SREBP-1c基因和蛋白水平降低,IRS-1蛋白表达升高（均P＜0.05）.结论 SREBP-1c可抑制骨骼肌IRS-1胰岛素信号通路,参与肌细胞胰岛素抵抗的发生.     

The origin and differentiation potential of smooth muscle cells in coronary atherosclerosis

OBJECTIVES: To determine the phenotypical state of smooth muscle cells during the pathogenesis of an atherosclerotic lesion, and to determine the morphological state of the endothelium and the origin of foam cells. METHODS: Twenty-one samples of atherosclerotically changed right coronary arteries, which were divided into six subgroups based on the stage of atherosclerosis, were analyzed. The tissues were fixed in formalin and embedded in paraffin. Sections of 5 mum thickness were stained immunocytochemically using a labelled streptavidin-biotin/horse radish peroxidase kit (Dako, Denmark) for the identification of vimentin, alpha-smooth muscle actin, myosin heavy chains, desmin, S-100 protein, CD3, CD31, CD34, CD45, CD68 and proliferating cell nuclear antigen protein. RESULTS: The present study showed that there is first functional and then morphological damage of the endothelium in the late stages of atherosclerosis. The preatheroma stage revealed the presence of intimal changes of smooth muscle cells, with expression of vimentin and alpha-smooth muscle actin and a lack of expression of desmin, which led to a switch to a synthetic phenotype. The described changes progressed into the later stages of atherosclerosis. Along with these changes, a large number of foam cells of variant origin were observed; some of the foam cells developed from monocyte-macrophage lineage (CD68-immunoreactive) and others originated from smooth muscle cells (vimentin- and S-100-immunoreactive). The late stages of atherosclerosis development, such as the atheroma stage, include intimal changes with the formation of a lipid core (S-100-immunoreactive cells and cell necrosis), while fibrosis in the lipid core and the accumulation of collagen fibres with extreme hypocellularity are characteristics of the fibroatheroma stage.     

Evidence for the expression of transient receptor potential proteins in guinea pig airway smooth muscle cells

OBJECTIVE: The present study investigates the expression of transient receptor potential (TRPC) proteins in airway smooth muscle (ASM) cells in order to determine whether these proteins may be candidate molecular counterparts of plasma membrane Ca2+-permeable channels involved in the contraction of ASM. METHODS: Expression of TRPC mRNA was detected using specific primers and RT-PCR. Expression of the TRPC1, TRPC3 and TRPC6 proteins was detected using antibodies in immunoprecipitation and Western blot. RESULTS: Guinea pig ASM cells exhibited thapsigargin- and acetylcholine-initiated Ca2+ inflow but none by 1-oleoyl-2-acetyl-sn-glycerol. mRNA encoding each of the TRPC1 to TRPC6 proteins was detected in ASM cells. mRNA encoding TRPC1, TRPC3, TRPC4 and TRPC6 was detected in ASM cells at a concentration approximately equivalent to that in guinea pig brain. mRNA encoding TRPC2 and TRPC5 was more abundant in ASM cells than in brain. The TRPC1 protein, but not the TRPC3 or TRPC6 proteins, was detected in extracts of ASM cells, while all three proteins were detected in brain. CONCLUSION: The results provide evidence for a low level of expression of the TRPC1 to TRPC6 proteins in ASM cells. These proteins may function as store-operated Ca2+ and/or second messenger-activated non-selective cation channels in ASM cells.     

Enhanced caveolin-1 expression in smooth muscle cells: Possible prelude to neointima formation

AIM: To study the genesis of neointima formation in pulmonary hypertension (PH), we investigated the role of caveolin-1 and related proteins.METHODS: Male Sprague Dawley rats were given monocrotaline (M, 40 mg/kg) or subjected to hypobaric hypoxia (H) to induce PH. Another group was given M and subjected to H to accelerate the disease process (M + H). Right ventricular systolic pressure, right ventricular hypertrophy, lung histology for medial hypertrophy and the presence of neointimal lesions were examined at 2 and 4 wk. The expression of caveolin-1 and its regulatory protein peroxisome proliferator-activated receptor (PPAR) γ, caveolin-2, proliferative and anti-apoptotic factors (PY-STAT3, p-Erk, Bcl-xL), endothelial nitric oxide synthase (eNOS) and heat shock protein (HSP) 90 in the lungs were analyzed, and the results from M + H group were compared with the controls, M and H groups. Double immunofluorescence technique was used to identify the localization of caveolin-1 in pulmonary arteries in rat lungs and in human PH lung tissue.RESULTS: In the M + H group, PH was more severe compared with M or H group. In the 4 wk M+H group, several arteries with reduced caveolin-1 expression in endothelial layer coupled with an increased expression in smooth muscle cells (SMC), exhibited neointimal lesions. Neointima was present only in the arteries exhibiting enhanced caveolin-1 expression in SMC. Lung tissue obtained from patients with PH also revealed neointimal lesions only in the arteries exhibiting endothelial caveolin-1 loss accompanied by an increased caveolin-1 expression in SMC. Reduction in eNOS and HSP90 expression was present in the M groups (2 and 4 wk), but not in the M + H groups. In both M groups and in the M + H group at 2 wk, endothelial caveolin-1 loss was accompanied by an increase in PPARγ expression. In the M + H group at 4 wk, increase in caveolin-1 expression was accompanied by a reduction in the PPARγ expression. In the H group, there was neither a loss of endothelial caveolin-1, eNOS or HSP90, nor an increase in SMC caveolin-1 expression; or any alteration in PPARγ expression. Proliferative pathways were activated in all experimental groups.CONCLUSION: Enhanced caveolin-1 expression in SMC follows extensive endothelial caveolin-1 loss with subsequent neointima formation. Increased caveolin-1 expression in SMC, thus, may be a prelude to neointima formation.     

可罗卡林对血管平滑肌细胞增殖及c-myc基因表达的影响

目的：观察对大鼠主动脉平滑肌细胞起负调节作用的可罗卡林(cromakalim对同型半胱氨酸(hcy)刺激的血管平滑肌细胞(vascular smooth muscle cells，VSMC)增殖及c—myc基因表达的影响。方法：在建立hcy诱导的平滑肌细胞增殖模型后，应用流式细胞术观察VSMC增殖周期的变化；并用免疫细胞化学方法观察可罗卡林对VSMC增殖及c—myc基因蛋白表达的影响。结果：可罗卡林使VSMC处于G0／G1期的细胞数显著增多(P＜0．01)，S期G2 M期的细胞数显著减少(P＜0．01．)，能够抑制hcy诱导的VSMC增殖和c—myc基因蛋白表达的增加。结论：可罗卡林对hcy诱导的VSMC增殖有显著的抑制作用，其作用机制与抑制c—myc基因表达有关。     

Reasons for the degeneration of ageing skeletal muscle: a central role for IGF-1 signalling

This paper examines two major possibilities for the striking loss of skeletal muscle mass and strength that occurs in very old animals and humans. It is concluded that muscle regeneration is not significantly impaired with age. Instead, it seems that individual myofibres undergo atrophy, with selective death of the fast type 2B myofibres, due to the combined effects of many age-related changes the main causes being: nutrition(under-nutrition and lack of vitamin D),decreased hormone levels (e.g growth hormone, testosterone), reduced physical activity, and a loss of nerves that innervate the muscles. The discussion focusses on the central role of a local muscle form of insulin-like growth factor-I (IGF-I) in muscle hypertrophy, atrophy and motor neurone loss. Reduced IGF-Isignalling is involved in muscle atrophy and results from decreased muscle exercise, reduced growth hormone and insulin levels, reduced vitamin D, and treatment with drugs like corticosteroids, dexamethasone, and cyclosporin. In addition, elevated levels of inflammatory cytokines like TNF-α and IL-6can cause muscle wasting (cachexia) although this is usually associated with disease, andTNF-α may also act (at least in part) by inhibiting IGF-I signalling. The possible clinical prevention of age-related muscle wasting (and associated motor neurone loss) by the locally acting muscle isoform of IGF-I is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cannabinoid type 1 receptors in human skeletal muscle cells participate in the negative crosstalk between fat and muscle

Aims/hypothesis  Cannabinoid type 1 receptor (CB1R) antagonists such as rimonabant (Rim) represent a novel approach to treat obesity and related metabolic disorders. Recent data suggest that endocannabinoids are also produced by human adipocytes. Here we studied the potential involvement of endocannabinoids in the negative crosstalk between fat and muscle. Methods  The protein level of CB1R in human skeletal muscle cells (SkM) during differentiation was analysed using western blotting. SkM were treated with adipocyte-conditioned medium (CM) or anandamide (AEA) in combination with the CB1R antagonists Rim or AM251, and insulin-stimulated Akt phosphorylation and glucose uptake were determined. Furthermore, signalling pathways of CB1R were investigated. Results  We revealed an increase of CB1R protein in SkM during differentiation. Twenty-four hour incubation of SkM with CM or AEA impaired insulin-stimulated Akt(Ser473) phosphorylation by 60% and up to 40%, respectively. Pretreatment of cells with Rim or AM251 reduced the effect of CM by about one-half, while the effect of AEA could be prevented completely. The reduction of insulin-stimulated glucose uptake by CM was completely prevented by Rim. Short-time incubation with AEA activated extracellular regulated kinase 1/2 and p38 mitogen-activated protein kinase, and impaired insulin-stimulated Akt(Ser473) phosphorylation, but had no effect on Akt(Thr308) and glycogen synthase kinase 3α/β phosphorylation. In addition, enhanced IRS-1 (Ser307) phosphorylation was observed. Conclusions/interpretation  Our results show that the CB1R system may play a role in the development of insulin resistance in human SkM. The results obtained with CM support the notion that adipocytes may secrete factors which are able to activate the CB1R. Furthermore, we identified two stress kinases in the signalling pathway of AEA and enhanced IRS-1(Ser307) phosphorylation, potentially underlying the development of insulin resistance. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorised users.     

Insulin analogues (insulin detemir and insulin aspart) versus traditional human insulins (NPH insulin and regular human insulin) in basal-bolus therapy for patients with Type 1 diabetes

Aims/hypothesis The aim of the trial was to compare the efficacy and tolerability of two types of basal-bolus therapy, using either the soluble long-acting basal insulin analogue, insulin detemir, in combination with the rapid-acting analogue, insulin aspart, or NPH insulin in combination with mealtime regular human insulin.Methods In this 18-week, 1:1 randomised, open-labelled, parallel trial, 595 patients with Type 1 diabetes mellitus received insulin detemir or NPH insulin in the morning and at bedtime in combination with mealtime insulin aspart or regular human insulin respectively.Results Glycaemic control with insulin detemir/insulin aspart was improved in comparison with NPH insulin/regular human insulin (HbA₁c: 7.88% vs 8.11%; mean difference: –0.22% point [95% CI: –0.34 to –0.10]; p<0.001). Self-measured 8-point plasma glucose profiles differed between the groups (p<0.001), with lower postprandial plasma glucose levels in the insulin detemir/insulin aspart group. Within-person day-to-day variation in plasma glucose was lower with insulin detemir/insulin aspart than with NPH insulin/regular human insulin (SD: 2.88 vs 3.12 mmol/l; p<0.001). Risk of overall and nocturnal hypoglycaemia (23.00–06.00 hours) was, respectively, 21% (p=0.036) and 55% (p<0.001) lower in the insulin detemir/insulin aspart group than in the NPH insulin/regular human insulin group. Body weight (adjusted for baseline and change in HbA₁c) was 1 kg lower with insulin detemir/insulin aspart than with NPH insulin/regular human insulin (p<0.001).Conclusions/interpretation Basal-bolus therapy using insulin detemir/insulin aspart offers a better balance of control and tolerability than with NPH insulin/regular human insulin. The low variability and more physiological action profiles generated with these insulin analogues resulted in improved glycaemic control with lower risk of hypoglycaemia and no concomitant body weight increase.     

Glucose and insulin independently reduce the fibrinolytic potential of human vascular smooth muscle cells in culture

Summary Hyperglycaemia and hyperinsulinaemia have both been related to accelerated atherosclerosis in non-insulin-dependent diabetes mellitus (NIDDM). Plasma fibrinolytic potential is reduced in NIDDM and it is known that glucose and insulin can modulate plasminogen activator inhibitor (PAI-1) and tissue-plasminogen activator (t-PA) secretion and can therefore regulate local fibrinolysis. Vascular smooth muscle cells (vSMC) play an important role in the development of atherosclerotic lesions; however, the role of insulin and glucose in regulating PAI-1 and t-PA production in vSMC is presently not known. Therefore, we cultured arterial vSMC explanted from human umbilical cords and exposed them to increasing concentrations of glucose (5, 12, 20, 27, 35 mmol/l) or insulin (0.1, 0.5, 1, 10 nmol/l) in a serum free medium. After 24 h, PAI-1 and t-PA antigens and activity were evaluated in the culture medium; in cells exposed to 20 mmol/l glucose and to 0.5 nmol/l insulin PAI-1 gene expression was also evaluated. An increase in PAI-1 antigen was observed at each glucose concentration (by 138, 169, 251 and 357 % as compared to 5 mmol/l glucose) which was paralleled by an increase in PAI-1 activity. t-PA concentration was also increased by glucose but its activity was sharply reduced. An increase in PAI-1 antigen was detected at each insulin level (by 121, 128, 156 and 300 % as compared to no insulin). PAI-1 activity was slightly increased at the lowest insulin concentrations but markedly increased by 10 nmol/l insulin. t-PA antigen was also increased by insulin; however, its activity was markedly reduced at each concentration. As compared to control cells, PAI-1 mRNA was increased by 2.5 and 2.0 fold by 20 mmol/l glucose and 0.5 nmol/l insulin, respectively. We conclude that in human vSMC both glucose and insulin can affect the fibrinolytic balance so as to reduce fibrinolytic potential. This might contribute to decreased local fibrinolysis and thereby might accelerate the atherothrombotic process in NIDDM subjects. [Diabetologia (1996) 39: 1425–1431] Received: 5 June 1996 and in revised form: 29 July 1996     

果蝇样受体4介导游离脂肪酸调节人血管平滑肌细胞单核细胞趋化蛋白-1的表达

目的探讨软脂酸对人主动脉血管平滑肌细胞（HA—VSMC）单核细胞趋化蛋白-1（MCP-1）基因表达的调节及果蝇样受体4（TLR4）信号通路的作用。方法采用不同剂量的软脂酸（100、200、400μmol/L）处理HA—VSMC6、12、24h,采用实时荧光定量聚合酶链反应（PCR）检测细胞MCP．1mRNA表达,酶联免疫吸附实验（ELISA）检测MCP-1蛋白表达,观察软脂酸调节MCP-1表达的剂量依赖关系和时间效应;采用蛋白激酶C（PKC）抑制剂白屈菜红碱、磷脂酰肌醇3激酶（P13K）抑制剂wortmannin、神经酰胺抑制剂myriocin和核因子KB（NF—KB）抑制剂parthenolide分别处理细胞30min,再加入软脂酸（400μmol/L）处理细胞6h后,实时荧光定量PCR检测MCP-1mRNA的表达水平,ELISA检测MCP-1的蛋白表达水平,研究软脂酸调节MCP-1表达依赖的信号通路;构建TLR4短发夹RNA（shRNA）腺病毒pGSadeno-TLR4并感染HA—VSMC沉默TLR4基因表达,实验同时设空白对照组（PBS缓冲液）和对照病毒（pGSadeno-GFP）组。细胞感染96h后更换培养基,再加入软脂酸（400μmoL／L）处理细胞6h,采用实时荧光定量PCR检测MCP-1mRNA表达水平,ELISA检测MCP-1的蛋白表达水平。提取细胞核蛋白,采用ELISA检测NF—KBp65亚基活性,观察TLR4／NF-KB通路在软脂酸调节HA-VSMCMCP-1基因表达中的作用。组间均数比较采用单因素方差分析。结果采用软脂酸处理细胞6h后,对照组及100、200和400μmoVL软脂酸组MCP-1mRNA表达分别为1．00±0．02、3．30±2．84、8．21±4．31和11．25±2．73（F=7．57,P〈0．05）;MCP-1蛋白表达分别为（127±10）、（147±10）、（163±18）和（194±14）ng／L（F=7．81,P〈0．05）。软脂酸可促进HA-VSMCMCP-1mRNA和蛋白表达且具有明显的剂量依赖关系。细胞培养12h和24h后,随着软脂酸浓度的增加,MCP-1mRNA和蛋白表达水平呈逐渐增加趋势,但时间效应则不明显。采用不同的信号通路抑制剂和软脂酸处理细胞6h后,对照组、软脂酸组、软脂酸＋parthenolide组、软脂酸＋白屈菜红碱组、软脂酸＋wortmannin组和软脂酸＋myriocin组MCP-1mRNA表达分别为1．00±0．02、10．80±1．23、3．49±0．28、10．84±0．24、11．24±0．27和10．62±0．36（F=1313．07,P〈0．05）;MCP-1蛋白表达分别为（132±8）、（218±12）、（152±4）、（213±12）、（225±7）和（226±9）ng／L（F=106．83,P〈0．05）。成功地构建并获得TLR4shRNA腺病毒pGSadeno—TLR4,采用pGSadeno-TLR4感染HA—VSMC阻断TLR4信号后,软脂酸＋pGSadeno．TLR4组的NF—KB065结合活性、MCP-1mRNA和蛋白表达均显著低于软脂酸组[分别为0．48±0．12比1．24±0．16、1．88±0．33比10．80±1．23、（154±10）比（218±12）ng／L;F=591．86、659．16、118．37,均P〈0．01]。而对照病毒pGSadeno．GFP对软脂酸诱导的NF—KB065结合活性和MCP：I表达均无明显影响。结论TLR4／NF—KB信号通路介导了软脂酸诱导的人主动脉血管平滑肌细胞MCP-1基因表达。     

1-磷酸鞘氨醇受体1参与晚期糖基化终产物引起的血管平滑肌细胞增殖和迁移

目的观察1-磷酸鞘氨醇受体1(S1PR1)在晚期糖基化终产物(AGE)引起的血管平滑肌细胞增殖和迁移中的作用。方法培养人脐动脉平滑肌细胞(HUASMC),葡萄糖与牛血清白蛋白(BSA)孵育法获得AGE-BSA,分为对照组、BSA组和AGE-BSA组,采用CCK-8实验检测平滑肌细胞增殖能力,采用细胞划痕和Transwell实验检测平滑肌细胞迁移能力,并进一步观察BSA和AGE-BSA在有或无S1PR1拮抗剂VPC23019/激动剂SEW2871预处理后的细胞增殖和迁移。结果与对照组比较,BSA和AGE-BSA均能诱导HUASMC增殖和迁移,AGE-BSA的作用比BSA更加显著(P0.05);S1PR1拮抗剂VPC23019可以明显抑制BSA和AGE-BSA诱导的HUASMC增殖和迁移;S1PR1激动剂SEW2871本身就可以促进HUASMC增殖和迁移,并且进一步促进BSA诱导的HUASMC增殖和迁移,而对AGE-BSA诱导的HUASMC增殖和迁移没有进一步的促进作用。结论血浆白蛋白本身对平滑肌细胞的增殖具有促进作用,糖基化修饰的白蛋白这一作用更加明显;S1PR1的激活参与了BSA和AGE-BSA促进平滑肌细胞增殖和迁移,AGE-BSA对S1PR1的激活作用更加显著。