Harte A L, McTernan P G, McTernan C L, Smith S A, Barnett A H, Kumar S
Division of Medical Sciences, Department of Medicine, University of Birmingham and Heartlands Hospital, Edgbaston, Birmingham, UK.
Diabetes Obes Metab. 2003 Sep;5(5):302-10. doi: 10.1046/j.1463-1326.2003.00276.x.
The aim of this study was to investigate the effect of insulin and an insulin-sensitizing agent, rosiglitazone (RSG), on the production of plasminogen-activator inhibitor-1 (PAI-1) in isolated subcutaneous abdominal adipocytes. Human tissue-type plasminogen activator (t-PA) was also measured to assess changes in overall thrombotic risk.
The mean depot-specific expression of PAI-1 and t-PA mRNA (n = 42) in subcutaneous abdominal (n = 21), omental (n = 10) and thigh (n = 11) adipose tissue depots was examined. Furthermore, subcutaneous adipocytes were treated with insulin, RSG and insulin in combination with RSG (10-8 m) for 48 h. Conditioned media were collected and enzyme-linked immunosorbent assays performed for PAI-1 and t-PA (n = 12) antigen. PAI-1 and t-PA mRNA levels were also assessed.
PAI-1 mRNA levels were significantly higher in subcutaneous and omental abdominal tissue than in thigh fat (p = 0.037 and p = 0.014). No change in t-PA mRNA expression between the adipose tissue depots was observed. Insulin stimulated PAI-1 protein secretion in a concentration-dependent manner in adipocytes (control: 68.3 +/- 1.2 ng/ml (s.e.m.); 10 nm insulin: 73.7 +/- 3.8 ng/ml upward arrow; 100 nm insulin: 86.8 +/- 4.1 ng/ml upward arrow **; 1000 nm insulin: 102.0 +/- 4.8 ng/ml upward arrow ***; **p < 0.01, ***p < 0.001). In contrast, insulin + RSG (10-8 m) reduced PAI-1 production relative to insulin alone (***p < 0.001), whilst RSG alone reduced PAI-1 protein secretion in a concentration-dependent manner (RSG at 10-10 m: 50.4 +/- 2.87 ng/ml downward arrow ***; RSG at 10-5 m: 30.3 +/- 2.0 ng/ml downward arrow ***; p < 0.001). No difference was observed between control and treatments for t-PA secretion (range 7-11 ng/ml).
Insulin stimulated PAI-1 secretion, whilst RSG reduced both PAI-1 secretion alone and in combination with insulin. These data suggest that adipose tissue may contribute significantly to the elevated circulating PAI-1 in obesity. Therefore, RSG's effects on PAI-1 production in adipose tissue may contribute to the fall in circulating PAI-1 levels observed in patients receiving RSG therapy.
本研究旨在探讨胰岛素及胰岛素增敏剂罗格列酮（RSG）对分离的腹部皮下脂肪细胞中纤溶酶原激活物抑制剂-1（PAI-1）生成的影响。同时检测人组织型纤溶酶原激活物（t-PA），以评估整体血栓形成风险的变化。
检测腹部皮下（n = 21）、网膜（n = 10）和大腿（n = 11）脂肪组织库中PAI-1和t-PA mRNA的平均库特异性表达（n = 42）。此外，将皮下脂肪细胞用胰岛素、RSG以及胰岛素与RSG联合（10⁻⁸ m）处理48小时。收集条件培养基，进行PAI-1和t-PA（n = 12）抗原的酶联免疫吸附测定。同时评估PAI-1和t-PA mRNA水平。
腹部皮下和网膜组织中PAI-1 mRNA水平显著高于大腿脂肪（p = 0.037和p = 0.014）。未观察到各脂肪组织库之间t-PA mRNA表达的变化。胰岛素以浓度依赖方式刺激脂肪细胞中PAI-1蛋白分泌（对照：68.3 ± 1.2 ng/ml（标准误）；10 nM胰岛素：73.7 ± 3.8 ng/ml↑；100 nM胰岛素：86.8 ± 4.1 ng/ml↑；1000 nM胰岛素：102.0 ± 4.8 ng/ml↑*；**p < 0.01，p < 0.001）。相反，胰岛素 + RSG（10⁻⁸ m）相对于单独使用胰岛素降低了PAI-1的生成（p < 0.001），而单独使用RSG以浓度依赖方式降低PAI-1蛋白分泌（10⁻¹⁰ m的RSG：50.4 ± 2.87 ng/ml↓；10⁻⁵ m的RSG：30.3 ± 2.0 ng/ml↓；p < 0.001）。t-PA分泌在对照与各处理组之间未观察到差异（范围7 - 11 ng/ml）。
胰岛素刺激PAI-1分泌，而RSG单独及与胰岛素联合使用时均降低PAI-1分泌。这些数据表明脂肪组织可能对肥胖患者循环中PAI-1升高有显著作用。因此，RSG对脂肪组织中PAI-1生成的影响可能有助于接受RSG治疗患者循环中PAI-1水平的下降。
