莊立民臺灣大學：臨床醫學研究所張以承Chang, Yi-ChengYi-ChengChang2007-11-272018-07-062007-11-272018-07-062006http://ntur.lib.ntu.edu.tw//handle/246246/55533脂肪組織會產生許多分泌性物質, 稱為脂肪激素(adipokines), 在人體的能量新陳代謝中扮演重要角色。 最近, 以基因差異表現方法(differential display method)找尋到一種新的可能的脂肪激素, 稱為visfatin/PBEF。研究顯示visfatin/PBEF在人類和小鼠身體中, 主要是表現在內臟脂肪組織(visceral fat), 而非皮下脂肪組織(subcutaneous fat), 而且其血清濃度會隨著肥胖而增高。Visfatin/PBEF在週邊組織會和胰島素受器結合, 具有類似胰島素的作用, 可以降低血糖。 為了釐清visfatin/PBEF在人體內的作用, 我們利用定量即時聚合酶鍊反應(quantitative real-time polymerase chain reaction, RT-PCR), 測定62位臺灣成年人中, 腹部內臟脂肪組織及皮下脂肪組織中visfatin/PBEF mRNA表現量, 並研究其與新陳代謝表現型(metabolic phenotypes)的關連。 我們發現visfatin/PBEF mRNA表現量在皮下脂肪組織中較在內臟脂肪組織中高(以比較閾值次數值comparative threshold cycle values △Ct 表示: -0.75 ± 2.71 v.s. –1.36 ± 2.47; p= 0.04), 尤其是在肥胖的人身上 (△Ct: -0.53 ± 2.57 v.s. –1.46 ± 2.41; p= 0.006)。兩者和身體質量指數(body mass index)皆無相關。皮下脂肪組織中visfatin/PBEF mRNA和飯前血清中胰島素濃度呈現正相關(r= 0.40, p= 0.008), 和胰島素阻抗指標Homeostasis Model Assessment (HOMA-IR) 也呈現正相關(r= 0.35, p= 0.02)。 我們進一步利用小鼠RAW 267.4 巨噬細胞株以及3T3-L1脂肪細胞株(這兩種細胞為脂肪組織中兩種主要表現visfatin/PBEF的細胞類型)為模型, 釐清脂肪組織中visfatin/PBEF 蛋白質表現可能的調節機轉。我們發現長時間(96小時)的游離脂肪酸(free fatty acids), 包括palmitate和oleate, 會大量增加巨噬細胞visfatin/PBEF的表現, 同時也會增加iNOS表現。NF-κB 抑制劑 parthenolide會抑制此作用, 而NF-κB促進劑 lipopolysaccharide會增加visfatin/PBEF表現。依此推測, 游離脂肪酸可能會經由活化NF-κB 而增加visfatin/PBEF表現。 Aspirin 及sodium salicylate為已知具有抑制 NF-κB 活性之非類固醇抗發炎藥物, 也會抑制visfatin/PBEF在巨噬細胞的表現, 相反的, ketorolac或indomethacin等其他非類固醇抗發炎藥物則沒有此作用。15-deoxy-Δ12,14-prostaglandin J2 是已知具有抑制NF-κB 活化作用的內生性peroxisome proliferator-activated receptor-γ(PPAR-γ)促進劑, 也會抑制visfatin/PBEF在巨噬細胞的表現, 相反的, 合成PPAR-γ促進劑rosiglitazone則沒有此作用。 簡言之, 我們的研究顯示高胰島素阻抗性的人其腹部皮下脂肪組織visfatin/PBEF mRNA表現量增加, 這增加可能和脂肪組織內巨噬細胞受游離脂肪酸刺激而活化有關。Context: Visfatin/PBEF was recently identified as an adipocytokine predominantly expressed and secreted in visceral adipose tissue with insulin-mimetic effect in peripheral tissues. Objectives: The goals were to investigate the association of visfatin/PBEF gene expresion in human abdominal adipose tissue with metabolic phenotypes and to identify the regulatory mechanism of visfatin/PBEF expression in cultured cells. Subjects and Methods: Relative visfatin/PBEF mRNA levels in human abdominal visceral and subcutaneous adipose tissues were determined by quantitative real-time polymerase chain reaction for correlation with metabolic phenotypes. Regulation of visfatin/PBEF expression by humoral factors was examined using cultured murine3T3-L1 adipocytes and RAW 264.7 macrophages. Results: Relative visfatin/PBEF mRNA levels in abdominal subcutaneous adipose tissue were higher than those in visceral adipose tissue and neither correlated with BMI. Relative visfatin/PBEF mRNA levels in abdominal subcutaneous adipose tissue correlated positively with fasting plasma insulin concentrations and with the insulin resistance index by Homeostasis Model Assessment(HOMA-IR). Free fatty acids (palmitate and oleate) and lipopolysaccharide stimulated visfatin/PBEF expression in RAW 264.7 macrophages but not 3T3-L1 adipocytes; the stimulation was mediated by NF-κB activation. Treatment with aspirin, sodium salicylate, or 15-deoxy-Δ12,14-prostaglandin J2 (15-d-PGJ2), but not indomethacin, ketorolac or rosiglitazone, suppressed visfatin/PBEF expression in RAW 264.7 macrophages. Conclusions: Visfatin/PBEF mRNA expression in abdominal subcutaneous adipose tissue is increased in hyperinsulinemic and insulin-resistant subjects. Visfatin/PBEF expression is induced by free fatty acids and inflammatory stimuli in macrophages rather than adipocytes. These findings support linkages among insulin resistance, macrophage activation, and increased visfatin/PBEF expression.口試委員, 指導教授與所長簽名………………………………………2 致謝………………………………………………………………………3 一、 中文摘要 (Abstract in Chinese)………………………5 二、 緒論 (Introduction)………………………………………6 三、 研究方法與對象 (Method and Subjects)………………8 四、 結果 (Results)…………………………………………10 五、 討論 (Discussion)………………………………………12 六、 侷限與展望 (Limitations and Perspective)…………15 七、 英文簡述 (Abstract in English)...…………………16 八、 英文論文 (English Manuscript)………………………18 九、 參考文獻 (References) …………………………………37 十、 圖表 (Figures and Tables)……………………………41919854 bytesapplication/pdfen-USvisfatinPBEF脂肪組織巨噬細胞游離脂肪酸發炎adipose tissuemacrophagefree fatty acidinflammationtexthttp://ntur.lib.ntu.edu.tw/bitstream/246246/55533/1/ntu-95-P93421031-1.pdf