Marzioni M, Alpini G, Saccomanno S, Candelaresi C, Venter J, Rychlicki C, Fava G, Francis H, Trozzi L, Benedetti A
Department of Gastroenterology, Università Politecnica delle Marche, Nuovo Polo Didattico, Via Tronto 10, 60020 Ancona, Italy.
Gut. 2009 Jul;58(7):990-7. doi: 10.1136/gut.2008.150870. Epub 2008 Oct 1.
Progression of chronic cholestatic disorders towards ductopenia results from the dysregulation of cholangiocyte survival, with cell death by apoptosis prevailing over compensatory proliferation. Currently, no therapy is available to sustain cholangiocyte survival in the course of those disorders. It was recently shown that cholangiocytes express the glucagon-like peptide-1 receptor (GLP-1R); its activation results in enhanced proliferative reaction to cholestasis. The GLP-1R selective agonist exendin-4 sustains pancreatic beta cell proliferation and prevents cell death by apoptosis. Exendin-4 is now employed in humans as a novel therapy for diabetes. The aim of the present study was to verify whether exendin-4 is effective in preventing cholangiocyte apoptosis.
In vitro, tests were carried out to determine if exendin-4 is able to prevent apoptosis of cholangiocytes isolated from normal rats induced by glycochenodeoxycholic acid (GCDCA); in vivo, animals subjected to 1 week of bile duct ligation and to a single intraperitoneal injection of CCl(4) were treated with exendin-4 for 3 days.
Exendin-4 prevented GCDCA-induced Bax mitochondrial translocation, cytochrome c release and an increase in caspase 3 activity. Phosphatidylinositol 3-kinase, but not cAMP/protein kinase A or Ca(2+)/calmodulin-dependent protein kinase inhibitors, neutralised the effects of exendin-4. In vivo, exendin-4 administration prevented the increase in TUNEL (terminal deoxynucleotidyl transferase-mediated triphosphate end-labelling)-positive cholangiocytes and the loss of bile ducts observed in bile duct-ligated rats treated with CCl(4).
Exendin-4 prevents cholangiocyte apoptosis both in vitro and in vivo; such an effect is due to the ability of exendin-4 to counteract the activation of the mitochondrial pathway of apoptosis. These findings support the hypothesis that exendin-4 may be effective in slowing down the progression of cholangiopathies to ductopenia.
慢性胆汁淤积性疾病向胆管减少发展是由于胆管细胞存活失调，凋亡导致的细胞死亡超过了代偿性增殖。目前，尚无疗法可在这些疾病过程中维持胆管细胞存活。最近研究表明胆管细胞表达胰高血糖素样肽-1受体（GLP-1R）；其激活会增强对胆汁淤积的增殖反应。GLP-1R选择性激动剂艾塞那肽可维持胰腺β细胞增殖并防止凋亡导致的细胞死亡。艾塞那肽目前作为糖尿病的新型疗法应用于人体。本研究的目的是验证艾塞那肽是否能有效预防胆管细胞凋亡。
在体外，进行试验以确定艾塞那肽是否能够预防从正常大鼠分离的胆管细胞因甘氨鹅去氧胆酸（GCDCA）诱导的凋亡；在体内，对接受1周胆管结扎并单次腹腔注射四氯化碳（CCl₄）的动物用艾塞那肽治疗3天。
艾塞那肽可预防GCDCA诱导的Bax线粒体转位、细胞色素c释放以及半胱天冬酶3活性增加。磷脂酰肌醇3激酶可中和艾塞那肽的作用，但环磷酸腺苷/蛋白激酶A或钙/钙调蛋白依赖性蛋白激酶抑制剂则不能。在体内，给予艾塞那肽可预防在接受CCl₄治疗的胆管结扎大鼠中观察到的TUNEL（末端脱氧核苷酸转移酶介导的dUTP缺口末端标记）阳性胆管细胞增加以及胆管丢失。
艾塞那肽在体外和体内均可预防胆管细胞凋亡；这种作用归因于艾塞那肽抵消凋亡线粒体途径激活的能力。这些发现支持了艾塞那肽可能有效减缓胆管病向胆管减少发展的假说。
