Núñez L, Amigo L, Mingrone G, Rigotti A, Puglielli L, Raddatz A, Pimentel F, Greco A V, González S, Garrido J
Department of Gastroenterology, Pontificia Universidad Católica, Gantiago, Chile.
Gut. 1995 Sep;37(3):422-6. doi: 10.1136/gut.37.3.422.
Several biliary proteins have cholesterol crystallisation promoting activity. One of these glycoproteins is aminopeptidase-N, a canalicular ectoenzyme. This study attempted to localise aminopeptidase-N along the biliary tree, to assess its concentration in a series of 98 patients subjected to abdominal surgery, 40 of them without gall stones, and to correlate its concentration with cholesterol crystal formation time of gall bladder bile. Aminopeptidase-N was isolated from purified native biliary vesicles. A specific polyclonal rabbit anti-aminopeptidase-N antibody was prepared for quantitative immunoblotting and for immunolocalisation. Tissue was obtained from liver biopsy specimens and from gall bladders removed at surgery because of gall stone disease. Aminopeptidase-N was immunolocalised to the apical membranes of hepatocytes and to the apical pole of ductular and gall bladder mucosal cells. The nucleation time of gall bladder bile was mean (SD) 4 (3) days in the gall stone group, compared with 21 (18) days in the control group (p < 0.001). Total absolute biliary protein and aminopeptidase-N concentrations were similar in both the control and gall stone patients. There was a reciprocal significant correlation, however, between the nucleation time and the relative aminopeptidase-N concentration (r = -0.35, p < 0.01) only in the gall stone group of patients. This study shows that this apical transmembrane ectoenzyme with cholesterol crystallisation promoting activity is present along the biliary tree and the hepatocyte. These findings support the concept that high concentrations or qualitative changes of biliary aminopeptidase-N contribute to cholesterol gall stone formation.
几种胆汁蛋白具有促进胆固醇结晶的活性。其中一种糖蛋白是氨肽酶N，一种胆小管外切酶。本研究试图确定氨肽酶N在胆管树中的定位，评估其在98例接受腹部手术患者中的浓度，其中40例无胆结石，并将其浓度与胆囊胆汁中胆固醇晶体形成时间相关联。从纯化的天然胆汁小泡中分离出氨肽酶N。制备了一种特异性的兔抗氨肽酶N多克隆抗体，用于定量免疫印迹和免疫定位。组织取自肝活检标本和因胆结石疾病在手术中切除的胆囊。氨肽酶N免疫定位于肝细胞的顶膜以及胆小管和胆囊黏膜细胞的顶端。胆结石组胆囊胆汁的成核时间平均（标准差）为4（3）天，而对照组为21（18）天（p<0.001）。对照组和胆结石患者的总胆汁蛋白绝对浓度和氨肽酶N浓度相似。然而，仅在胆结石患者组中，成核时间与氨肽酶N相对浓度之间存在显著的负相关（r=-0.35，p<0.01）。本研究表明，这种具有促进胆固醇结晶活性的顶端跨膜外切酶存在于胆管树和肝细胞中。这些发现支持了胆汁氨肽酶N的高浓度或质量变化有助于胆固醇胆结石形成的观点。
