Choi J, Klinkspoor J H, Yoshida T, Lee S P
Department of Surgery, Chungbuk National University Hospital, Seoul, South Korea.
Hepatology. 1999 May;29(5):1352-7. doi: 10.1002/hep.510290515.
Biliary infection is associated with mucin hypersecretion by the biliary epithelium. Mucins have been identified as potent pronucleators of cholesterol in bile. The aim of the present study was to determine whether lipopolysaccharides (LPS) from different bacteria are capable of stimulating mucin secretion by cultured dog gallbladder epithelial (DGBE) cells, and to investigate the mechanism by which LPS stimulate mucin secretion. Mucin secretion by confluent monolayers of DGBE cells was quantified by measuring the secretion of [3H]-N-acetyl-D-glucosamine-labeled glycoproteins. Cell viability was evaluated by measuring the leakage of the enzyme, lactate dehydrogenase (LDH), into the culture medium. LPS, derived from Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa (200 microg/mL), all caused an increase in mucin secretion by the DGBE cells, without causing concomitant cell lysis. LPS from E. coli was found to be the most potent stimulator of mucin secretion, and increased mucin secretion by the DGBE cells to 252% +/- 14% of control. LPS from E. coli had no effect on intracellular cyclic adenosine monophosphate (cAMP) levels in the DGBE cells. Addition of the nitric oxide (NO)-releasing compound, NOR-4 (0.125-1 mmol/L), to the cells did not result in increased mucin secretion, and the NO synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME) (4 or 10 mmol/L), did not inhibit the LPS-stimulated mucin secretion. Exogenous tumor necrosis factor alpha (TNF-alpha) (1-10 ng/mL) did cause a minor increase in mucin secretion by the DGBE cells, but the effect of LPS from E. coli on mucin secretion could not be inhibited by preincubation with a TNF-alpha antibody (10 microg/mL). We conclude that LPS stimulates mucin secretion by the gallbladder epithelium. Whether this stimulation is mediated by TNF-alpha remains to be determined.
胆道感染与胆管上皮细胞粘蛋白分泌过多有关。粘蛋白已被确定为胆汁中胆固醇的强效促核剂。本研究的目的是确定来自不同细菌的脂多糖（LPS）是否能够刺激培养的犬胆囊上皮（DGBE）细胞分泌粘蛋白，并研究LPS刺激粘蛋白分泌的机制。通过测量[3H]-N-乙酰-D-葡萄糖胺标记的糖蛋白的分泌来定量DGBE细胞汇合单层的粘蛋白分泌。通过测量乳酸脱氢酶（LDH）泄漏到培养基中的量来评估细胞活力。源自大肠杆菌、肺炎克雷伯菌和铜绿假单胞菌的LPS（200μg/mL）均导致DGBE细胞粘蛋白分泌增加，且未引起伴随的细胞裂解。发现大肠杆菌来源的LPS是粘蛋白分泌的最有效刺激物，使DGBE细胞的粘蛋白分泌增加至对照的252%±14%。大肠杆菌来源的LPS对DGBE细胞内的环磷酸腺苷（cAMP）水平没有影响。向细胞中添加一氧化氮（NO）释放化合物NOR-4（0.125-1 mmol/L）不会导致粘蛋白分泌增加，且NO合酶抑制剂Nω-硝基-L-精氨酸甲酯（L-NAME）（4或10 mmol/L）不会抑制LPS刺激的粘蛋白分泌。外源性肿瘤坏死因子α（TNF-α）（1-10 ng/mL）确实导致DGBE细胞的粘蛋白分泌略有增加，但用TNF-α抗体（10μg/mL）预孵育不能抑制大肠杆菌来源的LPS对粘蛋白分泌的影响。我们得出结论，LPS刺激胆囊上皮细胞分泌粘蛋白。这种刺激是否由TNF-α介导仍有待确定。
