Trypsin activity is not involved in premature, intrapancreatic trypsinogen activation
Trypsin activity is not involved in premature, intrapancreatic trypsinogen activation
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DOI：
10.1152/ajpgi.00315.2001
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发表时间：
2002-02-01
影响因子：
4.5
通讯作者：
Lerch, MM
中科院分区：
文献类型：
--
作者：
Halangk, W;Krüger, B;Lerch, MM
消化酶原的过早和细胞内激活被认为是胰腺炎发病的原因。由于胰蛋白酶在启动肠道中消化酶的激活级联中具有关键作用，因此假定胰蛋白酶也启动胰腺中的细胞内酶原激活。我们已经测试了这一假设在离体腺泡和小叶从大鼠胰腺。细胞内胰蛋白酶原激活诱导的超大促分泌素刺激和测量使用特定的胰蛋白酶底物或免疫反应性的胰蛋白酶原激活肽（TAP）。为了防止胰蛋白酶诱导的胰蛋白酶原激活，我们使用了细胞平均的、高度特异性的、可逆的抑制剂N α-（2-萘磺酰基）-3-脒基苯丙氨酸-羧甲基哌嗪（S124），为了防止组织蛋白酶诱导的胰蛋白酶原激活，我们使用了半胱氨酸蛋白酶抑制剂E-64 d。在S124存在下孵育腺泡或小叶完全阻止了胰蛋白酶活性的产生，以响应于超大雨蛙素，但对TAP的产生没有任何影响。相反，当胰蛋白酶的活性恢复在实验结束时，无论是冲洗S124从腺泡或小叶匀浆的广泛稀释，它是高达400%高于单独雨蛙肽后，对应的，在摩尔方面，TAP的产生。E-64 d对胰蛋白酶活性和TAP释放的抑制作用是平行的。我们的结论是，在胰腺中的蛙皮素诱导的胰蛋白酶原激活是由E-64 d-可识别的机制，如组织蛋白酶诱导的胰蛋白酶原激活，既不涉及也不需要细胞内的胰蛋白酶活性。另一方面，特异性胰蛋白酶抑制可防止胰腺中80%的胰蛋白酶失活或自降解。
A premature and intracellular activation of digestive zymogens is thought to be responsible for the onset of pancreatitis. Because trypsin has a critical role in initiating the activation cascade of digestive enzymes in the gut, it has been assumed that trypsin also initiates intracellular zymogen activation in the pancreas. We have tested this hypothesis in isolated acini and lobules from rat pancreas. Intracellular trypsinogen activation was induced by supramaximal secretagogue stimulation and measured using either specific trypsin substrates or immunoreactivity of the trypsinogen activation peptide (TAP). To prevent a trypsin-induced trypsinogen activation, we used the cell-per-meant, highly specific, and reversible inhibitor Nalpha-(2-naphthylsulfonyl)-3-amidinophenylalanine-carboxymethylpiperazide (S124), and to prevent cathepsin-induced trypsinogen activation, we used the cysteine protease inhibitor E-64d. Incubation of acini or lobules in the presence of S124 completely prevented the generation of trypsin activity in response to supramaximal caerulein but had no effect whatsoever on the generation of TAP. Conversely, when trypsin activity was recovered at the end of the experiment by either washout of S124 from acini or extensive dilution of lobule homogenates, it was up to 400% higher than after caerulein alone and corresponded, in molar terms, to the generation of TAP. Both trypsin activity and TAP release were inhibited in parallel by E-64d. We conclude that caerulein-induced trypsinogen activation in the pancreas is caused by an E-64d-inhibitable mechanism such as cathepsin-induced trypsinogen activation, and neither involves nor requires intracellular trypsin activity. Specific trypsin inhibition, on the other hand, prevents 80% of trypsin inactivation or autodegradation in the pancreas.