Impaired autophagic flux mediates acinar cell vacuole formation and trypsinogen activation in rodent models of acute pancreatitis
Impaired autophagic flux mediates acinar cell vacuole formation and trypsinogen activation in rodent models of acute pancreatitis
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DOI：
10.1172/jci38674
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发表时间：
2009-11-01
影响因子：
15.9
通讯作者：
Gukovskaya, Anna S.
中科院分区：
文献类型：
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作者：
Mareninova, Olga A.;Hermann, Kip;Gukovskaya, Anna S.
急性胰腺炎的发病机制尚不清楚。这种疾病的两个关键病理腺泡细胞反应是空泡积聚和胰蛋白酶原激活。我们通过比较啮齿动物急性胰腺炎模型中的自噬反应与禁食引发的生理性自噬反应，发现两者都是由缺陷性自噬引起的。胰腺炎引起的空泡在腺泡细胞的数量和更大的比禁食诱导。在体外胰腺炎中，长寿命蛋白质的降解（自噬效率的一个衡量指标）被显著抑制，而腺泡细胞饥饿则刺激了长寿命蛋白质的降解。此外，溶酶体蛋白酶组织蛋白酶L（CatL）和CatB加工成其完全活性，成熟的形式减少胰腺炎，因为它们的活动在溶酶体富集的亚细胞部分。这些发现表明，胰腺炎中的自噬是由于受损的组织蛋白酶加工引起的溶酶体降解不足而延迟的。胰蛋白酶原激活发生在胰腺炎，但不与禁食，并防止抑制自噬。胰蛋白酶原活化的标志物部分定位于自噬空泡，CatL的药理学抑制增加了腺泡细胞中活性胰蛋白酶的量。结果表明，延迟的自噬与CatL和CatB之间的不平衡有关，CatL降解胰蛋白酶原和胰蛋白酶，CatB将胰蛋白酶原转化为胰蛋白酶，导致胰腺炎中活性胰蛋白酶的腺泡内积累。因此，溶酶体降解不足可能是胰腺炎腺泡内胰蛋白酶升高的主要机制。
The pathogenic mechanisms underlying acute pancreatitis are not clear. Two key pathologic acinar cell responses of this disease are vacuole accumulation and trypsinogen activation. We show here that both result from defective autophagy, by comparing the autophagic responses in rodent models of acute pancreatitis to physiologic autophagy triggered by fasting. Pancreatitis-induced vacuoles in acinar cells were greater in number and much larger than those induced with fasting. Degradation of long-lived proteins, a measure of autophagic efficiency, was markedly inhibited in in vitro pancreatitis, while it was stimulated by acinar cell starvation. Further, processing of the lysosomal proteases cathepsin L (CatL) and CatB into their fully active, mature forms was reduced in pancreatitis, as were their activities in the lysosome-enriched subcellular fraction. These findings indicate that autophagy is retarded in pancreatitis due to deficient lysosomal degradation caused by impaired cathepsin processing. Trypsinogen activation occurred in pancreatitis but not with fasting and was prevented by inhibiting autophagy. A marker of trypsinogen activation partially localized to autophagic vacuoles, and pharmacologic inhibition of CatL increased the amount of active trypsin in acinar cells. The results suggest that retarded autophagy is associated with an imbalance between CatL, which degrades trypsinogen and trypsin, and CatB, which converts trypsinogen into trypsin, resulting in intra-acinar accumulation of active trypsin in pancreatitis. Thus, deficient lysosomal degradation may be a dominant mechanism for increased intra-acinar trypsin in pancreatitis.