Cathepsin D regulates cathepsin B activation and disease severity predominantly in inflammatory cells during experimental pancreatitis
Cathepsin D regulates cathepsin B activation and disease severity predominantly in inflammatory cells during experimental pancreatitis
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DOI：
10.1074/jbc.m117.814772
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发表时间：
2018-01-19
影响因子：
4.8
通讯作者：
Lerch, Markus M.
中科院分区：
文献类型：
--
作者：
Aghdassi, Ali A.;John, Daniel S.;Lerch, Markus M.
急性胰腺炎是一种复杂的疾病，涉及过早的细胞内蛋白酶激活和炎性细胞侵袭。起始事件是组织蛋白酶B（CTSB）对胰蛋白酶原的细胞内活化，其可通过腺泡细胞上的G蛋白偶联受体或通过炎性细胞直接诱导。在这里，我们研究了另一种溶酶体水解酶，组织蛋白酶D（CTSD）的CTSB调节，使用具有完全（CTSD-/-）或胰腺特异性条件性CTSD敲除（KO）（CTSD（f/f/）p48（Cre/+））的小鼠。我们通过反复注射雨蛙肽诱导急性胰腺炎，并分离腺泡和骨髓细胞进行体外研究。超最大雨蛙肽刺激诱导CTSD从溶酶体到腺泡细胞的含酶原亚细胞区室的亚细胞重新分布，并激活CTSD、CTSB和胰蛋白酶原。值得注意的是，CTSD KO大大降低了腺泡细胞中的CTSB和胰蛋白酶原活化，并且CTSD在体外直接活化CTSB而不是胰蛋白酶原。在胰腺特异性CTSD（f/f/）p48（Cre/+）动物的胰腺炎期间，严重程度标志物仅在1小时降低，而在完全KO中，这种作用还包括晚期疾病阶段（8小时），表明腺泡外CTSD对疾病进程的重要影响。CTSD-/-白细胞在脂多糖（LPS）刺激后表现出减少的细胞因子释放，CTSD KO还减少了肠激素胆囊收缩素刺激的腺泡细胞中的caspase-3活化和凋亡。总之，CTSD在胰腺腺泡和炎性细胞中表达，在实验性胰腺炎期间经历亚细胞再分布和激活，并通过有效激活CTSB来调节疾病严重程度。其影响在胰腺炎的早期腺泡细胞依赖性阶段仅是微小和短暂的，而在疾病的晚期炎性细胞依赖性阶段则大得多。
Acute pancreatitis is a complex disorder involving both premature intracellular protease activation and inflammatory cell invasion. An initiating event is the intracellular activation of trypsinogen by cathepsin B (CTSB), which can be induced directly via G protein-coupled receptors on acinar cells or through inflammatory cells. Here, we studied CTSB regulation by another lysosomal hydrolase, cathepsin D (CTSD), using mice with a complete (CTSD-/-) or pancreas-specific conditional CTSD knockout (KO) (CTSD(f/f/)p48(Cre/+)). We induced acute pancreatitis by repeated caerulein injections and isolated acinar and bone marrow cells for ex vivo studies. Supramaximal caerulein stimulation induced subcellular redistribution of CTSD from the lysosomal to the zymogen-containing subcellular compartment of acinar cells and activation of CTSD, CTSB, and trypsinogen. Of note, the CTSD KO greatly reduced CTSB and trypsinogen activation in acinar cells, and CTSD directly activated CTSB but not trypsinogen in vitro. During pancreatitis in pancreas-specific CTSD(f/f/)p48(Cre/+) animals, markers of severity were reduced only at 1 h, whereas in the complete KO, this effect also included the late disease phase (8 h), indicating an important effect of extra-acinar CTSD on course of the disease. CTSD-/- leukocytes exhibited reduced cytokine release after lipopolysaccharide (LPS) stimulation, and CTSD KO also reduced caspase-3 activation and apoptosis in acinar cells stimulated with the intestinal hormone cholecystokinin. In summary, CTSD is expressed in pancreatic acinar and inflammatory cells, undergoes subcellular redistribution and activation during experimental pancreatitis, and regulates disease severity by potently activating CTSB. Its impact is only minimal and transient in the early, acinar cell-dependent phase of pancreatitis and much greater in the later, inflammatory cell-dependent phase of the disease.