Coxsackieviral pancreatitis: autophagy, proteolysis, and inflammation

描述（由申请方提供）：柯萨奇病毒B3（CVB3）是小核糖核酸病毒家族中的一种肠道病毒，是胰腺炎的常见感染性病因，胰腺炎是一种常见、严重且昂贵的疾病。已知某些形式的胰腺炎涉及自噬途径;例如，阻断该途径后期步骤的毒素可引发该疾病，这可能是因为阻断导致细胞内胰蛋白酶原的活化。巧合的是，自噬的完全失活可以防止这些类型的胰腺炎。因此，至少那些形式的胰腺炎需要该途径在晚期（i）活跃和（ii）阻断。自噬在许多病毒和细菌感染期间上调，并且通常与之对抗。可以预见的是，进化已经导致几种病毒发展出逃避该途径抑制作用的机制，研究表明，包括CVB 3在内的一些病毒已经更进一步，积极利用自噬来增强其复制。我的实验室已经表明，在体内腺泡细胞中，CVB 3中断了自噬途径的晚期阶段。因此，我们假设CVB3对自噬途径的影响与病毒引起胰腺炎的能力之间可能存在联系。我们希望在体内测试这个想法，（即，在活的动物中，不仅在组织培养细胞中）。为了实现这一目标，我们最近开发了条件性KO小鼠（Atg5f/f/Cre+小鼠），其中自噬途径中的关键蛋白Atg5仅在胰腺腺泡细胞中缺失。使用这些小鼠，我们已经表明，CVB3受益于完整的自噬途径，没有它，CVB3在胰腺中的复制被严重削减。此外，病毒诱导的胰腺炎在Atg5f/f/Cre+小鼠中显著减少。因此，像其他类型的胰腺炎一样，CVB胰腺炎需要自噬活跃（如野生型小鼠），但功能失调（因为病毒阻断了途径）。此外，我们未发表的数据表明，CVB3感染诱导腺泡细胞内的自噬依赖性胰蛋白酶活性。这些和其他数据使我提出，所有胰腺炎，无论是病毒性的还是非病毒性的，都有一个共同的原因;我认为它们是由自噬途径的晚期阻断引起的，自噬途径导致细胞内胰蛋白酶原的裂解，释放细胞内的胰蛋白酶活性。这些问题将在目标1和2中加以研究。我进一步假设，胰蛋白酶引发的损害可以加剧T1干扰素信号进入腺泡细胞，这将在目标3。如果这些概念得到验证，自噬和T1IFN将成为所有形式的这种目前无法治愈的疾病的关键治疗靶点。有三个具体目标。目标1.为了更好地定义体内腺泡细胞中CVB3、自噬和胰蛋白酶原之间的相互作用。目标二。评估T1IFN信号直接进入腺泡细胞如何影响病毒性胰腺炎。目标3。评价T1IFN在病毒感染胰腺募集免疫细胞中的作用。

DESCRIPTION (provided by applicant): Coxsackievirus B3 (CVB3), an enterovirus in the picornavirus family, is a frequent infectious cause of pancreatitis, a common, serious, and costly disease. Some forms of pancreatitis are known to involve the autophagy pathway; e.g., toxins that block late steps in the pathway can trigger the disease, perhaps because the blockade causes activation of intracellular trypsinogen. Paradoxically, complete inactivation of autophagy protects against those types of pancreatitis. Therefore, at least those forms of pancreatitis require that the pathway be both (i) active and (ii) blocked at a late stage. Autophagy is upregulated during, and often combats, many viral and bacterial infections. Predictably, evolution has led to several viruses developing mechanisms by which to evade the inhibitory effects of the pathway, and studies have suggested that some viruses - including CVB3 - have gone one step further, actively exploiting autophagy to enhance their replication. My lab has shown that, in acinar cells in vivo, CVB3 interrupts a late stage of the autophagy pathway. We therefore hypothesized that there might be a link between this effect of CVB3 on the autophagy pathway, and the virus' ability to cause pancreatitis. We wished to test this idea in vivo, (i.e., n the living animal, not only in tissue culture cells). To achieve this goal, we have recently developed conditional KO mice (Atg5f/f/Cre+ mice) in which a key protein in the autophagy pathway, Atg5, has been deleted only in pancreatic acinar cells. Using these mice, we have shown that CVB3 benefits from an intact autophagy pathway without which CVB3 replication in the pancreas is severely curtailed. Furthermore, virus-induced pancreatitis is dramatically reduced in the Atg5f/f/Cre+ mice. Thus, like some other types of pancreatitis, CVB pancreatitis requires that autophagy be active (as it is in wt mice), but dysfunctional (because the virus blocks the pathway). Furthermore, our unpublished data show that CVB3 infection induces autophagy-dependent trypsin activity inside acinar cells. These and other data lead me to propose that there is a common cause for all pancreatitides, viral and non- viral; I propose that they result from a late blockade of the autophagy pathway, which leads to cleavage of intracellular trypsinogen, unleashing trypsin activity inside the cell. These issues will be investigated in Aims 1 & 2. I further hypothesize that the trypsin-initiated damage can be exacerbated by T1IFN signaling into acinar cells; this will be investigated in Aim 3. If these concepts are validated, autophagy and T1IFNs would become key therapeutic targets for all forms of this currently-untreatable disease. There are three Specific Aims. Aim 1. To better define interactions among CVB3, autophagy, and trypsinogen in acinar cells in vivo. Aim 2. To evaluate how T1IFN signaling directly into acinar cells affects viral pancreatitis. Aim 3. To evaluate the role of T1IFNs in recruiting immune cells to the virus-infected pancreas.