Role of non-myeloid cells' pyroptosis in melioidosis

在炎性小体的背景下，caspase-1和caspase-11的激活导致IL-1β和IL-18的加工和分泌，并引发溶解性细胞死亡，称为焦亡。炎性小体的激活和焦亡已被证明可以保护宿主免受一系列病原体的感染，包括假伯克霍尔德菌，一种革兰氏阴性细菌，被用作类melidosis的小鼠模型。然而，越来越清楚的是，炎症小体的激活和焦亡可以通过触发致死性类二十烷风暴、介导致死性内毒素休克和引起弥散性血管内凝血（DIC）对宿主有害。我们最近的研究表明，上皮细胞和内皮细胞表达的唯一功能性炎性体是caspase-11，并且在类鼻疽模型中，caspase-11依赖性肺上皮细胞焦亡具有保护作用。根据我们的初步结果和已发表的文献，我们假设上皮细胞中caspase-11的激活将通过诱导焦亡和优先产生抗炎类二十烷如前列腺素E2来保护宿主免受肺炎类melidosis。相反，内皮细胞中的caspase-11激活可能是有害的，因为它可能破坏屏障完整性，通过释放组织因子和LTB4诱导DIC和过度炎症。因此，选择性地研究caspase-11在上皮细胞或内皮细胞中的功能将使我们能够识别有害和有益的反应，从而潜在地指出抑制前者和促进后者的治疗途径。在目标1中，我们将重点关注caspase-11在上皮细胞中的作用。我们将测试caspase-11和gasdermin D在肺上皮细胞产生二十烷类蛋白中的作用。我们还将测试肺上皮细胞中缺乏caspase-11表达的小鼠对类鼻疽的易感性，并确定上皮来源的类二十烷在类鼻疽中的作用。在目标2中，我们将研究caspase-11在内皮细胞中的作用。我们将研究caspase-11如何控制内皮细胞中类二十烷酸的产生和组织因子的释放。我们将检测内皮细胞缺乏caspase-11表达的小鼠对类鼻疽病的易感性，并确定组织因子、血小板活化因子和DIC在类鼻疽病发病中的作用。

Activation of caspase-1 and caspase-11 in the context of inflammasomes leads to processing and secretion of IL-1β and IL-18 and triggers a lytic cell death termed pyroptosis. Inflammasome activation and pyroptosis have been shown to protect the host from infection with a range of pathogens including Burkholderia pseudomallei, a gram-negative bacterium used as a mouse model of melioidosis. However, it is also becoming clear that inflammasome activation and pyroptosis can be deleterious to the host by triggering lethal eicosanoid storm, mediating lethal endotoxic shock, and causing disseminated intravascular coagulation (DIC). We have recently shown that the only functional inflammasome expressed by epithelial and endothelial cells is caspase-11, and that in a model of melioidosis caspase-11-dependent pyroptosis of lung epithelial cells is protective. Based on our preliminary results and the published literature we hypothesize that activation of caspase-11 in epithelial cells will protect the host from pneumonic melioidosis through induction of pyroptosis and preferential production of anti-inflammatory eicosanoids like prostaglandin E2. In contrast, caspase-11 activation in endothelial cells may prove deleterious because it may damage barrier integrity, induce DIC and excessive inflammation through release of Tissue Factor and LTB4. Thus, studying the function of caspase-11 selectively in epithelial or endothelial cells will allow us to identify the deleterious and the beneficial responses and therefore potentially indicate therapeutic avenues to inhibit the former and encourage the latter. In aim 1 we will focus on the role of caspase-11 in epithelial cells. We will test the role of caspase-11 and gasdermin D in the production of eicosanoids by lung epithelial cells. We will also test the susceptibility to melioidosis of mice that lack expression of caspase-11 in lung epithelial cells and determine the role of epithelial-derived eicosanoids in melioidosis. In aim 2 we will study the role of caspase-11 in endothelial cells. We will examine how caspase-11 controls production of eicosanoids and release of Tissue Factor in endothelial cells. We will test the susceptibility to melioidosis of mice that lack expression of caspase-11 in endothelial cells and establish the role of Tissue Factor, Platelet Activating Factor, and DIC in the pathogenesis of melioidosis.