Candida-endothelial interactions under conditions of flow

描述(申请人提供)：问题：系统性念珠菌病是一种严重的感染，死亡率很高。死亡的原因是循环真菌细胞进入组织并造成广泛的器官损害。这一过程的第一步是黏附于血管的内皮衬里，然后跨越内皮屏障进入组织。然而，我们对这两个步骤中涉及的机制知之甚少，关于酵母和菌丝形态的白色念珠菌在黏附和迁移过程中所扮演的角色，也有相互矛盾的证据。背景：到目前为止，大多数探索念珠菌与内皮细胞黏附的体外研究都是在静态条件下进行的，尽管很明显，在体内血管中发生的流动条件下，黏附过程是非常不同的。研究形态发生变化在这些过程中的重要性一直是困难的，因为这些研究中使用的大多数白色念珠菌突变株都锁定在一种或另一种形态上，并且毒力降低，而野生型白色念珠菌的形态发生转化是不可预测的，很难控制。 在初步研究中，我们开发了一种白色念珠菌的工程菌株SSY50-B，在这种菌株中，我们可以调节从酵母到菌丝体的形态发生转换，同时保持生物的毒力。另外，我们已经开发了一些分析方法，使我们能够研究细胞，特别是白细胞和肿瘤细胞，在类似于血管中的流动条件下，与内皮细胞表面的粘连，并跟踪它们随后的跨内皮迁移。我们的目标是将这些技术结合在一起，这样我们就可以研究系统性念珠菌病中白色念珠菌如何从循环进入组织的许多悬而未决的问题。更具体地说，我们的目标是： 具体目标1：建立一种体外模型，使我们能够研究和比较酵母和菌丝形态的白色念珠菌在血流条件下与血管内皮细胞的黏附特性。 具体目的2：建立流动条件下白念珠菌跨内皮细胞迁移的体外模型，以探讨酵母形态、菌丝形态和形态发生转化在迁移过程中的作用。 公众利益：系统性念珠菌病是一种严重威胁生命的疾病，循环中的真菌细胞附着并跨越血管内皮细胞层进入组织，在那里它们会导致广泛的器官损害。通过了解念珠菌-内皮细胞黏附和移行的机制，我们可能能够抑制念珠菌在组织中的迁移，防止由此造成的组织损伤，并增加循环生物对抗真菌药物和网状内皮系统的暴露，从而使它们能够被破坏。

DESCRIPTION (provided by applicant): Problem: Systemic candidiasis is a serious infection with high mortality. Death results from circulating fungal cells entering the tissues and causing extensive organ damage. The first step in this process is adhesion to the endothelial lining of blood vessels followed by transmigration across the endothelial barrier into the tissues. However, we know little about the mechanisms involved in either of these steps and there is conflicting evidence about the role played by yeast and hyphal forms of Candida albicans in both the adhesion and transmigration process. Background: To date, most in vitro studies exploring candidal adhesion to endothelium have been performed under static conditions although it is clear that adhesion processes are very different under the conditions of flow that occur in blood vessels in vivo. Studying the importance of morphogenetic change in these processes has been difficult, because most mutant strains of C. albicans used in these studies are locked into one or other morphological form and have reduced virulence, while morphogenetic conversion of wild type C. albicans is unpredictable and difficult to control. In preliminary studies, we have developed an engineered stain of C. albicans, SSY50-B, in which we can regulate morphogenetic conversion from yeast to hyphal form whilst maintaining the organism's virulence. Separately we have developed assays that allow us to study the adhesion of cells, particularly leukocytes and tumor cells, to endothelial surfaces under conditions of flow similar to those in blood vessels and to follow their subsequent trans-endothelial migration. Our objective is to bring these technologies together so that we can investigate many of the unanswered questions about how C. albicans moves from the circulation into the tissues in systemic candidiasis. More specifically our aims are: Specific aim 1: To develop an in vitro model that will allow us to study and compare the adhesion characteristics of yeast and hyphal forms of Candida albicans to vascular endothelium under conditions of flow. Specific aim 2: To develop an in vitro model to study the trans-endothelial cell migration of C. albicans under conditions of flow, in order to investigate the role of yeast forms, hyphal forms and morphogenetic conversion in the transmigration process. Public benefit: Systemic Candidiasis is a serious life threatening condition in which circulating fungal cells adhere to and migrate across the endothelial lining of blood vessels to enter the tissues where they cause extensive organ damage. By understand the mechanisms involved in Candida-endothelial adhesion and transmigration, we may be able to inhibit Candida migration into the tissues, prevent the resulting tissue damage and increase the exposure of circulating organisms to anti-fungal agents and the reticuloendothelial system so that they can be destroyed.