Oral Epithelial Cells, Candida and PMN Activation

描述（由申请人提供）：口疮（假膜性念珠菌病）继续困扰着免疫功能低下的个体，特别是儿童，这一比例高得令人无法接受。由于这种主要由白色念珠菌引发的口腔感染的顽固性可能归因于其生物膜形成活动，因此了解粘膜生物膜形成和伴随的宿主反应的不同阶段对于理解这种感染的发病机制和设计有效的抗感染策略至关重要。下一个竞争周期中提出的研究目标是为了更好地了解宿主对口腔中念珠菌形成的粘膜生物膜的反应，以及促炎细胞因子和中性粒细胞在预防或消除这种生物膜中的作用。在目前的资助周期中，我们建立了一个三维口腔组织模型，该模型忠实地再现了假膜性念珠菌病病变的组织学和细胞特征，并纳入了中性粒细胞，以便我们可以原位检测它们的念珠菌活性。在研究这种组织类似物时，我们发现念珠菌不作为单细胞生物与口腔粘膜组织相互作用，而是形成复杂的粘膜生物膜。我们能够在口腔食管念珠菌病的小鼠模型中重现并验证粘膜组织生物膜的存在。该应用程序将建立在当前资助周期中产生的数据基础上，以实现以下目标：a)描述口腔粘膜生物膜的发育阶段、细胞组成和空间排列，并验证念珠菌组织生物膜影响粘膜促炎细胞因子对感染的反应的假设；b)验证中性粒细胞抗念珠菌反应在生物膜环境中受到抑制的假设，并研究这种抑制的机制；c)研究特定念珠菌基因产物在促进口腔黏膜生物膜形成、组织侵袭和损伤中的作用。由于以层状上皮表面形成念珠菌生物膜为特征的浅表真菌病会影响其他胃肠道粘膜部位，如食管粘膜，这些部位可能更容易受到侵袭，因此我们的研究可能对预防播散性感染具有深远的意义。我们设想我们的研究将导致新的口服抗真菌药物的开发，这些药物针对白色念珠菌调节粘膜生物膜的途径，并促进局部中性粒细胞抗真菌功能。公共卫生意义：口腔假膜性念珠菌病仍然是免疫系统较弱或不成熟的患者（如HIV+儿童、新生儿和恶性肿瘤患者）中最常见的念珠菌感染形式。我们认为，在这种感染中，生物膜为念珠菌提供了先天防御机制的保护环境，这可能促进其持久性。我们设想，我们对组织生物膜的研究将导致新的口服抗真菌药物的开发，这些药物针对白色念珠菌调节生物膜的途径，并促进中性粒细胞抗真菌功能。

DESCRIPTION (provided by applicant): Oral thrush (pseudomembranous candidiasis) continues to afflict an unacceptably high percentage of immunocompromised individuals, particularly children. Since the recalcitrant nature of this oral infection, triggered primarily by C. albicans, could be attributed to its biofilm forming activities, knowledge of the distinct stages in mucosal biofilm formation and concomitant host responses is of paramount importance in understanding the pathogenesis of this infection and designing effective anti-infective strategies. The goals of the proposed studies in the next competitive cycle are directed toward a better understanding of the host response to mucosal biofilms formed by Candida in the oral cavity and the role of proinflammatory cytokines and neutrophils in the prevention or elimination of such biofilms. In the current funding cycle we established a three-dimensional oral tissue model which faithfully reproduces the histologic and cellular characteristics of pseudomembranous candidiasis lesions and incorporated neutrophils so that we can examine their candidacidal activities in situ. While working with this tissue analogue we discovered that Candida does not interact with oral mucosal tissues as single cell organisms, but forms a complex mucosal biofilm. We were able to reproduce and validate the presence of a mucosal tissue biofilm in a mouse model of oroesophageal candidiasis. This application will build on data generated during the current funding cycle to address the following Aims: a) characterize the stages in development, cellular composition and spatial arrangement of biofilms in the oral mucosa and test the hypothesis that Candida tissue biofilms affect the mucosal proinflammatory cytokine response to infection; b) test the hypothesis that neutrophil anti-Candida responses are inhibited within the biofilm environment and examine the mechanisms of this inhibition; and c) investigate the role of specific Candida gene products in facilitating oral mucosal biofilm formation, tissue invasion and damage. Since superficial mycoses characterized by Candida biofilm formation on the surface of stratified epithelia affect other GI tract mucosal sites, such as the esophageal mucosa, which may be more vulnerable to invasion our studies may have far reaching implications in preventing disseminated infection. We envision that our studies will lead to the development of new oral anti-mycotic agents which target pathways of mucosal biofilm regulation by C. albicans and promote local neutrophil antifungal functions. Public Health Significance: Oral pseudomembranous candidiasis is still the most prevalent form of Candida infection in patients with weakened or immature immune systems, such as HIV+ children, neonates and patients with malignancies. We propose that in this infection biofilms provide a protective environment for Candida from innate defense mechanisms, which may promote its persistence. We envision that our studies in tissue biofilms will lead to the development of new oral anti-mycotic agents which target pathways of biofilm regulation by C. albicans and promote neutrophil antifungal functions.