Regulation of neutrophil death by GSDMD in Candida albicans infection

项目摘要 白色念珠菌是免疫功能低下患者血液感染的主要原因。 中性粒细胞在白色念珠菌的宿主防御中起着关键作用，而中性粒细胞减少是发展的主要风险因素。 严重播散性念珠菌病。在目前的研究中，我们建议减轻与中性粒细胞减少相关的播散 通过抑制白色念珠菌诱导的中性粒细胞死亡从而增强中性粒细胞而感染白念珠菌 中性粒细胞减少患者的介导性真菌杀灭。我们将通过瞄准Gasdermin D(GSDMD)来实现这一目标 与中性粒细胞死亡的调节有关。GSDMD最初被认为是一个关键因素 导致巨噬细胞裂解性嗜酸性死亡(嗜热症)的炎症形式。我们最近 报道称，GSDMD也在中性粒细胞中高表达，并介导中性粒细胞死亡 在中性粒细胞动态平衡和炎症消退中的重要作用。我们的初步数据显示，C. 白念珠菌可以劫持GSDMD介导的中性粒细胞死亡机制来消除中性粒细胞，因此 再次抑制中性粒细胞介导的宿主防御白念珠菌感染。GSDMD缺乏症被彻底抑制 白色念珠菌诱导中性粒细胞死亡，并对播散性白色念珠菌感染产生抵抗力。一起， 这些结果提出了GSDMD在调节中性粒细胞死亡中的新的病理生理学作用，引导我们 假设抑制GSDMD将导致中性粒细胞介导的宿主防御增强，并且应该 治疗中性粒细胞减少相关的白色念珠菌感染的合法治疗策略。为了进一步 了解GSDMD在调节白色念珠菌诱导的中性粒细胞死亡和宿主杀菌活性中的作用 将首先揭示白色念珠菌激活中性粒细胞GSDMD的机制。的贡献 溶酶体膜通透性(LMP)、吞噬作用、ROS、念珠菌菌丝形成和 将在人和鼠中性粒细胞中检测念珠菌素对GSDMD的裂解作用(目标1)。接下来，我们 将阐明GSDMD在调节白念珠菌感染期间体内中性粒细胞死亡中的作用 正常和中性粒细胞减少的小鼠(目标2)。我们还将直接评估中性粒细胞GSDMD对 新研制的中性粒细胞特异性条件性GSDMD-KO小鼠对白色念珠菌的宿主防御作用 (目标3)。最后，我们将研究宿主对白色念珠菌的防御是否可以通过 药理靶向GSDMD(目标4)。加在一起，在这四个具体目标中提出的实验将 更好地了解GSDMD介导的中性粒细胞死亡的作用和调控 播散性白色念珠菌感染。这项研究将巩固GSDMD及其相关通路作为新的治疗方法 中性粒细胞减少相关的严重念珠菌病的治疗目标。

Project Summary Candida albicans (C. albicans) is a leading cause of bloodstream infection in immunocompromised patients. Neutrophils play a key role in C. albicans host defense and neutropenia is a major risk factor for developing severe disseminated candidiasis. In current study, we propose to alleviate neutropenia-related disseminated C. albicans infection by inhibiting C. albicans-induced neutrophil death and thus enhancing neutrophil- mediated fungal killing in neutropenic patients. We will do so by targeting Gasdermin D (GSDMD) which has been implicated in the regulation of neutrophil death. GSDMD was originally identified as a key factor responsible for the inflammatory form of lytic pyroptotic death (pyroptosis) in macrophages. We recently reported that GSDMD is also highly expressed in neutrophils and mediates neutrophil death which plays essential roles in neutrophil homeostasis and resolution of inflammation. Our preliminary data show that C. albicans can hijack GSDMD-mediated neutrophil death mechanism to eliminate neutrophils and therefore suppress neutrophil-mediated host defense again C. albicans infection. GSDMD deficiency drastically inhibited C. albicans-induced neutrophil death and conferred resistance to disseminated C. albicans infection. Together, these results present a novel pathophysiological role for GSDMD in regulation of neutrophil death, leading us to hypothesize that inhibition of GSDMD will lead to elevated neutrophil-mediated host defense and should be a legitimate therapeutic strategy for the treatment of neutropenia-related C. albicans infection. To further understand the role GSDMD in regulating C. albicans-induced neutrophil death and host fungicidal activity, we will first reveal the mechanism by which C. albicans activates GSDMD in neutrophils. The contribution of lysosomal membrane permeabilization (LMP), phagocytosis, ROS, candida hyphae formation, and candidalysin to GSDMD cleavage will be examined in both human and mouse neutrophils (Aim 1). Next, we will elucidate the role of GSDMD in regulating neutrophil death in vivo during C. albicans infection in both normal and neutropenic mice (Aim 2). We will also directly assess the contribution of neutrophil GSDMD to host defense against C. albicans using a newly developed neutrophil-specific conditional GSDMD KO mouse (Aim 3). Finally, we will examine whether the host defense against C. albicans can be enhanced by pharmacologically targeting GSDMD (Aim 4). Together, experiments proposed in these four specific aims will provide a better understanding of the role and regulation of GSDMD-mediated neutrophil death in disseminated C. albicans infection. This study will solidify GSDMD and related pathways as novel therapeutic targets for treatment of neutropenia-related severe candidiasis.