Regulation of neutrophil death by GSDMD in Candida albicans infection

项目概要 白色念珠菌（C. albicans）是免疫功能低下患者血流感染的主要原因。 中性粒细胞在白色念珠菌宿主防御中发挥关键作用，中性粒细胞减少是发展的主要危险因素 严重的播散性念珠菌病。在当前的研究中，我们建议缓解中性粒细胞减少症相关的播散性 通过抑制白色念珠菌感染引起的中性粒细胞死亡，从而增强中性粒细胞 介导中性粒细胞减少患者的真菌杀灭。我们将通过针对 Gasdermin D (GSDMD) 来实现这一目标，该药物已 参与中性粒细胞死亡的调节。 GSDMD 最初被确定为关键因素 负责巨噬细胞中溶解性焦亡的炎症形式（焦亡）。我们最近 据报道，GSDMD 在中性粒细胞中也高表达，并介导中性粒细胞死亡，从而发挥作用 在中性粒细胞稳态和炎症消退中发挥重要作用。我们的初步数据表明，C. 白色念珠菌可以劫持 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色念珠菌感染。 GSDMD 缺乏症受到显着抑制 白色念珠菌诱导中性粒细胞死亡并赋予对播散性白色念珠菌感染的抵抗力。在一起， 这些结果展示了 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升高，并且应该 治疗中性粒细胞减少症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，我们 首先揭示白色念珠菌激活中性粒细胞中GSDMD的机制。的贡献 溶酶体膜透化 (LMP)、吞噬作用、ROS、念珠菌菌丝形成，以及 将在人和小鼠中性粒细胞中检查念珠菌溶酶与 GSDMD 的裂解（目标 1）。接下来，我们 将阐明 GSDMD 在白色念珠菌感染期间体内调节中性粒细胞死亡的作用 正常小鼠和中性粒细胞减少小鼠（目标 2）。我们还将直接评估中性粒细胞 GSDMD 对 使用新开发的中性粒细胞特异性条件 GSDMD KO 小鼠对抗白色念珠菌的宿主防御 （目标 3）。最后，我们将研究是否可以通过以下方式增强宿主对白色念珠菌的防御： 药理学靶向 GSDMD（目标 4）。总之，这四个具体目标提出的实验将 更好地了解 GSDMD 介导的中性粒细胞死亡的作用和调节 播散性白色念珠菌感染。这项研究将巩固 GSDMD 和相关途径作为新型治疗方法 治疗中性粒细胞减少症相关的严重念珠菌病的目标。

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.