Novel Toxins and Receptors in Mucormycosis Pathogenesis and Treatment

项目总结/摘要 毛霉菌病，由毛霉目真菌引起，是一种危及生命的感染，发生在免疫缺陷的患者中。 糖尿病酮症酸中毒、中性粒细胞减少症、皮质类固醇使用和/或血清铁增加。根霉 种是毛霉菌病的最常见的原因。由于毛霉菌病患病率的上升 由于这些因素，感染的发生率上升了。尽管进行了毁容手术和积极的抗真菌治疗， 毛霉菌病的死亡率保持在> 40%，并且在具有播散性疾病的患者中接近100%。 显然，需要新的策略来预防和治疗毛霉菌病。 毛霉菌病通常通过吸入孢子引起，临床特征是几乎均匀的压力， 广泛的血管侵犯，导致血管血栓形成和组织坏死。这些特点突出了 真菌侵入肺泡上皮细胞（AEC）以启动感染的能力的重要性。 他们还强调了在进展和传播过程中穿透内皮的重要性 疾病。最后，广泛的组织坏死表明存在真菌毒素。 在上一个资助周期中，我们确定当CotH侵袭素结合到Mucorales时，Mucorales启动感染。 整合素对AEC的影响。这种结合触发AEC表皮生长因子受体（EGFR）的激活， 以未知的机制引起萌发孢子的入侵。我们还发现发芽了 孢子通过CotH相互作用通过周细胞和细胞外基质传播侵入内皮细胞， 葡萄糖调节蛋白78我们还发现毛霉菌会破坏宿主细胞 通过产生一种叫做毛霉素的毒素，之所以这样命名是因为它与植物毒素蓖麻毒素相似。两个CotH 侵袭素和毛霉素是致病所必需的，靶向任一蛋白质的抗体在 小鼠具体地说，我们的初步数据表明，结合CotH侵袭素和随后的 毛霉素的产生引起AEC的崩解（可能通过激活ADP-核糖基化因子6 （Arf 6））、过度血管渗漏、组织水肿和器官衰竭;所有这些都是毛霉菌病的标志 并且与抗真菌治疗失败有关。因此，我们建议建立在这些令人兴奋的数据和威慑- 挖掘毛霉菌诱导AEC崩解和血管渗漏的分子机制， 精细的毛霉素诱导的宿主细胞进入和死亡的细胞内事件。我们还将评估 靶向Arf 6、宿主受体、毛霉素和毛霉素诱导的宿主细胞死亡的新治疗策略 在老鼠的路径。 我们使用一种机制为基础的方法来研究毛霉菌病的两个标志：血管侵入和组织 坏死这些研究将导致新的疗法，靶向毛霉素，宿主受体和宿主细胞- 激活途径。其中一些疗法是FDA批准的药物，有可能迅速影响治疗- 这种致命的感染。

PROJECT SUMMARY/ABSTRACT Mucormycosis, caused by Mucorales fungi, is a life-threatening infection that occurs in patients immunocom- promised by diabetic ketoacidosis, neutropenia, corticosteroid use, and/or increased serum iron. Rhizopus species are the most common cause of mucormycosis. Because of the rising prevalence of mucormycosis risk factors, the incidence of the infection has risen. Despite disfiguring surgery and aggressive antifungal therapy, the mortality of mucormycosis remains >40%, and approaches 100% in patients with disseminated disease. Clearly new strategies to prevent and treat mucormycosis are needed. Commonly initiated via inhalation of spores, clinical hallmarks of mucormycosis is the virtually uniform pres- ence of extensive angioinvasion with resultant vessel thrombosis and tissue necrosis. These features highlight the importance of the ability of the fungus to invade alveolar epithelial cells (AECs) to initiate the infection. They also emphasize the significance of penetrating the endothelium during the progression and dissemination of the disease. Finally, the extensive tissue necrosis points to the presence of fungal toxins. During the last funding cycle, we determined that Mucorales initiate infection when the CotH invasins bind to integrins on AECs. This binding triggers the activation of AEC epidermal growth factor receptor (EGFR) to in- duce invasion of germinated spores with an unidentified mechanism. We also discovered that germinated spores disseminate through the pericytes and extracellular matrix to invade endothelial cells via CotH interact- ing with Glucose Regulated Protein 78. We also made the seminal discovery that Mucorales damage host cells by producing a toxin called mucoricin, so named because of its similarities to the plant toxin, ricin. Both CotH invasins and mucoricin are required for pathogenesis and antibodies targeting either protein are protective in mice. Specifically, our preliminary data show that the combination of binding of CotH invasins and subsequent production of mucoricin cause disintegration of AECs (potentially by activating the ADP-ribosylation factor 6 (Arf6)), excessive vascular leak, tissue edema, and organ failure; all of which are hallmarks of mucormycosis and are associated with antifungal therapy failure. Thus, we propose to build on these exciting data and deter- mine the molecular mechanisms by which Mucorales induce disintegration of AECs and vascular leak and de- fine the intracellular events of mucoricin-induced host cell entry and death. We will also evaluate the efficacy of novel therapeutic strategies targeting Arf6, host receptors, mucoricin and mucoricin-induced host cell death pathways in mice. We use a mechanism-based approach to examine two hallmarks of mucormycosis: angioinvasion and tissue necrosis. These studies will lead to novel therapies that target mucoricin, host receptors and host cell- activation pathways. Some of these therapies are FDA-approved drugs with potential to rapidly impact treat- ment of this lethal infection.