Novel Toxins and Receptors in Mucormycosis Pathogenesis and Treatment

项目摘要/摘要 毛霉病是由毛霉菌引起的一种危及生命的感染，发生在患者的免疫球蛋白中。 可能由糖尿病酮症酸中毒、中性粒细胞减少、皮质类固醇使用和/或血清铁升高所致。根霉菌 物种是毛霉病最常见的原因。因为毛霉病风险的上升 因素方面，感染的发生率有所上升。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%，而在播散性疾病患者中接近100%。 显然，需要新的策略来预防和治疗毛霉病。 毛霉菌病通常是通过吸入孢子而开始的，其临床特征是几乎一致的压力。 广泛的血管侵袭导致血管血栓形成和组织坏死。这些功能突出了 真菌侵入肺泡上皮细胞(AECs)以启动感染的重要性。 他们还强调了在进展和扩散过程中穿透内皮的重要性。 这种疾病的危害。最后，大面积的组织坏死表明存在真菌毒素。 在上一个资金周期中，我们确定毛霉菌在Coth侵袭素结合到 血管内皮细胞上的整合素。这种结合触发了AEC表皮生长因子受体(EGFR)的激活。 Duce入侵萌发的孢子，机制不明。我们还发现萌发了 孢子通过周细胞和细胞外基质传播，通过COTH相互作用侵入内皮细胞。 ING使用葡萄糖调节蛋白78。我们还发现毛霉菌破坏宿主细胞 通过产生一种名为毛霉素的毒素，因其与植物毒素蓖麻毒素相似而得名。两个都是 侵袭素和毛霉素是致病所必需的，针对这两种蛋白的抗体都具有保护作用。 老鼠。具体地说，我们的初步数据显示，coth inasins与随后的 毛霉素的产生导致血管内皮细胞解体(可能通过激活ADP-核糖化因子6 (ARF6)、血管过度渗漏、组织水肿和器官衰竭；所有这些都是毛霉菌病的特征。 并与抗真菌治疗失败有关。因此，我们建议以这些令人兴奋的数据为基础，阻止- 探讨毛霉菌诱导血管内皮细胞解体和血管渗漏、破裂的分子机制。 改善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 针对Arf6、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 老鼠体内的通路。 我们使用一种基于机制的方法来检查毛霉菌病的两个特征：血管侵袭和组织 坏死。这些研究将导致针对毛霉素、宿主受体和宿主细胞的新疗法。 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.