Candida Albicans Gastrointestinal Colonization and Dissemination

白色念珠菌（CA）定植是侵袭性疾病所必需的。成年小鼠对CA有抵抗力 胃肠道（GI）定植。我们已经鉴定出两种遗传上不同的厌氧微生物 可以单独维持无菌小鼠中CA定殖抗性。这些厌氧微生物 诱导宿主免疫效应物（转录因子HIF 1-α和抗菌肽CRAMP/LL-37）， 显著降低CA GI定殖。通过反复诱导HIF 1-α和CRAMP， 能够显著减少CA定植，并将CA传播的死亡率降低50%。有趣的是， 能够将CA排出肠道的厌氧细菌具有产生短链脂肪酸的能力 （SCFAs）。SCFAS已被证明具有许多免疫调节特性。因此，我的中央 假设是由肠道厌氧细菌产生的SCFAs是维持CA所必需的 殖民抵抗这项工作将涉及两个具体目标。首先，我将确定SCFA是否 CA定植抗性所必需的。我将评估是否有嗜酸性厌氧菌类杆菌 不能产生SCFAs或单独产生SCFAs的多核突变体可减少CA定殖。我预测 SCFA是维持CA定殖抗性所必需的。其次，我将确定HIF-1 α和/或 CRAMP是SCFA诱导的GI定植减少所必需的。我将评估SCFA是否可以 促进培养的人和小鼠肠上皮细胞中的CA清除和Hif1a中CA定殖减少 和Cramp敲除小鼠。我预测HIF 1-α和CRAMP是维持CA定殖所必需的 阻力鉴于侵袭性真菌感染的高发病率和死亡率， 抗真菌抗生素的使用，以及抗生素耐药菌株的不断出现， 迫切需要治疗和预防患者的侵袭性真菌感染。利用自然发生的 厌氧细菌代谢物（SCFA），以增强GI粘膜免疫效应，减少真菌定植 并最终减少传播可能代表我们预防/治疗真菌感染的方式的范式转变， 患者感染。这些研究将为以下创新奠定基础：1）一部小说 SCFA激活肠道免疫防御以维持CA定植抗性的机制; 2）一种新的 方法（SCFAs）抑制CA传播;和3）预防真菌感染的新方法， 患者总之，这些研究应该导致对细菌/真菌相互作用的基本见解， 肠道，并将提供新的前景，在打击侵入性真菌疾病在人类宿主。

Candida albicans (CA) colonization is required for invasive disease. Adult mice are resistant to CA gastrointestinal (GI) colonization. We have identified two genetically distinct anaerobic commensal bacteria that can individually maintain CA colonization resistance in germ-free mice. These anaerobic commensals induce host immune effectors (transcription factor, HIF1-α, and antimicrobial peptide, CRAMP/LL-37) that significantly decrease CA GI colonization. By pharmacologically inducing both HIF1-α and CRAMP, we were able to significantly reduce CA colonization and reduce mortality from CA dissemination by 50%. Interestingly, the anaerobic bacteria that can expel CA from the gut share the ability to produce short-chain fatty acids (SCFAs). SCFAS have been shown to have numerous immunomodulatory properties. Therefore, my central hypothesis is that SCFAs produced by gut commensal anaerobic bacteria are necessary to maintain CA colonization resistance. This work will involve two specific aims. First, I will determine whether SCFAs are necessary for CA colonization resistance. I will evaluate whether commensal anaerobe Bacteroides thetaiotamicron mutants unable to produce SCFAs or SCFAs alone can reduce CA colonization. I predict that SCFAs are necessary for maintaining CA colonization resistance. Second, I will determine if HIF-1α and/or CRAMP are necessary for SCFA-induced GI colonization reduction. I will evaluate whether SCFAs can promote CA clearance in cultured human and mouse gut epithelial cells and CA colonization reduction in Hif1a and Cramp knockout mice. I predict that HIF1-α and CRAMP are necessary for maintaining CA colonization resistance. Given the high morbidity and mortality associated with invasive fungal infections, the limited arsenal of antifungal antibiotics, and the continuing emergence of antibiotic resistant strains, new approaches to treating and preventing invasive fungal infections in patients are desperately needed. Using natural occurring anaerobic bacterial metabolites (SCFAs) to boost GI mucosal immune effectors to reduce fungal colonization and ultimately decrease dissemination could represent paradigm shift in the way we prevent/treat fungal infections in patients. These studies will lay the groundwork for the following innovations: 1) a novel mechanism by which SCFAs activate gut immune defenses to maintain CA colonization resistance; 2) a novel approach (SCFAs) to inhibit CA dissemination; and 3) a novel approach to preventing fungal infections in patients. Together, these studies should lead to fundamental insights into bacterial/fungal interactions within the intestinal tract and will provide new perspectives in combating invasive fungal disease in the human host.