Prevention of C. Albicans Biofilms by Beta-Peptide Release From Thin Films

描述(申请人提供)：白色念珠菌是从人类分离的最常见的真菌病原体，也是医院获得性感染的主要原因。系统性念珠菌血症是一种通常是致命的疾病，通常与留置医疗器械表面形成的白色念珠菌生物膜有关。我们项目的目标是开发一种新的策略来防止导管上白色念珠菌生物被膜的形成，从而减少高危患者的念珠菌血症的发生率。在之前的工作中，PI发现，与哺乳动物细胞相比，氨基酸的阳离子、两亲性寡聚体(称为多肽)对白色念珠菌具有高水平的特异性活性。这些多肽是基于与天然抗菌肽的结构相似而设计的，当与细胞膜结合时，天然抗菌肽通常折叠成两亲性阳离子螺旋。然而，β-肽可以设计成比a-肽抗菌肽具有关键优势，包括在生理pH和离子强度下的活性，更大的结构稳定性，以及对蛋白质降解的抵抗。在这里，我们将设计活性和选择性的螺旋肽化合物，并评估它们在体外和体内防止白色念珠菌生物被膜形成的能力。此外，我们还将研究混合α/β-肽的特定抗真菌活性，这些α/β-肽也折叠成两亲性螺旋，并允许调节β-肽以外的结构。为了促进抗真菌多肽从医疗器械表面的输送，我们将设计聚电解质多层(PEM)膜，以适当的速率结合和释放多肽，以防止导管应用中体内生物膜的形成。我们将评估膜厚度、膜交联度、多肽结构和化学性质对释放速率的影响。抗真菌多肽和a/a多肽抑制白色念珠菌生物膜形成的能力将在体外通过测定多肽包裹的PEM膜的生物被膜形成速率和生物膜结构来定量。优化的多肽和释放策略随后将使用大鼠中心静脉导管模型在体内进行评估。总之，这些结果将检验这样一种预测，即从导管上的PEM膜中输送-和α-肽低聚物将抑制白色念珠菌生物被膜的形成，并可能建立预防设备相关念珠菌血症的新范式。

DESCRIPTION (provided by applicant): Candida albicans is the most common fungal pathogen isolated from humans and is a leading cause of hospital-acquired infections. Systemic candidemia, an often fatal disease, is typically associated with C. albicans biofilms formed on the surface of indwelling medical devices. The goal of our project is to develop a novel strategy to prevent C. albicans biofilm formation on catheters, and to thereby reduce the incidence of candidemia in high-risk patients. In prior work the PI identified that cationic, amphiphilic oligomers of ¿-amino acids (called ¿-peptides) can exhibit high levels of specific activity against C. albicans as compared to mammalian cells. These ¿-peptides were designed based on structural similarity to natural antimicrobial peptides, which typically fold into amphiphilic cationic helices when associated with cellular membranes. However, ¿-peptides can be designed to possess key advantages over a-peptide antimicrobial peptides including activity at physiologic pH and ionic strength, greater structural stability, and resistance to proteolytic degradation. Here, we will design active and selective helical -peptides compounds and assess their ability to prevent C. albicans biofilm formation in vitro and in vivo. Additionally, we will investigate the specific antifungal activity of mixed a/¿-peptides, which also fold into amphiphilic helices, and permit regulation of structure beyond that of ¿-peptides. To facilitate delivery of antifungal ¿- and a/¿-peptides from the surface of medical devices we will design polyelectrolyte multilayer (PEM) films that incorporate and release the peptides at rates relevant for prevention of biofilm formation in vivo in catheter applications. We will assess how film thickness, film crosslinking, and peptide structures and chemical properties influence rate of release. The ability of antifungal ¿- and a/¿-peptides to inhibit C. albicans biofilm formation will be quantified in vitro by determining biofilm formation rate and biofilm structure on substrates coated with peptide-incorporated PEM films. Optimized peptides and release strategies will then be assessed in vivo using a rat central venous catheter model. Together these results will test the prediction that delivery of ¿- and a/¿-peptide oligomers from a PEM film on a catheter will inhibit C. albicans biofilm formation, and may establish a new paradigm for prevention of device-associated candidemia.