CARBOHYDRATE-BASED PEPTIDOMIMETICS TO PREVENT CANDIDIAS

细胞表面碳水化合物（低聚糖）在广泛的细胞识别事件中发挥重要作用。这种相互作用的精细特异性导致了几种有前途的基于碳水化合物的治疗方法的发展。然而，合成低聚糖的高成本已被证明是该方法更广泛使用的重大障碍。此外，在通过“基因治疗”方法最佳递送治疗药物的情况下，没有直接递送碳水化合物药物的方法。有几个分子模仿的例子，其中不相关的分子共享足够的表面拓扑结构，被认为是功能等同。碳水化合物结构的肽模拟物已经被确定，它们的生产成本相对较低，并且可以通过标准的基因治疗方法在体内传递。白色念珠菌是一种机会性真菌，可引起危及生命的感染，特别是在免疫功能低下的个体中。这种生物的毒性部分与它通过装饰真菌和宿主细胞表面的识别碳水化合物结构附着在宿主组织表面的能力有关。这项探索性研究的目的是验证一种假设，即特定细胞表面碳水化合物结构的拟肽物可以用来降低体内口腔念珠菌病伴（实验性）唾液腺功能减退的水平。我们将使用两种互补的方法来生成肽模拟物；(1)组合文库将筛选与凝集素或抗体结合的肽，这些抗体识别感兴趣的寡糖；(2)肽序列将从针对适当的抗寡糖抗体制备的抗糖尿病型抗体的抗体高变区序列中得到。通过实验确定每个肽的二级结构，并获得定量描述每个肽与其同源凝集素或抗体相互作用的动力学参数。在体外引起念珠菌粘附口腔上皮细胞显著减少的模拟物将在先前在我们实验室使用的手术去盐大鼠模型系统中进行测试。

Cell surface carbohydrates (oligosaccharides) play significant roles in a wide range of cellular recognition events. The exquisite specificity of such interactions has led to development of several promising carbohydrate-based therapeutics. However, the high cost of synthesizing oligosaccharides has proven to be significant barrier to more wide-spread use of this approach. Moreover, In instances where a therapeutic is optimally delivered via a "gene therapy" approach, there is no direct way of delivering a carbohydrate based agent. There are several examples of molecular mimicry in which unrelated molecules share sufficient surface topology to be considered functional equivalents. Peptide mimetics of a carbohydrate structure have been identified, and these would be relatively inexpensive to produce and could be delivered in vivo by standard gene therapy approaches. Candida albicans Is an opportunistic fungus which can cause life-threatening infection, particularly among immunocompromised individuals. The virulence of this organism is related, in part, to Its ability to adhere to host tissue surfaces via the recognition carbohydrate structures which decorate the cell-surfaces of both fungus and host. The goal of this exploratory research grant proposal is to test the hypothesis that peptidomimetics of specific cell-surface carbohydrate structures can be used to reduce the level of the in vivo oral candidiasis which accompanies (experimental) salivary gland hypofunction. We will use two complementary approaches to generate the peptidomimetics; (1) combinatorial libraries will be screened for peptides which bind to either lectins or antibodies which recognize the oligosaccharide of interest; and (2) peptide sequence will be derived from antibody hypervariable region sequences of anti-ldiotypic antibodies prepared against appropriate anti-oligosaccharide antibodies. The secondary structure of each peptide will be experimentally determined and kinetic parameters which quantitatively describe the interaction of each peptide with its cognate lectin or antibody will be obtained. Mimetics which cause significant reduction of Candida adhesion to buccal epithelial cells in vitro will then be tested in a surgically desalivated rat model system used previously in our laboratories.