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着重要作用。这种相互作用的精妙特异性导致了几种有希望的碳水化合物疗法的发展。然而，合成低聚糖的高昂成本已被证明是该方法更广泛应用的重大障碍。此外，在通过“基因治疗”方法提供最佳治疗药物的情况下，没有直接的方法来提供碳水化合物基试剂。有几个分子模拟的例子，其中无关的分子有足够的表面拓扑结构被认为是功能等价的。碳水化合物结构的多肽模拟物已经被确定，这些化合物的生产成本相对较低，并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，可导致危及生命的感染，特别是在免疫功能低下的人中。这种微生物的毒力在一定程度上与其通过修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。这项探索性的研究拨款提案的目的是测试这样一个假设，即特定细胞表面碳水化合物结构的肽仿制可以用来降低体内口腔念珠菌病的水平，这种疾病伴随着(实验性的)唾液腺功能低下。我们将使用两种互补的方法来产生多肽模拟物；(1)将筛选与凝集素或识别所需低聚糖的抗体结合的多肽；以及(2)将从针对适当的抗寡糖抗体制备的抗独特型抗体的抗体高变区序列中获得多肽序列。通过实验确定每个多肽的二级结构，并获得定量描述每个多肽与其同源凝集素或抗体相互作用的动力学参数。在体外能显着减少念珠菌与口腔上皮细胞黏附的模拟物，然后将在我们实验室以前使用的手术去活的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.