Leishmaniasis treatment: Macrophage scavenger receptor

描述（由申请人提供）：我们研究的长期目标是将载脂蛋白的独特结构特征和脂质相互作用特性应用于利什曼病的治疗。载脂蛋白具有将磷脂囊泡转化为离散的纳米级圆盘状复合物的能力，称为纳米盘（ND）。迄今为止的研究表明，将特定的疏水药物分子掺入ND是可行的。负载多烯抗生素两性霉素B （ampB）的ND能有效抑制真菌的体外生长。此外，在感染利什曼原虫的小鼠体内进行的实验表明，ampB-ND在无毒剂量下显示出疗效。为了研究这种作用的分子基础，将进行药代动力学研究，以确定作为ND给药的ampB的血浆衰变动力学和组织分布。ND的载脂蛋白成分将受到化学和/或基因改变的影响，以产生一种被巨噬细胞上的a类清道夫受体（SR-A）识别的分子。将对ND的载脂蛋白组分进行定点诱变，以去除特定的带正电的残基，并定位带负电的氨基酸残基，以便它们创建SR-A的识别位点。我们将利用转染SR-A的中国仓鼠卵巢细胞进行结合实验，以测定SR-A与工程载脂蛋白的结合活性。将在利什曼病小鼠模型中评估含有载脂蛋白成分靶向SR-A的ampB-ND的功效。将进行研究，以检查将ampB与第二种疏水抗利什曼病药物（十六烷基磷胆碱）结合到ND中所实现的潜在增强。将评估ampB-ND在多大程度上诱导寄生物破坏含有L. major的细胞，并确定ampB-ND暴露对人外周血单个核细胞T细胞/细胞因子反应的影响。这些实验的结果将为利什曼病的治疗提供新的机会，进一步了解SR-A的配体识别特征，并证明ND作为靶向递送疏水药物的载体的用途。

DESCRIPTION (provided by applicant): The long-term goal of our research is to apply the unique structural features and lipid interaction properties of apolipoproteins to the treatment of leishmaniasis. Apolipoproteins possess the capacity to transform phospholipid vesicles into discrete, nanometer scale, disc-shaped, complexes termed nanodisks (ND). Studies to date have shown that incorporation of specific hydrophobic drug molecules into ND is feasible. ND loaded with the polyene antibiotic amphotericin B (ampB) effectively inhibits fungal growth in vitro. Furthermore, in vivo experiments in Leishmania major infected mice have revealed that ampB-ND show efficacy at non-toxic doses. To investigate the molecular basis of this effect, pharmacokinetic studies will be performed to determine plasma decay kinetics and tissue distribution of ampB administered as ND. The apolipoprotein component of ND will be subject to chemical and/or genetic alteration to create a molecule that is recognized by the class A scavenger receptor (SR-A) on macrophages. Site-directed mutagenesis of the apolipoprotein component of ND will be performed to remove specific positively charged residues and position negatively charged amino acid residues such that they create a recognition site for SR-A. Chinese hamster ovary cells transfected with SR-A will be employed in binding experiments designed to measure the SR-A binding activity of engineered apolipoproteins. The efficacy of ampB-ND harboring apolipoprotein components targeted to SR-A will be evaluated in a mouse model of leishmaniasis. Studies will be performed to examine the potential enhancement achieved by incorporating ampB with a second hydrophobic anti-leishmanial drug, hexadecylphosphocholine, into ND. The extent to which ampB-ND induce parasite destruction in cells that harbor L. major will be assessed and the effect of ampB-ND exposure on the T cell/cytokine response of human peripheral blood mononuclear cells determined. The results of these experiments should offer new opportunity for the treatment of leishmaniasis, provide further insight into the ligand recognition characteristics of SR-A, and document the utility of ND as vehicles for targeted delivery of hydrophobic drugs.