Heparin-mimetic sulfated oligoxylan inhibitors of malaria parasites

疟疾寄生虫的肝素模拟硫酸化寡聚木聚糖抑制剂

• 批准号: 7594208
• 负责人: AUDREY L STONE
• 金额: $ 5.2万
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7594208
• 关键词: Acute; Anti-malarial drug resistance; Antimalarials; Biological; Biological Assay; Cells; Cerebral Malaria; Cessation of life; Charge; Child; Class; Clinical; Clinical Research; Culicidae; Data; Dependence; Development; Disease; Dose; Endothelium; Erythrocytes; Exhibits; Family; Gelshift Analysis; Generations; Glucuronic Acid; Glucuronic Acids; Goals; HIV Infections; Health Sciences; Heparin; Heparitin Sulfate; Hepatocyte; Immunity; In Vitro; Incidence; Infection; Inorganic Sulfates; Invaded; Laboratories; Libraries; Life; Ligands; Malaria; Malaria Vaccines; Measurement; Measures; Medical; Methods; Microcirculation; Molecular; Oligosaccharides; Organism; Parasites; Pathology; Patients; Pharmaceutical Preparations; Pharmacologic Substance; Plasmodium falciparum; Preventive; Process; Proteins; Reaction; Research; Resistance; Resources; Role; Sporozoites; Staging; Structure; Symptoms; Testing; Unspecified or Sulfate Ion Sulfates; Vaccines; Variant; Virulent; Xylans; Xylose; combinatorial; density; drug development; inhibitor/antagonist; mimetics; mimicry; novel; parasite invasion; pathogen; prevent; receptor; research study; response; sugar

Heparin was known to inhibit the rosetting and cytoadhesion of parasitized Plasmodium falciparum erythrocytes (PfRBC) to normal RBC and the endothelium, and to clear blockage of the microcirculation and ameliorate life-threatening symptoms of cerebral malaria when administered in children; it also inhibited the initial malaria parasite invasion of hepatocytes (and possibly RBC). Malaria ranks in the top three deadliest diseases globally (approximately 300 million clinical cases per year). 1-3% of the Pf parasites are highly virulent, causing severe and cerebral malaria and the death of about 2 million people per year (90 % young children). There is no preventive vaccine, and malarial parasites are increasingly resistant to anti-malarial drugs. This project has previously applied a macro combinatorial srategy to study the heparin inhibitions in vitro, utilizing our library of sulfated oligoxylans. These were prepared from a Heparin/Heparan sulfate (H/HS)-mimetic pharmaceutical that mimics numerous discrete biological actions of the heparin family. (See HD001315-03-05). The capacity of P. yoelii sporozoites (freshly isolated from infected mosquitos) to invade hepatocytes was measured; differential potencies of inhibition of the parasite invasion by S-OligoS was demonstrated; highest potency and concentration- dependence resided in two S-OligoS in mass class about 7200 and 3700 with 43 and 56 percent inhibition at 3.5 and 5 micromolar, resp. CURRENT STUCTURAL CONSIDERATIONS indicate the S-OligoS structure contains a tetrasaccharide motif of three xyloses and a glucuronic acid as a branch on the xylan chain i.e., -D-glucuronyl-alpha 1,2 beta 1,4 D-(xylyl)3 with up to one thirdof the GlcA O-methylated. The sugars are within 90 percent sulfated yielding a high negative charge density. Such motif could accommodate the subtle variations in geometries involving sulfates which would be components to provide for mutifunctional mimicry of the heparins. The mass of Cp 6 and 3 wouod accommodate the presence of 6 and 2 such motifs, resp. Studies on the Inhibition of the erythrocyte invasion stage of malarial parasites revealed that S-OligoS of mass class less than 4500 exhibited very low inhibitory capacity, while high potency was associated with S-OligoS of relatively high mass class equal to or greater than 10,000. Such data suggests that the molecular reactions underlying the inhibition of the two parasite stages differ. Enlagement of our H/HS-mimetic S-OligoS library to generate specific anti-malaria Components of mass class Cp 4 and 5 (8-9000) continues. Recent advances in malaria research include the first method for generation of sporozoites (and other stages of the malaria parasite) in a cell free culture (John Sacci, Jr.). This now promises to provide amounts of sporozoites to allow completion of full dose-response measurements of groups of S-oligoS in bioassays by comparison. We plan to resume our studies on inhibition of sporozoites, parasitized RBC, and rosetting as a path towards stable, inexpensive heparin-mimetic anti-malarials against initial infection, pathologies, and/or acute cerebral malaria to the limit of our resources. Experiments to elucidate putative protein ligands using a modified gel-shift analysis and/or to identify protein ligands using fluorescent receptors (library of S-oligoS and/or heparin-oligoS) have been identified.

已知肝素可以抑制恶性疟原虫红细胞（PFRBC）对正常的RBC和内皮的粘性和细胞粘附，并清除儿童服用时脑症状疟疾的微循环和安息的威胁性生命症状的症状； 它还抑制了肝细胞（可能是RBC）的最初疟疾寄生虫入侵。 疟疾在全球排名前三的最致命疾病中排名（每年约3亿个临床病例）。 1-3％的PF寄生虫具有高毒，导致严重和脑疟疾，每年约有200万人死亡（90％的幼儿）。没有预防性疫苗，疟疾寄生虫越来越对抗疟疾药物具有抗性。 该项目以前已经应用了宏观组合srategy来研究体外肝素抑制作用，并利用我们的硫酸化寡素库。 这些是由肝素/肝素硫酸盐（H/HS）模拟药物制备的，该药物模仿了肝素家族的许多离散生物学作用。 （请参阅HD001315-03-05）。 测量了P. yoelii孢子岩（从感染蚊子新鲜分离）侵入肝细胞的能力； 证明了S-Oligos抑制寄生虫侵袭的差异效力。在大约7200和3700的质量类别中，最高的效力和浓度依赖性在两个S-橄榄岩中，有43和56％的抑制作用，为3.5和5 microlol，分别。 当前的构件考虑表明，S-Oligos结构包含三种木糖的四含糖基序，而葡萄糖酸是Xylan链上的分支，即-d-葡萄糖酰基-Alpha 1,2β1,2β1,4d-（xylyl）3，最多三分之一三分之一。 糖在90％的硫酸盐之内，产生高电荷密度。 这种基序可以适应涉及硫酸盐的几何形状的细微变化，这些变化将是提供肝素型模仿的组成部分。 CP 6和3的质量适应6和2的存在。 关于抑制疟疾寄生虫红细胞浸润阶段的研究表明，质量类别小于4500的质量类表现出非常低的抑制能力，而高效力与相对较高的质量类别等于或大于或大于10,000的S-Oligos有关。 这样的数据表明，抑制两个寄生虫阶段的分子反应不同。 我们的H/HS模拟S-Oligos文库的启动仍在继续生成质量CP 4和5（8-9000）的特定抗马拉里亚组件。 疟疾研究的最新进展包括在无细胞培养物中生成子孢子（和疟原虫寄生虫的其他阶段）的第一种方法（John Sacci，Jr。）。 相比之下，这现在有望提供大量的子孢子，以允许在生物测定中完成S-Oligos组的全剂量反应测量。 我们计划恢复有关刺激孢子物，寄生的RBC和玫瑰花的研究，作为通往稳定的，廉价的肝素模拟抗癌症，以针对初始感染，病理学和/或急性大脑疟疾，达到我们资源的极限。 已经鉴定了使用改良的凝胶转移分析和/或使用荧光受体（S-Oligos和/或肝素 - 橄榄岩库）鉴定蛋白质配体的实验。