Castellanos-Gonzalez Alejandro, Sparks Hayley, Nava Samantha, Huang Wenlin, Zhang Zhongsheng, Rivas Kasey, Hulverson Matthew A, Barrett Lynn K, Ojo Kayode K, Fan Erkang, Van Voorhis Wesley C, White Arthur Clinton
Infectious Disease Division, Department of Internal Medicine, University of Texas Medical Branch, Galveston.
Allergy and Infectious Diseases Division, Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle.
J Infect Dis. 2016 Dec 15;214(12):1850-1855. doi: 10.1093/infdis/jiw481. Epub 2016 Oct 12.
Cryptosporidium is recognized as one of the main causes of childhood diarrhea worldwide. However, the current treatment for cryptosporidiosis is suboptimal. Calcium flux is essential for entry in apicomplexan parasites. Calcium-dependent protein kinases (CDPKs) are distinct from protein kinases of mammals, and the CDPK1 of the apicomplexan Cryptosporidium lack side chains that typically block a hydrophobic pocket in protein kinases. We exploited this to develop bumped kinase inhibitors (BKIs) that selectively target CDPK1. We have shown that several BKIs of Cryptosporidium CDPK1 potently reduce enzymatic activity and decrease parasite numbers when tested in vitro. In the present work, we studied the anticryptosporidial activity of BKI-1517, a novel BKI. The half maximal effective concentration for Cryptosporidium parvum in HCT-8 cells was determined to be approximately 50 nM. Silencing experiments of CDPK1 suggest that BKI-1517 acts on CDPK1 as its primary target. In a mouse model of chronic infection, 5 of 6 SCID/beige mice (83.3%) were cured after treatment with a single daily dose of 120 mg/kg BKI-1517. No side effects were observed. These data support advancing BKI-1517 as a lead compound for drug development for cryptosporidiosis.
隐孢子虫被认为是全球儿童腹泻的主要病因之一。然而，目前隐孢子虫病的治疗效果并不理想。钙内流对于顶复门寄生虫的入侵至关重要。钙依赖性蛋白激酶（CDPKs）与哺乳动物的蛋白激酶不同，顶复门隐孢子虫的CDPK1缺乏通常会阻断蛋白激酶中疏水口袋的侧链。我们利用这一点开发了选择性靶向CDPK1的碰撞激酶抑制剂（BKIs）。我们已经表明，几种隐孢子虫CDPK1的BKIs在体外测试时能有效降低酶活性并减少寄生虫数量。在本研究中，我们研究了新型BKI-1517的抗隐孢子虫活性。确定HCT-8细胞中小隐孢子虫的半数最大有效浓度约为50 nM。CDPK1的沉默实验表明，BKI-1517以CDPK1为主要作用靶点。在慢性感染的小鼠模型中，6只SCID/米色小鼠中有5只（83.3%）在每天单次给予120 mg/kg BKI-1517治疗后被治愈。未观察到副作用。这些数据支持将BKI-1517作为隐孢子虫病药物开发的先导化合物进行推进。
