1. A high-throughput phenotypic screen identifies clofazimine as a potential treatment for cryptosporidiosis
- Author
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Christopher D. Huston, Melissa S. Love, Rajiv S. Jumani, Peter G. Schultz, Timothy M. Wright, Federico C. Beasley, Arnab Chatterjee, and Case W. McNamara
- Subjects
0301 basic medicine ,Drug Evaluation, Preclinical ,Cryptosporidiosis ,Clofazimine ,Mice ,Medicine and Health Sciences ,Protozoans ,biology ,Pharmaceutics ,lcsh:Public aspects of medicine ,Cryptosporidium ,Nitazoxanide ,Animal Models ,Drug repositioning ,Treatment Outcome ,Infectious Diseases ,Cryptosporidium parvum ,Experimental Organism Systems ,Leprosy ,Research Article ,medicine.drug ,lcsh:Arctic medicine. Tropical medicine ,lcsh:RC955-962 ,Phenotypic screening ,030106 microbiology ,Antiprotozoal Agents ,Mouse Models ,Library Screening ,Research and Analysis Methods ,Microbiology ,Cell Line ,03 medical and health sciences ,Model Organisms ,Drug Therapy ,Virology ,Parasite Groups ,Parasitic Diseases ,medicine ,Animals ,Humans ,Molecular Biology Techniques ,Molecular Biology ,Automation, Laboratory ,Molecular Biology Assays and Analysis Techniques ,Host Cells ,Drug Repositioning ,Organisms ,Oocysts ,Public Health, Environmental and Occupational Health ,Biology and Life Sciences ,Epithelial Cells ,lcsh:RA1-1270 ,biology.organism_classification ,medicine.disease ,Parasitic Protozoans ,High-Throughput Screening Assays ,Disease Models, Animal ,Regimen ,030104 developmental biology ,Immunology ,Parasitology ,Apicomplexa ,Viral Transmission and Infection - Abstract
Cryptosporidiosis has emerged as a leading cause of non-viral diarrhea in children under five years of age in the developing world, yet the current standard of care to treat Cryptosporidium infections, nitazoxanide, demonstrates limited and immune-dependent efficacy. Given the lack of treatments with universal efficacy, drug discovery efforts against cryptosporidiosis are necessary to find therapeutics more efficacious than the standard of care. To date, cryptosporidiosis drug discovery efforts have been limited to a few targeted mechanisms in the parasite and whole cell phenotypic screens against small, focused collections of compounds. Using a previous screen as a basis, we initiated the largest known drug discovery effort to identify novel anticryptosporidial agents. A high-content imaging assay for inhibitors of Cryptosporidium parvum proliferation within a human intestinal epithelial cell line was miniaturized and automated to enable high-throughput phenotypic screening against a large, diverse library of small molecules. A screen of 78,942 compounds identified 12 anticryptosporidial hits with sub-micromolar activity, including clofazimine, an FDA-approved drug for the treatment of leprosy, which demonstrated potent and selective in vitro activity (EC50 = 15 nM) against C. parvum. Clofazimine also displayed activity against C. hominis–the other most clinically-relevant species of Cryptosporidium. Importantly, clofazimine is known to accumulate within epithelial cells of the small intestine, the primary site of Cryptosporidium infection. In a mouse model of acute cryptosporidiosis, a once daily dosage regimen for three consecutive days or a single high dose resulted in reduction of oocyst shedding below the limit detectable by flow cytometry. Recently, a target product profile (TPP) for an anticryptosporidial compound was proposed by Huston et al. and highlights the need for a short dosing regimen (< 7 days) and formulations for children < 2 years. Clofazimine has a long history of use and has demonstrated a good safety profile for a disease that requires chronic dosing for a period of time ranging 3–36 months. These results, taken with clofazimine’s status as an FDA-approved drug with over four decades of use for the treatment of leprosy, support the continued investigation of clofazimine both as a new chemical tool for understanding cryptosporidium biology and a potential new treatment of cryptosporidiosis., Author summary Diarrheal diseases cause significant morbidity and mortality in the developing world. A recent multi-site study investigating diarrheal disease identified Cryptosporidium as one of the leading causes, responsible for upwards of 25% of cases in some regions. Currently approved therapy for cryptosporidiosis is limited to nitazoxanide, which is approved only for children ages 1–11 years. Nitazoxanide demonstrates moderate efficacy in immunocompetent patients and poor efficacy in immunodeficient patients. The limited treatment options underscore an opportunity to reduce the global burden of diarrheal disease by developing novel medicines with increased efficacy against Cryptosporidium spp. We report the largest high-throughput screen for anticryptosporidial compounds to date, leading to the identification of the FDA-approved drug clofazimine as a potential new treatment for cryptosporidiosis, and as a tool to probe the biology of this pathogen.
- Published
- 2017