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Spottiswoode N, Haston JC, Hanners NW, Gruenberg K, Kim A, DeRisi JL, Wilson MR. Challenges and advances in the medical treatment of granulomatous amebic encephalitis. Ther Adv Infect Dis 2024; 11:20499361241228340. [PMID: 38312848 PMCID: PMC10838035 DOI: 10.1177/20499361241228340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 01/09/2024] [Indexed: 02/06/2024] Open
Abstract
Granulomatous amebic encephalitis, caused by the free-living amebae Balamuthia mandrillaris or Acanthamoeba species, is a rare and deadly infectious syndrome with a current mortality rate of >90%. Much work remains to define the optimal treatment for these infections. Here, we provide a comprehensive overview of the supporting evidence behind antimicrobials currently recommended by the Centers for Disease Control and Prevention (CDC) with updated statistics on survival rates and medication usage from the CDC Free-Living Ameba Database. We also discuss promising treatments, especially the emerging therapeutic agent nitroxoline, and provide recommendations for the next steps in this area.
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Affiliation(s)
- Natasha Spottiswoode
- Division of Infectious Diseases, University of California San Francisco, San Francisco, CA, USA
| | - Julia C. Haston
- Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Natasha W. Hanners
- Division of Pediatric Infectious Diseases, University of Texas Southwestern, Dallas, TX, USA
| | - Katherine Gruenberg
- Department of Clinical Pharmacy, University of California San Francisco School of Pharmacy, San Francisco, CA, USA
| | - Annie Kim
- Department of Clinical Pharmacy, Zuckerberg San Francisco General, San Francisco, CA, USA
| | - Joseph L. DeRisi
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- Chan Zuckerberg Biohub SF, San Francisco, CA, USA
| | - Michael R. Wilson
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA 94143, USA
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Haston JC, Cope JR. Amebic encephalitis and meningoencephalitis: an update on epidemiology, diagnostic methods, and treatment. Curr Opin Infect Dis 2023; 36:186-191. [PMID: 37093056 PMCID: PMC10798061 DOI: 10.1097/qco.0000000000000923] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
PURPOSE OF REVIEW Free-living amebae (FLA) including Naegleria fowleri , Balamuthia mandrillaris , and Acanthamoeba species can cause rare, yet severe infections that are nearly always fatal. This review describes recent developments in epidemiology, diagnosis, and treatment of amebic meningoencephalitis. RECENT FINDINGS Despite similarities among the three pathogenic FLA, there are notable variations in disease presentations, routes of transmission, populations at risk, and outcomes for each. Recently, molecular diagnostic tools have been used to diagnose a greater number of FLA infections. Treatment regimens for FLA have historically relied on survivor reports; more data is needed about novel treatments, including nitroxoline. SUMMARY Research to identify new drugs and guide treatment regimens for amebic meningoencephalitis is lacking. However, improved diagnostic capabilities may lead to earlier diagnoses, allowing earlier treatment initiation and improved outcomes. Public health practitioners should continue to prioritize increasing awareness and providing education to clinicians, laboratorians, and the public about amebic infections.
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Affiliation(s)
- Julia C. Haston
- Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jennifer R. Cope
- Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Repurposing the Kinase Inhibitor Mavelertinib for Giardiasis Therapy. Antimicrob Agents Chemother 2022; 66:e0001722. [PMID: 35703552 PMCID: PMC9295539 DOI: 10.1128/aac.00017-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A phenotypic screen of the ReFRAME compound library was performed to identify cell-active inhibitors that could be developed as therapeutics for giardiasis. A primary screen against Giardia lamblia GS clone H7 identified 85 cell-active compounds at a hit rate of 0.72%. A cytotoxicity counterscreen against HEK293T cells was carried out to assess hit compound selectivity for further prioritization. Mavelertinib (PF-06747775), a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), was identified as a potential new therapeutic based on indication, activity, and availability after reconfirmation. Mavelertinib has in vitro efficacy against metronidazole-resistant 713-M3 strains. Other EGFR-TKIs screened in follow-up assays exhibited insignificant inhibition of G. lamblia at 5 μM, suggesting that the primary molecular target of mavelertinib may have a different mechanistic binding mode from human EGFR-tyrosine kinase. Mavelertinib, dosed as low as 5 mg/kg of body weight or as high as 50 mg/kg, was efficacious in the acute murine Giardia infection model. These results suggest that mavelertinib merits consideration for repurposing and advancement to giardiasis clinical trials while its analogues are further developed.
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Levinson S, Kumar KK, Wang H, Tayyar R, Dunning M, Toland A, Budvytiene I, Vogel H, Chang A, Banaei N, Shuer L. Balamuthia mandrillaris brain infection: a rare cause of a ring-enhancing central nervous system lesion. Illustrative case. JOURNAL OF NEUROSURGERY: CASE LESSONS 2022; 3:CASE2268. [PMID: 36303497 PMCID: PMC9379710 DOI: 10.3171/case2268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 02/23/2022] [Indexed: 11/24/2022]
Abstract
BACKGROUND An 80-year-old man presented with subacute mental status change, dizziness, and left-sided vision loss. Magnetic resonance imaging demonstrated a ring-enhancing right parietooccipital lesion. OBSERVATIONS Biopsy and laboratory testing demonstrated an amoebic Balamuthia mandrillaris infection. Fewer than 200 cases of this infection have been recognized in the United States, and no standardized treatment regimen currently exists. LESSONS Rapid antimicrobial therapy with miltefosine, azithromycin, fluconazole, flucytosine, sulfadiazine, and albendazole was initiated. The pathophysiology, diagnosis, and management of this infection and the patient’s course were reviewed. The importance of biopsy for pathologic and laboratory diagnosis and rapid treatment initiation with a multidisciplinary team was reinforced.
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Affiliation(s)
| | | | | | - Ralph Tayyar
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Palo Alto, California
| | - Megan Dunning
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Palo Alto, California
| | | | | | | | - Amy Chang
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Palo Alto, California
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Differential Growth Rates and In Vitro Drug Susceptibility to Currently Used Drugs for Multiple Isolates of Naegleria fowleri. Microbiol Spectr 2022; 10:e0189921. [PMID: 35138140 PMCID: PMC8826828 DOI: 10.1128/spectrum.01899-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The free-living amoeba Naegleria fowleri, which typically dwells within warm, freshwater environments, can opportunistically cause primary amoebic meningoencephalitis (PAM), a disease with a mortality rate of >97%. The lack of positive treatment outcomes for PAM has prompted the discovery and development of more effective therapeutics, yet most studies utilize only one or two clinical isolates. The inability to assess possible heterogenic responses to drugs among isolates from various geographical regions hinders progress in the discovery of more effective drugs. Here, we conducted drug efficacy and growth rate determinations for 11 different clinical isolates by applying a previously developed CellTiter-Glo 2.0 screening technique and flow cytometry. We found significant differences in the susceptibilities of these isolates to 7 of 8 drugs tested, all of which make up the cocktail that is recommended to physicians by the U.S. Centers for Disease Control and Prevention. We also discovered significant variances in growth rates among isolates, which draws attention to the differences among the amoeba isolates collected from different patients. Our results demonstrate the need for additional clinical isolates of various genotypes in drug assays and highlight the necessity for more targeted therapeutics with universal efficacy across N. fowleri isolates. Our data establish a needed baseline for drug susceptibility among clinical isolates and provide a segue for future combination therapy studies as well as research related to phenotypic or genetic differences that could shed light on mechanisms of action or predispositions to specific drugs. IMPORTANCENaegleria fowleri, also known as the brain-eating amoeba, is ubiquitous in warm freshwater and is an opportunistic pathogen that causes primary amoebic meningoencephalitis. Although few cases are described each year, the disease has a case fatality rate of >97%. In most laboratory studies of this organism, only one or two well-adapted lab strains are used; therefore, there is a lack of data to discern if there are major differences in potency of currently used drugs for multiple strains and genotypes of the amoeba. In this study, we found significant differences in the susceptibilities of 11 N. fowleri isolates to 7 of the 8 drugs currently used to treat the disease. The data from this study provide a baseline of drug susceptibility among clinical isolates and suggest that new drugs should be tested on a larger number of isolates in the future.
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Ponatinib, Lestaurtinib and mTOR/PI3K inhibitors are promising repurposing candidates against Entamoeba histolytica. Antimicrob Agents Chemother 2021; 66:e0120721. [PMID: 34871094 DOI: 10.1128/aac.01207-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dysentery caused by Entamoeba histolytica affects millions of people annually. Current treatment regimens are based on metronidazole to treat invasive parasites combined with paromomycin for luminal parasites. Issues with treatment include significant side effects, inability to easily treat breastfeeding and pregnant women, the use of two sequential agents, and concern that all therapy is based on nitroimidazole agents with no alternatives if clinical resistance emerges. Thus, the need for new drugs against amebiasis is urgent. To identify new therapeutic candidates, we screened the ReFRAME library (11,948 compounds assembled for Repurposing, Focused Rescue, and Accelerated Medchem) against E. histolytica trophozoites. We identified 159 hits in the primary screen at 10 μM and 46 compounds were confirmed in secondary assays. Overall, 26 were selected as priority molecules for further investigation including 6 FDA approved, 5 orphan designation, and 15 which are currently in clinical trials (3 phase III, 7 phase II and 5 phase I). We found that all 26 compounds are active against metronidazole resistant E. histolytica and 24 are able to block parasite recrudescence after drug removal. Additionally, 14 are able to inhibit encystation and 2 (lestaurtinib and LY-2874455) are active against mature cysts. Two classes of compounds are most interesting for further investigations: the Bcr-Abl TK inhibitors, with the ponatinib (EC50 0.39) as most potent and mTOR or PI3K inhibitors with 8 compounds in clinical development, of which 4 have nanomolar potency. Overall, these are promising candidates and represent a significant advance for drug development against E. histolytica.
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Bhosale NK, Parija SC. Balamuthia mandrillaris: An opportunistic, free-living ameba - An updated review. Trop Parasitol 2021; 11:78-88. [PMID: 34765527 PMCID: PMC8579774 DOI: 10.4103/tp.tp_36_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Revised: 05/27/2021] [Accepted: 06/07/2021] [Indexed: 01/08/2023] Open
Abstract
Balamuthia mandrillaris is an opportunistic, free-living ameba that is pathogenic to humans. It has a worldwide distribution but is mainly detected in warmer regions. Balamuthia infections are rare but have been reported in both immunocompetent and immunocompromised individuals of all ages. B. mandrillaris can enter through wounds on the skin or the nose and cause cutaneous lesions and the usually fatal Balamuthia amebic encephalitis (BAE). Infection usually spreads from the lungs or through nerve fibers, and attacks the central nervous system, forming granulomatous lesions and necrosis in the brain. Balamuthia infection is usually chronic, and patients initially present with nonspecific symptoms, including headache, nausea, myalgia, and low-grade fever. As the disease progresses, the patient becomes paralyzed and comatose, often leading to death. Lack of knowledge of predisposing factors, specific treatment, and standardized detection tools have resulted in a nearly cent percent fatality rate. Although only about 200 cases have been reported worldwide since its characterization in the 1990s, the number of reported cases has increased over the years. BAE is an emerging disease and a major health concern. Few patients have survived Balamuthia infections with antimicrobial treatment that has largely been empirical. Early diagnosis is the key and requires familiarity with the disease and a high degree of suspicion on the part of the diagnostician. There are currently no specific treatment and prevention recommendations. This review highlights our current understanding of B. mandrillaris in terms of its pathogenicity, genomics, and novel diagnostic and therapeutic approaches against BAE infections.
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Affiliation(s)
- Namrata K Bhosale
- Department of Microbiology, Mahatma Gandhi Medical College and Research Institute, Puducherry, India
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Ahmed U, Anwar A, Ong SK, Anwar A, Khan NA. Applications of medicinal chemistry for drug discovery against Acanthamoeba infections. Med Res Rev 2021; 42:462-512. [PMID: 34472107 DOI: 10.1002/med.21851] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 07/13/2021] [Accepted: 08/17/2021] [Indexed: 01/16/2023]
Abstract
Acanthamoeba is a genus of free-living amoebae, pervasively found in the environment. Most of its pathogenic species are the causative agent of sight-threatening Acanthamoeba keratitis and fatal granulomatous amoebic encephalitis. Despite the advancements in the field of chemotherapy, treating Acanthamoeba infections is still challenging due to incomplete knowledge of the complicated pathophysiology. In case of infection, the treatment regimen for the patients is often ineffective due to delayed diagnosis, poor specificity, and side-effects. Besides the resistance of Acanthamoeba cysts to most of the drugs, the recurrence of infection further complicates the recovery. Thus, it is necessary to develop an effective treatment which can eradicate these rare, but serious infections. Based on various computational and in vitro studies, it has been established that the synthetic scaffolds such as heterocyclic compounds may act as potential drug leads for the development of antiamoebic drugs. In this review, we report different classes of synthetic compounds especially heterocyclic compounds which have shown promising results against Acanthamoeba. Moreover, the antiamoebic activities of synthetic compounds with their possible mode of actions against Acanthamoeba, have been summarized and discussed in this review.
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Affiliation(s)
- Usman Ahmed
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Subang Jaya, Selangor, Malaysia
| | - Ayaz Anwar
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Subang Jaya, Selangor, Malaysia
| | - Seng-Kai Ong
- Department of Biological Sciences, School of Medical and Life Sciences, Sunway University, Subang Jaya, Selangor, Malaysia
| | - Areeba Anwar
- Faculty of Defence Science and Technology, National Defence University of Malaysia, Kuala Lampur, Malaysia
| | - Naveed Ahmed Khan
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, UAE
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Debnath A. Drug discovery for primary amebic meningoencephalitis: from screen to identification of leads. Expert Rev Anti Infect Ther 2021; 19:1099-1106. [PMID: 33496193 DOI: 10.1080/14787210.2021.1882302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Introduction: Naegleria fowleri is responsible for primary amebic meningoencephalitis (PAM) which has a fatality rate of >97%. Because of the rarity of the disease, pharmaceutical companies do not pursue new drug discovery for PAM. Yet, it is possible that the infection is underreported and finding a better drug would have an impact on people suffering from this deadly infection.Areas covered: This paper reports the efforts undertaken by different academic groups over the last 20 years to test different compounds against N. fowleri. The drug discovery research encompassed synthesis of new compounds, development and use of high-throughput screening methods and attempts to repurpose clinically developed or FDA-approved compounds for the treatment of PAM.Expert opinion: In absence of economic investment to develop new drugs for PAM, repurposing the FDA-approved drugs has been the best strategy so far to identify new leads against N. fowleri. Increasing use of high-throughput phenotypic screening has the potential to accelerate the identification of new leads, either in monotherapy or in combination treatment. Since phase II clinical trial is not possible for PAM, it is critical to demonstrate in vivo efficacy of a clinically safe compound to translate the discovery from lab to the clinic.
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Affiliation(s)
- Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
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Sauvey C, Ehrenkaufer G, Shi D, Debnath A, Abagyan R. Antineoplastic kinase inhibitors: A new class of potent anti-amoebic compounds. PLoS Negl Trop Dis 2021; 15:e0008425. [PMID: 33556060 PMCID: PMC7895358 DOI: 10.1371/journal.pntd.0008425] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 02/19/2021] [Accepted: 12/21/2020] [Indexed: 12/17/2022] Open
Abstract
Entamoeba histolytica is a protozoan parasite which infects approximately 50 million people worldwide, resulting in an estimated 70,000 deaths every year. Since the 1960s E. histolytica infection has been successfully treated with metronidazole. However, drawbacks to metronidazole therapy exist, including adverse effects, a long treatment course, and the need for an additional drug to prevent cyst-mediated transmission. E. histolytica possesses a kinome with approximately 300–400 members, some of which have been previously studied as potential targets for the development of amoebicidal drug candidates. However, while these efforts have uncovered novel potent inhibitors of E. histolytica kinases, none have resulted in approved drugs. In this study we took the alternative approach of testing a set of twelve previously FDA-approved antineoplastic kinase inhibitors against E. histolytica trophozoites in vitro. This resulted in the identification of dasatinib, bosutinib, and ibrutinib as amoebicidal agents at low-micromolar concentrations. Next, we utilized a recently developed computational tool to identify twelve additional drugs with human protein target profiles similar to the three initial hits. Testing of these additional twelve drugs led to the identification of ponatinib, neratinib, and olmutinib were identified as highly potent, with EC50 values in the sub-micromolar range. All of these six drugs were found to kill E. histolytica trophozoites as rapidly as metronidazole. Furthermore, ibrutinib was found to kill the transmissible cyst stage of the model organism E. invadens. Ibrutinib thus possesses both amoebicidal and cysticidal properties, in contrast to all drugs used in the current therapeutic strategy. These findings together reveal antineoplastic kinase inhibitors as a highly promising class of potent drugs against this widespread and devastating disease. Every year, nearly a hundred thousand people worldwide die from infection by the intestinal parasite Entamoeba histolytica, despite the widespread availability of metronidazole as a treatment. Here we report that six anticancer drugs of the kinase inhibitor class possess potent anti-amoebic properties, with one of them killing both actively dividing parasite and its transmissible cysts. These anticancer kinase inhibitors, including the dual-purpose drug with both amoebicidal and cysticidal activities may be used to treat amoebiasis, especially in cancer patients or in life-threatening brain- and liver-infecting forms of the disease.
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Affiliation(s)
- Conall Sauvey
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
- * E-mail: (CS); (RA)
| | - Gretchen Ehrenkaufer
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Da Shi
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
| | - Ruben Abagyan
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
- * E-mail: (CS); (RA)
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Escrig JI, Hahn HJ, Debnath A. Activity of Auranofin against Multiple Genotypes of Naegleria fowleri and Its Synergistic Effect with Amphotericin B In Vitro. ACS Chem Neurosci 2020; 11:2464-2471. [PMID: 32392039 DOI: 10.1021/acschemneuro.0c00165] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Primary amebic meningoencephalitis, caused by brain infection with a free-living ameba, Naegleria fowleri, leads to extensive inflammation of the brain and death within 3-7 days after symptoms begin. Treatment of primary amebic meningoencephalitis relies on amphotericin B in combination with other drugs, but use of amphotericin B is associated with severe adverse effects. Despite a fatality rate of over 97%, economic incentive to invest in development of antiamebic drugs by the pharmaceutical industry is lacking. Development of safe and rapidly acting drugs remains a critical unmet need to avert future deaths. Since FDA-approved anti-inflammatory and antiarthritic drug auranofin is a known inhibitor of selenoprotein synthesis and thioredoxin reductase and the genome of N. fowleri encodes genes for both selenocysteine biosynthesis and thioredoxin reductases, we tested the effect of auranofin against N. fowleri strains of different genotypes from the USA, Europe, and Australia. Auranofin was equipotent against all tested strains with an EC50 of 1-2 μM. Our growth inhibition study at different time points demonstrated that auranofin is fast-acting, and ∼90% growth inhibition was achieved within 16 h of drug exposure. A short exposure of N. fowleri to auranofin led to the accumulation of intracellular reactive oxygen species. This is consistent with auranofin's role in inhibiting antioxidant pathways. Further, combination of auranofin and amphotericin B led to 95% of growth inhibition with 2-9-fold dose reduction for amphotericin B and 3-20-fold dose reduction for auranofin. Auranofin has the potential to be repurposed for the treatment of primary amebic meningoencephalitis.
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Affiliation(s)
- Jose Ignacio Escrig
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0756, United States
| | - Hye Jee Hahn
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0756, United States
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0756, United States
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Inhibition of Fatty Acid Oxidation as a New Target To Treat Primary Amoebic Meningoencephalitis. Antimicrob Agents Chemother 2020; 64:AAC.00344-20. [PMID: 32513800 PMCID: PMC7526813 DOI: 10.1128/aac.00344-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022] Open
Abstract
Primary amoebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoeba Naegleria fowleri. The amoeba migrates along the olfactory nerve to the brain, resulting in seizures, coma, and, eventually, death. Previous research has shown that Naegleria gruberi, a close relative of N. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several already-approved inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine. Primary amoebic meningoencephalitis (PAM) is a rapidly fatal infection caused by the free-living amoeba Naegleria fowleri. The amoeba migrates along the olfactory nerve to the brain, resulting in seizures, coma, and, eventually, death. Previous research has shown that Naegleria gruberi, a close relative of N. fowleri, prefers lipids over glucose as an energy source. Therefore, we tested several already-approved inhibitors of fatty acid oxidation alongside the currently used drugs amphotericin B and miltefosine. Our data demonstrate that etomoxir, orlistat, perhexiline, thioridazine, and valproic acid inhibited growth of N. gruberi. We then tested these compounds on N. fowleri and found etomoxir, perhexiline, and thioridazine to be effective growth inhibitors. Hence, not only are lipids the preferred food source for N. gruberi, but also oxidation of fatty acids seems to be essential for growth of N. fowleri. Inhibition of fatty acid oxidation could result in new treatment options, as thioridazine inhibits N. fowleri growth in concentrations that can be reached at the site of infection. It could also potentiate currently used therapy, as checkerboard assays revealed synergy between miltefosine and etomoxir. Animal testing should be performed to confirm the added value of these inhibitors. Although the development of new drugs and randomized controlled trials for this rare disease are nearly impossible, inhibition of fatty acid oxidation seems a promising strategy as we showed effectivity of several drugs that are or have been in use and that thus could be repurposed to treat PAM in the future.
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Rice CA, Troth EV, Russell AC, Kyle DE. Discovery of Anti-Amoebic Inhibitors from Screening the MMV Pandemic Response Box on Balamuthia mandrillaris, Naegleria fowleri, and Acanthamoeba castellanii. Pathogens 2020; 9:E476. [PMID: 32560115 PMCID: PMC7344389 DOI: 10.3390/pathogens9060476] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 02/06/2023] Open
Abstract
Pathogenic free-living amoebae, Balamuthia mandrillaris, Naegleria fowleri, and several Acanthamoeba species are the etiological agents of severe brain diseases, with case mortality rates > 90%. A number of constraints including misdiagnosis and partially effective treatments lead to these high fatality rates. The unmet medical need is for rapidly acting, highly potent new drugs to reduce these alarming mortality rates. Herein, we report the discovery of new drugs as potential anti-amoebic agents. We used the CellTiter-Glo 2.0 high-throughput screening methods to screen the Medicines for Malaria Ventures (MMV) Pandemic Response Box in a search for new active chemical scaffolds. Initially, we screened the library as a single-point assay at 10 and 1 µM. From these data, we reconfirmed hits by conducting quantitative dose-response assays and identified 12 hits against B. mandrillaris, 29 against N. fowleri, and 14 against A. castellanii ranging from nanomolar to low micromolar potency. We further describe 11 novel molecules with activity against B. mandrillaris, 22 against N. fowleri, and 9 against A. castellanii. These structures serve as a starting point for medicinal chemistry studies and demonstrate the utility of phenotypic screening for drug discovery to treat diseases caused by free-living amoebae.
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Affiliation(s)
- Christopher A. Rice
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
- Center for Tropical and Emerging Global Diseases, Athens, GA 30602, USA; (E.V.T.); (A.C.R.)
| | - Emma V. Troth
- Center for Tropical and Emerging Global Diseases, Athens, GA 30602, USA; (E.V.T.); (A.C.R.)
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - A. Cassiopeia Russell
- Center for Tropical and Emerging Global Diseases, Athens, GA 30602, USA; (E.V.T.); (A.C.R.)
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
| | - Dennis E. Kyle
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
- Center for Tropical and Emerging Global Diseases, Athens, GA 30602, USA; (E.V.T.); (A.C.R.)
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
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Ehrenkaufer G, Li P, Stebbins EE, Kangussu-Marcolino MM, Debnath A, White CV, Moser MS, DeRisi J, Gisselberg J, Yeh E, Wang SC, Company AH, Monti L, Caffrey CR, Huston CD, Wang B, Singh U. Identification of anisomycin, prodigiosin and obatoclax as compounds with broad-spectrum anti-parasitic activity. PLoS Negl Trop Dis 2020; 14:e0008150. [PMID: 32196500 PMCID: PMC7112225 DOI: 10.1371/journal.pntd.0008150] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/01/2020] [Accepted: 02/18/2020] [Indexed: 01/20/2023] Open
Abstract
Parasitic infections are a major source of human suffering, mortality, and economic loss, but drug development for these diseases has been stymied by the significant expense involved in bringing a drug though clinical trials and to market. Identification of single compounds active against multiple parasitic pathogens could improve the economic incentives for drug development as well as simplifying treatment regimens. We recently performed a screen of repurposed compounds against the protozoan parasite Entamoeba histolytica, causative agent of amebic dysentery, and identified four compounds (anisomycin, prodigiosin, obatoclax and nithiamide) with low micromolar potency and drug-like properties. Here, we extend our investigation of these drugs. We assayed the speed of killing of E. histolytica trophozoites and found that all four have more rapid action than the current drug of choice, metronidazole. We further established a multi-institute collaboration to determine whether these compounds may have efficacy against other parasites and opportunistic pathogens. We found that anisomycin, prodigiosin and obatoclax all have broad-spectrum antiparasitic activity in vitro, including activity against schistosomes, T. brucei, and apicomplexan parasites. In several cases, the drugs were found to have significant improvements over existing drugs. For instance, both obatoclax and prodigiosin were more efficacious at inhibiting the juvenile form of Schistosoma than the current standard of care, praziquantel. Additionally, low micromolar potencies were observed against pathogenic free-living amebae (Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba castellanii), which cause CNS infection and for which there are currently no reliable treatments. These results, combined with the previous human use of three of these drugs (obatoclax, anisomycin and nithiamide), support the idea that these compounds could serve as the basis for the development of broad-spectrum anti-parasitic drugs.
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Affiliation(s)
- Gretchen Ehrenkaufer
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
| | - Pengyang Li
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
| | - Erin E. Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Monica M. Kangussu-Marcolino
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Corin V. White
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Matthew S. Moser
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Joseph DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Jolyn Gisselberg
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA, United States of America
| | - Ellen Yeh
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, United States of America
- Department of Pathology, Stanford University, Stanford, CA, United States of America
| | - Steven C. Wang
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Ana Hervella Company
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Ludovica Monti
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Conor R. Caffrey
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Christopher D. Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Upinder Singh
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, United States of America
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