Promising Drug Targets and Compounds with Anti-Toxoplasma gondii Activity

Toxoplasmosis is a parasitic disease caused by the globally distributed protozoan parasite Toxoplasma gondii, which infects around one-third of the world population. This disease may result in serious complications for fetuses, newborns, and immunocompromised individuals. Current treatment options are old, limited, and possess toxic side effects. Long treatment durations are required since the current therapeutic system lacks efficiency against T. gondii tissue cysts, promoting the establishment of latent infection. This review highlights the most promising drug targets involved in anti-T. gondii drug discovery, including the mitochondrial electron transport chain, microneme secretion pathway, type II fatty acid synthesis, DNA synthesis and replication and, DNA expression as well as others. A description of some of the most promising compounds demonstrating antiparasitic activity, developed over the last decade through drug discovery and drug repurposing, is provided as a means of giving new perspectives for future research in this field.

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TgATAT-Mediated α-Tubulin Acetylation Is Required for Division of the Protozoan Parasite Toxoplasma gondii

mSphere ◽

10.1128/msphere.00088-15 ◽

2016 ◽

Vol 1 (1) ◽

Cited By ~ 4

Author(s):

Joseph M. Varberg ◽

Leah R. Padgett ◽

Gustavo Arrizabalaga ◽

William J. Sullivan

Keyword(s):

Toxoplasma Gondii ◽

Drug Target ◽

Drug Targets ◽

Protozoan Parasite ◽

World Population ◽

Content Type ◽

Tubulin Acetylation ◽

Parasite Replication ◽

New Treatments

ABSTRACT Toxoplasma gondii is an opportunistic parasite that infects at least one-third of the world population. New treatments for the disease (toxoplasmosis) are needed since current drugs are toxic to patients. Microtubules are essential cellular structures built from tubulin that show promise as antimicrobial drug targets. Microtubules can be regulated by chemical modification, such as acetylation on lysine 40 (K40). To determine the role of K40 acetylation in Toxoplasma and whether it is a liability to the parasite, we performed mutational analyses of the α-tubulin gene. Our results indicate that parasites cannot survive without K40 acetylation unless microtubules are stabilized with a secondary mutation. Additionally, we identified the parasite enzyme that acetylates α-tubulin (TgATAT). Genetic disruption of TgATAT caused severe defects in parasite replication, further highlighting the importance of α-tubulin K40 acetylation in Toxoplasma and its promise as a potential new drug target. Toxoplasma gondii is a widespread protozoan parasite that causes potentially life-threatening opportunistic disease. New inhibitors of parasite replication are urgently needed, as the current antifolate treatment is also toxic to patients. Microtubules are essential cytoskeletal components that have been selectively targeted in microbial pathogens; further study of tubulin in Toxoplasma may reveal novel therapeutic opportunities. It has been noted that α-tubulin acetylation at lysine 40 (K40) is enriched during daughter parasite formation, but the impact of this modification on Toxoplasma division and the enzyme mediating its delivery have not been identified. We performed mutational analyses to provide evidence that K40 acetylation stabilizes Toxoplasma microtubules and is required for parasite replication. We also show that an unusual Toxoplasma homologue of α-tubulin acetyltransferase (TgATAT) is expressed in a cell cycle-regulated manner and that its expression peaks during division. Disruption of TgATAT with CRISPR/Cas9 ablates K40 acetylation and induces replication defects; parasites appear to initiate mitosis yet exhibit incomplete or improper nuclear division. Together, these findings establish the importance of tubulin acetylation, exposing a new vulnerability in Toxoplasma that could be pharmacologically targeted. IMPORTANCE Toxoplasma gondii is an opportunistic parasite that infects at least one-third of the world population. New treatments for the disease (toxoplasmosis) are needed since current drugs are toxic to patients. Microtubules are essential cellular structures built from tubulin that show promise as antimicrobial drug targets. Microtubules can be regulated by chemical modification, such as acetylation on lysine 40 (K40). To determine the role of K40 acetylation in Toxoplasma and whether it is a liability to the parasite, we performed mutational analyses of the α-tubulin gene. Our results indicate that parasites cannot survive without K40 acetylation unless microtubules are stabilized with a secondary mutation. Additionally, we identified the parasite enzyme that acetylates α-tubulin (TgATAT). Genetic disruption of TgATAT caused severe defects in parasite replication, further highlighting the importance of α-tubulin K40 acetylation in Toxoplasma and its promise as a potential new drug target.

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Genomics-driven drug discovery based on disease-susceptibility genes

Inflammation and Regeneration ◽

10.1186/s41232-021-00158-7 ◽

2021 ◽

Vol 41 (1) ◽

Author(s):

Kyuto Sonehara ◽

Yukinori Okada

Keyword(s):

Drug Discovery ◽

Drug Targets ◽

Disease Susceptibility ◽

Mendelian Randomization ◽

Association Studies ◽

Drug Repurposing ◽

Susceptibility Genes ◽

Genome Wide Association Studies ◽

Genome Wide ◽

Disease Associations

AbstractGenome-wide association studies have identified numerous disease-susceptibility genes. As knowledge of gene–disease associations accumulates, it is becoming increasingly important to translate this knowledge into clinical practice. This challenge involves finding effective drug targets and estimating their potential side effects, which often results in failure of promising clinical trials. Here, we review recent advances and future perspectives in genetics-led drug discovery, with a focus on drug repurposing, Mendelian randomization, and the use of multifaceted omics data.

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SELDI ProteinChip®Array Technology: Protein-Based Predictive Medicine and Drug Discovery Applications

Journal of Biomedicine and Biotechnology ◽

10.1155/s1110724303210020 ◽

2003 ◽

Vol 2003 (4) ◽

pp. 237-241 ◽

Cited By ~ 30

Author(s):

Guru Reddy ◽

Enrique A. Dalmasso

Keyword(s):

Drug Discovery ◽

Drug Targets ◽

Treatment Options ◽

Drug Effects ◽

Proteome Analysis ◽

Predictive Medicine ◽

Protein Drug ◽

Proteinchip Array ◽

Drug Candidates ◽

Array Technology

Predictive medicine, utilizing the ProteinChip®Array technology, will develop through the implementation of novel biomarkers and multimarker patterns for detecting disease, determining patient prognosis, monitoring drug effects such as efficacy or toxicity, and for defining treatment options. These biomarkers may also serve as novel protein drug candidates or protein drug targets. In addition, the technology can be used for discovering small molecule drugs or for defining their mode of action utilizing protein-based assays. In this review, we describe the following applications of the ProteinChip Array technology: (1) discovery and identification of novel inhibitors of HIV-1 replication, (2) serum and tissue proteome analysis for the discovery and development of novel multimarker clinical assays for prostate, breast, ovarian, and other cancers, and (3) biomarker and drug discovery applications for neurological disorders.

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Toxoplasmosis Related Uveitis: Clinic, Diagnosis, and Treatment

Güncel Retina Dergisi (Current Retina Journal) ◽

10.37783/crj-0171 ◽

2019 ◽

pp. 237-243

Keyword(s):

Toxoplasma Gondii ◽

Treatment Options ◽

Protozoan Parasite ◽

Posterior Uveitis ◽

Ocular Toxoplasmosis ◽

Diagnosis And Treatment ◽

Frequent Form

Ocular toxoplasmosis (OT) is considered the most frequent form of infectious posterior uveitis and is caused by the protozoan parasite Toxoplasma gondii. Despite large advances in the field of OT, large gaps still exist in our knowledge concerning the epidemiology and pathophysiology of this potentially blinding infectious old disease. In this review, we aimed to investigate the current clinical understanding of OT, diagnosis treatment options.

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Hydroxylamine and Carboxymethoxylamine Can Inhibit Toxoplasma gondii Growth through an Aspartate Aminotransferase-Independent Pathway

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01889-19 ◽

2020 ◽

Vol 64 (3) ◽

Cited By ~ 1

Author(s):

Jixu Li ◽

Huanping Guo ◽

Eloiza May Galon ◽

Yang Gao ◽

Seung-Hun Lee ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Drug Targets ◽

Protozoan Parasite ◽

Cell Types ◽

Lytic Cycle ◽

Type I ◽

Content Type ◽

Mechanism Of Inhibition

ABSTRACT Toxoplasma gondii is an obligate intracellular protozoan parasite and a successful parasitic pathogen in diverse organisms and host cell types. Hydroxylamine (HYD) and carboxymethoxylamine (CAR) have been reported as inhibitors of aspartate aminotransferases (AATs) and interfere with the proliferation in Plasmodium falciparum. Therefore, AATs are suggested as drug targets against Plasmodium. The T. gondii genome encodes only one predicted AAT in both T. gondii type I strain RH and type II strain PLK. However, the effects of HYD and CAR, as well as their relationship with AAT, on T. gondii remain unclear. In this study, we found that HYD and CAR impaired the lytic cycle of T. gondii in vitro, including the inhibition of invasion or reinvasion, intracellular replication, and egress. Importantly, HYD and CAR could control acute toxoplasmosis in vivo. Further studies showed that HYD and CAR could inhibit the transamination activity of rTgAAT in vitro. However, our results confirmed that deficiency of AAT in both RH and PLK did not reduce the virulence in mice, although the growth ability of the parasites was affected in vitro. HYD and CAR could still inhibit the growth of AAT-deficient parasites. These findings indicated that HYD and CAR inhibition of T. gondii growth and control of toxoplasmosis can occur in an AAT-independent pathway. Overall, further studies focusing on the elucidation of the mechanism of inhibition are warranted. Our study hints at new substrates of HYD and CAR as potential drug targets to inhibit T. gondii growth.

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Amiloride-sensitive cation channel 2 genotype affects the response to a carbon dioxide panic challenge

Journal of Psychopharmacology ◽

10.1177/0269881116686880 ◽

2017 ◽

Vol 31 (10) ◽

pp. 1294-1301 ◽

Cited By ~ 6

Author(s):

Nicole K Leibold ◽

Daniel LA van den Hove ◽

Wolfgang Viechtbauer ◽

Gunter Kenis ◽

Liesbet Goossens ◽

...

Keyword(s):

Carbon Dioxide ◽

Healthy Volunteers ◽

Emotional Response ◽

Treatment Options ◽

Genetic Research ◽

Current Treatment ◽

Cation Channel ◽

Differential Sensitivity ◽

Future Research ◽

Genotype Effect

Until recently, genetic research into panic disorder (PD) has had only limited success. Inspired by rodent research, demonstrating that the acid-sensing ion channel 1a (ASIC1a) is critically involved in the behavioral fear response to carbon dioxide (CO2) exposure, variants in the human homologue gene amiloride-sensitive cation channel 2 (ACCN2) were shown to be associated with PD. However, the relationship between changes in brain pH and ACCN2, as done in rodents by CO2 exposure, has not been investigated yet in humans. Here, we examined this link between the ACCN2 gene and the response to CO2 exposure in two studies: in healthy volunteers as well as PD patients and using both behavioral and physiological outcome measures. More specifically, 107 healthy volunteers and 183 PD patients underwent a 35% CO2 inhalation. Negative affect was assessed using visual analogue scales and the panic symptom list (PSL), and, in healthy volunteers, cardiovascular measurements. The single nucleotide polymorphism rs10875995 was significantly associated with a higher emotional response in PD patients and with an increase in systolic as well as diastolic blood pressure in healthy subjects. In all measurements, subjects homozygous for the T-allele showed a heightened reactivity to CO2. Furthermore, a trend towards an rs685012 genotype effect on the emotional response was found in PD patients. We provide the first evidence that genetic variants in the ACCN2 are associated with differential sensitivity to CO2 in PD patients as well as healthy volunteers, further supporting ACCN2 as a promising candidate for future research to improve current treatment options.

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Brown adipose tissue – A future treatment for obesity?

Morecambe Bay Medical Journal ◽

10.48037/mbmj.v8i3.46 ◽

2019 ◽

Vol 8 (3) ◽

pp. 75-79

Author(s):

Natasha Povey ◽

Dr Fiona Curtis

Keyword(s):

Adipose Tissue ◽

Brown Adipose Tissue ◽

Treatment Options ◽

Current Treatment ◽

Current Understanding ◽

Health Concern ◽

Future Research ◽

Future Treatment ◽

Brown Adipose

Obesity is a major public health concern: in the United Kingdom (UK) over two thirds of the population are obese or overweight, the prevalence of obesity is growing exponentially, and current treatment options have limited success – making the need for novel therapies vital. Brown adipose tissue (BAT) has the ability to safely dissipate chemical energy as heat and in 2009 was found to be active in human adults, leading to hope that its therapeutic manipulation could contribute to weight loss. This review discusses methods proposed for BAT activation and potential pitfalls in our current understanding to evaluate if BAT can be used as a future treatment for obesity. To date, ơ3-adrenergic receptor (ơ3-AR) agonists and cold activation have been shown to be the most promising options to activate BAT. However, cold activation requires a high degree of patient cooperation and ơ3-AR agonists appear non-effective long-term. Nonetheless, ơ3-AR agonists are likely to be a more realistic treatment than cold activation, making our next challenge to understandand mitigate the mechanisms that inhibit BAT activation in long-term ơ3-AR agonist administration. Our assumptions about BAT activation are predominately from rodent studies and based on measurements from [18F]-fl uorodeoxyglucose (18F-FDG)-positron-emission tomography and computed tomography (PET/CT) imaging, both with their respective limitations. BAT has offered huge insight into weight homeostasis, with the potential of offering prospective therapeutics for obesity and beyond. Nevertheless, before we can truly understand the real possibilities of BAT we need to further our current understanding of the physiological controls of BAT, potentially leading to more suitable therapies. The focus for future research should be to improve and standardise the methodology used to measure BAT activation, enabling larger clinical trials and better comparisons.

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Identification of Antifungal Compounds against Multidrug Resistant Candida auris Utilizing a High Throughput Drug Repurposing Screen

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01305-20 ◽

2021 ◽

Author(s):

Yu-Shan Cheng ◽

Jose Santinni Roma ◽

Min Shen ◽

Caroline Mota Fernandes ◽

Patricia S. Tsang ◽

...

Keyword(s):

High Throughput ◽

High Throughput Screening ◽

Treatment Options ◽

Drug Repurposing ◽

Multidrug Resistant ◽

Current Treatment ◽

Drug Combinations ◽

Serine Palmitoyltransferase ◽

Candida Auris ◽

Pharmacologically Active

Candida auris is an emerging fatal fungal infection that has resulted in several outbreaks in hospitals and care facilities. Current treatment options are limited by the development of drug resistance. Identifying new pharmaceuticals to combat these drug-resistant infections will thus be required to overcome this unmet medical need. We have established a bioluminescent ATP-based assay to identify new compounds and potential drug combinations showing effective growth inhibition against multiple strains of multidrug resistant Candida auris. The assay is robust and suitable for assessing large compound collections by high throughput screening. Utilizing this assay, we conducted a screen of 4,314 approved drugs and pharmacologically active compounds which yielded 25 compounds including 6 novel anti-Candida auris compounds and 13 sets of potential two drug combinations. Among the drug combinations, the serine palmitoyltransferase inhibitor myriocin demonstrated a combinational effect with flucytosine against all tested isolates during screening. This combinational effect was confirmed in 13 clinical isolates of Candida auris.

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In vitro anti-Toxoplasma gondii efficacy of synthesised benzyltriazole derivatives

Onderstepoort Journal of Veterinary Research ◽

10.4102/ojvr.v88i1.1898 ◽

2021 ◽

Vol 88 (1) ◽

Author(s):

Huanping Guo ◽

Yang Gao ◽

David D. N’Da ◽

Xuenan Xuan

Keyword(s):

Toxoplasma Gondii ◽

Fluorescent Protein ◽

Treatment Options ◽

Preliminary Test ◽

Positive Control ◽

Current Treatment ◽

Effective Vaccine ◽

Bone Marrow Toxicity ◽

Type I

Toxoplasma gondii, an obligate intracellular parasite, is the aetiological agent of toxoplasmosis, a disease that affects approximately 25% – 30% of the world’s population. At present, no safe and effective vaccine exists for the prevention of toxoplasmosis. Current treatment options for toxoplasmosis are active only against tachyzoites and may also cause bone marrow toxicity. To contribute to the global search for novel agents for the treatment of toxoplasmosis, we herein report the in vitro activities of previously synthesised benzyltriazole derivatives. The effects of these compounds against T. gondii in vitro were evaluated by using a expressing green fluorescent protein (GFP) type I strain parasite (RH-GFP) and a type II cyst-forming strain of parasite (PruΔku80Δhxgprt). The frontline antitubercular drug isoniazid, designated as Frans J. Smit -isoniazid (FJS-INH), was also included in the screening as a preliminary test in view of future repurposing of this agent. Of the compounds screened, FJS-302, FJS-303, FJS-403 and FJS-INH demonstrated 80% parasite growth inhibition with IC50 values of 5.6 µg/mL, 6.8 µg/µL, 7.0 µg/mL and 19.8 µg/mL, respectively. FJS-302, FJS-303 and FJS-403 inhibited parasite invasion and replication, whereas, sulphadiazine (SFZ), the positive control, was only effective against parasite replication. In addition, SFZ induced bradyzoite differentiation in vitro, whilst FJS-302, FJS-303 and FJS-403 did not increase the bradyzoite number. These results indicate that FJS-302, FJS-303 and FJS-403 have the potential to act as a viable source of antiparasitic therapeutic agents.

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Defining the Location of T-bet-expressing Myeloid Cells During Acute Intestinal Toxoplasma gondii Infection

Proceedings of IMPRS ◽

10.18060/25814 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Melody Wickstrom ◽

Madison Schanz ◽

Kimberly Larson ◽

Américo H. López-Yglesias

Keyword(s):

Toxoplasma Gondii ◽

Treatment Options ◽

Foodborne Pathogen ◽

Myeloid Cells ◽

Myeloid Cell ◽

Protozoan Parasite ◽

The United States ◽

Parasite Infection ◽

Toxoplasma Gondii Infection ◽

Deficient Mice

Background/Objective: The protozoan parasite Toxoplasma gondii is the second leading cause of foodborne pathogen-related deaths in the United States. The transcription factor T-bet is indispensable for host immunity against T. gondii. The absence of T-bet results in rapid susceptibility during parasite infection. T-bet has been considered essential for T-cell-derived IFN-g during T. gondii infection; yet, recent research has shown that T-bet is not required for lymphocyte-derived IFN-g responses. Our preliminary research shows that T-bet-deficient mice succumb to parasite infection significantly quicker than mice lacking lymphocytes. This has led to our hypothesis that T-bet-dependent myeloid cells are critical for host resistance during acute intestinal T. gondii infection. The objective of this project was to define the location of the T-bet-expressing myeloid cells in the medial small intestines (MSI) of naïve and infected mice during acute mucosal parasite infection. Methods: We used immunofluorescence microscopy to determine the location of T-bet-expressing myeloid cells in the MSI of naïve and T. gondii infected mice. Mice were orally infected with 40 cysts of the ME49 strain of T. gondii. On days 0 and 5, one-inch MSI segments were harvested, fixed with 4% paraformaldehyde for at least one hour, and then frozen in OCT compound. Tissues were then cut into 8mm sections and placed onto slides for staining. Sections were stained for nuclei, CD11c, T-bet, and T. gondii. Results: Our results revealed T-bet-expressing CD11c+ cells in both the MSI and spleen on days 0 and 5 of T. gondii infection. Summary: These data indicate that T-bet-expressing myeloid cells are present in the MSI during T. gondii infection. Defining the position of these cells will allow us to determine T-bet’s role in mediating myeloid cell-dependent T. gondii clearance. Due to the limited treatment options for patients suffering from toxoplasmosis it is critical to define new mechanisms for eliminating T. gondii.

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