Effect of Praziquantel on Schistosoma mekongi Proteome and Phosphoproteome

Unveiling potent inhibitors for schistosomiasis through ligand-based drug design, molecular docking, molecular dynamics simulations and pharmacokinetics predictions

Schistosomiasis is a neglected tropical disease which imposes a considerable and enduring impact on affected regions, leading to persistent morbidity, hindering child development, diminishing productivity, and imposing economic burdens. Due to the emergence of drug resistance and limited management options, there is need to develop additional effective inhibitors for schistosomiasis. In view of this, quantitative structure-activity relationship studies, molecular docking, molecular dynamics simulations, drug-likeness and pharmacokinetics predictions were applied to 39 Schistosoma mansoni Thioredoxin Glutathione Reductase (SmTGR) inhibitors. The chosen QSAR model demonstrated robust statistical parameters, including an R2 of 0.798, R2adj of 0.767, Q2cv of 0.681, LOF of 0.930, R2test of 0.776, and cR2p of 0.746, confirming its reliability. The most active derivative (compound 40) was identified as a lead candidate for the development of new potential non-covalent inhibitors through ligand-based design. Subsequently, 12 novel compounds (40a-40l) were designed with enhanced anti-schistosomiasis activity and binding affinity. Molecular docking studies revealed strong and stable interactions, including hydrogen bonding, between the designed compounds and the target receptor. Molecular dynamics simulations over 100 nanoseconds and MM-PBSA free binding energy (ΔGbind) calculations validated the stability of the two best-designed molecules. Furthermore, drug-likeness and pharmacokinetics prediction analyses affirmed the potential of these designed compounds, suggesting their promise as innovative agents for the treatment of schistosomiasis.

A reanalysis and integration of transcriptomics and proteomics datasets unveil novel drug targets for Mekong schistosomiasis

Schistosomiasis, caused by Schistosoma trematodes, is a significant global health concern, particularly affecting millions in Africa and Southeast Asia. Despite efforts to combat it, the rise of praziquantel (PZQ) resistance underscores the need for new treatment options. Protein kinases (PKs) are vital in cellular signaling and offer potential as drug targets. This study focused on focal adhesion kinase (FAK) as a candidate for anti-schistosomal therapy. Transcriptomic and proteomic analyses of adult S. mekongi worms identified FAK as a promising target due to its upregulation and essential role in cellular processes. Molecular docking simulations assessed the binding energy of FAK inhibitors to Schistosoma FAK versus human FAK. FAK inhibitor 14 and PF-03814735 exhibited strong binding to Schistosoma FAK with minimal binding for human FAK. In vitro assays confirmed significant anti-parasitic activity against S. mekongi, S. mansoni, and S. japonicum, comparable to PZQ, with low toxicity in human cells, indicating potential safety. These findings highlight FAK as a promising target for novel anti-schistosomal therapies. However, further research, including in vivo studies, is necessary to validate efficacy and safety before clinical use. This study offers a hopeful strategy to combat schistosomiasis and reduce its global impact.

Praziquantel: An update on the mechanism of its action against schistosomiasis and new therapeutic perspectives

Praziquantel (PZQ) is the drug of choice for the treatment of all forms of schistosomiasis, although its mechanisms of action are not completely understood. PZQ acts largely on adult worms. This narrative literature review describes what is known about the mechanisms of action of PZQ against schistosomes from in vitro and in vivo studies and highlights the molecular targets in parasites and immune responses induced in definitive hosts by this drug. Moreover, new therapeutic uses of PZQ are discussed. Studies have demonstrated that in addition to impacting voltage-operated Ca2 + channels, PZQ may interact with other schistosome molecules, such as myosin regulatory light chain, glutathione S-transferase, and transient receptor potential channels. Following PZQ administration, increased T regulatory type 1 (Tr1) cell differentiation and decreased inflammation were observed, indicating that PZQ promotes immunoregulatory pathways. Although PZQ is widely used in mass drug administration schemes, the existence of resistant parasites has not been proven; however, it is a concern that should be constantly investigated in human populations. In addition, we discuss studies that evaluate health applications of PZQ (other than helminth infection), such as its effect in cancer therapy and its adjuvant action in vaccines against viruses.

A first attempt at determining the antibody-specific pattern of Platynosomum fastosum crude antigen and identification of immunoreactive proteins for immunodiagnosis of feline platynosomiasis

Background and Aim:

Feline platynosomiasis, also known as lizard poisoning, is a feline hepatic disease caused by the parasitic trematode Platynosomum fastosum. Since this helminth resides in biliary ducts and gallbladder, the heavy infection can lead to failure of the hepatobiliary system and can be associated with cholangiocarcinoma. The primary diagnostic tool currently used is conventional fecal microscopy. However, low sensitivity of detection could occur in the case of light infection or biliary obstruction. This study aimed to determine the antibody-specific pattern of P. fastosum crude antigen and to identify immunoreactive proteins to develop the immunodiagnostic techniques.

Materials and Methods:

We investigated potential antigens specific to P. fastosum infection using western blotting. Forty-six samples of cat serum, including 16 P. fastosum-infected sera, eight healthy control sera, and 22 sera infected with other endoparasites were used. The sensitivity, specificity, positive predictive value, and negative predictive value of each band were calculated. Immunoreactive bands with high diagnostic values were further analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to identify the protein components.

Results:

Using immunoblotting, three proteins of 72 kDa, 53 kDa, and 13 kDa were found to be immunogenic. LC-MS/MS identified these proteins as a 70 kDa heat shock protein, a hypothetical protein (CRM22_002083) (adenosine triphosphate synthase subunit beta), and histone H2B, respectively.

Conclusion:

This study is the first to reveal three proteins that could be candidates for developing diagnostic tools for feline platynosomiasis.

Docking-Based Virtual Screening Enables Prioritizing Protein Kinase Inhibitors With In Vitro Phenotypic Activity Against Schistosoma mansoni

Schistosomiasis is a parasitic neglected disease with praziquantel (PZQ) utilized as the main drug for treatment, despite its low effectiveness against early stages of the worm. To aid in the search for new drugs to tackle schistosomiasis, computer-aided drug design has been proved a helpful tool to enhance the search and initial identification of schistosomicidal compounds, allowing fast and cost-efficient progress in drug discovery. The combination of high-throughput in silico data followed by in vitro phenotypic screening assays allows the assessment of a vast library of compounds with the potential to inhibit a single or even several biological targets in a more time- and cost-saving manner. Here, we describe the molecular docking for in silico screening of predicted homology models of five protein kinases (JNK, p38, ERK1, ERK2, and FES) of Schistosoma mansoni against approximately 85,000 molecules from the Managed Chemical Compounds Collection (MCCC) of the University of Nottingham (UK). We selected 169 molecules predicted to bind to SmERK1, SmERK2, SmFES, SmJNK, and/or Smp38 for in vitro screening assays using schistosomula and adult worms. In total, 89 (52.6%) molecules were considered active in at least one of the assays. This approach shows a much higher efficiency when compared to using only traditional high-throughput in vitro screening assays, where initial positive hits are retrieved from testing thousands of molecules. Additionally, when we focused on compound promiscuity over selectivity, we were able to efficiently detect active compounds that are predicted to target all kinases at the same time. This approach reinforces the concept of polypharmacology aiming for “one drug-multiple targets”. Moreover, at least 17 active compounds presented satisfactory drug-like properties score when compared to PZQ, which allows for optimization before further in vivo screening assays. In conclusion, our data support the use of computer-aided drug design methodologies in conjunction with high-throughput screening approach.

Metabolomics reveal alterations in arachidonic acid metabolism in Schistosoma mekongi after exposure to praziquantel

BACKGROUND

Mekong schistosomiasis is a parasitic disease caused by the blood-dwelling fluke Schistosoma mekongi. This disease contributes to human morbidity and mortality in the Mekong region, posing a public health threat to people in the area. Currently, praziquantel (PZQ) is the drug of choice for the treatment of Mekong schistosomiasis. However, the molecular mechanisms of PZQ action remain unclear, and Schistosoma PZQ resistance has been reported occasionally. Through this research, we aimed to use a metabolomic approach to identify the potentially altered metabolic pathways in S. mekongi associated with PZQ treatment.

METHODOLOGY/PRINCIPAL FINDINGS

Adult stage S. mekongi were treated with 0, 20, 40, or 100 μg/mL PZQ in vitro. After an hour of exposure to PZQ, schistosome metabolites were extracted and studied with mass spectrometry. The metabolomic data for the treatment groups were analyzed with the XCMS online platform and compared with data for the no treatment group. After low, medium (IC50), and high doses of PZQ, we found changes in 1,007 metabolites, of which phosphatidylserine and anandamide were the major differential metabolites by multivariate and pairwise analysis. In the pathway analysis, arachidonic acid metabolism was found to be altered following PZQ treatment, indicating that this pathway may be affected by the drug and potentially considered as a novel target for anti-schistosomiasis drug development.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that arachidonic acid metabolism is a possible target in the parasiticidal effects of PZQ against S. mekongi. Identifying potential targets of the effective drug PZQ provides an interesting viewpoint for the discovery and development of new agents that could enhance the prevention and treatment of schistosomiasis.

Protein Kinases: Potential Drug Targets Against Schistosoma japonicum

Schistosoma japonicum (S. japonicum) infection can induce serious organ damage and cause schistosomiasis japonica which is mainly prevalent in Asia and currently one of the most seriously neglected tropical diseases. Treatment of schistosomiasis largely depends on the drug praziquantel (PZQ). However, PZQ exhibits low killing efficacy on juvenile worms and the potential emergence of its drug resistance is a continual concern. Protein kinases (PKs) are enzymes that catalyze the phosphorylation of proteins and can participate in many signaling pathways in vivo. Recent studies confirmed the essential roles of PKs in the growth and development of S. japonicum, as well as in schistosome-host interactions, and researches have screened drug targets about PKs from S. japonicum (SjPKs), which provide new opportunities of developing new treatments on schistosomiasis. The aim of this review is to present the current progress on SjPKs from classification, different functions and their potential to become drug targets compared with other schistosomes. The efficiency of related protein kinase inhibitors on schistosomes is highlighted. Finally, the current challenges and problems in the study of SjPKs are proposed, which can provide future guidance for developing anti-schistosomiasis drugs and vaccines.

Preclinical Evaluations of Modified Rice Hydrogel for Topical Ophthalmic Drug Delivery of Praziquantel on Avian Philophalmiasis

The present study aims to evaluate the efficacy of a novel drug delivery system of the modified rice hydrogel containing praziquantel (PZQ) against Philophthalmus gralli isolated from ostrich eyes and determine the toxicity of the preparation on chicken eye model. The parasiticidal activity of PZQ (0, 1, 10, and 100 µg/mL) was tested on P. gralli. The ophthalmic antiparasitic hydrogel was formulated with appropriate amount of PZQ and chemically modified rice gel. The parasitic morphology after exposure with the preparation was examined under scanning electron microscope (SEM). The anthelminthic efficacy of the preparation on motility and mortality of parasites was performed by visual inspection and vital dye staining. The ocular irritation of the preparation was evaluated for 21 days using standard avian model followed by OECD 405. The results demonstrated that the parasiticidal activity of PZQ against P. gralli appears to be in a concentration- and time-dependent manner. In addition, the concentration of PZQ 10 µg/mL (Chi squared test, p = 0.003) and exposure time for 24 h (log-rank test, p = 0.0004) is sufficient to kill parasites, when statistically compared to negative control group. Rice hydrogel containing a lethal concentration of 10 µg/mL PZQ was successfully prepared. The preparation illustrated good parasitic killing and motile inhibiting effect on P. gralli compared with PZQ 10 µg/mL and its control (p < 0.05). An appearance under SEM of non-viable parasite after being incubated with the preparation, showing parasitic deformity, was observed comparing with the viable parasite in 0.9% normal saline solution (NSS). Moreover, no irritation of chicken eyes was also observed. Our results contribute to understanding the efficacy and the safety of the rice hydrogel of PZQ which have a predictive value for controlling P. gralli on the animal eyes. However, the pharmacological application needs to be further investigated for the best possible therapeutic approach.