Praziquantel for the treatment of schistosomiasis: its use for control in areas with endemic disease and prospects for drug resistance

Schistosomiasis presenting as ruptured ectopic pregnancy

A woman from sub-Saharan Africa living in the Middle East, presented with acute abdominal pain and COVID-19 infection. She underwent a laparotomy and left salpingectomy for a left tubal ruptured ectopic pregnancy. The histopathology report revealed the presence of tubal schistosomiasis in addition to the ectopic sac. The report emphasises the importance of considering female genital schistosomiasis as a potential cause of ectopic pregnancy and the need for collaboration between obstetricians and infectious disease physicians in the definitive treatment of the disease to reduce reproductive morbidity. This case report highlights the possibility of female genital schistosomiasis as a cause of ectopic pregnancy in women from endemic regions.

Therapeutic potential of hydantoin and thiohydantoin compounds against Schistosoma mansoni: An integrated in vitro, DNA, ultrastructural, and ADMET in silico approach

The study aimed to conduct in vitro biological assessments of hydantoin and thiohydantoin compounds against mature Schistosoma mansoni worms, evaluate their cytotoxic effects and predict their pharmacokinetic parameters using computational methods. The compounds showed low in vitro cytotoxicity and were not considered hemolytic. Antiparasitic activity against adult S. mansoni worms was tested with all compounds at concentrations ranging from 200 to 6.25 μM. Compounds SC01, SC02, and SC03 exhibited low activity. Compounds SC04, SC05, SC06 and SC07 caused 100 % mortality within 24 h of incubation at a concentration of 100 and 200 μM. Thiohydantoin SC04 exhibited the highest activity, resulting in 100 % mortality after 24 h of incubation at a concentration of 50 μM and IC50 of 28 µM. In the ultrastructural analysis (SEM), the compound SC04 (200 µM) induced integumentary changes, formation of integumentary blisters, and destruction of tubercles and spicules. Therefore, the SC04 compound shows promise as an antiparasitic against S. mansoni.

Nature-Inspired Gallinamides Are Potent Antischistosomal Agents: Inhibition of the Cathepsin B1 Protease Target and Binding Mode Analysis

Schistosomiasis, caused by a parasitic blood fluke of the genus Schistosoma, is a global health problem for which new chemotherapeutic options are needed. We explored the scaffold of gallinamide A, a natural peptidic metabolite of marine cyanobacteria that has previously been shown to inhibit cathepsin L-type proteases. We screened a library of 19 synthetic gallinamide A analogs and identified nanomolar inhibitors of the cathepsin B-type protease SmCB1, which is a drug target for the treatment of schistosomiasis mansoni. Against cultured S. mansoni schistosomula and adult worms, many of the gallinamides generated a range of deleterious phenotypic responses. Imaging with a fluorescent-activity-based probe derived from gallinamide A demonstrated that SmCB1 is the primary target for gallinamides in the parasite. Furthermore, we solved the high-resolution crystal structures of SmCB1 in complex with gallinamide A and its two analogs and describe the acrylamide covalent warhead and binding mode in the active site. Quantum chemical calculations evaluated the contribution of individual positions in the peptidomimetic scaffold to the inhibition of the target and demonstrated the importance of the P1' and P2 positions. Our study introduces gallinamides as a powerful chemotype that can be exploited for the development of novel antischistosomal chemotherapeutics.

Spinal cord schistosomiasis in a 6-year-old child with complete recovery after spine surgery and medical treatment: case report and discussion

Spinal cord schistosomiasis is a rare and severe form of schistosomiasis. The prognosis is largely conditioned by early diagnosis and treatment. The authors present a case of spinal cord schistosomiasis complicated by spinal cord compression syndrome. This is the case of a 6-year-old patient who presented with febrile gastroenteritis followed by complete paralysis of both lower limbs of sudden onset following a brief stay in a village setting with notion of multiple baths at a stream. Spinal cord MRI revealed an enlarged spinal cord spanning D10 to D12 with heterogeneous contrast enhancement and a syrinx cavity above the lesion. Biological workup revealed an inflammatory syndrome. Treatment consisted of decompressive laminectomy with biopsy of the lesion and a syringo-subarachnoid shunt. Pathological analysis revealed fragments of central nervous system tissues with an infiltrate composed of lymphocytes, plasmocytes, and macrophages producing granulomatous foci lined with areas of necrosis in addition to a large contingent of polynuclear eosinophils, agglutinating around or covering in some places elongated ovoid structures, with relatively thick eosinophilic shells and presenting a terminal spur. Adjuvant treatment consisted of praziquantel and corticotherapy for 1 month. The evolution showed marked improvement in the neurological deficits. She now walks unassisted and has good sphincter control. Spinal cord schistosomiasis is rare in our context; its diagnosis is difficult. The treatment is both medical and surgical.

The Microbiome and Infectious Diseases

Our perception of microbes has considerably changed since the recognition of their pathogenic potential in the 19th century. The discovery of antibiotics and their subsequent widespread adoption have substantially altered the landscape of medicine, providing us with treatment options for many infectious diseases and enabling the deployment of previously risky interventions (eg, surgical procedures and chemotherapy), while also leading to the rise of AMR. The latter is commonly viewed as the predominant downside of antibiotic use. However, with the increasing recognition that all metazoan organisms rely on a community of microbes (the microbiota) for normal development and for most physiologic processes, the negative impacts of antibiotic use now extend well beyond AMR. Using the iceberg as a metaphor, we argue that the effects of antibiotics on AMR represent the tip of the iceberg, with much greater repercussions stemming from their role in the rise of so-called noncommunicable diseases (including obesity, diabetes, allergic and autoimmune diseases, neurodevelopmental disorders, and certain cancers). We highlight some of the emerging science around the intersection of the microbiome, antibiotic use, and health (including biological costs and future therapeutic avenues), and we advocate a more nuanced approach in evaluating the impacts of proposed antibiotic use, especially in the setting of preexposure and postexposure prophylaxis.

Gendered lives, gendered Vulnerabilities: An intersectional gender analysis of exposure to and treatment of schistosomiasis in Pakwach district, Uganda

INTRODUCTION

Schistosomiasis is a neglected tropical disease (NTD) that is endemic in Uganda, despite several interventions to eliminate it. It is transmitted when people infected with it pass on their waste matter into fresh water bodies used by others, consequently infecting them. Several studies have demonstrated gender and age differences in prevalence of schistosomiasis and NTDs such as lymphatic filariasis and soil transmitted helminths. However, few intersectional gender analysis studies of schistosomiasis have been undertaken. Using the World Health Organisation (WHO)'s intersectional gender analysis toolkit, this study was undertaken to identify which social stratifiers most intersected with gender to influence vulnerability to and access to treatment for schistosomiasis disease, to understand how best to implement interventions against it.

METHODOLOGY

This was a qualitative study comprising eight focus group discussions (FGDs) of community members, disaggregated by age, sex and location, and 10 key informant interviews with health care providers and community leaders. The Key informants were selected purposively while the community members were selected using stratified random sampling (to cater for age, sex and location). The data was analysed manually to identity key themes around gender, guided by a gender and intersectionality lens.

RESULTS

The study established that while the River Nile provided livelihoods it also exposed the community to schistosomiasis infection. Gender relations played a significant role in exposure to and access to treatment for schistosomiasis. Traditional gender roles determined the activities men and women performed in the private and public spheres, which in turn determined their exposure to schistosomiasis and treatment seeking behaviour. Gender relations also affected access to treatment and decision making over family health care. Men and some women who worked outside the home were reported to prioritise their income earning activities over seeking health care, while women who visited the health facilities more regularly for antenatal care and to take sick children were reported to have higher chance of being tested and treated in time, although this was undermined by the irregular and infrequent provision of praziquantel (PZQ) mass drug administration. These gender relations were further compounded by underdevelopment and limited economic opportunities, insufficient health care services, as well as the respondent's age and location.

CONCLUSIONS

The study concludes that vulnerability to schistosomiasis disease and treatment occurred within a complex web of gender relations, culture, poverty, limited economic opportunities and insufficient health services delivery, which together undermined efforts to eliminate schistosomiasis. This study recommends the following: a) increased public health campaigns around schistosomiasis prevention and treatment; b) more regular PZQ MDA at home and schools; c) improved health services delivery and integration of services to include vector control; d) prioritising NTDs; e) providing alternative economic activities; and f) addressing negative gender norms that promote social behaviours which negatively influence vulnerability, treatment seeking and decision making for health.

In vitro activity, ultrastructural analysis and in silico pharmacokinetic properties (ADMET) of thiazole compounds against adult worms of Schistosoma mansoni

The present work aimed to carry out in vitro biological assays of thiazole compounds against adult worms of Schistosoma mansoni, as well as the in silico determination of pharmacokinetic parameters to predict the oral bioavailability of these compounds. In addition to presenting moderate to low cytotoxicity against mammalian cells, thiazole compounds are not considered hemolytic. All compounds were initially tested at concentrations ranging from 200 to 6.25 μM against adult worms of S. mansoni parasites. The results showed the best activity of PBT2 and PBT5 at a concentration of 200 μM, which caused 100% mortality after 3 h of incubation. While at 6 h of exposure, 100% mortality was observed at the concentration of 100 µM. Subsequent studies with these same compounds allowed classifying PBT5, PBT2, PBT6 and PBT3 compounds, which were considered active and PBT1 and PBT4 compounds, which were considered inactive. In the ultrastructural analysis the compounds PBT2 and PBT5 (200 µM) promoted integumentary changes with exposure of the muscles, formation of integumentary blisters, integuments with abnormal morphology and destruction of tubercles and spicules. Therefore, the compounds PBT2 and PBT5 are promising antiparasitics against S. mansoni.

Perspective on Schistosomiasis Drug Discovery: Highlights from a Schistosomiasis Drug Discovery Workshop at Wellcome Collection, London, September 2022

In September 2022, the Drug Discovery Unit at the University of Dundee, UK, organised an international meeting at the Wellcome Collection in London to explore the current clinical situation and challenges associated with treating schistosomiasis. The aim of this meeting was to discuss the need for new treatments in view of the clinical situation and to ascertain what the key requirements would be for any potential new anti-schistosomals. This information will be essential to inform ongoing drug discovery efforts for schistosomiasis. We also discussed the potential drug discovery pathway and associated criteria for progressing compounds to the clinic. To date, praziquantel (PZQ) is the only drug available to treat all species causing schistosomiasis, but it is often unable to completely clear parasites from an infected patient, partially due to its inactivity against juvenile worms. PZQ-mediated mass drug administration campaigns conducted in endemic areas (e.g., sub-Saharan Africa, where schistosomiasis is primarily prevalent) have contributed to reducing the burden of disease but will not eliminate the disease as a public health problem. The potential for Schistosoma to develop resistance towards PZQ, as the sole treatment available, could become a concern. Consequently, new anthelmintic medications are urgently needed, and this Perspective aims to capture some of the learnings from our discussions on the key criteria for new treatments.

Spinal Schistosomiasis Masquerading as an Intramedullary Tumor

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Biochanin A in murine Schistosoma mansoni infection: effects on inflammation, oxidative stress and fibrosis

Biochanin A (BCA) is a multifunctional natural compound that possesses anti-infective, anti-inflammatory, anti-oxidative and hepatoprotective effects. The aim of the study was to assess the therapeutic efficacy of BCA on Schistosoma mansoni-infected mice. Fifty mice were divided into six different groups as non-infected, non-infected BCA-treated, infected untreated, early infected BCA-treated (seven days post-infection (dpi)), late infected BCA-treated 60 dpi and infected praziquantel (PZQ)-treated groups. Parasitological, histopathological examination and immunohistochemical staining of transforming growth factor (TGF)-β, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) were investigated in liver sections. Cytochrome P450 (CYP450) gene expression of S. mansoni was evaluated by quantitative real-time polymerase chain reaction (RT-qPCR). A single dose of BCA significantly reduced worm burden in early (82.14%) and late infection (77.74%), mean tissue egg load in early (7.27 ± 0.495) and late BCA administration (7.63 ± 0.435) and decreased granuloma size. CYP450 mRNA expression was significantly reduced in early BCA treatment as compared to late treatment which emphasizes that early administration of BCA had more pronounced effects on worms than late administration. Both early and late BCA administration led to significant reduction in inflammatory cytokines as TGF and iNOS. Although the reduction of TGF and iNOS in BCA-treated mice was superior to PZQ, no statistically significant differences were noted. However, a significant downregulation of COX2 was noted in hepatocytes as compared to both infected control and PZQ-treated mice. BCA has schistosomicidal, anti-inflammatory, antioxidant and anti-fibrotic effects and could be regarded as a potential drug in schistosomiasis treatment.

Thioredoxin reductase selenoproteins from different organisms as potential drug targets for treatment of human diseases

Human thioredoxin reductase (TrxR) is a selenoprotein with a central role in cellular redox homeostasis, utilizing a highly reactive and solvent-exposed selenocysteine (Sec) residue in its active site. Pharmacological modulation of TrxR can be obtained with several classes of small compounds showing different mechanisms of action, but most often dependent upon interactions with its Sec residue. The clinical implications of TrxR modulation as mediated by small compounds have been studied in diverse diseases, from rheumatoid arthritis and ischemia to cancer and parasitic infections. The possible involvement of TrxR in these diseases was in some cases serendipitously discovered, by finding that existing clinically used drugs are also TrxR inhibitors. Inhibiting isoforms of human TrxR is, however, not the only strategy for human disease treatment, as some pathogenic parasites also depend upon Sec-containing TrxR variants, including S. mansoni, B. malayi or O. volvulus. Inhibiting parasite TrxR has been shown to selectively kill parasites and can thus become a promising treatment strategy, especially in the context of quickly emerging resistance towards other drugs. Here we have summarized the basis for the targeting of selenoprotein TrxR variants with small molecules for therapeutic purposes in different human disease contexts. We discuss how Sec engagement appears to be an indispensable part of treatment efficacy and how some therapeutically promising compounds have been evaluated in preclinical or clinical studies. Several research questions remain before a wider application of selenoprotein TrxR inhibition as a first-line treatment strategy might be developed. These include further mechanistic studies of downstream effects that may mediate treatment efficacy, identification of isoform-specific enzyme inhibition patterns for some given therapeutic compounds, and the further elucidation of cell-specific effects in disease contexts such as in the tumor microenvironment or in host-parasite interactions, and which of these effects may be dependent upon the specific targeting of Sec in distinct TrxR isoforms.

A review of the genetic determinants of praziquantel resistance in Schistosoma mansoni: Is praziquantel and intestinal schistosomiasis a perfect match?

Schistosomiasis is a neglected tropical disease (NTD) caused by parasitic trematodes belonging to the Schistosoma genus. The mainstay of schistosomiasis control is the delivery of a single dose of praziquantel (PZQ) through mass drug administration (MDA) programs. These programs have been successful in reducing the prevalence and intensity of infections. Due to the success of MDA programs, the disease has recently been targeted for elimination as a public health problem in some endemic settings. The new World Health Organization (WHO) treatment guidelines aim to provide equitable access to PZQ for individuals above two years old in targeted areas. The scale up of MDA programs may heighten the drug selection pressures on Schistosoma parasites, which could lead to the emergence of PZQ resistant schistosomes. The reliance on a single drug to treat a disease of this magnitude is worrying should drug resistance develop. Therefore, there is a need to detect and track resistant schistosomes to counteract the threat of drug resistance to the WHO 2030 NTD roadmap targets. Until recently, drug resistance studies have been hindered by the lack of molecular markers associated with PZQ resistance. This review discusses recent significant advances in understanding the molecular basis of PZQ action in S. mansoni and proposes additional genetic determinants associated with PZQ resistance. PZQ resistance will also be analyzed in the context of alternative factors that may decrease efficacy within endemic field settings, and the most recent treatment guidelines recommended by the WHO.

Schistosome TRPML channels play a role in neuromuscular activity and tegumental integrity

Schistosomiasis is a neglected tropical disease caused by parasitic flatworms of the genus Schistosoma. Mono-therapeutic treatment of this disease with the drug praziquantel, presents challenges such as inactivity against immature worms and inability to prevent reinfection. Importantly, ion channels are important targets for many current anthelmintics. Transient receptor potential (TRP) channels are important mediators of sensory signals with marked effects on cellular functions and signaling pathways. TRPML channels are a class of Ca2+-permeable TRP channels expressed on endolysosomal membranes. They regulate lysosomal function and trafficking, among other functions. Schistosoma mansoni is predicted to have a single TRPML gene (SmTRPML) with two splice variants differing by 12 amino acids. This study focuses on exploring the physiological properties of SmTRPML channels to better understand their role in schistosomes. In mammalian cells expressing SmTRPML, TRPML activators elicit a rise in intracellular Ca2+. In these cells, SmTRPML localizes both to lysosomes and the plasma membrane. These same TRPML activators elicit an increase in adult worm motility that is dependent on SmTRPML expression, indicating a role for these channels in parasite neuromuscular activity. Suppression of SmTRPML in adult worms, or exposure of adult worms to TRPML inhibitors, results in tegumental vacuolations, balloon-like surface exudates, and membrane blebbing, similar to that found following TRPML loss in other organisms. Together, these findings indicate that SmTRPML may regulate the function of the schistosome endolysosomal system. Further, the role of SmTRPML in neuromuscular activity and in parasite tegumental integrity establishes this channel as a candidate anti-schistosome drug target.

Comparative characterization of microRNAs of Schistosoma japonicum from SCID mice and BALB/c mice: Clues to the regulation of parasite growth and development

Schistosomiasis, caused by a parasite with a wide range of mammalian hosts, remains one of the most prevailing parasitic diseases in the world. While numerous studies have reported that the growth and reproduction of schistosomes in immunodeficient mice was significantly retarded, the underlying molecular mechanisms have yet to be revealed. In this study, we comparatively analyzed the microRNA expression of Schistosoma japonicum derived from SCID and BALB/c mice on the 35^th day post-infection by high-throughput RNA sequencing as prominent morphological abnormalities had been observed in schistosomes from SCID mice when compared with those from BALB/c mice. The results revealed that more than 72% and 61% of clean reads in the small RNA libraries of female and male schistosomes, respectively, could be mapped to the selected miRs in the miRBase or the sequences of species-specific genomes. Further analysis identified 122 miRNAs using TPM >0.01 as the threshold value, including 75 known and 47 novel miRNAs, 96 of which were commonly expressed across all the four tested schistosome libraries. Comparative analysis of the libraries of schistosomes from SCID and BALB/c mice identified 15 differentially expressed miRNAs (5 up-regulated and 10 down-regulated) among females and 16 among males (9 up-regulated and 7 down-regulated). Integrated analysis of the two sets of differentially expressed miRNAs of female and male worms identified 2 miRNAs (sja-miR-3488 and sja-miR-novel_29) that overlapped between female and male datasets. Prediction of miRNA targets and Gene Ontology (GO) term enrichment analysis of the predicted target genes revealed that these genes were involved in some important biological processes, such as nucleic acid metabolic process, macromolecule modification, and cellular aromatic compound metabolic process. The predicted target genes were further matched to the differentially expressed genes in male and female schistosomes from the above two hosts, obtaining 7 genes that may be responsible for regulating the growth, development and sex maturation of schistosomes. Taken together, this study provides the first identification of differentially expressed miRNAs in schistosomes from SCID and BALB/c mice. These miRNAs and their predicted target mRNAs are probably involved in the regulation of development, growth, and maturation of schistosomes. Therefore, this study expands our understanding of schistosome development regulation and host-parasite relationship, and also provides a valuable set of potential anti-schistosomal targets for prevention and control of schistosomiasis.

In vitro, in vivo, and ADME evaluation of SF5-containing N,N'-diarylureas as antischistosomal agents

In recent years, N,N'-diarylureas have emerged as a promising chemotype for the treatment of schistosomiasis, a disease that poses a considerable health burden to millions of people worldwide. Here, we report a novel series of N,N'-diarylureas featuring the scarcely explored pentafluorosulfanyl group. Low IC₅₀ values for Schistosoma mansoni newly transformed schistosomula (0.6 - 7.7 μM) and adult worms (0.1 - 1.6 μM) were observed. Four selected compounds, highly active in presence of albumin (>70% at 10 μM), endowed with decent cytotoxicity profile (SI against L6 cells >8.5) and good microsomal hepatic stability (>62.5% of drug remaining after 60 min), were tested in S. mansoni infected mice. Despite the promising in vitro worm killing potency, none of them showed significant activity in vivo. Pharmacokinetic data showed a slow absorption, with maximal drug concentrations reached after 24 h of exposure. Finally, no direct correlation between drug exposure and in vivo activity was found. Thus, further investigations are needed to better understand the underlying mechanisms of SF₅-containing N,N'-diarylureas.

Evaluation of Praziquantel Effectivenss After Decades of Prolonged Use in an Endemic Area in Egypt

PURPOSE

Praziquantel (PZQ) is the preferred drug for schistomiasis treatment because of its safety. As PZQ is used for mass drug administration (MDA) in schistosomiasis endemic areas, the effectiveness of the drug, used solely for decades, should be continuously monitored to detect drug resistance. We aimed to assess the effectiveness of PZQ to cure Schistosoma mansoni infection and to reduce the intensity of infection in an endemic area by estimating the cure rate (CR), egg reduction rate (ERR), and comparing these estimates to the levels recommended by the World Health Organization (WHO).

METHODS

A total of 342 children aged 5-15 years living in Kafr-El-Sheikh were screened for S. mansoni infection. Stool samples were examined microscopically using Kato-Katz (KK) technique. Among the screened children, 106 children had S. mansoni ova in stool, 100 of them received the first dose of PZQ (40 mg/kg). Four weeks later, 96 of 100 children received the second dose of PZQ. Stool samples, collected 4 weeks after each dose of PZQ, were examined using KK. The effectiveness of PZQ was assessed based on ERR and CR.

RESULTS

CR after the first dose of PZQ was 66.7%, increased to 79.12% after second dose (X² = 3.05, P = 0.08). Median egg count before treatment was 30.00 (6.00-744), that significantly decreased after two doses of PZQ to 0.00 (0.00-221.33) (Z = 8.29, P = 0.001). Children aged 10-15 years showed higher CR (91.3%) than those aged 5-9 years (OR = 5.25, CI 1.58-17.40).

CONCLUSIONS

PZQ is still an effective agent against S. mansoni in endemic areas, achieving a high CR and ERR with predominantly low intensity of infection. Age is a main predictor of response to PZQ.

In vitro Effects of Punica granatum Ellagitannins on Adult Worms of Schistosoma mansoni

Schistosomiasis ranks second behind malaria in terms of overall morbidity and mortality. We evaluated the lethal effect of Punica granatum ellagitannins, extracted from the fruit rind, placenta and barks of the root and stem, on adult worms of Schistosoma mansoni (S. mansoni). All four ellagitannins were lethal to S. mansoni adult worms. However, while the rind ellagitannins were the most potent, placental ellagitannins were the least. Rind ellagitannins were capable of killing 40% of adult worms at a concentration of 25µg/mL after 5 days. The killing of 100% of the worms was achievable by rind ellagitannins at a concentration of 50µg/mL after 5 days. The LD_50S of the rind ellagitannins after 96h and 120h were 41.25 µg/mL and 28.73 respectively. Ellagitannins-treated worms suffered from erosions, wrinkles, swellings and losses, degenerations of the surface tubercles and tegument. In addition, ellagitannins induced deformation and degradation of oral and ventral suckers and degenerations in the muscles of worms. Ellagitannins also caused a separation of coupled worms and reduction of their motility. Data obtained suggest that ellagitannins of pomegranate could be considered as a cheap candidate for the treatment of schistosomiasis.

Imported Schistosomiasis: A New Public Health Challenge for China

Significantly increased imported schistosomiasis cases have been reported in China as the economy grows. The aim of this study is to review and summarize the current status, clinical features, and transmission risk of imported infections of Schistosoma mansoni and Schistosoma haematobium in China. A retrospective study was performed to review all information regarding the imported cases of schistosomiasis collected from published literature and the database of the National Notifiable Disease Report System from 1979 to 2019. The characterization of epidemiological and clinical features was analyzed. A total of 355 cases of imported schistosomiasis have been reported in 15 provinces (autonomous regions, municipalities) in China since 1979, including 78 cases of infection with S. mansoni (21.97%), 262 cases with S. haematobium (73.80%), and 15 cases with unidentified Schistosoma species. Eosinophilia was the most common sign of the infection with S. mansoni (91.03%). The parasitological findings were confirmed in 89.74% (70/78) of cases infected with S. mansoni and 32.06% (84/262) of cases infected with S. haematobium. There was no imported case of infection of Schistosoma japonicum, Schistosoma intercalatum, or Schistosoma mekongi reported in China during this period. Praziquantel is the best therapeutic drug for curing imported schistosomiasis. In addition, Biomphalaria straminea, the intermediate host of S. mansoni, has already been found in Guangdong province in south China. There is a rising risk that the existence of the intermediate host B. straminea and the imported cases of S. mansoni infection could cause the spread of the infections and make these endemic. Thus, better understanding of the clinical features and the transmission pattern of these Schistosoma infections would assist Chinese physicians in the diagnosis and treatment of these imported schistosomiasis cases.

Differential expression of microRNA between normally developed and underdeveloped female worms of Schistosoma japonicum

Eggs produced by bisexual infected mature female worms (MF) of Schistosoma japonicum are important in the transmission of the parasite and responsible for the pathogenesis of schistosomiasis. The single-sex infected female worms (SF) cannot mature and do not produce normal eggs; also they do not induce severe damage to the host. In this study, the microRNA (miRNA) expression profiles of 25d MF and 25d SF were investigated through Solexa deep-sequencing technology to explore the developmental mechanisms of schistosome female worms. There were 36 differentially expressed miRNA, 20 up-regulated and 16 down-regulated found in MF/SF worms, including some development related miRNA such as bantam (ban), let-7, miR-124, miR-8, miR-1, miR-7. There were 166 target genes of up-regulated miRNA and 201 target genes of down-regulated miRNA after comparing the target gene prediction software results with RNA-Seq transcriptome results. Analysis of the target genes shows that different ones are involved in MF and SF worms in Gene Ontology terms, with a similar situation in KEGG. This observation indicates that different genes regulated by differentially expressed miRNA take part in MF and SF and lead to differential sexual status. This means that the sexual status of female worms is regulated by miRNA.

Schistosomiasis infections in South African pregnant women: A review

Background

Schistosomiasis, a chronic parasitic disease caused by Schistosoma species, has a negative impact on pregnancy outcomes and child development. The disease affects over 230 million people worldwide, and in South Africa an estimated 5.2 million people are thought to be infected. However, there is scant data on the impact of schistosomiasis in pregnancy in South Africa and globally. The aim of this review was to analyse the current knowledge of schistosomiasis in pregnancy, particularly in South Africa, focusing on maternal and neonatal complications linked directly to the disease or its treatment.

Methods

An electronic search of online databases was used to identify and collect relevant research articles related to schistosomiasis in pregnancy, with a focus on South Africa.

Results

Schistosomiasis can cause severe organ damage when left untreated and influences maternal and foetal morbidity and mortality. Although South Africa's first helminth control programme was established in 1997, there is currently no ongoing treatment strategy programme, and little information is available on prevalence rates in pregnant women for the last 20 years. There is also an absence of data from well-controlled clinical trials that focus on the efficacy and safety of treatment during pregnancy, which has led to this vulnerable group being neglected.

Conclusion

This review highlights the dearth of information on the impact of schistosomiasis in pregnant women in South Africa and the need for high-quality evidence-based studies.

Schistosome TRP channels: An appraisal

Ion channels underlie electrical excitability in cells and are essential for a variety of functions, most notably neuromuscular and sensory activity. They are also validated targets for a preponderance of approved anthelmintic compounds. Transient receptor potential (TRP) channels constitute an ion channel superfamily whose members play important roles in sensory signaling, regulation of ion homeostasis, organellar trafficking, and other key cellular and organismal activities. Unlike most other ion channels, TRP channels are often polymodal, gated by a variety of mechanisms. Furthermore, TRP channels fall into several classes or subtypes based on sequence and structure. Until recently, there had been very little investigation of the properties and functions of TRP channels from parasitic helminths, including schistosomes, but that situation has changed in the past few years. Indeed, it is now clear that at least some schistosome TRP channels exhibit unusual pharmacological properties, and, intriguingly, both a mammalian and a schistosome TRP channel are activated by praziquantel, the current antischistosomal drug of choice. With the latest release of the Schistosoma mansoni genome database, several changes in predicted TRP channel sequences appeared, some of which were significant. This review updates and reassesses the TRP channel repertoire in S. mansoni, examines recent findings regarding these potential therapeutic targets, and provides guideposts for some of the physiological functions that may be mediated by these channels in schistosomes.

Three monthly doses of 60 mg/kg praziquantel for Schistosoma haematobium infection is a safe and effective treatment regimen

Background

Praziquantel (PZQ) is the standard treatment for Schistosomiasis in sub-Saharan Africa. However, there is evidence suggesting praziquantel treatment failure in Schistosome infections with associated potential renal impairment. The objective of this study was to determine the effect of three monthly doses of 60 mg/kg/day PZQ on schistosome egg count, liver and renal function during the treatment of urinary schistosomiasis in Ghana.

Methods

A nested case-control study was designed from a cohort screened for schistosomiasis; 28 schistosomiasis positive cases by microscopy matched with 53 healthy controls by age and gender. The study population was urban dwellers from the Asokwa sub-metropolitan area, Kumasi in Ghana. Participants were within the age range of 6 to 30 years. We assessed Schistosoma haematobium egg counts in urine and its associated impact on liver and renal function at baseline, treatment and post-treatment phases using serum.

Results

Of the 28 cases and 53 controls, 78.6% and 81.1% were males respectively. Globulin levels before treatment was higher in cases [36.7 (32.8, 40.1) vrs 30.5 (22.4, 33.8), p = 0.005] at pre-treatment but not at post-treatment [35.8 (31.2, 39.1) vrs 37.4 (29.7, 43.0), p = 0.767]. Estimated cure rate was 42.9, 46.4 and 96.4% after first, second and third dose respectively. Schistosome egg counts dropped significantly (p = 0.001) from before second dose to post-treatment. Similarly, levels of alanine aminotransferase (p = 0.001), aspartate aminotransferase (p = 0.028) and gamma glutamyl transferase (p = 0.001) significantly declined towards post-treatment. Estimated glomerular filtration rate significantly improved from before second dose to post-treatment using both the Chronic Kidney Disease Epidemiology Program (p = 0.001) and 4-variable Modification of Diet in Renal Disease (p = 0.002) equations.

Conclusion

Treatment of urinary Schistosoma hematobium infections with a repeated high monthly dose of 60 mg/kg of praziquantel for 3 months is safe and effective.

Role of the Pumilio gene in the reproductive system of Schistosoma japonicum

The elimination of schistosomiasis, a parasitic disease caused by Schistosoma and a major source of morbidity and mortality in developing countries, faces serious challenges. Although the pumilio protein regulates the reproductive organ development in many species, its role in Schistosoma japonicum is unknown. Thus, this study investigated the function of pumilio in S. japonicum reproduction. The complete coding sequences of S. japonicum Pumilio1 (SjPum1) and SjPum2 genes were cloned and characterized. The full-length open-reading frame SjPum1 (2613 nucleotides) and SjPum2 (4479 nucleotides) genes were obtained. Bioinformatics analysis showed that those genes belonged to the PUF (pumilio and FBF) family. Quantitative polymerase chain reaction analyses revealed that SjPum1 and SjPum2 were differentially expressed throughout the S. japonicum life cycle and were highly expressed in reproductive organs. In situ hybridization results showed that mRNA expression of SjPum2 was higher than that of SjPum1 in the ovary and testis. Knocking down SjPum2 using RNA interference techniques to explore potential reproductive functions showed that compared with the control (untransfected or scrambled mRNA-transfected) worms, the morphology of both male and female reproductive organs was altered, the number of eggs produced by paired females was significantly decreased, and the transcription levels of caspase 3 and caspase 7 genes related to apoptosis were significantly increased. The transcription level of Nanos1 gene which related to reproduction was also significantly increased. Therefore, SjPum2 may play a role in the reproductive development of S. japonicum.

The Proteasome as a Drug Target in the Metazoan Pathogen, Schistosoma mansoni

Proteases are fundamental to successful parasitism, including that of the schistosome flatworm parasite, which causes the disease schistosomiasis in 200 million people worldwide. The proteasome is receiving attention as a potential drug target for treatment of a variety of infectious parasitic diseases, but it has been understudied in the schistosome. Adult Schistosoma mansoni were incubated with 1 μM concentrations of the proteasome inhibitors bortezomib, carfilzomib, and MG132. After 24 h, bortezomib and carfilzomib decreased worm motility by more than 85% and endogenous proteasome activity by >75%, and after 72 h, they increased caspase activity by >4.5-fold. The association between the engagement of the proteasome target and the phenotypic and biochemical effects recorded encouraged the chromatographic enrichment of the S. mansoni proteasome (Sm20S). Activity assays with fluorogenic proteasome substrates revealed that Sm20S contains caspase-type (β1), trypsin-type (β2), and chymotrypsin-type (β5) activities. Sm20S was screened with 11 peptide epoxyketone inhibitors derived from the marine natural product carmaphycin B. Analogue 17 was 27.4-fold less cytotoxic to HepG2 cells than carmaphycin B and showed equal potency for the β5 subunits of Sm20S, human constitutive proteasome, and human immunoproteasome. However, this analogue was 13.2-fold more potent at targeting Sm20S β2 than it was at targeting the equivalent subunits of the human enzymes. Furthermore, 1 μM 17 decreased both worm motility and endogenous Sm20S activity by more than 90% after 24 h. We provide direct evidence of the proteasome's importance to schistosome viability and identify a lead for which future studies will aim to improve the potency, selectivity, and safety.

Differential gene expression, including Sjfs800, in Schistosoma japonicum females at pre-pairing, initial pairing and oviposition

Background

Schistosomiasis is a prevalent but neglected tropical disease caused by parasitic trematodes of the genus Schistosoma, with the primary disease-causing species being S. haematobium, S. mansoni and S. japonicum. Male–female pairing of schistosomes is necessary for sexual maturity and the production of a large number of eggs, which are primarily responsible for schistosomiasis dissemination and pathology.

Methods

Here, we used microarray hybridization, bioinformatics, quantitative PCR, in situ hybridization and gene silencing assays to identify genes that play critical roles in S. japonicum reproduction biology, particularly in vitellarium development, a process that affects male–female pairing, sexual maturation and subsequent egg production.

Results

Microarray hybridization analyses generated a comprehensive set of genes differentially transcribed before and after male–female pairing. Although the transcript profiles of females were similar 16 and 18 days after host infection, marked gene expression changes were observed at 24 days. The 30 most abundantly transcribed genes on day 24 included those associated with vitellarium development. Among these, the gene for female-specific 800 (fs800) was substantially upregulated. Our in situ hybridization results in female S. japonicum indicated that Sjfs800 mRNA was observed only in the vitellarium, localized in mature vitelline cells. Knocking down the Sjfs800 gene in female S. japonicum by approximately 60% reduced the number of mature vitelline cells, decreased rates of pairing and oviposition, and decreased the number of eggs produced in each male–female pairing by about 50%.

Conclusions

These results indicate that Sjfs800 may play a role in vitellarium development and egg production in S. japonicum and suggest that Sjfs800 regulation may provide a novel approach for the prevention or treatment of schistosomiasis.

Mapping evidence of the concomitant management of schistosomiasis by traditional health practitioners and health care professionals in communities with high prevalent infections: a systematic scoping review protocol

BACKGROUND

Schistosomiasis is one of the most prevalent parasitic diseases in low- and middle-income countries (LMICs), being regarded as a neglected tropical disease in sub-Saharan Africa. Praziquantel is the conventional treatment recommended for schistosomiasis in mainstream healthcare systems. In many poor settings, while many people reportedly use both traditional medicine and public sector mainstream healthcare systems, little is known if those infected with schistosomiasis use both African traditional and prescribed antischistosomal medicines. This review aims to map evidence of the concomitant management of schistosomiasis by traditional health practitioners (THPs) and health care professionals (HCPs) in communities with a high prevalence schistosomiasis infection in LMICs.

METHODS/DESIGN

Guided by Arksey and O'Malley scoping review framework and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we will map the evidence from relevant studies dating from 2007 to 2019 published in LMICs. An electronic keyword search of the following databases will be conducted: PubMed, Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and MEDLINE via EBSCOhost, Google Scholar, and WILEY online Library. Peer-reviewed articles, gray literature sources, and reference lists will be included to identify eligible studies. Following title screening, two reviewers will independently screen the abstracts and full texts. Any study that focuses on managing schistosomiasis will be included. The data will be analyzed using thematic analysis with the help of NVIVO software version 12, with the Mixed Method Appraisal Tool (MMAT) being used to assess the quality of the included studies.

DISCUSSION

This review will map the evidence in the literature of the concomitant management of schistosomiasis by THPs and HCPs in communities with a high prevalent infection in LMICs. The review findings will be important for policy makers across the healthcare continuum and be used to inform stakeholders' consensus process to explore the development of a generic set of patient-centered quality indicators that are applicable to multiple care settings. It will also identify research gaps in schistosomiasis management in LMICs and provide direction for future research. The results will be disseminated through a peer-reviewed publication and presented in relevant conferences.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017078198.

Activity and pharmacokinetics of a praziquantel crystalline polymorph in the Schistosoma mansoni mouse model

Schistosomiasis is a global disease of significant public health relevance. Only one racemic drug, praziquantel, characterized by low bioavailability, low water solubility and extensive first pass metabolism, is currently available. We studied a new praziquantel formulation (polymorph B), which is based on a racemic praziquantel crystalline polymorph (TELCEU01). Its in vitro activity was tested on newly transformed schistosomula (NTS) and adult Schistosoma mansoni. In vivo studies were conducted in mice harboring chronic S. mansoni infections. Pharmacokinetic (PK) profiles of R- and S-praziquantel and R- and S- polymorph B following oral administration with both formulations were generated by sampling mice at 30, 60, 240 min and 24 h post-treatment, followed by LC-MS/MS analysis. PK parameters were calculated using a non-compartmental analysis with a linear trapezoidal model. In vitro, commercial praziquantel and the polymorph B performed similarly on both NTS (IC₅₀ = 2.58 and 2.40 µg/mL at 72 h) and adults (IC₅₀ = 0.05 and 0.07 µg/mL at 72 h). Praziquantel showed higher in vivo efficacy with an ED₅₀ of 58.75 mg/kg compared to an ED₅₀ of 122.61 mg/kg for the polymorph B. The PK profiles of the two drugs exhibited differences: R-praziquantel showed an overall 40% higher area under the plasma drug concentration-time curve (AUC_0→24) (R-praziquantel = 3.42; R-polymorph B = 2.05 h*µg/mL) and an overall 30% lower apparent clearance (Cl/F) (R-praziquantel = 70.68 and R-polymorph B = 97.63 (mg)/(µg/mL)/h). Despite the lack of improved activity and PK properties of polymorph B against S. mansoni, here presented; research on pharmaceutical polymorphism remains a valid and cost-effective option for the development of new praziquantel formulations with enhanced properties such as increased solubility and/or dissolution.

Schistosoma mansoni venom allergen-like proteins: phylogenetic relationships, stage-specific transcription and tissue localization as predictors of immunological cross-reactivity

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The Schistosoma mansoni venom allergen-like (SmVAL) family relationships were investigated.

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Transcription patterns of SmVALs associate with phylogenetic relationships.

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There was clear antibody cross-reactivity between related native SmVAL proteins.

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SmVAL4, 10, 18 and 19 all localized via WISH to pre-acetabular glands of cercariae.

Schistosoma mansoni venom allergen-like proteins (SmVALs) are part of a diverse protein superfamily partitioned into two groups (group 1 and group 2). Phylogenetic analyses of group 1 SmVALs revealed that members could be segregated into subclades (A–D); these subclades share similar gene expression patterns across the parasite lifecycle and immunological cross-reactivity. Furthermore, whole-mount in situ hybridization demonstrated that the phylogenetically, transcriptionally and immunologically-related SmVAL4, 10, 18 and 19 (subclade C) were all localized to the pre-acetabular glands of immature cercariae. Our results suggest that SmVAL group 1 phylogenetic relationships, stage-specific transcriptional profiles and tissue localization are predictive of immunological cross-reactivity.

The ABL kinase inhibitor imatinib causes phenotypic changes and lethality in adult Schistosoma japonicum

Schistosomiasis caused by different species of schistosome parasites is one of the most debilitating helminthic diseases of humans worldwide. For decades, chemotherapy is the main method of controlling schistosomiasis. However, the fear of drug resistance has motivated the search for alternatives. It has been demonstrated that the ABL kinase inhibitor imatinib affected the development and survival of Schistosoma mansoni in vitro; however, there is still lack of information on whether imatinib also affects other schistosome species such as Schistosoma japonicum. In the present study, the anti-schistosomal potency of imatinib on adult S. japonicum was investigated in vitro, and the results showed that imatinib had a significant impact on various physiological processes of S. japonicum adult worms. Besides its negative effects on worm motility, pairing stability, and gonad development, imatinib caused pathological changes in the gastrodermis as well as the death of the parasite. Our findings suggest that imatinib is an intriguing candidate for further development as an option to fight S. japonicum.

TRP channels as potential targets for antischistosomals

Ion channels are membrane protein complexes that underlie electrical excitability in cells, allowing ions to diffuse through cell membranes in a regulated fashion. They are essential for normal functioning of the neuromusculature and other tissues. Ion channels are also validated targets for many current anthelmintics, yet the properties of only a small subset of ion channels in parasitic helminths have been explored in any detail. Transient receptor potential (TRP) channels comprise a widely diverse superfamily of ion channels with important roles in sensory signaling, regulation of ion homeostasis, organellar trafficking, and other functions. There are several subtypes of TRP channels, including TRPA1 and TRPV1 channels, both of which are involved in, among other functions, sensory, nociceptive, and inflammatory signaling in mammals. Several lines of evidence indicate that TRPA1-like channels in schistosomes exhibit pharmacological sensitivities that differ from their mammalian counterparts and that may signify unique physiological properties as well. Thus, in addition to responding to TRPA1 modulators, schistosome TRPA1-like channels also respond to compounds that in other organisms modulate TRPV1 channels. Notably, TRPV channel genes are not found in schistosome genomes. Here, we review the evidence leading to these conclusions and examine potential implications. We also discuss recent results showing that praziquantel, the current drug of choice against schistosomiasis, selectively targets host TRP channels in addition to its likely primary targets in the parasite. The results we discuss add weight to the notion that schistosome TRP channels are worthy of investigation as candidate therapeutic targets.

Accuracy of the WHO praziquantel dose pole for large-scale community treatment of urogenital schistosomiasis in northern Mozambique: Is it time for an update?

BACKGROUND

A pioneering strategy developed by the World Health Organization (WHO) for the control of schistosomiasis was the concept of a height-based dose pole to determine praziquantel (PZQ) dosing in large-scale treatment campaigns. However, some recent studies have shown variable accuracy for the dose pole in terms of predicting correct mg/Kg dosing, particularly for treatment of adults. According to the WHO, 91 million adults in 52 countries are targeted to be treated by 2020.

METHODS/PRINCIPAL FINDINGS

The present study aimed to test the accuracy of the dose pole in determining PZQ dosage by comparing the number of tablets determined by the dose pole with the number of tablets determined according to total body weight. The analysis included height-for-weight data from 9,827 school-aged children (SAC) and adults from 42 villages in the province of Cabo Delgado in Mozambique. The results revealed that of the 7,596 SAC, 91.8% has received an appropriate dose (30-60mg/Kg), 6% received an insufficient dose (<30mg/Kg) and 2% an excessive dose (> 60mg/Kg). On the other hand, 13.7% out of 2,231 adults were treated inaccurately with 13.5% receiving an insufficient dose and 0.2% an excessive dose. When the percentage of insufficient dosing was disaggregated by gender, the frequency of adult females who were underdosed reached 18.3% versus 10.8% of adult males. Of note, Adult females aged 21-55 years were found to have an underdose frequency of 21.3%, compared to 11.8% of adult males in the same age range. The performance of a proposed modified dose pole was compared using the same dataset of adult Mozambicans. The results showed that the modified dose pole reduced the underdose frequency among adults from 13.5% to 10.4%, and subsequently increased the percentage of optimal dosing from 33.7% to 45.3%.

CONCLUSIONS

Our findings highlight the need to update the WHO-dose pole to avoid administration of insufficient PZQ doses to adults and therefore minimize the potential emergence of PZQ-resistant strains.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial registry under ISRTC number 14117624.

Computationally-guided drug repurposing enables the discovery of kinase targets and inhibitors as new schistosomicidal agents

The development of novel therapeutics is urgently required for diseases where existing treatments are failing due to the emergence of resistance. This is particularly pertinent for parasitic infections of the tropics and sub-tropics, referred to collectively as neglected tropical diseases, where the commercial incentives to develop new drugs are weak. One such disease is schistosomiasis, a highly prevalent acute and chronic condition caused by a parasitic helminth infection, with three species of the genus Schistosoma infecting humans. Currently, a single 40-year old drug, praziquantel, is available to treat all infective species, but its use in mass drug administration is leading to signs of drug-resistance emerging. To meet the challenge of developing new therapeutics against this disease, we developed an innovative computational drug repurposing pipeline supported by phenotypic screening. The approach highlighted several protein kinases as interesting new biological targets for schistosomiasis as they play an essential role in many parasite’s biological processes. Focusing on this target class, we also report the first elucidation of the kinome of Schistosoma japonicum, as well as updated kinomes of S. mansoni and S. haematobium. In comparison with the human kinome, we explored these kinomes to identify potential targets of existing inhibitors which are unique to Schistosoma species, allowing us to identify novel targets and suggest approved drugs that might inhibit them. These include previously suggested schistosomicidal agents such as bosutinib, dasatinib, and imatinib as well as new inhibitors such as vandetanib, saracatinib, tideglusib, alvocidib, dinaciclib, and 22 newly identified targets such as CHK1, CDC2, WEE, PAKA, MEK1. Additionally, the primary and secondary targets in Schistosoma of those approved drugs are also suggested, allowing for the development of novel therapeutics against this important yet neglected disease.

The rise of resistance through the intensive use of drugs targeted to treat specific infectious diseases means that new therapeutics are continually required. Diseases common in the tropics and sub-tropics, classified as neglected tropical diseases, suffer from a lack of new drug treatments due to the difficulty in developing new drugs and the lack of market incentive. One such disease is schistosomiasis, a major human helminth disease caused by worms from the genus Schistosoma. It is currently treated by a 40-year old drug, praziquantel, but its widespread use has led to signs of drug-resistance emerging, with no alternative effective treatments available. To meet this challenge, we have developed an innovative computational drug repurposing pipeline supported by experimental phenotypic screening. Protein kinases emerged from our pipeline as interesting new biological targets. Given that many human kinase inhibitors have been successfully applied specially in cancer therapy and kinases have conserved structures and functions, we also undertook a detailed analysis of the kinases present in all infective Schistosoma species and human host. This allowed identification of new Schistosoma-specific kinase targets and suggest approved drugs to be used for treating schistosomiasis as well as opening new avenues to treat this neglected disease.

Application of Dendrimers for the Treatment of Infectious Diseases

Dendrimers are drug delivery systems that are characterized by a three-dimensional, star-shaped, branched macromolecular network. They possess ideal properties such as low polydispersity index, biocompatibility and good water solubility. They are made up of the interior and the exterior layers. The exterior layer consists of functional groups that are useful for conjugation of drugs and targeting moieties. The interior layer exhibits improved drug encapsulation efficiency, reduced drug toxicity, and controlled release mechanisms. These unique properties make them useful for drug delivery. Dendrimers have attracted considerable attention as drug delivery system for the treatment of infectious diseases. The treatment of infectious diseases is hampered severely by drug resistance. Several properties of dendrimers such as their ability to overcome drug resistance, toxicity and control the release mechanism of the encapsulated drugs make them ideal systems for the treatment of infectious disease. The aim of this review is to discuss the potentials of dendrimers for the treatment of viral and parasitic infections.

A Novel Class of Schistosoma mansoni Histone Deacetylase 8 (HDAC8) Inhibitors Identified by Structure-Based Virtual Screening and In Vitro Testing

A promising means in the search of new small molecules for the treatment of schistosomiasis (amongst other parasitic ailments) is by targeting the parasitic epigenome. In the present study, a docking based virtual screening procedure using the crystal structure of histone deacetylase 8 from Schistosoma mansoni (smHDAC8) was designed. From the developed screening protocol, we were able to identify eight novel N-(2,5-dioxopyrrolidin-3-yl)-n-alkylhydroxamate derivatives as smHDAC8 inhibitors with IC₅₀ values ranging from 4.4-20.3 µM against smHDAC8. These newly identified inhibitors were further tested against human histone deacetylases (hsHDAC1, 6 and 8), and were found also to be exerting interesting activity against them. In silico prediction of the docking pose of the compounds was confirmed by the resolved crystal structure of one of the identified hits. This confirmed these compounds were able to chelate the catalytic zinc ion in a bidentate fashion, whilst showing an inverted binding mode of the hydroxamate group when compared to the reported smHDAC8/hydroxamates crystal structures. Therefore, they can be considered as new potential scaffold for the development of new smHDAC8 inhibitors by further investigation of their structure-activity relationship.

Impact of treatment with a Protein Tyrosine Kinase Inhibitor (Genistein) on acute and chronic experimental Schistosoma mansoni infection

Schistosomiasis mansoni is considered one of the most common fibrotic diseases resulting from inflammation and deposition of fibrous tissue around parasitic eggs trapped in the liver, causing morbidity and mortality. Chemotherapy against schistosomiasis is largely dependent on Praziquantel (PZQ). Yet, the huge administration of it in endemic areas and its incompetence towards the immature stages have raised serious alarms against the development of drug resistance. Few drugs are directed to reverse schistosomal liver fibrosis, particularly at the chronic and advanced stages of the disease. Recently, protein tyrosine kinase (PTK) inhibitors have been identified as potent anti-schistosomal and anti-fibrotic drugs against schistosomes, that may suppress and reverse Schistosoma mansoni (S. mansoni) induced liver fibrosis. The present study was designed to assess the anti-schistosomal and antifibrotic activity of Genistein, a PTK inhibitor, in comparison to PZQ, on both acute and chronic S. mansoni-infected mice using different parasitological, histopathological and immunohistochemical studies. Genistein showed a significant reduction (P < .05) in total worm burden, tissue egg load, mean hepatic granulomas diameter and numbers, percentage of collagen and expression of transforming growth factor-beta 1 (TGF-β 1) in the examined hepatocytes with elevation in percentage of degenerated ova, in comparison to the control groups, in both acute and chronic stages of infection. The best results were obtained when Genistein was combined with PZQ. Therefore, it was concluded that Genistein showed a promising anti-schistosomal and anti-fibrotic properties which could make it one of the new potential targets in chemotherapy against schistosomiasis.

The RIO protein kinase-encoding gene Sj-riok-2 is involved in key reproductive processes in Schistosoma japonicum

Background

Schistosomiasis is one of the most prevalent parasitic diseases worldwide and is caused by parasitic trematodes of the genus Schistosoma. The pathogenesis of schistosomiasis is caused by eggs whose production is the consequence of the pairing of schistosomes and the subsequent sexual maturation of the female. Previous studies have demonstrated that protein kinases are involved in processes leading to the male-induced differentiation of the female gonads, ovary and vitellarium. Right open reading frame protein kinase 2 (RIOK-2) is a member of the atypical kinase family and shown in other organisms to be responsible for ribosomal RNA biogenesis and cell-cycle progression, as well as involves in nematode development. However, nothing is known about its functions in any trematode including schistosome.

Methods

We isolated and characterized the riok-2 gene from S. japonicum, and detected the transcriptional profiles of Sj-riok-2 by using real-time PCR and in situ hybridization. RNAi-mediated knockdown of Sj-riok-2 was performed, mitotic activities were detected by EdU incorporation assay and morphological changes on organs were observed by confocal laser scanning microscope (CLSM).

Results

In silico analyses of the amino acid sequence of Sj-RIOK-2 revealed typical features of this class of kinases including a winged helix (wHTH) domain and a RIO kinase domain. Sj-riok-2 is transcribed in different developmental stages of S. japonicum, with a higher abundance in adult females and eggs. Localization studies showed that Sj-riok-2 was mainly transcribed in female reproductive organs. Experiments with adult schistosomes in vitro demonstrated that the transcriptional level of Sj-riok-2 was affected by pairing. Knocking down Sj-riok-2 by RNAi reduced cell proliferation in the vitellarium and caused the increased amount of mature oocytes in ovary and an accumulation of eggs within the uterus.

Conclusions

Sj-riok-2 is involved in the reproductive development and maturation of female S. japonicum. Our findings provide first evidence for a pairing-dependent role of Sj-riok-2 in the reproductive development and maturation of female S. japonicum. Thus this study contributes to the understanding of molecular processes controlling reproduction in schistosomes.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2524-7) contains supplementary material, which is available to authorized users.

Detection of duo-schistosome infection from filtered urine samples from school children in Zambia after MDA

Schistosomiasis is one of the major Neglected Tropical Diseases (NTDs) in sub-Saharan Africa. In sub-Saharan Africa, two major human schistosome species namely Schistosoma mansoni and S. haematobium often occur sympatrically largely affecting children. Recognizing the public health impact of Schistosomiasis, the World Health Organization (WHO) is urging member states to regularly treat at least 75% and up to 100%, of all school-aged children at risk of morbidity. For control strategies based on targeted mass drug administration (MDA) to succeed it is essential to have a simple and sensitive test for monitoring the success of these interventions. Current available diagnostic tests, such as egg detection in stool by Kato-Katz (KK) for S. mansoni and detection of eggs or blood (hematuria) in urine for S. haematobium have reduced sensitivity in low intensity settings. The objective of the study was to evaluate active single or duo schistosome infections in school children following MDA using molecular diagnostics (PCR) on filtered urine samples and comparing that against traditional diagnostic tests. This cross-sectional study was conducted among 111 school children aged 7–15 years in Chongwe and Siavonga Districts in Zambia. Species-specific cell-free repeat DNA fragment were amplified from 111 filtered urine samples. Our approach detected eight times more positive cases (total 77) than by KK (9) for S. mansoni and six times more (total 72) than by hematuria (11) for S. haematobium and even more against urine filtration (77 compared to only 6). The same pattern was observed when stratified for age group and sex specific analysis with 100% sensitivity and specificity devoid of any cross amplification. In addition, 69 individuals (62%) were co-infected by both parasites. We have demonstrated a significantly higher prevalence of both species than indicated by the traditional tests and the persistent maintenance of reservoir of infection after MDA. Our approach is an effective means of detecting low intensity infection, which will enhance the effectiveness of surveillance and assess the impact of MDA control programs against schistosomiasis.

Schistosomiasis: Drugs used and treatment strategies

Neglected tropical diseases (NTDs) affect millions of people in different geographic regions, especially the poorest and most vulnerable. Currently NTDs are prevalent in 149 countries, seventeen of these neglected tropical parasitic diseases are classified as endemic. One of the most important of these diseases is schistosomiasis, also known as bilharzia, a disease caused by the genus Schistosoma. It presents several species, such as Schistosoma haematobium, Schistosoma japonicum and Schistosoma mansoni, the latter being responsible for parasitosis in Brazil. Contamination occurs through exposure to contaminated water in the endemic region. This parasitosis is characterized by being initially asymptomatic, but it is able to evolve into more severe clinical forms, potentially causing death. Globally, more than 200 million people are infected with one of three Schistosome species, including an estimated 40 million women of reproductive age. In Brazil, about 12 million children require preventive chemotherapy with anthelmintic. However, according to the World Health Organization (WHO), only about 15% of the at-risk children receive regular treatment. The lack of investment by the pharmaceutical industry for the development and/or improvement of new pharmaceutical forms, mainly aimed at the pediatric public, is a great challenge. Currently, the main forms of treatment used for schistosomiasis are praziquantel (PZQ) and oxaminiquine (OXA). PZQ is the drug of choice because it presents as a high-spectrum anthelmintic, used in the treatment of all known species of schistosomiasis and some species of cestodes and trematodes. OXA, however, is not active against the three Schistosome species. This work presents a literature review regarding schistosomiasis. It addresses points such as available treatments, the role of the pharmaceutical industry against neglected diseases, and perspectives for treatment.

Comparative Analysis of Proteome-Wide Lysine Acetylation in Juvenile and Adult Schistosoma japonicum

Schistosomiasis is a devastating parasitic disease caused by tremotodes of the genus Schistosoma. Eggs produced by sexually mature schistosomes are the causative agents of for pathogenesis and transmission. Elucidating the molecular mechanism of schistosome development and sexual maturation would facilitate the prevention and control of schistosomiasis. Acetylation of lysine is a dynamic and reversible post-translational modification playing keys role in many biological processes including development in both eukaryotes and prokaryotes. To investigate the impacts of lysine acetylation on Schistosoma japonicum (S. japonicum) development and sexual maturation, we used immunoaffinity-based acetyllysine peptide enrichment combined with mass spectrometry (MS), to perform the first comparative analysis of proteome-wide lysine acetylation in both female and male, juvenile (18 days post infection, 18 dpi) and adult (28 dpi) schistosome samples. In total, we identified 874 unique acetylated sites in 494 acetylated proteins. The four samples shared 47 acetylated sites and 46 proteins. More acetylated sites and proteins shared by both females and males were identified in 28 dpi adults (189 and 143, respectively) than in 18 dpi schistosomula (76 and 59, respectively). More stage-unique acetylated sites and proteins were also identified in 28 dpi adults (494 and 210, respectively) than in 18 dpi schistosomula (73 and 44, respectively). Functional annotation showed that in different developmental stages and genders, a number of proteins involving in muscle movement, glycometabolism, lipid metabolism, energy metabolism, environmental stress resistance, antioxidation, etc., displayed distinct acetylation profiles, which was in accordance with the changes of their biological functions during schistosome development, suggesting that lysine acetylation modification exerted important regulatory roles in schistosome development. Taken together, our data provided the first comparative global survey of lysine acetylation in juvenile and adult S. japonicum, which would deepen our understanding of the molecular mechanism of schistosome development and sexual maturation, and provide clues for the development of new anti-schistosome strategies.

Ultrastructural alterations in Schistosoma mansoni juvenile and adult male worms after in vitro incubation with primaquine

BACKGROUND

Praziquantel has been cited as the only drug for treating schistosomiasis. However, concerns over drug resistance have encouraged the search for novel drug leads. The antimalarial drug primaquine possesses interesting anti-schistosmal properties.

OBJECTIVES

This study is the first to document the potential role of primaquine as a schistosomicide and the ultrastructural changes induced by primaquine on juvenile or adult male worms of Schistosoma mansoni.

METHODS

Ultrastructural alterations in the tegumental surface of 21-day-old juvenile and adult male worms of S. mansoni were demonstrated following primaquine treatment at different concentrations (2, 5, 10, 15, and 20 µg/mL) and incubation periods (1, 3, 6, 24, and 48 h) in vitro, using both scanning and transmission electron microscopy.

FINDINGS

At low concentrations (2, 5, and 10 µg/mL) both juvenile and adult male worms were alive after 24 h of incubation, whereas contraction, paralysis, and death of all worms were observed after 24 h of drug exposure at 20 µg/mL. The tegument of juvenile and adult male worms treated with primaquine exhibited erosion, peeling, and sloughing. Furthermore, extensive damage of both tegumental and subtegumental layers included embedded spines, and shrinkage of muscles with vacuoles. The in vitro results confirmed that primaquine has dose-dependent effects with 20 µg/mL as the most effective concentration in a short incubation period.

MAIN CONCLUSIONS

The schistosomicidal activity of primaquine indicates that this drug possesses moderate in vitro activity against juvenile and adult male worms, since it caused high mortality and tegumental alterations. This study confirmed that the antimalarial drug primaquine possesses anti-schistosomal activity. Further investigation is needed to elucidate its mechanism of action.

Genome-wide miRNAs expression profiles of Schistosoma japonicum schistosomula in response to artesunate

Aim: miRNAs play a significant role in pharmacogenomics and are likely to be important in the molecular mechanism of atesunate (ART) effects on Schistosoma japonicum. Methods: We sequenced the RNAs using an Illumina (Solexa) DNA sequencer and compared the relative expression levels of the miRNAs in 10-day-old schistosomula from ART and the parallel control group. Results: We characterized 95 known miRNAs from S. japonicum schistosomula individuals, including 38 novel miRNA families. Among the detectable 134 miRNAs differentially expressed (>2.0-fold change, p < 0.01) after ART treatment in schistosomula, a total of seven known or novel 3p- or 5p- derived S. japonicum miRNAs were characterized. We propose that sja-miR-125b may regulate the expression of ART metabolizing enzymes, glutathione synthetase or heme-binding protein 2 to help S. japonicum resists or adapts to drug stress and also ART may significantly inhibit sexual maturation of female worms mediated by mir-71b/2 miRNA cluster. Conclusion: This was the first comprehensive miRNAs expression profile analysis of S. japonicum in response to ART, and provides an overview of the complex network of the mechanism of action of ART on S. japonicum.

SmShb, the SH2-Containing Adaptor Protein B of Schistosoma mansoni Regulates Venus Kinase Receptor Signaling Pathways

Venus kinase receptors (VKRs) are invertebrate receptor tyrosine kinases (RTKs) formed by an extracellular Venus Fly Trap (VFT) ligand binding domain associated via a transmembrane domain with an intracellular tyrosine kinase (TK) domain. Schistosoma mansoni VKRs, SmVKR1 and SmVKR2, are both implicated in reproductive activities of the parasite. In this work, we show that the SH2 domain-containing protein SmShb is a partner of the phosphorylated form of SmVKR1. Expression of these proteins in Xenopus oocytes allowed us to demonstrate that the SH2 domain of SmShb interacts with the phosphotyrosine residue (pY979) located in the juxtamembrane region of SmVKR1. This interaction leads to phosphorylation of SmShb on tyrosines and promotes SmVKR1 signaling towards the JNK pathway. SmShb transcripts are expressed in all parasite stages and they were found in ovary and testes of adult worms, suggesting a possible colocalization of SmShb and SmVKR1 proteins. Silencing of SmShb in adult S. mansoni resulted in an accumulation of mature sperm in testes, indicating a possible role of SmShb in gametogenesis.

TRP channels in schistosomes

Praziquantel (PZQ) is effectively the only drug currently available for treatment and control of schistosomiasis, a disease affecting hundreds of millions of people worldwide. Many anthelmintics, likely including PZQ, target ion channels, membrane protein complexes essential for normal functioning of the neuromusculature and other tissues. Despite this fact, only a few classes of parasitic helminth ion channels have been assessed for their pharmacological properties or for their roles in parasite physiology. One such overlooked group of ion channels is the transient receptor potential (TRP) channel superfamily. TRP channels share a common core structure, but are widely diverse in their activation mechanisms and ion selectivity. They are critical to transducing sensory signals, responding to a wide range of external stimuli. They are also involved in other functions, such as regulating intracellular calcium and organellar ion homeostasis and trafficking. Here, we review current literature on parasitic helminth TRP channels, focusing on those in schistosomes. We discuss the likely roles of these channels in sensory and locomotor activity, including the possible significance of a class of TRP channels (TRPV) that is absent in schistosomes. We also focus on evidence indicating that at least one schistosome TRP channel (SmTRPA) has atypical, TRPV1-like pharmacological sensitivities that could potentially be exploited for future therapeutic targeting.

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We provide an overview of transient receptor potential (TRP) channels in schistosomes and other parasitic helminths.

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TRP channels are important for sensory signaling, ion homeostasis, organellar trafficking, and a host of other functions.

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Very little work has been done on TRP channels in parasitic helminths.

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TRPV channels, found throughout the Metazoa, appear not to be present in parasitic platyhelminths.

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TRP channels in schistosomes appear to have atypical pharmacology, perhaps an entrée for therapeutic targeting.

MicroRNAs Are Involved in the Regulation of Ovary Development in the Pathogenic Blood Fluke Schistosoma japonicum

Schistosomes, blood flukes, are an important global public health concern. Paired adult female schistosomes produce large numbers of eggs that are primarily responsible for the disease pathology and critical for dissemination. Consequently, understanding schistosome sexual maturation and egg production may open novel perspectives for intervening with these processes to prevent clinical symptoms and to interrupt the life-cycle of these blood-flukes. microRNAs (miRNAs) are key regulators of many biological processes including development, cell proliferation, metabolism, and signal transduction. Here, we report on the identification of Schistosoma japonicum miRNAs using small RNA deep sequencing in the key stages of male-female pairing, gametogenesis, and egg production. We identified 38 miRNAs, including 10 previously unknown miRNAs. Eighteen of the miRNAs were differentially expressed between male and female schistosomes and during different stages of sexual maturation. We identified 30 potential target genes for 16 of the S. japonicum miRNAs using antibody-based pull-down assays and bioinformatic analyses. We further validated some of these target genes using either in vitro luciferase assays or in vivo miRNA suppression experiments. Notably, suppression of the female enriched miRNAs bantam and miR-31 led to morphological alteration of ovaries in female schistosomes. These findings uncover key roles for specific miRNAs in schistosome sexual maturation and egg production.

Quantitative proteomic analyses of Schistosoma japonicum in response to artesunate

Artesunate (ART) has high prophylactic efficacy against Schistosoma japonicum infections and has been used to treat and prevent schistosomiasis in China since 1995. However, the molecular mechanism of ART's effects on S. japonicum remains unclear. Herein, we applied isobaric tagging reagents for relative and absolute quantification analyses coupled with two-dimensional liquid chromatography and tandem mass spectrometry to investigate the effect of ART on the proteome of S. japonicum in susceptible mice. 4529 proteins were quantified on the basis of 21,825 unique peptides. Comparative proteomic analyses revealed that 145, 228 and 185 proteins were significantly differentially expressed after ART treatment in schistosomula, juvenile and adult worms, respectively. Ninety proteins were differentially expressed between each two treatment groups in response to ART treatment: 67 proteins were associated with S. japonicum development/aging and 23 were specifically associated with ART treatment. Quantitative real-time PCR of selected genes verified the proteomic data. Gene ontology annotation and Kyoto encyclopedia of genes and genomes pathway mapping analysis showed that the majority of differentially expressed proteins were involved in stress/defense/detoxification, signal transduction, carbohydrate metabolism, amino acid metabolism, transcription/translation, and protein synthesis/assembly/degradation. Thirty-four of the proteins differentially expressed under ART treatment encoded hypothetical, uncharacterized proteins with unknown functions. This study obtained the first comprehensive protein expression profile of S. japonicum in response to ART, and provides a basis for a better understanding of the molecular mechanisms of ART effects on S. japonicum.