Schistosomiasis

Long Non-Coding RNA Levels Are Modulated in Schistosoma mansoni following In Vivo Praziquantel Exposure

Schistosomiasis is a disease caused by trematodes of the genus Schistosoma that affects over 200 million people worldwide. For decades, praziquantel (PZQ) has been the only available drug to treat the disease. Despite recent discoveries that identified a transient receptor ion channel as the target of PZQ, schistosome response to this drug remains incompletely understood, since effectiveness relies on other factors that may trigger a complex regulation of parasite gene expression. Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with low or no protein-coding potential that play important roles in S. mansoni homeostasis, reproduction, and fertility. Here, we show that in vivo PZQ treatment modulates lncRNA levels in S. mansoni. We re-analyzed public RNA-Seq data from mature and immature S. mansoni worms treated in vivo with PZQ and detected hundreds of lncRNAs differentially expressed following drug exposure, many of which are shared among mature and immature worms. Through RT-qPCR, seven out of ten selected lncRNAs were validated as differentially expressed; interestingly, we show that these lncRNAs are not adult worm stage-specific and are co-expressed with PZQ-modulated protein-coding genes. By demonstrating that parasite lncRNA expression levels alter in response to PZQ, this study unravels an important step toward elucidating the complex mechanisms of S. mansoni response to PZQ.

Schistosoma mansoni phosphoglycerate mutase: a glycolytic ectoenzyme with thrombolytic potential

Schistosomiasis is a debilitating parasitic disease caused by intravascular flatworms called schistosomes (blood flukes) that affects >200 million people worldwide. Proteomic analysis has revealed the surprising presence of classical glycolytic enzymes – typically cytosolic proteins – located on the extracellular surface of the parasite tegument (skin). Immunolocalization experiments show that phosphoglycerate mutase (PGM) is widely expressed in parasite tissues and is highly expressed in the tegument. We demonstrate that live Schistosoma mansoni parasites express enzymatically active PGM on their tegumental surface. Suppression of PGM using RNA interference (RNAi) diminishes S. mansoni PGM (SmPGM) gene expression, protein levels, and surface enzyme activity. Sequence comparisons place SmPGM in the cofactor (2,3-bisphosphoglycerate)-dependent PGM (dPGM) family. We have produced recombinant SmPGM (rSmPGM) in an enzymatically active form in Escherichia coli. The Michaelis-Menten constant (K_m) of rSmPGM for its glycolytic substrate (3-phosphoglycerate) is 0.85 mM ± 0.02. rSmPGM activity is inhibited by the dPGM-specific inhibitor vanadate. Here, we show that rSmPGM not only binds to plasminogen but also promotes its conversion to an active form (plasmin) in vitro. This supports the hypothesis that host-interactive tegumental proteins (such as SmPGM), by enhancing plasmin formation, may help degrade blood clots around the worms in the vascular microenvironment and thus promote parasite survival in vivo.

Multifunctional Roles of MicroRNAs in Schistosomiasis

Schistosomiasis is a parasitic disease that is caused by helminths of the genus Schistosoma. The dioecious schistosomes mate and lay eggs after undergoing a complex life cycle. Schistosome eggs are mostly responsible for the transmission of schistosomiasis and chronic fibrotic disease induced by egg antigens is the main cause of the high mortality rate. Currently, chemotherapy with praziquantel (PZQ) is the only effective treatment against schistosomiasis, although the potential of drug resistance remains a concern. Hence, there is an urgent demand for new and effective strategies to combat schistosomiasis, which is the second most prevalent parasitic disease after malaria. MicroRNAs (miRNAs) are small non-coding RNAs that play pivotal regulatory roles in many organisms, including the development and sexual maturation of schistosomes. Thus, miRNAs are potential targets for treatment of schistosomiasis. Moreover, miRNAs can serve as multifunctional “nano-tools” for cross-species delivery in order to regulate host-parasite interactions. In this review, the multifunctional roles of miRNAs in the growth and development of schistosomes are discussed. The various regulatory functions of host-derived and worm-derived miRNAs on the progression of schistosomiasis are also thoroughly addressed, especially the promotional and inhibitory effects on schistosome-induced liver fibrosis. Additionally, the potential of miRNAs as biomarkers for the diagnosis and treatment of schistosomiasis is considered.

Transmission Dynamics of Schistosoma haematobium among School-Aged Children: A Cohort Study on Prevalence, Reinfection and Incidence after Mass Drug Administration in the White Nile State of Sudan

The reinfection rate of schistosomiasis after mass drug administration (MDA) has not been documented in Sudan. We aimed to explore the transmission dynamics of urogenital schistosomiasis after MDA, targeting school-aged children in the White Nile State of Sudan, assessing the prevalence, reinfection rate, and incidence. A single dose of praziquantel (40 mg/kg) was administered to 1951 students in five primary schools from January to February 2018 immediately after a baseline survey, and follow-up surveys were performed at 2 weeks and 6 months after treatment. We examined Schistosoma haematobium eggs by centrifugation methods. The overall reinfection rate at 6 months after treatment was 9.8% (95% confidence interval: 0.5-17.4%). By school, the reinfection rate was highest in the Al Hidaib school, whose prevalence was highest at baseline. The reinfection rate was significantly higher in high-infection areas than low-infection areas (p = 0.02). Of the prevalence at 6 months in high-infection areas, 41% of cases were due to reinfection. MDA interventions are decided upon and undertaken at the district level. A more targeted treatment strategy should be developed with a particular focus on tracking high-risk groups, even within a school or a community.

First morphogenetic analysis of parasite eggs from Schistosomiasis haematobium infected sub-Saharan migrants in Spain and proposal for a new standardised study methodology

Schistosomiasis is a Neglected Tropical Disease caused by trematode species of the genus Schistosoma. Both, autochthonous and imported cases of urogenital schistosomiasis have been described in Europe. The present study focuses on eggs, considered pure S. haematobium by genetic characterisation (intergenic ITS region of the rDNA and cox1 mtDNA). A phenotypic characterisation of S. haematobium eggs was made by morphometric comparison with experimental populations of S. bovis and S. mansoni, to help in the diagnosis of S. haematobium populations infecting sub-Saharan migrants in Spain. Analyses were made by Computer Image Analysis System (CIAS) applied on the basis of new standardised measurements and geometric morphometric tools. The principal component analysis (PCA), including seventeen non-redundant measurements, showed three phenotypic patterns in eggs of S. haematobium, S. bovis and S. mansoni. PCA showed that the S. bovis population presented a large egg size range with a pronouncedly larger maximum size. Similarly, S. bovis shows bigger spine values than S. haematobium. Mahalanobis distances between each pair of groups were calculated for each discriminant analysis performed. In general, S. mansoni and S. bovis present larger distances between them than with S. haematobium, i.e. they present the greatest differences. Regarding the spine, S. haematobium and S. mansoni are the most distant species. Results show the usefulness of this methodology for the phenotypic differentiation between eggs from these Schistosoma species, capable of discerning morphologically close eggs, as is the case of the haematobium group. Schistosoma egg phenotyping approaches may be applied to assess not only hybrid forms but also potential influences of a variety of other factors.

Assessment of reference genes at six different developmental stages of Schistosoma mansoni for quantitative RT-PCR

Reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR) is the most used, fast, and reproducible method to confirm large-scale gene expression data. The use of stable reference genes for the normalization of RT-qPCR assays is recognized worldwide. No systematic study for selecting appropriate reference genes for usage in RT-qPCR experiments comparing gene expression levels at different Schistosoma mansoni life-cycle stages has been performed. Most studies rely on genes commonly used in other organisms, such as actin, tubulin, and GAPDH. Therefore, the present study focused on identifying reference genes suitable for RT-qPCR assays across six S. mansoni developmental stages. The expression levels of 25 novel candidates that we selected based on the analysis of public RNA-Seq datasets, along with eight commonly used reference genes, were systematically tested by RT-qPCR across six developmental stages of S. mansoni (eggs, miracidia, cercariae, schistosomula, adult males and adult females). The stability of genes was evaluated with geNorm, NormFinder and RefFinder algorithms. The least stable candidate reference genes tested were actin, tubulin and GAPDH. The two most stable reference genes suitable for RT-qPCR normalization were Smp_101310 (Histone H4 transcription factor) and Smp_196510 (Ubiquitin recognition factor in ER-associated degradation protein 1). Performance of these two genes as normalizers was successfully evaluated with females maintained unpaired or paired to males in culture for 8 days, or with worm pairs exposed for 16 days to double-stranded RNAs to silence a protein-coding gene. This study provides reliable reference genes for RT-qPCR analysis using samples from six different S. mansoni life-cycle stages.

In vivo Therapeutic Effects and Mechanisms of Hydroxyasiaticoside Combined With Praziquantel in the Treatment of Schistosomiasis Induced Hepatic Fibrosis

Schistosomiasis has been a fatal obstinate disease that threatens global human health, resulting in the granulomatous inflammation and liver fibrosis. Objective:The aim of this study was to evaluate the therapeutic effects and mechanisms of hydroxyasiaticoside combined with praziquantel in the treatment of schistosomiasis-induced liver fibrosis. Methods:Mice were randomly distributed into four experimental groups: normal control group, model group, praziquantel group, praziquantel + hydroxyasiaticoside group. Except for the normal control group, they were infected with Schistosomia cercariae through the abdominal skin to induce liver fibrosis. In the intervention group, mice were administered with the respective drugs by gavage after 8 weeks of infection. At the end of the treatment, mice were sacrificed to collect blood for the determination of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) serum levels. Moreover, the liver was excised, weighed, and liver indices were calculated. Histopathological examination was performed to assess liver morphology. Besides, the expression of collagen type I and III in liver was determined; the mRNA expression levels of IL-6 and TNF-α in liver tissues were measured using Real-time PCR while ELISA and western blotting were performed on liver tissue homogenate to determine the protein expression of IL-6 and TNF-α. Results:The combination of praziquantel and hydroxyasiaticoside lowered the pathological scores of schistosomiasis-induced hepatic fibrosis, the liver indice, serum AST and ALT levels, improved liver morphology, downregulated the expression levels of hepatic type I and III collagen, inhibited the mRNA expression levels of pro-inflammatory factors (IL-6 and TNF-α) in the liver of mice relative to the praziquantel alone. Conclusion:The combination of hydroxyasiaticoside and praziquantel is a potential therapeutic option for schistosomiasis-induced hepatic fibrosis. Notably, this combination noticeably suppresses the protein and mRNA expression levels of pro-inflammatory factors (TNF-α and IL-6) in the liver.

RNA sequencing analysis of altered expression of long noncoding RNAs associated with Schistosoma japonicum infection in the murine liver and spleen

BACKGROUND

Schistosomiasis is a chronic, debilitating infectious disease caused by members of the genus Schistosoma. Previous findings have suggested a relationship between infection with Schistosoma spp. and alterations in the liver and spleen of infected animals. Recent reports have shown the regulatory role of noncoding RNAs, such as long noncoding RNAs (lncRNAs), in different biological processes. However, little is known about the role of lncRNAs in the mouse liver and spleen during Schistosoma japonicum infection.

METHODS

In this study, we identified and investigated lncRNAs using standard RNA sequencing (RNA-Seq). The biological functions of the altered expression of lncRNAs and their target genes were predicted using bioinformatics. Ten dysregulated lncRNAs were selected randomly and validated in reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) experiments.

RESULTS

Our study identified 29,845 and 33,788 lncRNAs from the liver and spleen, respectively, of which 212 were novel lncRNAs. We observed that 759 and 789 of the lncRNAs were differentially expressed in the respective organs. The RT-qPCR results correlated well with the sequencing data. In the liver, 657 differentially expressed lncRNAs were predicted to target 2548 protein-coding genes, whereas in the spleen 660 differentially expressed lncRNAs were predicted to target 2673 protein-coding genes. Moreover, functional annotation showed that the target genes of the differentially expressed lncRNAs were associated with cellular processes, metabolic processes, and binding, and were significantly enriched in metabolic pathways, the cell cycle, ubiquitin-mediated proteolysis, and pathways in cancer.

CONCLUSIONS

Our study showed that numerous lncRNAs were differentially expressed in S. japonicum-infected liver and spleen compared to control liver and spleen; this suggested that lncRNAs may be involved in pathogenesis in the liver and spleen during S. japonicum infection.

Surveillance on schistosomiasis in five provincial-level administrative divisions of the People's Republic of China in the post-elimination era

Background

The People’s Republic of China (P. R. China) has made significant progress on schistosomiasis control. Among the 12 provincial-level administrative divisions (PLADs) with schistosomiasis endemic in P. R. China, Guangdong, Shanghai, Fujian, Guangxi and Zhejiang PLADs (following as five PLADs) had successively eliminated schistosomiasis during 1985–1995. However, consolidation of the schistosomiasis elimination in these five PLADs remains challenging. In the current study, we sought to understand the epidemic situation in these post-elimination areas and their surveillance capabilities on schistosomiasis.

Methods

Annual data reflecting the interventions and surveillance on human beings, cattle and snails based on county level from 2005 to 2016 were collected through the national schistosomiasis reporting system and the data were analyzed to understand the epidemic status of schistosomiasis in the five PLADs. A standardized score sheet was designed to assess the surveillance capacity for schistosomiasis of selected disease control agencies in five PLADs and ten counties. Assessment on surveillance capacity including schistosomiasis diagnostic skills, identification of snails’ living and infection status and knowledge about schistosomiasis and its control were made. Descriptive analysis was used to analyze the epidemic status and evaluation results on surveillance capacities.

Results

The assessments showed that no local cases in humans and cattle or infected snail were found in these five PLADs since 2005. However, from 2005 to 2016, a total of 221 imported cases were detected in Zhejiang, Shanghai and Fujian, and 11.98 hm² of new snail habitats were found in Zhejiang, Shanghai and Guangxi. In addition, snail infestation reoccurred in 247.55 hm² of former snail habitats since 2011. For the surveillance capacity assessment, the accuracy rate of IHA and MHT were 100 and 89.3%, respectively. All participants could judge the living status of snails accurately and 98.1% on the infection status of snails. The accuracy rate of the questionnaire survey was 98.0%.

Conclusions

Elimination of schistosomiasis was consolidated successfully in five PLADs of P. R. China due to effective and strong post-elimination surveillance. Comprehensive consolidation strategies should be focused on the elimination of residual snails and the prevention of imported infection sources to consolidate the achievements of schistosomiasis control.

Prohibitin 1 (PHB1) controls growth and development and regulates proliferation and apoptosis in Schistosoma japonicum

Schistosomiasis is a zoonotic parasitic disease caused by the trematode blood flukes of the genus Schistosoma. The prodigious egg output of females is the main cause of the disease in definitive hosts, while the female worm relies on continuous pairing with the male worm to fuel the growth and maturation of the reproductive organs and egg production. Prohibitin, which contains the functionally interdependent PHB1 and PHB2 subunits in human and some other species, has been proposed to participate in the cell proliferation and apoptosis regulation in mammals. However, little is known about the function of PHB homolog in the growth and reproductive development of schistosomes. Here, we reported the Phb1 gene that was structurally and evolutionarily conserved in Schistosoma japonicum when compared with that of other species from Caenorhabditis elegans to human. Real-time PCR detected that SjPhb1 was highly transcribed in the vitellaria of female worms. SjPhb1 knockdown achieved through the dsRNA-mediated RNAi in vivo resulted in retarded growth, decreased pairing, and fecundity in adult worms, as well as attenuated pathogenicity or virulence of worms to their hosts. Cell proliferation and apoptosis examination found decreased cell proliferation and increased cell apoptosis in SjPhb1 dsRNA-treated worms. Therefore, our study provides the first characterization of S. japonicum PHB1 and reveals its fundamental role in the regulation of growth and development of S. japonicum by specific dsRNA-mediated RNAi in vivo. Our findings prompt for a promising molecular of schistosomes that can be targeted to effectively retard the growth and development of the schistosomes.

Pharmacological inhibition of lysine-specific demethylase 1 (LSD1) induces global transcriptional deregulation and ultrastructural alterations that impair viability in Schistosoma mansoni

Treatment and control of schistosomiasis still rely on only one effective drug, praziquantel (PZQ) and, due to mass treatment, the increasing risk of selecting for schistosome strains that are resistant to PZQ has alerted investigators to the urgent need to develop novel therapeutic strategies. The histone-modifying enzymes (HMEs) represent promising targets for the development of epigenetic drugs against Schistosoma mansoni. In the present study, we targeted the S. mansoni lysine-specific demethylase 1 (SmLSD1), a transcriptional corepressor, using a novel and selective synthetic inhibitor, MC3935, which was used to treat schistosomula and adult worms in vitro. By using cell viability assays and optical and electron microscopy, we showed that treatment with MC3935 affected parasite motility, egg-laying, tegument, and cellular organelle structures, culminating in the death of schistosomula and adult worms. In silico molecular modeling and docking analysis suggested that MC3935 binds to the catalytic pocket of SmLSD1. Western blot analysis revealed that MC3935 inhibited SmLSD1 demethylation activity of H3K4me1/2. Knockdown of SmLSD1 by RNAi recapitulated MC3935 phenotypes in adult worms. RNA-Seq analysis of MC3935-treated parasites revealed significant differences in gene expression related to critical biological processes. Collectively, our findings show that SmLSD1 is a promising drug target for the treatment of schistosomiasis and strongly support the further development and in vivo testing of selective schistosome LSD1 inhibitors.

Inhibition of the NAD salvage pathway in schistosomes impairs metabolism, reproduction, and parasite survival

NAD, a key co-enzyme required for cell metabolism, is synthesized via two pathways in most organisms. Since schistosomes apparently lack enzymes required for de novo NAD biosynthesis, we evaluated whether these parasites, which infect >200 million people worldwide, maintain NAD homeostasis via the NAD salvage biosynthetic pathway. We found that intracellular NAD levels decline in schistosomes treated with drugs that block production of nicotinamide or nicotinamide mononucleotide–known NAD precursors in the non-deamidating salvage pathway. Moreover, in vitro inhibition of the NAD salvage pathway in schistosomes impaired egg production, disrupted the outer membranes of both immature and mature parasites and caused loss of mobility and death. Inhibiting the NAD salvage pathway in schistosome-infected mice significantly decreased NAD levels in adult parasites, which correlated with reduced egg production, fewer liver granulomas and parasite death. Thus, schistosomes, unlike their mammalian hosts, appear limited to one metabolic pathway to maintain NAD-dependent metabolic processes.

Schistosomiasis (snail fever) is a deadly parasitic disease that affects more than 200 million people worldwide and, if not treated, can lead to death. This disease is caused by parasitic worms called schistosomes that feed on the host blood and lay hundreds of eggs each day that damage the liver and kidneys. Therapies to treat schistosomiasis are limited. The most widely-used anti-schistosomal drug, praziquantel, is not effective against immature parasites and adult worms can, in some cases, become resistant to this drug. It is therefore important to find new therapies to treat this deadly disease. In this study, we observed that schistosomes cannot use amino acids to make Nicotinamide Adenine Dinucleotide (NAD)–a key cellular metabolite found in all living organisms. Instead, these parasites salvage NAD by scavenging vitamins from the host. We observed that disruption of this NAD salvage pathway negatively impacts metabolism, reproduction and survival of both adult and immature worms. As such, targeting the parasite’s NAD salvage pathway is a promising therapeutic approach for the treatment of snail fever.

The role of the adaptor molecule STING during Schistosoma mansoni infection

Schistosomiasis is a human parasitic disease responsible for serious consequences for public health, as well as severe socioeconomic impacts in developing countries. Here, we provide evidence that the adaptor molecule STING plays an important role in Schistosoma mansoni infection. S. mansoni DNA is sensed by cGAS leading to STING activation in murine embryonic fibroblasts (MEFs). Sting^-/- and C57BL/6 (WT) mice were infected with schistosome cercariae in order to assess parasite burden and liver pathology. Sting^-/- mice showed worm burden reduction but no change in the number of eggs or granuloma numbers and area when compared to WT animals. Immunologically, a significant increase in IFN-γ production by the spleen cells was observed in Sting^-/- animals. Surprisingly, Sting^-/- mice presented an elevated percentage of neutrophils in lungs, bronchoalveolar lavage, and spleens. Moreover, Sting^-/- neutrophils exhibited increased survival rate, but similar ability to kill schistosomula in vitro when stimulated with IFN-γ when compared to WT cells. Finally, microbiota composition was altered in Sting^-/- mice, revealing a more inflammatory profile when compared to WT animals. In conclusion, this study demonstrates that STING signaling pathway is important for S. mansoni DNA sensing and the lack of this adaptor molecule leads to enhanced resistance to infection.

Nomograms to predict 2-year overall survival and advanced schistosomiasis-specific survival after discharge: a competing risk analysis

Background

The prognosis of patients with advanced schistosomiasis is poor. Pre-existing prognosis studies did not differentiate the causes of the deaths. The objectives were to evaluate the 2-year overall survival (OS) and advanced schistosomiasis-specific survival (ASS) in patients with advanced schistosomiasis after discharge through competing risk analysis and to build predictive nomograms.

Methods

Data was extracted from a previously constructed database from Hubei province. Patients were enrolled from September 2014 to January 2015, with follow up to January 2017. OS and ASS were primary outcome measures. Nomograms for estimating 2-year OS and ASS rates after discharge were established based on univariate and multivariate Cox regression model and Fine and Gray’s model. Their predictive performances were evaluated using C-index and validated in both internal and external validation cohorts.

Results

The training cohort included 1487 patients with advanced schistosomiasis. Two-year mortality rate of the training cohort was 8.27% (123/1487). Competing events accounted for 26.83% (33/123). Older age, splemomegaly clinical classification, abnormal serum DBil, AST, ALP and positive HBsAg were significantly associated with 2-year OS. Older age, splemomegaly clinical classification, abnormal serum AST, ALP and positive HBsAg were significantly associated with 2-year ASS. The established nomograms were well calibrated, and had good discriminative ability, with a C-index of 0.813 (95% CI 0.803–0.823) for 2-year OS prediction and 0.834 (95% CI 0.824–0.844) for 2-year ASS prediction. Their predictive performances were well validated in both internal and external validation cohorts.

Conclusion

The effective predictors of 2-year OS and ASS were discovered through competing risk analysis. The nomograms could be used as convenient predictive tools in clinical practice to guide follow-up and aid accurate prognostic assessment.

Schistosoma mansoni glyceraldehyde-3-phosphate dehydrogenase enhances formation of the blood-clot lysis protein plasmin

Schistosomes are intravascular blood flukes that cause the parasitic disease schistosomiasis. In agreement with Schistosoma mansoni (Sm) proteomic analysis, we show here that the normally intracellular glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is also found at the parasite surface; live worms from all intravascular life stages display GAPDH activity. Suppressing GAPDH gene expression using RNA interference significantly lowers this live worm surface activity. Medium in which the worms are cultured overnight displays essentially no activity, showing that the enzyme is not shed or excreted but remains associated with the worm surface. Immunolocalization experiments confirm that the enzyme is highly expressed in the parasite tegument (skin). Surface activity in schistosomula amounts to ∼8% of that displayed by equivalent parasite lysates. To address the functional role of SmGAPDH, we purified the protein following its expression in Escherichiacoli strain DS113. The recombinant protein displays optimal enzymatic activity at pH 9.2, shows robust activity at the temperature of the parasite's hosts, and has a Michaelis-Menten constant for glyceraldehyde-3-phosphate (GAP) of 1.4 mM±0.24. We show that recombinant SmGAPDH binds plasminogen (PLMG) and promotes PLMG conversion to its active form (plasmin) in a dose response in the presence of tissue plasminogen activator. Since plasmin is a key mediator of thrombolysis, our results support the hypothesis that SmGAPDH, a host-interactive tegumental protein that can enhance PLMG activation, could help degrade blood clots around the worms in the vascular microenvironment and thus promote parasite survival in vivoThis article has an associated First Person interview with the first author of the paper.

MicroRNA-21 Mediates the Inhibiting Effect of Praziquantel on NLRP3 Inflammasome in Schistosoma japonicum Infection

Praziquantel (PZQ), a traditional helminthicide drug, has been shown to exert an anti-inflammatory effect on splenomegaly induced by schistosomiasis via regulating macrophage polarization. Meanwhile, miR-21 has been demonstrated to control macrophage polarization. However, the role of miR-21 in the regulation of macrophage polarization by PZQ in schistosomiasis is still unclear. In the present study, we found that M1-type macrophages were the predominant splenic macrophages in chronic schistosomiasis and that NLRP3 inflammasome–related molecules were upregulated. PZQ inhibited NLRP3 inflammasome in M1 macrophages and reduced the expression of miR-21. Furthermore, using the methods of quantitative real-time PCR and transfection, the downregulation of NLRP3/IL-1β by PZQ in M1 macrophages were reversed by miR-21 overexpression. These results indicated that miR-21 was involved in the inhibiting effect of PZQ on activation of NLRP3 inflammasome. Moreover, miR-21 might target Smad7 to mediate the anti-inflammatory effect of PZQ in polarized macrophages. This study provides an in-depth mechanism of PZQ in the treatment of schistosomiasis.

Upregulation of KSRP by miR-27b attenuates schistosomiasis-induced hepatic fibrosis by targeting TGF-β1

Hepatic stellate cells (HSCs) are the main effectors for various types of hepatic fibrosis, including Schistosome-induced hepatic fibrosis. Multiple inflammatory cytokines/chemokines, such as transforming growth factor-β1 (TGF-β1), activate HSCs, and contribute to the development of hepatic fibrosis. MicroRNAs regulate gene expression at the posttranscriptional level and are involved in regulation of inflammatory cytokine/chemokine synthesis. In this study, we showed that soluble egg antigen (SEA) stimulation and Schistosoma japonicum infection downregulate miR-27b expression and increase KH-type splicing regulatory protein (KSRP) mRNA and protein levels in vitro and in vivo. miR-27b regulates the stabilization of TGF-β1 mRNA through targeting KSRP by interacting with their AU-rich elements in hepatocytes and non-parenchymal cells, which has an effect on the activation of HSCs. Importantly, our results have shown that either knockdown miR-27b or overexpression of KSRP attenuates S. japonicum-induced hepatic fibrosis in vivo. Therefore, our study highlights the crucial role of miR-27b and KSRP in the negative regulation of immune reactions in hepatocyte and non-parenchymal cells in response to SEA stimulation and S. japonicum infection. It reveals that manipulation of miR-27b or KSRP might be a useful strategy not only for treating Schistosome-induced hepatic fibrosis but also for curing hepatic fibrosis in general.

In vitro activity of aryl-thiazole derivatives against Schistosoma mansoni schistosomula and adult worms

Schistosomiasis is caused by a trematode of the genus Schistosoma and affects over 200 million people worldwide. The only drug recommended by the World Health Organization for treatment and control of schistosomiasis is praziquantel. Development of new drugs is therefore of great importance. Thiazoles are regarded as privileged structures with a broad spectrum of activities and are potential sources of new drug prototypes, since they can act through interactions with DNA and inhibition of DNA synthesis. In this context, we report the synthesis of a series of thiazole derivatives and their in vitro schistosomicidal activity by testing eight molecules (NJ03-08; NJ11-12) containing thiazole structures. Parameters such as motility and mortality, egg laying, pairing and parasite viability by ATP quantification, which were influenced by these compounds, were evaluated during the assays. Scanning electron microscopy (SEM) was utilized for evaluation of morphological changes in the tegument. Schistosomula and adult worms were treated in vitro with different concentrations (6.25 to 50 μM) of the thiazoles for up to 5 and 3 days, respectively. After in vitro treatment for five days with 6.25 μM NJ05 or NJ07 separately, we observed a decrease of 30% in schistosomula viability, whilst treatment with NJ05+NJ07 lead to a reduction of 75% in viability measured by ATP quantitation and propidium iodide labeling. Adult worms’ treatment with 50 μM NJ05, NJ07 or NJ05 + NJ07 showed decreased motility to 30–50% compared with controls. Compound NJ05 was more effective than NJ07, and adult worm viability after three days was reduced to 25% in parasites treated with 50 μM NJ05, compared with a viability reduction to 40% with 50 μM NJ07. SEM analysis showed severe alterations in adult worms with formation of bulges and blisters throughout the dorsal region of parasites treated with NJ05 or NJ07. Oviposition was extremely affected by treatment with the NJ series compounds; at concentrations of 25 μM and 50 μM, oviposition reached almost zero with NJ05, NJ07 or NJ05 + NJ07 already at day one. Tested genes involved in egg biosynthesis were all confirmed by qPCR as downregulated in females treated with 25 μM NJ05 for 2 days, with a significant reduction in expression of p14, Tyrosinase 2, p48 and fs800. NJ05, NJ07 or NJ05+NJ07 treatment of HEK293 (human embryonic cell line) and HES (human epithelial cell line) showed EC50 in the range of 18.42 to 145.20 μM. Overall, our results demonstrate that those molecules are suitable targets for further development into new drugs for schistosomiasis treatment, although progress is needed to lessen the cytotoxic effects on human cells. According to the present study, thiazole derivatives have schistosomicidal activities and may be part of a possible new arsenal of compounds against schistosomiasis.

Impact of chronic schistosomiasis and HBV/HCV co-infection on the liver: current perspectives

Schistosomiasis is a public health problem in many countries. Its prevalence is increasing annually; the current infection rate is one in 30 individuals. The WHO reported that at least 206.4 million people all over the world required preventive treatments for schistosomiasis in 2016. Chronic schistosomiasis, hepatitis B virus (HBV) and hepatitis C virus (HCV) co-infection are common in countries where schistosomiasis is endemic. The effects of the hepatotropic virus co-infection may modify the Th2-dominated granulomatous phase of schistosomal infection. These viruses induce a strong-specific T cell response, with infiltration of large numbers of specific interferon-γ-producing CD8+ cells into the liver. The outcome of liver diseases depends on the underlying causes, host immune response and concomitant infections. Co-infection of schistosomiasis with HBV/HCV infection causes advanced liver disease and worsens the outcome, especially with higher viral load titers, which increase the mortality rate through an increased incidence of liver cirrhosis and hepatocellular carcinoma. The exposure risk for HBV in patients with HCV and schistosomiasis was two and half times greater than that in CHC patients without schistosomiasis. Finally, chronic schistosomiasis and HBV/HCV co-infection have serious effects on liver pathology. Co-infection accelerates the progression of liver disease and leads to advanced liver diseases and liver failure.

Efficacy of China-made praziquantel for treatment of Schistosomiasis haematobium in Africa: A randomized controlled trial

Background

In the roadmap on the neglected tropical diseases (NTD) the World Health Organization (WHO) aims at attaining at least 75% coverage of preventive chemotherapy in pre-school and school-age children by 2020. A randomized controlled trial was used to compare the effectiveness of praziquantel in treating Schistosoma haematobium in Africa using two different sources for the drug, Merck Limited Partnership (KgaA), Germany and Nanjing Pharmaceutical Factory (NPF), China.

Methods

More than 6,000 participants testing positive for S. haematobium infection were enrolled from three villages (shehias) situated in the northern, middle and southern part of Pemba Island, Zanzibar. Applying criteria of inclusion and exclusion, resulted in a study population of 152 people (84 males, 68 females). A randomized controlled trial was conducted assigning participants to either praziquantel from NPF or Merck KGaA. After one month, the cure rate of S. haematobium and adverse events were compared to evaluate effectiveness. The ratio of male to female, the ratio of light/high infection intensity, and the average value of age were calculated between the two drug manufacturers. Chi-squared test and T-test were used for consistency analysis.

Results

Out of the total of 73 cases receiving praziquantel from NPF, the cure rate achieved was 97.3% (73/75), while the 74 cases receiving the drug from Merck KgaA reached a similar cure rate (96.1% or 74/77). There was no significant difference between the two outcomes (χ² = 0.003, P = 0.956). Among the 75 patients treat, only one (a 16-years old female student), who had received the drug made in China had slight adverse reactions manifested as dizziness, headache and abdominal pain.

Conclusion

The efficacy of China-made praziquantel does not differ significantly from praziquantel made by Merck KGaA in Germany.

Trial registration

ClinicalTrials.gov, NCT03133832

Schistosomiasis is a neglected tropical disease (NTD) with praziquantel the only effective drug available. It is estimated that about 800 million people are currently at risk for this disease with more than 200 million people infected. A large drug donation partnership between Merck, Darmstadt, Germany and the World Health Organization supports widespread, successful preventive chemotherapy programs, but the donated drugs does not meet the entire need, particularly not in Africa. The primary aim of our study was to evaluate the efficacy of China-made praziquantel to explore whether the drug could complement preventive chemotherapy programs in Africa. A randomized controlled trial was conducted assigning participants to two groups, one receiving praziquantel from NPF, the other from Merck KGaA. After one month, the cure rate of S. haematobium and were compared to evaluate effectiveness and document potential adverse events. The outcome showed that the two sources of praziquantel that did not differ significantly from each other. China-made praziquantel can thus be trusted to complement the current use of the drug from Merck KGaA in Africa making it possible to enlarge drug provision programs.

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.

Can CRISPR help in the fight against parasitic worms?

The first reports of CRISPR/Cas9 genome editing in flatworms could usher in a new era of research on these dangerous human parasites.

Extracellular Vesicle-Mediated Communication Within Host-Parasite Interactions

Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) in vivo and in vitro that contain large amounts of important substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.

Trematoda (flukes)

The class Trematoda is the largest group of Platyhelminths and includes two subclasses: Aspidogastrea and Digenea. Trematodes, and particularly Digeneans, is a large group of organisms with significant medical and veterinary interest. Over 100 species of digenetic trematodes have been reported infecting humans. Although the significant mortality and morbidity that some of these infections cause, they are among the most neglected tropical diseases. Apart from their impact in public and animal health, the Digenea constitutes an intriguing group of organisms that has a vast interest in experimental biology. Systematics and taxonomy of this group constitute a challenge for biologists in relation to the difficulty entailed in the establishment of phylogenetic relationships between trematodes and the determination of valid diagnostic features. Moreover, their complex life cycles, using at least two hosts and alternating free-living and parasitic stages or sexual and asexual multiplication, constitute a paradigm of how organisms can evolve to become adapted to different biotic and abiotic environments to enhance survival. In this review, we briefly summarize the major features of trematodes in relation to both biological and medical areas.

Lentivirus-mediated over-expression of let-7b microRNA suppresses hepatic fibrosis in the mouse infected with Schistosoma japonicum

Transforming growth factor-β (TGF-β) signaling pathway is documented to participate in liver fibrosis via multifactorial mechanisms. microRNA Let-7b (Let-7b) has been proved to alleviate cell fibrosis through regulating TGF-β receptor I (TβRI), but whether it is involved in Schistosomiasis liver fibrosis (SLF) has not been determined. In the present, SLF mice model was used to investigate Let-7b's function and mechanism in SLF. We found that hepatic let-7b expression was continuously declined in SLF, accompanied by the induction of TGF-β pathway molecules (TGF-β1, TβRI), profibrogenic mediators (α-SMA, colla I), and Th1/Th2 cells response factors (IFN-γ, IL-4). When recombinant Lentivirus of let-7b (Lenti-let-7b) was transfected into S. japonicum-infected mice, the mice hepatic fibrosis was distinctly ameliorated, and TGF-β1, TβRI, α-SMA, and colla I expressions were remarkly decreased, mice serum IL-4 and IFN-γ levels were reduced. Similarly, over-expression of let-7b down-regulated the expression of TβRI in THP-1 cells transfected with let-7b mimics, while TβRI was up-regulated after treated with let-7b inhibitor. These findings suggested that let-7b is a negative regulator to SLF through downregulating TβRI, and inhibits Th1 and Th2 type cell immune response. This provides a novel potential therapeutic strategy for SFL prevention.

Absence of Batf3 results in reduced liver pathology in mice infected with Schistosoma japonicum

Background

The involvement of CD8⁺T cells in schistosomiasis is being increasingly appreciated, but the underlying mechanism is not well defined.

Results

In this study, we showed that the absence of Batf3 alleviated liver damage in Batf3^−/− mice infected with S. japonicum. We found alleviated liver granulomatous inflammation in Batf3^−/− mice with schistosomiasis japonica could not be attributed to the difference in schistosome egg or worm burden. The stronger Tc1 cell responses observed in Batf3^−/− mice suggested that the deletion of Batf3 resulted in more activation of CD8⁺T cells unexpectedly during the natural infection of schistosomes. We detected a small amount of CD8α⁺ DCs in the spleen of Batf3^−/− mice at 9w post-infection. This small amount of newly generated CD8α⁺ DCs might contribute to enhanced activation of CD8⁺T cells via cross-presentation and activation which then attenuate hepatic pathological damage found in Batf3^−/− mice.

Conclusions

Our study provides evidence that Batf3 is associated with the immunoregulation of the liver granuloma formation, which may confer a new options for schistosomiasis treatment.

Lessons from a 15-year-old boy with advanced schistosomiasis japonica in China: a case report

Schistosomiasis is a chronic, parasitic disease caused by flukes (trematodes) of the genus Schistosoma, which presents the most important global burden of the 17 neglected tropical diseases listed by the World Health Organization. China has made great achievements in schistosomiasis control, and now China is planning to move forward, to eliminate schistosomiasis within 2020, but the fact cannot be denied that the possibility of schistosome infection is still there in some endemic due to its zoonotic nature as well as wide distribution of its intermediate hosts (snails). Thus, how to interrupt the transmission in areas with distribution of schistosomes and intermediate snails becomes a very serious challenge that China is facing. In this paper, it is reported an advanced schistosomiasis japonica case of a 15-year-old boy which is extremely rare in the current schistosomiasis control in China. Thus, it is supposed to strengthen health education of school children and to train professional physicians of local hospitals.

Advances in Spermatological Characters in the Digenea: Review and Proposal of Spermatozoa Models and Their Phylogenetic Importance

The wide biodiversity and economic importance of digeneans have motivated a great deal of research in the last decade, focussing on their phylogenetic positions. Molecular research was instrumental for our understanding of phylogeny in the Digenea, but spermatological studies have also provided many results, which are potentially useful for phylogeny; however, the complete spermatological data set has never been reviewed in a whole phylogenetic perspective. Spermatological data are now available for more than 100 species, belonging to 15 superfamilies and 46 families. In this paper, we try to summarize the current knowledge about sperm structure in the digeneans and propose a classification of digenean spermatozoa into five basic models. The main ultrastructural characters used are (1) the type of axoneme, (2) the lateral expansion, (3) the association 'external ornamentation of the plasma membrane + cortical microtubules', (4) the field of cortical microtubules and its number, (5) the location of the external ornamentation, (6) the location of the maximum number of cortical microtubules and (7) the number of mitochondria. We also outline the most interesting features for phylogenetic inference and their possible value in the context of digenean systematics, phylogeny and evolution. Associations between sperm models and superfamilies were found as follows: Type 1 in the Schistosomatoidea; Type 2 in the Hemiuroidea; Type 3 in the Opecoeloidea, Lepocreadioidea, Haploporoidea and Opisthorchioidea; Type 4 in the Gorgoderoidea, Microphalloidea, Plagiorchioidea and Gymnophalloidea; Type 5 in the Echinostomatoidea, Microscaphidioidea, Paramphistomoidea, Pronocephaloidea and Brachylaimoidea.