The rhesus macaque provides a unique model of acquired immunity against schistosomes, which afflict >200 million people worldwide. By monitoring bloodstream levels of parasite-gut-derived antigen, we show that from week 10 onwards an established infection withSchistosoma mansoniis cleared in an exponential manner, eliciting resistance to reinfection. Secondary challenge at week 42 demonstrates that protection is strong in all animals and complete in some. Antibody profiles suggest that antigens mediating protection are the released products of developing schistosomula. In culture they are killed by addition of rhesus plasma, collected from week 8 post-infection onwards, and even more efficiently with post-challenge plasma. Furthermore, cultured schistosomula lose chromatin activating marks at the transcription start site of genes related to worm development and show decreased expression of genes related to lysosomes and lytic vacuoles involved with autophagy. Overall, our results indicate that enhanced antibody responses against the challenge migrating larvae mediate the naturally acquired protective immunity and will inform the route to an effective vaccine.

Background: Schistosomiasis chemotherapy is largely based on praziquantel (PZQ). Although PZQ is very safe and tolerable, it does not prevent reinfection and emerging resistance is a primary concern. Recent studies have shown that the targeting of epigenetic machinery in Schistosoma mansoni may result in severe alterations in parasite development, leading to death. This new route for drug discovery in schistosomiasis has focused on classes of histone deacetylases (HDACs) and histone acetyltransferases (HATs) as epigenetic drug targets. Schistosoma histone demethylases also seem to be important in the transition of cercariae into schistosomula, as well as sexual differentiation in adult worms. Methods: The Target-Pathogen database and molecular docking assays were used to prioritize the druggability of S. mansoni histone demethylases. The transcription profile of Smp_03400 was re-analyzed using available databases. The effect of GSK-J4 inhibitor in schistosomula and adult worms’ motility/viability/oviposition was assessed by in vitro assays. Ultrastructural analysis was performed on adult worms exposed to GSK-J4 by scanning electron microscopy, while internal structures and muscle fiber integrity was investigated by confocal microscopy after Langeronʼs carmine or phalloidin staining. Results: The present evaluation of the potential druggability of 14 annotated S. mansoni demethylase enzymes identified the S. mansoni ortholog of human KDM6A/UTX (Smp_034000) as the most suitable druggable target. In silico analysis and molecular modeling indicated the potential for cofactor displacement by the chemical probe GSK-J4. Our re-analysis of transcriptomic data revealed that Smp_034000 expression peaks at 24 h in newly transformed schistosomula and 5-week-old adult worms. Moreover, this gene was highly expressed in the testes of mature male worms compared to the rest of the parasite body. In in vitro schistosome cultures, treatment with GSK-J4 produced striking effects on schistosomula mortality and adult worm motility and mortality, as well as egg oviposition, in a dose- and time-dependent manner. Unexpectedly, western blot assays did not demonstrate overall modulation of H3K27me3 levels in response to GSK-J4. Confocal and scanning electron microscopy revealed the loss of original features in muscle fibers and alterations in cell-cell contact following GSK-J4 treatment. Conclusions: GSK-J4 presents promising potential for antischistosomal control; however, the underlying mechanisms warrant further investigation.

Schistosomiasis is a parasitic disease that affects more than 250 million people. The treatment is limited to praziquantel and the control of the intermediate host with the highly toxic molluscicidal niclosamide. Marine algae are a poorly explored and promising alternative that can provide lead compounds, and the use of multivariate analysis could contribute to quicker discovery. As part of our search for new natural compounds with which to control schistosomiasis, we screened 45 crude extracts obtained from 37 Brazilian seaweed species for their molluscicidal activity against Biomphalaria glabrata embryos and schistosomicidal activities against Schistosoma mansoni. Two sets of extracts were taxonomically grouped for metabolomic analysis. The extracts were analyzed by GC–MS, and the data were subjected to Pattern Hunter and Pearson correlation tests. Overall, 22 species (60%) showed activity in at least one of the two models. Multivariate analysis pointed towards 3 hits against B. glabrata veliger embryos in the Laurencia/Laurenciella set, 5 hits against B. glabrata blastula embryos, and 31 against S. mansoni in the Ochrophyta set. Preliminary annotations suggested some compounds such as triquinane alcohols, prenylated guaianes, dichotomanes, and xenianes. Despite the putative identification, this work presents potential candidates and can guide future isolation and identification.

The present study evaluated the efficacy of the mineralizing action of Casearia sylvestris ethanolic extract on bovine dentin blocks in its pure form and in dental paste, through scanning electron microscopy. The dentin blocks were immersed in artificial saliva and incubated at 37°C for 7 days. Subsequently, six groups were treated with different test substances and analysed qualitatively and quantitatively at 30 and 60 days. The tests used were Kruskal-Wallis and Dunn's. Shapiro-Wilk and ANOVA. The qualitative analysis at 30 days showed a difference between the groups treated with ethanolic extract and toothpaste. Quantitatively, at 30 days, treatment with ethanolic extract of Casearia showed a greater number of open dentinal tubules. At 60 days, the difference persisted only for the blocks treated with toothpaste. The results obtained indicated that there is a positive relationship between the use of Casearia sylvestris and obliteration of dentinal tubules.

Background: Marine macroalgae has been studied by our research group as alternative sources of bioactive compounds with promising antiparasitic activity, particularly against Schistosoma mansoni. Objectives: This study aimed to employ a metabolomics-based approach to identify anthelminthic active compounds from the macroalgae Laurencia aldingensis Saito and Womersley 1974 and Laurencia dendroidea J. Agardh 1852. Methods: The algae were extracted using a dichloromethane/methanol mixture, followed by liquid–liquid partitioning and sequential chromatographic fractionation using solvents of varying polarities. The resulting fractions were tested for biological activity against adult Schistosoma mansoni worms. Detailed chemical characterization of the extracts was conducted via HPLC-DAD-MS/MS, with subsequent data alignment and statistical analysis (Pearson correlation) to associate specific chemical compounds with the observed bioactivity. Results: Non-polar fractions (hexane and dichloromethane) exhibited significant anthelminthic activity, substantially reducing parasite viability and reproduction. Specific subfractions obtained from the dichloromethane fraction demonstrated notable activity. Metabolomic analysis revealed considerable chemical diversity, emphasizing the presence of bromophenols and halogenated sesquiterpenes, including potentially novel compounds with therapeutic potential against schistosomiasis. Conclusions: The metabolomics approach proved effective in identifying promising bioactive compounds from Laurencia spp. macroalgae with activity against S. mansoni.