Evaluation of sensitivity and specificity of Kato-Katz and circulating cathodic antigen in terms of Schistosoma japonicum using latent class analysis

Schistosoma japonicum is endemic in the Philippines. The Kato-Katz (KK) method was used to diagnose S. japonicum. This is impractical, particularly when the sample size is limited. Knowledge on point-of-care circulating cathodic antigen (CCA) test performance for S. japonicum is limited. Determining the sensitivity and specificity of new diagnostics is difficult when the gold standard test is less effective or absent. Latent class analysis (LCA) can address some limitations. A total of 484 children and 572 adults from the Philippines were screened for S. japonicum. We performed Bayesian LCA to estimate the infection prevalence, sensitivity and specificity of each test by stratifying them into two age groups. Observed prevalence assessed by KK was 50.2% and 31.8%, and by CCA was 89.9% and 66.8%, respectively. Using Bayesian LCA, among children, the sensitivity and specificity of CCA were 94.8% (88.7-99.4) and 21.5% (10.5-36.1) while those of KK were 66.0% (54.2-83.3) and 78.1% (61.1-91.3). Among adults, the sensitivity and specificity of CCA were 86.4% (76.6-96.9) and 62.8% (49.1-81.1) while those of KK were 43.6% (35.1-53.9) and 85.5% (75.8-94.6). Overall, CCA was more sensitive than KK, regardless of the age group at diagnosis, as KK was more specific. KK and CCA have different diagnostic performance, which should inform their use in the planning and implementation of S. japonicum control programs.

Antigenic epitope targets of rhesus macaques self-curing from Schistosoma mansoni infection

The self-cure of rhesus macaques from a schistosome infection and their subsequent strong immunity to a cercarial challenge should provide novel insights into the way these parasites can be eliminated by immunological attack. High-density arrays comprising overlapping 15-mer peptides from target proteins printed on glass slides can be used to screen sera from host species to determine antibody reactivity at the single epitope level. Careful selection of proteins, based on compositional studies, is crucial to encompass only those exposed on or secreted from the intra-mammalian stages and is intended to focus the analysis solely on targets mediating protection. We report the results of this approach using two pools of sera from hi- and lo-responder macaques undergoing self-cure, to screen arrays comprising tegument, esophageal gland, and gastrodermis proteins. We show that, overall, the target epitopes are the same in both groups, but the intensity of response is twice as strong in the high responders. In addition, apart from Sm25, tegument proteins elicit much weaker responses than those originating in the alimentary tract, as was apparent in IFNγR KO mice. We also highlight the most reactive epitopes in key proteins. Armed with this knowledge, we intend to use multi-epitope constructs in vaccination experiments, which seek to emulate the self-cure process in experimental animals and potentially in humans.

The genome and transcriptome of the snail Biomphalaria sudanica s.l.: immune gene diversification and highly polymorphic genomic regions in an important African vector of Schistosoma mansoni

BACKGROUND

Control and elimination of schistosomiasis is an arduous task, with current strategies proving inadequate to break transmission. Exploration of genetic approaches to interrupt Schistosoma mansoni transmission, the causative agent for human intestinal schistosomiasis in sub-Saharan Africa and South America, has led to genomic research of the snail vector hosts of the genus Biomphalaria. Few complete genomic resources exist, with African Biomphalaria species being particularly underrepresented despite this being where the majority of S. mansoni infections occur. Here we generate and annotate the first genome assembly of Biomphalaria sudanica sensu lato, a species responsible for S. mansoni transmission in lake and marsh habitats of the African Rift Valley. Supported by whole-genome diversity data among five inbred lines, we describe orthologs of immune-relevant gene regions in the South American vector B. glabrata and present a bioinformatic pipeline to identify candidate novel pathogen recognition receptors (PRRs).

RESULTS

De novo genome and transcriptome assembly of inbred B. sudanica originating from the shoreline of Lake Victoria (Kisumu, Kenya) resulted in a haploid genome size of ~ 944.2 Mb (6,728 fragments, N50 = 1.067 Mb), comprising 23,598 genes (BUSCO = 93.6% complete). The B. sudanica genome contains orthologues to all described immune genes/regions tied to protection against S. mansoni in B. glabrata, including the polymorphic transmembrane clusters (PTC1 and PTC2), RADres, and other loci. The B. sudanica PTC2 candidate immune genomic region contained many PRR-like genes across a much wider genomic region than has been shown in B. glabrata, as well as a large inversion between species. High levels of intra-species nucleotide diversity were seen in PTC2, as well as in regions linked to PTC1 and RADres orthologues. Immune related and putative PRR gene families were significantly over-represented in the sub-set of B. sudanica genes determined as hyperdiverse, including high extracellular diversity in transmembrane genes, which could be under pathogen-mediated balancing selection. However, no overall expansion in immunity related genes was seen in African compared to South American lineages.

CONCLUSIONS

The B. sudanica genome and analyses presented here will facilitate future research in vector immune defense mechanisms against pathogens. This genomic/transcriptomic resource provides necessary data for the future development of molecular snail vector control/surveillance tools, facilitating schistosome transmission interruption mechanisms in Africa.

Schistosoma mansoni co-infection modulates Chagas disease development but does not impair the effect of benznidazole-based chemotherapy

The adequate management of parasite co-infections represents a challenge that has not yet been overcome, especially considering that the pathological outcomes and responses to treatment are poorly understood. Thus, this study aimed to evaluate the impact of Schistosoma mansoni infection on the efficacy of benznidazole (BZN)-based chemotherapy in Trypanosoma cruzi co-infected mice. BALB/c mice were maintained uninfected or co-infected with S. mansoni and T. cruzi, and were untreated or treated with BZN. Body weight, mortality, parasitemia, cardiac parasitism, circulating cytokines (Th1/Th2/Th17); as well as heart, liver and intestine microstructure were analyzed. The parasitemia peak was five times higher and myocarditis was more severe in co-infected than T. cruzi-infected mice. After reaching peak, parasitemia was effectively controlled in co-infected animals. BZN successfully controlled parasitemia in both co-infected and T. cruzi-infected mice and improved body mass, cardiac parasitism, myocarditis and survival in co-infected mice. Co-infection dampened the typical cytokine response to either parasite, and BZN reduced anti-inflammatory cytokines in co-infected mice. Despite BZN normalizing splenomegaly and liver cellular infiltration, it exacerbated hepatomegaly in co-infected mice. Co-infection or BZN exerted no effect on hepatic granulomas, but increased pulmonary and intestinal granulomas. Marked granulomatous inflammation was identified in the small intestine of all schistosomiasis groups. Taken together, our findings indicate that BZN retains its therapeutic efficacy against T. cruzi infection even in the presence of S. mansoni co-infection, but with organ-specific repercussions, especially in the liver.

Expression of SmATPDases 1 and 2 in Schistosoma mansoni eggs favours IL-10 production in infected individuals

A role of IL-10 is down-regulating T-cell responses to schistosome antigens. Since SmATPDases can be correlated to modulation of the immune response, we evaluated the expression of enzymes in S. mansoni eggs. Faecal samples were collected from 40 infected individuals to detect coding regions of the SmATPDases. The cytokines were measured in supernatants of PBMC. The analysis was performed by the global median determination and set up high producers (HP) of cytokines. Six individuals expressed SmATPDase1, six expressed SmATPDase2 and six expressed both enzymes. The group who expressed only SmATPDase1 showed a high frequency of IFN-γ, TNF IL-4 HP; individuals who expressed only SmATPDase2 showed a high frequency of IFN-γ, IL-6 and IL-4 HP; and individuals who expressed both enzymes showed a high frequency of IL-10 HP. The comparison of the IFN-γ/IL-10 ratio presented higher indices in the group who had SmATPDase 2 expression than those who had the expression of both enzymes. The positive correlation between infection intensity and IL-10 levels remained only in the positive SmATPDase group. The IL-10 is the only cytokine induced by the expression of both enzymes. Our data suggest that the expression of both enzymes seems to be a factor that modulates the host immune response by inducing high IL-10 production.

Schistosomiasis in Burkina Faso: review on 60 years' research

Schistosomiasis is a common neglected helminthic disease in the tropics and sub-tropics particularly in sub-Saharan countries including Burkina Faso. It is the second world parasitic endemic disease after malaria. The two prevalent species infecting human in Burkina Faso are are Schistosoma haematobium and Schistosoma mansoni which cause respectively the urogenital schistosomiasis and the intestinal schistosomiasis. This review aimed at providing an historical perspective of research on schistosomiasis from 1960 to 2020 and shedding some light on the gaps in knowledge useful for the disease control and the elimination efforts in Burkina Faso. Formal systematic review was not followed for this review. Published studies on the schistosomiasis in Burkina Faso over the period from 1960 to 2020, were search in Medline, PubMed, Google Scholar, EMBASE and the libraries of main universities in Burkina Faso namely: Joseph KI-ZERBO University and Nazi BONI University. The following key words used were: Schistosomiasis, Bilharzia, Bulinus, Biomphalaria, Upper-Volta and Burkina Faso. Over a period of 60 years, a total of 87 scientific research documents were identified. The original scientific research articles represent the majority of the scientific documents found (65.52%). Urinary schistosomiasis was the most common from the documentation. There has been a gradual decrease in the prevalence, more significantly since the implementation of the National Schistosomiasis Control Program (NSCP). The effectiveness of the NSCP could therefore contribute to the elimination of schistosomiasis in Burkina Faso.

Praziquantel efficacy, urinary and intestinal schistosomiasis reinfection - a systematic review

Praziquantel (PZQ) has been extensively used as the drug of choice for the treatment of schistosomiasis on account of its safety and effectiveness against all major forms of schistosomiasis. However, low cure rate, reduced susceptibility of Schistosoma mansoni to PZQ and treatment failures in S. haematobium infections have been reported, raising concerns about its efficacy. Using the search terms, 'praziquantel efficacy, schistosomiasis, school children, reinfection' as well as defined inclusion criteria, and guided by the PRISMA guidelines, articles from 2001 to 2022 were selected from the PubMed and Google Scholar databases and reviewed to assess their importance to the research question. This review assessed the efficacy of PZQ against schistosomiasis and reinfection rates following treatment of Schistosoma infections in children. Majority of both intestinal and urinary schistosomiasis studies reported comparable egg reduction rates (ERRs) of 94.2% to 99.9% and 91.9% to 98%, respectively. However, ERRs suggestive of sub-optimal PZQ efficacy as well as generally high and comparable cure rates for intestinal (81.2%-99.1%) and urinary (79%-93.7%) schistosomiasis studies were reported. Schistosomiasis reinfection rates varied widely for urinary (8.1%-39.6%) and intestinal (13.9%-63.4%) studies within eight to 28 weeks following PZQ treatment. Praziquantel treatment of urinary and intestinal schistosomiasis should be accompanied by the provision of potable water, toilet, and recreational facilities to reduce reinfection and egg reduction rates and increase cure rate to expedite schistosomiasis elimination.

Experimental infection with Schistosoma mansoni from Belém, Pará, Brazil: Strains newly isolated vs. laboratory maintained

BACKGROUND

Schistosomiasis is a neglected tropical disease that occurs in locations with inadequate sanitation conditions. The geographic distribution of Schistosoma mansoni trematode depends directly on the presence of its intermediate host, Biomphalaria mollusks. Studies involving recently isolated and laboratory strains are not common due to the difficulty in cycle maintenance. This study evaluated the susceptibility and infectivity responses in intermediate and definitive hosts with strains of S. mansoni, one isolated and kept in laboratory environment for 34 years (BE) and the other recently collected (BE-I) METHODS: For experimental infection, a total of 400 B. glabrata mollusks were divided in four infection groups. Thirty mice were divided in two groups for infection with the two strains.

RESULTS

It was possible to notice differences about S. mansoni infection in both strains. The laboratory strain was more harmful to freshly collected mollusks. Differences in the patterns of infection in mice could be observed.

CONCLUSION

Particularities occurred in each group of infection by S. mansoni strains, despite having the same geographic origin. Effects from the parasite-host interaction are visible in terms of infection in definitive and intermediate hosts.

Role of the IL-33/ST2 Activation Pathway in the Development of the Hepatic Fibrosis Induced by Schistosoma mansoni Granulomas in Mice

Schistosoma mansoni eggs retained in host tissues induce innate cytokine release, contributing to the induction of Type-2 immune responses and granuloma formation, important to restrain cytotoxic antigens, but leading to fibrosis. Interleukin(IL)-33 participates in experimental models of inflammation and chemically induced fibrosis, but its role in S. mansoni-induced fibrosis is still unknown. To explore the role of the IL-33/suppressor of the tumorigenicity 2 (ST2) pathway, serum and liver cytokine levels, liver histopathology, and collagen deposition were comparatively evaluated in S. mansoni-infected wild-type (WT) and IL-33-receptor knockout (ST2-/-) BALB/c mice. Our data show similar egg counts and hydroxyproline in the livers of infected WT and ST2-/- mice; however, the extracellular matrix in ST2-/- granulomas was loose and disorganised. Pro-fibrotic cytokines, such as IL-13 and IL-17, and the tissue-repairing IL-22 were significantly lower in ST2-/- mice, especially in chronic schistosomiasis. ST2-/- mice also showed decreased α-smooth muscle actin (α-SMA) expression in granuloma cells, in addition to reduced Col III and Col VI mRNA levels and reticular fibres. Therefore, IL-33/ST2 signalling is essential for tissue repairing and myofibroblast activation during S. mansoni infection. Its disruption results in inappropriate granuloma organisation, partly due to the reduced type III and VI collagen and reticular fibre formation.

Pulmonary inflammation promoted by type-2 dendritic cells is a feature of human and murine schistosomiasis

Schistosomiasis is a parasitic disease affecting over 200 million people in multiple organs, including the lungs. Despite this, there is little understanding of pulmonary immune responses during schistosomiasis. Here, we show type-2 dominated lung immune responses in both patent (egg producing) and pre-patent (larval lung migration) murine Schistosoma mansoni (S. mansoni) infection. Human pre-patent S. mansoni infection pulmonary (sputum) samples revealed a mixed type-1/type-2 inflammatory cytokine profile, whilst a case-control study showed no significant pulmonary cytokine changes in endemic patent infection. However, schistosomiasis induced expansion of pulmonary type-2 conventional dendritic cells (cDC2s) in human and murine hosts, at both infection stages. Further, cDC2s were required for type-2 pulmonary inflammation in murine pre-patent or patent infection. These data elevate our fundamental understanding of pulmonary immune responses during schistosomiasis, which may be important for future vaccine design, as well as for understanding links between schistosomiasis and other lung diseases.

CD193 ( CCR3 ) expression by B cells correlates with reduced IgE production in paediatric schistosomiasis

We demonstrate that CD193, the eotaxin receptor, is highly expressed on circulating B cells in paediatric schistosomiasis mansoni. CD193 plays a role in directing granulocytes into sites of allergic-like inflammation in the mucosa, but little is known about its functional significance on human B cells. We sought to characterize CD193 expression and its relationship with S. mansoni infection. We found that CD193+ B cells increased with the intensity of schistosome infection. In addition, a significant negative association was observed between CD193 expression by B cells and IgE production. Decreased IgE levels are generally associated with susceptibility to re-infection. B cell stimulation with eotaxin-1 increased CD193 levels whereas IL-4 led to a reduction. This was supported by plasma levels of eotaxin-1 correlating with CD193 levels on B cells and other cells. In contrast, CD193 expression was induced on naive B cells with a combination of IL-10 and schistosome antigens. Whereas T cells had a modest increase in CD193 expression, only B cell CD193 appeared functionally chemotactic to eotaxin-1. Thus, CD193+ B cells, which co-express CXCR5, may be enroute to sites with allergic-like inflammation, such as gastrointestinal follicles, or even to Th2 granulomas, which develop around parasite eggs. Overall, our results suggest that schistosome infection may promote CD193 expression and suppress IgE via IL-10 and other undefined mechanisms related to B cell trafficking. This study adds to our understanding of why young children may have poor immunity. Nonetheless, praziquantel treatment was shown to reduce percentages of circulating CD193+ B cells lending hope for future vaccine efforts.

Tumour-like breast lesions due to ectopic schistosomiasis in a European traveller†

Schistosomiasis is a neglected tropical disease classically responsible for intestinal or urogenital forms. We report the incidental diagnosis of ectopic mammary schistosomiasis involving Schistosoma haematobium following a breast cancer screening mammogram in a European patient with a distant history of travel.

A cercarial invadolysin interferes with the host immune response and facilitates infection establishment of Schistosoma mansoni

Schistosoma mansoni employs immune evasion and immunosuppression to overcome immune responses mounted by its snail and human hosts. Myriad immunomodulating factors underlie this process, some of which are proteases. Here, we demonstrate that one protease, an invadolysin we have termed SmCI-1, is released from the acetabular glands of S. mansoni cercaria and is involved in creating an immunological milieu favorable for survival of the parasite. The presence of SmCI-1 in the cercarial stage of S. mansoni is released during transformation into the schistosomula. SmCI-1 functions as a metalloprotease with the capacity to cleave collagen type IV, gelatin and fibrinogen. Additionally, complement component C3b is cleaved by this protease, resulting in inhibition of the classical and alternative complement pathways. Using SmCI-1 knockdown cercariae, we demonstrate that SmCI-1 protects schistosomula from complement-mediated lysis in human plasma. We also assess the effect of SmCI-1 on cytokine release from human peripheral blood mononuclear cells, providing compelling evidence that SmCI-1 promotes an anti-inflammatory microenvironment by enhancing production of IL-10 and suppressing the production of inflammatory cytokines like IL-1B and IL-12p70 and those involved in eosinophil recruitment and activation, like Eotaxin-1 and IL-5. Finally, we utilize the SmCI-1 knockdown cercaria in a mouse model of infection, revealing a role for SmCI-1 in S. mansoni survival.

Effects of Schistosoma mansoni and praziquantel treatment on the lower gastrointestinal mucosa: A cohort study in Tanzania

Schistosomes infect over 200 million people worldwide, but few studies have characterized the effects of Schistosoma mansoni infection and effective treatment on the lower gastrointestinal mucosa. In this prospective cohort study, we compared the clinical findings on sigmoidoscopy and laboratory measures in Tanzanian adults with and without S. mansoni infection at baseline and 6 months after praziquantel treatment. Grading of the endoscopic findings was done using the Mayo Scoring System for Assessment of Ulcerative Colitis Activity. Schistosome infection was confirmed by stool microscopy and serum circulating anodic antigen (CAA). Baseline comparisons were performed in Stata using Fisher's exact and Wilcoxon rank-sum tests, and pre- and post-treatment comparisons using Wilcoxon matched-pairs signed-rank and McNemar's tests. We investigated the clinical characteristics of 48 individuals: 32 with and 16 without S. mansoni infection. Infected individuals had greater severity of sigmoid and rectal mucosal abnormalities and higher Mayo scores and serum eosinophils (all p < 0.05) than uninfected individuals at initial evaluation. At 6 months, 28 individuals completed repeat blood tests and sigmoidoscopy. Of these, 14 cleared their baseline infection (n = 7) or experienced a greater than 7-fold decrease in serum CAA (n = 7). Follow-up sigmoidoscopies revealed some improvements in sigmoid and rectal mucosal findings, although Mayo scores were not significantly lower. Both the median erythrocyte sedimentation rates (32.5→12.5 mm/hr) and percent of eosinophils (7.1→3.1%) decreased in this group from baseline to follow-up. S. mansoni infection was associated with mild-to-moderate lower gastrointestinal mucosal abnormalities that were grossly visible during sigmoidoscopy, and these improved partially 6 months after effective treatment with praziquantel. Additional studies, of longer duration and focused on both clinical and mucosal immunologic effects of S. mansoni, could provide additional insight.

Toxic, cytotoxic and genotoxic effect of plumbagin in the developmental stages of Biomphalaria glabrata (Say, 1818-intermediate host) and cercaricidal activity against the infectious agent of schistosomiasis mansoni

BACKGROUND

Snails of the genus Biomphalaria are intermediate hosts of Schistosoma mansoni, the main etiological agent of schistosomiasis mansoni, which affects about 236.6 million people in tropical and subtropical regions of the world. The World Health Organization recommends the population control of vector snails as one of the strategies to reduce the prevalence and incidence of schistosomiasis. In this study, molluscicidal and antiparasitic activities of plumbagin, a naturally sourced naphthoquinone with a range of biological effects, were evaluated against B. glabrata and cercariae of S. mansoni.

RESULTS

After 24 h of exposure, plumbagin demonstrated molluscicidal activity at low concentrations against embryos (LC₅₀ of 0.56, 0.93, 0.68, 0.51 and 0.74 μg mL^-1 for the blastula, gastrula, trochophore, veliger and hippo stage, respectively) and adult snails (LC₅₀ of 3.56 μg mL^-1 ). There were no changes in exposed snails' fecundity or fertility; however, plumbagin was able to increase the frequency of DNA damage and the number of hemocytes, with apoptosis and binucleation being the main hemocyte alterations. In addition, plumbagin showed death of S. mansoni cercariae in the concentration of 1.5 μg mL^-1 in 60 min, while showing moderate toxicity to Artemia salina.

CONCLUSION

Plumbagin proved to be a promising substance for the control of B. glabrata population, intermediate host of S. mansoni, as well as the cercariae, infective stage for humans (definitive host), while being moderately toxic to A. salina, a crustacean widely used in ecotoxicity tests. © 2022 Society of Chemical Industry.

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

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

Role of IL-17A in enhancing liver fibrosis induced by TGF-β1 and IL-13 in Schistosoma mansoni infected mice

Schistosoma mansoni liver fibrosis is a complicated multicellular process involving numerous cytokines, chemokines, and growth factors. Transforming growth factor beta 1 (TGF-1) and interleukin (IL)-13 have been identified as critical pro-fibrotic mediators in many studies. IL-17A was linked to enhanced TGF- and IL-13-induced pathologies. This case-control study aimed to explore the effect of IL-17A on TGF- and IL-13-induced liver fibrosis during experimentally schistosomiasis mansoni infection. A total of 40 laboratory-bred female C57BL/6 mice were divided into four equal groups (G), G1 non-infected, G2 infected wild type (WT), G3 infected/anti-IL-17 monoclonal antibodies (mAb) and G4 treated mice. Mice were infected percutaneously with 40±5 cercariae per mouse. Neutralizing IL-17 mAb was administered to G3 intraperitoneally 3 weeks after infection and then every third day until 2 days before sacrification; mice of G4 were treated with a single dose of praziquantel. Serum levels of TGF-, IL-13, IL-17A, and proinflammatory cytokines were measured by ELISA. Liver granulomas were identified by hematoxylin-eosin stain and measured by an ocular micrometer. There was a significantly increased serum concentration of TGF-, IL-13, and IL-17A in infected WT mice (P<0.01), but praziquantel treatment reduced cytokine levels (P<0.03). Neutralization of IL-17A activity remarkably reduced serum concentrations of TGF- and IL-13 (P <0.03) resulting in improved liver functions and reduced granuloma size. Secretion of IL-IL-6 and TNF-were markedly enhanced by infection, however, mice that received anti-mouse IL-17 mAb displayed fewer inflammatory mediators (P<0.03). In conclusion, IL-17A might contribute to the progress of liver fibrosis by enhancing the profibrotic effect of TGF- and IL-13 in mice infected with S. mansoni.

Experimental infection with Schistosoma mansoni isolated from the wild rodent Holochilus sciureus shows a low parasite burden but induces high schistosomiasis severity in BALB/c mice

Wild mammals, especially rodents, can participate in the life cycle of Schistosoma mansoni; however, the impact of these parasite strains on the severity of schistosomiasis remains unclear. The aim of this study was to comparatively evaluate the parasitological and immunopathological alterations induced by an S. mansoni strain isolated from the wild rodent Holochilus sciureus (HS strain) and a parasite strain isolated from a human (LE strain) in experimentally infected mice. Male BALB/c mice were subcutaneously infected with 50 cercariae/mouse of either the HS or the LE strain and were evaluated for 12 weeks. In the experimental groups, the parasite burden was estimated by worm and egg (feces and tissues) count, and immunopathological alterations were evaluated in the liver and intestines. Compared to experimental infection with the LE parasite strain, HS-infected mice showed reduced number of parasite worms but higher fecundity rate, significant reduction in IL-5, IL-10 and IL-13 concentrations, lower EPO-activity in liver homogenate and higher concentrations of TNF-α, IFN-γ, IL-12 and IL-17 in the small intestine homogenate. Moreover, HS infection resulted in higher concentrations of NO end-products in both the liver and intestine, suggesting a predominance of the Th1/Th17 immune response. HS-infected mice also showed higher plasma transaminase levels, formed larger granulomas, and had a higher mortality rate in comparison with LE-infected mice. Data indicate that BALB/c mice infected with the HS strain of S. mansoni showed reduced susceptibility to the parasite but stronger tissue inflammation and high disease severity.

Profiling the serum proteome during Schistosoma mansoni infection in the BALB/c mice: A focus on the altered lipid metabolism as a key modulator of host-parasite interactions

Schistosomiasis represents a condition in which every aspect of the disease, starting from skin invasion of the cercariae to egg laying by adult worms, incites a tissue response from the vertebrate host. This response, whether acute or chronic, leads to the appearance of reporter molecules of tissue injury in bodily fluids that could be surveyed as markers for disease diagnosis, status and prognosis. In this scenario, the serum proteome associated with a schistosome infection remains poorly explored; particularly by the use of high-throughput mass spectrometric instrumentation. In this study, we aimed to comparatively examine the serum proteome of control versus infected BALB/c mice, spanning the interval between the onset of egg laying and the peak of the acute phase of infection. Compositional analysis of the sera, using one dimensional reversed-phase fractionation of tryptic peptides coupled to mass spectrometry, allowed identification of 453 constituents. Among these, over 30% (143 molecules) were differentially present comparing sera from infected and non-infected mice, as revealed by quantitative label-free shotgun approach. The majority of proteins exhibiting altered levels was categorised as belonging to immune response (acute phase-related proteins) followed by those linked to lipid transport and metabolism. Inspection of the lipid profile from control and infected individuals demonstrated more pronounced and significant alterations in triglycerides, VLDL and HDL fractions (p<0,001), attesting for a disturbance in circulating lipid molecules, and suggesting a key role in host-parasite interactions. Our findings provide a global view of the serum proteome in the context of experimental schistosomiasis during the acute phase of infection. It contributes by listing key molecules that could be monitored to inform on the associated inflammatory disease status. We hope it will shed light into uncovered aspects of the Schistosoma mansoni parasitism in the vertebrate host, particularly those related to modulation of the lipid metabolism mediating immune responses.

Use of wogonin as a cooperative drug with praziquantel to better combat schistosomiasis

BACKGROUND

Schistosomiasis is one of the most devastating tropical diseases in the world. Currently, praziquantel (PZQ) represents the best pharmacological option for the treatment of schistosomiasis as it effectively kills the worm. However, the inability to reverse established liver damages often makes treatment futile. In the current study, we investigate whether combining the use of wogonin, a compound that was found to be liver-protective, with PZQ can attribute to the greatest beneficial effect in Schistosoma mansoni-infected mice.

METHODS

To determine the protective effect of PZQ-wogonin treatment on S. manosni-infected mice, histopathological analysis was done to evaluate the granuloma size and fibrotic areas in the liver. Western blotting was performed to analyze several injuries-related markers including fibrotic markers, inflammasomes, and apoptotic markers. Scanning electron microscopy was done to evaluate the effect of wogonin on the worms, and the worm and egg burden was calculated.

RESULTS

Our results showed that PZQ-wogonin treatment significantly improved liver histopathology of S. mansoni-infected mice. Further analysis showed that PZQ-wogonin combinations are more effective in reducing fibrosis, inflammation, and apoptosis in the liver than that of individual drug use. Furthermore, our results revealed that wogonin is anthelmintic; and it works better with PZQ in reducing hepatic egg burden, further lessen the disease progression.

CONCLUSION

In general, this combinatorial strategy may represent a new and effective approach to schistosomiasis treatment.

SmTAL-9, a Member of the Schistosoma mansoni Tegument Allergen-Like Family, Is Important for Parasite Survival and a Putative Target for Drug/Vaccine Development

The tegument of Schistosoma mansoni is involved in essential functions for parasite survival and is known to stimulate immune responses in pre-clinical vaccine trials. Smtal-9, a member of the tegument-allergen-like (TAL) family, is one of the components of the tegument of schistosomula recognized by sera from immunized and protected mice. In this work, we assessed the role of Smtal-9 in parasite survival using the RNAi approach. Also, we cloned and expressed a recombinant form of Smtal-9 and evaluated its ability to induce protection in mice. Smtal-9 knockdown did not impact parasite survival in vitro, but significantly decreased schistosomula size. Additionally, significant reduction in both parasite and egg burdens were observed in mice inoculated with Smtal-9-knockdown schistosomula. Immunization using the Smtal-9 as an antigen conferred partial protection against challenge infection. Overall, our results indicate that Smtal-9 is a candidate target for drug and/or vaccine development due to its important role in parasite biology and survival.

Dynamics of Host Immune Response Development During Schistosoma mansoni Infection

Schistosomiasis is a disease of global significance, with severity and pathology directly related to how the host responds to infection. The immunological narrative of schistosomiasis has been constructed through decades of study, with researchers often focussing on isolated time points, cell types and tissue sites of interest. However, the field currently lacks a comprehensive and up-to-date understanding of the immune trajectory of schistosomiasis over infection and across multiple tissue sites. We have defined schistosome-elicited immune responses at several distinct stages of the parasite lifecycle, in three tissue sites affected by infection: the liver, spleen, and mesenteric lymph nodes. Additionally, by performing RNA-seq on the livers of schistosome infected mice, we have generated novel transcriptomic insight into the development of schistosome-associated liver pathology and fibrosis across the breadth of infection. Through depletion of CD11c+ cells during peak stages of schistosome-driven inflammation, we have revealed a critical role for CD11c+ cells in the co-ordination and regulation of Th2 inflammation during infection. Our data provide an updated and high-resolution account of how host immune responses evolve over the course of murine schistosomiasis, underscoring the significance of CD11c+ cells in dictating host immunopathology against this important helminth infection.

Sex-Specific Modulation of the Host Transcriptome in the Spleen of Schistosoma mansoni-Infected Mice

Background

Schistosomiasis is a severe parasitic disease that is primarily driven by the host’s immune response to schistosome eggs trapped in tissue and by the granulomatous inflammatory and fibrotic reaction they cause. Despite significant progress in understanding the complex immunological processes involved in the relationship between schistosomes and their host, neither an effective vaccine against the infection nor anti-fibrotic drugs currently exists, making the search for new targets for schistosome drugs and vaccine candidates even more important. In order to identify new molecular targets for defense against or elimination of the parasite, we investigate herein the interplay between the host and male or female schistosomes, clearly separating this from the action of the parasite eggs.

Methods

For this purpose, we infected 6–8-week-old female NMRI mice with 100 male (M), female (F), or both (MF) S. mansoni cercariae and performed a comparative transcriptomic and flow cytometric analysis of their spleens.

Results

Principal component analysis of a total of 22,207 transcripts showed a clear clustering of the experimental groups. We identified a total of 1,293 genes in group M, 512 genes in group F, and 4,062 genes in group MF that were differentially expressed compared to naive controls. The highest percentage of regulated genes (2,972; 65.9%) was found in group MF alone, but there was a large overlap between groups M and MF (798; 17.7%) and a small overlap between groups F and MF (91; 2.0%). Only 4.5% of genes (201) were revealed to be regulated in all experimental groups (M/F/MF). In addition, we were able to show that both worm sexes trigger immune responses in an egg-independent manner (non-polarized Th1 and Th2 response), with female worms exerting less regulatory influence than males.

Conclusion

Our data show that adult schistosomes trigger sex-specific, egg-independent immune responses. The lists of genes regulated by adult female or male worms presented here may be useful in deciphering host–parasite interactions to identify targets for schistosome elimination.

Schistosoma mansoni miracidia: revisiting motility and survival parameters for improved computational modelling

Schistosoma mansoni is the main causative agent of intestinal schistosomiasis which affects millions of people worldwide. At the larval stage, miracidia are released into bodies of water where they utilize their motility to successfully infect their intermediate host, snails. Here, we revisit the motility and survival of S. mansoni miracidia throughout its life span. Briefly, miracidia motility was monitored at 30-min and 60-min intervals under the presence/absence of natural/artificial light. Based on a subjective evaluation of activity, body shape and transparency, 6 categories of miracidia activity were established from its fully active stage to its immobile larva stage. The estimated life span of miracidia was 5.8 and 3.5 h in the experiments with 60-min and 30-min observation intervals, respectively. Death was defined by an absence of cilia and body movement. When mobility was used as a proxy for infectivity, infective miracidia were detected at 2.5 and 4.5 h, respectively. The present miracidia motility and survival re-evaluation supports parameters optimization for computational modelling of schistosomiasis transmission dynamics. Target control interventions, especially at late stages next to transmission interruption, may greatly benefit from improved modelling studies.

Schistosoma mansoni infection induces plasmablast and plasma cell death in the bone marrow and accelerates the decline of host vaccine responses

Schistosomiasis is a potentially lethal parasitic disease that profoundly impacts systemic immune function in chronically infected hosts through mechanisms that remain unknown. Given the immunoregulatory dysregulation experienced in infected individuals, this study examined the impact of chronic schistosomiasis on the sustainability of vaccine-induced immunity in both children living in endemic areas and experimental infections in mice. Data show that chronic Schistosoma mansoni infection impaired the persistence of vaccine specific antibody responses in poliovirus-vaccinated humans and mice. Mechanistically, schistosomiasis primarily fostered plasmablast and plasma cell death in the bone marrow and removal of parasites following praziquantel treatment reversed the observed cell death and partially restored vaccine-induced memory responses associated with increased serum anti-polio antibody responses. Our findings strongly suggest a previously unrecognized mechanism to explain how chronic schistosomiasis interferes with an otherwise effective vaccine regimen and further advocates for therapeutic intervention strategies that reduce schistosomiasis burden in endemic areas prior to vaccination.

Schistosoma mansoni (S. mansoni), a schistosomiasis disease-causing parasite species, is most common in sub-Saharan Africa. Schistosoma mansoni can influence immune responses and trigger physiological imbalances in their human and animal hosts, which improve their survival and multiplication in the host. These influences can disrupt the host’s ability to maintain long term protective immunity mounted by vaccines for infectious diseases. Here, we investigated the impact of S. mansoni infection on poliovirus vaccine immunity in school-aged children and mice. We found that the parasite reduced its host’s ability to maintain protective blood antibodies produced by immune responses to poliovirus vaccines. We also found that S. mansoni infection reduces the maintenance of antibody-producing plasma cells in the bone marrow of vaccinated mice. Our data showed that treating S. mansoni infected children and mice with praziquantel mitigated the parasite’s negative influences on vaccine immunity. These findings suggest that in regions where schistosomiasis is endemic, the Schistosoma spp. parasites may be notable causes of suboptimal viral vaccine immunity maintenance by children, leaving them vulnerable to vaccine-preventable diseases.

High prevalence of urinary schistosomiasis in a desert population: results from an exploratory study around the Ounianga lakes in Chad

BACKGROUND

Researching a water-borne disease in the middle of the Sahara desert might not seem the most relevant concern. However, nomadic Sahelian pastoralists health concerns regarding their livestock and anecdotal reports about trematode infections of Fasciola spp. and Schistosoma spp. in desert-raised animals justified an exploratory study focusing on the lakes of Ounianga in Northern Chad. The aim was to test whether trematode parasites such as Schistosoma spp. occur in human populations living around the Sahara desert lakes of Ounianga Kebir and Ounianga Serir in northern Chad.

METHODS

The study was carried out in January 2019 and comprised of three components. First, a cross sectional survey based on a random sample drawn from the population to detect infections with S. haematobium and S. mansoni; second, focus group discussions exploring disease priorities, access to health and health seeking behaviour; and third, surveying water contact sites for intermediate host snails. Samples of trematode parasites and snails were confirmed on species level by molecular genetic methods. For parasitological and malacological surveys descriptive statistics were performed. Qualitative data analysis included the full review of all transcripts, followed by a descriptive and explorative thematic analysis.

RESULTS

Among 258 participants, the overall S. haematobium prevalence using urine filtration was 39.2% [95% confidence interval (CI): 33.5-45.1%], with 51.5% of the infected suffering from heavy infection. The intermediate host snail of S. haematobium (Bulinus truncatus) occurred at water contact sites near both study villages, revealing the potential for local transmission. Although a positive S. mansoni point-of-care circulating cathodic antigen (POC-CCA) test result was obtained from 8.6% (95% CI 5.7-12.8%) of the samples, no intermediate host snails of S. mansoni were found, and the relevance of S. mansoni remains uncertain. Qualitative findings underline the importance of morbidity caused by urinary schistosomiasis, and the lack of access to diagnostics and treatment as a major health concern.

CONCLUSIONS

This research revealed a high prevalence of urinary schistosomiasis in the population living around the lakes of Ounianga in the Sahara, a United Nations Educational, Scientific and Cultural Organization (UNESCO) world heritage site in Chad. Despite the high public health importance of the associated morbidity expressed by the population, there is no access to diagnostics and treatment. Further work is needed to develop and test a context-adapted intervention.

The effect of fs800 on female egg production in Schistosoma mansoni

During schistosomiasis, the paired Schistosoma mansoni female produces about 300 eggs each day. These eggs are responsible for the clinical picture and the transmission of the disease. During female development and egg production, fs800 is expressed only in female vitelline cells. Blast search of fs800 did not show similarities with any published sequences by NCBI. We hypothesize that the product of this gene plays a role in S. mansoni egg production. By using RNA interference to knockdown fs800 and quantitative PCR to measure the gene expression in the female schistosomes, we were able to demonstrate that fs800 product is crucial for viable egg production, it has no effect on worm health or male-female pairing. Our data suggest fs800 inhibition as a potential target to prevent transmission and pathology of schistosomiasis.

Modelling the present and future distribution of Biomphalaria species along the watershed of the Middle Paranapanema region, São Paulo, Brazil

The Middle Paranapanema region in the state of São Paulo, Brazil, is an area with high diversity for Biomphalaria species, with municipalities historically marked by cases of schistosomiasis transmission. The objectives of the study were to evaluate the current distribuition and predict the future distribution of habitats of Biomphalaria species at a high spatial resolution along 114 freshwater sites in the Middle Paranapanema watershed. The modelling encompassed 55 municipalities of the Middle Paranapanema region, which were analyzed through the maximum entropy algorithm. All geographic coordinates of the Biomphalaria species collected from 2015-2018 and environmental data were obtained through WorldClim, HydroSHEDS, TOPODATA and Secretaria do Meio Ambiente for the 1970-2017 period. For the 2041-2060 period we used the HadGEM2-ES climate model. Due to climate change, MaxEnt showed that there was a high probability for the maintenance of B. glabrata habitats near Ourinhos and Assis, an expansion of scattered spots, and a 50% probability that the species will spread throughout new suitable areas. The results showed that the geographical range of B. straminea will most likely expand in the future along the Middle Paranapanema hydrographic basin, especially in the municipalities near Ourinhos. For B. glabrata and B. straminea, the geographic expansion was related to the predicted increase in the annual temperature range. The habitats suitable for B. tenagophila and B. peregrina seemed to slightly expand around the west border of the Middle Paranapanema region. Biomphalaria occidentalis may have a small reduction in its distribution due to climate change. The variables that contributed the most to the future modelling for these three species were precipitation and temperature. Identifying the sites with intermediate hosts for schistosomiasis may guide public health measures to avoid or reduce future transmissions in this region.

Liver damage in schistosomiasis is reduced by adipose tissue-derived stem cell therapy after praziquantel treatment

Background

In view of the potential immunosuppressive and regenerative properties of mesenchymal stem cells (MSC), we investigated whether transplantation of adipose tissue-derived stem cells (ASC) could be used to control the granulomatous reaction in the liver of mice infected with Schistosoma mansoni after Praziquantel (PZQ) treatment.

Methodology/Prinicpal findings

C57BL/6 mice infected with S. mansoni were treated with PZQ and transplanted intravenously with ASC from uninfected mice. Liver morpho-physiological and immunological analyses were performed. The combined PZQ/ASC therapy significantly reduced the volume of hepatic granulomas, as well as liver damage as measured by ALT levels. We also observed that ASC accelerated the progression of the granulomatous inflammation to the advanced/curative phase. The faster healing interfered with the expression of CD28 and CTLA-4 molecules in CD4⁺ T lymphocytes, and the levels of IL-10 and IL-17 cytokines, mainly in the livers of PZQ/ASC-treated mice.

Conclusions

Our results show that ASC therapy after PZQ treatment results in smaller granulomas with little tissue damage, suggesting the potential of ASC for the development of novel therapeutic approaches to minimize hepatic lesions as well as a granulomatous reaction following S. mansoni infection. Further studies using the chronic model of schistosomiasis are required to corroborate the therapeutic use of ASC for schistosomiasis.

Schistosomiasis is the second most prevalent parasitic disease in the world and is caused by the Schistosoma trematode. This disease is characterized by a granulomatous reaction around parasite eggs trapped in the tissues. The liver is one of the most affected organs and can develop severe fibrosis. Praziquantel (PZQ) is the treatment for schistosomiasis and kills the adult the worm; however, inflammation still persists around the eggs in the tissues. Mesenchymal stem cells (MSC) have been extensively studied as an alternative therapy to repair tissues and to stop inflammation due to their potential to differentiate in several cells types (bone, cartilage, fat, tendon, muscle, and marrow stroma), and to interfere with immune responses. This scenario has motivated the authors to investigate the use of MSC extract from adipose tissue (ASC) associated with PZQ to treat schistosomiasis. Briefly, mice were treated with PZQ followed by ASC injection showing significant reduction of the granulomas and normal levels of the enzyme alanine aminotransferase, an indicator of liver damage. These results suggest that ASC has the potential to be used as a novel therapeutic approach to control inflammation following infection by S. mansoni or liver disorders. Although the findings are promising, further studies using the chronic model of schistosomiasis are required to confirm using ASC for schistosomiasis therapy.

Fifteen Years of Sm-p80-Based Vaccine Trials in Nonhuman Primates: Antibodies From Vaccinated Baboons Confer Protection in vivo and in vitro From Schistosoma mansoni and Identification of Putative Correlative Markers of Protection

Recent advances in systems biology have shifted vaccine development from a largely trial-and-error approach to an approach that promote rational design through the search for immune signatures and predictive correlates of protection. These advances will doubtlessly accelerate the development of a vaccine for schistosomiasis, a neglected tropical disease that currently affects over 250 million people. For over 15 years and with contributions of over 120 people, we have endeavored to test and optimize Sm-p80-based vaccines in the non-human primate model of schistosomiasis. Using RNA-sequencing on eight different Sm-p80-based vaccine strategies, we sought to elucidate immune signatures correlated with experimental protective efficacy. Furthermore, we aimed to explore the role of antibodies through in vivo passive transfer of IgG obtained from immunized baboons and in vitro killing of schistosomula using Sm-p80-specific antibodies. We report that passive transfer of IgG from Sm-p80-immunized baboons led to significant worm burden reduction, egg reduction in liver, and reduced egg hatching percentages from tissues in mice compared to controls. In addition, we observed that sera from Sm-p80-immunized baboons were able to kill a significant percent of schistosomula and that this effect was complement-dependent. While we did not find a universal signature of immunity, the large datasets generated by this study will serve as a substantial resource for further efforts to develop vaccine or therapeutics for schistosomiasis.

Zinc oxide nanoparticles and L-carnitine effects on neuro-schistosomiasis mansoni induced in mice

Neuro-schistosomiasis can induce neurological symptoms and severe disability. Since the resistance against the chemotherapy "praziquantel" was reported, the aim of the present study was investigating the anti-neuro-schistosomal effects of ZnO nanoparticles and/or L-carnitine (as free radicals scavenger) on schistosome-infected mice, where technology of nanoparticles has come to the forefront in the medical diagnosis and therapeutic drug delivery. In the human body, nanoscale-sized particles can move freely and reveal unique biological, mechanical, electrical, and chemical properties. In the present study, mice were divided into five groups. The first group served as the non-infected control group. Groups II, III, IV, and V were infected with cercariae of Schistosoma mansoni. Mice of groups III and IV were treated with ZnO nanoparticles (5.6 mg/kg b. wt.) and L-carnitine (500 mg/kg b. wt.), respectively, after 47 days post-infection. Finally, mice of the fifth group were injected with ZnO nanoparticles and after 1 h, the mice were intraperitoneally injected with L-carnitine once daily for 5 days. On day 52, post-infection mice of all groups were cervically decapitated. The treatment of ZnO nanoparticles and/or L-carnitine to schistosome-infected mice decreased brain oxidative stress parameters, where glutathione level and catalase activity were significantly increased as compared to schistosome-infected group. On the contrary, the treatment decreased nitrite/nitrate, malondialdehyde, and reactive oxygen species levels significantly. In addition, ZnO nanoparticles and/or L-carnitine treatment restored DNA laddering profile and improved the brain histopathological impairments resulting from neuro-schistosomiasis. Finally, the ZnO nanoparticle treatment and the co-treatment of ZnO nanoparticles and L-carnitine revealed anti-neuro-schistosomal effects on the infected mice.

Comparison of ELISA and Urine Microscopy for Diagnosis of Schistosoma haematobium Infection

BACKGROUND

Schistosoma haematobium which causes urogenital schistosomiasis (UGS) is highly prevalent in African countries. Urine microscopy (UM) is the first-line diagnostic method of UGS. Enzyme-linked immunosorbent assay (ELISA) is a common method for screening many parasite infections primarily or alternatively. The present study established an in-house diagnostic system by ELISA and evaluated its diagnostic efficacy in comparison with UM for screening UGS in White Nile State, Republic of Sudan, 2011-2013.

METHODS

A total of 490 participants were screened by UM or ELISA, and 149 by both. The in-house ELISA system was established employing soluble egg antigen of S. haematobium and the cut-off absorbance was set at 0.270.

RESULTS

Of the 149 subjects, 58 participants (38.9%) were positive by UM, 119 (79.9%) were positive by ELISA and 82 (55.0%) showed consistently positive or negative results by both methods. The diagnostic sensitivity of ELISA was 94.8% and specificity was 29.7% based on UM results. The ELISA positive serum samples also cross-reacted with egg antigens of Schistosoma mansoni and Schistosoma japonicum.

CONCLUSION

We have established in-house ELISA for screening serum immunoglobulin (Ig) G antibodies by employing soluble egg antigen of S. haematobium for diagnosis of UGS with 94.8% sensitivity and 29.7% specificity. The ELISA system can supplement the conventional diagnosis by UM.

Spatio-temporal dynamics of schistosomiasis in Rwanda between 2001 and 2012: impact of the national Neglected Tropical Disease control programme

Schistosomiasis is recognised as a major public health problem in Rwanda. We aimed to identify the spatio-temporal dynamics of its distribution at a fine-scale spatial resolution and to explore the impact of control programme interventions. Incidence data of Schistosoma mansoni infection at 367 health facilities were obtained for the period 2001-2012. Disease cluster analyses were conducted using spatial scan statistics and geographic information systems. The impact of control interventions was assessed for three distinct sub-periods. Findings demonstrated persisting, emerging and re-emerging clusters of schistosomiasis infection across space and time. The control programme initially caused an abrupt increase in incidence rates during its implementation phase. However, this was followed by declining and disappearing clusters when the programme was fully in place. The findings presented should contribute to a better understanding of the dynamics of schistosomiasis distribution to be used when implementing future control activities, including prevention and elimination efforts.

A Miniaturized Screen of a Schistosoma mansoni Serotonergic G Protein-Coupled Receptor Identifies Novel Classes of Parasite-Selective Inhibitors

Schistosomiasis is a tropical parasitic disease afflicting ~200 million people worldwide and current therapy depends on a single drug (praziquantel) which exhibits several non-optimal features. These shortcomings underpin the need for next generation anthelmintics, but the process of validating physiologically relevant targets (‘target selection’) and pharmacologically profiling them is challenging. Remarkably, even though over a quarter of current human therapeutics target rhodopsin-like G protein coupled receptors (GPCRs), no library screen of a flatworm GPCR has yet been reported. Here, we have pharmacologically profiled a schistosome serotonergic GPCR (Sm.5HTR) implicated as a downstream modulator of PZQ efficacy, in a miniaturized screening assay compatible with high content screening. This approach employs a split luciferase based biosensor sensitive to cellular cAMP levels that resolves the proximal kinetics of GPCR modulation in intact cells. Data evidence a divergent pharmacological signature between the parasitic serotonergic receptor and the closest human GPCR homolog (Hs.5HTR7), supporting the feasibility of optimizing parasitic selective pharmacophores. New ligands, and chemical series, with potency and selectivity for Sm.5HTR over Hs.5HTR7 are identified in vitro and validated for in vivo efficacy against schistosomules and adult worms. Sm.5HTR also displayed a property resembling irreversible inactivation, a phenomenon discovered at Hs.5HTR7, which enhances the appeal of this abundantly expressed parasite GPCR as a target for anthelmintic ligand design. Overall, these data underscore the feasibility of profiling flatworm GPCRs in a high throughput screening format competent to resolve different classes of GPCR modulators. Further, these data underscore the promise of Sm.5HTR as a chemotherapeutically vulnerable node for development of next generation anthelmintics.

Parasitic flatworms express a diverse array of G protein coupled receptors, but our knowledge of their pharmacological profile is limited. No high throughput screen of a flatworm GPCR has been reported, even though these targets have precedent for high druggability and functionality in the chemotherapeutically vulnerable excitable cell niche. The goal of this study was to establish a method for profiling flatworm G protein coupled receptors that can be scaled to high content screening. Using a cAMP biosensor, we have performed a proof of principle miniaturized screen on a schistosome serotonergic GPCR that resolves new ligands that potently and selectivity block 5-HT receptor activity in vitro, and 5-HT evoked responses in schistosomules and adult worms. This approach evidences the pharmacological divergence of a parasitic GPCR from the closest human homolog and a capacity for high content interrogation of flatworm GPCR properties and ligand specificities.

In vitro and in vivo anthelmintic activity of (-)-6,6'-dinitrohinokinin against schistosomula and juvenile and adult worms of Schistosoma mansoni

The chemotherapy of schistosomiasis relies on the use of praziquantel. However, concerns over drug resistance have encouraged the search for new drug leads. This paper is the first report on the in vitro and in vivo activity of (-)-6,6'-dinitrohinokinin (DNK) against Schistosoma mansoni. In vitro, the lethal concentrations for 50% of parasites (LC50) of DNK against adult worms were 103.9±3.6 and 102.5±4.8μM at 24 and 72h, respectively. Scanning electron microscopy images showed extensive tegumental alterations such as peeling and smaller numbers of tubercles in the spine of adult worms. DNK also elicited high mortality of schistosomula, with LC50 values of 57.4±2.3, 32.5±0.9, and 20.4±1.2μM at 24, 48, and 72h, respectively. DNK displayed moderate activity against the juvenile liver parasite, with an LC50 value of 179.5±2.3 μM at 72h. This compound reduced the total number of eggs by over 83%, and it affected the development of eggs produced by adult worms. The selectivity index showed that at 24h, DNK was 8.5 and 15.4 times more toxic to the adult worms and schistosomula than to Chinese hamster lung fibroblast cells, respectively. Treatment of infected mice with DNK moderately decreased worm burden (33.8-52.3%), egg production (40.7-60.0%), and spleen and liver weights. Together, our results indicated that DNK presents moderate in vitro and in vivo activities against S. mansoni, and it might therefore be interesting to explore the structure-activity relationship of the antischistosomal activity of this compound.

Terminal ileum schistosomiasis with perianal fistula mimicking Crohn's disease

Schistosomiasis is a parasitic disease related to water contact in the agricultural fields, affecting millions of people in developing countries in tropical and subtropical parts of Africa, Asia, and South America. We report a case of a 27-year-old male, with intestinal schistosomiasis associated with perianal fistula mimicking Crohn's disease, where the terminal ileum showed a cobblestone appearance, and histopathological biopsy showed schistosoma granuloma.

Helminth communities of Nectomys squamipes naturally infected by the exotic trematode Schistosoma mansoni in southeastern Brazil

The water rat Nectomys squamipes is endemic in Brazil and found naturally infected with Schistosoma mansoni. Helminth communities, their prevalences, intensity of infection and abundance in N. squamipes in an endemic area of schistosomiasis in the state of Rio de Janeiro, Brazil were studied. Four species of nematodes (Physaloptera bispiculata, Syphacia venteli, Hassalstrongylus epsilon and Litomosoides chagasfilhoi) were recovered in 85.3%, two trematodes (Schistosoma mansoni and Echinostoma paraensei) in 38.8% and one cestode species (Raillietina sp.) in 1.7% of rats examined. Rats were infected with up to five helminth species each, and these were highly aggregated in distribution. For H. epsilon and S. venteli, intensities and abundances were higher in adult male and subadult female hosts, respectively. Hassaltrongylus epsilon, P. bispiculata, S. venteli and S. mansoni were classified as dominant species, L. chagasfilhoi and E. paraensei as co-dominant and Raillietina sp. as subordinated. No significant correlation was found in the intensity of infecton between each pair of helminth species. Schistosoma mansoni was not related to any other helminth species according to their infection rates, althougth S. mansoni was well established in the natural helminth comunity of the water rat.

Contrasting patterns in the small-scale heterogeneity of human helminth infections in urban and rural environments in Brazil

Marked heterogeneity exists in the patterns of parasitic infection between individuals, households and communities. Analysis of parasite distributions within populations is complicated by the fact that parasite distributions are highly aggregated and few studies have explicitly incorporated this distribution when investigating small-scale spatial heterogeneities. This study aimed to quantify the small-scale (within- and between-household) heterogeneity of helminth infection in an area of Minas Gerais State, Brazil, with rural and urban sectors. Parasitological data from a cross-sectional survey of 1,249 individuals aged 0-86 years from 242 households were analysed. Within-household clustering of infection was assessed using random effect logistic regression models and between-household spatial heterogeneity was assessed using a Bayesian negative binomial spatial model. The overall prevalence of hookworm (Necator americanus) was 66.9%, the prevalence of Schistosoma mansoni was 44.9% and the prevalence of Ascaris lumbricoides was 48.8%. Statistical analysis indicated significant (within) household and (between household) spatial clustering of hookworm in both rural and urban areas and of S. mansoni in rural areas. There was no evidence of either household or spatial clustering of S. mansoni in urban areas. The spatial correlation of S. mansoni was estimated to reduce by half over a distance of 700 m in the rural area. Rural hookworm had a much smaller half-distance (28 m) and urban hookworm showed an even smaller half-distance (12 m). We suggest that such species-specific differences in patterns of infection by environment are primarily due to variation in exposure and parasite life cycle, although host genetic factors cannot be ruled out.

Study of gamma-interferon in schistosomiasis mansoni, autoimmune diseases and schistosomal arthropathy

IFN-gamma, a Th1 cytokine was quantitatively estimated using EASIA in the sera of patients with different stages of schistosomiasis mansoni autoimmune diseases and schistosomal arthropathy. Level of IFN-gamma was significantly elevated in all the test groups compared to the control group. The highest level of IFN-gamma observed was in RA and SLE, with insignificant statistical difference (P > 0.05) between them. Cases with early S. mansoni infection showed significant higher level (P < 0.05) of IFN-gamma compared to hepatosplenic schistosomiasis with and without ascites. A significant statistical difference (P < 0.05) concerning IFN-gamma level was observed when comparing RA and SLE to different stages of S. mansoni infection and schistosomal arthropathy. This might lead to a conclusion that IFN-gamma estimation in sera of patients having joint complaint could be a good marker for differentiation between autoimmune collagen induced arthritis and schistosomiasis induced arthropathy.

Anti-inflammatory properties of molecular hydrogen: investigation on parasite-induced liver inflammation

Molecular hydrogen reacts with the hydroxyl radical, a highly cytotoxic species produced in inflamed tissues. It has been suggested therefore to use gaseous hydrogen in a new anti-inflammatory strategy. We tested this idea, with the aid of the equipment and skills of COMEX SA in Marseille, a group who experiments with oxygen-hydrogen breathing mixtures for professional deep-sea diving. The model used was schistosomiasis-associated chronic liver inflammation. Infected animals stayed 2 weeks in an hyperbaric chamber in a normal atmosphere supplemented with 0.7 MPa hydrogen. The treatment had significant protective effects towards liver injury, namely decreased fibrosis, improvement of hemodynamics, increased NOSII activity, increased antioxidant enzyme activity, decreased lipid peroxide levels and decreased circulating TNF-alpha levels. Under the same conditions, helium exerted also some protective effects, indicating that hydroxyl radical scavenging is not the only protective mechanism. These findings indicate that the proposed anti-inflammatory strategy deserves further attention.

Gastrointestinal complications of schistosomiasis

Schistosomiasis is an important disease in many parts of the world and has affected the course of human history many times over. The parasitic infection is acquired during contact with infected water. A chronic inflammatory response to schistosome eggs, mediated by both cellular and humoral mechanisms, is the root of the pathology seen in schistosomiasis. Hepatosplenic disease results in intrahepatic presinusoidal portal hypertension. The resultant esophageal and gastric varices are an important cause of morbidity and mortality. Standard treatment guidelines for managing varices can be applied to patients with schistosomiasis. Coinfection with viral hepatitis results in liver disease that progresses more rapidly and is more difficult to treat. Intestinal schistosomiasis may be confused with other disease states and can be an important cause of morbidity, especially in heavily infected patients. Diagnosis relies on demonstration of schistosome eggs in feces or tissue. Praziquantel is the treatment of choice. The development of a vaccine for schistosomiasis is an important goal in the attempt to control this disease.

Lower faecal egg excretion in chemically-induced diabetic mice infected with Schistosoma mansoni due to impaired egg maturation

The effect of streptozotocin-induced diabetes mellitus was studied in mice infected with Schistosoma mansoni. Faecal egg excretion was lower in diabetic mice but worm load and total amount of eggs in the intestine tissue were equal to the control group. Evaluation of an oogram showed a great number of immature dead eggs and a low number of mature eggs in diabetic mice. It was therefore concluded that faecal egg excretion was lower in diabetic mice due to impaired egg maturation.