Vaccination with Schistosoma mansoni Cholinesterases Reduces the Parasite Burden and Egg Viability in a Mouse Model of Schistosomiasis

Schistosomiasis is a neglected tropical disease caused by parasitic blood flukes of the genus Schistosoma, which kills 300,000 people every year in developing countries, and there is no vaccine. Recently, we have shown that cholinesterases (ChEs)—enzymes that regulate neurotransmission—from Schistosoma mansoni are expressed on the outer tegument surface and present in the excretory/secretory products of larval schistosomula and adult worms, and are essential for parasite survival in the definitive host, highlighting their utility as potential schistosomiasis vaccine targets. When treated in vitro with anti-schistosome cholinesterase (SmChE) IgG, both schistosomula and adult worms displayed significantly decreased ChE activity, which eventually resulted in parasite death. Vaccination with individual SmChEs, or a combination of all three SmChEs, significantly reduced worm burdens in two independent trials compared to controls. Average adult worm numbers and liver egg burdens were significantly decreased for all vaccinated mice across both trials, with values of 29–39% and 13–46%, respectively, except for those vaccinated with SmAChE1 in trial 1. Egg viability, as determined by egg hatching from liver homogenates, was significantly reduced in the groups vaccinated with the SmChE cocktail (40%) and SmAChE2 (46%). Furthermore, surviving worms from each vaccinated group were significantly stunted and depleted of glycogen stores, compared to controls. These results suggest that SmChEs could be incorporated into a vaccine against schistosomiasis to reduce the pathology and transmission of this debilitating disease.

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Vaccination with Schistosoma mansoni cholinesterases reduces parasite burden and egg viability in a mouse model of schistosomiasis

10.1101/2020.01.28.922732 ◽

2020 ◽

Author(s):

Bemnet A. Tedla ◽

Darren Pickering ◽

Luke Becker ◽

Alex Loukas ◽

Mark S. Pearson

Keyword(s):

Schistosoma Mansoni ◽

Parasite Burden ◽

Egg Viability ◽

Egg Hatching ◽

Parasite Survival ◽

Liver Homogenates ◽

Secretory Products ◽

Glycogen Stores ◽

Independent Trials

AbstractSchistosomiasis is a neglected tropical disease which kills 300,000 people every year in developing countries and there is no vaccine. Recently, we have shown that cholinesterases (ChEs) - enzymes that regulate neurotransmission - from Schistosoma mansoni are expressed on the tegument and present in the excretory/secretory products of schistosomula and adult worms, and are essential for parasite survival in the definitive host, highlighting their utility as potential schistosomiasis vaccine targets. When treated in vitro with anti-SmChE IgG, both schistosomula and adult worms displayed significantly decreased ChE activity, which eventually resulted in parasite death. Vaccination with individual SmChEs, or a combination of all three SmChEs, significantly reduced worm burdens in two independent trials compared to controls. Liver egg burdens were significantly decreased for all vaccinated mice across both trials (13% - 46%) except for those vaccinated with SmAChE1 in trial 1. Egg viability, as determined by egg hatching from liver homogenates, was significantly reduced in the groups vaccinated with the SmChE cocktail (40%) and SmAChE2 (46%). Further, surviving worms from each vaccinated group were significantly stunted and depleted of glycogen stores, compared to controls. These results suggest that SmChEs could be incorporated into a vaccine against schistosomiasis to reduce the pathology and transmission of this debilitating disease.

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Structure-Reactivity Relationships on Substrates and Inhibitors of the Lysine Deacylase Sirtuin 2 from Schistosoma Mansoni (SmSirt2)

10.26434/chemrxiv.7957544 ◽

2019 ◽

Cited By ~ 1

Author(s):

Daria Monaldi ◽

Dante Rotili ◽

Julien Lancelot ◽

Martin Marek ◽

Nathalie Wössner ◽

...

Keyword(s):

Schistosoma Mansoni ◽

Human Cancer ◽

Egg Laying ◽

Human Cancer Cells ◽

Parasite Survival ◽

Survival And Reproduction ◽

Emergence Of Resistance ◽

First Time ◽

Parasitic Life Cycle

The only drug for treatment of Schistosomiasis is Praziquantel, and the possible emergence of resistance makes research on novel therapeutic agents necessary. Targeting of Schistosoma mansoni epigenetic enzymes, which regulate the parasitic life cycle, emerged as promising approach. Due to the strong effects of human Sirtuin inhibitors on parasite survival and reproduction, Schistosoma sirtuins were postulated as therapeutic targets. In vitro testing of synthetic substrates of S. mansoni Sirtuin 2 (SmSirt2) and kinetic experiments on a myristoylated peptide demonstrated lysine long chain deacylation as an intrinsic SmSirt2 activity for the first time. Focused in vitro screening of the GSK Kinetobox library and structure-activity relationships (SAR) of identified hits, led to the first SmSirt2 inhibitors with activity in the low micromolar range. Several SmSirt2 inhibitors showed potency against both larval schistosomes (viability) and adult worms (pairing, egg laying) in culture without general toxicity to human cancer cells.

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Studies with tryptophan metabolites in vitro. Kynurenine metabolism in liver homogenates of normal and Schistosoma mansoni-infested mice

Biochemical Journal ◽

10.1042/bj1040656 ◽

1967 ◽

Vol 104 (2) ◽

pp. 656-662 ◽

Cited By ~ 8

Author(s):

MS Amer ◽

MH Abdel-Daim ◽

GA Abdel-Tawab

Keyword(s):

Schistosoma Mansoni ◽

Tryptophan Metabolites ◽

Kynurenine Metabolism ◽

Liver Homogenates

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Structure-Reactivity Relationships on Substrates and Inhibitors of the Lysine Deacylase Sirtuin 2 from Schistosoma Mansoni (SmSirt2)

10.26434/chemrxiv.7957544.v1 ◽

2019 ◽

Author(s):

Daria Monaldi ◽

Dante Rotili ◽

Julien Lancelot ◽

Martin Marek ◽

Alessia Lucidi ◽

...

Keyword(s):

Schistosoma Mansoni ◽

Human Cancer ◽

Egg Laying ◽

Standard Drug ◽

Human Cancer Cells ◽

Parasite Survival ◽

Survival And Reproduction ◽

Emergence Of Resistance ◽

Parasitic Life Cycle

The standard drug for treatment of the neglected disease Schistosomiasis is Praziquantel, and the possible emergence of resistance to this treatment makes the research on novel therapeutic agents necessary and urgent. To this end, the targeting of Schistosoma mansoni epigenetic enzymes, which regulate the parasitic life cycle, emerged as promising approach. Due to strong effects of human Sirtuin inhibitors on parasite survival and reproduction, Schistosoma sirtuins were postulated as potential therapeutic targets. In vitro testing of synthetic substrates of SmSirt2 and kinetic experiments on a myristoylated peptide newly demonstrated lysine long chain deacylation as an intrinsic SmSirt2 activity in addition to the known deacetylation. Focused in vitro screening of the GSK Kinetobox library and structure-activity relationships (SAR) of identified hits, led to the first SmSirt2 inhibitors with activity in the low micromolar range. Several SmSirt2 inhibitors showed potency against both larval schistosomes (viability) and adult worms (pairing, egg laying) in culture without general toxicity to human cancer cells.

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In vitro Effect of Larval Schistosoma mansoni Excretory-Secretory Products on Phagocytosis-Stimulated Superoxide Production in Hemocytes from Biomphalaria glabrata

Journal of Parasitology ◽

10.2307/3282811 ◽

1990 ◽

Vol 76 (6) ◽

pp. 895 ◽

Cited By ~ 50

Author(s):

Vincent A. Connors ◽

Timothy P. Yoshino

Keyword(s):

Schistosoma Mansoni ◽

Biomphalaria Glabrata ◽

Superoxide Production ◽

Secretory Products ◽

Vitro Effect

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Ameliorative effects of Schisandrin B on Schistosoma mansoni-induced hepatic fibrosis in vivo

PLoS Neglected Tropical Diseases ◽

10.1371/journal.pntd.0009554 ◽

2021 ◽

Vol 15 (6) ◽

pp. e0009554

Author(s):

Ho Yin Pekkle Lam ◽

Ting-Ruei Liang ◽

Shih-Yi Peng

Keyword(s):

Liver Fibrosis ◽

Schistosoma Mansoni ◽

Egg Production ◽

Treatment Options ◽

Parasite Burden ◽

Inflammasome Activation ◽

Schisandrin B ◽

Male Adult

Schistosomiasis is second only to malaria as the most devastating parasitic disease in the world. It is caused by the helminths Schistosoma mansoni (S. mansoni), S. haematobium, or S. japonicum. Typically, patients with schistosomiasis suffer from symptoms of liver fibrosis and hepatosplenomegaly. Currently, patients were treated with praziquantel. Although praziquantel effectively kills the worm, it cannot prevent re-infection or resolve liver fibrosis. Also, current treatment options are not ample to completely cure liver fibrosis and splenic damages. Moreover, resistance of praziquantel has been reported in vivo and in vitro studies. Therefore, finding new effective treatment agents is urgently needed. Schisandrin B (Sch B) of Schisandra chinensis has been shown to protect against different liver injuries including fatty liver disease, hepatotoxicity, fibrosis, and hepatoma. We herein investigate the potential of using Sch B to treat S. mansoni-induced liver fibrosis. Results from the present study demonstrate that Sch B is beneficial in treating S. mansoni-induced liver fibrosis and splenic damages, through inhibition of inflammasome activation and apoptosis; and aside from that regulates host immune responses. Besides, Sch B treatment damages male adult worm in the mice, consequently helps to reduce egg production and lessen the parasite burden.

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Synthesis and degradation of glycogen by Schistosoma mansoni worms in vitro

Parasitology ◽

10.1017/s0031182000059692 ◽

1989 ◽

Vol 98 (1) ◽

pp. 67-73 ◽

Cited By ~ 9

Author(s):

A. G. M. Tielens ◽

C. Celik ◽

J. M. Van Den Heuvel ◽

R. H. Elfring ◽

S. G. Van Den Bergh

Keyword(s):

Schistosoma Mansoni ◽

Glycogen Content ◽

Glycogen Synthesis ◽

Krebs Cycle ◽

Glycogen Metabolism ◽

Mammalian Host ◽

Initial Reduction ◽

Glycogen Stores ◽

Synthesis And Degradation

SummaryThe glycogen stores of adult Schistosoma mansoni worms could be labelled by incubation of the worms, after an initial reduction of their glycogen content, in the presence of [6-14C]glucose. Subsequent breakdown of the labelled glycogen by the parasite revealed that glycogen was degraded to lactate and carbon dioxide. The degradation of glycogen, as compared to that of glucose, resulted in slightly different ratios of these two end-products. This indicates that glycogen breakdown did not replace glucose breakdown to the same extent in all cells and that Krebs-cycle activity was not uniformly distributed throughout the cells of this parasite. Both fructose and mannose could replace glucose as an energy source and the rate of glycogen synthesis from either of these two carbohydrates was higher than from glucose. No indications for glyconeogenesis from C3-units were found. Glycogen metabolism of S. mansoni was not influenced by hormones of the mammalian host. It is regulated by the external glucose concentration and by the level of the endogenous glycogen stores. Studies on paired and unpaired worms showed that no interaction between male and female was necessary for the synthesis of glycogen by female worms.

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Vaccination against the digestive enzyme Cathepsin B using a YS1646Salmonella entericaTyphimurium vector provides almost complete protection againstSchistosoma mansonichallenge in a mouse model

10.1101/652644 ◽

2019 ◽

Author(s):

Adam S Hassan ◽

Nicholas H Zelt ◽

Dilhan J Perera ◽

Momar Ndao ◽

Brian J Ward

Keyword(s):

Schistosoma Mansoni ◽

Cathepsin B ◽

Oral Vaccine ◽

Digestive Enzyme ◽

Parasite Burden ◽

Complete Protection ◽

Intramuscular Dose ◽

Serum Igg

AbstractSchistosoma mansonithreatens hundreds of millions of people in >50 countries. Schistosomulae migrate through the lung and adult worms reside adjacent to the intestinal mucosa. None of the candidate vaccines in current development is designed to elicit a mucosal response. We have repurposed an attenuatedSalmonella entericaTyphimurium strain (YS1646) to produce such a vaccine targeting Cathepsin B (CatB), a digestive enzyme important for parasite survival. Promoter-Type 3 secretory signal pairs were screened for protein expressionin vitroand transfected into YS1646 to generate candidate vaccine strains. Two strains were selected forin vivoevaluation (nirB_SspH1 and SspH1_SspH1). Female C57BL/6 mice were immunized twice, 3 weeks apart, using six strategies: i) saline gavage (control), ii) the ‘empty’ YS1646 vector orally (PO) followed by intramuscular recombinant CatB (20μg IM rCatB), iii) two doses of IM rCatB, iv) two PO doses of YS1646-CatB, v) IM rCatB then PO YS1646-CatB and vi) PO YS1646-CatB then IM rCatB. Serum IgG responses to CatB were monitored by ELISA. Three weeks after the second dose, mice were challenged with 150 cercariae and sacrificed 7 weeks later to assess adult worm and egg burden (liver and intestine), granuloma size and egg morphology. CatB-specific IgG antibodies were low/absent in the control and PO only groups but rose substantially in other groups (5898-6766ng/mL). The highest response was in animals that received nirB_SspH1 YS1646 PO then IM rCatB. In this group, reductions in worm and intestine/liver egg burden (vs. control) were 93.1% and 79.5%/90.3% respectively (allP<.0001). Granuloma size was reduced in all vaccinated groups (range 32.86–52.83 ×103μm2) and most significantly in the nirB_SspH1 + CatB IM group (34.74±3.35 ×103μm2vs. 62.22±6.08 ×103μm2: vs. controlP<.01). Many eggs in the vaccinated animals had abnormal morphology. Targeting CatB using a multi-modality approach can provide almost complete protection againstS. mansonichallenge.Author SummarySchistosomiasis is a parasitic disease that affects over 250 million people worldwide and over 800 million are at risk of infection. Of the three main species,Schistosoma mansoniis the most widely distributed and is endemic in the Caribbean, South America, Africa, and the Middle East. It causes a chronic disease with severe negative effects on quality of life. Mass drug administration of praziquantel is the only available course of action due to a current lack of vaccines. However, praziquantel does not protect from reinfection. Therefore, a vaccine would be beneficial as a long-term solution to reduce morbidity and transmission of the disease. Our group has repurposed the attenuated YS1646 strain ofSalmonellaTyphimurium as an oral vaccine vector for the digestive enzyme Cathepsin B ofS. mansoni. Oral vaccination followed by an intramuscular dose of recombinant Cathepsin B lead to significant reductions in parasite burden in mice. These animals had the highest titers in serum IgG and intestinal IgA antibodies. This multimodal vaccination approach also elicited both Th1 and Th2 cytokines as seen by the increases in IFNγ and IL-5. Finally, vaccinated mice had reductions in granuloma size along with a higher proportion of morphologically-abnormal eggs. This work demonstrates that a YS1646-based, multimodality, prime-boost immunization schedule can provide nearly complete protection againstS. mansoniin a well-established murine model.

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Structure-Reactivity Relationships on Substrates and Inhibitors of the Lysine Deacylase Sirtuin 2 from Schistosoma Mansoni (SmSirt2)

10.26434/chemrxiv.7957544.v2 ◽

2019 ◽

Author(s):

Daria Monaldi ◽

Dante Rotili ◽

Julien Lancelot ◽

Martin Marek ◽

Nathalie Wössner ◽

...

Keyword(s):

Schistosoma Mansoni ◽

Human Cancer ◽

Egg Laying ◽

Human Cancer Cells ◽

Parasite Survival ◽

Survival And Reproduction ◽

Emergence Of Resistance ◽

First Time ◽

Parasitic Life Cycle

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Sm16, A Schistosoma mansoni Immunomodulatory Protein, Fails to Elicit a Protective Immune Response and Does Not Have an Essential Role in Parasite Survival in the Definitive Host

Journal of Immunology Research ◽

10.1155/2019/6793596 ◽

2019 ◽

Vol 2019 ◽

pp. 1-16 ◽

Cited By ~ 1

Author(s):

Wilma Patrícia de Oliveira Santos Bernardes ◽

Juliano Michel de Araújo ◽

Gardênia Braz Carvalho ◽

Clarice Carvalho Alves ◽

Aline Thaynara de Moura Coelho ◽

...

Keyword(s):

Immune Responses ◽

Schistosoma Mansoni ◽

Definitive Host ◽

Egg Production ◽

Vaccine Development ◽

Parasite Burden ◽

Egg Laying ◽

Parasite Life Cycle ◽

Parasite Survival ◽

Immunomodulatory Protein

Sm16 is an immunomodulatory protein that seems to play a key role in the suppression of the cutaneous inflammatory response during Schistosoma mansoni penetration of the skin of definitive hosts. Therefore, Sm16 represents a potential target for protective immune responses induced by vaccination. In this work, we generated the recombinant protein rSm16 and produced polyclonal antibodies against this protein to evaluate its expression during different parasite life-cycle stages and its location on the surface of the parasite. In addition, we analyzed the immune responses elicited by immunization with rSm16 using two different vaccine formulations, as well as its ability to induce protection in Balb/c mice. In order to explore the biological function of Sm16 during the course of experimental infection, RNA interference was also employed. Our results demonstrated that Sm16 is expressed in cercaria and schistosomula and is located in the schistosomula surface. Despite humoral and cellular immune responses triggered by vaccination using rSm16 associated with either Freund’s or alum adjuvants, immunized mice presented no reduction in either parasite burden or parasite egg laying. Knockdown of Sm16 gene expression in schistosomula resulted in decreased parasite size in vitro but had no effect on parasite survival or egg production in vivo. Thus, our findings demonstrate that although the vaccine formulations used in this study succeeded in activating immune responses, these failed to promote parasite elimination. Finally, we have shown that Sm16 is not vital for parasite survival in the definitive host and hence may not represent a suitable target for vaccine development.

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