Dataset Information

Suppression of mRNAs encoding tegument tetraspanins from Schistosoma mansoni results in impaired tegument turnover.

ABSTRACT: Schistosomes express a family of integral membrane proteins, called tetraspanins (TSPs), in the outer surface membranes of the tegument. Two of these tetraspanins, Sm-TSP-1 and Sm-TSP-2, confer protection as vaccines in mice, and individuals who are naturally resistant to S. mansoni infection mount a strong IgG response to Sm-TSP-2. To determine their functions in the tegument of S. mansoni we used RNA interference to silence expression of Sm-tsp-1 and Sm-tsp-2 mRNAs. Soaking of parasites in Sm-tsp dsRNAs resulted in 61% (p = 0.009) and 74% (p = 0.009) reductions in Sm-tsp-1 and Sm-tsp-2 transcription levels, respectively, in adult worms, and 67%-75% (p = 0.011) and 69%-89% (p = 0.004) reductions in Sm-tsp-1 and Sm-tsp-2 transcription levels, respectively, in schistosomula compared to worms treated with irrelevant control (luciferase) dsRNA. Ultrastructural morphology of adult worms treated in vitro with Sm-tsp-2 dsRNA displayed a distinctly vacuolated and thinner tegument compared with controls. Schistosomula exposed in vitro to Sm-tsp-2 dsRNA had a significantly thinner and more vacuolated tegument, and morphology consistent with a failure of tegumentary invaginations to close. Injection of mice with schistosomula that had been electroporated with Sm-tsp-1 and Sm-tsp-2 dsRNAs resulted in 61% (p = 0.005) and 83% (p = 0.002) reductions in the numbers of parasites recovered from the mesenteries four weeks later when compared to dsRNA-treated controls. These results imply that tetraspanins play important structural roles impacting tegument development, maturation or stability.

SUBMITTER: Tran MH

PROVIDER: S-EPMC2855321 | biostudies-literature | 2010 Apr

REPOSITORIES: biostudies-literature

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Suppression of mRNAs encoding tegument tetraspanins from Schistosoma mansoni results in impaired tegument turnover.

Tran Mai H MH Freitas Tori C TC Cooper Leanne L Gaze Soraya S Gatton Michelle L ML Jones Malcolm K MK Lovas Erica E Pearce Edward J EJ Loukas Alex A

PLoS pathogens 20100415 4

Schistosomes express a family of integral membrane proteins, called tetraspanins (TSPs), in the outer surface membranes of the tegument. Two of these tetraspanins, Sm-TSP-1 and Sm-TSP-2, confer protection as vaccines in mice, and individuals who are naturally resistant to S. mansoni infection mount a strong IgG response to Sm-TSP-2. To determine their functions in the tegument of S. mansoni we used RNA interference to silence expression of Sm-tsp-1 and Sm-tsp-2 mRNAs. Soaking of parasites in Sm- ...[more]

PMID: 20419145

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Project description:BackgroundPrevious studies have demonstrated that S. mansoni infection and inoculation of the parasite eggs and antigens are able to modulate airways inflammation induced by OVA in mice. This modulation was associated to an enhanced production of interleukin-10 and to an increased number of regulatory T cells. The S. mansoni schistosomulum is the first stage to come into contact with the host immune system and its tegument represents the host-parasite interface. The schistosomula tegument (Smteg) has never been studied in the context of modulation of inflammatory disorders, although immune evasion mechanisms take place in this phase of infection to guarantee the persistence of the parasite in the host.Methodology and principal findingsThe aim of this study was to evaluate the Smteg ability to modulate inflammation in an experimental airway inflammation model induced by OVA and to characterize the immune factors involved in this modulation. To achieve the objective, BALB/c mice were sensitized with ovalbumin (OVA) and then challenged with OVA aerosol after Smteg intraperitoneal inoculation. Protein extravasation and inflammatory cells were assessed in bronchoalveolar lavage and IgE levels were measured in serum. Additionally, lungs were excised for histopathological analyses, cytokine measurement and characterization of the cell populations. Inoculation with Smteg led to a reduction in the protein levels in bronchoalveolar lavage (BAL) and eosinophils in both BAL and lung tissue. In the lung tissue there was a reduction in inflammatory cells and collagen deposition as well as in IL-5, IL-13, IL-25 and CCL11 levels. Additionally, a decrease in specific anti-OVA IgE levels was observed. The reduction observed in these inflammatory parameters was associated with increased levels of IL-10 in lung tissues. Furthermore, Smteg/asthma mice showed high percentage of CD11b+F4/80+IL-10+ and CD11c+CD11b+IL-10+ cells in lungs.ConclusionTaken together, these findings demonstrate that S. mansoni schistosomula tegument can modulates experimental airway inflammation.

Project description:Schistosomiasis continues to be a significant public health problem1. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of S. mansoni. Our group recently identified Sm29, an antigen that is predominantly recognized by IgG1 and IgG3 antibodies of resistant patients2. In the present study, we show that Sm29 is located on the surface of adult worms and lung-stage schistosomula. Immunization of mice with recombinant (r) Sm29 engendered 51% reduction in adult worm burdens, 60% reduction in intestinal eggs and 55% reduction in liver granulomas. Protective immunity in mice was associated with high titers of specific IgG1 and IgG2a and elevated production of IFN-Î³, TNF-Î± and IL-12. Further, cellular responses of infected schistosomiasis patients to rSm29 consisted of elevated IFN-Î³ and an absence of IL-5. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to control mice revealed a significant (q< 0.01) down-regulation of 498 genes, while no up-regulation was detected. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals suggesting that under immune attack schistosomes reduce the expression of critical surface proteins. This study demonstrates that the membrane-bound Sm29 protein is a new molecule that has great potential as a vaccine candidate against schistosomiasis. Keywords: Schistosoma mansoni gene expression in vaccinated mice Two biological samples were used in the study, each used in two arrays (technical replicates with dye swap) and each array containing two replicates of each spot. Overall, there are eight data points data points for each spot. Only cases with more than 4 of 8 points are valid ratios were considered. Value and its respective dye swap value [after changing the log(ratio) signal] were averaged, reducing the data point to four. The average values were than used in the significance testing using SAM (Tusher et al., 2001). The samples were used to get average values using the following combination: 3000139790L with 3000139792L; 3000139790R with 3000139792R; 3000139791L with 3000139795L; 3000139791R with 3000139795R The normalized, averaged dyeswap values are provided in a supplementary file at the foot of the record.

Project description:The draft nuclear genome sequence of the snail-transmitted, dimorphic, parasitic, platyhelminth Schistosoma mansoni revealed eight genes encoding proteins that contain the Universal Stress Protein (USP) domain. Schistosoma mansoni is a causative agent of human schistosomiasis, a severe and debilitating Neglected Tropical Disease (NTD) of poverty, which is endemic in at least 76 countries. The availability of the genome sequences of Schistosoma species presents opportunities for bioinformatics and genomics analyses of associated gene families that could be targets for understanding schistosomiasis ecology, intervention, prevention and control. Proteins with the USP domain are known to provide bacteria, archaea, fungi, protists and plants with the ability to respond to diverse environmental stresses. In this research investigation, the functional annotations of the USP genes and predicted nucleotide and protein sequences were initially verified. Subsequently, sequence clusters and distinctive features of the sequences were determined. A total of twelve ligand binding sites were predicted based on alignment to the ATP-binding universal stress protein from Methanocaldococcus jannaschii. In addition, six USP sequences showed the presence of ATP-binding motif residues indicating that they may be regulated by ATP. Public domain gene expression data and RT-PCR assays confirmed that all the S. mansoni USP genes were transcribed in at least one of the developmental life cycle stages of the helminth. Six of these genes were up-regulated in the miracidium, a free-swimming stage that is critical for transmission to the snail intermediate host. It is possible that during the intra-snail stages, S. mansoni gene transcripts for universal stress proteins are low abundant and are induced to perform specialized functions triggered by environmental stressors such as oxidative stress due to hydrogen peroxide that is present in the snail hemocytes. This report serves to catalyze the formation of a network of researchers to understand the function and regulation of the universal stress proteins encoded in genomes of schistosomes and their snail intermediate hosts.

Project description:BACKGROUND: Schistosomiasis affects more than 200 million individuals worldwide, with a further 650 million living at risk of infection, constituting a severe health problem in developing countries. Even though an effective treatment exists, it does not prevent re-infection, and the development of an effective vaccine still remains the most desirable means of control for this disease. METHODOLOGY/PRINCIPAL FINDINGS: Herein, we report the cloning and characterization of a S. mansoni Stomatin-like protein 2 (SmStoLP-2). In silico analysis predicts three putative sites for palmitoylation (Cys11, Cys61 and Cys330), which could contribute to protein membrane association; and a putative mitochondrial targeting sequence, similar to that described for human Stomatin-like protein 2 (HuSLP-2). The protein was detected by Western blot with comparable levels in all stages across the parasite life cycle. Fractionation by differential centrifugation of schistosome tegument suggested that SmStoLP-2 displays a dual targeting to the tegument membranes and mitochondria; additionally, immunolocalization experiments confirm its localization in the tegument of the adult worms and, more importantly, in 7-day-old schistosomula. Analysis of the antibody isotype profile to rSmStoLP-2 in the sera of patients living in endemic areas for schistosomiasis revealed that IgG1, IgG2, IgG3 and IgA antibodies were predominant in sera of individuals resistant to reinfection as compared to those susceptible. Next, immunization of mice with rSmStoLP-2 engendered a 30%-32% reduction in adult worm burden. Protective immunity in mice was associated with specific anti-rSmStoLP-2 IgG1 and IgG2a antibodies and elevated production of IFN-gamma and TNF-alpha, while no IL-4 production was detected, suggesting a Th1-predominant immune response. CONCLUSIONS/SIGNIFICANCE: Data presented here demonstrate that SmStoLP-2 is a novel tegument protein located in the host-parasite interface. It is recognized by different subclasses of antibodies in patients resistant and susceptible to reinfection and, based on the data from murine studies, shows protective potential against schistosomiasis. These results indicate that SmStoLP-2 could be useful in a combination vaccine.

Dataset Information

Suppression of mRNAs encoding tegument tetraspanins from Schistosoma mansoni results in impaired tegument turnover.

Publications

Suppression of mRNAs encoding tegument tetraspanins from Schistosoma mansoni results in impaired tegument turnover.

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