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Chronic infection with Schistosoma mansoni parasites is associated with reduced allergic sensitization in humans, while schistosome eggs protects against allergic airway inflammation (AAI) in mice. One of the main secretory/excretory molecules from schistosome eggs is the glycosylated T2-RNAse Omega-1 (ω1). We hypothesized that ω1 induces protection against AAI during infection. Peritoneal administration of ω1 prior to sensitization with Ovalbumin (OVA) reduced airway eosinophilia and pathology, and OVA-specific Th2 responses upon challenge, independent from changes in regulatory T cells. ω1 was taken up by monocyte-derived dendritic cells, mannose receptor (CD206)-positive conventional type 2 dendritic cells (CD206+ cDC2), and by recruited peritoneal macrophages. Additionally, ω1 impaired CCR7, F-actin, and costimulatory molecule expression on myeloid cells and cDC2 migration in and ex vivo, as evidenced by reduced OVA+ CD206+ cDC2 in the draining mediastinal lymph nodes (medLn) and retainment in the peritoneal cavity, while antigen processing and presentation in cDC2 were not affected by ω1 treatment. Importantly, RNAse mutant ω1 was unable to reduce AAI or affect DC migration, indicating that ω1 effects are dependent on its RNAse activity. Altogether, ω1 hampers migration of OVA+ cDC2 to the draining medLn in mice, elucidating how ω1 prevents allergic airway inflammation in the OVA/alum mouse model. Author summary: Asthma is a chronic inflammatory disease, leading to cough, wheeze, and shortness of breath. The prevalence has increased drastically in Westernized societies and is now increasing in low- and middle-income countries. Chronic infection with the parasitic helminth, Schistosoma (S.) mansoni protects against allergic airway inflammation (AAI) in mice, and is associated with reduced skin prick test positivity to inhaled allergens in humans. Here we show that peritoneal administration of ω1, a single glycoprotein secreted by S. mansoni eggs, reduced OVA/alum-induced AAI. ω1 is taken up in the peritoneal cavity by dendritic cells (DCs) expressing the mannose receptor, reducing their expression of CCR7 and migratory capacity to the draining mediastinal lymph nodes. This results in accumulation of DCs in the peritoneal cavity of allergic mice and reduced numbers of DCs reaching the draining lymph nodes. The effects observed for ω1 is dependent on its RNAse activity, since the RNAse mutant form of ω1 was unable to reduce AAI nor affect DC migration. Our findings provide insights into how ω1 can modulated the immune response during allergic inflammation, and this may open new avenues for the development of novel therapeutic strategies for allergic asthma. [ABSTRACT FROM AUTHOR]

During chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role. Schistosoma mansoni soluble egg antigens (SEA) are bound and internalized by B cells and induce both human and mouse IL-10 producing Breg cells. To identify Breg-inducing proteins in SEA, we fractionated SEA by size exclusion chromatography and found 6 fractions able to induce IL-10 production by B cells (out of 18) in the high, medium and low molecular weight (MW) range. The high MW fractions were rich in heavily glycosylated molecules, including multi-fucosylated proteins. Using SEA glycoproteins purified by affinity chromatography and synthetic glycans coupled to gold nanoparticles, we investigated the role of these glycan structures in inducing IL-10 production by B cells. Then, we performed proteomics analysis on active low MW fractions and identified a number of proteins with putative immunomodulatory properties, notably thioredoxin (SmTrx1) and the fatty acid binding protein Sm14. Subsequent splenic murine B cell stimulations and hock immunizations with recombinant SmTrx1 and Sm14 showed their ability to dose-dependently induce IL-10 production by B cells both in vitro and in vivo. Identification of unique Breg cells-inducing molecules may pave the way to innovative therapeutic strategies for inflammatory and auto-immune diseases. Author summary: Worm parasites, such as schistosomes, are master regulators of the human immune system, manipulating the host response in order to prolong their survival in their host. As a bystander effect, they also reduce immune responses to allergens and/or auto antigens, thus protecting their host against inflammatory and auto-immune diseases. One of the immune cells involved in immune regulation is the IL-10-producing regulatory B (Breg) cells. Schistosome eggs release various molecules that induce the development of Breg cells, but the identity of these molecules is not yet fully known. In this study, the authors aimed to identify some of these molecules. They investigated both the involvement of glycans on high molecular weight schistosomal egg molecules, as well as dissected the role of proteins with a lower molecular weight coming from schistosomal eggs. Using proteomics, they targeted various interesting molecules, which they recombinantly expressed and confirmed the IL-10 inducing capacity in B cells in vitro and in vivo for 2 molecules. This new knowledge may explain the hyporesponsiveness found in chronic schistosome-infected people and may pave the way to new innovative therapies for inflammatory and auto-immune diseases. [ABSTRACT FROM AUTHOR]

α-galactosidase (α-GAL) and α-N-acetylgalactosaminidase (α-NAGAL) are two glycosyl hydrolases responsible for maintaining cellular homeostasis by regulating glycan substrates on proteins and lipids. Mutations in the human genes encoding either enzyme lead to neurological and neuromuscular impairments seen in both Fabry- and Schindler/Kanzaki- diseases. Here, we investigate whether the parasitic blood fluke Schistosoma mansoni, responsible for the neglected tropical disease schistosomiasis, also contains functionally important α-GAL and α-NAGAL proteins. As infection, parasite maturation and host interactions are all governed by carefully-regulated glycosylation processes, inhibiting S. mansoni's α-GAL and α-NAGAL activities could lead to the development of novel chemotherapeutics. Sequence and phylogenetic analyses of putative α-GAL/α-NAGAL protein types showed Smp_089290 to be the only S. mansoni protein to contain the functional amino acid residues necessary for α-GAL/α-NAGAL substrate cleavage. Both α-GAL and α-NAGAL enzymatic activities were higher in females compared to males (p<0.05; α-NAGAL > α-GAL), which was consistent with smp_089290's female biased expression. Spatial localisation of smp_089290 revealed accumulation in parenchymal cells, neuronal cells, and the vitellaria and mature vitellocytes of the adult schistosome. siRNA-mediated knockdown (>90%) of smp_089290 in adult worms significantly inhibited α-NAGAL activity when compared to control worms (siLuc treated males, p<0.01; siLuc treated females, p<0.05). No significant reductions in α-GAL activities were observed in the same extracts. Despite this, decreases in α-NAGAL activities correlated with a significant inhibition in adult worm motility as well as in egg production. Programmed CRISPR/Cas9 editing of smp_089290 in adult worms confirmed the egg reduction phenotype. Based on these results, Smp_089290 was determined to act predominantly as an α-NAGAL (hereafter termed SmNAGAL) in schistosome parasites where it participates in coordinating movement and oviposition processes. Further characterisation of SmNAGAL and other functionally important glycosyl hydrolases may lead to the development of a novel anthelmintic class of compounds. Author summary: Schistosomiasis is a parasitic disease caused by infection with blood flukes, which leads to acute and chronic pathology in millions of infected individuals located in deprived tropical and subtropical regions. Elucidating the function of schistosome genes has provided a clearer view on their roles in various molecular pathways, which are critical to successful parasitism. This information is invaluable when progressing novel drug and vaccine candidates. Here, we add to the existing knowledge of the Schistosoma mansoni parasitic glycan processing and modification machinery by functionally characterising a glycosyl hydrolase (S. mansoni α-N-acetylgalactosaminidase, SmNAGAL). We demonstrate that this protein is enzymatically active and important in coordinating parasite movement in adult male and female schistosomes. Additionally, we provide evidence that this protein regulates pathways associated with egg production in female schistosomes, which is responsible for inducing pathological reactions. Developing drugs that inhibit SmNAGAL enzymatic activity could provide a novel approach for controlling schistosomiasis. [ABSTRACT FROM AUTHOR]

Infection with the helminth Schistosoma (S.) mansoni drives the development of interleukin (IL)-10-producing regulatory B (Breg) cells in mice and man, which have the capacity to reduce experimental allergic airway inflammation and are thus of high therapeutic interest. However, both the involved antigen and cellular mechanisms that drive Breg cell development remain to be elucidated. Therefore, we investigated whether S. mansoni soluble egg antigens (SEA) directly interact with B cells to enhance their regulatory potential, or act indirectly on B cells via SEA-modulated macrophage subsets. Intraperitoneal injections of S. mansoni eggs or SEA significantly upregulated IL-10 and CD86 expression by marginal zone B cells. Both B cells as well as macrophages of the splenic marginal zone efficiently bound SEA in vivo, but macrophages were dispensable for Breg cell induction as shown by macrophage depletion with clodronate liposomes. SEA was internalized into acidic cell compartments of B cells and induced a 3-fold increase of IL-10, which was dependent on endosomal acidification and was further enhanced by CD40 ligation. IPSE/alpha-1, one of the major antigens in SEA, was also capable of inducing IL-10 in naïve B cells, which was reproduced by tobacco plant-derived recombinant IPSE. Other major schistosomal antigens, omega-1 and kappa-5, had no effect. SEA depleted of IPSE/alpha-1 was still able to induce Breg cells indicating that SEA contains more Breg cell-inducing components. Importantly, SEA- and IPSE-induced Breg cells triggered regulatory T cell development in vitro. SEA and recombinant IPSE/alpha-1 also induced IL-10 production in human CD1d+ B cells. In conclusion, the mechanism of S. mansoni-induced Breg cell development involves a direct targeting of B cells by SEA components such as the secretory glycoprotein IPSE/alpha-1. [ABSTRACT FROM AUTHOR]

Background: Human immunity to Schistosoma infection requires many years of exposure, and multiple infections and treatments to develop. Unlike humans, rhesus macaques clear an established schistosome infection naturally at the same time acquiring immunity towards re-infection. In macaques, schistosome egg production decreases after 8 weeks post-infection and by week 22, physiological impairment of the worm caused by unclarified antibody-mediated processes is observed. Since strong antibody responses have been observed against schistosome glycan antigens in human and animal infections, we here investigate if anti-glycan antibodies are associated with immunity against schistosome infections in macaques. Methods: We used a microarray containing a large repertoire of glycoprotein- and glycolipid-derived glycans from different schistosome life stages to analyse anti-glycan serum IgG and IgM from S. japonicum-infected macaques during the course of infection and self-cure. We also used an in vitro schistosomula assay to investigate whether macaque sera containing anti-glycan antibodies can kill schistosomula. Conclusions/significance: Antibody responses towards schistosome glycans at week 4 post-infection were dominated by IgM while IgG was high at week 8. The profound increase in IgG was observed mainly for antibodies towards a large subset of glycans that contain (multi-)fucosylated terminal GalNAcβ1-4GlcNAc (LDN), and Galβ1-4(Fucα1–3)GlcNAc (LeX) motifs. In general, glycans with a higher degree of fucosylation gave rise to stronger antibody responses than non-fucosylated glycans. Interestingly, even though many IgG and IgM responses had declined by week 22 post-infection, IgG towards O-glycans with highly fucosylated LDN motifs remained. When incubating macaque serum with schistosomula in vitro, schistosomula death was positively correlated with the duration of infection of macaques; macaque serum taken 22 weeks post-infection caused most schistosomula to die, suggesting the presence of potentially protective antibodies. We hypothesize that IgGs against highly fucosylated LDN motifs that remain when the worms deteriorate are associated with infection clearance and the resistance to re-infection in macaques. [ABSTRACT FROM AUTHOR]

Background: The pig parasite Ascaris suum plays and important role in veterinary medicine and represents a suitable model for A. lumbricoides, which infects over 800 million people. In pigs, continued exposure to Ascaris induces immunity at the level of the gut, protecting the host against migrating larvae. The objective of this study was to identify and characterize parasite antigens targeted by this local immune response that may be crucial for parasite invasion and establishment and to evaluate their protective and diagnostic potential. Methodology/Principal Findings: Pigs were immunized by trickle infection for 30 weeks, challenged with 2,000 eggs at week 32 and euthanized two weeks after challenge. At necropsy, there was a 100% reduction in worms recovered from the intestine and a 97.2% reduction in liver white spots in comparison with challenged non-immune control animals. Antibodies purified from the intestinal mucus or from the supernatant of cultured antibody secreting cells from mesenteric lymph nodes of immune pigs were used to probe L3 extracts to identify antibody targets. This resulted in the recognition of a 12kDa antigen (As12) that is actively shed from infective Ascaris L3. As12 was characterized as a phosphorylcholine-containing glycolipid-like antigen that is highly resistant to different enzymatic and chemical treatments. Vaccinating pigs with an As12 fraction did not induce protective immunity to challenge infection. However, serological analysis using sera or plasma from experimentally infected pigs or naturally infected humans demonstrated that the As12 ELISA was able to detect long-term exposure to Ascaris with a high diagnostic sensitivity (98.4% and 92%, respectively) and specificity (95.5% and 90.0%) in pigs and humans, respectively. Conclusions/Significance: These findings show the presence of a highly stage specific, glycolipid-like component (As12) that is actively secreted by infectious Ascaris larvae and which acts as a major antibody target in infected humans and pigs. [ABSTRACT FROM AUTHOR]

Recently, the prevalence of Fasciola hepatica in some areas has increased considerably and the availability of a vaccine to protect livestock from infection would represent a major advance in tools available for controlling this disease. To date, most vaccine-target discovery research on this parasite has concentrated on proteomic and transcriptomic approaches whereas little work has been carried out on glycosylation. As the F. hepatica tegument (Teg) may contain glycans potentially relevant to vaccine development and the Newly Excysted Juvenile (NEJ) is the first lifecycle stage in contact with the definitive host, our work has focused on assessing the glycosylation of the NEJTeg and identifying the NEJTeg glycoprotein repertoire. After in vitro excystation, NEJ were fixed and NEJTeg was extracted. Matrix-assisted laser desorption ionisation-time of flight-mass spectrometry (MALDI-TOF-MS) analysis of released N-glycans revealed that oligomannose and core-fucosylated truncated N-glycans were the most dominant glycan types. By lectin binding studies these glycans were identified mainly on the NEJ surface, together with the oral and ventral suckers. NEJTeg glycoproteins were affinity purified after targeted biotinylation of the glycans and identified using liquid chromatography and tandem mass spectrometry (LC-MS/MS). From the total set of proteins previously identified in NEJTeg, eighteen were also detected in the glycosylated fraction, including the F. hepatica Cathepsin B3 (FhCB3) and two of the Cathepsin L3 (FhCL3) proteins, among others. To confirm glycosylation of cathepsins, analysis at the glycopeptide level by LC-ESI-ion-trap-MS/MS with collision-induced dissociation (CID) and electron-transfer dissociation (ETD) was carried out. We established that cathepsin B1 (FhCB1) on position N80, and FhCL3 (BN1106_s10139B000014, scaffold10139) on position N153, carry unusual paucimannosidic Man2GlcNAc2 glycans. To our knowledge, this is the first description of F. hepatica NEJ glycosylation and the first report of N-glycosylation of F. hepatica cathepsins. The significance of these findings for immunological studies and vaccine development is discussed. [ABSTRACT FROM AUTHOR]

Fascioliasis, caused by the liver fluke Fasciola hepatica, is a neglected tropical disease infecting over 1 million individuals annually with 17 million people at risk of infection. Like other helminths, F. hepatica employs mechanisms of immune suppression in order to evade its host immune system. In this study the N-glycosylation of F. hepatica’s tegumental coat (FhTeg) and its carbohydrate-dependent interactions with bone marrow derived dendritic cells (BMDCs) were investigated. Mass spectrometric analysis demonstrated that FhTeg N-glycans comprised mainly of oligomannose and to a lesser extent truncated and complex type glycans, including a phosphorylated subset. The interaction of FhTeg with the mannose receptor (MR) was investigated. Binding of FhTeg to MR-transfected CHO cells and BMDCs was blocked when pre-incubated with mannan. We further elucidated the role played by MR in the immunomodulatory mechanism of FhTeg and demonstrated that while FhTeg’s binding was significantly reduced in BMDCs generated from MR knockout mice, the absence of MR did not alter FhTeg’s ability to induce SOCS3 or suppress cytokine secretion from LPS activated BMDCs. A panel of negatively charged monosaccharides (i.e. GlcNAc-4P, Man-6P and GalNAc-4S) were used in an attempt to inhibit the immunoregulatory properties of phosphorylated oligosaccharides. Notably, GalNAc-4S, a known inhibitor of the Cys-domain of MR, efficiently suppressed FhTeg binding to BMDCs and inhibited the expression of suppressor of cytokine signalling (SOCS) 3, a negative regulator the TLR and STAT3 pathway. We conclude that F. hepatica contains high levels of mannose residues and phosphorylated glycoproteins that are crucial in modulating its host’s immune system, however the role played by MR appears to be limited to the initial binding event suggesting that other C-type lectin receptors are involved in the immunomodulatory mechanism of FhTeg. [ABSTRACT FROM AUTHOR]

Background: Conventional diagnostic methods for human ascariasis are based on the detection of Ascaris lumbricoides eggs in stool samples. However, studies of ascariasis in pigs have shown that the prevalence and the number of eggs detected in the stool do not correlate well with exposure of the herd to the parasite. On the other hand, an ELISA test measuring antibodies to Ascaris suum haemoglobin (AsHb) has been shown to be useful for estimating transmission intensity on pig farms. In this study, we further characterized the AsHb antigen and screened samples from a population-based study conducted in an area that is endemic for Ascaris lumbricoides in Indonesia to assess changes in AsHb antibody rates and levels in humans following mass drug administration (MDA). Methodology/Principal findings: We developed and evaluated an ELISA to detect human IgG4 antibodies to AsHb. We tested 1066 plasma samples collected at different times from 599 subjects who lived in a village in rural Indonesia that was highly endemic for ascariasis. The community received 6 rounds of MDA for lymphatic filariasis with albendazole plus diethylcarbamazine between 2002 and 2007. While the AsHb antibody assay was not sensitive for detecting all individuals with Ascaris eggs in their stools, the percentage of seropositive individuals decreased rapidly following MDA. Reductions in antibody rates reflected decreased mean egg output per person both at the community level and in different age groups. Two years after the last round of MDA the community egg output and antibody prevalence rate were reduced by 81.6% and 78.9% respectively compared to baseline levels. Conclusion/Significance: IgG4 antibody levels to AsHb appear to reflect recent exposure to Ascaris. The antibody prevalence rate may be a useful indicator for Ascaris transmission intensity in communities that can be used to assess the impact of control measures on the force of transmission. [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis is a serious health problem especially in developing countries and affects more than 243 million people. Only few anthelmintic drugs are available up to now. A major obstacle for drug treatment is the different developmental stages and the varying host compartments during worm development. Anthelmintic drugs have been tested mainly on adult schistosomes or freshly transformed cercariae. Knowledge concerning the larval stages is lacking. Methodology/Principal Findings: In this study, we used in vitro-grown schistosomula (aged between 2 to 14 days) to investigate drug effects of the three anthelmintics praziquantel, artemether, and oxamniquine. Further, we analyzed the antibody accessibility of two exemplary schistosome antigens SmCD59a and SmKK7, before and after drug treatment. Our results demonstrated that praziquantel applied at a concentration of 1 μM inhibited development of all life stages. Application of 10 μM praziquantel led to dramatic morphological changes of all schistosomula. Artemether at 1 and 10 μM had differential effects depending on whether it was applied to 2-day as compared to 7- and 14-day schistosomula. While 2-day schistosomula were not killed but inhibited from further development, severe morphological damage was seen in 7- and 14-day schistosomula. Oxamniquine (1 and 10 μM) led to severe morphological impairment in all life stages. Analyzing the accessibility of the antigens SmCD59a and SmKK7 before drug treatment showed no antibody binding on living intact schistosomula. However, when schistosomula were treated with anthelmintics, both antigens became exposed on the larvae. Oxamniquine turned out to be most effective in promoting antibody binding to all schistosomula stages. Conclusion: This study has revealed marked differences in anthelmintic drug effects against larvae. Drug treatment increases surface antigen presentation and renders larvae accessible to antibody attack. Author Summary: Schistosomiasis is one of the major parasitic diseases in developing countries and still causes 200,000 deaths per year. Mass drug administration programs with praziquantel, the drug of choice against schistosomiasis, are currently undertaken in Sub-Saharan Africa. Praziquantel, although efficient against adult worms, fails to cure early infection. The complex developmental stages of schistosomes and migration through varying host compartments with different local drug concentration are a challenge for drug treatment. After infecting their mammalian host, schistosomula traverse through skin and the vasculature of lung, liver and intestines. During their migration, they develop from larvae to paired adults in approximately 4 to 5 weeks. So far, drug effects have been analyzed on adult worms or freshly transformed schistosomula only. Information about the effects on the larval stages is lacking. We were able to transfer the larval development of the first three weeks into the culture dish. This tool can be used for the analysis of drug effects against schistosomula and for investigation of the accessibility, expression and localization of antigens. Rendering the parasite's larvae vulnerable to the host's immune system by increasing antigen presentation is an important aspect of drug activity. We demonstrate on in vitro-cultured Schistosoma mansoni larvae, that SmCD59a and SmKK7, as examples for hidden antigens, become accessible to antibodies following drug treatment. [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis (bilharzia) is a chronic and potentially deadly parasitic disease that affects millions of people in (sub)tropical areas. An important partial immunity to Schistosoma infections does develop in disease endemic areas, but this takes many years of exposure and maturation of the immune system. Therefore, children are far more susceptible to re-infection after treatment than older children and adults. This age-dependent immunity or susceptibility to re-infection has been shown to be associated with specific antibody and T cell responses. Many antibodies generated during Schistosoma infection are directed against the numerous glycans expressed by Schistosoma. The nature of glycan epitopes recognized by antibodies in natural schistosomiasis infection serum is largely unknown. Methodology/Principal Findings: The binding of serum antibodies to glycans can be analyzed efficiently and quantitatively using glycan microarray approaches. Very small amounts of a large number of glycans are presented on a solid surface allowing binding properties of various glycan binding proteins to be tested. We have generated a so-called shotgun glycan microarray containing natural N-glycan and lipid-glycan fractions derived from 4 different life stages of S. mansoni and applied this array to the analysis of IgG and IgM antibodies in sera from children and adults living in an endemic area. This resulted in the identification of differential glycan recognition profiles characteristic for the two different age groups, possibly reflecting differences in age or differences in length of exposure or infection. Conclusions/Significance: Using the shotgun glycan microarray approach to study antibody response profiles against schistosome-derived glycan elements, we have defined groups of infected individuals as well as glycan element clusters to which antibody responses are directed in S. mansoni infections. These findings are significant for further exploration of Schistosoma glycan antigens in relation to immunity. Author Summary: Schistosomes are parasitic worms that cause chronic and potentially deadly disease in millions of people in (sub)tropical areas. An important partial immunity to infection does develop but this takes many years of exposure and multiple infections. Therefore, children are far more susceptible to re-infection after treatment than adults. This immunological protection is associated with specific antibody and T cell responses. Many antibodies generated during Schistosoma infection are directed against carbohydrate chains (glycans) expressed by the parasite. The nature of the glycan epitopes recognized by antibodies in natural schistosomiasis infection serum is largely unknown. We have used a so-called shotgun glycan microarray approach to study differences in anti-glycan antibody responses between S. mansoni-infected children and adults. This resulted in the identification of differential glycan recognition profiles characteristic for the two different age groups that may reflect differences in age or differences in length of exposure or infection in people living in an endemic area. [ABSTRACT FROM AUTHOR]

Background: Schistosomiasis (bilharzia) is a chronic and potentially deadly parasitic disease that affects millions of people in (sub)tropical areas. An important partial immunity to Schistosoma infections does develop in disease endemic areas, but this takes many years of exposure and maturation of the immune system. Therefore, children are far more susceptible to re-infection after treatment than older children and adults. This age-dependent immunity or susceptibility to re-infection has been shown to be associated with specific antibody and T cell responses. Many antibodies generated during Schistosoma infection are directed against the numerous glycans expressed by Schistosoma. The nature of glycan epitopes recognized by antibodies in natural schistosomiasis infection serum is largely unknown. Methodology/Principal Findings: The binding of serum antibodies to glycans can be analyzed efficiently and quantitatively using glycan microarray approaches. Very small amounts of a large number of glycans are presented on a solid surface allowing binding properties of various glycan binding proteins to be tested. We have generated a so-called shotgun glycan microarray containing natural N-glycan and lipid-glycan fractions derived from 4 different life stages of S. mansoni and applied this array to the analysis of IgG and IgM antibodies in sera from children and adults living in an endemic area. This resulted in the identification of differential glycan recognition profiles characteristic for the two different age groups, possibly reflecting differences in age or differences in length of exposure or infection. Conclusions/Significance: Using the shotgun glycan microarray approach to study antibody response profiles against schistosome-derived glycan elements, we have defined groups of infected individuals as well as glycan element clusters to which antibody responses are directed in S. mansoni infections. These findings are significant for further exploration of Schistosoma glycan antigens in relation to immunity. [ABSTRACT FROM AUTHOR]

Recent evidence supports the involvement of inducible, highly diverse lectin-like recognition molecules in snail hemocyte-mediated responses to larval Schistosoma mansoni. Because host lectins likely are involved in initial parasite recognition, we sought to identify specific carbohydrate structures (glycans) shared between larval S. mansoni and its host Biomphalaria glabrata to address possible mechanisms of immune avoidance through mimicry of elements associated with the host immunoreactivity. A panel of monoclonal antibodies (mABs) to specific S. mansoni glycans was used to identify the distribution and abundance of shared glycan epitopes (glycotopes) on plasma glycoproteins from B. glabrata strains that differ in their susceptibilities to infection by S. mansoni. In addition, a major aim of this study was to determine if larval transformation products (LTPs) could bind to plasma proteins, and thereby alter the glycotopes exposed on plasma proteins in a snail strain-specific fashion. Plasma fractions (<100 kDa/>100 kDa) from susceptible (NMRI) and resistant (BS-90) snail strains were subjected to SDS-PAGE and immunoblot analyses using mAB to LacdiNAc (LDN), fucosylated LDN variants, Lewis X and trimannosyl core glycans. Results confirmed a high degree of glycan sharing, with NMRI plasma exhibiting a greater distribution/abundance of LDN, F-LDN and F-LDN-F than BS-90 plasma (<100 kDa fraction). Pretreatment of blotted proteins with LTPs significantly altered the reactivity of specific mABs to shared glycotopes on blots, mainly through the binding of LTPs to plasma proteins resulting in either glycotope blocking or increased glycotope attachment to plasma. Many LTP-mediated changes in shared glycans were snail-strain specific, especially those in the <100 kDa fraction for NMRI plasma proteins, and for BS-90, mainly those in the >100 kDa fraction. Our data suggest that differential binding of S. mansoni LTPs to plasma proteins of susceptible and resistant B. glabrata strains may significantly impact early anti-larval immune reactivity, and in turn, compatibility, in this parasite-host system. Author Summary: Early larval stages of the human blood fluke Schistosoma mansoni face many barriers in their attempt to establish successful infections within their snail host, Biomphalaria spp. The snail's internal defense system represents one such barrier, which includes lectin-like recognition receptors and circulating hemocytes capable of encapsulating and killing invading larvae. Since host lectins likely are involved in early immunorecognition events, the recent identification of specific carbohydrate structures (glycans) shared between larval stages of S. mansoni and its host Biomphalaria glabrata suggests that larvae may be avoiding immune recognition through a molecular mimicry mechanism mediated by lectin-reactive glycans. Results of the present study support previous findings of extensive host-parasite glycan sharing, and demonstrate that molecules released by S. mansoni miracidia during in vitro development (larval transformation products or LTPs) selectively bind to plasma proteins, altering their reactivity to various glycan-specific monoclonal antibodies. Moreover, some of the changes in recognized glycans following exposure of blotted plasma proteins to LTP were B. glabrata strain-specific. We hypothesize that the differential interaction of LTPs with plasma proteins from different B. glabrata strains may play an important role in influencing the efficacy of anti-larval immune reactivity within a given host strain. [ABSTRACT FROM AUTHOR]

Background: Markers for longevity that reflect the health condition and predict healthy aging are extremely scarce. Such markers are, however, valuable in aging research. It has been shown previously that the N-glycosylation pattern of human immunoglobulin G (IgG) is age-dependent. Here we investigate whether N-linked glycans reflect early features of human longevity. Methodology/Principal Findings: The Leiden Longevity Study (LLS) consists of nonagenarian sibling pairs, their offspring, and partners of the offspring serving as control. IgG subclass specific glycosylation patterns were obtained from 1967 participants in the LLS by MALDI-TOF-MS analysis of tryptic IgG Fc glycopeptides. Several regression strategies were applied to evaluate the association of IgG glycosylation with age, sex, and longevity. The degree of galactosylation of IgG decreased with increasing age. For the galactosylated glycoforms the incidence of bisecting GlcNAc increased as a function of age. Sex-related differences were observed at ages below 60 years. Compared to males, younger females had higher galactosylation, which decreased stronger with increasing age, resulting in similar galactosylation for both sexes from 60 onwards. In younger participants (<60 years of age), but not in the older age group (>60 years), decreased levels of non-galactosylated glycoforms containing a bisecting GlcNAc reflected early features of longevity. Conclusions/Significance: We here describe IgG glycoforms associated with calendar age at all ages and the propensity for longevity before middle age. As modulation of IgG effector functions has been described for various IgG glycosylation features, a modulatory effect may be expected for the longevity marker described in this study. [ABSTRACT FROM AUTHOR]