Structural and Functional Analysis of Glycosphingolipids of Schistosoma mansoni. Glycobiology. Elsevier; 2010. pp. 117-40. [DOI: 10.1016/s0076-6879(10)80006-0]

The antifibrotic effect of Vildagliptin and Diaminodiphenyl Sulfone in murine schistosomiasis mansoni

Schistosomiasis drastically affects human health, where S. mansoni-induced hepatic fibrosis remains a serious problem with no available drug yet. The current study aimed to evaluate the hepatoprotective effects of Vildagliptin (Vilda), Diaminodiphenyl Sulfone (DDS), and their combination (Vilda/DDS) against S. mansoni-induced hepatic fibrosis and elucidate their underlying molecular mechanisms. S.mansoni-infected mice were administered praziquantel (PZQ) for two consecutive days, or Vilda, DDS, and Vilda/DDS for 14 consecutive days. Schistosomiasis-induced hepatic fibrosis was assessed parasitologically, biochemically, and pathologically. Results revealed that Vilda, DDS, and Vida/DDS treatments significantly reduced worm count, oogram stages, ova count, and ameliorated the granulomatous inflammatory reactions and hepatotoxicity indices. Moreover, they enhanced hepatic Nrf2/HO-1 pathway with significant increasing SOD and reducing MDA levels. Furthermore, they significantly downregulated the hepatic TLR4/NF-κB and NLRP3 inflammasome pathways leading to a significant reduction in TNF-α and caspase-1 levels which is important in the activation of IL-1β and caspase-3. Notably, significant downregulation in hepatic TGF-β1, α-SMA, and MMP-9 expressions were also recorded. In conclusion, Vilda/DDS showed antioxidant, anti-inflammatory and antifibrotic activities in comparison to either Vilda or DDS alone against S. mansoni-induced hepatic fibrosis. Therefore, Vilda/DDS is a promising approach for managing S. mansoni infection, liver fibrosis, and associated disease morbidity.

Glycosphingolipids in human parasites

Glycosphingolipids (GSLs) are comprised of glycans (oligosaccharides) linked to a lipid containing a sphingosine moiety. They are major membrane components in cells of most animals, and importantly, they also occur in parasitic protozoans and worms that infect people. While the endogenous functions of the GSLs in most parasites are elusive, many of these GSLs are recognized by antibodies in infected human and animal hosts, and thus, their structures, biosynthesis, and functions are of great interest. Such knowledge of GSLs could lead to new drugs and diagnostics for treating infections, as well as novel vaccine strategies. The diversity of GSLs recently identified in such infectious organisms and aspects of their immune recognition are major topics of this review. It is not intended to be exhaustive but to highlight aspects of GSL glycans in human parasites.

Profiling the glycome of Cardicola forsteri, a blood fluke parasitic to bluefin tuna

Infections by blood flukes (Cardicola spp.) are considered the most significant health issue for ranched bluefin tuna, a major aquaculture industry in Japan and Australia. The host-parasite interfaces of trematodes, namely their teguments, are particularly rich in carbohydrates, which function both in evasion and modulation of the host immune system, while some are primary antigenic targets. In this study, histochemistry and mass spectrometry techniques were used to profile the glycans of Cardicola forsteri. Fluorescent lectin staining of adult flukes indicates the presence of oligomannose (Concanavalin A-reactive) and fucosylated (Pisum sativum agglutinin-reactive) N-glycans. Additionally, reactivity of succinylated wheat germ agglutinin (s-WGA) was localised to several internal organs of the digestive and monoecious reproductive systems. Glycan structures were further investigated with tandem mass spectrometry, which revealed structures indicated by lectin reactivity. While O-glycans from these adult specimens were not detectable by mass spectrometry, several oligomannose, paucimannosidic, and complex-type N-glycans were identified, including some carrying hexuronic acid and many carrying core xylose. This is, to our knowledge, the first glycomic characterisation of a marine platyhelminth, with broader implications for research into other trematodes.

A plant-mediated synthesis of nanostructured hydroxyapatite for biomedical applications: a review

The engineering of calcium-based phosphate materials at the nanoscale gains several unique properties compared to the bulky state. The effort to scale down, e.g., from bulky state to nanoscale in order to control the morphology and improve structural properties requires the use of varying reagents that can be detrimental to the environment. A typical example of these materials is hydroxyapatite (HAp), one of the well-known calcium phosphate materials, which has a close resemblance to human bone tissue. HAp has valuable applications in catalysis, drug delivery, bone and dental implant formation, and adsorption. Hydroxyapatite-based nanomaterials synthesized through conventional routes make use of reagents that are not environmental friendly and are very costly. Since the current research trends are geared towards producing/synthesizing nanomaterials through an eco-friendly approach, there is the need to consider the techniques and reagents involved in the synthesis of HAp. This review touches on the possible replacement of such synthetic chemical reagents, synthesis routes, and toxic capping agents with plant extracts for synthesizing HAp-based nanomaterials for multi-functional applications. The influence of biomolecules from plants on synthesized HAps and the attainable mechanism during these green approaches are discussed. Viable future modifications of the methods used to obtain extracts from plants are also studied.

Structures and functions of invertebrate glycosylation

Glycosylation refers to the covalent attachment of sugar residues to a protein or lipid, and the biological importance of this modification has been widely recognized. While glycosylation in mammals is being extensively investigated, lower level animals such as invertebrates have not been adequately interrogated for their glycosylation. The rich diversity of invertebrate species, the increased database of sequenced invertebrate genomes and the time and cost efficiency of raising and experimenting on these species have enabled a handful of the species to become excellent model organisms, which have been successfully used as tools for probing various biologically interesting problems. Investigation on invertebrate glycosylation, especially on model organisms, not only expands the structural and functional knowledgebase, but also can facilitate deeper understanding on the biological functions of glycosylation in higher organisms. Here, we reviewed the research advances in invertebrate glycosylation, including N- and O-glycosylation, glycosphingolipids and glycosaminoglycans. The aspects of glycan biosynthesis, structures and functions are discussed, with a focus on the model organisms Drosophila and Caenorhabditis. Analytical strategies for the glycans and glycoconjugates are also summarized.

Schistosoma mansoni soluble egg antigen (SEA) and recombinant Omega-1 modulate induced CD4+ T-lymphocyte responses and HIV-1 infection in vitro

Parasitic helminths evade, skew and dampen human immune responses through numerous mechanisms. Such effects will likely have consequences for HIV-1 transmission and disease progression. Here we analyzed the effects that soluble egg antigen (SEA) from Schistosoma mansoni had on modulating HIV-1 infection and cytokine/chemokine production in vitro. We determined that SEA, specifically through kappa-5, can potently bind to DC-SIGN and thereby blocks DC-SIGN mediated HIV-1 trans-infection (p<0.05) whilst not interfering with cis-infection. DCs exposed to SEA whilst maturing under Th2 promoting conditions, will upon co-culture with naïve T-cells induce a T-cell population that was less susceptible to HIV-1 R5 infection (p<0.05) compared to DCs unexposed to SEA, whereas HIV-1 X4 virus infection was unaffected. This was not observed for DCs exposed to SEA while maturing under Th1 or Th1/Th2 (T_mix) promoting conditions. All T-cell populations induced by SEA exposed DCs demonstrate a reduced capacity to produce IFN-γ and MIP-1β. The infection profile of T-cells infected with HIV-1 R5 was not associated with down-modulation of CCR5 cell surface expression. We further show that DCs maturing under T_mix conditions exposed to plant recombinant omega-1 protein (rω-1), which demonstrates similar functions to natural ω-1, induced T-cell populations that were less sensitive for HIV-1 R5 infection (p<0.05), but not for X4 virus infection. This inhibition associated again with a reduction in IFN-γ and MIP-1β expression, but additionally correlated with reduced CCR5 expression. We have shown that SEA parasite antigens and more specifically rω-1 can modulate HIV-1 infectivity with the potential to influence disease course in co-infected individuals.

Parasitic helminths have developed a number of strategies to evade, skew and dampen human immune responses. Such effects will likely have consequences for HIV-1 transmission and disease progression. Here we analyzed the effect that soluble egg antigen (SEA) from Schistosoma mansoni had on HIV-1 infection in vitro. We determined that SEA, through kappa-5, can potently block DC-SIGN mediated HIV-1 trans-infection of CD4⁺ T-lymphocytes, but not block cis-infection. Dendritic cells (DC) exposed to SEA during maturation under Th2 skewing conditions, induce T-cell populations that are less susceptible to HIV-1 R5 infection compared to cells induced by unexposed DCs. HIV-1 X4 infection was unaffected. This restricted infection profile was not associated with down-modulation of CCR5 surface expression or observed differences in cytokine/chemokine production. Using recombinant omega-1, an abundant component of SEA, HIV-1 R5 infection was similarly inhibited with no effect on HIV-1 X4 infection levels. Hence SEA possesses antigens, namely omega-1, that can modulate HIV-1 infection and potentially influence disease course in co-infected individuals.

High molecular weight components containing N-linked oligosaccharides of Ascaris suum extract inhibit the dendritic cells activation through DC-SIGN and MR

Helminths, as well as their secretory/excretory products, induce a tolerogenic immune microenvironment. High molecular weight components (PI) from Ascaris suum extract down-modulate the immune response against ovalbumin (OVA). The PI exerts direct effect on dendritic cells (DCs) independent of TLR 2, 4 and MyD88 molecule and, thus, decreases the T lymphocytes response. Here, we studied the glycoconjugates in PI and the role of C-type lectin receptors (CLRs), DC-SIGN and MR, in the modulation of DCs activity. Our data showed the presence of glycoconjugates with high mannose- and complex-type N-linked oligosaccharide chains and phosphorylcholine residues on PI. In addition, these N-linked glycoconjugates inhibited the DCs maturation induced by LPS. The binding and internalization of PI-Alexa were decreased on DCs previously incubated with mannan, anti-DC-SIGN and/or anti-MR antibodies. In agreement with this, the incubation of DCs with mannan, anti-DC-SIGN and/or anti-MR antibodies abolished the down-modulatory effect of PI on these cells. It was also observed that the blockage of CLRs, DC-SIGN and MR on DCs reverted the inhibitory effect of PI in in vitro T cells proliferation. Therefore, our data show the involvement of DC-SIGN and MR in the recognition and consequent modulatory effect of N-glycosylated components of PI on DCs.

Identification of Antigenic Glycans from Schistosoma mansoni by Using a Shotgun Egg Glycan Microarray

Infection of mammals by the parasitic helminth Schistosoma mansoni induces antibodies to glycan antigens in worms and eggs, but the differential nature of the immune response among infected mammals is poorly understood. To better define these responses, we used a shotgun glycomics approach in which N-glycans from schistosome egg glycoproteins were prepared, derivatized, separated, and used to generate an egg shotgun glycan microarray. This array was interrogated with sera from infected mice, rhesus monkeys, and humans and with glycan-binding proteins and antibodies to gather information about the structures of antigenic glycans, which also were analyzed by mass spectrometry. A major glycan antigen targeted by IgG from different infected species is the FLDNF epitope [Fucα3GalNAcβ4(Fucα3)GlcNAc-R], which is also recognized by the IgG monoclonal antibody F2D2. The FLDNF antigen is expressed by all life stages of the parasite in mammalian hosts, and F2D2 can kill schistosomula in vitro in a complement-dependent manner. Different antisera also recognized other glycan determinants, including core β-xylose and highly fucosylated glycans. Thus, the natural shotgun glycan microarray of schistosome eggs is useful in identifying antigenic glycans and in developing new anti-glycan reagents that may have diagnostic applications and contribute to developing new vaccines against schistosomiasis.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

Characterization of α-L-fucosidase and other digestive hydrolases from Biomphalaria glabrata

Schistosoma mansoni is one of the major agents of the disease Schistosomiasis, which is one of the major global public health concerns. Biomphalaria glabrata is an obligate intermediate mollusc host of S. mansoni. Although the development of S. mansoni occurs in the snail hepatopancreas, studies that focus on this organ remain limited. In this study, we biochemically identified five distinct carbohydrases (amylase, maltase, α-glucosidase, trehalase, and α-L-fucosidase), lipases, and peptidases in the B. glabrata hepatopancreas and focused on the isolation and characterization of the activity of α-L-fucosidase. The isolated α-L-fucosidase has a molecular mass of 141 kDa, an optimum pH of 5.8, and is inhibited by Tris, fucose, and 1-deoxyfuconojirimycin. B. glabrata α-L-fucosidase is an exoglycosidase that can hydrolyze the natural substrate fucoidan to fucose residues. It presented Km values of 48.4 μM to 4-Methylumbelliferyl α-L-fucopyranoside and 0.55 mM to p-nitrophenyl-α-L-fucopyranoside. Thus, α-L-fucosidase has a high activity in the hepatopancreas of B. glabrata, and the differential expression of this enzyme between susceptible and resistant strains indicates that besides its digestive role, α-L-fucosidase may also be important in host/parasite interactions.

Application of microarrays for deciphering the structure and function of the human glycome

Glycan structures were defined historically using multiple methods to determine composition, sequence, linkage, and anomericity of component monosaccharides. Such approaches have been replaced by more sensitive MS methods to profile or predict glycan structures, but these methods are limited in their ability to completely define glycan structures. Glycan-binding proteins, including lectins and antibodies, have been found to have exquisite binding specificities that can provide information about glycan structures. Here, we show glycan-binding proteins can be used along with MS to help define glycan linkages and other determinants in unknown glycans printed as shotgun glycan microarrays.

Differences in genomic architecture between two distinct geographical strains of the blood fluke Schistosoma japonicum reveal potential phenotype basis

The Chinese (SjC) and Philippine (SjP) strains of the blood fluke Schistosoma japonicum have been shown to present clearly different phenotypes in fecundity, pathology, drug sensitivity and immunology. We used microarray based comparative genomic hybridisation (aCGH) to investigate structural differences in the genomes of the two strains and identified seven distinct regions of the S. japonicum genome that present differential aCGH representing either deletion or duplication regions in SjP. Within these regions, genes predicted to be associated with the recognised phenotypic differences were identified and that may provide new insights into the biology and evolution of the two strains, with implications for the epidemiology and control of schistosomiasis japonica in China and the Philippines.

Parasite glycans and antibody-mediated immune responses in Schistosoma infection

Schistosome infections in humans are characterized by the development of chronic disease and high re-infection rates after treatment due to the slow development of immunity. It appears that anti-schistosome antibodies are at least partially mediating protective mechanisms. Efforts to develop a vaccine based on immunization with surface-exposed or secreted larval or worm proteins are ongoing. Schistosomes also express a large number of glycans as part of their glycoprotein and glycolipid repertoire, and antibody responses to those glycans are mounted by the infected host. This observation raises the question if glycans might also form novel vaccine targets for immune intervention in schistosomiasis. This review summarizes current knowledge of antibody responses and immunity in experimental and natural infections with Schistosoma, the expression profiles of schistosome glycans (the glycome), and antibody responses to individual antigenic glycan motifs. Future directions to study anti-glycan responses in schistosomiasis in more detail in order to address more precisely the possible role of glycans in antibody-mediated immunity are discussed.

Triangulated mal-signaling in Alzheimer's disease: roles of neurotoxic ceramides, ER stress, and insulin resistance reviewed

Ceramides are lipid signaling molecules that cause cytotoxicity and cell death mediated by insulin resistance, inflammation, and endoplasmic reticulum (ER) stress. However, insulin resistance dysregulates lipid metabolism, which promotes ceramide accumulation with attendant inflammation and ER stress. Herein, we discuss two major pathways, extrinsic and intrinsic, that converge and often overlap in propagating AD-type neurodegeneration via a triangulated mal-signaling network. First, we review evidence that systemic insulin resistance diseases linked to obesity, type 2 diabetes, and non-alcoholic steatohepatitis promote neurodegeneration. Mechanistically, we propose that toxic ceramides generated in extra-CNS tissues (e.g., liver) get released into peripheral blood, and subsequently transit across the blood-brain barrier into the brain where they induce brain insulin resistance, inflammation, and cell death (extrinsic pathway). Then we discuss the role of the intrinsic pathway of neurodegeneration which is mediated by endogenous or primary brain insulin/IGF resistance, and impairs neuronal and oligodendrocyte survival, energy metabolism, membrane integrity, cytoskeletal function, and AβPP-Aβ secretion. The end result is increased ER stress and ceramide generation, which exacerbate brain insulin resistance, cell death, myelin degeneration, and neuroinflammation. Altogether, the data suggest that the triangulated mal-signaling network mediated by toxic ceramides, ER stress, and insulin resistance should be targeted to disrupt positive feedback loops that drive the AD neurodegeneration cascade.

TLR2 mediates immunity to experimental cysticercosis

Information concerning TLR-mediated antigen recognition and regulation of immune responses during helminth infections is scarce. TLR2 is a key molecule required for innate immunity and is involved in the recognition of a wide range of viruses, bacteria, fungi and parasites. Here, we evaluated the role of TLR2 in a Taenia crassiceps cysticercosis model. We compared the course of T. crassiceps infection in C57BL/6 TLR2 knockout mice (TLR2^-/-) with that in wild type C57BL/6 (TLR2^+/+) mice. In addition, we assessed serum antibody and cytokine profiles, splenic cellular responses and cytokine profiles and the recruitment of alternatively activated macrophages (AAMφs) to the site of the infection. Unlike wild type mice, TLR2^-/- mice failed to produce significant levels of inflammatory cytokines in either the serum or the spleen during the first two weeks of Taenia infection. TLR2^-/- mice developed a Th2-dominant immune response, whereas TLR2^+/+ mice developed a Th1-dominant immune response after Taenia infection. The insufficient production of inflammatory cytokines at early time points and the lack of Th1-dominant adaptive immunity in TLR2^-/- mice were associated with significantly elevated parasite burdens; in contrast, TLR2^+/+ mice were resistant to infection. Furthermore, increased recruitment of AAMφs expressing PD-L1, PD-L2, OX40L and mannose receptor was observed in TLR2^-/- mice. Collectively, these findings indicate that TLR2-dependent signaling pathways are involved in the recognition of T. crassiceps and in the subsequent activation of the innate immune system and production of inflammatory cytokines, which appear to be essential to limit infection during experimental cysticercosis.