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Abstract

Schistosomes are digenetic trematodes which cause schistosomiasis, also known as bilharzia, one of the main parasitic infections in man. In tropical and subtropical areas an estimated 200 million people are infected and suffer from the debilitating effects of this chronic disease. Schistosomes live in the blood vessels and strongly modulate the immune response of their host to be able to survive the hostile environment that they are exposed to. It has become increasingly clear that glycoconjugates of schistosome larvae, adult worms and eggs play an important role in the evasion mechanisms that schistosomes utilise to withstand the immunological measures of the host. Upon infection, the host mounts innate as well as adaptive immune responses to antigenic glycan elements, setting the immunological scene characteristic for schistosomiasis. In this review we summarise the structural data now available on schistosome glycans and provide data and ideas regarding the role that these glycans play in the various aspects of the glycobiology and immunology of schistosomiasis.

CD209a Expression on Dendritic Cells Is Critical for the Development of Pathogenic Th17 Cell Responses in Murine Schistosomiasis

“…CLRs are a large family of calcium-dependent receptors that bind glycans on both pathogen and host cell surfaces, facilitating recognition of a wide range of glycosylation patterns [21,22]. Schistosome-specific glycans, both O- and N- linked, are rich in fucose and include Le X , polyLe X , pseudo Lewis Y (Le Y ), LDN, LDN-F, CAA, F-LDN, F-LDN-F, and HexNAc-DF [23,24,26]. Such glycans are heavily expressed on the surface of S. mansoni eggs and are actively secreted in the form of soluble glycoproteins [44].…”

DC-SIGN Mediates Binding of Dendritic Cells to Authentic Pseudo-LewisY Glycolipids of Schistosoma mansoni Cercariae, the First Parasite-specific Ligand of DC-SIGN

“…The abundant expression of such self-glycans or glycan antigens that mimic self-glycans, may allow schistosomes to mislead the host immune system by down-regulating DC function in all stages of infection. However, DC-SIGN has been shown to internalize schistosome glycoconjugates 3 and could also play a role in processing of these glycoconjugates and antigen presentation. Because currently more than 200 million people have schistosomiasis, it is challenging to understand the central role of DCs in both the strong immune response that is evoked upon infection, as well as in the immune evasion and suppression mechanisms that are exploited by the schistosomes.…”

“…3 The instrument was operated in the positive-ion reflector mode throughout using 6-aza-2-thiothymine (Sigma-Aldrich) as matrix. About 100 -500 spectra were summarized in each case.…”

“…These glycoconjugates are often developmentally regulated antigens that are expressed during different life cycle stages. Proteins of different schistosoma life cycle stages carry both N-and O-glycans (2,3). In addition, schistosomes synthesize highly immunogenic glycosphingolipids, especially in the egg and cercarial stage (4,5).…”

Deciphering the glycogenome of schistosomes

“…Subsequent studies (Bergwerff et al, 1994; Van Dam et al, 1994; Khoo et al, 1995, 1997a,b; Frank et al, 2012) (also see reviews by Cummings and Nyame, 1996, 1999; Hokke and Deelder, 2001; Hokke and Yazdanbakhsh, 2005; Hokke et al, 2007; Prasanphanich et al, 2013) identified complex types of glycan structures in both membrane associated and circulating antigens. These types of studies, now generally recognized as structural glycomics , involve complex analyses incorporating tandem mass spectrometry (MS), nuclear magnetic resonance (NMR) and compositional and linkage analyses.…”