Glycan remodelling of live adult Schistosoma mansoni worms by chemical inhibition of α-mannosidases

Abstract

Schistosomiasis is a neglected tropical disease affecting over 250 million people worldwide. Schistosoma parasites can survive in the human host for years due to their capability to evade and modulate host immune responses. Glycans and glycoproteins produced by schistosomes are thought to play an important role in shaping parasite-host interactions. In addition, N-linked glycans are vital post-translational protein modifications involved in fundamental cellular and developmental processes like protein folding and cell-cell interactions. In this study, we generated live Schistosoma mansoni adult worms with altered N-glycosylation using the α-mannosidase inhibitors kifunensine and swainsonine, compounds which restrict complex N-glycan processing thereby preventing complex N-glycan formation. We show that ex vivo cultured adult schistosomes display a stable N-glycosylation profile during two weeks of culture characterised by roughly one-third mannose and two-third complex glycans. Inhibition of α-mannosidases during culture resulted in a modified N-glycan profile over time: kifunensine-treated parasites were found to contain 76% mannose N-glycans, while swainsonine-treated parasites showed a strongly increased abundance of hybrid glycans and (fucosylated) mannose glycans. These observations are in line with the expected effect of the inhibitors on endoplasmic reticulum and Golgi α-mannosidases, respectively. Additionally, we examined the N-glycan composition of the worm tegument, a major parasitic structure found at the parasite-host interface. The tegument contained mainly complex N-glycans, often carrying the GalNAcβ1-4GlcNAc (LacdiNAc, LDN) motif, different from the rest of the schistosome body. Again, α-mannosidase inhibition changed the N-glycosylation profile of the tegument, similarly as observed for whole worms. No negative effects of any of the treatments on parasite motility or morphology were observed, indicating that the basic biology of the worms in culture was not affected by these N-glycosylation changes. Our results demonstrate the feasibility of creating a live glyco-remodelled parasite, setting the scene for studying functional parasite glycobiology and glycan-mediated effects in host-parasite interaction.

Keywords: Adult worms; N-glycans; Schistosoma mansoni; α-mannosidase inhibition.