Comparative metabonomic investigations of Schistosoma japonicum from SCID mice and BALB/c mice: clues to developmental abnormality of schistosome in the immunodeficient host
Authors: Liu Rong , Cheng Wen-jun , Tang Hong-bin , Zhong Qin-ping , Ming Zhen-ping , Dong Hui-fen 
Published: October 2018

It has been discovered that the development of schistosome is hampered in immunodeficient mice, e.g. nude mice lacking T-lymphocytes and the severe combined immune deficient (SCID) mice lacking both T- and B-lymphocytes. However, it’s still unresolved about the underlying regulatory mechanisms of the retarded growth and development of schistosomes in their immunodeficient definitive host. In this study, therefore, five replicates of male or female Schistosoma japonicum samples with twenty male or female worms in each sample, were collected from SCID mice or BALB/c mice at five weeks post infection and used to perform metabonomic analysis using liquid chromatography tandem mass spectrometry (LC-MS/MS) platform, for elucidating the growth and development regulation of schistosome in their definitive hosts from the metabolomic aspect. Based on the identified 1015 ion features in ESI+ mode and 342 ion features in ESI-mode, multivariate modelling methods including the Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) identified distinct metabolic profiles that clearly differentiated both male and female worms in SCID mice from those in BALB/c mice, respectively. Common and uniquely perturbed metabolites and their involved metabolic pathways were identified in male and female worms from SCID mice when compared with those from BALB/c mice. The results also revealed that more differential metabolites were found in female worms (one metabolite was up-regulated and forty metabolites were down-regulated) than male worms (nine metabolites were up-regulated and twenty metabolites were down-regulated) between SCID mice and BALB/c mice. The top five increased metabolites of male worms in SCID mice when compared with those in BALB/c mice were PC(22:6/20:1), L-allothreonine, L-serine, glycerophosphocholine and 5-aminoimidazole ribonucleotide. And the top five decreased metabolites of male worms in SCID mice when compared with those in BALB/c mice were PC(16:0/0:0), PAF C-16, PE(18:1/0:0), adenosine and butenoyl PAF. Most of the differential metabolites of female worms in SCID mice had lower levels when compared with the normal female worms in BALB/c mice, except for retinyl ester with a higher level. The top five decreased metabolites of female worms in SCID mice when compared with those in BALB/c mice were adrenic acid, 5-phosphoribosylamine, PC(16:0/0:0), PC(22:6/20:1) and ergothioneine. The involved metabolic pathways of the differential metabolites in male worms between SCID mice and BALB/c mice mainly included taurine and hypotaurine metabolism, glycerophospholipid metabolism, sphingolipid metabolism, arachidonic acid metabolism, alpha-linolenic acid metabolism, etc. The involved metabolic pathways of differential metabolites in female worms included mainly pyrimidine metabolism, sphingolipid metabolism, arachidonic acid metabolism, glycerophospholipid metabolism, tryptophan metabolism, etc. These findings suggested a correlation between the retarded growth and development of schistosome in SCID mice and their perturbed metabolic profiles, which also provided a new insight into the regulation mechanisms of growth and development of S. japonicum worms from the metabolic level, and provided clues for discovery of drugs or vaccines against the parasites and parasitic disease.

Author summary

The growth and development of schistosome has been discovered hampered in the immunodeficient hosts. But it remains unresolved about the molecular mechanisms involved in this. In this study, we tested and compared the metabolic profiles of the male and female Schistosoma japonicum worms collected from SCID mice or BALB/c mice at five weeks post infection using liquid chromatography tandem mass spectrometry (LC-MS/MS) platform. There were 1015 ion features in ESI+ mode and 342 ion features in ESI-mode were identified, and distinct metabolic profiles were found to clearly differentiate both male and female worms in SCID mice from those in BALB/c mice, respectively. The results also found more differential metabolites in female worms than in male worms between SCID mice and BALB/c mice. The enriched metabolic pathways of the differential metabolites in male worms between SCID mice and BALB/c mice included taurine and hypotaurine metabolism, glycerophospholipid metabolism, sphingolipid metabolism, arachidonic acid metabolism, alpha-linolenic acid metabolism, etc. And the enriched metabolic pathways of differential metabolites in female worms included pyrimidine metabolism, sphingolipid metabolism, arachidonic acid metabolism, glycerophospholipid metabolism, tryptophan metabolism, etc. The findings in this study suggested an association between the developmentally stunted schistosome and their perturbed metabolites and metabolic pathways, which provided a new insight into the regulation mechanisms of growth and development of S. japonicum worms from the metabolic level, and clues for discovery of drugs or vaccines against the parasites and disease.