Studies on the establishment of a co-culture system of lung stage Schistosoma japonicum with host cells

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Due to their role in eliciting protective Th1 cell-mediated immune responses in definitive hosts lung stage schistosomula are in the focus of intensive research. In vitro culture approaches in the past exhibited significant differences in gene expression profiles between lung stage schistosomula isolated from hosts and those cultured conventionally. Therefore, new approaches to culture schistosomula are of broad interest. In the present study, co-culture systems of schistosomula of Schistosoma japonicum and different vertebrate host cells were tested. Among these, human hepatic venous endothelial cells (ED25) turned out to be very suitable and interesting feeder cells. Compared with controls cultured in vitro or co-cultured with other cells, schistosomula co-cultured with ED25 cells shared more similarities in morphology and tegumental structures with schistosomula directly obtained from infected mice as microscopically determined. According to results from a suppression subtractive hybridization approach to compare transcriptional differences of co-cultured and host group or control group parasites, four candidate transcripts encoding cathepsin L precursor, heat shock protein 70, glyceraldehyde 3-phosphate dehydrogenase, and programmed cell death protein 10 were shown to be differently expressed among the three groups by real-time PCR. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis finally confirmed not only congruent protein patterns but also interesting differences among the compared schistosomula groups. The co-culture system between schistosomula of S. japonicum and ED25 cells established in the present study improved existing cultivation attempts. Although some differences to host-derived schistosomula were still observed, co-culture with ED25 cells positively influenced parasite morphology and gene expression in a more host-like manner.