Cutaneous interleukin-7 transgenic mice display a propitious environment to Schistosoma mansoni infection

Interleukin (IL)-7 is produced early in Schistosoma mansoni-infected human and murine skin and was recently shown to favour parasite development. In the present work, we investigated the participation of keratinocyte-derived IL-7 in this process. Keratinocytes are the predominant cellular constituents of the epidermis and the first tissue encountered by the parasite when it infects the vertebrate host. We therefore infected IL-7 cutaneous transgenic mice and compared several parasitological and immunological parameters to those of infected littermate controls. In transgenic mice, an increased number of total adult worms was observed while egg number and female fecundity remained unchanged. Additionally, transgenic animals displayed a more intensive hepatic fibrosis. In parallel, infected IL-7 transgenic animals showed a dominant Th2-type humoral response towards egg antigens. The results presented here confirm and reinforce the key role play by IL-7 in S. mansoni-vertebrate host interplay, beginning with keratinocyte-derived IL-7.