CCL20 production by Eimeria tenella infected chicken epithelial cells: a new mechanism to control the infection?
Résumé
Introduction : Eimeria tenella infection is associated with a severe intestinal disease leading to high economic impact in poultry industry. The cost of vaccine and the emergence of anticoccidial drug resistances highlight the need of alternative strategies. For this purpose, the understanding of host-parasite interaction is needed.
Matériels et méthodes : We first studied the host response to Eimeria tenella in vitro and in vivo. For this purpose, we used a parasite Eimeria tenella expressing a fluorescent protein (YFP or m-cherry) for in vitro and in vivo infection. Non infected cells, cells with sporozoites and schizontes were sorted by flow cytometry and processed for the transcriptomic analysis of the antimicrobial chemokine CCL20. As CCL20 gene expression is regulated at the transcriptional level by various transcription factors such as nuclear factor (NF)-kB itself regulated by receptor-ligand interactions, we measured the induction of NF-kB with Eimeria tenella infection by using human embryonic kidney (HEK)-BlueTM and THP1-XBlue™ cells derived from the human monocytic THP-1 cell line stably expressing an NF-kB-inducible SEAP reporter gene. Moreover, as transcription factors are regulated by kinases such as mitogen activated protein kinases (MAPKs) implicated in diverse cellular processes involved early in infections, we also tested the importance of the p38 MAPK on CCL20 gene expression by using the p38 MAPK inhibitor SB203580. Finally, we tested the effect of recombinant chicken CCL20 and the effect of CCL20 surexpression in chicken epithelial cells on free stages of parasites and its effect on cell invasion.
Résultats : We showed, in both models, an increase in the gene expression of the chemokine CCL20. By using HEK-BlueTM and THP1-XBlue™ cells, we showed that NF-kB is induced by Eimeria tenella infection when the parasite is alive. Moreover, CCL20 gene expression is inhibited by the p38MAPK inhibitor suggesting that p38 MAPK is also involved in the regulation of this pathway. Other data show that surexpression of CCL20 in chicken epithelial cells or addition of recombinant CCL20 in vitro directly affects free stages of parasites then leading to a decrease in cell invasion by the parasite.
Conclusion : Overall, this study describes a signaling pathway by which CCL20 expression is induced in Eimeria tenella infection and its potential effect on free stages of the parasite then limiting the infection. Immunostimulation strategies could present some interest to control the infection.