Eimeria tenella 14-kDa phosphohistidine phosphatase stimulates maturation of chicken dendritic cells and mediates DC-induced T cell priming in a Th1 cytokine interface

Given the central role of dendritic cells (DCs) in directing cell-mediated immunity, this study investigated the capability of Eimeria tenella 14-kDa phosphohistidine phosphatase (EtPHP14) to mature chicken DCs and initiate DC-induced T cell immunity. With the aim of identifying novel protective Eimeria antigen, EtPHP14 gene was successfully cloned and EtPHP14 recombinant protein (rEtPHP14) was expressed in Escherichia coli expression system. rEtPHP14 binding was identified on the surface of chicken DCs by Immunofluorescence assay. DC phenotypes were evaluated by flow cytometry and results indicated that MHCII, CD80, CD86, CD1.1 and CD11c were up-modulated in DCs following rEtPHP14 treatment. RT-qPCR showed increased transcript levels of DC maturation markers CCL5, CCR7 and CD83 in rEtPHP14-treated DCs. Moreover, transcript profile of genes associated with intracellular signaling pathways that characterize the immunogenic (TLR signaling) or tolero-genic (Wnt signaling) state of DCs revealed that TLR signaling was stimulated and Wnt signaling was inhibited in rEtPHP14-treated DCs. Furthermore, proliferation of T cells and differentiation of CD4+ cells were promoted when rEtPHP14-treated DCs were co-cultured with autologous T cells. DCs incubated with rEtPHP14 alone expressed increased IL-12 and IFN-gamma levels while IL-10 and TGF-beta levels remained unaffected. Likewise, similar trend of IFN-gamma expression was noted in rEtPHP14 treated DC-T cell coculture, whereas IL-4 expression remained unchanged. These findings indicate that EtPHP14 is an important molecule that can upregulate host immune response, particularly Th1, during host-parasite interaction, suggesting its importance as a novel candidate for coccidiosis vaccine.