The excretory-secretory products of Echinococcus granulosus protoscoleces directly regulate the differentiation of B10, B17 and Th17 cells.

Background: Excretory-secretory products (ESPs) released by helminths are well-known to regulate T cell responses in the host. However, their direct influence in the differentiation of naïve T cells, and especially B cells, remains largely unknown. This study investigated the effects of Echinococcus granulosus protoscoleces ESPs (EgPSC-ESPs) on the differentiation of IL-10-producing B cells (B10), IL-17A-producing B cells (B17) and Th17 cells.

Methods: BALB/c mice injected with EgPSC were used to evaluate the in vivo profiles of B10, B17 and Th17 cells. In vitro purified CD19 B and naïve CD4 T cells were cultured in the presence of native, heat-inactivated or periodate-treated EgPSC-ESPs, and the differentiation of these cell subsets were compared.

Results: In contrast to the control group, infected mice showed higher frequencies of B10, B17 and Th17 cells, and higher levels of IL-10 and IL-17A in the sera. Interestingly, B17 cells were first identified to express CD19CD1d. In vitro, B cells cultured with native ESPs exhibited a higher percentage of B10 cells but lower percentage of B17 and Th17 cells compared to the PBS group. Moreover, the relative expression of IL-10 and IL-17A mRNA were consistent with the altered frequencies. However, ESPs subjected to heat-inactivation or periodate treatment exhibited an inverse effect on the induction of these cell subsets.

Conclusions: Our findings indicate that ESPs released by EgPSC can directly regulate the differentiation of B10, B17 and Th17 cells, which appear to be heat-labile and carbohydrate-dependent.