Notch signaling pathway involved in Echinococcus granulosus infection regulates dendritic cell development and differentiation.

Introduction: The Notch signaling pathway is involved in the development of many diseases; it regulates the development of dendritic cells (DCs), and affects the immune response of DC-mediated T cells. We previously found that ferritin and malate dehydrogenase (mMDH) in Echinococcus granulosus (E.granulosus) induced different immune responses through sensitized DCs. Therefore, in the study we explored whether the Notch signaling pathway affects the development and differentiation of DCs, causing changes in the immune response of DCs sensitized with E. granulosus antigens, and clarified whether it is involved in E.granulosus infection. Methods: We used the Notch signaling pathway inhibitor [N-[3,5-difluorophenace-tyl] -L-alanyl]-S-phenylglycinet-butyl ester (DAPT) or activator Jagged1 to construct in vitro cell models with blocked or activated Notch signaling respectively. We analyzed the effect of Notch signaling on the development and differentiation of DCs by detecting their morphology, migration function, capacity to promote T cell proliferation, and cytokine secretion. We observed the changes in DC response to E. granulosus antigens and the mediated immune response. Results: DAPT inhibited the development and maturation of DCs, which were in a non-responsive or incompetent state, reduced the sensitization of DCs to Eg.ferritin, weakened the migration ability of DCs, disrupted their ability to mediate T-cell proliferation, reduced DC expression of MHCII, CD80, CD60, and CD40 co-stimulatory molecules, prevented the secretion of cytokines and attenuated the expression of Notch1, Notch2, Notch3 receptors, Jagged1, Delta-like 4 (Delta4), and Hes1. Following Jagged1 addition, the function of DCs was restored to some extent, and the expression of Notch1, Delta4 and Hes1 was activated in response to the stimulation of Eg.ferritin. However, Eg.mMDH stimulated DCs to produce an immune response showing weak interference by DAPT and Jagged1. Discussion: The study suggests that the Notc h signaling pathway is involved in the Eg.ferritin-sensitized DC-mediated immune response, which may become a new target for treating E.granulosus infection.

Impact of Echinococcus granulosus Antigens on Monocyte Development and Dendritic Cell Differentiation.

Background: Different subtypes of dendritic cells (DCs) can induce different types of immune responses. Our previous study found that Echinococcus granulosus (E. granulosus) antigens (Eg.ferritin, Eg.mMDH and Eg.10) stimulated DC differentiation to different subtypes and produced different immune responses. Objective: To further understand whether Eg.ferritin, Eg.mMDH and Eg.10 affect the DC-mediated immune response by promoting the differentiation of monocytes to DCs. Methods: Bone marrow-derived monocytes were exposed to three antigens of E. granulosus on days 0, 3, 5, and 7. The percentage of monocyte-derived DCs (moDCs), DCs subsets, and the expression of surface molecules of DCs at different time points in different groups were assessed by flow cytometry. The levels of cytokines of IL-1ß, IL-4, IL-6, IL-10, IL-13, IFN-γ, TNF-α, IL-12p70, IL-18, IL-23, and IL-27 in the cell culture supernatant were detected by multi-factorial detection technology. Results: The percentage of moDCs revealed that none of the three antigens blocked monocyte differentiation to DCs. The monocytes of 7-day-old cultures showed increased sensitivity to these antigens. The Eg.ferritin induced more mature DCs, which expressed high levels of MHC II and costimulatory molecules, and secreted Th1 cytokines. Eg10 and Eg.mMDH induced lower degrees of DC maturation, however differentiated DCs were in a semi-mature state due to low expression of MHC II and costimulatory molecules and secretion of higher Th2 and lower Th1 cytokines. Conclusion: Eg.ferritin promotes full maturation of DCs and induces Th1 immune response, whereas Eg.10 and Eg.mMDH induce semi-mature DCs producing higher levels of Th2 cytokines.