IL-25 and HDM co-operated to upregulate HLA-DR, PD-L1 and OX-40L expression on eosinophils from allergic asthma patients
Effective antigen presentation requires expression of both MHC-II and co-stimulatory molecules on APCs, so we firstly examined whether IL-25 had an impact on the expression of those co-stimulatory molecules of eosinophils from allergic asthmatics in vitro. When stimulated with both HDM and IL-25 for 18 h, the expression of HLA-DR, PD-L1 and OX-40L of cultured eosinophils was found to be significantly increased compared with control group. HLA-DR expression was also elevated in HDM+IL-25 group compared to HDM or IL-25 alone group. The expression of PD-L1 was significantly higher when cultured with HDM+IL-25 than HDM alone (Figure 1).
IL-25 and HDM co-sensitized eosinophils promoted Th2 differentiation of autologous Naïve CD4+ T cells from allergic asthma patients
Eosinophils were pulsed with HDM and/or IL-25 for 18 h, and then went through a coculture procedure with autologous Naïve CD4+ T cells for up to 48 h. Intracellular cytokines expression was tested by flow cytometry. Signature effector cytokines IFN-γ, IL-4, IL-9 and IL-17A were selected to stand for Th1, Th2, Th9 and Th17 cells, respectively. When treated with both IL-25 and HDM, eosinophils further promoted differentiation of autologous Naïve CD4+ T cells towards Th2 cells, which was unseen in IL-25 or HDM mono-stimulation group. Comparatively, in groups where eosinophils were absent, IL-25 and HDM separately were unable to promote Th cell differentiation effectively (Figure 2).