Fig. 4.

Effect of IL-33 on microglia and Th cell polarization. (1) IL-33 inhibits the transformation of (i) microglia into M1-type to produce TNF-α, IL-1β, IFN-γ, ROS, and NO. (ii) Th cells into Th1 to produce IL-6, IL-12, IL-1β, IFN-γ, and TNF-α. (iii) Th cells into Th17 to produce IL-17. (2) IL-33 promotes the conversion of (i) microglia into M2-type to produce IL-4, IL-13, and IL-10. (ii) Th cells into Th2 to produce IL-4, IL-5, and IL-13. (iii) Th cells into Treg to produce IL-10, IL-35, and TGF-β. (3) The overall effects of IL-33 on the transformation of microglia and Th cells are to inhibit the release of pro-inflammatory cytokines and promote the release of anti-inflammatory cytokines. These regulatory molecules exert their effects on neurons, regulating neuroinflammation and cognitive function