Figure 1

Immunoregulatory effects of helminthes on the immune system. Helminthes exert their immunoregulatory actions by modulating cells of both the innate and adaptive immune system. Regarding T-cells, helminthes may promote a Th2-type response and down-regulate Th1/Th17 differentiation, leading to increased Th2-type cytokine (IL-4, IL-5, IL-9, IL-10, IL-13) and decreased Th1/Th17-type cytokine (TNF-α, IFN-γ, IL-6, IL-12, IL-17) secretion. Furthermore, worms’ products enhance Treg cell proliferation, the latter hampering Th1/Th2/Th17 polarization mainly through the secretion of IL-10 and TGF-β. Helminthes also promote a regulatory phenotype of B-cells, DCs, and macrophages. Both tolerogenic DCs and regulatory M2-macrophages contribute to switching from a Th1/Th17 to a Th2/Treg profile. Finally, these parasites may hamper the proliferation of ILC2, a subset of innate immune cells responsible for allergic responses. Thus, helminthes create a tolerant environment ensuring their own survival but also protecting the host from immune-mediated conditions by limiting excessive inflammatory and autoimmune phenomena. We declare that this figure is original. Breg, B-regulatory cell; DC, Dendritic cell; IFN, Interferon; IL, Interleukin; ILC2, Type-2 Innate lymphoid cell; TGF, Transforming growth factor; Th, T-helper cell; TNF, Tumor necrosis factor; Treg, T-regulatory cell.