Fig. 2.

Mechanisms of regulatory T cells (Tregs) increase during sepsis. The increase of Tregs in sepsis is mediated by the production of TGF-β ± IL-10 by dendritic cells, monocytes/macrophages and MDSCs. Moreover, the injured tissues produce IL-33 which in turn activates ILC2 cells. Activated ILC2 cells release IL-4 and IL-13, cytokines responsible for a polarization of macrophages toward a M2 phenotype, which release TGF-β. DCs: dendritic cells; Treg: regulatory T cells; MDSC: myeloid-derived suppressor cells; TGF-β: transforming growth factor β; CTLA-4: cytotoxic T-lymphocyte-associated protein 4; IL-10: interleukin 10; IL-4: interleukin 4; IL-33: interleukin 33; ILC 2: type 2 innate lymphoid cells, M2: type 2 macrophage