Figure 13.
Factors that have a regulatory role in the formation of different subsets of T helper cells. RSVs = Resolvins; PRTs = Protectins; MaRs = Maresins; LXA4 = Lipoxin A4; LTs = Leukotrienes; TXs = Thromboxanes; NO = Nitric oxide; CO = Carbon monoxide; H2S = Hydrogen peroxide; TGF-β = Transforming growth factor β; IFN-γ = Interferon-γ. Naive CD41 T cells differentiate into T helper cells: TH1, TH2, and TH17. TGF-β converts naive T cells into FOXP3-expressing induced Treg (iTreg) cells. T helper cell differentiation needs T-bet, GATA3, and ROR-γt. Terminally differentiated T helper cells produce a specific combination of effector cytokines needed for the adaptive immune system. TGF-β, retinoic acid, or cytokines: IL-6, IL-1, IL-23, or IL-27 secreted by the innate immune system cells (immature or activated dendritic cells (DCs), respectively) dictate whether a naive T cell develops into a FOXP31 Treg cell, a TH17 cell, or otherwise. PGE2 through its receptor EP4 on T cells and dendritic cells facilitates TH1 cell differentiation and amplifies IL-23-mediated TH17 cell expansion. Bioactive lipids modulate the generation, proliferation, and function of several immunocytes, and their secretion of soluble mediators and nitric oxide (NO)/carbon monoxide (CO)/hydrogen sulfide (H2S) has a modulatory action on various immunocytes and their actions, as shown in the figure. This figure is taken from reference [56]; for more details, see reference [56].