Figure 6

Schematic illustration of potential mechanisms of human amnion epithelial cell (hAEC)-mediated immune regulation. Upon stimuli from inflammatory cytokines such as interferon-gamma (IFNγ) and tumour necrosis factor-alpha (TNFα), (i) hAECs synthesize transforming growth factor-beta (TGF-β), thus reducing inflammation by inhibiting effector T-cell proliferation. (ii) TGFβ induces maturation of T cells into regulatory T cells (Tregs), which polarises surrounding resident macrophages toward an M2 phenotype. (iii) M2 macrophages begin the cascade of resolution by increasing their phagocytic activity through mannose receptor, CD206. (iv) Repair is followed closely by pro-angiogenic factors Arg-1 and found in inflammatory zone protein-1 (FIZZ-1), which are also expressed by M2 macrophages.