Fig. 4: The T. gondii antigen alters the signaling pathway of the host cell.
From: Exploring the potential of Toxoplasma gondii in drug development and as a delivery system
T. gondii antigens, including MICs, ROPs, GRAs, and SAGs, manipulate host cell signaling pathways. a In DCs, STAg induces the expression of SOCS2 via LXA4 and consequently suppresses IL-2 expression and CCR5 secretion. ROP5 and ROP18 suppress MHC I antigen presentation by resisting IFN-γ and IRG. b In macrophages, MIC1 and MIC4 bind to TLR4; induce the secretion of IL-12, TNF-α, and IL-6 through NF-κB; and translocate TLR4 to endosomes to produce the anti-inflammatory cytokine IL-10. SAG-1 and SAG-2 induce IL-1/IL-6/GM-CSF/TNF-α transcription in macrophages. GRA9 disrupts NLRP3 inflammasome assembly by blocking the binding of ASC to NLRP3 and consequently suppressing IL-1β and IL-18 secretion. ROP5, ROP18, and GRA7 inhibit MHC I antigen presentation by resisting IFN-γ and IRG. ROP16 activates STAT3- and STAT6-dependent M2 macrophages and induces the expression of the M2 macrophage marker Arg-1 and the secretion of IL-1 and IL-1ra.
