Virulence-related gene wx2 of Toxoplasma gondii regulated host immune response via classic pyroptosis pathway

Abstract

Abstract Background Toxoplasma gondii is known as the most successful parasite, which can regulate the host immune response through a variety of ways to achieve immune escape. We previously reported that a novel gene wx2 of T. gondii may be a virulence-related molecule. The objective of this study was to explore the mechanism of wx2 regulating host immune response. Methods The wx2 knockout strain (RH wx2−/− strain) and complementary strain (RH wx2+/+ strain) were constructed by the CRISPR/Cas9 technique, and the virulence of the wx2 gene was detected and changes in pyroptosis-related molecules were observed. Results Compared with the wild RH and RH wx2+/+ strain groups, the survival time for mice infected with the RH wx2−/− strain was prolonged to a certain extent. The mRNA levels of pyroptosis-related molecules of caspase-1, NLRP3, and GSDMD and et al. in mouse lymphocytes in vivo and RAW267.4 cells in vitro infected with RH wx2−/− strain increased to different degrees, compared with infected with wild RH strain and RH wx2+/+ strain. As with the mRNA level, the protein level of caspase-1, caspase-1 p20, IL-1β, NLRP3, GSDMD-FL, GSDMD-N, and phosphorylation level of NF-κB (p65) were also significantly increased. These data suggest that wx2 may regulate the host immune response through the pyroptosis pathway. In infected RAW264.7 cells at 48 h post-infection, the levels of Th1-type cytokines of IFN-γ, Th2-type cytokines such as IL-13, Th17-type cytokine of IL-17 in cells infected with RH wx2−/− were significantly higher than those of RH and RH wx2+/+ strains, suggesting that the wx2 may inhibit the host's immune response. Conclusion wx2 is a virulence related gene of T. gondii, and may be involved in host immune regulation by inhibiting the pyroptosis pathway. Graphical Abstract

Keywords

• wx2 gene
• Toxoplasma gondii
• Virulence
• Pyroptosis
• Host immune response