Effect Of Interleukin-33 On The Pyroptosis And Immune Dysfunction Of Dendritic Cells In Septic Mice

Objective: To investigate the effect of interleukin-33(IL-33)on the pyroptosis of mouse splenic dendritic cells(DCs)and its relationship with immunosuppression in the setting of septic challenge.Methods: Normal mice were randomly divided into CLP group,sST2-treatment group and sham group.The cecal ligation and perforation(CLP)mouse model was used to mimic sepsis.Mice in sham group were treated with the same operation as in CLP group,except for cecal perforation.In the sST2-treatment group,recombinant sST2(to neutralize the Biological function of IL-33)was injected intraperitoneally 1 hour after CLP procedure(10 ?g /mouse,in 200 ?L PBS),and the same volume of PBS was injected in the control CLP group.In the IL-33 group,recombinant mouse IL-33(rmIL-33)was injected intraperitoneally(5 ?g/mouse,in 200 ?L PBS),and the same volume of PBS was injected in the control group.DCs were isolated and purified from mice spleens with immunomagnetic beads.The splenic DCs of normal mice were cultured in vitro and stimulated with recombinant IL-33 at different concentrations(0,1,10,100 ng/mL)and at different times(12 and 24 hours).The expressions of CD80,CD86,and major histocompatibility complex(MHC)-II on the surface of DCs and the rate of pyroptosis of DCs in every group were determined with flow cytometry.The expressions of IL-33 and pyroptosis related proteins in DCs were determined by confocal laser microscope.The protein level of IL-33 in mice spleens and DCs and The expressions of pyroptosis related proteins in DCs were detected by Western blotting.Results: 1.The protein levels of IL-33 in spleen and in splenic DCs were all increased in CLP mice.Compared with the sham group,the rate of pyroptosis of splenic DCs was increased in a time-dependent manner in CLP mice.And,the protein levels of Caspase-1(CASP-1),NLRP3,IL-1? and IL-33 were upregulated after CLP.Moreover,levels of CD86 and major histocompatibility complex(MHC)-? on surface of splenic DCs were markedly down-regulated in CLP mice(P<0.01).2.Stimulation with rmIL-33(10 ng/mLfor 24 h)could induce obviously dysfunction of DC.Levels of CD86 and MHC-?on the surface of DC isolated from the spleen of normal mice decreased after cultured with rmIL-33 in vitro(P<0.05).And also in vivo,the rate of pyroptotic of splenic DCs was increased in mice injected with rmIL-33(5 ?g/mouse)intraperitoneally for 24 h.And the expression of CASP-1,ASC and IL-1? was significantly upregulated.Moreover,the levels of CD80,CD86 on surface of DCs were decreased(P<0.01).3.Treatment with sST2 in CLP mice could decrease DC pyroptosis and downregulate the levels of CASP-1,NLRP3 and IL-1?.Furthermore,sST2 could promote the expression of related markers(CD80,CD86,MHC-?)on the surface of DC that decreased in CLP mice(P<0.01).Conclusion: The pyroptosis and dysfunction of splenic DCs in CLP mice was related with the increased level of IL-33 in mice spleen and DCs.Treatment with sST2 could obviously decrease the pyroptosis of DCs,improve DC function and play a protective role during sepsis.