pORF5 plasmid protein of Chlamydia trachomatis induces IL-1βand IL-18 production through NALP3 inflammasome activation / 中国免疫学杂志

ABSTRACT

Objective:To investigate whether pORF5 plasmid protein of Chlamydia trachomatis(Ct) induces 1L-1βand 1L-18 production in THP-1 cells,and its potential molecular mechanism.Methods:pORF5 plasmid protein was used to stimulate THP-1 cells at different concentrations(0,3,6,12,24,36 μg/ml),then the inflammatory cytokines IL-18 and IL-1βwere detected by ELISA at the time of 0,8,16,24,36 h;The mRNA expression of NALP3 inflammasome were detected by Realtime-PCR,and Caspase-1 activity was determined by Western blot analysis.THP-1 cells were transfected with siRNA targeting NALP3 and ASC gene for 24 h or pretreated with Caspase-1 inhibitor(Z-YVAD-FMK) for 30 min,and subsequently stimulated with pORF5(24 μg/ml) for 24 h,then secretion of IL-1βand IL-18 were analyzed by ELISA.Results: The pORF5 plasmid protein induced THP-1 cells to secrete IL-1βand IL-18 by dose-and time-dependent manners,production of IL-1βand IL-18 reached their peaks(491 pg/ml and 186 pg/ml) at concentration of 24 μg/ml,and the peak amount of IL-1βand IL-18 occurred at 24 h and 16 h post-stimulation respectively.pORF5 plasmid protein in-creased mRNA expression of NALP3 inflammasome and activated Caspase-1 in THP-1 cells.NALP3 siRNA,ASC siRNA and Z-YVAD-FMK reduced pORF5-induced IL-1βand IL-18 production when compared with control groups(P<0.05).Conclusion:pORF5 plasmid protein could induce THP-1 cells to produce IL-1βand IL-18 through NALP3 inflammasome activation,which may play an important role in the pathogenesis in Ct infection.