Hypervirulent Klebsiella pneumoniae serotype K1 induces liver abscess through activating NLRP3 inflammasome / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate whether the hypervirulent Klebsiella pneumoniae (hvKP) induces liver abscess through activating NLRP3 inflammasome. Methods:K1-hvKP and K35-non-hvKP bacterial suspensions were intraperitoneally injected into C57BL/6 mice to establish the models of liver abscess. Human peripheral blood neutrophils were sorted by immunomagnetic beads with CD45 + and Gr-1 + , and the purity was detected by flow cytometry. The concentrations of capsular polysaccharide of K1-hvKP and K35-non-hvKP were detected by total carbohydrate assay kit. The expression of IL-18 and IL-33 by neutrophils at mRNA and protein levels was detected by real-time fluorescence quantitative PCR and ELISA, respectively. The activation of NLRP3 inflammasome in neutrophils was detected by Western blot. Neutrophil extracellular trap formation (NETosis) was observed under confocal laser scanning microscope. Results:The C57BL/6 mice with K1-hvKP infection had significantly serious liver abscess as compared with the K35-non-hvKP-infected mice. The purity of human neutrophils was more than 95%. The concentration of capsular polysaccharide in K1-hvKP was significantly higher than that in K35-non-hvKP. Compared with K35-non-hvKP, K1-hvKP significantly promoted the neutrophils to express IL-18 and IL-33 at both mRNA and protein levels, enhanced the activation of NLRP3 and induced NETosis.Conclusions:This study suggested that hvKP could promote NETosis by activating NLRP3 inflammasome to cause liver abscess.