TLR-4 involvement in pyroptosis of mice with pulmonary inflammation infected by Actinobacillus pleuropneumoniae

Abstract:

Abstract:［Objective］Pyroptosis is a caspase-1 dependent programmed cell death and involves pathogenesis of infectious diseases by releasing many pro-inflammatory cytokines to induced inflammation．TLR-4 plays an important role in mediating pathogenesis of some infectious diseases． In this study，we detected the expression of TLR-4 and some molecules (e．g caspase-1，TNF-α，IL-1β，IL-6，IL-18) related with pyroptosis to determine its involvement and mechanisms of pulmonary inflammation in mice infected by A．pleuropneumoniae．［Methods］ Mice were intranasally infected by A．pleuropneumoniae and killed 48 hours post infection．Pulmonary gross lesion and histological pathology by H-E were observed． Expression levels of caspase-1，caspase-3，TNF-α，IL-1β，IL-6，IL-18，and TLＲ-4 in lung of mice were detected by RT-PCR and qPCR．［Results］Serious pulmonary hemorrhage and inflammation in infected mice were observed． Expression levels of caspase-1，caspase-3，TNF-α，IL-1β，IL-6，IL-18 and TLR-4 increased，and expression levels of caspase-3 were not changed in lung of infected mice．［Conclusion］ TLＲ-4 might be involved in pulmonary inflammation of mice infected by A．pleuropneumoniae． After induced by activated TLR-4 some cells in this lesion expressed pro-inflammatory cytokines．These cytokines would induce pulmonary inflammation． This lesion might involve pyroptosis with caspase-1 expression．