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

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-1ß, 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-1ß, 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-1ß, 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.