Effect of LPS combined with ATP on the expression of IL-1β of human A549 cells regulated by NLRP3 inflammasome and its mechanism / 解放军医学杂志

ABSTRACT

Objective To investigate the expression and the mechanism of interleukin-1 beta (IL-1β) in human A549 cells regulated by lipopolysaccharide (LPS) combined with adenosine triphosphate (ATP). Methods The protein expressions of NLRP3, ASC and caspase-1 in A549 cell lines were firstly assessed by Western blotting, and then the effects of different concentrations (0, 1, 5, 10, 50 and 100µg/ml) of LPS on the protein expression of NLRP3 inflammasome pathway and the secretion of IL-1β in A549 cell lines were determined by Western blotting and ELISA, respectively. Secondly, the effects of co-stimulation of LPS and ATP on the activation of inflammasome and the secretion of IL-1β in A549 cell lines were detected. Finally, the effects were observed of siRNA interference to the NLRP3 gene expression in A549 cell lines on the secretion of proinflammatory cytokines-IL-1β induced by LPS+ATP. Results NLRP3, ASC and caspase-1 proteins were observed in A549 cell lines. The expressions of NLRP3, caspase- 1p45 and pro-IL-1β in A549 cell lines increased by treatment of LPS alone compared with that of control group (P<0.05) in a dosedependent manner, but no expression of caspase-1p20 protein and no secretion of cytokine IL-1β were detected. While the expression of activated caspase-1p20 protein and the secretion of cytokine IL-1β were found by co-stimulation of LPS+ATP compared with that of LPS alone stimulation group (P<0.05). After siRNA interference of the expression of NLRP3 gene, the LPS+ATP-induced release of proinflammatory cytokines-IL-1 β was inhibited significantly (P<0.05). Conclusions The NLRP3 inflammasome pathway is present in A549 cell lines. The release of cytokines-IL-1β in LPS+ATP-induced A549 cell lines decreases after down-regulation of NLRP3 genes, implying the release of cytokines-IL-1 β may be regulated by the NLRP3 inflammasome pathway.