Abstract: Objective To investigate the clearance mechanism of NLRP3 against Pseudomonas aeruginosa (PA) based on TLR4 / NF-κB pathway. Methods PA-infected HP-1-induced differentiated macrophages and primary human monocyte-derived macrophages were used for following experiments. NLRP3 and TLR4 were later silenced in macrophages by siRNAs (si-NLRP3 and si-TLR4), and the expression levels of IL-1β and IL-8 in the supernatant were detected by ELISA. The mRNA expression levels of NLRP3 and caspase-1 were detected by RT-PCR. The protein expression levelsof TLR4 and p-NF-κB P65 were detected by Western blotting. Results The levels of IL-1β, IL-8,the mRNA expression levels of NLRP3, caspase-1 and TLR4, and the protein expression level of pNF-κB P65 were significantly increased in the supernatants or cells of the PA-infected THP-1-induced differentiated macrophages and primary human monocyte-derived macrophages hMDMs (P <0. 05). The levels of IL-1β, IL-8, the expression levels of NLRP3, caspase-1 mRNA and TLR4,p-NF-κB P65 protein in the supernatants of the si-NLRP3 and si-TLR4 groups (NLRP3 and TLR4were silenced in THP-1-induced differentiated macrophages and primary human monocyte-derivedmacrophages hMDMs) were significantly reduced when compared with those in the si-NC group (P< 0. 05). The clearance rate was significantly increased in NLRP3 and / or TLR4 silenced PA-infected THP-1 macrophages and primary human monocyte-derived macrophage hMDMs when comparedwith that in the si-NC group (P < 0. 05). Conclusion Silencing NLRP3 increases the clearance of Pseudomonas aeruginosa by macrophages, and the mechanism may be related to the inhibition ofTLR4 / NF-κB signaling pathway activation.

Key words: TLR4 / NF-κB pathway, NLRP3, Pseudomonas aeruginosa, macrophages