【Abstract】 Objective To investigate the regulatory effect of microRNA-146a (miR-146a) on nucleotide-binding oligomeric domain-like receptor protein 3 (NLRP3) and its role in ventilator induced lung injury (VILI) and its mechanism. Methods MLE-12 cells were cultured in vitro and divided into cycle stretching 0,2 and 4 hours (CS0h, CS2h, CS4h); After overexpression of miR-146a, the rats were divided into negative control+cycle stretching 0h group (NC+CS0h), miR-146a overexpression+cycle stretching 0h group (miR-146a mimic+CS0h), negative control+cycle stretching 4h group (NC+CS4h), miR-146a overexpression+cycle stretching 4h group (miR-146a mimic+CS4h); After transfection of miR-146a inhibitor to inhibit miR-146a activity, the rats were divided into four groups: negative control+cycle stretching 0h group (NC+CS0h), miR-146a inhibitor+cycle stretching 0h group (miR-146a inhibitor+CS0h), negative control+cycle stretching 4h group (NC+CS4h), miR-146a inhibitor+cycle stretching 4h group (miR-146a inhibitor+CS4h);After overexpression of miR-146a, autophagy lysosome pathway inhibitor chloroquine (CQ), ubiquitin proteasome inhibitor MG132 and protein synthase inhibitor cycloheximide (CHX) were used respectively. They were divided into negative control group (NC), miR-146a overexpression group (miR-146a mimic), negative control+autophagy lysosomal pathway inhibitor group (NC+CQ), miR-146a overexpression+autophagy lysosomal pathway inhibitor group (miR-146a mimic+CQ), negative control+ubiquitin proteasome inhibitor group (NC+MG132), miR-146a overexpression+ubiquitin proteasome inhibitor group (miR-146a mimic+MG132), negative control+protein synthase inhibitor group (NC+CHX). MiR-146a overexpression+protein synthase inhibitor group (miR-146a mimic+CHX); The protein expressions of E-cadherin, Occludin and NLRP3 were detected by Western blot, and the expression of miR-146a was detected by real-time fluorescence quantitative (RT-qPCR). Results Compared with CS0h group, the expression of E-cadherin, Occludin and miR-146a in CS4h group decreased significantly (P0.01, P0.001, P0.01), while the expression of NLRP3 increased significantly (P0.001). Compared with NC+CS0h group, the expression of NLRP3 protein in miR-146a mimic+CS0h group decreased (P0.01)NLRP3 protein expression increased (P0.01) in miR-146a inhibitor+CS0h group . Compared with NC+CS4h group, the expression of NLRP3 protein in miR-146a mimic+CS4h group decreased (P0.001), while the expression of E-cadherin and Occludin protein increased (P0.05, P0.01); NLRP3 protein expression increased (P0.05) and E-cadherin and Occludin protein expression decreased (P0.05, P0.05) in miR-146a inhibitor+CS4h group compared with NC+CS4h group. Compared with miR-146a mimic group, there was no significant change in NLRP3 protein expression in miR-146a mimic+CQ group and miR-146a mimic+MG132 group (P0.05). The expression of NLRP3 protein was increased(P0.01) in miR-146a mimic+CHX group. Conclusion After cycle stretching, the expression of miR-146a decreased and the expression of NLRP3 increased, which activated the excessive activation of inflammatory response and led to the degradation of epithelial barrier-related connexins E-cadherin and Occludin to form VILI. MiR-146a may inhibit the expression of NLRP3 through protein synthesis pathway to alleviate inflammation and thus alleviate VILI.