[Knockdown of IL-33 suppresses the expression of inflammatory factors and NLRP3 to inhibit the inflammatory response in asthmatic mice].

Objective To explore the regulatory mechanism of interleukin-33 (IL-33) on the inflammatory response in asthmatic mice. Methods Using 10 μg/mL of lipopolysaccharide (LPS) to establish a cellular inflammation model of mouse bone marrow mesenchymal stem cells (BMMSCs), the cells were divided into three groups: small interfering RNA of IL-33(si-IL-33) group, IL-33 overexpression (IL-33-OE) group, and model group, based on the transfection status of si-IL-33 plasmid and IL-33-OE plasmid. Real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) was used to detect mRNA expression of IL-33, nucleotide binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3), IL-1β and IL-6. Fluo-3 AM was used to measure calcium ion content, and JC-1 mitochondrial membrane potential detection kit was performed to detect mitochondrial membrane potential changes. An asthma mouse model was established by intraperitoneal injection of sensitizers and activators. According to different treatment plans, the asthmatic mice were divided into si-IL-33 group, IL-33-OE group and model group, with 5 mice in each group. ELISA was used to detect the levels of IL-1β, IL-6 and NLRP3 in mouse serum, while HE staining and Masson staining were performed to assess lung tissue lesions. Results Compared with the model group, the mRNA expression levels of IL-33, NLRP3, IL-1β and IL-6 in the si-IL-33 group were all reduced, while those in the IL-33-OE group were increased. The calcium ion fluorescence was decreased in BMMSCs, while it was increased in the IL-33-OE group. In the si-IL-33 group, JC-1 existed in a polymer form in mitochondria, showing bright red fluorescence and weak green fluorescence, indicating stable mitochondria and normal mitochondrial function. After treating with IL-33-OE plasmid to reduce the mitochondrial membrane potentia, JC-1 cannot exist in polymer form within the mitochondrial matrix. At this point, the red fluorescence intensity inside the mitochondria decreases significantly, while the green fluorescence in the cytoplasm increases significantly. The levels of IL-1β, IL-6, and NLRP3 in the serum of mice in the si-IL-33 group were significantly lower, while those in the IL-33-OE group were significantly higher. In the si-IL-33 group, almost no inflammatory cell infiltration was observed, indicating a relief of inflammation and normal epithelial cell morphology. Additionally, the fibrotic portion of the lung tissue in the si-IL-33 group tended to be normal. The total wall area of bronchus (WAt)/basement membrane perimeter (Pbm) and wall area of bronchial smooth muscle (WAm)/Pbm were reduced in the si-IL-33 group compared with the model group, while they were increased in the IL-33-OE group. Conclusion Knockdown of IL-33 inhibits the inflammatory response in asthmatic mice by downregulating the expression of NLRP3, IL-1β and IL-6.