Preliminary Study On The Effects And Mechanisms Of S100A9 In Regulating Airway Inflammation In Asthmatic Mice

S100A9 is a member of the calcium binding protein family,which is mainly expressed in monocytes and neutrophils,and is involved in the inflammatory response of rheumatoid arthritis,psoriatic arthritis,glomerulonephritis,asthma and other diseases.Studies have indicated that the expression abundance of S100A9 is related to the severity of asthma.The previous study of our group found that the expression of S100A9 gene in asthmatic airway tissues was significantly up-regulated,but the mechanism of S100A9 in the pathogenesis of asthma is still unclear.In order to further clarify the regulatory effect and mechanism of S100A9 in asthma,the regulatory effect and mechanism of S100A9 on asthma inflammation in mice were studied basing on S100A9 gene-edited mice obtained using CRISPR/Cas9 method,and obtained results are as the following:1.S100A9 gene-edited mice were prepared by CRISPR/Cas9 method.The results showed that the designed two pairs of sg RNAs successfully knocked out some exons 2,3 and intron 2of the S100A9 gene,totaling 2492 bp.S100A9 gene expression profile analysis showed that S100A9 was highly expressed in the lung and spleen tissues of wild-type mice.However,no obvious expression of S100A9 was detected in the lung and spleen tissues of gene-edited mice,indicating that the S100A9 gene was successfully knocked out.After testcross reproduction,stable inherited S100A9 gene-deficient mice were obtained.2.To explore the regulatory effect of S100A9 on asthma inflammation through the mouse asthma model stimulated by OVA.Detection of S100A9 gene transcription and protein levels found that the expression of S100A9 in the lung tissue of asthmatic mice was significantly upregulated,indicating that S100A9 may play a regulatory role in the occurrence of asthma.The results of lung tissue pathological section analysis showed that the lack of S100A9 function can significantly enhance the infiltration of airway inflammatory cells and airway wall remodeling in mice.The results of lung function test showed that the lack of S100A9 function significantly increased airway resistance in mice.Bronchoalveolar lavage fluid inflammatory cell count and inflammatory factor test results showed that the level of eosinophils were significantly increased,and the levels of inflammatory cytokines such as IL-1β,TNF-α,i NOS and other inflammatory factors were aslo significantly increased,while the level of IL-10 was significantly decreased in asthmatic mice lacking S100A9 function.3.A preliminary study on the mechanism of S100A9 dysfunction causing exacerbation of airway inflammation in asthma.The results showed that the loss of S100A9 function caused a significant increase in the expression of S100A9 receptors such as RAGE and TLR4 in asthmatic mice.Further detection of inflammatory pathway-related proteins showed that the phosphorylation levels of NF-κB and MAPK in S100A9 function-deficient mice increased significantly.The above results indicate that S100A9 plays a regulatory role in inhibiting asthma airway inflammation,airway remodeling,and airway hyperresponsiveness by affecting the activation of inflammatory pathways such as NF-κB and MAPK,and the lack of function of this gene can enhance inflammation response and exacerbate asthma.The above research results will provide new ideas and materials for the development of asthma treatment drugs with S100A9 as the target.