| Objective: The ALI model of mice was induced by lipopolysaccharide,and the expressions of p-p38 mapk protein in lung tissues,as well as the expression levels of c-fos,c-jun,chemokine IL-8 and MIP-2 mRNA were detected,so as to explore the chemotactic mechanism of neutrophils in the lung during ALI,and provide new ideas for ALI treatment strategies.Methods: 80 healthy C57BL/6 mice were randomly divided into control group(40 mice in group N)and experimental group(40 mice in group L).The N group was intranasally instilled into 50 ?l of PBS solution,and the L group was dropped with an equal amount of lipopolysaccharide solution(20 mg/ml).The experimental mice of each group were collected at four time points of 12 h,24h,48 h and 72 h after administration.Firstly,we observed the pathological damage of lung tissue in each group,calculated the W/D value of lung tissue in each group,counted the percentage of PMNs after collecting BALF,detected the expression of p-p38 MAPK in lung tissue of each group by immunohistochemistry,and detected the expression levels of c-fos,c-jun,IL-8 and MIP-2 in lung tissue of each group by qPCR.Results: 1.General situation: N group of mice had stable breathing,good mental state,normal diet,and rapid activity when grasping mice.The mice in group L had shortness of breath,worse mental state and diet than those in group N,and had slow movement.The above symptoms tended to aggravate with the prolongation of modeling time.2.Results of W/D value in lung tissue of mice in each group: the W/D value in lung tissue of mice in group L was significantly higher than that in group N,and the difference was statistically significant(P<0.05),and the ratio gradually increased with the extension of modeling time.3.Morphology and HE staining of lung tissue specimens of mice in each group: the surface of lung tissue of mice in group N was light pink,with no obvious swelling and bleeding points.HE staining showed that the lung tissue structure was basically complete,with almost no inflammatory cells,red blood cells and fluid exudation.L group showed that the lung tissue of mice had different degrees of edema at various time points,scattered ecchymosis and hemorrhage on the surface of the lung.HE staining showed different degrees of vascular congestion and hemorrhage in lung tissue,and a large number of inflammatory cells,red blood cells and protein-rich liquid infiltrated into the alveolar cavity and interstitial lung,making the alveolar wall thicker and thicker,some alveolar walls ruptured in different degrees,and alveolar cavity fusion enlarged.As time progressed,the pathological changes of lung tissue became more and more serious.4.Immunohistochemical detection of p-p38 MAPK protein expression results: In the immunohistochemical reaction of mice in each group,claybank cells appeared as positive expression,p-p38 MAPK was expressed in lung tissues of mice in L group at different time points.The expression of p-p38 MAPK in lung tissues of mice in L group was significantly higher than that in N group,and there was almost no positive expression in lung tissues of mice in N group.5.Percentage of PMNs in bronchoalveolar lavage fluid(BALF): The percentage of PMNs in group L was significantly higher than that in group N at each time point,and the difference was statistically significant(P<0.05).6.The mRNA expression levels of c-fos,c-jun,MIP-2 and IL-8 in lung tissues were detected by qPCR: The relative expression levels of the four target genes in the L group were higher than those in the N group.The difference was statistically significant(P<0.05).Conclusion: 1.In the LPS-induced mouse ALI model,the expression of p-p38 MAPK,c-fos and c-jun mRNA in the experimental group are increased.It is speculated that the activation of p38MAPK/AP-1 signaling pathway may be related to the early inflammatory response of ALI.2.MIP-2 and IL-8 are highly expressed in the mouse ALI model,suggesting that they play a chemotactic role in the recruitment of PMNs to the site of inflammation. |
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