| Objective: To investigate the changes of IL-17 and TGF-β1 in mouse lung tissue after RSV infection, and whether they are involved in the pathogenesis of RSV infection of airway inflammation by dynamic observing the pathological changes of lung tissue, collagen deposition and expression of IL-17 and TGF-β1 in mice infected with RSV.Methods: This research enrolled 48 female BALB/c mice, which were randomly divided into control group and RSV infected group. The experimental group were dripped with 100μl 106 PFU RSV through nasal cavity, and the control group were dripped with 100μl NS. Then put mice to death and draw the left lung from the mice immediately on the 4th day, the 8th days, the 14 th days and the 28 th day. The lung tissue were used to observe airway pathological changes by HE staining method, to calculate the percentage of positive area of collagen fiber by masson staining image analysis, and to detecte the expression of IL-17 and TGF-β1 in lung tissue by immunohistochemistry.Results: 1. Pathological changes of lung tissue: In the control group, the bronchiole tube wall was smooth and complete, and no inflammation performance. The bronchiole of RSV infected mice could observed that infiltration of inflammatory cells was obvious, lymph cell mainly, inflammatory exudation was observed in the lumen, alveolar wall and alveolar septum were congestion, edema, thickening, alveolar space was narrowed or disappeared, partial alveolar wall was fractured, performance as interstitial pneumonia. The most obvious inflammation was found on the 8th day, gradually reduce inflammation, until 28 th days have not fully returned to normal.2. Masson staining method to calculate the percentage of positive area of airway collagen fibers: There was not obvious blue collagen deposition in control group at different time points(P>0.05). Compared with the control group, the blue collagen deposition around the airway increased on the 4th, 8th, 14 th days in the infected group, the difference was statistically significant(P<0.05). The time points of infection group were compared and a small amount of collagen deposition was found on the 4th day, 8th day more than 4th day, reaching the peak on the 14 th day. No obvious collagen deposition was found on the 28 th day. The difference was statistically significant in each time points(P<0.05).3. IL-17 expression in lung tissue: IL-17 immunohistochemical positive reaction was that brown granules could be found in bronchial epithelial cell cytoplasm, the deeper the color of the particles, the stronger the positive expression. In control group, IL-17 showed weak positive, and there was no significant difference in each time point(P>0.05). The positive expression of IL-17 in RSV infection group was on the 4th days and 8th days. Compared with the control group, the difference was statistically significant(P<0.05).The 14 th day and 28 th day were weakly positive, and there was no significant difference comparing with the control group(P>0.05). Comparison of each time point in RSV infection group, IL-17 expression was increased on the 4th day, lasting until 8th day, there was no obvious difference between the two time points(P>0.05), IL-17 expression of 14 th day was reduced, and the difference comparing with the 8th day was statistically significant(P<0.05).4. TGF-β1 expression in lung tissue: Immunohistochemical positive reaction of TGF-β1 showed dark brown granules in the cytoplasm of bronchial epithelial cells, prompting positive expression was stronger. In control group, the expression of TGF-β1 in lung tissue was weak positive, and there was no significant difference in each time point(P>0.05). The positive expression of TGF-β1 in RSV infection group was on the 4th days, 8th days and 14 th days. Compared with the control group, the difference was statistically significant(P<0.05). The 28 th day were weakly positive, and there was no significant difference comparing with the control group(P>0.05). Comparison of each time point in RSV infection group, TGF-β1 expression was increased on the 4th day, reaching the peak on the 8th day, and reduced gradually on the 14 th. The difference was statistically significant at each time point in the group(P<0.05).Conclusion: 1. IL-17 is involved in the airway inflammation of RSV infection.2. TGF-β1 is involved in the airway inflammation and collagen deposition of RSV infection. |
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