| Objective:To investigate the expression and role of autophagy related protein Beclin-1,P62 and microtubule-associated protein 1 light chain 3B(LC3B)in the lungs of Streptococcus pneumoniae infected mouse.Methods:Fifty adult SPF Balb/c mice(female,6~8week,16~20g)were infected with 20ul Streptococcus pneumoniae D39 by nose dropping at the concentration of 1.5×10~9 CFU/ml.The BALF and lung tissues of experimental mice were collected at the point of 0h,6h,12h,24h and 48h after infection.Wright-Giemsa staining was used to cells counting in the BALF.Hematoxyin-eosin(HE)staining was use to observe the morphological changes in the lung.Western blot was adopted to detect the expression of Beclin-1,P62 and LC3B protein in the lung.Immunofluorescence assay was employed to investigate the distribution of LC3B in the lung.Results:A large number of inflammatory cells had infiltrated in the lung tissue around 12h to 24h after dripping Streptococcus pneumoniae.The BALF total cells and neutrophils in BALF of mice increased dramatically at 6h(1.280±0.506、6.272±1.312,P=0.000;0.000±0.000、3.456±1.308,P=0.000)since inoculation,and reached a peak at 12h(1.280±0.506、19.456±0.997,P=0.000;0.000±0.000、15.040±1.012,P=0.000),then declined to normal level at 48h(1.280±0.506、3.520±0.933,P=0.005;0.000±0.000、0.128±0.175,P=0.835).Western blot results showed that the expression of Beclin-1 appeared at 6h(0.626±0.078、0.921±0.093,P=0.002),and were significantly higher at 48h(0.626±0.078、1.884±0.158,P=0.000).Meanwhile the expression of P62 decreased at 6h(2.915±0.094、2.275±0.269,P=0.000),and were significantly lower at 48h(2.915±0.094、1.178±0.142,P=0.000).The expression of LC3B increased at 12h(0.747±0.197、1.429±0.318,P=0.006),and peaked at 24 h(0.747±0.197、2.002±0.451,P=0.000),then dropped to a lower level at 48h(0.747±0.197、1.563±0.501,P=0.002).Immunoflurescent results showed that the expression of LC3B increased at 12h and 24h.Conclusion:Autophagy was activated and played an important role in the immune response during Streptococcus pneumoniae infection. |
