The Machanism Of Rac1/AKT/NF-?B Signaling Pathway In Rats Ventilation Induced Lung Injury

OBJECTIVE:To investigate the machanism of Ras related C3 botulinum toxin substrate 1/ Protein Kinase B / nuclear factor-?B(Rac1/AKT/NF-?B)signaling pathway in rats ventilator induced lung injury(VILI).METHODS : Thirty Sprague-Dawley(SD)rats were randomly divided into spontaneous respiratory group,high tidal volume(VT)group(high VT,VT was40mL/Kg group)and NSC23766 group(rats were given 200?L NSC23766 at1.5mg/kg by slow instillation through tracheal catheter,and then ventilated with a high tidal volume of 40 mL/kg).Heart bleed to death after mechanically ventilation for 4 hours,Pulmonary alveolar lavage fluid(BALF),serum and lung tissue were collected for examination.The lung wet to dry weight ratio(W/D)was calculated;Microscope was used to observe the changes of pulmonary tissue in pathology;Determination of total protein content in BALF by using BCA method;Enzyme linked immunosorbent assay(ELISA)was performed to determine the concentration of interleukins(IL-1?,IL-6)in serum and brconchoalveolar lavage fluid(BALF)and Rac1 in BALF;The mRNA expressions of NF-?B,Rac1 were determined by real-time fluorescent quantitation reverse transcription-polymerase chain reaction(RT-qPCR),and protein expressions of AKT,phosphorylation of Protein Kinase B(p-AKT),NF-?B were determined by Western Blot.RESULTS:No obvious pathological changes in lungs were found in spontaneous respiratory group.But pathological changes were observedin high VT group,including pulmonaryalveoli fusion,alveoli septum thickening,inflammatory cells infiltration.In NSC23766 group,there was slight edema and infiltration of inflammatory cells.Compared with the spontaneous respiratory group,the W/D ratio in the high VT group was significantly higher,the difference was statistically significant(P < 0.01),and the total protein in the high VT group was also significantly increased(P < 0.05),and there was no statistical difference between the W/D ratio and the total protein in the NSC23766 group(P > 0.05).Compared with the spontaneous respiratory group,the Rac1 content in the BALF of the high VT group and the NSC23766 group was significantly higher,the difference was statistically significant(P < 0.01).The levels of IL-1 beta and IL-6 in the serum and BALF of the high VT group were significantly higher,the difference was statistically significant(P < 0.01).The serum and BALF in the NSC23766 group were also significantly higher.The difference was statistically significant(P < 0.05).Compared with the high VT group,the content of IL-1 beta and IL-6 in serum and BALF in NSC23766 group was significantly decreased,and the difference was statistically significant(P < 0.05).Compared with the spontaneous respiratory group,the mRNA expression of NF-kappa B in the lung tissue of the high VT group and the NSC23766 group was significantly up,and the difference was statistically significant(P < 0.05),and the mRNA expression of Rac1 in the high VT group and NSC23766 group was obviously up,and the difference was statistically significant(P < 0.01).AKT protein expression: compared with the spontaneous respiratory group,the expression of AKT protein in the high VT group and NSC23766 group increased significantly,the difference was statisticallysignificant(P < 0.05).The expression of p-AKT and NF-kappa B protein:compared with the spontaneous respiratory group,the expression of p-AKT and NF-kappa B protein in the high VT group increased significantly(P < 0.01).There was no significant difference in the expression of p-AKT and NF-kappa B protein in the NSC23766 group(> 0.05).CONCLUSION:Rac1/AKT/NF-kappa B pathway is involved in the occurrence and development of VILI.NSC23766 can effectively inhibit inflammatory signal transduction,thereby improving the progress of VILI.