Lung Protective Effect And Its Mechanism Of Recombinant Human Keratinocyte Growth Factor-2 On Rabbits With Smoke Inhalation Injury

Objective: To study the protective effect and its mechanism of recombinant human keratinocyte growth factor-2 on lung of rabbits with smoke inhalation.Methods: 120 New Zealand rabbits injured by smoke inhalation,were randomly divided into five groups,24 rats in each group: 0mg/kg group(control group): injury rabbits without treatment;group PBS: 4 hours after injury,inhalation of phosphate buffered saline(PBS)5ml,once daily for 7 days;1mg/kg group: 4 hours after injury,inhalation of rhKGF-2(1mg/Kg,dissolved in 5ml PBS),once daily,for 7 consecutive days;group 2mg/kg: 4 hours after injury,inhalation of rhKGF-2(2mg/Kg,dissolved in 5ml PBS),once daily,for 7 consecutive days;group 5mg/kg: 4 hours of injury after inhalation of rhKGF-2(5mg/Kg,dissolved in 5ml PBS),once daily for 7 consecutive days;After treatment of 1d,3d,5d,7d,an animal was randomly selected from each group,the arterial blood was drawn for blood gas analysis,then animals were sacrificed,bronchoalveolar lavage fluid were collected to measure IL-6,IL-8,IL-10,and MCP-1 by Elisa.(SP-A),vascular endothelial growth factor(VEGF)and Bcl-2 protein were detected by Western blot.The trachea and lung tissue were taken out for pathological examination and NF-κB,lung surfactant protein A(SP-A),vascular endothelial growth factor(VEGF),phosphatidylinositol 3 kinase(P13K),protein kinase B(Akt),Bcl-2 protein were detected by Western blot.Real-time PCR was used to detect the expression of the corresponding proteins and TUNEL was used to detect apoptosis of lung tissue.Results:(1)1 day after trentment in each group,PaO2 was at a low level,with the extension of time,PaO2 had a rising trend,but no significant difference between each time point(P>0.05).Overall analysis showed that each dose group can significantly improve the oxygen partial pressure(P<0.01),but the PH.PaCO2,HCO3 has no significant effect(P>0.05).(2)According to the pathological,1 day after injured,tracheal mucosa epithelial cells swell and fall off,lots of inflammatory cells infiltrated at submucosal;Pulmonary edema,hemorrhage,a lot of inflammatory exudate found in alveolar,a large number of inflammatory cells can also be seen in the pulmonary interstitial and alveolar.(3)Overall analysis,after atomization inhalation of rhKGF-2,alveolar lavage fluid of IL-6,IL-8 drop,with IL – 10 rising slightly,while 5mg group is most significant,the treatment group had little effects on MCP-1(P>0.05).(4)after atomization inhalation of rhKGF-2,NF-κB protein level and gene expression are falling,and 5mg group is preferred.(5)After inhalation of rhKGF-2,the SP-A and VEGF protein in lung tissue gradually increased,particularly in the 5mg group,but the Akt and PI3 K protein were not significantly changed during treatment(P>0.05).(6)After inhalation of rhKGF-2,RNA expression of SP-A,VEGF,PI3 K,Akt were increased obviously,significantly in group 5mg;the RNA expression of SP-A,VEGF,PI3 K is associated with dose,but the RNA expression of Akt has no obvious relationship with dose.(7)After inhalation of rhKGF-2,immunohistochemistry showed that the expression of Bcl-2 was significant;and cell apoptosis of lung reduced;the contents of Bcl-2 in lung tissue of animals of 2mg group,5mg group increased,but no significant difference was found between 1mg group animal at difference time points(P>0.05);expression of Bcl-2 RNA in the lung tissue also increased,but no significant differences between the groups.Conclusion: rhKGF-2 can improve rabbits with smoke inhalation injury on oxygenation,alleviate lung inflammatory reaction,reduce apoptosis,and promote airway repair.High dose group performed better.The mechanism may be related to the down-regulation of NF-κB,up-regulation of expression of Bcl-2 and activation of PI3K/Akt pathway.