Effects Of EPO On Serum Levels Of HMGB1 And Bcl-2 In Rats With Acute Lung Injury Induced By Sepsis

Objective: To investigate whether erythropoietin(EPO)has protective effect on acute lung injury induced by sepsis by researching the pathological variation of lung tissue and the variation of HMGB1 and Bcl-2 levels in serum with EPO intervention through the establishment of the rats model of acute lung injury induced by sepsis.Methods: Totals of 24 normal healthy Sprague Dawley(SD)male rats weighing180~200 g were randomly divided: control group(Group S),acute lung injury(ALI)group(Group A)and EPO treatment group(Group E).A rat model of ALI induced by LPS second-hit stimulus was established.At six hours after bilateral femoral fracture in rats,sublingual intravenous injection of 5 mg/kg of LPS was given as a second–hit stimulus to complete the modeling.Rats in the EPO treatment group were intravenously injected with1,000 IU/kg of recombinant human erythropoietin(rh EPO)immediately after the LPS second-hit,and rats in the ALI group and control group were intravenously injected with the same volume of normal saline.After eight hours,pulmonary tissues and arterial blood were collected.Blood gas analysis was performed to detect Pa O2,Pa CO2,HCO3-and p H levels,and determine the lung wet-to-dry(W/D)weight ratio of the left pulmonary lower lobe.Serum HMGB1 and Bcl-2 content were detected by ELISA assay,the upper lobe of the right lung was fixed in 4% paraformaldehyde,and pathological examination was performed by HE staining after 24 hours.All data were statistically analyzed using SPSS17.0 software.Results:(1)Lung tissue pathological results: The control group had complete structures in the pulmonary alveoli,without inflammatory cell infiltration;The ALI group had completely damaged structures in the pulmonary alveoli,and inflammatory cell infiltration and varying amounts of erythrocytic exudation were observed in the alveoli;The EPO treatment group had partially damaged structures in the pulmonary alveoli,focal foam cell aggregation and a small amount of erythrocytic exudation could be observed in some alveoli.Compared with ALI group,the other two groups presented with varying degrees of injuries and inflammatory pathological changes.However,ALI group presented with more serious damages in alveolous structures,as well as more inflammatory cells and erythrocytic exudation.(2)Lung tissue Wet/dry ratio results: The lung tissue W/D ratio of the ALI group and EPO treatment group was(6.05 ± 0.64)and(5.33 ± 0.57),significantly higher than control group(4.48 ± 0.25)(P<0.01),meanwhile that of ALI group was higher than EPO treatment group(P<0.05).(3)Blood gas analysis results: Pa O2 of the ALI group and EPO treatment group was(58.4 ± 1.3)mm Hg and(67.0 ± 3.5)mm Hg,significantly lower than control group(94.8 ± 2.8)mm Hg(P<0.01),meanwhile that of ALI group was significantly lower than EPO treatment group(P<0.01);HCO3-and p H value of control group were respectively(27.4 ± 1.1)mmol/L and(7.38 ± 0.41),HCO3-and p H value of ALI group were respectively(22.4 ± 3.1)mmol/L and(7.25 ± 0.66),HCO3-and p H value of EPO treatment group were respectively(24.8 ± 1.7)mmol/L and(7.32 ± 0.42),HCO3-and p H value were lower in the ALI group than control group(P<0.01)and EPO treatment(P<0.05),meanwhile that of EPO treatment group were lower than control group(P<0.05);Pa CO2 of the control group,ALI group and EPO treatment group was respectively(41.5 ±2.7)mm Hg,(40.2±5.8)mm Hg and(43.3 ± 4.2)mm Hg,and the inter-group comparison of Pa CO2 yielded no statistically significant difference(P>0.05).(4)Serum HMGB1 and Bcl-2 levels results: HMGB1 levels in serum of the ALI group and EPO treatment group was(1390.83 ± 178.99)pg/ml and(1208.08 ± 116.45)pg/ml,significantly higher than control group(359.25 ± 92.89)pg/ml(P<0.01),meanwhile that of ALI group was higher than EPO treatment group(P<0.05).Bcl-2 levels in serum of the ALI group and EPO treatment group was(1.71 ± 0.55)ng/ml and(2.53 ± 0.38)ng/ml,significantly lower than control group(4.31 ± 0.86)ng/ml(P<0.01),meanwhile that of ALI group was lower than EPO treatment group(P<0.05).Conclusion: EPO reducing the inflammatory response of lung tissue of rats with acute lung injury and down-regulating the level of HMGB1 and up-regulating the level of Bcl-2in serum.EPO has protective effect on acute lung injury induced by sepsis.