Effects Of PDTC On Apoptosis Factor Expression Of LPS-induced Mouse ARDS Lung Tissue

Objective: The mouse model of ARDS was induced by lipopolysaccharide(LPS)and PDTC pretreatment was given simultaneously.The expression changes of apoptosis factors,like Bcl-2,Bax and Caspase-3 in the lung tissue were detected in both groups in the same period.Our study aims to explore the possible effect of PDTC on apoptosis of ARDS cells for provide a new way for prevention and treatment of ARDS.Methods: The experimental mice were randomly divided into control group,model group and intervention group.LPS 20mg/kg was intraperitoneally injected to duplicate mouse animal models with ARDS.30 min before injection of LPS,PDTC 120mg/kg was intraperitoneally injected in intervention group,and samples were collected 4 h,8 h and 12 h after injection of LPS.Normal saline(NS)20ml/kg was intraperitoneally injected in control group.Real-time polymerase reaction(RT-PCR)was used to detect the levels of Bcl-2,Bax and caspase-3 in lung tissues in each group.Fluorescence enzyme immunosorbent assay was applied to detect the level of caspase-3 protease in lung tissues in each group.The W/D ratio of lung tissues in each group was detected.Arterial blood-gas analysis indexes were detected and oxygenation indexes(OI)was calculated in each group.The lung tissues in each group received paraffin section and hematein eosin(HE)staining to observe their pathological changes.Results: 1.General condition: Mice in control group showed smooth respiration,normal diet and free activity,while those in model group exhibited polypnea,reduced amount of diet and decrease of activity after injection of LPS,and those in intervention group had relatively smooth respiration,and insignificant decrease of diet amount and activity.The symptoms were in a deteriorating tendency along with study time in model group and intervention group.2.OI in each group: Arterial partial pressure of oxygen(Pa O2)/ fraction of inspiration O2(Fi O2)was evidently lower in model group than that in control group at the three time phases,and there were significant differences(P <0.05).The ratio in intervention group was between that in control group and model group.Pa O2/Fi O2 ratio showed a decreasing tendency along with time in model group and intervention group,and there was significantdifference(P <0.05).3.Appearance and HE staining of samples of lung tissues in each group: In control group,the lung tissues in mice were pink according to visible observation,and HE staining showed integrated structure of alveolar walls,without intra-cavity effusion and inflammatory cell infiltration in interstitial tissues.In model group,the color of lung tissues was deepened significantly into dark red,with size larger than that in control group,and there were hemorrhagic spots on the surface.Meanwhile,HE staining revealed obvious different-degree rupture or damage of alveolar walls,and infiltration of large amount of inflammatory cells(such as neutrophils and mononuclear macrophages)in alveolar cavity and alveolar mesenchyme.In intervention group,the lung volume was similar with control group,but exhibited deep red in color,with small amount of hemorrhagic spots on surface.In addition,the HE staining suggested obviously relieved damage of alveolar walls than model group,and notably reduced amount of inflammatory cells in alveolar cavity and alveolar mesenchyme.The symptoms were in deteriorating tendency along with study time in model group and intervention group.4.W/D ratio of lung tissues in each group: W/D ratio increased markedly in lung tissues in model group than that in control group(P <0.05),while the ratio in intervention group was between that in control group and model group.The ratio was in an increasing tendency along with time in model group and intervention group,and there was significant difference(P <0.05).5.The expression levels of Bcl-2,Bax and caspase-3 in lung tissues in each group: Bcl-2 expression in lung tissues increased prominently in lung tissues in model group and intervention group than that in control group,which increased more significantly in intervention group than that in model group.Bcl-2 expression was in an increasing tendency along with time in model group and intervention group,and there was significant difference(P <0.05).Bax and caspase-3 expressions in lung tissues increased evidently in model group than that in control group,and the increase in intervention group was between control group and model group.Bax and caspase-3 expressions were in an increasing tendency along with time in model group and intervention group,and there were significant differences(P <0.05).6.Caspase-3 protease level in lung tissues in each group: caspase-3 protease level in lung tissues increased notably in model group than that in control group,and the level in intervention group was between control group and model group.However,caspase-3protease level was in a decreasing tendency along with time in model group and intervention group,and there was significant difference(P <0.05).Conclusion: 1.The expressions of Bcl-2,Bax and Caspase-3 are increased in the lung tissues of LPS-induced ARDS mouse model,indicating that the above factors are involved in the development of ARDS.2.PDTC pretreatment could attenuate the lung injury induced by LPS in ARDS mice,and the underlying mechanism is closely related not only to upregulation of apoptosis inhibitory factor Bcl-2 but also to down-regulation of the pro-apoptotic factors Bax and Caspase-3.