The Protective Effect Of Icaritin On LPS Induced Acute Lung Injury(ALI) In Mice Model

Objective: Acute lung injury/acute respiratory distress syndrome a common serious disease in clinic.In recent years,the pathophysiology of ALI has been gradually explored,but there is still a lack of effective drugs for treatment.Inflammation plays a central role in the occurrence of ALI,so anti-inflammatory is the key for ALI treatment.Icaritin has been proved to have widely anti-inflammatory effects.In this study,ALI mouse model induced by lipopolysaccharide was established,different doses of Icaritin were used to intervene to investigate its protective effect on ALI.We hope to provide new,cost-effective and potential drugs for the treatment of ALI.Methods : Sixty C57BL/6J males were randomly divided into control group,model group,Icaritin low-dose(4mg/kg)group,Icaritin high-dose group(8mg/kg)and dexamethasone(5mg/kg)group,12 mice in each group.An ALI mouse model was established by instilling LPS(5mg/kg)into the trachea.First,the prepared Icaritin solution(DMSO)was diluted with saline and injected into the mice intraperitoneally with different dose.The mice in the control group were injected with the same amount of normal saline;the mice in the dexamethasone group were injected with the same amount of dexamethasone.After 1 hour,the mice were intraperitoneally anesthetized with 7% chloral hydrate,LPS(5mg/kg)was instilled into the trachea,and 50μl normal saline was instilled into the trachea of the control group.Mice in each group were anesthesia 12 h after LPS treatment,blood was collected from the eyeballs,and then the mice were sacrificed by cervical dislocation.the thoracic cavity was fully exposed,the alveolar lavage fluid was collected,and the total number of white blood cells in the alveolar lavage fluid of each group was compared by cytometry.The left lung tissue was fixed with 4% paraformaldehyde and then H&E staining was performed to evaluate the damage degree of the mouse lung tissue.The right lung tissue of 6 mice was randomly selected from each group to determine the wet/dry weight(W/D)ratio of lung tissue.The activity of myeloperoxidase(MPO)in the upper lobe of the right lung was determined by colorimetry.The MDA content in middle lobe of right lung was detected by TBA method.Results: In this study,ICT was found to significantly reduce LPS-induced lung injury,which could be evaluated by lung histopathology,histological score,W/D weight ratio,lung tissue MPO activity,and the lung tissue MDA content.(1)Compared with the control group,the total number of white blood cells in BALF in the LPS group increased(P<0.05);compared with the model group,the total number of white blood cells in BALF in the ICT groups decreased(P<0.05),and ICT(8mg/kg)group was lower than ICT(4mg/kg)group(P<0.05).(2)Compared with the control group,lung tissue in the LPS group showed obvious pulmonary edema,a large number of inflammatory cell infiltration and alveolar wall thickening.ICT alleviates pulmonary edema,reduces inflammatory cell infiltration,and inhibits alveolar wall thickening.Meanwhile,compared with the control group,The pathological score of LPS group increased(P<0.05);compared with the LPS group,the pathological score of the ICT low and ICT high groups were lower(P<0.05),and ICT(8mg/kg)group was lower than ICT(4mg/kg)group(P<0.05).(3)Compared with the control group,the wet/dry weight ratio of lung tissue in LPS group increased(P<0.05);compared with LPS group,the wet/dry weight ratio of lung tissue in ICT groups decreased(P<0.05),and ICT(8mg/kg)group was lower than ICT(4mg/kg)group(P<0.05).(4)Compared with the control group,the lung tissue MPO activity level of the LPS group enhanced(P<0.05);compared with the LPS group,the lung tissue MPO activity level of the ICT low and ICT high groups reduced(P<0.05),and ICT(8mg/kg)group was lower than ICT(4mg/kg)group(P<0.05).(5)Compared with the control group,the lung tissue MDA content of the LPS group increased(P<0.05);compared with the LPS group,the lung tissue MDA content of the ICT groups decreased(P<0.05),and ICT(8mg/kg)group was lower than ICT(4mg/kg)group(P<0.05).Conclusions: Our findings showed that ICT could decrease in the total number of white blood cells,mitigate the pathological damage of lung tissue,reduce the ratio of lung wet/dry weight,and also significantly inhibit MPO activity and reduce MDA content.Our research proves that ICT has a protective effect on LPS-induced ALI by inhibiting inflammation and oxidative stress,moreover,the therapeutic effect was dose-dependent.