Protective Effect And Mechanism Of Baicalin Liposome On Lipopolysaccharide Induced Acute Lung Injury In Mice

The development of new drug formulations and new technologies have greatly improved the properties of drugs and made them play better effects on the prevention and treatment of diseases.Acute lung injury（ALI）is a serious respiratory infectious disease caused by a variety of pathogenic factors,which has been researched in many years.While there is still lack of effective methods to reduce the high mortality.Therefore,it is an urgent need to develop a new effective treatment to intervene in this disease.Baicalin（BA）is the main effective component of Scutellaria baicalensis.Studies have shown that BA has protective effect on LPS induced ALI,while the specific mechanisms are not complete.At the same time,the low solubility of BA greatly limits the development and application.In this study,we evaluated the pharmacokinetics and tissues distribution of baicalin liposomes（BA-LP）in mice through animal experiments,and further explored its protective effect and mechanism on LPS induced ALI of mice,so as to provide a new strategy for the improvement of ALI.It also provides a reference for the development and utilization of new dosage forms of active ingredients in traditional Chinese medicine.Objective:1 To research the pharmacokinetics and tissues distribution of BA-LP in normal mice after intravenous injection2 To research the protective effect of BA-LP on LPS induced ALI in mice after intravenous injection3 To explore the protective mechanism of BA-LP on LPS induced ALI in mice after intravenous injectionMethod:1 The content of BA in plasma and tissues samples were analyzed by HPLC.The pharmacokinetics and tissue targeting of BA-LP in normal mice were researched by measuring the blood concentration and the distribution of heart,liver,spleen,lung and kidney after intravenous injection of BA monomer and BA-LP.2 The KM mice were divided into control group,LPS model group,BA monomer group（100 mg/Kg）,BA-LP low dose group（50 mg/Kg）,medium（100 mg/Kg）and high dose group（200 mg/Kg）.Each group was given the corresponding test substance intravenously for 3 days in advance.Except for the control group,all animals were intratracheal instillation of LPS to induce ALI model.After 12 hours,the mice were anesthetized and euthanized in order to get the bronchoalveolar lavage fluid（BALF）and lung tissues.The wet to dry ratio（W/D）of lung tissues were measured.The histopathology of lung tissues was observed after Hematoxylin-eosin（HE）staining.The total protein contents in BALF were determined by BCA protein analysis kit.3 The levels of TNF-αand IL-1βin BALF were detected by ELISA kit,and the key protein expression levels of TLR4,JNK,ERK and NF-κB in lung tissues collected from"2"were determined by Western blot.Result:1 After intravenous injection of BA-LP and BA monomer,the results showed that AUC_0-tof BA-LP was about 6.46 times of that of BA monomer solution（P<0.05）,MRT_0-twas higher than that of BA group（P<0.001）,T_1/2of BA-LP group and BA group were 202.963±18.291 min and 127.18±10.849 min,respectively.The C_LZof BA monomer solution（0.0338±0.0004）was 6.76 times of that of BA-LP（0.005）.The distributions of BA were detected in tissues of mice.The results showed that the distributions of BA in heart,liver,spleen and lung increased significantly after injection of BA-LP,while the content of BA in kidney decreased relatively compared with BA group.And BA-LP has a certain targeting effect on liver,heart,spleen and lung.2 Pharmacodynamic studies showed that BA-LP were better than that of BA monomer group in reducing W/D ratio,reducing lung injury score and total protein in BALF.In addition,the therapeutic effect of BA-LP was dose-dependent within a certain range.3 The results of ELISA showed that BA-LP and BA monomer solution could reduce the levels of pro-inflammatory factors（TNF-α,IL-1β）in BALF.Western blot analysis showed that the anti-inflammatory effect of BA may be related to the inhibition of TLR4/JNK/ERK/NF-κB p65 signaling pathway.Conclusion:In vivo pharmacokinetics and tissues distribution showed that the BA-LP not only made the drug sustained-release,prolonged the retention time of BA in mice,but also increased the concentration of BA in lung.Through ALI model,it was confirmed that there was inflammatory reaction in ALI,and BA had a therapeutic effect on inflammatory reaction.The mechanism may be related to TLR4/JNK/ERK/NF-κB p65 signaling pathway,suggesting that BA-LP can be used for the treatment of ALI.