The Effects Of Methylprednisolone On The Expression Of Liver Bile Acid Transporters Ntcp And Bsep In Liver Injury Induced By Endotoxion

Sepsis is a main cause of acute liver injury(ALI),characterised by high bilirubin,elevated serum bile acid levels.The mechanism of septic ALI and how to prevent septic ALI become research hotspots in critical care medicine.The first part of this study aims to explore the effects of lipopolysaccharide(LPS)on the expression of sodium taurocholate cotransporting polypeptide(Ntcp)and bile salt export pump(Bsep)by intraperitoneal injection of different doses of LPS.The second part of this study aims to investigate the role and mechanism of methylprednisolone(MP)in the mouse model of LPS-induced ALI.Part 1: The m RNA expression of Ntcp and Bsep in livers of lipopolysaccharide-induced liver injury miceObjective To investigate the effects of LPS on the m RNA expression of Ntcp and Bsep,as well as the liver function parameters in the serum including total bilirubin(TBIL),total bile acids(TBA),alanine aminotransferase(ALT),aspartate aminotransferase(AST)in mice.Methods One hundred and twenty-eight C57BL/6J mice were intraperitoneally injected with different doses of LPS 5,10,20,or 40 mg/kg,respectively(n=8).Serum TBIL,TBA,ALT,AST levels were measured at 24 h,48 h and 72 h after LPS injection in each group.The m RNA expression levels of Ntcp and Bsep were analyzed by reverse transcription quantitative polymerase chain reaction(RT-q PCR).The liver histological sections were stained with haematoxylin and eosin(HE).Results The Ntcp and Bsep m RNA levels were significantly lower in livers of LPStreated mice within 24 h in a dose-dependent manner.In addition,serum levels of TBIL,TBA,ALT,AST were significantly increased in mice of LPS–treated group compared with control group,particularly within 24 h after LPS treatment.Furthermore,histological changes in liver depend on dose and time course of LPS treatment.Cytoplasm rarefaction and inflammatory cells infiltration were detected at 24 h after treatment with 5 or 10 mg/kg LPS.Acidophilic and vacuolar degeneration,neutrophils infiltration in the hepatic sinusoid and portal area,ductal proliferation were observed in livers of mice at 48 h,72 h after treatment with 5 or 10 mg/kg LPS.In the 20 or 40 mg/kg LPS treatment groups,disorder of focal necrosis,inflammatory cellsinfiltration,ductal proliferation and expansion were observed in livers of mice at 24 h,48 h and 72 h after LPS treatment.Conclusions LPS treatment decreases the m RNA expression of Ntcp and Bsep in a dose dependent manner in mice,which might associated with the mechanism of liver injury induced by endotoxin.Part 2:Glucocorticoids alleviates lipopolysaccharide-induced acute liver injury associated with promoting the expression of NTCP and BSEPObjective Methylprednisolone(MP)is a glucocorticoid steroid administered usually in severe sepsis and septic shock.However,the role and molecular mechanisms underlying hepatoprotective effect of MP in sepsis-induced ALI is largely unknown.The aim of the present study was to investigate the effect of MP in a mouse model of LPS-induced ALI.Methods A total of 96 male C57BL/6J mice were randomly divided into four groups(n=24 per group)according to the treatment including vehicle(control group)or LPS only(LPS group)or with 2 mg/kg MP(LPS+ 2 mg/kg MP group)or LPS with 20 mg/kg MP(LPS+ 20 mg/kg MP group)three times at 1 h,24 h,48 h after LPS treatment.The livers and serum were collected for further analysis.Serum levels of t TBIL,TBA,ALT,AST were measured at 24 h,48 h or 72 h after LPS administration.Histological examinations were performed on liver,and liver sections were stained with hematoxylin and eosin(HE).Furthermore,the expression of Interleukin-6(Il-6),Tumour Necrosis Factor-α(Tnf-α),sodium-taurocholate co-transporting polypeptide(NTCP)and bile salt export pump(BSEP)in liver were analyzed by reverse transcription quantitative polymerase chain reaction(RT-q PCR)and western blot.Results MP therapy protects mice against LPS-induced ALI at the dose of 2 mg/kg and 20 mg/kg.The serum TBIL,TBA,ALT,AST levels were significantly decreased in LPS + 2 mg/kg MP group and LPS + 20 mg/kg MP group compared with LPS group.However,there is no significant difference between the LPS + 2 mg/kg MP and the LPS + 20 mg/kg MP.Furthermore,LPS administration suppresses the expression of NTCP and BSEP,which is significantly reversed by MP therapy.Moreover,LPS-induced higher expression of Il-6 and Tnf-α was significantly suppressed by MP administration.Conclusion MP protects mice against LPS-induced ALI and improves bile acid secretion and transportation,partially due to the upregulated expression of NTCP and BSEP.