Evaluation Of Activity Of Carboxylesterase In Immunological Liver Injury Rats

Immunological liver injury is mediated by the activation of the innate and/or specificimmune response. Bacillus Calmette-Guerin （BCG） and a subsequent challenge withlipopolysaccharide （LPS） induce acute hepatic injury, mimicking fulminant hepatitisinduced by virus and endotoxin. Liver injury may induce dysregulations of drugmetabolizing enzymes that may change the metabolism, pharmacokinetics and thus thetherapeutic effects of drugs.The animal model of immunological liver injury was established by intraperitonealinjection of lipopolysaccharide （LPS） plus Bacille-Calmette-Guerin （BCG） in SD rats. Ratswere randomly divided into three groups: LPS with low dose, LPS with high dose andnormal control group. After injection of BCG （8mg）, the three groups were given LPS5mg·kg^-1,10mg·kg^-1and saline, respectively. Activities of serum alanine aminotransferase（ALT） and aspartate aminotransferase （AST） were measured by biochemical methods.Hepatic tissues sections were stained with haematoxylin and eosin and examianed under alight microscope. The results indicated that the activities of serum ALT and AST inimmunological liver injury rats were increased significantly （P<0.05）, compared with thenormal control group, and exhibited a dose-dependent pattern. At the mean time,histological examination demonstrated that the inflammatory cell infiltration and liver cellnecrosis existed in liver cells, and the injury degree was aggravated by the high dose ofLPS.After successful model of immunological liver injury, the activity of CES was studiedand imidapril and irinotecan （CPT-11） were selected as substrates of CES1and CES2,respectively. Then we developed methos of LC-MS/MS and HPLC for the determination of imidaprilat and SN-38, the active metabolite of imidapril and CPT-11, respectively, inplasma. Both the methods were sensitive, specific and were suitable for metabolism studyof imidapril and CPT-11. Nextly, the pharmacokinetics of imidapril and CPT-11werestudied in rats with immunological liver injury. The rats were given with imidapril(10mg·kg^-1) by intragastric administration and CPT-11(20mg·kg^-1) by caudal vein,respectively. Compared with the normal control group, AUC0-12hof imidaprilat wasdecreased from1759.93±386.57mg·h-1·L-1to620.93±197.16mg·h-1·L-1，and Cmaxwasdecreased from234.66±68.85mg·L-1to113.1±19.69mg·L-1（P<0.05）. AUC0-24hof SN-38was decreased from646.1±110.9ng·h·mL-1to275.9±52.5ng·h·mL-1, and Cmaxwasdecreased from145.6±15.9ng·mL-1to57.8±9.5ng·mL-1（P<0.05）. The resultsdemonstrated the hydrolysis of imidapril and CPT-11was inhibited significantly.At lat, real-time polymerase chain reaction （RT-PCR） and Western Blot were followedto further evaluate the levels of mRNA and protein of CES1and CES2in immunologicalliver injury rats. The results of RT-PCR revealed the expression of CES1mRNA and thetwo CES2isozymes （AB010635and AY034877） were reduced remarkly （P<0.05）.Furthermore, the protein levels of CES1and CES2were decreased significantly （P<0.05）.It is suggested that expression and activities of CES1and CES2were down-regulated underimmunological liver injury, and it has provided profound reference for dose adjustment ofdrug metabolized by CES.