Pitt Logo LinkContact Us

DRUG METABOLISM AND TRANSPORT DURING REJECTION OF TRANSPLANTED LIVER

Al-Mohizea, Abdullah M (2002) DRUG METABOLISM AND TRANSPORT DURING REJECTION OF TRANSPLANTED LIVER. Doctoral Dissertation, University of Pittsburgh.

[img]
Preview
PDF - Primary Text
Download (853Kb) | Preview

    Abstract

    Organ transplantation is an accepted therapy for diseases that result in chronic irreversible failure of various organs. During transplantation, the transplanted organ is subjected to two inflammatory processes, alloantigen-independent (ischemia/reperfusion injury) and alloantigen-dependent (rejection), both of which involve release of cytokines. The objectives of this dissertation were to evaluate the effect of acute rejection of liver in rats on hepatic and extra-hepatic drug metabolizing capacity for phase I and II enzymes, to evaluate the effect of chronic rejection of liver in humans on hepatic metabolizing capacity of phase I and II enzymes, to evaluate the effect of acute and chronic rejection of liver on hepatic and extra-hepatic protein and mRNA expression of P-glycoprotein and to evaluate the effect of different cytokines on the constitutive and inducible hepatic CYP3A4 activity and protein expression in human hepatocytes. Alloantigen-independent inflammation and altered blood flow caused a reduction in hepatic mRNA of different phase I and II enzymes. However, this reduction did not significantly alter protein levels of all CYP450 enzymes studied. Occurrence of rejection resulted in further reduction in mRNA, protein levels and activity of all CYP450s studied. Syngeneic and allogeneic transplantation caused reduction in the metabolic capacity of extra-hepatic tissues and increased expression of P-gp in the liver. Chronic rejection of the liver in humans selectively altered the activity and protein expression of different phase I and II enzymes and increased P-gp protein expression. In human hepatocyte cultures, IL-1â, IL-6 and TNF-á decreased the activity and protein expression of both constitutive and induced forms of CYP3A4 enzyme. Pre-exposing or co-exposing the hepatocytes to cytokines reduced the ability of rifampicin to induce CYP3A4.In conclusion, acute and chronic rejection of liver significantly altered the expression and activity of several drug metabolizing enzymes and transporters. The magnitude of these alterations was higher in acute rejection. Acute rejection also caused alterations in the metabolizing ability and transporters expression in renal and pulmonary tissues. Cytokines play a major role in modulating the activity of drug metabolizing enzymes and transporters and may contribute to the large inter-individual variation in the pharmacokinetics of drugs in transplant patients.


    Share

    Citation/Export:
    Social Networking:

    Details

    Item Type: University of Pittsburgh ETD
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairVenkataramanan, Raman
    Committee MemberBurckart, Gilbert
    Committee MemberPerel, James
    Committee MemberFrye, Reginald
    Committee MemberVollmer, Regis
    Title: DRUG METABOLISM AND TRANSPORT DURING REJECTION OF TRANSPLANTED LIVER
    Status: Unpublished
    Abstract: Organ transplantation is an accepted therapy for diseases that result in chronic irreversible failure of various organs. During transplantation, the transplanted organ is subjected to two inflammatory processes, alloantigen-independent (ischemia/reperfusion injury) and alloantigen-dependent (rejection), both of which involve release of cytokines. The objectives of this dissertation were to evaluate the effect of acute rejection of liver in rats on hepatic and extra-hepatic drug metabolizing capacity for phase I and II enzymes, to evaluate the effect of chronic rejection of liver in humans on hepatic metabolizing capacity of phase I and II enzymes, to evaluate the effect of acute and chronic rejection of liver on hepatic and extra-hepatic protein and mRNA expression of P-glycoprotein and to evaluate the effect of different cytokines on the constitutive and inducible hepatic CYP3A4 activity and protein expression in human hepatocytes. Alloantigen-independent inflammation and altered blood flow caused a reduction in hepatic mRNA of different phase I and II enzymes. However, this reduction did not significantly alter protein levels of all CYP450 enzymes studied. Occurrence of rejection resulted in further reduction in mRNA, protein levels and activity of all CYP450s studied. Syngeneic and allogeneic transplantation caused reduction in the metabolic capacity of extra-hepatic tissues and increased expression of P-gp in the liver. Chronic rejection of the liver in humans selectively altered the activity and protein expression of different phase I and II enzymes and increased P-gp protein expression. In human hepatocyte cultures, IL-1â, IL-6 and TNF-á decreased the activity and protein expression of both constitutive and induced forms of CYP3A4 enzyme. Pre-exposing or co-exposing the hepatocytes to cytokines reduced the ability of rifampicin to induce CYP3A4.In conclusion, acute and chronic rejection of liver significantly altered the expression and activity of several drug metabolizing enzymes and transporters. The magnitude of these alterations was higher in acute rejection. Acute rejection also caused alterations in the metabolizing ability and transporters expression in renal and pulmonary tissues. Cytokines play a major role in modulating the activity of drug metabolizing enzymes and transporters and may contribute to the large inter-individual variation in the pharmacokinetics of drugs in transplant patients.
    Date: 11 December 2002
    Date Type: Completion
    Defense Date: 20 November 2002
    Approval Date: 11 December 2002
    Submission Date: 06 December 2002
    Access Restriction: No restriction; The work is available for access worldwide immediately.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Doctoral Dissertation
    Refereed: Yes
    Degree: PhD - Doctor of Philosophy
    URN: etd-12062002-115904
    Uncontrolled Keywords: acute rejection; chronic rejection; cytokines; drug metabolism; hepatocytes; liver transplantation; microsomes; organ transplantation; transplantation; drug transporters; Organ rejection
    Schools and Programs: School of Pharmacy > Pharmaceutical Sciences
    Date Deposited: 10 Nov 2011 15:08
    Last Modified: 21 May 2012 12:14
    Other ID: http://etd.library.pitt.edu:80/ETD/available/etd-12062002-115904/, etd-12062002-115904

    Actions (login required)

    View Item

    Document Downloads