1. ¹Dumont–UCLA Transplant Center and David Geffen School of Medicine, University of California at Los Angeles, Box 957054, Los Angeles, CA 90095, USA
2. ²Cedars–Sinai Medical Center, Gene Therapeutics Research Institute, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA
3. ³Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, Box 957054, Los Angeles, CA 90095, USA

Correspondence: Jerzy W. Kupiec-Weglinski, Fax: (310) 267-2358. E-mail: jkupiec@mednet.ucla.edu

Received 29 October 2003; Accepted 29 October 2003.

Abstract

Liver injury induced by ischemia/reperfusion (I/R) is the prime factor in delayed or loss graft function following transplantation. CD4⁺ T lymphocytes are key cellular mediators of antigen-independent inflammatory response triggered by I/R. We attempted to modulate rat liver I/R injury by targeted gene therapy with CD40Ig, which blocks the CD40–CD154 costimulation pathway. One hundred percent of Ad-CD40Ig-pretreated orthotopic liver transplants (OLTs) subjected to 24 h of cold (4°C) ischemia survived >14 days (vs 50% in untreated/Ad--gal groups). Ad-CD40Ig treatment decreased sGOT levels and depressed neutrophil infiltration, compared with controls. These functional data correlated with histological Suzuki's grading of hepatic injury, which in untreated/Ad--gal groups showed severe necrosis (>60%) and moderate to severe sinusoidal congestion; the Ad-CD40Ig-pretreated group revealed minimal sinusoidal congestion/necrosis. Unlike in controls, OLT expression of mRNA coding for IL-2/IFN- remained depressed, whereas that of IL-4/IL-13 reciprocally increased in the Ad-CD40Ig group. Ad-CD40Ig reduced frequency of TUNEL⁺ cells and proapoptotic Caspase-3, but enhanced antioxidant HO-1 and antiapoptotic Bcl-2/Bcl-xl expression. Thus, prolonged blockade of CD40–CD154 by CD40Ig exerts potent cytoprotection against hepatic I/R injury. These results provide the rationale for a novel gene therapy approach to maximize the organ donor pool through the safer use of liver transplants exposed to prolonged cold ischemia.