Adenovirus-mediated gene transfer in the transplant setting: Early events after orthotopic transplantation of liver allografts expressing TGF- β1

We hypothesized that adenovirus mediated gene transfer of TGF-β1 into liver grafts would enhanced local expression of this recombinant protein and down-regulate inflammatory and alloreactive immune response. A full length DNA encoding the murine TGF-β1 was used to replaced the E1 region of adenovirus type 5 (AdmTGF-β1). Expression and protein production of biologically active murine TGF-β1 was tested in AdmTGF-β1-transduced Hep G2 cells and TGF-β-sensitive MV1 cells. In the transplant setting, the replication-defective vector was used to perfused cold preserved ACI liver allograft prior to transplantation into Lewis recipients. Control livers were similarly perfused with cold lactated Ringer's solution and were followed without immunosuppression. Animals were sacrificed at 1, 3, and 5 days after transplantation. Intragraft cytokine levels of TNFα, and IFNγ were determined using ELISA and quantitative PCR. TGF-β1 ELISA of culture supernatants from AdmTGF-β1 transduced hepatocyte cell line Hep G2 excreted TGF-β1 in quantities directly correlated with multiplicity of infection (MOI, vector:hepatic cell ratio). The biological activity of the excreted recombinant protein was confirmed by growth inhibition of MV1 TGF-β- sensitive cells. Enhanced production of TGF-β1 in transduced allografts was associated with decreased levels of TNFα and IFNγ when compared with nonimmunosuppressed controls. Adenovirus-mediated gene transfer of murine TGF-β1 into hepatic cells results in the expression of biologically active protein. Transduction of allografts with TGF-β1 down-regulates TNFα and IFNγ production early after orthotopic transplantation. Graft transduction with TGF-β1 offers a novel approach to study the effects of single immune modulator on alloreactive immune response, T cell function, and cytokine cascade.