Adenovirus-mediated gene transfer into cold-preserved liver allografts: survival pattern and unresponsiveness following transduction with CTLA4Ig

The immune response of liver transplant recipients was modulated via adenovirus-mediated transduction of the cold-preserved liver with sequences encoding CTLA4Ig. Transplanted allografts demonstrated rapid transient local expression and recombinant protein production shortly after revascularization, resulting in intact liver function, indefinite survival of the recipient, and the development of donor-specific unresponsiveness. Lymphocytic infiltration of the graft was mainly of the T helper 2 (Th2) subset and was not associated with injury to primary cellular targets of the alloimmune response. These findings demonstrate a successful outcome of a feasible and potentially clinically relevant system of gene delivery of sequences encoding proteins capable of inhibiting the alloimmune response.

Organ transplantation in the twenty-first century

Major advances in the understanding of the immunologic process responsible for organ or cellular transplant rejection, a dramatic improvement in available immunosuppressive drugs, development of more sophisticated surgical techniques, and important progress in posttransplant intensive care over the last 30 years have led to a remarkable improvement in success following organ transplantation. Whereas excellent short-term survival of most transplanted organs is readily achieved, graft loss because of chronic rejection and the worsening problem of organ donor shortage remain major concerns in the field of transplantation. Recent advances in immunosuppressive drugs, induction of immunologic tolerance, and gene therapy strategies may help to prolong organ allograft survival in the future. Revised criteria for organ donation and xenotransplantation may one day solve the problem of organ supply. Today, as we approach the next millennium, we are optimistic that the elusive goal of immunologic tolerance will be achieved and perhaps applied to animal tissue. Such will certainly be the challenge for the next century.

Assessment of liver function: pre- and peritransplant evaluation

Liver transplantation has been demonstrated to be a successful therapeutic modality for patients with end-stage liver disease. The high rate of survival for an otherwise terminal condition has resulted in significant expansion of the indications and diseases treated by this procedure, and is hampered only by the limited numbers of organs available for transplantation. Efforts in clinical and laboratory medicine should be directed to identify candidates who would benefit most from this procedure, to provide better means for accurate assessment of liver reserve and the appropriate timing for transplantation, to identify quality liver grafts that would have the potential to tolerate cold preservation and reperfusion injury, and to assist in accurate monitoring of graft function immediately after transplantation. The aim of this manuscript is to describe the existing pathways for clinical and laboratory assessment of pretransplant residual liver function, the donor liver graft, and immediate posttransplantation function.

Gene transfer into nerve and muscle by isolated limb perfusion or during replantation

In this study, the authors tested the feasibility of adenovirus vectors transferring functional genetic material into relevent soft-tissue structures during replantation of mouse hindlimbs. An adenovirus vector was constructed encoding the marker gene LacZ and CMV promoter and titered by plaque forming assay to 5 x 10(9) particles/ml. C3H mouse hindlimbs were divided into three groups. In Group 1 (n = 9), the femoral neurovascular bundle was divided and re-anastomosed . Group 2 (n = 9) hindlimbs were transected at mid-femur, perfused with adenovirus, and replanted. Group 3 limbs (n = 4) were perfused with saline only, followed by replantation. After 48 hr, morbidity and mortality were assessed, and the replanted limbs were assayed for gene transfer by histochemistry and polymerase chain reaction. 12/18 limbs were viable after 48 hr. Histochemical staining for adenovirus-mediated LacZ expression was positive within skeletal muscle, femoral nerve, and capillaries adjacent to the anastomoses. Distal muscle was also gene transfer positive. PCR analysis confirmed adenovirus-mediated gene transfer within the femoral nerve and skeletal muscle. This study confirms that viral-mediated gene transfer can be accomplished into the soft tissues of a replanted extremity.

Adenovirus-mediated gene transfer of viral interleukin-10 inhibits the immune response to both alloantigen and adenoviral antigen

Although adenoviral vectors are attractive for gene transfer, their effectiveness is limited by host antiviral immune responses. In this study, we determined if host antiallograft and antiviral immunity could be diminished with an adenoviral vector encoding the immunosuppressive cytokine viral interleukin-10 (vIL-10). AdSV40vIL-10, a vIL-10-expressing adenoviral vector with an SV40 promoter, induced significant prolongation of murine cardiac allograft survival to 32.2 +/- 1.7 days compared to 14.2 +/- 1.0 days for controls (p < 0.01). This effect was specific for vIL-10 encoding vector and could be inhibited by anti-vIL-10 monoclonal antibody (mAb). In vivo administration of adenovirus facilitated the generation of adenovirus-specific cytotoxic T lymphocytes (CTL), whereas treatment with AdSV40vIL-10 prevented CTL priming and generation of virus-specific immunity. AdSV40vIL-10 also induced extended expression of a beta-galactosidase reporter from a co-injected LacZ-encoding adenoviral vector. These results demonstrate that adenovirus-mediated gene transfer and expression of vIL-10 prolong allograft survival and inhibit the immune response to adenoviral antigens, thereby improving the persistence of the vector and extending transgene expression. The efficacy of adenoviral vectors can be improved by incorporating immunosuppressive genes into the vector.

Adenoviral transfection of isolated pancreatic islets: a study of programmed cell death (apoptosis) and islet function

Gene therapy provides a potential technique to modify immunity in vitro and therefore may prolong graft survival in vivo. However, viral infection and gene transfer may damage target cells and interfere with biologic function. Viruses, including adenovirus, are known to be capable of modulating apoptosis and initiating cell death by either inducing or suppressing specific processes, depending on the virus and cell system studied. The effect of adenovirus on islet cell viability and function has not been examined in detail. In this study, the dose-dependent effect of an adenoviral vector on islet cell death and glucose-stimulated insulin secretion (GSIS) was investigated to establish a therapeutic window for the dose of viral vector administered. Isolated pancreatic rat islets were incubated with an adenovirus expressing a beta-galactosidase gene (AdHCMVsp1LacZ) at different viral concentrations [multiplicity of infection (MOI) 1:10, 1:100, and 1:1000]. Transfection rate, in vitro and in vivo islet viability, and occurrence of programmed cell death were determined 1, 3, and 7 days after transfection. Islets, transfected at MOI 1:10 and 1:100, demonstrated apoptosis not significantly different from nontransfected controls. Islets, transfected at MOI 1:1000, demonstrated a significant increase in apoptosis at 24 hr, which decreased over 7 days of culture. The increase in apoptosis was not reflected by a significant decrease in in vitro GSIS of surviving islet cells, as assessed by stimulation index following in vitro perifusion. SCID or nude mice transplanted with AdlacZ-transfected islets (MOI 1:100 and 1:1000) remained normoglycemic for > or = 30 days. These results demonstrate that transfection of islets using adenoviral vectors can be manipulated such that efficient expression of the gene product encoded by the transfected gene (beta-galactosidase) can be achieved at lower transfecting concentrations of the adenoviral vector (MOI 1:10, 20.2%; MOI 1:100, 30.7%) while preserving islet function. This efficiency of transfection may allow pretransplant manipulation of isolated islet cells without vector-specific alteration of islet function. In cases where high virus concentrations are required for efficient gene transfer (adequate expression of the transgene product), a deleterious effect of the vector on islet cell function, with increased cell loss due to increased apoptotic events, is predicted. Using the AdlacZ vector, cell loss by apoptotic mechanisms appears limited to the first days following coculture with high viral concentrations, and does not appear to influence in vitro or in vivo cell function of the surviving islet cells.

Randomized controlled trial to evaluate flush and reperfusion techniques in liver transplantation

To determine the impact of different flush and reperfusion techniques on postreperfusion syndrome (PRS) and postoperative graft function, 100 transplants were randomly assigned into four groups as follows: group 1 (n=31), portal vein flush, no vena caval venting; group 2 (n=21), hepatic arterial flush, no vena caval venting; group 3 (n=29), portal vein flush with vena caval venting; and group 4 (n=19), hepatic artery flush with vena caval venting. Donor and recipient characteristics were similar. Extensive intraoperative and postoperative monitoring was performed and measurements were documented immediately before reperfusion and at 1, 5, 15, and 30 min after reperfusion. PRS was defined by three criteria: mean arterial pressure (MAP) <60 mmHg at 1 min after reperfusion, MAP <60 mmHg at 5 min after reperfusion, and a decrease of 30% or more for the MAP percent area under the curve during the initial 5 min after reperfusion (%AUC). Using these definitions, the overall incidence of PRS was 21%, 8%, and 43%, respectively. Group 1 was the most hemodynamically stable; the incidence of PRS in group 1 was 2/31 (7%) at 1 min and 8/31 (25%) using %AUC criteria compared with 7/21 (33%) at 1 min and 12/21 (57%) using %AUC criteria for group 2 (P<0.05). The patients in groups 3 and 4 (vena caval venting) demonstrated smaller percentage increases in serum potassium levels (as determined by %AUC; 4.3+/-6.8 and 0.3+/-5.4, vs. 15.1+/-8.1 for group 1 and 22.9+/-8.2 for group 2). The difference between group 4 and group 2 was statistically significant (P<0.05). The increases in serum potassium did not translate into increased cardiac or hemodynamic instability. Combining all data obtained over the first 30 min after reperfusion, there was no statistically significant difference in hemodynamic or biochemical changes noted among the four groups. Postoperative liver function was similar among the four groups. We conclude that portal vein flush without vena caval venting provided a lower incidence of PRS than any other technique. Vena caval venting decreased the release of potassium into the circulation. Postoperative graft function was not significantly affected by flush and reperfusion techniques.

Coccidioidomycosis in liver transplant patients

Eight (0.59%) of 1,347 patients who underwent liver transplantation at the UCLA Medical Center (Los Angeles) developed coccidioidomycosis. Whereas only one case occurred during the first 8 years and 10 months of the UCLA Liver Transplant Program (February 1984 to December 1992), seven cases occurred within the following 23-month period (December 1992 to November 1994). The median time of onset for infection after transplantation was 8 weeks (range, 4-312 weeks). Clinical presentations of patients with coccidioidomycosis included pneumonia (six cases), pneumonia with meningitis (one case), hepatitis (one case), and monoarticular arthritis (one case). Despite therapy with amphotericin B alone (six cases) or amphotericin B plus fluconazole (two cases), infection was fatal in four of eight cases. As of this writing, the four surviving patients are receiving chronic maintenance therapy with either fluconazole (three patients) or itraconazole (one patient). These experiences show that coccidioidomycosis can be a serious and frequently fatal infection after liver transplantation and that the incidence of this disease appears to be increasing.

Decreased alloreactivity to human islets secreting recombinant viral interleukin 10

The objective of this study was to analyze allogeneic lymphocyte proliferative responses to cultured human pancreatic islets after gene transfer of viral interleukin (IL)-10 to the islets using replication-defective adenoviral vector. Human islets, either whole or dispersed into single cells, were cocultured with adenovector containing an expression cassette encoding the viral IL-10 gene under control of an SV40 promoter, this sequence replacing viral E1A and part of E1B early viral protein sequences. Subsequent production of recombinant protein by islets was determined by ELISA, and was found dependent on the multiplicity of infection (or ratio of vector to target cells). Protein was secreted by transfected islets at high levels 3-7 days after gene transfer. At high multiplicity of infection (100:1), islet viability was normal, but insulin secretion in response to glucose stimulation was blunted by 50%. Low-level recombinant viral IL-10 secretion by the islets was associated with increased allogeneic lymphocyte proliferation in mixed islet lymphocyte reactions. At protein levels in islet supernatant above 5 ng/ml, lymphocyte proliferation was significantly reduced. This pattern of viral IL-10 effect on lymphocyte proliferation correlated well with mixed lymphocyte reaction assays using purified protein. We conclude that transferred cytokine sequences are secreted by transfected islets as a function of the initial vector inoculum. The functional effect of the secreted cytokine viral IL-10 on allogeneic lymphocyte proliferation is dose dependent. Low-level recombinant protein secretion tended to augment lymphocyte proliferation, whereas high-level secretion significantly down-regulates this response.

Adenovirus-mediated gene transfer in the transplant setting: early events after orthotopic transplantation of liver allografts expressing TGF-beta1

We hypothesized that adenovirus mediated gene transfer of TGF-beta1 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-beta1 was used to replaced the E1 region of adenovirus type 5 (AdmTGF-beta1). Expression and protein production of biologically active murine TGF-beta1 was tested in AdmTGF-beta1-transduced Hep G2 cells and TGF-beta-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 TNFalpha, and IFNgamma were determined using ELISA and quantitative PCR. TGF-beta1 ELISA of culture supernatants from AdmTGF-beta1 transduced hepatocyte cell line Hep G2 excreted TGF-beta1 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-beta-sensitive cells. Enhanced production of TGF-beta1 in transduced allografts was associated with decreased levels of TNFalpha and IFNgamma when compared with nonimmunosuppressed controls. Adenovirus-mediated gene transfer of murine TGF-beta1 into hepatic cells results in the expression of biologically active protein. Transduction of allografts with TGF-beta1 down-regulates TNFalpha and IFNgamma production early after orthotopic transplantation. Graft transduction with TGF-beta1 offers a novel approach to study the effects of single immune modulator on alloreactive immune response, T cell function, and cytokine cascade.

Failure of ganciclovir prophylaxis to prevent allograft reinfection following orthotopic liver transplantation for chronic hepatitis B infection

The effect of ganciclovir prophylaxis on reinfection of hepatic allografts by hepatitis B virus (HBV) was studied in 26 patients undergoing orthotopic liver transplantation (OLT) for decompensated cirrhosis due to HBV. Patients were randomized to receive either ganciclovir (6 mg/kg/day intravenously for a total of 100 days) or acyclovir (10 mg/kg every 8 hours intravenously until discharged and then 800 mg orally every 6 hours) for a total of 100 days after OLT as part of a study of prophylaxis against cytomegalovirus infection. All patients received hepatitis B immunoglobulin (HBIG), 10,000 units intravenously, during the anhepatic phase, daily for the first 7 days, after OLT, and then every 4 weeks for 6 months, Seven of 12 (58%) patients in the ganciclovir group developed recurrent HBV, compared with 6/14 (46%) of the acyclovir group (nonsignificant). No significant difference was observed in time to recurrent HBV in the ganciclovir group (mean 13.2 months) compared to the acyclovir group (mean 11 months). Our results suggest that ganciclovir administered prophylactically for 100 days after OLT does not prevent or delay graft reinfection by HBV.

Improved results of liver transplantation in patients with portal vein thrombosis

OBJECTIVE

To analyze the impact of preexisting portal vein thrombosis (PVT) on the operative management and outcome of liver transplantation.

DESIGN

Retrospective review of 1423 patients who received transplants over 11 years.

SETTING

Tertiary referral center.

PATIENTS OR OTHER PARTICIPANTS

Seventy patients who underwent liver transplantation who had preexisting PVT.

INTERVENTIONS

Portal vein thromboendovenectomy, vein grafting, or use of portal collateral veins for inflow during liver transplantation.

MAIN OUTCOME MEASURES

Postoperative PVT, intraoperative transfusion, retransplantation rate, 30-day and 1-year actuarial survival rates.

RESULTS

Operative management consisted of thromboendovenectomy in 61 cases, vein graft to the superior mesenteric vein in 6 cases, and vein graft to other mesenteric veins in 3 cases. The incidence of posttransplant PVT was 3% (n = 2). The mean +/- SD transfusion requirement was 23 +/- 18 U. The 1-year actuarial survival rate was 74% but improved from 66% in the first 35 cases to 82% in the latter 35 cases.

CONCLUSIONS

Thromboendovenectomy is the procedure of choice for PVT. Results of liver transplantation in patients with PVT improve significantly with experience gained and are equivalent to results in patients without PVT.

Rapid en bloc technique for pancreas-liver procurement. Improved early liver function

It is our experience that warm dissection in the porta hepatis as well as extensive organ mobilization during combined pancreas-liver procurements may cause posttransplant dysfunction of the liver. To avoid this, we recently utilized a rapid en bloc procurement technique with minimal warm dissection and division of the liver and pancreas ex vivo. Fifteen procurements were performed using this rapid en bloc technique; seventeen procurements involved extensive dissection followed by sequential in situ procurement of the liver and pancreas grafts. The control group consisted of 15 age-matched patients who received livers when no pancreas was harvested. Dissection time was 157 +/- 13 min (mean +/- SEM) in the in situ group, 78 +/- 3 min in the en bloc group (P<0.02), and 51 +/- 6 min in the liver only group (P<0.02). There was no difference in donor age, cold ischemia time, or recipient United Network for Organ Sharing status. Pancreata obtained using the en bloc technique all had immediate function and there were no episodes of acute pancreatitis. Early liver graft function, as assessed by lactate dehydrogenase, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, and total bilirubin levels, was significantly lower in the en bloc and liver only group when compared with the in situ group. The total hospital stay was also significantly lower in these groups. We conclude that the rapid en bloc technique decreases operative time during the donor operation. Procurement-related injury to the liver graft is minimized without compromising pancreas graft function.

Viral IL-10 gene therapy inhibits TNF-alpha and IL-1 beta, not IL-6, in the newborn endotoxemic mouse

INTRODUCTION

Modulation of the inflammatory cascade within the liver of critically ill infants may improve the chance of survival. Using gene therapy, the authors hypothesized that augmented local production of the counter-regulatory cytokine viral interleukin-10 (IL-10) in vivo will modulate the critical cytokines in the inflammatory response. The purpose of the present study was to determine whether replication-defective adenovirus-mediated viral IL-10 (vIL-10) gene transfer and expression within the liver can achieve this goal in newborn mice.

MATERIALS AND METHODS

Four-week-old Balb/c mice were administered (intraperitoneally) 1 x 10(9) plaque-forming units (pfu) per milliliter of an adenovirus vector (E1a/b-deleted) than encodes the sv40 promoter and the BCRF1 cDNA, or of control vector dl434 that expresses no foreign gene. Forty-eight hours later the mice were challenged with 50 micrograms/kg of lipopolysaccharide (LPS) they were killed 1, 2, 6, or 24 hours later (six at each time point). Southern blot analysis was performed on genomic DNA isolated from the liver, lung, and kidney to assess gene transfer of BCRF1. Homogenized liver protein was analyzed for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, IL-6, and recombinant vIL-10.

RESULTS

Southern blot analysis confirmed successful gene transfer to the liver but not to the lung, kidney, or dl434-transduced liver in mice that received adenovectors. Viral IL-10 levels within the liver ranged from 14 to 18 ng/mL. In controls, TNF-alpha production was elevated at early time points, to 18,000 pg/mL, but decreased rapidly by 24 hours after LPS challenge. The TNF-alpha levels of animals treated with Ad5svBCRF1 were significantly lower than those of controls throughout the course of study (P < .0001). After the LPS challenge, hepatic IL-1 beta decreased, from a maximum of 800 pg/mL (2 hours) to 411 pg/mL (24 hours). Inhibition of IL-1 beta by vIL-10 occurred at 1 hour (P > .016) and 2 hours (P < .001) only. Hepatic production of IL-6 after LPS challenge ranged from 7 to 8,000 pg/mL in all groups and was not altered by vIL-10 gene therapy.

CONCLUSION

In vivo administration of adenovectors encoding BCRF1 to newborn mice results in efficient hepatic transduction and expression of recombinant vIL-10. The Kupffer cell response to LPS is suppressed with respect to TNF-alpha and IL-1 beta, but not IL-6. In vivo modulation of hepatic cytokine responses is achievable using gene products that mimic cellular cytokines. This is an effective model for the selective evaluation of therapeutic gene products for gene therapy of sepsis.