Patterns of transgene expression and viral clearance from the transplanted liver following ex vivo adenovirus-mediated gene transfer

Cytotoxic T Lymphocyte-associated Protein 4 Acts on Local Draining Lymph Nodes in the Allogeneic Abdominal Skin Flap of a Rat Model to Extend Its Survival

BACKGROUND

Early acute allograft rejection is the result of immune cells mainly composed of thymocyte (T) cells, which are activated, mature, and differentiate in lymphoid tissue.

METHODS

Cytotoxic T lymphocyte-associated protein 4 immunoglobulin (CTLA4-Ig) competitively suppresses the cluster of differentiation 28/CTLA4-B7 costimulatory signaling pathway and alters the ratio of T helper 1 to T helper 2, leading to the inhibition of T cell activation.

RESULTS

We used lentivirus-packed CTLA4-Ig to infect the local draining lymph nodes of the allograft skin flap in a rat model, which effectively extended the survival of the allograft. Meanwhile, it also reduced the dose of immunosuppressant necessary in the early stages of transplantation, which lowered the toxicity and side effects of the drug.

CONCLUSIONS

Our findings provide new insights into transplantation immunology, facilitate the exploration of a safe and effective immunosuppressive therapy, and promote the wide clinical application of composite tissue allotransplantation.

Immune safety of a novel oncolytic mutant M1 after administration in vivo

The aim of this study was to evaluate the safety and efficiency of a novel, oncolytic adenovirus mutant M1 administered in conjunction with immunosuppressive agents. Animal models were established by administering purified M1 either intravenously or retroperitoneally. At different time points, blood samples were taken from the mice for testing of liver and renal function. Microscopic examination of the liver was performed to observe pathological changes. Immunohistochemical analyses were used to evaluate the expression of the adenovirus in the liver. Lymphocyte recruitment to the liver and the activation of adenovirus specific T cells were also analyzed. No signs of general toxicity were observed, but transient increases in ALT and Scr were observed following the administration of M1. Microscopic examination revealed a mild inflammatory response in the liver. Compared to intravenous injection, higher expression levels of adenoviral proteins were observed after retroperitoneal injection. Combined treatment with cyclosporine A resolved the liver and kidney dysfunction and increased the concentration of the adenovirus in the liver. The use of the novel oncolytic adenovirus mutant M1 in vivo is safe, and the combined administration of M1 with immunosuppressive agents was able to enhance the effectiveness and safety profile of M1.

CC Chemokine receptor 5 deficiency does not prevent local immune responses to adenovirus vector in islet transplant recipients

BACKGROUND

CC chemokine receptor 5 (CCR5) plays an important role in mediating inflammation. We examined the effect of CCR5 on the immune response to adenovirus vectors and graft function in islet transplant model.

MATERIALS AND METHODS

Syngeneic wild-type (WT) or CCR5-deficient (KO) mouse islets transduced with adenovirus encoding β-gal were transplanted under the renal capsule. After transplant, blood glucose, glucose tolerance, graft cellular infiltration, transgene and chemokine/receptor expression, and systemic anti-adenoviral/-β-gal immune response were evaluated.

RESULTS

Diabetes was reversed in 1 d in both WT and KO untransduced recipients, while islets transduced with adenovirus failed to reverse diabetes until 10 d post-transplant in WT recipients or even longer (>15 d) in KO recipients (P < 0.05). A profound infiltration of CD4(+), CD8(+) cells and macrophages was observed in both WT and KO transduced grafts at 25 d. Though transgene expression was significantly reduced, insulin and β-gal expression persisted over 3 mo. Glucose tolerance was impaired in all grafts in KO recipients compared with untransduced grafts in WT recipients at 25 d post-transplant, but was equivalent at 3 mo. Early expression of CCR2 mRNA was increased in transduced grafts in both WT and KO recipients. No systemic antivector immunity was demonstrated in any recipient group.

CONCLUSIONS

Transduction of islets with adenovirus causes significant local inflammation in islet grafts and impairs early graft function in CCR5-deficient recipients, but long-term graft function is preserved. Thus, CCR5 absence does not prevent the local immune response to adenovirus transduction, and vector-associated graft dysfunction is not mediated by CCR5.

Adenoviral vector-mediated glucagon-like peptide 1 gene therapy improves glucose homeostasis in Zucker diabetic fatty rats

BACKGROUND

Glucagon-like peptide-1 (GLP-1) is a gut-derived incretin hormone that plays an important role in glucose homeostasis. Its functions include glucose-stimulated insulin secretion, suppression of glucagon secretion, deceleration of gastric emptying, and reduction in appetite and food intake. Despite the numerous antidiabetic properties of GLP-1, its therapeutic potential is limited by its short biological half-life due to rapid enzymatic degradation by dipeptidyl peptidase IV. The present study aimed to demonstrate the therapeutic effects of constitutively expressed GLP-1 in an overt type 2 diabetic animal model using an adenoviral vector system.

METHODS

A novel plasmid (pAAV-ILGLP-1) and recombinant adenoviral vector (Ad-ILGLP-1) were constructed with the cytomegalovirus promoter and insulin leader sequence followed by GLP-1(7-37) cDNA.

RESULTS

The results of an enzyme-linked immunosorbent assay showed significantly elevated levels of GLP-1(7-37) secreted by human embryonic kidney cells transfected with the construct containing the leader sequence. A single intravenous administration of Ad-ILGLP-1 into 12-week-old Zucker diabetic fatty (ZDF) rats, which have overt type 2 diabetes mellitus (T2DM), achieved near normoglycemia for 3 weeks and improved utilization of blood glucose in glucose tolerance tests. Circulating plasma levels of GLP-1 increased in GLP-1-treated ZDF rats, but diminished 21 days after treatment. When compared with controls, Ad-ILGLP-1-treated ZDF rats had a lower homeostasis model assessment for insulin resistance score indicating amelioration in insulin resistance. Immunohistochemical staining showed that cells expressing GLP-1 were found in the livers of GLP-1-treated ZDF rats.

CONCLUSIONS

These data suggest that GLP-1 gene therapy can improve glucose homeostasis in fully developed diabetic animal models and may be a promising treatment modality for T2DM in humans.

Lentivirus-mediated superoxide dismutase1 gene delivery protects against oxidative stress-induced liver injury in mice

BACKGROUND

The exposure of liver to hepatotoxins, and their subsequent metabolism, results in increased reactive oxygen species (ROS), one of the major culprits in causing both acute liver cell injury and chronic liver diseases. The aim of this present study is to investigate the protective effects of lentiviral vector-mediated copper-zinc superoxide dismutase (LV-SOD1) gene transfer against ROS-induced cytotoxicity in Hep G2 cells and liver injury in mice.

METHODS

In vitro SOD1 efficacy was tested against two ROS-generating systems: hypoxanthine/xanthine oxidase (HX/XO) and hydroxyethyl radicals (HER), whereas in vivo SOD1 efficacy was evaluated in carbon tetrachloride (CCl4)-induced liver injury in C57BL/6 mice.

RESULTS

LV-SOD1 transduction in Hep G2 cells resulted in a significant increase in SOD activity in cell lysates, and it significantly decreased the toxicity induced by HX/XO and HER. High SOD1 expression in the liver was achieved via portal vein injection of LV-SOD1 in mice and these high levels were observed for 30 days, the length of the experiment to date. SOD1 overexpression significantly decreased the toxicity and restored liver function in the CCl4-treated mice.

CONCLUSIONS

These findings demonstrate for the first time that LV transduction led to the long-term expression of fully functional transgene expression in both in vitro and in vivo systems.