Pig-to-monkey islet xenotransplantation using multi-transgenic pigs.

The generation of pigs with genetic modifications has significantly advanced the field of xenotransplantation. New genetically engineered pigs were produced on an α1,3-galactosyltransferase gene-knockout background with ubiquitous expression of human CD46, with islet beta cell-specific expression of human tissue factor pathway inhibitor and/or human CD39 and/or porcine CTLA4-lg. Isolated islets from pigs with 3, 4 or 5 genetic modifications were transplanted intraportally into streptozotocin-diabetic, immunosuppressed cynomolgus monkeys (n = 5). Immunosuppression was based on anti-CD154 mAb costimulation blockade. Monitoring included features of early islet destruction, glycemia, exogenous insulin requirement and histopathology of the islets at necropsy. Using these modified pig islets, there was evidence of reduced islet destruction in the first hours after transplantation, compared with two series of historical controls that received identical therapy but were transplanted with islets from pigs with either no or only one genetic modification. Despite encouraging effects on early islet loss, these multi-transgenic islet grafts did not demonstrate consistency in regard to long-term success, with only two of five demonstrating function beyond 5 months.

Administration of a negative vaccination induces hyporesponsiveness to islet allografts.

As a result of less than optimal outcomes the use of islet allografts as a standard insulin replacement therapy is limited to adults with a history of extreme glucose dysregulation and hypoglycemia unawareness. In this study, we examined the use of prophylactic immunotherapy to prevent islet allograft rejection in the absence of antirejection drugs. Our protocol to achieve allograft acceptance used a negative vaccination strategy that is comprised of apoptotic donor cells delivered in Incomplete Freund's Adjuvant (IFA) 1 week prior to islet transplantation. The goal of this new protocol is to elicit hyporesponsiveness to alloantigen prior to islet transplantation. First, we examined our protocol without islet allograft transplants and determined that the negative vaccination was not globally immunosuppressive or immunostimulatory. Islet allograft experiments using fully MHC-mismatched islet donors and recipients demonstrated that the negative vaccination strategy induced long-term islet allograft acceptance. Upon rechallenge with alloantigen, the negative vaccination protocol successfully achieved hyporesponsiveness. In addition, the microenvironment at the site of the tolerant allograft revealed a decrease in proinflammatory mediators (IFN-γ, TNF-α) and an increase in the anti-inflammatory mediator IL-10, as well as increased expression of the master regulator of T-regulatory cells, FOXP3. Our data suggest that pretreating allograft recipients with apoptotic donor alloantigen delivered in IFA induced long-term islet allograft acceptance and glycemic control by introducing alloantigen to the recipient immune system in a nonimmunostimulatory manner prior to transplant.

dsAAV8-mediated gene transfer and ß-cell expression of IL-4 and ß-cell growth factors are capable of reversing early-onset diabetes in NOD mice.

Type-I diabetes is a chronic disease mediated by autoimmune destruction of insulin-producing ß-cells. Although progress has been made towards improving diabetes-associated pathologies and the quality of life for those living with diabetes, no therapy has been effective at eliminating disease manifestations or reversing disease progression. Here, we examined whether double-stranded adeno-associated virus serotype 8 (dsAAV8)-mediated gene delivery to endogenous ß-cells of interleukin (IL)-4 in combination with ß-cell growth factors can reverse early-onset diabetes in NOD mice. Our results demonstrate that a single treatment with dsAAV8 vectors expressing IL-4 in combination with glucagon-like peptide-1 or hepatocyte growth factor/NK1 under the regulation of the insulin promoter enhanced ß-cell proliferation and survival in vivo, significantly delaying diabetes progression in NOD mice, and reversing disease in ∼10% of treated NOD mice. These results demonstrate the ability to reverse hyperglycemia in NOD mice with established diabetes by in vivo gene transfer to ß-cells of immunomodulatory factors and ß-cell growth factors.

Islet amyloid deposition limits the viability of human islet grafts but not porcine islet grafts.

Islet transplantation is a promising treatment for diabetes but long-term success is limited by progressive graft loss. Aggregates of the beta cell peptide islet amyloid polypeptide (IAPP) promote beta cell apoptosis and rapid amyloid formation occurs in transplanted islets. Porcine islets are an attractive alternative islet source as they demonstrate long-term graft survival. We compared the capacity of transplanted human and porcine islets to form amyloid as an explanation for differences in graft survival. Human islets were transplanted into streptozotocin-diabetic immune-deficient mice. Amyloid deposition was detectable at 4 weeks posttransplantation and was associated with islet graft failure. More extensive amyloid deposition was observed after 8 weeks. By contrast, no amyloid was detected in transplanted neonatal or adult porcine islets that had maintained normoglycemia for up to 195 days. To determine whether differences in IAPP sequence between humans and pigs could explain differences in amyloid formation and transplant viability, we sequenced porcine IAPP. Porcine IAPP differs from the human sequence at 10 positions and includes substitutions predicted to reduce its amyloidogenicity. Synthetic porcine IAPP was considerably less amyloidogenic than human IAPP as determined by transmission electron microscopy, circular dichroism, and thioflavin T binding. Viability assays indicated that porcine IAPP is significantly less toxic to INS-1 beta cells than human IAPP. Our findings demonstrate that species differences in IAPP sequence can explain the lack of amyloid formation and improved survival of transplanted porcine islets. These data highlight the potential of porcine islet transplantation as a therapeutic approach for human diabetes.

Suitability of human juvenile pancreatic islets for clinical use.

AIMS/HYPOTHESIS: The limited availability of deceased donor pancreases suitable for pancreas and islet transplantation calls for a broader utilisation of donor tissue for transplantation purposes. Young donors, representing, fortunately, a minor but significant pool of individuals, have been largely under-employed, mainly because of anatomical and functional incompatibilities with potential recipients. For islet transplantation, the isolation of pancreatic islets from young donors rarely occurs, because of technical problems. As a result of the peculiar characteristics of young donor pancreases, the standard isolation procedure does not allow efficient separation of the islets from the surrounding exocrine tissue, and favours the generation of mantled islets. Nonetheless, young donor islets offer high qualitative and clinically appealing characteristics. SUBJECTS AND METHODS: We standardised a modified methodology to obtain purified and mantle-free human islets from young donors. This method principally involves efficient delivery of isolation enzyme with reduced mechanical disruption of the pancreas combined with additional filtration steps. RESULTS: We were able to obtain purified and mantle-free human islets from donors as young as 6 months of age with good morphological and functional properties. The good qualitative characteristics of the islets, evidenced in vitro, were proven in vivo, as they were qualitatively superior to islets of older donors in transplantation studies. CONCLUSIONS/INTERPRETATION: This study justifies the utilisation of islets derived from young donors for islet transplantation.

DNA vaccination with an insulin construct and a chimeric protein binding to both CTLA4 and CD40 ameliorates type 1 diabetes in NOD mice.

Type 1 diabetes (T1D), a T-cell-mediated autoimmune disease, could be attributed to many defects in nonobese diabetic (NOD) mice, including deficient expressions of costimulatory molecules that impair antigen presentation. Thus, this deficient antigen presentation may result in a reduced ability to induce a tolerogenic response through negative selection/regulation of autoreactive T cells. Improperly activated T cells seem to be able to induce autoimmune responses causing diabetes. To re-establish tolerance to autoantigens by modulating costimulation, we constructed and tested a new type of DNA vaccine encoding a membrane-bound preproinsulin (mbPPI) and a chimeric gene vector encoding mutant B7.1/CD40L (mB7.1/CD40L) fusion protein. This mutant B7.1 binds CTLA4 but not CD28. We report that young NOD mice immunized with mbPPI along with mB7.1/CD40L DNA vectors significantly reduced diabetes incidence while treatment with CTLA4/IgG1 exacerbated diabetes. In conclusion, the combination of mbPPI and mB7.1/CD40L was able to protect against autoimmunity and diabetes in NOD mice possibly by promoting a more efficient presentation of autoantigen PPI and inducing specific tolerance to PPI by negatively regulating autoreactive T cells.

Prolongation of islet allograft survival following ex vivo transduction with adenovirus encoding a soluble type 1 TNF receptor-Ig fusion decoy.

Islet transplantation is a viable long-term therapeutic alternative to daily insulin replacement for type I diabetes. The allogeneic nature of the transplants poses immunological challenges for routine clinical utility. Gene transfer of immunoregulatory molecules and those that improve insulin release kinetics provides rational approaches to facilitate allogeneic islet transplantation as a potential therapy. We have examined the efficacy of a soluble type 1 tumor necrosis factor receptor (TNFR) immunoglobulin-Fc fusion transgene (TNFR-Ig) to protect human islets from cytokine-induced apoptosis in culture, as well as in facilitating allogeneic islet transplants in diabetic mice. Cultured human islets were transduced with an adenoviral vector encoding human TNFR-Ig (Ad-TNFR-Ig). TNFR-Ig protein was secreted by cultured islets, as well as by transduced mouse islet transplants recovered from mouse recipients. Glucose-induced insulin release kinetics were comparable among untransduced, Ad-TNFR-Ig-infected human islets and vector-transduced islets exposed to cytokines. In parallel, Ad-TNFR-Ig-infected islets were protected from cytokine-induced apoptosis activation. Finally, diabetic mice transplanted with allogeneic islets expressing TNFR-Ig returned to and maintained normoglycemia significantly longer than untransduced islet recipients. These data support the potential utility of TNFR-Ig gene transfer to islets as a means of facilitating allogeneic islet transplantation.

Delivery of a cyclic adenosine 3',5'-monophosphate response element-binding protein (creb) mutant to seminiferous tubules results in impaired spermatogenesis.

FSH binding to Sertoli cells is required for optimal production of sperm in mammals. The cAMP response element-binding protein (CREB) is a major mediator of FSH-induced changes in gene expression. To determine whether CREB is required for spermatogenesis, an adenovirus encoding a phosphorylation-defective CREB mutant (AdCREBm1) was used to inhibit CREB activity in Sertoli cells. Addition of AdCREBm1 to primary rat Sertoli cell cultures completely abolished induction of the CREB-regulated c-fos gene. Injection of an adenovirus encoding ss-galactosidase into the rat testis seminiferous tubules in vivo demonstrated that predominately Sertoli cells were infected by adenovirus. AdCREBm1-directed expression of CREBm1 in seminiferous tubules did not affect Sertoli cell viability, but resulted in the apoptosis of meiotic spermatocyte germ cells within 4 days of adenovirus injection into seminiferous tubules. Disrupted spermatogenesis, defined by at least a 75% reduction of round spermatids, was observed in 42 +/- 5.8% of seminiferous tubules 14 days after AdCREBm1 infection, whereas using this criteria, testes injected with a control adenovirus did not display disrupted spermatogenesis. These data demonstrate that AdCREBm1 causes apoptosis and elimination of germ cells and suggest that CREB is required to produce a Sertoli cell-derived factor that is critical for germ cell survival.

Restricted TCR V beta gene expression and enterovirus infection in type I diabetes: a pilot study.

AIMS/HYPOTHESIS: High frequencies of T-cell receptor (TCR) V beta 7+ T cells were detected among the lymphocytes isolated from pancreatic islets of children at the onset of Type I (insulin-dependent) diabetes mellitus. We assessed whether a preferential expression of certain TCR V beta gene families could also be detected among the peripheral blood mononuclear cells from diabetic patients. METHODS: T-cell receptor repertoires were evaluated by using a semi-quantitative RT-PCR-based technique and confirmed by FACS analysis in peripheral blood mononuclear cells from diabetic patients before, at and after onset of the disease. These patients were also tested for exposure to enteroviruses by RT-PCR and by measuring titres of enterovirus-specific antibodies of the IgA, IgG, and IgM classes. RESULTS: T-cell receptor V beta 7 gene family values were higher in recently-diagnosed diabetic patients (10.5% +/- 3.7) than in age-matched non-diabetic control subjects (5.1% +/- 1.6) (p < 0.001). In a time-course analysis of people who developed diabetes during clinical monitoring (i.e., converters), T-cell receptor V beta 7 gene expression showed values consistently above 10% (p < 0.0005). Long-standing diabetic patients showed lower percentage of V beta 7 expression compared to values measured at disease onset. In the longitudinal study of the converters, multiple acute enterovirus infections were also detected. These infections appeared to be temporally related to increased percentage of V beta 7 gene transcripts. CONCLUSION/INTERPRETATION: The deviation in the T-cell receptor V beta repertoire among circulating T cells from diabetic patients seems to re-emphasize the importance of enterovirus infections in accelerating the progression of Type I diabetes.

Immunology of type 1 diabetes. Intervention and prevention strategies.

Type 1 diabetes is the outcome of a progressive and selective destruction of insulin-producing cells in the pancreatic islets of Langerhans. The precise cause and mechanism(s) that trigger the insulin-producing cell destruction are still unclear, although it is well accepted that an autoimmune process plays a central role in diabetes development among genetically susceptible children. Additionally, certain viral infections, especially those caused by Coxsackievirus B, have been associated with the onset of type 1 diabetes. Possible gene therapy-based prevention and intervention strategies are discussed, based on the most accepted models of type 1 diabetes pathogenesis.

The same HLA-DQ alleles determine either susceptibility or resistance to different coxsackievirus-mediated autoimmune diseases.

An important characteristic of autoimmune diseases is their association with major histocompatibility complex class I and class II alleles. In this study, we compared insulin-dependent diabetes mellitus (IDDM) with idiopathic dilated cardiomyopathy (IDC) from a strictly immunologic perspective. Although the target organs are different, being in one case the insulin-producing beta cells of the pancreas and in the other case the myocytes of the heart, many aspects of the tissue-specific immune destruction are common. Similar yet different Coxsackievirus B strains with either pancreotropic or cardiotropic specificity are able to perpetrate the first injury of the respective target tissue. Their shared capacity of inducing a superantigenic reaction further enhances the damage. Once previously secluded autoantigens are then exposed to the immune system, the tissue injury is completed via a more conventional type of immune response. On the basis of the compounded results we obtained, it is possible to propose that the same HLA-DQ molecules which are able to protect the individuals from IDDM (e.g., HLA-DQA1*0102, DQB1*0602) seem to favour the enteroviral attack to the myocardium, while alleles which confer the strongest susceptibility to IDDM (e.g., DQA1*0301, DQB1*0302), seem unable to sustain the immune attack against the heart.

No linkage or association of telomeric and centromeric T-cell receptor beta-chain markers with susceptibility to type 1 insulin-dependent diabetes in HLA-DR4 multiplex families.

The T-cell receptor beta locus (TCRB) on chromosome 7q35 was studied as a candidate region for genetic susceptibility to type 1 insulin-dependent diabetes (IDDM). A highly polymorphic microsatellite marker mapping to the TCRBV6.7 gene and a TCRB C-region RFLP were used to genotype the members of a total of 21 multiplex IDDM families from two different geographical areas. There was no evidence to support linkage to either of these markers with IDDM, and conventional two-point analysis excluded linkage to the telomeric end of the TCRB complex, in the region of the highly informative TCRBV6.7 marker. There was significant linkage of IDDM to the class II HLA-D locus with significant lod scores > 3.0 obtained for the HLA-DRB1 and HLA-DQB1 genes. Affected sib-pair (ASP) and transmission disequilibrium (TDT) association tests confirmed these findings.

Susceptibility to type 1 (insulin-dependent) diabetes mellitus in Spanish patients correlates quantitatively with expression of HLA-DQ alpha Arg 52 and HLA-DQ beta non-Asp 57 alleles.

HLA-DQ alpha and beta alleles were chosen as the most sensitive Type 1 (insulin-dependent) diabetes mellitus susceptibility markers for evaluating the disease associations and Type 1 diabetes risk in a population-based registry from Madrid. The absence of aspartic acid in position 57 of the DQ beta chain (non-Asp 57), and the presence of arginine in position 52 of the DQ alpha chain (Arg 52) were found to be reliable markers of Type 1 diabetes susceptibility among the Spanish population, with significantly higher frequencies among the cases of Type 1 diabetes compared to randomly selected non-diabetic control subjects from the general Madrid population. While non-Asp 57 homozygosity conferred an absolute risk of 32.3 per 100,000 per year and Arg 52 of 31.5 per 100,000 per year, the risk for double homozygotes for both non-Asp 57 and Arg 52 was estimated as 101.7 per 100,000 per year. Individuals homozygous for only one of these alleles, and heterozygous at the other locus, had a markedly lower Type 1 diabetes risk (12.8 per 100,000 per year), approximating the general population incidence for Madrid. Thus, susceptibility to Type 1 diabetes in Spanish patients is associated, quantitatively, with non-Asp 57 DQ beta and Arg 52 DQ alpha alleles.

Adoptive immunotherapy of microscopic and advanced visceral metastases with in vitro sensitized lymphoid cells from mice bearing progressive tumors.

Lymphocytes from mice bearing the weakly immunogenic MCA 105 sarcoma contained pre-effector cells that could be sensitized and expanded in vitro to acquire anti-tumor reactivity. The in vitro sensitization (IVS) required antigenic stimulation by tumor cells and the presence of IL-2 for cellular proliferation. Recent work has also demonstrated that IVS cells could be generated in an IL-2 concentration as low as 2 U/ml. In the present study, we have evaluated therapeutic efficacy of IVS cells generated in different concentrations of IL-2 against advanced metastases established in the lung as well as in the liver. Treatment of microscopic or grossly visible pulmonary metastases established for 3 or 10 days by systemic transfer of IVS cells resulted in significant reductions of the numbers of metastases. On a per cell basis, IVS cells generated in 2 U/ml of IL-2 exhibited at least twofold greater reactivity than cells generated in 1000 U/ml of IL-2. In survival experiments, treatment of established microscopic (day 3) and visible (day 10) pulmonary metastases with 1.5 x 10(7) and 3 x 10(7) IVS cells generated in 2 U/ml of IL-2 resulted in prolongation of survival and cure of the disease in 60 and 30% of animals, respectively. The systemic anti-tumor effect of IVS cells was further investigated in mice with hepatic metastases. Treatment of day 3 microscopic hepatic metastases revealed that as little as 1.2 X 10(7) IVS cells generated in 2 U/ml of IL-2 reduced the mean number of metastases from more than 250 in various control groups to 32. Evaluation by survival demonstrated that transfer of 1.7 x 10(7) and 3.8 x 10(7) IVS cells was capable of prolonging the survival and curing 40 and 30% of mice bearing day 3 and day 9 hepatic metastases, respectively. Again, IVS cells generated in 2 U/ml of IL-2 were more effective therapeutically than cells generated in 1000 U/ml of IL-2. In all experiments, mice were also given IL-2 to enhance the in vivo reactivity of IVS cells. However, the doses of IL-2 alone had no therapeutic benefit. Taken together, our results show that adoptive immunotherapy with IVS cells generated from tumor-bearing mice was an effective means of eliminating advanced metastases in various visceral organs.