Identification of the novel HLA allele HLA-DRB1*03:201 by next-generation sequencing.

HLA-DRB1*03:201 differs from HLA-DRB1*03:01 in exon 3 at codon 178 resulting in a proline to serine substitution.

NN1213 - A Potent, Long-Acting, and Selective Analog of Human Amylin.

Amylin, a member of the calcitonin family, acts via amylin receptors in the hindbrain and hypothalamus to suppress appetite. Native ligands of these receptors are peptides with short half-lives. Conjugating fatty acids to these peptides can increase their half-lives. The long-acting human amylin analog, NN1213, was generated from structure-activity efforts optimizing solubility, stability, receptor affinity, and selectivity, as well as in vivo potency and clearance. In both rats and dogs, a single dose of NN1213 reduced appetite in a dose-dependent manner and with a long duration of action. Consistent with the effect on appetite, studies in obese rats demonstrated that daily NN1213 dosing resulted in a dose-dependent reduction in body weight over a 21-day period. Magnetic resonance imaging indicated that this was primarily driven by loss of fat mass. Based on these data, NN1213 could be considered an attractive option for weight management in the clinical setting.

Detection of the novel HLA allele, HLA-DRB1*08:112, identified in a Danish family.

HLA-DRB1*08:112 differs from HLA-DRB1*08:01 in exon 2 at amino acid 62; asparagine to lysine substitution.

Detection of the novel HLA allele, HLA-DQA1*01:65, identified in a Danish donor.

HLA-DQA1*01:65 differs from HLA-DQA1*01:03 in exon 1 at amino acid -7 a valine to methionine substitution.

The flavanol (-)-epigallocatechin 3-gallate inhibits amyloid formation by islet amyloid polypeptide, disaggregates amyloid fibrils, and protects cultured cells against IAPP-induced toxicity.

Islet amyloid polypeptide (IAPP, amylin) is the major protein component of the islet amyloid deposits associated with type 2 diabetes. The polypeptide lacks a well-defined structure in its monomeric state but readily assembles to form amyloid. Amyloid fibrils formed from IAPP, intermediates generated in the assembly of IAPP amyloid, or both are toxic to ß-cells, suggesting that islet amyloid formation may contribute to the pathology of type 2 diabetes. There are relatively few reported inhibitors of amyloid formation by IAPP. Here we show that the tea-derived flavanol, (-)-epigallocatechin 3-gallate [(2R,3R)-5,7-dihydroxy-2-(3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3-yl 3,4,5-trihydroxybenzoate] (EGCG), is an effective inhibitor of in vitro IAPP amyloid formation and disaggregates preformed amyloid fibrils derived from IAPP. The compound is thus one of a very small set of molecules which have been shown to disaggregate IAPP amyloid fibrils. Fluorescence-detected thioflavin-T binding assays and transmission electron microscopy confirm that the compound inhibits unseeded amyloid fibril formation as well as disaggregates IAPP amyloid. Seeding studies show that the complex formed by IAPP and EGCG does not seed amyloid formation by IAPP. In this regard, the behavior of IAPP is similar to the reported interactions of Aß and α-synuclein with EGCG. Alamar blue assays and light microscopy indicate that the compound protects cultured rat INS-1 cells against IAPP-induced toxicity. Thus, EGCG offers an interesting lead structure for further development of inhibitors of IAPP amyloid formation and compounds that disaggregate IAPP amyloid.

RAGE binds preamyloid IAPP intermediates and mediates pancreatic ß cell proteotoxicity.

Islet amyloidosis is characterized by the aberrant accumulation of islet amyloid polypeptide (IAPP) in pancreatic islets, resulting in ß cell toxicity, which exacerbates type 2 diabetes and islet transplant failure. It is not fully clear how IAPP induces cellular stress or how IAPP-induced toxicity can be prevented or treated. We recently defined the properties of toxic IAPP species. Here, we have identified a receptor-mediated mechanism of islet amyloidosis-induced proteotoxicity. In human diabetic pancreas and in cellular and mouse models of islet amyloidosis, increased expression of the receptor for advanced glycation endproducts (RAGE) correlated with human IAPP-induced (h-IAPP-induced) ß cell and islet inflammation, toxicity, and apoptosis. RAGE selectively bound toxic intermediates, but not nontoxic forms of h-IAPP, including amyloid fibrils. The isolated extracellular ligand-binding domains of soluble RAGE (sRAGE) blocked both h-IAPP toxicity and amyloid formation. Inhibition of the interaction between h-IAPP and RAGE by sRAGE, RAGE-blocking antibodies, or genetic RAGE deletion protected pancreatic islets, ß cells, and smooth muscle cells from h-IAPP-induced inflammation and metabolic dysfunction. sRAGE-treated h-IAPP Tg mice were protected from amyloid deposition, loss of ß cell area, ß cell inflammation, stress, apoptosis, and glucose intolerance. These findings establish RAGE as a mediator of IAPP-induced toxicity and suggest that targeting the IAPP/RAGE axis is a potential strategy to mitigate this source of ß cell dysfunction in metabolic disease.

The EndoC-ßH1 cell line is a valid model of human beta cells and applicable for screenings to identify novel drug target candidates.

OBJECTIVE: To characterize the EndoC-ßH1 cell line as a model for human beta cells and evaluate its beta cell functionality, focusing on insulin secretion, proliferation, apoptosis and ER stress, with the objective to assess its potential as a screening platform for identification of novel anti-diabetic drug candidates. METHODS: EndoC-ßH1 was transplanted into mice for validation of in vivo functionality. Insulin secretion was evaluated in cells cultured as monolayer and as pseudoislets, as well as in diabetic mice. Cytokine induced apoptosis, glucolipotoxicity, and ER stress responses were assessed. Beta cell relevant mRNA and protein expression were investigated by qPCR and antibody staining. Hundreds of proteins or peptides were tested for their effect on insulin secretion and proliferation. RESULTS: Transplantation of EndoC-ßH1 cells restored normoglycemia in streptozotocin induced diabetic mice. Both in vitro and in vivo, we observed a clear insulin response to glucose, and, in vitro, we found a significant increase in insulin secretion from EndoC-ßH1 pseudoislets compared to monolayer cultures for both glucose and incretins. Apoptosis and ER stress were inducible in the cells and caspase 3/7 activity was elevated in response to cytokines, but not affected by the saturated fatty acid palmitate. By screening of various proteins and peptides, we found Bombesin (BB) receptor agonists and Pituitary Adenylate Cyclase-Activating Polypeptides (PACAP) to significantly induce insulin secretion and the proteins SerpinA6, STC1, and APOH to significantly stimulate proliferation. ER stress was readily induced by Tunicamycin and resulted in a reduction of insulin mRNA. Somatostatin (SST) was found to be expressed by 1% of the cells and manipulation of the SST receptors was found to significantly affect insulin secretion. CONCLUSIONS: Overall, the EndoC-ßH1 cells strongly resemble human islet beta cells in terms of glucose and incretin stimulated insulin secretion capabilities. The cell line has an active cytokine induced caspase 3/7 apoptotic pathway and is responsive to ER stress initiation factors. The cells' ability to proliferate can be further increased by already known compounds as well as by novel peptides and proteins. Based on its robust performance during the functionality assessment assays, the EndoC-ßH1 cell line was successfully used as a screening platform for identification of novel anti-diabetic drug candidates.

The X-linked inhibitor of apoptosis protein enhances survival of murine islet allografts.

Allotransplantation of pancreatic islets represents a promising approach to treat type 1 diabetes. Destruction of beta-cells in islet allografts involves multiple immune mechanisms that lead to activation of caspases and apoptotic cell death. The X-linked inhibitor of apoptosis (XIAP) inhibits apoptosis induced by a variety of triggers, primarily by preventing the activation of caspases. To determine whether XIAP would protect beta-cells from apoptosis, we used a recombinant adenovirus to overexpress XIAP in transformed murine beta-cells and in freshly isolated islets. In vitro cytokine-induced beta-cell death was decreased to baseline levels in XIAP-transduced MIN-6 and NIT-1 cell lines compared with controls. To evaluate the potential of XIAP overexpression to prevent in vivo allogeneic graft rejection, we transduced Balb/c islets ex vivo with XIAP before transplantation into CBA mice with streptozotocin-induced diabetes. We observed that almost all mice receiving allografts of XIAP-expressing islets maintained normoglycemia until the experiment was terminated (45-72 days posttransplant), whereas control mice receiving islets transduced with adenovirus expressing LacZ were hyperglycemic by approximately 17 days posttransplantation due to graft rejection. Immunohistochemistry revealed preservation of beta-cells and clearance of infiltrating immune cells in the XIAP-expressing islet grafts. The in vitro allogeneic response of splenocytes isolated from recipients of XIAP-expressing grafts 8 weeks posttransplant was similar to that seen in nonprimed allogeneic mice, suggesting that XIAP overexpression may lead to the acceptance of islet allografts in diabetic recipients. Long-term protection of islet allografts by XIAP overexpression may enhance the survival of islet transplants in diabetes.

Time-resolved studies define the nature of toxic IAPP intermediates, providing insight for anti-amyloidosis therapeutics.

Islet amyloidosis by IAPP contributes to pancreatic ß-cell death in diabetes, but the nature of toxic IAPP species remains elusive. Using concurrent time-resolved biophysical and biological measurements, we define the toxic species produced during IAPP amyloid formation and link their properties to induction of rat INS-1 ß-cell and murine islet toxicity. These globally flexible, low order oligomers upregulate pro-inflammatory markers and induce reactive oxygen species. They do not bind 1-anilnonaphthalene-8-sulphonic acid and lack extensive ß-sheet structure. Aromatic interactions modulate, but are not required for toxicity. Not all IAPP oligomers are toxic; toxicity depends on their partially structured conformational states. Some anti-amyloid agents paradoxically prolong cytotoxicity by prolonging the lifetime of the toxic species. The data highlight the distinguishing properties of toxic IAPP oligomers and the common features that they share with toxic species reported for other amyloidogenic polypeptides, providing information for rational drug design to treat IAPP induced ß-cell death.

Synergistic inhibition of tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in human pancreatic beta cells by Bcl-2 and X-linked inhibitor of apoptosis.

To better understand the cytokine death-signal transduction pathways in human beta cells, we investigated the inhibitory effects of Bcl-2 (protooncogene bcl-2) and X-linked inhibitor of apoptosis (XIAP) on TRAIL (TNF-related apoptosis-inducing ligand)-induced human beta-cell destruction. A panel of Bcl-2-overexpressing transfectants of the human beta-cell lines NES2Y and CM was developed by transfection with a pEFpGKpuro vector containing Bcl-2 or an empty vector as a control. TRAIL-induced cytotoxicity and apoptosis of Bcl-2-overexpressing beta cells were clearly decreased, in comparison with wild-type cells and the empty vector transfectants. XIAP-overexpressing CM, NES2Y, and primary islet cells were generated by exposing cells to recombinant adenovirus-expressing XIAP (AdXIAP) or AdLacz as a control. TRAIL-induced cytotoxicity and apoptosis of CM, NES2Y, and primary islet cells infected with AdXIAP were clearly reduced compared with controls. Interestingly, cytotoxicity induced by TRAIL in human beta cells transfected with both Bcl-2 and AdXIAP was much less than that observed in human beta cells transfected with either Bcl-2 or XIAP alone (p < 0.005 in CM and p < 0.03 in NES2Y). Overexpression of both Bcl-2 and XIAP inhibited TRAIL-induced activation of caspases as well as TRAIL-mediated damage of mitochondrial function in cells, suggesting possible regulatory mechanisms. These results indicate that Bcl-2 and XIAP synergistically inhibit TRAIL-mediated death pathways in human beta cells.

Increasing the yield of human mononuclear cells and low serum conditions for in vitro generation of macrophages with M-CSF.

The yield of mononuclear cells extracted from peripheral blood using standard protocols is frequently inadequate when working with material of limited availability. In addition, the regular usage of autologous and fetal calf serum (FCS) to generate human macrophages in vitro may complicate antigen uptake, processing and presentation on HLA molecules. We optimized the yield of mononuclear cells from 34+/-3% to 65+/-5% by collecting both the interface and more than half of the overlayering supernatant, followed by three washes at 4 degrees C. Monocytes from 12 individuals were cultured 1-4 days with 0-100 ng/ml macrophage colony-stimulating factor (M-CSF) at either 1% (low) or 5% (v/v) FCS. Regardless of number of days in culture, maximal (50-100 ng/ml) M-CSF stimulation and low FCS induced 65+/-5% esterase-positive cells in all individuals compared to 52+/-7% without M-CSF (p<0.001). M-CSF increased the mean proportion of esterase-positive cells in both 1% and 5% FCS with a negative interaction found between 5% FCS and M-CSF (p<0.05). All cells were positive for CD14 and HLA class II but cell number did not increase. The generation of human macrophages by M-CSF at low FCS should prove useful in studies where higher FCS concentrations may interfere with the assay.

Islet remodeling in female mice with spontaneous autoimmune and streptozotocin-induced diabetes.

Islet alpha- and delta-cells are spared autoimmune destruction directed at beta-cells in type 1 diabetes resulting in an apparent increase of non-beta endocrine cells in the islet core. We determined how islet remodeling in autoimmune diabetes compares to streptozotocin (STZ)-induced diabetes. Islet cell mass, proliferation, and immune cell infiltration in pancreas sections from diabetic NOD mice and mice with STZ-induced diabetes was assessed using quantitative image analysis. Serial sections were stained for various beta-cell markers and Ngn3, typically restricted to embryonic tissue, was only upregulated in diabetic NOD mouse islets. Serum levels of insulin, glucagon and GLP-1 were measured to compare hormone levels with respect to disease state. Total pancreatic alpha-cell mass did not change as autoimmune diabetes developed in NOD mice despite the proportion of islet area comprised of alpha- and delta-cells increased. By contrast, alpha- and delta-cell mass was increased in mice with STZ-induced diabetes. Serum levels of glucagon reflected these changes in alpha-cell mass: glucagon levels remained constant in NOD mice over time but increased significantly in STZ-induced diabetes. Increased serum GLP-1 levels were found in both models of diabetes, likely due to alpha-cell expression of prohormone convertase 1/3. Alpha- or delta-cell mass in STZ-diabetic mice did not normalize by replacement of insulin via osmotic mini-pumps or islet transplantation. Hence, the inflammatory milieu in NOD mouse islets may restrict alpha-cell expansion highlighting important differences between these two diabetes models and raising the possibility that increased alpha-cell mass might contribute to the hyperglycemia observed in the STZ model.

Advances and challenges in islet transplantation: islet procurement rates and lessons learned from suboptimal islet transplantation.

The initial step in successful islet transplantation is procurement of healthy donor islets. Given the limited number of donor pancreata selected for islet isolation and that islets from multiple donors are typically required to obtain insulin independence, it is critical to improve pancreas procurement rates and yield of islets for transplantation. Islets are delicate microorgans that are susceptible to apoptosis, hypoxia, and ischemia during isolation, culture, and the peritransplant period. Once the islets are engrafted, both prompt revascularization and protection from beta-cell death and graft rejection are key to secure long-term survival and function. To facilitate the engraftment of more robust islets suitable for combating the challenging isolation period and proinflammatory transplantation milieu, numerous approaches have been employed to prevent beta-cell dysfunction and death including immune modulation, prevention of apoptosis and hypoxia, as well as stimulation of growth factors, angiogenesis, and reinnervation. In addition to briefly discussing islet isolation procedures, procurement rates, and islet transplantation, the relevant literature pertaining to successful suboptimal islet transplantation is reviewed to provide insight into potential approaches to balance the limited supply of available donor islets.

XIAP inhibition of ß-cell apoptosis reduces the number of islets required to restore euglycemia in a syngeneic islet transplantation model.

Clinical pancreatic islet transplantation has great promise as a treatment for type 1 diabetes but despite recent advances, it is still limited by the need for lifelong immunosuppression, restricted availability of donor islets, and uncertainty regarding long-term graft survival. Using a syngeneic, suboptimal islet transplantation model, we asked whether adenoviral overexpression of an anti-apoptotic protein, the X-linked inhibitor of apoptosis protein (XIAP) would protect transplanted islet cells from death and reduce the number of islets required for successful transplantation. Transplantation of 100 XIAP-expressing islets into the kidney capsule of syngeneic Balb/c mice restored euglycemia in 86% of recipients, where transplantation of 100 islets transduced with a control adenovirus expressing LacZ restored euglycemia in only 27% of recipients. Analysis of islet grafts by insulin/TUNEL double immunostaining revealed fewer apoptotic beta-cells in recipients of XIAP- compared with LacZ-expressing grafts (0.8±0.5 vs. 2.4±0.8 double-positive cells/graft), suggesting that XIAP enhances graft success by inhibiting ß-cell apoptosis in the immediate post-transplant period. In summary, XIAP overexpression inhibits beta cell apoptosis in syngeneic islet transplants, thereby reducing the number of islets and decreasing the number of days required to restore euglycemia. These data raise the possibility that ex vivo XIAP gene transfer in islets prior to transplantation has the potential to increase the number of donor islets available for transplantation and may enhance graft function and long-term transplant success.

The sulfated triphenyl methane derivative acid fuchsin is a potent inhibitor of amyloid formation by human islet amyloid polypeptide and protects against the toxic effects of amyloid formation.

Islet amyloid polypeptide (IAPP), also known as amylin, is responsible for amyloid formation in type 2 diabetes. The formation of islet amyloid is believed to contribute to the pathology of the disease by killing beta-cells, and it may also contribute to islet transplant failure. The design of inhibitors of amyloid formation is an active area of research, but comparatively little attention has been paid to inhibitors of IAPP in contrast to the large body of work on beta-amyloid, and most small-molecule inhibitors of IAPP amyloid are generally effective only when used at a significant molar excess. Here we show that the simple sulfonated triphenyl methane derivative acid fuchsin, 3-(1-(4-amino-3-methyl-5-sulfonatophenyl)-1-(4-amino-3-sulfonatophenyl) methylene) cyclohexa-1,4-dienesulfonic acid, is a potent inhibitor of in vitro amyloid formation by IAPP at substoichiometric levels and protects cultured rat INS-1 cells against the toxic effects of human IAPP. Fluorescence-detected thioflavin-T binding assays, light-scattering, circular dichroism, two-dimensional IR, and transmission electron microscopy measurements confirm that the compound prevents amyloid fibril formation. Ionic-strength-dependent studies show that the effects are mediated in part by electrostatic interactions. Experiments in which the compound is added at different time points during the lag phase after amyloid formation has commenced reveal that it arrests amyloid formation by trapping intermediate species. The compound is less effective against the beta-amyloid peptide, indicating specificity in its ability to inhibit amyloid formation by IAPP. The work reported here provides a new structural class of IAPP amyloid inhibitors and demonstrates the power of two-dimensional infrared spectroscopy for characterizing amyloid inhibitor interactions.

Differentiation of mouse embryonic stem cells into endoderm without embryoid body formation.

Pluripotent embryonic stem cells hold a great promise as an unlimited source of tissue for treatment of chronic diseases such as Type 1 diabetes. Herein, we describe a protocol using all-trans-retinoic acid, basic fibroblast growth factor and dibutyryl cAMP (DBcAMP) in the absence of embryoid body formation, for differentiation of murine embryonic stem cells into definitive endoderm that may serve as pancreatic precursors. The produced cells were analyzed by quantitative PCR, immunohistochemistry and static insulin release assay for markers of trilaminar embryo, and pancreas. Differentiated cells displayed increased Sox17 and Foxa2 expression consistent with definitive endoderm production. There was minimal production of Sox7, an extraembryonic endoderm marker, and Oct4, a marker of pluripotency. There was minimal mesoderm or neuroectoderm formation based on expression levels of the markers brachyury and Sox1, respectively. Various assays revealed that the cell clusters generated by this protocol express markers of the pancreatic lineage including insulin I, insulin II, C-peptide, PDX-1, carboxypeptidase E, pan-cytokeratin, amylase, glucagon, PAX6, Ngn3 and Nkx6.1. This protocol using all-trans-retinoic acid, DBcAMP, in the absence of embryoid bodies, generated cells that have features of definitive endoderm that may serve as pancreatic endocrine precursors.

Islet allograft rejection is independent of toll-like receptor signaling in mice.

BACKGROUND: Islet transplantation is a promising therapy for type 1 diabetes; however, most islet grafts fail within 5 years. Innate immunity has been suggested to play a role in islet allograft rejection, potentially mediated by toll-like receptors (TLRs), a class of innate immune receptors. Lack of TLR4, in particular, has been reported to improve allograft survival. Therefore, we hypothesized that TLRs may be involved in islet allograft rejection, and that deletion of TLR4 may improve islet graft survival. METHODS: Islets were isolated from C57BL/10ScNJ (Tlr4(-/-)) and C57BL/10 (wild-type [WT]) animals and transplanted into Balb/cJ recipients with streptozotocin-induced diabetes. Blood glucose levels were used to determine graft viability and immunostaining to assess graft morphology and immune cell infiltration. The roles of the TLR4 adaptor molecules MyD88 and TLR adaptor molecule 1 (Ticam-1) were assessed using islets isolated from mice lacking MyD88 (MyD88(-/-)), Ticam-1 (Ticam-1(-/-)), or the combined double knockout (MyD88(-/-)/Ticam-1(-/-)). RESULTS: Contrary to our hypothesis, Tlr4(-/-) and WT islet allografts had similar failure rates; grafts failed at 23.2+/-1.2 and 24.5+/-1.5 days posttransplant, respectively (P=NS). Syngeneic grafts of Tlr4(-/-) and WT islets maintained normoglycemia for up to 10 weeks posttransplant, indicating that failure of Tlr4(-/-) islet allografts could not be attributed to an intrinsic defect in Tlr4(-/-) islets. Similarly, islet allotransplants from MyD88(-/-), Ticam-1(-/-), and MyD88(-/-)/Ticam-1(-/-) donors did not have improved allograft survival compared with WT controls. CONCLUSIONS: These findings indicate that islet allograft rejection in mice is independent of TLR4 and the TLR adaptor molecules MyD88 and Ticam-1, speaking against an essential role for TLR signaling in islet allograft rejection.