Desmoglein-2 is Important for Islet Function and β-Cell Survival

Type 1 diabetes is a complex disease characterized by the lack of endogenous insulin secreted from the pancreatic β-cells. Although β-cell targeted autoimmune processes and β-cell dysfunction are known to occur in type 1 diabetes, a complete understanding of the cell-to-cell interactions that support pancreatic function is still lacking. To characterize the pancreatic endocrine compartment, we studied pancreata from healthy adult donors and investigated a single cell surface adhesion molecule, desmoglein-2 (DSG2). Genetically-modified mice lacking Dsg2 were examined for islet cell mass, insulin production, responses to glucose, susceptibility to a streptozotocin-induced mouse model of hyperglycaemia, and ability to cure diabetes in a syngeneic transplantation model. Herein, we have identified DSG2 as a previously unrecognized adhesion molecule that supports β-cells. Furthermore, we reveal that DSG2 is within the top 10 percent of all genes expressed by human pancreatic islets and is expressed by the insulin-producing β-cells but not the somatostatin-producing δ-cells. In a Dsg2 loss-of-function mice (Dsg

A Combinatorial Protein Microarray for Probing Materials Interaction with Pancreatic Islet Cell Populations

Pancreatic islet transplantation has become a recognized therapy for insulin-dependent diabetes mellitus. During isolation from pancreatic tissue, the islet microenvironment is disrupted. The extracellular matrix (ECM) within this space not only provides structural support, but also actively signals to regulate islet survival and function. In addition, the ECM is responsible for growth factor presentation and sequestration. By designing biomaterials that recapture elements of the native islet environment, losses in islet function and number can potentially be reduced. Cell microarrays are a high throughput screening tool able to recreate a multitude of cellular niches on a single chip. Here, we present a screening methodology for identifying components that might promote islet survival. Automated fluorescence microscopy is used to rapidly identify islet derived cell interaction with ECM proteins and immobilized growth factors printed on arrays. MIN6 mouse insulinoma cells, mouse islets and, finally, human islets are progressively screened. We demonstrate the capability of the platform to identify ECM and growth factor protein candidates that support islet viability and function and reveal synergies in cell response

Desmoglein-2 is important for islet function and β-cell survival

Type 1 diabetes is a complex disease characterized by the lack of endogenous insulin secreted from the pancreatic β-cells. Although β-cell targeted autoimmune processes and β-cell dysfunction are known to occur in type 1 diabetes, a complete understanding of the cell-to-cell interactions that support pancreatic function is still lacking. To characterize the pancreatic endocrine compartment, we studied pancreata from healthy adult donors and investigated a single cell surface adhesion molecule, desmoglein-2 (DSG2). Genetically-modified mice lacking Dsg2 were examined for islet cell mass, insulin production, responses to glucose, susceptibility to a streptozotocin-induced mouse model of hyperglycaemia, and ability to cure diabetes in a syngeneic transplantation model. Herein, we have identified DSG2 as a previously unrecognized adhesion molecule that supports β-cells. Furthermore, we reveal that DSG2 is within the top 10 percent of all genes expressed by human pancreatic islets and is expressed by the insulin-producing β-cells but not the somatostatin-producing δ-cells. In a Dsg2 loss-of-function mice (Dsg2lo/lo), we observed a significant reduction in the number of pancreatic islets and islet size, and consequently, there was less total insulin content per islet cluster. Dsg2lo/lo mice also exhibited a reduction in blood vessel barrier integrity, an increased incidence of streptozotocin-induced diabetes, and islets isolated from Dsg2lo/lo mice were more susceptible to cytokine-induced β-cell apoptosis. Following transplantation into diabetic mice, islets isolated from Dsg2lo/lo mice were less effective than their wildtype counterparts at curing diabetes. In vitro assays using the Beta-TC-6 murine β-cell line suggest that DSG2 supports the actin cytoskeleton as well as the release of cytokines and chemokines. Taken together, our study suggests that DSG2 is an under-appreciated regulator of β-cell function in pancreatic islets and that a better understanding of this adhesion molecule may provide new opportunities to combat type 1 diabetes

Murine and Non-Human Primate Dendritic Cell Targeting Nanoparticles for <i>in Vivo</i> Generation of Regulatory T‑Cells

Porous silicon nanoparticles (pSiNP), modified to target dendritic cells (DC), provide an alternate strategy for the delivery of immunosuppressive drugs. Here, we aimed to develop a DC-targeting pSiNP displaying c-type lectin, dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), and CD11c monoclonal antibodies. The <i>in vivo</i> tracking of these fluorescent DC-targeting nanoparticles was assessed in both C57BL/6 mice and common marmosets (<i>Callithrix jacchus</i>) by intravenous injection (20 mg/kg). Rapamycin and ovalbumin (OVA)_323–339 peptide loaded pSiNP were employed to evaluate their ability to generate murine CD4⁺CD25⁺FoxP3⁺ regulatory T-cells <i>in vivo</i> within OVA sensitized mice. <i>In vivo,</i> pSiNP migrated to the liver, kidneys, lungs, and spleen in both mice and marmosets. Flow cytometry confirmed pSiNP uptake by splenic and peripheral blood DC when functionalized with targeting antibodies. C57BL/6 OVA sensitized mice injected with CD11c-pSiNP loaded with rapamycin + OVA_323–339 produced a 5-fold higher number of splenic regulatory T-cells compared to control mice, at 40 days post-pSiNP injection. These results demonstrate the importance of the immobilized targeting antibodies to enhance cellular uptake and enable the <i>in vivo</i> generation of splenic regulatory T-cells

Phenoxodiol, an experimental anticancer drug, shows potent antiangiogenic properties in addition to its antitumour effects

Phenoxodiol (2H-1-benzopyran-7-0,1, 3-[4-hydroxyphenyl], PXD) is a synthetic analogue of the naturally-occurring plant isoflavone and anticancer agent, genistein. PXD directly induces mitotic arrest and apoptosis in most cancer cells and is currently undergoing clinical trials, as a chemotherapeutic in ovarian and prostate cancers. We show here that PXD also exhibits potent antiangiogenic properties. Thus, it inhibited endothelial cell proliferation, migration and capillary tube formation and inhibited expression of the matrix metalloproteinase MMP-2, a major matrix degrading enzyme. Importantly, we demonstrate that PXD is functional in vivo since it inhibited the extent of capillary tube invasion in an in vivo model of angiogenesis. We show that phenoxodiol inhibits hallmarks of endothelial cell activation, namely TNF or IL-1 induced E-selectin and VCAM-1 expression and IL-8 secretion. However, PXD had no effect on unstimulated endothelial cells. We also describe that PXD inhibits the lipid kinase sphingosine kinase, which recently has been implicated in endothelial cell activation and angiogenesis as well as oncogenesis. Thus, our results suggest that PXD may be an effective anticancer drug targeting the two drivers of tumour growth--the proliferation of the tumour cells themselves and the angiogenic and inflammatory stimulation of the vasculature.Gamble, Jennifer R. ; Xia, Pu ; Hahn, Christopher N. ; Drew, Jenny J. ; Drogemuller, Christopher J. ; Brown, David ; Vadas, Mathew A

Manipulating human dendritic cell phenotype and function with targeted porous silicon nanoparticles

Dendritic cells (DC) are the most potent antigen-presenting cells and are fundamental for the establishment of transplant tolerance. The Dendritic Cell-Specific Intracellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN; CD209) receptor provides a target for dendritic cell therapy. Biodegradable and high-surface area porous silicon (pSi) nanoparticles displaying anti-DC-SIGN antibodies and loaded with the immunosuppressant rapamycin (Sirolimus) serve as a fit-for-purpose platform to target and modify DC. Here, we describe the fabrication of rapamycin-loaded DC-SIGN displaying pSi nanoparticles, the uptake efficiency into DC and the extent of nanoparticle-induced modulation of phenotype and function. DC-SIGN antibody displaying pSi nanoparticles favourably targeted and were phagocytosed by monocyte-derived and myeloid DC in whole human blood in a time- and dose-dependent manner. DC preconditioning with rapamycin-loaded nanoparticles, resulted in a maturation resistant phenotype and significantly suppressed allogeneic T-cell proliferation.Sebastian O. Stead, Steven J.P. McInnes, Svjetlana Kireta, Peter D. Rose, Shilpanjali Jesudason, Darling Rojas-Canales, David Warther, Frédérique Cunin, Jean-Olivier Durand, Christopher J. Drogemuller, Robert P. Carroll, P. Toby Coates, Nicolas H. Voelcke