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Beta-cell dysfunction is a hallmark of disease progression in patients with diabetes. Research have been focused on maintaining and restoring beta-cell function during diabetes development. The aims of this study were to explore the expression of C-type lectin domain containing 11A (CLEC11A), a secreted sulfated glycoprotein, in human islets, and to evaluate the effects of CLEC11A on beta-cell function and proliferation in vitro. To test these hypotheses, human islets and human EndoC-βH1 cell line were used in this study. We identified that CLEC11A was expressed in beta-cells and alpha-cells in human islets but not in EndoC-βH1 cells; whereas the receptor of CLEC11A called integrin subunit alpha 11 (ITGA11), was found in both human islets and EndoC-βH1 cells. Long-term treatment with exogenous recombinant human CLEC11A (rhCLEC11A) accentuated glucose stimulated insulin secretion, insulin content and proliferation from human islets and EndoC-βH1 cells, which was partially due to the accentuated expression levels of transcription factors MAFA and PDX1. However, the impaired beta-cell function and reduced mRNA expression of INS and MAFA in EndoC-βH1 cells that was caused by chronic palmitate exposure, could only be partially improved by the introduction of rhCLEC11A. Based on these results, we conclude that rhCLEC11A promotes insulin secretion, insulin content and proliferation in human beta-cells, which are associated with the accentuated expression levels of transcription factors MAFA and PDX1. CLEC11A, therefore, may provide a novel therapeutic target for maintaining beta-cell function in patients with diabetes.

The anti-inflammatory role of regulatory B cells (Breg cells) has been associated with IL-35 based on studies of experimental autoimmune uveitis and encephalitis. The role of Breg cells and IL-35+ Breg cells for type 1 diabetes (T1D) remains to be investigated. We studied PBMCs from T1D subjects and healthy controls (HC) and found lowered proportions of Breg cells and IL-35+ Breg cells in T1D. To elucidate the role of Breg cells, the lymphoid organs of two mouse models of T1D were examined. Lower proportions of Breg cells and IL-35+ Breg cells were found in the animal models of T1D compared with control mice. In addition, the systemic administration of recombinant mouse IL-35 prevented hyperglycemia after multiple low dose streptozotocin (MLDSTZ) injections and increased the proportions of Breg cells and IL-35+ Breg cells. A higher proportion of IFN-γ+ cells among Breg cells were found in the PBMCs of the T1D subjects. In the MLDSTZ mice, IL-35 administration decreased the proportions of IFN-γ+ cells among the Breg cells. Our data illustrate that Breg cells may play an important role in the development of T1D and that IL-35 treatment prevents the development of hyperglycemia by maintaining the phenotype of the Breg cells under an experimental T1D condition.

The anti-inflammatory role of regulatory B cells (Breg cells) has been associated with IL-35 based on studies of experimental autoimmune uveitis and encephalitis. The role of Breg cells and IL-35(+) Breg cells for type 1 diabetes (T1D) remains to be investigated. We studied PBMCs from T1D subjects and healthy controls (HC) and found lowered proportions of Breg cells and IL-35(+) Breg cells in T1D. To elucidate the role of Breg cells, the lymphoid organs of two mouse models of T1D were examined. Lower proportions of Breg cells and IL-35(+) Breg cells were found in the animal models of T1D compared with control mice. In addition, the systemic administration of recombinant mouse IL-35 prevented hyperglycemia after multiple low dose streptozotocin (MLDSTZ) injections and increased the proportions of Breg cells and IL-35(+) Breg cells. A higher proportion of IFN-gamma(+) cells among Breg cells were found in the PBMCs of the T1D subjects. In the MLDSTZ mice, IL-35 administration decreased the proportions of IFN-gamma(+) cells among the Breg cells. Our data illustrate that Breg cells may play an important role in the development of T1D and that IL-35 treatment prevents the development of hyperglycemia by maintaining the phenotype of the Breg cells under an experimental T1D condition. De två sista författarna delar sistaförfattarskapet.

Gliomas are brain tumors characterized by an immunosuppressive microenvironment. Immunostimulatory agonistic CD40 antibodies (αCD40) are in clinical development for solid tumors, but are yet to be evaluated for glioma. Here, we demonstrate that systemic delivery of αCD40 in preclinical glioma models induces the formation of tertiary lymphoid structures (TLS) in proximity of meningeal tissue. In treatment-naïve glioma patients, the presence of TLS correlates with increased T cell infiltration. However, systemic delivery of αCD40 induces hypofunctional T cells and impairs the response to immune checkpoint inhibitors in pre-clinical glioma models. This is associated with a systemic induction of suppressive CD11b+ B cells post-αCD40 treatment, which accumulate in the tumor microenvironment. Our work unveils the pleiotropic effects of αCD40 therapy in glioma and reveals that immunotherapies can modulate TLS formation in the brain, opening up for future opportunities to regulate the immune response., Agonistic CD40 antibodies (αCD40) have broad immunostimulatory properties, however their efficacy in glioma remains unclear. Here the authors show that αCD40 promotes the formation of tertiary lymphoid structures but does not improve survival and impairs the response to immune checkpoint blockade in murine glioma models.

Transplantation of pancreatic islet cells derived from human pluripotent stem cells is a promising treatment for diabetes. Despite progress in stem cell-derived islet (SC-islet) generation, detailed characterization of their functional properties has not been conducted. Here, we generated functionally mature SC-islets using an optimized protocol and comprehensively benchmarked them against primary adult islets. Biphasic glucose stimulated insulin secretion developed during in vitro maturation, associated with cytoarchitectural reorganization and increased alpha cells. Electrophysiology and exocytosis of SC-islets were comparable to adult islets. Glucose-responsive insulin secretion was achieved despite differences in glycolytic and mitochondrial glucose metabolism. Single-cell transcriptomics of SC-islets in vitro and throughout 6 months of murine engraftment revealed a continuous maturation trajectory culminating in a transcriptional landscape closely resembling that of primary islets. Our thorough evaluation of SC-islet maturation highlights their advanced degree of functionality and supports their use in further efforts to understand and combat diabetes.

Gliomas are brain tumors characterized by immunosuppression. Immunostimulatory agonistic CD40 antibodies (αCD40) are in clinical development for solid tumors but are yet to be evaluated for glioma. Here, systemic delivery of αCD40 led to cytotoxic T cell dysfunction and impaired the response to immune checkpoint inhibitors in preclinical glioma models. This was associated with an accumulation of suppressive CD11b+ B cells. However, αCD40 also induced tertiary lymphoid structures (TLS). In human glioma, TLS correlated with increased T cell infiltration indicating enhanced immune responses. Our work unveils the pleiotropic effects of αCD40 therapy in glioma, which is of high clinical relevance.

Availability of numerous high-quality iPSC lines is needed to overcome donor-associated variability caused by genetic background effects. We generated two human iPSC lines from dermal fibroblasts of two healthy females using Sendai virus reprogramming. Quality assessment of the iPSC lines confirmed the expression of pluripotency markers, trilineage differentiation capacity and absence of exogenous expression of reprogramming factors. Both iPSC lines were genetically stable with a genotype that matched the fibroblast lines of donors. These iPSC lines add to available reference lines as a resource for disease modeling of polygenic and multifactorial diseases, for evaluation of differentiation protocols and toxicology screening. Svitlana Vasylovska and Jens Schuster contributed equally to the study.

We assessed glucose uptake in different tissues in type 2 diabetes (T2D), prediabetes, and control subjects to elucidate its impact in the development of whole-body insulin resistance and T2D. Thirteen T2D, 12 prediabetes, and 10 control subjects, matched for age and BMI, underwent OGTT and abdominal subcutaneous adipose tissue (SAT) biopsies. Integrated whole-body 18F-FDG PET and MRI were performed during a hyperinsulinemic euglycemic clamp to asses glucose uptake rate (MRglu) in several tissues. MRglu in skeletal muscle, SAT, visceral adipose tissue (VAT), and liver was significantly reduced in T2D subjects and correlated positively with M-values (r=0.884, r=0.574, r=0.707 and r=0.403, respectively). Brain MRglu was significantly higher in T2D and prediabetes subjects and had a significant inverse correlation with M-values (r=–0.616). Myocardial MRglu did not differ between groups and did not correlate with the M-values. A multivariate model including skeletal muscle, brain and VAT MRglu best predicted the M-values (adjusted r2=0.85). In addition, SAT MRglu correlated with SAT glucose uptake ex vivo (r=0.491). In different stages of the development of T2D, glucose uptake during hyperinsulinemia is elevated in the brain in parallel with an impairment in peripheral organs. Impaired glucose uptake in skeletal muscle and VAT together with elevated glucose uptake in brain were independently associated with whole-body insulin resistance, and these tissue-specific alterations may contribute to T2D development.

Introduction The sodium-glucose cotransporter 2 inhibitor dapagliflozin and the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide reduce bodyweight via differing and complementary mechanisms. This post hoc analysis investigated the metabolic effects and baseline associations with bodyweight loss on coadministration of dapagliflozin and exenatide once weekly (QW) among adults with obesity and without diabetes. Methods In the primary trial, adults with obesity and without diabetes [n = 50; 18–70 years; body mass index (BMI) 30–45 kg/m2] were randomized to double-blind oral dapagliflozin 10 mg (DAPA) once daily plus subcutaneous long-acting exenatide 2 mg QW (ExQW) or placebo over 24 weeks, followed by an open-label extension from 24–52 weeks during which all participants received active treatment. Primary results have been published previously. This analysis evaluated: (1) the effects of DAPA + ExQW on changes in substrates [free fatty acids (FFAs), glycerol, beta-OH-butyrate, and glucose], hormones (glucagon and insulin), and insulin secretion [insulinogenic index (IGI)] via an oral glucose tolerance test (OGTT) and (2) associations between bodyweight loss and baseline characteristics (e.g., BMI), single-nucleotide polymorphisms (SNPs) associated with the GLP-1 pathway, and markers of glucose regulation. Results Compared with placebo at 24 weeks, 2-h FFAs post-OGTT increased (mean difference, +20.4 μmol/l; P < 0.05), and fasting glucose, 2-h glucose post-OGTT, and glucose area under the concentration-time curve (AUC) decreased with DAPA + ExQW [mean differences, −0.68 mmol/l [P < 0.001], −2.20 mmol/l (P < 0.01), and −306 mmol/l min (P < 0.001), respectively]. Glucagon, glycerol, beta-OH-butyrate, and IGI did not differ by treatment group at 24 weeks. Over 52 weeks, DAPA + ExQW decreased fasting insulin, 2-h post-OGTT insulin, and insulin AUC. Among DAPA + ExQW-treated participants, for each copy of the SNP variant rs10010131 A allele (gene WFS1), bodyweight decreased by 2.4 kg (P < 0.05). Lower BMI and a lower IGI were also associated with greater bodyweight loss with DAPA + ExQW. Conclusions Metabolic effects with DAPA + ExQW included less FFA suppression versus placebo during the OGTT, suggesting compensatory lipid mobilization for energy production when glucose availability was reduced because of glucosuria. The expected increase in glucagon with DAPA did not occur with DAPA + ExQW coadministration. Bodyweight loss with DAPA + ExQW was associated with the SNP variant rs10010131 A allele, lower baseline adiposity (BMI), and lower baseline insulin secretion (IGI). These findings require further validation. Funding AstraZeneca Electronic supplementary material The online version of this article (10.1007/s13300-018-0449-6) contains supplementary material, which is available to authorized users.

Insulin-producing cells derived from human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs) have for long been a promising, but elusive treatment far from clinical translation into type 1 diabetes therapy. However, the field is now on the verge of moving such insulin-producing cells into clinical trials. Although stem cell therapies provide great opportunities, there are also potential risks such as teratoma formation associated with the treatment. Many considerations are needed on how to proceed with clinical translation, including whether to use hESCs or iPSCs, and whether encapsulation of tissue will be needed. This review aims to give an overview of the current knowledge of stem cell therapy outcomes in animal models of type 1 diabetes and a proposed road map towards the clinical setting with special focus on the potential risks and hurdles which needs to be considered. From a clinical point of view, transplantation of insulin-producing cells derived from stem cells must be performed without immune suppression in order to be an attractive treatment option. Although costly and highly labour intensive, patient-derived iPSCs would be the only solution, if not clinically successful encapsulation or tolerance induction protocols are introduced.

Background: Murine boundary cap-derived neural crest stem cells (NCSCs) are capable of enhancing islet function by stimulating beta cell proliferation as well as increasing the neural and vascular density in the islets both in vitro and in vivo. This study aimed to isolate NCSC-like cells from human bone marrow. Methods: CD271 magnetic cell separation and culture techniques were used to purify a NCSC-enriched population of human bone marrow. Analyses of the CD271+ and CD271- fractions in terms of protein expression were performed, and the capacity of the CD271+ bone marrow cells to form 3-dimensional spheres when grown under non-adherent conditions was also investigated. Moreover, the NCSC characteristics of the CD271+ cells were evaluated by their ability to migrate toward human islets as well as human islet-like cell clusters (ICC) derived from pluripotent stem cells. Results: The CD271+ bone marrow population fulfilled the criterion of being multipotent stem cells, having the potential to differentiate into glial cells, neurons as well as myofibroblasts in vitro. They had the capacity to form 3-dimensional spheres as well as an ability to migrate toward human islets, further supporting their NCSC identity. Additionally, we demonstrated similar migration features toward stem cell-derived ICC. Conclusion: The results support the NCSC identity of the CD271-enriched human bone marrow population. It remains to investigate whether the human bone marrow-derived NCSCs have the ability to improve transplantation efficacy of not only human islets but stem cell-derived ICC as well.

The lipotoxicity is considered as one of the risk for diabetes. Here we report C-type lectin domain family 11, member A (Clec11a) as a new regulator in islet playing a protective role in lipotoxicity induced dysfunction. Islet transcriptome sequencing was performed using the high-fat diet induced obesity (DIO) mice model. We found a significant decrease of Clec11a expression in islets of DIO mice compared to normal control mice, which was further confirmed by real-time PCR. Immunostaining demonstrated the localization of the Clec11a protein in mouse islets. Administration of recombinant human Clec11a (rClec11a) protein promoted the proliferation of islet cells and rescued the inhibition of fatty acid on cell proliferation, which involved the activation of Erk signaling pathway. We also found that the rClec11a altered the expression of genes involved in lipid metabolism.

Low-oxygenated and dormant islets with a capacity to become activated when needed may play a crucial role in the complex machinery behind glucose homeostasis. We hypothesized that low-oxygenated islets, when not functionally challenged, do not rapidly cycle between activation and inactivation but are a stable population that remain low-oxygenated. As this was confirmed, we aimed to characterize these islets with regard to cell composition, vascular density, and endocrine cell proliferation. The 2-nitroimidazole low-oxygenation marker pimonidazole was administered as a single or repeated dose to Wistar Furth rats. The stability of oxygen status of islets was evaluated by immunohistochemistry as the number of islets with incorporated pimonidazole adducts after one or repeated pimonidazole injections. Adjacent sections were evaluated for islet cell composition, vascular density, and endocrine cell proliferation. Single and repeated pimonidazole injections over an 8-hour period yielded accumulation of pimonidazole adducts in the same islets. An average of 30% of all islets was in all cases positively stained for pimonidazole adducts. These islets showed a similar endocrine cell composition as other islets but had lower vascular density and β-cell proliferation. In conclusion, low-oxygenated islets were found to be a stable subpopulation of islets for at least 8 hours. Although they have previously been observed to be less functionally active, their islet cell composition was similar to that of other islets. Consistent with their lower oxygenation, they had fewer blood vessels than other islets. Notably, β-cell regeneration preferentially occurred in better-oxygenated islets.

We recently showed that the peripheral cannabinoid receptor type 1 (CNR1) gene is upregulated by the synthetic glucocorticoid dexamethasone. CNR1 is highly expressed in the central nervous system and has been a drug target for the treatment of obesity. Here we explore the role of peripheral CNR1 in states of insulin resistance in human adipose tissue. Subcutaneous adipose tissue was obtained from well-controlled type 2 diabetes subjects and controls. Subcutaneous adipose tissue gene expression levels of CNR1 and endocannabinoid synthesizing and degrading enzymes were assessed. Furthermore, paired human subcutaneous adipose tissue and omental adipose tissue from non-diabetic volunteers undergoing kidney donation or bariatric surgery, was incubated with or without dexamethasone. Subcutaneous adipose tissue obtained from volunteers through needle biopsy was incubated with or without dexamethasone and in the presence or absence of the CNR1-specific antagonist AM281. CNR1 gene and protein expression, lipolysis and glucose uptake were evaluated. Subcutaneous adipose tissue CNR1 gene expression levels were 2-fold elevated in type 2 diabetes subjects compared with control subjects. Additionally, gene expression levels of CNR1 and endocannabinoid-regulating enzymes from both groups correlated with markers of insulin resistance. Dexamethasone increased CNR1 expression dose-dependently in subcutaneous adipose tissue and omental adipose tissue by up to 25-fold. Dexamethasone pre-treatment of subcutaneous adipose tissue increased lipolysis rate and reduced glucose uptake. Co-incubation with the CNR1 antagonist AM281 prevented the stimulatory effect on lipolysis, but had no effect on glucose uptake. CNR1 is upregulated in states of type 2 diabetes and insulin resistance. Furthermore, CNR1 is involved in glucocorticoid-regulated lipolysis. Peripheral CNR1 could be an interesting drug target in type 2 diabetes and dyslipidemia.

Transplantation of islets into the liver confers several site-specific challenges, including a delayed vascularization and prevailing hypoxia. The greater omentum has in several experimental studies been suggested as an alternative implantation site for clinical use, but there has been no direct functional comparison to the liver. In this experimental study in mice, we characterized the engraftment of mouse and human islets in the omentum and compared engraftment and functional outcome with those in the intraportal site. The vascularization and innervation of the islets transplanted into the omentum were restored within the first month by paralleled ingrowth of capillaries and nerves. The hypoxic conditions in the islets early posttransplantation were transient and restricted to the first days. Newly formed blood vessels were fully functional, and the blood perfusion and oxygenation of the islets became similar to that of endogenous islets. Furthermore, islet grafts in the omentum showed at 1 month posttransplantation functional superiority to intraportally transplanted grafts. We conclude that in contrast to the liver the omentum provides excellent engraftment conditions for transplanted islets. Future studies in humans will be of great interest to investigate the capability of this site to also harbor larger grafts without interfering with islet functionality.

The adipokine lipocalin 2 is linked to obesity and metabolic disorders. However, its role in human adipose tissue glucose and lipid metabolism is not explored. Here we show that the synthetic glucocorticoid dexamethasone dose-dependently increased lipocalin 2 gene expression in subcutaneous and omental adipose tissue from pre-menopausal females, while it had no effect in post-menopausal females or in males. Subcutaneous adipose tissue from both genders treated with recombinant human lipocalin 2 showed a reduction in protein levels of GLUT1 and GLUT4 and in glucose uptake in isolated adipocytes. In subcutaneous adipose tissue, lipocalin 2 increased IL-6 gene expression whereas expression of PPARγ and adiponectin was reduced. Our findings suggest that lipocalin 2 can contribute to insulin resistance in human adipose tissue. In pre-menopausal females, it may partly mediate adverse metabolic effects exerted by glucocorticoid excess.

Multiple endocrine neoplasia type 1 (MEN1) is an endocrine tumor syndrome caused by heterozygous mutations in the MEN1 tumor suppressor gene. The MEN1 pancreas of the adolescent gene carrier frequently contain diffusely spread pre-neoplasias and microadenomas, progressing to macroscopic and potentially malignant pancreatic neuroendocrine tumors (P-NET), which represents the major death cause in MEN1. The unveiling of the molecular mechanism of P-NET which is not currently understood fully to allow the optimization of diagnostics and treatment. Glucagon-like peptide 1 (GLP-1) pathway is essential in islet regeneration, i.e. inhibition of β-cell apoptosis and enhancement of β-cell proliferation, yet involvement of GLP-1 in MEN1 related P-NET has not yet been demonstrated. The objective of this work was to investigate if normal sized islets of Men1 heterozygous mice have increased Glucagon-like peptide-1 receptor (GLP-1R) expression compared to wild type islets, and if this increase is detectable in vivo with positron emission tomography (PET) using [68Ga]Ga-DO3A-VS-Cys40-Exendin-4 (68Ga-Exendin-4). 68Ga-Exendin-4 showed potential for early lesion detection in MEN1 pancreas due to increased GLP1R expression.

Background Muscle is a promising alternative site for islet transplantation that facilitates rapid restoration of islet vascularization. However, the development of fibrosis suggests massive cellular death after transplantation. This study tested the hypothesis that islet graft function is limited by hypoxia-related death early after intramuscular transplantation, but that this can be overcome by cotransplantation of an oxygen carrier, that is, polymerized bovine hemoglobin (PolyHb). Methods Two hundred islets were transplanted with or without different doses of PolyHb intramuscularly to nondiabetic C57BL/6 and diabetic C57BL/6 nu/nu mice. β-cell hypoxia and apoptosis were evaluated by immunohistochemistry after injection of the biochemical marker pimonidazole or by staining for caspase-3, respectively. Blood glucose concentrations were monitored for 30 days after islet transplantation and animals were then subjected to an intravenous glucose tolerance test. Results Substantial hypoxia was observed in control islet grafts during the first 4 days after transplantation. Cotransplantation of PolyHb resulted in a dose-dependent reduction of β-cell hypoxia, but β-cell apoptosis was only reduced by cotransplantation of low-dose PolyHb (0.03 mg/g body weight) due to the inflammatory effects of higher PolyHb concentrations. Cotransplantation of low-dose PolyHb resulted in improved islet graft function 30 days after transplantation in diabetic mice, with a glucose tolerance comparable to transplantation of 50% more islets. Conclusion We conclude that cotransplantation of islets with PolyHb can be used to effectively bridge the critical hypoxic phase immediately after transplantation, improve islet graft function, and reduce the number of islets needed for successful intramuscular transplantation.

When one of us (A.A.) served as chairman of our society (Upsala lakareforening) for a 3-year period some 15 years ago, one of the most challenging tasks was to find a reasonable and fruitful handli...

Supplemental Digital Content is Available in the Text. Gastrin-releasing peptide receptor–expressing cells are interneurons that use glutamate to transmit the perception of chemical itch to the next step in the labeled line of itch in the spinal cord., Itch is a sensation that promotes the desire to scratch, which can be evoked by mechanical and chemical stimuli. In the spinal cord, neurons expressing the gastrin-releasing peptide receptor (GRPR) have been identified as specific mediators of itch. However, our understanding of the GRPR population in the spinal cord, and thus how these neurons exercise their functions, is limited. For this purpose, we constructed a Cre line designed to target the GRPR population of neurons (Grpr-Cre). Our analysis revealed that Grpr-Cre cells in the spinal cord are predominantly excitatory interneurons that are found in the dorsal lamina, especially in laminae II-IV. Application of the specific agonist gastrin-releasing peptide induced spike responses in 43.3% of the patched Grpr-Cre neurons, where the majority of the cells displayed a tonic firing property. Additionally, our analysis showed that the Grpr-Cre population expresses Vglut2 mRNA, and mice ablated of Vglut2 in Grpr-Cre cells (Vglut2-lox;Grpr-Cre mice) displayed less spontaneous itch and attenuated responses to both histaminergic and nonhistaminergic agents. We could also show that application of the itch-inducing peptide, natriuretic polypeptide B, induces calcium influx in a subpopulation of Grpr-Cre neurons. To summarize, our data indicate that the Grpr-Cre spinal cord neural population is composed of interneurons that use VGLUT2-mediated signaling for transmitting chemical and spontaneous itch stimuli to the next, currently unknown, neurons in the labeled line of itch.

Highly blood-perfused islets have been observed to be the most functional islets in the native pancreas. We hypothesised that differences in vascular support of islets in donor pancreases influence their susceptibility to cellular stress and capacity for vascular engraftment after transplantation.Highly blood-perfused islets in rats were identified by injection of microspheres into the ascending aorta before islet isolation. Cell death was evaluated after in vitro cytokine or hypoxia exposure, and 2 days post transplantation. One month post transplantation, islet engraftment, including vascular density, blood perfusion and oxygen tension (pO2) in the tissue, was evaluated.Microsphere-containing islets had a similar frequency of cell death during standard culture conditions but increased cell death after exposure to cytokines and hypoxia in comparison with other islets. Two days after transplantation the percentage of apoptotic or necrotic cells was also higher in grafts of such islets and 1 month post transplantation these grafts were composed of substantially more connective tissue. Grafts of highly blood-perfused islets in the native pancreas regained a higher vascular density, blood perfusion and pO2 in comparison with grafts of other islets.Native islets that are highly blood-perfused regained this feature after transplantation, indicating a superior capacity for revascularisation and post-transplant function. However, the same group of islets was more vulnerable to different kinds of cellular stress, which limited their early survival post transplantation. Preferential death of these most active islets may contribute to the high number of islets needed to provide cure with islet transplantation.

Rapid and effective revascularization of transplanted pancreatic islets is vital for the survival and function of the islet graft. Insufficient vascularization after islet transplantation may be one causative factor to the failure of islet grafts in clinical transplantation. The aim of this study was to investigate if N-{N-[2-(3,5-Difluorophenyl)acetyl]-(S)-alanyl}- (S)-phenylglycine- tert-butyl ester (DAPT) administration can improve engraftment of transplanted islets. DAPT is a dipeptidic gamma-secretase inhibitor which inhibits Notch signaling. Notch signaling is involved in angiogenesis and inhibition may result in excessive formation of new blood vessels. Excessive vasculature may be beneficial in the immediate posttransplantation period since the transplanted islets are dependent on diffusion of oxygen and nutrients before revascularization. Islets isolated from C57BL/6 mice were transplanted beneath the renal capsule of C57BL/6 mice. After islet transplantation DAPT or vehicle was administered subcutaneously for three days. Mice treated with DAPT had an increased vascular density when compared to control mice two days and one month posttransplantation. Moreover, mice treated with DAPT showed 54±8.2 % functional blood vessels compared to 40±6.7 % in control mice two days posttransplantation. After one month, the fraction of functional blood vessels increased to 86±2.8 % in DAPT treated mice compared to 61±9.4 % in control mice. Our findings demonstrated that administration of DAPT may be a feasible strategy to improve engraftment of transplanted islets.

Cancer immunotherapy of glioma, the most common primary brain tumor in adults, is constrained by an immunosuppressive microenvironment. Tertiary lymphoid structures (TLSs) are ectopic lymphoid structures that mediate immune responses and provide a local site for tumor antigen presentation. Here, we show for the first time that TLSs are present in human low-grade glioma and that they can be induced in murine glioma models. Agonistic CD40 antibodies induced lymphotoxin α expression in B cells and enhanced the formation of TLSs in mice bearing orthotopic GL261 or CT-2A gliomas. TLSs consisting of B cells, T-cells and antigen presenting cells formed around CD31+ vessels proximal to the tumor tissue and adjacent to the meninges. Agonistic CD40 antibody treatment improved the CD8+ T-cell / Treg ratio in tumor-bearing mice, but there was no survival benefit. A decreased CD69 activation status on CD8+ T-cells, an increase of B cells with a CD1d+CD5+ regulatory phenotype and a high infiltration of Tregs in TLSs indicate that agonistic CD40 antibodies induce an immunosuppressive microenvironment in glioma. Consistent with this, the efficacy of both PD-1 and CTLA-4 checkpoint blockade was significantly decreased by co-administration of agonistic CD40 antibodies. These results demonstrate that TLSs are present and can be induced in glioma, but that they at least under certain conditions are associated with immunosuppression, shedding light on new mechanisms of immune regulation in the brain microenvironment. Citation Format: Luuk van Hooren, Alessandra Vaccaro, Maria Georganaki, Mohanraj Ramachandran, Hua Huang, Joey Lau, Anja Smits, Magnus Essand, Anna Dimberg. Agonistic CD40 antibody therapy induces formation of tertiary lymphoid structures in glioma and inhibits the response to immune-checkpoint blockade [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A159.

Aims/hypothesis The hormone betatrophin was recently described as a potent stimulator of beta cell proliferation in mice. Insulin resistance, but not insulin deficiency, caused upregulation of betatrophin expression. If these findings were found to be fully applicable in humans, this would open up the possibility of future betatrophin treatment in type 1 diabetes. The present study measured for the first time betatrophin concentrations in humans and tested the hypothesis that there would be no difference in circulating betatrophin concentrations between patients with type 1 diabetes and healthy individuals. Methods Betatrophin concentrations in plasma of 33 patients with type 1 diabetes and 24 age-matched healthy controls were measured by ELISA. The study participants were characterised for blood lipids, BMI, plasma glucose and HbA1c, and, for the diabetic patients, their insulin requirements and any residual C-peptide concentrations. Results Plasma betatrophin concentrations were normally ∼300 pg/ml, but were approximately doubled in patients with type 1 diabetes. In the patients, there were no correlations between betatrophin and age, blood lipids, BMI, glucose control or insulin requirement, whereas in controls betatrophin levels increased with age. BMI, blood pressure and triacylglycerol, LDL-cholesterol and HDL-cholesterol levels were similar in patients and healthy controls. Conclusions/interpretation Circulating concentrations of betatrophin are increased in type 1 diabetes in contrast with what was recently described in an insulin-deficient mouse model. However, increased betatrophin concentrations do not protect against loss of C-peptide. Betatrophin treatment in type 1 diabetes would therefore probably not be successful without the use of supraphysiological doses or a combination with immune regulatory treatment.

ER stress results in activation of the unfolded protein response and has been implicated in the development of fibrotic diseases. In this study, we show that inhibition of the ER stress-induced IRE1α signaling pathway, using the inhibitor 4μ8C, blocks TGFβ-induced activation of myofibroblasts in vitro, reduces liver and skin fibrosis in vivo, and reverts the fibrotic phenotype of activated myofibroblasts isolated from patients with systemic sclerosis. By using IRE1α(-/-) fibroblasts and expression of IRE1α-mutant proteins lacking endoribonuclease activity, we confirmed that IRE1α plays an important role during myofibroblast activation. IRE1α was shown to cleave miR-150 and thereby to release the suppressive effect that miR-150 exerted on αSMA expression through c-Myb. Inhibition of IRE1α was also demonstrated to block ER expansion through an XBP-1-dependent pathway. Taken together, our results suggest that ER stress could be an important and conserved mechanism in the pathogenesis of fibrosis and that components of the ER stress pathway may be therapeutically relevant for treating patients with fibrotic diseases. De två första författarna delar förstaförfattarskapet.De två sista författarna delar sistaförfattarskapet.

Small and big mouse islets were compared with special reference to their content of glucagon-producingα-cells and somatostatin-producingδ-cells. Areas stained for glucagon and somatostatin were measured in the largest cross section of small (diameter < 60 μm) and big (diameter > 100 μm) islets. Comparison of the areas indicated proportionally moreδ- thanα-cells in the small islets. After isolation with collagenase these islets were practically devoid ofα-cells. We evaluated the functional importance of the islet size by measuring the Ca2+signal for insulin release. A majority of the small islets responded to the hyperpolarization action of somatostatin with periodic decrease of cytoplasmic Ca2+when glucose was elevated after tolbutamide blockade of theKATPchannels.

Experimental studies indicate low revascularization of intraportally transplanted islets. This study aimed to quantify, for the first time, the blood perfusion of intrahepatically transplanted islets and elucidate necessary factors for proper islet graft revascularization at this site. Yellow chameleon protein 3.0 islets expressing fluorescent protein in all cells were transplanted. Graft blood perfusion was determined by microspheres. The vascular density and relative contribution of donor blood vessels in revascularization was evaluated using islets expressing green fluorescent protein under the Tie-2 promoter. Blood perfusion of intrahepatic islets was as a mean only 5% of that of native islets at 1-month posttransplantation. However, there was a marked heterogeneity where blood perfusion was less decreased in islets transplanted without prior culture and in many cases restored in islets with disrupted integrity. Analysis of vascular density showed that distorted islets were well revascularized, whereas islets still intact at 1-month posttransplantation were almost avascular. Few donor endothelial cells were observed in the new islet vasculature. The very low blood perfusion of intraportally transplanted islets is likely to predispose for ischemia and hamper islet function. Since donor endothelial cells do not expand posttransplantation, disruption of islet integrity is necessary for revascularization to occur by recipient blood vessels.

SUMMARY Pancreatic islet transplantation to the liver provides the possibility of restoring glucose homeostasis in patients with Type 1 diabetes. However, several hurdles remain to be solved in order to optimize this treatment, including developing the means to restrict early islet cell death by hypoxia and inflammatory events and to facilitate the engraftment of islets by improvements in revascularization. Intraportally transplanted islets are poorly revascularized in contrast to islets implanted into muscle or the pancreas. Changing the implantation organ may therefore be a possibility for improving results in clinical islet transplantation, but other hurdles may then arise, including the issue of overload and excessive islet cell death when implanting islets in clusters. New strategies to improve revascularization, also at the intraportal site, by proangiogenic factors such as VEGF, and by inhibition of angiostatic factors such as thrombospondin-1 present in islets, or by cell therapy using mesenchymal...

Previously, we have found that human islets experimentally transplanted beneath the kidney capsule have lower vascular density than native islets. This study aimed to investigate whether human islets experimentally transplanted into the liver are also poorly revascularized in the same manner as islets at the renal subcapsular site. Human islets were transplanted to nude mice. One month posttransplantation, the islet graft-bearing livers or kidneys were removed, formalin-fixed, and stained with the lectin Bandeiraea (Griffonia) simplicifolia (BS-1) to visualize endothelium. The vascular density in the intraportally transplanted human islets was found to be similarly low as in human islets transplanted beneath the kidney capsule. The intrahepatic human islets were coated with numerous vessels, but few vessels could be seen within the islets. Human islets transplanted intraportally into the liver become poorly revascularized. This could contribute to the loss of function in human islets transplanted into the liver over time.

OBJECTIVE—Clinical islet transplantations are performed through infusion of islets via the portal vein into the liver. This study aimed at characterizing the influence of the implantation microenvironment on islet graft metabolism and function. RESEARCH DESIGN AND METHODS—Islets were transplanted into their normal environment, i.e., the pancreas, or intraportally into the liver of mice. One month posttransplantation, the transplanted islets were retrieved and investigated for changes in function and gene expression. RESULTS—Insulin content, glucose-stimulated insulin release, (pro)insulin biosynthesis, and glucose oxidation rate were markedly decreased in islets retrieved from the liver, both when compared with islets transplanted into the pancreas and endogenous islets. Islets transplanted into the pancreas showed normal insulin content, (pro)insulin biosynthesis, and glucose oxidation rate but increased basal insulin secretion and impaired glucose stimulation index. Gene expression data for retrieved islets showed downregulation of pancreatic and duodenal homeobox gene-1, GLUT-2, glucokinase, mitochondrial glycerol-phosphate dehydrogenase, and pyruvate carboxylase, preferentially in intraportally transplanted islets. CONCLUSIONS—Islets transplanted into their normal microenvironment, i.e., the pancreas, display gene expression changes when compared with endogenous islets but only moderate changes in metabolic functions. In contrast, site-specific properties of the liver markedly impaired the metabolic functions of intraportally transplanted islets.