DNA methylation regulates pancreatic gene expression and links maternal high-fat diet to the offspring glucose metabolism

Maternal high-fat diet (HFD) is related to an increased risk of glucose metabolism disorders throughout the whole life of offspring. The pancreas is a glucose homeostasis regulator. Accumulating evidence has revealed that maternal HFD affects offspring pancreas structure and function. However, the potential mechanism remains unclear. In this study, the mouse dam was fed with HFD or control diet (CD) during prepregnancy, pregnancy and lactation. The pancreatic insulin secretion function and islet genome methylome of offspring were analyzed. Pancreatic islet specific gene methylation was detected by using MeDIP qPCR. The results showed that body weight, blood glucose after oral glucose loads, fasting serum insulin, and HOMA-IR index values were significantly higher in male 12-week-old offspring from HFD dams than in the offspring from CD dams. Maternal HFD induced insulin secretion defects in male offspring. Compared with that in maternal CD group, methylation of the Abcc8 and Kcnj11 genes was increased in maternal HFD group in male offspring pancreatic islets. Furthermore, the expression levels of Abcc8 and Kcnj11 were downregulated by intrauterine exposure to a maternal HFD. In summary, maternal HFD results in a long-term functional disorder of the pancreas that is involved in insulin secretion-related gene DNA hypermethylation.

Experimental datasets on the immunohistological assessment of δ-cells in the islet organs of the endocrine pancreas of Japanese medaka (Oryzias latipes) fish exposed to graphene oxide

The datasets of this article present the experimental parameters resulting from the assessment of δ-cells in the islet organs of the endocrine pancreas as a potential biomarker of endocrine disruption (ED) mediated by graphene oxide (GO), using Japanese medaka fish as the model. These datasets support the article "Evaluation of pancreatic δ-cells as a potential target site of graphene oxide toxicity in Japanese medaka (Oryzias latipes) fish". GO used in the experiments was either obtained from a commercial source or synthesized in the laboratory by us. GO was sonicated for 5 min in ice temperature before application. The experiments were conducted on reproductively active adult fish maintained as a breeding pair (one male and one female) in 500 ml balanced salt solution (BSS) either by immersion (IMR) in GO (20 mg/L) continuously for 96 h with the refreshing of media once in every 24 h, or by a single intraperitoneal (IP) administration of GO (100 µg/g) to both male and female partners. Control fish were maintained in BSS only (IMR experiment), or nanopure water (vehicle) was injected into the peritoneal cavity (IP experiment). The IP experimental fish were anesthetized in MS-222 (100 mg/L in BSS); the injected volume (0.5 µL/10 mg fish) never exceeds 50 µl/fish. After injection, the injected fish were allowed for recovery in clean BSS and after recovery both partners were transferred to 1 L glass jars with 500 mL BSS. During depuration, the media of the breeders refreshed once every 24 h and the eggs were collected. After 21 days, the survived fish were anaesthetized, and the trunk region was preserved in 4% paraformaldehyde in PBS (20 mM) containing 0.05% Tween 20. The phenotypic sex of adult fish was assessed externally by secondary sex characters (fin features) and internally by gonad (testis and ovary) histology. Once the location of pancreas was determined after HE stains, immunohistochemical technique was applied on next few slides using rabbit derived polyclonal antisomatostatin antibody as primary antibody and a commercial kit for colorimetric determination of δ-cells in the islet organs was used. Images were captured using an Olympus CKX53 inverted microscope with DP22 camera and CellSens software. Using imagej software, a minimum 3 images of principal islets and one image of secondary islets were assessed. The immunoreactivity of δ-cells, due to neuron-like appearance and filopodia like processes, enabled us to separate them from other cell types found in the pancreatic islets of medaka. Based on immunoreactivity, we have classified islet cells into three categories; noncommunicating delta cells (NCDC), communicating cells (CC), and non-delta cells (NDC), and expressed as number of cells (NCDC/CC/NDC)/mm² of islet organs. The nuclear area (µm²) and the linear length of filopodia of NCDCs were also considered for evaluation. Numerical data were analysed by Kruskal-Wallis test followed by Mann-Whitney's test as post hoc test and presented as means  ±  SEM. Statistically significant differences were considered for p ≤ 0.05.

Peroxisomes during postnatal development of mouse endocrine and exocrine pancreas display cell-type- and stage-specific protein composition

Peroxisomal dysfunction unhinges cellular metabolism by causing the accumulation of toxic metabolic intermediates (e.g. reactive oxygen species, very -chain fatty acids, phytanic acid or eicosanoids) and the depletion of important lipid products (e.g. plasmalogens, polyunsaturated fatty acids), leading to various proinflammatory and devastating pathophysiological conditions like metabolic syndrome and age-related diseases including diabetes. Because the peroxisomal antioxidative marker enzyme catalase is low abundant in Langerhans islet cells, peroxisomes were considered scarcely present in the endocrine pancreas. Recently, studies demonstrated that the peroxisomal metabolism is relevant for pancreatic cell functionality. During the postnatal period, significant changes occur in the cell structure and the metabolism to trigger the final maturation of the pancreas, including cell proliferation, regulation of energy metabolism, and activation of signalling pathways. Our aim in this study was to (i) morphometrically analyse the density of peroxisomes in mouse endocrine versus exocrine pancreas and (ii) investigate how the distribution and the abundance of peroxisomal proteins involved in biogenesis, antioxidative defence and fatty acid metabolism change during pancreatic maturation in the postnatal period. Our results prove that endocrine and exocrine pancreatic cells contain high amounts of peroxisomes with heterogeneous protein content indicating that distinct endocrine and exocrine cell types require a specific set of peroxisomal proteins depending on their individual physiological functions. We further show that significant postnatal changes occur in the peroxisomal compartment of different pancreatic cells that are most probably relevant for the metabolic maturation and differentiation of the pancreas during the development from birth to adulthood.

iPSC-Derived Pancreatic Progenitors Lacking FOXA2 Reveal Alterations in miRNA Expression Targeting Key Pancreatic Genes

Recently, we reported that forkhead box A2 (FOXA2) is required for the development of human pancreatic α- and β-cells. However, whether miRNAs play a role in regulating pancreatic genes during pancreatic development in the absence of FOXA2 expression is largely unknown. Here, we aimed to capture the dysregulated miRNAs and to identify their pancreatic-specific gene targets in pancreatic progenitors (PPs) derived from wild-type induced pluripotent stem cells (WT-iPSCs) and from iPSCs lacking FOXA2 (FOXA2^-/-iPSCs). To identify differentially expressed miRNAs (DEmiRs), and genes (DEGs), two different FOXA2^-/-iPSC lines were differentiated into PPs. FOXA2^-/- PPs showed a significant reduction in the expression of the main PP transcription factors (TFs) in comparison to WT-PPs. RNA sequencing analysis demonstrated significant reduction in the mRNA expression of genes involved in the development and function of exocrine and endocrine pancreas. Furthermore, miRNA profiling identified 107 downregulated and 111 upregulated DEmiRs in FOXA2^-/- PPs compared to WT-PPs. Target prediction analysis between DEmiRs and DEGs identified 92 upregulated miRNAs, predicted to target 1498 downregulated genes in FOXA2^-/- PPs. Several important pancreatic TFs essential for pancreatic development were targeted by multiple DEmiRs. Selected DEmiRs and DEGs were further validated using RT-qPCR. Our findings revealed that FOXA2 expression is crucial for pancreatic development through regulating the expression of pancreatic endocrine and exocrine genes targeted by a set of miRNAs at the pancreatic progenitor stage. These data provide novel insights of the effect of FOXA2 deficiency on miRNA-mRNA regulatory networks controlling pancreatic development and differentiation.

Endocrine Diagnostics for Exotic Animals

Endocrine disease in exotic species is less common than in small animals. Nevertheless, the diagnostic principles used in small animals can be adapted to evaluate endocrine disease in many of the exotic species although species-specific aspects need to be considered. This article covers important diseases such as thyroid dysfunction in reptiles and birds, hyperthyroidism in guinea pigs, and hyperadrenocorticism in ferrets. Glucose metabolism in neoplasms affecting normal physiology, such as insulinoma in ferrets and gastric neuroendocrine carcinoma in bearded dragons, is discussed. Calcium abnormalities, including metabolic bone disease in reptiles and hypocalcemia in birds, are also covered.

The effect of zinc deficiency and iron overload on endocrine and exocrine pancreatic function in children with transfusion-dependent thalassemia: a cross-sectional study

BACKGROUND

Children with transfusion-dependent thalassemia (TDT) suffer from secondary hemosiderosis and the delirious effects this iron overload has on their different body organs, including the pancreas. They are also more prone to develop zinc deficiency than the general pediatric population. This study aimed to determine the effect of zinc deficiency and iron overload on the endocrine and exocrine pancreas in TDT children.

METHODS

Eighty children, already diagnosed with TDT, were included in this study. We assessed the following in the participant children: serum ferritin, serum zinc, endocrine pancreatic function (oral glucose tolerance test (OGTT), fasting insulin level and from them, HOMA-IR was calculated), and exocrine pancreatic function (serum lipase and serum amylase).

RESULTS

Forty-four TDT children had a subnormal zinc level, while 36 of them had a normal serum zinc level. TDT children with low serum zinc had significantly more impaired endocrine pancreatic function and an abnormally high serum lipase than children with normal serum zinc, p < 0.05 in all. Serum zinc was significantly lower in TDT children with serum ferritin above the ferritin threshold (≥2500 ng/ml) than those below (59.1 ± 20.2 vs. 77.5 ± 28.13), p = 0.02. TDT children, having a serum ferritin ≥2500 ng/ml, had significantly more frequently impaired endocrine pancreatic function and abnormally high serum lipase than TDT children below the ferritin threshold, p < 0.05 in all.

CONCLUSION

In children with transfusion-dependent thalassemia, zinc deficiency aggravates iron-induced pancreatic exocrine and endocrine dysfunction.

Involvement of aquaglyceroporins in energy metabolism in health and disease

Aquaglyceroporins are a group of the aquaporin (AQP) family of transmembrane water channels. While AQPs facilitate the passage of water, small solutes, and gases across biological membranes, aquaglyceroporins allow passage of water, glycerol, urea and some other solutes. Thanks to their glycerol permeability, aquaglyceroporins are involved in energy homeostasis. This review provides an overview of what is currently known concerning the functional implication and control of aquaglyceroporins in tissues involved in energy metabolism, i.e. liver, adipose tissue and endocrine pancreas. The expression, role and (dys)regulation of aquaglyceroporins in disorders affecting energy metabolism, and the potential relevance of aquaglyceroporins as drug targets to treat the alterations of the energy balance is also addressed.

The dynamic methylome of islets in health and disease

Background

Epigenetic processes control timing and level of gene expression throughout life, during development, differentiation, and aging, and are the link to adapting gene expression profiles to environmental cues. To qualify for the definition of ‘epigenetic’, a change to a gene's activity must be inherited through at least one mitotic division. Epigenetic mechanisms link changes in the environment to adaptions of the genome that do not rely on changes in the DNA sequence. In the past two decades, multiple studies have aimed to identify epigenetic mechanisms, and to define their role in development, differentiation and disease.

Scope of review

In this review, we will focus on the current knowledge of the epigenetic control of pancreatic beta cell maturation and dysfunction and its relationship to the development of islet cell failure in diabetes. Most of the data currently available have been obtained in mice, but we will summarize studies of human data as well. We will focus here on DNA methylation, as this is the most stable epigenetic mark, and least impacted by the variables inherent in islet procurement, isolation, and culture.

Major conclusions

DNA methylation patterns of beta cell are dynamic during maturation and during the diabetic process. In both cases, the changes occur at cell specific regulatory regions such as enhancers, where the methylation profile is cell type specific. Frequently, the differentially methylated regulatory elements are associated with key function genes such as PDX1, NKX6-1 and TCF7L2. During maturation, enhancers tend to become demethylated in association with increased activation of beta cell function genes and increased functionality, as indicated by glucose stimulated insulin secretion. Likewise, the changes to the DNA methylome that are present in pancreatic islets from diabetic donors are enriched in regulatory regions as well.

Cyb5r3 links FoxO1-dependent mitochondrial dysfunction with β-cell failure

OBJECTIVE

Diabetes is characterized by pancreatic β-cell dedifferentiation. Dedifferentiating β cells inappropriately metabolize lipids over carbohydrates and exhibit impaired mitochondrial oxidative phosphorylation. However, the mechanism linking the β-cell's response to an adverse metabolic environment with impaired mitochondrial function remains unclear.

METHODS

Here we report that the oxidoreductase cytochrome b5 reductase 3 (Cyb5r3) links FoxO1 signaling to β-cell stimulus/secretion coupling by regulating mitochondrial function, reactive oxygen species generation, and nicotinamide actin dysfunction (NAD)/reduced nicotinamide actin dysfunction (NADH) ratios.

RESULTS

The expression of Cyb5r3 is decreased in FoxO1-deficient β cells. Mice with β-cell-specific deletion of Cyb5r3 have impaired insulin secretion, resulting in glucose intolerance and diet-induced hyperglycemia. Cyb5r3-deficient β cells have a blunted respiratory response to glucose and display extensive mitochondrial and secretory granule abnormalities, consistent with altered differentiation. Moreover, FoxO1 is unable to maintain expression of key differentiation markers in Cyb5r3-deficient β cells, suggesting that Cyb5r3 is required for FoxO1-dependent lineage stability.

CONCLUSIONS

The findings highlight a pathway linking FoxO1 to mitochondrial dysfunction that can mediate β-cell failure.

Isolation and Purification of Rodent Pancreatic Islets of Langerhans

This chapter describes the detailed protocol for the isolation and purification of islets of Langerhans from rodent pancreas using collagenase digestion. The first step of the process is to separate and isolate the insulin-producing islets of Langerhans from the rest of the pancreas. The pancreas is excised from the animal, trimmed of nonpancreatic tissues before being inflated and chopped into small pieces. The connective tissue is then broken down with a collagenase enzyme solution to selectively digest the bulk of the exocrine tissue while leaving the endocrine islets intact and separated from their surrounding non-islet tissue. Once this process is completed, the islets of Langerhans are separated from the remaining mixture by centrifugation and purified by the means of hand picking. Once isolated, the subsequent islets can be used for several varied experimental processes, including transplantation, the study of pathophysiological mechanisms in diabetic conditions, and in the screening of novel therapeutic approaches in pharmacological research.

Embryonic exposure to oxy-polycyclic aromatic hydrocarbon interfere with pancreatic β-cell development in zebrafish via altering DNA methylation and gene expression

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are a class of anthropogenic, persistent and very toxic PAH contaminant associated with developmental toxicity. Abnormal glucose metabolism disturbs energy balances that impair the early development of vertebrates, but the mechanisms by which maternal OPAH exposure alters glucose homeostasis in offspring are not well understood. Studies have suggested that epigenetic changes, particularly in DNA methylation, provide a memory of plastic developmental responses to the environment, leading to the generation of novel offspring phenotypes. The objective of this study is to test the hypothesis that embryonic exposure to low-dose OPAH can impair early β-cell differentiation in zebrafish (Danio rerio) by altering DNA methylation and gene expression. The zebrafish embryos were exposed to 0, 0.03, 0.1, 0.3, 1 and 3 μM 9‑fluorenone (9-FLO) at 3 h postfertilization (hpf) until 120 hpf to assess pancreatic organogenesis. 9-FLO exposure reduced total body length, eye length and heart rate, decreased insulin generation, interfered with glucose metabolism, and altered the expression of pancreatic organogenesis-related genes pdx-1, foxa2, isl1 and ptf1a. In particular, low-dose embryonic 9-FLO exposure significantly decreased β-cell differentiation marker gene pdx-1 mRNA levels, indicating that pancreatic endocrine is a more sensitive target response to embryonic low-dose OPAH exposure. Additionally, we found that DNA methyltransferases dnmt1 and dnmt3 were elevated and the DNA methylation at promoter regions of pdx-1 was increased at an early stage of development. These data demonstrated that the low-dose OPAH embryonic exposure can impair pancreatic endocrine development by increasing DNA methylation at the promoter regions of pdx-1 that are essential for β-cell differentiation.

Can We Re-Engineer the Endocrine Pancreas?

PURPOSE OF REVIEW

Engineering endocrine pancreatic tissue is an emerging topic in type 1 diabetes with the intent to overcome the current limitation of β cell transplantation. During islet isolation, the vascularized structure and surrounding extracellular matrix (ECM) are completely disrupted. Once implanted, islets slowly engraft and mostly are lost for the initial avascular phase. This review discusses the main building blocks required to engineer the endocrine pancreas: (i) islet niche ECM, (ii) islet niche vascular network, and (iii) new available sources of endocrine cells.

RECENT FINDINGS

Current approaches include the following: tissue engineering of endocrine grafts by seeding of native or synthetic ECM scaffolds with human islets, vascularization of native or synthetic ECM prior to implantation, vascular functionalization of ECM structures to enhance angiogenesis after implantation, generation of engineered animals as human organ donors, and embryonic and pluripotent stem cell-derived endocrine cells that may be encapsulated or genetically engineered to be immunotolerated. Substantial technological improvements have been made to regenerate or engineer endocrine pancreatic tissue; however, significant hurdles remain, and more research is needed to develop a technology to integrate all components of viable endocrine tissue for clinical application.

Patterns of differential gene expression in a cellular model of human islet development, and relationship to type 2 diabetes predisposition

AIMS/HYPOTHESIS

Most type 2 diabetes-associated genetic variants identified via genome-wide association studies (GWASs) appear to act via the pancreatic islet. Observed defects in insulin secretion could result from an impact of these variants on islet development and/or the function of mature islets. Most functional studies have focused on the latter, given limitations regarding access to human fetal islet tissue. Capitalising upon advances in in vitro differentiation, we characterised the transcriptomes of human induced pluripotent stem cell (iPSC) lines differentiated along the pancreatic endocrine lineage, and explored the contribution of altered islet development to the pathogenesis of type 2 diabetes.

METHODS

We performed whole-transcriptome RNA sequencing of human iPSC lines from three independent donors, at baseline and at seven subsequent stages during in vitro islet differentiation. Differentially expressed genes (q < 0.01, log2 fold change [FC] > 1) were assigned to the stages at which they were most markedly upregulated. We used these data to characterise upstream transcription factors directing different stages of development, and to explore the relationship between RNA expression profiles and genes mapping to type 2 diabetes GWAS signals.

RESULTS

We identified 9409 differentially expressed genes across all stages, including many known markers of islet development. Integration of differential expression data with information on transcription factor motifs highlighted the potential contribution of REST to islet development. Over 70% of genes mapping within type 2 diabetes-associated credible intervals showed peak differential expression during islet development, and type 2 diabetes GWAS loci of largest effect (including TCF7L2; log2FC = 1.2; q = 8.5 × 10-10) were notably enriched in genes differentially expressed at the posterior foregut stage (q = 0.002), as calculated by gene set enrichment analyses. In a complementary analysis of enrichment, genes differentially expressed in the final, beta-like cell stage of in vitro differentiation were significantly enriched (hypergeometric test, permuted p value <0.05) for genes within the credible intervals of type 2 diabetes GWAS loci.

CONCLUSIONS/INTERPRETATION

The present study characterises RNA expression profiles during human islet differentiation, identifies potential transcriptional regulators of the differentiation process, and suggests that the inherited predisposition to type 2 diabetes is partly mediated through modulation of islet development.

DATA AVAILABILITY

Sequence data for this study has been deposited at the European Genome-phenome Archive (EGA), under accession number EGAS00001002721.

Insulinoma: A retrospective study analyzing the differences between benign and malignant tumors

BACKGROUND/OBJECTIVES

Insulinoma is a rare pancreatic tumor and, usually, a benign disease but can be a malignant one and, sometimes, a highly aggressive disease. The aim of this study was to determine differences between benign and malignant tumors.

METHODS

Retrospective study of 103 patients with insulinoma treated in a tertiary center. It was analyzed demographic, clinical, laboratory, localization and histologic analysis of tumor and follow up data of subjects in order to identify differences between individuals benign and malignant disease.

RESULTS

Almost all patients (87%) had a benign tumor and survival rates of 100% following pancreatic tumor surgery. Those with malignant tumors (13%) have a poor prognosis, 77% insulinoma-related deaths over a period of 1-300 months after the diagnosis with a survival rate of 24% in five years. The following factors are associated with an increased risk of malignant disease: duration of symptoms < 24 months, fasting time for the occurrence of hypoglycemia < 8 h, blood plasma insulin concentration ≥ 28 μU/mL and C-peptide ≥ 4.0 ng/mL at the glycemic nadir and tumor size ≥ 2.5 cm.

CONCLUSIONS

Our data help to base the literature about these tumors, reinforcing that although insulinoma is usually a single benign and surgically treated neoplasia, the malignant one is difficult to treat. We highlight the data that help predict a malignancy behavior of tumor and suggest a long follow up after diagnosis in these cases.

Sympathetic innervation is essential for metabolic homeostasis and pancreatic beta cell function in adult rats

Obesity is associated with an imbalance in the activity of the autonomic nervous system (ANS), specifically in the organs involved in energy metabolism. The pancreatic islets are richly innervated by the ANS, which tunes the insulin release due to changes in energy demand. Therefore, changes in the sympathetic input that reach the pancreas can lead to metabolic dysfunctions. To evaluate the role of the sympathetic ends that innervate the pancreas, 60-day-old male Wistar rats were subjected to sympathectomy (SYM) or were sham-operated (SO). At 120 day-old SYM rats exhibited an increase in body weight, fat pads and metabolic dysfunctions. Decreases in the HOMA-IR and reductions in insulin release were observed both in vivo and in vitro. Furthermore, the SYM rats exhibited altered pancreatic islet function in both muscarinic and adrenergic assays and exhibited high protein expression of the alpha-2 adrenergic receptor (α2AR). Because α2AR has been linked to type 2 diabetes, these findings demonstrate the clinical implications of this study.

Effects of acrylamide on oxidant/antioxidant parameters and CYP2E1 expression in rat pancreatic endocrine cells

Oxidative stress is one of the principle mechanism of acrylamide-induced toxicity. Acrylamide is metabolized by cytochrome P450 2E1 (CYP2E1) to glycidamide or by direct conjugation with glutathione. Bearing in mind that up to now the effects of acrylamide on oxidative stress status and CYP2E1 level in endocrine pancreas have not been studied we performed qualitative and quantitative immunohistochemical evaluation of inducible nitric oxide synthase (iNOS), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), catalase (CAT) and CYP2E1 expression in islets of Langerhans of rats subchronically treated with 25 or 50mg/kg bw of acrylamide. Since the majority of cells (>80%) in rodent islets are beta cells, in parallel studies, we employed the Rin-5F beta cell line to examine effects of acrylamide on redox status and the activity of CAT, SOD and glutathione-S-transferase (GST), their gene expression, and CYP2E1, NF-E2 p45-related factor 2 (Nrf2) and iNOS expression. Immunohistochemically stained pancreatic sections revealed that acrylamide induced increase of iNOS and decrease of CYP2E1 protein expression, while expression of antioxidant enzymes was not significantly affected by acrylamide in islets of Langerhans. Analysis of Mallory-Azan stained pancreatic sections revealed increased diameter of blood vessels lumen in pancreatic islets of acrylamide-treated rats. Increase in the GST activity, lipid peroxidation and nitrite level, and decrease in GSH content, CAT and SOD activities was observed in acrylamide-exposed Rin-5F cells. Level of mRNA was increased for iNOS, SOD1 and SOD2, and decreased for GSTP1, Nrf2 and CYP2E1 in acrylamide-treated Rin-5F cells. This is the first report of the effects of acrylamide on oxidant/antioxidant parameters and CYP2E1 expression in pancreatic endocrine cells.

18F-DOPA PET/CT and 68Ga-DOTANOC PET/CT scans as diagnostic tools in focal congenital hyperinsulinism: a blinded evaluation

Purpose

Focal congenital hyperinsulinism (CHI) is curable by surgery, which is why identification of the focal lesion is crucial. We aimed to determine the use of 18F–fluoro-dihydroxyphenylalanine (18F-DOPA) PET/CT vs. 68Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic-acid-1-Nal3-octreotide (68Ga-DOTANOC) PET/CT as diagnostic tools in focal CHI.

Methods

PET/CT scans of children with CHI admitted to Odense University Hospital between August 2005 and June 2016 were retrospectively evaluated visually and by their maximal standardized uptake values (SUV_max) by two independent examiners, blinded for clinical, surgical and pathological data. Pancreatic histology was used as the gold standard. For patients without surgery, the genetic profile served as the gold standard.

Results

Fifty-five CHI patients were examined by PET/CT (18F-DOPA n = 53, 68Ga-DOTANOC n = 18). Surgery was performed in 34 patients, no surgery in 21 patients. Fifty-one patients had a classifiable outcome, either by histology (n = 33, 22 focal lesions, 11 non-focal) or by genetics (n = 18, all non-focal). The predictive performance of 18F-DOPA PET/CT to identify focal CHI was identical by visual- and cut-off-based evaluation: sensitivity (95% CI) of 1 (0.85–1); specificity of 0.96 (0.82–0.99). The optimal 18F-DOPA PET SUV_max ratio cut-off was 1.44 and the optimal 68Ga-DOTANOC PET SUV_max cut-off was 6.77 g/ml. The area under the receiver operating curve was 0.98 (0.93–1) for 18F-DOPA PET vs. 0.71 (0.43–0.95) for 68Ga-DOTANOC PET (p < 0.03). In patients subjected to surgery, localization of the focal lesion was correct in 91%, and 100%, by 18F-DOPA PET/CT and 68Ga-DOTANOC PET/CT, respectively.

Conclusion

18F-DOPA PET/CT was excellent in predicting focal CHI and superior compared to 68Ga-DOTANOC PET/CT. Further use of 68GA-DOTANOC PET/CT in predicting focal CHI is discouraged.

Electronic supplementary material

The online version of this article (10.1007/s00259-017-3867-1) contains supplementary material, which is available to authorized users.

The Different Faces of the Pancreatic Islet

Type 1 diabetes (T1D) patients who receive pancreatic islet transplant experience significant improvement in their quality-of-life. This comes primarily through improved control of blood sugar levels, restored awareness of hypoglycemia, and prevention of serious and potentially life-threatening diabetes-associated complications, such as kidney failure, heart and vascular disease, stroke, nerve damage, and blindness. Therefore, beta cell replacement through transplantation of isolated islets is an important option in the treatment of T1D. However, lasting success of this promising therapy depends on durable survival and efficacy of the transplanted islets, which are directly influenced by the islet isolation procedures. Thus, isolating pancreatic islets with consistent and reliable quality is critical in the clinical application of islet transplantation.Quality of isolated islets is important in pre-clinical studies as well, as efforts to advance and improve clinical outcomes of islet transplant therapy have relied heavily on animal models ranging from rodents, to pigs, to nonhuman primates. As a result, pancreatic islets have been isolated from these and other species and used in a variety of in vitro or in vivo applications for this and other research purposes. Protocols for islet isolation have been somewhat similar across species, especially, in mammals. However, given the increasing evidence about the distinct structural and functional features of human and mouse islets, using similar methods of islet isolation may contribute to inconsistencies in the islet quality, immunogenicity, and experimental outcomes. This may also contribute to the discrepancies commonly observed between pre-clinical findings and clinical outcomes. Therefore, it is prudent to consider the particular features of pancreatic islets from different species when optimizing islet isolation protocols.In this chapter, we explore the structural and functional features of pancreatic islets from mice, pigs, nonhuman primates, and humans because of their prevalent use in nonclinical, preclinical, and clinical applications.

Epigenetics in formation, function, and failure of the endocrine pancreas

Background

Epigenetics, in the broadest sense, governs all aspects of the life of any multicellular organism, as it controls how differentiated cells arrive at their unique phenotype during development and differentiation, despite having a uniform (with some exceptions such as T-cells and germ cells) genetic make-up. The endocrine pancreas is no exception. Transcriptional regulators and epigenetic modifiers shape the differentiation of the five major endocrine cell types from their common precursor in the fetal pancreatic bud. Beyond their role in cell differentiation, interactions of the organism with the environment are also often encoded into permanent or semi-permanent epigenetic marks and affect cellular behavior and organismal health. Epigenetics is defined as any heritable – at least through one mitotic cell division – change in phenotype or trait that is not the result of a change in genomic DNA sequence, and it forms the basis that mediates the environmental impact on diabetes susceptibility and islet function.

Scope of review

We will summarize the impact of epigenetic regulation on islet cell development, maturation, function, and pathophysiology. We will briefly recapitulate the major epigenetic marks and their relationship to gene activity, and outline novel strategies to employ targeted epigenetic modifications as a tool to improve islet cell function.

Major conclusions

The improved understanding of the epigenetic underpinnings of islet cell differentiation, function and breakdown, as well as the development of innovative tools for their manipulation, is key to islet cell biology and the discovery of novel approaches to therapies for islet cell failure.

George E. Palade memorial lecture: My life in pancreatic research-unexpected results may open the door

The Palade Prize is the most distinguished award of the IAP for achievement in pancreatic research. It is named after George E. Palade, who in 1974 was awarded the Nobel Prize for his work on protein trafficking in pancreatic acinar cells. It is a great honor to be awarded the 2016 Palade Prize. While I was in graduate school, I was conducting research on hypothalamo-pituitary-thyroid axis; after finishing graduate school, I began research on amylase isoenzymes. This was the first step of my pancreatic research. Once I discovered that there are close relationships among blood glucose levels, amylase activity, and exocrine pancreatic function, I continued on to the next challenge. I performed research on the relationship between exocrine and endocrine aspects of the pancreas, pancreatic exocrine functions in diabetes mellitus, the role of cholecystokinin (CCK) and its synthetic analogue on exocrine and endocrine pancreas function, the role of CCK on the pathogenesis of pancreatitis, the cellular mechanisms of reversible and irreversible pancreatitis, and pancreatic stellate cell activation. In addition, I established guidelines for the diagnosis and management of acute, chronic and autoimmune pancreatitis as a chief investigator of the Research Committee of Intractable Pancreatic Diseases supported by the Ministry of Health, Labour and Welfare in Japan.

Analysis of pancreatic disease in zebrafish

One of the appeals of the zebrafish model is the relative ease of studying disease progression from embryonic or larval stages through to adulthood. Because of this, the zebrafish has become an important model for postembryonic pancreatic disease, particularly diabetes and pancreatic cancer. Here we present methods for using the adult zebrafish to analyze pancreas function and structure, with an emphasis on the endocrine pancreas and the beta cells. The methods include fasting, weighing adults, and anesthetizing adults, and intraperitoneal injection of glucose based on body weight. We also present dissection methods for removing the pancreas intact for histological studies and for sterile dissection of the principal islet followed by dissociation for cell culture-based studies of beta-cell function.

Proglucagons in vertebrates: Expression and processing of multiple genes in a bony fish

In contrast to mammals, where a single proglucagon (PG) gene encodes three peptides: glucagon, glucagon-like peptide 1 and glucagon-like peptide 2 (GLP-1; GLP-2), many non-mammalian vertebrates carry multiple PG genes. Here, we investigate proglucagon mRNA sequences, their tissue expression and processing in a diploid bony fish. Copper rockfish (Sebastes caurinus) express two independent genes coding for distinct proglucagon sequences (PG I, PG II), with PG II lacking the GLP-2 sequence. These genes are differentially transcribed in the endocrine pancreas, the brain, and the gastrointestinal tract. Alternative splicing identified in rockfish is only one part of this complex regulation of the PG transcripts: the system has the potential to produce two glucagons, four GLP-1s and a single GLP-2, or any combination of these peptides. Mass spectrometric analysis of partially purified PG-derived peptides in endocrine pancreas confirms translation of both PG transcripts and differential processing of the resulting peptides. The complex differential regulation of the two PG genes and their continued presence in this extant teleostean fish strongly suggests unique and, as yet largely unidentified, roles for the peptide products encoded in each gene.

Acute disruption of glucagon secretion or action does not improve glucose tolerance in an insulin-deficient mouse model of diabetes

AIMS/HYPOTHESIS

Normal glucose metabolism depends on pancreatic secretion of insulin and glucagon. The bihormonal hypothesis states that while lack of insulin leads to glucose underutilisation, glucagon excess is the principal factor in diabetic glucose overproduction. A recent study reported that streptozotocin-treated glucagon receptor knockout mice have normal glucose tolerance. We investigated the impact of acute disruption of glucagon secretin or action in a mouse model of severe diabetes by three different approaches: (1) alpha cell elimination; (2) glucagon immunoneutralisation; and (3) glucagon receptor antagonism, in order to evaluate the effect of these on glucose tolerance.

METHODS

Severe diabetes was induced in transgenic and wild-type mice by streptozotocin. Glucose metabolism was investigated using OGTT in transgenic mice with the human diphtheria toxin receptor expressed in proglucagon producing cells allowing for diphtheria toxin (DT)-induced alpha cell ablation and in mice treated with either a specific high affinity glucagon antibody or a specific glucagon receptor antagonist.

RESULTS

Near-total alpha cell elimination was induced in transgenic mice upon DT administration and resulted in a massive decrease in pancreatic glucagon content. Oral glucose tolerance in diabetic mice was neither affected by glucagon immunoneutralisation, glucagon receptor antagonism, nor alpha cell removal, but did not deteriorate further compared with mice with intact alpha cell mass.

CONCLUSIONS/INTERPRETATION

Disruption of glucagon action/secretion did not improve glucose tolerance in diabetic mice. Near-total alpha cell elimination may have prevented further deterioration. Our findings support insulin lack as the major factor underlying hyperglycaemia in beta cell-deficient diabetes.

Anatomic and molecular characterization of the endocrine pancreas of a teleostean fish: Atlantic wolffish (Anarhichas lupus)

BACKGROUND

The biologic attributes of the endocrine pancreas and the comparative endocrinology of islet amyloid polypeptide (IAPP) of fish are not well described in the literature. This study describes the endocrine pancreasof one teleostean fish. Ten captive Atlantic wolffish (Anarhichas lupus)from the Montreal Biodome were submitted for necropsy and their pancreata were collected.

RESULTS

Grossly, all the fish pancreata examined contained 1-3 nodules of variable diameter (1-8 mm). Microscopically, the nodules were uniform, highly cellular, and composed of polygonal to elongated cells. Immunofluorescence for pancreatic hormones was performed. The nodules were immunoreactive for insulin most prominent centrally, but with IAPP and glucagon only in the periphery of the nodules. Exocrine pancreas was positive for chromogranin A. Not previously recognized in fish, IAPP immunoreactivity occurred in α, glucagon-containing, cells and did not co-localize with insulin in β cells. The islet tissues were devoid of amyloid deposits. IAPP DNA sequencing was performed to compare the sequence among teleost fish and the potency to form amyloid fibrils. In silico analysis of the amino acid sequences 19-34 revealed that it was not amyloidogenic.

CONCLUSIONS

Amyloidosis of pancreatic islets would not be expected as a spontaneous disease in the Atlantic wolffish. Our study underlines that this teleost fish is a potential candidate for pancreatic xenograft research.

microRNAs in Pancreatic β-Cell Physiology

The β-cells within the pancreas are responsible for production and secretion of insulin. Insulin is released from pancreatic β-cells in response to increasing blood glucose levels and acts on insulin-sensitive tissues such as skeletal muscle and liver in order to maintain normal glucose homeostasis. Therefore, defects in pancreatic β-cell function lead to hyperglycemia and diabetes mellitus. A new class of molecules called microRNAs has been recently demonstrated to play a crucial role in regulation of pancreatic β-cell function under normal and pathophysiological conditions. miRNAs have been shown to regulate endocrine pancreas development, insulin biosynthesis, insulin exocytosis, and β-cell expansion. Many of the β-cell enriched miRNAs have multiple functions and regulate pancreas development as well as insulin biosynthesis and exocytosis. Furthermore, several of the β-cell specific miRNAs have been shown to accumulate in the circulation before the onset of diabetes and may serve as potential biomarkers for prediabetes. This chapter will focus on miRNAs that are enriched in pancreatic β-cells and play a critical role in modulation of β-cell physiology and may have clinical significance in the treatment of diabetes.

An immunohistochemical study of the endocrine pancreas in raptors

The cytoarchitecture of the endocrine pancreas of 10 raptors (golden eagles, peregrine falcons, Saker falcon, turkey vultures, red-tailed hawk and unspecified falcon) was examined by immunohistochemistry. Three islet types were identified: type A mixed islets composed mainly by glucagon (A)-secreting cells, type B mixed islets with predominantly insulin (B)-secreting cell component and type M mixed islets (type M) consisting of variable number of glucagon-, insulin- and somatostatin (D)-secreting cells. The latter were further characterized into Type I, II or III according to the cell distribution of the three cell types. A and D cells were also randomly scattered within the exocrine pancreas. The results of this study suggest that the classical concept in birds of a segregation of A and B cells in well-defined and distinct islets is not applicable in raptors, reflecting an evolutionary adaptation to different dietary habits and variation in developmental mechanisms.

Keratin 8 modulates β-cell stress responses and normoglycaemia

Keratin intermediate filament (IF) proteins are epithelial cell cytoskeletal components that provide structural stability and protection from cell stress, among other cellular and tissue-specific functions. Numerous human diseases are associated with IF gene mutations, but the function of keratins in the endocrine pancreas and their potential significance for glycaemic control are unknown. The impact of keratins on β-cell organisation and systemic glucose control was assessed using keratin 8 (K8) wild-type (K8(+/+)) and K8 knockout (K8(-/-)) mice. Islet β-cell keratins were characterised under basal conditions, in streptozotocin (STZ)-induced diabetes and in non-obese diabetic (NOD) mice. STZ-induced diabetes incidence and islet damage was assessed in K8(+/+) and K8(-/-) mice. K8 and K18 were the predominant keratins in islet β-cells and K8(-/-) mice expressed only remnant K18 and K7. K8 deletion resulted in lower fasting glucose levels, increased glucose tolerance and insulin sensitivity, reduced glucose-stimulated insulin secretion and decreased pancreatic insulin content. GLUT2 localisation and insulin vesicle morphology were disrupted in K8(-/-) β-cells. The increased levels of cytoplasmic GLUT2 correlated with resistance to high-dose STZ-induced injury in K8(-/-) mice. However, K8 deletion conferred no long-term protection from STZ-induced diabetes and prolonged STZ-induced stress caused increased exocrine damage in K8(-/-) mice. β-cell keratin upregulation occurred 2 weeks after treatments with low-dose STZ in K8(+/+) mice and in diabetic NOD mice, suggesting a role for keratins, particularly in non-acute islet stress responses. These results demonstrate previously unrecognised functions for keratins in β-cell intracellular organisation, as well as for systemic blood glucose control under basal conditions and in diabetes-induced stress.

Comparative analysis of pancreatic changes in aged rats fed life long with sunflower, fish, or olive oils

An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. We aimed to study the effect of oil consumption on pancreas histology in order to find aging-related signs. To this end, three groups of rats were fed an isocaloric diet for 2 years, where virgin olive, sunflower, or fish oil was included. Pancreatic samples for microscopy and blood samples were collected at the moment of sacrifice. As a result, the sunflower oil-fed rats presented higher β-cell numbers and twice the insulin content than virgin olive oil-fed animals. In addition, rats fed with fish oil developed acinar fibrosis and macrophage infiltrates in peri-insular regions, compared with counterparts fed with virgin olive oil. Inflammation signs were less prominent in the sunflower group. The obtained data emphasize the importance of dietary fatty acids in determining pancreatic structure.