Pancreatic Polypeptide Cells Research Articles

Development of Islet Organoids from H9 Human Embryonic Stem Cells in Biomimetic 3D Scaffolds.

Success in the differentiating human embryonic stem cells (hESCs) into insulin-secreting β cells raises new hopes for diabetes treatment. In this work, we demonstrated the feasibility of developing islet organoids from hESCs within biomimetic 3D scaffolds. We showed that such a 3D microenvironment is critical to the generation of pancreatic endoderm and endocrine from hESCs. The organoids formed consisted of pancreatic α, β, δ, and pancreatic polypeptide (PP) cells. A high-level co-expression of PDX1, NKX6.1, and NGN3 in these cells suggests the characteristics of pancreatic β cells. More importantly, most insulin-secreting cells generated did not express glucagon, somatostatin, or PP. The expression of mature β cell marker genes such as Pdx1, Ngn3, Insulin, MafA, and Glut2 was detected in these 3D-induced cell clusters. A high-level expression of C-peptide confirmed the de novo endogenous insulin production in these 3D induced cells. Insulin-secretory granules, an indication of β cell maturity, were detected in these cells as well. Glucose challenging experiments suggested that these cells are sensitive to glucose levels due to their elevated maturity. Exposing the cells to a high concentration of glucose induced a sharp increase in insulin secretion.

Influence of neuropeptide Y and pancreatic polypeptide on islet function and beta-cell survival

BackgroundIn the present study we assessed the impact of neuropeptide Y receptor (NPYR) modulators, neuropeptide Y (NPY) and pancreatic polypeptide (PP), on islet function and beta-cell survival. MethodsThe effects of NPY and PP on beta-cell function were examined in BRIN BD11 and 1.1B4 beta-cells, as well as isolated mouse islets. Involvement of both peptides in pancreatic islet adaptations to streptozotocin and hydrocortisone, as well as effects on beta-cell proliferation and apoptosis was also evaluated. ResultsNeither NPY nor PP affected in vivo glucose disposal or insulin secretion in mice. However, both peptides inhibited (p<0.05 to p<0.001) glucose stimulated insulin secretion from rat and human beta-cells. NPY exerted similar insulinostatic effects in isolated mouse islets. NPY and PP inhibited alanine-induced changes in BRIN BD11 cell membrane potential and (Ca2+)i. Streptozotocin treatment decreased and hydrocortisone treatment increased beta-cell mass in mice. In addition, streptozotocin, but not hydrocortisone, increased PP cell area. Streptozotocin also shifted the normal co-localisation of NPY with PP, towards more pronounced co-expression with somatostatin in delta-cells. Both streptozotocin and hydrocortisone increased pancreatic exocrine expression of NPY. More detailed in vitro investigations revealed that NPY, but not PP, augmented (p<0.01) BRIN BD11 beta-cell proliferation. In addition, both peptides exerted protective effects against streptozotocin-induced DNA damage in beta-cells. ConclusionThese data emphasise the involvement of PP, and particularly NPY, in the regulation of beta-cell mass and function. General significanceModulation of PP and NPY signalling is suitable for further evaluation and possible clinical development for the treatment of diabetes.

Physiological Uptake in the Pancreatic Head on Somatostatin Receptor Scintigraphy Using [111In-DTPA]Octreotide: Incidence and Mechanism.

Physiological uptake in the uncinate process or pancreatic head has been described with Ga-labeled PET tracers for somatostatin receptor imaging. In-DTPA-octreotide is the only registered radiopharmaceutical for the imaging of neuroendocrine tumors. We studied the uptake in this region of the pancreatic head on somatostatin receptor scintigraphy (SRS) using In-DTPA-octreotide in a large group of patients. Furthermore, known physiological and clinical characteristics are discussed in an attempt to elucidate this phenomenon. Four hundred seven patients underwent SRS using In-DTPA-octreotide in our department in 2014. After excluding patients with a known malignancy in or close to the pancreas, as well as all scans without SPECT/CT of the upper abdomen, we reviewed 178 scans in total. The uptake was graded on a 4-point scale that correlates the uptake in the pancreatic head to physiological uptake in the liver. Uptake in the region of the pancreatic head, including the uncinate process, was seen in 46 (26%) of 178 patients on SPECT/CT and in 12 patients (7%) on planar imaging. On SPECT/CT, uptake was lower than the liver in 26 patients (15%), equal to the liver in 17 patients (10%), and higher than the liver in 3 patients (2%). In patients with diabetes mellitus (DM), the incidence of uptake in the pancreatic head was 50% on SPECT/CT. Physiological uptake in the pancreatic head is seen on SPECT/CT with In-DTPA-octreotide in 26% of patients, and the incidence is doubled in patients with DM. Previous case reports showed uptake in the pancreatic head due to histologically proven pancreatic polypeptide (PP) cell hyperplasia. Also, patients with DM have elevated serum PP concentrations, which is likely due to PP cell hyperplasia. Because 90% of PP cells are present in the pancreatic head, PP cell hyperplasia is the most likely explanation for visualization of the pancreatic head on SRS in a substantial number of patients.

Use of the Fluidigm C1 platform for RNA sequencing of single mouse pancreatic islet cells

This study provides an assessment of the Fluidigm C1 platform for RNA sequencing of single mouse pancreatic islet cells. The system combines microfluidic technology and nanoliter-scale reactions. We sequenced 622 cells, allowing identification of 341 islet cells with high-quality gene expression profiles. The cells clustered into populations of α-cells (5%), β-cells (92%), δ-cells (1%), and pancreatic polypeptide cells (2%). We identified cell-type-specific transcription factors and pathways primarily involved in nutrient sensing and oxidation and cell signaling. Unexpectedly, 281 cells had to be removed from the analysis due to low viability, low sequencing quality, or contamination resulting in the detection of more than one islet hormone. Collectively, we provide a resource for identification of high-quality gene expression datasets to help expand insights into genes and pathways characterizing islet cell types. We reveal limitations in the C1 Fluidigm cell capture process resulting in contaminated cells with altered gene expression patterns. This calls for caution when interpreting single-cell transcriptomics data using the C1 Fluidigm system.

Pancreatic polypeptide responses to isoglycemic oral and intravenous glucose in humans with and without intact vagal innervation

Abstract Secretion of pancreatic polypeptide (PP) from the pancreatic PP cells is controlled partly by vagal mechanisms. Release is stimulated by cephalic stimulation and enteral but not parenteral nutrients. Ambient glucose levels modulate circulating PP levels as hypoglycemia stimulates while hyperglycemia inhibits secretion. The glucose sensing mechanism has yet to be determined but may involve a vagal pathway. To investigate the role of enteral stimuli with or without intact vagal innervation, while controlling for the glucose excursion caused by the OGTT, we measured PP plasma levels by an in-house radioimmunoassay in truncally vagotomized (n=15) and control individuals ( n = 10). All participants were studied by a 50-g oral glucose tolerance test (OGTT) with or without dipeptidyl peptidase 4 (DPP-4) inhibition (DPP-4i) and a subsequent isoglycemic intravenous glucose infusion (IGII). We included measurements from the DPP-4i day to determine the potential effect of DPP-4-cleaved peptides on PP secretion. In both vagotomized and controls, oral glucose elicited PP secretion. In controls, but not in the vagotomized participants, intravenous glucose significantly inhibited PP secretion suggesting a vagal glucose sensing mechanism dependent on intact vagal innervation. DPP-4i did not alter PP secretion in either group.

Research Resource: A Chromogranin A Reporter for Serotonin and Histamine Secreting Enteroendocrine Cells.

Chromogranin A (ChgA) is an acidic protein found in large dense-core secretory vesicles and generally considered to be expressed in all enteroendocrine cells of the gastrointestinal (GI) tract. Here, we characterize a novel reporter mouse for ChgA, ChgA-humanized Renilla reniformis (hr)GFP. The hrGFP reporter was found in the monoamine-storing chromaffin cells of the adrenal medulla, where ChgA was originally discovered. hrGFP also was expressed in enteroendocrine cells throughout the GI tract, faithfully after the expression of ChgA, as characterized by immunohistochemistry and quantitative PCR analysis of fluorescence-activated cell sorting-purified cells, although the expression in the small intestine was weak compared with that of the stomach and colon. In the stomach, hrGFP was highly expressed in almost all histamine-storing enterochromaffin (EC)-like cells, at a lower level in the majority of serotonin-storing EC cells and ghrelin cells, in a small fraction of somatostatin cells, but was absent from gastrin cells. In the small intestine, the hrGFP reporter was selectively, but weakly expressed in EC cells, although not in any peptide-storing enteroendocrine cells. In the colon, hrGFP was exclusively expressed in EC cells but absent from the peptide-storing enteroendocrine cells. In contrast, in the pancreas, hrGFP was expressed in β-cells, α-cells, and a fraction of pancreatic polypeptide cells. It is concluded that ChgA-hrGFP in the GI tract functions as an effective reporter, particularly for the large populations of still poorly characterized monoamine-storing enteroendocrine cells. Furthermore, our findings substantiate the potential function of ChgA as a monoamine-binding protein that facilitates the regulated endocrine secretion of large amounts of monoamines from enteroendocrine cells.

Alpha-, Delta- and PP-cells: Are They the Architectural Cornerstones of Islet Structure and Co-ordination?

Islet non-β-cells, the α- δ- and pancreatic polypeptide cells (PP-cells), are important components of islet architecture and intercellular communication. In α-cells, glucagon is found in electron-dense granules; granule exocytosis is calcium-dependent via P/Q-type Ca(2+)-channels, which may be clustered at designated cell membrane sites. Somatostatin-containing δ-cells are neuron-like, creating a network for intra-islet communication. Somatostatin 1-28 and 1-14 have a short bioactive half-life, suggesting inhibitory action via paracrine signaling. PP-cells are the most infrequent islet cell type. The embryologically separate ventral pancreas anlage contains PP-rich islets that are morphologically diffuse and α-cell deficient. Tissue samples taken from the head region are unlikely to be representative of the whole pancreas. PP has anorexic effects on gastro-intestinal function and alters insulin and glucagon secretion. Islet architecture is disrupted in rodent diabetic models, diabetic primates and human Type 1 and Type 2 diabetes, with an increased α-cell population and relocation of non-β-cells to central areas of the islet. In diabetes, the transdifferentiation of non-β-cells, with changes in hormone content, suggests plasticity of islet cells but cellular function may be compromised. Understanding how diabetes-related disordered islet structure influences intra-islet cellular communication could clarify how non-β-cells contribute to the control of islet function.

Pancreatic polypeptide responses to isoglycemic oral and intravenous glucose in humans with and without intact vagal innervation

Secretion of pancreatic polypeptide (PP) from the pancreatic PP cells is controlled partly by vagal mechanisms. Release is stimulated by cephalic stimulation and enteral but not parenteral nutrients. Ambient glucose levels modulate circulating PP levels as hypoglycemia stimulates while hyperglycemia inhibits secretion. The glucose sensing mechanism has yet to be determined but may involve a vagal pathway. To investigate the role of enteral stimuli with or without intact vagal innervation, while controlling for the glucose excursion caused by the OGTT, we measured PP plasma levels by an in-house radioimmunoassay in truncally vagotomized (n=15) and control individuals (n=10). All participants were studied by a 50-g oral glucose tolerance test (OGTT) with or without dipeptidyl peptidase 4 (DPP-4) inhibition (DPP-4i) and a subsequent isoglycemic intravenous glucose infusion (IGII). We included measurements from the DPP-4i day to determine the potential effect of DPP-4-cleaved peptides on PP secretion. In both vagotomized and controls, oral glucose elicited PP secretion. In controls, but not in the vagotomized participants, intravenous glucose significantly inhibited PP secretion suggesting a vagal glucose sensing mechanism dependent on intact vagal innervation. DPP-4i did not alter PP secretion in either group.

Pancreas-Specific Sirt1-Deficiency in Mice Compromises Beta-Cell Function without Development of Hyperglycemia.

Aims/HypothesisSirtuin 1 (Sirt1) has been reported to be a critical positive regulator of glucose-stimulated insulin secretion in pancreatic beta-cells. The effects on islet cells and blood glucose levels when Sirt1 is deleted specifically in the pancreas are still unclear.MethodsThis study examined islet glucose responsiveness, blood glucose levels, pancreatic islet histology and gene expression in Pdx1Cre; Sirt1ex4F/F mice that have loss of function and loss of expression of Sirt1 specifically in the pancreas.ResultsWe found that in the Pdx1Cre; Sirt1ex4F/F mice, the relative insulin positive area and the islet size distribution were unchanged. However, beta-cells were functionally impaired, presenting with lower glucose-stimulated insulin secretion. This defect was not due to a reduced expression of insulin but was associated with a decreased expression of the glucose transporter Slc2a2/Glut2 and of the Glucagon like peptide-1 receptor (Glp1r) as well as a marked down regulation of endoplasmic reticulum (ER) chaperones that participate in the Unfolded Protein Response (UPR) pathway. Counter intuitively, the Sirt1-deficient mice did not develop hyperglycemia. Pancreatic polypeptide (PP) cells were the only other islet cells affected, with reduced numbers in the Sirt1-deficient pancreas.Conclusions/InterpretationThis study provides new mechanistic insights showing that beta-cell function in Sirt1-deficient pancreas is affected due to altered glucose sensing and deregulation of the UPR pathway. Interestingly, we uncovered a context in which impaired beta-cell function is not accompanied by increased glycemia. This points to a unique compensatory mechanism. Given the reduction in PP, investigation of its role in the control of blood glucose is warranted.

Tuning to the right signal

Pancreatic beta cells are clustered in islets of Langerhans together with alpha cells in an arrangement that facilitates the tight coordination of insulin and glucagon secretion at the source of their release. Other secretory cells, including somatostatin-secreting delta cells and pancreatic polypeptide cells, co-localise with alpha and beta cells in the islet and serve to modulate islet endocrine output. A multitude of non-secretory cell types, including endothelial cells, pericytes, stromal cells, glial cells and macrophages, complete the cellular make up of the islet, which is further enhanced by (para)sympathetic nerve terminals that impinge on the islets via neurotransmitters released in the islet microenvironment. While this islet architecture is relatively simple compared with the vast complexity of the central nervous system, the constellation of cell types united in the islet nevertheless provides a rich substrate for local paracrine and autocrine interactions that affect diverse aspects of islet physiology, ranging from the modulation of hormone secretion to the regulation of islet cell mass via proliferation and death. In this issue of Diabetologia (DOI: 10.1007/s00125-015-3552-5 ), Yang et al take the notion of rich crosstalk within the islet as their point of departure for a systematic evaluation of the beta cell-protective properties of an extensive panel of over 200 factors, with some surprising and highly interesting results, as discussed in this commentary.

Expression pattern of 12-lipoxygenase in human islets with type 1 diabetes and type 2 diabetes.

Inflammation in the pancreas can cause β-cell stress, leading to diabetes development. Access to human pancreas tissues via the Network for Pancreatic Organ Donors with Diabetes (nPOD) has allowed characterization of pathways leading to this inflammation. 12-Lipoxygenase (12-LO) induces inflammation and has been implicated in diabetes development. Our goal was to determine expression of 12-LO in human islets from control, autoantibody-positive, type 1 diabetic, and type 2 diabetic nPOD pancreas donors. Pancreas tissues from nPOD donors were examined by immunohistochemistry and immunofluorescence for islet expression of 12-LO in different subsets of islet cells. Donor pancreas samples were obtained from nPOD based on disease status (control, n = 7; autoantibody-positive, n = 8; type 1 diabetic, n = 17; or type 2 diabetic donors, n = 15). Determination of 12-LO expression within human islets served as the main outcome measure, including distinguishing which types of islet cells expressed 12-LO. Islets from control participants (nondiabetic) lacked islet expression of 12-LO. Of donors in the other groups, 25% to 37% expressed islet 12-LO with a clear inverse relation between the numbers of β-cells and 12-LO(+) cells within islets of 12-LO(+) cases. 12-LO expression was not seen within macrophages, endothelial cells, α-cells, or β-cells, but only within cells expressing low levels of pancreatic polypeptide (PP) and increased levels of vimentin. 12-LO expression colocalizes within a specific type of islet PP(+) cell under prediabetic and diabetic conditions. The costaining of PP and vimentin suggests that 12-LO participates in the process leading to β-cell dedifferentiation in the islet.

Identification and localization of gastrointestinal hormones in the skin of the bullfrog Rana catesbeiana during periods of activity and hibernation

Amphibian skin and its secretions contain a wide variety of biogenic amines and biologically active peptides, some of which are either identical or highly homologous to gastrointestinal hormones (GHs) of higher vertebrates. This study investigated the distribution density and immunoreactive (IR) intensity of 5-hydroxytryptamine (5-HT), gastrin (GAS), somatostatin (SS), pancreatic polypeptide (PP), neuropeptide Y (NPY) and glucagon (GLU) IR cells in the skin of the bullfrog Rana catesbeiana during periods of activity and hibernation. The results indicated that the six types of GHs were all present in the bullfrog skin and were most predominant in the epidermis and mucous glands. In dorsal skin, the density of the GHs-IR cells in mucous glands was higher than that in epidermis except for GAS-IR cells. In ventral skin, the density of 5-HT, PP and NPY-IR cells in mucous glands was also higher than that in the epidermis. During hibernation, the density of the six types of GHs-IR cells and the IR intensity of GAS, SS, NPY and GLU-IR cells in the epidermis of dorsal skin increased significantly. The IR intensity of SS, PP and NPY-IR cells in granular glands of ventral skin also increased significantly during hibernation. These results suggested that multiple types of GHs-IR cells present in the skin of R. catesbeiana, may play important roles in the regulation of the physiological functions of skin. Also, adaptive changes in the density and IR intensity of GHs-IR cells occurred during hibernation.

Activation of GPR119 by fatty acid agonists augments insulin release from clonal β-cells and isolated pancreatic islets and improves glucose tolerance in mice

G-protein coupled receptor 119 (GPR119) is emerging as a potential target for the treatment of type 2 diabetes with beneficial effects on glucose homeostasis. This study assessed the insulin-secreting properties of various GPR119 agonists and the distribution of GPR119 in pancreatic islets. Endogenous ligands [oleoylethanolamide (OEA), palmitoylethanolamine (PEA)] and chemically synthetic analogues (AS-1269574, PSN-375963) were investigated in clonal BRIN-BD11 cells and mouse pancreatic islets. Secondary messenger assays such as intracellular Ca²⁺ and cAMP in response to agonists at normoglycaemic and hyperglycaemic conditions were assessed. Cytotoxicity was assessed by LDH release. AS-1269574 was the most potent and selective agonist tested in isolated islets, with an EC₅₀ value of 9.7×10⁻⁷ mol/l, enhancing insulin release maximally by 63.2%. Stimulation was also observed with GPR119 ligands; OEA (3.0×10⁻⁶ mol/l; 37.5%), PSN-375963 (2.4×10⁻⁶ mol/l; 28.7%) and PEA (1.2×10⁻⁶ mol/l; 22.2%). Results were corroborated by studies using BRIN-BD11 cells, which revealed augmentation of intracellular Ca²⁺ and cAMP. Both OEA and AS-1269574 enhanced insulin release and improved glucose tolerance in vivo in NIH Swiss mice. These results demonstrate the cellular localisation of GPR119 on islet cells (β and pancreatic polypeptide cells), its activation of the β-cell stimulus-secretion coupling pathway and glucose lowering effects in vivo.

New perspectives of vesicular monoamine transporter 2 chemical characteristics in mammals and its constant expression in type 1 diabetes rat models

Vesicular monoamine transporter 2 (VMAT2) has been exploited as a biomarker of β-cell mass in human islets. However, a current report suggested no immunoreactivity of VMAT2 in the β cells of rat islets. To investigate the cellular localization of VMAT2 in islets further, the pancreatic tissues from monkeys and humans were compared with those of rats and mice. The study was performed using among-species comparisons and a type 1 diabetes model (T1DM) for rats by Western blotting, double-label immunofluorescence, and confocal laser scanning microscopy. We found that VMAT2-immunoreactivity (IR) was distributed peripherally in the islets of rodents, but was widely scattered throughout the islets of primates. Consistent with rodent islets, VMAT2-IR did not exist in insulin (INS)-IR cells but was abundantly present in glucagon (GLU)-IR and pancreatic polypeptide (PP)-IR cells in monkey and human islets. VMAT2-IR had no colocalization with INS-IR in any part of the rat pancreas (head, body, and tail). INS-IR cells were reduced dramatically in T1DM rat islets, but no significant alteration in the proportion of VMAT2-IR cells and GLU-IR cells was observed. Furthermore, a strong colocalization of VMAT2-IR with GLU-IR was distributed in the peripheral regions of diabetic islets. For the first time, the current study demonstrates the presence of VMAT2 in α cells and PP cells but not in β cells in the islets of monkeys and humans. This study provides convinced morphologic evidence that VMAT2 is not present in β cells. There needs to be studies for new markers for β cell mass.

Vesicular monoamine transporter, type 2 (vmat2) expression as it compares to insulin and pancreatic polypeptide in the head, body and tail of the human pancreas

The vesicular monoamine transporter, type 2 (VMAT2) is responsible for sequestering monoamine neurotransmitters into exocytic vesicles in neurons, enterochromaffin-like cells of the stomach and cells arising from the common myeloid progenitor. VMAT2 is also present in the pancreas and is expressed by insulin producing β cells, but not by glucagon or somatostatin expressing islet cells. Positron emission tomography (PET) targeting of VMAT2 is currently being evaluated as a non-invasive tool to measure β cell mass (BCM) in living humans. In recent trials, PET measurements of VMAT2 in the pancreas overestimated BCM in type 1 diabetes (T1D) patients predicted to have little to no BCM by metabolic measures. Recently, tissue immunohistochemistry studies suggested that VMAT2 staining may also co-localize with pancreatic polypeptide (PP) staining cells in pancreas tissue, but these studies were not quantitative. In this report, we evaluated VMAT2 specificity for β cells in sub-regions of the human pancreas using antibodies targeting VMAT2, insulin and PP by double-label immunofluorescence. Immunostaining for VMAT2 and insulin demonstrated 89 ± 8% overlap in the body and tail of the pancreas. However, 44 ± 12% and 53 ± 15% of VMAT2 cells co-stained with PP- and insulin-staining cells, respectively in the pancreatic head. Significant co-staining for VMAT2 and PP cells in the head of the pancreas may partly explain the apparent overestimation of BCM in T1D by PET. Specific targeting of the pancreatic body and tail using VMAT2 PET scanning may reflect BCM more accurately.

Expression of the coiled coil domain containing protein 116 in the pancreatic islets and endocrine pancreatic tumors

Aims: Coiled coil domain containing protein 116 (CCDC116) is a product of the gene coiled coil domain containing 116 located on human chromosome 22. Its function has not yet been established. The present study focuses on the expression of this protein in human pancreatic islets and in the endocrine pancreatic tumors (EPTs). Methods and Results: Expression of the protein was evaluated by immunohistochemistry in endocrine pancreas from six patients and in various EPTs from 51 patients. In pancreatic islets, virtually all insulin, approx. 75% of the somatostatin, and approx. 60% of the pancreatic polypeptide (PP) cells were immunoreactive for the CCDC116 protein whereas glucagon, ghrelin and the exocrine cells were not. All insulinomas, gastrinomas, non-functioning sporadic tumors and the hereditary multihormonal EPTs were immunoreactive with variable relative incidence. Two of the three somatostatinomas, and one of the three ACTH-secreting tumors also expressed CCDC116. Conclusions: The CCDC116 protein is expressed in all islet cell types except the glucagon and ghrelin cells. Most of the EPTs also contained CCDC116 protein. These findings suggest that this protein may play some role for the above mentioned endocrine cells and tumors. Its function has to be investigated in future studies.

Staining Protocols for Human Pancreatic Islets

Estimates of islet area and numbers and endocrine cell composition in the adult human pancreas vary from several hundred thousand to several million and beta mass ranges from 500 to 1500 mg. With this known heterogeneity, a standard processing and staining procedure was developed so that pancreatic regions were clearly defined and islets characterized using rigorous histopathology and immunolocalization examinations. Standardized procedures for processing human pancreas recovered from organ donors are described in part 1 of this series. The pancreas is processed into 3 main regions (head, body, tail) followed by transverse sections. Transverse sections from the pancreas head are further divided, as indicated based on size, and numbered alphabetically to denote subsections. This standardization allows for a complete cross sectional analysis of the head region including the uncinate region which contains islets composed primarily of pancreatic polypeptide cells to the tail region. The current report comprises part 2 of this series and describes the procedures used for serial sectioning and histopathological characterization of the pancreatic paraffin sections with an emphasis on islet endocrine cells, replication, and T-cell infiltrates. Pathology of pancreatic sections is intended to characterize both exocrine, ductular, and endocrine components. The exocrine compartment is evaluated for the presence of pancreatitis (active or chronic), atrophy, fibrosis, and fat, as well as the duct system, particularly in relationship to the presence of pancreatic intraductal neoplasia. Islets are evaluated for morphology, size, and density, endocrine cells, inflammation, fibrosis, amyloid, and the presence of replicating or apoptotic cells using H&E and IHC stains. The final component described in part 2 is the provision of the stained slides as digitized whole slide images. The digitized slides are organized by case and pancreas region in an online pathology database creating a virtual biobank. Access to this online collection is currently provided to over 200 clinicians and scientists involved in type 1 diabetes research. The online database provides a means for rapid and complete data sharing and for investigators to select blocks for paraffin or frozen serial sections.

Immunohistochemical localization of somatostatin and pancreatic polypeptide in smokers with chronic pancreatitis

Recent studies have demonstrated a significant role of tobacco smoking in the development of chronic pancreatitis. Although there are published papers on the effects of cigarette smoking on insulin secretion in patients, no data are available on the effects of smoking on pancreatic endocrine cells secreting somatostatin and pancreatic polypeptide. The aim of the study was to evaluate the effects of cigarette smoking on endocrine pancreatic function by immunolocalization of somatostatin and pancreatic polypeptide in the pancreas from smokers and non-smoking patients with chronic pancreatitis in comparison with healthy controls. The LSAB2-HRP technique with polyclonal antibodies was used for the immunolocalization of somatostatin and pancreatic polypeptide in histological preparations of the pancreas. The intensity of immunohistochemical reaction was calculated with digital image analysis. The study demonstrated increased numbers of somatostatin (D) secreting cells and pancreatic polypeptide (PP) cells and their altered location in pancreatic islets and parenchyma of smoking patients with chronic pancreatitis, as compared to non-smoking patients and healthy controls. Smoking patients showed significantly higher immunostaining of the hormones in the pancreas compared to non-smoking patients and healthy persons. This study indicates that smoking may play a significant role in the development of endocrine disturbances in the development of chronic pancreatitis.

Low densities of serotonin and peptide YY cells in the colon of patients with irritable bowel syndrome.

BackgroundThe gut hormones are important in regulating gastrointestinal motility. Disturbances in gastrointestinal motility have been reported in patients with irritable bowel syndrome (IBS). Reduced endocrine cell density, as revealed by chromogranin A, has been reported in the colon of IBS patients.AimsTo investigate a possible abnormality in the colonic endocrine cells of IBS patients.MethodsA total of 41 patients with IBS according to Rome Criteria III and 20 controls were included in the study. Biopsies from the right and left colon were obtained from both patients and controls during colonoscopy. The biopsies were immunostained for serotonin, peptide YY (PYY), pancreatic polypeptide (PP), entroglucagon, and somatostatin cells. Cell densities were quantified by computerized image analysis.ResultsSerotonin and PYY cell densities were reduced in the colon of IBS patients. PP, entroglucagon, and somatostatin-immunoreactive cells were too few to enable reliable quantification.ConclusionThe cause of these observations could be primary genetic defect(s), secondary to altered serotonin and/or PYY signaling systems and/or subclinical inflammation. Serotonin activates the submucosal sensory branch of the enteric nervous system and controls gastrointestinal motility and chloride secretion via interneurons and motor neurons. PYY stimulates absorption of water and electrolytes, and inhibits prostaglandin (PG) E2, and vasoactive intestinal peptide, which stimulates intestinal fluid secretion and is a major regulator of the “ileal brake”. Although the cause and effect relationship of these findings is difficult to elucidate, the abnormalities reported here might contribute to the symptoms associated with IBS.

Transcriptional regulation of α‐cell differentiation

The development of the endocrine pancreas and the differentiation of its five cell types, α, β, δ, ε and pancreatic polypeptide (PP) cells, are a highly complex and tightly regulated process. Proper differentiation and function of α- and β-cells are critical for blood glucose homeostasis. These processes are governed by multiple transcription factors and other signalling systems, and its dysregulation results in diabetes. The differentiation of α-cells and the maintenance of α-cell function can be influenced at several stages during development and in the maturing islet. Many transcription factors, such as neurogenin 3 (Ngn3), pancreatic duodenal homeobox 1 (Pdx1) and regulatory factor x6 (Rfx6), play a crucial role in the determination of the endocrine cell fate, while other transcription factors, such as aristaless-related homeobox (Arx) and forkhead box A2 (Foxa2), are implicated in the initial or terminal differentiation of α-cells. In vivo and in vitro studies have shown that preproglucagon transcription, and therefore the maintenance of α-cell function, is regulated by several factors, including forkhead box A1 (Foxa1), paired box 6 (Pax6), brain4 (Brn4) and islet-1 (Isl-1). Detailed information about the regulation of normal and abnormal α-cell differentiation gives insight into the pathogenesis of diabetes, identifies further targets for diabetes treatment and provides clues for the reprogramming of α- to β-cells for replacement therapy.