Local Dialogues Between the Endocrine and Exocrine Cells in the Pancreas

For many years, it has been taught in medical textbooks that the endocrine and exocrine parts of the pancreas have separate blood supplies that do not mix. Therefore, they have been studied by different scientific communities, and patients with pancreatic disorders are treated by physicians in different medical disciplines, where endocrine and exocrine function are the focus of endocrinologists and gastroenterologists, respectively. The conventional model that every islet in each pancreatic lobule receives a dedicated arterial blood supply was first proposed in 1932, and it has been inherited to date. Recently, in vivo intravital recording of red blood cell flow in mouse islets as well as in situ structural analysis of 3D pancreatic vasculature from hundreds of islets provided evidence for preferentially integrated pancreatic blood flow in six mammalian species. The majority of islets have no association with the arteriole, and there is bidirectional blood exchange between the two segments. Such vascularization may allow an entire downstream region of islets and acinar cells to be simultaneously exposed to a topologically and temporally specific plasma content, which could underlie an adaptive sensory function as well as common pathogeneses of both portions of the organ in pancreatic diseases, including diabetes.

ARTICLE HIGHLIGHTS

Aging Associates with Cilium Elongation and Dysfunction in Kidney and Pancreas

Cilia are best known and most studied for their manifold functions enabling proper embryonic development. Loss of cilia or dysfunction thereof results in a great variety of congenital malformations and syndromes. However, there are also cilia-driven conditions, which manifest only later in life, such as polycystic kidney disease. Even degenerative diseases in the central nervous system have recently been linked to alterations in cilia biology. Surprisingly though, there is very little knowledge regarding cilia in normally aged organisms absent any disease. Here, it is provided evidence that cilia in naturally aged mice are considerably elongated in the kidney and pancreas, respectively. Moreover, such altered cilia appear to have become dysfunctional as indicated by changes in cellular signaling.

Aquaporins in Glandular Secretion

Exocrine and endocrine glands deliver their secretory product, respectively, at the surface of the target organs or within the bloodstream. The release of their products has been shown to rely on secretory mechanisms often involving aquaporins (AQPs). This chapter will provide insight into the role of AQPs in secretory glands located within the gastrointestinal tract, including salivary glands, gastric glands, duodenal Brunner's glands, liver, gallbladder, intestinal goblets cells, and pancreas, as well and in other parts of the body, including airway submucosal glands, lacrimal glands, mammary glands, and eccrine sweat glands. The involvement of AQPs in both physiological and pathophysiological conditions will also be highlighted.

Distinct Adipogenic and Fibrogenic Differentiation Capacities of Mesenchymal Stromal Cells from Pancreas and White Adipose Tissue

Pancreatic steatosis associates with β-cell failure and may participate in the development of type-2-diabetes. Our previous studies have shown that diabetes-susceptible mice accumulate more adipocytes in the pancreas than diabetes-resistant mice. In addition, we have demonstrated that the co-culture of pancreatic islets and adipocytes affect insulin secretion. The aim of this current study was to elucidate if and to what extent pancreas-resident mesenchymal stromal cells (MSCs) with adipogenic progenitor potential differ from the corresponding stromal-type cells of the inguinal white adipose tissue (iWAT). miRNA (miRNome) and mRNA expression (transcriptome) analyses of MSCs isolated by flow cytometry of both tissues revealed 121 differentially expressed miRNAs and 1227 differentially expressed genes (DEGs). Target prediction analysis estimated 510 DEGs to be regulated by 58 differentially expressed miRNAs. Pathway analyses of DEGs and miRNA target genes showed unique transcriptional and miRNA signatures in pancreas (pMSCs) and iWAT MSCs (iwatMSCs), for instance fibrogenic and adipogenic differentiation, respectively. Accordingly, iwatMSCs revealed a higher adipogenic lineage commitment, whereas pMSCs showed an elevated fibrogenesis. As a low degree of adipogenesis was also observed in pMSCs of diabetes-susceptible mice, we conclude that the development of pancreatic steatosis has to be induced by other factors not related to cell-autonomous transcriptomic changes and miRNA-based signals.

A Potential Synbiotic Strategy for the Prevention of Type 2 Diabetes: Lactobacillus paracasei JY062 and Exopolysaccharide Isolated from Lactobacillus plantarum JY039

The disturbance of intestinal microorganisms and the exacerbation of type 2 diabetes (T2D) are mutually influenced. In this study, the effect of exopolysaccharides (EPS) from Lactobacillus plantarum JY039 on the adhesion of Lactobacillus paracasei JY062 was investigated, as well as their preventive efficacy against T2D. The results showed that the EPS isolated from L. plantarum JY039 effectively improved the adhesion rate of L. paracasei JY062 to Caco-2 cells (1.8 times) and promoted the proliferation of L. paracasei JY062. In the mice experiment, EPS, L. paracasei JY062 and their complex altered the structure of the intestinal microbiota, which elevated the proportion of Bifidobacterium, Faecalibaculum, while inversely decreasing the proportion of Firmicutes, Muribaculaceae, Lachnospiraceae and other bacteria involved in energy metabolism (p < 0.01; p < 0.05); enhanced the intestinal barrier function; promoted secretion of the gut hormone peptide YY (PYY) and glucagon-like peptide-1 (GLP-1); and reduced inflammation by balancing pro-inflammatory factors IL-6, TNF-α and anti-inflammatory factor IL-10 (p < 0.01; p < 0.05). These results illustrate that EPS and L. paracasei JY062 have the synbiotic potential to prevent and alleviate T2D.

Cilia Action in Islets: Lessons From Mouse Models

Primary cilia as a signaling organelle have garnered recent attention as a regulator of pancreatic islet function. These rod-like sensors exist on all major islet endocrine cell types and transduce a variety of external cues, while dysregulation of cilia function contributes to the development of diabetes. The complex role of islet primary cilia has been examined using genetic deletion targeting various components of cilia. In this review, we summarize experimental models for the study of islet cilia and current understanding of mechanisms of cilia regulation of islet hormone secretion. Consensus from these studies shows that pancreatic cilia perturbation can cause both endocrine and exocrine defects that are relevant to human disease. We discuss future research directions that would further elucidate cilia action in distinct groups of islet cells, including paracrine and juxtacrine regulation, GPCR signaling, and endocrine-exocrine crosstalk.

Stem/progenitor cells in normal physiology and disease of the pancreas

Though embryonic pancreas progenitors are well characterised, the existence of stem/progenitor cells in the postnatal mammalian pancreas has been long debated, mainly due to contradicting results on regeneration after injury or disease in mice. Despite these controversies, sequencing advancements combined with lineage tracing and organoid technologies indicate that homeostatic and trigger-induced regenerative responses in mice could occur. The presence of putative progenitor cells in the adult pancreas has been proposed during homeostasis and upon different stress challenges such as inflammation, tissue damage and oncogenic stress. More recently, single cell transcriptomics has revealed a remarkable heterogeneity in all pancreas cell types, with some cells showing the signature of potential progenitors. In this review we provide an overview on embryonic and putative adult pancreas progenitors in homeostasis and disease, with special emphasis on in vitro culture systems and scRNA-seq technology as tools to address the progenitor nature of different pancreatic cells.

Chronic jetlag-induced alterations in pancreatic diurnal gene expression

Cell-autonomous circadian clocks exist in nearly every organ and function to maintain homeostasis through a complex series of transcriptional-translational feedback loops. The response of these peripheral clocks to external perturbations, such as chronic jetlag and shift work, has been extensively investigated. However, an evaluation of the effects of chronic jetlag on the mouse pancreatic transcriptome is still lacking. Herein, we report an evaluation of the diurnal variations encountered in the pancreatic transcriptome following exposure to an established chronic jetlag protocol. We found approximately 5.4% of the pancreatic transcriptome was rhythmic. Following chronic jetlag, we found the number of rhythmic transcripts decreased to approximately 3.6% of the transcriptome. Analysis of the core clock genes, which orchestrate circadian physiology, revealed that nearly all exhibited a shift in the timing of peak gene expression-known as a phase shift. Similarly, over 95% of the rhythmically expressed genes in the pancreatic transcriptome exhibited a phase shift, many of which were found to be important for metabolism. Evaluation of the genes involved in pancreatic exocrine secretion and insulin signaling revealed many pancreas-specific genes were also rhythmically expressed and several displayed a concomitant phase shift with chronic jetlag. Phase differences were found 9 days after normalization, indicating a persistent failure to reentrain to the new light-dark cycle. This study is the first to evaluate the endogenous pancreatic clock and rhythmic gene expression in whole pancreas over 48 h, and how the external perturbation of chronic jetlag affects the rhythmic expression of genes in the pancreatic transcriptome.

Tissue engineering and 3D printing of bioartificial pancreas for regenerative medicine in diabetes

Diabetes is a severe chronic disease worldwide. In various types of diabetes, the pancreatic beta cells fail to secrete sufficient insulin, at some point, to regulate blood glucose levels. Therefore, the replacement of dysfunctional pancreas, islets of Langerhans, or even the insulin-secreting beta cells facilitates physiological regulation of blood glucose levels. However, the current lack of sufficient donor human islets for cell replacement therapy precludes a routine and absolute cure for most of the existing diabetes cases globally. It is envisioned that tissue engineering of a bioartificial pancreas will revolutionize regenerative medicine and the treatment of diabetes. In this review, we discuss the anatomy and physiology of the pancreas, and identify the clinical considerations for engineering a bioartificial pancreas. Subsequently, we dissect the bioengineering problem based on the design of the device, the biomaterial used, and the cells involved. Last but not least, we highlight current tissue engineering challenges and explore potential directions for future work.

Spatio-temporal expression pattern and role of the tight junction protein MarvelD3 in pancreas development and function

Tight junction complexes are involved in the establishment and maintenance of cell polarity and the regulation of signalling pathways, controlling biological processes such as cell differentiation and cell proliferation. MarvelD3 is a tight junction protein expressed in adult epithelial and endothelial cells. In Xenopus laevis, MarvelD3 morphants present differentiation defects of several ectodermal derivatives. In vitro experiments further revealed that MarvelD3 couples tight junctions to the MEKK1-JNK pathway to regulate cell behaviour and survival. In this work, we found that MarvelD3 is expressed from early developmental stages in the exocrine and endocrine compartments of the pancreas, as well as in endothelial cells of this organ. We thoroughly characterized MarvelD3 expression pattern in developing pancreas and evaluated its function by genetic ablation. Surprisingly, inactivation of MarvelD3 in mice did not alter development and differentiation of the pancreatic tissue. Moreover, tight junction formation and organization, cell polarization, and activity of the JNK-pathway were not impacted by the deletion of MarvelD3.

Glucose Metabolism After Pancreatectomy: Opposite Extremes Between Pancreaticoduodenectomy and Distal Pancreatectomy

CONTEXT

The rate of glucose metabolism changes drastically after partial pancreatectomy.

OBJECTIVE

This work aims to analyze changes in patients' glucose metabolism and endocrine and exocrine function before and after partial pancreatectomy relative to different resection types (Kindai Prospective Study on Metabolism and Endocrinology after Pancreatectomy: KIP-MEP study).

METHODS

A series of 278 consecutive patients with scheduled pancreatectomy were enrolled into our prospective study. Of them, 109 individuals without diabetes, who underwent partial pancreatectomy, were investigated. Data were compared between patients with pancreaticoduodenectomy (PD, n = 73) and those with distal pancreatectomy (DP, n = 36).

RESULTS

Blood glucose levels during the 75-g oral glucose tolerance test (75gOGTT) significantly decreased after pancreatectomy in the PD group (area under the curve [AUC] -9.3%, P < .01), and significantly increased in the DP population (AUC + 16.8%, P < .01). Insulin secretion rate during the 75gOGTT and glucagon stimulation test significantly decreased after pancreatectomy both in the PD and DP groups (P < .001). Both groups showed similar homeostasis model assessment of insulin resistance (HOMA-IR) values after pancreatectomy. Decrease in exocrine function quality after pancreatectomy was more marked in association with PD than DP (P < .01). Multiple regression analysis indicated that resection type and preoperative HOMA-IR independently influenced glucose tolerance-related postoperative outcomes.

CONCLUSIONS

Blood glucose levels after the OGTT differed markedly between PD and DP populations. The observed differences between PD and DP suggest the importance of individualization in the management of metabolism and nutrition after partial pancreatectomy.

Ultrafiltration and Injection of Islet Regenerative Stimuli Secreted by Pancreatic Mesenchymal Stromal Cells

The secretome of mesenchymal stromal cells (MSCs) is enriched for biotherapeutic effectors contained within and independent of extracellular vesicles (EVs) that may support tissue regeneration as an injectable agent. We have demonstrated that the intrapancreatic injection of concentrated conditioned media (CM) produced by bone marrow MSC supports islet regeneration and restored glycemic control in hyperglycemic mice, ultimately providing a platform to elucidate components of the MSC secretome. Herein, we extend these findings using human pancreas-derived MSC (Panc-MSC) as "biofactories" to enrich for tissue regenerative stimuli housed within distinct compartments of the secretome. Specifically, we utilized 100 kDa ultrafiltration as a simple method to debulk protein mass and to enrich for EVs while concentrating the MSC secretome into an injectable volume for preclinical assessments in murine models of blood vessel and islet regeneration. EV enrichment (EV+) was validated using nanoscale flow cytometry and atomic force microscopy, in addition to the detection of classical EV markers CD9, CD81, and CD63 using label-free mass spectrometry. EV+ CM was predominately enriched with mediators of wound healing and epithelial-to-mesenchymal transition that supported functional regeneration in mesenchymal and nonmesenchymal tissues. For example, EV+ CM supported human microvascular endothelial cell tubule formation in vitro and enhanced the recovery of blood perfusion following intramuscular injection in nonobese diabetic/severe combined immunodeficiency mice with unilateral hind limb ischemia. Furthermore, EV+ CM increased islet number and β cell mass, elevated circulating insulin, and improved glycemic control following intrapancreatic injection in streptozotocin-treated mice. Collectively, this study provides foundational evidence that Panc-MSC, readily propagated from the subculture of human islets, may be utilized for regenerative medicine applications.

Long-term live imaging and multiscale analysis identify heterogeneity and core principles of epithelial organoid morphogenesis

BACKGROUND

Organoids are morphologically heterogeneous three-dimensional cell culture systems and serve as an ideal model for understanding the principles of collective cell behaviour in mammalian organs during development, homeostasis, regeneration, and pathogenesis. To investigate the underlying cell organisation principles of organoids, we imaged hundreds of pancreas and cholangiocarcinoma organoids in parallel using light sheet and bright-field microscopy for up to 7 days.

RESULTS

We quantified organoid behaviour at single-cell (microscale), individual-organoid (mesoscale), and entire-culture (macroscale) levels. At single-cell resolution, we monitored formation, monolayer polarisation, and degeneration and identified diverse behaviours, including lumen expansion and decline (size oscillation), migration, rotation, and multi-organoid fusion. Detailed individual organoid quantifications lead to a mechanical 3D agent-based model. A derived scaling law and simulations support the hypotheses that size oscillations depend on organoid properties and cell division dynamics, which is confirmed by bright-field microscopy analysis of entire cultures.

CONCLUSION

Our multiscale analysis provides a systematic picture of the diversity of cell organisation in organoids by identifying and quantifying the core regulatory principles of organoid morphogenesis.

Decreased blood vessel density and endothelial cell subset dynamics during ageing of the endocrine system

Age-associated alterations of the hormone-secreting endocrine system cause organ dysfunction and disease states. However, the cell biology of endocrine tissue ageing remains poorly understood. Here, we perform comparative 3D imaging to understand age-related perturbations of the endothelial cell (EC) compartment in endocrine glands. Datasets of a wide range of markers highlight a decline in capillary and artery numbers, but not of perivascular cells in pancreas, testis and thyroid gland, with age in mice and humans. Further, angiogenesis and β-cell expansion in the pancreas are coupled by a distinct age-dependent subset of ECs. While this EC subpopulation supports pancreatic β cells, it declines during ageing concomitant with increased expression of the gap junction protein Gja1. EC-specific ablation of Gja1 restores β-cell expansion in the aged pancreas. These results provide a proof of concept for understanding age-related vascular changes and imply that therapeutic targeting of blood vessels may restore aged endocrine tissue function. This comprehensive data atlas offers over > 1,000 multicolour volumes for exploration and research in endocrinology, ageing, matrix and vascular biology.

Debates in Pancreatic Beta Cell Biology: Proliferation Versus Progenitor Differentiation and Transdifferentiation in Restoring β Cell Mass

In all forms of diabetes, β cell mass or function is reduced and therefore the capacity of the pancreatic cells for regeneration or replenishment is a critical need. Diverse lines of research have shown the capacity of endocrine as well as acinar, ductal and centroacinar cells to generate new β cells. Several experimental approaches using injury models, pharmacological or genetic interventions, isolation and in vitro expansion of putative progenitors followed by transplantations or a combination thereof have suggested several pathways for β cell neogenesis or regeneration. The experimental results have also generated controversy related to the limitations and interpretation of the experimental approaches and ultimately their physiological relevance, particularly when considering differences between mouse, the primary animal model, and human. As a result, consensus is lacking regarding the relative importance of islet cell proliferation or progenitor differentiation and transdifferentiation of other pancreatic cell types in generating new β cells. In this review we summarize and evaluate recent experimental approaches and findings related to islet regeneration and address their relevance and potential clinical application in the fight against diabetes.

The Eye as a Transplantation Site to Monitor Pancreatic Islet Cell Plasticity

The endocrine cells confined in the islets of Langerhans are responsible for the maintenance of blood glucose homeostasis. In particular, beta cells produce and secrete insulin, an essential hormone regulating glucose uptake and metabolism. An insufficient amount of beta cells or defects in the molecular mechanisms leading to glucose-induced insulin secretion trigger the development of diabetes, a severe disease with epidemic spreading throughout the world. A comprehensive appreciation of the diverse adaptive procedures regulating beta cell mass and function is thus of paramount importance for the understanding of diabetes pathogenesis and for the development of effective therapeutic strategies. While significant findings were obtained by the use of islets isolated from the pancreas, in vitro studies are inherently limited since they lack the many factors influencing pancreatic islet cell function in vivo and do not allow for longitudinal monitoring of islet cell plasticity in the living organism. In this respect a number of imaging methodologies have been developed over the years for the study of islets in situ in the pancreas, a challenging task due to the relatively small size of the islets and their location, scattered throughout the organ. To increase imaging resolution and allow for longitudinal studies in individual islets, another strategy is based on the transplantation of islets into other sites that are more accessible for imaging. In this review we present the anterior chamber of the eye as a transplantation and imaging site for the study of pancreatic islet cell plasticity, and summarize the major research outcomes facilitated by this technological platform.

One hundred years ago: the dawning of the insulin era

The dawn of the insulin era can be placed in 1921, when Banting and Best started their experiments which led, a year later, to the successful treatment of diabetes. They were preceded by the discoveries of the pancreatic cause of diabetes by Minkowski and von Mering in 1889 and of the islets by Paul Langerhans in 1869. The achievement of the first targeted treatment in medical history was a landmark of medical progress. However, it was accompanied by a mixture of human greatness and misery. Genius and recklessness, ambition and deception, camaraderie and rivalry, selflessness and pursuit of glory went along with superficial search of the existing literature, poor planning, faulty interpretation of results, failure to reproduce them, and misquoting of reports from other laboratories. Then as now, such faults surface whenever human nature aims to push forward the boundaries of knowledge and pose a real challenge in today's world, as the scientific method strives to keep healthy in the face of growing anti-scientific feelings.

Development platform for artificial pancreas algorithms

BACKGROUND AND AIMS

Assessing algorithms of artificial pancreas systems is critical in developing automated and fault-tolerant solutions that work outside clinical settings. The development and evaluation of algorithms can be facilitated with a platform that conducts virtual clinical trials. We present in this paper a clinically validated cloud-based distributed platform that supports the development and comprehensive testing of single and dual-hormone algorithms for type 1 diabetes mellitus (T1DM).

METHODS

The platform is built on principles of object-oriented design and runs user algorithms in real-time virtual clinical trials utilizing a multi-threaded environment enabled by concurrent execution over a cloud infrastructure. The platform architecture isolates user algorithms located on personal machines from proprietary patient data running on the cloud. Users import a plugin into their algorithms (Matlab, Python, or Java) to connect to the platform. Once connected, users interact with a graphical interface to design experimental protocols for their trials. Protocols include trial duration in days, mealtimes and amounts, variability in mealtimes and amounts, carbohydrate counting errors, snacks, and onboard insulin levels.

RESULTS

The platform facilitates development by solving the ODE model in the cloud on large CPU-optimized machines, providing a 62% improvement in memory, speed and CPU utilization. Users can easily debug & modify code, test multiple strategies, and generate detailed clinical performance reports. We validated and integrated into the platform a glucoregulatory system of ordinary differential equations (ODEs) parameterized with clinical data to mimic the inter and intra-day variability of glucose responses of 15 T1DM patients.

CONCLUSION

The platform utilizes the validated patient model to conduct virtual clinical trials for the rapid development and testing of closed-loop algorithms for T1DM.

The core clock transcription factor BMAL1 drives circadian β-cell proliferation during compensatory regeneration of the endocrine pancreas

Circadian clocks in pancreatic islets participate in the regulation of glucose homeostasis. Here we examined the role of these timekeepers in β-cell regeneration after the massive ablation of β cells by doxycycline-induced expression of diphtheria toxin A (DTA) in Insulin-rtTA/TET-DTA mice. Since we crossed reporter genes expressing α- and β-cell-specific fluorescent proteins into these mice, we could follow the fate of α- and β cells separately. As expected, DTA induction resulted in an acute hyperglycemia, which was accompanied by dramatic changes in gene expression in residual β cells. In contrast, only temporal alterations of gene expression were observed in α cells. Interestingly, β cells entered S phase preferentially during the nocturnal activity phase, indicating that the diurnal rhythm also plays a role in the orchestration of β-cell regeneration. Indeed, in arrhythmic Bmal1-deficient mice, which lack circadian clocks, no compensatory β-cell proliferation was observed, and the β-cell ablation led to aggravated hyperglycemia, hyperglucagonemia, and fatal diabetes.

Human enteroviral infection impairs autophagy in clonal INS(832/13) cells and human pancreatic islet cells

AIM/HYPOTHESIS

Human enteroviral infections are suggested to be associated with type 1 diabetes. However, the mechanism by which enteroviruses can trigger disease remains unknown. The present study aims to investigate the impact of enterovirus on autophagy, a cellular process that regulates beta cell homeostasis, using the clonal beta cell line INS(832/13) and human islet cells as in vitro models.

METHODS

INS(832/13) cells and human islet cells were infected with a strain of echovirus 16 (E16), originally isolated from the stool of a child who developed type 1 diabetes-associated autoantibodies. Virus production and release was determined by 50% cell culture infectious dose (CCID₅₀) assay and FACS analysis. The occurrence of autophagy, autophagosomes, lysosomes and autolysosomes was detected by western blot, baculoviral-mediated expression of microtubule-associated protein light chain 3 (LC3)II-GFP and LysoTracker Red, and quantified by Cellomics ArrayScan. Autophagy was also monitored with a Cyto-ID detection kit. Nutrient deprivation (low glucose [2.8 mmol/l]), amino acid starvation (Earle's Balanced Salt Solution [EBSS]) and autophagy-modifying agents (rapamycin and chloroquine) were used in control experiments. Insulin secretion and the expression of autophagy-related (Atg) genes and genes involved in autophagosome-lysosome fusion were determined.

RESULTS

E16-infected INS(832/13) cells displayed an accumulation of autophagosomes, compared with non-treated (NT) cells (grown in complete RPMI1640 containing 11.1 mmol/l glucose) (32.1 ± 1.7 vs 21.0 ± 1.2 μm²/cell; p = 0.05). This was accompanied by increased LC3II ratio both in E16-infected cells grown in low glucose (LG) (2.8 mmol/l) (0.42 ± 0.03 vs 0.11 ± 0.04 (arbitrary units [a.u.]); p < 0.0001) and grown in media containing 11.1 mmol/l glucose (0.37 ± 0.016 vs 0.05 ± 0.02 (a.u.); p < 0.0001). Additionally, p62 accumulated in cells after E16 infection when grown in LG (1.23 ± 0.31 vs 0.36 ± 0.12 (a.u.); p = 0.012) and grown in media containing 11.1 mmol/l glucose (1.79 ± 0.39 vs 0.66 ± 0.15 (a.u.); p = 0.0078). mRNA levels of genes involved in autophagosome formation and autophagosome-lysosome fusion remained unchanged in E16-infected cells, except Atg7, which was significantly increased when autophagy was induced by E16 infection, in combination with LG (1.48 ± 0.08-fold; p = 0.02) and at 11.1 mmol/l glucose (1.26 ± 0.2-fold; p = 0.001), compared with NT controls. Moreover, autophagosomes accumulated in E16-infected cells to the same extent as when cells were treated with the lysosomal inhibitor, chloroquine, clearly indicating that autophagosome turnover was blocked. Upon infection, there was an increased viral titre in the cell culture supernatant and a marked reduction in glucose-stimulated insulin secretion (112.9 ± 24.4 vs 209.8 ± 24.4 ng [mg protein]^-1 h^-1; p = 0.006), compared with uninfected controls, but cellular viability remained unaffected. Importantly, and in agreement with the observations for INS(832/13) cells, E16 infection impaired autophagic flux in primary human islet cells (46.5 ± 1.6 vs 34.4 ± 2.1 μm²/cell; p = 0.01).

CONCLUSIONS/INTERPRETATION

Enteroviruses disrupt beta cell autophagy by impairing the later stages of the autophagic pathway, without influencing expression of key genes involved in core autophagy machinery. This results in increased viral replication, non-lytic viral spread and accumulation of autophagic structures, all of which may contribute to beta cell demise and type 1 diabetes. Graphical abstract.

Zinc: Roles in pancreatic physiology and disease

Zinc is an essential trace element. Deficiencies are frequently seen with gastrointestinal diseases, including chronic pancreatitis, nutritional deficiency, and reduced intestinal absorption. Additionally, reduced zinc levels have been linked to cellular changes associated with acute pancreatitis such as enhanced inflammation with increased macrophage activation and production of inflammatory cytokines such as IL-1β, impaired autophagy, and modulation of calcium homeostasis. Preliminary data suggest that zinc deficiency may lead to pancreatic injury in animal models. The purpose of this review is to explore the biologic effects of zinc deficiency that could impact pancreatic disease. MESH KEYWORDS: Malnutrition, inflammation, trace element.

Evidence of Tissue Repair in Human Donor Pancreas After Prolonged Duration of Stay in Intensive Care

M2 macrophages play an important role in tissue repair and regeneration. They have also been found to modulate β-cell replication in mouse models of pancreatic injury and disease. We previously reported that β-cell replication is strongly increased in a subgroup of human organ donors characterized by prolonged duration of stay in an intensive care unit (ICU) and increased number of leukocytes in the pancreatic tissue. In the present study we investigated the relationship between duration of stay in the ICU, M2 macrophages, vascularization, and pancreatic cell replication. Pancreatic organs from 50 donors without diabetes with different durations of stay in the ICU were analyzed by immunostaining and digital image analysis. The number of CD68⁺CD206⁺ M2 macrophages increased three- to sixfold from ≥6 days' duration of stay in the ICU onwards. This was accompanied by a threefold increased vascular density and a four- to ninefold increase in pancreatic cells positive for the replication marker Ki67. A strong correlation was observed between the number of M2 macrophages and β-cell replication. These results show that a prolonged duration of stay in the ICU is associated with an increased M2 macrophage number, increased vascular density, and an overall increase in replication of all pancreatic cell types. Our data show evidence of marked levels of tissue repair in the human donor pancreas.

Life with the pancreas: A personal experience

This review article has primary objective to summarize pancreatic research which has been done in our laboratory since 1965, the first year of the author's registration in the Ph.D. program at the University of Sherbrooke (Canada). It covers the following major topics of pancreatic physiology: controls of pancreatic adaptation to diet, control of pancreatic enzyme secretion, control of pancreatic enzyme synthesis, control of pancreatic growth, intracellular events stimulated during pancreatic growth, pancreas regeneration after pancreatitis and pancreatectomy, the pancreatic cholecystokinin receptor types 1 and 2, growth control and cell signaling in pancreatic cancer cells and finally, cystic fibrosis.

The functioning side of the pancreas: a review on insulinomas

PURPOSE

Insulinomas are a rare type of neuroendocrine tumors, originating in the pancreas, difficult to diagnose and to treat. Due to its rarity, insulinomas are a not well-known pathological entity; thus, the diagnostic process is frequently a medical challenge with many possible differential diagnoses. The diagnostic process varies between non-invasive procedures, such as the fasting test or imaging techniques, and invasive ones. Insulinomas are rarely malignant, but the glycemic imbalance correlated with this tumor can frequently alter the quality of life of the patients and the consequent hypoglycemia can be extremely dangerous. Moreover, insulinomas can be associated with different genetic syndromes, such as Multiple Endocrine Neoplasia 1, accompanied by other specific symptoms. There are many different treatment strategies, depending on the need to control symptoms or control diseases progression, the only curative one being surgery.

METHODS AND RESULTS

We reviewed the evidences present in the literature on insulinomas and reported its main clinical characteristics and management strategies.

CONCLUSION

The aim of this review of the literature is to present the current knowledge on insulinomas, exploring the main clinical characteristics, the diagnostic tools, and the therapeutic strategies.

Gastrin, Cholecystokinin, Signaling, and Biological Activities in Cellular Processes

The structurally-related peptides, gastrin and cholecystokinin (CCK), were originally discovered as humoral stimulants of gastric acid secretion and pancreatic enzyme release, respectively. With the aid of methodological advances in biochemistry, immunochemistry, and molecular biology in the past several decades, our concept of gastrin and CCK as simple gastrointestinal hormones has changed considerably. Extensive in vitro and in vivo studies have shown that gastrin and CCK play important roles in several cellular processes including maintenance of gastric mucosa and pancreatic islet integrity, neurogenesis, and neoplastic transformation. Indeed, gastrin and CCK, as well as their receptors, are expressed in a variety of tumor cell lines, animal models, and human samples, and might contribute to certain carcinogenesis. In this review, we will briefly introduce the gastrin and CCK system and highlight the effects of gastrin and CCK in the regulation of cell proliferation and apoptosis in both normal and abnormal conditions. The potential imaging and therapeutic use of these peptides and their derivatives are also summarized.

Organoids from the Human Fetal and Adult Pancreas

PURPOSE OF REVIEW

Novel 3D organoid culture techniques have enabled long-term expansion of pancreatic tissue. This review comprehensively summarizes and evaluates the applications of primary tissue-derived pancreatic organoids in regenerative studies, disease modelling, and personalized medicine.

RECENT FINDINGS

Organoids derived from human fetal and adult pancreatic tissue have been used to study pancreas development and repair. Generated adult human pancreatic organoids harbor the capacity for clonal expansion and endocrine cell formation. In addition, organoids have been generated from human pancreatic ductal adenocarcinoma in order to study tumor behavior and assess drug responses. Pancreatic organoids constitute an important translational bridge between in vitro and in vivo models, enhancing our understanding of pancreatic cell biology. Current applications for pancreatic organoid technology include studies on tissue regeneration, disease modelling, and drug screening.

Assessment of abdominal organ motion using cine magnetic resonance imaging in different gastric motilities: a comparison between fasting and postprandial states

This study assessed abdominal organ motion induced by gastroduodenal motilities in volunteers during fasting and postprandial states, using cine magnetic resonance imaging (cine-MRI). Thirty-five volunteers underwent cine-MRI while holding their breath in the fasting and postprandial states. Gastric motility was quantified by the amplitude and velocity of antral peristaltic waves. Duodenal motility was evaluated as the change of duodenal diameter. Abdominal organ motion was measured in the liver, pancreas and kidneys. Motion was quantified by calculating maximal organ displacement in the left-right, antero-posterior and caudal-cranial directions. Median antral amplitude and velocity in the fasting and postprandial states were 7.7 and 15.1 mm (P < 0.01), and 1.3 and 2.5 mm/s (P < 0.01), respectively. Duodenal motility did not change. Median displacement for all organs ranged from 0.9 to 2.9 mm in the fasting state and from 1.0 to 2.9 mm in the postprandial state. Significant increases in abdominal organ displacement in the postprandial state were observed in the right lobe of the liver, pancreatic head and both kidneys. Differences in the median displacement of these organs between the two states were all <1 mm. Although the motion of several abdominal organs increased in the postprandial state, the difference between the two states was quite small. Thus, our study suggests that treatment planning and irradiation need not include strict management of gastric conditions, nor the addition of excess margins to compensate for differences in the intra-fractional abdominal organ motion under different gastric motilities in the fasting and postprandial states.

Pancreatic Malnutrition in Children

Exocrine pancreatic insufficiency in children can lead to lifelong complications related to malnutrition and poor growth. The clinical presentation can be subtle in the early stages of insufficiency as the large functional capacity of the pancreas is gradually lost. The pediatrician plays a crucial role in the early identification of these children to ensure a timely referral so that a diagnosis can be made and therapy initiated. Early nutritional therapy allows for prevention and correction of deficiencies, which leads to improved outcomes and survival. When insufficiency is suspected, the workup should start with an indirect test of exocrine pancreatic function, such as fecal elastase, to establish the diagnosis. Once a diagnosis is established, further testing to delineate the etiology should be pursued, with cystic fibrosis being high on the differential list and assessed for with a sweat test. Assessment of anthropometry at every visit is key, as is monitoring of laboratory parameters and physical examination findings that are suggestive of malabsorption and malnutrition. The mainstay of management is administration of exogenous pancreatic enzymes to facilitate digestion and absorption. [Pediatr Ann. 2019;48(11):e441-e447.].

Understanding the mechanisms of reversal of type 2 diabetes

Clinical and pathophysiological studies have shown type 2 diabetes to be a condition mainly caused by excess, yet reversible, fat accumulation in the liver and pancreas. Within the liver, excess fat worsens hepatic responsiveness to insulin, leading to increased glucose production. Within the pancreas, the β cell seems to enter a survival mode and fails to function because of the fat-induced metabolic stress. Removal of excess fat from these organs via substantial weight loss can normalise hepatic insulin responsiveness and, in the early years post-diagnosis, is associated with β-cell recovery of acute insulin secretion in many individuals, possibly by redifferentiation. Collectively, these changes can normalise blood glucose levels. Importantly, the primary care-based Diabetes Remission Clinical Trial (DiRECT) showed that 46% of people with type 2 diabetes could achieve remission at 12 months, and 36% at 24 months, mediated by weight loss. This major change in our understanding of the underlying mechanisms of disease permits a reassessment of advice for people with type 2 diabetes.

Liver to Pancreas Transdifferentiation

PURPOSE OF THE REVIEW

Here, we review recent findings in the field of generating insulin-producing cells by pancreatic transcription factor (pTF)-induced liver transdifferentiation (TD). TD is the direct conversion of functional cell types from one lineage to another without passing through an intermediate stage of pluripotency. We address potential reasons for the restricted efficiency of TD and suggest modalities to overcome these challenges, to bring TD closer to its clinical implementation in autologous cell replacement therapy for insulin-dependent diabetes.

RECENT FINDINGS

Liver to pancreas TD is restricted to cells that are a priori predisposed to undergo the developmental process. In vivo, the predisposition of liver cells is affected by liver zonation and hepatic regeneration. The TD propensity of liver cells is related to permissive epigenome which could be extended to TD-resistant cells by specific soluble factors. An obligatory role for active Wnt signaling in continuously maintaining a "permissive" epigenome is suggested. Moreover, the restoration of the pancreatic niche and vasculature promotes the maturation of TD cells along the β cell function. Future studies on liver to pancreas TD should include the maturation of TD cells by 3D culture, the restoration of vasculature and the pancreatic niche, and the extension of TD propensity to TD-resistant cells by epigenetic modifications. Liver to pancreas TD is expected to result in the generation of custom-made "self" surrogate β cells for curing diabetes.

Pleiotropic roles of the insulin-like growth factor axis in type 1 diabetes

PURPOSE OF REVIEW

We review studies demonstrating lowered levels of insulin-like growth factors (IGFs) in patients with recent-onset type 1 diabetes (T1D) and discuss their potential roles in the disorder's pathogenesis.

RECENT FINDINGS

IGFs have long been recognized as a class of hormones that promote growth, development, and cellular metabolism throughout the human body. More recently, studies have noted an association between reduced pancreatic weight/volume and T1D. Thus, we believe it is important to understand pancreatic regulation of IGF expression and bioavailability, as well as the impact of IGFs on pancreatic growth and islet health. Additional studies of IGFs have been extended to their influence on the inflammatory/regulatory balance of monocytes, B cells, and T cells; features which have been previously established to show dysregulation in settings of T1D.

SUMMARY

These data suggest that IGFs may prevent known impairments in the pancreas and immune system in T1D and underscore the need to extend these studies, some of which were performed in health or other autoimmune diseases, toward T1D specifically. Collectively, the work emphasized here support the potential therapeutic use of IGFs in T1D prevention efforts as pancreatic growth factors and/or immunoregulatory agents.

Modeling Monogenic Diabetes using Human ESCs Reveals Developmental and Metabolic Deficiencies Caused by Mutations in HNF1A

Human monogenic diabetes, caused by mutations in genes involved in beta cell development and function, has been a challenge to study because multiple mouse models have not fully recapitulated the human disease. Here, we use genome edited human embryonic stem cells to understand the most common form of monogenic diabetes, MODY3, caused by mutations in the transcription factor HNF1A. We found that HNF1A is necessary to repress an alpha cell gene expression signature, maintain endocrine cell function, and regulate cellular metabolism. In addition, we identified the human-specific long non-coding RNA, LINKA, as an HNF1A target necessary for normal mitochondrial respiration. These findings provide a possible explanation for the species difference in disease phenotypes observed with HNF1A mutations and offer mechanistic insights into how the HNF1A gene may also influence type 2 diabetes.

The Propagation Display Method Improves the Reproducibility of Pancreatic Shear Wave Elastography

Evaluation of the pancreatic elastic modulus (PEM) using shear wave elastography (SWE) requires at least 5 measurements to ensure reproducibility. The aim of this study was to evaluate improvement in reproducibility of SWE, using the propagation display method in normal pancreas ([NP] phase 1) and to examine the differences in PEM between NP and chronic pancreatitis (CP), intraductal papillary mucinous neoplasm (IPMN) and autoimmune pancreatitis ([AIP] phase 2). In phase 1, the measurement success rate, median PEM in repeated measurements and appropriate number of SWE measurements were determined in 109 cases with NP. In phase 2, PEM was measured in CP (n = 10), IPMN (n = 31) and AIP (n = 5), using the required number of SWE measurements determined in phase 1. In phase 1, the measurement success rate was 93.9% (92/109 cases). The median PEM for NP was 14.6 kPa and the appropriate number of SWE measurements was at least 3. In phase 2, the median PEMs in CP, IPMN and AIP were 19.6, 18.1 and 17.2 kPa, respectively, with significant differences between NP and CP (p = 0.0133) and between NP and IPMN (p = 0.0436). Use of the propagation display method in SWE improves the reproducibility of measurement of PEM.

Reseeding endothelial cells with fibroblasts to improve the re-endothelialization of pancreatic acellular scaffolds

Pancreatic transplantation remains the only cure for diabetes, but the shortage of donors limits its clinical application. Whole organ decellularized scaffolds offer a new opportunity for pancreatic organ regeneration; however inadequate endothelialization and vascularization can prevent sufficient transport of oxygen and nutrient supplies to the transplanted organ, as well as leading unwanted thrombotic events. In the present study, we explored the re-endothelialization of rat pancreatic acellular scaffolds via circulation perfusion using human skin fibroblasts (FBs) and human umbilical vein endothelial cells (HUVECs). Our results revealed that the cell adhesion rate when these cells were co-cultured was higher than under control conditions, and this increase was associated with increased release of growth factors including VEGF, FGFb, EGF, and IGF-1 as measured by ELISA. When these recellularized organs were implanted in vivo for 28 days in rat dorsal subcutaneous pockets, we found that de novo vasculature formation in the co-culture samples was superior to the control samples. Together these results suggest that endothelial cell and FB co-culture enhances the re-endothelialization and vascularization of pancreatic acellular scaffolds.

The Wilms' tumor suppressor gene regulates pancreas homeostasis and repair

The Wilms’ tumor suppressor gene (Wt1) encodes a zinc finger transcription factor that plays an essential role in the development of kidneys, gonads, spleen, adrenals and heart. Recent findings suggest that WT1 could also be playing physiological roles in adults. Systemic deletion of WT1 in mice provokes a severe deterioration of the exocrine pancreas, with mesothelial disruption, E-cadherin downregulation, disorganization of acinar architecture and accumulation of ascitic transudate. Despite this extensive damage, pancreatic stellate cells do not become activated and lose their canonical markers. We observed that pharmacological induction of pancreatitis in normal mice provokes de novo expression of WT1 in pancreatic stellate cells, concomitant with their activation. When pancreatitis was induced in mice after WT1 ablation, pancreatic stellate cells expressed WT1 and became activated, leading to a partial rescue of the acinar structure and the quiescent pancreatic stellate cell population after recovery from pancreatitis. We propose that WT1 modulates through the RALDH2/retinoic acid axis the restabilization of a part of the pancreatic stellate cell population and, indirectly, the repair of the pancreatic architecture, since quiescent pancreatic stellate cells are required for pancreas stability and repair. Thus, we suggest that WT1 plays novel and essential roles for the homeostasis of the adult pancreas and, through its upregulation in pancreatic stellate cells after a damage, for pancreatic regeneration. Due to the growing importance of the pancreatic stellate cells in physiological and pathophysiological conditions, these novel roles can be of translational relevance.

The pancreas is largely composed by an exocrine tissue organized in acini, which secrete digestive enzymes. Pancreatic stellate cells (PSC) are arranged around the acini and they can become activated by a damage and contribute to pancreas repair. The pancreas is externally covered by a mesothelium characterized by the expression of the transcription factor WT1. Loss of WT1 function in adult mice provokes a rapid and severe deterioration of the pancreas, with disorganization of the acinar tissue. Despite the extensive damage, PSC do not become activated. We first showed that a pharmacologically induced acute pancreatitis led to expression of WT1 in PSC concomitant to their activation. Then, we induced pancreatitis in mice where WT1 had been previously deleted, and the upregulation of WT1 in PSC partially rescued the repairing phenotype of the PSC and reduced the disorganization of the acinar tissue. Thus, we suggest that WT1 function is necessary to maintain the integrity of the pancreatic mesothelium and, at the same time, it is required for activation of the repairing phenotype in PSC.

Pancreatic Progenitors: There and Back Again

Adult pancreatic regeneration is one of the most contentious topics in modern biology. The long-held view that the islets of Langerhans can be replenished throughout adult life through the reactivation of ductal progenitor cells has been replaced over the past decade by the now prevailing notion that regeneration does not involve progenitors and occurs only through the duplication of pre-existing mature cells. Here we dissect the limitations of lineage tracing (LT) to draw categorical conclusions about pancreatic regeneration, especially in view of emerging evidence that traditional lineages are less homogeneous and cell fates more dynamic than previously thought. This new evidence further suggests that the two competing hypotheses about regeneration are not mutually exclusive.

Association between Pancreatic Atrophy and Loss of Insulin Secretory Capacity in Patients with Type 2 Diabetes Mellitus

AIMS

To examine pancreatic volume (PV) changes among patients with different duration of type 2 diabetes and whether pancreatic atrophy was associated with loss of insulin secretory capacity.

METHODS

This cross-sectional study (203 patients with type 2 diabetes, 93 controls without diabetes) was conducted from January 2016 to December 2017. Patients with type 2 diabetes were divided into 3 groups: recently diagnosed (duration ≤ 2 years), midterm (duration 3-9 years), and long term (duration ≥ 10 years). All the patients were scanned with upper abdominal computerized tomography; PV was then calculated by an experienced technician. Absolute insulin deficiency was defined as fasting C - peptide < 0.9 ng/mL.

RESULTS

Compared with PV (cm³) in the controls, the mean PV was similar in patients with recently diagnosed type 2 diabetes (68.8 versus 71.0, P = 0.56) but significantly reduced in patients with midterm (68.8 versus 60.8, P < 0.05) and long-term (68.8 versus 53.1, P < 0.001) type 2 diabetes. A similar trend was observed for the PV index (PV adjusted for body surface area and body mass index). Furthermore, rates of pancreatic atrophy and absolute insulin deficiency increased with duration of diabetes. Multiple logistic regression analysis indicated that pancreatic atrophy was associated with higher likelihood of absolute insulin deficiency (odds ratio = 4.47, 95%confidence interval = 1.45-13.8).

CONCLUSIONS

PV was reduced in those with midterm and long-term type 2 diabetes compared to individuals without type 2 diabetes. Overall, pancreatic atrophy was associated with the loss of insulin secretory capacity in patients with type 2 diabetes.

[Features of endocrine function of the pancreas with aging in nonhuman primates with various types of adaptive behavior.]

An increasing number of studies are devoted to the study of the relationship of mental disorders, such as depression and anxiety, with the risk of developing type 2 diabetes mellitus. However, in the literature there are practically no publications on the study of the relationship of the features of higher nervous activity, in particular, adaptive behavior, in healthy individuals with the risk of developing age-related dysfunction of the pancreatic islet apparatus (PIA). The purpose of this study was to investigate features of the functioning of the PIA during aging in individuals with normal standard behavior (SB), as well as anxiety- and depressive-like behavior (DAB) in experiments on nonhuman primates. 76 physically healthy young mature and old female rhesus monkeys with SB and DAB were used in the experiments. Old animals were divided into subgroups with normal (NW) and excess (EW) body weight. All young animals were characterized by NW. The function of PIA was assessed using a glucose tolerance test. Intergroup differences in the functioning of the PIA in young animals were revealed, which were characterized by signs of impaired early insulin response, apparently due to a decrease in the sensitivity of β-cells of the pancreas to glucose. With aging, the function of the PIA was damaged in all animals, but the features of its changes depended on both the affiliation to a particular behavioral group and the animal's body weight. During aging in animals with SB, the development of relative insulin resistance of peripheral tissues was observed, accompanied by impaired glucose tolerance and a compensatory increase in the secretory activity of the PIA, which were more pronounced in animals with EW. Age-related dysfunction of the PIA in animals with DAB and NW was similar with age-related changes in the PIA function in animals with SB and NW. At the same time, with aging, animals with DAB and EW showed a more significant peak concentration of glucose than that of old animals with SB and EW, accompanied by a minimum «disappearance» rate of glucose from the circulation and significantly lower insulin secretion than this in animals with SB and EW. Thus, age-related dysfunctions of the PIA in primates with SB and DAB are unidirectional with the development of insulin resistance, impaired glucose tolerance and a compensatory increase in insulin secretion, which, however, in old animals with DAB and EW are accompanied by exhaustion of the PIA function, increasing the risk of developing type 2 diabetes mellitus.

Systematic review of the mesopancreas: concept and clinical implications

BACKGROUND

In 2007, Gockel et al. coined the term mesopancreas (MP). In the next 10 years, a limited number of publications about MP have been published, but little is known about the oncological benefit of MP resection. We performed a systematic review of the literature on MP.

METHODS

An electronic search was performed in PubMed, EMBASE, Cochrane, Latindex, Scielo, and Koreamed databases until 15 June 2017 to identify all published articles dealing with the subject of MP. Some language restriction was done (Chinese and Rumanian).

RESULTS

The search yielded 51 articles; 28 articles were selected as relevant. All were retrospective studies focused more on describing technical variants, feasibility and safety than on the cancer results. The R0 rate in patients with MP resection ranged between 57 and 96.7%. In all the articles with a control group, the R0 rate was higher in the MP excision group. Survival data were explicitly stated only in five series.

CONCLUSION

MP is a difficult-to-excise retropancreatic area. In theory, it is agreed that MP excision raises the rate of R0 resections, which in turn reflected in an improvement in the oncological results; however, at present there are no randomized studies to prove this. Achieving a worldwide consensus on its concept, landmarks, excision technique and oncological results is essential.

Adaptive changes in pancreas post Roux-en-Y gastric bypass induced weight loss

BACKGROUND

Obesity has been shown to trigger adaptive increases in pancreas parenchymal and fat volume. Consecutively, pancreatic steatosis may lead to beta-cell dysfunction. However, it is not known whether the pancreatic tissue components decrease with weight loss and pancreatic steatosis is reversible following Roux-en-Y gastric bypass (RYGB). Therefore, the objective of the study was to investigate the effects of RYGB-induced weight loss on pancreatic volume and glucose homeostasis.

METHODS

Eleven patients were recruited in the Obesity Centre of the University Medical Centre Hamburg-Eppendorf. Before and 6 months after RYGB, total GLP-1 levels were measured during oral glucose tolerance test. To assess changes in visceral adipose tissue and pancreatic volume, MRI was performed. Measures of glucose homeostasis and insulin indices were assessed. Fractional beta-cell area was estimated by correlation with the C-peptide-to-glucose ratio; beta-cell mass was calculated by the product of beta-cell area and pancreas parenchymal weight.

RESULTS

Pancreas volume decreased from 83.8 (75.7-92.0) to 70.5 (58.8-82.3) cm³ (mean [95% CI], P = .001). The decrease in total volume was associated with a significant decrease in fat volume. Fasting insulin and C-peptide were lower post RYGB. HOMA-IR levels decreased, whereas insulin sensitivity increased (P = .03). This was consistent with a reduction in the estimated beta-cell area and mass.

CONCLUSIONS

Following RYGB, pancreatic volume and steatosis adaptively decreased to "normal" levels with accompanying improvement in glucose homeostasis. Moreover, obesity-driven beta-cell expansion seems to be reversible; however, future studies must define a method to more accurately estimate functional beta-cell mass to increase our understanding of glucose homeostasis after RYGB.

Role of ghrelin in pancreatic development and function

Ghrelin is a gastric peptide with anabolic functions. It acutely stimulates growth hormone (GH) secretion from the anterior pituitary glands and modulates hypothalamic circuits that control food intake and energy expenditure. Besides its central activity, ghrelin is also involved in the regulation of pancreatic development and physiology. Particularly, several studies highlighted the ability of ghrelin to sustain β-cell viability and proliferation. Furthermore, ghrelin seems to exert inhibitory effects on pancreatic acinar and endocrine secretory functions. Due to its pleiotropic activity on energy metabolism, ghrelin has become a topic of great interest for experimental research focused on type II diabetes and obesity. The aim of this review is to illustrate the complex and not fully understood interplay between ghrelin, pancreas and glucose homeostasis.

Molecular characteristics of rhesus macaque interleukin-22: cloning, in vitro expression and biological activities

Interleukin-22 (IL-22) is a potential therapeutic agent for diseases driven by epithelial injury. To characterize the IL-22 expressed by rhesus macaques, animals that are irreplaceable for human disease research, rhesus macaque IL-22 (rhIL-22) was cloned and expressed, and its biological activity and in vivo distribution were examined. It was found that the rhIL-22 gene consists of five introns and six exons, including a short non-coding exon starting 22 bp downstream of a putative TATA box. The amino acid sequence of rhIL-22 showed 95·5% identity to that of humans, and it shared two conserved disulphide bonds, three N-glycosylation sites and all the critical residues for binding to IL-22R1. High levels of IL-22 mRNA were observed in the liver, pancreas, lymphoid tissues and especially in the outer-body barriers such as the intestinal tract of rhesus macaques. Functionally, purified rhIL-22 has a similar but a little earlier effect on signal transducer and activator of transcription 3 phosphorylation at Tyr705 compared with that of commercial human IL-22. The expression of the antibacterial proteins β-defensin-2, S100A8, S100A9, RegIIIα and Muc1 by HT-29 cells was largely upregulated after stimulation with rhIL-22. Recombinant rhIL-22 could also significantly promote the proliferation of human intestinal epithelial cells without affecting cell apoptosis. These data indicate that rhesus macaque IL-22 is highly similar to that of humans in both structure and function, and tests of therapeutic effects of human IL-22 on human diseases in rhesus macaques are warranted.

Regulation of compensatory β-cell proliferation by inter-organ networks from the liver to pancreatic β-cells

In insulin-resistant states such as obesity, pancreatic β-cells proliferate to prevent blood glucose elevations. However, the mechanism(s) by which obesity induces compensatory β-cell responses is not fully understood. Recently, several studies have shown that signals from the liver, such as neuronal signals or humoral factors, regulate β-cell proliferation during obesity development. We previously reported a liver-brain-pancreas neuronal relay, consisting of afferent splanchnic nerves, the central nervous system and efferent vagal nerves, to promote this compensatory β-cell proliferation. Furthermore, we recently clarified the molecular mechanisms by which efferent vagal signals induce β-cell proliferation in this inter-organ neuronal network system. Herein, these liver-β-cell inter-organ networks are reviewed, focusing mainly on the neuronal network. The significance of the neuronal network system in the maintenance of glucose homeostasis is also discussed with reference to the relevant literature.

Chronic AT1 blockade improves glucose homeostasis in obese OLETF rats

Obesity is associated with the inappropriate activation of the renin-angiotensin system (RAS), which increases arterial pressure, impairs insulin secretion and decreases peripheral tissue insulin sensitivity. RAS blockade reverses these detriments; however, it is not clear whether the disease state of the organism and treatment duration determine the beneficial effects of RAS inhibition on insulin secretion and insulin sensitivity. Therefore, the objective of this study was to compare the benefits of acute vs chronic angiotensin receptor type 1 (AT₁) blockade started after the onset of obesity, hyperglycemia and hypertension on pancreatic function and peripheral insulin resistance. We assessed adipocyte morphology, glucose intolerance, pancreatic redox balance and insulin secretion after 2 and 11 weeks of AT₁ blockade in the following groups of rats: (1) untreated Long-Evans Tokushima Otsuka (lean control; n = 10), (2) untreated Otsuka Long-Evans Tokushima Fatty (OLETF; n = 12) and (3) OLETF + ARB (ARB; 10 mg olmesartan/kg/day by oral gavage; n = 12). Regardless of treatment duration, AT₁ blockade decreased systolic blood pressure and fasting plasma triglycerides, whereas chronic AT₁ blockade decreased fasting plasma glucose, glucose intolerance and the relative abundance of large adipocytes by 22, 36 and 70%, respectively. AT₁ blockade, however, did not improve pancreatic oxidative stress or reverse impaired insulin secretion. Collectively, these data show that AT₁ blockade after the onset of obesity, hyperglycemia and hypertension improves peripheral tissue insulin sensitivity, but cannot completely reverse the metabolic derangement characterized by impaired insulin secretion once it has been compromised.

Earlier surgery improves outcomes from painful chronic pancreatitis

The timing of surgery for painful chronic pancreatitis (CP) may affect outcomes.Clinical course, Izbicki pain scores, and pancreatic function were retrospectively compared and analyzed between patients undergoing either early or late surgery (< 3 or ≥ 3 years from diagnosis) for painful CP in a single center from 2007 to 2012.The early surgery group (n = 98) more frequently than the late group (n = 199) had abdominal pain with jaundice (22.4% vs 9.5%, P = .002) and pancreatic mass +/- ductal dilatation (47% vs 27%, P < .001), but less frequently abdominal pain alone (73.5% vs 85.9%, P = .009), ductal dilatation alone (31% vs 71%, P < .001), parenchymal calcification (91.8% vs 100%, P < .001) or exocrine insufficiency (60% vs 72%, P = .034); there were no other significant differences. The early group had longer hospital stay (14.4 vs 12.2 days, P = .009), but no difference in complications. Significantly greater pain relief followed early surgery (complete 69% vs 47%, partial 22% vs 37%, none 8% vs 16%, P = .01) with lower rates of exocrine (60% vs 80%, P = .005) and endocrine insufficiency (36% vs 53%, P = .033).Our data indicate that early surgery results in higher rates of pain relief and pancreatic sufficiency than late surgery for chronic pancreatitis patients. Frey and Berne procedures showed better results than other surgical procedures.

SIRT6-mediated transcriptional suppression of Txnip is critical for pancreatic beta cell function and survival in mice

AIMS/HYPOTHESIS

Better understanding of how genetic and epigenetic components control beta cell differentiation and function is key to the discovery of novel therapeutic approaches to prevent beta cell dysfunction and failure in the progression of type 2 diabetes. Our goal was to elucidate the role of histone deacetylase sirtuin 6 (SIRT6) in beta cell development and homeostasis.

METHODS

Sirt6 endocrine progenitor cell conditional knockout and beta cell-specific knockout mice were generated using the Cre-loxP system. Mice were assayed for islet morphology, glucose tolerance, glucose-stimulated insulin secretion and susceptibility to streptozotocin. Transcriptional regulatory functions of SIRT6 in primary islets were evaluated by RNA-Seq analysis. Reverse transcription-quantitative (RT-q)PCR and immunoblot were used to verify and investigate the gene expression changes. Chromatin occupancies of SIRT6, H3K9Ac, H3K56Ac and active RNA polymerase II were evaluated by chromatin immunoprecipitation.

RESULTS

Deletion of Sirt6 in pancreatic endocrine progenitor cells did not affect endocrine morphology, beta cell mass or insulin production but did result in glucose intolerance and defective glucose-stimulated insulin secretion in mice. Conditional deletion of Sirt6 in adult beta cells reproduced the insulin secretion defect. Loss of Sirt6 resulted in aberrant upregulation of thioredoxin-interacting protein (TXNIP) in beta cells. SIRT6 deficiency led to increased acetylation of histone H3 lysine residue at 9 (H3K9Ac), acetylation of histone H3 lysine residue at 56 (H3K56Ac) and active RNA polymerase II at the promoter region of Txnip. SIRT6-deficient beta cells exhibited a time-dependent increase in H3K9Ac, H3K56Ac and TXNIP levels. Finally, beta cell-specific SIRT6-deficient mice showed increased sensitivity to streptozotocin.

CONCLUSIONS/INTERPRETATION

Our results reveal that SIRT6 suppresses Txnip expression in beta cells via deacetylation of histone H3 and plays a critical role in maintaining beta cell function and viability.

DATA AVAILABILITY

Sequence data have been deposited in the National Institutes of Health (NIH) Gene Expression Omnibus (GEO) with the accession code GSE104161.

GRP94 Is an Essential Regulator of Pancreatic β-Cell Development, Mass, and Function in Male Mice

Deficiencies in pancreatic β-cell mass contribute to both type 1 and type 2 diabetes. We investigated the role of the glucose-regulated protein (GRP) 94, an endoplasmic reticulum protein abundantly expressed in the pancreatic acini and islets, in β-cell development, survival, and function. We used a conditional knockout (KO) mouse in which the GRP94 gene, Hsp90b1, was specifically deleted in pancreatic and duodenal homeobox 1 (Pdx1)-expressing cells. These Hsp90b1 flox/flox;Pdx1Cre KO mice exhibited pancreatic hypoplasia at embryonic day (E) 16.5 to E18.5 and had significantly reduced β-cell mass at 4 weeks after birth. Further mechanistic studies showed that deletion of GRP94 reduced β-cell proliferation with increased cell apoptosis in both Pdx1+ endocrine progenitor cells and differentiated β cells. Although Hsp90b1 flox/flox;Pdx1Cre KO mice remained euglycemic at 8 weeks of age, they exhibited impaired glucose tolerance. In aggregate, these findings indicate that GRP94 is an essential regulator of pancreatic β-cell development, mass, and function.

Elevated HuR in Pancreas Promotes a Pancreatitis-Like Inflammatory Microenvironment That Facilitates Tumor Development

Human antigen R (ELAVL1; HuR) is perhaps the best-characterized RNA-binding protein. Through its overexpression in various tumor types, HuR promotes posttranscriptional regulation of target genes in multiple core signaling pathways associated with tumor progression. The role of HuR overexpression in pancreatic tumorigenesis is unknown and led us to explore the consequences of HuR overexpression using a novel transgenic mouse model that has a >2-fold elevation of pancreatic HuR expression. Histologically, HuR-overexpressing pancreas displays a fibroinflammatory response and other pathological features characteristic of chronic pancreatitis. This pathology is reflected in changes in the pancreatic gene expression profile due, in part, to genes whose expression changes as a consequence of direct binding of their respective mRNAs to HuR. Older mice develop pancreatic steatosis and severe glucose intolerance. Elevated HuR cooperated with mutant K-rasG12D to result in a 3.4-fold increase in pancreatic ductal adenocarcinoma (PDAC) incidence compared to PDAC presence in K-rasG12D alone. These findings implicate HuR as a facilitator of pancreatic tumorigenesis, especially in the setting of inflammation, and a novel therapeutic target for pancreatitis treatment.