The roles of calcium and ATP in the physiology and pathology of the exocrine pancreas.

This review deals with the roles of calcium ions and ATP in the control of the normal functions of the different cell types in the exocrine pancreas as well as the roles of these molecules in the pathophysiology of acute pancreatitis. Repetitive rises in the local cytosolic calcium ion concentration in the apical part of the acinar cells not only activate exocytosis but also, via an increase in the intramitochondrial calcium ion concentration, stimulate the ATP formation that is needed to fuel the energy-requiring secretion process. However, intracellular calcium overload, resulting in a global sustained elevation of the cytosolic calcium ion concentration, has the opposite effect of decreasing mitochondrial ATP production, and this initiates processes that lead to necrosis. In the last few years it has become possible to image calcium signaling events simultaneously in acinar, stellate, and immune cells in intact lobules of the exocrine pancreas. This has disclosed processes by which these cells interact with each other, particularly in relation to the initiation and development of acute pancreatitis. By unraveling the molecular mechanisms underlying this disease, several promising therapeutic intervention sites have been identified. This provides hope that we may soon be able to effectively treat this often fatal disease.

Clinical importance of main pancreatic duct variants and possible correlation with pancreatic diseases.

Background: Except for pancreas divisum (PD), the prevalence of anatomic variants of the main pancreatic duct (MPD) seems to be insufficiently investigated. To date, their role in the occurrence of pancreatic exocrine insufficiency (PEI) and morphological changes suggestive of chronic pancreatitis (CP) has remained unclear.Methods: A systematic review was performed, searching MEDLINE and Web of Science, limited to articles published between 1960 and 1 June 2019.Results: Our review included a total number of 3234 subjects. The most common variant of MPD was type 3, followed by type 1, indicating MPD drainage pattern into major papilla (MP) as the most frequent. A sub-variant of type 3, known as 'reverse pancreas divisum' had a prevalence of 2.2%. Type 4 variant- PD, was found in 6.4% of all cases. The most common sub-variant of PD was complete PD, followed by incomplete PD and variant with MPD as only pancreatic duct. Type 5 variant (including ansa pancreatica) was present in 2.9% of subjects. Apart from one study with a significantly higher frequency of morphological changes suggestive of CP in patients with ansa pancreatica, the studies stated no significant association between pancreatic disease and MPD variants. Furthermore, only one study examined the influence of MPD variants on exocrine pancreatic function. Although equivocal, this association is most likely found to be insignificant.Conclusion: To elucidate linkage between MPD variants and the occurrence of chronic pancreatitis and impairment of pancreatic exocrine function, further clinical investigations are warranted.

Healthy pancreatic parenchymal volume and its relationship to exocrine function.

BACKGROUND: Pancreatic atrophy as a finding of chronic pancreatitis has largely been a subjective finding. Cross-sectional imaging should provide a means to quantify pancreatic atrophy. OBJECTIVE: The purposes of this study were to: (1) quantify pancreatic volume by magnetic resonance imaging (MRI) in a cohort of children without pancreatic disease, (2) define predictors of pancreatic volume and (3) assess the relationship between pancreatic volume and pancreatic fluid secretion. MATERIALS AND METHODS: This study involved further analysis of data collected as part of an institutional review board-approved prospective study of secreted fluid volume in response to secretin in 50 healthy children ages 6-16 years. The pancreas was manually segmented on axial MR images to calculate pancreatic volume. Pearson correlation or the Student's t-test were used to define associations between pancreatic volume and patient characteristics and previously calculated secreted fluid volume. Quantile regression was used to define the 5th percentile for pancreatic volume based on body surface area (BSA) [1]. RESULTS: Mean pancreatic volume was 46.0±18.8 mL with no significant difference based on sex (boys: 42.4±19 mL, girls: 49.1±18.3 mL, P=0.21). Pancreatic volume was moderately correlated with age (r=0.51, P=0.002) and strongly correlated with BSA (r=0.75, P<0.0001), with the 5th percentile for pancreatic volume defined by: (24.66×BSA) - 4.97. Pancreatic volume was moderately correlated with volume of fluid secreted after secretin administration (r=0.51, P=0.0002). CONCLUSION: We report increasing pancreatic volumes by MRI during childhood in a cohort of children without pancreatic disease. We have also shown that pancreatic volume is associated with secreted fluid volume as measured by MRI.

Mouse pancreatic ductal organoid culture as a relevant model to study exocrine pancreatic ion secretion.

Pancreatic exocrine secretory processes are challenging to investigate on primary epithelial cells. Pancreatic organoid cultures may help to overcome shortcomings of the current models, however the ion secretory processes in pancreatic organoids-and therefore their physiological relevance or their utility in disease modeling-are not known. To answer these questions, we provide side-by-side comparison of gene expression, morphology, and function of epithelial cells in primary isolated pancreatic ducts and organoids. We used mouse pancreatic ductal fragments for experiments or were grown in Matrigel to obtain organoid cultures. Using PCR analysis we showed that gene expression of ion channels and transporters remarkably overlap in primary ductal cells and organoids. Morphological analysis with scanning electron microscopy revealed that pancreatic organoids form polarized monolayers with brush border on the apical membrane. Whereas the expression and localization of key proteins involved in ductal secretion (cystic fibrosis transmembrane conductance regulator, Na+/H+ exchanger 1 and electrogenic Na+/HCO3- cotransporter 1) are equivalent to the primary ductal fragments. Measurements of intracellular pH and Cl- levels revealed no significant difference in the activities of the apical Cl-/HCO3- exchange, or in the basolateral Na+ dependent HCO3- uptake. In summary we found that ion transport activities in the mouse pancreatic organoids are remarkably similar to those observed in freshly isolated primary ductal fragments. These results suggest that organoids can be suitable and robust model to study pancreatic ductal epithelial ion transport in health and diseases and facilitate drug development for secretory pancreatic disorders like cystic fibrosis, or chronic pancreatitis.

Long-term pancreatic exocrine and endometabolic functionality after pancreaticoduodenectomy. Comparison between pancreaticojejunostomy and pancreatic duct occlusion with fibrin glue.

OBJECTIVE: Even if pancreatic pathologies, residual fibrosis, residual amount of parenchyma, and anastomotic patency are recognized as main causes of exocrine and glycemic impairment after pancreaticoduodenectomy (PD), few data are reported concerning the role of the different pancreatic remnant treatment techniques. The objective of the study is to assess and compare exocrine functionality, glycemic pattern, nutritional status, and quality of life (QoL) after PD between pancreaticojejunostomy (PJ) and pancreatic duct occlusion (PDO), both in an objective and a subjective manner. PATIENTS AND METHODS: Thirty-two patients (16 PJ and 16 PDO) were evaluated after a mean follow-up of 21 months after surgery. Exocrine insufficiency was objectively evaluated through the 13C-labelled mixed triglyceride breath test. Fasting glucose, fasting insulin, HbA1c and HOMA-IR values were used to assess glucose metabolism. For these two outcomes, anamnestic data were also collected. QoL was assessed with GIQLI, SF-36, EORTC-QLQ-C30, and EORTC-PAN-26 questionnaires. RESULTS: The 13C-labelled mixed triglyceride breath test detected a lipid digestive insufficiency in 56% of patients after PJ and 100% after PDO respectively (p = 0.007). However, no difference was observed between the two groups regarding postoperative necessity of substitutive pancreatic enzymes. Nutritional status, fasting plasma glucose, fasting insulin, HbA1c levels, HOMA-IR values and postoperative necessity of insulin or oral antidiabetic agents were comparable between the two groups. QoL measurements showed similar results. However, in the subdomains analysis, better outcomes were reported regarding digestive symptoms and physical functioning for PJ and PDO respectively. CONCLUSIONS: Even if an objective exocrine major impairment was evidenced after PDO, this result did not impact the need for a higher rate of postoperative substitutive enzymes. In terms of glycemic pattern, nutritional status, and QoL, the two techniques turn out to be comparable.

Functional Correlation Between the Pancreas and the Small Intestine in Humans: The First Evaluation Using a Newly Developed Enteroscopy.

OBJECTIVES: The aim of this study is to evaluate a functional correlation between the pancreas and the small intestine and the association of this relationship with nutritional status, using magnifying enteroscopy. METHODS: The subjects were adults aged 20 years or older who underwent upper gastrointestinal endoscopy. An endoscope was inserted into the jejunum, and 10% glucose was sprayed under magnifying observation to evaluate changes in blood flow in the villous capillary network. Mucosal biopsy was performed before and after spraying to evaluate the incretin response in the jejunal mucosa. RESULTS: A total of 124 patients participated in the study. There was a positive correlation between villous blood flow change and exocrine pancreas function (R = 0.4337, P < 0.0001). Changes of gastric inhibitory polypeptide and glucagon-like peptide messenger RNAs in biopsy samples were positively correlated with endocrine pancreas function in 88 patients without treatment for diabetes (R = 0.4314, P = 0.0012; R = 0.4112, P = 0.0081). In patients with lower villous blood flow change and decreased pancreatic exocrine function, the prognostic nutritional index were significantly lower (P = 0.0098), compared with other patients. CONCLUSIONS: This study provides the first evidence of a close functional correlation between the pancreas and the small intestine.

Hes1 Controls Exocrine Cell Plasticity and Restricts Development of Pancreatic Ductal Adenocarcinoma in a Mouse Model.

Perturbation of pancreatic acinar cell state can lead to acinar-to-ductal metaplasia (ADM), a precursor lesion to the development of pancreatic ductal adenocarcinoma (PDAC). In the pancreas, Notch signaling is active both during development and in adult cellular differentiation processes. Hes1, a key downstream target of the Notch signaling pathway, is expressed in the centroacinar compartment of the adult pancreas as well as in both preneoplastic and malignant lesions. In this study, we used a murine genetic in vivo approach to ablate Hes1 in pancreatic progenitor cells (Ptf1a+/Cre; Hes1fl/fl). Using this model, we studied the role of Hes1 in both acinar cell plasticity and pancreatic regeneration after caerulein-induced pancreatitis and in KrasG12D-driven PDAC development. We show that, although pancreatic development is not perturbed on the deletion of Hes1, terminal acinar differentiation in the adult pancreas is compromised. Moreover, the loss of Hes1 leads to the impaired regeneration of the exocrine compartment, accelerated fatty metaplasia, and persistent ADM after acute caerulein-induced pancreatitis. In KrasG12D-driven carcinogenesis, Hes1 ablation resulted in increased ADM, decreased formation of high-grade pancreatic intraepithelial neoplasias, and accelerated development of PDAC with shortened survival time. In conclusion, Hes1 plays a key role in acinar cell integrity and plasticity on cellular insults. Furthermore, Hes1 is an essential component of the pancreatic intraepithelial neoplasias-to-PDAC route in KrasG12D-driven mouse pancreatic carcinogenesis.

ß-Cell regeneration through the transdifferentiation of pancreatic cells: Pancreatic progenitor cells in the pancreas.

Pancreatic progenitor cell research has been in the spotlight, as these cells have the potential to replace pancreatic ß-cells for the treatment of type 1 and 2 diabetic patients with the absence or reduction of pancreatic ß-cells. During the past few decades, the successful treatment of diabetes through transplantation of the whole pancreas or isolated islets has nearly been achieved. However, novel sources of pancreatic islets or insulin-producing cells are required to provide sufficient amounts of donor tissues. To overcome this limitation, the use of pancreatic progenitor cells is gaining more attention. In particular, pancreatic exocrine cells, such as duct epithelial cells and acinar cells, are attractive candidates for ß-cell regeneration because of their differentiation potential and pancreatic lineage characteristics. It has been assumed that ß-cell neogenesis from pancreatic progenitor cells could occur in pancreatic ducts in the postnatal stage. Several studies have shown that insulin-producing cells can arise in the duct tissue of the adult pancreas. Acinar cells also might have the potential to differentiate into insulin-producing cells. The present review summarizes recent progress in research on the transdifferentiation of pancreatic exocrine cells into insulin-producing cells, especially duct and acinar cells.

Loss of Periostin Results in Impaired Regeneration and Pancreatic Atrophy after Cerulein-Induced Pancreatitis.

The extracellular matrix molecule periostin (POSTN, encoded by POSTN), which is secreted by activated pancreatic stellate cells, has important functions in chronic pancreatitis and pancreatic cancer. However, the role of POSTN in acute pancreatitis and subsequent regeneration processes has not been addressed so far. We analyzed the function of POSTN in pancreatic exocrine regeneration after the induction of a severe acute pancreatitis. Postn-deficient mice and wild-type control animals received repetitive cerulein injections, and a detailed histologic analysis of pancreatic tissues was performed. Although there was no difference in pancreatitis severity in the acute inflammatory phase, the recovery of the exocrine pancreas was massively impaired in Postn-deficient mice. Loss of Postn expression was accompanied by strong pancreatic atrophy and acinar-to-adipocyte differentiation, which was also reflected in gene expression patterns. Our data suggest that POSTN is a crucial factor for proper exocrine lineage-specific regeneration after severe acute pancreatitis.

The Physiology and Pathophysiology of Pancreatic Ductal Secretion: The Background for Clinicians.

The human exocrine pancreas consists of 2 main cell types: acinar and ductal cells. These exocrine cells interact closely to contribute to the secretion of pancreatic juice. The most important ion in terms of the pancreatic ductal secretion is HCO3. In fact, duct cells produce an alkaline fluid that may contain up to 140 mM NaHCO3, which is essential for normal digestion. This article provides an overview of the basics of pancreatic ductal physiology and pathophysiology. In the first part of the article, we discuss the ductal electrolyte and fluid transporters and their regulation. The central role of cystic fibrosis transmembrane conductance regulator (CFTR) is highlighted, which is much more than just a Cl channel. We also review the role of pancreatic ducts in severe debilitating diseases such as cystic fibrosis (caused by various genetic defects of cftr), pancreatitis, and diabetes mellitus. Stimulation of ductal secretion in cystic fibrosis and pancreatitis may have beneficial effects in their treatment.

Serotonin promotes acinar dedifferentiation following pancreatitis-induced regeneration in the adult pancreas.

The exocrine pancreas exhibits a distinctive capacity for tissue regeneration and renewal following injury. This regenerative ability has important implications for a variety of disorders, including pancreatitis and pancreatic cancer, diseases associated with high morbidity and mortality. Thus, understanding its underlying mechanisms may help in developing therapeutic interventions. Serotonin has been recognized as a potent mitogen for a variety of cells and tissues. Here we investigated whether serotonin exerts a mitogenic effect in pancreatic acinar cells in three regenerative models, inflammatory tissue injury following pancreatitis, tissue loss following partial pancreatectomy, and thyroid hormone-stimulated acinar proliferation. Genetic and pharmacological techniques were used to modulate serotonin levels in vivo. Acinar dedifferentiation and cell cycle progression during the regenerative phase were investigated over the course of 2 weeks. By comparing acinar proliferation in the different murine models of regeneration, we found that serotonin did not affect the clonal regeneration of mature acinar cells. Serotonin was, however, required for acinar dedifferentiation following inflammation-mediated tissue injury. Specifically, lack of serotonin resulted in delayed up-regulation of progenitor genes and delayed the formation of acinar-to-ductal metaplasia and defective acinar cell proliferation. We identified serotonin-dependent acinar secretion as a key step in progenitor-based regeneration, as it promoted acinar cell dedifferentiation and the recruitment of type 2 macrophages. Finally, we identified a regulatory Hes1-Ptfa axis in the uninjured adult pancreas, activated by zymogen secretion. Our findings indicated that serotonin plays a critical role in the regeneration of the adult pancreas following pancreatitis by promoting the dedifferentiation of acinar cells.

Regeneration and repair of the exocrine pancreas.

Pancreatitis is caused by inflammatory injury to the exocrine pancreas, from which both humans and animal models appear to recover via regeneration of digestive enzyme-producing acinar cells. This regenerative process involves transient phases of inflammation, metaplasia, and redifferentiation, driven by cell-cell interactions between acinar cells, leukocytes, and resident fibroblasts. The NFκB signaling pathway is a critical determinant of pancreatic inflammation and metaplasia, whereas a number of developmental signals and transcription factors are devoted to promoting acinar redifferentiation after injury. Imbalances between these proinflammatory and prodifferentiation pathways contribute to chronic pancreatitis, characterized by persistent inflammation, fibrosis, and acinar dedifferentiation. Loss of acinar cell differentiation also drives pancreatic cancer initiation, providing a mechanistic link between pancreatitis and cancer risk. Unraveling the molecular bases of exocrine regeneration may identify new therapeutic targets for treatment and prevention of both of these deadly diseases.

Anatomic variants of the pancreatic duct and their clinical relevance: an MR-guided study in the general population.

OBJECTIVES: To investigate the frequency of pancreatic duct (PD) variants and their effect on pancreatic exocrine function in a population-based study using non-invasive secretin-stimulated magnetic resonance cholangiopancreatography (sMRCP). METHODS: Nine hundred and ninety-five volunteers, 457 women and 538 men, aged 51.9 ± 13.4 years, underwent navigator-triggered, T2-weighted, 3D turbo spin echo MRCP on a 1.5 T system after 1 unit/kg secretin administration. Two readers evaluated images for PD variants. Pancreatic exocrine function and morphological signs of chronic pancreatitis such as abnormalities of the main PD, side branch dilatation, and pancreatic cysts were evaluated and related to PD variants using a Kruskal-Wallis test and post hoc analysis. RESULTS: Of all sMRCP, 93.2% were of diagnostic quality. Interobserver reliability for detection of PD variants was found to be kappa 0.752 (95 %CI, 0.733 - 0.771). Normal PD variants were observed in 90.4% (n = 838/927). Variants of pancreas divisum was identified in 9.6% (n = 89/927). Abnormalities of the main PD, side branch dilatation, and pancreatic cysts were observed in 2.4%, 16.6%, and 27.7%, respectively, and were not significantly different between pancreas divisum and non-divisum group (P = 0.122; P = 0.152; P = 0.741). There was no association between PD variants and pancreatic exocrine function (P = 0.367). CONCLUSION: PD variants including pancreas divisum are not associated with morphological signs of chronic pancreatitis or restriction of pancreatic exocrine function. KEY POINTS: MRCP allows the evaluation of pancreatic duct variants and morphological change. Pancreatic duct variants are not associated with morphological signs of chronic pancreatitis. Pancreas divisum is not accompanied by restriction of pancreatic exocrine function. Pancreatic duct variants including pancreas divisum are limited in their clinical relevance.

The cystic fibrosis of exocrine pancreas.

The cystic fibrosis transmembrane conductance regulator (CFTR) protein is highly expressed in the pancreatic duct epithelia and permits anions and water to enter the ductal lumen. This results in an increased volume of alkaline fluid allowing the highly concentrated proteins secreted by the acinar cells to remain in a soluble state. This work will expound on the pathophysiology and pathology caused by the malfunctioning CFTR protein with special reference to ion transport and acid-base abnormalities both in humans and animal models. We will also discuss the relationship between cystic fibrosis (CF) and pancreatitis, and outline present and potential therapeutic approaches in CF treatment relevant to the pancreas.

Gata6 is required for complete acinar differentiation and maintenance of the exocrine pancreas in adult mice.

OBJECTIVES: Previous studies have suggested an important role of the transcription factor Gata6 in endocrine pancreas, while GATA6 haploinsufficient inactivating mutations cause pancreatic agenesis in humans. We aimed to analyse the effects of Gata6 inactivation on pancreas development and function. DESIGN: We deleted Gata6 in all epithelial cells in the murine pancreas at the onset of its development. Acinar proliferation, apoptosis, differentiation and exocrine functions were assessed using reverse transcriptase quantitative PCR (RT-qPCR), chromatin immunoprecipitation, immunohistochemistry and enzyme assays. Adipocyte transdifferentiation was assessed using electron microscopy and genetic lineage tracing. RESULTS: Gata6 is expressed in all epithelial cells in the adult mouse pancreas but it is only essential for exocrine pancreas homeostasis: while dispensable for pancreatic development after e10.5, it is required for complete acinar differentiation, for establishment of polarity and for the maintenance of acinar cells in the adult. Gata6 regulates directly the promoter of genes coding for digestive enzymes and the transcription factors Rbpjl and Mist1. Upon pancreas-selective Gata6 inactivation, massive loss of acinar cells and fat replacement take place. This is accompanied by increased acinar apoptosis and proliferation, acinar-to-ductal metaplasia and adipocyte transdifferentiation. By contrast, the endocrine pancreas is spared. CONCLUSIONS: Our data show that Gata6 is required for the complete differentiation of acinar cells through multiple transcriptional regulatory mechanisms. In addition, it is required for the maintenance of the adult acinar cell compartment. Our studies suggest that GATA6 alterations may contribute to diseases of the human adult exocrine pancreas.

Regeneration of the exocrine pancreas is delayed in telomere-dysfunctional mice.

INTRODUCTION: Telomere shortening is a cell-intrinsic mechanism that limits cell proliferation by induction of DNA damage responses resulting either in apoptosis or cellular senescence. Shortening of telomeres has been shown to occur during human aging and in chronic diseases that accelerate cell turnover, such as chronic hepatitis. Telomere shortening can limit organ homeostasis and regeneration in response to injury. Whether the same holds true for pancreas regeneration in response to injury is not known. METHODS: In the present study, pancreatic regeneration after acute cerulein-induced pancreatitis was studied in late generation telomerase knockout mice with short telomeres compared to telomerase wild-type mice with long telomeres. RESULTS: Late generation telomerase knockout mice exhibited impaired exocrine pancreatic regeneration after acute pancreatitis as seen by persistence of metaplastic acinar cells and markedly reduced proliferation. The expression levels of p53 and p21 were not significantly increased in regenerating pancreas of late generation telomerase knockout mice compared to wild-type mice. CONCLUSION: Our results indicate that pancreatic regeneration is limited in the context of telomere dysfunction without evidence for p53 checkpoint activation.

Molecular and cellular regulation of pancreatic acinar cell function.

PURPOSE OF REVIEW: This review focuses on studies from the past year that have greatly advanced our understanding of molecular and cellular regulation of pancreatic acinar cell function. RECENT FINDINGS: Recent advances focus on signals dictating pancreatic development, acinar cell fate, pancreatic growth, and secretion. Regeneration of acinar cells after pancreatitis depends on expression of embryonic signals in mature acinar cells. In this setting, acinar cells can also transdifferentiate into adipose cells. With the forced induction of certain early and endocrine-driving transcription factors, acinar cells can also transdifferentiate into beta-cells. There has also been an increased understanding of acinar-to-ductal metaplasia and the subsequent formation of pancreatic intraepithelial neoplasia lesions. Multiple proteins involved in secretion have been characterized, including small guanosine triphosphate-binding proteins, soluble N-ethylmaleimide-sensitive factor attachment proteins, and ion channels. SUMMARY: These findings demonstrate the regenerative potential of the acinar cell to mitigate injurious states such as pancreatitis. The ability of acinar cells to transdifferentiate into beta-cells could potentially provide a treatment for diabetes. Finally, the results might be helpful in preventing malignant transformation events arising from the acinar cell. Developments in proteomics and computer modeling could expand our view of proteins mediating acinar cell function.

Glucagon-like peptide-1 receptor activation modulates pancreatitis-associated gene expression but does not modify the susceptibility to experimental pancreatitis in mice.

OBJECTIVE: Clinical reports link use of the glucagon-like peptide-1 receptor (GLP-1R) agonists exenatide and liraglutide to pancreatitis. However, whether these agents act on the exocrine pancreas is poorly understood. RESEARCH DESIGN AND METHODS: We assessed whether the antidiabetic agents exendin (Ex)-4, liraglutide, the dipeptidyl peptidase-4 inhibitor sitagliptin, or the biguanide metformin were associated with changes in expression of genes associated with the development of experimental pancreatitis. The effects of Ex-4 when administered before or after the initiation of caerulein-induced experimental pancreatitis were determined. The importance of endogenous GLP-1R signaling for gene expression in the exocrine pancreas and the severity of pancreatitis was assessed in Glp1r(-/-) mice. RESULTS: Acute administration of Ex-4 increased expression of egr-1 and c-fos in the exocrine pancreas. Administration of Ex-4 or liraglutide for 1 week increased pancreas weight and induced expression of mRNA transcripts encoding the anti-inflammatory proteins pancreatitis-associated protein (PAP) (RegIIIbeta) and RegIIIalpha. Chronic Ex-4 treatment of high-fat-fed mice increased expression of PAP and reduced pancreatic expression of mRNA transcripts encoding for the proinflammatory monocyte chemotactic protein-1, tumor necrosis factor-alpha, and signal transducer and activator of transcription-3. Sitagliptin and metformin did not significantly change pancreatic gene expression profiles. Ex-4 administered before or after caerulein did not modify the severity of experimental pancreatitis, and levels of pancreatic edema and serum amylase were comparable in caerulein-treated Glp1r(-/-) versus Glp1r(+/+) mice. CONCLUSIONS: These findings demonstrate that GLP-1 receptor activation increases pancreatic mass and selectively modulates the expression of genes associated with pancreatitis. However, activation or genetic elimination of GLP-1R signaling does not modify the severity of experimental pancreatitis in mice.

Carbonic anhydrase II-positive pancreatic cells are progenitors for both endocrine and exocrine pancreas after birth.

The regenerative process in the pancreas is of particular interest because diabetes results from an inadequate number of insulin-producing beta cells and pancreatic cancer may arise from the uncontrolled growth of progenitor/stem cells. Continued and substantial growth of islet tissue occurs after birth in rodents and humans, with additional compensatory growth in response to increased demand. In rodents there is clear evidence of pancreatic regeneration after some types of injury, with proliferation of preexisting differentiated cell types accounting for some replacement. Additionally, neogenesis or the budding of new islet cells from pancreatic ducts has been reported, but the existence and identity of a progenitor cell have been debated. We hypothesized that the progenitor cells are duct epithelial cells that after replication undergo a regression to a less differentiated state and then can form new endocrine and exocrine pancreas. To directly test whether ductal cells serve as pancreatic progenitors after birth and give rise to new islets, we generated transgenic mice expressing human carbonic anhydrase II (CAII) promoter: Cre recombinase (Cre) or inducible CreER(TM) to cross with ROSA26 loxP-Stop-loxP LacZ reporter mice. We show that CAII-expressing cells within the pancreas act as progenitors that give rise to both new islets and acini normally after birth and after injury (ductal ligation). This identification of a differentiated pancreatic cell type as an in vivo progenitor of all differentiated pancreatic cell types has implications for a potential expandable source for new islets for replenishment therapy for diabetes.

Indications and surgical treatment of chronic pancreatitis.

BACKGROUND: Some patients with chronic pancreatitis (CP) may require surgery mainly because of intractable pain, suspicion of malignancy, or complications related to CP. This study aimed to analyze the efficacy of surgical treatment for patients with CP in terms of pain relief, control of local complications, and pancreatic endocrine/exocrine function. METHODS: Twenty-six patients with CP were treated surgically at our hospital from June 1985 to November 2005. The clinical data of these patients were analyzed retrospectively. RESULTS: The follow-up time ranged from 8 to 130 months with a median of 60.6 months. No patients were lost to follow-up. All patients had improvement of clinical symptoms such as abdominal pain, steatorrhea and weight loss, to some degree, especially pain relief in patients with good dilation and high pressure of the main pancreatic duct. The endocrine and exocrine functions were not alleviated in all patients, otherwise the impaired glucose tolerance was improved in 8 (30.8%), 15 (57.7%) maintained the same body weight, one (3.8%) had an acute attack of CP, and 2 (7.7%) developed pancreatic carcinoma in the 16th and 28th month postoperatively and died within 3 years after operation for CP. The 1-, 3-, 5-year pain-free rates of CP patients were 96.2% (25/26), 88.5% (23/26) and 84.6% (22/26), respectively. CONCLUSIONS: In selected patients with CP, surgical treatment is a safe procedure and can effectively relieve pain and control local complications; also, it is helpful to improve the quality of life for patients with pancreatitis, and to control the development of this disease.