Glycogen synthase kinase‐3β ablation limits pancreatitis‐induced acinar‐to‐ductal metaplasia

Acinar‐to‐ductal metaplasia (ADM) is a reversible epithelial transdifferentiation process that occurs in the pancreas in response to acute inflammation. ADM can rapidly progress towards pre‐malignant pancreatic intraepithelial neoplasia (PanIN) lesions in the presence of mutant KRas and ultimately pancreatic adenocarcinoma (PDAC). In the present work, we elucidate the role and related mechanism of glycogen synthase kinase‐3beta (GSK‐3β) in ADM development using in vitro 3D cultures and genetically engineered mouse models. We show that GSK‐3β promotes TGF‐α‐induced ADM in 3D cultured primary acinar cells, whereas deletion of GSK‐3β attenuates caerulein‐induced ADM formation and PanIN progression in Kras^G12D transgenic mice. Furthermore, we demonstrate that GSK‐3β ablation influences ADM formation and PanIN progression by suppressing oncogenic KRas‐driven cell proliferation. Mechanistically, we show that GSK‐3β regulates proliferation by increasing the activation of S6 kinase. Taken together, these results indicate that GSK‐3β participates in early pancreatitis‐induced ADM and thus could be a target for the treatment of chronic pancreatitis and the prevention of PDAC progression. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

p21WAF1/Cip1 limits senescence and acinar‐to‐ductal metaplasia formation during pancreatitis

Trans‐differentiation of pancreatic acinar cells into ductal‐like lesions, a process defined as acinar‐to‐ductal metaplasia (ADM), is observed in the course of organ regeneration following pancreatitis. In addition, ADM is found in association with pre‐malignant PanIN lesions and correlates with an increased risk of pancreatic adenocarcinoma (PDAC). Human PDAC samples show down‐regulation of p21^WAF1/Cip1, a key regulator of cell cycle and cell differentiation. Here we investigated whether p21 down‐regulation is implicated in controlling the early events of acinar cell trans‐differentiation and ADM formation. p21‐mediated regulation of ADM formation and regression was analysed in vivo during the course of cerulein‐induced pancreatitis, using wild‐type (WT) and p21‐deficient (p21^?/?) mice. Biochemical and immunohistochemical methods were used to evaluate disease progression over 2 weeks of the disease and during a recovery phase. We found that p21 was strongly up‐regulated in WT acinar cells during pancreatitis, while it was absent in ADM areas, suggesting that p21 down‐regulation is associated with ADM formation. In support of this hypothesis, p21^?/? mice showed a significant increase in number and size of metaplasia. In addition, p21 over‐expression in acinar cells reduced ADM formation in vitro, suggesting that the protein regulates the metaplastic transition in a cell‐autonomous manner. p21^?/? mice displayed increased expression and relocalization of β‐catenin both during pancreatitis and in the subsequent recovery phase. Finally, loss of p21 was accompanied by increased DNA damage and development of senescence. Our findings are consistent with a gate‐keeper role of p21 in acinar cells to limit senescence activation and ADM formation during pancreatic regeneration. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd     

Chronic Continuous Exenatide Infusion Does Not Cause Pancreatic Inflammation and Ductal Hyperplasia in Non-Human Primates

In this study, we aimed to evaluate the effects of exenatide (EXE) treatment on exocrine pancreas of nonhuman primates. To this end, 52 baboons (Papio hamadryas) underwent partial pancreatectomy, followed by continuous infusion of EXE or saline (SAL) for 14 weeks. Histological analysis, immunohistochemistry, Computer Assisted Stereology Toolbox morphometry, and immunofluorescence staining were performed at baseline and after treatment. The EXE treatment did not induce pancreatitis, parenchymal or periductal inflammatory cell accumulation, ductal hyperplasia, or dysplastic lesions/pancreatic intraepithelial neoplasia. At study end, Ki-67–positive (proliferating) acinar cell number did not change, compared with baseline, in either group. Ki-67–positive ductal cells increased after EXE treatment (P = 0.04). However, the change in Ki-67–positive ductal cell number did not differ significantly between the EXE and SAL groups (P = 0.13). M-30–positive (apoptotic) acinar and ductal cell number did not change after SAL or EXE treatment. No changes in ductal density and volume were observed after EXE or SAL. Interestingly, by triple-immunofluorescence staining, we detected c-kit (a marker of cell transdifferentiation) positive ductal cells co-expressing insulin in ducts only in the EXE group at study end, suggesting that EXE may promote the differentiation of ductal cells toward a β-cell phenotype. In conclusion, 14 weeks of EXE treatment did not exert any negative effect on exocrine pancreas, by inducing either pancreatic inflammation or hyperplasia/dysplasia in nonhuman primates.Glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-IV (DPP-IV) inhibitors represent new classes of therapeutic agents for type 2 diabetes mellitus treatment acting by augmenting β-cell function while decreasing food intake and body weight.^1–7Isolated cases of pancreatitis have been reported in diabetic patients treated with GLP-1 receptor agonists and DPP-IV inhibitors, prompting the US Food and Drug Administration to issue alerts on possible adverse effects.⁸ Acute pancreatitis is a severe clinical condition characterized by pancreatic pathological changes and increased serum amylase and lipase levels. Obstructive gallstone disease, alcohol abuse, hypertriglyceridemia, obesity, and type 2 diabetes mellitus are the most common risk factors for pancreatitis and pancreatic cancer.^9–11Although pancreatitis and pancreatic cancer have been suggested to be more frequent in diabetic patients treated with GLP-1–based therapies, the methodologically heterogeneous literature available does not support a firm conclusion on whether GLP-1 receptor agonists or DPP-IV inhibitors are directly implicated in pancreatitis or pancreatic cancer.^8,12–25 Animal studies designed to examine the effect of GLP-1–based therapies on exocrine pancreas have also yielded conflicting results.^26–31In this study, we directly evaluated whether the GLP-1 receptor agonist exenatide (EXE) can promote inflammation/pancreatitis and hyperplasia/dysplasia in exocrine pancreas of baboons. Baboons have interesting genetic and physiological similarity to humans, develop similar pathological features, and represent a valuable model to study human diseases, such as insulin resistance, obesity, and type 2 diabetes mellitus.^32–38     

ATDC induces an invasive switch in KRAS-induced pancreatic tumorigenesis

The initiation of pancreatic ductal adenocarcinoma (PDA) is linked to activating mutations in KRAS. However, in PDA mouse models, expression of oncogenic mutant KRAS during development gives rise to tumors only after a prolonged latency or following induction of pancreatitis. Here we describe a novel mouse model expressing ataxia telangiectasia group D complementing gene (ATDC, also known as TRIM29 [tripartite motif 29]) that, in the presence of oncogenic KRAS, accelerates pancreatic intraepithelial neoplasia (PanIN) formation and the development of invasive and metastatic cancers. We found that ATDC up-regulates CD44 in mouse and human PanIN lesions via activation of β-catenin signaling, leading to the induction of an epithelial-to-mesenchymal transition (EMT) phenotype characterized by expression of Zeb1 and Snail1. We show that ATDC is up-regulated by oncogenic Kras in a subset of PanIN cells that are capable of invading the surrounding stroma. These results delineate a novel molecular pathway for EMT in pancreatic tumorigenesis, showing that ATDC is a proximal regulator of EMT.     

The epigenetic regulators Bmi1 and Ring1B are differentially regulated in pancreatitis and pancreatic ductal adenocarcinoma

Chronic pancreatitis and pancreatic ductal adenocarcinoma (PDAC) are associated with major changes in cell differentiation. These changes may be at the basis of the increased risk for PDAC among patients with chronic pancreatitis. Polycomb proteins are epigenetic silencers expressed in adult stem cells; up‐regulation of Polycomb proteins has been reported to occur in a variety of solid tumours such as colon and breast cancer. We hypothesized that Polycomb might play a role in preneoplastic states in the pancreas and in tumour development/progression. To test these ideas, we determined the expression of PRC1 complex proteins (Bmi1 and Ring1b) during pancreatic development and in pancreatic tissue from mouse models of disease: acute and chronic pancreatic injury, duct ligation, and in K‐Ras^G12V conditional knock‐in and caerulein‐treated K‐Ras^G12V mice. The study was extended to human pancreatic tissue samples. To obtain mechanistic insights, Bmi1 expression in cells undergoing in vitro exocrine cell metaplasia and the effects of Bmi1 depletion in an acinar cancer cell line were studied. We found that Bmi1 and Ring1B are expressed in pancreatic exocrine precursor cells during early development and in ductal and islet cells—but not acinar cells—in the adult pancreas. Bmi1 expression was induced in acinar cells during acute injury, in acinar–ductal metaplastic lesions, as well as in pancreatic intraepithelial neoplasia (PanIN) and PDAC. In contrast, Ring1B expression was only significantly and persistently up‐regulated in high‐grade PanINs and in PDAC. Bmi1 knockdown in cultured acinar tumour cells led to changes in the expression of various digestive enzymes. Our results suggest that Bmi1 and Ring1B are modulated in pancreatic diseases and could contribute differently to tumour development. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Origin of pancreatic ductal adenocarcinoma from atypical flat lesions: a comparative study in transgenic mice and human tissues

Pancreatic ductal adenocarcinoma (PDAC) and its precursor lesions, pancreatic intraepithelial neoplasia (PanIN), display a ductal phenotype. However, there is evidence in genetically defined mouse models for PDAC harbouring a mutated kras under the control of a pancreas-specific promoter that ductal cancer might arise in the centroacinar-acinar region, possibly through a process of acinar-ductal metaplasia (ADM). In order to further elucidate this model of PDAC development, an extensive expression analysis and molecular characterization of the putative and already established (PanIN) precursor lesions were performed in the Kras(G12D/+) ; Ptf1a-Cre(ex1/+) mouse model and in human tissues, focusing on lineage markers, developmental pathways, cell cycle regulators, apomucins, and stromal activation markers. The results of this study show that areas of ADM are very frequent in the murine and human pancreas and represent regions of increased proliferation of cells with precursor potential. Moreover, atypical flat lesions originating in areas of ADM are the most probable precursors of PDAC in the Kras(G12D/+); Ptf1a-Cre(ex1/+) mice and similar lesions were also found in the pancreas of three patients with a strong family history of PDAC. In conclusion, PDAC development in Kras(G12D/+); Ptf1a-Cre(ex1/+) mice starts from ADM and a similar process might also take place in patients with a strong family history of PDAC.     

Expression patterns of epiplakin1 in pancreas, pancreatic cancer and regenerating pancreas

Epiplakin1 (Eppk1) is a plakin family gene with its function remains largely unknown, although the plakin genes are known to function in interconnecting cytoskeletal filaments and anchoring them at plasma membrane-associated adhesive junction. Here we analyzed the expression patterns of Eppk1 in the developing and adult pancreas in the mice. In the embryonic pancreas, Eppk1+/Pdx1+ and Eppk1+/Sox9+ pancreatic progenitor cells were observed in early pancreatic epithelium. Since Pdx1 expression overlapped with that of Sox9 at this stage, these multipotent progenitor cells are Eppk1+/Pdx1+/Sox9+ cells. Then Eppk1 expression becomes confined to Ngn3+ or Sox9+ endocrine progenitor cells, and p48+ exocrine progenitor cells, and then restricted to the duct cells and a cells at birth. In the adult pancreas, Eppk1 is expressed in centroacinar cells (CACs) and in duct cells. Eppk1 is observed in pancreatic intraepithelial neoplasia (PanIN), previously identified as pancreatic ductal adenocarcinoma (PDAC) precursor lesions. In addition, the expansion of Eppk1-positive cells occurs in a caerulein-induced acute pancreatitis, an acinar cell regeneration model. Furthermore, in the partial pancreatectomy (Px) regeneration model using mice, Eppk1 is expressed in "ducts in foci", a tubular structure transiently induced. These results suggest that Eppk1 serves as a useful marker for detecting pancreatic progenitor cells in developing and regenerating pancreas.     

Update on pancreatic intraepithelial neoplasia

Pancreatic intraepithelial neoplasia (PanIN) is a histologically well-defined precursor to invasive ductal adenocarcinoma of the pancreas. PanINs are remarkably common lesions, particularly in the elderly population. Molecular studies have helped establish the progression of PanIN to invasive cancer, and recently genetically engineered mouse models have been generated that recapitulate the entire spectrum of lesions from precursor to invasive pancreatic cancer. Some PanIN lesions produce lobulocentric atrophy of the pancreatic parenchyma, and, when multifocal, this lobulocentric atrophy may be detectable using currently available imaging techniques such as endoscopic ultrasound. The association of acinar-ductal metaplasia with PanIN lesions has led some to hypothesize that PanINs develop from acinar cells that undergo acinar-ductal metaplasia.     

In vivo Notch reactivation in differentiating cochlear hair cells induces Sox2 and Prox1 expression but does not disrupt hair cell maturation

Background: Notch signaling is active in mouse cochlear prosensory progenitors but declines in differentiating sensory hair cells (HCs). Overactivation of the Notch1 intracellular domain (NICD) in progenitors blocks HC fate commitment and/or differentiation. However, it is not known whether reactivation of NICD in differentiating HCs also interrupts their developmental program and reactivates its downstream targets. Results: By analyzing Atoh1^CreER+; Rosa26‐NICD^loxp/+ or Atoh1^CreER+; Rosa26‐NICD^loxp/+; RBP‐J^loxp/loxp mice, we demonstrated that ectopic NICD in differentiating HCs caused reactivation of Sox2 and Prox1 in an RBP‐J‐dependent manner. Interestingly, Prox1 reactivation was exclusive to outer HCs (OHCs). In addition, lineage tracing analysis of Prox1^CreER/+; Rosa26‐EYFP^loxp/+ and Prox1^CreEGFP/+; Rosa26‐EYFP^loxp/+ mice showed that nearly all HCs experiencing Prox1 expression were OHCs. Surprisingly, these HCs still matured normally with expression of prestin, wild‐type‐like morphology, and uptake of FM4‐64FX dye at adult ages. Conclusions: Our results suggest that the developmental program of cochlear differentiating HCs is refractory to Notch reactivation and that Notch is an upstream regulator of Sox2 and Prox1 in cochlear development. In addition, our results support that Sox2 and Prox1 should not be the main blockers for terminal differentiation of HCs newly regenerated from postnatal cochlear SCs that still maintain Sox2 and Prox1 expression. Developmental Dynamics 241:684–696, 2012. © 2012 Wiley Periodicals, Inc.     

Impact of peroxisome proliferator-activated receptor γ on angiotensin II type 1 receptor-mediated insulin sensitivity,vascular inflammation and atherogenesis in hypercholesterolemic mice

Introduction

The angiotensin II type 1 receptor (AT1R) and the peroxisome proliferator-activated receptor γ (PPARγ) have been implicated in the pathogenesis of atherosclerosis. A number of studies have reported that AT1R inhibition or genetic AT1R disruption and PPARγ activation inhibit vascular inflammation and improve glucose and lipid metabolism, underscoring a molecular interaction of AT1R and PPARγ. We here analyzed the hypothesis that vasculoprotective anti-inflammatory and metabolic effects of AT1R inhibition are mediated by PPARγ.

Material and methods

Female ApoE^–/–/AT1R^–/– mice were fedwith a high-fat and cholesterol-rich diet and received continuous treatment with the selective PPARγ antagonist GW9662 or vehicle at a rate of 700 ng/kg/min for 4 weeks using subcutaneously implanted osmotic mini-pumps. Additionally, one group of female ApoE^–/– mice served as a control group. After treatment for 4 weeks mice were sacrificed and read-outs (plaque development, vascular inflammation and insulinsensitivity) were performed.

Results

Using AT1R deficient ApoE^–/– mice (ApoE^–/–/AT1R^–/– mice) we found decreased cholesterol-induced endothelial dysfunction and atherogenesis compared to ApoE^–/– mice. Inhibition of PPARγ by application of the specific PPARγ antagonist GW9662 significantly abolished the anti-atherogenic effects of AT1R deficiency in ApoE^–/–/AT1R^–/– mice (plaque area as % of control: ApoE^–/–: 39 ±5%; ApoE^–/–/AT1R^–/–: 17 ±7%, p = 0.044 vs. ApoE^–/–; ApoE^–/–/AT1R^–/– + GW9662: 31 ±8%, p = 0.047 vs. ApoE^–/–/AT1R^–/–). Focusing on IL6 as a pro-inflammatory humoral marker we detected significantly increased IL-6 levels in GW9662-treated animals (IL-6 in pg/ml: ApoE^–/–: 230 ±16; ApoE^–/–/AT1R^–/–: 117 ±20, p = 0.01 vs. ApoE^–/–; ApoE^–/–/AT1R^–/– + GW9662: 199 ±20, p = 0.01 vs. ApoE^–/–/AT1R^–/–), while the anti-inflammatory marker IL-10 was significantly reduced after PPARγ inhibition in GW9662 animals (IL-10 in pg/ml: ApoE^–/–: 18 ±4; ApoE^–/–/AT1R^–/–: 55 ±12, p = 0.03 vs. ApoE^–/–; ApoE^–/–/AT1R^–/– + GW9662: 19 ±4, p = 0.03 vs. ApoE^–/–/AT1R^–/–). Metabolic parameters of glucose homeostasis (glucose and insulin tolerance test) were significantly deteriorated in ApoE^–/–/AT1R^–/– mice treated with GW9662 as compared to vehicle-treated ApoE^–/–/AT1R^–/– mice. Systolic blood pressure and plasma cholesterol levels were similar in all groups.

Conclusions

Genetic disruption of the AT1R attenuates atherosclerosis and improves endothelial function in an ApoE^–/– mouse model of hypercholesterolemia-induced atherosclerosis via PPARγ, indicating a significant role of PPARγ in reduced vascular inflammation, improvement of insulin sensitivity and atheroprotection of AT1R deficiency.     

Expression of urocortin in pancreatic ductal adenocarcinoma and pancreatic intraepithelial neoplasia

Urocortin (UCN) is a 40‐aminoacid neuropeptide that regulates angiogenesis and inhibits cell proliferation. Our aim was to examine the relationship of UCN expression to the clinicopathological parameters of pancreatic ductal adenocarcinoma (PDAC) and histological grade of pancreatic intraepithelial neoplasia (PanIN). Tissue microarray was used to analyze UCN protein expression in 89 surgical specimens including 21 PanIN, 3 PDAC arising from PanIN, and 65 PDAC without PanIN. UCN immunoscores ranging from 0 to 12 were obtained by multiplying intensity (scored on a 3‐point scale) by the percentage of stained cells (scored on a 4‐point scale). Strong expression of UCN was detected in 5 specimens of non‐neoplastic pancreatic ductal epithelia. UCN immunoscore was significantly higher in PanIN‐1 than in PanIN‐2 and PanIN‐3 (p = 0.038) and significantly higher in well‐differentiated PDAC or early American Joint Committee on Cancer (AJCC) stage PDAC than in poorly differentiated or advanced stage PDAC (p = 0.025, p = 0.018). Higher expression of UCN correlates with PDAC tumor grade and AJCC pathologic stage as well as PanIN grade. Immunohistochemical assessment of UCN may help clinicians predict tumor recurrence rate and help pathologists make a proper diagnosis.     

Cardiovascular effects of the intracerebroventricular injection of adrenomedullin: roles of the peripheral vasopressin and central cholinergic systems

Our objective was to investigate in conscious Sprague-Dawley (6-8 weeks, 250-300 g) female rats (N = 7 in each group) the effects of intracerebroventricularly (icv) injected adrenomedullin (ADM) on blood pressure and heart rate (HR), and to determine if ADM and calcitonin gene-related peptide (CGRP) receptors, peripheral V₁ receptors or the central cholinergic system play roles in these cardiovascular effects. Blood pressure and HR were observed before and for 30 min following drug injections. The following results were obtained: 1) icv ADM (750 ng/10 µL) caused an increase in both blood pressure and HR (ΔMAP = 11.8 ± 2.3 mmHg and ΔHR = 39.7 ± 4.8 bpm). 2) Pretreatment with a CGRP receptor antagonist (CGRP_8-37) and ADM receptor antagonist (ADM_22-52) blocked the effect of central ADM on blood pressure and HR. 3) The nicotinic receptor antagonist mecamylamine (25 µg/10 µL, icv) and the muscarinic receptor antagonist atropine (5 µg/10 µL, icv) prevented the stimulating effect of ADM on blood pressure. The effect of ADM on HR was blocked only by atropine (5 µg/10 µL, icv). 4) The V₁ receptor antagonist [β-mercapto-β-β-cyclopentamethylenepropionyl¹, O-me-Tyr²,Arg⁸]-vasopressin (V2255; 10 µg/kg), that was applied intravenously, prevented the effect of ADM on blood pressure and HR. This is the first study reporting the role of specific ADM and CGRP receptors, especially the role of nicotinic and muscarinic central cholinergic receptors and the role of peripheral V₁ receptors in the increasing effects of icv ADM on blood pressure and HR.     

Comparative Phenotypic Studies of Duct Epithelial Cell Lines Derived from Normal Human Pancreas and Pancreatic Carcinoma

We have investigated the mRNA/protein expression of several tyrosine kinase receptors, growth factors, and p16^INK4A cyclin inhibitor in cell lines derived from normal human pancreatic duct epithelium (HPDE) and compared them with those of five pancreatic ductal carcinoma cell lines. Cultured HPDE cells express low levels of epidermal growth factor receptor (EGFR), erbB2, transforming growth factor (TGF)-α, Met/hepatocyte growth factor receptor (HGFR), vascular endothelial growth factor (VEGF), and keratinocyte growth factor (KGF). They also expressed high levels of amphiregulin but did not express EGF and cripto. The expression levels were similar in primary normal HPDE cells and those expressing transfected E6E7 genes of human papilloma virus-16, but their immortalization appeared to enhance the expression of EGFR and Met/HGFR. In comparison, pancreatic carcinoma cell lines commonly demonstrated overexpression of EGFR, erbB2, TGF-α, Met/HGFR, VEGF, and KGF, but they consistently showed marked down-regulation of amphiregulin mRNA expression. In contrast to all carcinoma cell lines that showed deletions of the p16 gene, HPDE cells consistently demonstrated normal p16 genotype and its mRNA expression. This is the first report that compares the phenotypic expression of cultured pancreatic ductal carcinoma cells with epithelial cell lines derived from normal human pancreatic ducts. The findings confirm that malignant transformation of human pancreatic duct cells commonly results in a deregulation of expression of various growth factors and receptors.     

On the Etiology of Type 1 Diabetes: A New Animal Model Signifying a Decisive Role for Bacteria Eliciting an Adverse Innate Immunity Response

The cause of type 1 diabetes (T1D) remains unknown; however, a decisive role for environmental factors is recognized. The increased incidence of T1D during the last decades, as well as regional differences, is paralleled by differences in the intestinal bacterial flora. A new animal model was established to test the hypothesis that bacteria entering the pancreatic ductal system could trigger β-cell destruction and to provide new insights to the immunopathology of the disease. Obtained findings were compared with those present in two patients dying at onset of T1D. Different bacterial species, present in the human duodenum, instilled into the ductal system of the pancreas in healthy rats rapidly induced cellular infiltration, consisting of mainly neutrophil polymorphonuclear cells and monocytes/macrophages, centered around the pancreatic ducts. Also, the islets of Langerhans attracted polymorphonuclear cells, possibly via release of IL-6, IL-8, and monocyte chemotactic protein 1. Small bleedings or large dilatations of the capillaries were frequently found within the islets, and several β-cells had severe hydropic degeneration (ie, swollen cytoplasm) but with preserved nuclei. A novel rat model for the initial events in T1D is presented, revealing marked similarities with the morphologic findings obtained in patients dying at onset of T1D and signifying a decisive role for bacteria in eliciting an adverse innate immunity response. The present findings support the hypothesis that T1D is an organ-specific inflammatory disease.Our understanding of the etiology of type 1 diabetes (T1D) remains limited and originates to a large extent from two animal models: the nonobese diabetic mouse and the BioBreeding-diabetes prone rat.¹ In both models a progressive T-cell–mediated destruction of the β-cells occurs; however, the immunopathologic findings reveal limited similarities with the human disease.^2–5 In human pancreatic specimens, insulitis is discrete, affects only a few islets, and is heterogeneously distributed within the gland. In a recent meta-analysis, insulitis was reported in only 29% of patients with onset between 15 and 39 years of age and with a disease duration of <1 month.⁶ At the time of diagnosis, autoantibodies were only present in approximately 70% to 80% of affected patients.⁷ Likewise, attempts to prevent disease progression with immunosuppression^8–11 or immunointerventions^12–14 cause no or only transient preservation of β-cell function.The fact that the exocrine pancreas gets affected in patients with T1D is underappreciated, and several studies have found autoantibodies in the exocrine cells before the onset of T1D.^15–18 Mild to moderate exocrine pancreatic insufficiency is an early event in T1D,¹⁹ and a substantial reduction (32%) in pancreatic volume is already present 3 to 4 months after onset.²⁰ Also, in the classic report by Gepts,⁴ lesions of the acinar tissue were reported to occur frequently in patients with recent onset of T1D. The findings comprised mostly focal or diffuse lesions of acute pancreatitis with accumulation of leukocytes, often centered around the excretory canals.^2–5 In a more recent study of patients with long-term T1D, 40% had periductal fibrosis and 60% of cases had periductal fibrosis that extended to the interlobular pancreas.²¹ Collectively, these observations suggest that the injurious process that causes T1D affects both the exocrine and endocrine components of the pancreas and challenge the view that T1D is a β-cell–specific autoimmune disease.The low concordance rate for the development of T1D in identical twins and the current rapid increase in incidence of T1D argue against a decisive role for genetic factors. Notably, there is a close to sixfold gradient in the incidence of T1D between Russian and Finland Karelia, although the population is homogenous and the predisposing HLA genotypes are equally frequent.²² In addition, children born in Finland by immigrants from Somalia, a low incidence country for T1D, acquire the same risk for T1D as the native Finish population.²³ On the basis of these and similar observations, it is generally assumed that environmental factors may act as triggers of T1D. For decades different enteroviruses have been implicated in the pathogenesis of T1D²⁴; however, evidence of causality remains missing.Bacterial colonization of the infantile gut is influenced by environmental factors and has changed markedly in developed countries during the last decades.²⁵ Interestingly, the increased incidence of T1D²⁶ and the difference in incidence of T1D in Sweden, Italy, and Africa^26–28 are paralleled by reported frequencies of intestinal Staphylococcus aureus.^29–32 Bacteria entering the ductal system of the pancreas would be exposed to the pancreatic juice–containing substances, with marked antibacterial effects initiating release of bacterial components, such as lipopolysaccharide (LPS), lipoteichoic acid (LTA), and various toxins. Notably, these substances have been implicated in the etiology of neurogenerative diseases and neural cell death because they stimulate microglia to produce proinflammatory cytokines (IL-1b, IL-6, tumor necrosis factor-α), nitric oxide, and reactive oxygen species, causing significant cell death in neighboring neural cells.³³The present study was conducted to establish an animal model for the initial events in T1D to test the hypothesis that bacteria entering into the ductal system of the pancreas could elicit an adverse innate immunity response. Different bacterial species present transiently or continuously in the human duodenum were instilled into the ductal system of the pancreas in healthy rats. To examine the clinical relevance of the experimental model, obtained findings were compared with those present in the pancreases of two patients dying at onset of T1D.     

Familial pancreatic cancer: genetic advances

Beset by poor prognosis, pancreatic ductal adenocarcinoma is classified as familial or sporadic. This review elaborates on the known genetic syndromes that underlie familial pancreatic cancer, where there are opportunities for genetic counseling and testing as well as clinical monitoring of at-risk patients. Such subsets of familial pancreatic cancer involve germline cationic trypsinogen or PRSS1 mutations (hereditary pancreatitis), BRCA2 mutations (usually in association with hereditary breast–ovarian cancer syndrome), CDKN2 mutations (familial atypical mole and multiple melanoma), or DNA repair gene mutations (e.g., ATM and PALB2, apart from those in BRCA2). However, the vast majority of familial pancreatic cancer cases have yet to have their genetic underpinnings elucidated, waiting in part for the results of deep sequencing efforts.     

EGFR expression in pancreatic intraepithelial neoplasia and ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) is an aggressive malignant tumor with poor prognosis. Epidermal growth factor receptor (EGFR) is an important cell adhesion and signaling pathway mediator. The aim of this study was to evaluate the expression of EGFR in both pancreatic intraepithelial neoplasia (PanIN) and PDA and their relationship to clinicopathologic characteristics. Formalin-fixed, paraffin-embedded tissues including 81 cases with pancreatic ductal adenocarcinoma, 27 with normal pancreas, 16 with PanIN-1A, 18 with PanIN-1B, 11 with PanIN-2, and 24 with PanIN-3 were used for construction of tissue microarrays. Imunohistochemistry for EGFR was performed. Normal pancreatic ducts, PanIN-1A, and PanIN-1B did not show EGFR overexpression. EGFR overexpression was observed in 18.2% (2/9) of PanIN-2, 41.7% (10/14) of PanIN-3, and 64.2% (52/81) of PDA, respectively. Significantly higher EGFR overexpression was observed in PDAs than in PanIN lesions (P<0.05). No statistically significant correlation was observed between EGFR overexpression and patient age, sex, tumor location, size, histological grade, vascular invasion, lymph node metastasis and stage at presentation, respectively. In conclusion, EGFR expression increased from PanIN to PDA. EGFR may be involved in early stage in development of PDA.