Exocrine Pancreatic Acinar Cells Research Articles

Tumor Protein D52 Regulates Paligenosis in Exocrine Pancreatic Acinar Cells

Background: Paligenosis is a conserved cellular plasticity program in which fully differentiated cells reenter the cell cycle in order to regenerate lost tissue during injury. This process is utilized by cells that have a slow turnover rate and lack dedicated stem cells, as is the case with exocrine pancreatic acinar cells. Acinar cells, which synthesize and secrete digestive enzymes necessary for macronutrient digestion, undergo paligenosis in response to damage induced by the inflammatory disease pancreatitis. During paligenosis, acinar cells first downscale their secretory apparatus by upregulating autophagy, and then take on a mucinous-ductal-progenitor-like identity in a process called acinar to ductal metaplasia (ADM) prior to proliferation. This phenomenon can be recapitulated in rodent models in vivo utilizing repeated episodes of cerulein-induced pancreatitis or in 18-hour suspension culture during which primary isolated acinar cells dedifferentiate to a progenitor-like state. We have previously reported that markers of the endolysosomal secretory pathway in acinar cells are rapidly lost during models of experimental pancreatitis and suspension culture. Tumor Protein D52, which regulates endolysosomal traffcking and secretion in acinar cells, undergoes lysosomal degradation at the onset of experimental pancreatitis; furthermore, restoring D52 expression by adenovirus in isolated acinar cells maintains secretion during experimental pancreatitis as well as maintains acinar differentiation in suspension culture. Hypothesis: Degradation of D52, and loss of the endolysosomal secretory pathway, are pivotal events during the initial stages of paligenosis. Methods: To study the role of D52 and the regulation of paligenosis, we generated tamoxifen-inducible, acinar specific D52 knockout mice (D52KOac), and markers of paligenosis (ADM, proliferation) were assessed by immunoblot, qPCR, and immunostaining. Mice were given tamoxifen at 2-3 months of age to ensure normal pancreatic development, and tissues were harvested 21 days after tamoxifen. Results: Compared to controls, D52KOac exhibited 2.5-fold upregulation of the ductal markers Sox9 and CK19, 50% reduction of Ptf1α, and a 5-fold increase in β-catenin; these markers signify the presence of ADM and cells with progenitor-like characteristics. Cell cycle regulation and proliferation were also observed in D52KOac by a nearly 3-fold increase in cyclin D and increased Ki67+ nuclei. Conclusions: These data support that loss of D52 in pancreatic acinar cells induces spontaneous paligenosis in the absence of cellular injury and inflammation. These findings point to a previously unrecognized role for D52 in the regulation of acinar cell differentiation and plasticity. Given that paligenosis is a key pathway involved in the development of pancreatic neoplasms and adenocarcinoma, studying D52-regulated paligenosis will reveal additional insights into this critical protective mechanism. American Pancreatic Association Foundation Young Investigator Award. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Structural and immunohistochemical characterization of pancreas of Molly fish (Poecilia sphenops), with a special reference to its immune role.

Recently, teleost species have been considered important model systems for investigating different research areas including immunologic one. The available literature provides poor data about the localization and the structure of pancreas in Molly fish. Moreover, little attention has been paid to the immunologic role of pancreatic tissue of teleost, particularly Molly fish; therefore, this study aimed to highlights the description of pancreatic tissue in Molly fish using light- and electron- microscopy, focusing on the role of pancreatic immune cells and pancreatic acinar cells in immune responses. Microscopic analysis revealed that the pancreas of Molly fish was composed of intrahepatic, disseminated and compact parts. Exocrine pancreatic tissue was diffusely extended within the hepatic tissue forming hepatopancreas. The disseminated pancreas appeared as several irregular nodules of pancreatic tissue localized within the mesenteric adipose tissue. The compact pancreas appeared as an oval shaped body embedded within the mesenteric adipose tissue between the spleen and the intestinal loops. Several telocytes and melanomacrophages were detected within the disseminated pancreatic nodules. Moreover, dendritic cells were found in a close association to the exocrine pancreatic acini. The pancreatic acinar cells showed strong immunoreactivity to APG5, TGF-β, IL-1β, NF-κB, Nrf2, and SOX9 in both hepatopancreas and disseminated pancreas of Molly fish. S100 protein revealed a strong expression in the exocrine pancreatic acinar cells of disseminated pancreas and also in the endocrine cells of the compact pancreas. In conclusion, findings of this study suggest the potential role of the pancreas of the Molly fish in cell proliferation and differentiation, proinflammatory cytokines stimulation, and regulation of both innate and adaptive immunity. RESEARCH HIGHLIGHTS: Telocytes and melanomacrophages were detected in the disseminated pancreatic nodules of the Molly fish. In Molly fish, dendritic cells were found in a close association to the exocrine pancreatic acini. Strong immunoreactivity of the pancreatic acinar cells of the Molly fish to APG5, TGF-β, IL-1β, NF-κB, Nrf2, SOX9, and S100.

Trypsin Activity in Secretagogue-induced Murine Pancreatitis Is Solely Elicited by Cathepsin B and Does Not Mediate Key Pathologic Responses

See editorial on page 524. Genetically Engineered Mouse Models Shine New Light on Decades-old Story of Trypsin in PancreatitisGastroenterologyVol. 164Issue 4PreviewThe idea that pancreatitis—a common, painful, and life-threatening disease1,2—is caused by the pancreas digesting itself is about 130 years old,3 and the foremost villain in this process is believed to be trypsin, a serine protease discovered even earlier. The problem is that exocrine pancreatic (acinar) cells synthesize not trypsin per se, but trypsinogen, its inactive precursor (zymogen). In normal physiology, trypsinogen is converted to trypsin (activated) only in the duodenum after being secreted in response to a meal. Full-Text PDF

Loss of CAPS2/Cadps2 leads to exocrine pancreatic cell injury and intracellular accumulation of secretory granules in mice.

The type 2 Ca2+-dependent activator protein for secretion (CAPS2/CADPS2) regulates dense-core vesicle trafficking and exocytosis and is involved in the regulated release of catecholamines, peptidergic hormones, and neuromodulators. CAPS2 is expressed in the pancreatic exocrine acinar cells that produce and secrete digestive enzymes. However, the functional role of CAPS2 in vesicular trafficking and/or exocytosis of non-regulatory proteins in the exocrine pancreas remains to be determined. Here, we analyzed the morpho-pathological indicators of the pancreatic exocrine pathway in Cadps2-deficient mouse models using histochemistry, biochemistry, and electron microscopy. We used whole exosome sequencing to identify CADPS2 variants in patients with chronic pancreatitis (CP). Caps2/Cadps2-knockout (KO) mice exhibited morphophysiological abnormalities in the exocrine pancreas, including excessive accumulation of secretory granules (zymogen granules) and their amylase content in the cytoplasm, deterioration of the fine intracellular membrane structures (disorganized rough endoplasmic reticulum, dilated Golgi cisternae, and the appearance of empty vesicles and autophagic-like vacuoles), as well as exocrine pancreatic cell injury, including acinar cell atrophy, increased fibrosis, and inflammatory cell infiltration. Pancreas-specific Cadps2 conditional KO mice exhibited pathological abnormalities in the exocrine pancreas similar to the global Cadps2 KO mice, indicating that these phenotypes were caused either directly or indirectly by CAPS2 deficiency in the pancreas. Furthermore, we identified a rare variant in the exon3 coding region of CADPS2 in a non-alcoholic patient with CP and showed that Cadps2-dex3 mice lacking CAPS2 exon3 exhibited symptoms similar to those exhibited by the Cadps2 KO and cKO mice. These results suggest that CAPS2 is critical for the proper functioning of the pancreatic exocrine pathway, and its deficiency is associated with a risk of pancreatic acinar cell pathology.

MFG-E8 Maintains Cellular Homeostasis by Suppressing Endoplasmic Reticulum Stress in Pancreatic Exocrine Acinar Cells.

Excessive endoplasmic reticulum (ER) stress contributes significantly to the pathogenesis of exocrine acinar damage in acute pancreatitis. Our previous study found that milk fat globule EGF factor 8 (MFG-E8), a lipophilic glycoprotein, alleviates acinar cell damage during AP via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining cellular homeostasis. However, MFG-E8’s role in ER stress in pancreatic exocrine acinar cells has not been evaluated. To study this, thapsigargin, brefeldin A, tunicamycin and cerulein + LPS were used to induce ER stress in rat pancreatic acinar cells in vitro. L-arginine- and cerulein + LPS-induced acute pancreatitis in mice were used to study ER stress in vivo. The results showed that MFG-E8 dose-dependently inhibited ER stress under both in vitro and in vivo conditions. MFG-E8 knockout mice suffered more severe ER stress and greater inflammatory response after L-arginine administration. Mechanistically, MFG-E8 increased phosphorylation of FAK and STAT3 in cerulein + LPS-treated pancreatic acinar cells. The presence of specific inhibitors of αvβ3/5 integrin, FAK or STAT3 abolished MFG-E8’s effect on cerulein + LPS-induced ER stress in pancreatic acinar cells. In conclusion, MFG-E8 maintains cellular homeostasis by alleviating ER stress in pancreatic exocrine acinar cells.

Development and Application of a Semi quantitative Scoring Method for Ultrastructural Assessment of Acute Stress in Pancreatic Islets.

Background.Pancreas and islet transplantation outcomes are negatively impacted by injury to the endocrine cells from acute stress during donor death, organ procurement, processing, and transplant procedures. Here, we report a novel electron microscopy scoring system, the Newcastle Pancreas Endocrine Stress Score (NPESS).Methods.NPESS was adapted and expanded from our previously validated method for scoring pancreatic exocrine acinar cells, yielding a 4-point scale (0–3) classifying ultrastructural pathology in endocrine cell nuclei, mitochondria, endoplasmic reticulum, cytoplasmic vacuolization, and secretory granule depletion, with a maximum additive score of 15. We applied NPESS in a cohort of deceased organ donors after brainstem (DBD) and circulatory (DCD) death with a wide range of cold ischemic times (3.6–35.9 h) including 3 donors with type 1 and 3 with type 2 diabetes to assess islets in situ (n = 30) in addition to pancreata (n = 3) pre- and postislet isolation.Results.In DBD pancreata, NPESS correlated with cold ischemic time (head: r = 0.55; P = 0.02) and mirrored exocrine score (r = 0.48; P = 0.01). When stratified by endocrine phenotype, cells with granules of heterogeneous morphology had higher scores than α, β, and δ cells (P < 0.0001). Cells of mixed endocrine-exocrine morphology were observed in association with increased NPESS (P = 0.02). Islet isolation was associated with improved NPESS (in situ: 8.39 ± 0.77 [Mean ± SD]; postisolation: 5.44 ± 0.31; P = 0.04).Conclusions.NPESS provides a robust method for semiquantitative scoring of subcellular ultrastructural changes in human pancreatic endocrine cells in situ and following islet isolation with utility for unbiased evaluation of acute stress in organ transplantation research.

Endocrine and exocrine pancreas pathologies crosstalk: Insulin regulates the unfolded protein response in pancreatic exocrine acinar cells in pancreatitis

Endocrine and exocrine pancreas pathologies crosstalk: Insulin regulates the unfolded protein response in pancreatic exocrine acinar cells in pancreatitis

Laser-assisted 3D bioprinting of exocrine pancreas spheroid models for cancer initiation study

Pancreatic ductal adenocarcinoma (PDAC) is the most common malignancy of the pancreas. It has shown a poor prognosis and a rising incidence in the developed world. Other pathologies associated with this tissue include pancreatitis, a risk condition for pancreatic cancer. The onset of both pancreatitis and pancreatic cancer follows a common pattern: exocrine pancreatic acinar cells undergo a transdifferentiation to duct cells that triggers a 3D restructuration of the pancreatic tissue. However, the exact mechanism underlying this process remains partially undefined. Further understanding the cellular events leading to PDAC could open new avenues in the development of novel therapeutic approaches. Since current 2D cell culture models fail to mimic the tridimensional complexity of the pancreatic tissue, new in vitro models are urgently needed. Here, we generated 3D pancreatic cell spheroid arrays using laser-assisted bioprinting and characterized their phenotypic evolution over time through image analysis and phenotypic characterization. We show that these bioprinted spheroids, composed of both acinar and ductal cells, can replicate the initial stages of PDAC development. This bioprinted miniaturized spheroid-based array model should prove useful for the study of the internal and external factors that contribute to the formation of precursor PDAC lesions and to cancer progression, and may therefore shed light on future PDAC therapy strategies.

Glucagon-like peptide-1 (GLP1) and the gastrointestinal tract. GLP1 receptor agonists: overemphasized gastric, forgotten intestinal ("ileal brake") effect?

Glucagon-like peptide-1 (GLP1) and their receptor agonists - beside their blood glucose lowering and central effects- affect also the gastrointestinal function in many respects. They slow down the stomach emptying, the motility of the small bowel and colon - this is the explanation for the "ileal brake" terminology -, stimulate the function of exocrine pancreatic acinar cells and increase amylase production. GLP1 receptor agonists belong to the defining tools of the blood glucose lowering therapy in type 2 diabetes. Their long- and short-acting derivatives have different influence on the fasting and the postprandial blood glucose, respectively. By introducing the term non-prandial and prandial type analogues - which seems to be forced in light of the newer data - the potential slowdown in gastric emptying is the center of interest, lately, however, especially in the case of long-acting GLP1 variants, at least such attention should be paid to controlling bowel function. The article reviews the physiological effects of GLP1 on the gastrointestinal tract and draws attention to the potential for the prevention of possible side effects through detailed patient information and dietary advises. Orv Hetil. 2019; 160(49): 1927-1934.

Slc26a6 is an apical membrane anion exchanger that drives HCO3--dependent fluid secretion in murine pancreatic acinar cells.

The nonselective anion exchanger Slc26a6, also known as putative anion transporter 1 and chloride/formate exchanger, is thought to play a major role in transport in exocrine glands. In this study, Slc26a6 null mice were used to explore the function of Slc26a6 in the exocrine pancreas. Slc26a6 primarily localized to the apical membrane of pancreatic exocrine acinar cells. The volume of stimulated juice secretion by the ex vivo pancreas was significantly reduced ~35% in Slc26a6-/- mice, but no changes occurred in the gross structure or gland weights of Slc26a6 null mice. The secretion of pancreatic juice by Slc26a6+/+ mice was dependent on while, in contrast, fluid secretion by Slc26a6-/- mice was independent of , suggesting that Slc26a6 mediates the -dependent component of fluid secretion. Consistent with these observations, disruption of Slc26a6 also significantly reduced secretion by the pancreas ~35%. Taken together, these results demonstrate that the apical Slc26a6 anion exchanger in acinar cells is involved in -dependent fluid secretion but that another major -independent pathway is the primary driver of the fluid secretion process in the mouse pancreas.

Pancreatic exocrine acinar cells are stress-sensitive to high levels of glucose and insulin

Pancreatic exocrine acinar cells are stress-sensitive to high levels of glucose and insulin

Adult human pancreatic acinar cells dedifferentiate into an embryonic progenitor-like state in 3D suspension culture

Human pancreatic exocrine cells were cultured in 3D suspension and formed pancreatospheres composed of acinar-derived and duct-like cells. We investigated, up to 6 days, the fate of human pancreatic acinar cells using fluorescein-conjugated Ulex Europaeus Agglutinin 1 lectin, a previously published acinar-specific non-genetic lineage tracing strategy. At day 4, fluorescence-activated cell sort for the intracellularly incorporated FITC-conjugated UEA1 lectin and the duct-specific CA19.9 surface marker, distinguished acinar-derived cells (UEA1+CA19.9−) from duct-like cells (UEA1−CA19.9+) and acinar-to-duct-like transdifferentiated cells (UEA1+CA19.9+). mRNA expression analysis of the acinar-derived (UEA1+CA19.9−) and duct-like (UEA1-CA19.9+) cell fractions with concomitant immunocytochemical analysis of the pancreatospheres revealed acquisition of an embryonic signature in the UEA1+CA19.9− acinar-derived cells characterized by de novo expression of SOX9 and CD142, robust expression of PDX1 and surface expression of GP2. The colocalisation of CD142, a multipotent pancreatic progenitor surface marker, PDX1, SOX9 and GP2 is reminiscent of a cellular state present during human embryonic development. Addition of TGF-beta signalling inhibitor Alk5iII, induced a 28-fold increased KI67-labeling in pancreatospheres, more pronounced in the CD142+GP2+ acinar-derived cells. These findings with human cells underscore the remarkable plasticity of pancreatic exocrine acinar cells, previously described in rodents, and could find applications in the field of regenerative medicine.

Endocrine and exocrine pancreas pathologies crosstalk: Insulin regulates the unfolded protein response in pancreatic exocrine acinar cells

Exocrine pancreas insufficiency is common in diabetic mellitus (DM) patients. Cellular stress is a prerequisite in the development of pancreatic pathologies such as acute pancreatitis (AP). The molecular mechanisms underlying exocrine pancreatic ER-stress in DM are largely unknown. We studied the effects of insulin and glucose (related to DM) alone and in combination with cerulein (CER)-induced stress (mimicking AP) on ER-stress unfolded protein response (UPR) in pancreatic acinar cells.Exocrine pancreas cells (AR42J) were exposed to high glucose (Glu, 25 mM) and insulin (Ins, 100 nM) levels with or without CER (10 nM). ER-stress UPR activation was analyzed at the transcript, protein, immunocytochemistry, western blotting, quantitative RT-PCR and XBP1 splicing, including; XBP1, sXBP1, ATF6, cleaved ATF6, IRE1-p, CHOP, Caspase-12 and Bax.Exocrine acinar cells exposed to high Ins or Ins+Glu concentrations (but not Glu alone) exhibited ER-stress UPR, demonstrated by significant increase of transcript and protein levels of downstream markers in the ATF6 and IRE1 transduction arms, including: sXBP1, cleaved ATF6, XBP1, CHOP, IRE1-p and caspase-12. UPR activation resulted in IRE1-p aggregation and nuclear trans-localization of cleaved activated ATF6 and sXBP1. Ins further aggravated UPR when cells were co-challenged with CER-induced stress, exacerbating the effects of CER alone.High Ins levels, typical to type-2-DM, activate the ER-stress UPR in pancreatic acinar cells, through the ATF6 and IRE1 pathways. This effect of Ins in naïve acinar cells further augments CER-induced UPR. Our data highlight molecular pathways through which DM enhances exocrine pancreas pathologies.

C-Src regulates cargo transit via the Golgi in pancreatic acinar cells

The exocrine pancreatic acinar cell is unique for its rapid protein synthesis and packaging in zymogen granules (ZGs). However, while crucial to the pathogenesis of pancreatitis, the signaling involved in the transit of proteins via the Golgi is poorly understood in these cells. Noting the evidence of c-Src in regulating transit of cargo via the Golgi in other systems, we explored this in acinar cells. Stimulation of ZG formation with dexamethasone activated Src and increased the Golgi area in acinar cells. c-Src localized to the microsomes of acinar cells on immunofluorescence and subcellular fractionation. While other Src family members had no effect on the Golgi markers P115 and GM130, active c-Src increased the Golgi area these stained, extending them into the ER. Src inhibition reduced amylase staining outside the Golgi and increased it in a stack like Golgi morphology. In vivo pharmacologic inhibition or acinar specific genetic deletion of c-Src reduced ZG number and staining of amylase in ZGs along with increasing amylase retention in the microsomal fraction. Morphologically this was associated with smaller Golgi stacks, and dilation of the endoplasmic reticulum. Therefore the role c-Src regulated Golgi function, ZG formation and microsomal zymogen transit in acinar cells needs to be explored in pancreatitis.

Sericin improves heart and liver mitochondrial architecture in hypercholesterolaemic rats and maintains pancreatic and adrenal cell biosynthesis

Hypercholesterolaemia is well known to be associated with mitochondrial dysfunction, subsequently leading to multiple organ failure. Similar to other natural products, sericin is a candidate for adjunctive therapy in hyperlipidaemic conditions. However, the cholesterol-lowering mechanisms of sericin are multifactorial and controversial. Here, a high-cholesterol-fed rat model with or without sericin treatment was established using a dosage of 1000mg/kg/day for 30 days. Blood lipid profiles, oxidative stress markers (superoxide dismutase, SOD; malondialdehyde, MDA; nuclear factor erythroid 2-related factor, Nrf-2), dysmorphic mitochondria in relation to fission (dynamin-related protein-1; Drp-1) and fusion (guanosine triphosphatase mutated in dominant optic atrophy; OPA-1) markers and biosynthetic markers (aquaporin, AQP-1; tubulin-4β, Tb4B) in the pancreas and adrenal gland were evaluated. The results showed that sericin reduced blood cholesterol and increased high-density lipoprotein (HDL) by acting against oxidative stress. Hypocholesterolaemic and antioxidant conditions further preserved heart and liver mitochondrial architecture; however, this protection was not exhibited in the kidney, where a high level of renal mitophagy, indicating by LC-3 up-regulation, was presented. The steps of ultrastructural alteration of mitochondria from degenerative changes to necrosis were also demonstrated. Sericin also conserved AQP-1 and Tb4B levels in the exocrine pancreatic acinar cells and zona glomerulosa cells, which were positively correlated with serum lipase, HDL, antioxidative markers and mitochondrial integrity. The present study revealed that sericin not only has antioxidant capacity but also balances pancreatic and adrenal cell biosynthesis, especially lipase activity, which may have played an important role in improving lipid dysregulation in the hypercholesterolaemic rat model, leading to the reduction of dysmorphic mitochondria, particularly in the heart and liver.

Comparative studies on histology and histochemistry of pancreas between Labeo calbasu (Hamilton, 1822) and Mystus gulio (Hamilton, 1822)

The cellular architecture and histochemical nature of the enzyme secretory acinar cells of pancreas have been investigated in two species of fish, Labeo calbasu and Mystus gulio having different feeding habits. Histological analysis illustrates that the exocrine pancreatic tissues are scattered within the hepatic parenchyma as hepatopancreas and spleen as spleenpancreas in L. calbasu . The structural analysis also shows that exocrine as well as endocrine pancreatic tissues are also diffused in the adipose tissues in between the intestinal coiling of L. calbasu . In M. gulio the discrete pancreatic tissue is attached to the outer wall of the stomach and formed cluster of acini interspersed with small areas of islet of Langerhans and blood vessels. The exocrine pancreatic acinar cells are provided with conspicuous nuclei and densely packed acidophilic zymogen granules. The endocrine component of pancreas, islet of Langerhans is encircled by a thin connective tissue and comprised of α, β and δ cells. Different cell types in the islets are differentiated based mainly upon their shape, position, staining intensity and density of the cytoplasmic secretory granules. α cells contain sparse cytoplasm and densely stained nuclei, are generally located to the periphery of the islet Aldehyde fuchsin positive β cells bear spherical nucleus and granular cytoplasm, are in the center of islet of Langerhans contacted with blood vessels. δ cells are few in number with light stained nuclei disperse in the pancreatic islet. Histochemical detection displays that the zymogen granules of exocrine acinar cells showing variegated intensities of tryptophan reaction, the precursor of numerous pancreatic enzymes which probably related to the food and feeding habits of the fishes concerned. The zymogen granules are larger in size and heavily deposited in the acinar cells of hepatopancreas of L. calbasu in comparison to M. gulio may be correlated with the herbivorous feeding habit in respect to secretion of digestive enzymes.

Development of extrahepatic bile duct excluding gall bladder in human fetuses: histological, histochemical, and immunohistochemical analysis.

The fetal development of extrahepatic bile ducts (EBD) is unkown. Development of EBD was examined by immunohistochemistry in 16 fetuses of 7-40 gestational week (GW). Gall bladder (GB) was not investigated. At seven GW, a hepato-pancreatic bud (HPB) was seen near the hepatic hilus. At eight GW, embryonic EBD, GB and pacreas developed from HPB. Portal veins (PV) and hepatic arteries (HAs) were present in EBD at eight GW. Liver parenchyma was already present in seven GW. At eight GW, EBD at porta hepatis (PH) was already established; PH EBD was derived from ductal plate (DP). The distal and middle EBD gradually develeped and took shape of EBD at nine GW. In PH, cystic and hepatic ducts developed from DP at eight GW. EBD developed further, accompanying many nerve fibers (NF) at PH and distal and middle EBD. Apparent PV and HA were seen around 12 GW. Around 20 GW, HA and capillaries proliferated, giving rise to peribiliary capillary plexus (PCP) in all parts of EBD. EBD grew gradually further, and around 30 GW extrahepatic peribiliary glands (EPG) emerged from EBD but not from cystic duct. Around 36 GW, exocrine pancreatic acinar cells emerged from remodeled DP at PH. At term (40 GW), EBD was established but was as yet immature. Numerous NF were present around EBD. Histochemically, EBD epithelium had no mucins at 7-12 GW but contained neutral and acidic mucins at 23-40 GW. EPG had abundant neutral and acidic mucins. Immunohistochemically, alpha-fetoprotein (AFP) was consistently positive in the epithelial and mesenychyma. The NF and muscles of HPB present at seven GW were positive for neural cell adhesion molecule (NCAM), neuron-specific enolase (NSE), platelet-derived growth factor receptor-α (PDGFRA), and KIT, but they disappeared in nine GW. Expressions of cytokeratin (CK) seven and CK19 in EBD and EPG were slight or none, while expression of CK8 was moderate, and that of CK18 was strong. NF were positive for NCAM, NSE, synaptophysin, and chromogranin, and PDGFRA. MUC1 and MUC6 apomucins were noted in EBD and EPG. EPG contained numerous endocrine cells positive for chromogranin, synaptophysin, NCAM and NSE. A few endocrine cells positive for these antigens were seen in EBD. Numeous KIT-positive stem cells (SC) were seen in PH, EBD, PV, HA, PCP, and EPG. NCAM-positive and bcl-2-positive SC were also located in these structures. Epithelial cells of EBD and EPG showed expressions of MET, PDGFRA, CA19-9, MUC1, MUC2, MUC6, KIT, bcl-2, and ErbB2. No expressions of HepPar1, carcinoembryonic antigen (CEA), and epithelial membrane antigen (EMA) were noted. Although the findings have limitatios because this study of humans are descriptive one, the present data suggest that the processes of the development and differentiation of EBD system may be associated with EBD SC, CK prolifes, SFC/KIT signaling, HGF/MET signaling, PDGRa/PDGFRA signaling, fibroblast growth factor/ErbB2 signaling, neuroendocrine lineage, NF differentiation, pancreatic aninar cell differentiation, PCP differentiation, MUC apomucins differentiation, and expressions of AFP and CA19-9. HepPar1, EMA and CEA were not involved in them.

Expression of claudin-4 molecule in canine exocrine pancreatic acinar cell carcinomas.

Claudins, integral membrane proteins are components of the tight junction structures between epithelial and endothelial cells. These transmembrane proteins create a primary barrier to prevent paracellular transport of solutes, and also restrict the lateral diffusion of membrane lipids and proteins to maintain the cellular polarity. The aim of the present study was to characterise the expression pattern of claudin-4 tight junction molecule in canine normal pancreatic tissues and in the well-differentiated and poorly-differentiated pancreatic acinar cell carcinomas in canines. The necropsy samples included canine intact pancreatic tissues, and canine well-differentiated and poorly-differentiated pancreatic acinar cell carcinomas samples. Claudin-4 was detected as an intense lateral membrane labelling of acinar cells in all intact pancreatic tissues. The intact epithelial cells of the different ducts were negative for the claudin-4 molecule. All primary and secondary canine well-differentiated exocrine pancreatic acinar cell carcinoma tissues showed intense apical lateral positivity for the claudin-4 molecule. All primary and secondary poorly-differentiated pancreatic acinar cell carcinoma tissues showed diffusely the loss of claudin-4 expression. Consequently, we hypothesize that the loss of expression of claudin-4 plays a role in the progression of canine pancreatic acinar cell carcinoma and may lead to cellular detachment, disorientation and invasion of these pancreatic cancers. Furthermore, claudin-4 can be used as an immunohistochemical marker to distinguish canine well-differentiated and undifferentiated exocrine pancreatic acinar cell carcinomas.

The Distribution of Phosphatidylinositol 4,5-Bisphosphate in Acinar Cells of Rat Pancreas Revealed with the Freeze-Fracture Replica Labeling Method

Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a phospholipid that has been implicated in multiple cellular activities. The distribution of PI(4,5)P2 has been analyzed extensively using live imaging of the GFP-coupled phospholipase C-δ1 pleckstrin homology domain in cultured cell lines. However, technical difficulties have prevented the study of PI(4,5)P2 in cells of in vivo tissues. We recently developed a method to analyze the nanoscale distribution of PI(4,5)P2 in cultured cells by using the quick-freezing and freeze-fracture replica labeling method. In principle, this method can be applied to any cell because it does not require the expression of artificial probes. In the present study, we modified the method to study cells of in vivo tissues and applied it to pancreatic exocrine acinar cells of the rat. We found that PI(4,5)P2 in the plasma membrane is distributed in an equivalent density in the apical and basolateral domains, but exists in a significantly higher concentration in the gap junction. The intracellular organelles did not show labeling for PI(4,5)P2. The results are novel or different from the reported distribution patterns in cell lines and highlight the importance of studying cells differentiated in vivo.

Lineage Tracing Evidence for Transdifferentiation of Acinar to Duct Cells and Plasticity of Human Pancreas

Animal studies have indicated that pancreatic exocrine acinar cells have phenotypic plasticity. In rodents, acinar cells can differentiate into ductal precursors that can be converted to pancreatic ductal adenocarcinoma or insulin-producing endocrine cells. However, little is known about human acinar cell plasticity. We developed nongenetic and genetic lineage tracing methods to study the fate of human acinar cells in culture. Human exocrine tissue was obtained from organ donors, dissociated, and cultured. Cell proliferation and survival were measured, and cell phenotypes were analyzed by immunocytochemistry. Nongenetic tracing methods were developed based on selective binding and uptake by acinar cells of a labeled lectin (Ulex europaeus agglutinin 1). Genetic tracing methods were developed based on adenoviral introduction of a Cre-lox reporter system, controlled by the amylase promoter. Both tracing methods showed that human acinar cells can transdifferentiate into cells that express specific ductal markers, such as cytokeratin 19, hepatocyte nuclear factor 1β, SOX9, CD133, carbonic anhydrase II, and cystic fibrosis transmembrane conductance regulator. Within 1 week of culture, all surviving acinar cells had acquired a ductal phenotype. This transdifferentiation was decreased by inhibiting mitogen-activated protein kinase signaling. Human acinar cells have plasticity similar to that described in rodent cells. These results might be used to develop therapeutic strategies for patients with diabetes or pancreatic cancer.