Pancreatic Exocrine Cells Research Articles

Transdifferentiation of pancreatic cells: therapeutic implications for pancreatic diseases

The pancreas is a unique organ, integrating both exocrine and endocrine functions, playing critical roles in the secretion of digestive enzymes and the production of glucose-regulating hormones. An intriguing phenomenon exists where dynamic intercellular transdifferentiation occurs within the pancreas, particularly pronounced in pancreatic diseases. In diabetic patients, the transdifferentiation of pancreatic islet cells may potentially compensate for impaired pancreatic function. Conversely, abnormal transdifferentiation of exocrine cells may promote the progression of pancreatic cancer. These highlight the plasticity of pancreatic cells in adapting to changes in their microenvironment by regulating their own functions to cope with external pressures. This review summarizes recent researches into the transdifferentiation processes and mechanisms within pancreatic exocrine and endocrine cells, as well as between pancreatic and non-pancreatic cells, providing a new perspective for clinical interventions. The aim of this review is to offer novel insights and propose potential therapeutic strategies to address pancreatic-related diseases, contributing to the advancement of medical research in this field.

Circulating pancreatic enzyme levels are a causal biomarker of type 1 diabetes.

Novel biomarkers of type 1 diabetes (T1D) are needed for earlier detection of disease and identifying therapeutic targets. We identified biomarkers of T1D by combining plasma cis and trans protein QTLs (pQTLs) for 2,922 proteins in the UK Biobank with a T1D genome-wide association study (GWAS) in 157k samples. T1D risk variants at over 20% of known loci colocalized with cis or trans pQTLs, and distinct sets of T1D loci colocalized with immune, pancreatic secretion, or gut-related proteins. We identified 23 proteins with evidence for a causal role in using pQTLs as genetic instruments in Mendelian Randomization which included multiple sensitivity analyses. Proteins increasing T1D risk were involved in immune processes (e.g. HLA-DRA) and, more surprisingly, T1D protective proteins were enriched in pancreatic secretions (e.g. CPA1), cholesterol metabolism (e.g. APOA1), and gut homeostasis. Genetic variants associated with plasma levels of T1D-protective pancreatic enzymes such as CPA1 were enriched in cis-regulatory elements in pancreatic exocrine and gut enteroendocrine cells, and the protective effects of CPA1 and other enzymes on T1D were consistent when using instruments specific to acinar cells. Finally, pancreatic enzymes had decreased acinar expression in T1D, including CPA1 which was altered prior to onset. Together, these results reveal causal biomarkers and highlight processes in the exocrine pancreas, immune system, and gut that modulate T1D risk.

Identification of unique cell type responses in pancreatic islets to stress

Diabetes involves the death or dysfunction of pancreatic β-cells. Analysis of bulk sequencing from human samples and studies using in vitro and in vivo models suggest that endoplasmic reticulum and inflammatory signaling play an important role in diabetes progression. To better characterize cell type-specific stress response, we perform multiplexed single-cell RNA sequencing to define the transcriptional signature of primary human islet cells exposed to endoplasmic reticulum and inflammatory stress. Through comprehensive pair-wise analysis of stress responses across pancreatic endocrine and exocrine cell types, we define changes in gene expression for each cell type under different diabetes-associated stressors. We find that β-, α-, and ductal cells have the greatest transcriptional response. We utilize stem cell-derived islets to study islet health through the candidate gene CIB1, which was upregulated under stress in primary human islets. Our findings provide insights into cell type-specific responses to diabetes-associated stress and establish a resource to identify targets for diabetes therapeutics.

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.

Selective epigenetic alterations in RNF43 in pancreatic exocrine cells from high-fat-diet-induced obese mice; implications for pancreatic cancer

ObjectivePancreatic cancer (PC) originates and progresses with genetic mutations in various oncogenes and suppressor genes, notably KRAS, CDKN2A, TP53, and SMAD4, prevalent across diverse PC cells. In addition to genetic mutations/deletions, persistent exposure to high-risk factors, including obesity, induces whole-genome scale epigenetic alterations contributing to malignancy. However, the impact of obesity on DNA methylation in the presymptomatic stage, particularly in genes prone to PC mutation, remains uncharacterized.ResultsWe analyzed the methylation levels of 197 loci in six genes (KRAS, CDKN2A, TP53, SMAD4, GNAS and RNF43) using Illumina Mouse Methylation BeadChip array (280 K) data from pancreatic exocrine cells obtained from high-fat-diet (HFD) induced obese mice. Results revealed no significant differences in methylation levels in loci between HFD- and normal-fat-diet (NFD)-fed mice, except for RNF43, a negative regulator of Wnt signaling, which showed hypermethylation in three loci. These findings indicate that, in mouse pancreatic exocrine cells, high-fat dietary obesity induced aberrant DNA methylation in RNF43 but not in other frequently mutated PC-related genes.

Infection with SARS-CoV-2 can cause pancreatic impairment

Evidence suggests associations between COVID-19 patients or vaccines and glycometabolic dysfunction and an even higher risk of the occurrence of diabetes. Herein, we retrospectively analyzed pancreatic lesions in autopsy tissues from 67 SARS-CoV-2 infected non-human primates (NHPs) models and 121 vaccinated and infected NHPs from 2020 to 2023 and COVID-19 patients. Multi-label immunofluorescence revealed direct infection of both exocrine and endocrine pancreatic cells by the virus in NHPs and humans. Minor and limited phenotypic and histopathological changes were observed in adult models. Systemic proteomics and metabolomics results indicated metabolic disorders, mainly enriched in insulin resistance pathways, in infected adult NHPs, along with elevated fasting C-peptide and C-peptide/glucose ratio levels. Furthermore, in elder COVID-19 NHPs, SARS-CoV-2 infection causes loss of beta (β) cells and lower expressed-insulin in situ characterized by islet amyloidosis and necrosis, activation of α-SMA and aggravated fibrosis consisting of lower collagen in serum, an increase of pancreatic inflammation and stress markers, ICAM-1 and G3BP1, along with more severe glycometabolic dysfunction. In contrast, vaccination maintained glucose homeostasis by activating insulin receptor α and insulin receptor β. Overall, the cumulative risk of diabetes post-COVID-19 is closely tied to age, suggesting more attention should be paid to blood sugar management in elderly COVID-19 patients.

A neuroligin-2-YAP axis regulates progression of pancreatic intraepithelial neoplasia

Pancreatic ductal adenocarcinoma (PDAC) is a tumor with a dismal prognosis that arises from precursor lesions called pancreatic intraepithelial neoplasias (PanINs). Progression from low- to high-grade PanINs is considered as tumor initiation, and a deeper understanding of this switch is needed. Here, we show that synaptic molecule neuroligin-2 (NLGN2) is expressed by pancreatic exocrine cells and plays a crucial role in the regulation of contact inhibition and epithelial polarity, which characterize the switch from low- to high-grade PanIN. NLGN2 localizes to tight junctions in acinar cells, is diffusely distributed in the cytosol in low-grade PanINs and is lost in high-grade PanINs and in a high percentage of advanced PDACs. Mechanistically, NLGN2 is necessary for the formation of the PALS1/PATJ complex, which in turn induces contact inhibition by reducing YAP function. Our results provide novel insights into NLGN2 functions outside the nervous system and can be used to model PanIN progression.

Ehmt2 inactivation in pancreatic epithelial cells shapes the transcriptional landscape and inflammation response of the whole pancreas.

Introduction: The Euchromatic Histone Methyl Transferase Protein 2 (EHMT2), also known as G9a, deposits transcriptionally repressive chromatin marks that play pivotal roles in the maturation and homeostasis of multiple organs. Recently, we have shown that Ehmt2 inactivation in the mouse pancreas alters growth and immune gene expression networks, antagonizing Kras-mediated pancreatic cancer initiation and promotion. Here, we elucidate the essential role of Ehmt2 in maintaining a transcriptional landscape that protects organs from inflammation. Methods: Comparative RNA-seq studies between normal postnatal and young adult pancreatic tissue from Ehmt2 conditional knockout animals (Ehmt2 fl/fl ) targeted to the exocrine pancreatic epithelial cells (Pdx1-Cre and P48 Cre/+ ), reveal alterations in gene expression networks in the whole organ related to injury-inflammation-repair, suggesting an increased predisposition to damage. Thus, we induced an inflammation repair response in the Ehmt2 fl/fl pancreas and used a data science-based approach to integrate RNA-seq-derived pathways and networks, deconvolution digital cytology, and spatial transcriptomics. We also analyzed the tissue response to damage at the morphological, biochemical, and molecular pathology levels. Results and discussion: The Ehmt2 fl/fl pancreas displays an enhanced injury-inflammation-repair response, offering insights into fundamental molecular and cellular mechanisms involved in this process. More importantly, these data show that conditional Ehmt2 inactivation in exocrine cells reprograms the local environment to recruit mesenchymal and immunological cells needed to mount an increased inflammatory response. Mechanistically, this response is an enhanced injury-inflammation-repair reaction with a small contribution of specific Ehmt2-regulated transcripts. Thus, this new knowledge extends the mechanisms underlying the role of the Ehmt2-mediated pathway in suppressing pancreatic cancer initiation and modulating inflammatory pancreatic diseases.

Experimental study of the pattern of genes activated by multi-day intermittent hypoxia in the rat pancreas

Intermittent hypoxia affects a variety of pathological conditions in the body and is used in medicine to reproduce the sanogenic therapeutic effect. Intermittent hypoxia is used for clinical indications to improve lung function; increase the body’s adaptive capacity; in obstructive sleep apnoea syndrome; in anaemia, diabetes mellitus. In cancer radiotherapy, intermittent hypoxic training helps to increase the sensitivity of the tumour to treatment. Intermittent hypoxia is useful in rehabilitation medicine to improve the physical recovery of patients after surgery or injury to improve the body’s functional capabilities. However, to date, the activity of regulatory genes, that activate the molecular mechanisms of the above-mentioned sanogenic effects of intermittent hypoxia has not been sufficiently studied. The aim of the study: to determine the expression of hypoxia-related genes in pancreas of Wistar rats under intermittent hypoxia. Materials and methods. The CFX-96 Touch™ real-time reverse transcription polymerase chain reaction (PCR) (Bio-Rad, USA) and the RT2 Profiler™ PCR Array Rat Hypoxia Signalling Pathway kit (QIAGEN, Germany) were used to analyse gene expression in experimental animals, where 84 genes involved in the hypoxia signalling pathway identified in the pancreas were studied. Results. According to the results of PCR analysis of pancreatic samples from intact animals and animals exposed to hypoxic training, the activity of the gene panel can be distributed as follows: genes with high expression compared to the intact group of animals, genes with low expression compared to the intact group of animals and genes in which no significant changes were detected in the samples compared to the intact group of animals. We have found, that the genes Cops5, F10, Jmjd6, Lgals3, Rbpjl, Vegfa have high expression activity compared to the intact group of animals. Conclusions. The increase in the expression of Cops5 by 10.29 times, Lgals3 by 2.94 times and Rbpjl by 5.73 times as a result of intermittent hypoxia can be regarded as an activating factor for the increase in the proliferation of endocrine and exocrine pancreatic cells and the growth of their antiapoptotic potential. The 3.20-fold increase in Jmjd6 gene expression under intermittent hypoxia can be interpreted as a regulatory effect through protein dehydroxylation and promotion of antiapoptotic protein activity in endocrine and exocrine pancreatic cells. The 5.99-fold increased level of Vegfa expression may promote angiogenesis in the pancreas under intermittent hypoxia.

Circular RNA hsa_circ_0001846 facilitates the malignant behaviors of pancreatic cancer by sponging miR-204-3p and upregulating KRAS expression

Pancreatic cancer (PC) is mainly derived from the exocrine pancreatic ductal epithelial cells, and it is strongly aggressive malignant tumor. Due to its insidious onset and the lack of effective diagnostic biomarkers, PC currently remains one of the main causes of cancer-related mortality worldwide. Recent studies have found that hsa_circ_0001846 is involved in the progression of multiple cancers and has the potential to become biomarkers, but its function and mechanism in PC remains unclear. We found by qRT-PCR experiments that hsa_circ_0001846 was upregulated in PC cells and tissues, while circBase, Sanger sequencing, agarose gel electrophoresis and FISH experiments identified the splicing site, ring structure and cellular localization of hsa_circ_0001846. Various functional experiments by using the construction of small interfering RNA targeting hsa_circ_0001846 and overexpression plasmid demonstrated that hsa_circ_0001846 promoted the proliferation, migration and invasion of PC cells. Moreover, the tumor weight and volume of nude mice were significantly reduced after the stable knockdown of hsa_circ_0001846. In the mechanism exploration, RNA pull-down experiments and dual-luciferase experiments helped us to determine that hsa_circ_0001846 regulated the KRAS expression by sponging miR-204-3p in PC, thus playing a pro-cancer role. In this study, the effect of miR-204-3p on PC was also explored for the first time, and we found that knockdown of miR-204-3p reversed the tumor suppressive effect caused by silencing hsa_circ_0001846, and silencing KRAS also rescued the pro-cancer effect caused by overexpression of hsa_circ_0001846. In conclusion, our study revealed the pro-cancer role of hsa_circ_0001846 in PC, and for the first time identified the mechanism that hsa_circ_0001846 regulated KRAS by sponging miR-204-3p to promote PC progression and had the potential to become a cancer biomarker.

Neutrophil-specific ORAI1 Calcium Channel Inhibition Reduces Pancreatitis-associated Acute Lung Injury.

Acute pancreatitis is initiated within pancreatic exocrine cells and sustained by dysregulated systemic inflammatory responses mediated by neutrophils. Store-operated Ca2+ entry (SOCE) through ORAI1 channels in pancreatic acinar cells triggers acute pancreatitis, and ORAI1 inhibitors ameliorate experimental acute pancreatitis, but the role of ORAI1 in pancreatitis-associated acute lung injury has not been determined. Here, we showed mice with pancreas-specific deletion of Orai1 (Orai1ΔPdx1, ∼70% reduction in the expression of Orai1) are protected against pancreatic tissue damage and immune cell infiltration, but not pancreatitis-associated acute lung injury, suggesting the involvement of unknown cells that may cause such injury through SOCE via ORAI1. Genetic (Orai1ΔMRP8) or pharmacological inhibition of ORAI1 in murine and human neutrophils decreased Ca2+ influx and impaired chemotaxis, reactive oxygen species production, and neutrophil extracellular trap formation. Unlike pancreas-specific Orai1 deletion, mice with neutrophil-specific deletion of Orai1 (Orai1ΔMRP8) were protected against pancreatitis- and sepsis-associated lung cytokine release and injury, but not pancreatic injury in experimental acute pancreatitis. These results define critical differences between contributions from different cell types to either pancreatic or systemic organ injury in acute pancreatitis. Our findings suggest that any therapy for acute pancreatitis that targets multiple rather than single cell types is more likely to be effective.

Lipid storage disease in 4 sibling superb birds-of-paradise (Lophorina superba).

Pedigree analysis, clinical, gross, microscopic, ultrastructural, and lipidomic findings in 4 female superb bird-of-paradise (SBOP, Lophorina superba) siblings led to the diagnosis of a primary inherited glycerolipid storage disease. These birds were the offspring of a related breeding pair (inbreeding coefficient = 0.1797) and are the only known SBOPs to display this constellation of lesions. The birds ranged from 0.75 to 4.3 years of age at the time of death. Two birds were euthanized and 1 died naturally due to the disease, and 1 died of head trauma with no prior clinical signs. Macroscopic findings included hepatomegaly and pallor (4/4), cardiac and renal pallor (2/4), and coelomic effusion (1/4). Microscopic examination found marked tissue distortion due to cytoplasmic lipid vacuoles in hepatocytes (4/4), cardiomyocytes (4/4), renal tubular epithelial cells (4/4), parathyroid gland principal cells (2/2), exocrine pancreatic cells (3/3), and the glandular cells of the ventriculus and proventriculus (3/3). Ultrastructurally, the lipids were deposited in single to coalescing or fused droplets lined by an inconspicuous or discontinuous monolayer membrane. Lipidomic profiling found that the cytoplasmic lipid deposits were primarily composed of triacylglycerols. Future work, including sequencing of the SBOP genome and genotyping, will be required to definitively determine the underlying genetic mechanism of this disease.

FRI657 Case Series On GLP-1 Receptor Agonist Related Acute Pancreatitis

Abstract Disclosure: A.U. Kulkarni: None. V. Mehta: None. M. Renzu: None. K. Pereira: None. M.A. Rather: None. Introduction: Acute pancreatitis (AP) has now become one of the leading causes of GI related hospital admissions in the United States. With increasing use of GLP-1 Receptor Agonists (GLP-1 RA) in T2DM and obesity, they are now being identified as one such class of drugs which can cause AP. We present this case series to discuss these adverse effects. Case 1: A 50 yo AA male with a history of T2DM and hypertension presented with acute severe epigastric pain, nausea and vomiting for 5 days. Vitals were stable. On physical exam, tenderness in the RUQ was noted. Labs revealed lipase of 313 U/l (11-82 U/l), BG of 213 mg/dL, HbA1c 11.3, normal LFT and lipid panel. Blood EtOH was negative. He denied tobacco, alcohol, and illicit drug use. CT abdomen showed acute interstitial edematous pancreatitis without cholelithiasis or choledocholithiasis. Liver ultrasound showed hepatic steatosis. He noted recent initiation of Semaglutide 6 months ago which was stopped 3 weeks prior to this visit due to abdominal discomfort. Previous Dulaglutide therapy was also discontinued due to GI intolerance. Home medication for DM otherwise included metformin and basal insulin. Case 2: A 68 yo AA woman with a history of T2DM, hypothyroidism presented after a week of severe epigastric pain, radiating to her back, with nausea and vomiting. Labs showed lipase 593 U/l (11-82 U/l), BG of 427 mg/dl, HbA1c of 10. Social history was non-contributory. CT Abdomen showed AP and no gallstones or bile duct dilatation. LFTs and lipid panel were unremarkable. Chart review noted prior admission for AP a month ago. Her home medications were basal Insulin and Dulaglutide (4 yrs). Drug induced AP from Dulaglutide was suspected. Lack of clinical improvement after 3 days of management prompted RUQ ultrasound, which was prematurely terminated due to pain during the scan. Subsequent CCK-HIDA was negative for acute cholecystitis but noted low gallbladder EF. Thus dulaglutide was identified as a potential trigger along with gallbladder dysmotility as a possible etiology for her recurrent AP. Both patients were managed with IV fluids, NPO diet and morphine. They were instructed to stop GLP-1 RA and discharged with PCP follow-up. Discussion: GLP-1 RA are now being widely used due to low risk of hypoglycemia and weight loss. Clinical trials with GLP-1 RA have shown mild, asymptomatic increase in lipase, amylase levels as well as rare incidences of AP. This has been attributed to the stimulation of pancreatic beta cells and exocrine duct cells leading to acinar cell hypertrophy, proinflammatory cytokine induction, causing pancreatic injury. Though drug-induced AP is uncommon and is a diagnosis of exclusion, detailed history taking, medication review and investigating for all other causes is of utmost importance. A good understanding of the drugs associated with AP should alert the physician to identify these agents and promptly discontinue them to prevent further complications. Presentation: Friday, June 16, 2023

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.

Peroxisomes during postnatal development of mouse endocrine and exocrine pancreas display cell-type- and stage-specific protein composition

Peroxisomal dysfunction unhinges cellular metabolism by causing the accumulation of toxic metabolic intermediates (e.g. reactive oxygen species, very -chain fatty acids, phytanic acid or eicosanoids) and the depletion of important lipid products (e.g. plasmalogens, polyunsaturated fatty acids), leading to various proinflammatory and devastating pathophysiological conditions like metabolic syndrome and age-related diseases including diabetes. Because the peroxisomal antioxidative marker enzyme catalase is low abundant in Langerhans islet cells, peroxisomes were considered scarcely present in the endocrine pancreas. Recently, studies demonstrated that the peroxisomal metabolism is relevant for pancreatic cell functionality. During the postnatal period, significant changes occur in the cell structure and the metabolism to trigger the final maturation of the pancreas, including cell proliferation, regulation of energy metabolism, and activation of signalling pathways. Our aim in this study was to (i) morphometrically analyse the density of peroxisomes in mouse endocrine versus exocrine pancreas and (ii) investigate how the distribution and the abundance of peroxisomal proteins involved in biogenesis, antioxidative defence and fatty acid metabolism change during pancreatic maturation in the postnatal period. Our results prove that endocrine and exocrine pancreatic cells contain high amounts of peroxisomes with heterogeneous protein content indicating that distinct endocrine and exocrine cell types require a specific set of peroxisomal proteins depending on their individual physiological functions. We further show that significant postnatal changes occur in the peroxisomal compartment of different pancreatic cells that are most probably relevant for the metabolic maturation and differentiation of the pancreas during the development from birth to adulthood.

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

Abstract C062: Investigating the role of pancreatic intraepithelial neoplasia in development of pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDA) is a dismal disease with a 5-year survival rate of 11%. This poor prognosis is due in part to a lack of early disease detection and resistance to current therapies. The most common PDA precursor is pancreatic intraepithelial neoplasia (PanINs); a microscopic lesion that cannot be detected by imaging. Accumulation of a series of genomic mutations in pancreatic exocrine cells leads to formation of PanINs through mechanisms that remain unknown. While PanIN development has been well-studied in genetically engineered mouse models, its onset and pathogenesis in humans has remained elusive due to the inability to study tissue from pathologically normal pancreases. Due to its abundance in digestive enzymes, the pancreas degrades shortly after death and autopsy samples are not suitable for several research applications that require fresh tissue. Through collaboration with the Gift of Life Organ and Tissue donation program, we performed histological and transcriptomic analysis on ten normal pancreata that were refused for transplant. Histological analysis revealed the presence of PanIN lesions in 6 of the 10 donors as early as 25 years of age. To delineate the molecular, cellular, and spatial composition of PanIN lesions to those from acinar and ductal cells we combined single cell RNA sequencing analysis with spatial transcriptomics for the same sample. Annotation of cellular composition of distinct tissue regions demonstrated that PanIN transcriptome closely resembled that of invasive PDA. Using differential expression analysis, we identified factors that were highly expressed in PanINs, but not expressed in normal acini or ducts. We validated the transcript-based findings with immunostaining and RNA in-situ hybridization. We then sought to characterize the microenvironment of the normal pancreas and of PanIN lesions using multiplex immunohistochemical analysis. We observed abundant fibroblasts and macrophages in normal areas of the pancreas as well as surrounding PanIN lesions, while T cells were limited to the latter. Currently, we are characterizing the transcriptome profile of macrophages and fibroblasts. Uncovering the factors that promote the development of sporadic PanINs and their progression to malignancy could aid in designing preventative strategies for high-risk individuals. Citation Format: Padma Kadiyala, Eileen Carpenter, Ahmed Elhossiny, Yaqing Zhang, Sarah Nelson, Fatima Lima, Katelyn Donahue, Wenting Du, Jake McGue, Hannah Watkoske, Holly Attebury, Donnele Daley, Filip Bednar, Arvind Rao, Timothy Frankel, Marina Pasca Di Magliano. Investigating the role of pancreatic intraepithelial neoplasia in development of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C062.

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.

Epigenome-wide association analysis of pancreatic exocrine cells from high-fat- and normal diet-fed mice and its potential use for understanding the oncogenesis of human pancreatic cancer

Aberrant DNA methylation is associated with oncogenesis of various human cancers, including pancreatic cancer (PC). PC is the seventh most common cancer, and obesity is a known high-risk factor. However, whether obesity influences DNA methylation in pancreatic exocrine cells and if this influences PC development remain unclear. Here, we performed an epigenome-wide analysis of isolated pancreatic exocrine cells obtained from mice with high-fat-diet-induced obesity (DIO). Using the Illumina Mouse Methylation BeadChip array (280K), we identified 316 differentially methylated regions (DMRs) that were enriched for cellular processes, such as DNA repair, transcription regulation, and cell proliferation, which confirmed obesity-related dysregulation of certain metabolic processes in the pancreatic cells in DIO mice. Comparing the DMRs with those in stage IB PC helped identify 82 overlapping DMRs. Three pathways including the cell hypertrophy pathway involving PLC, PKC, SMAD2/3, and TRKA; the metabolic control pathway involving CREB and AMPK; and the potassium regulation pathway involving K+-channels, were shared between the pancreatic exocrine cells from DIO mice and stage IB PC. Enhanced alteration in the methylation level was observed in PC compared to that in DIO mice. These findings indicated that obesity influences DNA methylation in pancreatic exocrine cells of DIO mice, and persistent dysregulation of DNA methylation in individuals with obesity may result in PC development.

PMON230 Pancreatic Exocrine Cells are Altered during the Progression of Ovarian Cancer-Driven Cachexia in Female Mice

Abstract Cancer-associated cachexia (CAC) is a progressive debilitating syndrome that frequently complicates metabolic function in body vital organs and subsequently causes a high mortality rate in cancer patients. However, the underlying mechanisms and the functional consequences of organs dysfunction during CAC are not fully elucidated. Recently, we have developed a preclinical model characterized by oocyte-specific knockin for constitutively active Pi3k (Pik3ca*) which induces ovarian granulosa cell tumor (GCT) and mimics the stagewise progression of CAC in humans. Here, we aim to characterize the pathophysiological effect of cachexia on pancreatic dysfunction and investigate the potential role of the pancreas in the development and complication of cachexia in transgenic female mice with ovarian cancer. Notably, we found that cachectic mice showed a drastic loss in the pancreatic volume (PV) before death. Histological and morphometric assays revealed that exocrine pancreatic acinar atrophy (PAA) is drastic in the pancreas of cachectic PIK3CA* mice. The pancreas appeared to have an increased number of pancreatic stellate-shaped cells between acini. No significant changes were observed in the morphology of endocrine islets. Immunohistochemical assay confirmed a high level of TNF-a in atrophied pancreatic tissue and decreased intensity of pancreatic amylase in the cytoplasm of atrophied pancreatic acinar cells. Additionally, moderate fibrosis was also observed in the wall of pancreatic ducts and blood vessels, but not between the pancreatic acini. Masson trichrome and histochemical staining confirmed expression of extracellular matrix proteins including collagen I, II, IV, and a -smooth muscle actin in ducts and vessel walls. Overall, our preliminary findings in this novel CAC mouse model strongly suggest potential signs of exhausted exocrine pancreatic cells during the progression of ovarian cancer-driven cachexia. This mouse line could be an ideal preclinical model to aid in clarifying molecular mediators of pancreatic pathophysiology and metabolic dysfunction during CAC. Keywords: Ovarian cancer-driven cachexia, pancreas, atrophy, amylase. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.