Macrophage-induced reactive oxygen species in the initiation of pancreatic cancer: a mini-review.

Pancreatic inflammation is a risk factor for the development of pancreatic cancer. Increased presence of inflammatory macrophages can be found in response to a KRAS mutation in acinar cells or in response to experimentally-induced pancreatitis. Inflammatory macrophages induce pancreatic acinar cells to undergo dedifferentiation to a duct-like progenitor stage, a process called acinar-to-ductal metaplasia (ADM). Occurrence of ADM lesions are believed to be the initiating event in tumorigenesis. Here we will discuss how macrophage-induced oxidative stress contributes to ADM and how ADM cells shape the fibrotic stroma needed for further progression.

Activin A signaling stimulates neutrophil activation and macrophage migration in pancreatitis.

Acute Pancreatitis (AP) is associated with high mortality and current treatment options are limited to supportive care. We found that blockade of activin A (activin) in mice improves outcomes in two murine models of AP. To test the hypothesis that activin is produced early in response to pancreatitis and is maintained throughout disease progression to stimulate immune cells, we first performed digital spatial profiling (DSP) of human chronic pancreatitis (CP) patient tissue. Then, transwell migration assays using RAW264.7 mouse macrophages and qPCR analysis of "neutrophil-like" HL-60 cells were used for functional correlation. Immunofluorescence and western blots on cerulein-induced pancreatitis samples from pancreatic acinar cell-specific Kras knock-in (Ptf1aCreER™; LSL-KrasG12D) and functional WT Ptf1aCreER™ mouse lines mimicking AP and CP to allow for in vivo confirmation. Our data suggest activin promotes neutrophil and macrophage activation both in situ and in vitro, while pancreatic activin production is increased as early as 1 h in response to pancreatitis and is maintained throughout CP in vivo. Taken together, activin is produced early in response to pancreatitis and is maintained throughout disease progression to promote neutrophil and macrophage activation.

Biomimetic delivery of emodin via macrophage membrane-coated UiO-66-NH2 nanoparticles for acute pancreatitis treatment.

Acute pancreatitis (AP) is a severe inflammatory condition with a rising incidence and high mortality rates, especially in severe cases. Emodin (ED), known for its potent anti-inflammatory properties, holds promise in addressing AP. However, its clinical application is hindered by limitations such as low bioavailability and insufficient target specificity. Herein, we developed a novel drug delivery system using macrophage membrane-coated UiO-66-NH2 nanoparticles loaded with ED (MVs-UiO-ED). UiO-66-NH2 was successfully synthesized and characterized, revealing an octahedral structure with a suitable size distribution. The successful loading of ED onto UiO-66-NH2 was confirmed by ultraviolet and infrared spectroscopy. Subsequently, MVs-UiO-ED was prepared by coating macrophage membrane-derived vesicles onto UiO-ED, resulting in a biomimetic delivery system. In vitro release studies demonstrated that MVs-UiO-ED exhibited a sustained-release profile, indicating its potential for prolonged drug circulation. An AP mouse model was established to evaluate the therapeutic efficacy of MVs-UiO-ED. Compared with the model group, MVs-UiO-ED significantly reduced serum levels of α-amylase and lipase, two indicators of pancreatitis severity. Furthermore, histopathological examinations revealed that MVs-UiO-ED ameliorated pancreatic tissue damage. This study underscores the potential of MVs-UiO-ED as an effective therapeutic approach for AP.

NETosis in Surgery: Pathophysiology, Prevention, and Treatment.

OBJECTIVE: To provide surgeons with an understanding of the latest research on NETosis, including the pathophysiology and treatment of conditions involving neutrophil extracellular traps (NETs) in the care of surgical patients. BACKGROUND: A novel function of neutrophils, the formation of NETs, was described in 2004. Neutrophils form mesh-like structures of extruded decondensed chromatin, comprising DNA and histones decorated with bactericidal proteins. These NETs exert antimicrobial action by trapping microorganisms and preventing their wider dissemination through the body. RESULTS: A narrative review of the existing literature describing NETosis was conducted, including NET pathophysiology, conditions related to NET formation, and treatments relevant to surgeons. CONCLUSIONS: In addition to its canonical antimicrobial function, NETosis can exacerbate inflammation, resulting in tissue damage and contributing to numerous diseases. NETs promote gallstone formation and acute pancreatitis, impair wound healing in the early postoperative period and in chronic wounds, and facilitate intravascular coagulation, cancer growth, and metastasis. Agents that target NET formation or removal have shown promising efficacy in treating these conditions, although large clinical trials are required to confirm these benefits.

Autoimmune pancreatitis: Biopsy interpretation and differential diagnosis.

Autoimmune pancreatitis (AIP) is classified into type 1 (IgG4-related) and type 2 (IgG4-unrelated) and the interpretation of pancreatic biopsy findings plays a crucial role in their diagnosis. Needle biopsy of type 1 AIP in the acute or subacute phase shows a diffuse lymphoplasmacytic infiltrate, storiform fibrosis, obliterative phlebitis, and the infiltration of many IgG4-positive plasma cells. In a later phase, changes become less inflammatory and more fibrotic, making interpretations more challenging. Confirmation of the lack of 'negative' findings that are unlikely to occur in type 1 AIP (e.g., neutrophilic infiltration, abscess) is important to avoid an overdiagnosis. The number of IgG4-positive plasma cells increases to >10 cells/high-power field (hpf), and the IgG4/IgG-positive plasma cell ratio exceeds 40 %. However, these are minimal criteria and typical cases show >30 positive cells/hpf and a ratio >70 % even in biopsy specimens. Therefore, cases with a borderline increase in this number or ratio need to be diagnosed with caution. In cases of ductal adenocarcinoma, the upstream pancreas rarely shows type 1 AIP-like changes; however, the ratio of IgG4/IgG-positive plasma cells is typically <40 %. Although the identification of a granulocytic epithelial lesion (GEL) is crucial for type 2 AIP, this finding needs to be interpreted in conjunction with a background dense lymphoplasmacytic infiltrate. An isolated neutrophilic duct injury can occur in peritumoral or obstructive pancreatitis. Drug-induced pancreatitis in patients with inflammatory bowel disease often mimics type 2 AIP clinically and pathologically. IL-8 and PD-L1 are potential ancillary immunohistochemical markers for type 2 AIP, requiring validation studies.

Protein kinase D1 - A targetable mediator of pancreatic cancer development.

Members of the Protein kinase D (PKD) kinase family each play important cell-specific roles in the regulation of normal pancreas functions. In pancreatic diseases PKD1 is the most widely characterized isoform with roles in pancreatitis and in induction of pancreatic cancer and its progression. PKD1 expression and activation increases in pancreatic acinar cells through macrophage secreted factors, Kirsten rat sarcoma viral oncogene homolog (KRAS) signaling, and reactive oxygen species (ROS), driving the formation of precancerous lesions. In precancerous lesions PKD1 regulates cell survival, growth, senescence, and generation of doublecortin like kinase 1 (DCLK1)-positive cancer stem cells (CSCs). Within tumors, regulation by PKD1 includes chemoresistance, apoptosis, proliferation, CSC features, and the Warburg effect. Thus, PKD1 plays a critical role throughout pancreatic disease initiation and progression.

Association of high-risk stigmata and worrisome features with advanced neoplasia in intraductal papillary mucinous neoplasms (IPMN): A systematic review.

BACKGROUND: This systematic review aimed to assess the diagnostic accuracy of the International Consensus Fukuoka Guidelines (ICG2017) in identifying high-risk lesions of Intraductal Papillary Mucinous Neoplasms (IPMNs). METHODS: The ICG2017 revision committee conducted a comprehensive literature review to establish evidence-based statements on IPMNs. The review focused on articles examining the diagnostic value of imaging features (e.g., cyst or main pancreatic duct diameter), clinical symptoms associated with IPMN, and serum biomarkers. Five clinical questions regarding high-risk stigmata (HRS) and worrisome features (WF) in the ICG2017 guidelines were addressed. RESULTS: A total of 210 articles were reviewed. The findings revealed a significant association between the presence of mural nodules ≥5 mm in diameter or solid components with contrast enhancement and the diagnosis of high-grade dysplasia or invasive carcinoma. Contrast-enhanced diagnostic tools, such as CT, MRI, or EUS, demonstrated the highest prediction rate and were recommended. Positive cytology was identified as an HRS, while symptoms like acute pancreatitis and cyst diameter growth ≥2.5 mm per year were considered WFs. The use of nomograms and multiple diagnostic factors was recommended for optimal IPMN management. CONCLUSIONS: This systematic review provides evidence supporting the improved diagnostic accuracy of ICG2017 in identifying high-risk lesions of IPMN. The multidisciplinary incorporation of HRS and WF based on imaging findings and clinical symptoms is crucial. These findings should inform the revision of ICG2017, enhancing the evaluation and management of IPMN patients. By implementing these recommendations, clinicians can make more informed decisions, leading to better diagnosis and treatment outcomes for high-risk IPMN cases.

Acute pancreatitis in intraductal papillary mucinous neoplasm: a single-center retrospective cohort study with systematic review and meta-analysis.

BACKGROUND: Intraductal papillary mucinous neoplasm (IPMN) is a cystic tumor of the pancreas arising from abnormal papillary proliferation of ductal epithelial cells, and is a precancerous lesion of pancreatic malignancy. This study aimed to evaluate associations between acute pancreatitis (AP) and histologic subtypes of IPMN. METHODS: In the clinical study, patients with IPMN confirmed by surgical resection specimens at our institute between 2009 and 2021 were eligible for inclusion. Associations and predictive accuracy of AP on the presence of HGD were determined by logistic regressions. In addition, a systematic review and meta-analysis was conducted through literatures upon search in PubMed, Embase, CENTRAL, China National Knowledge Infrastructure (CKNI), and Wanfang database, up to June, 2023. Pooled effects of the associations between AP and HGD and intestinal epithelial subtype subtype, shown as odds ratios (ORs) with 95% confidence intervals (CIs), were calculated using random effects model. RESULTS: The retrospective cohort study included 47 patients (32 males, 15 females) diagnosed with IPMN at our center between 2009 and 2021, including 11 cases with AP (median 62 years) and 36 cases (median 64.5 years) without. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of AP in predicting HGD were 78.7%, 57.1%, 82.5%, 36.4%, and 91.7%, respectively. Univariate logistic regression analysis showed that AP group had greater odds of presence of HGD (OR: 6.29,95% CI: 1.14-34.57) than non-AP group. Meta-analysis of five case-control studies in the literature included 930 patients and showed that AP-IPMN patients had higher odds for HGD (OR: 2.13, 95% CI 1.38-3.29) and intestinal epithelial subtype (OR: 5.38, 95% CI: 3.50-8.27) compared to non-AP IPMN. CONCLUSIONS: AP is predictive of malignancy in patients with IPMN.

Galantamine ameliorates experimental pancreatitis.

BACKGROUND: Acute pancreatitis is a common and serious inflammatory condition currently lacking disease modifying therapy. The cholinergic anti-inflammatory pathway (CAP) is a potent protective anti-inflammatory response activated by vagus nerve-dependent α7 nicotinic acetylcholine receptor (α7nAChR) signaling using splenic CD4+ T cells as an intermediate. Activating the CAP ameliorates experimental acute pancreatitis. Galantamine is an acetylcholinesterase inhibitor (AChEI) which amplifies the CAP via modulation of central muscarinic ACh receptors (mAChRs). However, as mAChRs also activate pancreatitis, it is currently unknown whether galantamine would be beneficial in acute pancreatitis. METHODS: The effect of galantamine (1-6 mg/kg-body weight) on caerulein-induced acute pancreatitis was evaluated in mice. Two hours following 6 hourly doses of caerulein (50 µg/kg-body weight), organ and serum analyses were performed with accompanying pancreatic histology. Experiments utilizing vagotomy, gene knock out (KO) technology and the use of nAChR antagonists were also performed. RESULTS: Galantamine attenuated pancreatic histologic injury which was mirrored by a reduction in serum amylase and pancreatic inflammatory cytokines and an increase the anti-inflammatory cytokine IL-10 in the serum. These beneficial effects were not altered by bilateral subdiaphragmatic vagotomy, KO of either choline acetyltransferase+ T cells or α7nAChR, or administration of the nAChR ganglionic blocker mecamylamine or the more selective α7nAChR antagonist methyllycaconitine. CONCLUSION: Galantamine improves acute pancreatitis via a mechanism which does not involve previously established physiological and molecular components of the CAP. As galantamine is an approved drug in widespread clinical use with an excellent safety record, our findings are of interest for further evaluating the potential benefits of this drug in patients with acute pancreatitis.

Decreased neutrophil counts prolong inflammation in acute pancreatitis and cause inflammation spillover to distant organs.

BACKGROUND/OBJECTIVE: Acute pancreatitis is an aseptic inflammation caused by pathologically activated pancreatic enzymes and inflammatory mediators produced secondarily by neutrophils and other inflammatory cells and is one of the most difficult diseases to treat. This study aimed to investigate the role of neutrophils in pancreatitis by examining tissue dynamics. METHODS: We created a model of caerulein-induced pancreatitis in 12-week-old male granulocyte colony-stimulating factor knockout mice (G-CSF-KO) and wild-type littermate control mice (six intraperitoneal injections of caerulein [80 µg/kg body weight] at hourly intervals for 2 days). Mice were sacrificed 0, 3, 6, 12, 24, 36, 48, 72, and 168 h after caerulein administration and examined histologically. RESULTS: The survival rate after one week of caerulein administration was 100 % in the control mice, whereas it was significantly lower (10 %) in the G-CSF-KO mice. Histological examination revealed significant hemorrhage and inflammatory cell migration in the G-CSF-KO mice, indicating prolonged inflammation. CONCLUSION: Prolonged inflammation was observed in the G-CSF-KO mice. Tissue cleanup by neutrophils during the acute phase of inflammation may influence healing through the chronic phase.

Microenvironment of pancreatic inflammation: calling for nanotechnology for diagnosis and treatment.

Acute pancreatitis (AP) is a common and life-threatening digestive disorder. However, its diagnosis and treatment are still impeded by our limited understanding of its etiology, pathogenesis, and clinical manifestations, as well as by the available detection methods. Fortunately, the progress of microenvironment-targeted nanoplatforms has shown their remarkable potential to change the status quo. The pancreatic inflammatory microenvironment is typically characterized by low pH, abundant reactive oxygen species (ROS) and enzymes, overproduction of inflammatory cells, and hypoxia, which exacerbate the pathological development of AP but also provide potential targeting sites for nanoagents to achieve early diagnosis and treatment. This review elaborates the various potential targets of the inflammatory microenvironment of AP and summarizes in detail the prospects for the development and application of functional nanomaterials for specific targets. Additionally, it presents the challenges and future trends to develop multifunctional targeted nanomaterials for the early diagnosis and effective treatment of AP, providing a valuable reference for future research.

Interleukin-22 and acute pancreatitis: A review.

Acute pancreatitis (AP) is one of the most common gastrointestinal diseases, and it is divided into 3 types according to its severity:mild acute pancreatitis, moderately severe acute pancreatitis, and severe acute pancreatitis. The mortality in severe acute pancreatitis is approximately 15% to 30% due to multiorgan dysfunction and the lack of specific treatment. Interleukin-22 (IL-22) is a member of the Interleukin-10 family, and it can activate several downstream signaling pathways by binding to its receptor complex, thus it is involved in cell differentiation, proliferation, and apoptosis. Some studies have reported the elevated level of IL-22 in patients with AP, which suggests IL-22 may be involved in the pathogenesis of AP. And many studies have shown that IL-22 had a protective effect against AP. This article reviews the characteristics and mechanism of IL-22 and its role in AP to provide insight into the treatment of AP.

The role of iron and ferroptosis in the pathogenesis of acute pancreatitis.

Acute pancreatitis (AP) is an inflammatory disease of the pancreas. Iron is an essential element for life and is involved in many metabolic processes. Ferroptosis is a type of regulated cell death that is triggered by iron and oxidative stress. A well-established mouse AP model was adopted to study the role of iron and ferroptosis in the pathogenesis of pancreatitis. Mice were injected with cerulein to induce AP, and pancreatic tissue samples were analyzed to determine the pathology, cell death, iron deposition, expression of iron transporters, and lipid peroxidation. The role of iron was studied by giving mice extra iron or iron chelator. In vitro studies with acinar cells with ferroptosis activator and inhibitor were also performed to assess the inflammatory response. Iron was found accumulated in the pancreatic tissue of mice who suffered cerulein-induced pancreatitis. Cell death and lipid peroxidation increased in these tissues and could be further modulated by iron dextran or iron chelator. Mice given Hemin through gavage had reduced levels of GSH in pancreatic tissue and increased inflammatory response. Studies with acinar cells showed increased levels of lipid peroxidation and ferroptosis-specific mitochondrial damage when treated with ferroptosis inducer and inflammatory cytokines.

Stabilized Window for Intravital Imaging of the Murine Pancreas.

The physiology and pathophysiology of the pancreas are complex. Diseases of the pancreas, such as pancreatitis and pancreatic adenocarcinoma (PDAC) have high morbidity and mortality. Intravital imaging (IVI) is a powerful technique enabling the high-resolution imaging of tissues in both healthy and diseased states, allowing for real-time observation of cell dynamics. IVI of the murine pancreas presents significant challenges due to the deep visceral and compliant nature of the organ, which make it highly prone to damage and motion artifacts. Described here is the process of implantation of the Stabilized Window for Intravital imaging of the murine Pancreas (SWIP). The SWIP allows IVI of the murine pancreas in normal healthy states, during the transformation from the healthy pancreas to acute pancreatitis induced by cerulein, and in malignant states such as pancreatic tumors. In conjunction with genetically labeled cells or the administration of fluorescent dyes, the SWIP enables the measurement of single-cell and subcellular dynamics (including single-cell and collective migration) as well as serial imaging of the same region of interest over multiple days. The ability to capture tumor cell migration is of particular importance as the primary cause of cancer-related mortality in PDAC is the overwhelming metastatic burden. Understanding the physiological dynamics of metastasis in PDAC is a critical unmet need and crucial for improving patient prognosis. Overall, the SWIP provides improved imaging stability and expands the application of IVI in the healthy pancreas and malignant pancreas diseases.

Probiotics mixture and taurine attenuate L-arginine-induced acute pancreatitis in rats: Impact on transient receptor potential vanilloid-1 (TRPV-1)/IL-33/NF-κB signaling and apoptosis.

Acute pancreatitis (AP) is an inflammatory disorder of acinar cells. It may develop into severe chronic pancreatitis with a significant mortality rate. The current study aimed to assess the therapeutic effect of a Lactobacillus (LAB) mixture against rat AP. Six groups were created including control, taurine (300 mg/kg; i.p.) for 7 days, LAB mixture for 7 days, L-arginine (2.5 g/kg; i.p.) 2 doses with 1 h interval on 1st day, L-arginine+taurine, and L-arginine+LAB. Serum amylase and lipase activities were measured. Pancreatic tissue was used for histopathological examination, oxidative stress biomarkers including malondialdehyde (MDA) and reduced glutathione (GSH), and inflammatory biomarkers including myeloperoxidase (MPO) and interleukin (IL)-33 assessment. qRT-PCR was used for transient receptor potential vanilloid-1 (TRPV-1) investigation and Western blot analysis for measuring nuclear factor kappa-B (NF-κBp65) and the apoptosis biomarker; caspase-3. Taurine and LAB reduced lipase and significantly ameliorated induced oxidative stress by normalizing MDA and GSH contents. They counteracted inflammation by reducing MPO, IL-33, NF-κBp65, and TRPV-1. In addition, taurine and LAB counteracted apoptosis as proved by reduced caspase-3 expression. Taken together, these findings indicate that taurine and the use LAB mixture can mitigate AP by L-arginine via influencing TRPV-1/IL-33/NF-κB signaling together with exhibiting potent antioxidant and anti-inflammatory effects.

Healing effect of warfarin in the course of cerulein-induced acute pancreatitis in rats.

Acute pancreatitis (AP) is the most common gastrointestinal disease leading to hospitalizations and unexpected deaths. The development of AP leads to damage of the pancreatic microcirculation with a cascade of subsequent events resulting, among others, in coagulopathy. Previous research showed that anticoagulants can be important therapeutic agents. Heparin and acenocoumarol can alleviate the course of AP, as well as accelerate healing and post-inflammatory regeneration of the pancreas. The aim of this study was to determine whether warfarin, a drug with more stable effects than acenocoumarol, affects the healing and regeneration of the pancreas in the cerulein-induced AP. AP was evoked in Wistar male rats by intraperitoneal administration of cerulein. The first dose of warfarin (45, 90 or 180 µg/kg) was administered 24 hours after the first dose of cerulein and the doses of warfarin were repeated once a day in subsequent 10 days. The severity of AP was assessed immediately after the last dose of cerulein, as well as at days 1, 2, 3, 5, and 10 after AP induction. Treatment with warfarin dose-dependently increased international normalized ratio (INR) and attenuated the severity of pancreatitis in histological examination and accelerated pancreatic recovery. These effects were accompanied with a faster reduction in the AP-evoked increase in serum activity of amylase and lipase, the serum concentration of pro-inflammatory interleukin-1ß, and the plasma level of D-Dimer. In addition, treatment with warfarin decreased pancreatic weight (an index of pancreatic edema) and improved pancreatic blood flow in rats with AP. The therapeutic effect was particularly pronounced after the administration of warfarin at a dose of 90 µg/kg. We conclude that treatment with warfarin accelerated regeneration of the pancreas and recovery in the course of cerulein-induced mild-edematous acute pancreatitis.

Evaluation of circulating miR-216a and miR-217 as biomarkers of pancreatic damage in the L-arginine-induced acute pancreatitis mouse model.

We investigated the usefulness of circulating miR-216a-5p and miR-217-5p that are pancreas-enriched micro RNAs (miRNAs) as biomarkers of acute pancreatic damage, and compared them with conventional pancreatic biomarkers in L-arginine-induced acute pancreatitis mouse model. As the results, amylase and lipase levels apparently increased and peaked on Day 3 when acute pancreatitis including acinar cell degeneration/necrosis and inflammatory cell infiltration reached its peak. In contrast, miR-216a-5p and miR-217-5p increased from Day 1 when histopathological findings in the acinar cells were limited to decreased zymogen granules, and the increases in ratios were much higher than those of amylase and lipase. The miRNAs remained at high levels until Day 5 when the pseudo-tubular complex and replacement of inflammatory cells and fibrotic cells were apparent instead of necrosis, whereas amylase and lipase levels decreased to the control levels. Furthermore, we examined the relationship between biomarker levels and histopathological degeneration/necrosis scores in the acinar cells. miR-216a-5p and miR-217-5p levels increased depending on the score of degeneration/necrosis, and all individual miRNAs exceeded the control levels from a score of 2 (focal necrosis), whereas all individual amylase and lipase levels exceeded the control levels at scores of 4 (lobular necrosis) and 3 (sublobular necrosis), respectively. In conclusion, we demonstrated that circulating miR-216a-5p and miR-217-5p could detect pancreatic damage earlier with greater magnitude, and the sensitivity to detect acinar cell degeneration/necrosis was superior to that of conventional biomarkers in the L-arginine-induced acute pancreatitis mouse model.

The anti-inflammatory effect of dimethyl trisulfide in experimental acute pancreatitis.

Various organosulfur compounds, such as dimethyl trisulfide (DMTS), display anti-inflammatory properties. We aimed to examine the effects of DMTS on acute pancreatitis (AP) and its mechanism of action in both in vivo and in vitro studies. AP was induced in FVB/n mice or Wistar rats by caerulein, ethanol-palmitoleic acid, or L-ornithine-HCl. DMTS treatments were administered subcutaneously. AP severity was assessed by pancreatic histological scoring, pancreatic water content, and myeloperoxidase activity measurements. The behaviour of animals was followed. Pancreatic heat shock protein 72 (HSP72) expression, sulfide, and protein persulfidation were measured. In vitro acinar viability, intracellular Ca2+ concentration, and reactive oxygen species production were determined. DMTS dose-dependently decreased the severity of AP. It declined the pancreatic infiltration of leukocytes and cellular damage in mice. DMTS upregulated the HSP72 expression during AP and elevated serum sulfide and low molecular weight persulfide levels. DMTS exhibited cytoprotection against hydrogen peroxide and AP-inducing agents. It has antioxidant properties and modulates physiological but not pathophysiological Ca2+ signalling. Generally, DMTS ameliorated AP severity and protected pancreatic acinar cells. Our findings indicate that DMTS is a sulfur donor with anti-inflammatory and antioxidant effects, and organosulfur compounds require further investigation into this potentially lethal disease.

RBPJ Deficiency Sensitizes Pancreatic Acinar Cells to KRAS-Mediated Pancreatic Intraepithelial Neoplasia Initiation.

BACKGROUND AND AIMS: Development of pancreatic ductal adenocarcinoma (PDAC) is a multistep process intensively studied; however, precocious diagnosis and effective therapy still remain unsatisfactory. The role for Notch signaling in PDAC has been discussed controversially, as both cancer-promoting and cancer-antagonizing functions have been described. Thus, an improved understanding of the underlying molecular mechanisms is necessary. Here, we focused on RBPJ, the receiving transcription factor in the Notch pathway, examined its expression pattern in PDAC, and characterized its function in mouse models of pancreatic cancer development and in the regeneration process after acute pancreatitis. METHODS: Conditional transgenic mouse models were used for functional analysis of RBPJ in the adult pancreas, initiation of PDAC precursor lesions, and pancreatic regeneration. Pancreata and primary acinar cells were tested for acinar-to-ductal metaplasia together with immunohistology and comprehensive transcriptional profiling by RNA sequencing. RESULTS: We identified reduced RBPJ expression in a subset of human PDAC specimens. Ptf1α-CreERT-driven depletion of RBPJ in transgenic mice revealed that its function is dispensable for the homeostasis and maintenance of adult acinar cells. However, primary RBPJ-deficient acinar cells underwent acinar-to-ductal differentiation in ex vivo. Importantly, oncogenic KRAS expression in the context of RBPJ deficiency facilitated the development of pancreatic intraepithelial neoplasia lesions with massive fibrotic stroma formation. Interestingly, RNA-sequencing data revealed a transcriptional profile associated with the cytokine/chemokine and extracellular matrix changes. In addition, lack of RBPJ delays the course of acute pancreatitis and critically impairs it in the context of KRASG12D expression. CONCLUSIONS: Our findings imply that downregulation of RBPJ in PDAC patients derepresses Notch targets and promotes KRAS-mediated pancreatic acinar cells transformation and desmoplasia development.

Tumor Necrosis Factor Alpha Preconditioned Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles Enhance the Inhibition of Necroptosis of Acinar cells in Severe Acute Pancreatitis.

Severe acute pancreatitis (SAP) is a common abdominal emergency with a high mortality rate and a lack of effective therapeutic options. Although mesenchymal stem cell (MSC) transplantation is a potential treatment for SAP, the mechanism remains unclear. It has been suggested that MSCs may act mainly through paracrine effects; therefore, we aimed to demonstrate the therapeutic efficacy of extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (UCMSCs) for SAP. Na-taurocholate was used to induce a rat SAP model through retrograde injection into the common biliopancreatic duct. After 72 h of EVs transplantation, pancreatic pathological damage was alleviated, along with a decrease in serum amylase activity and pro-inflammatory cytokine levels. Interestingly, when UCMSCs were preconditioned with 10 ng/mL tumor necrosis factor alpha (TNF-α) for 48 h, the obtained EVs (named TNF-α-EVs) performed an enhanced efficacy. Furthermore, both animal and cellular experiments showed that TNF-α-EVs alleviated the necroptosis of acinar cells of SAP through RIPK3/MLKL axis. In conclusion, our study demonstrated that TNF-α-EVs were able to enhance the therapeutic effect on SAP by inhibiting necroptosis compared to normal EVs. This study heralds that TNF-α-EVs may be a promising therapeutic approach for SAP in the future.