Establishment of animal models for three types of pancreatitis and analyses of regeneration mechanisms

Transfer of inflammatory mitochondria via extracellular vesicles from M1 macrophages induces ferroptosis of pancreatic beta cells in acute pancreatitis

Extracellular vesicles (EVs) exert a significant influence not only on the pathogenesis of diseases but also on their therapeutic interventions, contingent upon the variances observed in their originating cells. Mitochondria can be transported between cells via EVs to promote pathological changes. In this study, we found that EVs derived from M1 macrophages (M1-EVs), which encapsulate inflammatory mitochondria, can penetrate pancreatic beta cells. Inflammatory mitochondria fuse with the mitochondria of pancreatic beta cells, resulting in lipid peroxidation and mitochondrial disruption. Furthermore, fragments of mitochondrial DNA (mtDNA) are released into the cytosol, activating the STING pathway and ultimately inducing apoptosis. The potential of adipose-derived stem cell (ADSC)-released EVs in suppressing M1 macrophage reactions shows promise. Subsequently, ADSC-EVs were utilized and modified with an F4/80 antibody to specifically target macrophages, aiming to treat ferroptosis of pancreatic beta cells in vivo. In summary, our data further demonstrate that EVs secreted from M1 phenotype macrophages play major roles in beta cell ferroptosis, and the modified ADSC-EVs exhibit considerable potential for development as a vehicle for targeted delivery to macrophages.

Extracellular Vesicle Content Changes Induced by Melatonin Promote Functional Recovery of Pancreatic Beta Cells in Acute Pancreatitis

Aim

Acute pancreatitis is an inflammatory disorder of the pancreas, which causes abnormal activation of immune cells. The macrophages were accumulated in pancreas and infiltrated into islets during the AP process to induce abnormal glucose metabolism. However, the role of macrophages in abnormal glucose metabolism remains understood. Extracellular vesicles act in the regulation of intercellular function, but whether EVs secreted by macrophages contribute to β cell failure and apoptosis in AP is unclear. Based on this, the aim of this study was to reveal the role of macrophages-EVs in AP and develop a treatment for symptoms of hyperglycemia in AP.

Methods

The AP model was established and treated by various doses of melatonin to analyze the therapeutic effect. The accumulation and polarization of macrophages in the AP pancreas were observed, and the β cells were incubated with pancreatic derived EVs to analyze the role in β cell failure and apoptosis.

Results

The results showed that macrophages were recruited and polarized to M1 phenotype macrophages in the pancreas of AP mice, which obtained inflammatory EVs that contained specific miRNAs to induce β cell failure and apoptosis. Then, the EVs derived from M1 macrophages triggered β cell failure and apoptosis. Melatonin prevented polarization of macrophages to the M1 phenotype in vivo, which reduced the secretion of inflammatory EVs, changed the abundance of miRNAs in EVs, and therefore decreased inflammatory EV-mediated β cell failure and apoptosis.

Conclusion

Our results demonstrate that similar to 20S proteasome inhibitor MG132, analyses indicated that melatonin prevented degradation of IκBα through the ubiquitylation pathway to restrict p50 subunits to the cytoplasm of macrophages, inhibited activation of the NF-κB pathway to downregulate the transcription of specific miRNAs, and reduced miRNA transport into EVs.

β-cell replacement sources for type 1 diabetes: a focus on pancreatic ductal cells

Thorough research on the capacity of human islet transplantation to cure type 1 diabetes led to the achievement of 3- to 5-year-long insulin independence in nearly half of transplanted patients. Yet, translation of this technique to clinical routine is limited by organ shortage and the need for long-term immunosuppression, restricting its use to adults with unstable disease. The production of new bona fide β cells in vitro was thus investigated and finally achieved with human pluripotent stem cells (PSCs). Besides ethical concerns about the use of human embryos, studies are now evaluating the possibility of circumventing the spontaneous tumor formation associated with transplantation of PSCs. These issues fueled the search for cell candidates for β-cell engineering with safe profiles for clinical translation. In vivo studies revealed the regeneration capacity of the exocrine pancreas after injury that depends at least partially on facultative progenitors in the ductal compartment. These stimulated subpopulations of pancreatic ductal cells (PDCs) underwent β-cell transdifferentiation through reactivation of embryonic signaling pathways. In vitro models for expansion and differentiation of purified PDCs toward insulin-producing cells were described using cocktails of growth factors, extracellular-matrix proteins and transcription factor overexpression. In this review, we will describe the latest findings in pancreatic β-cell mass regeneration due to adult ductal progenitor cells. We will further describe recent advances in human PDC transdifferentiation to insulin-producing cells with potential for clinical translational studies.

Cannabinoid receptor 2 agonist attenuates pain related behavior in rats with chronic alcohol/high fat diet induced pancreatitis

Background

Chronic Pancreatitis (CP) is a complex and multifactorial syndrome. Many contributing factors result in development of dysfunctional pain in a significant number of patients. Drugs developed to treat a variety of pain states fall short of providing effective analgesia for patients with chronic pancreatitis, often providing minimal to partial pain relief over time with significant side effects. Recently, availability of selective pharmacological tools has enabled great advances in our knowledge of the role of the cannabinoid receptors in pathophysiology. In particular, cannabinoid receptor 2 (CB2) has emerged as an attractive target for management of chronic pain, as demonstrated in several studies with inflammatory and neuropathic preclinical pain models. In this study, the analgesic efficacy of a novel, highly selective CB2 receptor agonist, LY3038404 HCl, is investigated in a chronic pancreatitis pain model, induced with an alcohol/high fat (AHF) diet.

Results

Rats fed the AHF diet developed visceral pain-like behaviors detectable by week 3 and reached a maximum at week 5 that persists as long as the diet is maintained. Rats with AHF induced chronic pancreatitis were treated with LY3038404 HCl (10 mg/kg, orally, twice a day for 9 days). The treated animals demonstrated significantly alleviated pain related behaviors after 3 days of dosing, including increased paw withdrawal thresholds (PWT), prolonged abdominal withdrawal latencies (ABWL), and decreased nocifensive responses to noxious 44°C hotplate stimuli. Terminal histological analysis of pancreatic tissue sections from the AHF chronic pancreatitis animals demonstrated extensive injury, including a global pancreatic gland degeneration (cellular atrophy), vacuolization (fat deposition), and fibrosis. After the LY3038404 HCl treatment, pancreatic tissue was significantly protected from severe damage and fibrosis. LY3038404 HCl affected neither open field exploratory behaviors nor dark/light box preferences as measures of higher brain and motor functions.

Conclusion

LY3038404 HCl, a potent CB2 receptor agonist, possesses tissue protective and analgesic properties without effects on higher brain function. Thus, activation of CB2 receptors is suggested as a potential therapeutic target for visceral inflammation and pain management.

Pathomorphological analysis of the pancreaticoduodenal organs in experimental pancreonecrosis induced by trypsin injection

Acute experimental pancreatitis induced by injection of trypsin into the pancreatic tissue exhibited characteristics of fulminant hemorrhagic pancreonecrosis (intense exudation of interlobular stroma, massive plasmo- and hemorrhages, foci of acinar cell autolysis involving by the end of day 1 an appreciable portion of the organ with formation of fields of necrosis and hemorrhagic imbibition of the glandular parenchyma, virtually completely without demarcation cellular reaction). Marked microcirculatory disorders and degenerative and necrobiotic changes in the duodenal mucosa and liver reflected the polyorgan nature of the pathological process. This model of hemorrhagic pancreonecrosis corresponded to the most severe forms of this conditions observed clinically.

Possible Involvement of Foxp3(+) Regulatory T Cells in the Development of Immune-Mediated Pancreatitis in MRL/Mp Mice Treated with Polyinosinic:Polycytidylic Acid

Objectives. This study was conducted to clarify whether or not Tregs are involved in the development of immune-mediated pancreatitis in MRL/Mp mice as an AIP (autoimmune pancreatitis) model, in order to understand more clearly the pathogenic mechanism of AIP. Methods. We compared the immunohistochemical features of pancreatic forkhead box P3 (Foxp3) in the administration of poly I:C in MRL/Mp mice and two types of control mice (BALB/c and C57BL/6). As a contrast, we analyzed three mouse models of pancreatitis without autoimmune mechanism (Cerulein-, Ligation-, and Ligation + Cerulein-treated mice). After staining these specimens, we compared the ratios of Foxp3-positive cells to infiltrated mononuclear cells (Foxp3/Mono). Results. Our immunohistochemical study of Foxp3 revealed that the infiltration of Foxp3-positive cells increased in poly I:C-treated MRL/Mp mice. The histopathological score of pancreatitis showed no difference among poly I:C-treated MRL/Mp, Ligation-, and Ligation + Cerulein-treated mice; however, the Foxp3/Mono ratio in poly I:C-treated MRL/Mp mice was significantly increased compared with Ligation- and Ligation + Cerulein-treated mice. Conclusions. MRL/Mp mice treated with poly I:C showed early development of pancreatitis with abundant infiltration of Foxp3-positive cells. There may be a possibility that Tregs are involved in the development of pancreatitis in these mice.

Purified human pancreatic duct cell culture conditions defined by serum-free high-content growth factor screening

The proliferation of pancreatic duct-like CK19+ cells has implications for multiple disease states including pancreatic cancer and diabetes mellitus. The in vitro study of this important cell type has been hampered by their limited expansion compared to fibroblast-like vimentin+ cells that overgrow primary cultures. We aimed to develop a screening platform for duct cell mitogens after depletion of the vimentin+ population. The CD90 cell surface marker was used to remove the vimentin+ cells from islet-depleted human pancreas cell cultures by magnetic-activated cell sorting. Cell sorting decreased CD90+ cell contamination of the cultures from 34±20% to 1.3±0.6%, yielding purified CK19+ cultures with epithelial morphology. A full-factorial experimental design was then applied to test the mitogenic effects of bFGF, EGF, HGF, KGF and VEGF. After 6 days in test conditions, the cells were labelled with BrdU, stained and analyzed by high-throughput imaging. This screening assay confirmed the expected mitogenic effects of bFGF, EGF, HGF and KGF on CK19+ cells and additionally revealed interactions between these factors and VEGF. A serum-free medium containing bFGF, EGF, HGF and KGF led to CK19+ cell expansion comparable to the addition of 10% serum. The methods developed in this work should advance pancreatic cancer and diabetes research by providing effective cell culture and high-throughput screening platforms to study purified primary pancreatic CK19+ cells.

The Id3/E47 axis mediates cell-cycle control in human pancreatic ducts and adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) has a 5-year survival rate of less than 5%, and therapeutic advances have been hampered by gaps in our understanding of cell-cycle control in the adult pancreas. Previously, we reported that basic Helix-Loop-Helix (bHLH) transcription factors regulate cell fate specification in the pancreas. In the present study, we found that a repressor of bHLH activity, Id3, was profoundly upregulated in ductal cells in murine models of pancreatitis and pancreatic intraepithelial neoplasia (PanIN). Id3 was also pervasively expressed in neoplastic lesions in human PDA in situ. We hypothesized that an imbalance in bHLH versus Id activity controlled cell growth in PDA. Consistent with this model, cell-cycle progression in PDA cells was impeded by siRNA-mediated depletion of Id3 or overexpression of the bHLH protein E47. The precursors of human PDA are normally quiescent duct cells which do not proliferate in response to high serum or growth factors. The finding that Id3 was expressed in pancreatitis, as well as PDA, suggested that Id3 might induce cell-cycle entry in ducts. To test this hypothesis, primary human pancreatic duct cells were transduced with an adenovirus-expressing Id3. Remarkably, Id3 expression alone was sufficient to trigger efficient cell-cycle entry, as manifested by expression of the proliferation markers Ki67, phospho-cyclin E, and phospho-histone H3. Collectively, the data establish dysregulation of the Id/bHLH axis as an early and sustained feature of ductal pathogenesis and mark this axis as a potential therapeutic target for intervention in pancreatitis and PDA.

Sox9+ ductal cells are multipotent progenitors throughout development but do not produce new endocrine cells in the normal or injured adult pancreas

One major unresolved question in the field of pancreas biology is whether ductal cells have the ability to generate insulin-producing β-cells. Conclusive examination of this question has been limited by the lack of appropriate tools to efficiently and specifically label ductal cells in vivo. We generated Sox9CreER(T2) mice, which, during adulthood, allow for labeling of an average of 70% of pancreatic ductal cells, including terminal duct/centroacinar cells. Fate-mapping studies of the Sox9(+) domain revealed endocrine and acinar cell neogenesis from Sox9(+) cells throughout embryogenesis. Very small numbers of non-β endocrine cells continue to arise from Sox9(+) cells in early postnatal life, but no endocrine or acinar cell neogenesis from Sox9(+) cells occurs during adulthood. In the adult pancreas, pancreatic injury by partial duct ligation (PDL) has been suggested to induce β-cell regeneration from a transient Ngn3(+) endocrine progenitor cell population. Here, we identify ductal cells as a cell of origin for PDL-induced Ngn3(+) cells, but fail to observe β-cell neogenesis from duct-derived cells. Therefore, although PDL leads to activation of Ngn3 expression in ducts, PDL does not induce appropriate cues to allow for completion of the entire β-cell neogenesis program. In conclusion, although endocrine cells arise from the Sox9(+) ductal domain throughout embryogenesis and the early postnatal period, Sox9(+) ductal cells of the adult pancreas no longer give rise to endocrine cells under both normal conditions and in response to PDL.

Wnt signaling in pancreatic islets

The Wnt signaling pathway is critically important not only for stem cell amplification, differentiation, and migration, but also is important for organogenesis and the development of the body plan. Beta-catenin/TCF7L2-dependent Wnt signaling (the canonical pathway) is involved in pancreas development, islet function, and insulin production and secretion. The glucoincretin hormone glucagon-like peptide-1 and the chemokine stromal cell-derived factor-1 modulate canonical Wnt signaling in beta-cells which is obligatory for their mitogenic and cytoprotective actions. Genome-wide association studies have uncovered 19 gene loci that confer susceptibility for the development of type 2 diabetes. At least 14 of these diabetes risk alleles encode proteins that are implicated in islet growth and functioning. Seven of them are either components of, or known target genes for, Wnt signaling. The transcription factor TCF7L2 is particularly strongly associated with risk for diabetes and appears to be fundamentally important in both canonical Wnt signaling and beta-cell functioning. Experimental loss of TCF7L2 function in islets and polymorphisms in TCF7L2 alleles in humans impair glucose-stimulated insulin secretion, suggesting that perturbations in the Wnt signaling pathway may contribute substantially to the susceptibility for, and pathogenesis of, type 2 diabetes. This review focuses on considerations of the hormonal regulation of Wnt signaling in islets and implications for mutations in components of the Wnt signaling pathway as a source for risk-associated alleles for type 2 diabetes.

The pancreas in human type 1 diabetes

Type 1 diabetes (T1D) is considered a disorder whose pathogenesis is autoimmune in origin, a notion drawn in large part from studies of human pancreata performed as far back as the 1960s. While studies of the genetics, epidemiology, and peripheral immunity in T1D have been subject to widespread analysis over the ensuing decades, efforts to understand the disorder through analysis of human pancreata have been far more limited. We have reviewed the published literature pertaining to the pathology of the human pancreas throughout all stages in the natural history of T1D. This effort uncovered a series of findings that challenge many dogmas ascribed to T1D and revealed data suggesting the marked heterogeneity in terms of its pathology. An improved understanding and appreciation for pancreatic pathology in T1D could lead to improved disease classification, an understanding of why the disorder occurs, and better therapies for disease prevention and management.

The perennial organelle: assembly and disassembly of the primary cilium

Primary cilia contain signaling receptors of diverse classes, and ciliary dysfunction results in a variety of developmental defects. Thus, primary cilia are thought to have an important role in sensing and transducing cellular signals. Although there is clear evidence demonstrating that these organelles are assembled and disassembled dynamically as cells progress through the cell cycle, the mechanisms by which the cell cycle controls the assembly and disassembly of the primary cilium remain poorly understood. In this Commentary, we review the basic cellular mechanisms that underlie the early stages of cilium assembly and discuss how the cell cycle communicates with the ciliation program. A commonly held view is that ciliation occurs exclusively in cells that have exited the cell cycle and entered quiescence or differentiation. However, this concept is at odds with the finding that, during development, many actively proliferating cells require cilia-mediated signaling pathways to instruct their developmental fate. Here, we reassess the quiescence-centric view of ciliation by reviewing historic and current literature. We discuss ample evidence that cilia are in fact present on many proliferating cells, and that a transient peak of ciliation before the G1-S transition might be tightly coupled to entry into the DNA replication phase. Finally, we touch on the relationship between the ciliation and cell-division cycles and the tissue distribution of primary cilia in order to highlight potential roles for the primary cilium in restraining cells from the hyperproliferative state that contributes to cancer.

Beneficial endocrine but adverse exocrine effects of sitagliptin in the human islet amyloid polypeptide transgenic rat model of type 2 diabetes: interactions with metformin

OBJECTIVE

We sought to establish the extent and mechanisms by which sitagliptin and metformin singly and in combination modify islet disease progression in human islet amyloid polypeptide transgenic (HIP) rats, a model for type 2 diabetes.

RESEARCH DESIGN AND METHODS

HIP rats were treated with sitagliptin, metformin, sitagliptin plus metformin, or no drug as controls for 12 weeks. Fasting blood glucose, insulin sensitivity, and beta-cell mass, function, and turnover were measured in each group.

RESULTS

Sitagliptin plus metformin had synergistic effects to preserve beta-cell mass in HIP rats. Metformin more than sitagliptin inhibited beta-cell apoptosis. Metformin enhanced hepatic insulin sensitivity; sitagliptin enhanced extrahepatic insulin sensitivity with a synergistic effect in combination. beta-Cell function was partially preserved by sitagliptin plus metformin. However, sitagliptin treatment was associated with increased pancreatic ductal turnover, ductal metaplasia, and, in one rat, pancreatitis.

CONCLUSIONS

The combination of metformin and sitagliptin had synergistic actions to preserve beta-cell mass and function and enhance insulin sensitivity in the HIP rat model of type 2 diabetes. However, adverse actions of sitagliptin treatment on exocrine pancreas raise concerns that require further evaluation.

Molecular imaging of pancreatic cancer in an animal model using targeted multifunctional nanoparticles

BACKGROUND & AIMS

Identification of a ligand/receptor system that enables functionalized nanoparticles to efficiently target pancreatic cancer holds great promise for the development of novel approaches for the detection and treatment of pancreatic cancer. Urokinase plasminogen activator receptor (uPAR), a cellular receptor that is highly expressed in pancreatic cancer and tumor stromal cells, is an excellent surface molecule for receptor-targeted imaging of pancreatic cancer using multifunctional nanoparticles.

METHODS

The uPAR-targeted dual-modality molecular imaging nanoparticle probe is designed and prepared by conjugating a near-infrared dye-labeled amino-terminal fragment of the receptor binding domain of urokinase plasminogen activator to the surface of functionalized magnetic iron oxide nanoparticles.

RESULTS

We have shown that the systemic delivery of uPAR-targeted nanoparticles leads to their selective accumulation within tumors of orthotopically xenografted human pancreatic cancer in nude mice. The uPAR-targeted nanoparticle probe binds to and is subsequently internalized by uPAR-expressing tumor cells and tumor-associated stromal cells, which facilitates the intratumoral distribution of the nanoparticles and increases the amount and retention of the nanoparticles in a tumor mass. Imaging properties of the nanoparticles enable in vivo optical and magnetic resonance imaging of uPAR-elevated pancreatic cancer lesions.

CONCLUSIONS

Targeting uPAR using biodegradable multifunctional nanoparticles allows for the selective delivery of the nanoparticles into primary and metastatic pancreatic cancer lesions. This novel receptor-targeted nanoparticle is a potential molecular imaging agent for the detection of pancreatic cancer.

Reduced pancreatic volume and beta-cell area in patients with chronic pancreatitis

BACKGROUND & AIMS

Chronic pancreatitis (CP) often leads to the development of diabetes. To understand better this pathogenic mechanism, we investigated whether islet cell area and pancreatic volume are reduced in CP patients, islet cell turnover increases in CP patients, and islet cells are less vulnerable to apoptosis than acinar cells.

METHODS

Pancreatic tissues from 43 patients with CP and 27 controls were examined by immunohistochemistry and quantitative morphometry. Pancreas volume was determined using abdominal computed tomography data.

RESULTS

The pancreatic volumes were 64.9 +/- 4.3 cm(3) in CP patients and 82.3 +/- 6.7 cm(3) in controls (P = .035). beta-cell areas were 0.69% +/- 0.08% in CP patients and 0.97% +/- 0.08% in controls (P = .017), whereas alpha-cell areas did not differ between the groups (P = .47). There were no differences in the frequencies of replication among groups of alpha-cells, beta-cells, duct cells, or acinar cells nor were there differences in numbers of apoptotic alpha-cells or beta-cells between CP patients and controls. However, CP patients had an approximately 10-fold increase in numbers of apoptotic acinar cells compared with controls (P < .0001).

CONCLUSIONS

Pancreatic volume was reduced by 21%, and the area comprising beta-cells was reduced by 29% in patients with CP. The lack of increased beta-cells turnover in CP patients, despite an approximately 10-fold increase in the number of apoptotic acinar cells, suggests that the damage to the pancreas is highly specific for the exocrine compartment and affects the endocrine islets to a lesser extent.

Murine pancreatic duct ligation induces stress kinase activation, acute pancreatitis, and acute lung injury

BACKGROUND

Acute lung injury is a major determinant of outcomes in acute pancreatitis. We evaluated acute lung injury and stress kinase activation in ligation-induced acute pancreatitis in mice.

METHODS

Mice with duct ligation or sham operation were killed after 24 or 48 hours.

RESULTS

In addition to acute pancreatitis, duct ligation was associated with pulmonary morphologic changes indicative of acute lung injury (alveolar septal thickening, congestion, and neutrophil infiltration). Furthermore, immunoblotting showed stress kinase activation in the pancreas and lung after ligation. Although mortality was observed in the ligated group, that is consistent with severe lung injury, it requires further evaluation.

CONCLUSIONS

Bile and pancreatic duct ligation in the mouse is associated with pancreatic and pulmonary stress kinase activation and acute inflammatory changes consistent with early acute pancreatitis and acute lung injury. Our findings are important as acute lung injury increases mortality in clinical acute pancreatitis and stress kinases are established proinflammatory signal transducers.

The Wistar Bonn Kobori rat, a unique animal model for autoimmune pancreatitis with extrapancreatic exocrinopathy

The male Wistar Bonn/Kobori (WBN/Kob) rat is known to be a unique animal model for chronic pancreatitis with widely distributed fibrosis and degeneration of parenchyma because of the infiltration of lymphocytes. In this report, we show that female (but not male) rats develop dacryoadenitis at 3 months of age, and that both male and female WBN/Kob rats develop sialoadenitis, thyroiditis, sclerotic cholangitis and tubulointerstitial nephritis over 18 months of age. The infiltration of CD8+ cells and the deposits of tissue-specific IgG2b were observed in the injured pancreas and lachrymal glands. Furthermore, the number of regulatory T cells (defined as CD4+ Forkhead box P3+ cells) decreased in the periphery of both male and female WBN/Kob rats, suggesting that the onset of these diseases is attributable, at least, to the failure in the maintenance of peripheral immune tolerance. These features show clearly that WBN/Kob rats are a useful animal model for autoimmune pancreatitis and Sjøgren-like syndrome or multi-focal fibrosclerosis in humans. We also show that these autoimmune diseases can be prevented by a newly devised strategy of bone marrow transplantation (BMT) in which bone marrow cells are injected directly into the bone marrow cavity: intrabone marrow-BMT.