Differences in the degree of cerulein-induced chronic pancreatitis in C57BL/6 mouse substrains lead to new insights in identification of potential risk factors in the development of chronic pancreatitis

A rapid protocol for inducing acute pancreatitis in zebrafish models

Acute pancreatitis (AP) is an inflammatory disorder that occurs in the exocrine pancreas associated with tissue injury and necrosis. Experimental models of AP typically involve rodents, such as rats or mice. However, rodents exhibit divergent pathophysiological responses after the establishment of AP between themselves and in comparison, with human. The experiments conducted for this manuscript aimed to standardize a new AP model in zebrafish and validate it. Here, we provide a protocol for inducing AP in zebrafish through intraperitoneal injections of synthetic caerulein. Details are provided for solution preparation, pre-injection procedures, injection technique, and monitoring animal survival. Subsequently, validation was performed through biochemical and histological analyses of pancreatic tissue. The administered dose of caerulein for AP induction was 10 μg/kg applied four times in the intraperitoneal region. The histological validation study demonstrated the presence of necrosis within the first 12 h post-injection, accompanied by an excess of zymogen granules in the extracellular milieu. These observations align with those reported in conventional rodent models. We have standardized and validated the AP model in zebrafish. This model can contribute to preclinical and clinical studies of new drugs for AP treatment. Therefore, this novel model expands the toolkit for exploring faster and more effective preventive and therapeutic strategies for AP.

Identification of Potential Hub Genes Related to Acute Pancreatitis and Chronic Pancreatitis via Integrated Bioinformatics Analysis and In Vitro Analysis

Acute pancreatitis (AP) and chronic pancreatitis (CP) are considered to be two separate pancreatic diseases in most studies, but some clinical retrospective analyses in recent years have found some degree of correlation between the two in actual treatment, however, the exact association is not clear. In this study, bioinformatics analysis was utilized to examine microarray sequencing data in mice, with the aim of elucidating the critical signaling pathways and genes involved in the progression from AP to CP. Differential gene expression analyses on murine transcriptomes were conducted using the R programming language and the R/Bioconductor package. Additionally, gene network analysis was performed using the STRING database to predict correlations among genes in the context of pancreatic diseases. Functional enrichment and gene ontology pathways common to both diseases were identified using Metascape. The hub genes were screened in the cytoscape algorithm, and the mRNA levels of the hub genes were verified in mice pancreatic tissues of AP and CP. Then the drugs corresponding to the hub genes were obtained in the drug-gene relationship. A set of hub genes, including Jun, Cd44, Epcam, Spp1, Anxa2, Hsp90aa1, and Cd9, were identified through analysis, demonstrating their pivotal roles in the progression from AP to CP. Notably, these genes were found to be enriched in the Helper T-cell factor (Th17) signaling pathway. Up-regulation of these genes in both AP and CP mouse models was validated through quantitative real-time polymerase chain reaction (qRT-PCR) results. The significance of the Th17 signaling pathway in the transition from AP to CP was underscored by our findings. Specifically, the essential genes driving this progression were identified as Jun, Cd44, Epcam, Spp1, Anxa2, Hsp90aa1, and Cd9. Crucial insights into the molecular mechanisms underlying pancreatitis progression were provided by this research, offering promising avenues for the development of targeted therapeutic interventions.

Pancreatic Acinar Cells-Derived Sphingosine-1-Phosphate Contributes to Fibrosis of Chronic Pancreatitis via Inducing Autophagy and Activation of Pancreatic Stellate Cells

BACKGROUND & AIMS

Studies have demonstrated that activated pancreatic stellate cells (PSCs) play a crucial role in pancreatic fibrogenesis in chronic pancreatitis (CP); however, the precise mechanism for PSCs activation has not been fully elucidated. We analyzed the role of injured pancreatic acinar cells (iPACs) in the activation of PSCs of CP.

METHODS

Sphingosine kinase 1 (SPHK1)/sphingosine-1-phosphate (S1P) signaling was evaluated in experimental CP induced by cerulein injection or pancreatic duct ligation, as well as in PACs injured by cholecystokinin. The activation of PSCs and pancreatic fibrosis in CP samples was evaluated by immunohistochemical and immunofluorescence analyses. In vitro coculture assay of iPACs and PSCs was created to evaluate the effect of the SPHK1/S1P pathway and S1P receptor 2 (SIPR2) on autophagy and activation of PSCs. The pathogenesis of CP was assessed in SPHK1-/- mice or PACs-specific SPHK1-knockdown mice with recombinant adeno-associated virus serotypes 9-SPHK1-knockdown, as well as in mice treated with inhibitor of SPHK1 and S1P receptor 2 (S1PR2).

RESULTS

SPHK1/S1P was remarkably increased in iPACs and acinar cells in pancreatic tissues of CP mice. Meanwhile, the pathogenesis, fibrosis, and PSCs activation of CP was significantly prevented in SPHK1-/- mice and recombinant adeno-associated virus serotypes 9-SPHK1-knockdown mice. Meanwhile, iPACs obviously activated PSCs, which was prevented by SPHK1 knockdown in iPACs. Moreover, iPACs-derived S1P specifically combined to S1PR2 of PSCs, by which modulated 5' adenosine monophosphate-activated protein kinase/mechanistic target of rapamycin pathway and consequently induced autophagy and activation of PSCs. Furthermore, hypoxia-inducible factor 1-α and -2α promoted SPHK1 transcription of PACs under hypoxia conditions, which is a distinct characteristic of the CP microenvironment. Coincidently, inhibition of SPHK1 and S1PR2 activity with inhibitor PF-543 and JTE-013 obviously impeded pancreatic fibrogenesis of CP mice.

CONCLUSIONS

The activated SPHK1/S1P pathway in iPACs induces autophagy and activation of PSCs by regulating the S1PR2/5' adenosine monophosphate-activated protein kinase/mammalian target of rapamycin pathway, which promotes fibrogenesis of CP. The hypoxia microenvironment might contribute to the cross talk between PACs and PSCs in pathogenesis of CP.

Krüppel-like Factor 5 Plays an Important Role in the Pathogenesis of Chronic Pancreatitis

Chronic pancreatitis results in the formation of pancreatic intraepithelial neoplasia (PanIN) and poses a risk of developing pancreatic cancer. Our previous study demonstrated that Krüppel-like factor 5 (KLF5) is necessary for forming acinar-to-ductal metaplasia (ADM) in acute pancreatitis. Here, we investigated the role of KLF5 in response to chronic injury in the pancreas. Human tissues originating from chronic pancreatitis patients showed increased levels of epithelial KLF5. An inducible genetic model combining the deletion of Klf5 and the activation of KrasG12D mutant expression in pancreatic acinar cells together with chemically induced chronic pancreatitis was used. The chronic injury resulted in increased levels of KLF5 in both control and KrasG12D mutant mice. Furthermore, it led to numerous ADM and PanIN lesions and extensive fibrosis in the KRAS mutant mice. In contrast, pancreata with Klf5 loss (with or without KrasG12D) failed to develop ADM, PanIN, or significant fibrosis. Furthermore, the deletion of Klf5 reduced the expression level of cytokines and fibrotic components such as Il1b, Il6, Tnf, Tgfb1, Timp1, and Mmp9. Notably, using ChIP-PCR, we showed that KLF5 binds directly to the promoters of Il1b, Il6, and Tgfb1 genes. In summary, the inactivation of Klf5 inhibits ADM and PanIN formation and the development of pancreatic fibrosis.

Gut microbiota affects pancreatic fibrotic progression through immune modulation in chronic pancreatitis

Chronic pancreatitis (CP) is characterized by chronic progressive pancreatic inflammation, which leads to the permanent damage of exocrine and endocrine cells. CP causes irreversible morphological and functional changes, and the clinical manifestations includes abdomen pain, steatorrhea and diabetes. CP induces changes in the composition of gut microbiota that could be used as potential biomarkers for pancreatic fibrosis evaluation. Gut microbiota has emerged as key regulator of immunomodulation and gut microbiota-induced immune activation has not been explored in CP. In current study, we profiled gut microbial signatures in mouse CP model, and found that higher proportion of Streptomyces, Turicibacter, Methylobacterium, Enterococcus and Candidatus_Paenicardiniummore were positively associated with the occurrence of pancreatic fibrosis. We then identified increased CD3⁺T cells and macrophage infiltration in mouse and human CP tissues by transcriptome sequencing data from GEO database. Subsequently, we demonstrated that fecal microbiota transplantation (FMT) from CP mouse (FMT-CP) exacerbated pancreatic fibrosis by increasing CD4⁺T cells and macrophage infiltration compared to fecal samples obtained from healthy mouse donor (FMT-HC). Our study describes the link between gut microbiota dysbiosis and immune activation in pancreatic fibrotic progression, and highlights the potential therapeutic roles of FMT and CP treatment.

Metabolic differences and differentially expressed genes between C57BL/6J and C57BL/6N mice substrains

C57BL/6J (B6J) and C57BL/6N (B6N) mice are the most frequently used substrains in C57BL/6 (B6) inbred mice, serving as physiological models for in vivo studies and as background strains to build transgenic mice. However, the differences in metabolic phenotypes between B6J and B6N mice are not coherent, and genotypic differences in metabolically important tissues have not been well studied. The phenotypic differences between B6J and B6N substrains have often been attributed to the role of the nicotinamide nucleotide transhydrogenase (Nnt) gene, whereby B6J has a spontaneous missense mutation of Nnt. Nevertheless, phenotypic differences between the two cannot be explained by Nnt mutations alone, especially in metabolic traits. Therefore, we aimed to investigate the genetic cause of the phenotypic differences between B6J and B6N mice. Determining consistent genetic differences across multiple tissues involved in metabolic traits such as subcutaneous and visceral white adipose tissues, brown adipose tissue, skeletal muscle, liver, hypothalamus, and hippocampus, may help explain phenotypic differences in metabolism between the two substrains. We report candidate genes along with comparative data on body weight, tissue weight, blood components involved in metabolism, and energy balance of B6J and B6N mice. Insulin degrading enzyme, adenylosuccinate synthase 2, and ectonucleotide triphosphate diphosphohydrolase 4 were highly expressed in B6J mice compared with those in B6N mice, and Nnt, WD repeat and FYVE domain containing 1, and dynein light chain Tctex-type 1 were less expressed in B6J mice compared with those in B6N mice in all seven tissues. Considering the extremely wide use of both substrains and their critical importance in generating transgenic and knock-out models, these findings guide future research across several interrelated fields.

Keratin 8 Is an Inflammation-Induced and Prognosis-Related Marker for Pancreatic Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the highest-grade malignancies in the world. More effective biomarkers and treatment plans are necessary to improve the diagnosis rate and clinical outcome. The oncogenesis of PDAC is influenced by several factors, including chronic pancreatitis (CP). Keratin 8 (KRT8) is an important member of the keratin protein family and plays a role in regulating the cellular response to stress stimuli and mediating inflammatory reactions. However, the role of KRT8 in pancreatitis and PDAC is still poorly understood. Here we assessed the differentially expressed genes (DEGs) by bioinformatic methods with expression profiles available online for a caerulein-induced mouse model and human PDAC tissue. The prognostic value was evaluated by Kaplan–Meier analysis and Cox regression analysis. The diagnostic value was evaluated by Receiver Operating Characteristic analysis (ROC). The function of the genes was predicted by protein-protein interaction analysis, correlation analysis, and GO analysis. The conclusion was further validated in rat pancreatitis model, human tissue, and PDAC cell lines, including immunohistochemical staining (IHC), CCK-8 assay, wound healing assay, and flow cytometry. KRT8 was found to be upregulated in murine pancreatitis tissue, human CP tissue, and human PDAC tissue. High expression of KRT8 had a negative impact on the prognosis of PDAC patients. KRT8 was predicted to be involved in the regulation of the migration and viability of PDAC cells, which was validated in PDAC cell lines. Knockdown of KRT8 impaired the migration and proliferation and induced apoptosis in PDAC cell lines. In conclusion, keratin 8 is an inflammation-induced molecule and could serve as a diagnostic and prognostic marker for PDAC patients. More studies are needed for further validation from the perspective of precision and individualized medicine.

psupertime: supervised pseudotime analysis for time-series single-cell RNA-seq data

Motivation

Improvements in single-cell RNA-seq technologies mean that studies measuring multiple experimental conditions, such as time series, have become more common. At present, few computational methods exist to infer time series-specific transcriptome changes, and such studies have therefore typically used unsupervised pseudotime methods. While these methods identify cell subpopulations and the transitions between them, they are not appropriate for identifying the genes that vary coherently along the time series. In addition, the orderings they estimate are based only on the major sources of variation in the data, which may not correspond to the processes related to the time labels.

Results

We introduce psupertime, a supervised pseudotime approach based on a regression model, which explicitly uses time-series labels as input. It identifies genes that vary coherently along a time series, in addition to pseudotime values for individual cells, and a classifier that can be used to estimate labels for new data with unknown or differing labels. We show that psupertime outperforms benchmark classifiers in terms of identifying time-varying genes and provides better individual cell orderings than popular unsupervised pseudotime techniques. psupertime is applicable to any single-cell RNA-seq dataset with sequential labels (e.g. principally time series but also drug dosage and disease progression), derived from either experimental design and provides a fast, interpretable tool for targeted identification of genes varying along with specific biological processes.

Availability and implementation

R package available at github.com/wmacnair/psupertime and code for results reproduction at github.com/wmacnair/psupplementary.

Supplementary information

Supplementary data are available at Bioinformatics online.

Variants in the pancreatic CUB and zona pellucida-like domains 1 (CUZD1) gene in early-onset chronic pancreatitis - A possible new susceptibility gene

OBJECTIVE

Non-alcoholic chronic pancreatitis (NACP) frequently develops in the setting of genetic susceptibility associated with alterations in genes that are highly expressed in the pancreas. However, the genetic basis of NACP remains unresolved in a significant number of patients warranting a search for further risk genes.

DESIGN

We analyzed CUZD1, which encodes the CUB and zona pellucida-like domains 1 protein that is found in high levels in pancreatic acinar cells. We sequenced the coding region in 1163 European patients and 2018 European controls. In addition, we analyzed 297 patients and 1070 controls from Japan. We analyzed secretion of wild-type and mutant CUZD1 from transfected cells using Western blotting.

RESULTS

In the European cohort, we detected 30 non-synonymous variants. Using different prediction tools (SIFT, CADD, PROVEAN, PredictSNP) or the combination of these tools, we found accumulation of predicted deleterious variants in patients (p-value range 0.002-0.013; OR range 3.1-5.2). No association was found in the Japanese cohort, in which 13 non-synonymous variants were detected. Functional studies revealed >50% reduced secretion of 7 variants, however, these variants were not significantly enriched in European CP patients.

CONCLUSION

Our data indicate that CUZD1 might be a novel susceptibility gene for NACP. How these variants predispose to pancreatitis remains to be elucidated.

Mitochondrial NAD(P)+ Transhydrogenase: From Molecular Features to Physiology and Disease

Significance: Proton-translocating NAD(P)⁺ transhydrogenase, also known as nicotinamide nucleotide transhydrogenase (NNT), catalyzes a reversible reaction coupling the protonmotive force across the inner mitochondrial membrane and hydride (H^-, a proton plus two electrons) transfer between the mitochondrial pools of NAD(H) and NADP(H). The forward NNT reaction is a source of NADPH in the mitochondrial matrix, fueling antioxidant and biosynthetic pathways with reductive potential. Despite the greater emphasis given to the net forward reaction, the reverse NNT reaction that oxidizes NADPH also occurs in physiological and pathological conditions. Recent Advances: NNT (dys)function has been linked to various metabolic pathways and disease phenotypes. Most of these findings have been based on spontaneous loss-of-function Nnt mutations found in the C57BL/6J mouse strain (Nnt^C57BL/6J mutation) and disease-causing Nnt mutations in humans. The present review focuses on recent advances based on the mouse Nnt^C57BL/6J mutation. Critical Issues: Most studies associating NNT function with disease phenotypes have been based on comparisons between different strains of inbred mice (with or without the Nnt^C57BL/6J mutation), which creates uncertainties over the actual contribution of NNT in the context of other potential genetic modifiers. Future Directions: Future research might contribute to understanding the role of NNT in pathological conditions and elucidate how NNT regulates physiological signaling through its forward and reverse reactions. The importance of NNT in redox balance and tumor cell proliferation makes it a potential target of new therapeutic strategies for oxidative-stress-mediated diseases and cancer. Antioxid. Redox Signal. 36, 864-884.

Docking Protein p130Cas Regulates Acinar to Ductal Metaplasia During Pancreatic Adenocarcinoma Development and Pancreatitis

BACKGROUND & AIMS

Acinar to ductal metaplasia is the prerequisite for the initiation of Kras-driven pancreatic ductal adenocarcinoma (PDAC), and candidate genes regulating this process are emerging from genome-wide association studies. The adaptor protein p130Cas emerged as a potential PDAC susceptibility gene and a Kras-synthetic lethal interactor in pancreatic cell lines; however, its role in PDAC development has remained largely unknown.

METHODS

Human PDAC samples and murine KrasG12D-dependent pancreatic cancer models of increasing aggressiveness were used. p130Cas was conditionally ablated in pancreatic cancer models to investigate its role during Kras-induced tumorigenesis.

RESULTS

We found that high expression of p130Cas is frequently detected in PDAC and correlates with higher histologic grade and poor prognosis. In a model of Kras-driven PDAC, loss of p130Cas inhibits tumor development and potently extends median survival. Deletion of p130Cas suppresses acinar-derived tumorigenesis and progression by means of repressing PI3K-AKT signaling, even in the presence of a worsening condition like pancreatitis.

CONCLUSIONS

Our observations finally demonstrated that p130Cas acts downstream of Kras to boost the PI3K activity required for acinar to ductal metaplasia and subsequent tumor initiation. This demonstrates an unexpected driving role of p130Cas downstream of Kras through PI3K/AKT, thus indicating a rational therapeutic strategy of targeting the PI3K pathway in tumors with high expression of p130Cas.

Targeting Endoplasmic Reticulum Stress as an Effective Treatment for Alcoholic Pancreatitis

Pancreatitis and alcoholic pancreatitis are serious health concerns with an urgent need for effective treatment strategies. Alcohol is a known etiological factor for pancreatitis, including acute pancreatitis (AP) and chronic pancreatitis (CP). Excessive alcohol consumption induces many pathological stress responses; of particular note is endoplasmic reticulum (ER) stress and adaptive unfolded protein response (UPR). ER stress results from the accumulation of unfolded/misfolded protein in the ER and is implicated in the pathogenesis of alcoholic pancreatitis. Here, we summarize the possible mechanisms by which ER stress contributes to alcoholic pancreatitis. We also discuss potential approaches targeting ER stress and UPR in developing novel therapeutic strategies for the disease.

Spermine-Related DNA Hypermethylation and Elevated Expression of Genes for Collagen Formation are Susceptible Factors for Chemotherapy-Induced Hand-Foot Syndrome in Chinese Colorectal Cancer Patients

Hand-foot syndrome (HFS) is a common capecitabine-based chemotherapy-related adverse event (CRAE) in patients with colorectal cancer (CRC). It is of great significance to comprehensively identify susceptible factors for HFS, and further to elucidate the biomolecular mechanism of HFS susceptibility. We performed an untargeted multi-omics analysis integrating DNA methylation, transcriptome, and metabolome data of 63 Chinese CRC patients who had complete CRAE records during capecitabine-based chemotherapy. We found that the metabolome changes for each of matched plasma, urine, and normal colorectal tissue (CRT) in relation to HFS were characterized by chronic tissue damage, which was indicated by reduced nucleotide salvage, elevated spermine level, and increased production of endogenous cytotoxic metabolites. HFS-related transcriptome changes of CRT showed an overall suppressed inflammation profile but increased M2 macrophage polarization. HFS-related DNA methylation of CRT presented gene-specific hypermethylation on genes mainly for collagen formation. The hypermethylation was accumulated in the opensea and shore regions, which elicited a positive effect on gene expression. Additionally, we developed and validated models combining relevant biomarkers showing reasonably good discrimination performance with the area under the receiver operating characteristic curve values from 0.833 to 0.955. Our results demonstrated that the multi-omics variations associated with a profibrotic phenotype were closely related to HFS susceptibility. HFS-related biomolecular variations in CRT contributed more to the relevant biomolecular mechanism of HFS than in plasma and urine. Spermine-related DNA hypermethylation and elevated expression of genes for collagen formation were closely associated with HFS susceptibility. These findings provided new insights into the susceptible factors for chemotherapy-induced HFS, which can promote the implementation of individualized treatment against HFS.

The tweety Gene Family: From Embryo to Disease

The tweety genes encode gated chloride channels that are found in animals, plants, and even simple eukaryotes, signifying their deep evolutionary origin. In vertebrates, the tweety gene family is highly conserved and consists of three members—ttyh1, ttyh2, and ttyh3—that are important for the regulation of cell volume. While research has elucidated potential physiological functions of ttyh1 in neural stem cell maintenance, proliferation, and filopodia formation during neural development, the roles of ttyh2 and ttyh3 are less characterized, though their expression patterns during embryonic and fetal development suggest potential roles in the development of a wide range of tissues including a role in the immune system in response to pathogen-associated molecules. Additionally, members of the tweety gene family have been implicated in various pathologies including cancers, particularly pediatric brain tumors, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Here, we review the current state of research using information from published articles and open-source databases on the tweety gene family with regard to its structure, evolution, expression during development and adulthood, biochemical and cellular functions, and role in human disease. We also identify promising areas for further research to advance our understanding of this important, yet still understudied, family of genes.

Substrains matter in phenotyping of C57BL/6 mice

The inbred mouse strain C57BL/6 has been widely used as a background strain for spontaneous and induced mutations. Developed in the 1930s, the C57BL/6 strain diverged into two major groups in the 1950s, namely, C57BL/6J and C57BL/6N, and more than 20 substrains have been established from them worldwide. We previously reported genetic differences among C57BL/6 substrains in 2009 and 2015. Since then, dozens of reports have been published on phenotypic differences in behavioral, neurological, cardiovascular, and metabolic traits. Substrains need to be chosen according to the purpose of the study because phenotypic differences might affect the experimental results. In this paper, we review recent reports of phenotypic and genetic differences among C57BL/6 substrains, focus our attention on the proper use of C57BL/6 and other inbred strains in the era of genome editing, and provide the life science research community wider knowledge about this subject.

Different characteristics of chronic dibutyltin dichloride-induced pancreatitis and cholangitis in mouse and rat

BACKGROUND

Current animal models of chronic pancreatitis (CP) often provide only limited pathophysiological insights since they incompletely reflect the human disease. CP induced by injection of dibutyltin dichloride (DBTC-pancreatitis) shares with human CP the important feature of extended fibrosis and would be an even more attractive model if it could be transferred from rats to mice, as recently suggested in the context of combined ethanol and DBTC application. This study aimed to evaluate the effects of DBTC in pancreas and liver of C57BL/6 mice, a strain commonly used to engineer genetic mouse models.

METHODS

C57BL/6 mice and Lewis rats were exposed to variable doses of DBTC. After an investigation period of up to 4 weeks, laboratory findings and histopathological changes of pancreas and liver were evaluated.

RESULTS

Chronic DBTC-pancreatitis in rats was characterized by acinar cell damage, ductal changes, fibrosis, and inflammatory cell infiltrates. Mice treated with DBTC at 6-8 mg/kg body weight, the standard doses in rats, showed transient increases of lipase activities but no morphological signs of chronic DBTC-pancreatitis 4 weeks after injection of the drug. Increased doses of 10-12 mg/kg DBTC were intolerable due to their high toxicity. In contrast, mice and rats presented with a similar histopathology of the liver that can be characterized as a chronic-proliferative DBTC-cholangitis with predominating damage and proliferation of the small bile ducts as well as secondary portal inflammatory cell infiltrates and a beginning portal fibrosis.

CONCLUSIONS

The DBTC-model cannot be transferred from rats to C57BL/6 mice with respect to chronic DBTC-pancreatitis, but might be of interest to study DBTC-cholangitis in both species.

Loss of RE-1 silencing transcription factor accelerates exocrine damage from pancreatic injury

Regulation of pancreas plasticity is critical for preventing injury and promoting regeneration upon tissue damage. The intricate process of pancreatic differentiation is governed by an orchestrated network of positive and negative transcription factors for appropriate gene expression. While the transcriptional repressor REST is well characterized as a silencer of neuronal genes in non-neuronal cells, the role of REST in regulating exocrine pancreas cell identity remains largely unexplored. Rest expression is increased upon injury in the mouse pancreas, such as induced acute and chronic pancreatitis and ductal adenocarcinoma. At the cellular level, Rest expression is lower in mature acinar cells compared with pancreas progenitor and ductal cells. To investigate the role of REST activity in pancreatic transdifferentiation and homeostasis, we developed a novel mouse model (Cre/REST^fl/fl) with conditional knockout (KO) of Rest expression within pancreas cells. The high Cre-mediated excision efficiency of Rest exon two KO caused decreased Rest expression and activity within the pancreas. Short-term organoid cultures of pancreatic acini to undergo acinar-to-ductal metaplasia (ADM) showed that loss of REST impedes induced ADM, while overexpression of REST increases ADM. Interestingly, REST ablation accelerated acute pancreatitis in mice treated with the cholecystokinin analog caerulein, as indicated by cellular morphology, elevated serum amylase levels and pancreatic edema. Furthermore, Cre/REST^fl/fl mice were more sensitive to acute pancreatitis injury and displayed augmented tissue damage and cellular lesions. These results suggest REST has a novel protective role against pancreatic tissue damage by acting as a regulator of exocrine cell identity.

Tuft Cell Formation Reflects Epithelial Plasticity in Pancreatic Injury: Implications for Modeling Human Pancreatitis

Chronic pancreatitis, a known risk factor for the development of pancreatic ductal adenocarcinoma (PDA), is a serious, widespread medical condition characterized by inflammation, fibrosis, and acinar to ductal metaplasia (ADM). ADM is a cell type transdifferentiation event where pancreatic acinar cells become ductal-like under conditions of injury or oncogenic mutation. Here, we show that chronic pancreatitis and ADM in genetically wild type mice results in the formation of a significant population of chemosensory tuft cells. Transcriptomic analyses of pancreatitis tuft cells identify expression of inflammatory mediators, consistent with a role for tuft cells in injury progression and/or resolution. Though similar to tuft cell populations in other organs and disease systems, we identified a number of key differences that suggest context-specific tuft cell functions. We evaluated seven different mouse strains for tuft cell formation in response to chronic injury and identified significant heterogeneity reflecting varying proclivity for epithelial plasticity between strains. These results have interesting implications in the role of epithelial plasticity and heterogeneity in pancreatitis and highlight the importance of mouse strain selection when modeling human disease.

Docosahexaenoic Acid Inhibits Expression of Fibrotic Mediators in Mice With Chronic Pancreatitis

Background

Chronic pancreatitis (CP) is an irreversible progressive disease that destroys exocrine parenchyma, which are replaced by fibrous tissue. As pancreatic fibrosis is a key feature of CP, reducing fibrotic protein content in the pancreas is crucial for preventing CP. Studies suggest that NF-κB facilitates the expression of fibrotic mediators in pancreas and protein kinase C-δ (PKC-δ) regulates NF-κB activation in stimulated pancreatic acinar cells. Docosahexaenoic acid (DHA) is an omega-3 fatty acid having anti-inflammatory and anti-fibrotic effects. It has been shown to inhibit NF-κB activity in cerulein-stimulated pancreatic acinar cells which is a cellular model of CP. In the present study, we investigated if DHA inhibits expression of fibrotic mediators by reducing PKC-δ and NF-κB expression in mouse pancreatic tissues with CP.

Methods

For six weeks, mice were weekly induced for acute pancreatitis to develop CP. Furthermore, acute pancreatitis was induced by hourly intraperitoneal injections of cerulein (50 μg/kg × 7). Mice were administered DHA (10 μM) via drinking water before and after CP induction.

Results

Cerulein-induced pancreatic damages like decreased pancreatic weight/total body weight, leukocyte infiltration, necrosis of acinar cells, and vacuolization were found to be inhibited by DHA. Additionally, DHA inhibited cerulein-induced fibrotic mediators like alpha-smooth muscle actin and fibronectin in pancreas. DHA reduced expression of PKC-δ and NF-κB p65 in pancreatic tissues of cerulein-treated mice.

Conclusions

DHA may be beneficial in preventing CP by suppressing pancreatic expression of fibrotic mediators.

Pancreatitis is an FGF21-deficient state that is corrected by replacement therapy

The exocrine pancreas expresses the highest concentrations of fibroblast growth factor 21 (FGF21) in the body, where it maintains acinar cell proteostasis. Here, we showed in both mice and humans that acute and chronic pancreatitis is associated with a loss of FGF21 expression due to activation of the integrated stress response (ISR) pathway. Mechanistically, we found that activation of the ISR in cultured acinar cells and mouse pancreata induced the expression of ATF3, a transcriptional repressor that directly bound to specific sites on the Fgf21 promoter and resulted in loss of FGF21 expression. These ATF3 binding sites are conserved in the human FGF21 promoter. Consistent with the mouse studies, we also observed the reciprocal expression of ATF3 and FGF21 in the pancreata of human patients with pancreatitis. Using three different mouse models of pancreatitis, we showed that pharmacologic replacement of FGF21 mitigated the ISR and resolved pancreatitis. Likewise, inhibition of the ISR with an inhibitor of the PKR-like endoplasmic reticulum kinase (PERK) also restored FGF21 expression and alleviated pancreatitis. These findings highlight the importance of FGF21 in preserving exocrine pancreas function and suggest its therapeutic use for prevention and treatment of pancreatitis.

Elastase 3B mutation links to familial pancreatitis with diabetes and pancreatic adenocarcinoma

While improvements in genetic analysis have greatly enhanced our understanding of the mechanisms behind pancreatitis, it continues to afflict many families for whom the hereditary factors remain unknown. Recent evaluation of a patient with a strong family history of pancreatitis sparked us to reexamine a large kindred originally reported over 50 years ago with an autosomal dominant inheritance pattern of chronic pancreatitis, diabetes and pancreatic adenocarcinoma. Whole exome sequencing analysis identified a rare missense mutation in the gene encoding pancreas-specific protease Elastase 3B (CELA3B) that cosegregates with disease. Studies of the mutant protein in vitro, in cell lines and in CRISPR-Cas9 engineered mice indicate that this mutation causes translational upregulation of CELA3B, which upon secretion and activation by trypsin leads to uncontrolled proteolysis and recurrent pancreatitis. Although lesions in several other pancreatitic proteases have been previously linked to hereditary pancreatitis, this is the first known instance of a mutation in CELA3B and a defect in translational control contributing to this disease.

Animal Models: Challenges and Opportunities to Determine Optimal Experimental Models of Pancreatitis and Pancreatic Cancer

At the 2018 PancreasFest meeting, experts participating in basic research met to discuss the plethora of available animal models for studying exocrine pancreatic disease. In particular, the discussion focused on the challenges currently facing the field and potential solutions. That meeting culminated in this review, which describes the advantages and limitations of both common and infrequently used models of exocrine pancreatic disease, namely, pancreatitis and exocrine pancreatic cancer. The objective is to provide a comprehensive description of the available models but also to provide investigators with guidance in the application of these models to investigate both environmental and genetic contributions to exocrine pancreatic disease. The content covers both nongenic and genetically engineered models across multiple species (large and small). Recommendations for choosing the appropriate model as well as how to conduct and present results are provided.

Cerulein-induced chronic pancreatitis in Swiss albino mice: An improved short-term model for pharmacological screening

There is a need for short-term, reliable and reproducible animal model of chronic pancreatitis (CP) in small animals like mice. This study was aimed to establish the 9 exposures of cerulein-induced CP in mice. Repeated intraperitoneal cerulein injections were performed at 6 consecutive doses (50 μg/kg)/day, 3 days a week for 3 weeks to induce chronic pancreatitis in Swiss albino mice. The severity of damage was assessed by biochemical assays and histopathology. The expression of pro-inflammatory cytokine and fibrotic proteins was assessed by IHC and western blotting. The cerulein treated mice showed significantly elevated plasma amylase (p < .0285) and lipase levels (p < .0022) and resulted in significantly increased pancreatic oxidative (p < .0022) and nitrosative (p < .0022) stress. The hydroxyproline levels were 3.06 fold increased in the cerulein treated mice. The expressions of fibrotic cytokine TGF-β1 by 1.8 folds and pro-inflammatory cytokines TNF-α by 2.3 fold, IL-6 by 2.2 fold and IL-1β by 3.7 fold were markedly increased in cerulein treated mice. The histological evaluations indicated increased inflammatory cells infiltration and deposition of collagen. Moreover, the expression of fibrotic markers such as α-SMA increased by 2.5 folds (p < .00014), collagen1a by 1.3 folds (p < .0258) and fibronectin by 3.5 folds (p < .00014) were significantly increased. Our study demonstrates the superiority of 9 exposures of cerulein-induced CP model in mice with the reduction of duration, cerulein exposure, more economical and mortality rate of mice over the available models. Therefore, our model may be suitable to evaluate the pharmacological effects of new drugs in chronic pancreatitis.

An Inhibitor of Arginine-Glycine-Aspartate-Binding Integrins Reverses Fibrosis in a Mouse Model of Nonalcoholic Steatohepatitis

The presence and stage of liver fibrosis in patients with nonalcoholic steatohepatitis (NASH) is strongly associated with mortality. Thus, both preventing and reversing fibrosis are critically important approaches to prevent death or the need for liver transplantation from NASH. Recently, fibrosis in several mouse models of organ injury was shown to be prevented and reversed with the potent small molecule, arginine‐glycine‐aspartic acid tripeptide (RGD)‐binding, integrin antagonist (3S)‐3‐(3‐bromo‐5‐(tert‐butyl)phenyl)‐3‐(2‐(3‐hydroxy‐5‐((5‐hydroxy‐1,4,5,6‐tetrahydropyrimidin‐2‐yl)amino)benzamido)acetamido)propanoic acid (Center for World Health and Medicine [CWHM]‐12). We hypothesized that RGD‐binding integrins may play an important role in fibrosis progression in NASH. We assessed the efficacy of CWHM‐12 in a choline deficient, amino‐acid defined, high‐fat diet (CDAHFD) mouse model of NASH. Mice were kept on the CDAHFD or a control diet for 10 weeks, and CWHM‐12 was delivered by continuous infusion for the final 4 weeks. The parameters of NASH and liver fibrosis were evaluated before and after drug treatment. Hepatic steatosis, liver injury, and inflammation were significantly induced by the CDAHFD at week 6 and did not change by week 10. Hepatic profibrogenic gene expression was induced by the CDAHFD at week 6, further increased at week 10, and decreased by CWHM‐12. Fibrosis measured by analysis of liver collagen was reduced by CWHM‐12 to levels significantly less than found at 6 weeks, demonstrating the possibility of reversing already established fibrosis despite ongoing injury. Demonstrated mechanisms of the antifibrotic effect of CWHM‐12 included loss of activated hepatic stellate cells through apoptosis and suppression of hepatic profibrotic signal transduction by transforming growth factor β. Conclusion: RGD‐binding integrins may be critical in the development of fibrosis in NASH and may represent potential targets for treating patients with NASH to reverse advanced liver fibrosis.

Recombinant human hepatocyte growth factor provides protective effects in cerulein-induced acute pancreatitis in mice

Acute pancreatitis is a multifactorial disease associated with profound changes of the pancreas induced by release of digestive enzymes that lead to increase in proinflammatory cytokine production, excessive tissue necrosis, edema, and bleeding. Elevated levels of hepatocyte growth factor (HGF) and its receptor c-Met have been observed in different chronic and acute pancreatic diseases including experimental models of acute pancreatitis. In the present study, we investigated the protective effects induced by the recombinant human HGF in a mouse model of cerulein-induced acute pancreatitis. Pancreatitis was induced by 8 hourly administrations of supramaximal cerulein injections (50 µg/kg, ip). HGF treatment (20 µg/kg, iv), significantly attenuated lipase content and amylase activity in serum as well as the degree inflammation and edema overall leading to less severe histologic changes such as necrosis, induced by cerulein. Protective effects of HGF were associated with activation of pro-survival pathways such as Akt, Erk1/2, and Nrf2 and increase in executor survival-related proteins and decrease in pro-apoptotic proteins. In addition, ROS content and lipid peroxidation were diminished, and glutathione synthesis increased in pancreas. Systemic protection was observed by lung histology. In conclusion, our data indicate that HGF exerts an Nrf2 and glutathione-mediated protective effect on acute pancreatitis reflected by a reduction in inflammation, edema, and oxidative stress.

Broad spectrum proteomics analysis of the inferior colliculus following acute hydrogen sulfide exposure

Acute exposure to high concentrations of H₂S causes severe brain injury and long-term neurological disorders, but the mechanisms involved are not known. To better understand the cellular and molecular mechanisms involved in acute H₂S-induced neurodegeneration we used a broad-spectrum proteomic analysis approach to identify key molecules and molecular pathways involved in the pathogenesis of acute H₂S-induced neurotoxicity and neurodegeneration. Mice were subjected to acute inhalation exposure of up to750 ppm of H₂S. H₂S induced behavioral deficits and severe lesions including hemorrhage in the inferior colliculus (IC). The IC was microdissected for proteomic analysis. Tandem mass tags (TMT) liquid chromatography mass spectrometry (LC-MS/MS)-based quantitative proteomics was applied for protein identification and quantitation. LC-MS/MS identified 598, 562, and 546 altered proteomic changes at 2 h, and on days 2 and 4 post-H₂S exposure, respectively. Of these, 77 proteomic changes were statistically significant at any of the 3 time points. Mass spectrometry data were subjected to Perseus 1.5.5.3 statistical analysis, and gene ontology heat map clustering. Expressions of several key molecules were verified to confirm H₂S-dependent proteomics changes. Webgestalt pathway overrepresentation enrichment analysis with Panther engine revealed H₂S exposure disrupted several biological processes including metabotropic glutamate receptor group 1 and inflammation mediated by chemokine and cytokine signaling pathways among others. Further analysis showed that energy metabolism, integrity of blood-brain barrier, hypoxic, and oxidative stress signaling pathways were also implicated. Collectively, this broad-spectrum proteomics data has provided important clues to follow up in future studies to further elucidate mechanisms of H₂S-induced neurotoxicity.

Endothelium-induced three-dimensional invasion of heterogeneous glioma initiating cells in a microfluidic coculture platform

Glioblastoma (GBM) is a highly invasive primary brain tumor that displays cellular heterogeneity, which is composed of glioma initiating cells (GICs) and their differentiated progeny. GICs play an important role in driving aggressive invasion. In particular, the interaction between GICs and blood vessels is critical because blood vessels are known to serve as routes for the invasion of GICs. However, the effect of endothelial cells on the three-dimensional (3D) invasion process of GICs as well as the spatial relationship between GICs and their differentiated progeny remains unclear. Here, we utilized a microfluidic device to recapitulate the 3D brain tumor microenvironments constituted by human umbilical vein endothelial cells (HUVECs) and type I collagen. Using the device, we found that HUVECs promoted the 3D invasion of heterogeneous glioma cell populations into type I collagen gel. The invasion induced by HUVECs was predominantly preceded by cells positive for nestin, a neural stem cell marker. In contrast, cells positive for tubulin β3 (TUBB3), a differentiated cell marker, rarely preceded invasion. In addition, HUVECs induced the upregulation of TUBB3 in GICs. Finally, we found that the genes associated with invasion, such as integrins α2 and β3, were significantly upregulated in the presence of HUVECs. These results as well as the experimental approach provide valuable knowledge for the development of effective therapeutic strategies targeting the aggressive invasion of GBM.

Role of eosinophils in the initiation and progression of pancreatitis pathogenesis

Eosinophilic pancreatitis (EP) is reported in humans; however, the etiology and role of eosinophils in EP pathogenesis are poorly understood and not well explored. Therefore, it is interesting to examine the role of eosinophils in the initiation and progression of pancreatitis pathogenesis. Accordingly, we performed anti-major basic protein immunostaining, chloroacetate esterase, and Masson's trichrome analyses to detect eosinophils, mast cells, and collagen in the tissue sections of mouse and human pancreas. Induced eosinophils accumulation and degranulation were observed in the tissue sections of human pancreatitis, compared with no eosinophils in the normal pancreatic tissue sections. Similarly, we observed induced tissue eosinophilia along with mast cells and acinar cells atrophy in cerulein-induced mouse model of chronic pancreatitis. Additionally, qPCR and ELISA analyses detected induced transcript and protein levels of proinflammatory and profibrotic cytokines, chemokines like IL 5, IL-18, eotaxin-1, eotaxin-2, TGF-β1, collagen-1, collagen-3, fibronectin, and α-SMA in experimental pancreatitis. Mechanistically, we show that eosinophil-deficient GATA1 and endogenous IL-5-deficient mice were protected from the induction of proinflammatory and profibrotic cytokines, chemokines, tissue eosinophilia, and mast cells in a cerulein-induced murine model of pancreatitis. These human and experimental data indicate that eosinophil accumulation and degranulation may have a critical role in promoting pancreatitis pathogenesis including fibrosis. Taken together, eosinophil tissue accumulation needs appropriate attention to understand and restrict the progression of pancreatitis pathogenesis in humans. NEW & NOTEWORTHY The present study for the first time shows that eosinophils accumulate in the pancreas and promote disease pathogenesis, including fibrosis in earlier reported cerulein-induced experimental models of pancreatitis. Importantly, we show that GATA-1 and IL-5 deficiency protects mice form the induction of eosinophil active chemokines, and profibrotic cytokines, including accumulation of tissue collagen in an experimental model of pancreatitis. Additionally, we state that cerulein-induced chronic pancreatitis is independent of blood eosinophilia.

TREM-1 and its potential ligands in non-infectious diseases: from biology to clinical perspectives

Triggering receptor expressed on myeloid cells-1 (TREM-1) is expressed on the majority of innate immune cells and to a lesser extent on parenchymal cells. Upon activation, TREM-1 can directly amplify an inflammatory response. Although it was initially demonstrated that TREM-1 was predominantly associated with infectious diseases, recent evidences shed new light into its role in sterile inflammatory diseases. Indeed, TREM-1 receptor and its signaling pathways contribute to the pathology of several non-infectious acute and chronic inflammatory diseases, including atherosclerosis, ischemia reperfusion-induced tissue injury, colitis, fibrosis and cancer. This review, aims to give an extensive overview of TREM-1 in non-infectious diseases, with the focus on the therapeutic potential of TREM-1 intervention strategies herein. In addition, we provide the reader with a functional enrichment analysis of TREM-1 signaling pathway and potential TREM-1 ligands in these diseases, obtained via in silico approach. We discuss pre-clinical studies which show that TREM-1 inhibition, via synthetic soluble TREM-1 protein mimickers, is effective in treating (preventing) specific inflammatory disorders, without significant effects on antibacterial response. Further research aimed at identifying specific TREM-1 ligands, in different inflammatory disorders, is required to further unravel the role of this receptor, and explore new avenues to modulate its function.

Do Animal Models of Acute Pancreatitis Reproduce Human Disease?

Acute pancreatitis is currently the most common cause of hospital admission among all nonmalignant gastrointestinal diseases. To understand the pathophysiology of the disease and as a potential step toward developing targeted therapies, attempts to induce the disease experimentally began more than 100 years ago. Recent decades have seen progress in developing new experimental pancreatitis models as well as elucidating many underlying cell biological and pathophysiological disease mechanisms. Some models have been developed to reflect specific causes of acute pancreatitis in human beings. However, the paucity of data relating to the molecular mechanisms of human disease, the likelihood that multiple genetic and environmental factors affect the risk of disease development and its severity, and the limited information regarding the natural history of disease in human beings make it difficult to evaluate the value of disease models. Here, we provide an overview of key models and discuss our views on their strengths for characterizing cell biological disease mechanisms or for identifying potential therapeutic targets. We also acknowledge their limitations.

CLIC1 null mice demonstrate a role for CLIC1 in macrophage superoxide production and tissue injury

We generated and studied CLIC1 null (C1KO) mice to investigate the physiological role of this protein. C1KO and matched wild-type (WT) mice were studied in two models of acute toxic tissue injury. CLIC1 expression is upregulated following acute injury of WT kidney and pancreas and is absent in C1KOs. Acute tissue injury is attenuated in the C1KOs and this correlates with an absence of the rise in tissue reactive oxygen species (ROS) that is seen in WT mice. Infiltration of injured tissue by inflammatory cells was comparable between WT and C1KOs. Absence of CLIC1 increased PMA-induced superoxide production by isolated peritoneal neutrophils but dramatically decreased PMA-induced superoxide production by peritoneal macrophages. CLIC1 is expressed in both neutrophils and macrophages in a peripheral pattern consistent with either plasma membrane or the cortical cytoskeleton in resting cells and redistributes away from the periphery following PMA stimulation in both cell types. Absence of CLIC1 had no effect on redistribution or dephosphorylation of Ezrin/ERM cytoskeleton in macrophages. Plasma membrane chloride conductance is altered in the absence of CLIC1, but not in a way that would be expected to block superoxide production. NADPH oxidase redistributes from an intracellular compartment to the plasma membrane when WT macrophages are stimulated to produce superoxide and this redistribution fails to occur in C1KO macrophages. We conclude that the role of CLIC1 in macrophage superoxide production is to support redistribution of NADPH oxidase to the plasma membrane, and not through major effects on ERM cytoskeleton or by acting as a plasma membrane chloride channel.

YAP1 and TAZ Control Pancreatic Cancer Initiation in Mice by Direct Up-regulation of JAK-STAT3 Signaling

BACKGROUND & AIMS

Pancreatitis is the most important risk factor for pancreatic ductal adenocarcinoma (PDAC). Pancreatitis predisposes to PDAC because it induces a process of acinar cell reprogramming known as acinar-to-ductal metaplasia (ADM)-a precursor of pancreatic intraepithelial neoplasia lesions that can progress to PDAC. Mutations in KRAS are found at the earliest stages of pancreatic tumorigenesis, and it appears to be a gatekeeper to cancer progression. We investigated how mutations in KRAS cooperate with pancreatitis to promote pancreatic cancer progression in mice.

METHODS

We generated mice carrying conditional alleles of Yap1 and Taz and disrupted Yap1 and Taz using a Cre-lox recombination strategy in adult mouse pancreatic acinar cells (Yap1fl/fl;Tazfl/fl;Ela1-CreERT2). We crossed these mice with LSL-KrasG12D mice, which express a constitutively active form of KRAS after Cre recombination. Pancreatic tumor initiation and progression were analyzed after chemically induced pancreatitis. We analyzed pancreatic tissues from patients with pancreatitis or PDAC by immunohistochemistry.

RESULTS

Oncogenic activation of KRAS in normal, untransformed acinar cells in the pancreatic tissues of mice resulted in increased levels of pancreatitis-induced ADM. Expression of the constitutive active form of KRAS in this system led to activation of the transcriptional regulators YAP1 and TAZ; their function was required for pancreatitis-induced ADM in mice. The JAK-STAT3 pathway was a downstream effector of KRAS signaling via YAP1 and TAZ. YAP1 and TAZ directly mediated transcriptional activation of several genes in the JAK-STAT3 signaling pathway; this could be a mechanism by which acinar cells that express activated KRAS become susceptible to inflammation.

CONCLUSIONS

We identified a mechanism by which oncogenic KRAS facilitates ADM and thereby generates the cells that initiate neoplastic progression. This process involves activation of YAP1 and TAZ in acinar cells, which up-regulate JAK-STAT3 signaling to promote development of PDAC in mice.

Nucleotide-binding oligomerization domain 1 acts in concert with the cholecystokinin receptor agonist, cerulein, to induce IL-33-dependent chronic pancreatitis

Nucleotide-binding oligomerization domain 1 (NOD1) fulfills important host-defense functions via its responses to a variety of gut pathogens. Recently, however, we showed that in acute pancreatitis caused by administration of cholecystokinin receptor (CCKR) agonist (cerulein) NOD1 also has a role in inflammation via its responses to gut commensal organisms. In the present study, we explored the long-term outcome of such NOD1 responsiveness in a new model of chronic pancreatitis induced by repeated administration of low doses of cerulein in combination with NOD1 ligand. We found that the development of chronic pancreatitis in this model requires intact NOD1 and type I IFN signaling and that such signaling mediates a macrophage-mediated inflammatory response that supports interleukin (IL)-33 production by acinar cells. The IL-33, in turn, has a necessary role in the induction of IL-13 and TGF-β1, factors causing the fibrotic reaction characteristic of chronic pancreatitis. Interestingly, the Th2 effects of IL-33 were attenuated by the concomitant type I IFN response since the inflammation was marked by clear increases in IFN-γ and TNF-α production but only marginal increases in IL-4 production. These studies establish chronic pancreatitis as an IL-33-dependent inflammation resulting from synergistic interactions between the NOD1 and CCKR signaling pathways.

Essential Role of Lyn in Fibrosis

Fibrotic disorders involve replacement of normal parenchyma with myofibroblasts, which deposit connective tissue, leading to obliteration of the function of the underlying organ. The treatment options are inadequate and reflect the fact that signaling targets in myofibroblasts are unknown. Here we identify the hyperactive Lyn signaling in myofibroblasts of patients with chronic pancreatitis-induced fibrosis. Lyn activation coexpress with markers of activated myofibroblasts, and is increased ~11-fold in chronic pancreatitis compared to normal tissue. Inhibition of Lyn with siRNA or INNO-406 leads to the substantial decrease of migration and proliferation of human chronic pancreatitis myofibroblasts in vitro, while leaving migration and proliferation of normal myofibroblasts only slightly affected. Furthermore, inhibition of Lyn prevents synthesis of procollagen and collagen in myofibroblasts in a mouse model of chronic pancreatitis-induced fibrosis. We conclude that Lyn, as a positive regulator of myofibroblast migration, proliferation, and collagen production, is a key target for preventing fibrosis.

Inhibitors of Arg-Gly-Asp-Binding Integrins Reduce Development of Pancreatic Fibrosis in Mice

BACKGROUND & AIMS

Pancreatic stellate cells (PSCs) regulate the development of chronic pancreatitis (CP) and are activated by the cytokine transforming growth factor β (TGFB). Integrins of the αv family promote TGFB signaling in mice, probably by interacting with the Arg-Gly-Asp (RGD) sequence of the TGFB latency-associated peptide, which frees TGFB to bind its cellular receptors. However, little is known about the role of integrins in the development of CP. We investigated the effects of small-molecule integrin inhibitors in a mouse model of CP.

METHODS

We induced CP in C57BL/6 female mice by repeated cerulein administration. An active RGD peptidomimetic compound (Center for World Health and Medicine [CWHM]-12) was delivered by continuous infusion, starting 3 days before or 5 days after cerulein administration began. Pancreata were collected and parenchymal atrophy, fibrosis, and activation of PSCs were assessed by histologic, gene, and protein expression analyses. We measured CWHM-12 effects on activation of TGFB in co-culture assays in which rat PSC cells (large T immortalized cells [LTC-14]) activate expression of a TGFB-sensitive promoter in reporter cells.

RESULTS

Pancreatic tissues of mice expressed messenger RNAs encoding subunits of RGD-binding integrins. Cerulein administration increased expression of these integrins, altered pancreatic cell morphology, and induced fibrosis. The integrin inhibitor CWHM-12 decreased acinar cell atrophy and loss, and substantially reduced fibrosis, activation of PSCs, and expression of genes regulated by TGFB. CWHM-12 also reduced established fibrosis in mice and blocked activation of TGFB in cultured cells.

CONCLUSIONS

Based on studies of a mouse model of CP and cultured PSCs, integrins that bind RGD sequences activate PSCs and promote the development of pancreatic fibrogenesis in mice. Small-molecule antagonists of this interaction might be developed for treatment of pancreatic fibrotic diseases.

Antioxidant activity of Inonotus obliquus polysaccharide and its amelioration for chronic pancreatitis in mice

Inonotus obliquus polysaccharide (IOP) was extracted by water with a yield of 9.83% and purified by an anion-exchange DEAE cellulose column and Sephadex G-200 gel with a polysaccharide content of 98.6%. The scavenging activities for 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and hydroxyl radicals of IOP were 82.3% and 81.3% respectively at a concentration of 5 mg/mL. IOP was composed of Man, Rha, Glu, Gal, Xyl and Ara in a molar ratio of 9.81:3.6：29.1：20.5：21.6：5.4 respectively. The gel permeation chromatography indicated that IOP was a homogeneous polysaccharide with molecular weight of 32.5 kDa. IOP helped to alleviate pancreatic acinar atrophy and weight loss for chronic pancreatitis (CP) mice induced by Diethyldithiocarbamate (DDC). The SOD level was increased most by IOP-H treatment (400 mg/kg body weight). MDA, IL-1β and LDH were significantly decreased by IOP treatment, especially hydroxyproline, IFN-γ and AMS levels were decreased 39.18%, 37.82% and 41.57% by IOP-H treatment respectively compared to MC group. In conclusion, IOP possessed strong antioxidant activity for scavenging free radicals in vitro and vivo which could be propitious to CP therapy in mice.

Attention to Background Strain Is Essential for Metabolic Research: C57BL/6 and the International Knockout Mouse Consortium

The International Knockout Mouse Consortium (IKMC) introduces its targeted constructs into C57BL/6N embryonic stem cells. However, breeding with a Cre-recombinase and/or Flp-recombinase mouse is required for the generation of a null allele with the IKMC cassette. Many recombinase strains are in the C57BL/6J background, resulting in knockout animals on a mixed strain background. This can lead to variability in metabolic data and the use of improper control groups. While C57BL/6N and C57BL/6J are derived from the same parental C57BL/6 strain, there are key genotypic and phenotypic differences between these substrains. Many researchers may not even be aware of these differences, as the shorthand C57BL/6 is often used to describe both substrains. We found that 58% of articles involving genetically modified mouse models did not completely address background strain. This review will describe these two substrains and highlight the importance of separate consideration in mouse model development. Our aim is to increase awareness of this issue in the diabetes research community and to provide practical strategies to enable researchers to avoid mixed strain animals when using IKMC knockout mice.

Neuropilin-2 Regulates Endosome Maturation and EGFR Trafficking to Support Cancer Cell Pathobiology

Neuropilin-2 (NRP2) is a non-tyrosine kinase receptor frequently overexpressed in various malignancies, where it has been implicated in promoting many protumorigenic behaviors, such as imparting therapeutic resistance to metastatic cancer cells. Here, we report a novel function of NRP2 as a regulator of endocytosis, which is enhanced in cancer cells and is often associated with increased metastatic potential and drug resistance. We found that NRP2 depletion in human prostate and pancreatic cancer cells resulted in the accumulation of EEA1/Rab5-positive early endosomes concomitant with a decrease in Rab7-positive late endosomes, suggesting a delay in early-to-late endosome maturation. NRP2 depletion also impaired the endocytic transport of cell surface EGFR, arresting functionally active EGFR in endocytic vesicles that consequently led to aberrant ERK activation and cell death. Mechanistic investigations revealed that WD-repeat- and FYVE-domain-containing protein 1 (WDFY1) functioned downstream of NRP2 to promote endosome maturation, thereby influencing the endosomal trafficking of EGFR and the formation of autolysosomes responsible for the degradation of internalized cargo. Overall, our results indicate that the NRP2/WDFY1 axis is required for maintaining endocytic activity in cancer cells, which supports their oncogenic activities and confers drug resistance. Therefore, therapeutically targeting endocytosis may represent an attractive strategy to selectively target cancer cells in multiple malignancies.

What does procollagen C-endopeptidase enhancer protein 2 have to do with HDL-cholesteryl ester uptake? Or how I learned to stop worrying and love reverse cholesterol transport?

PURPOSE OF REVIEW

The purpose of this study is to provide an update on the role HDL apolipoprotein A-I plays in reducing the risk of cardiovascular disease (CVD) and how it relates to reverse cholesterol transport (RCT).

RECENT FINDINGS

Despite numerous studies showing that plasma HDL cholesterol concentrations are correlated with a reduced risk of CVD, pharmacologic elevation of HDL has not shown any beneficial effects to date. In contrast, studies correlating the measure of an individual's plasma cholesterol efflux capacity show greater promise as a tool for assessing CVD risk. Although ATP-binding cassette transporter 1-mediated lipidation of apoA-I is considered the principal source of plasma HDL, it represents only one side of the RCT pathway. Equally important is the second half of the RCT pathway in which the liver scavenger receptor class B1 selectively removes HDL cholesteryl esters for excretion. The combined action of the two enzyme systems is reflected in the overall steady-state concentration of plasma HDL cholesterol. For example, reduced ATP-binding cassette transporter 1-mediated production of nascent HDL lowers plasma HDL concentration, just as an increase in cholesteryl ester uptake by scavenger receptor class B1 reduces HDL levels. Thus, the complexity of intravascular HDL metabolism suggests that steady-state plasma HDL concentrations do not provide adequate information regarding an individual's HDL quality or function. Herein, we describe a new player, procollagen C-endopeptidase enhancer 2, which shows atheroprotective function and influences both sides of RCT by enhancing production and catabolism of HDL cholesteryl esters.

SUMMARY

The discovery of a new molecule, procollagen C-endopeptidase enhancer 2, implicated in the regulation of HDL cholesteryl ester concentrations suggests that the extracellular matrix and the proteins that regulate its function represent a new and as yet unexplored realm of HDL cholesterol metabolism.

Impact of a novel homozygous mutation in nicotinamide nucleotide transhydrogenase on mitochondrial DNA integrity in a case of familial glucocorticoid deficiency

BACKGROUND

Familial Glucocorticoid Deficiency (FGD) is a rare autosomal recessive disorder that is characterized by isolated glucocorticoid deficiency. Recently, mutations in the gene encoding for the mitochondrial nicotinamide nucleotide transhydrogenase (NNT) have been identified as a causative gene for FGD; however, no NNT activities have been reported in FGD patients carrying NNT mutations.

METHODS

Clinical, biochemical and molecular analyses of lymphocytes from FDG homozygous and heterozygous carriers for the F215S NNT mutation.

RESULTS

In this study, we described an FGD-affected Japanese patient carrying a novel NNT homozygous mutation (c.644T>C; F215S) with a significant loss-of-function (NNT activity = 31% of healthy controls) in peripheral blood cells' mitochondria. The NNT activities of the parents, heterozygous for the mutation, were 61% of controls.

CONCLUSIONS

Our results indicated that (i) mitochondrial biogenesis (citrate synthase activity) and/or mtDNA replication (mtDNA copy number) were affected at ≤60% NNT activity because these parameters were affected in individuals carrying either one or both mutated alleles; and (ii) other outcomes (mtDNA deletions, protein tyrosine nitration, OXPHOS capacity) were affected at ≤30% NNT activity as also observed in murine cerebellar mitochondria from C57BL/6J (NNT^-/-) vs. C57BL/6JN (NNT^+/+) substrains.

GENERAL SIGNIFICANCE

By studying a family affected with a novel point mutation in the NNT gene, a gene-dose response was found for various mitochondrial outcomes providing for novel insights into the role of NNT in the maintenance of mtDNA integrity beyond that described for preventing oxidative stress.

Reanalysis of the gene expression profile in chronic pancreatitis via bioinformatics methods

Background

Diagnosis at an early stage of chronic pancreatitis (CP) is challenging. It has been reported that microRNAs (miRNAs) are increasingly found and applied as targets for the diagnosis and treatment of various cancers. However, to the best of our knowledge, few published papers have described the role of miRNAs in the diagnosis of CP.

Method

We downloaded gene expression profile data from the Gene Expression Omnibus and identified differentially expressed genes (DEGs) between CP and normal samples of Harlan mice and Jackson Laboratory mice. Common DEGs were filtered out, and the semantic similarities of gene classes were calculated using the GOSemSim software package. The gene class with the highest functional consistency was selected, and then the Lists2Networks web-based system was used to analyse regulatory relationships between miRNAs and gene classes. The functional enrichment of the gene classes was assessed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway annotation terms.

Results

A total of 405 common upregulated DEGs and 7 common downregulated DEGs were extracted from the two kinds of mice. Gene cluster D was selected from the common upregulated DEGs because it had the highest semantic similarity. miRNA 124a (miR-124a) was found to have a significant regulatory relationship with cluster D, and DEGs such as CHSY1 and ABCC4 were found to be regulated by miR-124a. The GO term of response to DNA damage stimulus and the pathway of Escherichia coli infection were significantly enriched in cluster D.

Conclusion

DNA damage and E. coli infection might play important roles in CP pathogenesis. In addition, miR-124a might be a potential target for the diagnosis and treatment of CP.

Early events in Sjögren's Syndrome pathogenesis: the importance of innate immunity in disease initiation

Sjögren's Syndrome (SS) is a debilitating autoimmune disease that primarily affects women. Patients with SS experience dry eyes and dry mouth in addition to systemic disease manifestations, including arthritis, peripheral neuropathy and pulmonary fibrosis. As in many autoimmune diseases, the inciting factors that precipitate SS are poorly understood. Patients with SS have periductal and perivascular lymphocytic infiltration of salivary and lacrimal tissue, and this is a hallmark of disease. While this infiltration is well characterized, the pathologic events that precede and cause this inflammatory cell recruitment are unknown. Although few studies have examined SS salivary tissue prior to disease onset, there is strong evidence for innate immune hyperactivity. Accordingly, processes such as apoptosis of glandular tissue, heightened inflammatory cytokine and chemokine production, and toll-like receptor (TLR) activation are described in early disease and are each linked to innate immune activation in murine models of disease and SS patients. This review will explore the relationship between innate immunity and SS pathogenesis prior to overt disease onset and discuss therapeutic strategies to mitigate disease progression in SS patients.