Immune cells and immune-based therapy in pancreatitis. Immunol Res. 2014;58:378-386. [PMID: 24710635 DOI: 10.1007/s12026-014-8504-5]

Genome Mining for Hub Genes Related to Endoplasmic Reticulum Stress in Pancreatitis: A Perspective from In Silico Characterization

Pancreatitis, as a common exocrine pancreatic disease, poses a daunting challenge to patients' health and the medical system. Endoplasmic reticulum stress (ERS) plays an essential role in the pathologic process of pancreatitis. However, its mechanism is not fully understood. Therefore, this study was designed to deepen the understanding of the pathogenic mechanism of the disease by screening key ERS-related genes (ERSRGs) associated with pancreatitis. Pancreatitis mRNA data for GSE194331 (Normal: 32, Pancreatitis: 87) and pancreatitis GSE143754 (Normal: 9, Pancreatitis: 6) were downloaded from the GEO database and were used as a training and validation set, respectively. First, the training set GSE194331 was differentially expressed and intersected with the ERSRGs (n = 265) obtained from the MSigDB database to result in 42 differentially expressed ERSRGs (DE-ERSRGs). Subsequently, five candidate genes were further screened by PPI network and MCC and MCODE algorithms. However, according to the ROC curve results, AUC values of CCND1, BCL2, PIK3R1, and BCL2L1 were all greater than 0.6, indicating that they had good diagnostic performance, which was verified by the GSE143754 data set. Based on the GeneMANIA network, it was found that hub genes BCL2 and BCL2L1 may be the key factors in the regulation of mitochondrial metabolism. 24 differentially expressed pancreatitis-related genes (DE-PRGs) were found by difference analysis and Venn analysis. Hub genes BCL2 and PIK3R1 that were significantly correlated with 24 DE-PRGs were determined by Spearman analysis. ssGSEA algorithm was further used to reveal the significant correlation between these hub genes and the immune microenvironment of pancreatitis. The miRNA and lncRNA targeting hub genes were predicted using miRWalk, TargetScan, miRDB, and ENCORI databases, providing research directions for the mechanism of pancreatitis. Finally, the Network Analyst website was used to predict potential compounds associated with the hub gene. In conclusion, this study not only further supports the role of ERS in the development of pancreatitis but also provides a new perspective and direction for the development of biomarkers and mechanism of pancreatitis. At the same time, the results of this study provide a reliable research direction for the targeted treatment of pancreatitis.

Association between neutrophil to high-density lipoprotein cholesterol ratio and disease severity in patients with acute biliary pancreatitis

BACKGROUND

The neutrophil to high-density lipoprotein cholesterol ratio (NHR) is independently associated with the severity of various diseases. However, its association with acute biliary pancreatitis (ABP) remains unknown.

METHODS

This study included 1335 eligible patients diagnosed with ABP from April 2016 to December 2022. Patients were divided into low- and high-NHR level groups using an optimal cut-off value determined utilizing Youden's index. Multivariate logistic regression analysis was used to investigate the correlation between NHR and ABP severity. Multivariate analysis-based limited restricted cubic spline (RCS) method was used to evaluate the nonlinear relationship between NHR and the risk of developing moderate or severe ABP.

RESULTS

In this study, multivariate logistic regression analysis indicated an independent association between NHR and ABP severity (p < .001). The RCS analysis showed a linear correlation between NHR and the risk of developing moderate or severe ABP (P for non-linearity > 0.05), and increased NHR was found to be independently associated with a more severe form of the disease.

CONCLUSIONS

Our study suggests that NHR is a simple and practical independent indicator of disease severity, serving as a potential novel predictor for patients with ABP.

Redefining Immune Dynamics in Acute Pancreatitis: The Protective Role of Galectin-3 Deletion and Treg Cell Enhancement

Acute pancreatitis (AP) is a complex inflammatory condition that can lead to systemic inflammatory responses and multiple organ dysfunction. This study investigates the role of Galectin-3 (Gal-3), a β-galactoside-binding lectin, in modulating acquired immune responses in AP. Acute pancreatitis was induced by ligation of the bile-pancreatic duct in wild-type and Galectin-3-deficient C57BL/6 mice. We determined the phenotypic and molecular features of inflammatory cells, serum concentrations of amylase, pancreatic trypsin activity, and pancreatic and lung pathology. Galectin-3 deficiency decreased the total number of CD3+CD49- T cells and CD4+ T helper cells, downregulated the production of inflammatory cytokine and IFN-γ, and increased the accumulation of IL-10-producing Foxp3+ T regulatory cells and regulatory CD4+ T cells in the pancreata of diseased animals. The deletion of Galectin-3 ameliorates acute pancreatitis characterized by lowering serum amylase concentration and pancreatic trypsin activity, and attenuating of the histopathology of the lung. These findings shed light on the role of Galectin-3 in acquired immune response in acute pancreatitis and identify Galectin-3 as an attractive target for investigation of the immunopathogenesis of disease and for consideration as a potential therapeutic target for patients with acute inflammatory disease of the pancreas.

The role and mechanism of action of microbiota-derived short-chain fatty acids in neutrophils: From the activation to becoming potential biomarkers

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, have emerged as critical mediators in the communication between the human microbiota and its host. As the first responder to the inflammatory site, neutrophils play an important role in protecting the host against bacterial infections. Recent investigations revealed that SCFAs generated from microbiota influence various neutrophil activities, including activation, migration, and generation of mediators of inflammatory processes. SCFAs have also been demonstrated to exhibit potential therapeutic benefits in a variety of disorders related to neutrophil dysfunction, including inflammatory bowel disease, viral infectious disorders, and cancer. This study aims to examine the molecular processes behind the complicated link between SCFAs and neutrophils, as well as their influence on neutrophil-driven inflammatory disorders. In addition, we will also provide an in-depth review of current research on the diagnostic and therapeutic value of SCFAs as possible biomarkers for neutrophil-related diseases.

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.

AKBA alleviates experimental pancreatitis by inhibiting oxidative stress in Macrophages through the Nrf2/HO-1 pathway

BACKGROUND

Acute pancreatitis (AP) is an inflammatory condition of the pancreas characterized by oxidative stress and inflammation in its pathophysiology. Acetyl-11-keto-β-boswellic acid (AKBA) is an active triterpenoid with antioxidant activity. This article seeks to assess the impact of AKBA on AP and investigate its underlying mechanisms.

METHODS

AP was induced in wild-type, Lyz2+/cre Nrf2fl/fl mice and Pdx1+/cre Nrf2fl/fl mice by caerulein. Serum amylase and lipase levels, along with histological grading, were utilized to evaluate the severity of AP. Murine bone marrow-derived macrophages (BMDMs) were isolated, cultured, and polarized to the M1 subtype. Flow cytometry and ELISA were utilized to identify the macrophage phenotype. Alterations in oxidative stress damage and intracellular ROS were observed. Nrf2/HO-1 signaling pathways were also evaluated.

RESULTS

In a caerulein-induced mouse model of AP, treatment with AKBA reduced blood amylase and lipase activity and ameliorated pancreatic tissue histological and pathological features. Furthermore, AKBA significantly mitigated oxidative stress-induced damage and induced the expression of Nrf2 and HO-1 protein. Additionally, by using conditional knockout mice (Lyz2+/cre Nrf2fl/fl and Pdx1+/cre Nrf2fl/fl mice), we verified that Nrf2 primarily functions in macrophages rather than acinar cells. In vitro, AKBA inhibits pro-inflammatory M1-subtype macrophage polarization and reduces ROS generation through Nrf2/HO-1 oxidative stress pathway. Moreover, the protective effects of AKBA against AP were abolished in myeloid-specific Nrf2-deficient mice and BMDMs. Molecular docking results revealed interactions between AKBA and Nrf2.

CONCLUSION

Our results confirm that AKBA exerts protective effects against AP in mice by inhibiting oxidative stress in macrophages through the Nrf2/HO-1 Pathway.

The Role of Krüppel-like Factors in Pancreatic Physiology and Pathophysiology

Krüppel-like factors (KLFs) belong to the family of transcription factors with three highly conserved zinc finger domains in the C-terminus. They regulate homeostasis, development, and disease progression in many tissues. It has been shown that KLFs play an essential role in the endocrine and exocrine compartments of the pancreas. They are necessary to maintain glucose homeostasis and have been implicated in the development of diabetes. Furthermore, they can be a vital tool in enabling pancreas regeneration and disease modeling. Finally, the KLF family contains proteins that act as tumor suppressors and oncogenes. A subset of members has a biphasic function, being upregulated in the early stages of oncogenesis and stimulating its progression and downregulated in the late stages to allow for tumor dissemination. Here, we describe KLFs' function in pancreatic physiology and pathophysiology.

Immune cells and immune cell-targeted therapy in chronic pancreatitis

In recent years, studies have attempted to understand the immune cells and mechanisms underlying the pathogenesis of chronic pancreatitis (CP) by constructing a model of CP. Based on these studies, the innate immune response is a key factor in disease pathogenesis and inflammation severity. Novel mechanisms of crosstalk between immune and non-immune pancreatic cells, such as pancreatic stellate cells (PSC), have also been explored. Immune cells, immune responses, and signaling pathways in CP are important factors in the development and progression of pancreatitis. Based on these mechanisms, targeted therapy may provide a feasible scheme to stop or reverse the progression of the disease in the future and provide a new direction for the treatment of CP. This review summarizes the recent advances in research on immune mechanisms in CP and the new advances in treatment based on these mechanisms.

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

Circulating monocytes in acute pancreatitis

Acute pancreatitis is a common gastrointestinal disease characterized by inflammation of the exocrine pancreas and manifesting itself through acute onset of abdominal pain. It is frequently associated with organ failure, pancreatic necrosis, and death. Mounting evidence describes monocytes - phagocytic, antigen presenting, and regulatory cells of the innate immune system - as key contributors and regulators of the inflammatory response and subsequent organ failure in acute pancreatitis. This review highlights the recent advances of dynamic change of numbers, phenotypes, and functions of circulating monocytes as well as their underling regulatory mechanisms with a special focus on the role of lipid modulation during acute pancreatitis.

Has COVID-19 Modified the Weight of Known Systemic Inflammation Indexes and the New Ones (MCVL and IIC) in the Assessment as Predictive Factors of Complications and Mortality in Acute Pancreatitis?

We aimed at evaluating the prognostic capacity of the inflammatory indices derived from routine complete blood cell counts in two groups of patients with acute pancreatitis from two different time periods, before and during the COVID-19 pandemic, when a high incidence of complications with surgical risk and mortality was found. Two new markers were introduced: the mean corpuscular volume to lymphocyte ratio (MCVL) and the cumulative inflammatory index (IIC), which were calculated at a baseline in the two groups of patients. Of the already established markers, none of them managed to effectively predict the complications with surgical risk and mortality, with a decrease of less than 50% in specificity in the peri-COVID group. The MCVL had the best prediction of complications with surgical risk in both the pre-COVID and peri-COVID groups, validated it as an independent factor by multivariate analysis. The IIC had the best prediction of mortality in both periods and was proven to be an independent factor by multivariate analysis. As the IIC predicted death best, we tested the occurrence of death and found that patients with PA who had an IIC > 12.12 presented a risk of death 4.08 times higher in the pre-COVID group and 3.33 times higher in the peri-COVID group. The new MCVL and IIC independent markers had a superior sensitivity and specificity in predicting surgical risk complications and, respectively, mortality in the group of patients with acute pancreatitis during the COVID-19 pandemic, which makes them widely applicable in populations with modified immune and inflammatory status. Conclusions: In patients with acute pancreatitis, MCVL has a significant predictive value regarding complications with surgical risk (abscess, necrosis, and pseudocyst), and the IIC has a significant predictive value for mortality.

Blockade of the protease ADAM17 ameliorates experimental pancreatitis

Acute and chronic pancreatitis, the latter associated with fibrosis, are multifactorial inflammatory disorders and leading causes of gastrointestinal disease-related hospitalization. Despite the global health burden of pancreatitis, currently, there are no effective therapeutic agents. In this regard, the protease A Disintegrin And Metalloproteinase 17 (ADAM17) mediates inflammatory responses through shedding of bioactive inflammatory cytokines and mediators, including tumor necrosis factor α (TNFα) and the soluble interleukin (IL)-6 receptor (sIL-6R), the latter of which drives proinflammatory IL-6 trans-signaling. However, the role of ADAM17 in pancreatitis is unclear. To address this, Adam17^ex/ex mice-which are homozygous for the hypomorphic Adam17^ex allele resulting in marked reduction in ADAM17 expression-and their wild-type (WT) littermates were exposed to the cerulein-induced acute pancreatitis model, and acute (1-wk) and chronic (20-wk) pancreatitis models induced by the cigarette smoke carcinogen nicotine-derived nitrosamine ketone (NNK). Our data reveal that ADAM17 expression was up-regulated in pancreatic tissues of animal models of pancreatitis. Moreover, the genetic (Adam17^ex/ex mice) and therapeutic (ADAM17 prodomain inhibitor [A17pro]) targeting of ADAM17 ameliorated experimental pancreatitis, which was associated with a reduction in the IL-6 trans-signaling/STAT3 axis. This led to reduced inflammatory cell infiltration, including T cells and neutrophils, as well as necrosis and fibrosis in the pancreas. Furthermore, up-regulation of the ADAM17/IL-6 trans-signaling/STAT3 axis was a feature of pancreatitis patients. Collectively, our findings indicate that the ADAM17 protease plays a pivotal role in the pathogenesis of pancreatitis, which could pave the way for devising novel therapeutic options to be deployed against this disease.

Myeloid-Derived Suppressor Cells in Patients With Acute Pancreatitis With Increased Inhibitory Function

Acute pancreatitis (AP) is pancreatic or systemic inflammation without or with motion organ dysfunction. Severe acute pancreatitis (SAP) is the main cause of death for patients with AP. A pro-/anti-inflammatory imbalance is considered the key regulation of disease severity. However, the real mechanism of SAP remains unclear. This study aimed to identify the frequency and specific roll of myeloid-derived suppressor cell (MDSC) in AP. We evaluated MDSC frequency and disease severity by analyzing MDSCs in the peripheral blood of healthy controls (HCs) and patients with mild acute pancreatitis (MAP) and SAP by flow cytometry. We also compared the frequency and inhibitory ability of MDSCs from HCs and SAP, and finally detected the reason for the difference in inhibitory ability. AP was marked by expansion of MDSCs as well as its subsets, granulocytic MDSCs (G-MDSCs) and monocytic MDSCs (M-MDSCs). The proportion of MDSC in the peripheral blood mononuclear cells of patients with AP was increased and positively correlated with AP severity. The frequency of MDSC was decreased after treatment compared with pre-treatment. CD3+ T cells were remarkably inhibited by MDSC derived from the patients with SAP. In the expression of arginase-1 (Arg-1) and reactive oxygen species (ROS), the MDSCs from patients with SAP increased. These findings demonstrated that MDSCs expanded in the peripheral blood in patients with AP, especially in those with SAP. Moreover, the inhibitory ability of MDSCs was increased in the patients with SAP compared with that in the HCs. The enhanced suppressive function was possibly caused by an overexpression of Arg-1 and ROS.

Immune enhancement in patients with predicted severe acute necrotising pancreatitis: a multicentre double-blind randomised controlled trial

PURPOSE

Infected pancreatic necrosis (IPN) is a highly morbid complication of acute necrotising pancreatitis (ANP). Since there is evidence of early-onset immunosuppression in acute pancreatitis, immune enhancement may be a therapeutic option. This trial aimed to evaluate whether early immune-enhancing Thymosin alpha 1 (Tα1) treatment reduces the incidence of IPN in patients with predicted severe ANP.

METHODS

We conducted a multicentre, double-blind, randomised, placebo-controlled trial involving ANP patients with an Acute Physiology and Chronic Health Evaluation II (APACHE II) score ≥ 8 and a computed tomography (CT) severity score ≥ 5 admitted within 7 days of the advent of symptoms. Enrolled patients were assigned to receive a subcutaneous injection of Tα1 1.6 mg every 12 h for the first 7 days and 1.6 mg once a day for the subsequent 7 days or matching placebos (normal saline). The primary outcome was the development of IPN during the index admission.

RESULTS

A total of 508 patients were randomised, of whom 254 were assigned to receive Tα1 and 254 placebo. The vast majority of the participants required admission to the intensive care unit (ICU) (479/508, 94.3%). During the index admission, 40/254(15.7%) patients in the Tα1 group developed IPN compared with 46/254 patients (18.1%) in the placebo group (difference -2.4% [95% CI - 7.4 to 5.1%]; p = 0.48). The results were similar across four predefined subgroups. There was no difference in other major complications, including new-onset organ failure (10.6% vs. 15%), bleeding (6.3% vs. 3.5%), and gastrointestinal fistula (2% vs. 2.4%).

CONCLUSION

The immune-enhancing Tα1 treatment of patients with predicted severe ANP did not reduce the incidence of IPN during the index admission.

Innate Lymphoid Cells: Emerging Players in Pancreatic Disease

Common pancreatic diseases have caused significant economic and social burdens worldwide. The interstitial microenvironment is involved in and plays a crucial part in the occurrence and progression of pancreatic diseases. Innate lymphoid cells (ILCs), an innate population of immune cells which have only gradually entered our visual field in the last 10 years, play an important role in maintaining tissue homeostasis, regulating metabolism, and participating in regeneration and repair. Recent evidence indicates that ILCs in the pancreas, as well as in other tissues, are also key players in pancreatic disease and health. Herein, we examined the possible functions of different ILC subsets in common pancreatic diseases, including diabetes mellitus, pancreatitis and pancreatic cancer, and discussed the potential practical implications of the relevant findings for future further treatment of these pancreatic diseases.

Pirfenidone increases IL10 and improves acute pancreatitis in multiple clinically relevant murine models

Despite decades of research there is no specific therapy for Acute Pancreatitis (AP). In the current study, we have evaluated the efficacy of pirfenidone, an anti-inflammatory and anti-fibrotic agent which is FDA-approved for treatment of idiopathic pulmonary fibrosis (IPF), in ameliorating local and systemic injury in AP. Our results suggest that treatment with pirfenidone in therapeutic settings (i.e. after initiation of injury), even when administered at the peak of injury, reduces severity of local and systemic injury and inflammation in multiple models of AP. In-vitro evaluation suggests that pirfenidone decreases cytokine release from acini and macrophages and disrupts acinar-macrophage crosstalk. Therapeutic pirfenidone treatment increases IL-10 secretion from macrophages preceding changes in histology and modulates the immune phenotype of inflammatory cells with decreased levels of inflammatory cytokines. Antibody-mediated IL-10 depletion, use of IL-10 Knock Out mice, and macrophage depletion experiments confirmed the role of IL-10 and macrophages in its mechanism of action, as pirfenidone was unable to reduce severity of AP in these scenarios. Since pirfenidone is FDA approved for IPF, a trial evaluating the efficacy of pirfenidone in patients with moderate to severe AP can be initiated expeditiously.Key Words: Acute Pancreatitis, Pirfenidone, Interleukin-10, L-arginine pancreatitis, Systemic inflammation, lung injury.

Cytokine signature for predicting new-onset prediabetes after acute pancreatitis: A prospective longitudinal cohort study

BACKGROUND/PURPOSE

Acute inflammation of the pancreas often leads to metabolic sequelae, the most common of which is new-onset prediabetes (and, ultimately, diabetes). However, there is a lack of studies on predictors of this sequela. The aim was to investigate whether cytokines/chemokines measured at baseline are predictive of new-onset prediabetes after acute pancreatitis (NOPAP).

METHODS

This was a prospective longitudinal cohort study (as part of the LACERTA project) that included 68 individuals with non-necrotising acute pancreatitis who had no diabetes mellitus. Of them, 17 individuals had prediabetes at baseline and during follow-up, 37 individuals had normoglycaemia at baseline and during follow-up, and 14 individuals had normoglycaemia at baseline and developed NOPAP during follow-up. A commercially available human cytokine/chemokine multiplex kit was used to measure a total of 28 analytes at baseline. Multinomial regression analyses were conducted to investigate the associations between the cytokines/chemokines and the three study groups.

RESULTS

Interleukin-1β and interferon γ significantly predicted progression to NOPAP with an odds ratio (95% confidence interval) of 1.097 (1.002, 1.201) and 1.094 (1.003, 1.192), respectively (after accounting for age, sex, body mass index, and aetiology of acute pancreatitis). None of the studied cytokines/chemokines showed statistically significant associations with the antecedent prediabetes group (after accounting for the above covariates).

CONCLUSION

Elevated levels of interleukin-1β and interferon γ in acute pancreatitis individuals with normoglycaemia at baseline may predict progression to NOPAP during follow-up.

Inhibition of nicotinamide phosphoribosyltransferase protects against acute pancreatitis via modulating macrophage polarization and its related metabolites

BACKGROUND & OBJECTIVES

Acute pancreatitis is a common inflammatory disorder of the exocrine pancreas with no specific therapy. Intracellular nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in nicotinamide adenine dinucleotide (NAD) salvage pathway, is involved in many inflammatory disorders. In this study, we investigated the role of NAMPT in experimental acute pancreatitis.

METHODS

Acute pancreatitis was induced in mice using three disparate models: (1) caerulein hyperstimulation, (2) ethanol plus palmitoleic acid, and (3) retrograde biliopancreatic ductal infusion of sodium taurocholate. The NAMPT inhibitor FK866 and NAMPT downstream product nicotinamide mononucleotide (NMN) was administered. Serum and pancreas were collected and analyzed biochemically and histologically. Bone marrow derived macrophages were isolated, cultured with cytokines or pancreatic acini, then analyzed by quantitative PCR and non-targeted metabolomics.

RESULTS

The levels of pancreatic NAMPT and NAD were down-regulated upon acute pancreatitis. NAMPT inhibitor FK866 suppressed M1 macrophage polarization while NMN boosted it. In co-culture of macrophages with acinar cells, inhibition of NAMPT prevented M1-like macrophage differentiation induced by injured pancreatic acini. The injured pancreatic acinar milieu induced a unique metabolic signature linked to macrophage polarization, and inhibition of NAMPT reversed these metabolites changes. Furthermore, NMN supplementation aggravated caerulein hyperstimulation pancreatitis and alcoholic pancreatitis, and inhibition of NAMPT protected against caerulein hyperstimulation, alcoholic and biliary acute pancreatitis and reducing pancreatic macrophage infiltration in vivo.

CONCLUSIONS

NAMPT inhibition protects against acute pancreatitis via preventing M1 macrophage polarization and restoring the metabolites related to macrophage polarization and that NAMPT could be a promising therapeutic target for acute pancreatitis.

STAT5 promotes chronic pancreatitis by enhancing GM-CSF-dependent neutrophil augmentation

Chronic pancreatitis (CP) is a continuing or relapsing inflammatory disease of the pancreas, characterized by fibrosis of the whole tissue. The regulatory mechanisms of the immune microenvironment in the pathogenesis of CP are still not clear. Immune cells, especially myeloid cells, play an important role in the pathogenesis of pancreatitis. Understanding the regulatory mechanisms of immune infiltration has a significant impact on CP intervention. Here, we demonstrated that transcription factor STAT5 was involved in and critical for the progression of CP. Inflammatory stress could significantly increase the expression and activation of STAT5 during CP. STAT5 deficiency or inhibition contributed to alleviating pancreatic inflammation and fibrosis in CP mice. The increased neutrophil infiltration, mediated by up-regulated GM-CSF, was responsible for the pancreatitis-promoting activity of STAT5. Our investigation highlighted the importance of STAT5 in regulating the immune microenvironment of CP. Targeting STAT5 may hold distinct promise for clinical treatment to alleviate CP.

Parabacteroides produces acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration

BACKGROUND

The endoglycosidase heparanase which degrades heparan sulfate proteoglycans, exerts a pro-inflammatory mediator in various inflammatory disorders. However, the function and underlying mechanism of heparanase in acute pancreatitis remain poorly understood. Here, we investigated the interplay between heparanase and the gut microbiota in the development of acute pancreatitis.

METHODS

Acute pancreatitis was induced in wild-type and heparanase-transgenic mice by administration of caerulein. The differences in gut microbiota were analyzed by 16S ribosomal RNA sequencing. Antibiotic cocktail experiment, fecal microbiota transplantation, and cohousing experiments were used to assess the role of gut microbiota.

RESULTS

As compared with wild-type mice, acute pancreatitis was exacerbated in heparanase-transgenic mice. Moreover, the gut microbiota differed between heparanase-transgenic and wild-type mice. Heparanase exacerbated acute pancreatitis in a gut microbiota-dependent manner. Specially, the commensal Parabacteroides contributed most to distinguish the differences between wild-type and heparanase-transgenic mice. Administration of Parabacteroides alleviated acute pancreatitis in wild-type and heparanase-transgenic mice. In addition, Parabacteroides produced acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration.

CONCLUSIONS

The gut-pancreas axis played an important role in the development of acute pancreatitis and the acetate produced by Parabacteroides may be beneficial for acute pancreatitis treatment. Video abstract.

Decreased infiltration of adipose tissue macrophages and amplified inflammation of adipose tissue in obese mice with severe acute pancreatitis

OBJECTIVE

Macrophages are involved in obesity-associated inflammation and severe acute pancreatitis (SAP) development. However, the role of adipose tissue macrophages (ATMs) in obesity-related SAP has not been fully elucidated. We investigated the relationship between ATMs and inflammatory responses in SAP model mice fed a high-fat diet (HFD).

METHODS

SAP was induced in animal models via intraperitoneal injections of caerulein and lipopolysaccharide (LPS). SAP severity was evaluated, both morphologically and biochemically, and macrophage infiltration in the pancreas and epididymal adipose tissue was measured. We also analyzed apoptosis levels, polarization of the ATMs, and expression of inflammatory mediators in epididymal adipose tissue.

RESULTS

Obesity increased disease severity in SAP animals. Increased macrophage infiltration in the pancreas induced by SAP was found in both normal diet (ND)- and HFD-fed mice. Total ATM infiltration in epididymal adipose tissue was elevated by HFD, while a significant decrease in infiltration was observed in both the ND + SAP and HFD + SAP groups. The apoptosis levels of ATMs were reduced in the HFD group, but were markedly enhanced in both the ND + SAP and HFD + SAP groups compared to their respective control groups. Higher levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) were observed in the HFD + SAP than in the ND + SAP group. Increased proportion of M1 type ATMs was induced by both HFD and SAP.

CONCLUSIONS

Total ATM infiltration was decreased in epididymal adipose tissue of SAP animals. ATM polarization to the M1 type resulted in an amplified inflammatory response in obese mice with SAP.

Electroacupuncture Ameliorates Acute Pancreatitis: A Role for the Vagus Nerve-Mediated Cholinergic Anti-Inflammatory Pathway

Organ failure resulting from excessive inflammation is the leading cause of death in the early phase of acute pancreatitis (AP). The autonomic nervous system was reported to be involved in AP, and the vagus nerve could exert anti-inflammatory effects through α7 nicotinic acetylcholine receptor (α7nAChR) signaling. Acupuncture has been widely used in traditional Asian medicine, and recent studies suggested the inflammation modulating effect of electroacupuncture (EA) might be mediated by the autonomic nervous system. In this study, we aimed to investigate the effects of EA in AP animal models. Two independent AP mouse models were used, namely, caerulein hyperstimulation and pancreatic duct ligation. We found that EA at Zusanli acupoint increased vagus nerve activity, suppressed systemic inflammation, and alleviated the histopathological manifestations and leukocyte infiltrations of the pancreas. Induction of AP resulted in a remarkable decrease in the frequency of α7nAchR⁺ macrophages in the pancreas, while EA counteracted this phenomenon. The anti-inflammatory, pancreatic protective and upregulation of α7nAchR effects of EA were reduced in mice with vagotomy. Moreover, the therapeutic effects of EA were attenuated in mice treated with methyllycaconitine citrate, a selective α7nAChR antagonist. Taken together, EA could modulate inflammation, thereby exerting protective effects in AP. The mechanism may include activating the vagus nerve through the cholinergic anti-inflammatory pathway.

Toll-like receptor 3 expression in myeloid cells is essential for efficient regeneration after acute pancreatitis in mice

Stringent regulation of the inflammatory response is crucial for normal tissue regeneration. Here, we analyzed the role of Toll-like receptor 3 (TLR3) in pancreatic regeneration after acute pancreatitis (AP). AP was induced by caerulein treatment in mice with global TLR3 deficiency (TLR3^OFF ) or in mice re-expressing TLR3 exclusively in the myeloid cell lineage (TLR3^Mye ). Compared to WT mice, TLR3^OFF mice had a markedly increased formation of acinar-to-ductal metaplasia (ADM) that persisted until day 7 after initiation of AP. Pancreatic tissue of WT mice was completely regenerated after 5 days with no detectable ADM structures. The enhancing effect of TLR3-deficiency on ADM formation was closely linked with an increased and prolonged accumulation of macrophages in pancreata of TLR3^OFF mice. Importantly, the phenotype of TLR3^OFF mice was rescued in TLR3^Mye mice, demonstrating the causative role of myeloid cell selective TLR3 signaling. Moreover, in vitro stimulation of macrophages through TLR3 initiated cell death by a caspase-8-associated mechanism. Therefore, these findings provide evidence that TLR3 signaling in myeloid cells is sufficient to limit inflammation and ADM formation and to promote regeneration after AP. Notably, resolution of inflammation after AP was associated with macrophage sensitivity to TLR3-mediated cell death.

Neddylation pathway alleviates chronic pancreatitis by reducing HIF1α-CCL5-dependent macrophage infiltration

Chronic pancreatitis (CP) is characterized by a wide range of irreversible fibro-inflammatory diseases with largely ambiguous pathogenesis. Although neddylation pathway has been implicated in regulating immune responses, whether the dysregulation of neddylation is involved in the progression of CP and how neddylation regulates the inflammatory microenvironment of CP have not yet been reported. Here, we demonstrate that global inactivation of neddylation pathway by MLN4924 significantly exacerbates chronic pancreatitis. The increased M2 macrophage infiltration, mediated by the upregulated chemokine (C-C motif) ligand 5 (CCL5), is responsible for the enhanced pancreatitis-promoting activity of MLN4924. Both CCL5 blockade and macrophage depletion contribute to alleviating pancreatic fibrosis and inflammation in MLN4924-treated CP mice. Mechanistic investigation identifies that inactivation of Cullin-RING ligases (CRLs) stabilizes cellular levels of hypoxia-inducible factor 1α (HIF-1α), which increases CCL5 expression by promoting CCL5 transactivation. Clinically, UBE2M expression remarkably decreases in human CP tissues compared with normal specimens and the levels of CCL5 and M2 marker CD163 are negatively correlated with UBE2M intensity, suggesting that neddylation is involved in the pathogenesis of pancreatitis. Hence, our studies reveal a neddylation-associated immunopathogenesis of chronic pancreatitis and provide new ideas for the disease treatment.

The Role of Pancreatic Infiltrating Innate Immune Cells in Acute Pancreatitis

Acute pancreatitis (AP) is a leading cause of gastrointestinal-related hospital admissions with significant morbidity and mortality. Although the underlying pathophysiology of AP is rather complex, which greatly limits the treatment options, more and more studies have revealed that infiltrating immune cells play a critical role in the pathogenesis of AP and determine disease severity. Thus, immunomodulatory therapy targeting immune cells and related inflammatory mediators is expected to be a novel treatment modality for AP which may improve the prognosis of patients. Cells of the innate immune system, including macrophages, neutrophils, dendritic cells, and mast cells, represent the majority of infiltrating cells during AP. In this review, an overview of different populations of innate immune cells and their role during AP will be discussed, with a special focus on neutrophils and macrophages.

Alcohol and Smoking Mediated Modulations in Adaptive Immunity in Pancreatitis

Pancreatitis is a condition of pancreatic inflammation driven by injury to the pancreatic parenchyma. The extent of acinar insult, intensity, and type of immune response determines the severity of the disease. Smoking, alcohol and autoimmune pancreatitis are some of the predominant risk factors that increase the risk of pancreatitis by differentially influencing the adaptive immune system. The overall decrease in peripheral lymphocyte (T-, B- and (natural killer T-) NKT-cell) count and increased infiltration into the damaged pancreatic tissue highlight the contribution of adaptive immunity in the disease pathology. Smoking and alcohol modulate the responsiveness and apoptosis of T- and B-cells during pancreatic insult. Acute pancreatitis worsens with smoking and alcohol, leading to the development of systemic inflammatory response syndrome and compensatory anti-inflammatory response syndrome, suggesting the critical role of adaptive immunity in fatal outcomes such as multiple organ dysfunction. The presence of CD4⁺ and CD8⁺ T-lymphocytes and perforin-expressing cells in the fibrotic tissue in chronic pancreatitis modulate the severity of the disease. Due to their important role in altering the severity of the disease, attempts to target adaptive immune mediators will be critical for the development of novel therapeutic interventions.

The early predictive value of routine laboratory tests on the severity of acute pancreatitis patients in pregnancy: a retrospective study

Acute pancreatitis in pregnancy (APIP) varies in severity from a self-limiting mild condition to a severe life-threatening condition, and its severity is significantly correlated with higher risks of maternal and foetal death. This study evaluated the early predictive value of routine laboratory tests on the severity of APIP patients. We enrolled 100 patients with APIP in West China Hospital. Initial routine laboratory tests, including the biochemistry and hematologic tests were collected within 48 hours after the onset of APIP. For predicting SAP in AP, LDH had the highest specificity of 0.879. RDW was a suitable predictive marker as it had the sensitivity of 0.882. Lower levels of triglycerides (<4.72 mmol/L) predicted mild AP of APIP, with an area under the curve (AUC) of 0.724, and a negative predictive value of 0.80. Furthermore, a risk score was calculated based on white blood cells, neutrophils, RDW, LMR and LDH, as an independent marker (adjusted odds ratio = 3.013, 95% CI 1.893 to 4.797, P < 0.001), with the highest AUC of 0.906, a sensitivity of 0.875 and a specificity of 0.828. In conclusion, the risk score we recommended was the powerful marker to aid in the early prediction of the severity of APIP patients.

T Lymphocytes: A Promising Immunotherapeutic Target for Pancreatitis and Pancreatic Cancer?

Pancreatic disorders cause a broad spectrum of clinical diseases, mainly including acute and chronic pancreatitis and pancreatic cancer, and are associated with high global rates of morbidity and mortality. Unfortunately, the pathogenesis of pancreatic disease remains obscure, and there is a lack of specific treatments. T lymphocytes (T cells) play a vital role in the adaptive immune systems of multicellular organisms. During pancreatic disease development, local imbalances in T-cell subsets in inflammatory and tumor environments and the circulation have been observed. Furthermore, agents targeting T cells have been shown to reverse the natural course of pancreatic diseases. In this review, we have discussed the clinical relevance of T-cell alterations as a potential outcome predictor and the underlying mechanisms, as well as the present status of immunotherapy targeting T cells in pancreatitis and neoplasms. The breakthrough findings summarized in this review have important implications for innovative drug development and the prospective use of immunotherapy for pancreatitis and pancreatic cancer.

Myeloid-specific dopamine D2 receptor signalling controls inflammation in acute pancreatitis via inhibiting M1 macrophage

BACKGROUND AND PURPOSE

Macrophage infiltration and activation is a critical step during acute pancreatitis (AP). We have shown that pancreas-specific D₂ receptor signalling protects against AP severity. As it is unclear to what extent myeloid-specific D₂ receptor mediates AP, we investigated the role of myeloid-specific D₂ receptor signalling in AP.

EXPERIMENTAL APPROACH

Using wild-type and LysM^+/cre D₂ ^fl/fl mice, AP was induced by l-arginine, caerulein and LPS. Murine bone marrow-derived macrophages and human peripheral blood mononuclear cells (PBMCs) were isolated, cultured and then induced to M1 phenotype. AP severity was assessed by measurements of serum amylase and lipase and histological grading. Macrophage phenotype was assessed by flow cytometry and qRT-PCR. NADPH oxidase-induced oxidative stress and NF-κB and NLRP3 inflammasome signalling pathways were also evaluated.

KEY RESULTS

We found that dopaminergic system was activated and dopamine reduced inflammatory cytokine expression in M1-polarized macrophages from human PBMCs. Dopaminergic synthesis was also activated, but D₂ receptor expression was down-regulated in M1-polarized macrophages from murine bone marrows. During AP, myeloid-specific D₂ receptor deletion worsened pancreatic injury, systematic inflammation and promoted macrophages to M1 phenotype. Furthermore, M1 macrophages from LysM^+/cre D₂ ^fl/fl mice exhibited increased NADPH oxidase-induced oxidative stress and enhanced NF-κB and NLRP3 inflammasome activation. D₂ receptor activation inhibited M1 macrophage polarization, oxidative stress-induced NF-κB and NLRP3 inflammasome activation.

CONCLUSION AND IMPLICATIONS

Our data for the first time showed that myeloid-specific D₂ receptor signalling controls pancreatic injury and systemic inflammation via inhibiting M1 macrophage, suggesting D₂ receptor activation might serve as therapeutic target for AP.

Characteristics of Long Noncoding RNAs in the Pancreas of Rats With Acute Pancreatitis

OBJECTIVE

Long noncoding RNAs (lncRNAs) have received increasing attention as potential regulators of several biological processes. However, the precise effects of lncRNAs in acute pancreatitis (AP) have seldom been studied. This study aimed to describe the microarray-based differential expression profile of messenger RNA (mRNAs) and lncRNAs in AP and identify candidate biomarkers for the diagnosis, prognosis, and treatment of AP.

METHODS

A rat model of AP was generated with retrograde pancreatic ductal injection of sodium taurocholate, and the pancreas was harvested for microarray detection. The biological functions of differentially expressed mRNAs noted from microarray data were assessed by bioinformatics analysis. A coding-noncoding gene coexpression network was built for the most promising mRNAs, from which 10 lncRNAs were selected for subsequent validation by real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

There were 1156 lncRNAs and 3022 mRNAs distinctively dysregulated in rats with AP relative to the controls. The significantly enriched Gene Ontology term associated with upregulated mRNAs was immune system process. Kyoto Encyclopedia of Genes and Genomes functional analysis demonstrated that the upregulated transcripts were highly enriched in natural killer cell-mediated cytotoxicity.

CONCLUSIONS

Further research is needed to establish lncRNAs uc.308-, BC158811, BC166549, BC166474, and BC161988 as diagnostic and therapeutic targets.

Altered Bioenergetics of Blood Cell Sub-Populations in Acute Pancreatitis Patients

Acute pancreatitis (AP) is a debilitating, sometimes fatal disease, marked by local injury and systemic inflammation. Mitochondrial dysfunction is a central feature of pancreatic damage in AP, however, its involvement in circulating blood cell subtypes is unknown. This study compared mitochondrial bioenergetics in circulating leukocytes from AP patients and healthy volunteers: 15 patients with mild to severe AP were compared to 10 healthy controls. Monocytes, lymphocytes and neutrophils were isolated using magnetic activated cell sorting and mitochondrial bioenergetics profiles of the cell populations determined using a Seahorse XF24 flux analyser. Rates of oxygen consumption (OCR) and extracellular acidification (ECAR) under conditions of electron transport chain (ETC) inhibition (“stress” test) informed respiratory and glycolytic parameters, respectively. Phorbol ester stimulation was used to trigger the oxidative burst. Basal OCR in all blood cell subtypes was similar in AP patients and controls. However, maximal respiration and spare respiratory capacity of AP patient lymphocytes were decreased, indicating impairment of functional capacity. A diminished oxidative burst occurred in neutrophils from AP patients, compared to controls, whereas this was enhanced in both monocytes and lymphocytes. The data demonstrate important early alterations of bioenergetics in blood cell sub-populations from AP patients, which imply functional alterations linked to clinical disease progression.

Myeloid Cell-Derived HB-EGF Drives Tissue Recovery After Pancreatitis

BACKGROUND & AIMS

Pancreatitis is a major cause of morbidity and mortality and is a risk factor for pancreatic tumorigenesis. Upon tissue damage, an inflammatory response, made up largely of macrophages, provides multiple growth factors that promote repair. Here, we examine the molecular pathways initiated by macrophages to promote pancreas recovery from pancreatitis.

METHODS

To induce organ damage, mice were subjected to cerulein-induced experimental pancreatitis and analyzed at various times of recovery. CD11b-DTR mice were used to deplete myeloid cells. Hbegf^f/f;LysM-Cre mice were used to ablate myeloid cell-derived heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF). To ablate EGFR specifically during recovery, pancreatitis was induced in Egfr^f/f;Ptf1a^FlpO/+;FSF-Rosa26^CAG-CreERT2 mice followed by tamoxifen treatment.

RESULTS

Macrophages infiltrating the pancreas in experimental pancreatitis make high levels of HB-EGF. Both depletion of myeloid cells and ablation of myeloid cell HB-EGF delayed recovery from experimental pancreatitis, resulting from a decrease in cell proliferation and an increase in apoptosis. Mechanistically, ablation of myeloid cell HB-EGF impaired epithelial cell DNA repair, ultimately leading to cell death. Soluble HB-EGF induced EGFR nuclear translocation and methylation of histone H4, facilitating resolution of DNA damage in pancreatic acinar cells in vitro. Consistent with its role as the primary receptor of HB-EGF, in vivo ablation of EGFR from pancreatic epithelium during recovery from pancreatitis resulted in accumulation of DNA damage.

CONCLUSIONS

By using novel conditional knockout mouse models, we determined that HB-EGF derived exclusively from myeloid cells induces epithelial cell proliferation and EGFR-dependent DNA repair, facilitating pancreas healing after injury.

Early immune response in post endoscopic retrograde cholangiopancreatography pancreatitis as a model for acute pancreatitis

This opinion review summarizes comparison of clinical presentation and immunology of post-endoscopic pancreatitis and acute pancreatitis (AP) of other etiology. The rationale for this topic was found in studies that mention differences in clinical presentation between these entities, stating that severe form of AP after endoscopic retrograde cholangiopancreatography was more severe than AP of other etiology. Found difference in clinical presentation may have a background in different immunology that needs to be further investigated.

Heme oxygenase-1 induced by desoxo-narchinol-A attenuated the severity of acute pancreatitis via blockade of neutrophil infiltration

Heme oxygenase-1 (HO-1) has an anti-inflammatory action in acute pancreatitis (AP). However, its mechanism of action and natural compounds/drugs to induce HO-1 in pancreas are not well understood. In this study, we investigated the regulatory mechanisms of HO-1 during AP using desoxo-narchinol-A (DN), the natural compound inducing HO-1 in the pancreas. Female C57/BL6 Mice were intraperitoneally injected with supramaximal concentrations of cerulein (50 μg/kg) hourly for 6 h to induce AP. DMSO or DN was administered intraperitoneally, then mice were sacrificed 6 h after the final cerulein injection. Administration of DN increased pancreatic HO-1 expression through activation of activating protein-1, mediated by mitogen-activated protein kinases. Furthermore, DN treatment reduced the pancreatic weight-to-body weight ratio as well as production of digestive enzymes and pro-inflammatory cytokines. Inhibition of HO-1 by tin protoporphyrin IX abolished the protective effects of DN on pancreatic damage. Additionally, DN treatment inhibited neutrophil infiltration into the pancreas via regulation of chemokine (C-X-C motif) ligand 2 (CXCL2) by HO-1. Our results suggest that DN is an effective inducer of HO-1 in the pancreas, and that HO-1 regulates neutrophil infiltration in AP via CXCL2 inhibition.

The effect of thymosin α1 for prevention of infection in patients with severe acute pancreatitis

INTRODUCTION

Severe acute pancreatitis (SAP) is an acute inflammatory disease with prolonged clinical course, which is complicated by the presence of persistent organ failure and severe infection. Infection mainly occurs in the late phase of SAP and it is found to be the main cause of death. Therefore, developing strategies for the prevention of SAP-related infection has been a crucial approach to improve patients' outcomes. Due to remarkable immune-cells-regulating properties, thymosin α1 has been recognized as a promising immune therapy, especially in several infectious diseases. Recently, thymosin α1 has been given high expectations to exert clinical benefits in the prevention of SAP-related infection.

AREAS COVERED

The review of currently available strategies for SAP-related infection prevention and the use of thymosin α1 in SAP patients.

EXPERT OPINION

The current available strategies achieve limited success for preventing SAP-related infection. A possible explanation is that the trigger of infection, immunosuppression has not been concurrently resolved. The application of thymosin α1 in a clinical study showed a prophylactic effect against SAP-related infection. However, the use of thymosin α1 in SAP patients is still at an early stage of clinical investigation and requires high-quality and large sample size evidences.

The Prognostic Role of Peripheral Lymphocyte Subsets in Patients With Acute Pancreatitis

BACKGROUND

The prognostic role of peripheral lymphocyte subsets in early stage of acute pancreatitis (AP) is unknown.

METHODS

After enrollment, blood samples were collected in the first 24 hours of the onset of AP in 164 patients. The lymphocyte count and the percentage of CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺, CD3^-CD19⁺and CD3^-CD (16 + 56)⁺ cells were assessed.

RESULTS

Reduction of the lymphocyte count and the percentage of CD3⁺CD8⁺ and CD3^-CD (16 + 56)⁺ cells within 24 hours of the onset of AP as well as an increase in the percentage of CD3⁺ and CD3⁺CD4⁺ cells were observed. The percentage of CD3^-CD (16 + 56)⁺ cells had the highest accuracy in prediction of AP severity.

CONCLUSIONS

Marked changes of the percentages of lymphocyte subset were found in peripheral blood in the early stage of AP. The percentage of CD3^-CD (16 + 56)⁺ cells in peripheral blood could be a potent prognostic predictor.

Pediatric Pancreatitis-Molecular Mechanisms and Management

Pediatric pancreatitis is an emerging field with an increasing incidence of disease. Management of pediatric pancreatitis is understudied and, therefore, extrapolated from adult studies (although the etiologies are different). There is evidence that feeding is safe in mild acute pancreatitis in children without increased pain or length of stay. Studies are needed to predict course of the disease, disease severity, and risk of chronic pancreatitis in children.

IL-15 regulates fibrosis and inflammation in a mouse model of chronic pancreatitis

Pancreatitis is an inflammatory disease characterized by the induction of several proinflammatory cytokines like interleukin (IL)-6, IL-8, IL-1β, and IL-1. Recently, the multifunctional innate cytokine IL-15 has been implicated in the protection of several diseases, including cancer. Tissue fibrosis is one of the major problems in successfully treating chronic pancreatitis pathogenesis. Therefore, we tested the hypothesis that recombinant IL-15 (rIL-15) treatment may induce innate tissue responses and its overexpression will improve the pathogenesis of cerulein-induced chronic pancreatitis, associated remodeling, and fibrosis. We observed atrophy of acinar cells, increased inflammation, and increased deposition of perivascular collagen, the upregulated protein level of transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA), and collagen-1 in cerulein-induced chronic pancreatitis in mice. Furthermore, we reported that rIL-15 treatment protects mice from the cerulein-induced chronic pancreatitis pathogenesis, including acinar cell atrophy, and perivascular accumulation of tissue collagen followed by downregulation of profibrotic genes such as TGF-β1, α-SMA, collagen-1, collagen-3, and fibronectin in cerulein-induced chronic pancreatitis in mice. Mechanistically, we show that IL-15-mediated increase of interferon-γ-responsive invariant natural killer T (iNKT) cells in the blood and tissue protects cerulein-induced pancreatic pathogenesis in mice. Of note, a reduction in iNKT cells was also observed in human chronic pancreatitis compared with normal individuals. Taken together, these data suggest that IL-15 treatment may be a novel therapeutic strategy for treating chronic pancreatitis pathogenesis. NEW & NOTEWORTHY Pancreatic fibrosis is a major concern for the successful treatment of chronic pancreatitis and pancreatic cancer. Therefore, restriction in the progression of fibrosis is the promising approach to manage the pancreatitis pathogenesis. Herein, we present in vivo evidences that pharmacological treatment of recombinant interleukin-15 improves remodeling and fibrosis in cerulein-induced chronic pancreatitis in mice. Our observations indicate that interleukin-15 immunotherapy may be a possible and potential strategy for restricting the progression of fibrosis in chronic pancreatitis.

Endoscopic retrograde cholangiopancreatography-induced and non-endoscopic retrograde cholangiopancreatography-induced acute pancreatitis: Two distinct clinical and immunological entities?

Acute pancreatitis (AP) is common gastrointestinal disease of varied aetiology. The most common cause of AP is gallstones, followed by alcohol abuse as an independent risk factor. With the increased need for invasive techniques to treat pancreatic and bile duct pathologies such as endoscopic retrograde cholangiopancreatography (ERCP), AP has emerged as the most frequent complication. While severe AP following ERCP is rare (0.5%), if it does develop it has a greater severity index compared to non-ERCP AP. Development of a mild form of AP after ERCP is not considered a clinically relevant condition. Differences in the clinical presentation and prognosis of the mild and severe forms have been found between non-ERCP AP and post-endoscopic pancreatitis (PEP). It has been proposed that AP and PEP may also have different immunological responses to the initial injury. In this review, we summarise the literature on clinical and inflammatory processes in PEP vs non-ERCP AP.

Adaptive Immune Cell Dysregulation and Role in Acute Pancreatitis Disease Progression and Treatment

Acute pancreatitis (AP) is an inflammation of the pancreas caused by various stimuli including excessive alcohol consumption, gallstone disease and certain viral infections. Managing specifically the severe form of AP is limited due to lack of an understanding of the complex immune events that occur during AP involving immune cells and inflammatory molecules such as cytokines. The relative abundance of various immune cells resulting from the immune dysregulation drives disease progression. In this review, we examine the literature on the adaptive immune cells in AP, the prognostic value of these cells in stratifying patients into appropriate care and treatment strategies based on cell frequency in different AP severities are discussed.

Circulating CD14+CD163+CD115+ M2 monocytes are associated with the severity of new onset severe acute pancreatitis in Chinese patients

BACKGROUND

Despite the role of monocytes in the pathogenesis of severe acute pancreatitis (SAP), it remains unclear how different subtypes of monocytes regulate and contribute to this pathogenesis.

METHODS

We examined the numbers of different subsets of monocytes by flow cytometry in 21 SAP, 15 mild acute pancreatitis (MAP) and 13 healthy controls (HC). The concentrations of plasma cytokines were assessed by cytometric bead array. Disease severity was evaluated based on the acute physiology and chronic health evaluation (APACHE) II score and plasma C-reactive proteins (CRP) levels.

RESULTS

Compared with the numbers in MAP patients and HC, we observed that the numbers of CD14⁺CD163^-, CD14⁺CD163^-MAC387⁺, CD14⁺CD163^-IL-12⁺ M1 monocytes, and CD115⁺, CD204⁺, IL-10⁺ M2 monocytes were significantly increased in SAP patients. In addition, these patients showed higher plasma levels of interleukin (IL)-12 and IL-10. Furthermore, the number of CD14⁺CD163^-, CD14⁺CD163^-MAC387⁺ M1 monocytes and the plasma IL-12 concentration showed a positive association with the CRP level, while the number of CD204⁺, IL-10⁺ M2 monocytes and the plasma IL-10 concentration showed a positive correlation with the APACHE II score. Importantly, the CD115⁺ M2 subset displayed a positive correlation with both the CRP level and APACHE II score, and treatment of SAP significantly reduced the number of this subset.

CONCLUSIONS

The CD14⁺CD163⁺CD115⁺ M2 monocyte count appears to be important factor in determining the severity and prognosis of SAP. Both the pro- and anti-inflammatory monocytes appear to participate in the pathogenesis of SAP.

Dopamine D2 receptor signalling controls inflammation in acute pancreatitis via a PP2A-dependent Akt/NF-κB signalling pathway

BACKGROUND AND PURPOSE

Dopamine has multiple anti-inflammatory effects, but its role and molecular mechanism in acute pancreatitis (AP) are unclear. We investigated the role of dopamine signalling in the inflammatory response in AP.

EXPERIMENTAL APPROACH

Changes in pancreatic dopaminergic system and effects of dopamine, antagonists and agonists of D1 and D2 dopamine receptors were analysed in wild-type and pancreas-specific Drd2-/- mice with AP (induced by caerulein and LPS or L-arginine) and pancreatic acinar cells with or without cholecystokinin (CCK) stimulation. The severity of pancreatitis was assessed by measuring serum amylase and lipase and histological assessments. The NF-κB signalling pathway was evaluated, and macrophage and neutrophil migration assessed by Transwell assay.

KEY RESULTS

Pancreatic dopamine synthetase and metabolic enzyme levels were increased, whereas D1 and D2 receptors were decreased in AP. Dopamine reduced inflammation in CCK-stimulated pancreatic acinar cells by inhibiting the NF-κB pathway. Moreover, the protective effects of dopamine were blocked by a D2 antagonist, but not a D1 antagonist. A D2 agonist reduced pancreatic damage and levels of p-IκBα, p-NF-κBp65, TNFα, IL-1β and IL-6 in AP. Pancreas-specific Drd2-/- aggravated AP. Also, the D2 agonist activated PP2A and inhibited the phosphorylation of Akt, IKK, IκBα and NF-κB and production of inflammatory cytokines and chemokines. Furthermore, it inhibited the migration of macrophages and neutrophils by reducing the expression of CCL2 and CXCL2. A PP2A inhibitor attenuated these protective effects of the D2 agonist.

CONCLUSIONS AND IMPLICATIONS

D2 receptors control pancreatic inflammation in AP by inhibiting NF-κB activation via a PP2A-dependent Akt signalling pathway.

Indomethacin inhabits the NLRP3 inflammasome pathway and protects severe acute pancreatitis in mice

Clinical studies have confirmed that indomethacin (Indo) can reduce the incidence and severity of post-endoscopicretrogradecholangio-pancreatography pancreatitis (PEP) effectively. However, the role of Indo on severe acute pancreatitis (SAP) is not clear. In the present study, we aimed to explore the effects of Indo treatment on SAP model induced by caerulein combined with lipopolysaccharide. After intraperitoneal injection of Indo in mice, both the severity of SAP and the serum levels of amylase, lipase, and proinflammatory cytokines were decreased. Furthermore, the mRNA and protein levels of NLRP3 inflammasome pathway (NLRP3,ASC and IL-1β) in pancreatic tissues were down-regulated. In vitro experiments, by isolating the pancreatic acinar cells (PACs) from mice, we found that Indo significantly reduced lactate dehydrogenase(LDH) excretion, increased the cell activity, and inhibited the NLRP3 inflammasome pathway of PACs. Taken together, our data showed that Indo could protect pancreatic acinar cell from injury by inhabiting NLRP3 pathway and decreased the severity of SAP accordingly.

Novel and Experimental Therapies in Chronic Pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disease of the pancreas. The currently available treatment of CP is aimed at controlling symptoms and managing complications. Unfortunately, no specific treatment is available to halt the progression of the disease process because the pathophysiological perturbations in CP are not well understood. In this review, we discuss various therapeutic targets and investigational agents acting on these targets. Among these, therapies modulating immune cells and those acting on pancreatic stellate cells appear promising and may translate into clinical benefit in near future. However, these experimental therapies are mostly in animal models and they do not recapitulate all aspects of human disease. Still they may be beneficial in developing effective therapeutic modalities to curb inflammation in chronic pancreatitis.

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.

Comparison of the prognostic values of inflammation markers in patients with acute pancreatitis: a retrospective cohort study

OBJECTIVES

Inflammation-based prognostic markers (neutrophil-lymphocyte ratio (NLR), prognostic nutritional index (PNI), red cell distribution width (RDW) and lymphocyte-monocyte ratio (LMR)) are associated with overall survival in some diseases. This study assessed their prognostic value in mortality and severity in acute pancreatitis (AP).

DESIGN

A retrospective cohort study.

SETTING

Patients with AP were recruited from the emergency department at our hospital.

PARTICIPANTS

A total of 359 patients with AP (31 non-survivors) were enrolled.

PRIMARY AND SECONDARY OUTCOME MEASURES

Mortality and severity of AP were the primary and secondary outcome measures, respectively. Biochemistry and haematology results of the first test after admission were collected. Independent relationships between severe AP (SAP) and markers were assessed using multivariate logistic regression models. Mortality prediction ability was evaluated using receiver operating characteristic (ROC) curves. Overall survival was evaluated using the Kaplan-Meier method, with differences compared using the log-rank test. Independent relationships between mortality and each predictor were estimated using the Cox proportional hazard models.

RESULTS

Compared with survivors of AP, non-survivors had higher RDW (p<0.001), higher NLR (p<0.001), lower LMR (p<0.001) and lower PNI (p<0.001) at baseline. C reactive protein (CRP; OR=8.251, p<0.001), RDW (OR=2.533, p=0.003) and PNI (OR=7.753, p<0.001) were independently associated with the occurrence of SAP. For predicting mortality, NLR had the largest area under the ROC curve (0.804, p<0.001), with a 16.64 cut-off value, 82.4% sensitivity and 75.6% specificity. RDW was a reliable marker for excluding death owing to its lowest negative likelihood ratio (0.11). NLR (HR=4.726, p=0.004), CRP (HR=3.503, p=0.003), RDW (HR=3.139, p=0.013) and PNI (HR=2.641, p=0.011) were independently associated with mortality of AP.

CONCLUSIONS

NLR was the most powerful marker of overall survival in this patient series.