Role of macrophages in the progression of acute pancreatitis

Electroacupuncture Improves Ovarian Function in Rats With Tripterygium Glycoside-Induced Diminished Ovarian Reserve by Promoting the Polarization of M2 Macrophages and Inhibiting Inflammatory Responses

Immunoinflammatory responses and macrophage polarisation are crucial for maintaining ovarian function. Moreover, electroacupuncture (EA) has been shown to protect ovarian function. However, the mechanisms by which EA improves ovarian function, including its effects on immunoinflammatory responses and macrophage polarisation, have not been determined. This study aimed to investigate the protective effects of EA on ovarian function in rats with diminished ovarian reserve (DOR) and to elucidate the regulatory mechanisms underlying inflammation and M1 and M2 macrophage polarisation. DOR models were established through the intragastric administration of 50 mg/kg Tripterygium glycoside suspension (TGs) for 14 consecutive days. The EA group received treatment at 2/100 Hz and 1.0 mA for 10 min using acupoints BL23, CV4 and CV12 for 14 days. Following the intervention, we employed various methodologies, including haematoxylin-eosin (H&E) staining, enzyme-linked immunosorbent assay (ELISA), flow cytometry, immunohistochemical (IHC) staining, western blotting and quantitative reverse transcriptase-polymerase chain reaction (PCR), to assess ovarian function, inflammatory factors and the expression levels of M1 and M2 macrophage-related factors. EA intervention reduced the oestrous cycle disorder rate in the rats compared with that in the DOR group, leading to an increase in growing follicles, a reduction in atretic follicles (AFs) and an enhancement of both the capillary (Cap) network and corpus luteum (CL) structure. This intervention also resulted in decreased serum levels of follicle-stimulating hormone (FSH), interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α), along with increased levels of oestradiol (E2), interleukin-4 (IL-4) and interleukin-10 (IL-10). Furthermore, the number of M2 macrophages in the spleen increased, which was accompanied by elevated arginase 1 (Arg1) and decreased inducible nitric oxide synthase (iNOS) expression in the ovarian tissues. In summary, EA can restore the impaired ovarian function caused by TGs by promoting M2 macrophage polarisation and inhibiting inflammatory responses.

Exosomes Derived From Cerulein-Stimulated Pancreatic Acinar Cells Mediate Peritoneal Macrophage M1 Polarization and Pyroptosis via an miR-24-3p/MARCH3/NLRP3 Axis in Acute Pancreatitis

OBJECTIVES

Acute pancreatitis (AP) has a high incidence of hospitalizations, morbidity, and mortality worldwide. A growing number of studies on AP pathogenesis are based on cerulein-induced experimental model, which simulates human AP in vivo. It has been demonstrated that both pancreatic acinar cells and peritoneal macrophages are involved in pancreatic inflammation and damage. However, their connection has not been well understood.

METHODS

A cerulein-induced AP model was established on the pancreatic acinar cell line AR42J. Rat macrophages were isolated from the peritoneal cavity. The effects of cerulein-induced pancreatic exosomes on the peritoneal macrophage and pancreas in vivo and in vitro were examined. The underlying molecular mechanism was investigated by exploring the regulatory role of downstream molecules.

RESULTS

We found that exosomes derived from cerulein-treated AR42J cells induced rat peritoneal macrophage M1 polarization and pyroptosis. miR-24-3p was upregulated in cerulein-stimulated exosomes, whereas the miR-24-3p inhibitor counteracted the effect of pancreatic exosomes on peritoneal macrophage M1 polarization and pyroptosis. Furthermore, miR-24-3p inhibited March3 expression, whereas MARCH3 mediated NLRP3 ubiquitination in rat peritoneal macrophages, which, in turn, contributed to the apoptosis, reactive oxygen species production, and inflammation in AR42J cells.

CONCLUSIONS

Exosomes derived from cerulein-stimulated pancreatic acinar cells mediate peritoneal macrophage M1 polarization and pyroptosis via an miR-24-3p/MARCH3/NLRP3 axis in AP.

The Pivotal Role of Macrophages in the Pathogenesis of Pancreatic Diseases

The pancreas is an organ with both exocrine and endocrine functions, comprising a highly organized and complex tissue microenvironment composed of diverse cellular and non-cellular components. The impairment of microenvironmental homeostasis, mediated by the dysregulation of cell-to-cell crosstalk, can lead to pancreatic diseases such as pancreatitis, diabetes, and pancreatic cancer. Macrophages, key immune effector cells, can dynamically modulate their polarization status between pro-inflammatory (M1) and anti-inflammatory (M2) modes, critically influencing the homeostasis of the pancreatic microenvironment and thus playing a pivotal role in the pathogenesis of the pancreatic disease. This review aims to summarize current findings and provide detailed mechanistic insights into how alterations mediated by macrophage polarization contribute to the pathogenesis of pancreatic disorders. By analyzing current research comprehensively, this article endeavors to deepen our mechanistic understanding of regulatory molecules that affect macrophage polarity and the intricate crosstalk that regulates pancreatic function within the microenvironment, thereby facilitating the development of innovative therapeutic strategies that target perturbations in the pancreatic microenvironment.

The Pathogenesis of Pancreatitis and the Role of Autophagy

The pathogenesis of acute and chronic pancreatitis has recently evolved as new findings demonstrate a complex mechanism operating through various pathways. In this review, the current evidence indicating that several mechanisms act in concert to induce and perpetuate pancreatitis were presented. As autophagy is now considered a fundamental mechanism in the pathophysiology of both acute and chronic pancreatitis, the fundamentals of the autophagy pathway were discussed to allow for a better understanding of the pathophysiological mechanisms of pancreatitis. The various aspects of pathogenesis, including trypsinogen activation, ER stress and mitochondrial dysfunction, the implications of inflammation, and macrophage involvement in innate immunity, as well as the significance of pancreatic stellate cells in the development of fibrosis, were also analyzed. Recent findings on exosomes and the miRNA regulatory role were also presented. Finally, the role of autophagy in the protection and aggravation of pancreatitis and possible therapeutic implications were reviewed.

Novel therapeutics to treat chronic pancreatitis: targeting pancreatic stellate cells and macrophages

INTRODUCTION

Chronic pancreatitis (CP) is a persistent, recurrent, and progressive disorder that is characterized by chronic inflammation and irreversible fibrosis of the pancreas. It is associated with severe morbidity, resulting in intense abdominal pain, diabetes, exocrine and endocrine dysfunction, and an increased risk of pancreatic cancer. The etiological factors are diverse and the major risk factors include smoking, chronic alcoholism, as well as other environmental and genetic factors. The treatment and management of CP is challenging, and no definitive curative therapy is currently available.

AREAS COVERED

This review paper aims to provide an overview of the different cell types in the pancreas that is known to mediate disease progression and outline potential novel therapeutic approaches and drug targets that may be effective in treating and managing CP. The information presented in this review was obtained by conducting a NCBI PubMed database search, using relevant keywords.

EXPERT OPINION

In recent years, there has been an increased interest in the development of novel therapeutics for CP. A collaborative multi-disciplinary approach coupled with a consistent funding for research can expedite progress of translating the findings from bench to bedside.

KAN0438757, a novel PFKFB3 inhibitor, prevent the progression of severe acute pancreatitis via the Nrf2/HO-1 pathway in infiltrated macrophage

Acute pancreatitis (AP) is a non-infectious pancreatic enzyme-induced disorder, a life-threatening inflammatory condition that can cause multi-organ dysfunction, characterized by high morbidity and mortality. Several therapies have been employed to target this disorder; however, few happen to be effectively employable even in the early phase. PFKFB3(6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-3) is a critical regulator of glycolysis and is upregulated under inflammatory, mitogenic, and hypoxia conditions. Essential information on the targeting of the inflammatory pathway will present the termination of the disorder and recovery. Herein we investigated the protective function of KAN0438757, a potent inhibitor of PFKFB3, and its mechanism of impeding AP induced in mice. KAN0438757 was confirmed to activate the Nrf2/HO-1 inflammatory signaling pathways in response to caerulein induced acute pancreatitis (CAE-AP) and fatty acid ethyl ester induced severe acute pancreatitis (FAEE-SAP). Additionally, KAN0438757 alleviated the inflammatory process in infiltrated macrophage via the Nrf2/HO-1 inflammatory signaling pathway and demonstrated a significant effect on the growth of mice with induced AP. And more importantly, KAN0438757 displayed negligible toxicity in vivo. Taken together our data suggest KAN0438757 directly suppresses the inflammatory role of PFKFB3 and induces a protective role via the Nrf2/HO-1 pathway, which could prove as an excellent therapeutic platform for SAP amelioration.

Role of lncRNAs in acute pancreatitis: pathogenesis, diagnosis, and therapy

Acute pancreatitis (AP) is one of the most common acute abdominal diseases characterized by an injury and inflammatory disorder of the pancreas with complicated pathological mechanisms. Long non-coding RNAs (lncRNAs) have been shown to play an important role in various physiological and pathological processes in humans, and they have emerged as potential biomarkers of diagnosis and therapeutic targets in various diseases. Recently, accumulating evidence has shown significant alterations in the expression of lncRNAs, which are involved in the pathogenesis of AP, such as premature trypsinogen activation, impaired autophagy, inflammatory response, and acinar cell death. Moreover, lncRNAs can be the direct target of AP treatment and show potential as biomarkers for the diagnosis. Thus, in this review, we focus on the role of lncRNAs in the pathogenesis, diagnosis, and therapy of AP and emphasize the future directions to study lncRNAs in AP, providing new insight into understanding the cellular and molecular mechanisms of AP and seeking novel biomarkers for the diagnosis and therapeutic targets to improve clinical management in the future.

Disulfiram relieves severe acute pancreatitis by inhibiting GSDMD-dependent NETs formation

OBJECTIVES

Severe acute pancreatitis (SAP) is characterized by pancreatic and systemic inflammation and persistent organ failure. Neutrophil extracellular traps (NETs) are considered to play an important role in the development of SAP. We aimed to explore the effect of disulfiram (DSL), a newly developed anti-inflammatory drug, on NETs in SAP.

METHODS

A mouse model of SAP was induced by caerulein and lipopolysaccharide, and the mice were divided into the normal control group, the DSL group, the SAP group, and the SAP treated with 50 mg/kg (50DSLSAP) and 100 mg/kg DSL (100DSLSAP) groups, respectively. The severity of SAP was evaluated based on the morphological and biochemical changes. Gasdermin D (GSDMD) expression was evaluated in vivo and in vitro to verify the effect of DSL. Additionally, the expressions of NETs were also evaluated in vivo and in vitro in SAP with and without DSL treatment to explore the possible mechanism of DSL on SAP.

RESULTS

Pancreatic inflammatory injury increased in the SAP group, which was alleviated by DSL. GSDMD, a protein related to the formation of NETs, increased in SAP. Expressions of NETs were also promoted in the in vivo SAP model and by phorbol myristate acetate (PMA) in vitro. Moreover, DSL inhibited the expressions of GSDMD and NETs in vivo. The results were further confirmed in the in vitro experiment.

CONCLUSIONS

NETs are highly associated with inflammatory injury in SAP. DSL inhibits NETs formation by downregulating GSDMD, which in turn relieves the inflammation of SAP. Our study may provide a possible therapeutic target for SAP.

Tricetin Reduces Inflammation and Acinar Cell Injury in Cerulein-Induced Acute Pancreatitis: The Role of Oxidative Stress-Induced DNA Damage Signaling

Acute pancreatitis (AP) poses a worldwide challenge due to the growing incidence and its potentially life-threatening course and complications. Specific targeted therapies are not available, prompting the identification of new pathways and novel therapeutic approaches. Flavonoids comprise several groups of biologically active compounds with wide-ranging effects. The flavone compound, tricetin (TCT), has not yet been investigated in detail but sporadic reports indicate diverse biological activities. In the current study, we evaluated the potential protective effects of TCT in AP. TCT (30 μM) protected isolated primary murine acinar cells from the cytotoxic effects of cerulein, a cholecystokinin analog peptide. The protective effects of TCT were observed in a general viability assay (calcein ester hydrolysis), in an apoptosis assay (caspase activity), and in necrosis assays (propidium iodide uptake and lactate dehydrogenase release). The effects of TCT were not related to its potential antioxidant effects, as TCT did not protect against H2O2-induced acinar cell death despite possessing radical scavenging activity. Cerulein-induced expression of IL1β, IL6, and matrix metalloproteinase 2 and activation of nuclear factor-κB (NFκB) were reduced by 30 μM TCT. In vivo experiments confirmed the protective effect of TCT in a mouse model of cerulein-induced AP. TCT suppressed edema formation and apoptosis in the pancreas and reduced lipase and amylase levels in the serum. Moreover, TCT inhibited interleukin-1β (IL1β), interleukin-6 (IL6), and tumor necrosis factor-α (TNFα) expression in the pancreas and reduced the activation of the oxidative DNA damage sensor enzyme poly(ADP-ribose) polymerase-1 (PARP-1). Our data indicate that TCT can be a potential treatment option for AP.

Emodin Ameliorates Acute Pancreatitis-Associated Lung Injury Through Inhibiting the Alveolar Macrophages Pyroptosis

Objective: To investigate the protective effect of emodin in acute pancreatitis (AP)-associated lung injury and the underlying mechanisms. Methods: NaT-AP model in rats was constructed using 3.5% sodium taurocholate, and CER+LPS-AP model in mice was constructed using caerulein combined with Lipopolysaccharide. Animals were divided randomly into four groups: sham, AP, Ac-YVAD-CMK (caspase-1 specific inhibitor, AYC), and emodin groups. AP-associated lung injury was assessed with H&E staining, inflammatory cytokine levels, and myeloperoxidase activity. Alveolar macrophages (AMs) pyroptosis was evaluated by flow cytometry. In bronchoalveolar lavage fluid, the levels of lactate dehydrogenase and inflammatory cytokines were measured by enzyme-linked immunosorbent assay. Pyroptosis-related protein expressions were detected by Western Blot. Results: Emodin, similar to the positive control AYC, significantly alleviated pancreas and lung damage in rats and mice. Additionally, emodin mitigated the pyroptotic process of AMs by decreasing the level of inflammatory cytokines and lactate dehydrogenase. More importantly, the protein expressions of NLRP3, ASC, Caspase1 p10, GSDMD, and GSDMD-NT in AMs were significantly downregulated after emodin intervention. Conclusion: Emodin has a therapeutic effect on AP-associated lung injury, which may result from the inhibition of NLRP3/Caspase1/GSDMD-mediated AMs pyroptosis signaling pathways.

Tuftsin ameliorates splenic inflammatory injury by promoting neuropilin-1 in severe acute pancreatitis

Severe acute pancreatitis (SAP)-associated spleen injury causing immune disturbances aggravates organs injuries, which contributes to higher mortality rate. However, there are no effective drugs to cure SAP-induced spleen injury. Here, we found that Tuftsin (TN) is effective for ameliorating SAP-induced pathological damage and inflammation of spleen, mainly via alleviating mitochondrial dysfunction, oxidative stress, ATP depletion and the expression of pro-inflammatory factors. We further found that TN promoted anti-inflammatory macrophage phenotype M2 via up-regulating NRP1 on macrophage in spleen during SAP. Meanwhile, EG00229 (an inhibitor of NRP1 bound to TN) weakened TN's therapeutic effect in SAP-associated spleen injury. And EG00229 also inhibited M2 macrophage, leading to increasing inflammasome formation. Additionally, EG00229 reduced the protective efficiency of TN on mitochondrial dysfunction, and inflammation injury via NRP1 in spleen caused by SAP. Similarly, siRNA-Nrp1 into macrophage also prevented TN's inhibition on apoptosis. These findings reveal that TN alleviates SAP-induced spleen injury by promoting NRP1.

Excess fatty acids induce pancreatic acinar cell pyroptosis through macrophage M1 polarization

Free fatty acid derived from hyperlipidemia contributes to the development of inflammation in the pancreas. Here we explore the molecular mechanisms of fatty acid-induced pancreatitis through cellular experiments and the construction of a mouse model of hyperlipidemic pancreatitis. We found that palmitic acid stimulation leads to M1 polarization of macrophage, which secretes cathepsin S via exosomes to pancreatic acinar cells and leads to activation of the caspase1-mediated classical pyrolysis pathway, resulting in inflammation and pancreatic tissue damage. In vivo experiments have also demonstrated that the high levels of fatty acids induced by hyperlipidaemia exacerbate the development of pancreatitis, and that cathepsin S inhibitors significantly alleviate hyperlipidemic pancreatitis. Therefore, cathepsin S may be a new target for the clinical treatment of hyperlipidemic pancreatitis.

Cytokines and inflammatory mediators: Markers involved in interstitial damage to the pancreas in two dengue fever cases associated with acute pancreatitis

Dengue viral (DENV) infections can lead to acute pancreatitis and associated tissue damage. This study examined the pancreas from two fatal cases of DENV for histopathological changes as well as for the detection of cytokines, and other inflammatory mediators. Tissue sections were prepared for examination by ultrastructural and histopathological techniques. Sections from the pancreas of non-infected individuals were prepared in parallel as a control. The presence of viral replication in macrophages was detected by co-staining for the proteins NS3 and CD68 by immunofluorescence. Immunohistochemistry was used to detect cells that expressed cytokines and inflammatory mediators to characterize the inflammatory response. Edema, acinar necrosis and fibrosis areas associated with a mononuclear infiltrate were found in infected tissues. The major site of virus replication appeared to be macrophages based on their exclusive presentation of the viral protein NS3. Pancreatic tissues from the infected individuals also displayed increased levels of high mobility group box-1, caspase-3, gelatinase B and tumor necrosis factor alpha compared to controls. The presence of virus replicating macrophages in the pancreas was associated with multiple changes in tissue structure that included elevated levels of cytokines and inflammatory markers that may differentiate acute pancreatitis due to DENV infections from other causes.

Netrin-1: A Modulator of Macrophage Driven Acute and Chronic Inflammation

Netrins belong to the family of laminin-like secreted proteins, which guide axonal migration and neuronal growth in the developing central nervous system. Over the last 20 years, it has been established that netrin-1 acts as a chemoattractive or chemorepulsive cue in diverse biological processes far beyond neuronal development. Netrin-1 has been shown to play a central role in cell adhesion, cell migration, proliferation, and cell survival in neuronal and non-neuronal tissue. In this context, netrin-1 was found to orchestrate organogenesis, angiogenesis, tumorigenesis, and inflammation. In inflammation, as in neuronal development, netrin-1 plays a dichotomous role directing the migration of leukocytes, especially monocytes in the inflamed tissue. Monocyte-derived macrophages have long been known for a similar dual role in inflammation. In response to pathogen-induced acute injury, monocytes are rapidly recruited to damaged tissue as the first line of immune defense to phagocyte pathogens, present antigens to initiate the adaptive immune response, and promote wound healing in the resolution phase. On the other hand, dysregulated macrophages with impaired phagocytosis and egress capacity accumulate in chronic inflammation sites and foster the maintenance-and even the progression-of chronic inflammation. In this review article, we will highlight the dichotomous roles of netrin-1 and its impact on acute and chronic inflammation.

Thymol regulates the functions of immune cells in the rat peritoneal cavity after l-arginine-induced pancreatitis

AIMS

The present study aimed to evaluate the protective action of thymol towards l-arginine-induced acute pancreatitis (AP) by studying the function of rat peritoneal immune cells.

MAIN METHODS

Rat peritoneal exudate cells (PECs), obtained 24 h after the injection of l-arginine (350 mg/100 g of b.w.), were evaluated for mitochondrial activity (MTT assay), adherence capacity (methylene-blue assay), and phagocyte enzyme activity (myeloperoxidase, MPO, assay). The activity of α-amylase and free MPO, as well as the concentration of reactive oxygen species (ROS, i.e. O2-), were determined in the peritoneal exudate fluid. Also, serum α-amylase activity determination and pancreatic tissue pathohistological analysis were performed.

KEY FINDING

The administered thymol (50 and 100 mg/kg, per os) caused a significant decrease in the PEC mitochondrial activity and adherence capacity when compared with these functions of PECs isolated from rats with AP. A decrease in cellular MPO activity, as well as in the levels of ROS, α-amylase, and free MPO in peritoneal exudates was found in animals treated with thymol compared to the control animals with AP. Additionally, thymol administration prevented an increase in serum α-amylase activity, accompanied by the decrease in pancreatic tissue damage that follows l-arginine application.

SIGNIFICANCE

The present results showed that thymol exerts significant immunomodulatory properties and a potential to silence PEC functions in inflammatory conditions such as the AP induced by l-arginine.

Cytotoxicity and Inflammatory Mediators Release by Macrophages Exposed to Real Seal XT and Sealapex Xpress

This study evaluated the cytotoxicity of Sealapex Xpress and Real Seal XT and their effect on macrophage activation. J774.1 macrophages were incubated with Sealapex Xpress and Seal Real XT (0.1, 1.0, and 10 mg/mL) for 24 and 48 h. Cell viability was assessed by the MTT assay and macrophage activation was measured by pro- and anti-inflammatory cytokine production using ELISA. Data were analyzed using one-way ANOVA and Tukey's post-test (a=0.05). Cell viability was not affected with 0.1 or 1.0 mg/mL of extracts of Sealapex Xpress and Real Seal XT at 24 and 48 h (p>0.05), but was significantly lower when cells were exposed to 10 mg/mL of both sealers (p<0.05). Sealapex Xpress inhibited the production of TNF-a, whereas Real Seal XT induced TNF-a secretion at 24 h (p<0.05). IL-6 production was induced by Real Seal XT, but not by Sealapex Xpress (p<0.05). Real Seal XT and Sealapex Xpress induced the secretion of anti-inflammatory IL-10. IL-4 was not detected in any group. In conclusion, both sealers had low toxicity but differentially activated macrophages. Macrophage activation by Sealapex Xpress was characterized by inhibition of TNF-a and induction of IL-10, whereas Real Seal XT induced IL-6 solely.

Intestinal bacterial overgrowth in the early stage of severe acute pancreatitis is associated with acute respiratory distress syndrome

BACKGROUND

In the early stage of acute pancreatitis (AP), a large number of cytokines induced by local pancreatic inflammation seriously damage the intestinal barrier function, and intestinal bacteria and endotoxins enter the blood, causing inflammatory storm, resulting in multiple organ failure, infectious complications, and other disorders, eventually leading to death. Intestinal failure occurs early in the course of AP, accelerating its development. As an alternative method to detect small intestinal bacterial overgrowth, the hydrogen breath test is safe, noninvasive, and convenient, reflecting the number of intestinal bacteria in AP indirectly. This study aimed to investigate the changes in intestinal bacteria measured using the hydrogen breath test in the early stage of AP to clarify the relationship between intestinal bacteria and acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Early clinical intervention and maintenance of intestinal barrier function would be highly beneficial in controlling the development of severe acute pancreatitis (SAP).

AIM

To analyze the relationship between intestinal bacteria change and ALI/ARDS in the early stage of SAP.

METHODS

A total of 149 patients with AP admitted to the intensive care unit of the Digestive Department, Xuanwu Hospital, Capital Medical University from 2016 to 2019 were finally enrolled, following compliance with the inclusion and exclusion criteria. The results of the hydrogen breath test within 1 wk of admission were collected, and the hydrogen production rates at admission, 72 h, and 96 h were calculated. The higher the hydrogen production rates the more bacteria in the small intestine. First, according to the improved Marshall scoring system in the 2012 Atlanta Consensus on New Standards for Classification of Acute Pancreatitis, 66 patients with a PaO2/FiO2 score ≤ 1 were included in the mild AP (MAP) group, 18 patients with a PaO2/FiO2 score ≥ 2 and duration < 48 h were included in the moderately SAP (MSAP) group, and 65 patients with a PaO2/FiO2 score ≥ 2 and duration > 48 h were included in the SAP group, to analyze the correlation between intestinal bacterial overgrowth and organ failure in AP. Second, ALI (PaO2/FiO2 = 2) and ARDS (PaO2/FiO2 > 2) were defined according to the simplified diagnostic criteria proposed by the 1994 European Union Conference. The MSAP group was divided into two groups according to the PaO2/FiO2 score: 15 patients with PaO2/FiO2 score = 2 were included in group A, and three patients with score > 2 were included in group B. Similarly, the SAP group was divided into two groups: 28 patients with score = 2 were included in group C, and 37 patients with score > 2 were included in group D, to analyze the correlation between intestinal bacterial overgrowth and ALI/ARDS in AP.

RESULTS

A total of 149 patients were included: 66 patients in the MAP group, of whom 53 patients were male (80.3%) and 13 patients were female (19.7%); 18 patients in the MSAP group, of whom 13 patients were male (72.2%) and 5 patients were female (27.8%); 65 patients in the SAP group, of whom 48 patients were male (73.8%) and 17 patients were female (26.2%). There was no significant difference in interleukin-6 and procalcitonin among the MAP, MSAP, and SAP groups (P = 0.445 and P = 0.399, respectively). There was no significant difference in the growth of intestinal bacteria among the MAP, MSAP, and SAP groups (P = 0.649). There was no significant difference in the growth of small intestinal bacteria between group A and group B (P = 0.353). There was a significant difference in the growth of small intestinal bacteria between group C and group D (P = 0.038).

CONCLUSION

Intestinal bacterial overgrowth in the early stage of SAP is correlated with ARDS.

A narrative review of acute pancreatitis and its diagnosis, pathogenetic mechanism, and management

Acute pancreatitis (AP) is an inflammatory disease that can progress to severe acute pancreatitis (SAP), which increases the risk of death. AP is characterized by inappropriate activation of trypsinogen, infiltration of inflammatory cells, and destruction of secretory cells. Other contributing factors may include calcium (Ca²⁺) overload, mitochondrial dysfunction, impaired autophagy, and endoplasmic reticulum (ER) stress. In addition, exosomes are also associated with pathophysiological processes of many human diseases and may play a biological role in AP. However, the pathogenic mechanism has not been fully elucidated and needs to be further explored to inform treatment. Recently, the treatment guidelines have changed; minimally invasive therapy is advocated more as the core multidisciplinary participation and "step-up" approach. The surgical procedures have gradually changed from open surgery to minimally invasive surgery that primarily includes percutaneous catheter drainage (PCD), endoscopy, small incision surgery, and video-assisted surgery. The current guidelines for the management of AP have been updated and revised in many aspects. The type of fluid to be used, the timing, volume, and speed of administration for fluid resuscitation has been controversial. In addition, the timing and role of nutritional support and prophylactic antibiotic therapy, as well as the timing of the surgical or endoscopic intervention, and the management of complications still have many uncertainties that could negatively impact the prognosis and patients' quality of life. Consequently, to inform clinicians about optimal treatment, we aimed to review recent advances in the understanding of the pathogenesis of AP and its diagnosis and management.

Macrophages in the pancreas: Villains by circumstances, not necessarily by actions

Introduction

Mounting evidence suggest that macrophages play crucial roles in disease and tissue regeneration. However, despite much efforts during the past decade, our knowledge about the extent of macrophages' contribution to adult pancreatic regeneration after injury or during pancreatic disease progression is still limited. Nevertheless, it is generally accepted that some macrophage features that normally would contribute to healing and regeneration may be detrimental in pancreatic cancer. Altogether, the current literature contains conflicting reports on whether macrophages act as friends or foe in these conditions.

Methods and Results

In this review, we briefly review the origins of tissue resident and infiltrating macrophages and the importance of cellular crosstalking between macrophages and other resident cells in tissue regeneration. The primary objective of this review is to summarize our knowledge of the distinct roles of tissue resident and infiltrating macrophages, the impact of M1 and M2 macrophage phenotypes, and emerging evidence on macrophage crosstalking in pancreatic injury, regeneration, and disease.

Conclusion

Macrophages are involved with various stages of pancreatic cancer development, pancreatitis, and diabetes. Elucidating their role in these conditions will aid the development of targeted therapeutic treatments.

Macrophages in pancreatitis: Mechanisms and therapeutic potential

Macrophages play a crucial role in the pathogenesis of pancreatitis that is a common gastrointestinal disease. Particularly, macrophages differentiate into different phenotypes and exert diverse functions in acute pancreatitis (AP) and chronic pancreatitis (CP), respectively. In AP, macrophages in the pancreas and other related organs are mainly activated and differentiated into a pro-inflammatory M1 phenotype, and furthermore secrete inflammatory cytokines and mediators, causing local inflammation of the pancreas, and even intractable systemic inflammatory response or multiple organ failure. In CP, macrophages often exhibit a M2 polarisation and interact with pancreatic stellate cells (PSCs) in an autocrine and paracrine cytokine-dependent manner to promote the progression of pancreatic fibrosis. As the severity of pancreatic fibrosis aggravates, the proportion of M2/M1 macrophage cytokines in the pancreas increases. The discovery of macrophages in the pathogenesis of pancreatitis has promoted the research of targeted drugs, which provides great potential for the effective treatment of pancreatitis. This paper provides an overview of the roles of various macrophages in the pathogenesis of pancreatitis and the current research status of pancreatitis immunotherapy targeting macrophages. The findings addressed in this review are of considerable significance for understanding the pivotal role of macrophages in pancreatitis.

Macrophage phenotypic switch orchestrates the inflammation and repair/regeneration following acute pancreatitis injury

Background

Impaired or hyperactive pancreas regeneration after injury would cause exocrine insufficiency or recurrent / chronic pancreatitis and potentially carcinogenesis. Macrophages are the most abundant immune cells in the regenerative pancreas, however their phenotype and role remain poorly defined.

Method

Using caerulein-induced acute pancreatitis (AP) model, we examined the dynamic landscape of pancreatic macrophages throughout the acute inflammation to regeneration phases by flow cytometric and RNA-seq analyses. Liposome depletion of macrophages, Il4ra^−/− mice as well as inhibitors were used to elucidate the role and regulatory mechanism of macrophages during pancreatic regeneration.

Findings

We found that M1 macrophages dominated in the pro-inflammatory phase of AP, while M2-like macrophages dominated during pancreas repair/regeneration. Depletion of macrophages at early or late regenerative stage dramatically blocked the acinar-ductal metaplasia (ADM) or delayed inflammation resolution, respectively. Moreover, alternative activation of macrophages was partially dependent on IL-4RA signaling, and ECM/AKT activation in pancreatic macrophages facilitated inflammation resolution during tissue regeneration.

Interpretation

Our findings illustrate a dynamic phenotype and function of macrophages during AP repair/regeneration, helping us better understand the mechanism of pancreatic regeneration and providing clues for novel therapeutic strategy.

Current trends in pharmacological approaches for treatment and management of acute pancreatitis – a review

Objectives

Acute pancreatitis (AP) is an inimical disorder associated with overall mortality rates between 10-15%. It is a disorder of the exocrine pancreas which is characterized by local and systemic inflammatory responses primarily driven by oxidative stress and death of pancreatic acinar cells. The severity of AP ranges from mild pancreatic edema with complete recuperative possibilities to serious systemic inflammatory response resulting in peripancreatic/pancreatic necrosis, multiple organ failure, and death.

Key findings

We have retrieved the potential alternative approaches that are developed lately for efficacious treatment of AP from the currently available literature and recently reported experimental studies. This review summarizes the need for alternative approaches and combinatorial treatment strategies to deal with AP based on literature search using specific key words in PubMed and ScienceDirect databases.

Summary

Since AP results from perturbations of multiple signaling pathways, the so called “monotargeted smart drugs” of the past decade is highly unlikely to be effective. Also, the conventional treatment approaches were mainly involved in providing palliative care instead of curing the disease. Hence, many researchers are beginning to focus on developing alternate therapies to treat AP effectively. This review also summarizes the recent trends in the combinatorial approaches available for AP treatment.

Irreversible and sustained upregulation of endothelin axis during oncogene-associated pancreatic inflammation and cancer

Endothelin-1 (ET-1) and its two receptors, endothelin receptor A (ETAR) and endothelin receptor B (ETBR) exhibit deregulated overexprerssion in pancreatic ductal adenocarcinoma (PDAC) and pancreatitis. We examined the expression pattern of endothelin (ET) axis components in the murine models of chronic and acute inflammation in the presence or absence of oncogenic K-ras. While the expression of endothelin converting enzyme-1 (ECE-1), ET-1, ETAR and ETBR in the normal pancreas is restricted predominantly to the islet cells, progressive increase of ET receptors in ductal cells and stromal compartment is observed in the KC model (Pdx-1 Cre; K-rasG12D) of PDAC. In the murine pancreas harboring K-rasG12D mutation (KC mice), following acute inflammation induced by cerulein, increased ETAR and ETBR expression is observed in the amylase and CK19 double positive cells that represent cells undergoing pancreatic acinar to ductal metaplasia (ADM). As compared to the wild type (WT) mice, cerulein treatment in KC mice resulted in significantly higher levels of ECE-1, ET-1, ETAR and ETBR, transcripts in the pancreas. Similarly, in response to cigarette smoke-induced chronic inflammation, the expression of ET axis components is significantly upregulated in the pancreas of KC mice as compared to the WT mice. In addition to the expression in the precursor pancreatic intraepithelial neoplasm (PanIN lesions) in cigarette smoke-exposure model and metaplastic ducts in cerulein-treatment model, ETAR and ETBR expression is also observed in infiltrating F4/80 positive macrophages and α-SMA positive fibroblasts and high co-localization was seen in the presence of oncogenic K-ras. In conclusion, both chronic and acute pancreatic inflammation in the presence of oncogenic K-ras contribute to sustained upregulation of ET axis components in the ductal and stromal cells suggesting a potential role of ET axis in the initiation and progression of PDAC.

Protective effect of diallyl disulfide against cerulein-induced acute pancreatitis and associated lung injury in mice

Garlic (Allium sativum) - derived organosulfur compound diallyl disulfide (DADS) possesses antioxidant, anti-inflammatory and anti-cancer effects. This study was aimed to investigate the anti-inflammatory role and the underlying molecular mechanisms of DADS in cerulein-induced acute pancreatitis (AP) and associated lung injury. Administration of DADS significantly attenuated the severity of pancreatic and pulmonary inflammation by inhibiting cerulein induced serum amylase, myeloperoxidase activity (MPO) and histological changes in pancreas and lung. Furthermore, the anti-inflammatory effect of DADS was associated with the decrease in tumor necrosis factor (TNF)-α,cystathionine-γ-lyase (CSE), preprotachykinin A (PPTA), neurokinin-1-receptor (NK1R) expression and hydrogen sulfide (H₂S) production in both pancreas and lung. In addition, DADS reduced caerulein-induced I-κB degradation and subsequent translocation of NF-κB in the pancreas and lung. These results show for the first time that in AP, DADS exhibits an anti-inflammatory effect by inhibiting CSE/H₂S and SP/NK1R signaling and NF-кB pathway.

MicroRNAs in acute pancreatitis: From pathogenesis to novel diagnosis and therapy

Acute pancreatitis (AP) is an inflammatory disorder initiated by activation of pancreatic zymogens, leading to pancreatic injury and systemic inflammatory response. MicroRNAs (miRNAs) have emerged as important regulators of gene expression and key players in human physiological and pathological processes. Discoveries over the past decade have confirmed that altered expression of miRNAs is implicated in the pathogenesis of AP. Indeed, a number of miRNAs have been found to be dysregulated in various cell types involved in AP such as acinar cells, macrophages, and lymphocytes. These aberrant miRNAs can regulate acinar cell necrosis and apoptosis, local and systemic inflammatory response, thereby contributing to the initiation and progression of AP. Moreover, patients with AP possess unique miRNA signatures when compared with healthy individuals or those with other diseases. In view of their stability and easy detection, therefore, miRNAs have the potential to act as biomarkers for the diagnosis and assessment of patients with AP. In this review, we provide an overview of the novel cellular and molecular mechanisms underlying the roles of miRNAs during the disease processes of AP, as well as the potential diagnosis and therapeutic biomarkers of miRNAs in patients with AP.

Induction of Macrophage M2b/c Polarization by Adipose Tissue-Derived Mesenchymal Stem Cells

Background

Adipose-derived mesenchymal stem cells (ADMSCs) can promote healing and inhibit inflammation/immune response in local tissues, while the detailed mechanism remains unknown.

Results

ADMSCs and peritoneal macrophages were collected from C57BL/6 mice. The culture medium (CM) from ADMSCs (24 hours cultured) was collected. The CM was added to the Mφ culture system with lipopolysaccharide (LPS) or IL-4/IL-13 or blank. And those Mφ cultures without adding CM were used as controls. A series of classification markers and signaling pathways for Mφ polarization were detected by using flow cytometry, RT-PCR, and western blotting. Furthermore, the cell viability of all the groups was detected by CCK8 assay. After CM induction in different groups, M1-Mφ markers and M2a-Mφ were decreased; however, M2b/c-Mφ markers increased. STAT3/SOCS3 and STAT6/IRF4 were suppressed in all 3 CM-treated groups. Moreover, the cell viability of all 3 groups which were induced by CM significantly increased as compared to that of the control groups without adding CM.

Conclusion

ADMSCs can induce nonactivated macrophage and M1-Mφ into M2b/c-Mφ. Downregulation of the STAT3 and STAT6 pathway may involve in this process. This data shows that the anti-inflammatory role of ADMSC in local tissues may be partly due to their effect on Mφ to M2b/c-Mφ.

Dynamic Detection of Monocyte Subsets in Peripheral Blood of Patients with Acute Hypertriglyceridemic Pancreatitis

Aim

Monocytes play an important role in acute pancreatitis (AP). Hypertriglyceridemic pancreatitis (HTGP) is always more severe than normal lipid-AP, whether the mechanism of aggravation involves monocyte subsets remains unknown though. The present study was aimed to analyze changes of peripheral blood M1 and M2 monocytes in HTGP patients.

Methods

A total of 90 subjects were enrolled, among which 16 diagnosed with HTGP, 34 with acute biliary pancreatitis (ABP), 20 with hypertriglyceridemia (HTG), and 20 healthy controls (HC). Peripheral blood CD14+CD86+ M1 and CD14+CD206+ M2 monocytes were examined by flow cytometry on days 1, 3, and 7 after admission.

Results

We found a marked increase in total and M1 monocyte count in AP patients (P < 0.05). In HTGP, the percentage of M1 monocytes in white blood cells was significantly higher on days 1, 3, and 7, while M2 monocyte percentage was decreased on day 3, compared with ABP (P < 0.05). In mild HTGP, M1 monocyte count and percentage gradually decreased, while M2 monocyte percentage gradually increased from day 1 to 7. In severe HTGP, M1 monocyte count and percentage rose to the highest point while M2 were the lowest on day 3. Additionally, the level of M1 monocytes showed a positive correlation with plasma triglyceride and Ranson score of HTGP patients.

Conclusions

Peripheral blood M1 and M2 monocytes showed different dynamic changes in mild and severe HTGP. A more dominant role of CD14+CD86+ M1 monocytes may be involved in the pathogenesis of HTGP.

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.

The Dual Role of HMGB1 in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of exocrine pancreatic cancer with a 9% five-year survival rate. High mobility group box 1 (HMGB1) is a nuclear protein that can act as a DNA chaperone in the sustainment of chromosome structure and function. When released into the extracellular space, HMGB1 becomes the most well-characterized damage-associated molecular pattern (DAMP) to trigger immune responses. Recent evidence indicates that intracellular HMGB1 is a novel tumor suppressor in PDAC, which is connected to its role in the prevention of oxidative stress, genomic instability, and histone release. However, since extracellular HMGB1 is a DAMP and pro-inflammatory cytokine, cancer cells can also exploit it to survive through the receptor for advanced glycation endproducts (RAGE) in the pancreatic tumor microenvironment. Interestingly, targeting the HMGB1-RAGE pathway has become a new anticancer therapy strategy for PDAC.

Enhanced proliferation of pancreatic acinar cells in MRL/MpJ mice is driven by severe acinar injury but independent of inflammation

Adult pancreatic acinar cells have the ability to re-enter the cell cycle and proliferate upon injury or tissue loss. Despite this mitotic ability, the extent of acinar proliferation is often limited and unable to completely regenerate the injured tissue or restore the initial volume of the organ, thus leading to pancreatic dysfunction. Identifying molecular determinants of enhanced proliferation is critical to overcome this issue. In this study, we discovered that Murphy Roths Large (MRL/MpJ) mice can be exploited to identify molecular effectors promoting acinar proliferation upon injury, with the ultimate goal to develop therapeutic regimens to boost pancreatic regeneration. Our results show that, upon cerulein-induced acinar injury, cell proliferation was enhanced and cell cycle components up-regulated in the pancreas of MRL/MpJ mice compared to the control strain C57BL/6. Initial damage of acinar cells was exacerbated in these mice, manifested by increased serum levels of pancreatic enzymes, intra-pancreatic trypsinogen activation and acinar cell apoptosis. In addition, MRL/MpJ pancreata presented enhanced inflammation, de-differentiation of acinar cells and acinar-to-ductal metaplasia. Manipulation of inflammatory levels and mitogenic stimulation with the thyroid hormone 5,3-L-tri-iodothyronine revealed that factors derived from initial acinar injury rather than inflammatory injury promote the replicative advantage in MRL/MpJ mice.

Brain Natriuretic Peptide-Regulated Expression of Inflammatory Cytokines in Lipopolysaccharide (LPS)-Activated Macrophages via NF-κB and Mitogen Activated Protein Kinase (MAPK) Pathways

Background

This study aimed to investigate the effects of recombinant human brain natriuretic peptide (rhBNP) on IL-6, TNF-α, and IL-10 secretion in LPS-activated RAW 264.7 cells and human peripheral blood mononuclear cells (PBMCs) in vitro and to explore the related signaling pathways of the regulation mechanisms of BNP in systemic inflammatory response syndrome (SIRS).

Material/Methods

MTT assay was used to evaluate the effects of rhBNP on cell viabilities. Lipopolysaccharide (LPS) was used to induce inflammation response. The whole study was divided into 8 groups: Control, low, middle, and high concentrations of rhBNP, LPS, LPS with low, middle, and high concentrations of rhBNP. Levels of IL-6, TNF-α, and IL-10 were evaluated using the Cytometric Bead Array Kit and RT-PCR assay. Western blotting was used to test the effects of rhBNP on inflammation-related NF-κB and MAPK pathways.

Results

Except for the concentrations ≥1.6 ng/mL, all concentrations of rhBNP showed little effect on cell viabilities of RAW264.7 cells and PBMCs after 24 h and 48 h, suggesting a weak cytotoxicity to cells. Expression of IL-6 and TNF-α significantly increased and expression of IL-10 significantly decreased at protein and mRNA levels after LPS treatment, and these effects were strongly inhibited in a dose-dependent manner by pretreatment of rhBNP. Similarly, the LPS-induced increase of NF-κB and MAPK pathway phosphorylation levels were also significantly inhibited by rhBNP.

Conclusions

rhBNP can regulate expression of IL-6, TNF-α, and IL-10 in LPS-activated RAW 264.7 cells and PBMCs through inhibiting NF-κB and MAPK pathways. These results may reveal potential causes of the increase of BNP in SIRS and may provide an experimental basis for treatment of SIRS.

Morphine worsens the severity and prevents pancreatic regeneration in mouse models of acute pancreatitis

BACKGROUND

Opioids such as morphine are widely used for the management of pain associated with acute pancreatitis. Interestingly, opioids are also known to affect the immune system and modulate inflammatory pathways in non-pancreatic diseases. However, the impact of morphine on the progression of acute pancreatitis has never been evaluated. In the current study, we evaluated the impact of morphine on the progression and severity of acute pancreatitis.

METHODS

Effect of morphine treatment on acute pancreatitis in caerulein, L-arginine and ethanol-palmitoleic acid models was evaluated after induction of the disease. Inflammatory response, gut permeability and bacterial translocation were compared. Experiments were repeated in mu (µ) opioid receptor knockout mice (MORKO) and in wild-type mice in the presence of opioid receptor antagonist naltrexone to evaluate the role of µ-opioid receptors in morphine's effect on acute pancreatitis. Effect of morphine treatment on pathways activated during pancreatic regeneration like sonic Hedgehog and activation of embryonic transcription factors like pdx-1 and ptf-1 were measured by immunofluorescence and quantitative PCR.

RESULTS

Histological data show that treatment with morphine after induction of acute pancreatitis exacerbates the disease with increased pancreatic neutrophilic infiltration and necrosis in all three models of acute pancreatitis. Morphine also exacerbated acute pancreatitis-induced gut permeabilisation and bacteraemia. These effects were antagonised in the MORKO mice or in the presence of naltrexone suggesting that morphine's effect on severity of acute pancreatitis are mediated through the µ-opioid receptors. Morphine treatment delayed macrophage infiltration, sonic Hedgehog pathway activation and expression of pdx-1 and ptf-1.

CONCLUSION

Morphine treatment worsens the severity of acute pancreatitis and delays resolution and regeneration. Considering our results, the safety of morphine for analgesia during acute pancreatitis should be re-evaluated in future human studies.

Cathepsin B-Mediated Activation of Trypsinogen in Endocytosing Macrophages Increases Severity of Pancreatitis in Mice

BACKGROUND & AIMS

Acute pancreatitis is characterized by premature intracellular activation of digestive proteases within pancreatic acini and a consecutive systemic inflammatory response. We investigated how these processes interact during severe pancreatitis in mice.

METHODS

Pancreatitis was induced in C57Bl/6 wild-type (control), cathepsin B (CTSB)-knockout, and cathepsin L-knockout mice by partial pancreatic duct ligation with supramaximal caerulein injection, or by repetitive supramaximal caerulein injections alone. Immune cells that infiltrated the pancreas were characterized by immunofluorescence detection of Ly6g, CD206, and CD68. Macrophages were isolated from bone marrow and incubated with bovine trypsinogen or isolated acinar cells; the macrophages were then transferred into pancreatitis control or cathepsin-knockout mice. Activities of proteases and nuclear factor (NF)-κB were determined using fluorogenic substrates and trypsin activity was blocked by nafamostat. Cytokine levels were measured using a cytometric bead array. We performed immunohistochemical analyses to detect trypsinogen, CD206, and CD68 in human chronic pancreatitis (n = 13) and acute necrotizing pancreatitis (n = 15) specimens.

RESULTS

Macrophages were the predominant immune cell population that migrated into the pancreas during induction of pancreatitis in control mice. CD68-positive macrophages were found to phagocytose acinar cell components, including zymogen-containing vesicles, in pancreata from mice with pancreatitis, as well as human necrotic pancreatic tissues. Trypsinogen became activated in macrophages cultured with purified trypsinogen or co-cultured with pancreatic acini and in pancreata of mice with pancreatitis; trypsinogen activation required macrophage endocytosis and expression and activity of CTSB, and was sensitive to pH. Activation of trypsinogen in macrophages resulted in translocation of NF-kB and production of inflammatory cytokines; mice without trypsinogen activation (CTSB-knockout mice) in macrophages developed less severe pancreatitis compared with control mice. Transfer of macrophage from control mice to CTSB-knockout mice increased the severity of pancreatitis. Inhibition of trypsin activity in macrophages prevented translocation of NF-κB and production of inflammatory cytokines.

CONCLUSIONS

Studying pancreatitis in mice, we found activation of digestive proteases to occur not only in acinar cells but also in macrophages that infiltrate pancreatic tissue. Activation of the proteases in macrophage occurs during endocytosis of zymogen-containing vesicles, and depends on pH and CTSB. This process involves macrophage activation via NF-κB-translocation, and contributes to systemic inflammation and severity of pancreatitis.

Imaging Macrophage Accumulation in a Murine Model of Chronic Pancreatitis with 125I-Iodo-DPA-713 SPECT/CT

Pancreatitis remains a diagnostic challenge in patients with mild to moderate disease, with current imaging modalities being inadequate. Given the prominent macrophage infiltration in chronic pancreatitis, we hypothesized that ¹²⁵I-iodo-DPA-713, a small-molecule radiotracer that specifically targets macrophages, could be used with SPECT/CT to image pancreatic inflammation in a relevant experimental model. Methods: Chronic pancreatitis was induced with cerulein in C57BL/6 mice, which were contrasted with saline-injected control mice. The animals were imaged at 7 wk after induction using N,N-diethyl-2-(2-(3-¹²⁵I-iodo-4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide (¹²⁵I-iodo-DPA-713) SPECT/CT or ¹⁸F-FDG PET/CT. The biodistribution of ¹²⁵I-iodo-DPA-713 was determined under the same conditions, and a pair of mice was imaged using a fluorescent analog of ¹²⁵I-iodo-DPA-713, DPA-713-IRDye800CW, for correlative histology. Results: Pancreatic ¹²⁵I-iodo-DPA-713 uptake was significantly higher in treated mice than control mice (5.17% ± 1.18% vs. 2.41% ± 0.34% injected dose/g, P = 0.02), as corroborated by imaging. Mice imaged with ¹⁸F-FDG PET/CT showed cerulein-enhanced pancreatic uptake in addition to a moderate signal from healthy pancreas. Near-infrared fluorescence imaging with DPA-713-IRDye800CW showed strong pancreatic uptake, focal liver uptake, and gastrointestinal uptake in the treated mice, whereas the control mice showed only urinary excretion. Ex vivo fluorescence microscopy revealed a large influx of macrophages in the pancreas colocalizing with the retained fluorescent probe in the treated but not the control mice. Conclusion: These data support the application of both ¹²⁵I-iodo-DPA-713 SPECT/CT and DPA-713-IRDye800CW near-infrared fluorescence to delineate pancreatic, liver, or intestinal inflammation in living mice.

Involvement of exosomes in lung inflammation associated with experimental acute pancreatitis

A frequent complication of acute pancreatitis is the lung damage associated with the systemic inflammatory response. Although various pro-inflammatory mediators generated at both local and systemic levels have been identified, the pathogenic mechanisms of the disease are still poorly understood. In recent years, exosomes have emerged as a new intercellular communication system able to transfer encapsulated proteins and small RNAs and protect them from degradation. Using an experimental model of taurocholate-induced acute pancreatitis in rats, we aimed to evaluate the role of exosomes in the extent of the systemic inflammatory response. Induction of pancreatitis increased the concentration of circulating exosomes, which showed a different proteomic profile to those obtained from control animals. A series of tracking experiments using PKH26-stained exosomes revealed that circulating exosomes effectively reached the alveolar compartment and were internalized by macrophages. In vitro experiments revealed that exosomes obtained under inflammatory conditions activate and polarize these alveolar macrophages towards a pro-inflammatory phenotype. Interestingly, the proteomic analysis of circulating exosomes during acute pancreatitis suggested a multi-organ origin with a relevant role for the liver as a source of these vesicles. Tracking experiments also revealed that the liver retains the majority of exosomes from the peritoneal cavity. We conclude that exosomes are involved in the lung damage associated with experimental acute pancreatitis and could be relevant mediators in the systemic effects of pancreatitis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Mannose-coated gadolinium liposomes for improved magnetic resonance imaging in acute pancreatitis

Background

Acute pancreatitis (AP) is an acute inflammatory condition of the pancreas. The symptoms, treatment, and prognosis of mild and severe AP are different, and severe AP is a potentially life-threatening disease with a high incidence of complications and high mortality rate. Thus, it is urgent to develop an effective approach to reliably discriminate between mild and severe AP.

Methods

We have developed novel gadolinium-diethylenetriaminepentaacetic (Gd-DTPA)-loaded mannosylated liposomes (named thereafter M-Gd-NL) that preferably target macrophages in AP. The targeting ability of M-Gd-NL toward macrophages in AP and its ability to discriminate between mild and severe AP were evaluated.

Results

The liposomes were of desired particle size (~100 nm), Gd-DTPA encapsulation efficiency (~85%), and stability. M-Gd-NL and non-targeted Gd-DTPA-loaded liposomes (Gd-NL) exhibited increased relaxivity compared with Gd-DTPA. Compared with Gd-NL and Gd-DTPA, M-Gd-NL showed increased uptake in macrophages, resulting in increased T₁ imaging ability both in vitro (macrophage cell line) and in vivo (severe AP model). Importantly, M-Gd-NL had the ability to discriminate between mild and severe AP, as reflected by a significantly higher T₁ magnetic resonance imaging signal in severe AP than in mild AP. M-Gd-NL did not show severe organ toxicity in rats.

Conclusion

Our data suggest that M-Gd-NL had enhanced magnetic resonance imaging ability by targeting macrophages in AP and good ability to discriminate between mild and severe AP. We believe that M-Gd-NL could shed new light on the diagnosis of AP in the near future.

Legumain is activated in macrophages during pancreatitis

Pancreatitis is an inflammatory disease of the pancreas characterized by dysregulated activity of digestive enzymes, necrosis, immune infiltration, and pain. Repeated incidence of pancreatitis is an important risk factor for pancreatic cancer. Legumain, a lysosomal cysteine protease, has been linked to inflammatory diseases such as atherosclerosis, stroke, and cancer. Until now, legumain activation has not been studied during pancreatitis. We used a fluorescently quenched activity-based probe to assess legumain activation during caerulein-induced pancreatitis in mice. We detected activated legumain by ex vivo imaging, confocal microscopy, and gel electrophoresis. Compared with healthy controls, legumain activity in the pancreas of caerulein-treated mice was increased in a time-dependent manner. Legumain was localized to CD68(+) macrophages and was not active in pancreatic acinar cells. Using a small-molecule inhibitor of legumain, we found that this protease is not essential for the initiation of pancreatitis. However, it may serve as a biomarker of disease, since patients with chronic pancreatitis show strongly increased legumain expression in macrophages. Moreover, the occurrence of legumain-expressing macrophages in regions of acinar-to-ductal metaplasia suggests that this protease may influence reprogramming events that lead to inflammation-induced pancreatic cancer.

The Receptor for Advanced Glycation End Products Activates the AIM2 Inflammasome in Acute Pancreatitis

Severe acute pancreatitis (AP) is responsible for significant human morbidity and mortality worldwide. Currently, no specific treatments for AP exist, primarily due to the lack of a mechanistic understanding of sterile inflammation and the resultant multisystem organ dysfunction, the pathologic response of AP linked to early death. In this study, we demonstrate that the class III major histocompatibility region III receptor for advanced glycation end products (RAGE) contributes to AP by modulating inflammasome activation in macrophages. RAGE mediated nucleosome-induced absent in melanoma 2 (but not NLRP3) inflammasome activation by modulating dsRNA-dependent protein kinase phosphorylation in macrophages. Pharmacological and genetic inhibition of the RAGE-dsRNA-dependent protein kinase pathway attenuated the release of inflammasome-dependent exosomal leaderless cytokines (e.g., IL-1β and high-mobility group box 1) in vitro. RAGE or absent in melanoma 2 depletion in mice limited tissue injury, reduced systemic inflammation, and protected against AP induced by l-arginine or cerulein in experimental animal models. These findings define a novel role for RAGE in the propagation of the innate immune response with activation of the nucleosome-mediated inflammasome and will help guide future development of therapeutic strategies to treat AP.

Intra-abdominal pressure: Time ripe to revise management guidelines of acute pancreatitis?

AIM

To systematically review evidence on pathophysiology of intra-abdominal pressure (IAP) in acute pancreatitis (AP) with its clinical correlates.

METHODS

Systematic review of available evidence in English literature with relevant medical subject heading terms on PubMed, Medline and Scopus with further search from open access sources on internet as suggested by articles retrieved.

RESULTS

Intra-abdominal hypertension (IAH) is increasingly gaining recognition as a point of specific intervention with potential to alter disease outcome and improve mortality in AP. IAH can be expected in at least 17% of patients presenting with diagnosis of AP to a typical tertiary care hospital (prevalence increasing to 50% in those with severe disease). Abdominal compartment syndrome can be expected in at least 15% patients with severe disease. Recent guidelines on management of AP do not acknowledge utility of surveillance for IAP other than those by Japanese Society of Hepato-Biliary-Pancreatic Surgery. We further outline pathophysiologic mechanisms of IAH; understanding of which advances our knowledge and helps to coherently align common observed variations in management related conundrums (such as fluid therapy, nutrition and antibiotic prophylaxis) with potential to further individualize treatment in AP.

CONCLUSION

We suggest that IAP be given its due place in future practice guidelines and that recommendations be formed with help of a broader panel with inclusion of clinicians experienced in management of IAH.

Reverse-migrated neutrophils regulated by JAM-C are involved in acute pancreatitis-associated lung injury

Junctional adhesion molecule-C (JAM-C) plays a key role in the promotion of the reverse transendothelial migration (rTEM) of neutrophils, which contributes to the dissemination of systemic inflammation and to secondary organ damage. During acute pancreatitis (AP), systemic inflammatory responses lead to distant organ damage and typically result in acute lung injury (ALI). Here, we investigated the role of rTEM neutrophils in AP-associated ALI and the molecular mechanisms by which JAM-C regulates neutrophil rTEM in this disorder. In this study, rTEM neutrophils were identified in the peripheral blood both in murine model of AP and human patients with AP, which elevated with increased severity of lung injury. Pancreatic JAM-C was downregulated during murine experimental pancreatitis, whose expression levels were inversely correlated with both increased neutrophil rTEM and severity of lung injury. Knockout of JAM-C resulted in more severe lung injury and systemic inflammation. Significantly greater numbers of rTEM neutrophils were present both in the circulation and pulmonary vascular washout in JAM-C knockout mice with AP. This study demonstrates that during AP, neutrophils that are recruited to the pancreas may migrate back into the circulation and then contribute to ALI. JAM-C downregulation may contribute to AP-associated ALI via promoting neutrophil rTEM.

Macrophage activation syndrome: A severe and frequent manifestation of acute pancreatitis in 362 childhood-onset compared to 1830 adult-onset systemic lupus erythematosus patients

OBJECTIVE

We previously reported a case series of acute pancreatitis (AP) and macrophage activation syndrome (MAS) in childhood (cSLE) patients; however, there are no data regarding the comparison of AP and MAS in large populations of cSLE and adult SLE (aSLE).

METHODS

A study included 362 cSLE and 1830 aSLE patients. MAS was diagnosed according to preliminary diagnostic guidelines and AP according to the presence of abdominal pain or vomiting associated to an increase of pancreatic enzymes and/or pancreatic radiological abnormalities. Demographic data, clinical features, SLEDAI-2K, SLICC/ACR-DI, and treatment were assessed.

RESULTS

Age in MAS patients was significantly lower compared with those without this complication [15 (8.8-55) vs. 33.5 (10.2-45.7) years, p = 0.007]. The frequencies of fever (94% vs. 37%, p = 0.001), leucopenia (82% vs. 19%, p = 0.0001), thrombocytopenia (65% vs. 19%, p = 0.013), hypertriglyceridemia (87% vs. 42%, p = 0.037), and hyperferritinemia (93% vs. 37%, p = 0.011) were also more frequently observed in AP patients with MAS compared in AP patients without MAS. Fever and hyperferritinemia concomitantly were more frequent in the former group (86% vs. 12%, p = 0.0015). Higher and significant frequency of AP in cSLE compared to aSLE patients [12/362 (3.3%) vs. 20/1830 (1.1%), p = 0.003], with similar AP duration [22 (6-60) vs. 15 (4-90) days, p = 0.534]. MAS (85% vs. 30%, p = 0.003) and death by MAS complication (31% vs. 0%, p = 0.017) were significantly higher in children compared with aSLE.

CONCLUSIONS

This study provides novel data demonstrating that MAS occur in the majority of cSLE with AP with a higher mortality compared to aSLE. In addition, we identified in AP patients, a cluster of MAS clinical and laboratorial parameters more associated with this complication.

Ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis-associated acute lung injury

This study examined the ultrastructural changes in the pulmonary mechanical barriers in a rat model of severe acute pancreatitis (SAP)-associated acute lung injury (ALI). Animals were randomized into the SAP group (n = 60) and the control group (n = 60). SAP was induced by retrograde injection of 5% taurocholic acid into the biliopancreatic duct. The morphological abnormalities assessed by histology and the lung wet/dry weight ratio and the ultrastructural abnormalities assessed by transmission electron microscope and scanning electron microscope examinations plus lanthanum nitrate tracing were compared between the two groups at 6, 12, and 24 h post-SAP induction (n = 10/group/time point). The SAP group had significantly greater extravascular effusion than the control group at each time point as assessed by the lung wet/dry weight ratio (p < .001). The severity of the tissue damage increased in the lung and pancreas over time in the SAP group (all p < .001). In the SAP group, ultrastructural damages to the endothelial, epithelial, and pleural barriers were apparent and the damages to the endothelial barrier were detected earlier than the other two barriers, suggesting its fundamental role in preventing the further development of SAP-associated ALI. Moreover, the ultrastructural abnormalities were detected earlier than symptoms and morphological changes. The ultrastructural damages in the endothelial, epithelial, and pleural barriers occurred in the early stage of SAP. The endothelial barrier is likely to be the first line to prevent the further development in this rat model of SAP-associated ALI.

Soluble CD163 is increased in patients with acute pancreatitis independent of disease severity

Macrophages are crucially involved in the pathophysiology of acute pancreatitis. Soluble CD163 (sCD163) is specifically released from macrophages and systemic levels are increased in inflammatory diseases. Here, sCD163 was measured in serum of 50 patients with acute pancreatitis to find out possible associations with disease activity. Admission levels of systemic sCD163 were nearly three-fold higher in patients with acute pancreatitis compared to controls. In patients sCD163 did not correlate with C-reactive protein and leukocyte count as established markers of inflammation. Levels were not associated with disease severity assessed by the Schroeder score, Balthazar score, Acute Physiology, Age, and Chronic Health Evaluation (Apache) II score and peripancreatic necrosis score. Soluble CD163 was not related to complications of acute pancreatitis. These data show that serum sCD163 is increased in acute pancreatitis indicating activation of macrophages but is not associated with disease severity and outcome.

Expression of serum sCD163 in patients with liver diseases and inflammatory disorders

OBJECTIVE

To investigate the diagnostic values of soluble cluster of differentiation 163 (sCD163) in patients with liver failure or various inflammations.

METHODS

Serum samples were collected from patients admitted to the First Affiliated Hospital, Zhejiang University from October 2013 to January 2015 for treatment of with liver diseases, including liver failure (n=38), hepatitis B virus (HBV)-induced liver cancer (HBsAg positive) (n=40), HBV-induced hepatic cirrhosis (HBsAg positive) (n=40), chronic hepatitis B (n=38), HBV carrier (n=40), fatty liver patients without HBV infection (n=40), chronic glomerulonephritis (n=38), community acquired pneumonia (n=38) and acute pancreatitis (n=38). The CD163/sCD163 was determined using commercial ELISA kits according to the manufacturer's instructions.

RESULTS

Significant decrease was noticed in the sCD163 in patients with fatty liver and HBV carrier compared with that of patients with chronic hepatitis B (P < 0.05). Compared with the healthy controls, the level of sCD163 was remarkably increased in the other groups (P < 0.05). The serum sCD163 in patients with HBV-induced liver cancer showed statistical difference compared with those of the patients with fatty liver, HBV carrier, as well as those with liver failure (P < 0.05). The expression of sCD163 was remarkably elevated in patients with liver failure compared with the patients with liver cancer, HBV-induced hepatic cirrhosis, chronic hepatitis B, fatty liver, or HBV carrier (P < 0.05). No significant difference was noticed in the sCD163 in patients with chronic hepatitis B, community acquired pneumonia, chronic glomerulonephritis, and acute pancreatitis (P > 0.05).

CONCLUSIONS

sCD163 is a sensitive marker protein for liver failure. The elevation of sCD163 was closely related to the progression of the liver failure. No statistical difference was noticed in the sCD163 in patients with inflammatory disorders, indicating sCD163 showed no organ specificity.

The oncogenic microRNA miR-21 promotes regulated necrosis in mice

MicroRNAs (miRNAs) regulate apoptosis, yet their role in regulated necrosis remains unknown. miR-21 is overexpressed in nearly all human cancer types and its role as an oncogene is suggested to largely depend on its anti-apoptotic action. Here we show that miR-21 is overexpressed in a murine model of acute pancreatitis, a pathologic condition involving RIP3-dependent regulated necrosis (necroptosis). Therefore, we investigate the role of miR-21 in acute pancreatitis injury and necroptosis. miR-21 deficiency protects against caerulein- or L-arginine-induced acute pancreatitis in mice. miR-21 inhibition using locked-nucleic-acid-modified oligonucleotide effectively reduces pancreatitis severity. miR-21 deletion is also protective in tumour necrosis factor-induced systemic inflammatory response syndrome. These data suggest that miRNAs are critical participants in necroptosis and miR-21 enhances cellular necrosis by negatively regulating tumour suppressor genes associated with the death-receptor-mediated intrinsic apoptosis pathway, and could be a therapeutic target for preventing pathologic necrosis.

Lipids generated during acute pancreatitis increase inflammatory status of macrophages by interfering with their M2 polarization

BACKGROUND

Necrosis of adipose tissue is a common complication of acute pancreatitis. The areas of steatonecrosis become a source of inflammatory mediators, including chemically modified fatty acids which could influence the progression of the systemic inflammation. In an experimental model of acute pancreatitis we analyzed the effects of lipids generated by two representative areas of adipose tissue on the switch to the M1 phenotype in macrophages.

METHODS

Pancreatitis was induced in rats by intraductal administration of 5% taurocholate and after 6 h, lipids from retroperitoneal, mesenteric or epididymal adipose tissues were collected. Lipid uptake, phenotype polarization and the activation of PPARγ and NFκB were evaluated in macrophages treated with these lipids.

RESULTS

After induction of pancreatitis, lipids from visceral adipose tissue promote the switch to an increased pro-inflammatory phenotype in macrophages. This effect is not related with a higher activation of NFκB but with an interfering effect on the activation of M2 phenotype.

CONCLUSIONS

During acute pancreatitis, lipids generated by some areas of adipose tissue interfere on the M2 polarization of macrophages, thus resulting in a more intense pro-inflammatory M1 response.

Inflammatory macrophages in pancreatic acinar cell metaplasia and initiation of pancreatic cancer

The roles of inflammatory macrophages in pancreatic tissue and the development of pancreatic cancer have not been well characterized. Recently it was shown that inflammatory macrophages, besides their function in clearing dead cells, also initiate pancreatic acinar cell metaplasia to duct-like progenitor cells. While in pancreatitis this is a reversible process, in context of an oncogenic stimulus this process is irreversible and can lead to the formation of precancerous lesions. Recent work now indicates that acquisition of an activating Kras mutation in acinar cells initiates signaling that leads to chemoattraction of M1-poliarized macrophages. This oncogene-caused chronic microinflammation can accelerate the pathogenesis of pancreatic cancers.

Immunomodulatory therapies for acute pancreatitis

It is currently difficult for conventional treatments of acute pancreatitis (AP), which primarily consist of anti-inflammatory therapies, to prevent the progression of AP or to improve its outcome. This may be because the occurrence and progression of AP, which involves various inflammatory cells and cytokines, includes a series of complex immune events. Considering the complex immune system alterations during the course of AP, it is necessary to monitor the indicators related to immune cells and inflammatory mediators and to develop more individualized interventions for AP patients using immunomodulatory therapy. This review discusses the recent advances in immunomodulatory therapies. It has been suggested that overactive inflammatory responses should be inhibited and excessive immunosuppression should be avoided in the early stages of AP. The optimal duration of anti-inflammatory therapy may be shorter than previously expected (< 24 h), and appropriate immunostimulatory therapies should be administered during the period from the 3^rd d to the 14^th d in the course of AP. A combination therapy of anti-inflammatory and immune-stimulating drugs would hopefully constitute an alternative to anti-inflammatory drug monotherapy. Additionally, the detection of the genotypes of critical inflammatory mediators may be useful for screening populations of AP patients at high risk of severe infections to enable the administration of early interventions to improve their prognosis.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.