Development of a novel model of hypertriglyceridemic acute pancreatitis in mice

Association of admission serum triglyceride levels with intensive care unit hospitalization rates in acute pancreatitis patients: A retrospective study

Acute pancreatitis (AP) is a complex and unpredictable condition, of which hypertriglyceridemia (HTG) is the third most prevalent cause. This study aimed to conduct a retrospective analysis of clinical data from hospitalized AP patients to uncover a potential correlation between triglyceride (TG) levels and the necessity for intensive care unit (ICU) admission. This retrospective cohort study utilized the Medical Information Mart for Intensive Care IV 2.2 (MIMIC-IV) critical care dataset, incorporating data from 698 patients with hypertriglyceridemic acute pancreatitis (HTG-AP). The analysis employed the RCS model along with univariate and multivariate logistic regression methods to affirm the association between triglyceride levels and ICU admission. Subgroup analysis was performed to investigate specific populations. The study included 698 patients with AP, 42.41% of whom experienced HTG during hospitalization. RCS analysis revealed a linear association between TG levels and risk of ICU admission (p for nonlinear = .219, p for overall = .009). Multivariate logistic regression analysis indicated an increased risk of ICU admission in the TG range of 1.7-5.65 mmol/L (aOR = 1.83, 95% CI 1.12-2.99, P = .015) and TG >11.3 mmol/L (aOR = 5.69, 95% CI 2.36-13.74, P < .001) compared to the normal group. Similar results were observed across the various subgroups. As triglyceride levels increased, there was a corresponding increase in ICU admissions. Patients within the 1.7 to 5.65 mmol/L and > 11.3 mmol/L triglyceride groups exhibited higher rates of ICU admissions. Moreover, we observed a higher risk of ICU hospitalization even with mild TG elevation.

Apolipoprotein C-III itself stimulates the Syk/cPLA2-induced inflammasome activation of macrophage to boost anti-tumor activity of CD8+ T cell

Increased prevalence of cancer in obese individuals is involved with dyslipidemia- induced chronic inflammation and immune suppression. Although apolipoprotein C-III (ApoC3)-transgenic mice (ApoC3TG mice) or poloxamer 407 (P407)-treated mice had hyperlipidemia, CD8+ T cells with upregulated antitumor activities were observed in ApoC3TG mice, and decreased CD8+ T cell activities were observed in P407-treated mice. Increased ApoC3 expression in hepatocellular carcinoma was associated with increased infiltration of CD8+ T cells and predicted survival. Recombinant ApoC3 had no direct effects on CD8+ T cells. The upregulation of CD8+ T cells in ApoC3TG mice was due to cross-talk with context cells, as indicated by metabolic changes and RNA sequencing results. In contrast to dendritic cells, the macrophages of ApoC3TG mice (macrophagesTG) displayed an activated phenotype and increased IL-1β, TNF-α, and IL-6 production. Coculture with macrophagesTG increased CD8+ T cell function, and the adoptive transfer of macrophagesTG suppressed tumor progression in vivo. Furthermore, spleen tyrosine kinase (Syk) activation induced by TLR2/TLR4 cross-linking after ApoC3 ligation promoted cellular phospholipase A2 (cPLA2) activation, which in turn activated NADPH oxidase 2 (NOX2) to promote an alternative mode of inflammasome activation. Meanwhile, mitochondrial ROS produced by increased oxidative phosphorylation of free fatty acids facilitated the classical inflammasome activation, which exerted an auxiliary effect on inflammasome activation of macrophagesTG. Collectively, the increased antitumor activity of CD8+ T cells was mediated by the ApoC3-stimulated inflammasome activation of macrophages, and the mimetic ApoC3 peptides that can bind TLR2/4 could be a future strategy to target liver cancer.

Comprehensive review on the pathogenesis of hypertriglyceridaemia-associated acute pancreatitis

It is well known, that the inflammatory process that characterizes acute pancreatitis (AP) can lead to both pancreatic damage and systemic inflammatory response syndrome (SIRS). During the last 20 years, there has been a growing incidence of episodes of acute pancreatitis associated with hypertriglyceridaemia (HTAP). This review provides an overview of triglyceride metabolism and the potential mechanisms that may contribute to developing or exacerbating HTAP. The article comprehensively discusses the various pathological roles of free fatty acid, inflammatory response mechanisms, the involvement of microcirculation, serum calcium overload, oxidative stress and the endoplasmic reticulum, genetic polymorphism, and gut microbiota, which are known to trigger or escalate this condition. Future perspectives on HTAP appear promising, with ongoing research focused on developing more specific and effective treatment strategies.

Neddylation-mediated degradation of hnRNPA2B1 contributes to hypertriglyceridemia pancreatitis

Hypertriglyceridemia-induced acute pancreatitis (HTGP) is characterized by the acute and excessive release of FFA produced by pancreatic lipases. However, the underlying mechanisms of this disease remain poorly understood. In this study, we describe the involvement of the RNA binding protein hnRNPA2B1 in the development of HTGP. We used palmitic acid (PA) and AR42J cells to create a model of HTGP in vitro. RT-PCR and western blot analyses revealed a decrease in the level of hnRNPA2B1 protein but not mRNA expression in PA-treated cells. Further analyses revealed that hnRNPA2B1 expression was regulated at the post-translational level by neddylation. Restoration of hnRNPA2B1 expression using the neddylation inhibitor MLN4924 protected AR42J cells from PA-induced inflammatory injury by preventing NF-κB activation and restoring fatty acid oxidation and cell proliferation. Furthermore, RNA immunoprecipitation studies demonstrated that hnRNPA2B1 orchestrates fatty acid oxidation by regulating the expression of the mitochondrial trifunctional protein-α (MTPα). Administration of MLN4924 in vivo restored hnRNPA2B1 protein expression in the pancreas of hyperlipidemic mice and ameliorated HTGP-associated inflammation and pancreatic tissue injury. In conclusion, we show that hnRNPA2B1 has a central regulatory role in preventing HTGP-induced effects on cell metabolism and viability. Furthermore, our findings indicate that pharmacological inhibitors that target neddylation may provide therapeutic benefits to HTGP patients.

miR-223-3p contributes to suppressing NLRP3 inflammasome activation in Streptococcus equi ssp. zooepidemicus infection

Streptococcus equi subsp. zooepidemicus (SEZ) is an essential pathogen in a range of species, causing a worldwide variety of diseases, such as meningitis, endocarditis, and septicaemia. Studies have shown that microRNAs (miRNAs), which regulate target genes at the post-transcriptional level, play an important regulatory role in the organism. In this study, the infection of J774A.1 murine macrophages with SEZ up-regulated NLRP3 inflammasome and downstream pathways accompanied by miR-223-3p down-regulation. Through computational prediction and experimental confirmation, we have shown that miR-223-3p directly targets the NLRP3 mRNA. Consequently, overexpression of miR-223-3p suppressed NLRP3 inflammasome activation and downstream pathways in response to SEZ infection. The miR-223-3p inhibitor exhibited the opposite effect, causing hyperactivation of NLRP3 inflammation activation and downstream pathways. Additionally, we further demonstrated that miRNA-223-3p inhibited the secretion of IL-1β and IL-18 by regulating the NLRP3/caspase-1 pathway. Furthermore, intravenous administration of miR-223-3p significantly decreased inflammation in mice in response to SEZ. In conclusion, our results demonstrated that miR-223-3p contributes to suppressing the NLRP3 inflammasome activation in SEZ infection, contributing novel evidence to identify a therapeutic target for treating SEZ.

Hypertriglyceridemia Acute Pancreatitis: Animal Experiment Research

In recent years, the number of acute pancreatitis cases caused by hypertriglyceridemia has increased gradually, which has caught the attention of the medical community. However, because the exact mechanism of hypertriglyceridemic acute pancreatitis (HTG-AP) is not clear, treatment and prevention in clinical practice face enormous challenges. Animal models are useful for elucidating the pathogenesis of diseases and developing and testing novel interventions. Therefore, animal experiments have become the key research means for us to understand and treat this disease. We searched almost all HTG-AP animal models by collecting many studies and finally collated common animals such as rats, mice and included some rare animals that are not commonly used, summarizing the methods to model spontaneous pancreatitis and induce pancreatitis. We sorted them on the basis of three aspects, including the selection of different animals, analyzed the characteristics of different animals, different approaches to establish hypertriglyceridemic pancreatitis and their relative advantages and disadvantages, and introduced the applications of these models in studies of pathogenesis and drug therapy. We hope this review can provide relevant comparisons and analyses for researchers who intend to carry out animal experiments and will help researchers to select and establish more suitable animal experimental models according to their own experimental design.

A Severe Acute Pancreatitis Mouse Model Transited from Mild Symptoms Induced by a “Two-Hit” Strategy with L-Arginine

To develop a severe acute pancreatitis (SAP) model transited from mild symptoms, we investigated a “two-hit” strategy with L-arginine in mice. The mice were intraperitoneally injected with ice-cold L-arginine (4 g/kg) twice at an interval of 1 h on the first day and subjected to the repeated operation 72 h afterwards. The results showed the “two-hit” strategy resulted in the destructive damage and extensive necrosis of acinar cells in the pancreas compared with the “one-hit” model. Meanwhile, excessive levels of pro-inflammatory mediators, namely IL-6 and TNF-α, were released in the serum. Remarkably, additional deleterious effects on multiple organs were observed, including high intestinal permeability, kidney injury, and severe acute lung injury. Therefore, we confirmed that the SAP animal model triggered by a “two-hit” strategy with L-arginine was successfully established, providing a solid foundation for a deeper understanding of SAP initiation and therapy research to prevent worsening of the disease.

LIGHT of pulmonary NKT cells annihilates tissue protective alveolar macrophages in augmenting severe influenza pneumonia

CD1d-restricted natural killer T (NKT) cells are innate-like T lymphocytes with protective or pathogenic roles in the development of influenza pneumonia. Here, we show that lung-infiltrated and activated NKT cells are the major cellular source of LIGHT/TNFSF14, which determines the severity of pulmonary pneumonia by highly deteriorative influenza A virus (IAV) infection. Compared to wild-type mice, LIGHT^-/- mice exhibit much lower morbidity and mortality to IAV, due to alleviated lung damage and reduced apoptosis of alveolar macrophages (AMs). LIGHT preferentially promotes cell death of lymphotoxin β receptors positive (LTβR⁺) AMs but not herpesvirus entry mediator positive (HVEM⁺) AMs. Therefore, these results suggest that NKT-derived LIGHT augments cell death of the tissue protective AMs in exacerbating lung pathology and susceptibility to fatal influenza infection. Suppression of LIGHT signaling might be a viable option in the treatment of influenza-associated acute respiratory distress syndrome.

Sleeve Gastrectomy Attenuates the Severity of Cerulein-Induced Acute Pancreatitis in Obese Rats

PURPOSE

Obesity is one of the most important risk factors for acute pancreatitis. Based on the effect of sleeve gastrectomy (SG) on improving body weight and blood lipids, we investigated whether SG is beneficial in improving pancreatitis in obese rats.

MATERIALS AND METHODS

Two studies were used to evaluate the effect of SG on the first onset of pancreatitis and acute episodes of recurrent pancreatitis in obese rats. A high-fat diet (HFD) for 8 weeks resulted in obesity in rats. Study 1: Obese rats were treated with SG and sham surgery. Pancreatitis was induced by intraperitoneal injection of cerulein at 6 weeks after surgery. The severity of pancreatitis was assessed by histological examination, cytokines, and infiltration of inflammatory cells. Study 2 performed the same procedure as in study 1, except that rats were intraperitoneally injected with a small dose of cerulein three times a week for 6 weeks before surgery to induce recurrent pancreatitis.

RESULTS

The body weight, food intake, and blood lipids of SG rats in study 1 and study 2 were significantly lower than those of sham rats during the 6 weeks after surgery. Compared with sham rats, SG rats in both studies had fewer inflammatory cytokines, inflammatory cell infiltration, and pathological injury in the pancreas after cerulein-induced acute pancreatitis.

CONCLUSION

SG reduces the severity of the first onset of pancreatitis and the seriousness of acute episodes of recurrent pancreatitis. The improvement of lipid metabolism and body weight by SG may play an important role in this effect.

Acinar cell NLRP3 inflammasome and gasdermin D (GSDMD) activation mediates pyroptosis and systemic inflammation in acute pancreatitis

BACKGROUND AND PURPOSE

Pyroptosis is a lytic form of pro-inflammatory cell death characterised as caspase 1 dependent with canonical NLRP3 inflammasome-induced gasdermin D (GSDMD) activation. We aimed to investigate the role of acinar pyroptotic cell death in pancreatic injury and systemic inflammation in AP.

EXPERIMENTAL APPROACH

Pancreatic acinar pyroptotic cell death pathway activation upon pancreatic toxin stimulation in vitro and in vivo was investigated. Effects of pharmacological (NLRP3 and caspase-1 inhibitors), constitutive (Nlrp3^-/- , Casp1^-/- and Gsdmd^-/- ) and acinar cell conditional (Pdx1^Cre Nlrp3^Δ/Δ and Pdx1^Cre Gsdmd^Δ/Δ ) genetic inhibition on pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation were assessed using mouse AP models (caerulein, sodium taurocholate and l-arginine). Effects of Pdx1^Cre Gsdmd^Δ/Δ versus myeloid conditional knockout (Lyz2^Cre Gsdmd^Δ/Δ ) and Gsdmd^-/- versus receptor-interacting protein 3 (RIP3) inhibitor were compared in CER-AP.

KEY RESULTS

There was consistent pyroptotic acinar cell death upon pancreatic toxin stimulation both in vitro and in vivo, which was significantly reduced by pharmacological or genetic pyroptosis inhibition. Pdx1^Cre Gsdmd^Δ/Δ but not Lyz2^Cre Gsdmd^Δ/Δ mice showed significantly reduced pyroptotic acinar cell death, pancreatic necrosis and systemic inflammation in caerulein-AP. Co-application of RIP3 inhibitor on Gsdmd^-/- mice further increased protection on caerulein-AP.

CONCLUSION AND IMPLICATIONS

This work demonstrates a critical role for NLRP3 inflammasome and GSDMD activation-mediated pyroptosis in acinar cells, linking pancreatic necrosis and systemic inflammation in AP. Targeting pyroptosis signalling pathways holds promise for specific AP therapy.

Cathepsin B aggravates acute pancreatitis by activating the NLRP3 inflammasome and promoting the caspase-1-induced pyroptosis

OBJECTIVES

Cathepsin B (CTSB), nod-like receptor family pyrin domain-containing 3 (NLRP3), and caspase-1 play an important role in the development of Acute Pancreatitis (AP). Besides, the relationship between the proteins remains poorly understood. In addition, whereas previous studies have found caspase-1 activation in AP, pyroptosis, a caspase-1 induced cell death mode, has never been proposed and proved in AP.

METHODS

We induced AP in mice by intraperitoneal injection of cerulein. Mice in the inhibitor group of CTSB were pretreated with injection of CA-074me, while mice in the inhibitor group of caspase-1 were of Ac-YVAD-CHO, 1 h earlier. We evaluated the inflammation of the pancreas and the detected expression of activated CTSB, NLRP3, ASC, caspase-1p20, IL-1β and IL-18. TUNEL staining was used to detect acinar cell death.

RESULTS

The inflammation of the pancreas in the two inhibitor groups was significantly reduced compared with that in the AP group. We observed that CA-074me not only inhibits CTSB, but also suppresses the expression and activity of NLRP3, ASC and caspase-1. We found that CA-074me further inhibits the downstream event of caspase-1, including pro-inflammatory cytokine secretion and pyroptosis. Whereas Ac-YVAD-CHO inhibited caspase-1 and decreased pro-inflammatory cytokine secretion and pyroptosis, it did not down-regulate the expression and activity ofCTSB, NLRP3 and ASC.

CONCLUSION

The results indicate that CTSB may aggravate AP by activating the NLRP3 inflammasome and promoting Caspase-1-induced pyroptosis. These provide clues about the pathophysiological mechanisms of AP, shedding light on new ideas and potential targets for the prevention and treatment of AP.

Dysregulated SREBP1c/miR-153 signaling induced by hypertriglyceridemia worsens acute pancreatitis and delays tissue repair

Severe acute pancreatitis (AP) is a life-threatening disease with up to 30% mortality. Therefore, prevention of AP aggravation and promotion of pancreatic regeneration are critical during the course and treatment of AP. Hypertriglyceridemia (HTG) is an established aggravating factor for AP that hinders pancreatic regeneration; however, its exact mechanism remains unclear. Using miRNA sequencing and further verification, we found that miRNA-153 (miR-153) was upregulated in the pancreas of HTG animal models and in the plasma of patients with HTG-AP. Increased miR-153 aggravated HTG-AP and delayed pancreatic repair via targeting TRAF3. Furthermore, miR-153 was transcriptionally suppressed by sterol regulatory element-binding transcription factor 1c (SREBP1c), which was suppressed by lipoprotein lipase malfunction-induced HTG. Overexpressing SREBP1c suppressed miR-153 expression, alleviated the severity of AP, and facilitated tissue regeneration in vivo. Finally, therapeutic administration of insulin also protected against HTG-AP via upregulating SREBP1c. Collectively, our results not only provide evidence that HTG leads to the development of more severe AP and hinders pancreatic regeneration via inducing persistent dysregulation of SREBP1c/miR-153 signaling, but also demonstrate that SREBP1c activators, including insulin, might be used to treat HTG-AP in patients.

Tanshinone IIA Protects against Acute Pancreatitis in Mice by Inhibiting Oxidative Stress via the Nrf2/ROS Pathway

Background

Danshen (Salvia miltiorrhiza Bunge) and its main active component Tanshinone IIA (TSA) are clinically used in China. However, the effects of TSA on acute pancreatitis (AP) and its potential mechanism have not been investigated. In this study, our objective was to investigate the protective effects of TSA against AP via three classic mouse models.

Methods

Mouse models of AP were established by caerulein, sodium taurocholate, and L-arginine, separately. Pancreatic and pulmonary histopathological characteristics and serum amylase and lipase levels were evaluated, and changes in oxidative stress injury and the ultrastructure of acinar cells were observed. The reactive oxygen species (ROS) inhibitor N-Acetylcysteine (NAC) and nuclear factor erythroid 2-related factor 2 (Nrf2) knockout mice were applied to clarify the protective mechanism of the drug.

Results

In the caerulein-induced AP model, TSA administration reduced serum amylase and lipase levels and ameliorated the histopathological manifestations of AP in pancreatic tissue. Additionally, TSA appreciably decreased ROS release, protected the structures of mitochondria and the endoplasmic reticulum, and increased the protein expression of Nrf2 and heme oxygenase 1 of pancreatic tissue. In addition, the protective effects of TSA against AP were counteracted by blocking the oxidative stress (NAC administration and Nrf2 knockout in mice). Furthermore, we found that TSA protects pancreatic tissue from damage and pancreatitis-associated lung injury in two additional mouse models induced by sodium taurocholate and by L-arginine.

Conclusion

Our data confirmed the protective effects of TSA against AP in mice by inhibiting oxidative stress via the Nrf2/ROS pathway.

Identification of a novel LPL nonsense variant and further insights into the complex etiology and expression of hypertriglyceridemia-induced acute pancreatitis

Background

Hypertriglyceridemia (HTG) is a leading cause of acute pancreatitis. HTG can be caused by either primary (genetic) or secondary etiological factors, and there is increasing appreciation of the interplay between the two kinds of factors in causing severe HTG.

Objectives

The main aim of this study was to identify the genetic basis of hypertriglyceridemia-induced acute pancreatitis (HTG-AP) in a Chinese family with three affected members (the proband, his mother and older sister).

Methods

The entire coding and flanking sequences of LPL, APOC2, APOA5, GPIHBP1 and LMF1 genes were analyzed by Sanger sequencing. The newly identified LPL nonsense variant was subjected to functional analysis by means of transfection into HEK-293 T cells followed by Western blot and activity assays. Previously reported pathogenic LPL nonsense variants were collated and compared with respect to genotype and phenotype relationship.

Results

We identified a novel nonsense variant, p.Gln118* (c.351C > T), in the LPL gene, which co-segregated with HTG-AP in the Chinese family. We provided in vitro evidence that this variant resulted in a complete functional loss of the affected LPL allele. We highlighted a role of alcohol abuse in modifying the clinical expression of the disease in the proband. Additionally, our survey of 12 previously reported pathogenic LPL nonsense variants (in 20 carriers) revealed that neither serum triglyceride levels nor occurrence of HTG-AP was distinguishable among the three carrier groups, namely, simple homozygotes, compound heterozygotes and simple heterozygotes.

Conclusions

Our findings, taken together, generated new insights into the complex etiology and expression of HTG-AP.

Acute Pancreatitis Induced by Diabetic Ketoacidosis with Major Hypertriglyceridemia: Report of Four Cases

Acute pancreatitis (AP) is a real clinical challenge. Acute pancreatitis remains a common cause of emergency department consultations and a major cause for hospitalization. Gallstones and drinking a lot of alcohol are the most frequent causes of AP. Moreover, AP can be induced by diabetic ketoacidosis (DKA) complicated by hypertriglyceridemia. We report 4 cases of DKA with hypertriglyceridemia complicated by AP in previously undiagnosed diabetes patients. All of our patients presented to the emergency ward with abdominal pain. Their physical exam showed epigastric tenderness. An abdominal CT scan was performed for each patient, showing an AP grade E. Laboratory samples showed high serum glucose levels. They had metabolic acidosis with elevated anion gap. They had high lipasemia and amylasemia. Their lipid panel was disturbed with a high level of cholesterol (from 12.8 mmol/l to 33 mmol/l) and triglyceridemia (from 53 to 133 mmol/l). Our patients were admitted into our ICU where they received fluid resuscitation and intravenous insulin, and their triglycerides rates decreased gradually. Two patients recovered to a good health state, and the two others developed septic shock, requiring the use of large-spectrum antibiotics, and acute kidney injury (AKI) with refractory metabolic acidosis, requiring hemodialysis. Despite the intensive treatment, they developed an unrecoverable multiorgan failure. Through our case series, we aim to highlight the importance of making an early diagnosis, which can be difficult in some situations due to overlapping signs; however, it is crucial for a good recovery. A good understanding of the pathway of hypoinsulinemic states causing hypertriglyceridemia then AP is important because it is the key to best management.

Large triglyceride-rich lipoproteins in hypertriglyceridemia are associated with the severity of acute pancreatitis in experimental mice

Hypertriglyceridemia severity is linked to acute pancreatitis prognosis, but it remains unknown why a portion of severe hypertriglyceridemia patients do not develop severe acute pancreatitis. To investigate whether hypertriglyceridemia subtypes affect acute pancreatitis progression, we analyzed two genetically modified hypertriglyceridemia mouse models—namely, glycosylphosphatidylinositol high-density lipoprotein binding protein 1 knockout (Gpihbp1−/−) and apolipoprotein C3 transgenic (ApoC3-tg) mice. Acute pancreatitis was induced by 10 intraperitoneal caerulein injections. Biochemical assays and pathological analysis were performed for the severity evaluation of acute pancreatitis. Plasma triglyceride-rich lipoproteins (TRLs), including chylomicrons and very low-density lipoprotein (VLDL), were collected via ultracentrifugation to evaluate their cytotoxic effects on primary pancreatic acinar cells (PACs). We found that the particle sizes of Gpihbp1−/− TRLs were larger than ApoC3-tg TRLs. Severe pancreatic injury with large areas of pancreatic necrosis in the entire lobule was induced in Gpihbp1−/− mice when plasma triglyceride levels were greater than 2000 mg/dL. However, ApoC3-tg mice with the same triglyceride levels did not develop large areas of pancreatic necrosis, even upon the administration of poloxamer 407 to further increase triglyceride levels. Meanwhile, in the acute pancreatitis model, free fatty acids (FFAs) in the pancreas of Gpihbp1−/− mice were greater than in ApoC3-tg mice. TRLs from Gpihbp1−/− mice released more FFAs and were more toxic to PACs than those from ApoC3-tg mice. Chylomicrons from patients showed the same effects on PACs as TRLs from Gpihbp1−/− mice. Gpihbp1−/− mice with triglyceride levels below 2000 mg/dL had milder pancreatic injury and less incidence of pancreatic necrosis than those with triglyceride levels above 2000 mg/dL, similar to Gpihbp1−/−mice with triglyceride levels above 2000 mg/dL but with fenofibrate administration. These findings demonstrated that hypertriglyceridemia subtypes with large TRL particles could affect acute pancreatitis progression and that chylomicrons showed more cytotoxicity than VLDL by releasing more FFAs.

GC-MS based metabolomics strategy to distinguish three types of acute pancreatitis

Acute pancreatitis (AP) is a progressive systemic inflammatory response with high morbidity and high mortality, which is mainly caused by alcohol, bulimia, gallstones and hyperlipidemia. The early diagnosis of different types of AP and further explore potential pathophysiological mechanism of each type of AP is beneficial for optimized treatment strategies and better patient's care. In this study, a metabolomics approach based on gas chromatography-mass spectrometry (GC-MS), and random forests algorithm was established to distinguish biliary acute pancreatitis (BAP), Hyperlipidemia acute pancreatitis (HLAP), and alcoholic acute pancreatitis (AAP), from healthy controls. The classification accuracies for BAP, HLAP, and AAP patients compared with healthy control, were 0.886, 0.906 and 0.857, respectively, by using 5-fold cross-validation method. And some special metabolites for each type of AP were discovered, such as l-Lactic acid, (R)-3-Hydroxybutyric acid, Phosphoric acid, Glycine, Erythronic acid, l-Phenylalanine, d-Galactose, l-Tyrosine, Arachidonic acid, Glycerol 1-hexadecanoate. Furthermore, associations between these metabolites with the metabolism of amino acids, fatty acids were identified. Our studies have illuminated the biomarkers and physiological mechanism of disease in a clinical setting, which suggested that metabolomics is a valuable tool for identifying the molecular mechanisms that are involved in the etiology of BAP, AAP, HLAP and thus novel therapeutic targets.

Protective effects of HTD4010, a Reg3α/PAP-derived peptide, in mouse model of acute pancreatitis via toll-like receptor 4 pathway

Acute pancreatitis (AP) is one of the most common digestive tract diseases, but effective drug therapy is still lack. Regenerating gene protein 3α (Reg3α) administration significantly reduced the severity of AP in mice. HTD4010 is a new 15 amino acid long synthetic peptide and its biological activities are similar to Reg3α. This study aimed to explore whether HTD4010 could protect pancreatic acinar cells against necrosis and decrease the inflammatory response in AP, and thus to explore underlying mechanisms. It was shown that administration of HTD4010 alleviated significantly the severity of biliary AP (BAP), characterized as less degree of pancreatic histological damage and acinar cell injury (both apoptosis and necroptosis), lower levels of serum amylase and pro-inflammatory cytokines. Moreover, HTD4010 down-regulated the expression of toll-like receptor 4 (TLR4) protein, and TLR4 deficiency eliminated the protective effect of HTD4010 on BAP in mice. In conclusion, these results showed that HTD4010 could alleviate the severity of pancreatitis, reduce the acinar cells necrosis and inflammatory response possibly by TLR4 signaling pathway in AP.

TSG-6 secreted by human adipose tissue-derived mesenchymal stem cells ameliorates severe acute pancreatitis via ER stress downregulation in mice

Background

Through recent studies, the onset of acute pancreatitis in pancreatic acinar cells (PACs) and the regulatory role of PACs in severe acute pancreatitis (SAP) have been revealed. During the early stages of pancreatitis, the endoplasmic reticulum (ER) in PACs undergoes significant changes, including swelling and vacuolization. In response to an increase in the extracellular stress in ER, PACs lose their functions, leading to cell apoptosis and inflammation response. The beneficial effects of human adipose tissue-derived mesenchymal stem cells (hAT-MSCs) on SAP have been well documented in previous studies. However, the underlying mechanism of their action remains controversial.

Methods

In this study, the therapeutic effects of intraperitoneally administered hAT-MSCs in a caerulein (50 μg/kg)- and lipopolysaccharide (LPS) (10 mg/kg)-co-induced SAP mouse model were evaluated. Inflammatory response and ER stress were measured in pancreatic tissue samples, and the beneficial effects were evaluated through quantitative reverse transcription polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence analysis.

Results

Inflammatory response and ER stress were ameliorated following hAT-MSC injection, and the beneficial effects were observed in the absence of significant engraftment of hAT-MSCs. hAT-MSCs transfected with siRNA-targeting tumour necrosis factor-α-induced gene/protein 6 (TSG-6) were unable to inhibit ER stress and inflammation. In addition, TSG-6 from hAT-MSCs significantly suppressed ER stress-induced apoptosis and nuclear factor kappa B (NF-κB) activity in SAP model mice.

Conclusions

TSG-6 secreted by hAT-MSCs protects PACs in SAP model mice via the inhibition of ER stress, as well as inflammatory responses. This study has revealed a new area for ER stress-targeted therapy in SAP patients.

Graphical abstract

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1009-8) contains supplementary material, which is available to authorized users.

SB203580 attenuates acute lung injury and inflammation in rats with acute pancreatitis in pregnancy

Acute pancreatitis in pregnancy (APIP) can lead to multiple maternal and fetal organ injury and mitogen-activated protein kinase (MAPK) signaling pathway may be involved in it; however, whether APIP can result in acute lung injury and P38MAPK signaling pathway is involved in the pathogenesis has not been elucidated. The present study was undertaken to investigate the participation of P38MAPK signaling pathway and the protective effect of SB203580, an inhibitor of P38MAPK on acute lung injury induced by APIP. Twenty-four late-gestation SD rats were randomly assigned to four groups: Sham operation (SO) group, SB302580 (SB) group, APIP group, and SB + APIP group. All the rats were killed 6 h after modeling. The severity of pancreatitis was evaluated by serum amylase (AMY) and lipase (LIPA) and histopathological changes. Histological assessment of the lung and inflammatory cell infiltration was performed by H&E and immunofluorescence assay. The lung wet/dry (W/D) weight ratio was determined, and the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were detected by enzyme-linked immunosorbent assay (ELISA). Western blot analysis was used to detect the protein expression of phosphorylated and total P38, tumor necrosis factor (TNF)-α, and intercellular adhesion molecules 1 (ICAM-1) in lung tissues. Obvious pathological changes existed in pancreas and lung after the induction of APIP, and their pathological scores were significantly higher than that of control group. The results showed that the phosphorylation of P38MAPK was elevated in the lung of APIP rats. Compared with APIP group, the intervention of SB203580 alleviated the pathological injury of the pancreas and lungs, decreased serum AMY and LIPA, attenuated the secretion of TNF-α, IL-1β, and IL-6 in lung, reduced the inflammatory cells' infiltration and lung W/D ratio and inhibited the activation of P38MAPK signaling pathway. These results suggest that APIP can lead to acute lung injury and inflammation and SB203580 can inhibit the lung injury by inhibiting the P38MAPK signaling pathway and blocking the inflammatory responses.

Diabetes aggravates acute pancreatitis possibly via activation of NLRP3 inflammasome in db/db mice

Clinical studies have confirmed that patients with diabetes had an elevated risk of acute pancreatitis (AP) and diabetes was associated with increased severity and mortality in patients with AP. However, these studies failed to prove a cause-and-effect relationship between diabetes and AP. In the present study, we for the first time have evaluated the effects of diabetes on AP by adopting a type 2 diabetes animal model db/db mice and investigated the possible underlying mechanisms. The results showed that in comparison to wide type (WT) mice, db/db mice showed exacerbated pancreatic and pulmonary injuries, elevated serum amylase and lipase levels, increased myeloperoxidase (MPO) expressions in pancreatic and pulmonary tissues as well as increased apoptotic acinar cells after AP induction. Furthermore, we observed that NLRP3 inflammasome in pancreatic tissues was remarkably activated in db/db mice compared with WT mice. In addition, we also found that diabetes could increase the susceptibility of mice to AP. Taken together, our results indicated that diabetes could predispose and aggravate the disease severity of AP potentially via promoting the activation of NLRP3 inflammasome pathway.

INT-777, a bile acid receptor agonist, extenuates pancreatic acinar cells necrosis in a mouse model of acute pancreatitis

Bile acids receptor TGR5 and its agonist INT-777, which has been found to be involved in the NLRP3 inflammasome pathway, play an important role in inflammatory diseases. However, the role of INT-777 in acute pancreatitis (AP) has not been reported. In this present study, we found that TGR5 was expressed in pancreatic tissue and increased after AP onset induced by caerulein and further evaluated the impact of INT-777 on the severity of AP. The results showed that INT-777 could reduce the severity of AP in mice, which was manifested as decreased pancreatic tissue damage as well as the decrease of serum enzymes (amylase and lipase), pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and the expression of necrosis related proteins (RIP3 and p-MLKL). Furthermore, we found that INT-777 reduced the reactive oxygen species (ROS) production in pancreatic acinar cells and inhibited the activation of NLRP3 inflammasome pathway. In conclusion, our data showed that INT-777 could protect pancreatic acinar cell against necrosis and reduce the severity of AP, which may be mediated by inhibiting ROS/NLRP3 inflammasome pathway.

Isoliquiritigenin Ameliorates Acute Pancreatitis in Mice via Inhibition of Oxidative Stress and Modulation of the Nrf2/HO-1 Pathway

Oxidative stress plays a crucial role in the pathogenesis of acute pancreatitis (AP). Isoliquiritigenin (ISL) is a flavonoid monomer with confirmed antioxidant activity. However, the specific effects of ISL on AP have not been determined. In this study, we aimed to investigate the protective effect of ISL on AP using two mouse models. In the caerulein-induced mild acute pancreatitis (MAP) model, dynamic changes in oxidative stress injury of the pancreatic tissue were observed after AP onset. We found that ISL administration reduced serum amylase and lipase levels and alleviated the histopathological manifestations of pancreatic tissue in a dose-dependent manner. Meanwhile, ISL decreased the oxidative stress injury and increased the protein expression of the Nrf2/HO-1 pathway. In addition, after administering a Nrf2 inhibitor (ML385) or HO-1 inhibitor (zinc protoporphyrin) to block the Nrf2/HO-1 pathway, we failed to observe the protective effects of ISL on AP in mice. Furthermore, we found that ISL mitigated the severity of pancreatic tissue injury and pancreatitis-associated lung injury in a severe acute pancreatitis model induced by L-arginine. Taken together, our data for the first time confirmed the protective effects of ISL on AP in mice via inhibition of oxidative stress and modulation of the Nrf2/HO-1 pathway.

Formononetin Administration Ameliorates Dextran Sulfate Sodium-Induced Acute Colitis by Inhibiting NLRP3 Inflammasome Signaling Pathway

Formononetin is a kind of isoflavone compound and has been reported to possess anti-inflammatory properties. In this present study, we aimed to explore the protective effects of formononetin on dextran sulfate sodium- (DSS-) induced acute colitis. By intraperitoneal injection of formononetin in mice, the disease severity of colitis was attenuated in a dose-dependent manner, mainly manifesting as relieved clinical symptoms of colitis, mitigated colonic epithelial cell injury, and upregulations of colonic tight junction proteins levels (ZO-1, claudin-1, and occludin). Meanwhile, our study found that formononetin significantly prevented acute injury of colonic cells induced by TNF-α in vitro, specifically manifesting as the increased expressions of colonic tight junction proteins (ZO-1, claudin-1, and occludin). In addition, the result showed that formononetin could reduce the NLRP3 pathway protein levels (NLRP3, ASC, IL-1β) in vivo and vitro, and MCC950, the NLRP3 specific inhibitor, could alleviate the DSS-induced mice acute colitis. Furthermore, in the foundation of administrating MCC950 to inhibit activation of NLRP3 inflammasome, we failed to observe the protective effects of formononetin on acute colitis in mice. Collectively, our study for the first time confirmed the protective effects of formononetin on DSS-induced acute colitis via inhibiting the NLRP3 inflammasome pathway activation.