Cell death and DAMPs in acute pancreatitis

Therapeutic potential of Da Cheng Qi Decoction and its ingredients in regulating ferroptosis via the NOX2-GPX4 signaling pathway to alleviate and predict severe acute pancreatitis

OBJECTIVE

This study aimed to elucidate the protective effects of Da Cheng Qi Decoction (DCQD) on severe acute pancreatitis (SAP) by targeting ferroptosis in pancreatic acinar cells and to establish a predictive signature and nomogram for acute pancreatitis (AP) risk assessment.

METHODS

We utilized microarray analysis to delineate gene expression patterns among 32 healthy controls and 87 AP patients stratified by severity. Employing SAP models and NOX2-deficient cells, we investigated the molecular underpinnings of ferroptosis. The impact of DCQD and the ferroptosis inhibitor Fer-1 on gene expression, oxidative stress, and inflammation was assessed. Machine learning algorithms identified differentially expressed genes (DEGs) sensitive to DCQD, SAP, and ferroptosis (DSNFGs), which were validated across multiple datasets. A predictive nomogram integrating DSNFGs was developed, and single-cell analysis provided a comprehensive view of the cellular dynamics.

RESULTS

The microarray analysis revealed upregulation of NOX2 and downregulation of GPX4 in AP, with expression patterns correlating with disease severity. DCQD ameliorated SAP-induced pancreatic acinar cell damage and ferroptosis by reducing inflammatory markers and enhancing GPX4 expression. NOX2 knockout mitigated ferroptosis in SAP models, suggesting a key role in the disease process. DCQD and Fer-1 differentially regulated the expression of ferroptosis-related genes, reduced reactive oxygen species (ROS) and high-mobility group box 1 (HMGB1) levels, and suppressed the inflammatory response in a SAP mouse model. The HPLC analysis of DCQD constituents indicated eight components (aloe-emodin, rhein, emodin, chrysophanol, naringin, hesperidin, magnolol, and honokiol) with the capacity to modulate ferroptosis. Venn analysis identified 48 DSNFGs, with a subset of five genes demonstrating significant predictive value. The developed nomogram, based on LASSO regression, showed high accuracy in validation cohorts. Single-cell RNA sequencing (scRNA-seq) and CellChat analysis uncovered heterogeneity and cell-cell communication networks in the pancreas during recovery from pancreatitis, implicating several signaling pathways.

CONCLUSION

DCQD and its eight ingredients exert its protective effect in SAP by inhibiting ferroptosis through the NOX2/GPX4 pathway. The DCQD-SAP-ferroptosis-related signature and nomogram offer a novel tool for AP risk assessment, prognosis prediction, and personalized therapeutic strategies in SAP management.

Metformin aggravates pancreatitis by regulating the release of oxidised mitochondrial DNA via the frataxin (FXN)/ninjurin 1 (NINJ1) signalling pathway

BACKGROUND AND PURPOSE

Patients with diabetes are at a higher risk of developing acute pancreatitis compared to those without diabetes. Therefore, it is essential to investigate the effects of metformin, a primary treatment for type 2 diabetes, on the progression of pancreatitis.

EXPERIMENTAL APPROACH

Network pharmacology was employed to investigate the potential effects of metformin on pancreatitis and to predict its underlying molecular mechanisms. Pharmacological and mechanistic studies of metformin were conducted utilising mtDNA depletion (ρ0) of 266-6 acinar cells, knockout mouse models and experimental models of both acute and chronic pancreatitis. The mitochondrial homeostasis and plasma membrane integrity were examined through phase-contrast microscopy and time-lapse video imaging.

KEY RESULTS

Network pharmacology analysis revealed that metformin possesses significant potential to modulate the pathogenesis of pancreatitis, likely through its regulation of mitochondrial function and cell membrane morphology. Further, the results revealed that metformin augmented the release of oxidised mitochondrial DNA (Ox-mtDNA) by enhancing NINJ1-mediated plasma membrane rupture, which subsequently ignited a cascade of acinar cell necrosis. Metformin exacerbated mitochondrial iron imbalance by suppressing Frataxin, thereby worsening mitochondrial homeostasis disruption and Ox-mtDNA generation. NINJ1 knockout eliminated the metformin-induced acinar cell necrosis and elevation of Ox-mtDNA levels, and mtDNA depletion reversed the effect of metformin on acinar cell death.

CONCLUSION AND IMPLICATIONS

Metformin exacerbates both acute and chronic pancreatitis, possibly because of increased release of Ox-mtDNA via modulation of mitochondrial iron homeostasis and NINJ1-mediated plasma membrane rupture, suggesting that extreme caution should be exercised when using metformin in diabetic patients with pancreatitis.

Octreotide attenuates experimental severe acute pancreatitis through inhibiting pyroptosis and modulating intestinal homeostasis

Severe acute pancreatitis (SAP) is a common clinical condition characterized by acute abdominal symptoms. Octreotide (OCT) is a commonly prescribed treatment for acute pancreatitis (AP). Recent research shows that pyroptosis and intestinal homeostasis significantly contribute to the progression of AP. However, it remains unclear whether OCT treats SAP through modulating pyroptosis and intestinal microbiota. Our study aimed to investigate and validate the potential therapeutic effects of OCT on SAP and underlying mechanisms. The inhibition of pyroptosis in mice using disulfiram was investigated to elucidate the role of pyroptosis in AP. Molecular biology experiments confirmed that OCT effectively inhibited the expression of pyroptosis-related markers. Additionally, the composition, abundance, and functionality of the intestinal microbiota were analyzed using 16S rRNA sequencing, while short-chain fatty acids (SCFAs) were quantified by targeted metabolomics. Our study demonstrated that the administration of OCT significantly mitigated the severity of SAP in a dose-dependent manner. Furthermore, the inhibition of pyroptosis in mice attenuated SAP, thereby highlighting the critical role of pyroptosis in this condition. OCT administration was observed to suppress the expression of key pyroptosis markers. Additionally, there was a notable reduction in intestinal permeability and bacterial translocation. OCT reverses gut dysbiosis caused by SAP, increasing beneficial bacteria while inhibiting pathogenic strains. Furthermore, OCT administration enhanced the levels of SCFAs, including propanoic acid, acetic acid, and butyric acid. Our findings indicate OCT has the potential to alleviate SAP by suppressing pyroptosis and restoring intestinal homeostasis.

Inhibition of Zbp1-PANoptosome-mediated PANoptosis effectively attenuates acute pancreatitis

Early acute pancreatitis is an acute inflammatory disease that involves multiple modes of cell death, including apoptosis, necrotic apoptosis, and pyroptosis in its disease process. PANoptosis, a type of cell death that includes pyroptosis, apoptosis, and necroptosis, has had an important role in a variety of infectious and inflammatory diseases in recent years. To judge the relationship between PANoptosis and AP, we first analyzed the data from pancreatic transcriptome data by bioinformatics techniques, and we found the enrichment of PANoptosis pathway in AP. Next, we screened the genes and identified differentially expressed genes (DEGs) associated with AP and PANoptosis. Finally, we found that Zbp1 may have a major role in the process of PANoptosis. For this purpose, we constructed AP models in mice and in vitro cell line 266-6 and intervened by inhibiting Zbp1. The final results showed that the PANoptosis in mice was significantly suppressed after inhibition of Zbp1. In conclusion, inflammatory injury in AP can be significantly improved by inhibiting Zbp1- PANoptosome-mediated PANoptosis.

Redox signaling in the pancreas in health and disease

This review addresses oxidative stress and redox signaling in the pancreas under healthy physiological conditions as well as in acute pancreatitis, chronic pancreatitis, pancreatic cancer, and diabetes. Physiological redox homeodynamics is maintained mainly by NRF2/KEAP1, NF-κB, protein tyrosine phosphatases, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α), and normal autophagy. Depletion of reduced glutathione (GSH) in the pancreas is a hallmark of acute pancreatitis and is initially accompanied by disulfide stress, which is characterized by protein cysteinylation without increased glutathione oxidation. A cross talk between oxidative stress, MAPKs, and NF-κB amplifies the inflammatory cascade, with PP2A and PGC1α as key redox regulatory nodes. In acute pancreatitis, nitration of cystathionine-β synthase causes blockade of the transsulfuration pathway leading to increased homocysteine levels, whereas p53 triggers necroptosis in the pancreas through downregulation of sulfiredoxin, PGC1α, and peroxiredoxin 3. Chronic pancreatitis exhibits oxidative distress mediated by NADPH oxidase 1 and/or CYP2E1, which promotes cell death, fibrosis, and inflammation. Oxidative stress cooperates with mutant KRAS to initiate and promote pancreatic adenocarcinoma. Mutant KRAS increases mitochondrial reactive oxygen species (ROS), which trigger acinar-to-ductal metaplasia and progression to pancreatic intraepithelial neoplasia (PanIN). ROS are maintained at a sufficient level to promote cell proliferation, while avoiding cell death or senescence through formation of NADPH and GSH and activation of NRF2, HIF-1/2α, and CREB. Redox signaling also plays a fundamental role in differentiation, proliferation, and insulin secretion of β-cells. However, ROS overproduction promotes β-cell dysfunction and apoptosis in type 1 and type 2 diabetes.

4-octyl Itaconate Attenuates Acute Pancreatitis and Associated Lung Injury by Suppressing Ferroptosis in Mice

Acute pancreatitis (AP) is a common gastrointestinal emergency requiring hospitalization. In recent years, several studies have demonstrated a role for 4-octyl itaconate (4-OI) in anti-inflammatory and oxidative stress injury. However, the potential effects of 4-OI in AP have not been investigated. Caerulein and LPS were used to induce experimental AP models in mice and AR42J cells and then studied by histopathology, biochemical, and molecular analysis. Ferroptosis inhibitor ferrostatin-1 effectively improves pancreatic injury and reduces lipid peroxidation products in experimental AP mice. 4-OI treatment significantly alleviated pancreatic and AP-associated lung injury and inflammation in experimental AP mice by inhibiting ferroptosis. The ferroptosis activator Erastin blocked the protective effect of 4-OI against pancreatic injury in AP, validating that 4-OI alleviates pancreatitis injury through ferroptosis. In vitro experiments further confirmed that 4-OI treatment ameliorated AP-induced pancreatic injury by inhibiting ferroptosis. Our study, for the first time, found that 4-OI ameliorates AP and AP-related lung injury by inhibiting ferroptosis in experimental AP mice, providing a new therapeutic target for alleviating AP.

An adenoviral vector encoding an inflammation-inducible antagonist, HMGB1 Box A, as a novel therapeutic approach to inflammatory diseases

Influenza, as well as other respiratory viruses, can trigger local and systemic inflammation resulting in an overall "cytokine storm" that produces serious outcomes such as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). We hypothesized that gene therapy platforms could be useful in these cases if the production of an anti-inflammatory protein reflects the intensity and duration of the inflammatory condition. The recombinant protein would be produced and released only in the presence of the inciting stimulus, avoiding immunosuppression or other unwanted side effects that may occur when treating infectious diseases with anti-inflammatory drugs. To test this hypothesis, we developed AdV.C3-Tat/HIV-Box A, an inflammation-inducible cassette that remains innocuous in the absence of inflammation but releases HMGB1 Box A, an antagonist of high mobility group box 1 (HMGB1), in response to inflammatory stimuli such as lipopolysaccharide (LPS) or influenza virus infection. We report here that this novel inflammation-inducible HMGB1 Box A construct in a non-replicative adenovirus (AdV) vector mitigates lung and systemic inflammation therapeutically in response to influenza infection. We anticipate that this strategy will apply to the treatment of multiple diseases in which HMGB1-mediated signaling is a central driver of inflammation.IMPORTANCEMany inflammatory diseases are mediated by the action of a host-derived protein, HMGB1, on Toll-like receptor 4 (TLR4) to elicit an inflammatory response. We have engineered a non-replicative AdV vector that produces HMGB1 Box A, an antagonist of HMGB1-induced inflammation, under the control of an endogenous complement component C3 (C3) promoter sequence, that is inducible by LPS and influenza in vitro and ex vivo in macrophages (Mϕ) and protects mice and cotton rats therapeutically against infection with mouse-adapted and human non-adapted influenza strains, respectively, in vivo. We anticipate that this novel strategy will apply to the treatment of multiple infectious and non-infectious diseases in which HMGB1-mediated TLR4 signaling is a central driver of inflammation.

Macrophage-mimicking nanotherapy for attenuation of acute pancreatitis

Acute pancreatitis (AP) is a highly fatal pancreatic inflammation. In recent years, synthetic nanoparticles have been extensively developed as drug carriers to address the challenges of systemic adverse reactions and lack of specificity in drug delivery. However, systemically administered nanoparticle therapy is rapidly cleared from circulation by the mononuclear phagocyte system (MPS), leading to suboptimal drug concentrations in inflamed tissues and suboptimal pharmacokinetics. To address this challenge, we herein demonstrate a surface masking strategy that involves coating the surface of selenylated Poria cocos polysaccharide nanoparticles with a layer of macrophage plasma membrane to circumvent MPS sequestration, thereby enhancing the therapeutic efficacy of selenylated Poria cocos polysaccharide nanoparticles. Nanoparticles encapsulated with macrophage membranes can simulate the active homing efficacy of macrophages to inflamed lesions during AP, resulting in excessive infiltration of macrophages in pancreatic inflammation sites and prolonged tissue retention time. This technique converts non-adhesive lipid nanoparticles into bioadhesive nanoparticles, increasing local tissue accumulation under inflammatory conditions, including the pancreas and vulnerable lungs. The mechanism is related to targeting pro-inflammatory macrophages. In murine models of mild and severe AP, intravenous treatment with macrophage-mimicking nanoparticles effectively reduces systemic inflammation level and diminishes the recruitment of macrophages and neutrophils. Mechanistic studies elucidate that macrophage membrane-biomimetic selenylated Poria cocos polysaccharide nanoparticles primarily mitigate pancreatic inflammation by inhibiting the AKT/mTOR pathway to reverse autophagic flux impairment. This allows us to envision that the developed biomimetic nanotherapy approach could potentially serve as a novel strategy for pancreatic drug therapy.

Lysine acetylation and its role in the pathophysiology of acute pancreatitis

Acute pancreatitis (AP) represents a severe inflammatory condition of the exocrine pancreas, precipitating systemic organ dysfunction and potential failure. The global prevalence of acute pancreatitis is on an ascending trajectory. The condition carries a significant mortality rate during acute episodes. This underscores the imperative to elucidate the etiopathogenic pathways of acute pancreatitis, enhance comprehension of the disease's intricacies, and identify precise molecular targets coupled with efficacious therapeutic interventions. The pathobiology of acute pancreatitis encompasses not only the ectopic activation of trypsinogen but also extends to disturbances in calcium homeostasis, mitochondrial impairment, autophagic disruption, and endoplasmic reticulum stress responses. Notably, the realm of epigenetic regulation has garnered extensive attention and rigorous investigation in acute pancreatitis research over recent years. One of these modifications, lysine acetylation, is a reversible post-translational modification of proteins that affects enzyme activity, DNA binding, and protein stability by changing the charge on lysine residues and altering protein structure. Numerous studies have revealed the importance of acetylation modification in acute pancreatitis, and that it is a favorable target for the design of new drugs for this disease. This review centers on lysine acetylation, examining the strides made in acute pancreatitis research with a focus on the contributory role of acetylomic alterations in the pathophysiological landscape of acute pancreatitis, thereby aiming to delineate novel therapeutic targets and advance the development of more efficacious treatment modalities.

Overview of the cellular and immune mechanisms involved in acute pancreatitis: In search of new prognosis biomarkers

Acute pancreatitis (AP) is an acute-onset gastrointestinal disease characterized by a significant inflammation of the pancreas. Most of the time, AP does not leave substantial changes in the pancreas after the resolution of the symptoms but the severe forms are associated with local or systemic complications. The pathogenesis of AP has long been investigated and, lately, the importance of intracellular mechanisms and the immune system has been described. The initial modifications in AP take place in the acinar cell. There are multiple mechanisms by which cellular homeostasis is impaired, one of the most important being calcium overload. Necrotic pancreatic cells initiate the inflammatory response by secreting inflammatory mediators and attracting immune cells. From this point on, the inflammation is sustained by the involvement of innate and adaptive immune systems. Multiple studies have demonstrated the importance of the first 48 h for identifying patients at risk for developing severe forms. For this reason, there is a need to find new, easy-to-use and reliable markers for accurate predictions of these forms. This review provides an overview of the main pathogenetic mechanisms involved in AP development and the most promising biomarkers for severity stratification.

CIP2A inhibitors TD52 and Ethoxysanguinarine promote macrophage autophagy and alleviates acute pancreatitis by modulating the AKT-mTOR pathway

BACKGROUND

Acute pancreatitis (AP) is a prevalent and serious condition within the digestive system, with approximately 20 % to 30 % of cases advancing to severe acute pancreatitis (SAP). During the initial phases of SAP, macrophages are activated in response to the substantial amounts of acinar cell contents and damage-associated molecular patterns (DAMPs) resulting from acinar cell destruction. Subsequently, activated macrophages release a significant array of pro-inflammatory factors that exacerbate the progression of SAP. Cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncogenic protein that is intimately linked to immune regulation. While the role of CIP2A in T-cell-mediated specific immune responses has been reported, its function and mechanism in macrophages, a component of non-specific immunity, have not been widely studied. This research fills this knowledge gap by elucidating the critical role of CIP2A in regulating macrophage autophagy and inflammation. This finding not only expands our understanding of CIP2A in immune modulation but also provides a new scientific basis and potential application prospects for targeting CIP2A in the treatment of AP.

METHODS

We established AP using a combination of palmitoleic acid with anhydrous ethanol or using caerulein alone. The effects of TD52 and Ethoxysanguinarine (Etho) on SAP were evaluated through serological, histopathological, and tissue inflammation observations. The effect of TD52 on macrophage activation in vitro was examined using primary macrophages (PMs) and RAW264.7 cells.

RESULTS

We found that TD52 and Etho inhibit CIP2A expression while reducing the levels of serum amylase, lipase, and inflammatory cytokines, thereby alleviating the pathological symptoms of SAP. Additionally, TD52 could reduce the infiltration of macrophages into pancreatic tissue. Therefore, we established a model of macrophage inflammatory response mimicking the pathophysiological process of AP and detected changes in inflammation, apoptosis, and autophagy through pre-treatment of macrophages with TD52. The results show that inhibiting CIP2A expression decreases the release of inflammatory cytokines and reduces apoptosis in macrophages. Further exploration revealed that TD52 promoted macrophage autophagy regulation and inhibited the AKT-mTOR pathway to modulate macrophage activation.

CONCLUSION

In summary, our findings indicate that TD52 and Etho can alleviate the severity of SAP. TD52 can block the AKT-mTOR pathway to promote macrophage autophagy, thereby improving SAP. Thus, CIP2A may serve as one of the molecular targets in SAP, highlighting its potential as a therapeutic option.

Pancreatic Morphology, Immunology, and the Pathogenesis of Acute Pancreatitis

Acute pancreatitis is a complex inflammatory disorder with significant morbidity and mortality. This review aims to integrate the current knowledge of pancreatic morphology and immunology with the pathogenesis of acute pancreatitis, providing a comprehensive understanding of this critical condition. We conducted an extensive literature review, synthesizing data from recent studies and authoritative sources on pancreatic anatomy, histology, immunology, and the pathophysiology of acute pancreatitis. We also incorporated epidemiological data, clinical features, diagnostic criteria, and prognostic factors. The pancreas exhibits a complex morphology with intricate interactions between its exocrine and endocrine components. Its unique immunological landscape plays a crucial role in maintaining homeostasis and orchestrating responses to pathological conditions. In acute pancreatitis, the disruption of intracellular calcium signaling leads to premature enzyme activation, triggering a cascade of events including mitochondrial dysfunction, ATP depletion, and the release of proinflammatory mediators. This process can escalate from localized inflammation to systemic complications. The interplay between pancreatic morphology, immune responses, and pathophysiological mechanisms contributes to the varied clinical presentations and outcomes observed in acute pancreatitis. Understanding the intricate relationships between pancreatic morphology, immunology, and the pathogenesis of acute pancreatitis is crucial for developing more effective diagnostic and therapeutic strategies. This integrated approach provides new insights into the complex nature of acute pancreatitis and may guide future research directions in pancreatic disorders.

Nanomedicine regulating PSC-mediated intercellular crosstalk: Mechanisms and therapeutic strategies

Pancreatic fibrosis (PF) is primarily distinguished by the stimulation of pancreatic stellate cells (PSCs) and excessive extracellular matrix deposition, which is the main barrier impeding drug delivery and distribution. Recently, nanomedicine, with efficient, targeted, and controllable drug release characteristics, has demonstrated enormous advantages in the regression of pancreas fibrotic diseases. Notably, paracrine signals from parenchymal and immune cells such as pancreatic acinar cells, islet cells, pancreatic cancer cells, and immune cells can directly or indirectly modulate PSC differentiation and activation. The intercellular crosstalk between PSCs and these cells has been a critical event involved in fibrogenesis. However, the connections between PSCs and other pancreatic cells during the progression of diseases have yet to be discussed. Herein, we summarize intercellular crosstalk in the activation of PSCs and its contribution to the development of common pancreatic diseases, including pancreatitis, pancreatic cancer, and diabetes. Then, we also examine the latest treatment strategies of nanomedicine and potential targets for PSCs crosstalk in fibrosis, thereby offering innovative insights for the design of antifibrotic nanomedicine. Ultimately, the enhanced understanding of PF will facilitate the development of more precise intervention strategies and foster individually tailored therapeutic approaches for pancreatic diseases.

GV-971 prevents severe acute pancreatitis by remodeling the microbiota-metabolic-immune axis

Despite recent advances, severe acute pancreatitis (SAP) remains a lethal inflammation with limited treatment options. Here, we provide compelling evidence of GV-971 (sodium oligomannate), an anti-Alzheimer's medication, as being a protective agent in various male mouse SAP models. Microbiome sequencing, along with intestinal microbiota transplantation and mass cytometry technology, unveil that GV-971 reshapes the gut microbiota, increasing Faecalibacterium populations and modulating both peripheral and intestinal immune systems. A metabolomics analysis of cecal contents from GV-971-treated SAP mice further identifies short-chain fatty acids, including propionate and butyrate, as key metabolites in inhibiting macrophage M1 polarization and subsequent lethal inflammation by blocking the MAPK pathway. These findings suggest GV-971 as a promising therapeutic for SAP by targeting the microbiota metabolic immune axis.

The TRIM28/miR133a/CD47 axis acts as a potential therapeutic target in pancreatic necrosis by impairing efferocytosis

Efferocytosis, the clearance of apoptotic cells by macrophages, plays a crucial role in inflammatory responses and effectively prevents secondary necrosis. However, the mechanisms underlying efferocytosis in acute pancreatitis (AP) remain unclear. In this study, we demonstrated the presence of efferocytosis in injured human and mouse pancreatic tissues. We also observed significant upregulation of CD47, an efferocytosis-related the "do not eat me" molecule in injured acinar cells. Subsequently, we used CRISPR-Cas9 gene editing, anti-adeno-associated virus (AAV) gene modification, and anti-CD47 antibody to investigate the potential therapeutic role of AP. CD47 expression was negatively regulated by upstream miR133a, which is controlled by the transcription factor TRIM28. To further investigate the regulation of efferocytosis and reduction of pancreatic necrosis in AP, we used miR-133a-agomir and pancreas-specific AAV-shTRIM28 to modulate CD47 expression. Our findings confirmed that CD47-mediated efferocytosis is critical for preventing pancreatic necrosis and suggest that targeting the TRIM28-miR133a-CD47 axis is clinically relevant for the treatment of AP.

Rhei Radix et Rhizoma and its anthraquinone derivatives: Potential candidates for pancreatitis treatment

BACKGROUND

Pancreatitis is a common exocrine inflammatory disease of the pancreas and lacks specific medication currently. Rhei Radix et Rhizoma (RR) and its anthraquinone derivatives (AQs) have been successively reported for their pharmacological effects and molecular mechanisms in experimental and clinical pancreatitis. However, an overview of the anti-pancreatitis potential of RR and its AQs is limited.

PURPOSE

To summarize and analyze the pharmacological effects of RR and its AQs on pancreatitis and the underlying mechanisms, and discuss their drug-like properties and future perspectives.

METHODS

The articles related to RR and its AQs were collected from the Chinese National Knowledge Infrastructure, Wanfang data, PubMed, and the Web of Science using relevant keywords from the study's inception until April first, 2024. Studies involving RR or its AQs in cell or animal pancreatitis models as well as structure-activity relationship, pharmacokinetics, toxicology, and clinical trials were included.

RESULTS

Most experimental studies are based on severe acute pancreatitis rat models and a few on chronic pancreatitis. Several bioactive anthraquinone derivatives of Rhei Radix et Rhizoma (RRAQs) exert local protective effects on the pancreas by maintaining pancreatic acinar cell homeostasis, inhibiting inflammatory signaling, and anti-fibrosis, and they improve systemic organ function by alleviating intestinal and lung injury. Pharmacokinetic and toxicity studies have revealed the low bioavailability and wide distribution of RRAQs, as well as hepatotoxicity and nephrotoxicity. However, there is insufficient research on the clinical application of RRAQs in pancreatitis. Furthermore, we propose effective strategies for subsequent improvement in terms of balancing effectiveness and safety.

CONCLUSION

RRAQs can be developed as either candidate drugs or novel lead structures for pancreatitis treatment. The comprehensive review of RR and its AQs provides references for optimizing drugs, developing therapies, and conducting future studies on pancreatitis.

The role of mitochondrial damage-associated molecular patterns in acute pancreatitis

Acute pancreatitis (AP) is one of the most common gastrointestinal tract diseases with significant morbidity and mortality. Current treatments remain unspecific and supportive due to the severity and clinical course of AP, which can fluctuate rapidly and unpredictably. Mitochondria, cellular power plant to produce energy, are involved in a variety of physiological or pathological activities in human body. There is a growing evidence indicating that mitochondria damage-associated molecular patterns (mtDAMPs) play an important role in pathogenesis and progression of AP. With the pro-inflammatory properties, released mtDAMPs may damage pancreatic cells by binding with receptors, activating downstream molecules and releasing inflammatory factors. This review focuses on the possible interaction between AP and mtDAMPs, which include cytochrome c (Cyt c), mitochondrial transcription factor A (TFAM), mitochondrial DNA (mtDNA), cardiolipin (CL), adenosine triphosphate (ATP) and succinate, with focus on experimental research and potential therapeutic targets in clinical practice. Preventing or diminishing the release of mtDAMPs or targeting the mtDAMPs receptors might have a role in AP progression.

MZB1 regulates cellular proliferation, mitochondrial dysfunction, and inflammation and targets the PI3K-Akt signaling pathway in acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) is a pathological condition characterized by the premature release and activation of trypsinogens and other enzyme precursors. In severe cases, the mortality rates are in the range of 20-30% and may even be as high as 50%. Though various prophylaxes are available for AP, the mechanism of its progression is unclear. Marginal zone B and B-1 cell-specific protein 1 (MZB1) is found in the endoplasmic reticulum (ER) where it is expressed exclusively in the B cells there. MZB1 promotes proliferation, inhibits apoptosis, invasion, and inflammation, and mitigates mitochondrial damage in cells. However, the importance of MZB1 in AP has not yet been determined.

METHODS

Differentially expressed genes (DEGs) between healthy pancreatic cells and those affected by AP were identified using datasets from Gene Expression Omnibus (GEO) datasets. Relative differences in MZB1 expression between normal and diseased tissues and cells were validated in vivo using a rat AP model induced with 4% (w/v) sodium taurocholate and in vitro using the AR42J rat pancreatic cell line exposed to caerulein (CAE). Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2`-deoxyuridine (EdU) assays were performed to detect and compare normal and pathological cell proliferation. Flow cytometry was employed to assess and compare cellular apoptosis. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot (WB) were applied to evaluate the apoptotic factors Bax and Bcl. The inflammatory factors interleukin (IL)-6 and IL-1β were quantified using Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR techniques. Mitochondrial function was evaluated using assays for reactive oxygen species (ROS) and tetramethylrhodamine methyl ester (TMRM). WB and qRT-PCR were utilized to measure the expression levels of the PI3K-Akt signaling pathway, followed by a rescue experiment involving the inhibitor of wortmannin.

RESULTS

MZB1 was upregulated in the AP cases screened from the GEO datasets, the rat AP model, and the AR42J cells exposed to CAE. Overexpression of MZB1 enhanced the growth and supressed the cell death of AR42J cells while also activating the PI3K-Akt signaling pathway. MZB1 knockdown led to mitochondrial dysfunction and exacerbated inflammation. The rescue experiment demonstrated that MZB1 enhanced proliferation and inhibited apoptosis, mitochondrial dysfunction, and inflammation in pancreatic cells through the PI3K-Akt pathway.

CONCLUSIONS

AP cells and tissues exhibited markedly elevated levels of MZB1 expression compared to their healthy counterparts. MZB1 overexpression promoted proliferation and supressed apoptosis, mitochondrial dysfunction, and inflammation in pancreatic cells through the positive regulation of the PI3K-Akt signaling pathway.

Molecular mechanisms of pain in acute pancreatitis: recent basic research advances and therapeutic implications

Although severe abdominal pain is the main symptom of acute pancreatitis, its mechanisms are poorly understood. An emerging body of literature evidence indicates that neurogenic inflammation might play a major role in modulating the perception of pain from the pancreas. Neurogenic inflammation is the result of a crosstalk between injured pancreatic tissue and activated neurons, which leads to an auto-amplification loop between inflammation and pain during the progression of acute pancreatitis. In this review, we summarize recent findings on the role of neuropeptides, ion channels, and the endocannabinoid system in acute pancreatitis-related pain. We also highlight potential therapeutic strategies that could be applied for managing severe pain in this disease.

Mitochondrial DNA Copy Number, a Damage-Associated Molecular Pattern Molecule, Can Predict Pancreatic Necrosis and Is Correlated with the Severity of Acute Pancreatitis

BACKGROUND

Mitochondrial DNA (mtDNA) is a damage-associated molecular pattern molecule that can trigger an immune-inflammatory response during pancreatic necrosis (PN).

AIM

To evaluate the role of mtDNA in the detection of PN and severe acute pancreatitis (SAP).

METHODS

The present study included 40 AP patients and 30 controls. AP patients were grouped into mild AP (MAP, n = 15), moderately severe AP (MSAP, n = 17), and SAP (n = 8). Also, the SAP + MSAP group, n = 25, was compared to MAP. AP patients were divided into NAP (n = 7) and non-necrotizing AP (n = 33). The mtDNA copy number, IL-6, and STAT3 expression levels were measured using quantitative real-time PCR.

RESULTS

The mtDNA, IL-6, and STAT3 levels were significantly higher in AP patients than in controls and in the SAP + MSAP than in the MAP. However, the SAP had non-significantly higher levels of mtDNA, STAT3, and IL-6 levels than the MSAP and statistically significant mtDNA, STAT3, and IL-6 when compared to the MAP. mtDNA, IL-6, and STAT3 showed significantly higher levels in NAP compared with non-necrotizing AP. mtDNA was positively correlated with STAT3, IL-6, CRP, APACHE, and CT severity index (CTSI) and negatively correlated with albumin. In the receiver operating curve (ROC), mtDNA was the most significant independent predictor of PN and MAP vs. SAP + MSAP. IL-6 and mtDNA + CRP had higher diagnostic abilities for SIRS and high CTSI.

CONCLUSIONS

mtDNA could enhance the prediction of NAP; however, its diagnostic ability of SAP needs further study.

An in-Depth Exploration of the Genetic Interaction Network Between Ferroptosis and Acute Pancreatitis

Background

Ferroptosis plays an important role in a variety of disease processes and is equally important in pancreatic diseases. However, the role of ferroptosis-related genes (FRGs) in acute pancreatitis (AP) remains unknown, and their specific potential mechanisms still need to be explored extensively.

Methods

AP-related gene microarray data were obtained from the GEO database, while FRGs were obtained from the ferroptosis database (FerrDb). Differentially expressed genes (DEGs) were screened by the "limma" package, and GSEA was performed. The corresponding ferroptosis-related differentially expressed genes (FRDEGs) were screened, and GO and KEGG pathway analyses were performed. A PPI network was constructed to identify hub FRDEGs by CytoHubba, MCODE and CTD scores. Transcription factors and miRNAs predicted using the NetworkAnalyst database were used to establish the regulatory network. Immune cell infiltration analysis was performed by the R package "ssGSEA" algorithm. The hub genes were validated by transcriptome sequencing of AP model mice and immunohistochemistry in rats and mice.

Results

A total of 82 FRDEGs were screened, and these genes were mainly associated with ferroptosis, hypoxic response, autophagy, mitophagy and immune inflammation. However, we also found that these genes are also jointly involved in other cell death modalities, such as apoptosis and necroptosis. Further analysis obtained 7 hub genes from 82 genes, and single-sample gene set enrichment analysis (ssGSEA) showed that the hub genes are closely associated with the infiltration of specific immune cells and the activation of immune pathways.

Conclusion

This study reveals the complex functions and important roles of ferroptosis-related genes in AP and provides gene targets for further studies of AP.

Kynurenine monooxygenase regulates inflammation during critical illness and recovery in experimental acute pancreatitis

Kynurenine monooxygenase (KMO) blockade protects against multiple organ failure caused by acute pancreatitis (AP), but the link between KMO and systemic inflammation has eluded discovery until now. Here, we show that the KMO product 3-hydroxykynurenine primes innate immune signaling to exacerbate systemic inflammation during experimental AP. We find a tissue-specific role for KMO, where mice lacking Kmo solely in hepatocytes have elevated plasma 3-hydroxykynurenine levels that prime inflammatory gene transcription. 3-Hydroxykynurenine synergizes with interleukin-1β to cause cellular apoptosis. Critically, mice with elevated 3-hydroxykynurenine succumb fatally earlier and more readily to experimental AP. Therapeutically, blockade with the highly selective KMO inhibitor GSK898 rescues the phenotype, reducing 3-hydroxykynurenine and protecting against critical illness and death. Together, our findings establish KMO and 3-hydroxykynurenine as regulators of inflammation and the innate immune response to sterile inflammation. During critical illness, excess morbidity and death from multiple organ failure can be rescued by systemic KMO blockade.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

New insights into regulatory cell death and acute pancreatitis

Acute pancreatitis (AP) may be associated with both local and systemic complications. Although it is usually self-limiting, up to 20% of patients develop severe acute pancreatitis (SAP), which leads to systemic inflammatory response syndrome (SIRS) and multiorgan dysfunction and failure affecting the lung, kidney, liver and heart. Patients who survive the condition frequently develop devastating long-term consequences such as diabetes mellitus, exocrine pancreatic insufficiency, chronic pancreatitis (CP) and poor quality of life. A lack of specific targeted treatments is the main reason for high mortality and morbidity, indicating that more research on the pathogenesis of AP is needed. In the past decade, substantial advancements have been made in our understanding of the pathophysiological mechanisms of AP, including mechanisms of calcium-mediated acinar cell injury and death, the cytoprotective role of the unfolded protein response (UPR) and autophagy in preventing sustained endoplasmic reticulum stress (ERs); however, the mechanism of parenchymal cell death is relatively poorly understood. This paper reviews the research progress of the regulatory cell death (RCD) mode in the pathogenesis of AP, providing some new insights and regulatory targets for the pathogenesis and treatment of AP, facilitating better targeted drug development.

Acute Pancreatitis: Current Clinical Approaches, Molecular Pathophysiology, and Potential Therapeutics

OBJECTIVE

Severe acute pancreatitis (SAP), pancreatic inflammation leading to multiorgan failure, is associated with high morbidity and mortality. There is a critical need to identify novel therapeutic strategies to improve clinical outcomes for SAP patients.

MATERIALS AND METHODS

A comprehensive literature review was performed to identify current clinical strategies, known molecular pathophysiology, and potential therapeutic targets for SAP.

RESULTS

Current clinical approaches focus on determining which patients will likely develop SAP. However, therapeutic options are limited to supportive care and fluid resuscitation. The application of a novel 5-cytokine panel accurately predicting disease outcomes in SAP suggests that molecular approaches will improve impact of future clinical trials in AP.

CONCLUSIONS

Inflammatory outcomes in acute pancreatitis are driven by several unique molecular signals, which compound to promote both local and systemic inflammation. The identification of master cytokine regulators is critical to developing therapeutics, which reduce inflammation through several mechanisms.

Extracellular SQSTM1 exacerbates acute pancreatitis by activating autophagy-dependent ferroptosis

ABBREVIATIONS

5-HETE, 5-hydroxyeicosatetraenoic acid; ACSL4, acyl-CoA synthetase long chain family member 4; AP, acute pancreatitis; ATG, autophagy related; AGER, advanced glycosylation end-product specific receptor; DAMPs, danger/damage-associated molecular patterns; FTH1, ferritin heavy chain 1; GPX4, glutathione peroxidase 4; IL, interleukin; INSR, insulin receptor; MAP1LC3B, microtubule associated protein 1 light chain 3 beta; MDA, malondialdehyde; MPO, myeloperoxidase; PRRs, pattern recognition receptors; PUFA, polyunsaturated fatty acid; RNAi, RNA interference; SQSTM1, sequestosome 1; TNF, tumor necrosis factor; TLR, toll like receptor.

Acinar cells and the development of pancreatic fibrosis

Pancreatic fibrosis is caused by excessive deposition of extracellular matrixes of collagen and fibronectin in the pancreatic tissue as a result of repeated injury often seen in patients with chronic pancreatic diseases. The most common causative conditions include inborn errors of metabolism, chemical toxicity and autoimmune disorders. Its pathophysiology is highly complex, including acinar cell injury, acinar stress response, duct dysfunction, pancreatic stellate cell activation, and persistent inflammatory response. However, the specific mechanism remains to be fully clarified. Although the current therapeutic strategies targeting pancreatic stellate cells show good efficacy in cell culture and animal models, they are not satisfactory in the clinic. Without effective intervention, pancreatic fibrosis can promote the transformation from pancreatitis to pancreatic cancer, one of the most lethal malignancies. In the normal pancreas, the acinar component accounts for 82% of the exocrine tissue. Abnormal acinar cells may activate pancreatic stellate cells directly as cellular source of fibrosis or indirectly via releasing various substances and initiate pancreatic fibrosis. A comprehensive understanding of the role of acinar cells in pancreatic fibrosis is critical for designing effective intervention strategies. In this review, we focus on the role of and mechanisms underlying pancreatic acinar injury in pancreatic fibrosis and their potential clinical significance.

The Emerging Roles of the Adaptive Immune Response in Acute Pancreatitis

Acute pancreatitis (AP) is an abrupt, variable inflammatory condition of the pancreas, potentially escalating to severe systemic inflammation, rampant pancreatic necrosis, and multi-organ failure. Its complex pathogenesis involves an intricate immune response, with different T cell subsets (Th1, Th2, Th9, Th17, Th22, TFH, Treg, and CD8+ T cells) and B cells playing pivotal roles. Early T cell activation initiates the AP development, triggering cytokines associated with the Th1 response, which stimulate macrophages and neutrophils. Other T cell phenotypes contribute to AP's pathogenesis, and the balance between pro-inflammatory and anti-inflammatory cytokines influences its progression. Regulatory T and B cells are crucial for moderating the inflammatory response and promoting immune tolerance. B cells further contribute through antibody production, antigen presentation, and cytokine secretion. Understanding these immune cells' roles in AP could aid in developing new immunotherapies to enhance patient outcomes. However, further research is required to define these cells' precise roles in AP and their potential as therapeutic targets.

Mmu_circ_0000037 inhibits the progression of acute pancreatitis by miR-92a-3p/Pias1 axis

BACKGROUND

Acute pancreatitis (AP) is an inflammatory disease with high mortality. Previous study has suggested that circular RNAs are dysregulated and involved in the regulation of inflammatory responses in AP. This study aimed to investigate the function and regulatory mechanism underlying mmu_circ_0000037 in caerulein-induced AP cellular model.

METHODS

Caerulein-treated MPC-83 cells were used as an in vitro cellular model for AP. The expression levels of mmu_circ_0000037, microRNA (miR)-92a-3p, and protein inhibitor of activated STAT1 (Pias1) were detected by quantitative real-time polymerase chain reaction. Cell viability, amylase activity, apoptosis, and inflammatory response were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Amylase Assay Kit, flow cytometry, and enzyme-linked immunosorbent assays. The protein level was quantified by western blot analysis. The target interaction between miR-92a-3p and mmu_circ_0000037 or Pias1 were predicted by StarbaseV3.0 and validated by dual-luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

Mmu_circ_0000037 and Pias1 levels were decreased, whereas miR-92a-3p expression was elevated in caerulein-induced MPC-83 cells. Overexpression of mmu_circ_0000037 protected MPC-83 cells from caerulein-induced the decrease of cell viability, as well as the promotion of amylase activity, apoptosis and inflammation. MiR-92a-3p was targeted by mmu_circ_0000037, and miR-92a-3p overexpression rescued the effect of mmu_circ_0000037 on caerulein-induced MPC-83 cell injury. Pias1 was confirmed as a target of miR-92a-3p and mmu_circ_0000037 regulated the expression of Pias1 by sponging miR-92a-3p.

CONCLUSION

Mmu_circ_0000037 relieves caerulein-induced inflammatory injury in MPC-83 cells by targeting miR-92a-3p/Pias1 axis, providing a theoretical basis for the treatment of AP.

Role of Pyroptosis, a Pro-inflammatory Programmed Cell Death, in Epilepsy

Epilepsy is one of the most common serious brain diseases worldwide. Programmed cell death (PCD), a cellular self-destruction phenomenon, has been greatly documented in neurodegenerative diseases. Pyroptosis is a well-known pro-inflammatory PCD, and its involvement in epilepsy has been reported in animal models of epilepsy and also epileptic patients. Canonical (caspase-1-dependent) and non-canonical (caspase-1-independent) pathways are two main mechanisms implicated in pyroptotic cell death. Mouse caspase-11 or human analogues caspase-4/5 induce the non-canonical pathway. In both pathways, membrane gasdermin (GSDMD) pores contribute to pro-inflammatory cytokine release and lead to membrane destabilization and cell lysis. IL-1β and IL-18 are pro-inflammatory cytokines that are released following pyroptotic PCD. Brain inflammation increases excitability in the nervous system, promotes seizure activity, and is probably associated with the molecular and synaptic changes involved in epileptogenesis. Pro-inflammatory cytokines affect the glutamate and GABA neurotransmitter release as well as their receptors, thereby resulting in seizure activity. This review is intended to provide an overview of the current published works on pyroptotic cell death in epilepsy. The mechanisms by which pro-inflammatory cytokines, including IL-1β and IL-18 can promote epileptic discharges were also collected. According to this survey, since the involvement of pyroptosis in the development of epilepsy has been established, pyroptosis-targeted therapies may represent a novel anti-epileptogenic strategy.

The role of the circadian rhythms in critical illness with a focus on acute pancreatitis

Circadian rhythms are responsible for governing various physiological processes, including hormone secretion, immune responses, metabolism, and the sleep/wake cycle. In critical illnesses such as acute pancreatitis (AP), circadian rhythms can become dysregulated due to disease. Evidence suggests that time of onset of disease, coupled with peripheral inflammation brought about by AP will impact on the circadian rhythms generated in the central pacemaker and peripheral tissues. Cells of the innate and adaptive immune system are governed by circadian rhythms and the diurnal pattern of expression can be disrupted during disease. Peak circadian immune cell release and gene expression can coincide with AP onset, that may increase pancreatic injury, tissue damage and the potential for systemic inflammation and multiple organ failure to develop. Here, we provide an overview of the role of circadian rhythms in AP and the underpinning inflammatory mechanisms to contextualise ongoing research into the chronobiology and chronotherapeutics of AP.

Salidroside ameliorates severe acute pancreatitis-induced cell injury and pyroptosis by inactivating Akt/NF-κB and caspase-3/GSDME pathways

Our previous studies showed that Salidroside (Sal), a glucoside of the phenylpropanoid tyrosol isolated from Rhodiola rosea L, alleviated severe acute pancreatitis (SAP) by inhibiting inflammation. However, the detailed mechanism remains unclear. Recent evidence has indicated a critical role of Sal in ameliorating inflammatory disorders by regulating pyroptosis. The present study aimed to explore the involvement of Sal and pyroptosis in the pathogenesis of SAP and investigate the potential mechanism. The effects of Sal on pyroptosis were first evaluated using SAP rat and cell model. Our results revealed that Sal treatment significantly decreased SAP-induced pancreatic cell damage and pyroptosis in vivo and in vitro, as well as reduced the release of lactate dehydrogenase (LDH), IL-1β and IL-18. Search Tool for Interacting Chemicals (STITCH) online tool identified 4 genes (CASP3, AKT1, HIF1A and IL10) as candidate targets of Sal in both rattus norvegicus and homo sapiens. Western blot and immunohistochemistry staining validated that Sal treatment decreased the phosphorylation levels of Akt and NF-κB p65, as well as cleaved caspase-3 and N-terminal fragments of GSDME (GSDME-N), suggesting that Sal might suppress pyroptosis through inactivating Akt/NF-κB and Caspase-3/GSDME pathways. Furthermore, overexpression of AKT1 or CASP3 could partially reverse the inhibitory effects of Sal on cell injury and pyroptosis, while downregulation of AKT1 or CASP3 promoted the inhibitory effects of Sal. Taken together, our data indicate that Sal suppresses SAP-induced pyroptosis through inactivating Akt/NF-κB and Caspase-3/GSDME pathways.

MARCH9 Mediates NOX2 Ubiquitination to Alleviate NLRP3 Inflammasome-Dependent Pancreatic Cell Pyroptosis in Acute Pancreatitis

OBJECTIVE

The pathogenesis of acute pancreatitis mainly involves NLRP3 inflammasome-mediated pancreatic cell injury, although regulators of this inflammasome machinery are still not fully identified. Membrane-associated RING-CH 9 (MARCH9) is a member of MARCH-type finger proteins, which regulates innate immunity through catalyzing polyubiquitination of critical immune factors. The aim of present research is to examine the function of MARCH9 in acute pancreatitis.

METHODS

Cerulein-induced acute pancreatitis was established on pancreatic cell line AR42J and rat model. Reactive oxygen species (ROS) accumulation and NLRP3 inflammasome-dependent cell pyroptosis in pancreas were examined by flow cytometry.

RESULTS

MARCH9 was downregulated by cerulein, but overexpressing MARCH9 could inhibit NLRP3 inflammasome activation and ROS accumulation, thus suppressing pancreatic cell pyroptosis and mitigating pancreatic injury. We further uncovered that the mechanism underlying such an effect of MARCH9 is through mediating the ubiquitination of NADPH oxidase-2, whose deficiency reduces cellular ROS accumulation and inflammasome formation.

CONCLUSIONS

Our results suggested that MARCH9 suppresses NLRP3 inflammasome-mediated pancreatic cell injury through mediating the ubiquitination and degradation of NADPH oxidase-2, which compromises ROS generation and NLRP3 inflammasomal activation.

Toll-Like Receptor 9 Signaling Pathway Contributes to Intestinal Mucosal Barrier Injury in Mice With Severe Acute Pancreatitis

OBJECTIVES

The purpose of this study was to investigate the role and mechanism of toll-like receptor 9 (TLR9) in intestinal mucosal barrier injury in mice with severe acute pancreatitis (SAP).

METHODS

The mice were randomly divided into 3 groups: control group, SAP group, and TLR9 antagonist-treated group. The expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, diamine oxidase, and endotoxin core antibodies were detected by enzyme-linked immunosorbent assay. The protein expression of zonula occluden-1 (ZO)-1, occludin, TLR9, myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), p-nuclear factor (NF)-κB p65, and NF-κB p65 were detected by Western blot. TdT-mediated dUTP nick-end labeling staining was used for detecting intestinal epithelial cell apoptosis.

RESULTS

The expression of TLR9 and its related pathway proteins MyD88, TRAF6, and p-NF-κB p65 in the intestinal tract of SAP mice were significantly increased compared with that of control mice. Inhibition of the TLR9 expression could reduce the level of serum proinflammatory cytokines, reduce the apoptosis of intestinal epithelial cells, improve intestinal permeability, and ultimately reduce the damage of intestinal mucosal barrier function in SAP.

CONCLUSIONS

Toll-like receptor 9/MyD88/TRAF6/NF-κB signaling pathway plays an important role in intestinal mucosal barrier injury of SAP.

MiR-325-3p Alleviates Acute Pancreatitis via Targeting RIPK3

BACKGROUND AND AIMS

Acute pancreatitis (AP) is an acute inflammatory disease that can lead to death. Mir-325-3p is strongly and abnormally expressed in many diseases, necessitating exploration of its function and mechanism in AP.

METHODS

Blood samples from AP patients and mice were analyzed. The expression levels of miR-325-3p in AP patients and mouse were detected. Whether miR-325-3p targets RIPK3 gene was predicted by TargetScan online database and dual luciferase reporter assay. In vitro experiments verified the effect of miR-325-3p overexpression on caerulein-induced MPC83 pancreatic acinar cancer cell line. In vivo experiments verified the effect of overexpression of miR-325-3p on the disease degree of pancreatic tissues in AP mice.

RESULTS

Analysis of blood samples from AP patients and experiments in mice demonstrated that expression of miR-325-3p was significantly reduced during the process of AP in humans and mice. Predicted using the TargetScan online database and through dual luciferase reporter assay detection, miR-325-3p directly targets the RIPK3 gene. In vitro experiments revealed that overexpression of miR-325-3p reversed caerulein-induced apoptosis and necroptosis in MPC83 pancreatic acinar cancer cell line. We used Z-VAD-FMK to assess necroptosis and demonstrated that miR-325-3p targets necroptosis to reduce cell damage. In subsequent experiments in mice, we verified that overexpression of miR-325-3p reduces inflammation, edema, hemorrhage, and necrosis in acute pancreatitis. Characteristic western blot, immunohistochemistry, and transmission electron microscopy results revealed that overexpression of miR-325-3p reduces the severity of acute pancreatitis by inhibiting pancreatic necroptosis in AP mice.

CONCLUSIONS

The current research results indicate that miR-325-3p directly targets RIPK3 and exerts a protective role in mouse AP. Necroptosis is still the primary mechanism of RIPK3 regulation. MiR-325-3p inhibits acute pancreatitis by targeting RIPK3-dependent necroptosis, which may represent a novel treatment method for acute pancreatitis.

Damage associated molecular patterns and neutrophil extracellular traps in acute pancreatitis

Previous researches have emphasized a trypsin-centered theory of acute pancreatitis (AP) for more than a century. With additional studies into the pathogenesis of AP, new mechanisms have been explored. Among them, the role of immune response bears great importance. Pro-inflammatory substances, especially damage-associated molecular patterns (DAMPs), play an essential role in activating, signaling, and steering inflammation. Meanwhile, activated neutrophils attach great importance to the immune defense by forming neutrophil extracellular traps (NETs), which cause ductal obstruction, premature trypsinogen activation, and modulate inflammation. In this review, we discuss the latest advances in understanding the pathological role of DAMPs and NETs in AP and shed light on the flexible crosstalk between these vital inflammatory mediators. We, then highlight the potentially promising treatment for AP targeting DAMPs and NETs, with a focus on novel insights into the mechanism, diagnosis, and management of AP.

Acinar Cell-Derived Extracellular Vesicle MiRNA-183-5p Aggravates Acute Pancreatitis by Promoting M1 Macrophage Polarization Through Downregulation of FoxO1

Acute pancreatitis (AP) is a common cause of a clinically acute abdomen. Crosstalk between acinar cells and leukocytes (especially macrophages) plays an important role in the development of AP. However, the mechanism mediating the interaction between acinar cells and macrophages is still unclear. This study was performed to explore the role of acinar cell extracellular vesicles (EVs) in the crosstalk between acinar cells and macrophages involved in the pathogenesis of AP. EVs derived from caerulein-treated acinar cells induced macrophage infiltration and aggravated pancreatitis in an AP rat model. Further research showed that acinar cell-derived EV miR-183-5p led to M1 macrophage polarization by downregulating forkhead box protein O1 (FoxO1), and a dual-luciferase reporter assay confirmed that FoxO1 was directly inhibited by miR-183-5p. In addition, acinar cell-derived EV miR-183-5p reduced macrophage phagocytosis. Acinar cell-derived EV miR-183-5p promoted the pancreatic infiltration of M1 macrophages and increased local and systemic damage in vivo. Subsequently, miR-183-5p overexpression in macrophages induced acinar cell damage and trypsin activation, thus further exacerbating the disease. In clinical samples, elevated miR-183-5p levels were detected in serum EVs and positively correlated with the severity of AP. EV miR-183-5p might play an important role in the development of AP by facilitating M1 macrophage polarization, providing a new insight into the diagnosis and targeted management of pancreatitis.

Graphical abstract of the present study. In our caerulein-induced AP model, miR-183-5p was upregulated in injured acinar cells and transported by EVs to macrophages. miR-183-5p could induce M1 macrophage polarization through downregulation of FoxO1 and the release of inflammatory cytokines, which could aggravate AP-related injuries. Therefore, a vicious cycle might exist between injured ACs and M1 macrophage polarization, which is fulfilled by EV-transported miR-183-5p, leading to sustainable and progressive AP-related injuries.

The Mechanism of Lung and Intestinal Injury in Acute Pancreatitis: A Review

Acute pancreatitis (AP), as a common cause of clinical acute abdomen, often leads to multi-organ damage. In the process of severe AP, the lungs and intestines are the most easily affected organs aside the pancreas. These organ damages occur in succession. Notably, lung and intestinal injuries are closely linked. Damage to ML, which transports immune cells, intestinal fluid, chyle, and toxic components (including toxins, trypsin, and activated cytokines to the systemic circulation in AP) may be connected to AP. This process can lead to the pathological changes of hyperosmotic edema of the lung, an increase in alveolar fluid level, destruction of the intestinal mucosal structure, and impairment of intestinal mucosal permeability. The underlying mechanisms of the correlation between lung and intestinal injuries are inflammatory response, oxidative stress, and endocrine hormone secretion disorders. The main signaling pathways of lung and intestinal injuries are TNF-α, HMGB1-mediated inflammation amplification effect of NF-κB signal pathway, Nrf2/ARE oxidative stress response signaling pathway, and IL-6-mediated JAK2/STAT3 signaling pathway. These pathways exert anti-inflammatory response and anti-oxidative stress, inhibit cell proliferation, and promote apoptosis. The interaction is consistent with the traditional Chinese medicine theory of the lung being connected with the large intestine (fei yu da chang xiang biao li in Chinese). This review sought to explore intersecting mechanisms of lung and intestinal injuries in AP to develop new treatment strategies.

Pyroptosis in acute pancreatitis and its therapeutic regulation

Pyroptosis defines a new type of GSDMs-mediated programmed cell death, distinguishes from the classical concepts of apoptosis and necrosis-mediated cell death and is prescribed by cell swelling and membrane denaturation, leading to the extensive secretion of cellular components and low-grade inflammatory response. However, NLRP3 inflammasome activation can trigger its downstream inflammatory cytokines, leading to the activation of pyroptosis-regulated cell death. Current studies reveal that activation of caspase-4/5/11-driven non-canonical inflammasome signaling pathways facilitates the pathogenesis and progression of acute pancreatitis (AP). In addition, a large number of studies have reported that NLRP3 inflammasome-dependent pyroptosis is a crucial player in driving the course of the pathogenesis of AP. Excessive uncontrolled GSDMD-mediated pyroptosis has been implicated in AP. Therefore, the pyroptosis-related molecule GSDMD may be an independent prognostic biomarker for AP. The present review paper summarizes the molecular mechanisms of pyroptotic signaling pathways and their pathophysiological impacts on the progress of AP. Moreover, we briefly present some experimental compounds targeting pyroptosis-regulated cell death for exploring novel therapeutic directions for the treatment and management of AP. Our review investigations strongly suggest that targeting pyroptosis could be an ideal therapeutic approach in AP.

New challenges for microRNAs in acute pancreatitis: progress and treatment

Acute pancreatitis (AP) is a common clinical abdominal emergency, with a high and increasing incidence each year. Severe AP can easily cause systemic inflammatory response syndrome, multiple organ dysfunction and other complications, leading to higher hospitalization rates and mortality. Currently, there is no specific treatment for AP. Thus, we still need to understand the exact AP pathogenesis to effectively cure AP. With the rise of transcriptomics, RNA molecules, such as microRNAs (miRNAs) transcribed from nonprotein-coding regions of biological genomes, have been found to be of great significance in the regulation of gene expression and to be involved in the occurrence and development of many diseases. Increasing evidence has shown that miRNAs, as regulatory RNAs, can regulate pancreatic acinar necrosis and apoptosis and local and systemic inflammation and play an important role in the development and thus potentially the diagnosis and treatment of AP. Therefore, here, the current research on the relationship between miRNAs and AP is reviewed.

Adenosine Kinase Inhibition Prevents Severe Acute Pancreatitis via Suppressing Inflammation and Acinar Cell Necroptosis

Background: Inflammatory disorder and acinar cell death contribute to the initiation and progression of severe acute pancreatitis (SAP). Adenosine kinase (ADK) has potential effects on both inflammation and cell death. However, the role of ADK in SAP remains to be explored.

Methods: To establish an experimental SAP model, male C57BL/6 mice were intraperitoneally injected with cerulein (50 μg/kg, seven doses at hourly intervals) and LPS (10 mg/kg, at the last cerulein injection). For ADK inhibition, ABT702 (1.5 mg/kg) was intraperitoneally injected 1 h before cerulein treatment. The pancreas and serum were collected and analyzed to determine the severity of pancreatic injury and explore the potential pathophysiological mechanisms. Pancreatic acinar cells (AR42J) were used to explore the in vitro effects of ADK inhibition on cerulein–induced inflammation and necroptotic cell death.

Results: ADK inhibition notably attenuated the severity of SAP, as indicated by the decreased serum amylase (7,416.76 ± 1,457.76 vs. 4,581.89 ± 1,175.04 U/L) and lipase (46.51 ± 11.50 vs. 32.94 ± 11.46 U/L) levels and fewer pancreatic histopathological alterations (histological scores: 6.433 ± 0.60 vs. 3.77 ± 0.70). MOMA-2 and CD11b staining confirmed that ADK inhibition prevented the infiltration of neutrophils and macrophages. The phosphorylation of nuclear factor-κB (NF-κB) was also reduced by ADK inhibition. ADK inhibition markedly limited the necrotic area of the pancreas and prevented the activation of the necroptotic signaling pathway. Endoplasmic reticulum (ER) stress was activated in the pancreas using the SAP model and cerulein–treated AR42J cells whereas ADK inhibition reversed the activation of ER stress both in vivo and in vitro. Moreover, the alleviating effects of ADK inhibition on ER stress, inflammation, and cell necroptosis were eliminated by the adenosine A_2A receptor antagonist.

Conclusion: ADK inhibition reduced inflammation and necroptotic acinar cell death in SAP via the adenosine A_2A receptor/ER stress pathway, suggesting that ADK might be a potential therapeutic target for SAP.

Paeonol protects against acute pancreatitis by inhibiting M1 macrophage polarization via the NLRP3 inflammasomes pathway

The excessive inflammatory response mediated by macrophage is one of the key factors for the progress of acute pancreatitis (AP). Paeonol (Pae) was demonstrated to exert multiple anti-inflammatory effects. However, the role of Pae on AP is not clear. In the present study, we aimed to investigate the protective effect and mechanism of Pae on AP in vivo and vitro. In the caerulein-induced mild acute pancreatitis (MAP) model, we found that Pae administration reduced serum levels of amylase, lipase, IL-1β and IL-6 and alleviated the histopathological manifestations of pancreatic tissue in a dose-dependent manner. And Pae decrease the ROS generated, restore mitochondrial membrane potential (ΔΨm), inhibit M1 macrophage polarization and NLRP3 inflammasome in bone marrow-derived macrophages (BMDMs) in vitro. In addition, specific NLRP3 inhibitor MCC950 eliminated the protective effect of Pae on AP induced by caerulein in mice. Correspondingly, the inhibitory effect of Pae on ROS generated and M1 polarization was not observed in BMDMs with MCC950 in vitro. Taken together, our datas for the first time confirmed the protective effects of Pae on AP via the NLRP3 inflammasomes Pathway.

Extracellular histones cause intestinal epithelium injury and disrupt its barrier function in vitro and in vivo

Extracellular histones are cytotoxic to various cells and have been extensively proven a vital mediator of multiple organ injuries. However, the effect of extracellular histones on the intestine remains largely unknown. This study aimed to clarify the effect of extracellular histones on the intestine. IEC-6, a cell line of rat small intestinal epithelial crypt, and C57BL/6 or ICR mice were treated with histones. The IEC-6 cells treated with histones from 20 μg/mL to 200 μg/mL for 0-24 h displayed a decline of cell viability and an increase of cell death in a concentration- and time-dependent manner. Moreover, histones (100 μg/mL) induced IEC-6 apoptosis through activating caspase 3 and necroptosis through up-regulation of receptor-interacting serine/threonine protein kinase 1 and 3 (RIPK1 and RIPK3), phosphorylated mixed-lineage kinase domain-like protein (p-MLKL) along with the decrease of caspase-8. Histones treatment disturbed zonular occludens 1 (ZO-1) expression and increased permeability of IEC-6 cell monolayer. In vivo, histones 50 mg/kg injection caused mice intestinal edema, loss apex of villus, epithelial lifting down the sides of the villi, and increased neutrophil infiltration. Elevation of serum intestinal fatty acid binding protein (I-FABP), D-lactate, or Diamine oxidase (DAO) and loss of tight junction protein, ZO-1, at 3 h and 6 h after histones injection strongly indicated severe intestinal epithelium injury, which led to increased permeability of the intestine. In conclusion, extracellular histones cause intestinal epithelial damage via direct cytotoxicity. Consequently, intestinal epithelial tight junction and barrier integrity are disrupted, which may play pivotal roles in diverse diseases.

miR-340-5p inhibits pancreatic acinar cell inflammation and apoptosis via targeted inhibition of HMGB1

Acute pancreatitis (AP) is a common gastrointestinal disease that affects 1 million individuals worldwide. Inflammation and apoptosis are considered to be important pathogenic mechanisms of AP, and high mobility group box 1 (HMGB1) has been shown to play a particularly important role in the etiology of this disease. MicroRNAs (miRs) are emerging as critical regulators of gene expression and, as such, they represent a promising area of therapeutic target identification and development for a variety of diseases, including AP. Using the online database query (microRNA.org), the current study identified a site in the 3' untranslated region of HMGB1 mRNA that was a viable target for miR-340-5p. The present study aimed to investigate the association between miR-340-5p and HMGB1 expression in pancreatic acinar cells following lipopolysaccharide (LPS) treatment by performing luciferase, western blotting and reverse transcription-quantitative PCR assays. The results suggest that miR-340-5p attenuates the induction of HMGB1 by LPS, thereby inhibiting inflammation and apoptosis via blunted activation of Toll-like receptor 4 and enhanced AKT signaling. Thus, the therapeutic application of miR-340-5p may be a useful strategy in AP via upregulation of HMGB1 and subsequent promotion of inflammation and apoptosis.

Molecular Patterns in Acute Pancreatitis Reflect Generalizable Endotypes of the Host Response to Systemic Injury in Humans

OBJECTIVE

Acute Pancreatitis (AP) is sudden onset pancreas inflammation that causes systemic injury with a wide and markedly heterogeneous range of clinical consequences. Here, we hypothesized that this observed clinical diversity corresponds to diversity in molecular subtypes that can be identified in clinical and multiomics data.

SUMMARY BACKGROUND DATA

Observational cohort study. n = 57 for the discovery cohort (clinical, transcriptomics, proteomics, and metabolomics data) and n = 312 for the validation cohort (clinical and metabolomics data).

METHODS

We integrated coincident transcriptomics, proteomics, and metabolomics data at serial time points between admission to hospital and up to 48 hours after recruitment from a cohort of patients presenting with acute pancreatitis. We systematically evaluated 4 different metrics for patient similarity using unbiased mathematical, biological, and clinical measures of internal and external validity.We next compared the AP molecular endotypes with previous descriptions of endotypes in a critically ill population with acute respiratory distress syndrome (ARDS).

RESULTS

Our results identify 4 distinct and stable AP molecular endotypes. We validated our findings in a second independent cohort of patients with AP.We observed that 2 endotypes in AP recapitulate disease endotypes previously reported in ARDS.

CONCLUSIONS

Our results show that molecular endotypes exist in AP and reflect biological patterns that are also present in ARDS, suggesting that generalizable patterns exist in diverse presentations of critical illness.

Protective Effects of Natural Polysaccharides on Intestinal Barrier Injury: A Review

Owing to their minimal side effects and effective protection from oxidative stress, inflammation, and malignant growth, natural polysaccharides (NPs) are a potential adjuvant therapy for several diseases caused by intestinal barrier injury (IBI). More studies are accumulating on the protective effects of NPs with respect to IBI, but the underlying mechanisms remain unclear. Thus, this review aims to represent current studies that investigate the protective effects of NPs on IBI by directly maintaining intestinal epithelial barrier integrity (inhibiting oxidative stress, regulating inflammatory cytokine expression, and increasing tight junction protein expression) and indirectly regulating intestinal immunity and microbiota. Furthermore, the mechanisms underlying IBI development are briefly introduced, and the structure-activity relationships of polysaccharides with intestinal barrier protection effects are discussed. Potential developments and challenges associated with NPs exhibiting protective effects against IBI have also been highlighted to guide the application of NPs in the treatment of intestinal diseases caused by IBI.

Molecular Events Involved in Influenza A Virus-Induced Cell Death

Viral infection usually leads to cell death. Moderate cell death is a protective innate immune response. By contrast, excessive, uncontrolled cell death causes tissue destruction, cytokine storm, or even host death. Thus, the struggle between the host and virus determines whether the host survives. Influenza A virus (IAV) infection in humans can lead to unbridled hyper-inflammatory reactions and cause serious illnesses and even death. A full understanding of the molecular mechanisms and regulatory networks through which IAVs induce cell death could facilitate the development of more effective antiviral treatments. In this review, we discuss current progress in research on cell death induced by IAV infection and evaluate the role of cell death in IAV replication and disease prognosis.

B Cell Receptor Signaling and Protein Kinase D2 Support Regulatory B Cell Function in Pancreatic Cancer

B cells can act as potent suppressors of anti-tumor T cell immunity, presenting a mechanism of resistance to immunotherapy. In pancreatic ductal adenocarcinoma, B cells can display a T cell-suppressive or regulatory phenotype centered on the expression of the cytokine Interleukin 35 (IL-35). While B cell-mediated immunosuppression presents a barrier to anti-tumorigenic T cell function, it is not clear how regulatory B cell function could be targeted, and the signals that promote this suppressive phenotype in B cells are not well understood. Here we use a novel IL-35 reporter model to understand which signaling pathways are important for immunosuppressive properties in B cells. In vitro analysis of IL-35 reporter B cells revealed a synergy between the BCR and TLR4 signaling pathways is sufficient to induce IL-35 expression. However, in vivo, B cell receptor activation, as opposed to MyD88 signaling in B cells, is central to B cell-mediated suppression and promotion of pancreatic cancer growth. Further analysis identified protein kinase D2 (PKD2) as being a key downstream regulator of IL-35 expression in B cells. Regulatory B cells with an inactivating mutation in PKD2 failed to produce IL-35 or fully suppress effector T cell function in vitro. Furthermore, inhibition of PKD in B cells decreased tumor growth and promoted effector T cell function upon adoptive transfer into B cell-deficient mice. Collectively, these data provide insight into how regulatory B cell function is promoted in pancreatic cancer and identify potential therapeutic targets to restrain this function.