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

Bone Marrow Mesenchymal Stem Cells Alleviate Acute Severe Pancreatitis and Promote Lung Repair via Inhibiting NLRP3 Inflammasome in Rat

BACKGROUND

Acute severe pancreatitis (SAP) is a severe acute abdominal disease, which can lead to pancreatic infection and necrosis as well as distant organ damage. Bone marrow mesenchymal stem cells (BMSCs) can exert anti-inflammatory effect on SAP, while NLRP3 inflammasomes play an important role in the inflammatory response. This study aimed to investigate whether BMSCs exert anti-inflammatory effect on SAP by inhibiting NLRP3 inflammasome.

METHODS

The rat SAP model was established. Serum amylase, lipase and inflammatory factor levels were measured by ELISA, and the level of tissue injury was assessed by HE staining. The expression of NLRP3 inflammasome was detected by PCR, Western Blot and immunohistochemistry. ML385 was used to block Nrf2 pathway, aiming to investigate whether Nrf2 pathway was involved in the therapeutic effect of BMSCs on SAP by regulating NLRP3 inflammasome expression.

RESULTS

In SAP rats, NLRP3 inflammasome was activated, which became more evident over time. After transplantation of BMSCs, the NLRP3 inflammasome expression decreased at both mRNA and protein levels, the serum levels of amylase, lipase and inflammatory factors decreased, and the pathological scores of the pancreas and lung were both improved. After blocking the Nrf2 pathway, the NLRP3 inflammasome expression increased in the injured pancreas and lung, and the inflammation deteriorated, which inhibited the therapeutic effects of BMSCs on SAP.

CONCLUSION

The therapeutic effect of BMSC on SAP is at least partially ascribed to the inhibition of NLRP3 inflammasome, and Nrf2 pathway mediates the therapeutic effect of BMSC on SAP by inhibiting NLRP3 inflammasome.

The trigger for pancreatic disease: NLRP3 inflammasome

NLRP3 inflammasome is a multiprotein complex expressed in a variety of cells to stimulate the production of inflammatory factors. Activation of NLRP3 inflammasome depends on a complex regulatory mechanism, and its pro-inflammatory function plays an important role in pancreatic diseases. In this literature review, we summarize the activation mechanism of NLRP3 and analyze its role in each of the four typical pancreatic diseases. Through this article, we provide a relatively comprehensive summary to the researchers in this field, and provide some targeted therapy routes.

Common NLRP3 inflammasome inhibitors and Covid-19: Divide and conquer

Severe SARS-CoV-2 infection causes systemic inflammation, cytokine storm, and hypercytokinemia due to activation of the release of pro-inflammatory cytokines that have been associated with case-fatality rate. The immune overreaction and cytokine storm in the infection caused by SARS-CoV-2 may be linked to NLRP3 inflammasome activation which has supreme importance in human innate immune response mainly against viral infections. In SARS-CoV-2 infection, NLRP3 inflammasome activation results in the stimulation and synthesis of natural killer cells (NKs), NFκB, and interferon-gamma (INF-γ), while inhibiting IL-33 expression. Various efforts have identified selective inhibitors of NLRP3 inflammasome. To achieve this, studies are exploring the screening of natural compounds and/or repurposing of clinical drugs to identify potential NLRP3 inhibitors. NLRP3 inflammasome inhibitors are expected to suppress exaggerated immune reaction and cytokine storm-induced-organ damage in SARS-CoV-2 infection. Therefore, NLRP3 inflammasome inhibitors could mitigate the immune-overreaction and hypercytokinemia in Covid-19 infection.

NLRP3 inflammasome in digestive diseases: From mechanism to therapy

Digestive system diseases remain a formidable challenge to human health. NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is the most characteristic multimeric protein complex and is involved in a wide range of digestive diseases as intracellular innate immune sensors. It has emerged as a research hotspot in recent years. In this context, we provide a comprehensive review of NLRP3 inflammasome priming and activation in the pathogenesis of digestive diseases, including clinical and preclinical studies. Moreover, the scientific evidence of small-molecule chemical drugs, biologics, and phytochemicals, which acts on different steps of the NLRP3 inflammasome, is reviewed. Above all, deep interrogation of the NLRP3 inflammasome is a better insight of the pathomechanism of digestive diseases. We believe that the NLRP3 inflammasome will hold promise as a novel valuable target and research direction for treating digestive disorders.

Protective effects of HTD4010, a Reg3a/PAP-derived peptide, in a mouse model of hypertriglyceridemic acute pancreatitis: Involvement of TLR4/NF-kappa B

Acute pancreatitis (AP) is an inflammatory disorder of pancreas and common digestive diseases, effective drug for AP is few. As an analog of active center of Reg3α, the biological activities of HTD4010 are similar to Reg3α. This study aimed to explore whether HTD4010 could decrease the inflammatory response and pancreatic injury in hypertriglyceridemic-AP (HTG-AP), and explore underlying mechanisms. This study was shown that the administration of HTD4010 could decrease the inflammatory response, reduce acinar cell injury (both apoptosis and necroptosis) and damage of lung tissue in HTG-AP. Moreover, HTD4010 down-regulated the expression of TLR4 and NF-κB protein. These results showed that HTD4010 could alleviate the severity of AP possibly by TLR4/NF-κB signaling pathway in HTG-AP.

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.

A novel self-nanomicellizing system of empagliflozin for oral treatment of acute pancreatitis: An experimental study

Acute pancreatitis (AP) is a severe inflammatory disorder hampered by a lack of effective drugs in its clinical practice. Empagliflozin (EMP) exhibits potential effects against AP but is limited by poor water-solubility and low bioavailability. Herein, a novel self-nanomicellizing formulation of EMP with phytochemical rebaudioside A (RA) as the nanocarrier (RA-EMP) was fabricated to address these issues. RA-EMP powder could be simply prepared and exhibited excellent storage stability, dramatically improved EMP's apparent solubility, and instantly self-assembled into micelles with high EMP encapsulation efficiency in water. In vivo experimental studies showed that RA-EMP exhibited significantly enhanced oral bioavailability of EMP and dramatically improved therapeutic efficacy against AP. The mechanisms through suppressing the effects of oxidative stress and proinflammatory cytokines were involved in this therapeutic effect. The results demonstrated that RA-EMP could serve as a promising way to enhance the oral bioavailability and strengthen the potential therapeutic efficacy of EMP against AP.

Hypobaric Hypoxia Induces Deficits in Adult Neurogenesis and Social Interaction via Cyclooxygenase-1/ EP1 Receptor Pathway Activating NLRP3 Inflammasome

Low oxygen environments, like hypobaric hypoxia (HH), are common nodes in a number of diseases characterized by neuroinflammation, which is detrimental to the structural and functional aspects of hippocampal circuitry. Hypoxic conditions lead to elevation of inflammasome-mediated inflammation that may contribute to cognitive deficits. However, a systematic investigation of the impact of inflammasome-mediated neuroinflammation on the components of neurogenic niche during HH remains to be elusive. Cerebral hypoxia was induced in adult male Sprague Dawley rats via decreasing partial pressure of oxygen. The effect of HH (1, 3, and 7 days at 25,000 ft) on social memory, anxiety, adult neurogenesis, and NLRP3- (NLR family pyrin domain containing 3) mediated neuroinflammation in the dentate gyrus (DG) was explored in detail. Furthermore, we explored the therapeutic efficacy of cyclooxygenase-1 inhibitor (valeryl salicylate, 5 mg/kg/day, i.p.) and EP1 receptor (EP1R) antagonist (SC19220, 1 mg/kg/day, i.p.) on HH-induced deficits. Seven days of HH exposure induced alteration in social and anxiety-like behavior along with perturbation in adult neurogenesis. Elevation in NLRP3, caspase-1, and IL-1β levels was observed during HH from day 1. A notable increase in the COX-1/EP1R pathway in activated glial cells in DG was evident during HH. COX-1 inhibitor and EP1R antagonist mitigated the detrimental effects of HH on social memory, adult neurogenesis via blunting NLRP3-mediated inflammation. Our data showed induction of the COX-1/EP1R pathway in the glial cells, which is detrimental to neurogenesis and social memory, opening up the possibility that the COX-1/EP1R pathway is a plausible target for inflammasome-related neurogenesis impairments.

The Effects of NLRP3 Inflammasome Inhibition in Experimental Acute Pancreatitis: A Systematic Review and Meta-Analysis

ABSTRACT

Acute pancreatitis (AP) is an inflammatory disease, and NLRP3 inflammasome activation is involved in the pathogenesis of AP. Previous research showed that inhibition of NLRP3 inflammasome may exert protective effects on animal models of AP and reduces disease severity. The aim of this systematic review and meta-analysis is to evaluate the effects of drug treatment of NLRP3 inflammasome on the outcomes of experimental AP. PubMed, Embase, Medline, and Web of Science databases were searched for relevant articles without language restrictions. The main outcomes for this study included local pancreatic injury, the incidence of systemic inflammatory responses, and the incidence of organ failure. Twenty-eight animal studies including 556 animals with AP were included in the meta-analysis. Compared with controls, inhibition of NLRP3 inflammasome significantly reduced the pancreatic histopathological scores, serum amylase, and lipase levels. In addition, inhibition of NLRP3 inflammasome reduced the levels of circulating inflammatory cytokines, as well as mitigating severity of AP-associated acute lung injury and acute intestinal injury. To conclude, inhibition of NLRP3 inflammasome has protective effects on AP by mitigating organ injury and systemic inflammation in animal studies, indicating that NLRP3 inflammasome holds promise as a target for specific AP therapy.

Common NLRP3 inflammasome inhibitors and Covid-19: Divide and Conquer

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A systematic review of NSAIDs treatment for acute pancreatitis in animal studies and clinical trials

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently given to patients with acute pancreatitis (AP) for controlling pain, but their efficacy in treating AP, particularly in reducing systemic complications, remains unclear.

AIM

The aim of our study was to evaluate the efficacy of NSAIDs in treating AP and its systematic complications.

METHODS

Two independent reviewers screened articles from MEDLINE, Embase and Cochrane and scored the quality of each study according to the CAMARADES 10-item quality checklist or the Jadad scale. Five endpoints were chosen to evaluate the effect of NSAIDs in animal studies: amylase and lipase levels, proinflammatory cytokines, oxidative damage, histopathological changes, and mortality rate. Meanwhile, in clinical studies, endpoints, such as proinflammatory cytokines, pain relief, systematic complications, mortality, and adverse events were used.

RESULTS

A total of 36 studies out of 17,845 were identified and included. Of these 36 studies, only 5 were clinical trials involving 580 patients, and the remaining 31 were animal studies with 1623 rats or mice. 24 studies focused on the treatment of AP with NSAIDs and 12 on AP-associated systematic complications. Both preclinical and clinical studies showed that NSAIDs may have beneficial effects against AP-related injuries. 9 of the 14 preclinical studies stated that NSAIDs reduced the serum amylase level significantly, and 6 of 7 showed that NSAIDs lowered the lipase level markedly. 17 experimental studies all demonstrated that NSAIDs reduced the inflammation. Histopathological examinations indicated that NSAIDs significantly improved the histopathological damages. Similarly, clinical evidence showed that NSAIDs are effective in suppressing proinflammatory cytokines, relieving pain, ameliorating systematic complications and reducing mortality. In the included 5 clinical studies, serious adverse events associated with NSAIDs were rarely reported.

CONCLUSION

This systematic review shows that NSAIDs are a potential treatment for AP-related injuries based on the current preclinical and clinical evidences.

Iguratimod Alleviates Myocardial Ischemia/Reperfusion Injury Through Inhibiting Inflammatory Response Induced by Cardiac Fibroblast Pyroptosis via COX2/NLRP3 Signaling Pathway

Background: NLRP3 inflammasome contributes a lot to sterile inflammatory response and pyroptosis in ischemia/reperfusion (I/R) injury. Cardiac fibroblasts (CFs) are regarded as semi-professional inflammatory cells and they exert an immunomodulatory role in heart. Iguratimod provides a protective role in several human diseases through exerting a powerful anti-inflammatory effect. However, it is still unclear whether iguratimod could alleviate myocardial I/R injury and whether inflammation triggered by NLRP3-related pyroptosis of CFs is involved in this process. Methods: Transcriptomics analysis for GSE160516 dataset was conducted to explore the biological function of differentially expressed genes during myocardial I/R. In vivo, mice underwent ligation of left anterior descending coronary artery for 30 min followed by 24 h reperfusion. In vitro, primary CFs were subjected to hypoxia for 1 h followed by reoxygenation for 3 h (H/R). Iguratimod was used prior to I/R or H/R. Myocardial infarct area, serum level of cardiac troponin I (cTnI), pathology of myocardial tissue, cell viability, lactate dehydrogenase (LDH) release, and the expression levels of mRNA and protein for pyroptosis-related molecules were measured. Immunofluorescence was applied to determine the cellular localization of NLRP3 protein in cardiac tissue. Results: During myocardial I/R, inflammatory response was found to be the most significantly enriched biological process, and nucleotide-binding oligomerization domain (NOD)-like receptor signaling was a crucial pathway in mediating cardiac inflammation. In our experiments, pretreatment with iguratimod significantly ameliorated I/R-induced myocardial injury and H/R-induced pyroptosis of CFs, as evidenced by reduced myocardial infarct area, serum cTnI level, and LDH release in supernatants, as well as improved pathology of cardiac tissue and cell viability. Immunofluorescence analysis showed that NLRP3 was mainly localized in CFs. Moreover, iguratimod inhibited the expression of pro-inflammatory cytokines and pyroptosis-related molecules, including NLRP3, cleaved caspase-1, and GSDMD-N. Conclusion: Our results suggested that inflammatory response mediated by NOD-like receptor signaling is of vital importance in myocardial I/R injury. Iguratimod protected cardiomyocytes through reducing the cascade of inflammation in heart by inhibiting cardiac fibroblast pyroptosis via the COX2/NLRP3 signaling pathway.

TNFAIP3-upregulated RIP3 exacerbates acute pancreatitis via activating NLRP3 inflammasome

Acute pancreatitis (AP) is an inflammatory disease of the pancreas. Accumulating studies have revealed the involvement of tumor necrosis factor alpha-induced protein 3 (TNFAIP3) in the progression of AP. Here, the current study was conducted to elucidate the role of TNFAIP3 and the underlying molecular mechanisms on the progression of AP. The in vivo animal model and in vitro cell model of AP were generated by retrograde injection of sodium taurocholate and stimulation of cerulein into AR42J cells, respectively. Relationships among TNFAIP3, receptor interacting protein 3 (RIP3) and nod-like receptor protein 3 (NLRP3) were predicted on bioinformatics websites and verified by co-immunoprecipitation. AR42J cells were transfected with overexpressing plasmid or shRNA to study the effects of TNFAIP3/RIP3/NLRP3 axis on cell proliferation and apoptosis, secretion of inflammatory cytokines and production of ROS. The effect of TNFAIP3/RIP3/NLRP3 axis in AP was further confirmed in vivo. High expression of TNFAIP3 was observed in AP pancreatic tissues and AP cell model. TNFAIP3 increased RIP phosphorylation through deubiquitination. RIP activated the NLRP3 inflammasome. Silencing of TNFAIP3 or RIP3T led to elevated proliferation and inhibited apoptosis in AR42J cells, accompanied by decreased inflammatory cytokine levels and ROS production. The protective role of inhibited TNFAIP3 in AP was confirmed evidenced by reduced levels of AMY, LIPA, and ROS in vivo. Collectively, overexpressed TNFAIP3 could contribute to the progression of AP by activating RIP3/NLRP3 axis, providing a potential therapeutic target for AP treatment.

Rectal Indomethacin Does Not Mitigate the Systemic Inflammatory Response Syndrome in Acute Pancreatitis: A Randomized Trial

INTRODUCTION

Experimental data suggest that nonsteroidal antiinflammatory drugs may prevent disease severity and mortality in acute pancreatitis (AP). The aim of this study was to compare the efficacy of rectal indomethacin vs placebo in reducing the systemic inflammatory response syndrome (SIRS) score in a high-risk AP population for clinical progression.

METHODS

We conducted a single-center, quadruple-blinded, randomized, placebo-controlled trial. Eligible criteria were subjects with AP and SIRS within 72 hours of presentation and those without organ failure. Subjects were allocated in a 1:1 ratio to indomethacin or placebo using simple randomization. Both interventions were administered rectally every 8 hours for 6 doses and compared using both intention-to-treat and per-protocol analyses.

RESULTS

A total of 42 subjects (mean age 52 years, 55% men) were randomized to indomethacin (n = 18) or placebo (n = 24). There was no significant difference between the indomethacin and placebo groups in the change of SIRS score, proportion of subjects with SIRS, and distribution of SIRS scores at 24, 48, and 72 hours from randomization. There were no significant differences in the change of C-reactive protein levels at 48 hours or clinical outcomes between both treatment groups. Indomethacin was as safe as placebo, with 2 adverse events occurring in the placebo and none in the indomethacin arm.

DISCUSSION

Rectal indomethacin can be safely administered over 48 hours; however, it is not superior to placebo in reducing the SIRS or clinical progression in a high-risk population with AP (ClinicalTrials.gov: NCT02692391).

Combined use of indomethacin and hydration is the best conservative approach for post-ERCP pancreatitis prevention: A network meta-analysis

OBJECTIVES

Post-ERCP pancreatitis (PEP) is a life-threatening complication. Given the lack of a causative treatment for pancreatitis, it is of vital importance to minimize this risk of PEP. Multi-target preventive therapy may be the best choice for PEP prevention as disease development is multifactorial.

AIM

We aimed to assess the efficacy of a combination of indomethacin and hydration - type and amount - for PEP prevention via a network meta-analysis.

METHODS

Through a systematic search in three databases, we searched all randomized controlled trials involving hydration and indomethacin and ranked the PEP preventive efficacy with a Bayesian network meta-analysis using the PRISMA for Network Meta-Analyses (PRISMA-NMA) guideline. The RoB2 tool was used for risk of bias assessment, surface under the cumulative ranking curve (SUCRA) for ranking and PROSPERO for the study protocol [reg. no. CRD42018112698]. We used risk ratios (RR) for dichotomous data with 95% credible intervals (95% CrI).

RESULTS

The quantitative analysis included 7559 patients from 24 randomized controlled trials. Based on the SUCRA values, a combination of lactated Ringer's and indomethacin is more effective than single therapy with a 94% certainty. The percent relative risk ratios estimate preventive efficacy 70-99% higher for combinations than single therapies. Aggressive hydration with indomethacin (SUCRA 100%) is also significantly more effective than all other interventions (percent relative effect 94.3-98.1%).

CONCLUSIONS

A one-hit-on-each-target therapeutic approach is recommended in PEP prevention with an easily accessible combination of indomethacin and aggressive hydration for all average and high-risk patients without contraindication.

Pharmacological effects of Pugionium cornutum (L.) Gaertn. extracts on gastrointestinal motility are partially mediated by quercetin

BACKGROUND

The majority of global population suffer from various functional gastrointestinal disorders. Pugionium cornutum (L.) Gaertn. (PCG) is used to relieve indigestive symptoms in traditional Chinese medicine. However, little is known about the effects of bioactive components from PCG extracts on gastrointestinal motility.

METHODS

Crude ethanol extract of PCG (EEP) was prepared from Pugionium cornutum (L.) Gaertn. Different solvents were used to prepare fine extracts from EEP, including water extract of PCG (WEP), petroleum ether extract of PCG (PEEP), dichloromethane extract of PCG (DEP) and ethyl acetate extract of PCG (EAEP). Smooth muscle cell model and colonic smooth muscle stripe model were used to test the bioactive effects and mechanisms of different PCG extracts on contraction and relaxation. Diverse chromatographic methods were used to identify bioactive substances from PCG extracts.

RESULTS

EEP was found to promote the relaxation of gastric smooth muscle cell and inhibit the contraction of colonic smooth muscle strip. Among the fractions of EEP, EAEP mainly mediated the relaxation effect by stimulating intracellular calcium influx. Further evidences revealed that EAEP was antagonistic to acetylcholine. In addition, COX and NO-GC-PKC pathways may be also involved in EAEP-mediated relaxation effect. Quercetin was identified as a bioactive compound from PCG extract for the relaxation effect.

CONCLUSION

Our research supports the notion that PCG extracts promote relaxation and inhibits contraction of gastrointestinal smooth muscle at least partially through the effect from quercetin.

CTRP3 ameliorates cerulein-induced severe acute pancreatitis in mice via SIRT1/NF-κB/p53 axis

Severe acute pancreatitis (SAP) is a common and life-threatening clinical acute abdominal disease. C1q/tumor necrosis factor-related protein 3 (CTRP3), a novel paralog of adiponectin, has been identified as a crucial regulator in multiple types of inflammatory disorders. However, the biological role of CTRP3 in SAP remains poorly understood. The present study aimed to characterize the role of CTRP3 in SAP and illuminate the potential mechanisms involved. In the current study, SAP mouse models were induced by seven hourly intraperitoneal injection of cerulein (50 μg/kg) and an immediate intraperitoneal injection of lipopolysaccharide (10 mg/kg) after the last cerulein administration. Histological examination and serological analysis demonstrated that SAP mouse models were successfully established. Herein, we found that CTRP3 expression was significantly decreased in the pancreatic tissues of SAP mice compared with normal control mice. Furthermore, we explored the effects of CTRP3 rescue in SAP mice and discovered that CTRP3 overexpression attenuated pathological lesions, inhibited inflammatory mediator release and repressed acinar cell apoptosis. Notably, mechanistic studies revealed that CTRP3 overexpression suppressed NF-κB p65 phosphorylation and p53 acetylation to alleviate cerulein-induced SAP in mouse models through activation of silent information regulator 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent protein deacetylase. Collectively, our data indicate that CTRP3 may exert its protective effects in SAP mice via regulation of SIRT1-mediated NF-κB and p53 signaling pathways, implying a promising therapeutic strategy against SAP.

The Proresolving Lipid Mediator Maresin1 Alleviates Experimental Pancreatitis via Switching Macrophage Polarization

Method

Repeated caerulein injection was used to induce AP and chronic pancreatitis (CP) models in mice. The histopathological and serological changes were examined for evaluating the severity of the AP model, and flow cytometry was used for detecting macrophage phagocytosis and phenotype. Meanwhile, clodronate liposomes were used for macrophage depletion in mice. Finally, the CP model was adopted to further observe the protective effect of MaR1.

Result

MaR1 administration manifested the improved histopathological changes and the lower serum levels of amylase and lipase. However, MaR1 played no protective role in the pancreatic acinar cell line in vitro. It obviously reduced the macrophage infiltration in the injured pancreas, especially M1-type macrophages. After macrophage clearance, MaR1 showed no further protection in vivo. This study also demonstrated that MaR1 could alleviate fibrosis to limit AP progression in the CP model.

Conclusion

Our data suggests that MaR1 was a therapeutic and preventive target for AP in mice, likely operating through its effects on decreased macrophage infiltration and phenotype switch.

NLRP3 Inflammasome-Mediated Inflammation in Acute Pancreatitis

The discovery of inflammasomes has enriched our knowledge in the pathogenesis of multiple inflammatory diseases. The NLR pyrin domain-containing protein 3 (NLRP3) has emerged as the most versatile and well-characterized inflammasome, consisting of an intracellular multi-protein complex that acts as a central driver of inflammation. Its activation depends on a tightly regulated two-step process, which includes a wide variety of unrelated stimuli. It is therefore not surprising that the specific regulatory mechanisms of NLRP3 inflammasome activation remain unclear. Inflammasome-mediated inflammation has become increasingly important in acute pancreatitis, an inflammatory disorder of the pancreas that is one of the fatal diseases of the gastrointestinal tract. This review presents an update on the progress of research into the contribution of the NLRP3 inflammasome to acute pancreatic injury, examining the mechanisms of NLRP3 activation by multiple signaling events, the downstream interleukin 1 family of cytokines involved and the current state of the literature on NLRP3 inflammasome-specific inhibitors.

Acetyl-α-boswellic acid and Acetyl-β-boswellic acid protects against caerulein-induced pancreatitis via down-regulating MAPKs in mice

This study is to investigate the protective effect of Acetyl-α-boswellic acid and Acetyl-β-boswellic mixture(α/β-ABA), which is the active ingredients isolated from Frankincense, on actue pancreatitis and its mechanism. Our experimental results showed that 2 μM α/β-ABA reduced production of NO, TNF-α, IL-6, IL-10 and IL-1β in RAW264.7 cells that were stimulated with lipopolysaccharide (LPS) which indicates its anti-inflammatory role. In pancreatitis model induced by caerulein, intra-gastrical administration of 100 mg/kg α/β-ABA relieved inflammatory cells infiltration significantly and attenuated the serum elevation of amylase TNF-α and IL-6 remarkably in mice. Furthermore, α/β-ABA down-regulated mitogen-activated protein kinase (MAPK) family phosphorylated proteins in pancreas, including phosphorylated p38, ERK1/2 and JNK, to reduce the serum inflammatory factors. Finally, α/β-ABA alleviated the pancreatic edema and inflammatory cell infiltration in pancreatitis mice model. This study suggests that α/β-ABA may be targeted for drug development against pancreatitis via modulating MAPKs pathway.

Iguratimod (T-614) attenuates severe acute pancreatitis by inhibiting the NLRP3 inflammasome and NF-κB pathway

Severe acute pancreatitis (SAP) is an acute abdominal disease that can develop locally to the multiple organs. It is characterized by pancreatic tissue self-digestion, and the rapid release of inflammatory cytokines, which play a dominant role in local or even systemic inflammation. In this study, we investigate the protective effect of T-614 against SAP induced by cerulein plus LPS in mice. Biochemical markers associated with pancreatitis in serum such as inflammatory cytokines, amylase and lipase activities were measured. Related proteins of NLRP3 inflammasome and NF-κB signaling pathway were evaluated by western blotting. Hematoxylin-eosin staining (HE) and immunohistochemistry (IHC) were used to evaluate changes of inflammation in pancreatic tissue. T-614 significantly alleviated the elevation markers of pancreatitis and suppresses the pancreatic tissue damage, including histopathological and molecular manifestations. In conclusion, T-614 plays a protective role in experimental SAP mice model via anti-inflammatory effects.

Inhibiting role of rosiglitazone in the regulation of inflammatory response and protective effects for severe acute pancreatitis in mice

OBJECTIVES

Our study aimed to probe the effects of rosiglitazone treatment on a severe acute pancreatitis (SAP) model induced by caerulein and investigate the underlying mechanism.

METHODS

Differentially expressed messenger RNAs (mRNAs) in the mice of a SAP group were screened out by microarray analysis. The inflammatory response pathway was obtained from the online website DAVID Bioinformatics Resources 6.8. The interactions of caerulein and its target proteins were shown by search tool for interactions of chemicals (STITCH). Functional interactions of the genes associated with pancreatitis and the target proteins of caerulein were obtained with search tool for interactions of chemicals (STRING). SAP mice were established by hourly intraperitoneal injection of caerulein. Rosiglitazone was used as treatment drug, and pancreatic inflammation was assessed. The expression of Socs3 was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. The expression of interleukin (IL)-6, IL-1b, and Egr1 were studied by RT-PCR and Western blot analysis.

RESULTS

The GSE77983 data were analyzed, and the results showed that Socs3 was overexpressed in SAP tissues. The inflammation response pathway in pancreas was selected by DAVID, STITCH, and STRING. After injection of rosiglitazone in mice, the serum levels of amylase and lipase were decreased. Furthermore, the mRNA and protein levels of Socs3 and inflammatory cytokines in pancreatic tissues were downregulated.

CONCLUSIONS

Rosiglitazone could protect mice with SAP from injury by downregulating Socs3 and inhibiting the inflammatory response 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.

Free Total Rhubarb Anthraquinones Protect Intestinal Injury via Regulation of the Intestinal Immune Response in a Rat Model of Severe Acute Pancreatitis

Intestinal mucosal immune barrier dysfunction plays a key role in the pathogenesis of severe acute pancreatitis (SAP). Rhubarb is a commonly used traditional Chinese medicine as a laxative in China. It markedly protects pancreatic acinar cells from trypsin-induced injury in rats. Free total rhubarb anthraquinones (FTRAs) isolated and extracted from rhubarb display the beneficial effects of antibacteria, anti-inflammation, antivirus, and anticancer. The principal aim of the present study was to investigate the effects of FTRAs on the protection of intestinal injury and modification of the intestinal barrier function through regulation of intestinal immune function in rats with SAP. We established a rat model of SAP by injecting 3.5% sodium taurocholate (STC, 350 mg/kg) into the biliopancreatic duct via retrograde injection and treated the rats with FTRAs (36 or 72 mg/kg) or normal saline (control) immediately and 12 h after STC injection. Then, we evaluated the protective effect of FTRAs on intestinal injury by pathological analysis and determined the levels of endotoxin (ET), interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), nitric oxide (NO), myeloperoxidase (MPO), capillary permeability, nucleotide-binding oligomerization domain-like receptors 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD domain (ASC), casepase-1, secretary immunoglobulin A (SIgA), regulatory T cells (Tregs), and the ratio of Th1/Th2 in the blood and/or small intestinal tissues or mesenteric lymph node (MLN) cells. Moreover, the chemical profile of FTRAs was analyzed by HPLC-UV chromatogram. The results showed that FTRAs significantly protected intestinal damage and decreased the levels of ET, IL-1β, TNF-α, and NO in the blood and TNF-α, IL-1β, and protein extravasation in the intestinal tissues in SAP rats. Furthermore, FTRAs significantly decreased the expressions of NLRP3, ASC, and caspase-1, the number of Tregs and the ratio of Th1/Th2, while significantly increased the expression of SIgA in the intestinal tissues and/or MLN cells in SAP rats. Our results indicate that FTRAs could protect intestinal injury and improve intestinal mucosal barrier function through regulating immune function of SAP rats. Therefore, FTRAs may have the potential to be developed as the novel agent for the treatment of SAP clinically.