Possible role of toll-like receptor 4 in acute pancreatitis

TAK-242 attenuates NLRP3-ASC inflammasome-mediated neuroinflammation via TLR4/NF-κB pathway in rat experimental autoimmune neuritis

The inhibition of the TLR4 receptor has been shown to protect neural structure and improve neurological functions in peripheral nervous system (PNS) diseases. There is a scarcity of research regarding the effect of inflammasomes during the process of neuroinflammation in immune related PNS disorders, such as, Guillain-Barré syndrome (GBS), even though it is an essential part for pathophysiology from immunological diseases that impact central nervous system (CNS). In this investigation, we found that TLR4 expression and formation and activation of the NLRP3 inflammasome were increased in the sciatic nerve of experimental autoimmune neuritis (EAN). Further intraperitoneal injection of the selective TLR4 receptor inhibitor TAK-242 (Resatorvid) showed that TAK-242 not only stopped the advancement of EAN to a certain extent, but also alleviated peripheral nerve injury brought on by EAN, as evidenced by improvements in body weight loss, neurological function scores, and nerve conduction deficits. More importantly, TAK-242 effectively inhibited neuroinflammation in EAN rats, mitigated myelin loss and helped the regeneration and repair of EAN peripheral nerve injury, mainly through suppressing TLR4/NF-κB signaling pathway and decreasing NLRP3 inflammasome activation. Based on these findings, administration of TAK-242 can be used as a potential therapy approach for GBS.

Fabp5 is a common gene between a high-cholesterol diet and acute pancreatitis

BACKGROUND AND AIMS

Hypercholesterolemia has been identified as risk factor for severe acute pancreatitis (AP). We aimed to identify the common differentially expressed genes (DEGs) between a high-cholesterol diet and AP.

METHODS

We retrived gene expression profiles from the GEO database. DEGs were assessed using GEO2R. For AP hub genes, we conducted functional enrichment analysis and protein-protein interaction (PPI) analysis. GeneMANIA and correlation analysis were employed to predict potential DEG mechanisms. Validation was done across various healthy human tissues, pancreatic adenocarcinoma, peripheral blood in AP patients, and Sprague-Dawley rats with AP.

RESULTS

The gene "Fabp5" emerged as the sole common DEG shared by a high-cholesterol diet and AP. Using the 12 topological analysis methods in PPI network analysis, Rela, Actb, Cdh1, and Vcl were identified as hub DEGs. GeneMANIA revealed 77.6% physical interactions among Fabp5, TLR4, and Rela, while genetic correlation analysis indicated moderate associations among them. Peripheral blood analysis yielded area under the ROC curve (AUC) values of 0.71, 0.63, 0.74, 0.64, and 0.91 for Fabp5, TLR4, Actb, Cdh1 genes, and artificial neural network (ANN) model respectively, in predicting severe AP. In vivo immunohistochemical analysis demonstrated higher Fabp5 expression in the hyperlipidemia-associated AP group compared to the AP and control groups.

CONCLUSION

Fabp5 emerged as the common DEG connecting a high-cholesterol diet and AP. Rela was highlighted as a crucial hub gene in AP. Genetic interactions were observed among Fabp5, TLR4, and Rela. An ANN model consisting of Fabp5, TLR4, Actb, and Cdh1 was helpful in predicting severe AP.

Intestinal TLR4 deletion exacerbates acute pancreatitis through gut microbiota dysbiosis and Paneth cells deficiency

Toll-like receptor 4 (TLR4) has been identified as a potentially promising therapeutic target in acute pancreatitis (AP). However, the role of intestinal TLR4 in AP and AP-associated gut injury remains unclear. This study aimed to explore the relationship between intestinal TLR4 and gut microbiota during AP. A mouse AP model was establish by intraperitoneal injection of L-arginine. Pancreatic injury and intestinal barrier function were evaluated in wild-type and intestinal epithelial TLR4 knockout (TLR4ΔIEC) mice. Gut microbiota was analyzed by 16S rRNA sequencing. Quadruple antibiotics were applied to induce microbiota-depleted mice. Differentially expressed genes in gut were detected by RNA sequencing. L. reuteri treatment was carried out in vivo and vitro study. Compared with wild-type mice, AP and AP-associated gut injury were exacerbated in TLR4ΔIEC mice in a gut microbiota-dependent manner. The relative abundance of Lactobacillus and number of Paneth cells remarkably decreased in TLR4ΔIEC mice. The KEGG pathway analysis derived from RNA sequencing suggested that genes affected by intestinal TLR4 deletion were related to the activation of nod-like receptor pathway. Furthermore, L. reuteri treatment could significantly improve the pancreatic and intestinal injury in TLR4ΔIEC mice through promoting Paneth cells in a NOD2-dependent manner. Loss of intestinal epithelial TLR4 exacerbated pancreatic and intestinal damage during AP, which might be attributed to the gut microbiota dysbiosis especially the exhausted Lactobacillus. L. reuteri might maintain intestinal homeostasis and alleviate AP via Paneth cells modulation.Abbreviations: AP Acute pancreatitis, TLR4 Toll-like receptor 4, IL-1β Interleukin-1β, IL-6 Interleukin-6, TNF-α Tumor necrosis factor-α, SIRS Systematic inflammatory response syndrome, LPS Lipopolysaccharides, SPF Specific pathogen-free, ZO-1 Zonula occludens-1, CON Control, H&E Hematoxylin and eosin, FISH Fluorescence in situ hybridization, DAPI 4',6-diamidino-2-phenylindole, PCoA Principal co-ordinates analysis, SCFA Short chain fatty acid, LEfSe Linear discriminant analysis Effect Size, ANOVA Analysis of variance, F/B Firmicutes/Bacteroidetes, PCA Principal component analysis, NOD2 Nod-like receptor 2, ABX antibiotics, PCNA proliferating cell nuclear antigen.

Usefulness of Random Forest Algorithm in Predicting Severe Acute Pancreatitis

BACKGROUND AND AIMS

This study aimed to develop an interpretable random forest model for predicting severe acute pancreatitis (SAP).

METHODS

Clinical and laboratory data of 648 patients with acute pancreatitis were retrospectively reviewed and randomly assigned to the training set and test set in a 3:1 ratio. Univariate analysis was used to select candidate predictors for the SAP. Random forest (RF) and logistic regression (LR) models were developed on the training sample. The prediction models were then applied to the test sample. The performance of the risk models was measured by calculating the area under the receiver operating characteristic (ROC) curves (AUC) and area under precision recall curve. We provide visualized interpretation by using local interpretable model-agnostic explanations (LIME).

RESULTS

The LR model was developed to predict SAP as the following function: -1.10-0.13×albumin (g/L) + 0.016 × serum creatinine (μmol/L) + 0.14 × glucose (mmol/L) + 1.63 × pleural effusion (0/1)(No/Yes). The coefficients of this formula were utilized to build a nomogram. The RF model consists of 16 variables identified by univariate analysis. It was developed and validated by a tenfold cross-validation on the training sample. Variables importance analysis suggested that blood urea nitrogen, serum creatinine, albumin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, calcium, and glucose were the most important seven predictors of SAP. The AUCs of RF model in tenfold cross-validation of the training set and the test set was 0.89 and 0.96, respectively. Both the area under precision recall curve and the diagnostic accuracy of the RF model were higher than that of both the LR model and the BISAP score. LIME plots were used to explain individualized prediction of the RF model.

CONCLUSIONS

An interpretable RF model exhibited the highest discriminatory performance in predicting SAP. Interpretation with LIME plots could be useful for individualized prediction in a clinical setting. A nomogram consisting of albumin, serum creatinine, glucose, and pleural effusion was useful for prediction of SAP.

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.

The Role of Toll-like Receptors (TLRs) Mediated Inflammation in Pancreatic Cancer Pathophysiology

Pancreatic cancer (PC) is one of the most lethal forms of cancer, characterized by its aggressiveness and metastatic potential. Despite significant improvements in PC treatment and management, the complexity of the molecular pathways underlying its development has severely limited the available therapeutic opportunities. Toll-like receptors (TLRs) play a pivotal role in inflammation and immune response, as they are involved in pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Activation of TLRs initiates a signaling cascade, which in turn, leads to the transcription of several genes involved in inflammation and anti-microbial defense. TLRs are also deregulated in several cancers and can be used as prognostic markers and potential targets for cancer-targeted therapy. In this review we discuss the current knowledge about the role of TLRs in PC progression, focusing on the available TLRs-targeting compounds and their possible use in PC therapy.

Pancreatitis initiated pancreatic ductal adenocarcinoma: Pathophysiology explaining clinical evidence

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant lethal disease due to its asymptomatic at its early lesion of the disease and drug resistance. Target therapy associated with molecular pathways so far seems not to produce reasonable outcomes. Understanding of the molecular mechanisms underlying inflammation-initiated tumorigenesis may be helpful for development of an effective therapy of the disease. A line of studies showed that pancreatic tumorigenesis was resulted from pancreatitis, which was caused synergistically by various pancreatic cells. This review focuses on those players and their possible clinic implications, such as exocrine acinar cells, ductal cells, and various stromal cells, including pancreatic stellate cells (PSCs), macrophages, lymphocytes, neutrophils, mast cells, adipocytes and endothelial cells, working together with each other in an inflammation-mediated microenvironment governed by a myriad of cellular signaling networks towards PDAC.

Asiaticoside ameliorates acinar cell necrosis in acute pancreatitis via toll-like receptor 4 pathway

Acinar cell necrosis is one of the most prominent pathophysiological changes of acute pancreatitis (AP). Asiaticoside (AS) is a triterpene compound with confirmed apoptosis-and necrosis-related activities. However, the specific effects of AS on AP have not been determined. In this study, we aimed to investigate the protective effect of AS on AP using two mouse models. In the caerulein-induced mild acute pancreatitis (MAP) model, We found that AS administration reduced serum amylase levels and alleviated the histopathological manifestations of pancreatic tissue in a dose-dependent manner. And the levels of toll-like receptor 4 (TLR4) and necrotic related proteins (RIP3 and p-MLKL) of pancreatic tissue were reduced after AS administration. In addition, TLR4 deficiency eliminated the protective effect of AS on AP induced by caerulein in mice. Correspondingly, we elucidated the effect of AS in vitro and found that AS protected against pancreatic acinar cells necrosis and TAK-242 counteracted this protective effect. Meanwhile, we found that AS ameliorated the severity of pancreatic tissue injury and pancreatitis-associated lung injury in a severe acute pancreatitis model induced by l-arginine. Furthermore, Molecular docking results revealed interaction between AS and TLR4. Taken together, our data for the first time confirmed the protective effects of AS on AP in mice via TLR4 pathway.

The Role of TLR-4 and Galectin-3 Interaction in Acute Pancreatitis

Toll-like receptor-4 (TLR-4) is a member of evolutionarily conserved type I transmembrane proteins that can initiate sterile inflammatory cascade in the pancreas. Expression of TLR-4 is up-regulated in pancreatic tissue, as well as, on peripheral blood innate immune cells in human and experimental models of acute pancreatitis. TLR-4 plays important pro-inflammatory roles during development of acute pancreatitis: it recognize alarmins released from injured acinar cells and promotes activation and infiltration of innate immune cells after the premature and intraacinar activation of tripsinogen. Galectin-3 is β-galactoside-binding lectin that plays pro-inflammatory roles in a variety autoimmune diseases, acute bacterial infections and during tumorigenesis. It is reported that Galectin-3 is alarmin in experimental models of neuroinflammation and binds to TLR-4 promoting the pro-inflammatory phenotype of microglia. Also, in experimental model of acute pancreatitis Galectin-3 is colocalized with TLR-4 on innate inflammatory cells resulted in enhanced production of inflammatory cytokines, TNF-α and IL-1β, increased infiltration of pro-inflammatory N1 neutrophils, macrophages and dendritic cells and increased damage of pancreatic tissue. This review paper discusses the role of TLR-4/Gal-3 axis in the pathogenesis of acute pancreatitis.

Edaravone Protects against Pancreatic and Intestinal Injury after Acute Pancreatitis via Nuclear Factor-κB Signaling in Mice

Acute pancreatitis (AP) is one kind of acute surgical abdominal disease in the world. It causes intestinal damage with subsequent bacterial migration, endotoxemia and secondary pancreatic infections. In this investigation, we determined that edaravone (EDA) reduces pancreatic and intestinal injury after AP in mice. This was demonstrated by a reduction in histological score, apoptosis, interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α, along with obstructing activation of Toll-like receptor 4 (TLR4) and nuclear factor-κB (NFκB). Our study results suggested that EDA exerts its protective effects against pancreatic and intestinal injury after AP via regulation of the TLR4/NFκB pathway. Our findings provide the basis for EDA to treat AP-induced pancreatic and intestinal injury, even might develop as a potential therapy for other inflammatory diseases.

High-Fat Diet Aggravates Acute Pancreatitis via TLR4-Mediated Necroptosis and Inflammation in Rats

High-fat diet (HFD) often increases oxidative stress and enhances inflammatory status in the body. Toll-like receptor 4 (TLR4) is widely expressed in the pancreatic tissues and plays an important role in pancreatitis. This study is aimed at investigating the effect of HFD on acute pancreatitis (AP) and the role of TLR4-mediated necroptosis and inflammation in this disease. Weight-matched rats were allocated for an 8-week feeding on the standard chow diet (SCD) or HFD, and then, the AP model was induced by infusion of 5% sodium taurocholate into the biliopancreatic duct. Rats were sacrificed at an indicated time point after modeling. Additionally, inhibition of TLR4 signaling by TAK-242 in HFD rats with AP was conducted in vivo. The results showed that the levels of serum free fatty acid (FFA) in HFD rats were higher than those in SCD rats. Moreover, HFD rats were more vulnerable to AP injury than SCD rats, as indicated by more serious pathological damage and much higher pancreatic malondialdehyde (MDA) and lipid peroxidation (LPO) levels as well as lower pancreatic superoxide dismutase (SOD) activities and reduced glutathione (GSH) contents and more intense infiltration of MPO-positive neutrophils and CD68-positive macrophages. In addition, HFD markedly increased the expressions of TLR4 and necroptosis marker (RIP3) and aggravated the activation of NF-κB p65 and the expression of TNF-α in the pancreas of AP rats at indicated time points. However, TLR4 inhibition significantly attenuated the structural and functional damage of the pancreas induced by AP in HFD rats, as indicated by improvement of the above indexes. Taken together, these findings suggest that HFD exacerbated the extent and severity of AP via oxidative stress, inflammatory response, and necroptosis. Inhibition of TLR4 signaling by TAK-242 alleviated oxidative stress and decreased inflammatory reaction and necroptosis, exerting a protective effect during AP in HFD rats.

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

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

Inflammatory stimuli promote oxidative stress in pancreatic acinar cells via Toll-like receptor 4/nuclear factor-κB pathway

The Toll‑like receptor 4/nuclear factor‑κB (TLR4/NF‑κB) pathway is vital to the pathogenesis of acute pancreatitis (AP). The aim of the present study was to identify the mechanism of the activation of the TLR4/NF‑κB signaling pathway in the viability of primary pancreatic cells. The cells were stimulated with lipopolysaccharide (LPS) for the activation of NF‑κB signaling. Next, the reactive oxygen species (ROS) level was evaluated by detecting the concentration of malondialdehyde and glutathione peroxidase. Cell viability was measured by Cell Counting Kit‑8 and MTT assays, while the percentage of apoptosis was detected by flow cytometry. Quantitative polymerase chain reaction was used to detect TLR4, B‑cell lymphoma 2 (Bcl2), Bcl2‑associated X protein (Bax) and phorbol‑12‑myristate‑13‑acetate‑induced protein 1 (PMAIP1) expression levels. Western blot assay was also conducted to detect TLR4 protein expression, while the activity of NF‑κB signaling was measured by determining the p65 and phosphorylated p65 protein levels. In addition, the effect of TLR4 overexpression or treatment with TLR4 antagonists in the presence of LPS stimulation was investigated. The results revealed that ROS levels were increased and cell viability was decreased in LPS‑stimulated pancreatic acinar cells. TLR4, Bax and PMAIP1 levels were increased, Bcl2 expression was decreased and NF‑κB signaling was activated in LPS‑stimulated pancreatic acinar cells. Furthermore, pancreatic cells with TLR4 overexpression exhibited increased ROS level and decreased viability. Finally, the effect caused by LPS stimulation was partially reversed by treatment of pancreatic acinar cells with TLR4 antagonists. In conclusion, the current study investigated a novel regulatory mechanism of the TLR4/NF‑κB pathway in LPS‑stimulated pancreatic cells, which may contribute to pancreatitis. The damage of these cells due to increased ROS levels was observed to occur through activation of the TLR4/NF‑κB pathway.

Phosphoinositide 3‑kinase/protein kinase B regulates inflammation severity via signaling of Toll‑like receptor 4 in severe acute pancreatitis

Phosphatidylinositol 3‑kinase (PI3K)/protein kinase B (Akt) has been indicated to serve an important role in the pathogenesis of inflammatory diseases. It was previously demonstrated that the PI3K/Akt inhibitor wortmannin alleviated the severity of inflammation and improved the survival rate in rats with induced severe acute pancreatitis (SAP), which indicates that PI3K/Akt may serve a role in the pathogenesis of acute pancreatitis. To date, the mechanism by which PI3K/Akt regulates inflammation has not been elucidated. In the present study, it was hypothesized that PI3K/Akt may be invovled in SAP inflammation via regulation of the Toll‑like receptor 4 (TLR4) signaling pathway. Rats with SAP were treated with the PI3K/Akt agonist insulin‑like growth factor (IGF)‑1, which alleviated the severity of inflammation in a dose‑dependent manner. Furthermore, to better understand the role of PI3K/Akt in inflammation, RAW264.7 murine macrophages were stimulated with IGF‑1 and wortmannin alone or together before the induction of inflammation by treatment with lipopolysaccharide (LPS). The results indicated that LPS stimulated overexpression of TLR4, myeloid differentiation primary response gene 88 (MyD88), PI3K, Akt, p38MAPK and NF‑κBp65 mRNA, and increased the levels of tumor necrosis factor (TNF)‑α and interleukin (IL)‑6 in RAW264.7 cells compared with the control group. The levels of all detected factors were increased by stimulation with IGF‑1, whereas these levels were decreased following treatment with wortmannin alone, and the effect of IGF‑1 was abolished by wortmannin in RAW264.7 cells. In vivo studies indicated that IGF‑1 produced the same anti‑inflammatory effect as wortmannin and that expression of TLR4, p38MAPK and NF‑κBp65 decreased following treatment with IGF‑1. These findings indicate that PI3K/Akt may take part in the progression of SAP by regulating the TLR4 signaling pathway and that IGF‑1 can inhibit inflammation in SAP rats.

The Toll-like receptor 4 antagonist TAK-242 protects against chronic pancreatitis in rats

Chronic pancreatitis is a progressive disease characterized by irreversible morphological changes to the pancreas, typically causing pain and permanent loss of function. It is a poorly understood disease with the pathogenesis remaining unclear. The authors' previous data demonstrated that the inhibition of Toll‑like receptor 4 (TLR4) using TLR4 antagonist kinase (TAK)‑242 attenuates taurocholate‑induced oxidative stress via the regulation of mitochondrial function in the pancreatic acinar cells of mice. In the present study, the effect of TAK‑242 on trinitrobenzene sulfonic acid (TNBS)‑induced chronic pancreatitis was investigated in rats. The results revealed that TAK‑242 attenuated the severity of chronic pancreatic injury, and regulated extracellular matrix secretion and cellular immunity. In addition, TAK‑242 treatment significantly decreased cell apoptosis, as evidenced by the reduction in Terminal deoxynucleotidyl transferase dUTP nick end labeling‑positive cells in pancreas tissue sections, and also promoted cell proliferation in TNBS‑treated animals. Furthermore, the results of the calibrated von Frey filament assay demonstrated that TAK‑242 could prevent the pancreatitis‑induced referred abdominal hypersensitivity. In summary, TAK‑242 exhibits protective effects against TNBS‑induced chronic pancreatitis and may be a potential therapeutic strategy for the treatment of patients with chronic pancreatitis.

Blockade of high-mobility group box 1 attenuates intestinal mucosal barrier dysfunction in experimental acute pancreatitis

The release of inflammatory cytokines, that plays a dominant role in local pancreatic inflammation and systemic complications in severe acute pancreatitis (SAP). High-mobility group box 1 (HMGB1) is implicated in the mechanism of organ dysfunction and bacterial translocation in SAP. This current study aims to investigate possible role of HMGB1 in the intestinal mucosal barrier dysfunction of SAP, and the effect of anti-HMGB1 antibody treatment in intestinal mucosal injury in SAP. Our data revealed that the HMGB1 expression was significantly increased in AP mice induced by caerulein and LPS, and the inhibition of HMGB1 played a protective role in intestinal mucosal barrier dysfunction, reduced the serum level of other proinflammatory cytokines include IL-1β, IL-6, TNF-α. Next we investigated the downstream receptors involving in HMGB1 signaling. We found that the expressions of toll-like receptor (TLR) 4 and TLR9 were elevated in ileum of AP mice, the administration of HMGB1 neutralizing antibody significantly reduced the TLR4 and TLR9 expression. It was concluded that HMGB1 contributed the mechanism to the intestinal mucosal barrier dysfunction during AP. Blockade of HMGB1 by administration of HMGB1 neutralizing antibody may be a beneficial therapeutic strategy in improving intestinal mucosal barrier dysfunction in SAP.

The toll-like receptor 4 antagonist transforming growth factor-β-activated kinase(TAK)-242 attenuates taurocholate-induced oxidative stress through regulating mitochondrial function in mice pancreatic acinar cells

BACKGROUND

Acute pancreatitis (AP) is a commonly occurring and potentially life-threatening disease. Recently, toll-like receptor 4 (TLR4) has been considered as a new clue for studying the pathogenesis of AP due to its important role in inflammatory response cascade.

MATERIALS AND METHODS

The aim of this study was to investigate the potential protective effect of transforming growth factor-β-activated kinase (TAK)-242, a novel TLR4 antagonist, in taurocholate-treated mice pancreatic acinar cells. The protective effects were measured by cell viability, lactate dehydrogenase release and apoptosis, and oxidative stress was assayed by lipid peroxidation and oxidative enzyme activities. To determine the potential underlying mechanisms, mitochondrial cytochrome c release, swelling, and calcium buffering capacity were measured in isolated mitochondria, and mitochondrial biogenesis and expression of mitochondrial dynamic proteins were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot.

RESULTS

Treatment with 6-mM taurocholate significantly increased the expression of TLR4 at both mRNA and protein levels. TAK-242 markedly increased cell viability, decreased lactate dehydrogenase release, and inhibited apoptotic cell death as measured by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining in pancreatic acinar cells. These protective effects were accompanied by the suppressed lipid peroxidation and enhanced endogenous antioxidative enzyme activity. Using isolated and purified mitochondria from pancreatic acinar cells, we found that TAK-242 treatment also inhibited cytochrome c release into the cytoplasm, mitochondrial swelling, and decrease in mitochondrial Ca2+ buffering capacity after taurocholate exposure. In addition, TAK-242 significantly promoted mitochondrial biogenesis, as evidenced by increased mtDNA and upregulated mitochondrial transcription factors. The results of Western blot analysis showed that TAK-242 also differently regulated the expression of mitochondrial fusion and fission proteins.

CONCLUSIONS

All these data strongly indicated that blocking TLR4 activity via TAK-242 exerts protective effects in an in vitro AP model, and it could be a possible strategy to improve clinical outcome in AP patients.

Socs1 and Socs3 degrades Traf6 via polyubiquitination in LPS-induced acute necrotizing pancreatitis

Mechanisms involved in inflammatory development during acute pancreatitis (AP) are largely vague, especially in the transformation of acute edematous pancreatitis (AEP) into acute necrotizing pancreatitis (ANP). This current study aims to investigate the functions of Traf6 in different AP models in vitro and in vivo, and to identify the possible regulatory mechanism in the progression of inflammation from mild to severe. Our data revealed that the level of Traf6 expression was significantly increased in the mild AP induced by caerulein, and the upregulation of Traf6 played a protective role in acinar cells against caerulein-induced apoptosis. In contrast, only Traf6 protein but not mRNA was downregulated in the severe ANP induced by combination treatment of caerulein and LPS. Mechanistic studies showed that LPS upregulated the levels of Socs1 and Socs3 expressions in acinar cells, Socs1 and Socs3 interacted Traf6 directly and degraded Traf6 protein via polyubiquitination, thereby counteracted the protective function of Traf6. In vivo study further showed that combination treatment of caerulein and LPS failed to induce an ANP model in the TLR4 knockout mice, and the level of Traf6 expression in the pancreatic tissues remained the same as that from the acute edematous pancreatitis (AEP) mouse. Taken together, our study reveals that Traf6 functioned as a protective factor in the progression of AP, and LPS-induced Socs1 and Socs3 exacerbate mild AP to severe AP, which provides evidence for developing a new therapeutic target to combat AP.

Transforming growth factor-β-activated kinase 1 resistance limits glucocorticoid responsiveness to Toll-like receptor 4-mediated inflammation

Glucocorticoids (GC) are among the most effective anti-inflammatory drugs, but are often associated with serious adverse effects or inadequate therapeutic responses. Here, we use activation of different Toll-like receptors (TLRs) by their respective ligands to evaluate context-specific GC sensitivity in the macrophage. Recruitment and activation of transforming growth factor-β-activated kinase 1 (TAK1), downstream of TLR engagement, is crucial in activating multiple inflammatory pathways, and contributes to inflammatory disorders. We hypothesize that GC exert anti-inflammatory effects through regulation of TAK1. Both in vivo and in vitro, in comparison to other TLRs, there was limited GC potency in restricting TLR4 ligand-mediated secretion of interleukin-6, tumour necrosis factor-α and interleukin-12. Also, we found that inactivation of TAK1 both in vivo and in vitro strongly inhibits TLR4-induced inflammation-associated genes beyond the suppressive effects from GC treatment. However, there was no effect of TAK1 inactivation on GC inhibition of TLR3- or TLR9-initiated inflammatory actions. Together, our findings demonstrate that GC resistance for TAK1 activation associated with TLR4 engagement may be an important contributor to GC resistance in inflammatory disorders.

Atypical manifestations of leptospirosis

Leptospirosis is an illness with a wide spectrum of clinical manifestations and severe illness affects nearly all organ systems. Serious and potentially life-threatening clinical manifestations of acute leptospirosis are caused by both direct tissue invasion by spirochaetes and by the host immune responses. In its severe form, leptospirosis can cause multi-organ dysfunction and death in a matter of days. Therefore it is critical to suspect and recognize the disease early, in order to initiate timely treatment. While the classical presentation of the disease is easily recognized by experienced clinicians practising in endemic regions, rarer manifestations can be easily missed. In this systematic review, we summarize the atypical manifestations reported in literature in patients with confirmed leptospirosis. Awareness of these unusual manifestations would hopefully guide clinicians towards early diagnosis.

Effect of lornoxicam therapy on expression of TLR2 and TLR4 mRNA during systemic complications of acute pancreatitis

Primary pancreatic injury that occurs in acute pancreatitis leads to necrosis of pancreatic cells and is accompanied by the development systemic inflammatory response of varying severity. Systemic inflammatory response, in turn, can lead to the development of multiple organ dysfunction syndrome and death of patients. The release of damage-associated molecular patterns into the extracellular space is the trigger pathological mechanism underlying these processes. The released patterns exert their effects via Toll-like receptors (TLR). These findings suggest that TLR can be considered a new target for therapeutic intervention in acute pancreatitis. We studied mRNA expression of TLR2 and TLR4 in the peripheral blood mononuclear cells from the patients with acute pancreatitis and showed a decrease in the examined parameters associated with lornoxicam treatment. Anti-mediator therapy decreased mortality in these patients.

Activation of TLR4 is required for the synergistic induction of dual oxidase 2 and dual oxidase A2 by IFN-γ and lipopolysaccharide in human pancreatic cancer cell lines

Pancreatitis is associated with release of proinflammatory cytokines and reactive oxygen species and plays an important role in the development of pancreatic cancer. We recently demonstrated that dual oxidase (Duox)2, an NADPH oxidase essential for reactive oxygen species-related, gastrointestinal host defense, is regulated by IFN-γ-mediated Stat1 binding to the Duox2 promoter in pancreatic tumor lines. Because LPS enhances the development and invasiveness of pancreatic cancer in vivo following TLR4-related activation of NF-κB, we examined whether LPS, alone or combined with IFN-γ, regulated Duox2. We found that upregulation of TLR4 by IFN-γ in BxPC-3 and CFPAC-1 pancreatic cancer cells was augmented by LPS, resulting in activation of NF-κB, accumulation of NF-κB (p65) in the nucleus, and increased binding of p65 to the Duox2 promoter. TLR4 silencing with small interfering RNAs, as well as two independent NF-κB inhibitors, attenuated LPS- and IFN-γ-mediated Duox2 upregulation in BxPC-3 cells. Induction of Duox2 expression by IFN-γ and LPS may result from IFN-γ-related activation of Stat1 acting in concert with NF-κB-related upregulation of Duox2. Sustained extracellular accumulation of H(2)O(2) generated by exposure to both LPS and IFN-γ was responsible for an ∼50% decrease in BxPC-3 cell proliferation associated with a G(1) cell cycle block, apoptosis, and DNA damage. We also demonstrated upregulation of Duox expression in vivo in pancreatic cancer xenografts and in patients with chronic pancreatitis. These results suggest that inflammatory cytokines can interact to produce a Duox-dependent pro-oxidant milieu that could increase the pathologic potential of pancreatic inflammation and pancreatic cancer cells.

Controversial role of toll-like receptors in acute pancreatitis

Acute pancreatitis (AP) is a common clinical condition with an incidence of about 300 or more patients per million annually. About 10%-15% of patients will develop severe acute pancreatitis (SAP) and of those, 10%-30% may die due to SAP-associated complications. Despite the improvements done in the diagnosis and management of AP, the mortality rate has not significantly declined during the last decades. Toll-like receptors (TLRs) are pattern-recognition receptors that seem to play a major role in the development of numerous diseases, which make these molecules attractive as potential therapeutic targets. TLRs are involved in the development of the systemic inflammatory response syndrome, a potentially lethal complication in SAP. In the present review, we explore the current knowledge about the role of different TLRs that have been described associated with AP. The main candidate for targeting seems to be TLR4, which recognizes numerous damage-associated molecular patterns related to AP. TLR2 has also been linked with AP, but there are only limited studies that exclusively studied its role in AP. There is also data suggesting that TLR9 may play a role in AP.

Pancreatitis and myocarditis followed by pulmonary hemorrhage, a rare presentation of leptospirosis- a case report and literature survey

Background

Leptospirosis is a potentially fatal disease which can cause multi-organ dysfunction. It can rarely present as acute pancreatitis. This is the first ever report of leptospirosis presenting with acute pancreatitis and myocarditis followed by diffuse pulmonary hemorrhages to the best of our knowledge.

Case presentation

A 15-year-old South Asian boy presented with high grade fever, epigastric discomfort and was anicteric on admission. He developed tachycardia, transient hypotension, changes of electro-cardiogram and positive troponin I suggestive of myocarditis. Acute pancreatitis was diagnosed with 12 fold high serum amylase and with the evidence of computerized tomography. Then he developed diffuse pulmonary hemorrhages and later acute renal failure. Leptospirosis was confirmed by positive leptospira IgM, negative IgG and strongly positive Microscopic Agglutination Test. Other possible infective and autoimmune causes were excluded. Patient recovered completely with antibiotics and the supportive care.

Conclusion

This case illustrates diagnostic difficulties especially in resource poor settings where leptospirosis is common. Additionally it highlights the fact that leptospirosis should be considered in patients presenting with pancreatitis which can be complicated with myocarditis and diffuse pulmonary hemorrhages. We hypothesize that Toll like receptors may play a role in such systemic involvement.

Upregulation of TLR1, TLR2, TLR4, and IRAK-2 Expression During ML-1 Cell Differentiation to Macrophages: Role in the Potentiation of Cellular Responses to LPS and LTA

12-O-tetradecanoylphorbol 13-acetate (TPA) induces the differentiation of human myeloid ML-1 cells to macrophages. In the current study, the expression, responsiveness, and regulation of toll-like receptors (TLRs) in TPA-induced ML-1-derived macrophages were investigated. We have found that TPA-induced differentiation of ML-1 cells was accompanied by the upregulation of TLR1, TLR2, TLR4, and CD14 expression at both the mRNA and protein levels. Interestingly, TLR1 and TLR4 protein expression on ML-1 cells could be blocked by pretreatment with U0126, suggesting the role of an Erk1/2-induced differentiation signal in this process. In addition, the expression of IRAK-2, a key member of the TLR/IRAK-2/NF-κB-dependent signaling cascade was also induced in response to TPA. Accordingly, we demonstrated an increased cellular release of inflammatory cytokines (TNF-α and various interleukins) upon stimulation with LPS and LTA ligands for TLR4 and TLR2, respectively. Furthermore, using luminol-dependent chemiluminescence, addition of LPS and LTA induces a sustained DPI-inhibitable generation of reactive oxygen species (ROS) by the differentiated ML-1 cells. Together, these data suggest that the increase in the responsiveness of TPA-treated ML-1 cells to LPS and LTA occurs in response to the upregulation of their respective receptors as well as an induction of the IRAK-2 gene expression.

Toll-like receptor 4 signaling pathway and pancreatitis

The pathogenesis of pancreatitis has long been a hot topic in basic and clinical research but is still not fully clarified. Toll-like receptor 4 (TLR4) recognizes the lipopolysaccharide (LPS) of Gram-negative bacteria and stimulates the synthesis and release of inflammatory cytokines through activation of the NF-κB signaling pathway, which ultimately results in inflammatory responses that involve multiple organs. Animal and clinical studies have shown that the TLR4 signal pathway plays an important role in the development of tissue injury during acute pancreatitis (AP) and up-regulation of TLR4 and the TLR4 signaling pathway contributes to the development of multiple organ dysfunction syndrome (MODS) associated with severe acute pancreatitis (SAP) by increasing proinflammatory cytokines. Therefore, further studies are required to clarify the role of the TLR 4 signaling pathway in the pathogenesis of pancreatitis to explore novel methods for treating this disease.

Lipid profile changes and importance of low serum α-lipoprotein fraction (high-density lipoprotein) in cases with acute pancreatitis

OBJECTIVES

Acute pancreatitis (AP) is a common systemic inflammatory disorder of the pancreas. The data related to the lipid changes in patients with AP were insufficient. In this study, we aimed to investigate the relation between high-density lipoprotein (HDL) and the other lipid parameters and the severity of the disease in AP cases.

METHODS

Seventy-five cases admitted to the Gastroenterohepatology Clinic with diagnosis of AP were included in the study. Ranson scores and Glasgow scores were used for prognosis. Lipid parameters were evaluated for the first 24 hours and after clinic and laboratory remission.

RESULTS

The causes of the disease among patients included in the study were as follows: 44 biliary origin (58.7%), 14 alcohol dependent (18.7%), 10 idiopathic (13.3%), 6 hyperlipidemic (8%), and 1 endoscopic retrograde cholangiopancreatography dependent (1.3%). Triglyceride (TG) levels of the patients included in the study measured in the first 2 days were significantly higher than TG levels measured after clinic and laboratory remission (P = 0.013). High-density lipoprotein was significantly lower in alcoholic and hypertriglyceridemic AP cases. There was a statistical correlation between HDL and Ranson (P = 0.023).

CONCLUSION

The low levels of HDL in AP cases during acute attack are associated with severity of the disease.

TLR4 but not TLR2 regulates inflammation and tissue damage in acute pancreatitis induced by retrograde infusion of taurocholate

OBJECTIVE

Neutrophil infiltration is a key regulator in the pathophysiology of acute pancreatitis (AP), although the impact of Toll-like receptors (TLRs) in AP remains elusive. The aim of this study was to define the role of TLR2 and TLR4 in leukocyte recruitment and tissue damage in severe AP.

EXPERIMENTAL DESIGN

AP was induced by retrograde infusion of sodium taurocholate into the pancreatic duct in wild-type, TLR2- and TLR4-deficient mice. Samples were collected 24 h after induction of AP.

RESULTS

Taurocholate challenge caused a clear-cut pancreatic damage characterized by increased acinar cell necrosis, neutrophil infiltration, focal hemorrhage and edema formation, as well as increased levels of blood amylase and CXCL2 (macrophage inflammatory protein-2) in the pancreas and serum. Moreover, challenge with taurocholate increased activation of trypsinogen in the pancreas. Notably, TLR2 gene-deficient mice exhibited a similar phenotype to wild-type mice after challenge with taurocholate. In contrast, tissue damage, pancreatic and lung myeloperoxidase (MPO) activity, serum and pancreatic levels of CXCL2 as well as blood amylase were significantly reduced in TLR4-deficient mice exposed to taurocholate. However, taurocholate-induced activation of trypsinogen was intact in TLR4-deficient mice.

CONCLUSION

Our data suggest a role for TLR4 but not TLR2 in the pathogenesis of severe AP in mice.

The essential roles of Toll-like receptor signaling pathways in sterile inflammatory diseases

Toll-like receptors (TLRs) form a family of pattern recognition receptors with at least 11 members in human and 13 in mouse. TLRs recognize a wide variety of putative host-derived agonists that have emerged as key mediators of innate immunity. TLR signaling also plays an important role in the activation of the adaptive immune system by inducing pro-inflammatory cytokines and upregulating costimulatory molecules of antigen presenting cells. Inappropriate activation of TLRs by self-components generated by damaged tissues may result in sterile inflammation. This review discusses the contribution of TLR signaling to the initiation and progression of non-infectious inflammatory processes, such as ischemia and reperfusion (I/R) injury, tissue repair and regeneration and autoimmune diseases. The involvement of TLR signaling in the pathogenesis of sterile inflammation-related diseases may provide novel targets for the development of therapeutics.