Ordered transcriptional factor recruitment and epigenetic regulation of tnf-alpha in necrotizing acute pancreatitis

MFG-E8 Maintains Cellular Homeostasis by Suppressing Endoplasmic Reticulum Stress in Pancreatic Exocrine Acinar Cells

Excessive endoplasmic reticulum (ER) stress contributes significantly to the pathogenesis of exocrine acinar damage in acute pancreatitis. Our previous study found that milk fat globule EGF factor 8 (MFG-E8), a lipophilic glycoprotein, alleviates acinar cell damage during AP via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining cellular homeostasis. However, MFG-E8's role in ER stress in pancreatic exocrine acinar cells has not been evaluated. To study this, thapsigargin, brefeldin A, tunicamycin and cerulein + LPS were used to induce ER stress in rat pancreatic acinar cells in vitro. L-arginine- and cerulein + LPS-induced acute pancreatitis in mice were used to study ER stress in vivo. The results showed that MFG-E8 dose-dependently inhibited ER stress under both in vitro and in vivo conditions. MFG-E8 knockout mice suffered more severe ER stress and greater inflammatory response after L-arginine administration. Mechanistically, MFG-E8 increased phosphorylation of FAK and STAT3 in cerulein + LPS-treated pancreatic acinar cells. The presence of specific inhibitors of αvβ3/5 integrin, FAK or STAT3 abolished MFG-E8's effect on cerulein + LPS-induced ER stress in pancreatic acinar cells. In conclusion, MFG-E8 maintains cellular homeostasis by alleviating ER stress in pancreatic exocrine acinar cells.

Silencing of CREB Inhibits HDAC2/TLR4/NF-κB Cascade to Relieve Severe Acute Pancreatitis-Induced Myocardial Injury

The purpose of the present study is to investigate the role of CREB in cardiomyocytes proliferation in regulation of HDAC2-dependent TLR4/NF-κB pathway in severe acute pancreatitis (SAP)-induced myocardial injury. The SAP rat model was developed by injecting sodium touracholate into SD rats and then infected with lentivirus vectors expressing sh-CREB in the presence/absence of LPS. The pathological alterations of rat pancreatic and cardiac tissues were observed by HE staining. TUNEL assay was used to study apoptosis of cardiomyocytes. Next, the loss- and gain-function assay was conducted in LPS-induced myocardial injury cardiomyocytes to define the roles of CREB, HDAC2, and TLR4 in cardiomyocyte proliferation, apoptosis, inflammation, and myocardial injury in vitro. ChIP assay was used to study the enrichment of CREB bound to HDAC2 promoter. RT-qPCR and Western blot analysis were used to detect the expressions of related mRNA and proteins in the NF-κB pathway, respectively. CREB was found to be overexpressed in both SAP tissues and cells. CREB directly bound to the promoter of HDAC2 and activated its expression. Overexpressed CREB or HDAC2 inhibited proliferation and promoted apoptosis of cardiomyocytes. Suppression of CREB inhibited the HDAC2/TLR4/NF-κB cascade to promote proliferation and inhibit apoptosis of cardiomyocytes. The in vitro results were validated in vivo experiments. Coherently, suppression of CREB can inhibit HDAC2/TLR4/NF-κB cascade to promote cardiomyocyte proliferation, thus ameliorating SAP-induced myocardial injury.

P300/CBP-associated factor (PCAF) attenuated M1 macrophage inflammatory responses possibly through KLF2 and KLF4

Macrophages exhibit distinct phenotypes in response to environmental signals. The polarization of M1 macrophages plays an essential role in the inflammatory response. However, the specific molecular mechanisms regulating the inflammatory response during M1 macrophage polarization remain to be further understood. Here, we found that the histone acetyltransferase P300/CBP-associated factor (PCAF) was a potential negative regulator of the M1 macrophage inflammatory response. During M1 macrophage polarization, the inflammatory response gradually reduced, but PCAF expression increased. Furthermore, the overexpression of PCAF significantly inhibited the expression of the M1 macrophage-related pro-inflammatory genes TNF-α, IL-6 and CXCL10, while PCAF deficiency enhanced the expression of these genes. Furthermore, we found that PCAF overexpression suppressed the NF-κB signaling pathway and promoted the expression of the Krüppel-like factors (KLF) KLF2 and KLF4 through regulating their transcriptional levels. In addition, KLF2 and KLF4 deficiency reversed the PCAF-induced inhibition of the expression of pro-inflammatory genes in M1 macrophages. Collectively, the present results demonstrate a potential negative regulatory mechanism of the inflammatory response during M1 macrophage polarization and propose a novel mechanism of inflammation resolution for maintaining homeostasis.

CVB3 VP1 interacts with MAT1 to inhibit cell proliferation by interfering with Cdk-activating kinase complex activity in CVB3-induced acute pancreatitis

Coxsackievirus B3 (CVB3) belongs to the genus Enterovirus of the family Picornaviridae and can cause acute acinar pancreatitis in adults. However, the molecular mechanisms of pathogenesis underlying CVB3-induced acute pancreatitis have remained unclear. In this study, we discovered that CVB3 capsid protein VP1 inhibited pancreatic cell proliferation and exerted strong cytopathic effects on HPAC cells. Through yeast two-hybrid, co-immunoprecipitation, and confocal microscopy, we show that Menage a trois 1 (MAT1), a subunit of the Cdk-Activating Kinase (CAK) complex involved in cell proliferation and transcription, is a novel interaction protein with CVB3 VP1. Moreover, CVB3 VP1 inhibited MAT1 accumulation and localization, thus interfering with its interaction with CDK7. Furthermore, CVB3 VP1 could suppress CAK complex enzymic phosphorylation activity towards RNA Pol II and CDK4/6, direct substrates of CAK. VP1 also suppresses phosphorylation of retinoblastoma protein (pRb), an indirect CAK substrate, especially at phospho-pRb Ser780 and phospho-pRb Ser807/811 residues, which are associated with cell proliferation. Finally, we present evidence using deletion mutants that the C-terminal domain (VP1-D8, 768-859aa) is the minimal VP1 region required for its interaction with MAT1, and furthermore, VP1-D8 alone was sufficient to arrest cells in G1/S phase as observed during CVB3 infection. Taken together, we demonstrate that CVB3 VP1 can inhibit CAK complex assembly and activity through direct interaction with MAT1, to block MAT1-mediated CAK-CDK4/6-Rb signaling, and ultimately suppress cell proliferation in pancreatic cells. These findings substantially extend our basic understanding of CVB3-mediated pancreatitis, providing strong candidates for strategic therapeutic targeting.

Efficacy of Xuebijing Injection for Acute Pancreatitis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

METHODS

PubMed Medline, Embase, Cochrane Library, China National Knowledge Infrastructure, China Biology Medicine disc, VIP, and Wanfang databases were searched. The primary outcome was treatment response. The secondary outcomes included changes in clinical and laboratory indicators and incidence of AP-related complications. Meta-analyses were performed by using a random-effect model. Risk ratios (RRs) with 95% confidence intervals (CIs) or weighted mean differences (WMDs) with 95% CIs were calculated.

RESULTS

Overall, 23 RCTs were included. The rates of overall (RR = 1.16; 95% CI = 1.12 to 1.20; P < 0.00001) and complete (RR = 1.40; 95% CI = 1.30 to 1.50; P < 0.00001) responses were significantly higher in the Xuebijing injection group. After treatment, the levels of interleukin-6 (WMD = -18.22; 95% CI = -23.36 to -13.08; P < 0.00001), tumor necrosis factor-α (WMD = -16.44; 95% CI = -20.49 to -12.40; P < 0.00001), serum amylase (WMD = -105.61; 95% CI = -173.77 to -37.46; P=0.002), white blood cell (WMD = -1.51; 95% CI = -1.66 to -1.36; P < 0.00001), and C-reactive protein (WMD = -11.05; 95% CI = -14.32 to -7.78; P < 0.00001) were significantly lower in the Xuebijing injection group. Abdominal pain (WMD = -1.74; 95% CI = -1.96 to -1.52; P < 0.00001), abdominal distension (WMD = -1.56; 95% CI = -2.07 to -1.04; P < 0.00001), gastrointestinal function (WMD = -2.60; 95% CI = -3.07 to -2.13; P < 0.00001), body temperature (WMD = -2.16; 95% CI = -2.83 to -1.49; P < 0.00001), serum amylase level (WMD = -1.81; 95% CI = -2.66 to -0.96; P < 0.0001), and white blood cell (WMD = -2.16; 95% CI = -2.99 to -1.32; P < 0.00001) recovered more rapidly in the Xuebijing injection group. The incidence of multiple organ dysfunction syndrome (RR = 0.18; 95% CI = 0.05 to 0.62; P=0.006), pancreatic pseudocyst (RR = 0.17; 95% CI = 0.04 to 0.77; P=0.02), and renal failure (RR = 0.16; 95% CI = 0.05 to 0.60; P=0.006) was significantly lower in the Xuebijing injection group.

CONCLUSIONS

Xuebijing injection added on the basis of conventional treatment has a potential benefit for improving the outcomes of AP.

Pentoxifylline and Oxypurinol: Potential Drugs to Prevent the "Cytokine Release (Storm) Syndrome" Caused by SARS-CoV-2?

BACKGROUND

COVID-19, caused by SARS-CoV-2, is a potentially lethal, rapidly-expanding pandemic and many efforts are being carried out worldwide to understand and control the disease. COVID-19 patients may display a cytokine release syndrome, which causes severe lung inflammation, leading, in many instances, to death.

OBJECTIVE

This paper is intended to explore the possibilities of controlling the COVID-19-associated hyperinflammation by using licensed drugs with anti-inflammatory effects.

HYPOTHESIS

We have previously described that pentoxifylline alone, or in combination with oxypurinol, reduces the systemic inflammation caused by experimentally-induced pancreatitis in rats. Pentoxifylline is an inhibitor of TNF-α production and oxypurinol inhibits xanthine oxidase. TNF-α, in turn, activates other inflammatory genes such as Nos2, Icam or IL-6, which regulate migration and infiltration of neutrophils into the pulmonary interstitial tissue, causing injury to the lung parenchyma. In acute pancreatitis, the anti-inflammatory action of pentoxifylline seems to be mediated by the prevention of the rapid and presumably transient loss of PP2A activity. This may also occur in the hyperinflammatory -cytokine releasing phase- of SARS-CoV-2 infection. Therefore, it may be hypothesized that early treatment of COVID-19 patients with pentoxifylline, alone or in combination with oxypurinol, would prevent the potentially lethal acute respiratory distress syndrome.

CONCLUSION

Pentoxifylline and oxypurinol are licensed drugs used for diseases other than COVID-19 and, therefore, phase I clinical trials would not be necessary for the administration to SARS-CoV-2- infected people. It would be worth investigating their potential effects against the hyperinflammatory response to SARS-CoV-2 infection.

Pharmacological blockade of PCAF ameliorates osteoarthritis development via dual inhibition of TNF-α-driven inflammation and ER stress

Background

Epigenetic mechanisms have been reported to play key roles in osteoarthritis (OA) development. P300/CBP-associated factor (PCAF) is a member of the histone acetyltransferases, which exhibits a strong relationship with endoplasmic reticulum (ER) stress and transcription factor nuclear factor kappa B (NF-κB) signals. Salidroside, a natural histone acetylation inhibitor, showed its anti-inflammatory and anti-apoptotic effects in lipopolysaccharide (LPS)-stimulated microglia cells in our previous study. However, whether Sal has a protective effect against OA remains unknown, and its relationships to PCAF, NF-κB, and the ER stress pathway should be explored further.

Methods

We identified the role of PCAF in the pathogenesis of OA and determined the chondroprotective effect of Sal on both tumor necrosis factor alpha (TNF-α)-treated human chondrocytes and a destabilized medial meniscus (DMM) mouse OA model.

Findings

We found increased PCAF expression in human OA cartilage and TNF-α-driven chondrocytes. Meanwhile, silencing of PCAF attenuated nuclear p65 and C/EBP homologous protein levels in chondrocytes upon TNF-α stimulation. Furthermore, Sal was found to specifically bind to the inhibitory site of the PCAF protein structure, which subsequently reversed the TNF-α-induced activation of NF-κB signal and ER stress-related apoptosis in chondrocytes. In addition, the protective effect of Sal and its inhibitory effects on PCAF as well as inflammatory- and ER stress-related markers were also observed in the mouse DMM model.

Interpretation

Pharmacological blockade of PCAF by Sal ameliorates OA development via inhibition of inflammation and ER stress, which makes Sal a promising therapeutic agents for the treatment of OA.

Superoxide dismutase mimetic nanoceria restrains cerulein induced acute pancreatitis

Aim: The present study was carried out to assess the effect of nanoceria (NC) on pancreatic inflammation caused by cerulein. Methods: NC was characterized and in vitro studies were carried out in murine macrophages. The in vivo effects were tested on cerulein-induced pancreatitis. Results: In vitro treatment with NC remarkably protected macrophages from lipopolysaccharide-induced inflammation and oxidative stress as evident from the results of 2',7'-dichlorofluorescin diacetate, JC-1 and MitoSox staining. In vivo treatment with NC showed potent superoxide dismutase and catalase mimetic activity, antipancreatitis activity and improved histology. Furthermore, it reduced the expression of p65-NF-κB and acetylation of histone H3 at lysine K14, K56 and K79 residues. Conclusion: We for the first time, demonstrate that NC may be a promising candidate for the therapy of pancreatitis.

Yttrium oxide nanoparticles reduce the severity of acute pancreatitis caused by cerulein hyperstimulation

Oxidative stress plays a major role in acute pancreatitis (AP), leading to massive macrophage infiltration. Nanoyttria (NY) possesses potent free radical scavenging activity. As reactive oxygen species and inflammation play major role in AP, we hypothesized that NY may alleviate cerulein induced AP. NY ameliorated LPS induced oxidative stress in vitro. It reduced ROS, superoxide radical generation and restored the mitochondrial membrane potential in macrophages. Interestingly, NY reduced plasma amylase and lipase levels and attenuated the mitochondrial stress and inflammatory markers. NY suppressed the recruitment of inflammatory cells around the damaged pancreatic acinar cells. Furthermore, NY intervention perturbed the course of AP via reduction of endoplasmic reticulum (ER) stress markers (BiP, IRE1 and Ero1-Lα), and molecular chaperones (Hsp27 and Hsp70). We, to the best of our knowledge, report for first time that NY can attenuate experimental AP by restoration of mitochondrial and ER homeostasis through Nrf2/NFκB pathway modulation.

Chymotrypsinogen C Genetic Variants, Including c.180TT, Are Strongly Associated With Chronic Pancreatitis in Pediatric Patients

OBJECTIVES

Genetic studies in adults/adolescent patients with chronic pancreatitis (CP) identified chymotrypsinogen C (CTRC) genetic variants but their association with CP risk has been difficult to replicate. To evaluate the risk of CP associated with CTRC variants in CP pediatric patients-control study.

METHODS

The distribution of CTRC variants in CP pediatric cohort (n = 136, median age at CP onset 8 years) with no history of alcohol/smoking abuse was compared with controls (n = 401, median age 45).

RESULTS

We showed that p.Arg254Trp (4.6%) and p.Lys247_Arg254del (5.3%) heterozygous mutations are frequent and significantly associated with CP risk in pediatric patients (odds ratio [OR] = 19.1; 95% CI 2.8-160; P = 0.001 and OR = 5.5; 95% CI 1.6-19.4; P = 0.001, respectively). For the first time, we demonstrated that the c.180TT genotype of common p.Gly60Gly variant is strong, an independent CP risk factor (OR = 23; 95% CI 7.7-70; P < 0.001) with effect size comparable to p.Arg254Trp mutation. The other novel observation is that common c.493+51C>A variant, both CA and AA genotype, is significantly underrepresented in CP compared with controls (15% vs 35%; OR = 0.33; 95% CI 0.19-0.59; P < 0.001 and 2.8% vs 11%; OR = 0.24; 95% CI 0.06-0.85; P = 0.027, respectively).

CONCLUSIONS

Our study provides evidence that CTRC variants, including c.180TT (p.Gly60Gly) are strong CP risk factors. The c.493+51C>A variant may play a protective role against CP development.

Epigenetic Regulation of Early- and Late-Response Genes in Acute Pancreatitis

Chromatin remodeling seems to regulate the patterns of proinflammatory genes. Our aim was to provide new insights into the epigenetic mechanisms that control transcriptional activation of early- and late-response genes in initiation and development of severe acute pancreatitis as a model of acute inflammation. Chromatin changes were studied by chromatin immunoprecipitation analysis, nucleosome positioning, and determination of histone modifications in promoters of proinflammatory genes in vivo in the course of taurocholate-induced necrotizing pancreatitis in rats and in vitro in rat pancreatic AR42J acinar cells stimulated with taurocholate or TNF-α. Here we show that the upregulation of early and late inflammatory genes rely on histone acetylation associated with recruitment of histone acetyltransferase CBP. Chromatin remodeling of early genes during the inflammatory response in vivo is characterized by a rapid and transient increase in H3K14ac, H3K27ac, and H4K5ac as well as by recruitment of chromatin-remodeling complex containing BRG-1. Chromatin remodeling in late genes is characterized by a late and marked increase in histone methylation, particularly in H3K4. JNK and p38 MAPK drive the recruitment of transcription factors and the subsequent upregulation of early and late inflammatory genes, which is associated with nuclear translocation of the early gene Egr-1 In conclusion, specific and strictly ordered epigenetic markers such as histone acetylation and methylation, as well as recruitment of BRG-1-containing remodeling complex are associated with the upregulation of both early and late proinflammatory genes in acute pancreatitis. Our findings highlight the importance of epigenetic regulatory mechanisms in the control of the inflammatory cascade.

Redox signaling in acute pancreatitis

Acute pancreatitis is an inflammatory process of the pancreatic gland that eventually may lead to a severe systemic inflammatory response. A key event in pancreatic damage is the intracellular activation of NF-κB and zymogens, involving also calcium, cathepsins, pH disorders, autophagy, and cell death, particularly necrosis. This review focuses on the new role of redox signaling in acute pancreatitis. Oxidative stress and redox status are involved in the onset of acute pancreatitis and also in the development of the systemic inflammatory response, being glutathione depletion, xanthine oxidase activation, and thiol oxidation in proteins critical features of the disease in the pancreas. On the other hand, the release of extracellular hemoglobin into the circulation from the ascitic fluid in severe necrotizing pancreatitis enhances lipid peroxidation in plasma and the inflammatory infiltrate into the lung and up-regulates the HIF-VEGF pathway, contributing to the systemic inflammatory response. Therefore, redox signaling and oxidative stress contribute to the local and systemic inflammatory response during acute pancreatitis.

Histone acetyltransferase PCAF regulates inflammatory molecules in the development of renal injury

Kidney diseases, including chronic kidney disease (CKD) and acute kidney injury (AKI), are associated with inflammation. The mechanism that regulates inflammation in these renal injuries remains unclear. Here, we demonstrated that p300/CBP-associated factor (PCAF), a histone acetyltransferase, was overexpressed in the kidneys of db/db mice and lipopolysaccharide (LPS)-injected mice. Moreover, elevated histone acetylation, such as H3K18ac, and up-regulation of some inflammatory genes, such as ICAM-1, VCAM-1, and MCP-1, were found upon these renal injuries. Furthermore, increased H3K18ac was recruited to the promoters of ICAM-1, VCAM-1, and MCP-1 in the kidneys of LPS-injected mice. In vitro studies demonstrated that PCAF knockdown in human renal proximal tubule epithelial cells (HK-2) led to downregulation of inflammatory molecules, including VCAM-1, ICAM-1, p50 subunit of NF-κB (p50), and MCP-1 mRNA and protein levels, together with significantly decreased H3K18ac level. Consistent with these, overexpression of PCAF enhanced the expression of inflammatory molecules. Furthermore, PCAF deficiency reduced palmitate-induced recruitment of H3K18ac on the promoters of ICAM-1 and MCP-1, as well as inhibited palmitate-induced upregulation of these inflammatory molecules. In summary, the present work demonstrates that PCAF plays an essential role in the regulation of inflammatory molecules through H3K18ac, which provides a potential therapeutic target for inflammation-related renal diseases.

The Common Chymotrypsinogen C (CTRC) Variant G60G (C.180T) Increases Risk of Chronic Pancreatitis But Not Recurrent Acute Pancreatitis in a North American Population

OBJECTIVES:

Recurrent acute pancreatitis (RAP) is a complex inflammatory disorder that may progress to fibrosis and other irreversible features recognized as chronic pancreatitis (CP). Chymotrypsinogen C (CTRC) protects the pancreas by degrading prematurely activated trypsinogen. Rare mutations are associated with CP in Europe and Asia. We evaluated the occurrence of CTRC variants in subjects with RAP, CP, and controls from the North American Pancreatitis Study II cohort.

METHODS:

CP (n=694), RAP (n=448), and controls (n=1017) of European ancestry were evaluated. Subgroup analysis included CFTR and SPINK1 variants, alcohol, and smoking.

RESULTS:

We identified previously reported rare pathogenic CTRC A73T, R254W, and K247_R254del variants, intronic variants, and G60G (c.180 C>T; rs497078). Compared with controls (minor allele frequency (MAF)=10.8%), c.180T was associated with CP (MAF=16.8%, P<0.00001) but not RAP (MAF=11.9% P=NS). Trend test indicated co-dominant risk for CP (CT odds ratio (OR)=1.36, 95% confidence interval (CI)=1.13–1.64, P=0.0014; TT OR=3.98, 95% CI=2.10–7.56, P<0.0001). The T allele was significantly more frequent with concurrent pathogenic CFTR variants and/or SPINK1 N34S (combined 22.9% vs. 16.1%, OR 1.92, 95% C.I. 1.26–2.94, P=0.0023) and with alcoholic vs. non-alcoholic CP etiologies (20.8% vs. 12.4%, OR=1.9, 95% CI=1.30–2.79, P=0.0009). Alcohol and smoking generally occurred together, but the frequency of CTRC c.180 T in CP, but not RAP, was higher among never drinkers–ever smokers (22.2%) than ever drinker–never smokers (10.8%), suggesting that smoking rather than alcohol may be the driving factor in this association.

CONCLUSIONS:

The common CTRC variant c.180T acts as disease modifier that promotes progression from RAP to CP, especially in patients with CFTR or SPINK1 variants, alcohol, or smoking.

Tetraspanin CD9 is involved in pancreatic damage during caerulein-induced acute pancreatitis in mice

OBJECTIVE

Pancreatic acinar cell necrosis and subsequent inflammatory response aggravate acute pancreatitis (AP). Tetraspanin CD9 has been reported to mediate inflammatory signaling by regulating molecular organization at the cell surface. This study aimed to investigate the role of CD9 in caerulein-induced AP (CIP) in mice.

METHODS

The expression of CD9 was detected in CIP in mice in vivo and cholecystokinin (CCK)/recombinant mouse tumor necrosis factor (rmTNF)-α induced pancreatic acinar cell death in vitro by quantitative real-time polymerase chain reaction, Western blot and immunofluorescence. The roles of CD9 in pancreatic acinar cell death and inflammatory response were further studied through the deletion of CD9 expression using small interfering RNA (siRNA).

RESULTS

CD9 was markedly upregulated in pancreatic tissues in mice during the early onset of CIP and was located mainly at the pancreatic acinar cell surface, which was associated with pancreatic damage. Additionally, incubation with CCK or rmTNF-α directly increased the expression of CD9 in isolated mice pancreatic acinar cells in vitro. The deletion of CD9 expression partially reversed both pancreatic acinar cell death induced by CCK and mRNA levels of proinflammatory cytokines produced by damaged acinar cells.

CONCLUSION

These results indicate that increased CD9 expression may be involved in pancreatic injury, possibly via the promotion of cytokine expressions in CIP in mice.

A super TLR agonist to improve efficacy of dendritic cell vaccine in induction of anti-HCV immunity

Persistent infections caused by pathogens such as hepatitis C virus are major human diseases with limited or suboptimal prophylactic and therapeutic options. Given the critical role of dendritic cell (DC) in inducing immune responses, DC vaccination is an attractive means to prevent and control the occurrence and persistence of the infections. However, DCs are built-in with inherent negative regulation mechanisms which attenuate their immune stimulatory activity and lead to their ineffectiveness in clinical application. In this study, we developed a super DC stimulant that consists of a modified, secretory Toll-like Receptor (TLR)-5 ligand and an inhibitor of the negative regulator, suppressor of cytokine sinaling-1 (SOCS1). We found that expressing the super stimulant in DCs is drastically more potent and persistent than using the commonly used DC stimuli to enhance the level and duration of inflammatory cytokine production by both murine and human DCs. Moreover, the DCs expressing the super stimulant are more potent to provoke both cellular and humoral immune responses against hepatitis C virus (HCV) antigen in vivo. Thus, the strategy capable of triggering and sustaining proinflammatory status of DCs may be used to boost efficiency of DC vaccine in preventing and combating the persistent infection of HCV or other chronic viruses.

Redox signaling and histone acetylation in acute pancreatitis

Histone acetylation via CBP/p300 coordinates the expression of proinflammatory cytokines in the activation phase of inflammation, particularly through mitogen-activated protein kinases (MAPKs), nuclear factor-κB (NF-κB), and signal transducers and activators of transcription (STAT) pathways. In contrast, histone deacetylases (HDACs) and protein phosphatases are mainly involved in the attenuation phase of inflammation. The role of reactive oxygen species (ROS) in the inflammatory cascade is much more important than expected. Mitochondrial ROS act as signal-transducing molecules that trigger proinflammatory cytokine production via inflammasome-independent and inflammasome-dependent pathways. The major source of ROS in acute inflammation seems to be NADPH oxidases, whereas NF-κB, protein phosphatases, and HDACs are the major targets of ROS and redox signaling in this process. There is a cross-talk between oxidative stress and proinflammatory cytokines through serine/threonine protein phosphatases, tyrosine protein phosphatases, and MAPKs that greatly contributes to amplification of the uncontrolled inflammatory cascade and tissue injury in acute pancreatitis. Chromatin remodeling during induction of proinflammatory genes would depend primarily on phosphorylation of transcription factors and their binding to gene promoters together with recruitment of histone acetyltransferases. PP2A should be considered a key modulator of the inflammatory cascade in acute pancreatitis through the ERK/NF-κB pathway and histone acetylation.

Inhibition of the JAK/STAT3 signaling pathway reduces acute renal injury in rats with experimental severe acute pancreatitis

AIM: To investigate whether inhibition of the JAK/STAT3 signaling pathway exerts a protective effect against acute renal injury in rats with experimental severe acute pancreatitis (SAP) and to explore the potential mechanisms involved.

METHODS: Fifty-six male SD rats were randomly divided into three groups: control group, SAP group and JAK inhibitor (AG490)-treated group. A rat model of SAP was reproduced by retrograde infusion of 4% sodium taurocholate into the biliopancreatic duct. The levels of serum amylase (AMY), creatinine (Cr) and urea nitrogen (BUN) were measured. The concentrations of IL-6 and TNF-α were determined by ELISA. Pathological changes in the pancreas and kidney were evaluated. The expression of STAT3 and p-STAT3 in the kidney was determined by Western blotting.

RESULTS: Compared to the normal control group, pancreatic and renal injuries were gradually aggravated with disease progression, and serum levels of IL-6, TNF-α AMY, Cr and BUN and expression of STAT3 and p-STAT3 increased significantly (all P < 0.01) in the SAP group. In the AG490-treated group, all the above parameters improved significantly in comparison with those in the SAP model group (all P < 0.01).

CONCLUSION: The JAK/STAT3 signaling pathway is involved in the development of renal injury in rats with SAP, and inhibition of this pathway can significantly inhibit excessive STAT3 activation, which may in turn effectively reduce renal injury.

Effects of down-regulation of microRNA-23a on TNF-α-induced endothelial cell apoptosis through caspase-dependent pathways

AIMS

Endothelial cell injury induced by inflammatory factors plays a critical role in the pathogenesis of numerous vascular diseases. MicroRNAs are well known to be implicated in cell proliferation and apoptosis in inflammatory responses; however, it remains to be determined whether microRNAs are associated with tumour necrosis factor (TNF)-α-mediated endothelial cell injury. The aim of the present study was to investigate the role of microRNAs in TNF-α-induced endothelial cell apoptosis.

METHODS AND RESULTS

Microarrays were used to analyse the global expression of microRNAs in TNF-α-stimulated human primary endothelial cells. Expression profiles of the microRNAs were verified using qRT-PCR. After TNF-α treatment, 12 miRNAs were dramatically up-regulated and nine were down-regulated. LNA-anti-miR-23a and pre-miR-23a were found to modulate one of the markedly down-regulated miRNAs, miR-23a, which could in turn increase or attenuate TNF-α-induced endothelial cell apoptosis. Bioinformatics analysis suggested that caspase-7 and serine/threonine kinase 4 are potential targets of miR-23a. LNA-anti-miR-23a enhanced but pre-miR-23a inhibited the activation of caspase-7, serine/threonine kinase 4, and its related signalling caspase-3 after TNF-α treatment; however, neither pre-miR-23a nor LNA-anti-miR-23a had an effect on TNF-α-induced Bcl-2 activation.

CONCLUSION

Our results suggest that miR-23a may be involved in TNF-α-induced endothelial cell apoptosis through regulation of the caspase-7 and serine/threonine kinase 4-caspase-3 pathways.

Epigenetic transcriptional regulation of the growth arrest-specific gene 1 (Gas1) in hepatic cell proliferation at mononucleosomal resolution

BACKGROUND

Gas1 (growth arrest-specific 1) gene is known to inhibit cell proliferation in a variety of models, but its possible implication in regulating quiescence in adult tissues has not been examined to date. The knowledge of how Gas1 is regulated in quiescence may contribute to understand the deregulation occurring in neoplastic diseases.

METHODOLOGY/PRINCIPAL FINDINGS

Gas1 expression has been studied in quiescent murine liver and during the naturally synchronized cell proliferation after partial hepatectomy. Chromatin immunoprecipitation at nucleosomal resolution (Nuc-ChIP) has been used to carry out the study preserving the in vivo conditions. Transcription has been assessed at real time by quantifying the presence of RNA polymerase II in coding regions (RNApol-ChIP). It has been found that Gas1 is expressed not only in quiescent liver but also at the cell cycle G(1)/S transition. The latter expression peak had not been previously reported. Two nucleosomes, flanking a nucleosome-free region, are positioned close to the transcription start site. Both nucleosomes slide in going from the active to the inactive state and vice versa. Nuc-ChIP analysis of the acquisition of histone epigenetic marks show distinctive features in both active states: H3K9ac and H3K4me2 are characteristic of transcription in G(0) and H4R3me2 in G(1)/S transition. Sequential-ChIP analysis revealed that the "repressing" mark H3K9me2 colocalize with several "activating" marks at nucleosome N-1 when Gas1 is actively transcribed suggesting a greater plasticity of epigenetic marks than proposed until now. The recruitment of chromatin-remodeling or modifying complexes also displayed distinct characteristics in quiescence and the G(1)/S transition.

CONCLUSIONS/SIGNIFICANCE

The finding that Gas1 is transcribed at the G(1)/S transition suggests that the gene may exert a novel function during cell proliferation. Transcription of this gene is modulated by specific "activating" and "repressing" epigenetic marks, and by chromatin remodeling and histone modifying complexes recruitment, at specific nucleosomes in Gas1 promoter.

Going up in flames: necrotic cell injury and inflammatory diseases

Recent evidence indicates that cell death can be induced through multiple mechanisms. Strikingly, the same death signal can often induce apoptotic as well as non-apoptotic cell death. For instance, inhibition of caspases often converts an apoptotic stimulus to one that causes necrosis. Because a dedicated molecular circuitry distinct from that controlling apoptosis is required for necrotic cell injury, terms such as "programmed necrosis" or "necroptosis" have been used to distinguish stimulus-dependent necrosis from those induced by non-specific traumas (e.g., heat shock) or secondary necrosis induced as a consequence of apoptosis. In several experimental models, programmed necrosis/necroptosis has been shown to be a crucial control point for pathogen- or injury-induced inflammation. In this review, we will discuss the molecular mechanisms that regulate programmed necrosis/necroptosis and its biological significance in pathogen infections, drug-induced cell injury, and trauma-induced tissue damage.

Naturally produced outer membrane vesicles from Pseudomonas aeruginosa elicit a potent innate immune response via combined sensing of both lipopolysaccharide and protein components

Pseudomonas aeruginosa is a prevalent opportunistic human pathogen that, like other Gram-negative pathogens, secretes outer membrane vesicles. Vesicles are complex entities composed of a subset of envelope lipid and protein components that have been observed to interact with and be internalized by host cells. This study characterized the inflammatory responses to naturally produced P. aeruginosa vesicles and determined the contribution of vesicle Toll-like receptor (TLR) ligands and vesicle proteins to that response. Analysis of macrophage responses to purified vesicles by real-time PCR and enzyme-linked immunosorbent assay identified proinflammatory cytokines upregulated by vesicles. Intact vesicles were shown to elicit a profoundly greater inflammatory response than the response to purified lipopolysaccharide (LPS). Both TLR ligands LPS and flagellin contributed to specific vesicle cytokine responses, whereas the CpG DNA content of vesicles did not. Neutralization of LPS sensing demonstrated that macrophage responses to the protein composition of vesicles required the adjuvantlike activity of LPS to elicit strain specific responses. Protease treatment to remove proteins from the vesicle surface resulted in decreased interleukin-6 and tumor necrosis factor alpha production, indicating that the production of these specific cytokines may be linked to macrophage recognition of vesicle proteins. Confocal microscopy of vesicle uptake by macrophages revealed that vesicle LPS allows for binding to macrophage surfaces, whereas vesicle protein content is required for internalization. These data demonstrate that macrophage sensing of both LPS and protein components of outer membrane vesicles combine to produce a bacterial strain-specific response that is distinct from those triggered by individual, purified vesicle components.