Novel HMGB1-inhibiting therapeutic agents for experimental sepsis. Shock. 2009;32:348-357. [PMID: 19333143 DOI: 10.1097/SHK.0b013e3181a551bd]

Systemic high-mobility group box 1 administration suppresses skin inflammation by inducing an accumulation of PDGFRα(+) mesenchymal cells from bone marrow

High-mobility group box 1 (HMGB1) mobilizes platelet-derived growth factor receptor alpha-positive (PDGFRα⁺) mesenchymal cells from bone marrow (BM) into circulation. However, whether HMGB1-induced endogenous PDGFRα⁺ mesenchymal cells stimulate skin regeneration has been unclear. Here, we investigated the functions of the HMGB1/BM-PDGFRα⁺ mesenchymal cell axis in the regeneration of mouse skin grafts. We found that intravenous HMGB1 administration induced an accumulation of endogenous BM-PDGFRα⁺ mesenchymal cells followed by significant inflammatory suppression in the grafts. In contrast, mice with reduced BM-PDGFRα⁺ mesenchymal cells showed massive inflammation of the grafts compared to mice that had normal levels of these cells even after HMGB1 administration, suggesting that BM-PDGFRα⁺ mesenchymal cells contribute to the HMGB1-induced anti-inflammatory effect. We also found that intravenously administered HMGB1 augmented the local migration of BM-PDGFRα⁺ mesenchymal cells from circulation to skin graft by inducing the expression of CXCR4, an SDF-1 receptor, on these cells. Finally, we showed the therapeutic activity of the HMGB1/BM-PDGFRα⁺ mesenchymal cell axis in an allergic contact dermatitis model. The results illustrated the contribution of the HMGB1/BM-PDGFRα⁺ mesenchymal cell axis in suppressing the inflammation of injured/inflamed skin. These findings may provide future perspectives on the use of HMGB1-based medicines for intractable diseases.

CO2 pneumoperitoneum preserves β-arrestin 2 content and reduces high mobility group box-1 (HMGB-1) expression in an animal model of peritonitis

Laparoscopy (LS) has been shown to decrease the inflammatory sequelae of endotoxemia. β-arrestin 2 plays an important function in signal transduction pathway of TLR4. High mobility group box-1 (HMGB-1) is involved in the delayed systemic inflammatory response. We investigated the effects of CO2 insufflation on liver, lung, and kidney expression of both β-arrestin 2 and HMGB-1 during sepsis. Cecal ligation and puncture (CLP) was performed in male rats and 6 h later the animals were randomly assigned to receive a CO2 pneumoperitoneum or laparotomy. Animals were euthanized; liver, lung, and kidney were removed for the evaluation of β-arrestin 2 and HMGB-1 expression. Immunohistochemical detection of myeloperoxidase (MPO) was investigated in lung and liver and bacterial load was determined in the peritoneal fluid. CO2 pneumoperitoneum reduced peritoneal bacterial load, increased the expression of β-arrestin 2, and blunted the expression of the potent proinflammatory HMGB-1 in liver, lung, and kidney compared with laparotomy. Liver and lung MPO was markedly reduced in rats subjected to LS compared with laparotomy. We believe that CO2 exerts an early protective effect by reducing bacterial load and likely toll-like receptor activation which in turn leads to a preserved β-arrestin 2 expression and a reduced HMGB-1 expression.

CO2 pneumoperitoneum preserves β-arrestin 2 content and reduces high mobility group box-1 (HMGB-1) expression in an animal model of peritonitis

Laparoscopy (LS) has been shown to decrease the inflammatory sequelae of endotoxemia. β-arrestin 2 plays an important function in signal transduction pathway of TLR4. High mobility group box-1 (HMGB-1) is involved in the delayed systemic inflammatory response. We investigated the effects of CO₂ insufflation on liver, lung, and kidney expression of both β-arrestin 2 and HMGB-1 during sepsis. Cecal ligation and puncture (CLP) was performed in male rats and 6 h later the animals were randomly assigned to receive a CO₂ pneumoperitoneum or laparotomy. Animals were euthanized; liver, lung, and kidney were removed for the evaluation of β-arrestin 2 and HMGB-1 expression. Immunohistochemical detection of myeloperoxidase (MPO) was investigated in lung and liver and bacterial load was determined in the peritoneal fluid. CO₂ pneumoperitoneum reduced peritoneal bacterial load, increased the expression of β-arrestin 2, and blunted the expression of the potent proinflammatory HMGB-1 in liver, lung, and kidney compared with laparotomy. Liver and lung MPO was markedly reduced in rats subjected to LS compared with laparotomy. We believe that CO₂ exerts an early protective effect by reducing bacterial load and likely toll-like receptor activation which in turn leads to a preserved β-arrestin 2 expression and a reduced HMGB-1 expression.

High mobility group box 1 induced human lung myofibroblasts differentiation and enhanced migration by activation of MMP-9

High mobility group box 1 (HMGB1) is a nuclear protein that involves the binding with DNA and influences chromatin regulation and transcription. HMGB1 is also a cytokine that can activate monocytes and neutrophils involved in inflammation. In this study, we investigated the role of HMGB1 on cellular activation using human fibroblast cell line WI-38. After treatment with 1, 10, and 100 ng/mL of HMGB1 for 24 h, we did not find obviously cytotoxicity and cellular proliferation of WI-38 cells by MTT and BrdU incorporation assay, respectively. However, we found that treatment with 10 and 100 ng/mL of HMGB1 induced the differentiation of lung fibroblasts into myofibroblasts and myofibroblasts showed higher migration ability through activation of matrix metalloproteinase (MMP)-9 activation. To delineate the mechanism underlying HMGB1-induced cellular migration, we examined HMGB1-induced mitogen activated protein kinases (MAPKs), including extracellular signal related kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen activated protein kinase (p38) phosphorylation, as well as nuclear factor (NF)-κB nuclear translocation. Using specific inhibitors and shRNAs of protein kinases, we observed that repression of ERK, JNK, p38, and NF-κB all inhibited HMGB1-induced cellular differentiation, migration and MMP-9 activation in WI-38 cells. In addition, knocking down of RAGE but not TLR2 and TLR4 by shRNAs attenuated HMGB1-induced myofibroblast differentiation and migration. In conclusion, our study demonstrated that HMGB1 induced lung fibroblasts’ differentiation into myofibroblasts and enhanced cell migration through induction of MMP-9 activation and the RAGE-MAPK and NF-κB interaction signaling pathways. Targeting HMGB1 might be a potential therapeutic approach for alleviation of airway remodeling seen in chronic airway inflammatory diseases.

The HMGB1 protein sensitizes colon carcinoma cells to cell death triggered by pro-apoptotic agents

The HMGB1 protein has multiple functions in tumor biology and can act both as a transcription factor and as a cytokine. HMGB1 is released during cell death, and in our previous studies we demonstrated that HMGB1 induces a distinct, necrosis-like cell death in glioblastoma. In epithelial malignant tumors such as colorectal cancer (CRC), the HMGB1-dependent effects show cross-talk with apoptotic signal transduction. Treatment of CRC cells with low concentrations of recombinant HMGB1 results in dose-dependent cytotoxicity which is morphologically characterized by the formation of giant mitochondria and does not share features of apoptosis. HMGB1-triggered cell death is associated with intracellular ROS release, and overexpression of Bcl-2 blocks both the increase of ROS as well as HMGB1-dependent cell death. Importantly, treatment with recombinant HMGB1 or overexpression of endogenous HMGB1 strongly sensitizes CRC cells to the cytotoxic activity of the pro-apoptotic death ligand TRAIL as well as the small molecule Bcl-2 family inhibitor ABT‑737. Moreover, treatment of CRC cells with TRAIL or ABT‑737 induces a release of endogenous HMGB1 into the extracellular space, and preincubation with glycyrrhizin, an HMGB1 inhibitor, significantly inhibits induction of cell death by TRAIL and ABT‑737, suggesting that HMGB1 functionally contributes to the execution of cell death triggered by pro-apoptotic agents. Finally, we investigated the expression of HMGB1 in human CRC tumor samples and found that loss of HMGB1 expression is associated with a more aggressive phenotype and a more advanced stage of disease in patients with CRC. Altogether, our findings demonstrate a functional link between cytotoxic signaling cascades triggered by HMGB1 and pro-apoptotic agents leading to an HMGB1-dependent sensitization to CRC cell death. Thus, a further evaluation of recombinant HMGB1 as part of an experimental combination treatment of CRC seems warranted.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Prevalence and clinical significance of sterile intra-amniotic inflammation in patients with preterm labor and intact membranes

PROBLEM

Inflammation and infection play a major role in preterm birth. The purpose of this study was to (i) determine the prevalence and clinical significance of sterile intra-amniotic inflammation and (ii) examine the relationship between amniotic fluid (AF) concentrations of high mobility group box-1 (HMGB1) and the interval from amniocentesis to delivery in patients with sterile intra-amniotic inflammation.

METHOD OF STUDY

AF samples obtained from 135 women with preterm labor and intact membranes were analyzed using cultivation techniques as well as broad-range PCR and mass spectrometry (PCR/ESI-MS). Sterile intra-amniotic inflammation was defined when patients with negative AF cultures and without evidence of microbial footprints had intra-amniotic inflammation (AF interleukin-6 ≥ 2.6 ng/mL).

RESULTS

(i) The frequency of sterile intra-amniotic inflammation was significantly greater than that of microbial-associated intra-amniotic inflammation [26% (35/135) versus 11% (15/135); (P = 0.005)], (ii) patients with sterile intra-amniotic inflammation delivered at comparable gestational ages had similar rates of acute placental inflammation and adverse neonatal outcomes as patients with microbial-associated intra-amniotic inflammation, and (iii) patients with sterile intra-amniotic inflammation and high AF concentrations of HMGB1 (≥8.55 ng/mL) delivered earlier than those with low AF concentrations of HMGB1 (P = 0.02).

CONCLUSION

(i) Sterile intra-amniotic inflammation is more frequent than microbial-associated intra-amniotic inflammation, and (ii) we propose that danger signals participate in sterile intra-amniotic inflammation in the setting of preterm labor.

Thrombin inhibits HMGB1-mediated proinflammatory signaling responses when endothelial protein C receptor is occupied by its natural ligand

High mobility group box 1 (HMGB1) is involved in the pathogenesis of vascular diseases. Unlike activated protein C (APC), the activation of PAR-1 by thrombin is known to elicit proinflammatory responses. To determine whether the occupancy of EPCR by the Gla-domain of APC is responsible for the PAR-1-dependent antiinflammatory activity of the protease, we pretreated HUVECs with the PC zymogen and then activated PAR-1 with thrombin. It was found that thrombin downregulates the HMGB1-mediated induction of both TNF-α and IL-6 and inhibits the activation of both p38 MAPK and NF-κB in HUVECs pretreated with PC. Furthermore, thrombin inhibited HMGB1-mediated hyperpermeability and leukocyte adhesion/migration by inhibiting the expression of cell adhesion molecules in HUVECs if EPCR was occupied. Collectively, these results suggest the concept that thrombin can initiate proinflammatory responses in vascular endothelial cells through the activation of PAR-1 may not hold true for normal vessels expressing EPCR under in vivo conditions. [BMB Reports 2013; 46(11): 544-549]

Baicalein Inhibits HMGB1 Release and MMP-2/-9 Expression in Lipopolysaccharide-Induced Cardiac Hypertrophy

Myocardial dysfunction, a common complication after sepsis, significantly contributes to the death of patients with septic shock. In the search for potentially effective drugs to decrease mortality from sepsis, we investigated the cardioprotective effects of baicalein, a flavonoid present in the root of Scutellaria baicalensis, on lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production and matrix metalloproteinase-2 and -9 (MMP-2/-9) expression. We found that baicalein significantly attenuated LPS-induced cardiac hypertrophy and counteracted reactive oxygen species (ROS) generation in neonatal rat cardiomyocytes. In addition, pretreatment with baicalein inhibited LPS-induced early (e.g., tumor necrosis factor-α (TNF-α) and interleukin-6) and late (e.g., high mobility group box 1 (HMGB1) pro-inflammatory cytokine release, inducible nitric oxide synthase (iNOS) expression and NO production. Finally, baicalein also significantly down-regulated the expression of MMP-2/-9 and attenuated HMGB1 translocation from the nucleus to the cytoplasm. These results suggest that baicalein can protect cardiomyocytes from LPS-induced cardiac injury via the inhibition of ROS and inflammatory cytokine production. These cardioprotective effects are possibly mediated through the inhibition of the HMGB1 and MMP-2/-9 signaling pathways.

Sodium butyrate protects against toxin-induced acute liver failure in rats

BACKGROUND

Acute liver failure (ALF) is a serious clinical syndrome with high mortality. Sodium butyrate has been shown to alleviate organ injury in a wide variety of preclinical models of critical diseases. The aim of this study was to investigate the protective effect of sodium butyrate on ALF in rats.

METHODS

All rats were randomly divided into control, model and sodium butyrate treatment groups. Except the control group, the rats were induced ALF animal model by subcutaneous injection of human serum albumin+ D-galactosamine+lipopolysaccharide. After induction of ALF, the rats in the treatment group received sodium butyrate (500 mg/kg) at 12-hour or 24-hour time point. Fourty-eight hours after ALF induction, the animals were sacrificed and samples were harvested. Serum endotoxin, high mobility group box-1 (HMGB1), liver function parameters, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) were measured. The expression of HMGB1 and nuclear factor-kappa B (NF-kappaB) p65 protein in liver tissue was detected by Western blotting. The histological changes of liver and intestine were examined. The survival duration was also observed.

RESULTS

Serum endotoxin, alanine aminotransferase, HMGB1, TNF-alpha and IFN-gamma were significantly increased and the liver histology showed more severe histopathological injury in the model group compared with the control group (P<0.05). Compared to the model group, sodium butyrate treatment significantly improved the histopathological changes in the liver and intestine, reduced serum endotoxin and inflammatory cytokines, suppressed HMGB1 and NF-kappaB p65 proteins in liver tissue, and prolonged the survival duration regardless of treatment at 12 hours or 24 hours after induction of ALF (P<0.05).

CONCLUSIONS

Sodium butyrate protected the liver from toxin-induced ALF in rats. The mechanisms may be due to direct hepatoprotection and decreased intestinal permeability.

High mobility group box 1 in patients with 2009 pandemic H1N1 influenza-associated encephalopathy

BACKGROUND

Patients with 2009 pandemic H1N1 influenza-associated encephalopathy (pIE) have been reported in Japan. The most common clinical symptoms of this condition are seizures and progressive coma with high-grade fever. We previously highlighted the cytokine profile of pIE; our results suggest that proinflammatory cytokines play an important role in the pathogenesis. High mobility group box 1 (HMGB1) protein is a late mediator of inflammation or sepsis. However, there are few reports regarding the serum and cerebrospinal fluid (CSF) levels of HMGB1 in pIE patients.

METHODS

We measured serum and CSF levels of HMGB1 in the following: pIE patients with poor outcomes, pIE patients without neurological sequelae, influenza patients without pIE, and control subjects.

RESULTS

Serum HMGB1 levels were significantly higher in pIE patients with poor outcomes compared to those without neurological sequelae. In contrast, there was no difference in CSF HMGB1 levels among all groups. Regarding pIE patients, we found a significant positive correlation between HMGB1 levels and IL-6 in the serum but not in the CSF.

CONCLUSIONS

Our results suggest that HMGB1 protein may be involved in the pathogenesis of pIE and that a high serum, but not CSF, level of inflammatory cytokines plays an important role in the severity of pIE.

CD14 contributes to warm hepatic ischemia-reperfusion injury in mice

INTRODUCTION

Ischemia/reperfusion (I/R) of the liver contributes to the pathobiology of liver injury in transplantation, liver surgery, and hemorrhagic shock. Ischemia/reperfusion induces an inflammatory response that is driven, in part, by Toll-like receptor 4 (TLR) signaling. CD14 is known to participate in the function of TLR4. We hypothesized that CD14 would be involved in the pathobiology of warm hepatic I/R.

METHODS

Using a 70% liver inflow inclusion model, CD14 knockout and wild-type (WT) mice were subjected to 1-h warm ischemia followed by reperfusion. CD14 mRNA, circulating transaminase, interleukin 6, soluble CD14, and high-mobility group box 1 (HMGB1) levels were measured. CD14 neutralizing antibody or isotype control antibody was given before ischemia or reperfusion for CD14 blockade in WT mice. Recombinant HMGB1 was given before reperfusion in some experiments to test if liver injury worsens.

RESULTS

There was an upregulation of CD14 mRNA in reperfused livers together with increased soluble CD14 levels in the circulation. Compared with WT control mice, CD14 knockout mice had much lower alanine aminotransferase and interleukin 6 levels at 6 and 24 h following I/R, and much less liver necrosis by histology. TUNEL (terminal deoxynucleotidyl-transferase dUTP nick end labeling) staining displayed less apoptosis at 24 h in the absence of CD14. CD14 blockage by neutralizing antibody also attenuated liver injury and the inflammatory response in C57BL/6 mice following I/R, but did not provide additional protection to TLR4 mutant C3H/Hej mice. CD14 deficiency did not change circulating HMGB1 levels following I/R (6 h). A dose of recombinant HMGB1, which worsened hepatic injury when given before reperfusion in WT mice, did not increase liver damage in CD14-deficient mice.

CONCLUSIONS

CD14 is actively involved in hepatic I/R injury. Its deficiency or blockade ischemia attenuates liver injury and inflammatory response. CD14 mediates liver damage and inflammatory responses in the setting of warm hepatic I/R in mice.

Analysis of the released nuclear cytokine HMGB1 in human serum

A ubiquitous nuclear protein, the high-mobility group box 1 (HMGB1), is secreted by activated macrophages/monocytes and leaked passively from injured cells. HMGB1 functions as a mediator of infection- and injury-elicited inflammatory diseases. Here, we describe a semiquantitative immuno-blotting method to measure the released HMGB1 in human serum, in comparison with a commercially available HMGB1 ELISA technique.

Galectin-9 prolongs the survival of septic mice by expanding Tim-3-expressing natural killer T cells and PDCA-1+ CD11c+ macrophages

INTRODUCTION

Galectin-9 ameliorates various inflammatory conditions including autoimmune diseases by regulating T cell and macrophage/dendritic cell (DC) functions. However, the effect of galectin-9 on polymicrobial sepsis has not been assessed.

METHODS

We induced polymicrobial sepsis by cecal ligation and puncture (CLP) in mice. The survival rate was compared between galectin-9- and PBS-treated CLP mice. An ELISA was used to compare the levels of various cytokines in the plasma and culture supernatants. Fluorescence-activated cell sorting analysis was further performed to compare the frequencies of subpopulations of spleen cells.

RESULTS

Galectin-9 exhibited a protective effect in polymicrobial sepsis as demonstrated in galetin-9 transgenic mice and therapeutic galectin-9 administration. In contrast, such effect was not observed in nude mice, indicating the involvement of T cells in galectin-9-mediated survival prolongation. Galectin-9 decreased TNFα, IL-6, IL-10 and, high mobility group box 1 (HMGB1) and increased IL-15 and IL-17 plasma and spleen levels. Galectin-9 increased the frequencies of natural killer T (NKT) cells and PDCA-1+ CD11c+ macrophages (pDC-like macrophages) but did not change the frequency of CD4 or CD8 T cells, γδT cells or conventional DC. As expected, galectin-9 decreased the frequency of Tim-3+ CD4 T cells, most likely Th1 and Th17 cells. Intriguingly, many spleen NK1.1+ NKT cells and pDC-like macrophages expressed Tim-3. Galectin-9 increased the frequency of Tim-3-expressing NK1.1+ NKT cells and pDC-like macrophages. Galectin-9 further increased IL-17+ NK1.1+ NKT cells.

CONCLUSION

These data suggest that galectin-9 exerts therapeutic effects on polymicrobial sepsis, possibly by expanding NKT cells and pDC-like macrophages and by modulating the production of early and late proinflammatory cytokines.

Identification of pharmacological modulators of HMGB1-induced inflammatory response by cell-based screening

High mobility group box 1 (HMGB1), a highly conserved, ubiquitous protein, is released into the circulation during sterile inflammation (e.g. arthritis, trauma) and circulatory shock. It participates in the pathogenesis of delayed inflammatory responses and organ dysfunction. While several molecules have been identified that modulate the release of HMGB1, less attention has been paid to identify pharmacological inhibitors of the downstream inflammatory processes elicited by HMGB1 (C23-C45 disulfide C106 thiol form). In the current study, a cell-based medium-throughput screening of a 5000+ compound focused library of clinical drugs and drug-like compounds was performed in murine RAW264.7 macrophages, in order to identify modulators of HMGB1-induced tumor-necrosis factor alpha (TNFα) production. Clinically used drugs that suppressed HMGB1-induced TNFα production included glucocorticoids, beta agonists, and the anti-HIV compound indinavir. A re-screen of the NIH clinical compound library identified beta-agonists and various intracellular cAMP enhancers as compounds that potentiate the inhibitory effect of glucocorticoids on HMGB1-induced TNFα production. The molecular pathways involved in this synergistic anti-inflammatory effect are related, at least in part, to inhibition of TNFα mRNA synthesis via a synergistic suppression of ERK/IκB activation. Inhibition of TNFα production by prednisolone+salbutamol pretreatment was also confirmed in vivo in mice subjected to HMGB1 injection; this effect was more pronounced than the effect of either of the agents administered separately. The current study unveils several drug-like modulators of HMGB1-mediated inflammatory responses and offers pharmacological directions for the therapeutic suppression of inflammatory responses in HMGB1-dependent diseases.

Nuclear antigens and auto/alloantibody responses: friend or foe in transplant immunology

In addition to cellular immune responses, humoral immune responses, mediated by natural antibodies, autoantibodies, and alloantibodies, have increasingly been recognized as causes of organ transplant rejection. In our previous studies, we have demonstrated the induction of antinuclear antibodies against histone H1 and high-mobility group box 1 (HMGB1), in both experimental and clinical liver transplant tolerance. The active induction of antinuclear antibodies is usually an undesirable phenomenon, but it is often observed after liver transplantation. However, the release of nuclear antigens and its suppression by neutralizing antibodies are proposed to be important in the initiation and regulation of immune responses. In this review article, we summarize the current understanding of nuclear antigens and corresponding antinuclear regulatory antibodies (Abregs) on infection, injury, inflammation, transplant rejection, and tolerance induction and discuss the significance of nuclear antigens as diagnostic and therapeutic targets.

Ursolic acid attenuates lipopolysaccharide-induced acute lung injury in a mouse model

AIM

To assess whether ursolic acid (UA) can attenuate lipopolysachharide (LPS)-induced acute lung injury and improve the survival time in a mouse model.

MATERIALS & METHODS

The mice were challenged with LPS and survival time was monitored from 0-96 h after LPS treatment. TNF-α, IL-6, IL-1β, HMGB1, nitric oxide (NO) and IL-10 concentration in serum were measured by ELISA. Myeloperoxidase activity, malondialdehyde, lung wet:dry weight ratio and lung permeability in lung tissues were detected. NF-κB, HMGB1 and inducible NO synthase in the lungs were detected by western blot.

RESULTS

UA markedly rescued lethality, improved survival time and lung pathological changes, inhibited TNF-α, IL-6, IL-1β, HMGB1 and NO, and increased IL-10 expression. In addition, UA can also decrease myeloperoxidase, malondialdehyde, lung wet:dry weight ratio and lung permeability. UA attenuated NF-κB, HMGB1 and inducible NO synthase protein expression in the lungs.

CONCLUSION

The results suggest that UA is capable of improving survival time and LPS-induced acute lung injury. UA has a potentially therapeutic role in septic shock.

Human recombinant protein C for severe sepsis and septic shock in adult and paediatric patients

BACKGROUND

Sepsis is a common and frequently fatal condition. Human recombinant activated protein C (APC) has been introduced to reduce the high risk of death associated with severe sepsis or septic shock. This systematic review is an update of a Cochrane review originally published in 2007.

OBJECTIVES

We assessed the benefits and harms of APC for patients with severe sepsis or septic shock.

SEARCH METHODS

We searched CENTRAL (The Cochrane Library 2012, Issue 6); MEDLINE (2010 to June 2012); EMBASE (2010 to June 2012); BIOSIS (1965 to June 2012); CINAHL (1982 to June 2012) and LILACS (1982 to June 2012). There was no language restriction.

SELECTION CRITERIA

We included randomized clinical trials assessing the effects of APC for severe sepsis or septic shock in adults and children. We excluded studies on neonates. We considered all-cause mortality at day 28 and at the end of study follow up, and hospital mortality as the primary outcomes.

DATA COLLECTION AND ANALYSIS

We independently performed trial selection, risk of bias assessment, and data extraction in duplicate. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

We identified one new randomized clinical trial in this update which includes six randomized clinical trials involving 6781 participants in total, five randomized clinical trials in adult (N = 6307) and one randomized clinical trial in paediatric (N = 474) participants. All trials had high risk of bias and were sponsored by the pharmaceutical industry. APC compared with placebo did not significantly affect all-cause mortality at day 28 compared with placebo (780/3435 (22.7%) versus 767/3346 (22.9%); RR 1.00, 95% confidence interval (CI) 0.86 to 1.16; I(2) = 56%). APC did not significantly affect in-hospital mortality (393/1767 (22.2%) versus 379/1710 (22.1%); RR 1.01, 95% CI 0.87 to 1.16; I(2) = 20%). APC was associated with an increased risk of serious bleeding (113/3424 (3.3%) versus 74/3343 (2.2%); RR 1.45, 95% CI 1.08 to 1.94; I(2) = 0%). APC did not significantly affect serious adverse events (463/3334 (13.9%) versus 439/3302 (13.2%); RR 1.04, 95% CI 0.92 to 1.18; I(2) = 0%). Trial sequential analyses showed that more trials do not seem to be needed for reliable conclusions regarding these outcomes.

AUTHORS' CONCLUSIONS

This updated review found no evidence suggesting that APC should be used for treating patients with severe sepsis or septic shock. APC seems to be associated with a higher risk of bleeding. The drug company behind APC, Eli Lilly, has announced the discontinuation of all ongoing clinical trials using this drug for treating patients with severe sepsis or septic shock. APC should not be used for sepsis or septic shock outside randomized clinical trials.

High-mobility group box-1 induces proinflammatory cytokines production of Kupffer cells through TLRs-dependent signaling pathway after burn injury

Kupffer cells (KCs) were a significant source of cytokine release during the early stage of severe burns. High mobility group box protein 1 (HMGB1) was recently identified as a new type of proinflammatory cytokine. The ability of HMGB1 to generate inflammatory responses after burn trauma has not been well characterized. KCs were isolated from sham animals and rats with a 30% full-thickness burn, and then were stimulated with increasing concentrations of HMGB1. The levels of Tumor necrosis factor (TNF)-α and interleukin (IL)-1β in culture supernatant were measured by enzyme-linked immunosorbent assay. Northern blot analysis was performed to detect the expressions of TNF-α and IL-1β mRNAs. The activities of p38 MAPK and JNK (by Western blot analysis) as well as NF-κB (by EMSA) in KCs were also examined. As a result, HMGB1 in vitro upregulated expressions of TNF-α and IL-1β of KCs in a dose-dependent manner, and HMGB1 promoted KCs from burn rats to produce significantly more TNF-α and IL-1β proteins than those from sham animals. After harvested from burn rats, KCs were pre-incubated with anti-TLR2 or anti-TLR4 antibody prior to HMGB1 administration. HMGB1 exposure not only significantly increased expressions of TNF-α and IL-1β mRNAs in KCs from burn rats, but also enhanced activities of p38 MAPK, JNK and NF-κB. However, these upregulation events were all reduced by pre-incubation with anti-TLR2 or anti-TLR4 antibody. These results indicate that HMGB1 induces proinflammatory cytokines production of KCs after sever burn injury, and this process might be largely dependent on TLRs-dependent MAPKs/NF-κB signal pathway.

High-mobility group box-1 induces proinflammatory cytokines production of Kupffer cells through TLRs-dependent signaling pathway after burn injury

Kupffer cells (KCs) were a significant source of cytokine release during the early stage of severe burns. High mobility group box protein 1 (HMGB1) was recently identified as a new type of proinflammatory cytokine. The ability of HMGB1 to generate inflammatory responses after burn trauma has not been well characterized. KCs were isolated from sham animals and rats with a 30% full-thickness burn, and then were stimulated with increasing concentrations of HMGB1. The levels of Tumor necrosis factor (TNF)-α and interleukin (IL)-1β in culture supernatant were measured by enzyme-linked immunosorbent assay. Northern blot analysis was performed to detect the expressions of TNF-α and IL-1β mRNAs. The activities of p38 MAPK and JNK (by Western blot analysis) as well as NF-κB (by EMSA) in KCs were also examined. As a result, HMGB1 in vitro upregulated expressions of TNF-α and IL-1β of KCs in a dose-dependent manner, and HMGB1 promoted KCs from burn rats to produce significantly more TNF-α and IL-1β proteins than those from sham animals. After harvested from burn rats, KCs were pre-incubated with anti-TLR2 or anti-TLR4 antibody prior to HMGB1 administration. HMGB1 exposure not only significantly increased expressions of TNF-α and IL-1β mRNAs in KCs from burn rats, but also enhanced activities of p38 MAPK, JNK and NF-κB. However, these upregulation events were all reduced by pre-incubation with anti-TLR2 or anti-TLR4 antibody. These results indicate that HMGB1 induces proinflammatory cytokines production of KCs after sever burn injury, and this process might be largely dependent on TLRs-dependent MAPKs/NF-κB signal pathway.

Ethyl pyruvate protects against experimental acute-on-chronic liver failure in rats

AIM: To investigate the protective effects of ethyl pyruvate (EP) on acute-on-chronic liver failure (ACLF) in rats.

METHODS: An ACLF model was established in rats, and animals were randomly divided into normal, model and EP treatment groups. The rats in EP treatment group received EP (40 mg/kg) at 3 h, 6 h, 12 h and 24 h after induction of ACLF. Serum endotoxin, high mobility group box-1 (HMGB1), alanine transaminase (ALT), tumor necrosis factor-α (TNF-α), interferon-α (IFN-γ), interleukin (IL)-10 and IL-18 levels, changes of liver histology and HMGB1 expressions in liver tissues were detected at 48 h after induction of ACLF. The effects of EP on the survival of ACLF rats were also observed.

RESULTS: Serum levels of endotoxin (0.394 ± 0.066 EU/mL vs 0.086 ± 0.017 EU/mL, P < 0.001), HMGB1 (35.42 ± 10.86 μg/L vs 2.14 ± 0.27 μg/L, P < 0.001), ALT (8415.87 ± 3567.54 IU/L vs 38.64 ± 8.82 IU/L, P < 0.001), TNF-α (190.77 ± 12.34 ng/L vs 124.40 ± 4.12 ng/L, P < 0.001), IFN-γ (715.38 ± 86.03 ng/L vs 398.66 ± 32.91 ng/L, P < 0.001), IL-10 (6.85 ± 0.64 ng/L vs 3.49 ± 0.24 ng/L, P < 0.001) and IL-18 (85.19 ± 3.49 ng/L vs 55.38 ± 1.25 ng/L, P < 0.001) were significantly increased, and liver tissues presented severe pathological injury in the model group compared with the normal group. However, EP administration significantly improved hepatic histopathology and reduced the serum levels of endotoxin (0.155 ± 0.045 EU/mL vs 0.394 ± 0.066 EU/mL, P < 0.001) and inflammatory cytokines (11.13 ± 2.58 μg/L vs 35.42 ± 10.86 μg/L for HMGB1, 3512.86 ± 972.67 IU/L vs 8415.87 ± 3567.54 IU/L for ALT, 128.55 ± 5.76 ng/L vs 190.77 ± 12.34 ng/L for TNF-α, 438.16 ± 38.10 ng/L vs 715.38 ± 86.03 ng/L for IFN-γ, 3.55 ± 0.36 ng/L vs 6.85 ± 0.64 ng/L for IL-10, and 60.35 ± 1.63 ng/L vs 85.19 ± 3.49 ng/L for IL-18, respectively, P < 0.001), and the levels of HMGB1 in liver tissues regardless of treatment time after induction of ACLF. EP treatment at the four time points prolonged the median survival time of ACLF rats (60 h) to 162 h, 120 h, 102 h and 78 h, respectively (χ² = 41.17, P < 0.0001).

CONCLUSION: EP administration can protect against ACLF in rats, and is a potential and novel therapeutic agent for severe liver injury.

Role of high mobility group box 1 in inflammatory disease: focus on sepsis

High mobility group box 1 (HMGB1) is a highly conserved, ubiquitous protein present in the nuclei and cytoplasm of nearly all cell types. In response to infection or injury, HMGB1 is actively secreted by innate immune cells and/or released passively by injured or damaged cells. Thus, serum and tissue levels of HMGB1 are elevated during infection, and especially during sepsis. Sepsis is a systemic inflammatory response to disease and the most severe complication of infections, and HMGB1 acts as a potent proinflammatory cytokine and is involved in delayed endotoxin lethality and sepsis. Furthermore, the targeting of HMGB1 with antibodies or specific antagonists has been found to have protective effects in established preclinical inflammatory disease models, including models of lethal endotoxemia and sepsis. In the present study, emerging evidence supporting the notion that extracellular HMGB1 acts as a proinflammatory danger signal is reviewed, and the potential therapeutic effects of a wide array of HMGB1 inhibitors agents in sepsis and ischemic injury are discussed.

Biomarkers and molecular probes for cell death imaging and targeted therapeutics

Cell death is a critically important biological process. Disruption of homeostasis, either by excessive or deficient cell death, is a hallmark of many pathological conditions. Recent research advances have greatly increased our molecular understanding of cell death and its role in a range of diseases and therapeutic treatments. Central to these ongoing research and clinical efforts is the need for imaging technologies that can locate and identify cell death in a wide array of in vitro and in vivo biomedical samples with varied spatiotemporal requirements. This review article summarizes community efforts over the past five years to identify useful biomarkers for dead and dying cells, and to develop molecular probes that target these biomarkers for optical, radionuclear, or magnetic resonance imaging. Apoptosis biomarkers are classified as either intracellular (caspase enzymes, mitochondrial membrane potential, cytosolic proteins) or extracellular (plasma membrane phospholipids, membrane potential, surface exposed histones). Necrosis, autophagy, and senescence biomarkers are described, as well as unexplored cell death biomarkers. The article discusses possible chemotherapeutic and theranostic strategies, and concludes with a summary of current challenges and expected eventual rewards of clinical cell death imaging.

Ethyl pyruvate induces heme oxygenase-1 through p38 mitogen-activated protein kinase activation by depletion of glutathione in RAW 264.7 cells and improves survival in septic animals

AIMS

We investigated the molecular mechanism by which ethyl pyruvate (EP) induces heme oxygenase-1 (HO-1) in RAW 264.7 cells and its effect on survival rate in cecal ligation and puncture (CLP)-induced wild-type (WT) and HO-1 knockout (HO-1(-/-)) septic mice.

RESULTS

EP induced HO-1 in a dose- and time-dependent manner, which was mediated through p38 mitogen-activated protein kinase (MAPK) and NF-E2-related factor 2 (Nrf2) signaling cascade in RAW 264.7 cells. EP significantly inhibited the lipopolysaccharide (LPS)-stimulated inducible nitric oxide synthase (iNOS) expression and high-mobility group box 1 (HMGB1) release in RAW 264.7 cells. The inhibitory effect of EP on LPS-stimulated iNOS expression and HMGB1 release was reversed by transfection with siHO-1RNA in RAW 264.7 cells, but EP failed to reduce them in HO-1(-/-) peritoneal macrophages treated with LPS. Moreover, treatment of cells with glutathione ethyl ester (GSH-Et), SB203580 (p38 MAPK inhibitor), siHO-1, or p38-siRNA transfection inhibited anti-inflammatory effect of EP. Interestingly, both HO-1 induction and phosphorylation of p38 by EP were reversed by GSH-Et, and antioxidant redox element-luciferase activity by EP was reversed by SB203580 in LPS-activated cells. EP increased survival and decreased serum HMGB1 in CLP-WT mice, whereas it did not increase survival or decrease circulating HMGB1 in HO-1(-/-) CLP-mice.

INNOVATION AND CONCLUSION

Our work provides new insights into the understanding the molecular mechanism by showing that EP induces HO-1 through a p38 MAPK- and NRF2-dependent pathway by decreasing GSH cellular levels. We conclude that EP inhibits proinflammatory response to LPS in macrophages and increases survival in CLP-induced septic mice by upregulation of HO-1 level, in which p38 MAPK and Nrf2 play an important role.

Presence of preexisting antibodies mediates survival in sepsis

Sepsis is one of the leading causes of death in hospitals worldwide. Even with optimal therapy, severe sepsis results in 50% mortality, indicating variability in the response of individuals towards treatment. We hypothesize that the presence of preexisting antibodies present in the blood before the onset of sepsis induced by cecal ligation and puncture (CLP) in mice accounts for the differences in their survival. A plasma-enhanced killing (PEK) assay was performed to calculate the PEK capacity of plasma, that is, the ability of plasma to augment polymorphonuclear neutrophil killing of bacteria. Plasma-enhanced killing was calculated as PEK = [1 / log (N)] × 100, where N = number of surviving bacteria; a higher PEK indicated better bacterial killing. A range of PEK in plasma collected from mice before CLP was observed, documenting individual differences in bacterial killing capacity. Mortality was predicted based on plasma IL-6 levels at 24 h after CLP. Mice predicted to die (Die-P) had a lower PEK (<14) and higher peritoneal bacterial counts at 24 h after sepsis compared with those predicted to live (Live-P) with a PEK of greater than 16. Mice with PEK of less than 14 were 3.1 times more likely to die compared with the group with PEK of greater than 16. To understand the mechanism of defense conferred by the preexisting antibodies, binding of IgM or IgG to enteric bacteria was documented by flow cytometry. To determine the relative contribution of IgM or IgG, the immunoglobulins were specifically immunodepleted from the naive plasma samples and the PEK of the depleted plasma measured. Compared with naive plasma, depletion of IgM had no effect on the PEK. However, depletion of IgG increased PEK, suggesting that an inhibitory IgG binds to antigenic sites on bacteria preventing optimal opsonization of the bacteria. These data demonstrate that, before CLP, circulating inhibitory IgG antibodies exist that prevent bacterial killing by polymorphonuclear neutrophils in a CLP model of sepsis.

Human recombinant activated protein C for severe sepsis

BACKGROUND

Sepsis is a common and frequently fatal condition. Human recombinant activated protein C (APC) has been used to reduce the high rate of death by severe sepsis or septic shock. This is an update of a Cochrane review (originally published in 2007 and updated in 2008).

OBJECTIVES

We assessed the clinical effectiveness and safety of APC for the treatment of patients with severe sepsis or septic shock.

SEARCH METHODS

For this updated review we searched CENTRAL (The Cochrane Library 2010, Issue 6); MEDLINE (1966 to June 2010); EMBASE (1980 to July 1, 2010); BIOSIS (1965 to July 1, 2010); CINAHL (1982 to 16 June 2010) and LILACS (1982 to 16 June 2010). There was no language restriction.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing the effects of APC for severe sepsis in adults and children. We excluded studies on neonates. We considered all-cause mortality at day 28, at the end of study follow up, and hospital mortality as the primary outcomes.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

We identified one new RCT in this update. We included a total of five RCTs involving 5101 participants. For 28-day mortality, APC did not reduce the risk of death in adult participants with severe sepsis (pooled RR 0.97, 95% confidence interval (CI) 0.78 to 1.22; P = 0.82, I(2) = 68%). APC use was associated with an increased risk of bleeding (RR 1.47, 95% CI 1.09 to 2.00; P = 0.01, I(2) = 0%). In paediatric patients, APC did not reduce the risk of death (RR 0.98, 95% CI 0.66 to 1.46; P = 0.93). Although the included trials had no major limitations most of them modified their original completion or recruitment protocols.

AUTHORS' CONCLUSIONS

This updated review found no evidence suggesting that APC should be used for treating patients with severe sepsis or septic shock. Additionally, APC is associated with a higher risk of bleeding. Unless additional RCTs provide evidence of a treatment effect, policy-makers, clinicians and academics should not promote the use of APC.Warning: On October 25th 2011, the European Medicines Agency issued a press release on the worldwide withdrawal of Xigris (activated protein C / drotrecogin alfa) from the market by Eli Lilly due to lack of beneficial effect on 28-day mortality in the PROWESS-SHOCK study. Furthermore, Eli Lily has announced the discontinuation of all other ongoing clinical trials. The final results of the PROWESS-SHOCK study are expected to be published in 2012. This systematic review will be updated when results of the PROWESS-SHOCK or other trials are published.

Effect of ethyl pyruvate on high mobility group box 1 protein expression and serum cytokine levels in rats with experimental colitis

AIM: To evaluate the effect of ethyl pyruvate (EP) on the expression of high mobility group box 1 protein (HMGB1) and cytokine levels in rats with experimental colitis.

METHODS: Thirty-six rats were randomly and equally divided into three groups: blank control group, model control group, and EP treatment group. Experimental colitis was induced in mice by giving dextran sodium sulfate (DSS). The impact of EP on disease activity index (DAI) and histopathological score (HPS) in experimental colitis was evaluated. The expression of HMGB1 mRNA and protein was measured by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot, respectively. Serum levels of TNF-a and IL-6 were determined by ELISA.

RESULTS: DAI and HPS were higher in the model control group than in the blank control group (7.20 ± 2.28 vs 0.45 ± 0.16, 13.60 ± 0.72 vs 6.4 ± 0.85, both P < 0.01). The expression levels of HMGB1 mRNA and protein were significantly higher in the model control group than in the blank control group (both P < 0.01). The levels of TNF-a and IL-6 in serum were also significantly higher in the model control group than in the blank control group (190.40 ± 24.55 vs 43.65 ± 8.79, 238.75 ± 26.58 vs 74.3 ± 7.92, both P < 0.01). Compared to the model control group, EP inhibited the body weight loss and occurrence of diarrhea as well as rectal bleeding in rats. DAI, HPS, TNF-a, IL-6 as well as the expression levels of HMGB1 mRNA and protein in the EP treatment group were significantly lower than those in the model control group (all P < 0.05).

CONCLUSION: The expression of HMGB1 is up-regulated in experimental colitis, which is closely related with the development and progression of experimental colitis. EP exerts significant therapeutic effects on DSS-induced experimental colitis in rats possibly by down-regulating the expression of HMGB1 and ameliorating the levels of inflammatory factors.

Peroxisome proliferator-activated receptor γ agonist troglitazone inhibits high mobility group box 1 expression in endothelial cells via suppressing transcriptional activity of nuclear factor κB and activator protein 1

High mobility group box 1 (HMGB1), a delayed mediator of proinflammatory cytokines, could initiate and amplify inflammatory responses to infection, injury, and other inflammatory stimuli, and it has emerged as a potential therapeutic target for inflammatory diseases. The overexpression of HMGB1 in endothelial cells has been proved to contribute to the development of these diseases. Because many proinflammatory cytokines expression were suppressed by thiazolidinediones (TZDs), agonists for nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ), whether TZDs can inhibit HMGB1 expression and function is of great interest, however, it remains unknown. Herein, we provide evidence that PPARγ agonist troglitazone, a member of the TZD class, modulates HMGB1 expression in the endothelial cell line EA.hy926 and propose a potential mechanism for that. Results from polymerase chain reaction experiments revealed that PPARγ is expressed in EA.hy926 cells, and it can be activated by troglitazone. Troglitazone inhibited the basal and LPS-stimulated HMGB1 expression at the mRNA level and protein level. A luciferase reporter assay showed that troglitazone inhibited not only the transcriptional activation of the HMGB1 promoter but also activities of heterologous promoters driven by nuclear factor κB (NF-κB) or activator protein 1 (AP-1) response elements. Altogether, these data suggest that NF-κB and AP-1 may participate in the inhibitory effect on HMGB1 transcription induced by troglitazone. Activation of PPARγ by troglitazone is effective for HMGB1 inhibition via suppressing NF-κB and AP-1 transcriptional activity in endothelial cells, which provides a new potential strategy to suppress excessive HMGB1 in inflammatory diseases.

In vitro evaluation of high mobility group box 1 protein removal with various membranes for continuous hemofiltration

The high mobility group box 1 protein (HMGB1) is an alarmin that plays an important role in sepsis and has been recognized as a promising target with a wide therapeutic window; however, no drugs and devices are currently in practical use. We hypothesized that hemofilters composed of porous membranes or cytokine-adsorbing membranes could remove HMGB1 from the blood. We performed experimental hemofiltration in vitro using four types of hemofilters composed of different membranes specifically designed for continuous hemofiltration. The test solution was a 1000-mL substitution fluid containing 100 µg of HMGB1 and 35 g of bovine serum albumin. Experimental hemofiltration was conducted for 360 min in a closed loop circulation system. Among the four membranes, surface-treated polyacrylonitrile (AN69ST) showed the highest capacity to adsorb HMGB1; it adsorbed nearly 100 µg of HMGB1 in the initial 60 min and showed a markedly high clearance rate (60.8 ± 5.0 mL/min) at 15 min. The polymethylmethacrylate membrane had half of the adsorption capacity of the AN69ST membrane. Although the highest sieving coefficient for HMGB1 was obtained with the high cut-off polyarylethersulfone membrane, which correlated with a constant filtrate clearance rate, albumin loss was observed. However, no such removal of both HMGB1 and albumin was observed with the polysulfone membrane and tubing. We conclude that continuous hemofiltration using the AN69ST membrane is a promising approach for HMGB1-related sepsis.

Damage-associated molecular patterns (DAMPs) in preterm labor with intact membranes and preterm PROM: a study of the alarmin HMGB1

OBJECTIVE

Preterm parturition is a syndrome caused by multiple etiologies. Although intra-amniotic infection is causally linked with intrauterine inflammation and the onset of preterm labor, other patients have preterm labor in the absence of demonstrable infection. It is now clear that inflammation may be elicited by activation of the Damage-Associated Molecular Patterns (DAMPs), which include pathogen-associated molecular patterns (PAMPs) as well as "alarmins" (endogenous molecules that signal tissue and cellular damage). A prototypic alarmin is high-mobility group box 1 (HMGB1) protein, capable of inducing inflammation and tissue repair when it reaches the extracellular environment. HMGB1 is a late mediator of sepsis, and blockade of HMGB1 activity reduces mortality in an animal model of endotoxemia, even if administered late during the course of the disorder. The objectives of this study were to: (1) determine whether intra-amniotic infection/inflammation (IAI) is associated with changes in amniotic fluid concentrations of HMGB1; and (2) localize immunoreactivity of HMGB1 in the fetal membranes and umbilical cord of patients with chorioamnionitis.

METHODS

Amniotic fluid samples were collected from the following groups: (1) preterm labor with intact membranes (PTL) with (n=42) and without IAI (n=84); and (2) preterm prelabor rupture of membranes (PROM) with (n=38) and without IAI (n=35). IAI was defined as either a positive amniotic fluid culture or amniotic fluid concentration of interleukin-6 (IL-6) ≥ 2.6ng/mL. HMGB1 concentrations in amniotic fluid were determined by ELISA. Immunofluorescence staining for HMGB1 was performed in the fetal membranes and umbilical cord of pregnancies with acute chorioamnionitis.

RESULTS

(1) Amniotic fluid HMGB1 concentrations were higher in patients with IAI than in those without IAI in both the PTL and preterm PROM groups (PTL IAI: median 3.1 ng/mL vs. without IAI; median 0.98 ng/mL; p <0.001; and preterm PROM with IAI median 7.3 ng/mL vs. without IAI median 2.6 ng/mL; p=0.002); (2) patients with preterm PROM without IAI had a higher median amniotic fluid HMGB1 concentration than those with PTL and intact membranes without IAI (p <0.001); and (3) HMGB1 was immunolocalized to amnion epithelial cells and stromal cells in the Wharton's jelly (prominent in the nuclei and cytoplasm). Myofibroblasts and macrophages of the chorioamniotic connective tissue layer and infiltrating neutrophils showed diffuse cytoplasmic HMGB1 immunoreactivity.

CONCLUSIONS

(1) intra-amniotic infection/inflammation is associated with elevated amniotic fluid HMGB1 concentrations regardless of membrane status; (2) preterm PROM was associated with a higher amniotic fluid HMGB1 concentration than PTL with intact membranes, suggesting that rupture of membranes is associated with an elevation of alarmins; (3) immunoreactive HMGB1 was localized to amnion epithelial cells, Wharton's jelly and cells involved in the innate immune response; and (4) we propose that HMGB1 released from stress or injured cells into amniotic fluid may be responsible, in part, for intra-amniotic inflammation due to non-microbial insults.

Serum concentrations of complement anaphylatoxins and proinflammatory mediators in patients with 2009 H1N1 influenza

Anaphylatoxins (C5a, C4a, and C3a) are fragments of activated complement and are leading mediators of the inflammatory response for controlling viral infection. However, an excessive response may increase the severity of infectious diseases. Serum concentrations of proinflammatory mediators, including cytokines, high-mobility group box 1 and anaphylatoxins, were measured in pediatric 2009 H1N1 influenza patients in order to investigate the pathology of this new influenza. The concentrations of all three anaphylatoxins were significantly enhanced by 2009 H1N1 influenza infection. However, there were no significant differences in anaphylatoxin concentrations between 2009 H1N1 influenza patients with and without severe complications during the early stages of the disease. C3a concentrations dropped significantly during the recovery phase, whereas there were no significant differences between the acute and recovery phases in C5a and C4a concentrations. There was a correlation between C5a and IL-2. C4a was associated with IL-1ra, eotaxin, MCP-1, PDGFbb, and VEGF. C3a was correlated with IL-2 and IFN-γ. Taken together, these findings indicate that complement activation occurs in patients infected with 2009 H1N1 influenza virus and demonstrate that anaphylatoxins are involved in increased production of proinflammatory mediators in this new influenza.

Sepsis: Something old, something new, and a systems view

Sepsis is a clinical syndrome characterized by a multisystem response to a microbial pathogenic insult consisting of a mosaic of interconnected biochemical, cellular, and organ-organ interaction networks. A central thread that connects these responses is inflammation that, while attempting to defend the body and prevent further harm, causes further damage through the feed-forward, proinflammatory effects of damage-associated molecular pattern molecules. In this review, we address the epidemiology and current definitions of sepsis and focus specifically on the biologic cascades that comprise the inflammatory response to sepsis. We suggest that attempts to improve clinical outcomes by targeting specific components of this network have been unsuccessful due to the lack of an integrative, predictive, and individualized systems-based approach to define the time-varying, multidimensional state of the patient. We highlight the translational impact of computational modeling and other complex systems approaches as applied to sepsis, including in silico clinical trials, patient-specific models, and complexity-based assessments of physiology.

Human recombinant activated protein C for severe sepsis

BACKGROUND

Sepsis is a common and frequently fatal condition. Human recombinant activated protein C (APC) has been used to reduce the high rate of death by severe sepsis or septic shock. This is an update of a Cochrane review (originally published in 2007 and updated in 2008).

OBJECTIVES

We assessed the clinical effectiveness and safety of APC for the treatment of patients with severe sepsis or septic shock.

SEARCH STRATEGY

For this updated review we searched CENTRAL (The Cochrane Library 2010, Issue 6); MEDLINE (1966 to June 2010); EMBASE (1980 to July 1, 2010); BIOSIS (1965 to July 1, 2010); CINAHL (1982 to 16 June 2010) and LILACS (1982 to 16 June 2010). There was no language restriction.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing the effects of APC for severe sepsis in adults and children. We excluded studies on neonates. We considered all-cause mortality at day 28, at the end of study follow up, and hospital mortality as the primary outcomes.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction. We estimated relative risks (RR) for dichotomous outcomes. We measured statistical heterogeneity using the I(2) statistic. We used a random-effects model.

MAIN RESULTS

We identified one new RCT in this update. We included a total of five RCTs involving 5101 participants. For 28-day mortality, APC did not reduce the risk of death in adult participants with severe sepsis (pooled RR 0.97, 95% confidence interval (CI) 0.78 to 1.22; P = 0.82, I(2) = 68%). APC use was associated with an increased risk of bleeding (RR 1.47, 95% CI 1.09 to 2.00; P = 0.01, I(2) = 0%). In paediatric patients, APC did not reduce the risk of death (RR 0.98, 95% CI 0.66 to 1.46; P = 0.93). Although the included trials had no major limitations most of them modified their original completion or recruitment protocols.

AUTHORS' CONCLUSIONS

This updated review found no evidence suggesting that APC should be used for treating patients with severe sepsis or septic shock. Additionally, APC is associated with a higher risk of bleeding. Unless additional RCTs provide evidence of a treatment effect, policy-makers, clinicians and academics should not promote the use of APC.

High-mobility group box 1, oxidative stress, and disease

Oxidative stress and associated reactive oxygen species can modify lipids, proteins, carbohydrates, and nucleic acids, and induce the mitochondrial permeability transition, providing a signal leading to the induction of autophagy, apoptosis, and necrosis. High-mobility group box 1 (HMGB1) protein, a chromatin-binding nuclear protein and damage-associated molecular pattern molecule, is integral to oxidative stress and downstream apoptosis or survival. Accumulation of HMGB1 at sites of oxidative DNA damage can lead to repair of the DNA. As a redox-sensitive protein, HMGB1 contains three cysteines (Cys23, 45, and 106). In the setting of oxidative stress, it can form a Cys23-Cys45 disulfide bond; a role for oxidative homo- or heterodimerization through the Cys106 has been suggested for some of its biologic activities. HMGB1 causes activation of nicotinamide adenine dinucleotide phosphate oxidase and increased reactive oxygen species production in neutrophils. Reduced and oxidized HMGB1 have different roles in extracellular signaling and regulation of immune responses, mediated by signaling through the receptor for advanced glycation end products and/or Toll-like receptors. Antioxidants such as ethyl pyruvate, quercetin, green tea, N-acetylcysteine, and curcumin are protective in the setting of experimental infection/sepsis and injury including ischemia-reperfusion, partly through attenuating HMGB1 release and systemic accumulation.

EGCG stimulates autophagy and reduces cytoplasmic HMGB1 levels in endotoxin-stimulated macrophages

Historically, consumption of Green tea (Camellia sinensis) has been associated with health benefits against multiple diseases including cancer, atherosclerosis and cardiovascular disorders. Emerging evidence has suggested a pathogenic role for HMGB1, a newly identified "late" mediator of lethal systemic inflammation, in the aforementioned diseases. Here we demonstrated that a major ingredient of Green tea, EGCG, was internalized into HMGB1-containing LC3-positive cytoplasmic vesicles (likely autophagosomes) in macrophages, and induced HMGB1 aggregation in a time-dependent manner. Furthermore, EGCG stimulated LC3-II production and autophagosome formation, and inhibited LPS-induced HMGB1 up-regulation and extracellular release. The EGCG-mediated HMGB1 inhibitory effects were diminished by inhibition of class III phosphatidylinositol-3 kinase (with 3-methyladenine) or knockdown of an essential autophagy-regulating protein, beclin-1. Moreover, the EGCG-mediated protection against lethal sepsis was partly impaired by co-administration of an autophagy inhibitor, chloroquine. Taken together, the present study has suggested a possibility that EGCG inhibits HMGB1 release by stimulating its autophagic degradation.

A hepatic protein, fetuin-A, occupies a protective role in lethal systemic inflammation

Background

A liver-derived protein, fetuin-A, was first purified from calf fetal serum in 1944, but its potential role in lethal systemic inflammation was previously unknown. This study aims to delineate the molecular mechanisms underlying the regulation of hepatic fetuin-A expression during lethal systemic inflammation (LSI), and investigated whether alterations of fetuin-A levels affect animal survival, and influence systemic accumulation of a late mediator, HMGB1.

Methods and Findings

LSI was induced by endotoxemia or cecal ligation and puncture (CLP) in fetuin-A knock-out or wild-type mice, and animal survival rates were compared. Murine peritoneal macrophages were challenged with exogenous (endotoxin) or endogenous (IFN-γ) stimuli in the absence or presence of fetuin-A, and HMGB1 expression and release was assessed. Circulating fetuin-A levels were decreased in a time-dependent manner, starting between 26 h, reaching a nadir around 24–48 h, and returning towards base-line approximately 72 h post onset of endotoxemia or sepsis. These dynamic changes were mirrored by an early cytokine IFN-γ-mediated inhibition (up to 50–70%) of hepatic fetuin-A expression. Disruption of fetuin-A expression rendered animals more susceptible to LSI, whereas supplementation of fetuin-A (20–100 mg/kg) dose-dependently increased animal survival rates. The protection was associated with a significant reduction in systemic HMGB1 accumulation in vivo, and parallel inhibition of IFN-γ- or LPS-induced HMGB1 release in vitro.

Conclusions

These experimental data suggest that fetuin-A is protective against lethal systemic inflammation partly by inhibiting active HMGB1 release.

[New therapeutic alternatives for severe sepsis in the critical patient. A review]

BACKGROUND

Despite efforts to establish uniform protocols for the management of severe sepsis, this condition continues to have high morbidity and mortality. This is due, among other factors, to the many barriers for the development of the protocols and the application time. That is why new therapeutic measures are continuing to be investigated and developed.

OBJECTIVE

To review the literature on the new and future therapeutic alternatives available in the management of sepsis in critically ill patients. DATA SOURCE AND SEARCH METHOD: A search was made for articles consistent with evidence- based medicine guidelines published between 2004 and 2009 in different databases (Cochrane Plus Library, National Guideline Clearinghouse, Clinical Evidence, REMI and PubMed) and the NIH Clinical Trails database (ClinicalTrials.gov) using the TRIP meta-search engine.

STUDY SELECTION

A total of 357 documents were retrieved, selecting 48 of which included systematic reviews, meta-analyses, clinical practice guidelines, structured abstracts of original articles, and clinical trials. The selection criteria followed the peer review process.

DATA EXTRACTION

Data were extracted by two independent reviewers.

CONCLUSIONS

Based on the 2004-2009 study period, sufficient evidence was not obtained to make further recommendations on the treatment of sepsis. Although the abundant evidence needed to suggest the utility of these therapeutic measures, inhaled nitric oxide, statins, and immunoglobulins are probably good options for the adjuvant treatment of sepsis. However, we must wait for the results of different ongoing clinical trials on new treatment modalities. Stem cells and gene therapy will probably emerge as novel therapies in the future.

Alpha7 nicotinic receptors as novel therapeutic targets for inflammation-based diseases

In recent years the etiopathology of a number of debilitating diseases such as type 2 diabetes, arthritis, atherosclerosis, psoriasis, asthma, cystic fibrosis, sepsis, and ulcerative colitis has increasingly been linked to runaway cytokine-mediated inflammation. Cytokine-based therapeutic agents play a major role in the treatment of these diseases. However, the temporospatial changes in various cytokines are still poorly understood and attempts to date have focused on the inhibition of specific cytokines such as TNF-α. As an alternative approach, a number of preclinical studies have confirmed the therapeutic potential of targeting alpha7 nicotinic acetylcholine receptor-mediated anti-inflammatory effects through modulation of proinflammatory cytokines. This "cholinergic anti-inflammatory pathway" modulates the immune system through cholinergic mechanisms that act on alpha7 receptors expressed on macrophages and immune cells. If the preclinical findings translate into human efficacy this approach could potentially provide new therapies for treating a broad array of intractable diseases and conditions with inflammatory components.

The C-terminal acidic tail is responsible for the inhibitory effects of HMGB1 on efferocytosis

HMGB1 was described originally as a nuclear protein involved in DNA binding and transcriptional regulation. However, HMGB1 also has an extracellular role as a potent mediator of inflammation and can diminish the uptake of apoptotic cells by phagocytes, a process called efferocytosis. To explore the mechanism responsible for the ability of HMGB1 to inhibit efferocytosis, we examined the role of the C-terminal acidic tail, a region of HMGB1 that has been shown to participate in specific intramolecular interactions. Deletion of the C-terminal tail abrogated the ability of HMGB1 to decrease murine macrophage ingestion of apoptotic neutrophils and to diminish phagocytosis-induced activation of Erk and Rac-1 in macrophages. We found that RAGE plays a major role in efferocytosis, and deletion of the C-terminal tail of HMGB1 prevented binding of HMGB1 to RAGE but not to other macrophage receptors involved in efferocytosis, such as the α(V)β(3) integrin. Whereas HMGB1 decreased ingestion of apoptotic neutrophils significantly by alveolar macrophages under in vivo conditions in the lungs of mice, this effect was lost when the C-terminal acidic tail was absent from HMGB1. These results demonstrate that the HMGB1 C-terminal tail is responsible for the inhibitory effects of HMGB1 on phagocytosis of apoptotic neutrophils under in vitro and in vivo conditions.

The RAGE axis in systemic inflammation, acute lung injury and myocardial dysfunction: an important therapeutic target?

BACKGROUND

The sepsis syndromes, frequently complicated by pulmonary and cardiac dysfunction, remain a major cause of death amongst the critically ill. Targeted therapies aimed at ameliorating the systemic inflammation that characterises the sepsis syndromes have largely yielded disappointing results in clinical trials. Whilst there are many potential reasons for lack of success of clinical trials, one possibility is that the pathways targeted, to date, are only modifiable very early in the course of the illness. More recent approaches have therefore attempted to identify pathways that could offer a wider therapeutic window, such as the receptor for advanced glycation end-products (RAGE) and its ligands.

PURPOSE

The objectives of this study were to review the evidence supporting the role of the RAGE axis in systemic inflammation and associated acute lung injury and myocardial dysfunction, to explore some of the problems and conflicts that these RAGE studies have raised and to consider strategies by which they might be resolved.

METHODS

MEDLINE was searched (1990-2010) and relevant literature collected and reviewed.

RESULTS AND CONCLUSION

RAGE is an inflammation-perpetuating receptor with a diverse range of ligands. Evidence supporting a role of the RAGE axis in the pathogenesis of systemic inflammation, ALI and myocardial dysfunction is compelling with numerous animal experiments showing the beneficial effects of inhibiting the RAGE axis. Despite a number of unanswered questions that need to be further addressed, the potential for inhibiting RAGE-mediated inflammation in humans undoubtedly exists.

High mobility group box 1 protein as a potential drug target for infection- and injury-elicited inflammation

In response to infection or injury, a ubiquitous nucleosomal protein, HMGB1 is secreted actively by innate immune cells, and / or released passively by injured/damaged cells. Subsequently, extracellular HMGB1 alerts, recruits, and activates various innate immune cells to sustain a rigorous inflammatory response. A growing number of HMGB1 inhibitors ranging from neutralizing antibodies, endogenous hormones, to medicinal herb-derived small molecule HMGB1 inhibitors (such as nicotine, glycyrrhizin, tanshinones, and EGCG) are proven protective against lethal infection and ischemic injury. Here we review emerging evidence that support extracellular HMGB1 as a proinflammatory alarmin(g) danger signal, and discuss a wide array of HMGB1 inhibitors as potential therapeutic agents for sepsis and ischemic injury.

Peripheral administration of fetuin-A attenuates early cerebral ischemic injury in rats

Cerebral ischemia-elicited inflammatory responses are driven by inflammatory mediators produced both by central (e.g., neurons and microglia) and infiltrating peripheral immune cells (e.g., macrophage/monocyte), and contribute to the evolution of tissue injury. A ubiquitous molecule, spermine, is released from injured cells, and counter-regulates release of various proinflammatory cytokines. However, the spermine-mediated anti-inflammatory activities are dependent on the availability of fetuin-A, a liver-derived negative acute-phase protein. Using an animal model of focal cerebral ischemia (i.e., permanent middle cerebral artery occlusion, MCAo), we found that levels of fetuin-A in the ischemic brain tissue were elevated in a time-dependent manner, starting between 2 and 6 h, peaking around 24 to 48 h, and returning to baseline 72 h after MCAo. When administered peripherally, exogenous fetuin-A gained entry across the BBB into the ischemic brain tissue, and dose dependently reduced brain infarct volume at 24 h after MCAo. Meanwhile, fetuin-A effectively attenuated (i) ischemia-induced HMGB1 depletion from the ischemic core; (ii) activation of centrally (e.g., microglia) and peripherally derived immune cells (e.g., macrophage/monocytes); and (iii) TNF production in ischemic brain tissue. Taken together, these experimental data suggest that fetuin-A protects against early cerebral ischemic injury partly by attenuating the brain inflammatory response.