New high mobility group box 1 assay system

Urinary and serum levels of high mobility group box 1

Background

High mobility group box 1 (HMGB-1) has been extensively studied in adults and to a certain extent in neonates as well. Clinical examination of neonates, especially unwell neonates soon after birth, should be minimally invasive.

Objective

This study aimed to investigate whether the urinary HMGB-1 level is comparable to the serum HMGB-1 level in neonates.

Methods

In all, 87 neonates (37.5 ± 2.9 weeks of gestation and a mean birth weight of 2588 ± 649 g) were enrolled. Of these, 53 were males and 34 were females. The umbilical cord blood and the first or second spontaneous voiding urine samples were stored, and the HMGB-1 level in the samples was measured.

Results

HMGB-1 was detected in all urinary samples. In these samples, we found acetylated HMGB-1 and may be devoid of nine residues at the N-terminal amino acid sequence. There was a significant correlation between the serum HMGB-1 level and urinary HMGB-1 level (r = 0.73, p < 0.001). Urinary HMGB1 levels in fetal neonatal asphyxia were significantly higher than those in healthy controls (p = 0.09).

Conclusion

Urinary excretion may be one of the metabolic pathways of HMGB-1. The urinary HMGB-1 level may be comparable to the serum HMGB-1 level in the early neonatal period.

Plasma HMGB1 levels and physical performance in ICU survivors

PURPOSE

Physical impairment after critical illness is recognized as a part of the post-intensive care syndrome (PICS). About one third of intensive care unit (ICU) survivors suffer from long-term physical disability, yet the underlying pathophysiological mechanisms remain poorly understood. The pro-inflammatory alarmin, high mobility group box 1 (HMGB1), promotes muscle dysfunction in experimental models, and HMGB1 stays elevated in some patients after ICU discharge. Accordingly, we investigated the relationship between HMGB1 plasma levels and physical performance in ICU survivors.

METHODS

Prospective cohort study of 100 ICU survivors from the general ICU at the Karolinska University Hospital, Sweden. Patients returned for follow up at 3 (58 patients) and 6 months (51 patients) after ICU discharge. Blood samples were collected, and a 6-minute walk test (6-MWT), a handgrip-strength test (HST), and a timed-stands test (TST) were performed.

RESULTS

Compared to reference values of the different physical tests, 16% of patients underperformed at all tests at 3 months and 12% at 6 months. All test results, except hand-grip strength left, improved significantly over the follow-up period (P < .05). There was no significant association between plasma HMGB1 levels at 3 and 6 months and scores on the three tests (6-MWT, TST, and HST) (P = .50-0.69).

CONCLUSION

In this follow-up study of ICU survivors, we found no significant association between plasma HMGB1 levels and physical performance. Additional follow-up studies of HMGB1 plasma levels and muscle function in ICU survivors are still warranted.

EDITORIAL COMMENT

HMGB-1, a marker of cell damage and activation, is known to increase in ICU patients. In study participants at 3- to 6-month post-ICU stay, HMGB-1 levels were still elevated, although no association to the primary outcome, physical performance, was found. Mechanisms for failure to recover physical performance post-ICU remain unclear, and investigations into cause of post-intensive care syndrome need to continue.

TRIAL REGISTRATIONS

ClinicalTrials.gov identifier NCT02914756.

High Mobility Group Box-1 (HMGB1): A Potential Target in Therapeutics

High mobility group box-1 (HMGB1) mainly belongs to the non-histone DNA-binding protein. It has been studied as a nuclear protein that is present in eukaryotic cells. From the HMG family, HMGB1 protein has been focused particularly for its pivotal role in several pathologies. HMGB-1 is considered as an essential facilitator in diseases such as sepsis, collagen disease, atherosclerosis, cancers, arthritis, acute lung injury, epilepsy, myocardial infarction, and local and systemic inflammation. Modulation of HMGB1 levels in the human body provides a way in the management of these diseases. Various strategies, such as HMGB1-receptor antagonists, inhibitors of its signalling pathway, antibodies, RNA inhibitors, vagus nerve stimulation etc. have been used to inhibit expression, release or activity of HMGB1. This review encompasses the role of HMGB1 in various pathologies and discusses its therapeutic potential in these pathologies.

Exploring the therapeutic promise of targeting HMGB1 in rheumatoid arthritis

High mobility group box-1 (HMGB1) protein is a diverse, single polypeptide moiety, present in mammalian eukaryotic cells. In response to stimuli, this nuclear protein is actively secreted in to the extracellular compartment or passively released by the necrotic cells, in order to mediate inflammatory responses, by forming complexes with IL-1α, IL-1β, LPS and other moieties, and binding to RAGE, TLR and other receptor ligands, initiating downstream, signaling processes. This molecule acts as a proinflammatory cytokine and contributes to the progression of diseases like, acute lung injury, autoimmune liver damage, graft rejection immune response and arthritis. Small concentrations of HMGB1 are released during apoptosis, which facilitates oxidative regulation on Cys106, and propagates immune inactivating tolerogenic signals in the body. The review portrays the role of HMGB1 in rheumatoid arthritis, evidently supported by pre-clinical and clinical investigations, demonstrating extensive HMGB1 expression in synovial tissue and fluid as well as serum, excessive expression of transduction receptor signaling molecules, bone remodeling and uncontrolled expression of bone destroying osteoclastogenesis, resulting in destruction of articular cartilage, bone deformation and synovial proliferation, alleviating the pathogenesis in RA disease. Moreover, the review highlights the therapeutic regime targeting HMGB1, facilitating inhibition of its actions and release into the extracellular compartment, to ameliorate the destructive events that prevail in rheumatoid arthritis.

Adsorption kinetics of high mobility group box 1 protein in a polyacrylonitrile hemofiltration membrane

The high mobility group box 1 protein (HMGB1) is recognized as a prototypical endogenous danger cytokine in sepsis. We previously reported that a polyacrylonitrile (AN69ST) membrane rapidly adsorbed HMGB1. Herein, an in vitro hemofiltration system was designed to assess the HMGB1 adsorption capacity, adsorption sites, and adsorption mechanism of the AN69ST membrane. HMGB1 was repeatedly added seven times during hemofiltration. A rapid decrease in circulating HMGB1 was observed after every addition with no sign of saturation. Presence of HMGB1 on the filter membrane was observed on both membrane surfaces and within the bulk layer using a high concentration of HMGB1 by immunoelectron microscopy. We hypothesized that the addition of heparin to the membrane surface or filtration rate would contribute to the adsorption mechanism. We could not measure the influence of heparin and filtration. Although the membrane was too large to saturate under the μg/mL HMGB1 conditions, our results show that the AN69ST membrane has a robust absorption capacity that could be used to treat sepsis.

Prognostic role of serum high mobility group box 1 concentration in cardiac surgery

Outcomes of cardiac surgery are influenced by systemic inflammation. High mobility group box 1 (HMGB1), a pivotal inflammatory mediator, plays a potential role as a prognostic biomarker in cardiovascular disease. The aim of this prospective, observational study was to investigate the relationship between serum HMGB1 concentrations and composite of morbidity endpoints in cardiac surgery. Arterial blood samples for HMGB1 measurement were collected from 250 patients after anaesthetic induction (baseline) and 1 h after weaning from cardiopulmonary bypass (post-CPB). The incidence of composite of morbidity endpoints (death, myocardial infarction, stroke, renal failure and prolonged ventilator care) was compared in relation to the tertile distribution of serum HMGB1 concentrations. The incidence of composite of morbidity endpoints was significantly different with respect to the tertile distribution of post-CPB HMGB1 concentrations (p = 0.005) only, and not to the baseline. Multivariable analysis revealed post-CPB HMGB1 concentration (OR, 1.072; p = 0.044), pre-operative creatinine and duration of CPB as independent risk factors of adverse outcome. Accounting for its prominent role in mediating sterile inflammation and its relation to detrimental outcome, HMGB1 measured 1 h after weaning from CPB would serve as a useful biomarker for accurate risk stratification in cardiac surgical patients and may guide tailored anti-inflammatory therapy.

HMGB1 and repair: focus on the heart

High-mobility group box 1 (HMGB1) is one of the most abundant proteins in eukaryotes and the best characterized damage-associated molecular pattern (DAMP). The biological activities of HMGB1 depend on its subcellular location, context and post-translational modifications. Inside the nucleus, HMGB1 is engaged in many DNA events such as DNA repair, transcription regulation and genome stability; in the cytoplasm, its main function is to regulate the autophagic flux while in the extracellular environment, it possesses more complicated functions and it is involved in a large variety of different processes such as inflammation, migration, invasion, proliferation, differentiation and tissue regeneration. Due to this pleiotropy, the role of HMGB1 has been vastly investigated in various pathological diseases and a large number of studies have explored its function in cardiovascular pathologies. However, in this contest, the precise mechanism of action of HMGB1 and its therapeutic potential are still very controversial since is debated whether HMGB1 is involved in tissue damage or plays a role in tissue repair and regeneration. The main focus of this review is to provide an overview of the effects of HMGB1 in different ischemic heart diseases and to discuss its functions in these pathological conditions.

Quantification of Serum High Mobility Group Box 1 by Liquid Chromatography/High-Resolution Mass Spectrometry: Implications for Its Role in Immunity, Inflammation, and Cancer

High mobility group box 1 (HMGB1) is a non-histone chromosomal protein, which can be secreted through a variety of pathways and bind to pattern recognition receptors to release pro-inflammatory cytokines. Previous studies have suggested that HMGB1 is upregulated in numerous inflammatory diseases and that it could be a biomarker for such diseases. However, these studies used immunoassay-based methods to analyze serum HMGB1. Autoantibodies to HMGB1 in serum are found in healthy control subjects as well as in patients with different diseases. HMGB1 also binds to haptoglobin, a highly abundant plasma protein. This means that antibodies used in immunoassays must compete with binding of HMGB1 to endogenous serum HMGB1 autoantibodies and haptoglobin. To overcome these potential problems, we developed and validated a specific and sensitive assay based on stable isotope dilution and immunopurification to quantify HMGB1 in plasma and serum using two-dimensional nano-ultra-high-performance liquid chromatography parallel reaction monitoring/high-resolution mass spectrometry. Using this assay, we found that serum HMGB1 in 24 healthy control subjects (6.0 ± 2.1 ng/mL) was above the mean concentration reported for 18 different diseases (5.4 ± 2.8 ng/mL) where the analyses were conducted with immunoassay methodology. In light of our finding, the role of HMGB1 in these diseases will have to be re-evaluated. The concentration of HMGB1 in citrated and EDTA-treated plasma from the same healthy control subjects was below the limit of detection of our assay (1 ng/mL), confirming that HMGB1 in serum arises when blood is allowed to clot. This means that future studies on the role of HMGB1 in vivo should be conducted on plasma rather than serum.

Multicenter study for brain/body hypothermia for hypoxic-ischemic encephalopathy: Changes in HMGB-1

BACKGROUND

We measured changes in the blood level of high-mobility group box-1 (HMGB-1) at 24 h intervals in neonates treated with brain/body hypothermia (body hypothermia therapy: BHT) for hypoxic-ischemic encephalopathy (HIE), to evaluate the usefulness of HMGB-1 level for determining outcomes.

METHODS

We studied 15 neonates with HIE who underwent BHT (BHT (+) group) and six neonates with HIE who did not (BHT (-) group). We recorded HMGB-1 changes at 24 h intervals, creatinine phosphokinase, and the resistance index of the anterior cerebral artery. Magnetic resonance imaging (MRI) was used to determine short-term outcome.

RESULT

Baseline HMGB-1 was significantly higher in the BHT (+) group than in the BHT (-) group. Thereafter, HMGB-1 in the BHT (+) group significantly decreased at 24 h intervals, reaching the reference range by 2 days of age. In the BHT (+) group, when patients were classified into clinically significant neurological disorder due to HIE (+) and (-) according to MRI, the neurological disorder (+) group had higher mean HMGB-1.

CONCLUSIONS

In HIE, HMGB-1 differs according to the presence of BHT, suggesting that HMGB-1 measurement soon after birth might be useful for determining BHT necessity and short-term outcome.

Intravenous dendritic cell administration enhances suppression of lung metastasis induced by carbon-ion irradiation

Carbon-ion radiotherapy (CIRT) is an advanced radiotherapy and has achieved good local control, even in tumors that are resistant to conventional photon beam radiotherapy (PBRT). However, distant metastasis control is an important issue. Recently, the combination of radiotherapy and immunotherapy has attracted the attention. In immunotherapy, dendritic cells (DCs) play a pivotal role in the anti-tumor immune system. However, the mechanisms underlying the combination therapy of DCs and radiotherapy have been unclear. In the present study, we evaluated anti-metastatic effects of this combination therapy, focused on the irradiation type and the route of DC administration, using a mouse model. C3H/He mice bearing NR-S1 cells were treated with CIRT or PBRT, using biologically equivalent doses. Subsequently, DCs were administered intratumorally (IT) or intravenously (IV). IV and IT DC administrations combined with CIRT to the local tumor, but not alone, significantly suppressed pulmonary metastasis, whereas the combination of DCs with PBRT suppressed metastasis at a relatively higher dose. Additionally, the anti-metastatic effect was greater in IV DC administration compared with in IT DC administration in both CIRT and PBRT. The expression levels of CD40 and IL-12 in DCs were significantly increased after co-culturing with CIRT-treated NR-S1 cells. In addition, IV administration of those co-cultured DCs significantly suppressed pulmonary metastasis. Furthermore, ecto-calreticulin levels from CIRT-treated NR-S1 cells significantly increased compared with those of a PBRT-treated tumor. Taken together, these results suggest that local CIRT combined with IV DCs augments an immunogenicity of the tumor cells by ecto-calreticulin expression and the maturation of DCs to stimulate anti-tumor immunity to decrease lung metastases.

Postoperative changes in high mobility group box 1 levels after colorectal cancer surgery

Objective To investigate the potential use of high mobility group box 1 (HMGB1) as a marker for the surgical course following surgery for colorectal cancer (CRC). Methods Patients with advanced CRC undergoing open colorectal surgery who did not develop postsurgical complications were enrolled in the study. Blood samples were taken preoperatively and at 1 day, 1 week and 3 weeks after surgery for the measurement of the white blood cell count, serum C-reactive protein, serum amyloid A and HMGB1. Results Data from 21 patients were analysed. HMGB1 levels changed significantly during the surgical course, increasing from a preoperative median of 6.8 ng/ml to 12.1 ng/ml at 1 day postoperatively, and then decreasing to 8.1 ng/ml at 1 week postoperatively and 4.0 ng/ml at 3 weeks postoperatively. These changes were similar to but were not completely correlated with the changes seen in the other markers. Conclusion Serum HMGB1 may be a potential marker to monitor the surgical course in patients undergoing surgery for CRC, although further studies are warranted before it can be introduced into routine clinical practice.

Elevated preoperative HMGB1 as predictor of myocardial injury post-percutaneous coronary intervention

In this study, we evaluated the impact of preoperative high mobility group box 1 (HMGB1) on myocardial injury post-percutaneous coronary intervention.We evaluated 302 consecutive patients who underwent percutaneous coronary intervention. They were divided into equal tertiles based on their preoperative HMGB1 levels. Creatine kinase-MB and troponin I levels were measured at baseline, 8- and 24-hours after the procedure, while clinical outcomes were followed up for 1 year.The occurrence of post-procedural myocardial injury was significantly higher in the tertile comprising of patients with elevated HMGB1 levels. Moreover, these patients showed significantly higher post-procedural peak values of creatine kinase-MB and troponin I in comparison to patients with lower HMGB1 levels. Event-free survival was significantly associated with HMGB1 levels, with worst event-free survival in patients with elevated HMGB1 levels.Elevated preoperative HMGB1 was a predictor of myocardial injury after percutaneous coronary intervention, and was associated with the worst clinical outcomes during 1-year follow up.

High-mobility group box-1 release into fetal circulation from umbilical cord tissue and amniotic epithelium in fetal ischemia

We report the case of a baby with low birthweight born by emergency caesarean section at 33 weeks 2 days' gestation due to placental abruption. High-mobility group box-1 (HMGB-1) and interleukin-17 concentration in the umbilical cord blood were high at 55.7 ng/mL and 50.7 pg/mL, respectively. On immunostaining of umbilical cord and amniotic epithelium, HMGB-1 was identified in the nuclei of vascular endothelial cells and cytoplasm of the surrounding cells in the umbilical cord. This suggests that, in the present case of placental abruption and subsequent ischemic placenta and fetus, the high level of HMGB-1 observed was due to the release of HMGB-1 into the umbilical cord blood from the vascular endothelial cells of the umbilical cord.

Critical role of RAGE and HMGB1 in inflammatory heart disease

Autoimmune response to cardiac troponin I (TnI) induces inflammation and fibrosis in the myocardium. High-mobility group box 1 (HMGB1) is a multifunctional protein that exerts proinflammatory activity by mainly binding to receptor for advanced glycation end products (RAGE). The involvement of the HMGB1-RAGE axis in the pathogenesis of inflammatory cardiomyopathy is yet not fully understood. Using the well-established model of TnI-induced experimental autoimmune myocarditis (EAM), we demonstrated that both local and systemic HMGB1 protein expression was elevated in wild-type (wt) mice after TnI immunization. Additionally, pharmacological inhibition of HMGB1 using glycyrrhizin or anti-HMGB1 antibody reduced inflammation in hearts of TnI-immunized wt mice. Furthermore, RAGE knockout (RAGE-ko) mice immunized with TnI showed no structural or physiological signs of cardiac impairment. Moreover, cardiac overexpression of HMGB1 using adeno-associated virus (AAV) vectors induced inflammation in the hearts of both wt and RAGE-ko mice. Finally, patients with myocarditis displayed increased local and systemic HMGB1 and soluble RAGE (sRAGE) expression. Together, our study highlights that HMGB1 and its main receptor, RAGE, appear to be crucial factors in the pathogenesis of TnI-induced EAM, because inhibition of HMGB1 and ablation of RAGE suppressed inflammation in the heart. Moreover, the proinflammatory effect of HMGB1 is not necessarily dependent on RAGE only. Other receptors of HMGB1 such as Toll-like receptors (TLRs) may also be involved in disease pathogenesis. These findings could be confirmed by the clinical relevance of HMGB1 and sRAGE. Therefore, blockage of one of these molecules might represent a novel therapeutic strategy in the treatment of autoimmune myocarditis and inflammatory cardiomyopathy.

The Role of HMGB1 in Cardiovascular Biology: Danger Signals

SIGNIFICANCE

Cardiovascular disease (CVD) is the leading cause of mortality worldwide. Accumulating evidence shows that dysregulated immune response contributes to several types of CVDs such as atherosclerosis and pulmonary hypertension (PH). Vascular intimal impairment and low-density lipoprotein oxidation trigger a complex network of innate immune responses and sterile inflammation.

RECENT ADVANCES

High-mobility group box 1 (HMGB1), a nuclear DNA-binding protein, was recently discovered to function as a damage-associated molecular pattern molecule (DAMP) that initiates the innate immune responses. These findings lead to the understanding that HMGB1 plays a critical role in the inflammatory response in the pathogenesis of CVD.

CRITICAL ISSUES

In this review, we highlight the role of extracellular HMGB1 as a proinflammatory mediator as well as a DAMP in coronary artery disease, cerebral artery disease, peripheral artery disease, and PH.

FUTURE DIRECTIONS

A key focus for future researches on HMGB1 location, structure, modification, and signaling will reveal HMGB1's multiple functions and discover a targeted therapy that can eliminate HMGB1-mediated inflammation without interfering with adaptive immune responses.

Danger signaling in atherosclerosis

All aspects of the pathogenesis of atherosclerosis are critically influenced by the inflammatory response in vascular plaques. Research in the field of innate immunity from the past 2 decades has uncovered many novel mechanisms elucidating how immune cells sense microbes, tissue damage, and metabolic derangements. Here, we summarize which triggers of innate immunity appear during atherogenesis and by which pathways they can contribute to inflammation in atherosclerotic plaques. The increased understanding gained from studies assessing how immune activation is associated with the pathogenesis of atherosclerosis has provided many novel targets for potential therapeutic intervention. Excitingly, the concept that inflammation may be the core of cardiovascular disease is currently being clinically evaluated and will probably encourage further studies in this area.

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.

Clinical evaluation of high mobility group box 1 protein in Legionella pneumophila pneumonia

High mobility group box 1 (HMGB-1) protein is involved in acute lung injury due to various etiologies. We evaluated HMGB-1 levels in sera and bronchoalveolar fluids in patients with pneumonia caused by Legionella pneumophila. Levels of HMGB-1 in the sera of patients with L. pneumophila pneumonia (32 cases) and control subjects (24 cases) were determined. Serum HMGB-1 levels in Legionella pneumonia were similar to those of the control subjects. No significant correlation between HMGB-1 levels and other biomarkers and the outcome of cases was observed. In contrast, HMGB-1 levels, as well as interferon-γ, in bronchoalveolar (BA) fluids from severe L. pneumophila pneumonia (7 cases) were significantly higher than those in the sera of identical patients. HMGB-1 levels in BA fluids were relatively higher in pneumonia cases with ALI than those without ALI. Our findings suggest that intra-pulmonary HMGB-1 may be involved in the pathophysiology of pneumonia caused by L. pneumophila.

Efficacy of DHMEQ, a NF-κB inhibitor, in islet transplantation: II. Induction DHMEQ treatment ameliorates subsequent alloimmune responses and permits long-term islet allograft acceptance

BACKGROUND

Long-term graft deterioration remains a major obstacle in the success of pancreatic islet transplantation (PITx). Antigen-independent inflammatory and innate immune responses strengthen subsequent antigen-dependent immunity; further, activation of nuclear factor (NF)-κB plays a key role during these responses. In this study, we tested our hypothesis that, by the inhibition of NF-κB activation, the suppression of these early responses after PITx could facilitate graft acceptance.

METHODS

Full major histocompatibility complex (MHC)-mismatched BALB/c (H-2) mice islets were transplanted into streptozotocin-induced diabetic C57BL/6 (B6: H-2) mice. The NF-κB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) was administered for either 3 or 14 days after PITx. To some PITx recipients, tacrolimus was also administered. Islet allograft survival, alloimmune responses, and in vitro effects of DHMEQ on dendritic cells (DCs) were assessed.

RESULTS

With a vehicle treatment, 600 islet allografts were promptly rejected after PITx. In contrast, 3-day treatment with DHMEQ, followed by 2-week treatment with tacrolimus, allowed permanent acceptance of islet allografts. The endogenous danger-signaling molecule high mobility group complex 1 (HMGB1) was elevated in sera shortly after PITx, whereas DHMEQ administration abolished this elevation. DHMEQ suppressed HMGB1-driven cellular activation and proinflammatory cytokine secretion in mouse bone marrow-derived DCs and significantly reduced the capacity of DCs to prime allogeneic T-cell proliferation in vitro. Finally, the DHMEQ plus tacrolimus regimen reverted the diabetic state with only 300 islet allografts.

CONCLUSIONS

Inhibition of NF-κB activation by DHMEQ shortly after PITx suppresses HMGB1, which activates DCs and strengthens the magnitude of alloimmune responses; this permits long-term islet allograft acceptance, even in case of fewer islet allografts.

Brain hypothermic therapy dramatically decreases elevated blood concentrations of high mobility group box 1 in neonates with hypoxic-ischemic encephalopathy

Background. According to the Consensus 2010 of the International Liaison Committee on Resuscitation (ILCOR), children with moderate to severe hypoxic-ischemic encephalopathy (HIE) should receive brain hypothermic therapy (BHT) after successful resuscitation. Elevated high mobility group box 1 (HMGB1) in the blood at the early stage of brain ischemia-reperfusion injury has been suggested to be involved in the release of various inflammatory cytokines. Methods. In total, 21 neonates plasma HMGB1 concentration was measured. These neonates included 8 with HIE in whom BHT was indicated, 5 controls diagnosed as having HIE but who were not suitable candidates for BHT, and 8 normal controls. Results. The umbilical artery HMGB1 (UA-HMGB1) level before undergoing BHT significantly exceeded reference values. The UA-HMGB1 level in the BHT (−) group did not differ significantly from reference values, but was significantly increased 24 hours after birth. Repeated measure ANOVA showed a significant difference in time course changes between the BHT (+) and BHT (−) groups (P = 0.0002). Conclusions. This study demonstrated hypothermic therapy to significantly decrease HMGB1. Furthermore, HMGB1 is a useful index of the inhibition of early stage inflammation.

Low temperature condition prevents hypoxia-induced islet cell damage and HMGB1 release in a mouse model

One of the major issues in clinical islet transplantation is the poor efficacy of islet isolation. During pancreas preservation and islet isolation, islets suffer from hypoxia as islets are highly sensitive to hypoxic conditions.Cold preservation has been applied to minimize hypoxia-induced cell damage during organ preservation.However, the studies related to hypoxia-induced islet cell damage during islet isolation are limited. Recently,we demonstrated that mouse islets contain high levels of high-mobility group box 1 protein (HMGB1), and during proinflammatory cytokine-induced damage, islets release HMGB1 outside the cell. The released HMGB1 is involved in the initial events of early islet loss. In the present study, we hypothesize that low temperature conditions could prevent both hypoxia induced islet cell damage and HMGB1 release from islets in a mouse model. Isolated mouse islets underwent normoxic condition (95% air and 5% CO(2)) at 37°C or hypoxic conditions (1% O(2), 5% CO(2), and 94% N(2)) at 37°C (hypoxia-37°C islets), 22°C (hypoxia-22°C islets), or 4°C (hypoxia-4°C islets) for 12 h. In vitro and in vivo viability and functionality tests were performed. HMGB1, IL-6, G-CSF, KC, RANTES, MCP-1, and MIP-1α levels in the medium were measured. Low temperature conditions substantially reduced hypoxia-induced necrosis (p < 0.05) and apoptosis (p < 0.05). In addition, low temperature islet culture significantly increased the insulin secretion from islets by high glucose stimulation (p < 0.05). All of the recipient mice reversed diabetes after receiving the hypoxia-4°C islets but not after receipt of hypoxia-37°C or 22°C islets. The amounts of released HMGB1, IL-6, G-CSF, KC, RANTES, MCP-1, and MIP-1α were significantly reduced in the hypoxia-4°C islets compared to those of the hypoxia-37°C islets (p < 0.05). In conclusion, low temperature conditions could prevent hypoxia-induced islet cell damage, inflammatory reactions in islets, and HMGB1 release and expression. Low temperature conditions should improve the efficacy of isolated islets.

Correlation of released HMGB1 levels with the degree of islet damage in mice and humans and with the outcomes of islet transplantation in mice

Establishing reliable islet potency assay is a critical and unmet issue for clinical islet transplantation. Recently, we reported that islets contained high levels of high mobility group box 1 (HMGB1) and damaged islets released HMGB1 in a mouse model. In this study, we hypothesized that the amount of released HMGB1 could reflect the degree of islet damage, and could predict the outcome of islet transplantation. Four groups of damaged mouse islets and three groups of damaged human islets were generated by hypoxic conditions. These islets were assessed by in vivo (transplantation) and in vitro (released HMGB1 levels, released C-peptide levels, PI staining, TUNEL staining, ATP/DNA, and glucose-stimulated insulin release test) assays. In addition, the ability of each assay to distinguish between noncured (n = 13) and cured (n = 7) mice was assessed. The curative rates of STZ-diabetic mice after receiving control, hypoxia-3h, hypoxia-6h, and hypoxia-24h mouse islets were 100%, 40%, 0%, and 0%, respectively. Only amounts of released HMGB1 and ratio of PI staining significant increased according to the degree of damages in both human and mouse islets. In terms of predictability of curing diabetic mice, amounts of released HMGB1 showed the best sensitivity (100%), specificity (100%), positive (100%), and negative predictive values (100%) among all the assays. The amount of released HMGB1 reflected the degree of islet damage and correlated with the outcome of islet transplantation in mice. Hence, released HMGB1 levels from islets should be a useful marker to evaluate the potency of isolated islets.

Pretreatment of donor islets with the Na(+) /Ca(2+) exchanger inhibitor improves the efficiency of islet transplantation

Pancreatic islet transplantation is an attractive therapy for the treatment of insulin-dependent diabetes mellitus. However, the low efficiency of this procedure necessitating sequential transplantations of islets with the use of 2-3 donors for a single recipient, mainly due to the early loss of transplanted islets, hampers its clinical application. Previously, we have shown in mice that a large amount of HMGB1 is released from islets soon after their transplantation and that this triggers innate immune rejection with activation of DC, NKT cells and neutrophils to produce IFN-γ, ultimately leading to the early loss of transplanted islets. Thus, HMGB1 release plays an initial pivotal role in this process; however, its mechanism remains unclear. Here we demonstrate that release of HMGB1 from transplanted islets is due to hypoxic damage resulting from Ca(2+) influx into β cells through the Na(+) /Ca(2+) exchanger (NCX). Moreover, the hypoxia-induced β cell damage was prevented by pretreatment with an NCX-specific inhibitor prior to transplantation, resulting in protection and long-term survival of transplanted mouse and human islets when grafted into mice. These findings suggest a novel strategy with potentially great impact to improve the efficiency of islet transplantation in clinical settings by targeting donor islets rather than recipients.

Cardiovascular disease and high-mobility group box 1--is a new inflammatory killer in town?

High-mobility group box 1 (HMGB-1) is a nuclear protein physiologically involved in the maintaining of DNA structure in the nucleus. When tissue damage occurs, necrotic cells as well as inflammatory cells, once activated, release this protein in circulating blood, where it seems to exert a direct proinflammatory action. Thus, HMGB-1 might be involved in the pathophysiology of several diseases, including cardiovascular disease. However, the experimental evidence has not yet clarified its cardiovascular role which is still debated. Specifically, it is still not completely resolved whether HMGB-1 plays a protective or detrimental role on cardiovascular function. In this review, we consider the role of HMGB-1 in pathological conditions and comment on the role of this protein in the cardiovascular disease.

Correlation between serum high-mobility group box-1 levels and high-sensitivity C-reactive protein and troponin I in patients with coronary artery disease

The aim of this study was to evaluate the correlation between levels of serum high-mobility group box-1 (HMGB1) and high-sensitivity C-reactive protein (hs-CRP) and cardiac troponin I in patients with coronary artery disease. The levels of serum HMGB1, hs-CRP and cardiac troponin I were measured in 98 patients with coronary artery disease and in 30 healthy subjects. The correlation between serum HMGB1 levels and hs-CRP and cardiac troponin I levels was analyzed. Serum HMGB1 levels in patients with coronary artery disease were higher compared with those in healthy volunteers (63.5±15.29 vs. 21.98±4.33 μg/l; P<0.01). Serum HMGB1 levels in patients with acute myocardial infarction were higher compared with those in patients with unstable and stable angina pectoris (77.53±6.86 vs. 63.67±8.6 and 44.39±9.01 μg/l, respectively; both P<0.01). The levels of HMGB1 were positively correlated with hs-CRP and cardiac troponin I levels (r=0.657 and 0.554, respectively; both P<0.01) in patients with coronary artery disease. In conclusion, serum HMGB1 levels were elevated in patients with coronary artery disease, particularly in those with acute myocardial infarction. The levels of HMGB1 were correlated with the levels of hs-CRP and cardiac troponin I.

HMGB1 is associated with atherosclerotic plaque composition and burden in patients with stable coronary artery disease

OBJECTIVES

The role of inflammation in atherosclerosis is widely appreciated. High mobility group box 1 (HMGB1), an injury-associated molecular pattern molecule acting as a mediator of inflammation, has recently been implicated in the development of atherosclerosis. In this study, we sought to investigate the association of plasma HMGB1 with coronary plaque composition in patients with suspected or known coronary artery disease (CAD).

DESIGN

HMGB1, high sensitive troponin T (hsTnT) and high sensitive C-reactive protein (hsCRP) were determined in 152 consecutive patients with suspected or known stable CAD who underwent clinically indicated 256-slice coronary computed tomography angiography (CCTA). Using CCTA, we assessed 1) coronary calcification, 2) non-calcified plaque burden and 3) the presence of vascular remodeling in areas of non-calcified plaques.

RESULTS

Using univariate analysis, hsCRP, hsTnT and HMGB1 as well as age, and atherogenic risk factors were associated with non-calcified plaque burden (r = 0.21, p = 0.009; r = 0.48, p<0.001 and r = 0.34, p<0.001, respectively). By multivariate analysis, hsTnT and HMGB1 remained independent predictors of the non-calcified plaque burden (r = 0.48, p<0.01 and r = 0.34, p<0.001, respectively), whereas a non-significant trend was noticed for hs-CRP (r = 0.21, p = 0.07). By combining hsTnT and HMGB1, a high positive predictive value for the presence of non-calcified and remodeled plaque (96% and 77%, respectively) was noted in patients within the upper tertiles for both biomarkers, which surpassed the positive predictive value of each marker separately.

CONCLUSIONS

In addition to hs-TnT, a well-established cardiovascular risk marker, HMGB1 is independently associated with non-calcified plaque burden in patients with stable CAD, while the predictive value of hs-CRP is lower. Complementary value was observed for hs-TnT and HMGB1 for the prediction of complex coronary plaque.

Optimization of fluoroimmunoassay against C-reactive protein exploiting immobilized-antigen glass slide

An optimization experiment for an indirect-competitive (IC) fluoroimmunoassay (FIA) against C-reactive protein (CRP) was conducted exploiting an immobilized-antigen glass slide and an anti-CRP antibody tagged with fluorescent silica nanoparticles (FSNPs). The optimized conditions for the IC FIA were as follows: time and concentration of treatment with glutaraldehyde, 30 min and 1.5%, respectively; time of reaction with coating antigen and concentration of coating antigen for immobilization, 1 h and 0.1 mg/mL, respectively; concentration of FSNP-anti-CRP antibody conjugate coupled by the biotin-avidin interaction, the bioconjugate, for immune reaction, 0.250 mg/mL; concentration of bovine serum albumin (BSA) for blocking and time of blocking with BSA, 3% and 30 min, respectively. By using the glass slide, a highly sensitive detection against CRP was possible with the limit of detection below 0.1 ng/mL.

Paucity of CD34-positive cells and increased expression of high-mobility group box 1 in coronary thrombus with type 2 diabetes mellitus

To examine the presence of CD34-positive cells and intranuclear factors in acute coronary thrombi, we compared thrombi in patients with type 2 diabetes mellitus (DM, n = 21) and without DM (n = 29). Immunohistochemical staining revealed the constitutive presence of platelets, fibrin, erythrocytes, neutrophils, extracellular high-mobility group box 1 (HMGB-1), and histone H3 in all thrombi. There were significantly more oval or flat CD34-positive cells and significantly larger HMGB-1-positive areas in the thrombi from patients with DM. The flat CD34-positive cells expressed ecto-nucleoside triphosphate diphosphohydrolase (a platelet aggregation inhibitor). The number of CD34-positive cells was negatively correlated with the serum levels of glucose and hemoglobin A1c, whereas the HMGB-1-positive area was positively correlated with the levels of serum glucose. The paucity of CD34-positive cells and the high levels of HMGB-1 expression in acute coronary thrombi from patients with type 2 DM could facilitate thrombus formation.

Circulating high-mobility group box 1 and cardiovascular mortality in unstable angina and non-ST-segment elevation myocardial infarction

OBJECTIVE

High-mobility group box 1 (HMGB1) is a damage-associated molecular pattern molecule, which suggests a potential role of this protein in the pathophysiology of acute coronary syndrome (ACS). Circulating HMGB1 has been shown to be independently associated with cardiac mortality in ST-segment elevation myocardial infarction. However, its prognostic value remains unclear in unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI).

METHODS

HMGB1, high-sensitivity C-reactive protein (hsCRP), cardiac troponin I and B-type natriuretic peptide concentrations were measured on admission in 258 consecutive patients (mean age of 67 years) hospitalized for UA/NSTEMI within 24h (mean, 7.4h) of the onset of chest symptoms.

RESULTS

A total of 38 (14.7%) cardiovascular deaths, including 10 in-hospital deaths, occurred during a median follow-up period of 49 months after admission. In a stepwise Cox regression analysis including 19 well-known clinical predictors of ACS, HMGB1 [relative risk (RR) 3.24 per 10-fold increment; P = 0.0003], cardiac troponin I (RR 1.83 per 10-fold increment, P = 0.0007), Killip class>1 (RR 4.67, P = 0.0001) and age (RR 1.05 per 1-year increment, P = 0.03), but not hsCRP, were independently associated with cardiovascular mortality. In-hospital and cardiovascular mortality rates were higher in patients with increased HMGB1 (≥ 2.4 ng/mL of median value) than those without increased HMGB1 (6.3% vs. 1.5%, P = 0.04; and 23% vs. 6.9%, P = 0.0003).

CONCLUSION

Circulating concentration of HMGB1 on admission may be a potential and independent predictor of cardiovascular mortality in patients hospitalized for UA/NSTEMI within 24h of onset.

HMGB1: a multifunctional alarmin driving autoimmune and inflammatory disease

HMGB1 is a non-histone nuclear protein that can serve as an alarmin to drive the pathogenesis of inflammatory and autoimmune disease. Although primarily located in the cell nucleus, HMGB1 can translocate to the cytoplasm, as well as the extracellular space, during cell activation and cell death; during activation, HMGB1 can undergo post-translational modifications. The activity of HMGB1 varies with the redox states of the cysteine residues, which are required for binding to TLR4. In addition to stimulating cells directly, HMGB1 can form immunostimulatory complexes with cytokines and other endogenous and exogenous factors. In the synovia of patients with rheumatoid arthritis, as well as animal models of this disease, extranuclear expression of HMGB1 is increased and blockade of HMGB1 expression attenuates disease in animal models. In systemic lupus erythematosus, HMGB1 can be a component of immune complexes containing anti-DNA because of its interaction with DNA. In myositis, expression of HMGB1 is enhanced in inflamed muscle and can perturb muscle function. Together, these findings indicate that HMGB1 might be an important mediator and biomarker in rheumatic diseases as well as a target of new therapy.

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.

Measurement of plasma concentration of high mobility group box1 (HMGB1) in early neonates and evaluation of its usefulness

BACKGROUND

High mobility group box 1 (HMGB1), intensively studied in adult patients by several investigators, is suggested to cause potentially fatal conditions such as systemic inflammatory response syndrome (SIRS) and disseminated intravascular coagulation (DIC). However, little is known about the role of this protein in neonates.

METHODS

In total, 173 full-term neonates were divided into 4 groups according to mode of delivery: scheduled cesarean section (group E, n=67), unscheduled cesarean section (group ER, n=10), normal delivery (group N, n=64) and other modes of vaginal delivery (group CN, n=32). HMGB1 concentration in umbilical cord blood and plasma samples collected 5 days after birth were compared among these 4 groups. We also attempted to determine a reference value for HMGB1 concentrations in neonates.

RESULTS

The HMGB1 reference value in neonates was 2.0-35.3 ng/ml in groups E and N (n=131). The concentration was significantly higher in group ER than in group E (P=0.00022), and was also higher in group CN than in group N (P=0.00721).

CONCLUSIONS

To our knowledge, this study is the first to determine a reference value for HMGB1 concentrations in neonates. We also revealed significantly elevated HMGB1 concentrations in association with ischemic reperfusion injury caused by certain delivery modes.

Acute removal of common sepsis mediators does not explain the effects of extracorporeal blood purification in experimental sepsis

The effect of extracorporeal blood purification on clinical outcomes in sepsis is assumed to be related to modulation of plasma cytokine concentrations. To test this hypothesis directly, we treated rats that had a cecal ligation followed by puncture (a standard model of sepsis) with a modest dose of extracorporeal blood purification that did not result in acute changes in a panel of common cytokines associated with inflammation (TNF-α, IL-1β, IL-6, and IL-10). Pre- and immediate post-treatment levels of these cytokines were unchanged compared to the sham therapy of extracorporeal circulation without blood purifying sorbent. The overall survival to 7 days, however, was significantly better in animals that received extracorporeal blood purification compared to those with a sham procedure. This panel of common plasma cytokines along with alanine aminotransferase and creatinine was significantly lower 72 h following extracorporeal blood purification compared to sham-treated rats. Thus, the effects of this procedure on organ function and survival do not appear to be due solely to immediate changes in the usual measured circulating cytokines. These results may have important implications for the design and conduct of future trials in sepsis including defining alternative targets for extracorporeal blood purification and other therapies.

High-mobility group box 1 is involved in the initial events of early loss of transplanted islets in mice

Islet transplantation for the treatment of type 1 diabetes mellitus is limited in its clinical application mainly due to early loss of the transplanted islets, resulting in low transplantation efficiency. NKT cell-dependent IFN-gamma production by Gr-1(+)CD11b(+) cells is essential for this loss, but the upstream events in the process remain undetermined. Here, we have demonstrated that high-mobility group box 1 (HMGB1) plays a crucial role in the initial events of early loss of transplanted islets in a mouse model of diabetes. Pancreatic islets contained abundant HMGB1, which was released into the circulation soon after islet transplantation into the liver. Treatment with an HMGB1-specific antibody prevented the early islet graft loss and inhibited IFN-gamma production by NKT cells and Gr-1(+)CD11b(+) cells. Moreover, mice lacking either of the known HMGB1 receptors TLR2 or receptor for advanced glycation end products (RAGE), but not the known HMGB1 receptor TLR4, failed to exhibit early islet graft loss. Mechanistically, HMGB1 stimulated hepatic mononuclear cells (MNCs) in vivo and in vitro; in particular, it upregulated CD40 expression and enhanced IL-12 production by DCs, leading to NKT cell activation and subsequent NKT cell-dependent augmented IFN-gamma production by Gr-1(+)CD11b(+) cells. Thus, treatment with either IL-12- or CD40L-specific antibody prevented the early islet graft loss. These findings indicate that the HMGB1-mediated pathway eliciting early islet loss is a potential target for intervention to improve the efficiency of islet transplantation.

Comparative effects of benidipine and amlodipine on proteinuria, urinary 8-OHdG, urinary L-FABP, and inflammatory and atherosclerosis markers in early-stage chronic kidney disease

INTRODUCTION

We examined the effects of 2 calcium channel blockers, benidipine (T-, L-, and N-type) and amlodipine (L- and N-type), on renal, inflammatory, oxidative, and atherosclerosis markers in hypertensive patients with mild chronic kidney disease (CKD).

METHODS

Forty hypertensive patients with CKD were assigned randomly to either of the 2 treatments: 8 mg benidipine once daily (n = 20, group A) or 5 mg amlodipine once daily (n = 20, group B). Treatment was continued for 12 months. Blood pressure, serum creatinine, estimated glomerular filtration rate, urinary protein excretion, urinary liver-type fatty acid-binding protein, interleukin-6, high mobility group box-1 protein, urinary 8-hydroxy-2'-deoxyguanosine, pulse wave velocity, intima-media thickness, and blood asymmetric dimethylarginine were monitored.

RESULTS

Blood pressure decreased equally in both groups (P < 0.001, at 6 and 12 months versus before treatment). Serum creatinine and estimated glomerular filtration rate changed little during the experimental period in each group. However, urinary protein excretion (P < 0.001), urinary liver-type fatty acid-binding protein (P < 0.001), urinary 8-hydroxy-2'-deoxyguanosine (P < 0.001), blood interleukin-6 (P < 0.001), blood high mobility group box-1 (P < 0.05), and pulse wave velocity (P < 0.01) decreased more in group A than in group B with 12 months of treatment. The percent reductions in intima-media thickness and blood asymmetric dimethylarginine were significantly greater in group A than in group B (P < 0.001).

CONCLUSIONS

Benidipine is more effective than amlodipine for protecting renal function and potentially for ameliorating atherosclerosis in hypertensive patients with mild CKD. T-type calcium channel blockers may be effective in patients with CKD.

Factors associated with serum high mobility group box 1 (HMGB1) levels in a general population

High mobility group box 1 (HMGB1), a nonhistone chromatin-associated protein, is implicated as a mediator of both infectious and non-infectious inflammatory conditions. Clinical research on this protein in humans just has begun; serum HMGB1 was reported to be elevated in a small number of critically ill patients suffering from sepsis. However, the kinetics, distribution and factors associated with circulating HMGB1 are unknown in a general population. In this study, we examined these issues in a large population of healthy subjects. Fasting blood samples were obtained from 626 subjects (237 males and 389 females). HMGB1 levels showed a skewed distribution with a mean of 1.65 +/- 0.04 ng/ml. Multiple stepwise regression analyses found that white blood cell (WBC) counts (P = .016) and the soluble form of receptor for advanced glycation end products (sRAGE; P < .001, inversely), which is also known to be a receptor for HMGB1, were independently associated with HMGB1 levels. We demonstrated for the first time that circulating HMGB1 levels were inversely associated with sRAGE levels in a general population. Because RAGE is involved in HMGB1 signaling, our present study suggests that sRAGE may capture and eliminate circulating HMGB1 in humans.

Positive association of serum levels of advanced glycation end products and high mobility group box-1 with asymmetric dimethylarginine in nondiabetic chronic kidney disease patients

There is accumulating evidence that engagement of the receptor for advanced glycation end products (RAGE) with ligands such as advanced glycation end products (AGEs) and high mobility group box-1 (HMGB-1) elicits vascular inflammation, thus contributing to the increased risk for cardiovascular disease. Furthermore, enhanced accumulation of asymmetric dimethylarginine (ADMA) plays a role in cardiovascular disease in chronic kidney disease (CKD) patients. However, the relationships among serum levels of AGEs, HMGB-1, soluble form of RAGE (sRAGE), and ADMA are largely unknown. The aim of the present study is to determine their relationships in CKD patients. Twenty nondiabetic normotensive CKD patients with dyslipidemia and 20 age- and sex-matched healthy controls were enrolled. All subjects underwent determination of blood chemistries; urinary proteinuria; and serum levels of AGEs, HMGB-1, sRAGE, and ADMA. Serum AGE, HMGB-1, sRAGE, and ADMA levels in CKD patients were significantly higher than those in control subjects. Circulating levels of AGEs in CKD patients were positively associated with sRAGE and ADMA, and HMGB-1 with ADMA, but not sRAGE. There were no significant associations among these markers and serum creatinine, estimated glomerular filtration rate, proteinuria, and lipid levels. In multiple regression analyses, AGEs and HMGB-1 were independently correlated with ADMA. The present study demonstrated that AGE and sRAGE levels were correlated with each other and that AGEs and HMGB-1 were independently associated with ADMA in nondiabetic CKD patients. Elevation of the RAGE ligands may enhance ADMA levels, suggesting the active involvement of AGE/HMGB-1-RAGE-ADMA axis in CKD patients.

Effect of polymyxin B-immobilized fiber hemoperfusion on serum high mobility group box-1 protein levels and oxidative stress in patients with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by diffuse inflammation in the lung and resultant permeability edema. Polymyxin B-immobilized fiber (PMX-F) hemoperfusion is effective for sepsis-induced ARDS. High mobility group box-1 protein (HMGB1) is newly recognized as a proinflammatory cytokine. The aim of the study was to determine whether blood HMGB1 levels are increased in patients with ARDS and whether PMX-F treatment affects these levels. Subjects were 20 sepsis-induced patients with ARDS treated by PMX-F column and 20 age-matched healthy volunteers. Polymyxin B-immobilized fiber treatment was carried out twice at a rate of 100 ml/min for 2 hours. Systolic and diastolic blood pressures, the PaO2/FiO2 (PF) ratio and endotoxin, HMGB1, and urinary 8-hydroxy-2'-deoxyguanosine (OHdG) levels were measured before and after PMX-F treatment. Blood endotoxin levels, blood HMGB1 levels, and urinary 8-OHdG levels were significantly higher in patients with ARDS than in healthy volunteers. Systolic and diastolic blood pressures and the PF ratio increased significantly after PMX-F treatments. Polymyxin B-immobilized fiber treatment reduced blood endotoxin, blood HMGB1, and urinary 8-OHdG levels significantly. These data suggest that HMGB1 and oxidative stress play a role in the pathogenesis of ARDS and that PMX-F treatment may ameliorate increased blood HMGB1 and urinary 8-OHdG levels in patients with ARDS.

Innate immune signals in atherosclerosis

Atherosclerosis is a chronic disease characterised by lipid retention and inflammation in the arterial intima. Innate immune mechanisms are central to atherogenesis, involving activation of pattern-recognition receptors (PRRs) and induction of inflammatory processes. In a complex tissue, such as the atherosclerotic lesion, innate signals can originate from several sources and promote atherogenesis through ligation of PRRs. The receptors recognise conserved molecular patterns on pathogens and endogenous products of tissue injury and inflammation. Activation of PRRs might affect several aspects of atherosclerosis by acting on lesion resident cells. Scavenger receptors mediate antigen uptake and clearance of lipoproteins, thereby promoting foam cell formation. Signalling receptors, such as Toll-like receptors (TLRs), lead to induction of pro-inflammatory cytokines and antigen-specific immune responses. In this review we describe the innate mechanisms present in the plaque. We focus on TLRs, their cross-talk with other PRRs, and how their signalling cascades influence inflammation within the atherosclerotic lesion.

HMGB1 is markedly elevated within 6 hours of mechanical trauma in humans

High-mobility group box 1 (HMGB1) is a late mediator of the systemic inflammation associated with sepsis. Recently, HMGB1 has been shown in animals to be a mediator of hemorrhage-induced organ dysfunction. However, the time course of plasma HMGB1 elevations after trauma in humans remains to be elucidated. Consequently, we hypothesized that mechanical trauma in humans would result in early significant elevations of plasma HMGB1. Trauma patients at risk for multiple organ failure (ISS > or = 15) were identified for inclusion (n = 23), and postinjury plasma samples were assayed for HMGB1 by enzyme-linked immunosorbent assay. Comparison of postinjury HMGB1 levels with markers for patient outcome (age, injury severity score, units of red blood cell (RBC) transfused per first 24 h, and base deficit) was performed. To investigate whether postinjury transfusion contributes to elevations of circulating HMGB1, levels were determined in both leuko-reduced and non-leuko-reduced packed RBCs. Plasma HMGB1 was elevated more than 30-fold above healthy controls within 1 h of injury (median, 57.76 vs. 1.77 ng/mL; P < 0.003), peaked from 2 to 6 h postinjury (median, 526.18 ng/mL; P < 0.01 vs. control), and remained elevated above control through 136 h. No clear relationship was evident between postinjury HMGB1 levels and markers for patient outcome. High-mobility group box 1 levels increase with duration of RBC storage, although concentrations did not account for postinjury plasma levels. Leuko-reduced attenuated HMGB1 levels in packed RBCs by approximately 55% (P < 0.01). Plasma HMGB1 is significantly increased within 1 h of trauma in humans with marked elevations occurring from 2 to 6 h postinjury. These results suggest that, in contrast to sepsis, HMGB1 release is an early event after traumatic injury in humans. Thus, HMGB1 may be integral to the early inflammatory response to trauma and is a potential target for future therapeutics.