Serum High Mobility Group Box 1 Concentrations Research Articles

Emulsified Isoflurane Protects Against Transient Focal Cerebral Ischemia Injury in Rats via the PI3K/Akt Signaling Pathway.

Phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) pathway activation may promote neuronal survival via neuroprotection during inflammation after cerebral ischemia. In this study, we investigated whether IV pretreatment with emulsified isoflurane (EI) could decrease ischemic brain injury related to the PI3K/Akt pathway. Male Sprague-Dawley rats received different doses of IV EI (1, 2, 4, or 8 mL/kg/h) or Intralipid (8 mL/kg/h) for 30 minutes (n = 6-12 per group), followed by middle cerebral artery occlusion (MCAO) for 100 minutes to induce transient focal ischemia. The neurologic score and infarct volume were measured 48 hours after MCAO. Immunostaining, Western blot analysis, and an enzyme-linked immunosorbent assay were used to assess EI effects on the cell inflammatory response, high-mobility group box-1 release, and phosphorylated Akt (expression. LY294002, a PI3K inhibitor, was also infused into the ventricular space before EI to determine the effect of EI. Four milliliters per kilogram per hour of EI reduced the infarct size (21.08 ± 11.24 vs 37.09 ± 10.46, P = 0.006), improved neurologic scores after MCAO (1.13 ± 0.48 vs 1.95 ± 0.65, P = 0.015), significantly reinforced neuronal survival (982.7 ± 364.4 vs 439.8 ± 278.4, P = 0.036), and inhibited CD68 macrophage/macroglial infiltration in the ischemic core (188.2 ± 49.1 vs 282 ± 49.4, P = 0.018) compared with the vehicle group. In the EI pretreatment group, the serum high-mobility group box-1 concentration (3.62 ± 0.72 vs 5.73 ± 0.65, P < 0.001) was decreased, and the cerebral phosphorylated Akt level (50.33 ± 4.73 vs 37.5 ± 3.11, P = 0.007) was increased at 48 hours, which was inhibited by LY294002 compared with the vehicle group (5.31 ± 0.72 vs 5.73 ± 0.65, P = 0.216; 43.00 ± 4.84 vs 37.5 ± 3.11, P = 0.091). These findings suggest that EI pretreatment protects against ischemic brain injury via the inhibition of cerebral inflammation and is associated with the PI3K-Akt pathway in rats with MCAO. This drug may be a novel therapeutic agent for patients after stroke.

High-mobility group box 1 protein levels in serum of subjects after exposure to fire smoke--short communication.

Fire smoke inhalation a recognized etiologic factor of airway injuries. The objective of this study was evaluation of serum high-mobility group box 1 (HMGB1) protein concentration in subjects exposed to fire smoke (SEFS). The study group consisted of 40 consecutive patients admitted to the Toxicology Unit, Lodz, Poland after exposure to fire smoke. Serum HMGB1 concentrations were measured upon admission to hospital and rechecked on the 2nd and on the day of discharge. Patients also underwent routine toxicological diagnostic procedures applied in case of those exposures, such as carboxyhaemoglobin (COHb) levels and urinary thiocyanate concentrations. The same diagnostic tests were performed in 10 healthy volunteers not exposed to smoke of the control group. The average serum SEFS concentration of HMGB1 protein was not significantly higher on admission in comparison with the respective values recorded on the 2nd day and on the day of discharge. The mean serum level of HMGB1 protein of exposed group was higher than that one in the control group, however the difference was not statistically significant. The highest concentration of HMGB1 protein was noted in serum of 28 subjects exposed to fire smoke reporting at least one symptom and the difference was statistically significant in a comparison with the control group. As indicated, an acute exposure to smoke may lead to transient increase of HMGB1 in serum in exposed subjects. Further studies are necessary in order to confirm the importance of this protein in pathogenesis of acute airway injury due to exposure to fire smoke.

Poly(ADP-ribose) polymerase 1-sirtuin 1 functional interplay regulates LPS-mediated high mobility group box 1 secretion.

Pathophysiological conditions that lead to the release of the prototypic damage-associated molecular pattern molecule high mobility group box 1 (HMGB1) also result in activation of poly(ADP-ribose) polymerase 1 (PARP1; now known as ADP-ribosyl transferase 1 [ARTD1]). Persistent activation of PARP1 promotes energy failure and cell death. The role of poly(ADP-ribosyl)ation in HMGB1 release has been explored previously; however, PARP1 is a versatile enzyme and performs several other functions including cross-talk with another nicotinamide adenine dinucleotide- (NAD(+)) dependent member of the Class III histone deacetylases (HDACs), sirtuin-1 (SIRT1). Previously, it has been shown that the hyperacetylation of HMGB1 is a seminal event prior to its secretion, a process that also is dependent on HDACs. Therefore, in this study, we seek to determine if PARP1 inhibition alters LPS-mediated HMGB1 hyperacetylation and subsequent secretion due to its effect on SIRT1. We demonstrate in an in vitro model that LPS treatment leads to hyperacetylated HMGB1 with concomitant reduction in nuclear HDAC activity. Treatment with PARP1 inhibitors mitigates the LPS-mediated reduction in nuclear HDAC activity and decreases HMGB1 acetylation. By utilizing an NAD(+)-based mechanism, PARP1 inhibition increases the activity of SIRT1. Consequently, there is an increased nuclear retention and decreased extracellular secretion of HMGB1. We also demonstrate that PARP1 physically interacts with SIRT1. Further confirmation of this data was obtained in a murine model of sepsis, that is, administration of PJ-34, a specific PARP1 inhibitor, led to decreased serum HMGB1 concentrations in mice subjected to cecal ligation and puncture (CLP) as compared with untreated mice. In conclusion, our study provides new insights in understanding the molecular mechanisms of HMGB1 secretion in sepsis.

Serum HMGB1 as a Diagnostic Marker for Malignant Peritoneal Mesothelioma

Diffuse malignant peritoneal mesothelioma (DMPM) is an aggressive malignant tumor of mesothelial origin that shows a limited response to cytoreductive surgery along with intraperitoneal chemotherapy. Therefore, early diagnosis of DMPM is very important. Some researchers have previously reported that high-mobility group box 1 (HMGB1) was correlated with pulmonary fibrosis. DMPM involves the malignant transformation of mesothelial cells, which originate from mesenchymal cells, similar to lung fibroblasts. Here, we investigated serum levels of HMGB1 in patients with MPM and compared them with those of a population that had been exposed to asbestos without developing MPM. The serum concentrations of HMGB1 were measured in 13 DMPM patients and 45 individuals with benign asbestos-related diseases. We demonstrated that the patients with DMPM had significantly higher serum levels of HMGB1 compared with the population who had been exposed to asbestos but did not develop DMPM. Our data suggest that serum HMGB1 concentration is a useful serum marker for DMPM.

Serum HMGB1 as a prognostic marker for malignant pleural mesothelioma

BackgroundMalignant pleural mesothelioma (MPM) is an aggressive malignant tumor of mesothelial origin that shows a limited response to conventional chemotherapy and radiotherapy. Therefore, diagnosing MPM early is very important. Some researchers have previously reported that high-mobility group box 1 (HMGB1) was correlated with pulmonary fibrosis. MPM involves the malignant transformation of mesothelial cells, which originate from mesenchymal cells similar to lung fibroblasts. Here, we investigated serum levels of HMGB1 in patients with MPM and compared them with those of a population that had been exposed to asbestos without developing MPM.MethodsHMGB1 production from MPM cell lines was measured using ELISA. Serum HMGB1 levels were also examined in 61 MPM patients and 45 individuals with benign asbestos-related diseases.ResultsHMGB1 concentrations of 2 out of 4 MPM cell lines were higher than that of normal mesothelial cell line, Met-5A. We demonstrated that patients with MPM had significantly higher serum levels of HMGB1 than the population who had been exposed to asbestos but had not developed MPM. The difference in overall survival between groups with serum HMGB1 levels that were lower and higher than assumed cut-off values was significant.ConclusionsOur data suggest that serum HMGB1 concentration is a useful prognostic factor for MPM.

High mobility group box 1 released from necrotic cells enhances regrowth and metastasis of cancer cells that have survived chemotherapy

The role of the high mobility group box 1 (HMGB1) protein in chemotherapy-induced cell death was examined. CT26 mouse colon cancer cells were treated with trichostatin A (TSA; apoptosis inducer) or doxorubicin (DXR; necrosis inducer). DXR increased HMGB1 concentration in CT26 cell culture medium, whereas TSA did not. In a CT26 bilateral subcutaneous tumour model, DXR or TSA was injected in a single tumour. After injection, serum HMGB1 concentration in DXR-treated mice was 10 times higher than that in TSA-treated mice. After DXR treatment, the contralateral and remnant tumours showed more pronounced growth than did those treated with TSA. In mouse models, lung and liver metastasis was enhanced by DXR but not by TSA. DXR-enhanced metastasis was abrogated by anti-HMGB1 antibody treatment. In a cancer dormancy model, DXR induced regrowth of quiescent CT26 cells. HMGB1 induced tumour necrosis factor-α secretion via Toll-like receptor (TLR)4 in U937 monocytes; however, HMGB1 decreased the number of U937 cells, resulting in restriction of immune activation via receptor for advanced glycation endproducts (RAGE). RAGE showed a more pronounced effect on nuclear factor kappa B activation than did TLR4 in CT26 cells. These findings suggest that HMGB1 released from necrotic cancer cells treated with a necrosis inducer enhances regrowth and metastasis of remnant cancer cells via RAGE activation.

HMGB1 as a predictor of infarct transmurality and functional recovery in patients with myocardial infarction

High-mobility group box 1 (HMGB1) protein is an innate danger signal for the initiation of host defence and tissue repair. The aim of this study was to analyse serum HMGB1 concentration and its correlation with infarct transmurality and functional recovery in patients with ST-elevation (STEMI) and non-ST-elevation myocardial infarction (NSTEMI). We prospectively examined patients with first-time STEMI (n = 46) or NSTEMI (n = 49), treated according to current guidelines. Contrast-enhanced cardiac magnetic resonance imaging was performed 2-4 days after infarction for the estimation of infarct transmurality and was repeated after 6 months for the estimation of residual left ventricular function. HMGB1 was measured 2-4 days after infarction. High-mobility group box 1 concentration was related to infarct size and to residual ejection fraction in patients with STEMI (r(2) = 0.81 and r(2) =0.40, respectively, P < 0.001 for both) and NSTEMI (r(2) = 0.74 and r(2) = 0.25, respectively, P < 0.001 for both). Receiver operating characteristic (ROC) curve-derived cut-off values of 6.2 and 5.9 ng mL(-1) for patients with STEMI and NSTEMI, respectively, were predictive of infarct transmurality greater than 75% (STEMI: area under the curve (AUC) = 0.93, standard error (SE) = 0.04, 95% confidence interval (CI) = 0.81-0.98; NSTEMI: AUC = 0.96, SE = 0.04, 95% CI = 0.86-0.99). HMGB1 cut-off values of 7.2 and 6.4 ng mL(-1) for patients with STEMI and NSTEMI, respectively, were predictive of residual ejection fraction 6 months after myocardial infarction (MI) (STEMI: AUC = 0.81, SE = 0.07, 95% CI = 0.66-0.91; NSTEMI: AUC = 0.81, SE = 0.09, 95% CI = 0.68-0.91). High-mobility group box 1 serum levels represent a highly valuable surrogate marker for infarct transmurality and for the prediction of residual left ventricular function after MI.

The Kupffer Cell Inhibition Exacerbates but Splenectomy Prevents Mortality in a Rat Septic Peritonitis Model

The purpose of this study was to investigate whether inhibition of Kupffer cells (KCs) affects the expression of high mobility group box 1 (HMGB1) and mortality in septic peritonitis. The role of the spleen in septic peritonitis was also investigated. Rats were given liposome-entrapped dichloromethylene diphosphonate (lipo-MDP) to eliminate KCs or non-entrapped liposome (lipo) before cecal ligation and puncture (CLP), and serum HMGB1 levels and mortality were assessed after CLP. Furthermore, KCs and tissue macrophages were isolated, and production of HMGB1 was investigated. Effects of splenectomy on serum HMGB1 levels and mortality were also investigated after CLP. Elimination of the Kupffer cells by lipo-MDP increased serum HMGB1 concentrations and mortality significantly. Furthermore, HMGB1 expression in both the periportal area of the liver and the spleen was greater in the lipo-MDP group than the lipo group. On the other hand, splenectomy blunted serum HMGB1 levels and improved mortality after CLP. The HMGB1 expression was greater in the spleen compared with the liver after CLP. Furthermore, production of HMGB1 was greatest in splenic macrophages in vitro. The number of ED3-positive cells increased significantly in non-splenectomized animals but not in splenectomized animals after CLP. In the lipo-MDP treated groups, the number of ED3-positive macrophages also increased in the liver from non-splenectomized animals but not in the splenectomized animals after CLP. The liver and the spleen play key roles in host defense during septic peritonitis. Migrating macrophages into the liver are, in part, derived from the spleen after CLP.

High Mobility Group Box 1 (HMGB1) Levels in the Placenta and in Serum in Preeclampsia

Preeclampsia is a pregnancy disorder characterized by systemic inflammation. High mobility group box 1 (HMGB1) is a molecule known to act as a 'danger signal' by participating in various inflammatory processes, but data in regard to preeclampsia are sparse. The aim of this study was to analyze placental and serum HMGB1 levels in normal pregnancy and preeclampsia. Sera were collected from women with preeclampsia soon after the manifestation of the disease and before commencing any medication. Placental samples were collected immediately after delivery. Expressed isoforms of HMGB1 (28- and 30-kDa) in the placenta were evaluated by Western blot analysis. Serum HMGB1 concentrations were measured using enzyme-linked immunosorbent assays (ELISA). Two isoforms of HMGB1 are expressed by the human placenta. The 28- and 30-kDa HMGB1 isoforms were expressed highly in preeclamptic placental tissue; however, compared with normotensive control tissue, differences in detected expression levels did not reach statistical significance. No significant difference was observed in serum HMGB1 levels between control and preeclampsia. Inflammation provoked by HMGB1 is likely to be involved in the proinflammatory process in preeclamptic placenta. Further studies are needed to elucidate the precise role of HMGB1 in preeclampsia.

Effects of ischemic preconditioning versus ischemic postconditioning on myocardial ischemia-reperfusion-induced inflammatory response in rats

Objective To compare the effects of ischemic preconditioning versus ischemic postconditioning on myocardial ischemia-reperfusion （I/R）-induced inflammatory response in rats. Methods Forty male SD rats weighing 290-320 g were randomly divided into 4 groups （ n = 10 each）： Ⅰ group sham operatin （group S）; Ⅱ group I/R; Ⅲ group ischemic preconditioning （group IPC） and Ⅳ group ischemic postconditioning （group IPOC）.Myocardial I/R was induced by 30 min ligation of left anterior descending branch （LAD） of coronary artery followed by reperfusion. In group IPC myocardial I/R was preceded by 3 cycles of ischemia followed by reperfusion （each lasting 5 min） while in group IPOC 3 cycles of I/R （each lasting 10 s） was started at the end of 30 min myocardial ischemia. MAP, HR and RPP （ MAP × HR） were recorded before （baseline） and at 1 and 20 min of ischemia and 60, 120 and 180 min of reperfusion. Venous blood samples were collected at 30 and 180 min of reperfusion for determination of serum concentrations of TNF-α, IL-6, high-mobility group box 1 （HMGB1） and cTnI. The animals were sacrificed at 180 min of reperfusion and the myocardial infarct size was measured. Results Myocardial I/R significantly decreased MAP and RPP and increased myocarcial infarct size, serum concentrations of TNF-α, IL-6,HMGB1 and cTnI in group I/R as compmed with group S. Ischemic pre- and postconditioning significantly increased MAP and reduced myocardial infarct size and I/R-induced increase in serum TNF-α, HMGB1 and cTnI concentrations in group Ⅲ and Ⅳ as compared with group Ⅱ （I/R）. The myocardial infarct size was significantly larger and the serum concentrations of TNF-α, IL-6 and HMGB1 were significantly higher in ischemic postconditioning group than in the preconditioning group. Conclusion Ischemic preconditioning is more effective in attenuating the myocardial I/R-induced inflammatory response than the ischemic postconditioning. Key words: Ischemic preconditioning, myocardial; Myocardial repcrfusion injury; Inflammation; Ischemia postconditioning

Dietary Linoleic Acid and Glucose Enhances Azoxymethane-Induced Colon Cancer and Metastases via the Expression of High-Mobility Group Box 1

Objective: High-mobility group box 1 (HMGB1) was closely associated with progression and metastasis of colorectal cancer. Methods: We examined the significance of HMGB1 in causing colon carcinogenesis induced by azoxymethane (AOM) injection in Fischer 344 rats fed on a control diet (group C), a 15% linoleic acid (LA) diet (group L), a control diet with 10% glucose drink (group G), and a 15% LA diet with a 10% glucose drink (group L+G). Results: Group L+G showed the highest body weight and calorie intake. Serum and mucosal HMGB1 levels were temporally increased in all groups, while the highest levels were observed in group L+G. Mucosal HMGB1 levels were correlated with cancer multiplicity and nodal metastases. In the AOM-injected rats fed the 15% LA diet with 10% glucose drink, administration of HMGB1 antibody suppressed serum HMGB1 concentration and cancer multiplicity . Conclusion: These data suggest that dietary LA and glucose provided the synergistic effect on AOM-induced rat colon cancer through HMGB1 induction.

High-mobility group B1 proteins in canine lymphoma: prognostic value of initial and sequential serum levels in treatment outcome following combination chemotherapy

Elevated high-mobility group box 1 (HMGB1) levels have been demonstrated in different human neoplasias. Information on serum HMGB1 before and during chemotherapy is lacking, as is data pertaining to its prognostic significance. The aim of this study was to characterize serum HMGB1 level in dogs with lymphoma and to assess its influence on the outcome following chemotherapy. Serum HMGB1 concentrations were measured in 16 dogs with lymphoma before treatment (W1) and on weeks 2 (W2), 6 (W6) and 12 (W12) of treatment with chemotherapy. Initial serum HMGB1 levels were significantly higher than HMGB1concentrations in control dogs and the levels in W2, W6 and W12. HMGB1-W1 concentrations were lower in dogs achieving complete remission than that in the single dog with partial remission. The ratio W12/W6 exhibited significant influence on remission duration. In these dogs with lymphoma, serum HMGB1 was elevated in comparison with that in controls. Initial serum HMGB1 level and its modulation during treatment may possess prognostic value.

Increased serum HMGB1 is related to the severity of coronary artery stenosis

Background High mobility group box 1 (HMGB1) protein has been identified as a novel pro-inflammatory cytokine in coronary artery disease (CAD). We investigated the relationship between serum HMGB1 level and the severity of coronary artery stenosis. Methods Serum HMGB1 concentration in patients was measured by ELISA. All patients underwent coronary angiography and were assigned into groups according to the quartile of HMGB1 level. Results HMGB1 level in USAP group was higher than that in control and SAP group. HMGB1 level in SAP group was higher than that in control group ( p < 0.05). Gensini scores in the highest quartile group (group IV), group III and group II were all significantly higher than that in the lowest quartile group (group I). There was significant correlation between angiographic Gensini score and serum level of HMGB1 ( r = 0.710, p < 0.05). However, in subgroup analysis, we found that serum HMGB1 level was only correlated with angiographic Gensini score in SAP patients ( r = 0.786, p < 0.05), but not USAP patients. Conclusions Serum HMGB1 level was markedly increased with the severity of coronary artery stenosis in patients with SAP and USAP, especially in SAP patients, which suggested that increased serum HMGB1 may involve in the pathogenesis of atherosclerotic CAD.

Tetrandrine Increased the Survival Rate of Mice With Lipopolysaccharide-Induced Endotoxemia

Endotoxemia usually causes significant morbidity and mortality, and treatment of endotoxemia is often ineffective. The effects of tetrandrine (a bisbenzylisoquinoline alkaloid) on lipopolysaccharide (LPS)-induced endotoxemia were investigated in mice. The peritoneal macrophages were stimulated with LPS and treated with or without tetrandrine. The amounts of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-10 secreted by peritoneal macrophages were measured by enzyme-linked immunosorbent assay. Mice were intraperitoneally injected with LPS to induce endotoxemia and were treated or not treated with oral gavage with 150 mg/kg tetrandrine 1 hour before or after LPS injection. The survival rate of the mice was determined after they were treated with various regiments. The amounts of TNF-alpha, IL-1beta, IL-6, and IL-10 in the serum of the mice were measured by enzyme-linked immunosorbent assay, and the high mobility group box 1 (HMGB1) concentration was studied by Western blot analysis. Tetrandrine suppressed the LPS-induced increase of TNF-alpha, IL-1beta, and HMGB1 secretion by peritoneal macrophages but did not affect the IL-6 and IL-10 concentrations. The animals treated with tetrandrine either 1 hour before or after LPS injection had a 100% survival rate, which was significantly higher than that of the control group (40%) (p = 0.005). The LPS-induced increase in serum TNF-alpha, IL-1beta, and HMGB1 concentrations was reduced by tetrandrine treatment administered either 1 hour before or after LPS injection (p < 0.0001). In contrast, tetrandrine prolonged the LPS-induced elevation in serum IL-10 concentrations only mildly changed the serum IL-6 concentrations. Tetrandrine treatment either 1 hour before or 1 hour after LPS injection reduced the mortality rate of the mice with LPS-induced endotoxemia. The effects of tetrandrine on LPS-induced endotoxemia might be related to the suppression of TNF-alpha, IL-1beta, and HMGB1 concentrations.

Bench-to-bedside review: High-mobility group box 1 and critical illness

High-mobility group box 1 (HMGB1) is a DNA-binding protein that also exhibits proinflammatory cytokine-like activity. HMGB1 is passively released by necrotic cells and also is actively secreted by immunostimulated macrophages, dendritic cells, and enterocytes. Although circulating HMGB1 levels are increased relative to healthy controls in patients with infections and severe sepsis, plasma or serum HMGB1 concentrations do not discriminate reliably between infected and uninfected critically ill patients. Nevertheless, administration of drugs that block HMGB1 secretion or of anti-HMGB1 neutralizing antibodies has been shown to ameliorate organ dysfunction and/or improve survival in numerous animal models of critical illness. Because HMGB1 tends to be released relatively late in the inflammatory response (at least in animal models of endotoxemia or sepsis), this protein is an attractive target for the development of new therapeutic agents for the treatment of patients with various forms of critical illness.

New high mobility group box 1 assay system

Background High-sensitivity sandwich ELISA methods have been developed using chemiluminescent substrates. HMGB1 (high mobility group box 1) protein has been shown to play a critical role in several inflammatory diseases and it may be involved in the development of atherosclerosis. Methods Anti-human HMGB1 monoclonal antibodies and anti-peptide polyclonal antibodies against the peptide sequence (KPDAAKKGVVKAEK) with high antigenicity and different from the sequence of HMGB2 were developed, and the antibodies were used to construct sandwich ELISA methods with a chromogenic substrate (TMBZ) and a chemiluminescent substrate (PS-atto). Highly purified human HMGB1 was used as a standard material and high-sensitivity CRP was measured to compare with HMGB1. Results The analytical characteristics of the ELISA method we developed were validated inter-assay and intra-assay CVs were < 10%, and the detection limit was 0.3 μg/l by the chemiluminescent method and 1 μg/l with the chromogenic substrates. HMGB1 was detected in the serum of patients with acute coronary syndrome (ACS). When a cut-off of 0.6 μg/l HMGB1 upon admission to the intensive care unit (ICU) was used, the risk of developing an acute cardiac event within 1 month after discharge of ACS patients with an abnormal HMGB1 was significantly higher than for the patients with normal values ( P < 0.0001). The usefulness of HMGB1 as an acute prognostic marker was suggested. Conclusions The assay is easy to perform and suitable for use in the hospital laboratory and for screening large populations. HMGB1 is detectable in the serum of ACS patients and that the serum concentration of HMGB1 may be a prognostic indicator in ACS patients.

Dynamic Defense System Against HMGB1, a Proinflammatory and Lethal Mediator in Severe Infections and Malignancies.

High Mobility Group box 1(HMGB1) is an abundant DNA-binding protein that acts as a proinflammatory cytokine when released in the extracellular milieu by necrotic and inflammatory cells. Moreover, an increased HMGB1 in the circulation of septic patients may induce multi-organ failure and lethality. However, very recent observations suggest that the protein also acts as an innate adjuvant, stem cell chemoattractant and growth factor. Thus only systemic and circulatory HMGB1 may induce morbidity and mortality, however, localized HMGB1 may have beneficial effects. Therefore, we serially examined the serum HMGB1 level in patients with various diseases, and also evaluated the significance of the protein.We demonstrate here how HMGB1 is localized and acts as an immune-adjuvant and a repairing factor in damaged tissue. We first established specific ELISA method to measure HMGB1. An increased level of HMGB1 was detected in the serum from patients with sever sepsis, infections, malignancy and so on. However, serum HMGB1 concentrations were fluctuated during the clinical course, and could not be concluded as a lethal mediator as previously reported. Next we investigated the reason of dynamic fluctuations of the protein in the circulation. Based on our findings, we proposed that this fluctuation of HMGB1 concentrations may be mediated by at least following three fashions; 1) proteolytic degradation by plasmin and thrombin, 2) endothelial thrombomodulin(TM) adsorption, and 3) generation of antibody against the protein. We observed that plasmin efficiently degraded HMGB1 into small fragments. However, interestingly the generated fragments of the protein still possess an ability to produce TNFa in macrophages through an undefined pathway. TM binds the protein on its N-terminus lectin-like domain. Binding of HMGB1 to TM resulted in decrement of TM's cofactor activity to activate protein C by thrombin. HMGB1 bound to TM was gradually degraded by thrombin. These may be a system to localize HMGB1 only in injury sites where TM is down-regulated or disappeared through endothelial-loss. This may exert endothelial defense system against extracellular HMGB1 in severe tissue injury. Another possibility is that the generated antibody against HMGB1 may neutralize the proinflammatory action of the protein. In this context, we found that some of the antibodies against HMGB1 have the characteristics of P-ANCA(perinuclear anti-neutrophil cytoplasmic antibody). This may alter the phenotype of the underlining diseases. In conclusion, we suggest that HMGB1 is not merely a lethal mediator, but a kind of “testament” mediator of cell necrosis or invasive attacks to dendritic cells.