Inhibition Of High-mobility Group Box 1 Activity Research Articles

Paeonol ameliorates CFA-induced inflammatory pain by inhibiting HMGB1/TLR4/NF-κB p65 pathway.

The enhanced release of inflammatory cytokines mediated by high mobility group box1 (HMGB1) leads to pain sensation, and has been implicated in the etiology of inflammatory pain. Paeonol (PAE), a major active phenolic component in Cortex Moutan, provides neuroprotective efficacy via exerting anti-inflammatory effect. However, the role and mechanism of PAE in inflammatory pain remain to be fully clarified. In this study, we showed that PAE treatment significantly ameliorated mechanical and thermal hyperalgesia of mice induced by complete Freund's adjuvant (CFA). The analgesic effect of PAE administration was associated with suppressing the enhanced expression of HMGB1 as well as the downstream signaling molecules including toll-like receptor 4 (TLR4), the nuclear NF-κB p65, TNF-α and IL-1β after CFA insult in the anterior cingulate cortex (ACC), a key brain region responsible for pain processing. Furthermore, inhibition of HMGB1 activity by glycyrrhizin (GLY), an HMGB1 inhibitor, alleviated CFA-induced pain and also facilitated PAE-mediated analgesic effect in mice along with the decreased expression of TLR4, NF-κB p65, TNF-α and IL-1β upon CFA injury. Collectively, we showed PAE exerted analgesic effect through inhibiting the HMGB1/TLR4/NF-κB p65 pathway and subsequent generation of cytokines TNF-α and IL-1β in the ACC.

Minocycline prevents the depressive-like behavior through inhibiting the release of HMGB1 from microglia and neurons

BackgroundOur previous study reports the causal role of high mobility group box 1 (HMGB1) in the development of depression; and we find glycyrrhizic acid (GZA) can be a potential treatment for major depressive disorder (MDD) considering its inhibition of HMGB1 activity. This study aims to further explore the exact cell types that release HMGB1 in the hippocampus. MethodsWe detected the effects of microglia conditioned medium on primary astrocytes and neurons. The effects of minocycline on depressive-like behaviors were tested in BABLB/c mice after four weeks of chronic unpredictable mild stress (CUMS) exposure. Furthermore, the immunofluorescence (IF) assays, hematoxylin-eosin (HE) and TUNEL staining were used to observe hippocampal slices to evaluate the release of HMGB1. The cytoplasmic translocations of HMGB1 protein were assayed by western-blot. ResultsExposure to CUMS caused an active release of HMGB1 from microglia and neurons in the hippocampus. After minocycline administration for inhibiting the activation of microglia, both microglia and neurons reduced the release of HMGB1 and the protein level of central and peripheral HMGB1 recovered accordingly. Along with blocking the release of HMGB1, behavioral and cognitive deficits induced by CUMS were improved significantly by minocycline. In addition, the supernatant of primary microglia stimulated the secretion of HMGB1 in primary neurons, not in astrocytes, at 24 h after 4 h-LPS treatment. ConclusionAll the evidence supported our hypotheses that microglia and neurons are the main cell sources of HMGB1 release under CUMS condition, and that the release of HMGB1 by microglia may play an important role in the development of depressive-like behavior.

HMGB1 release from trophoblasts contributes to inflammation during Brucella melitensis infection.

Brucella melitensis infection causes acute necrotizing inflammation in pregnant animals; however, the pathophysiological mechanisms leading to placentitis are unknown. Here, we demonstrate that high-mobility group box 1 (HMGB1) acts as a mediator of placenta inflammation in B.melitensis-infected pregnant mice model. HMGB1 levels were increased in trophoblasts or placental explant during B.melitensis infection. Inhibition of HMGB1 activity with neutralising antibody significantly reduced the secretion of inflammatory cytokines in B.melitensis-infected trophoblasts or placenta, whereas administration of recombinant HMGB1 (rHMGB1) increased the inflammatory response. Mechanistically, this decreased inflammatory response results from inhibition of HMGB1 activity, which cause the suppression of both mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. Moreover, neutralising antibody to HMGB1 prevented B.melitensis infection-induced activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in trophoblasts. In contrast, in vitro stimulation of trophoblasts with rHMGB1 caused activation of NADPH oxidase and increased the production of ROS, which contributes to high bacterial burden within trophoblasts or placenta. In vivo, treatment with anti-HMGB1 antibody increases the number of Brucella survival within placenta in B.melitensis-infected pregnant mice but successfully reduced the severity of placentitis and abortion.

Aspirin delays mesothelioma growth by inhibiting HMGB1-mediated tumor progression.

High-mobility group box 1 (HMGB1) is an inflammatory molecule that has a critical role in the initiation and progression of malignant mesothelioma (MM). Aspirin (acetylsalicylic acid, ASA) is the most widely used nonsteroidal anti-inflammatory drug that reduces the incidence, metastatic potential and mortality of many inflammation-induced cancers. We hypothesized that ASA may exert anticancer properties in MM by abrogating the carcinogenic effects of HMGB1. Using HMGB1-secreting and -non-secreting human MM cell lines, we determined whether aspirin inhibited the hallmarks of HMGB1-induced MM cell growth in vitro and in vivo. Our data demonstrated that ASA and its metabolite, salicylic acid (SA), inhibit motility, migration, invasion and anchorage-independent colony formation of MM cells via a novel HMGB1-mediated mechanism. ASA/SA, at serum concentrations comparable to those achieved in humans taking therapeutic doses of aspirin, and BoxA, a specific inhibitor of HMGB1, markedly reduced MM growth in xenograft mice and significantly improved survival of treated animals. The effects of ASA and BoxA were cyclooxygenase-2 independent and were not additive, consistent with both acting via inhibition of HMGB1 activity. Our findings provide a rationale for the well documented, yet poorly understood antitumorigenic activity of aspirin, which we show proceeds via HMGB1 inhibition. Moreover, the use of BoxA appears to allow a more efficient HMGB1 targeting while eluding the known gastrointestinal side effects of ASA. Our findings are directly relevant to MM. Given the emerging importance of HMGB1 and its tumor-promoting functions in many cancer types, and of aspirin in cancer prevention and therapy, our investigation is poised to provide broadly applicable information.

The nuclear factor HMGB1 mediates hepatic injury after murine liver ischemia-reperfusion

High-mobility group box 1 (HMGB1) is a nuclear factor that is released extracellularly as a late mediator of lethality in sepsis as well as after necrotic, but not apoptotic, death. Here we demonstrate that in contrast to the delayed role of HMGB1 in the systemic inflammation of sepsis, HMGB1 acts as an early mediator of inflammation and organ damage in hepatic ischemia reperfusion (I/R) injury. HMGB1 levels were increased during liver I/R as early as 1 h after reperfusion and then increased in a time-dependent manner up to 24 h. Inhibition of HMGB1 activity with neutralizing antibody significantly decreased liver damage after I/R, whereas administration of recombinant HMGB1 worsened I/R injury. Treatment with neutralizing antibody was associated with less phosphorylation of c-Jun NH2-terminal kinase and higher nuclear factor–κB DNA binding in the liver after I/R. Toll-like receptor 4 (TLR4)-defective (C3H/Hej) mice exhibited less damage in the hepatic I/R model than did wild-type (C3H/HeOuj) mice. Anti-HMGB1 antibody failed to provide protection in C3H/Hej mice, but successfully reduced damage in C3H/Ouj mice. Together, these results demonstrate that HMGB1 is an early mediator of injury and inflammation in liver I/R and implicates TLR4 as one of the receptors that is involved in the process.

High-mobility group box 1 inhibition protects against hepatic ischemia-reperfusion injury

Introduction. Hepatic ischemia followed by reperfusion (I/R) occurs in the settings of trauma, transplantation, and elective liver resections. The mechanisms that account for local organ damage are only partially understood. High-mobility group box 1 (HMGB1) has been identified as a late mediator of lethality in sepsis and is released by damaged tissues where it could also act as a mediator of inflammation and organ injury. We hypothesized that HMGB1 would contribute to organ injury following hepatic I/R. Methods. HMGB1 protein expression and hepatocellular secretion were determined in rat hepatocytes subjected to hypoxia (1% O 2) versus normoxic cells. The role of HMGB1 in mediating hepatic I/R injury was examined in C57Bl/6 mice that underwent 90 min of partial I/R injury. These mice were pretreated with neutralizing HMGB1 antibody (600 μg) or control normal saline 1 h prior to ischemia. Results. Basal HMGB1 expression was observed in normoxic hepatocytes and was dramatically up regulated 12–24 h after hypoxia. This corresponded to increased HMGB1 secretion 18–24 h after hypoxia. In mice undergoing partial warm liver I/R injury, HMGB1 protein expression is increased as early as 1 h after reperfusion and then increases in a time-dependent manner up to 24 h. Inhibition of HMGB1 activity with neutralizing antibody significantly decreased liver damage after warm ischemia compared to control animals. TABLE—ABSTRACT 81 Group ALT-1 h ALT-6 h ALT-24h Sham 67 ± 24 57 ± 8 51 ± 2 Control 3101 ± 1167 8140 ± 1656 905 ± 65 Anti-HMGB1 662 ± 120 ∗ 2382 ± 687 ∗ 265 ± 16 ∗ Note. Data are mean ± SEM, n = 3–4 per group; ∗ indicates P < 0.05 versus control. Conclusion. This study demonstrates that HMGB1 is up regulated in hepatocytes by simple hypoxia. The same was seen to occur in vivo in liver I/R as early as 1 h. The reduction in liver damage by a neutralizing antibody shows that HMGB1 is a key mediator in the pathways that lead to organ damage in warm liver I/R. Thus, unlike sepsis where HMGB1 is late mediator, this danger protein appears to be an early mediator in I/R.