A pilot study to detect high mobility group box 1 and heat shock protein 72 in cerebrospinal fluid of pediatric patients with meningitis

Potential significance of high-mobility group protein box 1 in cerebrospinal fluid

High-mobility group protein box 1 (HMGB1) is a cytokine with multiple functions (according to its subcellular location) that serves a marker of inflammation. CSF HMGB1 could be the part of pathological mechanisms that underlie the complications associated with CNS diseases. HMGB1 actively or passively released into the CSF is detected in the CSF in many diseases of the central nervous system (CNS) and thus may be useful as a biomarker. Pathological alterations in distant areas were observed due to lesions in a specific region, and the level of HMGB1 in the CSF was found to be elevated. Reducing the HMGB1 level via intraventricular injection of anti-HMGB1 neutralizing antibodies can improve the outcomes of CNS diseases. The results indicated that CSF HMGB1 could serve as a biomarker for predicting disease progression and may also act as a pathogenic factor contributing to pathological alterations in distant areas following focal lesions in the CNS. In this mini-review, the characteristics of HMGB1 and progress in research on CSF HMGB1 as a biomarker of CNS diseases were discussed. CSF HMGB1 is useful not only as a biomarker of CNS diseases but may also be involved in interactions between different brain regions and the spinal cord.

ADAMTS-13 and HMGB1-induced oxidative stress in Taenia multiceps-infected animals

This study investigated the cytotoxic effects of oxidative stress (OS), high mobility group box 1 (HMGB1), ADAMTS (A disintegrin and metalloproteinase with thrombospondin motifs), and neuropathology associated with coenurus cerebralis (Taenia multiceps). ADAMTS-13, HMGB1, glutathione reductase (GR), copper/zinc superoxide dismutase (Cu/Zn SOD), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) expression levels were studied. The study found that ADAMTS-13 (P < 0.005), HMGB1 (P < 0.005), GR (P < 0.005), Cu/Zn SOD (P < 0.005), and 8-OHdG (P < 0.005) levels were significantly higher in T. multiceps (c. cerebralis)-infected animals compared to healthy control animals. This study's most important finding was that HMGB1 up-regulation in neurons, endothelial cells, and glial cells can directly cause brain parenchymal destruction and that HMGB1-mediated oxidative stress plays a crucial role in the neuropathogenesis of coenurosis. The results also showed that increased levels of ADAMTS-13 may play a pivotal role in regulating and protecting the blood-brain barrier integrity and neuroprotection. These findings also suggest that ADAMTS-13 and HMGB1 compete in the prevention or formation of microthrombi, which was regarded as a remarkable finding. ADAMTS-13 and HMGB1 are valuable biomarkers for disease risk assessment, estimating host neuropathy following T. multiceps (c. cerebralis) exposure, and providing a new therapeutic target. This is the first study to show that HMGB1 and ADAMTS-13 are expressed in reactive cells and are associated with neuroimmunopathology in coenurosis.

Urinary HSP70 improves diagnostic accuracy for urinary tract infection in children: UTILISE study

BACKGROUND

The accuracy of conventional urinalysis in diagnosing urinary tract infection (UTI) in children is limited, leading to unnecessary antibiotic exposure in a large fraction of patients. Urinary heat shock protein 70 (uHSP70) is a novel marker of acute urinary tract inflammation. We explored the added value of uHSP70 in discriminating UTI from other infections and conditions confused with UTI.

METHODS

A total of 802 children from 37 pediatric centers in seven countries participated in the study. Patients diagnosed with UTI (n = 191), non-UTI infections (n = 178), contaminated urine samples (n = 50), asymptomatic bacteriuria (n = 26), and healthy controls (n = 75) were enrolled. Urine and serum levels of HSP70 were measured at presentation in all patients and after resolution of the infection in patients with confirmed UTI.

RESULTS

Urinary (u)HSP70 was selectively elevated in children with UTI as compared to all other conditions (p < 0.0001). uHSP70 predicted UTI with 89% sensitivity and 82% specificity (AUC = 0.934). Among the 265 patients with suspected UTI, the uHSP70 > 48 ng/mL criterion identified the 172 children with subsequently confirmed UTI with 90% sensitivity and 82% specificity (AUC = 0.862), exceeding the individual diagnostic accuracy of leukocyturia, nitrite, and leukocyte esterase positivity. uHSP70 had completely normalized by the end of antibiotic therapy in the UTI patients. Serum HSP70 was not predictive.

CONCLUSIONS

Urine HSP70 is a novel non-invasive marker of UTI that improves the diagnostic accuracy of conventional urinalysis. We estimate that rapid urine HSP70 screening could spare empiric antibiotic administration in up to 80% of children with suspected UTI. A higher resolution version of the Graphical abstract is available as Supplementary information.

miR-141-3p inhibits the activation of astrocytes and the release of inflammatory cytokines in bacterial meningitis through down-regulating HMGB1

BACKGROUND

Bacterial meningitis (BM) is a serious infectious disease of the central nervous system that often occurs in children and adolescents. Many studies have suggested that microRNAs (miRNAs) are involved in BM. This study aimed to address the effects of miR-141-3p on astrocyte activation and inflammatory response in BM through HMGB1.

METHODS

The 3-week-old rats were injected with Streptococcus pneumoniae (SP) into the lateral ventricle to establish a BM model. Loeffler scoring method was used to evaluate the recovery of neurological function. Brain pathological damage was observed by hematoxylin and eosin (H&E) staining. Primary astrocytes were isolated from brain tissues of BM or non-infected SD rats. The levels of TNF-α, IL-1β, and IL-6 in brain tissues and astrocyte culture supernatant were measured by enzyme-linked immunosorbent assay (ELISA). The targeting relationship between miR-141-3p and HMGB1 was tested using dual-luciferase reporter assay. The expression of miR-141-3p, HMGB1, and the astrocytic marker glial fibrillary acidic protein (GFAP) were detected by quantitative real-time polymerase chain reaction (qRT-PCR) or western blotting. Methylation-specific PCR (MSP) analysis was performed to measure the methylation status of miR-141 promoter.

RESULTS

The results showed that lower Loeffler scores were exhibited in rats with BM. The subarachnoid space of brain tissues of BM rats was widened, and obvious inflammatory cells were observed. miR-141-3p expression was reduced in BM rats and SP-treated astrocytes. Additionally, we found that overexpression of miR-141-3p led to the downregulation of HMGB1, GFAP, and inflammatory cytokines (TNF-α, IL-1β, and IL-6) in astrocytes. Furthermore, the results of dual-luciferase reporter assay confirmed that miR-141-3p directly targeted HMGB1. Overexpression of miR-141-3p inhibited the levels of GFAP, TNF-α, IL-1β, and IL-6 in astrocytes, which was eliminated by the up-regulation of HMGB1. The results of MSP analysis indicated that miR-141 promoter was highly methylated in brain tissues and astrocytes. DNMT1 was involved in the methylation of miR-141 promoter in BM.

CONCLUSION

The present study verified that miR-141-3p affected inflammatory response by suppressing HMGB1 in SP-induced astrocytes and BM rat model.

High mobility group box 1 and angiogenetic growth factor levels in children with central nerve system infections

INTRODUCTION

To clarify the pathology of children with acute encephalopathy and other neurological disorders, the involvement of high-mobility group box 1 (HMGB1), which is a representative of danger-associated molecular patterns, and angiogenesis-related growth factors were investigated.

PATIENTS AND METHODS

Participants were 12 children with acute encephalopathy (influenza, rotavirus, and others), 7 with bacterial meningitis, and 6 with epilepsy disease (West syndrome). Twenty-four patients with non-central nervous system (CNS) infections as a control group were admitted to our hospital. We examined the levels of HMGB1, platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and other cytokines in the serum and cerebrospinal fluid (CSF) of the subjects.

RESULTS

Serum and CSF HMGB1 levels were significantly higher in the encephalopathy and meningitis groups than in the West syndrome and control groups. CSF HMGB1 levels correlated with those of interleukin-6 and -8. CSF HMGB1 and VEGF levels were correlated, and PDGF showed a positive relationship.

CONCLUSION

HMGB1 and angiogenesis-related growth factors appear to play pivotal roles in the pathophysiology of CNS infections.

High-mobility group box-1 protein as a novel biomarker to diagnose healthcare-associated ventriculitis and meningitis: a pilot study

BACKGROUND

The diagnosis of healthcare-associated ventriculitis and meningitis (HAVM) is challenging in the ICU setting. Traditional cerebrospinal fluid (CSF) markers and clinical signs of infection fail to diagnose HAVM in the critically ill setting. We sought to determine the diagnostic accuracy of measuring levels of high-mobility group box 1 (HMGB1) protein in cerebrospinal fluid (CSF) for the diagnosis of HAVM.

METHODS

In this prospective observational cohort study, we enrolled 29 patients with an implanted external ventricular drainage (EVD). We tested the accuracy of CSF-HMGB1 as a diagnostic test for HAVM when compared to standard CSF parameters.

RESULTS

HAVM was diagnosed in 11/29 (37.9%) patients. These patients had significantly higher CSF-HMGB1 levels compared to patients without HAVM (median [IQR] 43.39 [83.51] ng/mL vs 6.46 ng/mL [10.94]; P<0.001). CSF-HMGB1 and CSF-glucose were independently related to HAVM, with OR's (95% CI) of 15.43 (15.37 to 15.48, P<0.0001) and 0.31 (0.30 to 0.32, P<0.0001), respectively. The AUC [CI] of CSF-HMGB1 to predict HAVM was 0.83 [0.72 to 0.94].

CONCLUSIONS

HMGB1 is an accurate marker of HAVM and it adds incremental diagnostic value when paired with CSF-glucose measurements. Future larger and multicenter studies should assess the incremental diagnostic value of HMGB1 data when used alongside other established CSF markers of infection, and the external validity of these preliminary results.

The performance of the alarmin HMGB1 in pediatric diseases: From lab to clinic

INTRODUCTION

The ubiquitously expressed nonhistone nuclear protein high-mobility group box protein 1 (HMGB1) has different functions related to posttranslational modifications and cellular localization. In the nucleus, HMGB1 modulates gene transcription, replication and DNA repair as well as determines chromosomal architecture. When the post-transcriptional modified HMGB1 is released into the extracellular space, it triggers several physiological and pathological responses and initiates innate immunity through interacting with its reciprocal receptors (i.e., TLR4/2 and RAGE). The effect of HMGB1-mediated inflammatory activation on different systems has received increasing attention. HMGB1 is now considered to be an alarmin and participates in multiple inflammation-related diseases. In addition, HMGB1 also affects the occurrence and progression of tumors. However, most studies involving HMGB1 have been focused on adults or mature animals. Due to differences in disease characteristics between children and adults, it is necessary to clarify the role of HMGB1 in pediatric diseases.

METHODS AND RESULTS

Through systematic database retrieval, this review aimed to first elaborate the characteristics of HMGB1 under physiological and pathological conditions and then discuss the clinical significance of HMGB1 in the pediatric diseases according to different systems.

CONCLUSIONS

HMGB1 plays an important role in a variety of pediatric diseases and may be used as a diagnostic biomarker and therapeutic target for new strategies for the prevention and treatment of pediatric diseases.

Involvement of high mobility group box 1 in the pathogenesis of severe hemolytic uremic syndrome in a murine model

Typical hemolytic uremic syndrome is caused by Shiga toxin (Stx2) and lipopolysaccharide (LPS) of Escherichia coli and leads to acute kidney injury. The role of innate immunity in this pathogenesis is unclear. We analyzed the role of high mobility group box 1 (HMGB1) at the onset of disease in a murine model. C57BL/6 mice were intraperitoneally administered saline ( group A), anti-HMGB1 monoclonal antibody ( group B), Stx2 and LPS to elicit severe disease ( group C), or Stx2, LPS, and anti-HMGB1 antibody ( group D). While all mice in group C died by day 5 of the experiment, all mice in group D survived. Anemia and thrombocytopenia were pronounced and plasma creatinine levels were significantly elevated in group C only at 72 h. While at 72 h after toxin administration the glomerulus tissue in group C showed pathology similar to that of humans, mesangial cell proliferation was seen in group D. Plasma HMGB1 levels in group C peaked 3 h after administration and were higher than those in other groups. Expression of the receptor of advanced glycation end products and NF-κB, involved in HMGB1 signaling, was significantly elevated in group C but not in group D. Administration of anti-HMGB1 antibody in a murine model of severe disease inhibited plasma HMGB1 and promoted amelioration of tissue damage. HMGB1 was found to be involved in the disease pathology; therefore, controlling HMGB1 activity might inhibit disease progression.

Circulating level of high mobility group box‑1 predicts the severity of community‑acquired pneumonia: Regulation of inflammatory responses via the c‑Jun N‑terminal signaling pathway in macrophages

High mobility group box‑1 (HMGB‑1) has been reported to serve significant roles in various inflammatory diseases. However, the correlation between the circulating level of HMGB‑1 and severity of community‑acquired pneumonia (CAP) remains unclear. The present study investigated differential alterations in plasma HMGB‑1 levels of patients with CAP prior to and following antibiotic treatment, and further analyzed the association between CAP severity and HMGB‑1 levels. Furthermore, lipopolysaccharide (LPS)‑induced HMGB‑1 expression in RAW264.7 macrophages and the relevant signaling pathways were examined. Plasma HMGB‑1 levels of 90 patients with CAP and 52 healthy controls were measured using a commercial ELISA. The levels of plasma HMGB‑1 were significantly elevated in CAP patients compared with the controls, and antibiotic treatment was effective in reducing HMGB‑1 levels. Plasma HMGB‑1 correlated with the pneumonia severity index score (r=0.566, P<0.001). Furthermore, LPS‑stimulation significantly upregulated HMGB‑1 secretion via the c‑Jun N‑terminal kinase (JNK) signaling pathway in RAW264.7 macrophages, whereas pretreatment with the JNK inhibitor SP600125 markedly downregulated LPS‑induced HMGB‑1 levels. In conclusion, plasma HMGB‑1 levels may serve a role in the diagnosis and clinical assessment of CAP severity. These findings may provide information on novel targets for the treatment of CAP.

HMGB1 is negatively correlated with the development of endometrial carcinoma and prevents cancer cell invasion and metastasis by inhibiting the process of epithelial-to-mesenchymal transition

High-mobility group box protein 1 (HMGB1), a nuclear protein that plays a significant role in DNA architecture and transcription, was correlated with the progression of some types of cancer. However, the role of HMGB1 in endometrial cancer cell invasion and metastasis remains unexplored. HMGB1 expression was initially assessed by immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in normal endometrial tissue and endometrial carcinoma tissue. High expressions of HMGB1 protein were detected in normal endometrial tissues; however, in endometrial cancer tissues, the expressions of HMGB1 were found to be very weak. Furthermore, HMGB1 expressions were negatively correlated with advanced stage and lymph node metastasis in endometrial cancer. Then by RT-qPCR, Western blot and immunocytochemistry, HMGB1 was also detected in primary cultured endometrial cells and four kinds of endometrial cancer cell lines (Ishikawa, HEC-1A, HEC-1B and KLE). We found that the expression of HMGB1 was much higher in normal endometrial cells than in endometrial cancer cells, and reduced expression levels of HMGB1 were observed especially in the highly metastatic cell lines. Using lentivirus transfection, HMGB1 small hairpin RNA was constructed, and this infected the lowly invasive endometrial cancer cell lines, Ishikawa and HEC-1B. HMGB1 knockdown significantly enhanced the proliferation, invasion and metastasis of endometrial cancer cells and induced the process of epithelial-to-mesenchymal transition. These results can contribute to the development of a new potential therapeutic target for endometrial cancer.

A comparison of HMGB1 concentrations between cerebrospinal fluid and blood in patients with neurological disease

AIMS

To determine whether a correlation exists between paired cerebrospinal fluid (CSF) and serum levels of a novel inflammatory biomarker, high-mobility group box 1 (HMGB1), in different neurological conditions.

METHODS

HMGB1 was measured in the serum and CSF of 46 neurological patients (18 idiopathic intracranial hypertension [IIH], 18 neurological infection/inflammation [NII] and 10 Rasmussen's encephalitis [RE]).

RESULTS

Mean serum (± SD) HMGB1 levels were 1.43 ± 0.54, 25.28 ± 27.9 and 1.89 ± 1.49 ng/ml for the patients with IIH, NII and RE, respectively. Corresponding mean (± SD) CSF levels were 0.35 ± 0.22, 4.48 ± 6.56 and 2.24 ± 2.35 ng/ml. Both CSF and serum HMGB1 was elevated in NII. Elevated CSF HMGB1 was demonstrated in RE. There was no direct correlation between CSF and serum levels of HMGB1.

CONCLUSION

Serum HMGB1 cannot be used as a surrogate measure for CSF levels. CSF HMGB1 was elevated in NII and RE, its role as a prognostic/stratification biomarker needs further study.

Neogambogic acid prevents silica-induced fibrosis via inhibition of high-mobility group box 1 and MCP-1-induced protein 1

BACKGROUND

Silicosis is a systemic disease caused by inhaling silicon dioxide (SiO2); early stages are characterized by alveolar inflammation, and later stages are characterized by progressive lung fibrosis. Mounting evidence indicates that high-mobility group box 1 (HMGB1) is involved in pulmonary fibrosis. Whether neogambogic acid (NGA) inhibits macrophage and fibroblast activation induced by SiO2 by targeting HMGB1 remains unclear.

METHODS AND RESULTS

Experiments using cultured mouse macrophages (RAW264.7 cells) demonstrated that SiO2 treatment induces the expression of HMGB1 in a time- and dose-dependent manner via mitogen-activated protein kinases (MAPKs) and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway; in turn, this expression causes macrophage apoptosis and fibroblast activation. Pretreating macrophages with NGA inhibited the HMGB1 expression induced by SiO2 and attenuated both macrophage apoptosis and fibroblast activation. Moreover, NGA directly inhibited MCP-1-induced protein 1 (MCPIP1) expression, as well as markers of fibroblast activation and migration induced by SiO2. Furthermore, the effects of NGA on macrophages and fibroblasts were confirmed in vivo by exposing mice to SiO2.

CONCLUSION

NGA can prevent SiO2-induced macrophage activation and apoptosis via HMGB1 inhibition and SiO2-induced fibrosis via the MCPIP1 pathway. Targeting HMGB1 and MCPIP1 with NGA could provide insights into the potential development of a therapeutic approach for alleviating the inflammation and fibrosis induced by SiO2.

Urine heat shock protein 70 levels as a marker of urinary tract infection in children

BACKGROUND

Heat shock proteins (HSPs) are a multi-family group of proteins which are upregulated by the cell in response to exposure to hazardous (stress) factors, including infectious agents, to prevent changes in protein structure. The aim of our study was to assess whether urine levels of the 70-kDa family of HSPs (HSP70s) increase in children with urinary tract infection (UTI) and to determine the optimal urine (u) HSP70 cut-off level to predict UTI in children.

METHODS

Forty patients with symptomatic UTI (UTI group), 30 healthy children (control group), 21 asymptomatic patients with proven bacterial contamination in their urine culture (contamination group) and 30 patients with fever caused by other infections (non-UTI infection group) were enrolled in the study. Random urine samples were obtained for measurement of HSP70 and creatinine (Cr) from all groups. Urine was collected prior to the treatment of UTI at the time of presentation and after treatment. Urine HSP70 levels were measured by enzyme-linked immunosorbent analysis. A dimercaptosuccinic acid (DMSA) scan was performed at 5-7 days after presentation in UTI group to distinguish patients with acute pyelonephritis from those with cystitis; based on this scan, no patients had acute pyelonephritis. Patients were classified with pyelonephritis in the presence of all of the following signs: axillary fever of ≥39 °C, leukocytosis and positivity for C-reactive protein.

RESULTS

The mean urine HSP70:Cr ratio (uHSP70/Cr) prior to treatment was significantly higher in the UTI group (449.86 ± 194.33 pg/mg) than in the control, contamination and non-UTI infection groups (39.93 ± 47.61, 32.43 ± 9.09 and 45.14 ± 19.76, respectively; p = 0.0001). Using a cut-off of 158 pg/mg uHSP70/Cr for the prediction of UTI, the sensitivity and specificity of the assay were 100 and 100 %, respectively (area under the time-concentration curve = 1). The uHSP70/Cr was highest in the patients with clinical pyelonephritis (p = 0.001). Mean uHSP70/Cr after treatment decreased to 60.68 ± 51.11 pg/mg in UTI group (p = 0 .0001).

CONCLUSIONS

Our findings suggest that elevated uHSP70/Cr may be a useful biomarker for the prediction of UTI in children, with a high sensitivity and specificity, and that they may help to distinguish UTI from other infections as well as bacterial contamination of the urine.

Edaravone attenuates hippocampal damage in an infant mouse model of pneumococcal meningitis by reducing HMGB1 and iNOS expression via the Nrf2/HO-1 pathway

AIM

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) is a free radical scavenger that has shown potent antioxidant, anti-inflammatory and neuroprotective effects in variety of disease models. In this study, we investigated whether edaravone produced neuroprotective actions in an infant mouse model of pneumococcal meningitis.

METHODS

C57BL/6 mice were infected on postnatal d 11 by intracisternal injection of a certain inoculum of Streptococcus pneumoniae. The mice received intracisternal injection of 10 μL of saline containing edaravone (3 mg/kg) once a day for 7 d. The severity of pneumococcal meningitis was assessed with a clinical score. In mice with severe meningitis, the survival rate from the time of infection to d 8 after infection was analyzed using Kaplan-Meier curves. In mice with mild meningitis, the CSF inflammation and cytokine levels in the hippocampus were analyzed d 7 after infection, and the clinical neurological deficit score was evaluated using a neurological scoring system d 14 after infection. The nuclear factor (erythroid-derived 2)-like 2 knockout (Nrf2 KO) mice and heme oxygenase-1 knockout (HO-1 KO) mice were used to confirm the involvement of Nrf2/HO-1 pathway in the neuroprotective actions of edaravone.

RESULTS

In mice with severe meningitis, edaravone treatment significantly increased the survival rate (76.4%) compared with the meningitis model group (32.2%). In mice with mild meningitis, edaravone treatment significantly decreased the number of leukocytes and TNF- levels in CSF, as well as the neuronal apoptosis and protein levels of HMGB1 and iNOS in the hippocampus, but did not affect the high levels of IL-10 and IL-6 in the hippocampus. Moreover, edaravone treatment significantly improved the neurological function of mice with mild meningitis. In Nrf2 KO or HO-1 KO mice with the meningitis, edaravone treatment was no longer effective in improving the survival rate of the mice with severe meningitis (20.2% and 53.6%, respectively), nor it affected the protein levels of HMGB1 and iNOS in the hippocampus of the mice with mild meningitis.

CONCLUSION

Edaravone produces neuroprotective actions in a mouse model of pneumococcal meningitis by reducing neuronal apoptosis and HMGB1 and iNOS expression in the hippocampus via the Nrf2/HO-1 pathway. Thus, edaravone may be a promising agent for the treatment of bacterial meningitis.

The implication and potential applications of high-mobility group box 1 protein in breast cancer

High-mobility group box 1 protein (HMGB1) is a highly conserved, non-histone and ubiquitous chromosomal protein found enriched in active chromatin forming part of the high mobility group family of proteins and is encoded by the HMGB1 gene (13q12) in human beings. It has various intranuclear and extracellular functions. It plays an important role in the pathogenesis of many diseases including cancer. In 2012, there was approximately 1.67 million new breast cancer cases diagnosed which makes it the second most frequent cancer in the world after lung cancer (25% of all cancers) and the commonest cancer among women. Both pre-clinical and clinical studies have suggested that HMGB1 might be a useful target in the management of breast cancer. This review summarises the structure and functions of HMGB1 and its dual role in carcinogenesis both as a pro-tumorigenic and anti-tumorigenic factor. It also sums up evidence from in vitro and in vivo studies using breast cancer cell lines and samples which demonstrate its influence in radiotherapy, chemotherapy and hormonal therapy in breast cancer. It may have particular importance in HER2 positive and metastatic breast cancer. It might pave the way for new breast cancer treatments through development of novel drugs, use of microRNAs (miRNAs), targeting breast cancer stem cells (CSCs) and breast cancer immunotherapy. It may also play a role in determining breast cancer prognosis. Thus HMGB1 may open up novel avenues in breast cancer management.

Does Infection-Induced Immune Activation Contribute to Dementia?

The central nervous system (CNS) is protected by a complex blood-brain barrier system; however, a broad diversity of virus, bacteria, fungi, and protozoa can gain access and cause illness. As pathogens replicate, they release molecules that can be recognized by innate immune cells. These molecules are pathogen-associated molecular patterns (PAMP) and they are identified by pattern-recognition receptors (PRR) expressed on antigen-presenting cells. Examples of PRR include toll-like receptors (TLR), receptors for advanced glycation endproducts (RAGE), nucleotide binding oligomerisation domain (NOD)-like receptors (NLR), c-type lectin receptors (CLR), RIG-I-like receptors (RLR), and intra-cytosolic DNA sensors. The reciprocal action between PAMP and PRR triggers the release of inflammatory mediators that regulate the elimination of invasive pathogens. Damage-associated molecular patterns (DAMP) are endogenous constituents released from damaged cells that also have the ability to activate the innate immune response. An increase of RAGE expression levels on neurons, astrocytes, microglia, and endothelial cells could be responsible for the accumulation of αβ-amyloid in dementia and related to the chronic inflammatory state that is found in neurodegenerative disorders.

Evaluation of heat shock proteins for discriminating between latent tuberculosis infection and active tuberculosis: A preliminary report

The diagnosis of a latent tuberculosis infection (LTBI) is of the utmost concern. The available tests, the tuberculin skin test (TST) and the Quantiferon-TB Gold test (QFT-G) cannot discriminate between active TB and LTBI. Therefore, the aim of the study is to identify new biomarkers that can discriminate between active TB and LTBI and can also assess the risk of the individual developing active TB. In total, 55 blood samples were collected, of which 10 samples were from the active TB infection group, 10 were from the high-risk exposure group, 23 were from the low-risk exposure group, and 12 were from healthy controls living in a non-TB endemic area. A panel of heat shock proteins (Hsps), including host Hsp25, Hsp60, Hsp70, and Hsp90 and Mycobacterium tuberculosis (MTB) Hsp16, were evaluated in all of the collected samples using ELISA. The levels of the host Hsp(s) (Hsp25, Hsp60, Hsp70 and Hsp90) and MTB Hsp16 were significantly (p<0.05) elevated in the active TB group compared to the high-risk exposure group, the low-risk exposure group and the control group. Notably, the levels of the same panel of Hsp(s) were elevated in the high-risk exposure group compared to the low-risk exposure group. On follow-up, out of the 10 high-risk exposure participants, 3 converted into active TB, indicating that this group has the highest risk of developing TB. Thus, the evaluated panel of Hsp(s) can discriminate between LTBI and active TB. They can also identify individuals who are at the highest risk of developing active TB. Because they can be rapidly detected, Hsp(s) have an edge over the existing diagnostic tools for LTBI. The evaluation of these proteins will be useful in designing better diagnostic methods for LTBI.

Thalassaemia major and infectious risk: High Mobility Group Box-1 represents a novel diagnostic and prognostic biomarker

High mobility group box -1 (HMGB1) represents a common causal agent for various types of diseases, including infective pathologies. This study aimed to investigate the role of HMGB1 in β-thalassemia major (TM) by evaluating its diagnostic and prognostic role. Fifty-one TM patients and 30 healthy subjects (HS) were enrolled. Receiver operating characteristics (ROC) analysis was employed to calculate the area under the curve (AUC) for HMGB1 to determine the best cut-off values capable of identifying infectious episodes. Adjusted risk estimates for infective events were calculated using univariate followed by multivariate Cox proportional hazard regression analysis. Serum HMGB1 levels were higher in TM patients than in HS (14·6 ± 8·7 vs. 2·08 ± 0·9 ng/ml, P < 0·0001). Patients who underwent splenectomy were characterized by lower levels of HMGB1, when compared with patients with an intact spleen (10·2 ± 8 vs. 19·1 ± 7 ng/ml, P = 0·004). ROC analyses revealed an AUC for serum HMGB1 of 0·801, with a sensitivity and specificity of 92·3% and 68·2% to detect an infectious episode. Low HMGB1 levels predicted high risk of infective events (HR: 0·81; P = 0·006). HMGB1 represents a prognostic marker for TM patients and a predictive factor for infectious events.

Immunohistochemical detection of high-mobility group box 1 correlates with resistance of preoperative chemoradiotherapy for lower rectal cancer: a retrospective study

Background

High-mobility group box 1 (HMGB1) is a nucleoprotein that is related to inflammation. It has been implicated in a variety of biologically important processes, including transcription, DNA repair, differentiation, development, and extracellular signaling. Recently, its important role in the process of tumor invasion, metastasis, and resistance to anti-cancer therapies has been demonstrated. In this study, we aimed to investigate the correlation of HMGB1 expression and resistance of rectal cancer patients to chemoradiotherapy (CRT) prior to curative operation.

Methods

We retrospectively reviewed the data of 75 lower rectal cancer patients without complete pathological response who had received preoperative CRT and had undergone curative resection at the University of Tokyo Hospital between May 2003 and June 2010. HMGB1 expression in surgically resected specimens was evaluated using immunohistochemical detection and specimens were classified into high or low HMGB1 expression groups. Clinicopathologic features, degree of tumor reduction, regression of tumor grade, and patient survival were compared between the groups using non-paired Student’s t-tests and Kaplan-Meier analysis.

Results

A total of 52 (69.3%) patients had high HMGB1 expression, and 23 (30.7%) had low expression. HMGB1 expression was significantly correlated with histologic type (P = 0.02), lymphatic invasion (P = 0.02), and venous invasion (P = 0.05). Compared to patients with low HMGB1 expression, those with high expression had a poorer response to CRT, in terms of tumor reduction ratio (42.2 versus 28.9%, respectively; P <0.01) and post-CRT histological tumor regression grade (56.5 versus 30.8% grade 2; respectively; P = 0.03). However, no significant correlation was found between HMGB1 expression and recurrence-free and overall survival rates.

Conclusions

HMGB1 expression may be one of the key factors regulating the response of rectal cancer to preoperative CRT in terms of tumor invasiveness and resistance to therapy.

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.

High-mobility group box 1 (HMGB1) in childhood: from bench to bedside

High-mobility group box protein 1 (HMGB1) is a nonhistone nuclear protein that has a dual function. Inside the cell, HMGB1 binds DNA, regulating transcription and determining chromosomal architecture. Outside the cell, HMGB1 activates the innate system and mediates a wide range of physiological and pathological responses. HMGB1 exerts these actions through differential engagement of multiple surface receptors, including Toll-like receptor (TLR)2, TLR4, and receptor for advanced glycation end products (RAGE). HMGB1 is implicated as a late mediator of sepsis and is also involved in inflammatory and autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, HMGB1 was associated with tumor progression, becoming a potential therapeutic target, due to its involvement in the resistance to chemotherapy. Its implication on the pathogenesis of systemic vasculitis and inflammatory bowel diseases has also been evaluated. Moreover, it regulates neuroinflammation after traumatic brain injuries or cerebral infectious diseases. The aim of this review is to analyze these different roles of HMGB1, both in physiological and pathological conditions, discussing clinical and scientific implications in the field of pediatrics.

CONCLUSION

HMGB1 plays a key role in several pediatric diseases, opening new scenarios for diagnostic biomarkers and therapeutic strategies development.

HMGB1 in hormone-related cancer: a potential therapeutic target

High-mobility group box 1 (HMGB1) is a dynamic nuclear protein participating in transcription, chromatin remodelling, and DNA recombination and repair processes. Accumulating evidence indicates that its function now extends beyond the nucleus, notably its extracellular role in inflammation. HMGB1 is implicated as a late mediator of sepsis and is also believed to promote atherosclerosis and other inflammatory diseases such as rheumatoid arthritis and systemic lupus erythematosus. Interestingly, deregulation of HMGB1 is shown to be associated with the hallmarks of cancer development. Moreover, several clinical studies have shown that HMGB1 is a promising biomarker for a variety of cancer types. In this review, we provide novel insights into the role and mechanisms of HMGB1, in particular, to hormone-related cancers and its potential to serve as a therapeutic target.

Heat shock proteins: possible biomarkers in pulmonary and extrapulmonary tuberculosis

Tuberculosis (TB) and Tuberculous meningitis (TBM) caused by Mycobacterium tuberculosis (MTB) continue to be a major cause of morbidity and mortality. Therefore there is a need to explore potential biomarkers and heat shock proteins [Hsp(s)] could be one such candidate. We found that host (Hsp 25, Hsp 60, Hsp 70 and Hsp 90) and MTB Hsp(s) (Hsp 16, Hsp 65 and Hsp 71) to be an important feature of the immune response in human clinical samples of pulmonary and extrapulmonary TB patients and in MTB infected monocytes. Notably, the host (Hsp 25, Hsp 70 and Hsp 90) and MTB (Hsp 16, Hsp 65 and Hsp 71) Hsp(s) increases significantly in the clinical samples as well as in cell line model after TB infection. Collectively, results revealed that alteration in immune response leads to a change in the both host and MTB Hsp profile, highlighting them as possible biomarkers for the disease.

Relationship between plasma high-mobility group box-1 levels and clinical outcomes of ischemic stroke

PURPOSE

High-mobility group box-1 (HMGB1) is regarded as a central mediator of inflammation and involved in many inflammatory diseases. This study aimed to investigate impact of plasma HMGB1 level on 1-year clinical outcomes of ischemic stroke.

METHODS

Plasma HMGB1 levels of 338 patients were quantified by enzyme-linked immunosorbent assay. The end points were mortality and unfavorable outcome (modified Rankin Scale score>2) after 1 year.

RESULTS

Plasma HMGB1 level emerged as an independent predictor of 1-year clinical outcomes. Its prognostic value was similar to National Institutes of Health Stroke Scale score's. It improved prognostic value of National Institutes of Health Stroke Scale score.

CONCLUSION

Plasma HMGB1 level represents a novel biomarker for predicting 1-year clinical outcomes of ischemic stroke.

Relationship between plasma high mobility group box-1 protein levels and clinical outcomes of aneurysmal subarachnoid hemorrhage

Background

High-mobility group box 1 (HMGB1), originally described as a nuclear protein that binds to and modifies DNA, is now regarded as a central mediator of inflammation by acting as a cytokine. However, the association of HMGB1 in the peripheral blood with disease outcome and cerebrovasospasm has not been examined in patients with aneurysmal subarachnoid hemorrhage.

Methods

In this study, 303 consecutive patients were included. Upon admission, plasma HMGB1 levels were measured by ELISA. The end points were mortality after 1 year, in-hospital mortality, cerebrovasospasm and poor functional outcome (Glasgow Outcome Scale score of 1 to 3) after 1 year.

Results

Upon admission, the plasma HMGB1 level in patients was statistically significantly higher than that in healthy controls. A multivariate analysis showed that the plasma HMGB1 level was an independent predictor of poor functional outcome and mortality after 1 year, in-hospital mortality and cerebrovasospasm. A receiver operating characteristic curve showed that plasma HMGB1 level on admission statistically significantly predicted poor functional outcome and mortality after 1 year, in-hospital mortality and cerebrovasospasm of patients. The area under the curve of the HMGB1 concentration was similar to those of World Federation of Neurological Surgeons (WFNS) score and modified Fisher score for the prediction of poor functional outcome and mortality after 1 year, and in-hospital mortality, but not for the prediction of cerebrovasospasm. In a combined logistic-regression model, HMGB1 improved the area under the curve of WFNS score and modified Fisher score for the prediction of poor functional outcome after 1 year, but not for the prediction of mortality after 1 year, in-hospital mortality, or cerebrovasospasm.

Conclusions

HMGB1 level is a useful, complementary tool to predict functional outcome and mortality after aneurysmal subarachnoid hemorrhage. However, HMGB1 determination does not add to the accuracy of prediction of the clinical outcomes.

Cerebrospinal fluid levels of high-mobility group box 1 and cytochrome C predict outcome after pediatric traumatic brain injury

High-mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that is passively released from damaged and necrotic cells, and actively released from immune cells. In contrast, cytochrome c is released from mitochondria in apoptotic cells, and is considered a reliable biomarker of apoptosis. Thus, HMGB1 and cytochrome c may in part reflect the degree of necrosis and apoptosis present after traumatic brain injury (TBI), where both are felt to contribute to cell death and neurological morbidity. Ventricular cerebrospinal fluid (CSF) was obtained from children admitted to the intensive care unit (ICU) after TBI (n=37). CSF levels of HMGB1 and cytochrome c were determined at four time intervals (0-24 h, 25-48 h, 49-72 h, and>72 h after injury) using enzyme-linked immunosorbent assay (ELISA). Lumbar CSF from children without TBI served as controls (n=12). CSF HMGB1 levels were: control=1.78±0.29, 0-24 h=5.73±1.45, 25-48 h=5.16±1.73, 49-72 h=4.13±0.75,>72 h=3.80±0.90 ng/mL (mean±SEM). Peak HMGB1 levels were inversely and independently associated with favorable Glasgow Outcome Scale (GOS) scores at 6 mo (0.49 [0.24-0.97]; OR [5-95% CI]). CSF cytochrome c levels were: control=0.37±0.10, 0-24 h=0.69±0.15, 25-48 h=0.82±0.48, 49-72 h=1.52±1.08,>72 h=1.38±1.02 ng/mL (mean±SEM). Peak cytochrome c levels were independently associated with abusive head trauma (AHT; 24.29 [1.77-334.03]) and inversely and independently associated with favorable GOS scores (0.42 [0.18-0.99]). In conclusion, increased CSF levels of HMGB1 and cytochrome c were associated with poor outcome after TBI in infants and children. These data are also consistent with the designation of HMGB1 as a "danger signal." Distinctly increased CSF cytochrome c levels in infants and children with AHT and poor outcome suggests that apoptosis may play an important role in this unique patient population.

High-mobility group protein B1 (HMGB1) is a novel biomarker for human ovarian cancer

BACKGROUND

High mobility group box l (HMGB1), a nuclear and extracellular protein, is implicated in some physiologic and pathologic conditions. In this study, we investigated the expression and function of HMGB1 in ovarian cancer.

METHODS

cDNA microarray analysis was performed to compare gene expression profiles of the highly invasive and the low invasive subclones derived from the SKOV3 human ovarian cancer cell line. Immunohistochemistry (IHC) staining was performed to investigate HMGB1 expression in a total of 100 ovarian tissue specimens. In functional assays, effects of HMGB1 knockdown on the biological behavior of ovarian cancer cells were investigated.

RESULTS

HMGB1 was overexpressed in the highly invasive subclone compared with the low invasive subclone. High HMGB1 expression was associated with poor clinicopathologic features. Knockdown of HMGB1 expression significantly suppressed ovarian cancer cell proliferation accompanied by decreased cyclin D1 and PCNA expression, and inhibited cell migration and invasion accompanied by decreased MMP2 and MMP9 activities.

CONCLUSION

HMGB1 is a newly identified gene overexpressed in ovarian cancer and associated with poor clinicopathologic features. HMGB1 may serve as a new biomarker and a therapeutic target for ovarian cancer in the future.

High mobility group box 1 in cerebrospinal fluid from several neurological diseases at early time points

The present study aimed to elucidate the possible role of High Mobility Group Box 1 (HMGB1), which is a candidate prognostic marker in diseases that combine inflammation and tissue injury, in acute encephalopathy. HMGB1 in cerebrospinal fluid (CSF) obtained on admission from eight children with acute encephalopathy, and 16 children with febrile seizure, eight children with bacterial/aseptic meningitis, and eight children with fever without neurological symptoms were analyzed using enzyme-linked immunosorbent assay (ELISA). We found no increase in HMGB1 in CSF from acute encephalopathy or in CSF from febrile seizure or fever without neurological complications at early time points, while marked elevation of HMGB1 was seen in CSF from bacterial and aseptic meningitis. In conclusion, HMGB1 is a poor disease marker for acute encephalopathy.

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

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

Association between high-mobility group box-1 protein release and immune function of dendritic cells in thermal injury

The present study was performed to investigate in vivo the effect of high-mobility group box-1 protein (HMGB1) on the maturation of dendritic cell (DC) and the influence on T-cell-mediated immunity after thermal injury. Rats were randomly divided into 3 groups as follows: sham burn group, burn group, and burn with ethyl pyruvate (EP) treatment group, and they were sacrificed on post burn days (PBD) 1, 3, 5, and 7 respectively. MACS microbeads were used to isolate splenic DCs and column of nylon wool to obtain T cells. Phenotypes were analyzed by flow cytometry and cytokines were determined with ELISA kits. The expression levels of splenic HMGB1 were significantly elevated during PBD 1-7. DC expressed similar CD80 levels, strongly enhanced CD86, and slightly elevated MHC class II levels in comparison to DC from sham-injured rats, and protein levels of IL-12 were not increased after thermal injury. Administration of EP to inhibit HMGB1 could significantly enhance expression levels of CD80, MHC class II on DC surface, and IL-12 production after burns. Simultaneously, proliferative activity and expression levels of IL-2 as well as IL-2R alpha of T cell were restored. These results suggested that the excessively released HMGB1 might stimulate splenic DC to mature abnormally and down-regulate the IL-12 production, and further shifting of Th1 to Th2 with suppression of T-lymphocyte immune function following burn injury.

HMGB1-induced autophagy promotes chemotherapy resistance in leukemia cells

Autophagy, a tightly regulated lysosome-dependent catabolic pathway, is important in the regulation of cancer development and progression and in determining the response of tumor cells to anticancer therapy. However, the role of autophagy in leukemia still remains largely unknown. Here we show that high-mobility group box 1 (HMGB1), the best characterized damage-associated molecular pattern, was released from leukemia cell lines after chemotherapy-induced cytotoxicity and activated autophagy to protect against injury. Treatment with HMGB1-neutralizing antibodies increased the sensitivity of leukemia cells to chemotherapy; whereas, exogenous HMGB1 rendered these cells more resistant to drug-induced cytotoxicity. Moreover, exogenous HMGB1 increased autophagy as evaluated by increased expression of the autophagic marker microtubule-associated protein light chain 3-II, degradation of sequestosome 1 (p62) and autophagosome formation. Furthermore, knockdown or pharmacological inhibition of either phosphoinositide 3-kinase-III or extracellular signal-regulated kinase kinase mitogen-activated protein kinase kinase/extracellular signal-regulated protein kinase inhibited HMGB1-induced autophagy. Taken together, these results suggest that HMGB1 release after chemotherapy is a critical regulator of autophagy and a potential drug target for therapeutic interventions in leukemia.

Neuron specific metabolic adaptations following multi-day exposures to oxygen glucose deprivation

Prior exposure to sub toxic insults can induce a powerful endogenous neuroprotective program known as ischemic preconditioning. Current models typically rely on a single stress episode to induce neuroprotection whereas the clinical reality is that patients may experience multiple transient ischemic attacks (TIAs) prior to suffering a stroke. We sought to develop a neuron-enriched preconditioning model using multiple oxygen glucose deprivation (OGD) episodes to assess the endogenous protective mechanisms neurons implement at the metabolic and cellular level. We found that neurons exposed to a five minute period of glucose deprivation recovered oxygen utilization and lactate production using novel microphysiometry techniques. Using the non-toxic and energetically favorable five minute exposure, we developed a preconditioning paradigm where neurons are exposed to this brief OGD for three consecutive days. These cells experienced a 45% greater survival following an otherwise lethal event and exhibited a longer lasting window of protection in comparison to our previous in vitro preconditioning model using a single stress. As in other models, preconditioned cells exhibited mild caspase activation, an increase in oxidized proteins and a requirement for reactive oxygen species for neuroprotection. Heat shock protein 70 was upregulated during preconditioning, yet the majority of this protein was released extracellularly. We believe coupling this neuron-enriched multi-day model with microphysiometry will allow us to assess neuronal specific real-time metabolic adaptations necessary for preconditioning.

HMGB1 release and redox regulates autophagy and apoptosis in cancer cells

The functional relationship and cross-regulation between autophagy and apoptosis is complex. Here we show that high-mobility group box 1 protein (HMGB1) is a redox-sensitive regulator of the balance between autophagy and apoptosis. In cancer cells, anti-cancer agents enhanced autophagy and apoptosis as well as HMGB1 release. HMGB1 release may be a pro-survival signal for residual cells following various cytotoxic cancer treatments. Diminished HMGB1 by shRNA transfection or inhibition of HMGB1 release by ethyl pyruvate or other small molecules led to predominantly apoptosis and decreased autophagy in stressed cancer cells. In this setting, reducible HMGB1 binds to the receptor for advanced glycation end products (RAGE) but not Toll-like receptor 4 (TLR4), induces Beclin1-dependent autophagy, and promotes tumor resistance to alkylators (melphalan), tubulin disrupting agents (paclitaxel), DNA crosslinkers (ultraviolet light) and DNA-intercalators (oxaliplatin or adriamycin). Oxidized HMGB1 conversely increases the cytotoxicity of these agents and induces apoptosis mediated by the caspase-9/-3 intrinsic pathway. HMGB1 release as well as its redox state thus link autophagy and apoptosis, representing a suitable target when coupled with conventional tumor treatments.

High-mobility group box 1 and cancer

High-mobility group box 1 protein (HMGB1), a chromatin associated nuclear protein and extracellular damage associated molecular pattern molecule (DAMP), is an evolutionarily ancient and critical regulator of cell death and survival. Overexpression of HMGB1 is associated with each of the hallmarks of cancer including unlimited replicative potential, ability to develop blood vessels (angiogenesis), evasion of programmed cell death (apoptosis), self-sufficiency in growth signals, insensitivity to inhibitors of growth, inflammation, tissue invasion and metastasis. Our studies and those of our colleagues suggest that HMGB1 is central to cancer (abnormal wound healing) and many of the findings in normal wound healing as well. Here, we focus on the role of HMGB1 in cancer, the mechanisms by which it contributes to carcinogenesis, and therapeutic strategies based on targeting HMGB1.

Quercetin prevents LPS-induced high-mobility group box 1 release and proinflammatory function

The pathogenesis of sepsis is mediated in part by the pathogen-associated molecular pattern molecule bacterial endotoxin, which stimulates macrophages to sequentially release early (e.g., TNF-alpha, IL-1beta) and late (e.g., high-mobility group box [HMGB] 1 protein) proinflammatory mediators. The recent discovery of HMGB1 as a late mediator of lethal sepsis has prompted investigation into development of several new experimental therapeutics that limit release, either blocking HMGB1 itself or its nominal receptors. Quercetin was recently identified as an experimental therapeutic that significantly protects against oxidative injury. Here, we report that quercetin attenuates lethal systemic inflammation caused by endotoxemia, even if treatment is started after the early TNF response. Quercetin treatment reduced circulating levels of HMGB1 in animals with established endotoxemia. In macrophage cultures, quercetin inhibited release as well as the cytokine activities of HMGB1, including limiting the activation of mitogen-activated protein kinase and NF-kappaB, two signaling pathways that are critical for HMGB1-induced subsequent cytokine release. Quercetin and autophagic inhibitor, wortmannin, inhibited LPS-induced type-II microtubule-associated protein 1A/1B-light chain 3 production and aggregation, as well as HMGB1 translocation and release, suggesting a potential association between autophagy and HMGB1 release. Quercetin delivery, a strategy to pharmacologically inhibit HMGB1 release that is effective at clinically achievable concentrations, now warrants further evaluation in sepsis and other systemic inflammatory disorders.