High mobility group box 1 in the central nervous system:regeneration hidden beneath inflammation

High-mobility group box 1 was first discovered in the calf thymus as a DNA-binding nuclear protein and has been widely studied in diverse fields,including neurology and neuroscience.High-mobility group box 1 in the extracellular space functions as a pro-inflammatory damage-associated molecular pattern,which has been proven to play an important role in a wide variety of central nervous system disorders such as ischemic stroke,Alzheimer’s disease,frontotemporal dementia,Parkinson’s disease,multiple sclerosis,epilepsy,and traumatic brain injury.Several drugs that inhibit high-mobility group box 1 as a damage-associated molecular pattern,such as glycyrrhizin,ethyl pyruvate,and neutralizing anti-high-mobility group box 1 antibodies,are commonly used to target high-mobility group box 1 activity in central nervous system disorders.Although it is commonly known for its detrimental inflammatory effect,high-mobility group box 1 has also been shown to have beneficial pro-regenerative roles in central nervous system disorders.In this narrative review,we provide a brief summary of the history of high-mobility group box 1 research and its characterization as a damage-associated molecular pattern,its downstream receptors,and intracellular signaling pathways,how high-mobility group box 1 exerts the repair-favoring roles in general and in the central nervous system,and clues on how to differentiate the pro-regenerative from the pro-inflammatory role.Research targeting high-mobility group box 1 in the central nervous system may benefit from differentiating between the two functions rather than overall suppression of high-mobility group box 1.

Hmo1:A versatile member of the high mobility group box family of chromosomal architecture proteins

Eukaryotic chromatin consisting of nucleosomes connected by linker DNA is organized into higher order structures,which is facilitated by linker histone H1.Formation of chromatin compacts and protects the genome,but also hinders DNA transactions.Cells have evolved mechanisms to modify/remodel chromatin resulting in chromatin states suitable for genome functions.The high mobility group box(HMGB)proteins are non-histone chromatin architectural factors characterized by one or more HMGB motifs that bind DNA in a sequence nonspecific fashion.They play a major role in chromatin dynamics.The Saccharomyces cerevisiae(yeast hereafter)HMGB protein Hmo1 contains two HMGB motifs.However,unlike a canonical HMGB protein that has an acidic C-terminus,Hmo1 ends with a lysine rich,basic,C-terminus,resembling linker histone H1.Hmo1 exhibits characteristics of both HMGB proteins and linker histones in its multiple functions.For instance,Hmo1 promotes transcription by RNA polymerases I and II like canonical HMGB proteins but makes chromatin more compact/stable like linker histones.Recent studies have demonstrated that Hmo1 destabilizes/disrupts nucleosome similarly as other HMGB proteins in vitro and acts to maintain a common topological architecture of genes in yeast genome.This minireview reviews the functions of Hmo1 and the underlying mechanisms,highlighting recent discoveries.

Suppressing high mobility group box-1 release alleviates morphine tolerance via the adenosine5'-monophosphate-activated protein kinase/heme oxygenase-1 pathway

Opioids,such as morphine,are the most potent drugs used to treat pain.Long-term use results in high tolerance to morphine.High mobility group box-1(HMGB1) has been shown to participate in neuropathic or inflammatory pain,but its role in morphine tolerance is unclear.In this study,we established rat and mouse models of morphine tolerance by intrathecal injection of morphine for 7 consecutive days.We found that morphine induced rat spinal cord neurons to release a large amount of HMGB1.HMGB1 regulated nuclear factor κB p65 phosphorylation and interleukin-1β production by increasing Toll-like receptor 4receptor expression in microglia,thereby inducing morphine tolerance.Glycyrrhizin,an HMGB1 inhibito r,markedly attenuated chronic morphine tole rance in the mouse model.Finally,compound C(adenosine 5’-monophosphate-activated protein kinase inhibitor) and zinc protoporphyrin(heme oxygenase-1 inhibitor)alleviated the morphine-induced release of HMGB1 and reduced nuclear factor κB p65 phosphorylation and interleukin-1β production in a mouse model of morphine tolerance and an SH-SY5Y cell model of morphine tole rance,and alleviated morphine tolerance in the mouse model.These findings suggest that morphine induces HMGB1 release via the adenosine 5’-monophosphate-activated protein kinase/heme oxygenase-1 signaling pathway,and that inhibiting this signaling pathway can effectively reduce morphine tole rance.

Scolopendra subspinipes mutilans protected the ceruleininduced acute pancreatitis by inhibiting high-mobility group box protein-1

AIM:To evaluate the inhibitory effects of Scolopendra subspinipes mutilans(SSM) on cerulein-induced acute pancreatitis(AP) in a mouse model.METHODS:SSM water extract(0.1,0.5,or 1 g/kg) was administrated intraperitoneally 1 h prior to the first injection of cerulein.Once AP developed,the stable cholecystokinin analogue,cerulein was injected hourly,over a 6 h period.Blood samples were taken 6 h later to determine serum amylase,lipase,and cytokine levels.The pancreas and lungs were rapidly removed for morphological examination,myeloperoxidase assay,and real-time reverse transcription polymerase chain reaction.To specify the role of SSM in pancreatitis,the pancreatic acinar cells were isolated using collagenase method.Then the cells were pre-treated with SSM,then stimulated with cerulein.The cell viability,cytokine productions and high-mobility group box protein-1(HMGB-1) were measured.Furthermore,the regulating mechanisms of SSM action were evaluated.RESULTS:The administration of SSM significantly attenuated the severity of pancreatitis and pancreatitis associated lung injury,as was shown by the reduction in pancreatic edema,neutrophil infiltration,vacuolization and necrosis.SSM treatment also reduced pancreatic weight/body weight ratio,serum amylase,lipase and cytokine levels,and mRNA expression of multiple inflammatory mediators such as tumor necrosis factor-α and interleukin-1β.In addition,treatment with SSM inhibited HMGB-1 expression in the pancreas during AP.In accordance with in vivo data,SSM inhibited the cerulein-induced acinar cell death,cytokine,and HMGB-1 release.SSM also inhibited the activation of c-Jun NH2-terminal kinase,p38 and nuclear factor(NF)-κB.CONCLUSION:These results suggest that SSM plays a protective role during the development of AP and pancreatitis associated lung injury via deactivating c-Jun NH2-terminal kinase,p38 and NF-κB.

High-mobility group box 1 protein and its role in severe acute pancreatitis

The high mobility group box 1(HMGB1),which belongs to the subfamily of HMG-1/-2,is a highly conserved single peptide chain consisting of 215 amino acid residues with a molecular weight of approximately 24894 Da.HMGB1 is a ubiquitous nuclear protein in mammals and plays a vital role in inflammatory diseases.Acute pancreatitis is one of the most common causes of acute abdominal pain with a poor prognosis.Acute pancreatitis is an acute inflammatory process of the pancreas(duration of less than six months),for which the severe form is called severe acute pancreatitis(SAP).More and more studies have shown that HMGB1 has a bidirectional effect in the pathogenesis of SAP.Extracellular HMGB1 can aggravate the pancreatic inflammatory process,whereas intracellular HMGB1 has a protective effect against pancreatitis.The mechanism of HMGB1 is multiple,mainly through the nuclear factor-κB pathway.Receptors for advanced glycation endproducts and toll-like receptors(TLR),especially TLR-2 and TLR-4,are two major types of receptors mediating the inflammatory process triggered by HMGB1 and may be also the main mediators in the pathogenesis of SAP.HMGB1 inhibitors,such as ethyl pyruvate,pyrrolidine dithiocarbamate and Scolopendra subspinipes mutilans,can decrease the level of extracellular HMGB1 and are the promising targets in the treatment of SAP.

High mobility group box-1 protein inhibits regulatory T cell immune activity in liver failure in patients with chronic hepatitis B

BACKGROUND: Liver failure in chronic hepatitis B (CHB) patients is a severe, life-threatening condition. Intestinal endotoxemia plays a significant role in the progress to liver failure. High mobility group box-1 (HMGB1) protein is involved in the process of endotoxemia. Regulatory T (Treg) cells maintain immune tolerance and contribute to the immunological hyporesponsiveness against HBV infection. However, the roles of HMGB1 and Treg cells in the pathogenesis of liver failure in CHB patients, and whether HMGB1 affects the immune activity of Treg cells are poorly known at present, and so were explored in this study. METHODS: The levels of HMGB1 expression were detected by ELISA, real-time RT-PCR, and Western blotting, and the percentage of CD4(+)CD25(+)CD127(low) Treg cells among CD4(+) cells was detected by flow cytometry in liver failure patients with chronic HBV infection, CHB patients, and healthy controls. Then, CD4(+)CD25(+)CD127(low) Treg cells isolated from the peripheral blood mononuclear cells from CHB patients were stimulated with HMGB1 at different concentrations or at various intervals. The effect of HMGB1 on the immune activity of Treg cells was assessed by a suppression assay of the allogeneic mixed lymphocyte response. The levels of forkhead box P3 (Foxp3) expression in Treg cells treated with HMGB1 were detected by RT-PCR and Western blotting. RESULTS: A higher level of HMGB1 expression and a lower percentage of Treg cells within the population of CIA(+) cells were found in liver failure patients than in CHB patients (82.6+/-20.1 mu g/L vs. 34.2+/-13.7 mu g/L; 4.55+/-1.34% vs. 9.52+/-3.89%, respectively). The immune activity of Treg cells was significantly weakened and the levels of Foxp3 expression were reduced in a dose- or time-dependent manner when Treg cells were stimulated with HMGB1 in vitro. CONCLUSIONS: The high level of HMGB1 and the low percentage of Treg cells play an important role in the pathogenesis of liver failure in patients with chronic HBV infection. Moreover, HMGB1 can weaken the immune activity of Treg cells. It is suggested that effectively inhibiting HMGB1 expression could be a feasible way to treat liver failure by suppressing endotoxemia and enhancing Treg cell activity.

Delayed ethyl pyruvate therapy attenuates experimental severe acute pancreatitis via reduced serum high mobility group box 1 levels in rats

AIM： To investigate the effect of delayed ethyl pyruvate （EP） delivery on distant organ injury, survival time and serum high mobility group box 1 （HMGB1） levels in rats with experimental severe acute pancreatitis （SAP）. METHODS： A SAP model was induced by retrograde injection of artificial bile into the pancreatic ducts of rats. Animals were divided randomly into three groups （n = 32 in each group）： sham group, SAP group and delayed EP treatment group. The rats in the delayed EP treatment group received EP （30 mg/kg） at 12 h, 18 h and 30 h after induction of SAP. Animals were sacrificed, and samples were obtained at 24 h and 48 h after induction of SAP. Serum HMGB1, aspartate arninotransferase （AST）, alanine arninotransferase （ALT）, blood urea nitrogen （BUN）, and creatinine （Cr） levels were measured. Lung wet-to-dry-weight （W/D） ratios and histological scores were calculated to evaluate lung injury. Additional experiments were performed between SAP and delayed EP treatment groups to study the influence of EP on survival times of SAP rats. RESULTS： Delayed EP treatment significantly reduced serum HMGB1 levels, and protected against liver, renal and lung injury with reduced lung W/D ratios （8.22 ±0.42 vs 9.76 ± 0.45, P 〈 0.01）, pulmonary histological scores （7.1 ± 0.7 vs 8.4 ± 1.1, P 〈 0.01）, serum AST （667 ± 103 vs 1 368 ± 271, P 〈 0.01）, ALT （446 ± 91 vs 653 ± 98, P 〈 0.01） and Cr （1.2 ± 0.3 vs 1.8 ± 0.3, P 〈 0.01） levels. SAP rats had a median survival time of 44 h. Delayed EP treatment significantly prolonged median survival time to 72 h （P 〈 0.01）. CONCLUSION： Delayed EP therapy protects against distant organ injury and prolongs survival time via reduced serum HMGBllevels in rats with experimental SAP. EP may potentially serve as an effective new therapeutic option against the inflammatory response and multiple organ dysfunction syndrome （MODS） in SAP patients.

Novel insights for high mobility group box 1 proteinmediated cellular immune response in sepsis:A systemic review

High mobility group box 1 protein （HMGB1） is a highly conserved, ubiquitous protein in the nuclei and cytoplasm of nearly all cell types. HMGB1 is secreted into the extracellular milieu and acts as a proinflammatory cytokine. In this article we reviewed briefly the cellular immune response mediated by HMGB1 in inflammation and sepsis. This systemic review is mainly based on our own work and other related reports HMGB1 can actively affect the immune functions of many types of cells including T lymphocytes, regulatory T cells （Tregs）, dendritic cells （DCs）, macrophages, and natural killer cells （NK cells）. Various cellular responses can be mediated by HMGB1 which binds to cell-surface receptors [e.g., the receptor for advanced glycation end products （RAGE）, Toll-like receptor （TLR）2, and TLR4]. Anti-HMGB1 treatment, such as anti-HMGB1 polyclonal or monoclonal antibodies, inhibitors （e.g., ethyl pyruvate） and antagonists （e.g., A box）, can protect against sepsis lethality and give a wider window for the treatment opportunity. HMGB1 is an attractive target for the development of new therapeutic strategies in the treatment of patients with septic complications.

Inflammatory response and immune regulation of high mobility group box-1 protein in treatment of sepsis

Sepsis is an infection induced systemic inflammatory response syndrome and is a major cause of morbidity as well as mortality in intensive care units. A growing body of evidence suggests that the activation of a proinflammatory cascade is responsible for the development of immune dysfunction, susceptibility to severe sepsis and septic shock. The present theories of sepsis as a dysregulated inflammatory response and immune function, as manifested by excessive release of inflammatory mediators such as high mobility group box 1 protein （HMGB1）, are supported by increasing studies employing animal models and clinical observations of sepsis. HMGB1, originally described as a DNA-binding protein and released passively by necrotic cells and actively by macrophages/monocytes, has been discovered to be one of essential cytokines that mediates the response to infection, injury and inflammation. A growing number of studies still focus on the inflammation-regulatory function and its contribution to infectious and inflammatory disorders, recent data suggest that HMGB1 formation can also markedly influence the host cell-mediated immunity, including T lymphocytes and macrophages. Here we review emerging evidence that support extracellular HMGB1 as a late mediator of septic complications, and discuss the therapeutic potential of several HMGBl-targeting agents in experimental sepsis. In addition, with the development of traditional Chinese medicine in recent years, it has been proven that traditional Chinese herbal materials and their extracts have remarkable effective in treating severe sepsis. In this review, we therefore provide some new concepts of HMGBl-targeted Chinese herbal therapies in sepsis.

High mobility group box 1 protein(HMGB1)as an immune-modulating factor for polarization of human T lymphocytes

Objective This study was performed to investigate the effect of high mobility group box-1 protein(HMGB1)on immune function of human T lymphocytes in vitro and explore its potential role in cell-mediated immune dysfunction.Methods Fresh blood was obtained from healthy adult volunteers and peripheral blood mononuclear cells(PBMCs)were isolated,then rhHMGB1 was added to PBMCs.Four-color flow cytometric(FCM)analysis was used for the measurement of intracellular cytokine including interleukin IL-4 and interferon IFN-?ELISA kits were employed for the determination of IL-2 and sIL-2R protein levels in cell culture supernatants.Results(1)Different stimulating time and dosage of rhHMGB1 did not alter the number of IFN-αpositive cells(Th1).rhHMGB1 stimulation provoked a dose-dependent and time-dependent increase in Th2 subset and decrease in ratio of Th1 to Th2.(2)Compared with the untreated cells,when the cells were coincubated with rhHMGB1(10-100ng/ml)for 12 hrs,protein release of IL-2 and sIL-2R were significantly up-regulated.At 48 hrs,in contrast,protein production was relatively lower in cells after exposure to 100-1000 ng/ml rhHMGB1.Conclusions These findings demonstrated that HMGB1 has a dual influence on immune functions of human T lymphocytes.

Inhibition of LOX-1 alleviates the proinflammatory effects of high-mobility group box 1 in Aspergillus fumigatus keratitis

AIM: To investigate the inflammatory amplification effect of high-mobility group box 1(HMGB1) in Aspergillus fumigatus(A. fumigatus) keratitis and the relationship between lectin-like oxidized low-density lipoprotein receptor 1(LOX-1) and HMGB1 in keratitis immune responses.METHODS: Phosphate buffer saline(PBS), and Boxb were injected into BALB/c mice subconjunctivally before the corneas were infected with A. fumigatus. RAW264.7 macrophages and neutrophils were pretreated with PBS and Boxb to determine the HMGB1 inflammatory amplification effects. Abdominal cavity extracted macrophages were pretreated with Boxb and Poly(I)(a LOX-1 inhibitor) before A. fumigatus hyphae stimulation to prove the the relationship between the two molecules. LOX-1, interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), macrophage inflammatory protein-2(MIP-2) and IL-10 were assessed by polymerase chain reaction and Western blot.RESULTS: Pretreatment with Boxb exacerbated corneal inflammation. In macrophages and neutrophils, A. fumigatus induced LOX-1, IL-1β, TNF-α and MIP-2 expression in Boxb group was higher than those in PBS group. Poly(I) treatments before infection alleviated the proinflammatory effects of Boxb in abdominal cavity extracted macrophages. Pretreatment with Boxb did not influence Dectin-1 mRNA levels in macrophages and neutrophils.CONCLUSION: In fungal keratitis, HMGB1 is a proinflammatory factor in the first line of immune response. HMGB1 mainly stimulates neutrophils and macrophages to produce inflammatory cytokines and chemokines during the immune response. LOX-1 participates in HMGB1 induced inflammatory exacerbation in A. fumigatus keratitis.

Changes of High Mobility Group box 1 in Serum of Pig Acute Hepatic Failure Model and Significance

The role of the high mobility group box 1 （HMGB-1） in acute hepatic failure and the effect of artificial liver support system treatment on HMGB-1 level were investigated. Pig models of acute hepatic failure were induced by D-galactosamine and randomly divided into two groups with or without artificial liver support system treatment. Tumor necrosis factor-α （TNF-α） and interleukin-1β （IL-1β） levels were detected by the enzyme linked immunosorbent assay （ELISA）, the expression of HMGB-1 by Western blot, and serum levels of HMGB-1, liver function and hepatic pathology were observed after artificial liver support system treatment. The levels of TNF-α and IL-1β were increased and reached the peak at 24th h in the acute hepatic failure group, then quickly decreased. The serum level of HMGB-1 was increased at 24th h in the acute hepatic failure group and reached the peak at 48th h, then kept a stable high level. Significant liver injury appeared at 24th h and was continuously getting worse in the pig models of acute hepatic failure. In contrast, the liver injury was significantly alleviated and serum level of HMGB-1 was significantly decreased in the group treated with artificial liver support system （P〈0.05）. It was suggested that HMGB-1 may participate in the inflammatory response and liver injury in the late stage of the acute liver failure. Artificial liver support system treatment can reduce serum HMGB-1 level and relieve liver pathological damage.

High mobility group box-1 release from H2O2-injured hepatocytes due to sirt1 functional inhibition

BACKGROUND High mobility group box-1 (HMGB1), recognized as a representative of damageassociated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited. AIM To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress. METHODS C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2- deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation. RESULTS When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation. CONCLUSION The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.

Association between thrombomodulin and high mobility group box 1 in sepsis patients

BACKGROUND High mobility group box 1(HMGB1)has been studied as a molecule associated with severe outcomes in sepsis and thrombomodulin(TM)seems to decrease HMGB1 activity.AIM To investigate the role of the thrombomodulin/high mobility group box 1(T/H)ratio in patients with sepsis and their association with their clinic,testing the hypothesis that higher ratios are associated with better outcomes.METHODS Twenty patients diagnosed with sepsis or septic shock,according to the 2016 criteria sepsis and septic shock(Sepsis-3),were studied.Patients were followed until they left the intensive care unit or until they achieved 28 d of hospitalization(D28).The following clinical outcomes were observed:Sequential Organ Failure Assessment(SOFA)score;Need for mechanical pulmonary ventilation;Presence of septic shock;Occurrence of sepsis-induced coagulopathy;Need for renal replacement therapy(RRT);and Death.RESULTS The results showed that patients with SOFA scores greater than or equal to 12 points had higher serum levels of TM:76.41±29.21 pg/mL vs 37.41±22.55 pg/mL among those whose SOFA scores were less than 12 points,P=0.003.The T/H ratio was also higher in patients whose SOFA scores were greater than or equal to 12 points,P=0.001.The T/H ratio was,on average,three times higher in patients in need of RRT(0.38±0.14 vs 0.11±0.09),P<0.001.CONCLUSION Higher serum levels of TM and,therefore,higher T/H ratio in the first 24 h after the diagnosis of sepsis were associated with more severe disease and the need for renal replacement therapy,while those with better clinical outcomes and those who were discharged before D28 showed a tendency for lower T/H ratio values.

Role of high mobility group box protein 1 in depression:A mechanistic and therapeutic perspective

As a common and serious psychiatric disorder,depression significantly affects psychosocial functioning and quality of life.However,the mechanism of depression is still enigmatic and perplexing,which limits its precise and effective therapeutic methods.Recent studies demonstrated that neuroinflammation activation plays an important role in the pathophysiology of depression.In this respect,high mobility group box 1(HMGB1)may be a possible signaling inducer of neuroinflammation and can be a potential mechanistic and therapeutic target for depression.Herein,we review recent studies on the mechanistic and therapeutic targets of HMGB1 in depression and propose potential perspectives on this topic.

Effect on proliferation and apoptosis of retinoblastoma cell by RNA inhibiting high mobility group protein box-1 expression

AIM： To investigate the effect of high mobility group protein box-1 （HMGB1） siRNA on proliferation and apoptosis of retinoblastoma （Rb） cells.METHODS： The expression of HMGB1 in Rb cells were detected by real-time polymerase chain reaction （RT-PCR） and Western blot. Chemically synthesized HMGB1 siRNA was transfected into Y79 cells. The inhibitory rate was also examined by RT-PCR and Western blot. After HMGB1 siRNA transfection, the cell proliferation was analyzed by MTT, and cell apoptosis was detected by Caspase-3 active detection kit. Cell cycle distribution and apoptosis were detected by flow cytometry. RESULTS： The expression of HMGB1 significantly elevated in Rb cells （P〈0.01）. After transfected by siRNA, the HMGB1 protein level of Y79 cells was significantly reduced （P〈0.01）. After siRNA interference HMGB1, the proportion of proliferating cells reduced, and the proportion of quiescent cells increased （P〈0.05）. In addition, apoptosis rate of Y79 cells increased from 2.03% to 9.10% after interfering with HMGB1 siRNA （P〈0.05）.CONCLUSION： Specific HMGB1 siRNA can inhibit the expression of HMGB1. The effect may be attributed to inhibit the proliferation and promote cell apoptosis.

Effect of high mobility group box-1 protein on immune cells and its regulatory mechanism

High mobility group box-1 protein(HMGB1),which is a nuclear protein,participates in chromatin architecture and transcriptional regulation.When released from cells,HMGB1 also plays a well-established role as a pro-inflammatory mediator during innate immune responses to injury.In the initial stage of injury,there is a release of large quantities of early pro-inflammatory mediators to initiate or perpetuate immune responses against pathogens,but this pro-inflammatory period is transient,and it is followed by a prolonged period of immune suppression.At present,several lines of evidences have suggested that HMGB1 is a late cytokine provoking delayed endotoxin morbidity,which may enhance the production of early proinflammatory mediators,and it can contribute potently to the activation of different immune cells and play a role in the development of host cell-mediated immunity.The biology of HMGB1 has been extensively studied as a pro-inflammatory cytokine of systemic inflammation,however,this review will attempt to provide a summary of the effects of HMGB1 on different immune cells and its regulatory mechanism in acute insults.

Renal Expression and Clinical Significance of High Mobility Group Box 1 in Lupus Nephritis

Objective: To evaluate the clinical significance of high mobility group box 1 (HMGB1) expression in nephridial tissues of lupus nephritis (LN). Methods: Sixty-three patients with active LN and 15 systemic lupus erythematosus (SLE) (combined without LN) were included. Renal biopsies were performed in the two groups. The biopsies were evaluated according to the World Health Organization (WHO) classification and renal disease activity was estimated using the British Isles lupus assessment group (BILAG) index. Serum levels of HMGB1 were analyzed by western blot. HMGB1 expression in renal tissue was assessed by immunohistochemistry in the two groups. The correlation between HMGB1 and renal active index (AI), chronicity index (CI), pathological type of LN was analyzed. Results: LN biopsies showed WHO class III, IV or V and all patients had high renal disease activity (BILAG A/B). The HMGB1 expression was higher in the LN groups than the control groups (t = 9.263, P < 0.05). It showed positive correlation between HMGB1 expression and SLE DAI classification (r = 0.579, P P < 0.05) and renal tubule interstitial (TIL) classification (r = 0.815, P < 0.05), and negative correlation between HMGB1 expression and CI classification (r = 0.582, P < 0.05). In all patients, serum levels of HMGB1 increased only slightly in the patients only with SLE;however, in patients with LN WHO class IV a significant decrease was observed (P = 0.02). Immunostaining revealed a pronounced extranuclear HMGB1 expression predominantly outlining the glomerular endothelium and in the mesangium. There were significant differences in HMGB1 expression between LN and control biopsies and it existed with apparent association to histopathological classification and clinical outcome. Conclusions: Renal tissue expression and serum levels of HMGB1 were elevated in LN. The unusual elevation of HMGB1 in serum and tissue in LN may reflect persistent inflammatory activity, which clearly indicates a role for HMGB1 in pathogenesis of LN.

Relationship of plasma homocysteine, soluble intercellular adhesion molecule-1, high mobility group box 1 protein with carotid intima-media thickness in elderly patients with type 2 diabetes mellitus

Objective:To explore the relationship of plasma homocysteine(Hcy),soluble intercellular adhesion molecule-1(sICAM-1)and high mobility group box 1 protein(HMGB1)with carotid intima-media thickness(c-IMT)in elderly patients with type 2 diabetes mellitus.Methods:A total of 100 elderly patients who were diagnosed as type 2 diabetes mellitus in Baogang Hospital of Inner Mongolia from June 2017 to May 2020 were chosen as research objects.According to c-IMT,they were divided into the normal group(n=35),the mild to moderate group(n=41)and the severe group(n=24).The expression levels of plasma Hcy,sICAM-1 and HMGB1 were compared between groups respectively.Pearson’s correlation coefficient was used to analyze the relationship of plasma Hcy,sICAM-1,HMGB1 with c-IMT.Results:The comparison in plasma Hcy,sICAM-1,HMGB1 and c-IMT among the three groups of patients was of statistical significance(p<.05).The results of correlation analysis showed that the expression levels of plasma Hcy,sICAM-1 and HMGB1 were positively correlated with c-IMT in elderly patients with type 2 diabetes mellitus(r=.627,.598,.614;p<.05).Conclusions:The expression levels of plasma Hcy,sICAM-1 and HMGB1 are abnormally increased in elderly patients with type 2 diabetes mellitus,and related to c-IMT,which can provide a strong evidence for clinical diagnosis and treatment by detecting their levels in clinical practice.

High mobility group protein 1: A collaborator in nucleosome dynamics and estrogen-responsive gene expression

High mobility group protein 1(HMGB1) is a multifunctional protein that interacts with DNA and chromatin to influence the regulation of transcription, DNA replication and repair and recombination. We show that HMGB1 alters the structure and stability of the canonical nucleosome(N) in a nonenzymatic,adenosine triphosphate-independent manner. As a result, the canonical nucleosome is converted to two stable, physically distinct nucleosome conformers. Although estrogen receptor(ER) does not bind to its consensus estrogen response element within a nucleosome, HMGB1 restructures the nucleosome to facilitate strong ER binding. The isolated HMGB1-restructured nucleosomes(N' and N'') remain stable and exhibit a number of characteristics that are distinctly different from the canonical nucleosome. These findings complement previous studies that showed(1) HMGB1 stimulates in vivo transcriptional activation at estrogen response elements and(2) knock down of HMGB1 expression by siR NA precipitously reduced transcriptional activation. The findings indicate that a major facet of the mechanism of HMGB1 action involves a restructuring of aspects of the nucleosome that appear to relax structural constraints within the nucleosome. The findings are extended to reveal the differences between ER and the other steroid hormone receptors. A working proposal outlines mechanisms that highlight the multiple facets that HMGB1 may utilize in restructuring the nucleosome.