Endotoxemia ; metabolism ; pathology ; HMGB1 Protein ; Humans ; Liver ; metabolism ; pathology

High mobility group box 1 (HMGB1) is an evolutionarily conserved non-histone chromatin-binding protein. During infection or injury, activated immune cells and damaged cells release HMGB1 into the extracellular space, where HMGB1 functions as a proinflammatory mediator and contributes importantly to the pathogenesis of inflammatory diseases. Recent studies reveal that inflammasomes, intracellular protein complexes, critically regulate HMGB1 release from activated immune cells in response to a variety of exogenous and endogenous danger signals. Double stranded RNA dependent kinase (PKR), an intracellular danger-sensing molecule, physically interacts with inflammasome components and is important for inflammasome activation and HMGB1 release. Together, these studies not only unravel novel mechanisms of HMGB1 release during inflammation, but also provide potential therapeutic targets to treat HMGB1-related inflammatory diseases.
HMGB1 Protein ; chemistry ; metabolism ; Humans ; Inflammasomes ; metabolism ; Macrophages ; immunology ; metabolism ; eIF-2 Kinase ; metabolism

Atrial fibrillation (AF) is the most common sustained dysrhythmia in clinical practice. The bulk of evidence suggests that inflammatory processes, oxidative stress and matrix metalloproteinase are associated with development of AF. However, these agents may be involved in high mobility group box 1 protein (HMGB1). We hypothesized that HMGB1 may be a possible pathogenic link to AF. A growing body of evidence supports these hypotheses. First, the level of serum HMGB1 is significantly increased in patients with AF including paroxysmal and persistent AF. Second, HMGB1 has been identified as a new pro-inflammatory cytokine in cardiovascular diseases, along with tumor necrosis factor (TNF)-α, interleukin (IL)-6, and C-reactive protein, and there is cross-talk between HMGB1 and inflammatory cytokines. Third, oxidative stress is involved in the release of the pro-inflammatory cytokine, HMGB1, indicating there is cross-talk between oxidative stress and inflammation, and oxidative stress may reinforce the effect of inflammation on the pathogenesis of AF and inflammation may play a more important role in the pathogenesis of AF. Fourth, HMGB1 can promote matrix metalloproteinase-9 upregulation and activation. Fifth, HMGB1 receptors (receptor for advanced glycation end products, Toll-like receptor-2,4) may mediate the atrial structural remodeling or be up-regulated in patients with non-valvular AF. These results suggest that HMGB1 may participate in the pathogenesis of AF and provide a potential target for pharmacological interruption of AF.
Atrial Fibrillation ; metabolism ; HMGB1 Protein ; metabolism ; Humans ; Metalloendopeptidases ; metabolism ; Oxidative Stress ; physiology

OBJECTIVETo investigate the influence of high mobility group box 1 (HMGB1) on the expression of interleukin 6 (IL-6), receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG) on periodontal ligament fibroblasts.

METHODSHuman periodontal ligament fibroblasts were stimulated with HMGB1 at concentrations of 10, 30, and 100 ng x mL(-1) for 24 h. RT-PCR and Western blot analysis were performed to check mRNA and protein expression of IL-6, RANKL and OPG on the cells.

RESULTSThe ratio of RANKL/OPG was increased at both mRNA and protein level after HMGB1 stimulation at 10, 30, 100 ng x mL(-1). Inflammatory cytokine IL-6 was upregulated by HMGB1 at the concentration of 100 ng x mL(-1).

CONCLUSIONIncreased ratio of RANKL/OPG and IL-6 on periodontal ligament fibroblasts suggests that HMGB1 might play a role in the pathogenesis and progression of periodontal disease.

Cells, Cultured ; Fibroblasts ; metabolism ; HMGB1 Protein ; metabolism ; Humans ; Interleukin-6 ; metabolism ; Osteoprotegerin ; metabolism ; Periodontal Ligament ; cytology ; RANK Ligand ; metabolism

Bone substitute material implantation has become an important treatment strategy for the repair of oral and maxillofacial bone defects. Recent studies have shown that appropriate inflammatory and immune cells are essential factors in the process of osteoinduction of bone substitute materials. Previous studies have mainly focused on innate immune cells such as macrophages. In our previous work, we found that T lymphocytes, as adaptive immune cells, are also essential in the osteoinduction procedure. As the most important antigen-presenting cell, whether dendritic cells (DCs) can recognize non-antigen biomaterials and participate in osteoinduction was still unclear. In this study, we found that surgical trauma associated with materials implantation induces necrocytosis, and this causes the release of high mobility group protein-1 (HMGB1), which is adsorbed on the surface of bone substitute materials. Subsequently, HMGB1-adsorbed materials were recognized by the TLR4-MYD88-NFκB signal axis of dendritic cells, and the inflammatory response was activated. Finally, activated DCs release regeneration-related chemokines, recruit mesenchymal stem cells, and initiate the osteoinduction process. This study sheds light on the immune-regeneration process after bone substitute materials implantation, points out a potential direction for the development of bone substitute materials, and provides guidance for the development of clinical surgical methods.
Biocompatible Materials/metabolism* ; HMGB1 Protein/metabolism* ; Myeloid Differentiation Factor 88/metabolism* ; Bone Substitutes/metabolism* ; Dendritic Cells/metabolism*

High mobility group box 1 protein (HMGB1), a damage-associated molecular pattern, exists ubiquitously in the cells of mammals. It contributes to maintaining the structure of nucleosome and modulating transcription of gene in nuclei. Extracellular HMGB1 plays two-way roles in promoting inflammatory and tissue repair. Released actively as well as passively following cytokine stimulation during cell death, HMGB1 may act as a late inflammatory factor and an endogenous damage-associated molecular pattern recognized by its receptors. And it may mediate the occurrence, development and outcome of the inflammatory injury of digestive system diseases, such as gastric mucosal injury, inflammatory bowel-disease, liver injury, pancreatitis, and so on. This review mainly concerns the research progresses of HMGB1 in the inflammatory injury of digestive system diseases. At the same time, HMGB1 itself, or as a therapeutic target, can promote tissue repair.
Animals ; Digestive System Diseases ; pathology ; HMGB1 Protein ; metabolism ; Humans ; Inflammation ; pathology

Animals ; Endotoxins ; Female ; HMGB1 Protein ; biosynthesis ; Liver Failure, Acute ; chemically induced ; metabolism ; Male ; Rats ; Rats, Wistar

This study was aimed to establish a stable subline of K562 cells (K562-HMGB1) overexpressing HMGB1 protein and K562-HMGB1 sublines served as control, so as to provide a basis for exploring the role of hmgb1 gene in occurrence and development of leukemia and their mechanism. Protein-coding gene of hmgb1 was amplified by PCR with cDNA as template, which was synthesized by reverse transcription from total RNA extracted from U937 cells. The PCR-amplified hmgb1 gene was ligated into PMD18-T vector (PMD18-T-HMGB1 vector), and then transformed into E. coli strain DH5α. DH5α containing PMD18-T-HMGB1 vector were grown on LB agar plate supplemented with 100 µg/ml ampicillin overnight. The single ampicillin-selected DH5α clone was picked for culturing overnight and then harvested for plasmid extraction. The extracted plasmid was characterized to contain hmgb1 gene digested with the desired restriction enzymes of KpnI/XhoI. The correctness of hmgb1 sequence was confirmed with DNA sequencing. The insert of hmgb1 gene contained in PMD18-T-HMGB1 vector was cut out with restriction enzymes of KpnI/XhoI and then ligated into eukaryotic expression vector pcDNA3.1 to form pcDNA3.1-HMGB1 vector. 10µg of pcDNA3.1-HMGB1 or pcDNA3.1 plasmid was separately electroporated into K562 cells. At 48 hours after electroporation the cells were cultured with G418 at a final concentration of 800 µg/ml for over 2 weeks. Finally stably transfected sublines of K562 cells containing hmgb1 gene (K562-HMGB1), and of K562 containing pcDNA3.1 vector (K562-pcDNA3.1) served as a control, were obtained. The transcriptional or translational expression of hmgb1 gene was detected with RT-PCR or Western blot, respectively, to testify transfected efficiency and validity of stable subline of K562-HMGB1. The results indicated that the eukaryotic expression vector pcDNA3.1-HMGB1 plasmid was successfully constructed and was electroporated into K562 cells. The transcriptional or translational expression of hmgb1 gene in the stable subline of K562 cells containing hmgb1 gene was overexpressed. It indicated that stable subline of K562-HMGB1 cells was successfully established. It is concluded that the stable sublines of K562-HMGB1 cells or K562-pcDNA3.1 cells are successfully established, which provides a basis for exploring the roles and mechanisms of hmgb1 gene in leukemogenesis and development of leukemia.
Gene Expression ; Genes, Regulator ; Genetic Vectors ; HMGB1 Protein ; genetics ; Humans ; K562 Cells ; metabolism ; Plasmids ; Transformation, Genetic

High-mobility group box 1 (HMGB1) is a non-histone nuclear protein in most eukaryocytes. Inside the nucleus, HMGB1 plays an important role in several DNA events such as DNA repair, transcription, telomere maintenance, and genome stability. While outside the nucleus, it fulfils more complicated functions, including promoting cell proliferation, inflammation, angiogenesis, immune tolerance and immune escape, which may play a pro-tumoral role.Meanwhile, HMGB1 acts as an anti-tumoral protein by regulating immune cell recruitment and inducing immunogenic cell death (ICD) during the carcinogenesis process. Therefore, abnormal expression of HMGB1 is associated with oncogenesis, development, and metastasis of cancer, which may play a dual role of pro-tumor and anti-tumor.
Carcinogenesis ; Cell Proliferation ; HMGB1 Protein/metabolism* ; Humans ; Neoplasms/pathology* ; Neovascularization, Pathologic

OBJECTIVETo investigate the effect of hydrogen dioxide (H(2)O(2)) on the release and translocation of high mobility group box 1 release (HMGB1) from normal human bronchiolar epithelial cells (HBE).

METHODSMTT assay was used to assess the viability of HBE135-E6E7 cells exposed to different concentrations of H(2)O(2). The expression and location of HMGB1 in the cytoplasm, nuclei and culture medium of the exposed cells were determined using Western blotting and immunofluorescence assay.

RESULTSExposure to 125 µmmol/L H(2)O(2) did not obviously affect the cell viability. At the concentration of 250 µmmol/L, H(2)O(2) significantly decreased the cell viability (P<0.05), but significant cell death occurred only after exposure to 400 µmmol/L H(2)O(2) (P=0.000). Compared with the control cells, the cells exposed to 12.5, 125 and 250 µmmol/L H(2)O(2) for 24 h showed significantly increased levels of HMGB1 in the culture medium (P<0.05), and exposure to 125 µmmol/L H(2)O(2) for 12 and 24 h also caused significantly increased HMGB1 level (P<0.05). Exposure to 125 µmmol/L H(2)O(2) for 24 h significantly increased HMGB1 expression in the cytoplasm but decreased its expression in the nucleus. HMGB1 translocation from the nuclei to the cytoplasm and to the plasmalemma occurred after 125 µmmol/L H(2)O(2) exposure for 12 h and 24 h, respectively.

CONCLUSIONH(2)O(2) can induce HMGB1 translocation and release in human bronchial epithelial cells, suggesting the involvement of HMGB1 in airway oxidative stress in chronic inflammatory diseases such as asthma and COPD.

Bronchi ; cytology ; Cell Line ; Epithelial Cells ; drug effects ; metabolism ; HMGB1 Protein ; drug effects ; metabolism ; Humans ; Hydrogen Peroxide ; pharmacology ; Protein Transport