A high-sensitivity method for detection and measurement of HMGB1 protein concentration by high-affinity binding to DNA hemicatenanes

Fiber Optic Localized Surface Plasmon Resonance Sensor Based on Carboxymethylated Dextran Modified Gold Nanoparticles Surface for High Mobility Group Box 1 (HMGB1) Analysis

Rapid, sensitive, and reliable detection of high mobility group box 1 (HMGB1) is essential for medical and diagnostic applications due to its important role as a biomarker of chronic inflammation. Here, we report a facile method for the detection of HMGB1 using carboxymethyl dextran (CM-dextran) as a bridge molecule modified on the surface of gold nanoparticles combined with a fiber optic localized surface plasmon resonance (FOLSPR) biosensor. Under optimal conditions, the results showed that the FOLSPR sensor detected HMGB1 with a wide linear range (10^-10 to 10^-6 g/mL), fast response (less than 10 min), and a low detection limit of 43.4 pg/mL (1.7 pM) and high correlation coefficient values (>0.9928). Furthermore, the accurate quantification and reliable validation of kinetic binding events measured by the currently working biosensors are comparable to surface plasmon resonance sensing systems, providing new insights into direct biomarker detection for clinical applications.

Clinical Biomarker of Sterile Inflammation, HMGB1, in Patients with Chronic Non-Specific Low Back Pain: A Pilot Cross-Sectional Study

The present study explores whether the inflammatory biomarker of sterile inflammation, high mobility box 1 (HMGB1), contributes to the inflammatory/nociceptive pathophysiology that characterizes chronic non-specific low back pain (LBP). Patients with chronic LBP (N = 10, >3 pain score on a 11-point Visual Analogue Scale, VAS) and asymptomatic participants (N = 12) provided peripheral blood (PB) samples. The proportion of classical CD14++ monocytes within PB leukocytes was determined by flow cytometry. The plasma and extracellular HMGB1 levels in unstimulated adherent cell (AC) cultures were measured using specific immunoassays. HMGB1 localization in ACs was assessed by immunofluorescent staining. The relative gene expression levels of tumor necrosis factor α (TNFα), interleukin-1 beta (IL-1β) and HMGB1 were determined by quantitative polymerase chain reaction (qRT-PCR) in relation to the pain intensity (11-point VAS scores) in patients with LBP. The extracellular release of HMGB1 in the LBP patient AC cultures was significantly elevated (p = 0.001) and accompanied by its relocation into the cytoplasm from the nuclei. The number of CD14++ monocytes in the patients' PB was significantly (p = 0.03) reduced, while the HMGB1 plasma levels remained comparable to those of the controls. The mRNA levels of TNFα, IL-1β and HMGB1 were overexpressed relative to the controls and those of HMGB1 and IL-1β were correlated with the VAS scores at a significant level (p = 0.01-0.03). The results suggest that HMGB1 may play an important role in the pathophysiology of chronic non-specific LBP.

Progress in Assays of HMGB1 Levels in Human Plasma—The Potential Prognostic Value in COVID-19

Extracellular HMGB1 protein is known to induce inflammatory responses leading to an inflammatory storm. The outbreak of the Severe Acute Respiratory Syndrome COVID-19 due to the SARS-CoV-2 virus has resulted in a huge health concern worldwide. Recent data revealed that plasma/serum HMGB1 levels of patients suffering from inflammation-mediated disorders—such as COVID-19, cancer, and autoimmune disorders—correlate positively with disease severity and vice versa. A late release of HMGB1 in sepsis suggests the existence of a wide therapeutic window for treating sepsis. Rapid and accurate methods for the detection of HMGB1 levels in plasma/serum are, therefore, of great importance for monitoring the occurrence, treatment success, and survival prediction of patients with inflammation-mediated diseases. In this review, we briefly explain the role of HMGB1 in the cell, and particularly the involvement of extracellular HMGB1 (released from the cells) in inflammation-mediated diseases, with an emphasis on COVID-19. The current assays to measure HMGB1 levels in human plasma—Western blotting, ELISA, EMSA, and a new approach based on electrochemical immunosensors, including some of our preliminary results—are presented and thoroughly discussed.

High Mobility Group Box 1: Biological Functions and Relevance in Oxidative Stress Related Chronic Diseases

In the early 1970s, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and named high-mobility group (HMG) proteins. High-mobility group box 1 (HMGB1) is the most studied HMG protein that detects and coordinates cellular stress response. The biological function of HMGB1 depends on its subcellular localization and expression. It plays a critical role in the nucleus and cytoplasm as DNA chaperone, chromosome gatekeeper, autophagy maintainer, and protector from apoptotic cell death. HMGB1 also functions as an extracellular alarmin acting as a damage-associated molecular pattern molecule (DAMP). Recent findings describe HMGB1 as a sophisticated signal of danger, with a pleiotropic function, which is useful as a clinical biomarker for several disorders. HMGB1 has emerged as a mediator in acute and chronic inflammation. Furthermore, HMGB1 targeting can induce beneficial effects on oxidative stress related diseases. This review focus on HMGB1 redox status, localization, mechanisms of release, binding with receptors, and its activities in different oxidative stress-related chronic diseases. Since a growing number of reports show the key role of HMGB1 in socially relevant pathological conditions, to our knowledge, for the first time, here we analyze the scientific literature, evaluating the number of publications focusing on HMGB1 in humans and animal models, per year, from 2006 to 2021 and the number of records published, yearly, per disease and category (studies on humans and animal models).

O-GlcNAcylation of High Mobility Group Box 1 (HMGB1) Alters Its DNA Binding and DNA Damage Processing Activities

Protein O-GlcNAcylation is an essential and dynamic regulator of myriad cellular processes, including DNA replication and repair. Proteomic studies have identified the multifunctional nuclear protein HMGB1 as O-GlcNAcylated, providing a potential link between this modification and DNA damage responses. Here, we verify the protein's endogenous modification at S100 and S107 and found that the major modification site is S100, a residue that can potentially influence HMGB1-DNA interactions. Using synthetic protein chemistry, we generated site-specifically O-GlcNAc-modified HMGB1 at S100 and characterized biochemically the effect of the sugar modification on its DNA binding activity. We found that O-GlcNAc alters HMGB1 binding to linear, nucleosomal, supercoiled, cruciform, and interstrand cross-linked damaged DNA, generally resulting in enhanced oligomerization on these DNA structures. Using cell-free extracts, we also found that O-GlcNAc reduces the ability of HMGB1 to facilitate DNA repair, resulting in error-prone processing of damaged DNA. Our results expand our understanding of the molecular consequences of O-GlcNAc and how it affects protein-DNA interfaces. Importantly, our work may also support a link between upregulated O-GlcNAc levels and increased rates of mutations in certain cancer states.

Sample Preparation Strategies for Antibody-Free Quantitative Analysis of High Mobility Group Box 1 Protein

Sickness behavior and fatigue are induced by cerebral mechanisms involving inflammatory cytokines. High mobility group box 1 (HMGB1) is an alarmin, and a potential key player in this process. Reliable quantification methods for total HMGB1 and its redox variants must be established in order to clearly understand how it functions. Current methods pose significant challenges due to interference from other plasma proteins and autoantibodies. We aimed to develop an antibody-free sample preparation method followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to measure HMGB1 in human plasma. Different methods were applied for the removal of interfering proteins and the enrichment of HMGB1 from spiked human plasma samples. A comparison of methods showed an overall low extraction recovery (<40%), probably due to the stickiness of HMGB1. Reversed-phase liquid chromatography separation of intact proteins in diluted plasma yielded the most promising results. The method produced an even higher degree of HMGB1 purification than that observed with immunoaffinity extraction. Detection sensitivity needs to be further improved for the measurement of HMGB1 in patient samples. Nevertheless, it has been demonstrated that a versatile and fully antibody-free sample preparation method is possible, which could be of great use in further investigations.

Molecular Behavior of HMGB1 in the Cochlea Following Noise Exposure and in vitro

Noise-induced hearing loss (NIHL) is characterized by cellular damage to the inner ear, which is exacerbated by inflammation. High-mobility group box 1 (HMGB1), a representative damage-associated molecular pattern (DAMP), acts as a mediator of inflammation or an intercellular messenger according to its cellular localization. Blocking or regulating HMGB1 offers an attractive approach in ameliorating NIHL. However, the precise therapeutic intervention must be based on a deeper understanding of its dynamic molecular distribution and function in cochlear pathogenesis after acoustic trauma. Here, we have presented the spatiotemporal dynamics of the expression of HMGB1, exhibiting distribution variability in specific cochlear regions and cells following noise exposure. After gene manipulation, we further investigated the characteristics of cellular HMGB1 in HEI-OC1 cells. The higher cell viability observed in the HMGB1 knocked-down group after stimulation with H₂O₂ indicated the possible negative effect of HMGB1 on cellular lifespan. In conclusion, this study demonstrated that HMGB1 is involved in NIHL pathogenesis and its molecular biology has essential and subtle influences, preserving a translational potential for pharmacological intervention.

Post-translational modifications of high mobility group box 1 and cancer

Post-translational modifications (PTMs) of High mobility group box 1 (HMGB1) have not been investigated as extensively as those of other HMG proteins but accumulating evidence has shown the remarkable biological significances induced by the post-translational: acetylation, methylation and phosphorylation, oxidation, glycosylation and ADP-ribosylation of the HMGB1 to modulate its interactions with DNA and other proteins. Although HMGB1 is localized in the nucleus in almost all cells at baseline, it can be rapidly mobilized to other sites within the cell, including the cytoplasm and mitochondria, as well as into the extracellular; hence there is an increasing interest by researches into the complex relationship between the PTMs of HMGB1 protein and its diverse biological activities. The PTMs of HMGB1 could also have effects on gene expression following changes in its DNA-binding properties and in extracellular environment displays immunological activity and could serve as a potential target for new therapy. Our reviewed identifies covalent modifications of HMGB1, and highlighted how these PTMs affect the functions of HMGB1 protein in a variety of cellular and extra cellular processes as well as diseases and therapy.

Single-Multiplex Detection of Organ Injury Biomarkers using SPRi based Nano-Immunosensor

The clinical assessment of multiple organ dysfunctions at early stages is recognized to be an important factor in prompting definitive treatment decisions that prevent irreversible organ damage. In this article, we propose a real-time, label-free, and multiplex nanoenhanced SPRi platform to quantitatively assess two biomarkers, kidney injury molecule (KIM-1) and high mobility group box-1 (HMGB-1) simultaneously in buffer. Our work involves three major contributions in the design of the immunosensor: (1) we applied site-specific immobilization of antibodies to the solid surface that avoids loss of biological activity caused by covalent attachment; (2) we constructed a well-blocked sensor surface that exhibits minimal non-specific adsorption for singleplex measurements of each biomarker in buffer; and (3) we adopted a sandwich assay that implements functionalized quantum dots (NanoEnhancers) as signal amplifiers to achieve a sensitivity level of 5 pg/mL for KIM-1 and HMGB-1 in buffer. We foresee great potential and success in extending this multiplex and ultra-sensitive platform to assess a variety of other emerging clinical biomarkers at low concentrations and in complex matrices.

Hematopoietic stem and multipotent progenitor cells produce IL-17, IL-21 and other cytokines in response to TLR signals associated with late apoptotic products and augment memory Th17 and Tc17 cells in the bone marrow of normal and lupus mice

We studied effects of early and late apoptotic (necroptotic) cell products, related damage associated alarmins and TLR agonists, on hematopoietic stem and progenitor cells (HSPC). Surprisingly, normal HSPC themselves produced IL-17 and IL-21 after 1½days of stimulation, and the best stimulators were TLR 7/8 agonist; HMGB1-DNA; TLR 9 agonist, and necroptotic B cells. The stimulated HSPC expressed additional cytokines/mediators, directly causing rapid expansion of IL-17(+) memory CD4 T (Th17), and CD8 T (Tc17) cells, and antigen-experienced IL-17(+) T cells with "naïve" phenotype. In lupus marrow, HSPC were spontaneously pre-stimulated by endogenous signals to produce IL-17 and IL-21. In contrast to HSPC, megakaryocyte progenitors (MKP) did not produce IL-17, and unlike HSPC, they could process and present particulate apoptotic autoantigens to augment autoimmune memory Th17 response. Thus abnormally stimulated primitive hematopoietic progenitors augment expansion of IL-17 producing immune and autoimmune memory T cells in the bone marrow, which may affect central tolerance.

Redox status of high-mobility group box 1 performs a dual role in angiogenesis of colorectal carcinoma

During inflammation, high-mobility group box 1 in reduced all-thiol form (at-HMGB1) takes charge of chemoattractant activity, whereas only disulfide-HMGB1 (ds-HMGB1) has cytokine activity. Also as pro-angiogenic inducer, the role of HMGB1 in different redox states has never been defined in tumour angiogenesis. To verify which redox states of HMGB1 induces angiogenesis in colorectal carcinoma. To measure the expression of VEGF-A and angiogenic properties of the endothelial cells (ECs), at-HMGB1 or ds-HMGB1 was added to cell medium, further with their special inhibitors (DPH1.1 mAb and 2G7 mAb) and antibodies of corresponding receptors (RAGE Ab and TLR4 Ab). Also, a co-culture system and conditioned medium from tumour cells were applied to mimic tumour microenvironment. HMGB1 triggered VEGF-A secretion mainly through its disulfide form interacting with TLR4, while co-operation of at-HMGB1 and RAGE mediated migratory capacity of ECs. Functional inhibition of HMGB1 and its receptors abrogated HMGB1-induced angiogenic properties of ECs co-cultured with tumour cells. HMGB1 orchestrates the key events of tumour angiogenesis, migration of ECs and their induction to secrete VEGF-A, by adopting distinct redox states.

Circulating HMGB1 and RAGE as Clinical Biomarkers in Malignant and Autoimmune Diseases

High molecular group box 1 (HMGB1) is a highly conserved member of the HMG-box-family; abundantly expressed in almost all human cells and released in apoptosis; necrosis or by activated immune cells. Once in the extracellular space, HMGB1 can act as a danger associated molecular pattern (DAMP), thus stimulating or inhibiting certain functions of the immune system; depending on the “combinatorial cocktail” of the surrounding milieu. HMGB1 exerts its various functions through binding to a multitude of membrane-bound receptors such as TLR-2; -4 and -9; IL-1 and RAGE (receptor for advanced glycation end products); partly complex-bound with intracellular fragments like nucleosomes. Soluble RAGE in the extracellular space, however, acts as a decoy receptor by binding to HMGB1 and inhibiting its effects. This review aims to outline today’s knowledge of structure, intra- and extracellular functions including mechanisms of release and finally the clinical relevance of HMGB1 and RAGE as clinical biomarkers in therapy monitoring, prediction and prognosis of malignant and autoimmune disease.

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.

Redox modulation of HMGB1-related signaling

SIGNIFICANCE

In the cells' nuclei, high-mobility group box protein 1 (HMGB1) is a nonhistone chromatin-binding protein involved in the regulation of transcription. Extracellularly, HMGB1 acts as a danger molecule with properties of a proinflammatory cytokine. It can be actively secreted from myeloid cells or passively leak from any type of injured, necrotic cell. Increased serum levels of active HMGB1 are often found in pathogenic inflammatory conditions and correlate with worse prognoses in cancer, sepsis, and autoimmunity. By damaging cells, superoxide and peroxynitrite promote leakage of HMGB1.

RECENT ADVANCES

The activity of HMGB1 strongly depends on its redox state: Inflammatory-active HMGB1 requires an intramolecular disulfide bond (Cys23 and Cys45) and a reduced Cys106. Oxidation of the latter blocks its stimulatory activity and promotes immune tolerance.

CRITICAL ISSUES

Reactive oxygen and nitrogen species create an oxidative environment and can be detoxified by superoxide dismutase (SOD), catalase, and peroxidases. Modifications of the oxidative environment influence HMGB1 activity.

FUTURE DIRECTIONS

In this review, we hypothesize that manipulations of an oxidative environment by SOD mimics or by hydrogen sulfide are prone to decrease tissue damage. Both the concomitant decreased HMGB1 release and its redox chemical modifications ameliorate inflammation and tissue damage.

The influence of DNA sequence on epigenome-induced pathologies

Clear cause-and-effect relationships are commonly established between genotype and the inherited risk of acquiring human and plant diseases and aberrant phenotypes. By contrast, few such cause-and-effect relationships are established linking a chromatin structure (that is, the epitype) with the transgenerational risk of acquiring a disease or abnormal phenotype. It is not entirely clear how epitypes are inherited from parent to offspring as populations evolve, even though epigenetics is proposed to be fundamental to evolution and the likelihood of acquiring many diseases. This article explores the hypothesis that, for transgenerationally inherited chromatin structures, "genotype predisposes epitype", and that epitype functions as a modifier of gene expression within the classical central dogma of molecular biology. Evidence for the causal contribution of genotype to inherited epitypes and epigenetic risk comes primarily from two different kinds of studies discussed herein. The first and direct method of research proceeds by the examination of the transgenerational inheritance of epitype and the penetrance of phenotype among genetically related individuals. The second approach identifies epitypes that are duplicated (as DNA sequences are duplicated) and evolutionarily conserved among repeated patterns in the DNA sequence. The body of this article summarizes particularly robust examples of these studies from humans, mice, Arabidopsis, and other organisms. The bulk of the data from both areas of research support the hypothesis that genotypes predispose the likelihood of displaying various epitypes, but for only a few classes of epitype. This analysis suggests that renewed efforts are needed in identifying polymorphic DNA sequences that determine variable nucleosome positioning and DNA methylation as the primary cause of inherited epigenome-induced pathologies. By contrast, there is very little evidence that DNA sequence directly determines the inherited positioning of numerous and diverse post-translational modifications of histone side chains within nucleosomes. We discuss the medical and scientific implications of these observations on future research and on the development of solutions to epigenetically induced disorders.

HMGB1: a multifunctional alarmin driving autoimmune and inflammatory disease

HMGB1 is a non-histone nuclear protein that can serve as an alarmin to drive the pathogenesis of inflammatory and autoimmune disease. Although primarily located in the cell nucleus, HMGB1 can translocate to the cytoplasm, as well as the extracellular space, during cell activation and cell death; during activation, HMGB1 can undergo post-translational modifications. The activity of HMGB1 varies with the redox states of the cysteine residues, which are required for binding to TLR4. In addition to stimulating cells directly, HMGB1 can form immunostimulatory complexes with cytokines and other endogenous and exogenous factors. In the synovia of patients with rheumatoid arthritis, as well as animal models of this disease, extranuclear expression of HMGB1 is increased and blockade of HMGB1 expression attenuates disease in animal models. In systemic lupus erythematosus, HMGB1 can be a component of immune complexes containing anti-DNA because of its interaction with DNA. In myositis, expression of HMGB1 is enhanced in inflamed muscle and can perturb muscle function. Together, these findings indicate that HMGB1 might be an important mediator and biomarker in rheumatic diseases as well as a target of new therapy.

Stepwise release of biologically active HMGB1 during HSV-2 infection

BACKGROUND

High mobility group box 1 protein (HMGB1) is a major endogenous danger signal that triggers inflammation and immunity during septic and aseptic stresses. HMGB1 recently emerged as a key soluble factor in the pathogenesis of various infectious diseases, but nothing is known of its behaviour during herpesvirus infection. We therefore investigated the dynamics and biological effects of HMGB1 during HSV-2 infection of epithelial HEC-1 cells.

METHODOLOGY/PRINCIPAL FINDINGS

Despite a transcriptional shutdown of HMGB1 gene expression during infection, the intracellular pool of HMGB1 protein remained unaffected, indicating its remarkable stability. However, the dynamics of HMGB1 was deeply modified in infected cells. Whereas viral multiplication was concomitant with apoptosis and HMGB1 retention on chromatin, a subsequent release of HMGB1 was observed in response to HSV-2 mediated necrosis. Importantly, extracellular HMGB1 was biologically active. Indeed, HMGB1-containing supernatants from HSV-2 infected cells induced the migration of fibroblasts from murine or human origin, and reactivated HIV-1 from latently infected T lymphocytes. These effects were specifically linked to HMGB1 since they were blocked by glycyrrhizin or by a neutralizing anti-HMGB1 antibody, and were mediated through TLR2 and the receptor for Advanced Glycation End-products (RAGE). Finally, we show that genital HSV-2 active infections also promote HMGB1 release in vivo, strengthening the clinical relevance of our experimental data.

CONCLUSIONS

These observations target HMGB1 as an important actor during HSV-2 genital infection, notably in the setting of HSV-HIV co-infection.

Implications of the release of high-mobility group box 1 protein from dying cells during human immunodeficiency virus type 1 infection in vitro

Plasma levels of high-mobility group box 1 protein (HMGB1) are elevated during the course of human immunodeficiency virus type 1 (HIV-1) infection and the molecule has an impact on virus replication. This study investigated the mode of cell death and release of HMGB1 during HIV-1 infection in vitro. MT4 cells and primary CD4(+) T cells were infected with HIV-1 isolates, and HMGB1 release was monitored in relation to cytopathic effects (CPE) and apoptosis. HMGB1 release from cells was analysed by Western blotting. For MT4 cells, an enzyme-linked immunosorbent spot (ELISPOT) assay was adapted to measure the release during necrosis. Lactate dehydrogenase (LDH) activity was quantified using a commercial assay. Flow cytometry was used to determine the level of infection and apoptosis. MT4 cells were > or =90 % infected at 48 h post-infection (p.i.). CPE was first observed at 60 h and correlated with release of HMGB1, LDH activity and caspase-3 (C3) activation. HMGB1 spots were clearly detected by ELISPOT assay at 72 h p.i. Annexin V and C3 staining showed that apoptosis was substantially involved in HIV-1-related cell death. Addition of Z-VAD (a caspase inhibitor) in a single dose at 24 or 40 h p.i. decreased both the number of caspase-positive cells and the release of HMGB1. Infection of primary CD4(+) T cells showed a 22 % (median) infection rate at 96 h. Related CPE corresponded to LDH and HMGB1 release. Both necrosis and apoptosis contributed to HMGB1 liberation during HIV-1-induced cell death and the protein could induce tumour necrosis factor-alpha release from peripheral mononuclear blood cells. These data imply that passive HMGB1 release contributes to the excessive immune activation characteristic of HIV-1 pathogenesis.

[HMGB1: a link between innate and adaptive immunity]

La protéine HMGB1 (high mobility group box 1) a été originalement identifiée comme une protéine nucléaire capable de se fixer à l’ADN. Elle est considérée comme un facteur architectural de la chromatine. Des travaux récents ont pu montrer qu’HMGB1 pouvait être également présente dans le milieu extracellulaire et ont permis de caractériser les processus cellulaires qui conduisent à la libération de la protéine. HMGB1 peut se retrouver dans le milieu extracellulaire de deux façons : (1) lors d’une sécrétion active par les cellules de l’inflammation ; (2) lors d’une libération passive et rapide lorsque les cellules meurent par nécrose. Dans ces conditions, la protéine HMGB1 est capable d’agir comme un médiateur soluble impliqué dans la coordination de divers mécanismes cellulaires. HMGB1 joue un rôle crucial dans l’amplification de la réponse inflammatoire, dans l’établissement de la réponse immunitaire et dans la réparation tissulaire. Cependant, la protéine HMGB1 dans le milieu extracellulaire serait également capable d’agir comme une cytokine pro-inflammatoire et contribuerait ainsi à la pathogenèse de différentes maladies qu’elles soient d’origine inflammatoire ou infectieuse.