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

High Mobility Group Box Protein (HMGB1): A Potential Therapeutic Target for Diabetic Encephalopathy

HMGB (high mobility group B) is one of the ubiquitous non-histone nuclear protein superfamilies that make up the HMG (high mobility group) protein group. HMGB1 is involved in a variety of physiological and pathological processes in the human body, including a structural role in the cell nucleus as well as replication, repair, DNA transcription, and assembly of nuclear proteins. It functions as a signaling regulator in the cytoplasm and a pro-inflammatory cytokine in the extracellular environment. Among several studies, HMGB1 protein is also emerging as a crucial factor involved in the development and progression of diabetic encephalopathy (DE) along with other factors such as hyperglycaemia-induced oxidative and nitrosative stress. Diabetes' chronic side effect is DE, which manifests as cognitive and psychoneurological dysfunction. The HMGB1 is released outside to the extracellular medium in diabetes condition through active or passive routes, where it functions as a damage-associated molecular pattern (DAMP) molecule to activate several signaling pathways by interacting with receptors for advanced glycosylation end-products (RAGE)/toll like receptors (TLR). HMGB1 reportedly activates inflammatory pathways, disrupts the blood-brain barrier, causes glutamate toxicity and oxidative stress, and promotes neuroinflammation, contributing to the development of cognitive impairment and neuronal damage which is suggestive of the involvement of HMGB1 in the enhancement of the diabetes-induced encephalopathic condition. Additionally, HMGB1 is reported to induce insulin resistance, further exacerbating the metabolic dysfunction associated with diabetes mellitus (DM). Thus, the present review explores the possible pathways associated with DM-induced hyperactivation of HMGB1 ultimately leading to DE.

THE ALARMIN EFFECT OF HMGB1/RIP3 ON TRANSFUSION-RELATED ACUTE LUNG INJURY VIA TLR4/NF-ΚB OR MAPK PATHWAY

ABSTRACT

Nonantibody-mediated transfusion-related acute lung injury (TRALI) may account for up to 25% of TRALI cases. This indicates the need for further research to understand the pathophysiological mechanisms involved beyond antibody mediation fully. During this research, a TRALI rat model was developed using the trauma-blood loss-massive transfusion method. The severity of pulmonary edema was checked via measurement of lung histopathological changes and the amount of Evans blue dye fluid and bronchoalveolar lavage fluid protein leakage. In addition, potential mechanisms of pathophysiological pathways and inflammation cascades were investigated in TRALI rats in vivo . The findings indicated that TRALI increased inflammatory cytokines and triggered elevated levels of high-mobility group box 1 (HMGB1)/receptor-interacting protein kinase 3 (RIP3), apoptosis protein, and mRNAs in the TM (TRALI model) group as opposed to the normal control. Furthermore, TRALI activated the toll-like receptor 4/nuclear factor kappa B and mitogen-activated protein kinase signaling pathways, which partially regulated the inflammatory response in the TRALI rats. A significant increase was observed in the inflammatory mediators HMGB1 and RIP3 during the early stages of TRALI, suggesting that these mediators could be used as diagnostic markers for TRALI. In addition, HMGB1 and RIP3 promoted the inflammatory response by stimulating the toll-like receptor 44/nuclear factor kappa B and mitogen-activated protein kinase signaling pathways in the lung tissue of rats. Identifying efficient agents from inflammatory mediators such as alarmin can be an innovative scheme for diagnosing and preventing TRALI. These findings give HMGB1 and RIP3 a strong theoretical and experimental foundation for clinical use.

Advanced Biomarkers of Hepatotoxicity in Psychiatry: A Narrative Review and Recommendations for New Psychoactive Substances

One of the factors that increase the effectiveness of the pharmacotherapy used in patients abusing various types of new psychoactive substances (NPSs) is the proper functioning of the liver. However, the articles published to date on NPS hepatotoxicity only address non-specific hepatic parameters. The aim of this manuscript was to review three advanced markers of hepatotoxicity in psychiatry, namely, osteopontin (OPN), high-mobility group box 1 protein (HMGB1) and glutathione dehydrogenase (GDH, GLDH), and, on this basis, to identify recommendations that should be included in future studies in patients abusing NPSs. This will make it possible to determine whether NPSs do indeed have a hepatotoxic effect or whether other factors, such as additional substances taken or hepatitis C virus (HCV) infection, are responsible. NPS abusers are at particular risk of HCV infection, and for this reason, it is all the more important to determine what factors actually show a hepatotoxic effect in them.

The role of High-mobility group box-1 and Psoriasin in multiple myeloma: Analysis of a population affected by monoclonal gammopathies and review of the literature

Multiple myeloma (MM) is a plasma cells neoplasm which is often preceded by a preneoplastic condition called monoclonal gammopathy of unknown significance (MGUS). A protein called High-mobility group box-1 (HMGB-1) controls transcription and genomic stability. Both pro- and anti-tumor properties of HMGB1 have been described during tumor growth. The S100 protein family includes a protein known as psoriasin. Poorer prognosis and survival were linked to higher psoriasin expression in cancer patients. The goal of the current investigation was to compare the plasma levels of HMGB-1 and psoriasin in patients with MM and MGUS significance, as well as in a group of healthy controls. According to our research, patients with MGUS have higher HMGHB-1 concentrations than healthy controls (846.7 ± 287.6 pg/ml vs. 176.9 ± 204.8 pg/ml for controls, p < 0.001). Similarly, we found a huge difference in HMGB-1 levels for MM patients with respect to controls (928.0 ± 551.4 pg/ml vs. 176.9 ± 204.8 pg/ml; p = 0.001). No difference was found as for the Psoriasin levels in the three groups considered. Additionally, we tried to evaluate the knowledge already present in the literature about putative mechanisms of action for these molecules in the onset and development of these disorders.

Structural Characteristics of High-Mobility Group Proteins HMGB1 and HMGB2 and Their Interaction with DNA

Non-histone nuclear proteins HMGB1 and HMGB2 (High Mobility Group) are involved in many biological processes, such as replication, transcription, and repair. The HMGB1 and HMGB2 proteins consist of a short N-terminal region, two DNA-binding domains, A and B, and a C-terminal sequence of glutamic and aspartic acids. In this work, the structural organization of calf thymus HMGB1 and HMGB2 proteins and their complexes with DNA were studied using UV circular dichroism (CD) spectroscopy. Post-translational modifications (PTM) of HMGB1 and HMGB2 proteins were determined with MALDI mass spectrometry. We have shown that despite the similar primary structures of the HMGB1 and HMGB2 proteins, their post-translational modifications (PTMs) demonstrate quite different patterns. The HMGB1 PTMs are located predominantly in the DNA-binding A-domain and linker region connecting the A and B domains. On the contrary, HMGB2 PTMs are found mostly in the B-domain and within the linker region. It was also shown that, despite the high degree of homology between HMGB1 and HMGB2, the secondary structure of these proteins is also slightly different. We believe that the revealed structural properties might determine the difference in the functioning of the HMGB1 and HMGB2 as well as their protein partners.

Translocation of High Mobility Group Box 1 From the Nucleus to the Cytoplasm in Depressed Patients With Epilepsy

Depression is a common psychiatric comorbidity in patients with epilepsy, especially those with temporal lobe epilepsy (TLE). The aim of this study was to assess changes in high mobility group box protein 1 (HMGB1) expression in epileptic patients with and without comorbid depression. Sixty patients with drug-resistant TLE who underwent anterior temporal lobectomy were enrolled. Anterior hippocampal samples were collected after surgery and analyzed by immunofluorescence (n  = 7/group). We also evaluated the expression of HMGB1 in TLE patients with hippocampal sclerosis and measured the level of plasma HMGB1 by enzyme-linked immunosorbent assay. The results showed that 28.3% of the patients (17/60) had comorbid depression. HMGB1 was ubiquitously expressed in all subregions of the anterior hippocampus. The ratio of HMGB1-immunoreactive neurons and astrocytes was significantly increased in both TLE patients with hippocampal sclerosis and TLE patients with comorbid depression compared to patients with TLE only. The ratio of cytoplasmic to nuclear HMGB1-positive neurons in the hippocampus was higher in depressed patients with TLE than in nondepressed patients, which suggested that more HMGB1 translocated from the nucleus to the cytoplasm in the depressed group. There was no significant difference in the plasma level of HMGB1 among patients with TLE alone, TLE with hippocampal sclerosis, and TLE with comorbid depression. The results of the study revealed that the translocation of HMGB1 from the nucleus to the cytoplasm in hippocampal neurons may play a previously unrecognized role in the initiation and amplification of epilepsy and comorbid depression. The direct targeting of neural HMGB1 is a promising approach for anti-inflammatory therapy.

Alarmins in autoimmune diseases

Alarmins are endogenous, constitutively expressed, chemotacting and immune activating proteins or peptides released because of non-programmed cell death (i.e. infections, trauma, etc). They are considered endogenous damage-associated molecular patterns (DAMPs), able to induce a sterile inflammation. In the last years, several studies highlighted a possible role of different alarmins in the pathogenesis of various autoimmune and immune-mediated diseases. We reviewed the relevant literature about this topic, for about 160 articles. Particularly, we focused on systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis, idiopathic inflammatory myopathies, ANCA-associated vasculitides, Behçet's disease) and cutaneous organ-specific autoimmune diseases (vitiligo, psoriasis, alopecia, pemphigo). Finally, we discussed about future perspectives and potential therapeutic implications of alarmins in autoimmune diseases. In fact, identification of receptors and downstream signal transducers of alarmins may lead to the identification of antagonistic inhibitors and agonists, with the capacity to modulate alarmins-related pathways and potential therapeutic applicability.

Oxidized high mobility group B-1 enhances metastability of colorectal cancer via modification of mesenchymal stem/stromal cells

High mobility group box-1 (HMGB1) is known to be a chemotactic factor for mesenchymal stem/stromal cells (MSCs), but the effect of post-translational modification on its function is not clear. In this study, we hypothesized that differences in the oxidation state of HMGB1 would lead to differences in the function of MSCs in cancer. In human colorectal cancer, MSCs infiltrating into the stroma were correlated with liver metastasis and serum HMGB1. In animal models, oxidized HMGB1 mobilized 3-fold fewer MSCs to subcutaneous tumors compared to reduced HMGB1. Reduced HMGB1 inhibited proliferation of mouse bone marrow MSCs (BM-MSCs) and induced differentiation into osteoblasts and vascular pericytes, whereas oxidized HMGB1 promoted proliferation and increased stemness, and no differentiation was observed. When BM-MSCs pretreated with oxidized HMGB1 were co-cultured with syngeneic cancer cells, cell proliferation and stemness of cancer cells were increased, and tumorigenesis and drug resistance were promoted. In contrast, co-culture with reduced HMGB1-pretreated BM-MSCs did not enhance stemness. In an animal orthotopic transplantation colorectal cancer model, oxidized HMGB1, but not reduced HMGB1, promoted liver metastasis with intratumoral MSC chemotaxis. Thus, oxidized HMGB1 reprograms MSCs and promotes cancer malignancy. The oxidized HMGB1-MSC axis may be an important target for cancer therapy.

HMGB1: A Potential Target of Nervus Vagus Stimulation in Pediatric SARS-CoV-2-Induced ALI/ARDS

From the start of pandemics, children were described as the ones who were less affected by SARS-Cov-2 or COVID-19, which was mild in most of the cases. However, with the growing vaccination rate of the adult population, children became more exposed to the virus and more cases of severe SARS-CoV-2-induced ARDS are being diagnosed with the disabling consequences or lethal outcomes associated with the cytokine storm. Thus, we do hypothesize that some of the children could benefit from nervus vagus stimulation during COVID-19 ARDS through the inhibition of HMGB1 release and interaction with the receptor, resulting in decreased neutrophil accumulation, oxidative stress, and coagulopathy as well as lung vascular permeability. Moreover, stimulation through alpha-7 nicotinic acetylcholine receptors could boost macrophage phagocytosis and increase the clearance of DAMPs and PAMPs. Further rise of FGF10 could contribute to lung stem cell proliferation and potential regeneration of the injured lung. However, this stimulation should be very specific, timely, and of proper duration, as it could lead to such adverse effects as increased viral spread and systemic infection, especially in small children or infants due to specific pediatric immunity state and anatomical features of the respiratory system.

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).

Resveratrol Improves Synaptic Plasticity in Hypoxic-Ischemic Brain Injury in Neonatal Mice via Alleviating SIRT1/NF-κB Signaling-Mediated Neuroinflammation

Neonatal hypoxic-ischemic encephalopathy (HIE) is an obstinate disease that troubles neonatologists. At present, cognitive impairment after HIE has received increasing attention. Synaptic plasticity determines the development of cognitive function, so it is urgent to develop new drugs that can improve HIE-induced cognitive impairment. Hypoxia-ischemia (HI)-induced neuroinflammation affects synaptic plasticity. As a SIRT1 agonist, resveratrol has a powerful anti-inflammatory effect, but whether it has an effect on impaired synaptic plasticity in HIE and the potential mechanism remain unclear. In the present study, resveratrol was used to intervene in hypoxic-ischemic brain injury (HIBI) mice, and the effects on hippocampal synaptic plasticity and further mechanisms were explored through performing neurobehavioral, morphological observations, Golgi sliver staining, western blotting, and quantitative real-time polymerase chain reaction experiments. We first found that resveratrol improves HI-induced long-term cognitive and memory deficits, and then we found that resveratrol reduces hippocampal neuronal damage and increases dendritic spine density and the expression of synaptic proteins. Finally, we found that this effect may be exerted by regulating the neuroinflammatory response mediated by the SIRT1/NF-κB axis. This study provides a new theoretical basis for resveratrol to prevent long-term neurological dysfunction following HIBI.

Exosomal HMGB1 derived from hypoxia-conditioned bone marrow mesenchymal stem cells increases angiogenesis via the JNK/HIF-1α pathway

Mesenchymal stem cells (MSCs) have been described to induce angiogenesis in various tissues and have been used for the development of novel cell‐based therapies. Increasing evidence suggests that MSCs execute their paracrine function via the secretion of exosomes, especially under hypoxic conditions. However, the mechanisms by which MSC‐derived exosomes secreted under hypoxia enhance angiogenesis still remain unclear. To study exosome physiology under hypoxic or normoxic conditions, we isolated exosomes from bone marrow mesenchymal stem cells (BMSCs). Furthermore, we detected the uptake of exosomes by human umbilical vein endothelial cells (HUVECs) by immunofluorescence staining. In addition, we determined the effects of exosomes on cell viability, migration and tube formation in HUVECs by Cell Counting Kit‐8, migration and tube formation assays, respectively. We examined the expression of key proteins related to exosome‐induced angiogenesis by BMSCs cultured under hypoxic conditions by western blot. Exosomes released by BMSCs cultured under hypoxic conditions enhanced cell proliferation, migration and angiogenesis of HUVECs. Hypoxia induced the expression of high mobility group box 1 protein (HMGB1) in BMSC‐derived exosomes, and silencing of HMGB1 abolished the angiogenic effect in HUVECs. Furthermore, exosomal HMGB1 activated the JNK signaling pathway and induced hypoxia‐inducible factor‐1α/vascular endothelial growth factor expression, consequently enhancing angiogenesis in HUVECs. Our data reveal that exosomal HMGB1 promotes angiogenesis via JNK/hypoxia‐inducible factor‐1α signaling. Therefore, BMSC exosomes derived under hypoxia may have potential for development of novel treatment strategies for angiogenesis‐related diseases.

Fecal High-Mobility Group Box 1 as a Marker of Early Stage of Necrotizing Enterocolitis in Preterm Neonates

Introduction: An early diagnosis of necrotizing enterocolitis (NEC), a major gastrointestinal emergency in preterm newborns, is crucial to improve diagnostic approach and prognosis. We evaluated whether fecal high-mobility group box protein 1 (HMGB1) may early identify preterms at risk of developing NEC. Materials and Methods: A case-control study including neonates admitted at the Neonatal Intensive Care Unit (NICU) of the Sapienza University Hospital "Umberto I" in Rome, from July 2015 to December 2016. Stool samples obtained from cases (preterm newborns with NEC) and controls (newborns without NEC) were collected at the enrolment (T0) and within 7-14 days after the first sample collection (T1). HMGB1, extracted and measured with western blot, was reported as densitometry units (DUS). Results: HMGB1 levels in 30 cases (n = 28-Bell stage 1, n = 2 Bell stage 2) were higher [T0: 21,462 DUS (95% CI, 16,370-26,553 DUS)-T1: 17,533 DUS (95% CI, 13,052-22,014 DUS)] than in 30 preterm controls [T0: 9,446 DUS (95% CI, 6,147-12,746 DUS)-T1: 9,261 DUS (95% CI, 5,126-13,396 DUS), p < 0.001). Preterm newborns showed significant higher levels of HMGB1 (15,690 DUS (95% CI, 11,929-19,451 DUS)] in comparison with 30 full-term neonates with birth weight >2,500 g [6,599 DUS (95% CI, 3,141-10,058 DUS), p = 0.003]. Multivariate analysis showed that the risk of NEC was significantly (p = 0.012) related to the HMGB1 fecal levels at T0. Conclusions: We suggest fecal HMGB1 as a reliable marker of early NEC in preterm neonates. This study supports further investigation on the role of fecal HMGB1 assessment in managing preterm newborns at risk of NEC. Further studies are advocated to evaluate diagnostic accuracy of this marker in more severe forms of the disease.

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.