ELEVATED HIGH-MOBILITY GROUP BOX 1 LEVELS IN PATIENTS WITH CEREBRAL AND MYOCARDIAL ISCHEMIA

Probing the interactions of genistein with HMGB1 through multi-spectroscopic and in-silico approaches

Functional regulation of proteins by ligand-protein interactions plays a crucial role in understanding biological processes and identifying potential drugs. High mobility group box 1 (HMGB1) plays a pivotal role in sterile inflammation as a key immunomodulatory protein. Genistein, a well-known isoflavone compound, has been shown to have neuroprotective effects. In this study, we investigated the genistein-HMGB1 interactions using experimental and computational approaches. Our results revealed that genistein binds to HMGB1 with a KD value of 6.06 × 10-5 M. The addition of genistein significantly quenched the fluorescence of HMGB1. Thermodynamic analyses demonstrated that hydrogen bonds and hydrophobic forces are the primary forces during the binding process. Furthermore, the interaction between genistein and HMGB1 led to changes in the microenvironment of protein chromogenic amino acids and subtle alterations in the protein secondary structure. Molecular modeling results indicate that Pro95, Pro98, and Lys154 are the major amino acid residues for genistein binding to HMGB1. Meanwhile, at the cellular level, an inhibitory effect of genistein on HMGB1-induced NO release from microglia was observed, demonstrating an inhibition rate of 42.1 %. Our studies demonstrated that genistein could be applied in treating neurological diseases through its interaction with HMGB1.

Targeting high-mobility-group-box-1-mediated inflammation: a promising therapeutic approach for myocardial infarction

Myocardial ischemia, resulting from coronary artery blockage, precipitates cardiac arrhythmias, myocardial structural changes, and heart failure. The pathophysiology of MI is mainly based on inflammation and cell death, which are essential in aggravating myocardial ischemia and reperfusion injury. Emerging research highlights the functionality of high mobility group box-1, a non-histone nucleoprotein functioning as a chromosomal stabilizer and inflammatory mediator. HMGB1's release into the extracellular compartment during ischemia acts as damage-associated molecular pattern, triggering immune reaction by pattern recognition receptors and exacerbating tissue inflammation. Its involvement in signaling pathways like PI3K/Akt, TLR4/NF-κB, and RAGE/HMGB1 underscores its significance in promoting angiogenesis, apoptosis, and reducing inflammation, which is crucial for MI treatment strategies. This review highlights the complex function of HMGB1 in the pathogenesis of myocardial infarction by summarizing novel findings on the protein in ischemic situations. Understanding the mechanisms underlying HMGB1 could widen the way to specific treatments that minimize the severity of MI and enhance patient outcomes.

High Mobility Group Box 1 and Cardiovascular Diseases: Study of Act and Connect

Cardiovascular disease is the deadly disease that can result in sudden death, and inflammation plays an important role in its onset and progression. High mobility group box 1 (HMGB1) is a nuclear protein that regulates transcription, DNA replication, repair, and nucleosome assembly. HMGB1 is released passively by necrotic tissues and actively secreted by stressed cells. Extracellular HMGB1 functions as a damage associated molecular patterns molecule, producing numerous redox forms that induce a range of cellular responses by binding to distinct receptors and interactors, including tissue inflammation and regeneration. Extracellular HMGB1 inhibition reduces inflammation and is protective in experimental models of myocardial ischemia/reperfusion damage, myocarditis, cardiomyopathies caused by mechanical stress, diabetes, bacterial infection, or chemotherapeutic drugs. HMGB1 administration following a myocardial infarction followed by permanent coronary artery ligation improves cardiac function by stimulating tissue regeneration. HMGB1 inhibits contractility and produces hypertrophy and death in cardiomyocytes, while also stimulating cardiac fibroblast activity and promoting cardiac stem cell proliferation and differentiation. Maintaining normal nuclear HMGB1 levels, interestingly, protects cardiomyocytes from apoptosis by limiting DNA oxidative stress, and mice with HMGB1cardiomyocyte-specific overexpression are partially protected from cardiac injury. Finally, elevated levels of circulating HMGB1 have been linked to human heart disease. As a result, following cardiac damage, HMGB1 elicits both detrimental and helpful responses, which may be due to the formation and stability of the various redox forms, the particular activities of which in this context are mostly unknown. This review covers recent findings in HMGB1 biology and cardiac dysfunction.

Constitutive DAMPs in CNS injury: From preclinical insights to clinical perspectives

Damage-associated molecular patterns (DAMPs) are endogenous molecules released in tissues upon cellular damage and necrosis, acting to initiate sterile inflammation. Constitutive DAMPs (cDAMPs) have the particularity to be present within the intracellular compartments of healthy cells, where they exert diverse functions such as regulation of gene expression and cellular homeostasis. However, after injury to the central nervous system (CNS), cDAMPs are rapidly released by stressed, damaged or dying neuronal, glial and endothelial cells, and can trigger inflammation without undergoing structural modifications. Several cDAMPs have been described in the injured CNS, such as interleukin (IL)-1α, IL-33, nucleotides (e.g. ATP), and high-mobility group box protein 1. Once in the extracellular milieu, these molecules are recognized by the remaining surviving cells through specific DAMP-sensing receptors, thereby inducing a cascade of molecular events leading to the production and release of proinflammatory cytokines and chemokines, as well as cell adhesion molecules. The ensuing immune response is necessary to eliminate cellular debris caused by the injury, allowing for damage containment. However, seeing as some molecules associated with the inflammatory response are toxic to surviving resident CNS cells, secondary damage occurs, aggravating injury and exacerbating neurological and behavioral deficits. Thus, a better understanding of these cDAMPs, as well as their receptors and downstream signaling pathways, could lead to identification of novel therapeutic targets for treating CNS injuries such as SCI, TBI, and stroke. In this review, we summarize the recent literature on cDAMPs, their specific functions, and the therapeutic potential of interfering with cDAMPs or their signaling pathways.

Expression of HMGB1, TGF-β1, BIRC3, ADAM17, CDKN1A, and FTO in Relation to Left Ventricular Remodeling in Patients Six Months after the First Myocardial Infarction: A Prospective Study

Background: After myocardial infarction (MI), adverse left ventricular (LV) remodeling may occur. This is followed by LV hypertrophy and eventually heart failure. The remodeling process is complex and goes through multiple phases. The aim of this study was to investigate the expression of HMGB1, TGF-β1, BIRC3, ADAM17, CDKN1A, and FTO, each involved in a specific step of LV remodeling, in association with the change in the echocardiographic parameters of LV structure and function used to assess the LV remodeling process in the peripheral blood mononuclear cells (PBMCs) of patients six months after the first MI. The expression of selected genes was also determined in PBMCs of controls. Methods: The study group consisted of 99 MI patients, who were prospectively followed-up for 6 months, and 25 controls. Cardiac parameters, measured via conventional 2D echocardiography, were evaluated at two time points: 3-5 days and 6 months after MI. The mRNA expression six-months-post-MI was detected using TaqMan® technology (Applied Biosystems, Thermo Fisher Scientific, Waltham, MA, USA). Results:HMGB1 mRNA was significantly higher in patients with adverse LV remodeling six-months-post-MI than in patients without adverse LV remodeling (p = 0.04). HMGB1 mRNA was significantly upregulated in patients with dilated LV end-diastolic diameter (LVEDD) (p = 0.03); dilated LV end-diastolic volume index (LVEDVi) (p = 0.03); severely dilated LV end-systolic volume index (LVESVi) (p = 0.006); impaired LV ejection fraction (LVEF) (p = 0.01); and LV enlargement (p = 0.03). It was also significantly upregulated in PBMCs from patients compared to controls (p = 0.005). TGF-β1 and BIRC3 mRNA were significantly lower in patients compared to controls (p = 0.02 and p = 0.05, respectively). Conclusions: Our results suggest that HMGB1 is involved in adverse LV remodeling six-months-post-MI, even on the mRNA level. Further research and validation are needed.

Ischemic stroke and diabetes: a TLR4-mediated neuroinflammatory perspective

Ischemic stroke is the major contributor to morbidity and mortality in people with diabetes mellitus. In ischemic stroke patients, neuroinflammation is now understood to be one of the main underlying mechanisms for cerebral damage and recovery delay. It has been well-established that toll-like receptor 4 (TLR4) signaling pathway plays a key role in neuroinflammation. Emerging research over the last decade has revealed that, compared to ischemic stroke without diabetes mellitus, ischemic stroke with diabetes mellitus significantly upregulates TLR4-mediated neuroinflammation, increasing the risk of cerebral and neuronal damage as well as neurofunctional recovery delay. This review aims to discuss how ischemic stroke with diabetes mellitus amplifies TLR4-mediated neuroinflammation and its consequences. Additionally covered in this review is the potential application of TLR4 antagonists in the management of diabetic ischemic stroke.

Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling

Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. Receptor interacting protein kinase-3 (RIPK3) signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of damage-associated molecular pattern signaling. In mechanistic experiments, we showed that factors released from dying neurons signaled through receptor for advanced glycation endproducts to induce astrocytic RIPK3 signaling, which conferred inflammatory and neurotoxic functional activity. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.

Hypochlorous acid derived from microglial myeloperoxidase could mediate high-mobility group box 1 release from neurons to amplify brain damage in cerebral ischemia-reperfusion injury

Myeloperoxidase (MPO) plays critical role in the pathology of cerebral ischemia-reperfusion (I/R) injury via producing hypochlorous acid (HOCl) and inducing oxidative modification of proteins. High-mobility group box 1 (HMGB1) oxidation, particularly disulfide HMGB1 formation, facilitates the secretion and release of HMGB1 and activates neuroinflammation, aggravating cerebral I/R injury. However, the cellular sources of MPO/HOCl in ischemic brain injury are unclear yet. Whether HOCl could promote HMGB1 secretion and release remains unknown. In the present study, we investigated the roles of microglia-derived MPO/HOCl in mediating HMGB1 translocation and secretion, and aggravating the brain damage and blood-brain barrier (BBB) disruption in cerebral I/R injury. In vitro, under the co-culture conditions with microglia BV cells but not the single culture conditions, oxygen-glucose deprivation/reoxygenation (OGD/R) significantly increased MPO/HOCl expression in PC12 cells. After the cells were exposed to OGD/R, MPO-containing exosomes derived from BV2 cells were released and transferred to PC12 cells, increasing MPO/HOCl in the PC12 cells. The HOCl promoted disulfide HMGB1 translocation and secretion and aggravated OGD/R-induced apoptosis. In vivo, SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus different periods of reperfusion. Increased MPO/HOCl production was observed at the reperfusion stage, accomplished with enlarged infarct volume, aggravated BBB disruption and neurological dysfunctions. Treatment of MPO inhibitor 4-aminobenzoic acid hydrazide (4-ABAH) and HOCl scavenger taurine reversed those changes. HOCl was colocalized with cytoplasm transferred HMGB1, which was blocked by taurine in rat I/R-injured brain. We finally performed a clinical investigation and found that plasma HOCl concentration was positively correlated with infarct volume and neurological deficit scores in ischemic stroke patients. Taken together, we conclude that ischemia/hypoxia could activate microglia to release MPO-containing exosomes that transfer MPO to adjacent cells for HOCl production; Subsequently, the production of HOCl could mediate the translocation and secretion of disulfide HMGB1 that aggravates cerebral I/R injury. Furthermore, plasma HOCl level could be a novel biomarker for indexing brain damage in ischemic stroke patients.

Crosstalk between myocardial autophagy and sterile inflammation in the development of heart failure

Heart failure, a leading driver of global mortality, remains a topic of intense contemporary research interest due to the prevailing unmet need in cardiometabolic therapeutics. Numerous mechanisms with the potential to influence the onset and development of heart failure remain incompletely understood. Firstly, myocardial autophagy, which involves lysosomal degradation of damaged cellular components, confers context-dependent beneficial and detrimental effects. Secondly, sterile inflammation may arise following cardiac stress and exacerbate the progression of heart failure. Inflammation changes in a temporal manner and its onset must be adequately resolved to limit progression of heart failure. Mitochondria are an important factor in contributing to sterile inflammation by releasing damage associated molecular patterns (DAMPs) including mitochondrial DNA (mtDNA). Accordingly, this is one reason why the selective autophagy of mitochondria to maintain optimal function is important in determining cardiac function. In this review, we examine the increasing evidence suggesting crosstalk between autophagy and sterile inflammation together with their role in the development of heart failure. In particular, this is exemplified in the preclinical models of ischaemia/reperfusion injury and pressure overload induced heart failure. We also highlight potential therapeutic approaches focusing on autophagy and addressing sterile inflammation, aiming to enhance outcomes in heart failure.

A review on regulation of DNA methylation during post-myocardial infarction

Myocardial infarction (MI) imposes a huge medical and economic burden on society, and cardiac repair after MI involves a complex series of processes. Understanding the key mechanisms (such as apoptosis, autophagy, inflammation, and fibrosis) will facilitate further drug development and patient treatment. Presently, a substantial body of evidence suggests that the regulation of epigenetic processes contributes to cardiac repair following MI, with DNA methylation being among the notable epigenetic factors involved. This article will review the research on the mechanism of DNA methylation regulation after MI to provide some insights for future research and development of related drugs.

Vesicular HMGB1 release from neurons stressed with spreading depolarization enables confined inflammatory signaling to astrocytes

The role of high mobility group box 1 (HMGB1) in inflammation is well characterized in the immune system and in response to tissue injury. More recently, HMGB1 was also shown to initiate an "inflammatory signaling cascade" in the brain parenchyma after a mild and brief disturbance, such as cortical spreading depolarization (CSD), leading to headache. Despite substantial evidence implying a role for inflammatory signaling in prevalent neuropsychiatric disorders such as migraine and depression, how HMGB1 is released from healthy neurons and how inflammatory signaling is initiated in the absence of apparent cell injury are not well characterized. We triggered a single cortical spreading depolarization by optogenetic stimulation or pinprick in naïve Swiss albino or transgenic Thy1-ChR2-YFP and hGFAP-GFP adult mice. We evaluated HMGB1 release in brain tissue sections prepared from these mice by immunofluorescent labeling and immunoelectron microscopy. EzColocalization and Costes thresholding algorithms were used to assess the colocalization of small extracellular vesicles (sEVs) carrying HMGB1 with astrocyte or microglia processes. sEVs were also isolated from the brain after CSD, and neuron-derived sEVs were captured by CD171 (L1CAM). sEVs were characterized with flow cytometry, scanning electron microscopy, nanoparticle tracking analysis, and Western blotting. We found that HMGB1 is released mainly within sEVs from the soma of stressed neurons, which are taken up by surrounding astrocyte processes. This creates conditions for selective communication between neurons and astrocytes bypassing microglia, as evidenced by activation of the proinflammatory transcription factor NF-ĸB p65 in astrocytes but not in microglia. Transmission immunoelectron microscopy data illustrated that HMGB1 was incorporated into sEVs through endosomal mechanisms. In conclusion, proinflammatory mediators released within sEVs can induce cell-specific inflammatory signaling in the brain without activating transmembrane receptors on other cells and causing overt inflammation.

Serum HMGB1 is a biomarker for acute myocardial infarction with or without heart failure

This study measured serum high mobility group box 1 (HMGB1) levels in patients with acute myocardial infarction (AMI) and/or heart failure (HF) and evaluated their relationship with peripheral inflammatory biomarkers and cardiac biomarkers, which have not been reported before. Of the patients, 55 had AMI without HF (AMI-HF ), 42 had AMI with HF (AMI+HF ), and 60 had HF without AMI (HF-AMI ) compared with 50 healthy controls. Blood samples were collected to assess serum HMGB1 levels and blood test-related inflammatory biomarkers (e.g., erythrocyte sedimentation rate [ESR], hs-CRP, uric acid, and white blood cell count) and cardiac biomarkers (e.g., MYO, cTnI, CKMB, CK, NT-proBNP, LDH, aspartate aminotransferase [AST], and alanine aminotransferase [ALT]). Compared to healthy controls, three groups of patients, especially those with AMI+HF , had significantly higher levels of serum HMGB1. All tested inflammatory biomarkers (except uric acid) were significantly positively correlated with HMGB1 in patients with AMI patients but not in patients with non-AMI. In addition, all tested cardiac biomarkers (except NT-proBNP in AMI-HF ) were significantly higher in patients with AMI than in control individuals. The levels of MYO, cTnI, CKMB, CK, AST, and ALT were not significantly changed in patients with HF-AMI compared to control individuals, but were still much lower than those in patients with AMI (except ALT). In all patients, the levels of NT-proBNP, and cTnI were significantly correlated with HMGB1 levels. Except for MYO, LDH, AST, and ALT, all cardiac biomarkers in AMI-HF and AMI+HF showed a significant correlation with HMGB1. Among risk factors, hypertension, diabetes, previous heart disease, and reduced left ventricular ejection fraction showed a significant correlation with HMGB1 in all disease groups.

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

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

Neuronal DAMPs exacerbate neurodegeneration via astrocytic RIPK3 signaling

Astrocyte activation is a common feature of neurodegenerative diseases. However, the ways in which dying neurons influence the activity of astrocytes is poorly understood. RIPK3 signaling has recently been described as a key regulator of neuroinflammation, but whether this kinase mediates astrocytic responsiveness to neuronal death has not yet been studied. Here, we used the MPTP model of Parkinson's disease to show that activation of astrocytic RIPK3 drives dopaminergic cell death and axon damage. Transcriptomic profiling revealed that astrocytic RIPK3 promoted gene expression associated with neuroinflammation and movement disorders, and this coincided with significant engagement of DAMP signaling. Using human cell culture systems, we show that factors released from dying neurons signal through RAGE to induce RIPK3-dependent astrocyte activation. These findings highlight a mechanism of neuron-glia crosstalk in which neuronal death perpetuates further neurodegeneration by engaging inflammatory astrocyte activation via RIPK3.

The role of circulating cell-free DNA as an inflammatory mediator after stroke

Stroke is the second leading cause of death worldwide and a leading cause of disability. Clinical and experimental studies highlighted the complex role of the immune system in the pathophysiology of stroke. Ischemic brain injury leads to the release of cell-free DNA, a damage-associated molecular pattern, which binds to pattern recognition receptors on immune cells such as toll-like receptors and cytosolic inflammasome sensors. The downstream signaling cascade then induces a rapid inflammatory response. In this review, we are highlighting the characteristics of cell-free DNA and how these can affect a local as well as a systemic response after stroke. For this purpose, we screened literature on clinical studies investigating cell-free DNA concentration and properties after brain ischemia. We report the current understanding for mechanisms of DNA uptake and sensing in the context of post-stroke inflammation. Moreover, we compare possible treatment options targeting cell-free DNA, DNA-sensing pathways, and the downstream mediators. Finally, we describe clinical implications of this inflammatory pathway for stroke patients, open questions, and potential future research directions.

High-Mobility Group Box 1-Signaling Inhibition With Glycyrrhizin Prevents Cerebral T-Cell Infiltration After Cardiac Arrest

Background High-mobility group box 1 (HMGB1) is a major promotor of ischemic injuries and aseptic inflammatory responses. We tested its inhibition on neurological outcome and systemic immune response after cardiac arrest (CA) in rabbits. Methods and Results After 10 minutes of ventricular fibrillation, rabbits were resuscitated and received saline (control) or the HMGB1 inhibitor glycyrrhizin. A sham group underwent a similar procedure without CA. After resuscitation, glycyrrhizin blunted the successive rises in HMGB1, interleukin-6, and interleukin-10 blood levels as compared with control. Blood counts of the different immune cell populations were not different in glycyrrhizin versus control. After animal awakening, neurological outcome was improved by glycyrrhizin versus control, regarding both clinical recovery and histopathological damages. This was associated with reduced cerebral CD4⁺ and CD8⁺ T-cell infiltration beginning 2 hours after CA. Conversely, granulocytes' attraction or loss of microglial cells or cerebral monocytes were not modified by glycyrrhizin after CA. These modifications were not related to the blood-brain barrier preservation with glycyrrhizin versus control. Interestingly, the specific blockade of the HMGB1 receptor for advanced glycation end products by FPS-ZM1 recapitulated the neuroprotective effects of glycyrrhizin. Conclusions Our findings support that the early inhibition of HMGB1-signaling pathway prevents cerebral chemoattraction of T cells and neurological sequelae after CA. Glycyrrhizin could become a clinically relevant therapeutic target in this situation.

Neutrophil extracellular traps: A novel target for the treatment of stroke

Stroke is a threatening cerebrovascular disease caused by thrombus with high morbidity and mortality rates. Neutrophils are the first to be recruited in the brain after stroke, which aggravate brain injury through multiple mechanisms. Neutrophil extracellular traps (NETs), as a novel regulatory mechanism of neutrophils, can trap bacteria and secret antimicrobial molecules, thereby degrading pathogenic factors and killing bacteria. However, NETs also exacerbate certain non-infectious diseases by activating autoimmune or inflammatory responses. NETs have been found to play important roles in the pathological process of stroke in recent years. In this review, the mechanisms of NETs formation, the physiological roles of NETs, and the dynamic changes of NETs after stroke are summarized. NETs participate in stroke through various mechanisms. NETs promote the coagulation cascade and interact with platelets to induce thrombosis. tPA induces the degranulation of neutrophils to form NETs, leading to hemorrhagic transformation and thrombolytic resistance. NETs aggravate stroke by mediating inflammation, atherosclerosis and vascular injury. In addition, the regulation of NETs in stroke, the potential of NETs as biomarker and the treatment of stroke targeting NETs are discussed. The increasing evidences suggest that NETs may be a potential target for stroke treatment. Inhibition of NETs formation or promotion of NETs degradation plays protective effects in stroke. However, how to avoid the adverse effects of NETs-targeted therapy deserves further study. In summary, this review provides a reference for the pathogenesis, drug targets, biomarkers and drug development of NETs in stroke.

Serum high mobility group box-1 levels associated with cardiovascular events after lower extremity revascularization: a prospective study of a diabetic population

Background

Peripheral arterial disease (PAD) is one of the most disabling cardiovascular complications of type 2 diabetes mellitus and is indeed associated with a high risk of cardiovascular and limb adverse events. High mobility group box-1 (HMGB-1) is a nuclear protein involved in the inflammatory response that acts as a pro-inflammatory cytokine when released into the extracellular space. HMBG-1 is associated with PAD in diabetic patients.

The aim of this study was to evaluate the association between serum HMGB-1 levels and major adverse cardiovascular events (MACE) and major adverse limb events (MALE) after lower-extremity endovascular revascularization (LER) in a group of diabetic patients with chronic limb-threatening ischemia (CLTI).

Methods

We conducted a prospective observational study of 201 diabetic patients with PAD and CLTI requiring LER. Baseline serum HMGB-1 levels were determined before endovascular procedure. Data on cardiovascular and limb outcomes were collected in a 12-month follow-up.

Results

During the follow-up period, 81 cases of MACE and 93 cases of MALE occurred. Patients who subsequently developed MACE and MALE had higher serum HMGB-1 levels. Specifically, 7.5 ng/mL vs 4.9 ng/mL (p < 0.01) for MACE and 7.2 ng/mL vs 4.8 ng/mL (p < 0.01) for MALE. After adjusting for traditional cardiovascular risk factors, the association between serum HMGB-1 levels and cardiovascular outcomes remained significant in multivariable analysis. In our receiver operating characteristic (ROC) curve analysis, serum HMGB-1 levels were a good predictor of MACE incidence (area under the curve [AUC] = 0.78) and MALE incidence (AUC = 0.75).

Conclusions

This study demonstrates that serum HMGB-1 levels are associated with the incidence of MACE and MALE after LER in diabetic populations with PAD and CLTI.

Modulation of α7nAchR by Melatonin Alleviates Ischemia and Reperfusion-Compromised Integrity of Blood-Brain Barrier Through Inhibiting HMGB1-Mediated Microglia Activation and CRTC1-Mediated Neuronal Loss

The only food and drug administration (FDA)-approved drug currently available for the treatment of acute ischemic stroke is tissue plasminogen activator (tPA), yet the therapeutic benefits of this drug are partially outweighed by the increased risk of hemorrhagic transformation (HT). Analysis of the NIH trial has shown that cigarette smoking protected tPA-treated patients from HT; however, the underlying mechanism is not clear. Nicotinic acetylcholine receptors (nAChR) has shown anti-inflammatory effect and modulation nAChR could be a strategy to reduce ischemia/reperfusion-induced blood-brain barrier (BBB) damage. Since melatonin could regulate the expression of α7nAchR and melatonin's neuroprotective effect against ischemic injury is mediated via α7nAChR modulation, here, we aim to test the hypothesis that melatonin reduces ischemia and reperfusion (I/R)-induced BBB damage through modulation of α7nACh receptor (α7nAChR). Mice were subjected to 1.5 h ischemia and 24 h reperfusion and at the onset of reperfusion, mice received intraperitoneal administration (i.p.) of either drug or saline. Mice were randomly assigned into five groups: Saline; α7nAChR agonist PNU282987; Melatonin; Melatonin+Methyllycaconitine (MLA, α7nAChR antagonist), and MLA group. BBB permeability was assessed by detecting the extravasation of Evan's blue and IgG. Our results showed that I/R significantly increased BBB permeability accompanied by occludin degradation, microglia activation, and high mobility group box 1 (HMGB1) release from the neuron. In addition, I/R significantly induced neuronal loss accompanied by the decrease of CREB-regulated transcriptional coactivator 1 (CRTC1) and p-CREB expression. Melatonin treatment significantly inhibited the above changes through modulating α7nAChR. Taken together, these results demonstrate that melatonin provides a protective effect on ischemia/reperfusion-induced BBB damage, at least in part, depending on the modulation of α7nAChR.

Role of alarmins in poststroke inflammation and neuronal repair

Severe loss of cerebral blood flow causes hypoxia and glucose deprivation in the brain tissue, resulting in necrotic cell death in the ischemic brain. Several endogenous molecules, called alarmins or damage-associated molecular patterns (DAMPs), are extracellularly released from the dead cells to activate pattern recognition receptors (PRRs) in immune cells that infiltrate into ischemic brain tissue following the disruption of the blood-brain barrier (BBB) after stroke onset. The activated immune cells produce various inflammatory cytokines and chemokines, triggering sterile cerebral inflammation in the ischemic brain that causes further neuronal cell death. Poststroke inflammation is resolved within several days after stroke onset, and neurological functions are restored to some extent as neural repair occurs around peri-infarct neurons. Clearance of DAMPs from the injured brain is necessary for the resolution of poststroke inflammation. Neurons and glial cells also express PRRs and receive DAMP signaling. Although the role of PRRs in neural cells in the ischemic brain has not yet been clarified, the signaling pathway is likely to be contribute to stroke pathology and neural repair after ischemic stroke. This review describes the molecular dynamics, signaling pathways, and functions of DAMPs in poststroke inflammation and its resolution.

Regulatory mechanisms of tetramethylpyrazine on central nervous system diseases: A review

Central nervous system (CNS) diseases can lead to motor, sensory, speech, cognitive dysfunction, and sometimes even death. These diseases are recognized to cause a substantial socio-economic impact on a global scale. Tetramethylpyrazine (TMP) is one of the main active ingredients extracted from the Chinese herbal medicine Ligusticum striatum DC. (Chuan Xiong). Many in vivo and in vitro studies have demonstrated that TMP has a certain role in the treatment of CNS diseases through inhibiting calcium ion overload and glutamate excitotoxicity, anti-oxidative/nitrification stress, mitigating inflammatory response, anti-apoptosis, protecting the integrity of the blood-brain barrier (BBB) and facilitating synaptic plasticity. In this review, we summarize the roles and mechanisms of action of TMP on ischemic cerebrovascular disease, spinal cord injury, Parkinson’s disease, Alzheimer’s disease, cognitive impairments, migraine, and depression. Our review will provide new insights into the clinical applications of TMP and the development of novel therapeutics.

CCCTC-binding factor-mediated microRNA-340-5p suppression aggravates myocardial injury in rats with severe acute pancreatitis through activation of the HMGB1/TLR4 axis

BACKGROUND

Severe acute pancreatitis (SAP) is a life-threatening disorder associated with multisystem organ failure. This study aimed to investigate the function of high mobility group box 1 (HMGB1) in SAP-induced myocardial injury.

METHODS

A rat model with SAP was induced. The pathological changes in rat pancreatic and cardiac tissues were examined by HE staining. Cardiomyocyte apoptosis in rat cardiac tissues, and the serum levels of myocardial injury markers and pro-inflammatory cytokines were examined. Rat primary cardiomyocytes were treated with H2O2 for in vitro experiments. The regulatory molecules of HMGB1 were predicted by bioinformatics analysis. Altered expression of HMGB1, microRNA (miR)-340-5p and CCCTC-binding factor (CTCF) was introduced in rats or cells to investigate their roles in myocardial injury.

RESULTS

CTCF and HMGB1 were highly expressed but miR-340-5p was poorly expressed in cardiac tissues of rats with SAP. HMGB1 silencing reduced toll-like receptor 4 (TLR4) expression to promote proliferation and reduce apoptosis of H2O2-treated cardiomyocytes. miR-340-5p targeted HMGB1 mRNA, while CTCF suppressed miR-340-5p transcription. CTCF upregulation or miR-340-5p downregulation blocked the effects of HMGB1 silencing on cardiomyocytes. In vivo, CTCF silencing alleviated injury in rat pancreatic and cardiac tissues and reduced the expression of creatine kinase-MB (CK-MB), lactic dehydrogenase, interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in rat serum. But further overexpression of HMGB1 or inhibition of miR-340-5p aggravated the symptoms in rats.

CONCLUSION

This study demonstrated that CTCF reduces transcription of miR-340-5p to promote HMGB1 expression, which activates TLR4 expression and promotes myocardial injury in rats with SAP.

HMGB1 signaling pathway in diabetes-related dementia: Blood-brain barrier breakdown, brain insulin resistance, and Aβ accumulation

Diabetes contributes to the onset of various diseases, including cancer and cardiovascular and neurodegenerative diseases. Recent studies have highlighted the similarities and relationship between diabetes and dementia as an important issue for treating diabetes-related cognitive deficits. Diabetes-related dementia exhibits several features, including blood-brain barrier disruption, brain insulin resistance, and Aβ over-accumulation. High-mobility group box1 (HMGB1) is a protein known to regulate gene transcription and cellular mechanisms by binding to DNA or chromatin via receptor for advanced glycation end-products (RAGE) and toll-like receptor 4 (TLR4). Recent studies have demonstrated that the interplay between HMGB1, RAGE, and TLR4 can impact both neuropathology and diabetic alterations. Herein, we review the recent research regarding the roles of HMGB1-RAGE-TLR4 axis in diabetes-related dementia from several perspectives and emphasize the importance of the influence of HMGB1 in diabetes-related dementia.

Neutrophil extracellular traps regulate ischemic stroke brain injury

Ischemic stroke prompts a strong inflammatory response, which is associated with exacerbated outcomes. In this study, we investigated mechanistic regulators of neutrophil extracellular trap (NET) formation in stroke and whether they contribute to stroke outcomes. NET-forming neutrophils were found throughout brain tissue of ischemic stroke patients, and elevated plasma NET biomarkers correlated with worse stroke outcomes. Additionally, we observed increased plasma and platelet surface-expressed high-mobility group box 1 (HMGB1) in stroke patients. Mechanistically, platelets were identified as the critical source of HMGB1 that caused NETs in the acute phase of stroke. Depletion of platelets or platelet-specific knockout of HMGB1 significantly reduced plasma HMGB1 and NET levels after stroke, and greatly improved stroke outcomes. We subsequently investigated the therapeutic potential of neonatal NET-inhibitory factor (nNIF) in stroke. Mice treated with nNIF had smaller brain infarcts, improved long-term neurological and motor function, and enhanced survival after stroke. nNIF specifically blocked NET formation without affecting neutrophil recruitment after stroke. Importantly, nNIF also improved stroke outcomes in diabetic and aged mice and was still effective when given 1 hour after stroke onset. These results support a pathological role for NETs in ischemic stroke and warrant further investigation of nNIF for stroke therapy.

The Cellular Senescence Factor Extracellular HMGB1 Directly Inhibits Oligodendrocyte Progenitor Cell Differentiation and Impairs CNS Remyelination

HMGB1 is a highly conserved, ubiquitous protein in eukaryotic cells. HMGB1 is normally localized to the nucleus, where it acts as a chromatin associated non-histone binding protein. In contrast, extracellular HMGB1 is an alarmin released by stressed cells to act as a danger associated molecular pattern (DAMP). We have recently determined that progenitor cells from multiple sclerosis patients exhibit a cellular senescent phenotype and release extracellular HMGB1 which directly impaired the maturation of oligodendrocyte progenitor cells (OPCs) to myelinating oligodendrocytes (OLs). Herein, we report that administration of recombinant HMGB1 into the spinal cord at the time of lysolecithin administration resulted in arrest of OPC differentiation in vivo, and a profound impairment of remyelination. To define the receptor by which extracellular HMGB1 mediates its inhibitory influence on OPCs to impair OL differentiation, we tested selective inhibitors against the four primary receptors known to mediate the effects of HMGB1, the toll-like receptors (TLRs)-2, -4, -9 or the receptor for advanced glycation end-products (RAGE). We found that inhibition of neither TLR9 nor RAGE increased OL differentiation in the presence of HMGB1, while inhibition of TLR4 resulted in partial restoration of OL differentiation and inhibiting TLR2 fully restored differentiation of OLs in the presence of HMGB1. Analysis of transcriptomic data (RNAseq) from OPCs identified an overrepresentation of NFκB regulated genes in OPCs when in the presence of HMGB1. We found that application of HMGB1 to OPCs in culture resulted in a rapid and concentration dependent shift in NFκB nuclear translocation which was also attenuated with coincident TLR2 inhibition. These data provide new information on how extracellular HMGB1 directly affects the differentiation potential of OPCs. Recent and past evidence for elevated HMGB1 released from senescent progenitor cells within demyelinated lesions in the MS brain suggests that a greater understanding of how this molecule acts on OPCs may unfetter the endogenous remyelination potential in MS.

Role of DAMPs and of Leukocytes Infiltration in Ischemic Stroke: Insights from Animal Models and Translation to the Human Disease

Stroke is a leading cause of death and disability worldwide. Several mechanisms are involved in the pathogenesis of ischemic stroke (IS). The contributory role of the inflammatory and immunity processes was demonstrated both in vitro and in animal models, and was confirmed in humans. IS evokes an immediate inflammatory response that involves complex cellular and molecular mechanisms. All components of the innate and adaptive immunity systems are involved in several steps of the ischemic cascade. In the early phase, inflammatory and immune mechanisms contribute to the brain tissue damage, whereas, in the late phase, they participate to the tissue repair processes. In particular, damage-associated molecular patterns (DAMPs) appear critical for the promotion of altered blood brain barrier permeability, leukocytes infiltration, tissue edema and brain injury. Conversely, the activation of regulatory T lymphocytes (Tregs) plays protective effects. The identification of specific cellular/molecular elements belonging to the inflammatory and immune responses, contributing to the brain ischemic injury and tissue remodeling, offers the advantage to design adequate therapeutic strategies. In this article, we will present an overview of the knowledge on inflammatory and immunity processes in IS, with a particular focus on the role of DAMPs and leukocytes infiltration. We will discuss evidence obtained in preclinical models of IS and in humans. The main molecular mechanisms useful for the development of novel therapeutic approaches will be highlighted. The translation of experimental findings to the human disease is still a difficult step to pursue. Further investigations are required to fill up the existing gaps.

The Intriguing Role of TLR Accessory Molecules in Cardiovascular Health and Disease

Activation of Toll like receptors (TLR) plays an important role in cardiovascular disease development, progression and outcomes. Complex TLR mediated signaling affects vascular and cardiac function including tissue remodeling and repair. Being central components of both innate and adaptive arms of the immune system, TLRs interact as pattern recognition receptors with a series of exogenous ligands and endogenous molecules or so-called danger associated molecular patterns (DAMPs) that are released upon tissue injury and cellular stress. Besides immune cells, a number of structural cells within the cardiovascular system, including endothelial cells, smooth muscle cells, fibroblasts and cardiac myocytes express TLRs and are able to release or sense DAMPs. Local activation of TLR-mediated signaling cascade induces cardiovascular tissue repair but in a presence of constant stimuli can overshoot and cause chronic inflammation and tissue damage. TLR accessory molecules are essential in guiding and dampening these responses toward an adequate reaction. Furthermore, accessory molecules assure specific and exclusive TLR-mediated signal transduction for distinct cells and pathways involved in the pathogenesis of cardiovascular diseases. Although much has been learned about TLRs activation in cardiovascular remodeling, the exact role of TLR accessory molecules is not entirely understood. Deeper understanding of the role of TLR accessory molecules in cardiovascular system may open therapeutic avenues aiming at manipulation of inflammatory response in cardiovascular disease. The present review outlines accessory molecules for membrane TLRs that are involved in cardiovascular disease progression. We first summarize the up-to-date knowledge on TLR signaling focusing on membrane TLRs and their ligands that play a key role in cardiovascular system. We then survey the current evidence of the contribution of TLRs accessory molecules in vascular and cardiac remodeling including myocardial infarction, heart failure, stroke, atherosclerosis, vein graft disease and arterio-venous fistula failure.

Cooling and Sterile Inflammation in an Oxygen-Glucose-Deprivation/Reperfusion Injury Model in BV-2 Microglia

Objective

Cold-inducible RNA-binding protein (CIRBP) has been shown to be involved not only in cooling-induced cellular protection but also as a mediator of sterile inflammation, a critical mechanism of the innate immune response in ischemia/reperfusion (I/R) injury. The role of microglia and its activation in cerebral I/R injury warrants further investigation as both detrimental and regenerative properties have been described. Therefore, we investigated the effects of cooling, specifically viability, activation, and release of damage associated molecular patterns (DAMPs) on oxygen glucose deprivation/reperfusion- (OGD/R-) induced injury in murine BV-2 microglial cells.

Methods

Murine BV-2 microglial cells were exposed to 2 to 6 h OGD (0.2% O₂ in glucose- and serum-free medium) followed by up to 19 h of reperfusion, simulated by restoration of oxygen (21% O₂) and nutrients. Cells were maintained at either normothermia (37°C) or cooled to 33.5°C, 1 h after experimental start. Cultured supernatants were harvested after exposure to OGD for analysis of DAMP secretions, including high-mobility group box 1 (HMGB1), heat shock protein 70 (HSP70), and CIRBP, and cytotoxicity was assessed by lactate dehydrogenase releases after exposure to OGD and reperfusion. Intracellular cold-shock proteins CIRBP and RNA-binding motif 3 (RBM3) as well as caspases 9, 8, and 3 were also analyzed via Western blot analysis. Furthermore, inducible nitric oxide synthase (iNOS), ionized calcium-binding adaptor molecule 1 (Iba1), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), interleukin-1α (IL-1α), monocyte chemotactic protein 1 (MCP-1), transforming growth factor β (TGFβ), CIRBP, and RBM3 gene expressions were assessed via reverse transcription polymerase chain reaction, and TNF-α, IL-6, and IL-1β releases into the cultured supernatants were assessed via enzyme-linked immunosorbent assays (ELISA).

Results

Prolonged exposure to OGD resulted in increased BV-2 necrotic cell death, which was attenuated by cooling. Cooling also significantly induced cold-shock proteins CIRBP and RBM3 gene expressions, with CIRBP expression more rapidly regulated than RBM3 and translatable to significantly increased protein expression. DAMPs including HMGB-1, HSP70, and CIRBP could be detected in cultured supernatants after 6 h of OGD with CIRBP release being significantly attenuated by cooling. Exposure to OGD suppressed cytokine gene expressions of IL-1β, TNF-α, MCP-1, and TGFβ independently of temperature management, whereas cooling led to a significant increase in IL-1α gene expression after 6 h of OGD. In the reperfusion phase, TNF-α and MCP-1 gene expressions were increased, and cooling was associated with significantly lower TGFβ gene expression. Interestingly, cooled Normoxia groups had significant upregulations of microglial activation marker, Iba1, IL-1β, and TNF-α gene expressions.

Conclusion

BV-2 microglial cells undergo necrotic cell death resulting in DAMP release due to OGD/R-induced injury. Cooling conveyed neuroprotection in OGD/R-injury as observable in increased cell viability as well as induced gene expressions of cold shock proteins. As cooling alone resulted in both upregulation of microglial activation, expression of proinflammatory cytokines, and cold shock protein transcript and protein expression, temperature management might have ambiguous effects in sterile inflammation. However, cooling resulted in a significant decrease of extracellular CIRBP, which has recently been characterized as a novel DAMP and a potent initiator and mediator of inflammation.

Danger-associated molecular patterns are locally released during occlusion in hyper-acute stroke

Objective

Immune responses are an integral part of the complex reactions to acute cerebral ischemia and contribute to infarct expansion and tissue remodeling. Among damage-associated molecular patterns (DAMPs) the high-mobility group box 1 protein (HMGB1) and calprotectin (S100A8/A9) are released from dying cells and activate the innate immune system.

Methods

To assess DAMPs concentrations and related leukocytic infiltration directly and locally in human stroke patients we performed microcatheter sampling from within the core of the occluded vascular compartment before recanalization by mechanical thrombectomy. These samples from the core of a sealed cerebral-ischemic arterial compartment were compared with systemic control samples from the internal carotid artery obtained after recanalization.

Results

We found increased plasma levels of total free HMGB1 (+33%) and increased S100A8/A9 (+8%) locally within the ischemic cerebral compartment vs. systemic levels. Local concentrations of HMGB1 were associated with more extensive structural brain infarction on admission. In addition, local ischemic HMGB1 and S100A8/A9 concentrations were associated with the numbers of leukocytes that infiltrate the occluded compartment by collateral pathways.

Conclusion

This is the first direct human observation of a local increase in DAMPs concentrations in a uniquely sealed vascular compartment of the ischemic cerebral circulation. These data provide an important pathophysiological link between ischemia-induced cell death and stroke-related inflammation.

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HMGB1 is locally released during occlusion in human hyper-acute stroke

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S100A8/A9 is locally released during occlusion in human hyper-acute stroke

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HMGB1 concentrations are associated with structural brain infarction on admission

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DAMPs concentrations are related to inflammatory responses

CSF high-mobility group box 1 is associated with drug-resistance and symptomatic etiology in adult patients with epilepsy

PURPOSE

Extracellular high-mobility group box 1 (HMGB1) is considered a proinflammatory mediator and is involved in various neurological disorders. This study aims to determine the expression profiles of HMGB1 in cerebrospinal fluid (CSF) and paired serum, and to explore whether there is a relationship between CSF HMGB1 concentrations with seizure parameters in adult patients with epilepsy.

METHODS

CSF and paired serum HMGB1 concentrations were measured in patients with drug-refractory epilepsy (DRE, n = 27), newly diagnosed epilepsy (NDE, n = 56), and other non-inflammatory neurological disorders (ONNDs, n = 22). The correlations in HMGB1 levels between CSF and blood were performed. The associations between HMGB1 levels and seizure parameters were analyzed.

RESULTS

Mean (± SD) CSF HMGB1 concentrations were 5.08 ± 3.06, 3.03 ± 2.25, 0.83 ± 0.77 ng/mL in patients with DRE, NDE, and ONNDs, respectively. Corresponding mean (± SD) serum concentrations were 4.53 ± 2.81, 2.32 ± 1.54, 1.56 ± 0.84 ng/mL. The CSF HMGB1 concentrations were significantly higher in the DRE and NDE groups compared with the ONNDs group (p < 0.001). There were no correlations in HMGB1 levels between CSF and serum in the DRE, NDE, and ONNDs groups. Furthermore, patients with symptomatic etiology showed significantly high levels of CSF HMGB1. Patients without remission expressed elevated levels of CSF HMGB1 at one-year follow-up. Additionally, the CSF HMGB1 levels were positively associated with seizure frequency.

CONCLUSION

Our study shows that HMGB1 may be a critical player in seizure mechanisms and CSF HMGB1 might be predictive in determining epilepsy etiology and prognosis.

Relevance of Circulating Nucleosomes, HMGB1 and sRAGE for Prostate Cancer Diagnosis

BACKGROUND/AIM

Evasion from cell death occurs in prostate cancer (PCa). We verified whether serum levels of cell death markers can have diagnostic value in PCa.

PATIENTS AND METHODS

A total of 233 men scheduled for prostate biopsy [prostate specific antigen (PSA) level: 2-10 ng/ml] were enrolled. Serum nucleosomes, nucleosomes containing the H3 histone (H3), high mobility group box 1 (HMGB1), and soluble receptor for advanced glycation end products (sRAGE) were analyzed by enzyme immunoassays.

RESULTS

There were no differences (p>0.05) in nucleosomes, H3, and sRAGE levels between patients with and without PCa or clinically significant PCa (csPCa). HMGB1 had lower levels in PCa patients (p=0.023) and was a predictor of PCa (p=0.047), but not of csPCa (p=0.180).

CONCLUSION

In patients with critical PSA levels between 2-10 ng/ml, HMGB1 had some diagnostic value for overall PCa detection, but it was not predictive of csPCa. Nucleosomes, H3 and sRAGE did not discriminate between PCa or csPCa and controls.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

Dynamic roles of neutrophils in post-stroke neuroinflammation

Clinical trials involving the blockage of peripheral inflammatory leukocyte recruitment into the brain have puzzlingly led to either no significant improvement in stroke outcome, or even worsened outcomes and increased mortality, prompting a re-evaluation of our understanding into the neuroinflammatory processes after stroke. Whilst traditionally understood as simple effectors of the innate immune system, emerging research in vascular disease biology has redefined the neutrophil as a specialized and highly specific cell type with dynamic functional capacity. Indeed, emerging experimental evidence indicates that neutrophils display diverse roles in the acute stages of ischemic stroke with the ability to elicit both pro-inflammatory and anti-inflammatory effects. Currently, there is some uncertainty as to whether neutrophil diversity is beneficial or harmful in stroke as their interactions with the resident cells of the brain, such as microglia and neurons, would potentially elicit heterogeneous outcomes. Current treatments for patients with stroke aim to remove the vascular blockage and to restore blood flow, but there are currently no drug treatments for managing the loss of functional brain tissue nor restoration of microglial and neuronal damage. If these hypothesized wound-healing functions of neutrophils can be validated in a stroke setting, promoting the recruitment of this type of neutrophils into the injured brain tissue may form a promising therapeutic target for the majority of stroke patients currently without treatment. In this review, we will provide an update on recent research that has explored neutrophil heterogeneity in the neuroinflammatory cascade after ischemic stroke.

High-mobility group box 1 serves as an inflammation driver of cardiovascular disease

Cardiovascular disease (CVD) is the most deadly disease, which can cause sudden death, in which inflammation is a key factor in its occurrence and development. High-mobility group box 1 (HMGB1) is a novel nuclear DNA-binding protein that activates innate immunity to induce inflammation in CVD. HMGB1 exists in the cytoplasm and nucleus of different cell types, including those in the heart. By binding to its receptors, HMGB1 triggers a variety of signaling cascades, leading to inflammation and CVD. To help develop HMGB1-targeted therapies, here we discuss HMGB1 and its biological functions, receptors, signaling pathways, and pathophysiology related to inflammation and CVD, including cardiac remodeling, cardiac hypertrophy, myocardial infarction, heart failure, pulmonary hypertension, atherosclerosis, and cardiomyopathy.

Uric acid inhibits HMGB1-TLR4-NF-κB signaling to alleviate oxygen-glucose deprivation/reoxygenation injury of microglia

Mounting evidence has implicated inflammation in ischemia-reperfusion injury following acute ischemic stroke (AIS). Microglia remain the primary initiator and participant of brain inflammation. Emerging evidence has indicated that uric acid has promise for the treatment of AIS, but its explicit mechanisms remain elusive. Here, we observed that uric acid reduced the severity of cerebral infarction and attenuated the activation of microglia in the cerebral cortex in a mouse middle cerebral-artery occlusion/reperfusion model. Thus, we speculated that uric acid may play a role by directly interfering with the inflammatory response of microglia. First, we investigated whether the HMGB1-TLR4-NF-κB signaling plays a role in oxygen glucose deprivation and reperfusion (OGD/R) injury of BV2 cells. Inhibition of the signaling significantly reduced the release of the proinflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β (IL1β), and IL6 caused by OGD/R in BV2 cells. Second, uric acid weakened the decreased cell viability and lactate dehydrogenase release induced by OGD/R in BV2 cells. Finally, uric acid reduced the release of the proinflammatory cytokines TNF-α, IL1β, and IL6 caused by OGD/R in BV2 cells by dampening HMGB1-TLR4-NF-κB signaling, which was reversed by probenecid treatment, an inhibitor of the uric acid channel. Hence, uric acid halted the release of inflammatory factors and the decreased cell viability induced by ODG/R via inhibiting the microglia HMGB1-TLR4-NF-κB signaling, thereby alleviating the damage to microglia. This may be part of the molecular mechanisms by which uric acid protects mice against the brain damage of middle cerebral-artery occlusion/reperfusion.

The Trinity of cGAS, TLR9, and ALRs Guardians of the Cellular Galaxy Against Host-Derived Self-DNA

The immune system has evolved to protect the host from the pathogens and allergens surrounding their environment. The immune system develops in such a way to recognize self and non-self and develops self-tolerance against self-proteins, nucleic acids, and other larger molecules. However, the broken immunological self-tolerance leads to the development of autoimmune or autoinflammatory diseases. Pattern-recognition receptors (PRRs) are expressed by immunological cells on their cell membrane and in the cytosol. Different Toll-like receptors (TLRs), Nod-like receptors (NLRs) and absent in melanoma-2 (AIM-2)-like receptors (ALRs) forming inflammasomes in the cytosol, RIG (retinoic acid-inducible gene)-1-like receptors (RLRs), and C-type lectin receptors (CLRs) are some of the PRRs. The DNA-sensing receptor cyclic GMP–AMP synthase (cGAS) is another PRR present in the cytosol and the nucleus. The present review describes the role of ALRs (AIM2), TLR9, and cGAS in recognizing the host cell DNA as a potent damage/danger-associated molecular pattern (DAMP), which moves out to the cytosol from its housing organelles (nucleus and mitochondria). The introduction opens with the concept that the immune system has evolved to recognize pathogens, the idea of horror autotoxicus, and its failure due to the emergence of autoimmune diseases (ADs), and the discovery of PRRs revolutionizing immunology. The second section describes the cGAS-STING signaling pathway mediated cytosolic self-DNA recognition, its evolution, characteristics of self-DNAs activating it, and its role in different inflammatory conditions. The third section describes the role of TLR9 in recognizing self-DNA in the endolysosomes during infections depending on the self-DNA characteristics and various inflammatory diseases. The fourth section discusses about AIM2 (an ALR), which also binds cytosolic self-DNA (with 80–300 base pairs or bp) that inhibits cGAS-STING-dependent type 1 IFN generation but induces inflammation and pyroptosis during different inflammatory conditions. Hence, this trinity of PRRs has evolved to recognize self-DNA as a potential DAMP and comes into action to guard the cellular galaxy. However, their dysregulation proves dangerous to the host and leads to several inflammatory conditions, including sterile-inflammatory conditions autoinflammatory and ADs.

The Roles of High Mobility Group Box 1 in Cerebral Ischemic Injury

High mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that plays an important role in stabilizing nucleosomes and DNA repair. HMGB1 can be passively released from necrotic neurons or actively secreted by microglia, macrophages/monocytes, and neutrophils. Cerebral ischemia is a major cause of mortality and disability worldwide, and its outcome depends on the number of neurons dying due to hypoxia in the ischemic area. HMGB1 contributes to the pathogenesis of cerebral ischemia via mediating neuroinflammatory responses to cerebral ischemic injury. Extracellular HMGB1 regulates many neuroinflammatory events by interacting with its different cell surface receptors, such as receptors for advanced glycation end products, toll-like receptor (TLR)-2, and TLR-4. Additionally, HMGB1 can be redox-modified, thus exerting specific cellular functions in the ischemic brain and has different roles in the acute and late stages of cerebral ischemic injury. However, the role of HMGB1 in cerebral ischemia is complex and remains unclear. Herein, we summarize and review the research on HMGB1 in cerebral ischemia, focusing especially on the role of HMGB1 in hypoxic ischemia in the immature brain and in white matter ischemic injury. We also outline the possible mechanisms of HMGB1 in cerebral ischemia and the main strategies to inhibit HMGB1 pertaining to its potential as a novel critical molecular target in cerebral ischemic injury.

Damage-Associated Molecular Patterns in Myocardial Infarction and Heart Transplantation: The Road to Translational Success

In the setting of myocardial infarction (MI), ischemia reperfusion injury (IRI) occurs due to occlusion (ischemia) and subsequent re-establishment of blood flow (reperfusion) of a coronary artery. A similar phenomenon is observed in heart transplantation (HTx) when, after cold storage, the donor heart is connected to the recipient's circulation. Although reperfusion is essential for the survival of cardiomyocytes, it paradoxically leads to additional myocardial damage in experimental MI and HTx models. Damage (or danger)-associated molecular patterns (DAMPs) are endogenous molecules released after cellular damage or stress such as myocardial IRI. DAMPs activate pattern recognition receptors (PRRs), and set in motion a complex signaling cascade resulting in the release of cytokines and a profound inflammatory reaction. This inflammatory response is thought to function as a double-edged sword. Although it enables removal of cell debris and promotes wound healing, DAMP mediated signalling can also exacerbate the inflammatory state in a disproportional matter, thereby leading to additional tissue damage. Upon MI, this leads to expansion of the infarcted area and deterioration of cardiac function in preclinical models. Eventually this culminates in adverse myocardial remodeling; a process that leads to increased myocardial fibrosis, gradual further loss of cardiomyocytes, left ventricular dilation and heart failure. Upon HTx, DAMPs aggravate ischemic damage, which results in more pronounced reperfusion injury that impacts cardiac function and increases the occurrence of primary graft dysfunction and graft rejection via cytokine release, cardiac edema, enhanced myocardial/endothelial damage and allograft fibrosis. Therapies targeting DAMPs or PRRs have predominantly been investigated in experimental models and are potentially cardioprotective. To date, however, none of these interventions have reached the clinical arena. In this review we summarize the current evidence of involvement of DAMPs and PRRs in the inflammatory response after MI and HTx. Furthermore, we will discuss various current therapeutic approaches targeting this complex interplay and provide possible reasons why clinical translation still fails.

Immunomodulatory properties of high mobility group box 1 and its potential role in brain injury: Review article

BACKGROUND

Human mobility group box 1 (HMGB1) is a novel biomolecular agent which has a major part in inflammation process. HMGB1 has been known to be a strong pro-inflammatory factor as damage associated molecular pattern (DAMP) which its interaction with its receptor, the receptor of advanced glycation end products (RAGE), will cause positive amplification of inflammation signalling pathway.Brain injury is one of the major contributors for disability and death which neuroinflammation has a major role in its pathogenesis and influencing its outcome. In neuroinflammation, it has been described that HMGB1 may have a pivotal role in the process.

OBJECTIVE

The objective of this article is to review the role HMGB1 in brain injury and its immunomodulatory properties.

METHODS

A comprehensive search of literature was conducted in PubMed (NIH), Scopus, EMBASE, and Google Scholar database using keyword combinations of the medical subject headings (MeSH) of "HMGB1" and "Brain Injury" and relevant reference lists were also manually searched. All relevant articles of any study design published from year 1990 till June 2020, were included and narratively discussed in this review.

RESULTS

Twenty-four articles were shortlisted and reviewed in this article. Through these articles, we synthesis information on the function and metabolism of HMGB1, immunomodulatory effect of HMGB1, clinical findings and other potential treatment involving HMGB1, and role of HMGB1 protein in brain injury.

CONCLUSION

HMGB1 has a strong pro-inflammation property which predominantly acts through RAGE pathways.Review registration number reviewregistry966 in www.researchregistry.com.

Role of HMGB1 in the Interplay between NETosis and Thrombosis in Ischemic Stroke: A Review

Neutrophil extracellular traps (NETs) comprise decondensed chromatin, histones and neutrophil granular proteins and are involved in the response to infectious as well as non-infectious diseases. The prothrombotic activity of NETs has been reported in various thrombus-related diseases; this activity can be attributed to the fact that the NETs serve as a scaffold for cells and numerous coagulation factors and stimulate fibrin deposition. A crosstalk between NETs and thrombosis has been indicated to play a role in numerous thrombosis-related conditions including stroke. In cerebral ischemia, neutrophils are the first group of cells to infiltrate the damaged brain tissue, where they produce NETs in the brain parenchyma and within blood vessels, thereby aggravating inflammation. Increasing evidences suggest the connection between NETosis and thrombosis as a possible cause of “tPA resistance”, a problem encountered during the treatment of stroke patients. Several damage-associated molecular pattern molecules have been proven to induce NETosis and thrombosis, with high mobility group box 1 (HMGB1) playing a critical role. This review discusses NETosis and thrombosis and their crosstalk in various thrombosis-related diseases, focusing on the role of HMGB1 as a mediator in stroke. We also addresses the function of peptidylarginine deiminase 4 with respect to the interplay with HMGB1 in NET-induced thrombosis.

Glycyrrhizic Acid Attenuates Balloon-Induced Vascular Injury Through Inactivation of RAGE Signaling Pathways

Percutaneous coronary intervention is a well-established technique used to treat coronary artery disease, but the risk of coronary artery in-stent restenosis following percutaneous coronary intervention is still high. Previous studies revealed that high mobility group protein B1 (HMGB1) plays a critical role in neointima formation. In this study, we aimed to investigate the role of glycyrrhizic acid (GA), an HMGB1 inhibitor, in the process of neointima formation and the potential mechanisms. We investigated the role of GA in neointima formation through an iliac artery balloon injury model in rabbits. Proliferation, migration, and phenotype transformation of human vascular smooth muscle cells (VSMCs) were observed. Besides, inflammation and receptor for advanced glycosylation end products (RAGE) signaling pathways were studied. The results indicate that GA attenuated neointima formation and downregulated HMGB1 expression in injured artery in rabbits. HMGB1 promoted proliferation, migration, and phenotype transformation through the activation of RAGE signaling pathways in VSMCs, and blockade of HMGB1 by GA (1, 10, and 100 μM) could attenuate those processes and reduce proliferation of human VSMCs. In conclusion, the HMGB1 inhibitor GA might be useful to treat proliferative vascular diseases by downregulating RAGE signaling pathways. Our results indicate a new and promising therapeutic agent for restenosis.

Immune Alterations Following Neurological Disorders: A Comparison of Stroke and Seizures

Background: Granulocytes and monocytes are the first cells to invade the brain post stroke and are also being discussed as important cells in early neuroinflammation after seizures. We aimed at understanding disease specific and common pathways of brain-immune-endocrine-interactions and compared immune alterations induced by stroke and seizures. Therefore, we compared granulocytic and monocytic subtypes between diseases and investigated inflammatory mediators. We additionally investigated if seizure type determines immunologic alterations.

Material and Methods: We included 31 patients with acute seizures, 17 with acute stroke and two control cohorts. Immune cells were characterized by flow cytometry from blood samples obtained on admission to the hospital and the following morning. (i) Monocytes subpopulations were defined as classical (CD14⁺⁺CD16⁻), (ii) intermediate (CD14⁺⁺CD16⁺), and (iii) non-classical monocytes (CD14^dimCD16⁺), while granulocyte subsets were characterized as (i) “classical granulocytes” (CD16⁺⁺CD62L⁺), (ii) pro-inflammatory (CD16^dimCD62L⁺), and (iii) anti-inflammatory granulocytes (CD16⁺⁺CD62L⁻). Stroke patient's blood was additionally drawn on days 3 and 5. Cerebrospinal fluid mitochondrial DNA was quantified by real-time PCR. Plasma High-Mobility-Group-Protein-B1, metanephrine, and normetanephrine were measured by ELISA.

Results: HLA-DR expression on monocytes and their subpopulations (classical, intermediate, and non-classical monocytes) was reduced after stroke or seizures. Expression of CD32 was increased on monocytes and subtypes in epilepsy patients, partly similar to stroke. CD32 and CD11b regulation on granulocytes and subpopulations (classical, anti-inflammatory, pro-inflammatory granulocytes) was more pronounced after stroke compared to seizures. On admission, normetanephrine was upregulated in seizures, arguing for the sympathetic nervous system as inducer of immune alterations similar to stroke. Compared to partial seizures, immunologic changes were more pronounced in generalized tonic-clonic seizures.

Conclusion: Seizures lead to immune alterations within the immediate postictal period similar but not identical to stroke. The type of seizures determines the extent of immune alterations.

Innate immunity as a target for acute cardioprotection

Acute obstruction of a coronary artery causes myocardial ischaemia and if prolonged, may result in an ST-segment elevation myocardial infarction (STEMI). First-line treatment involves rapid reperfusion. However, a highly dynamic and co-ordinated inflammatory response is rapidly mounted to repair and remove the injured cells which, paradoxically, can further exacerbate myocardial injury. Furthermore, although cardiac remodelling may initially preserve some function to the heart, it can lead over time to adverse remodelling and eventually heart failure. Since the size of the infarct corresponds to the subsequent risk of developing heart failure, it is important to find ways to limit initial infarct development. In this review, we focus on the role of the innate immune system in the acute response to ischaemia-reperfusion (IR) and specifically its contribution to cell death and myocardial infarction. Numerous danger-associated molecular patterns are released from dying cells in the myocardium, which can stimulate pattern recognition receptors including toll like receptors and NOD-like receptors (NLRs) in resident cardiac and immune cells. Activation of the NLRP3 inflammasome, caspase 1, and pyroptosis may ensue, particularly when the myocardium has been previously aggravated by the presence of comorbidities. Evidence will be discussed that suggests agents targeting innate immunity may be a promising means of protecting the hearts of STEMI patients against acute IR injury. However, the dosing and timing of such agents should be carefully determined because innate immunity pathways may also be involved in cardioprotection. This article is part of a Cardiovascular Research Spotlight Issue entitled 'Cardioprotection Beyond the Cardiomyocyte', and emerged as part of the discussions of the European Union (EU)-CARDIOPROTECTION Cooperation in Science and Technology (COST) Action, CA16225.

The role of Toll-like receptor signaling pathways in cerebrovascular disorders: the impact of spreading depolarization

Cerebral vascular diseases (CVDs) are a group of disorders that affect the blood supply to the brain and lead to the reduction of oxygen and glucose supply to the neurons and the supporting cells. Spreading depolarization (SD), a propagating wave of neuroglial depolarization, occurs in different CVDs. A growing amount of evidence suggests that the inflammatory responses following hypoxic-ischemic insults and after SD plays a double-edged role in brain tissue injury and clinical outcome; a beneficial effect in the acute phase and a destructive role in the late phase. Toll-like receptors (TLRs) play a crucial role in the activation of inflammatory cascades and subsequent neuroprotective or harmful effects after CVDs and SD. Here, we review current data regarding the pathophysiological role of TLR signaling pathways in different CVDs and discuss the role of SD in the potentiation of the inflammatory cascade in CVDs through the modulation of TLRs.

Neuronal HMGB1 in nucleus accumbens regulates cocaine reward memory

Cocaine is a common abused drug that can induce abnormal synaptic and immune responses in the central nervous system (CNS). High mobility group box 1 (HMGB1) is one kind of inflammatory molecules that is expressed both on neurons and immune cells. Previous studies of HMGB1 in the CNS have largely focused on immune function, and the role of HMGB1 in neurons and cocaine addiction remains unknown. Here, we show that cocaine exposure induced the translocation and release of HMGB1 in the nucleus accumbens (NAc) neurons. Gain and loss of HMGB1 in the NAc bidirectionally regulate cocaine-induced conditioned place preference. From the nucleus to the cytosol, HMGB1 binds to glutamate receptor subunits (GluA2/GluN2B) on the membrane, which regulates cocaine-induced synaptic adaptation and the formation of cocaine-related memory. These data unveil the role of HMGB1 in neurons and provide the evidence for the HMGB1 involvement in drug addiction.

PGE2 increases inflammatory damage in Escherichia coli-infected bovine endometrial tissue in vitro via the EP4-PKA signaling pathway

Endometritis is the most common bovine uterine disease following parturition. The role of prostaglandin E2 (PGE2) in the regulation of endometrial inflammation and repair is well understood. Excess PGE2 is also generated in multiple inflammatory diseases, including endometritis. However, it remains unclear whether PGE2 is associated with pathogen-induced inflammatory damage to the endometrium. To clarify the role of PGE2 in pathogen-induced inflammatory damage, this study evaluated the production of PGE2, inflammatory factors, and damage-associated molecular patterns (DAMPs) in cultured Escherichia coli-infected bovine endometrial tissue. PGE2 production was significantly higher in E. coli-infected tissue, and in E. coli-infected tissue treated with 15-prostaglandin dehydrogenase (15-PGDH) inhibitors, as compared to uninfected tissue. Phospholipase A2 (PLA2), cyclooxygenase-2 (COX-2), and microsomal prostaglandin E synthase-1 (mPGES-1) were also upregulated in E. coli-infected tissue, while concentrations of arachidonic acid (AA), leukotrienes, DAMPs, and other proinflammatory factors increased. The accumulation of PGE2 clearly damaged the cultured tissue. Treatment with the COX-2, mPGES-1, EP4, and protein kinase A (PKA) inhibitors decreased the production of PGE2, inflammatory factors, and DAMPs, simultaneously alleviating the E. coli-induced endometrial tissue damage. Therefore, the PGE2 that was generated by COX-2 and mPGES-1 accumulated, and this pathogenic PGE2 increased inflammatory damage by upregulating inflammatory factors and DAMPs in E. coli-infected bovine endometrial tissue. This upregulation of inflammatory factors and DAMPs might be regulated by the EP4-PKA signaling pathway.

Expression of HMGB1 and TLR4 in neuropsychiatric systemic lupus erythematosus patients with seizure disorders

Background

Previous studies show that the high-mobility group box protein 1 (HMGB1) and the toll-like receptor 4 (TLR4) participate in systemic lupus erythematosus (SLE). The two molecules contribute to the occurrence and persistence of seizures in various disease conditions, such as epilepsy. Since seizures are one of the most severe complications associated with neuropsychiatric SLE (NPSLE), the current study aimed at investigating whether HMGB1 and TLR4 play any role in NPSLE related seizures.

Methods

Data from 291 SLE patients and 100 healthy controls (HC) were prospectively collected from 2013 to 2018. The ELISA test was used to determine serum levels of HMGB1 for all patients and HC and cerebrospinal fluid (CSF) levels of NPSLE patients. The expression levels of TLR4 by the peripheral blood monocytes (PBMCs) were determined by real-time PCR of TLR4 mRNA. Binary logistic regression and ROC curve analysis were used to predict NPSLE.

Results

Among the 291 SLE patients, 188 had active disease and were grouped into two, NPSLE (N=86) and Non-NPSLE (N=102) groups. Among the NPSLE patients, 21 had seizure disorders. Serum HMGB1 levels were increased in NPSLE (8.73±0.29 ng/mL) and were associated with disease activity (r=0.6527, P=0.000). Both serum and CSF HMGB1 levels in NPSLE patients with seizure disorders (9.59±0.63 and 2.90±2.29 ng/mL, respectively) were higher than in patients with other neuropsychiatric symptoms (8.45±0.33 and 2.56±1.70 ng/mL, respectively), though without significance. The gene expression of mRNA TLR4 in PBMCs was similar to serum HMGB1 in the investigated groups. Independent predictors of NPSLE were SLEDAI-2k (OR 1.25; 95% CI: 1.155-1.353), serum HMGB1 (OR 1.659; 95% CI: 1.266-2.175), and anti-Rib-P Ab (OR 3.296; 95% CI: 1.013-10.725). ROC curves for the above predictors had a large AUC (95% CI) of 0.936 (0.900-0.971), indicating a good prediction of NPSLE occurrence.

Conclusions

The expression of HMGB1 and TLR4 was increased in NPSLE, but HMGB1 and TLR4 had minimal effect on NPSLE related seizures. The serum levels of HMGB1 were positively correlated with disease activity, and could, therefore, be a potential biomarker of NPSLE for use in future clinical practice.

Analysis of Circulating HMGB1 in Human Serum

As a ubiquitous nuclear protein, high-mobility group box 1 (HMGB1) is constitutively expressed and can be actively secreted by macrophages/monocytes, as well as passively released from damaged cells following pathological injuries. Studies indicate that HMGB1 functions as a mediator of infection- and injury-elicited inflammatory diseases. Although intracellular HMGB1 functions as a regulator of tumorigenesis, epigenetic anticancer agents or therapeutic γ-ray irradiation could also cause active secretion or passive release of HMGB1, enabling serum HMGB1 to serve as a biomarker for the diagnosis and therapy of various cancers. Here we describe a semiquantitative immune blotting method to measure HMGB1 in human serum, in comparison with a commercially available HMGB1 enzyme-linked immunosorbent assay (ELISA) technique.

NOD-like receptor protein 3 and high mobility group box-1 are associated with prognosis of patients with congenital heart disease

Objective

To investigate the association between plasma levels of nucleotide-binding oligomerization domain-like (NOD)-like receptor protein 3 (NLRP3) and high mobility group box-1 (HMGB1) and their prognostic significance in neonatal patients with congenital heart disease (CHD).

Methods

This study enrolled neonatal patients with CHD and collected their demographic and clinical data. Plasma concentrations of NLRP3 and HMGB1 were measured using enzyme-linked immunosorbent assays. Spearman’s analysis was used to determine the correlation between NLRP3 and HMGB1 levels. The association between NLRP3 and HMGB1 levels and 2-year survival and mortality were evaluated using Kaplan–Meier curve and logistic regression analyses.

Results

A total of 84 neonatal patients with CHD were included in the study. Plasma NLRP3 and HMGB1 levels were significantly higher in deceased patients compared with those that survived. There was a positive correlation between NLRP3 and HMGB1 levels in neonatal patients with CHD. Patients with elevated levels of NLRP3 and HMGB1 showed significantly lower 2-year survival and higher mortality rates compared with those with lower NLRP3 and HMGB1 levels.

Conclusion

Neonatal patients with CHD and a poor prognosis had higher NLRP3 and HMGB1 levels, which suggests that these might be potential biomarkers of CHD prognosis.

Minocycline Ameliorates Depressive-Like Behavior and Demyelination Induced by Transient Global Cerebral Ischemia by Inhibiting Microglial Activation

Global cerebral ischemia (GCI) commonly occurs in the elderly. Subcortical white matter lesions and oligodendrocyte (OLG) loss caused by cerebral ischemia have been implicated in the development of post-ischemic depression and cognitive impairment. OLGs are necessary for axonal myelination; the disrupted differentiation of OLG progenitor cells (OPCs) is associated with impaired remyelination. Evidence has indicated that increased levels of inflammatory cytokines released from activated microglia induce depression-like behaviors by affecting neurotransmitter pathways, but the mechanisms remain elusive. We explored the potential mechanisms that link microglia activation with GCI-induced depression and cognitive dysfunction by studying effects of minocycline on white matter damage, cytokine levels, and the monoaminergic neurotransmitters. An acute GCI animal model was generated through bilateral common carotid artery occlusion to induce ischemic inflammation and subcortical white matter damage. Minocycline, an inhibitor of microglia activation, was intraperitoneally administrated immediately after surgery and continued daily for additional six days. Minocycline shortened the immobile duration in tail suspension test and forced swimming test, while no improvement was found in Morris water maze test. The plasma levels of IL-1β, IL-6, TNF-α, HMGB1, and netrin-1 were significantly reduced with the treatment of minocycline. Minocycline treatment substantially reversed demyelination in corpus callosum and hippocampus, alleviated hippocampal microglia activation, and promoted OPCs maturation, while no effect was found on hippocampal neurodegeneration. Besides, the content of dopamine (DA) in the hippocampus was upregulated by minocycline treatment after GCI. Collectively, our data demonstrated that minocycline exerts an anti-depressant effect by inhibiting microglia activation, promoting OPCs maturation and remyelination. Increased DA in hippocampus may also play a role in ameliorating depressive behavior with minocycline treatment.