Elevated Serum High-Mobility Group Box-1 Protein Level Is Associated with Poor Functional Outcome in Ischemic Stroke

Effect of remote ischemic preconditioning intervention on serum levels of microRNA-582-5p/HMGB1 in patients with acute cerebral infarction

OBJECTIVE

Acute cerebral infarction (ACI) contributes to disability and death accross the globe. Remote ischemic preconditioning (RIPC) reduces cerebral infarct size and improves neurological function in ACI. We conducted this research to reveal the effects of RIPC intervention on serum levels of microRNA-582-5p (miR-582-5p)/high mobility group box-1 protein (HMGB1), inflammation, oxidative stress and neurological function in patients with ACI.

METHODS

In this study, 158 patients with ACI were prospectively selected and randomized into the control (administered symptomatic medication alone) and the RIPC (underwent RIPC of the limbs based on medication) groups, with their clinical baseline data documented. Serum levels of miR-582-5p, and HMGB1 and inflammatory factors [tumor necrosis factor alpha (TNF-α)/interleukin-1beta (IL-1β)/IL-10] were assessed by RT-qPCR/ELISA, followed by comparisons of oxidative stress indices [glutathione-peroxidase (GSH-Px)/catalase (CAT)/superoxide dismutase (SOD)] using a fully automatic biochemical analyzer. Correlations between serum miR-582-5p with serum HMGB1, and between their levels with TNF-α/IL-1β/IL-10 were analyzed by Pearson analysis. The NIHSS score/Barthel Index scale were used to assess neurological function/daily living ability. Intervention safety for ACI patients was evaluated.

RESULTS

RIPC intervention increased serum miR-582-5p levels and decreased serum HMGB1 levels in ACI patients. RIPC intervention significantly reduced inflammation (diminished TNF-α/IL-1β levels, increased IL-10 level) and oxidative stress (elevated GSH-Px/CAT/SOD levels) in ACI patients. Serum miR-582-5p was negatively correlated with TNF-α and IL-1β levels, while positively correlated with IL-10 level, while HMGB1 was positively correlated with TNF-α and IL-1β levels, while negatively correlated with IL-10 level. miR-582-5p was negatively correlated with HMGB1. RIPC intervention improved neurological function (reduced NIHSS, increased Barthel scores) in ACI patients to some extent. RIPC had certain effectiveness and safety in the treatment of ACI.

CONCLUSION

After RIPC intervention, serum miR-582-5p levels were increased, HMGB1 levels were decreased, and inflammation and oxidative stress were reduced in ACI patients, which mitigated neurological deficits, improved patients' ability to perform life activities, and exerted neuroprotective effects to some extent.

HMGB1: A New Target for Ischemic Stroke and Hemorrhagic Transformation

Stroke in China is distinguished by its high rates of morbidity, recurrence, disability, and mortality. The ultra-early administration of rtPA is essential for restoring perfusion in acute ischemic stroke, though it concurrently elevates the risk of hemorrhagic transformation. High-mobility group box 1 (HMGB1) emerges as a pivotal player in neuroinflammation after brain ischemia and ischemia-reperfusion. Released passively by necrotic cells and actively secreted, including direct secretion of HMGB1 into the extracellular space and packaging of HMGB1 into intracellular vesicles by immune cells, glial cells, platelets, and endothelial cells, HMGB1 represents a prototypical damage-associated molecular pattern (DAMP). It is intricately involved in the pathogenesis of atherosclerosis, thromboembolism, and detrimental inflammation during the early phases of ischemic stroke. Moreover, HMGB1 significantly contributes to neurovascular remodeling and functional recovery in later stages. Significantly, HMGB1 mediates hemorrhagic transformation by facilitating neuroinflammation, directly compromising the integrity of the blood-brain barrier, and enhancing MMP9 secretion through its interaction with rtPA. As a systemic inflammatory factor, HMGB1 is also implicated in post-stroke depression and an elevated risk of stroke-associated pneumonia. The role of HMGB1 extends to influencing the pathogenesis of ischemia by polarizing various subtypes of immune and glial cells. This includes mediating excitotoxicity due to excitatory amino acids, autophagy, MMP9 release, NET formation, and autocrine trophic pathways. Given its multifaceted role, HMGB1 is recognized as a crucial therapeutic target and prognostic marker for ischemic stroke and hemorrhagic transformation. In this review, we summarize the structure and redox properties, secretion and pathways, regulation of immune cell activity, the role of pathophysiological mechanisms in stroke, and hemorrhage transformation for HMGB1, which will pave the way for developing new neuroprotective drugs, reduction of post-stroke neuroinflammation, and expansion of thrombolysis time window.

Higher High-Mobility Group Box-1 Levels are Associated with White Matter Lesions in Ischemic Stroke Patients

Background and Purpose

High-mobility group box-1 (HMGB1) is a useful biomarker for disease severity stratification and prognosis prediction. We aim to explore whether the circulating HMGB1 concentrations are associated with the white matter lesions (WMLs) burden in stroke patients.

Methods

Between 2022 June and December 2022, patients with acute ischemic stroke were prospectively enrolled. HMGB1 levels were measured by an enzyme-linked immunosorbent assay after admission for all patients. The WMLs severity was assessed by the Fazekas scale. We dichotomized patients into those with moderate-severe WMLs (Fazekas score 3-6) versus those with none-mild WMLs (Fazekas score 0-2). Furthermore, based on the severity of periventricular WMLs (PWMLs) and deep WMLs (DWMLs), patients were categorized as none-mild (Fazekas score 0-1) or moderate-severe (Fazekas score 2-3).

Results

A total of 287 participants (mean age: 64.9 years; 157 male) were analyzed. The median serum HMGB1 levels were 7.3 ng/mL (interquartile, 4.3 ng/mL-12.3 ng/mL). After adjustment for potential confounders, elevated HMGB1 levels were associated with the presence of moderate-severe WMLs (first quartile vs fourth quartile, odds ratio [OR], 4.101; 95% confidence interval [CI], 1.948-8.633; P = 0.001) and moderate-severe PWMLs (first quartile vs fourth quartile, OR, 9.181; 95% CI, 4.078-20.671; P = 0.001). Similar results were found when the HMGB1 levels were analyzed as a continuous variable.

Conclusion

This study demonstrated that increased HMGB1 levels were associated with the severity of WMLs, mainly in the periventricular region.

Neuroinflammatory Biomarkers in the Brain, Cerebrospinal Fluid, and Blood After Ischemic Stroke

The most frequent type of stroke, known as ischemic stroke (IS), is a significant global public health issue. The pathological process of IS and post-IS episodes has not yet been fully explored, but neuroinflammation has been identified as one of the key processes. Biomarkers are objective indicators used to assess normal or pathological processes, evaluate responses to treatment, and predict outcomes, and some biomarkers can also be used as therapeutic targets. After IS, various molecules are produced by different cell types, such as microglia, astrocytes, infiltrating leukocytes, endothelial cells, and damaged neurons, that participate in the neuroinflammatory response within the ischemic brain region. These molecules may either promote or inhibit neuroinflammation and may be released into extracellular spaces, including cerebrospinal fluid (CSF) and blood, due to reasons such as BBB damage. These neuroinflammatory molecules should be valued as biomarkers to monitor whether their expression levels in the blood, CSF, and brain correlate with the diagnosis and prognosis of IS patients or whether they have potential as therapeutic targets. In addition, although some molecules do not directly participate in the process of neuroinflammation, they have been reported to have potential diagnostic or therapeutic value against post-IS neuroinflammation, and these molecules will also be listed. In this review, we summarize the neuroinflammatory biomarkers in the brain, CSF, and blood after an IS episode and the potential value of these biomarkers for the diagnosis, treatment, and prognosis of IS patients.

QHRD106 ameliorates ischemic stroke injury as a long-acting tissue kallikrein preparation

Ischemic stroke is the second leading cause of death worldwide, and there are limited effective treatment strategies. QHRD106, a polyethyleneglycol (PEG)-modified long-acting tissue kallikrein preparation, has not been reported previously. In this study, we aimed to investigate the therapeutic effect of QHRD106 in ischemic stroke and its possible mechanism. We found that QHRD106 treatment alleviated brain injury after stroke via bradykinin (BK) receptor B2 (B2R) instead of BK receptor B1 (B1R). Mechanistically, QHRD106 reduced high-mobility group box 1 (HMGB1)-induced apoptosis and inflammation after ischemic stroke in vivo and in vitro. Moreover, we confirmed that QHRD106 reduced the level of acetylated HMGB1 and reduced the binding between heat shock protein 90 alpha family class A member 1 (HSP90AA1) and HMGB1, thus inhibiting the translocation and release of HMGB1. In summary, these findings indicate that QHRD106 treatment has therapeutic potential for cerebral ischemic stroke.

The role of high mobility group box 1 in neuroinflammatory related diseases

High mobility group box 1 (HMGB1) is a ubiquitous and highly conserved non-histone DNA-binding protein with different biological functions according to its subcellular localization. It is widely believed that HMGB1, which is released into the extracellular space, plays a key role in the inflammatory response. In recent years, numerous studies have shown that the development of various neurological diseases such as epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), cerebrovascular disease and traumatic brain injury (TBI) are inextricably linked to inflammation. We will review the mechanisms of HMGB1 and its receptors in nervous system inflammation to provide a basis for further development of new HMGB1-based therapies.

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.

Janus Faced HMGB1 and Post-Aneurysmal Subarachnoid Hemorrhage (aSAH) Inflammation

Aneurysmal subarachnoid hemorrhage (aSAH), resulting majorly from the rupture of intracranial aneurysms, is a potentially devastating disease with high morbidity and mortality. The bleeding aneurysms can be successfully secured; however, the toxic and mechanical impact of the blood extravasation into the subarachnoid space damages the brain cells leading to the release of different damage-associated molecular pattern molecules (DAMPs). DAMPs upregulate the inflammation after binding their cognate receptors on the immune cells and underlies the early and delayed brain injury after aSAH. Moreover, these molecules are also associated with different post-aSAH complications, which lead to poor clinical outcomes. Among these DAMPs, HMGB1 represents a prototypical protein DAMP that has been well characterized for its proinflammatory role after aSAH and during different post-aSAH complications. However, recent investigations have uncovered yet another face of HMGB1, which is involved in the promotion of brain tissue remodeling, neurovascular repair, and anti-inflammatory effects after SAH. These different faces rely on different redox states of HMGB1 over the course of time after SAH. Elucidation of the dynamics of these redox states of HMGB1 has high biomarker as well as therapeutic potential. This review mainly highlights these recent findings along with the conventionally described normal role of HMGB1 as a nuclear protein and as a proinflammatory molecule during disease (aSAH).

Systemic inflammation after stroke: implications for post-stroke comorbidities

Immunological mechanisms have come into the focus of current translational stroke research, and the modulation of neuroinflammatory pathways has been identified as a promising therapeutic approach to protect the ischemic brain. However, stroke not only induces a local neuroinflammatory response but also has a profound impact on systemic immunity. In this review, we will summarize the consequences of ischemic stroke on systemic immunity at all stages of the disease, from onset to long‐term outcome, and discuss underlying mechanisms of systemic brain‐immune communication. Furthermore, since stroke commonly occurs in patients with multiple comorbidities, we will also overview the current understanding of the potential role of systemic immunity in common stroke‐related comorbidities, such as cardiac dysfunction, atherosclerosis, diabetes, and infections. Finally, we will highlight how targeting systemic immunity after stroke could improve long‐term outcomes and alleviate comorbidities of stroke patients.

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).

Correlation Between Plasma High Mobility Group Protein N1 Level and the Prognosis of Patients with Acute Cerebral Infarction: Preliminary Findings

PURPOSE

To investigate the correlation between plasma levels of high mobility group protein N1 (HMGN1) and the severity of neurological deficits and prognosis in patients with acute cerebral infarction (ACI).

PATIENTS AND METHODS

The plasma HMGN1 levels of 108 patients with ACI were detected by ELISA. The National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin Scale (mRS) were used to assess the neurological impairment and outcomes of these patients, respectively. The correlation between HMGN1 levels and clinical parameters was analyzed.

RESULTS

The plasma HMGN1 levels of patients with ACI were positively correlated with their NIHSS and mRS scores. Patients with the large artery atherosclerosis (LAA) subtype in the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification had higher plasma HMGN1 levels than patients with other subtypes.

CONCLUSION

HMGN1 levels are positively correlated with the severity of ACI and could be used to predict the prognosis of these patients. HMGN1 can be used as a biological marker and potential target for clinical assessment and therapy of ACI.

Inflammation Mediated Epileptogenesis as Possible Mechanism Underlying Ischemic Post-stroke Epilepsy

Post-stroke Epilepsy (PSE) is one of the most common forms of acquired epilepsy, especially in the elderly population. As people get increasingly older, the number of stroke patients is expected to rise and concomitantly the number of people with PSE. Although many patients are affected by post-ischemic epileptogenesis, not much is known about the underlying pathomechanisms resulting in the development of chronic seizures. A common hypothesis is that persistent neuroinflammation and glial scar formation cause aberrant neuronal firing. Here, we summarize the clinical features of PSE and describe in detail the inflammatory changes after an ischemic stroke as well as the chronic changes reported in epilepsy. Moreover, we discuss alterations and disturbances in blood-brain-barrier leakage, astrogliosis, and extracellular matrix changes in both, stroke and epilepsy. In the end, we provide an overview of commonalities of inflammatory reactions and cellular processes in the post-ischemic environment and epileptic brain and discuss how these research questions should be addressed in the future.

Newly-identified blood biomarkers of neurological damage are correlated with infarct volume in patients with acute ischemic stroke

Our group recently performed a genome-wide informatic analysis that highlighted eight brain-enriched proteins with strong potential to serve as blood biomarkers of neurological injury (GFAP, MBP, β-synuclein, OPALIN, MT-3, SNAP-25, KIF5A, MOBP), including six that have yet to be widely investigated. In this study, our aim was to determine whether the circulating levels of these proteins could be used to approximate the extent of neural tissue damage in ischemic stroke. To address this aim, blood was collected from 43 ischemic stroke patients immediately upon hospital admission. The serum levels of the eight candidate proteins were measured via ELISA, infarct volume was assessed via manual tracing of neuroradiological images, and correlational analysis was performed to examine potential associative relationships. The serum levels of all eight proteins exhibited positive correlations with infarct volume, however the strongest associations were observed in a subset of four proteins known to originate from neurons specifically (MT-3, SNAP-25, KIF5A, β-synuclein). Combining the serum levels of these neuron-originating proteins using principal components analysis produced a single composite value that was more strongly correlated with infarct volume than the levels of any single protein considered in isolation (r = 0.48, p < 0.001). Measures of these proteins could potentially be used to provide a minimally invasive approximation of lesion size when advanced imaging techniques are not available, or when imaging results are inconclusive.

Increased high-mobility group box 1 levels are associated with depression after acute ischemic stroke

BACKGROUND AND PURPOSE

Increased high-mobility group box 1 (HMGB1) levels were found in patients after acute ischemic stroke. The aim of this study was to examine whether the circulating HMGB1 levels could predict the 3-month post-stroke depression (PSD).

METHODS

The subjects were first-ever ischemic stroke patients who were hospitalized during the period from July 2020 to December 2020. HMGB1 concentrations were measured by enzyme-linked immunosorbent assay after admission. A 24-item Hamilton Depression Rating Scale was performed to evaluate PSD at 3 months after stroke.

RESULTS

The analyses included 324 participants (mean age, 63.7 years; 171 male). Ninety-four patients (29.0%) were diagnosed as having PSD at 3 months. The median serum HMGB1 levels at admission was 7.5 ng/mL (IQR, 4.4-11.3 ng/mL). The PSD distribution across the HMGB1 quartiles ranged between 17.5% (first quartile) and 57.5% (fourth quartile). After covariate adjustments, the fourth quartile of HMGB1 was found to be associated with a higher risk of PSD (as compared with first HMGB1 quartile, odd ratio, 1.26; 95% confidence interval [CI], 1.17-1.35; P < 0.001). The area under the receiver operating characteristic curve of HMGB1 was 0.726 (95% CI 0.660-0.792) for PSD. Similar results were found when HMGB1 was analyzed as continuous variable. Furthermore, the optimal cutoff point of circulating HMGB1 levels was 8.6 ng/mL, with a sensitivity of 69.2% and a specificity of 73.9%.

CONCLUSIONS

This study demonstrated that higher HMGB1 levels in the acute phase of ischemic stroke were associated with increased risk of PSD.

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.

Elevated plasma levels of galectin-3 binding protein are associated with post-stroke delirium - A pilot study

To explore the role of systemic inflammation in post-stroke delirium, we investigated the level of two inflammatory mediators: high mobility group box 1 (HMGB1) and galectin-3 binding protein (Gal-3BP). Of 571 stroke patients, we compared plasma levels of HMGB1 and Gal-3BP in 79 delirious patients with 81 non-delirious patients matched for age and stroke severity. Delirious patients had higher Gal-3BP level (median: 1440 vs 1053 ng/mL, P < 0.01). An elevated level of Gal-3BP was associated with an increased risk of delirium. HMGB1 levels did not differ between groups. Our results suggest that pro-inflammatory monocytes and macrophages might be involved in delirium pathophysiology.

DAMPs and RAGE Pathophysiology at the Acute Phase of Brain Injury: An Overview

Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives

Clinical perspectives on ischemic stroke

Treatments for acute stroke have improved over the past years, but have largely been limited to revascularization strategies. The topic of neuroprotection, or strategies to limit brain tissue damage or even reverse it, has remained elusive. Thus, the clinical mainstays for stroke management have focused on prevention. The lack of clinical translation of neuroprotective therapies which have shown promise in the laboratory may, in part, be due to a historic inattention to comorbidities suffered by a majority of stroke patients. With the advent of more stroke models that include one or more relevant comorbidities, it may be possible to identify effective treatments that may translate into new treatments at the clinical level. In the meantime, we review comorbidities in stroke patients, modification of stroke risk factors and available acute stroke treatments in the clinic.

High Mobility Group Box-1 and Blood-Brain Barrier Disruption

Increasing evidence suggests that inflammatory responses are involved in the progression of brain injuries induced by a diverse range of insults, including ischemia, hemorrhage, trauma, epilepsy, and degenerative diseases. During the processes of inflammation, disruption of the blood–brain barrier (BBB) may play a critical role in the enhancement of inflammatory responses and may initiate brain damage because the BBB constitutes an interface between the brain parenchyma and the bloodstream containing blood cells and plasma. The BBB has a distinct structure compared with those in peripheral tissues: it is composed of vascular endothelial cells with tight junctions, numerous pericytes surrounding endothelial cells, astrocytic endfeet, and a basement membrane structure. Under physiological conditions, the BBB should function as an important element in the neurovascular unit (NVU). High mobility group box-1 (HMGB1), a nonhistone nuclear protein, is ubiquitously expressed in almost all kinds of cells. HMGB1 plays important roles in the maintenance of chromatin structure, the regulation of transcription activity, and DNA repair in nuclei. On the other hand, HMGB1 is considered to be a representative damage-associated molecular pattern (DAMP) because it is translocated and released extracellularly from different types of brain cells, including neurons and glia, contributing to the pathophysiology of many diseases in the central nervous system (CNS). The regulation of HMGB1 release or the neutralization of extracellular HMGB1 produces beneficial effects on brain injuries induced by ischemia, hemorrhage, trauma, epilepsy, and Alzheimer’s amyloidpathy in animal models and is associated with improvement of the neurological symptoms. In the present review, we focus on the dynamics of HMGB1 translocation in different disease conditions in the CNS and discuss the functional roles of extracellular HMGB1 in BBB disruption and brain inflammation. There might be common as well as distinct inflammatory processes for each CNS disease. This review will provide novel insights toward an improved understanding of a common pathophysiological process of CNS diseases, namely, BBB disruption mediated by HMGB1. It is proposed that HMGB1 might be an excellent target for the treatment of CNS diseases with BBB disruption.

High-Mobility Group Box-1 Is Associated With Obesity, Inflammation, and Subclinical Cardiovascular Risk Among Young Adults: A Longitudinal Cohort Study

OBJECTIVE

We aimed to characterize circulating HMGB1 (high-mobility group box-1) levels, one of the better-characterized damage-associated molecular patterns, with respect to age, sex, and race in the general population, and investigate the longitudinal associations of HMGB1 with inflammatory markers, obesity, and preclinical markers of cardiovascular disease. Approach and Results: The analyses included 489 participants (50% Blacks, aged 24.6±3.3 years at the first visit) with up to 4 follow-up visits (1149 samples) over a maximum of 8.5 years. Systolic blood pressure, diastolic blood pressure, carotid-femoral pulse wave velocity, and carotid intima-media thickness together with plasma HMGB1, hs-CRP (high-sensitivity C-reactive protein), IFN-γ (interferon-γ), IL-6 (interleukin-6), IL-10 (interleukin-10), and TNF-α (tumor necrosis factor-α) were measured at each visit. At baseline, plasma HMGB1 concentrations were higher in Blacks compared with Whites (3.86 versus 3.20 ng/mL, P<0.001), and in females compared with males (3.75 versus 3.30 ng/mL, P=0.005). HMGB1 concentrations increased with age (P=0.007), and higher levels of obesity measures (P<0.001). Without adjustment for age, sex, race, and body mass index, HMGB1 concentrations were positively associated with hs-CRP, IL-6, TNF-α, systolic blood pressure, diastolic blood pressure, and carotid-femoral pulse wave velocity (P<0.05) but not IL-10, IFN-γ or carotid intima-media thickness. After covariate adjustments, the associations of HMGB1 with hs-CRP, and carotid-femoral pulse wave velocity remained statistically significant (P<0.05).

CONCLUSIONS

This study demonstrates the age, sex, and race differences in circulating HMGB1. The increasing circulating concentrations of HMGB1 with age suggest a potential role of HMGB1 in the pathogenesis of chronic low-grade inflammation, obesity, and subclinical cardiovascular disease risk.

Can baseline C-reactive protein level predict functional outcome in acute ischaemic stroke? A meta-analysis

BACKGROUND

The association between elevated C-reactive protein (CRP) level and poor functional outcome is conflicting in acute ischaemic stroke (AIS) patients. This meta-analysis sought to investigate the value of elevated CRP level in predicting poor functional outcome in AIS patients.

MATERIAL AND METHODS

A systematically literature search was performed in PubMed and Embase databases up to 31 October 2019. Prospective and retrospective studies evaluating the association between elevated CRP level and poor functional outcome (defined by the modified Rankin scale ≥3) beyond 3 months after AIS were included.

RESULTS

Ten studies with a total of 8087 AIS patients were identified in this meta-analysis. When compared with reference low CRP level, the highest CRP level was associated with an increased risk of poor functional outcome (multivariate-adjusted hazard ratio (HR) 1.99; 95% confidence interval (CI) 1.63-2.44) in a random effect model. Sensitivity analysis further confirmed the significance of CRP elevation for predicting poor functional outcome after AIS.

CONCLUSIONS

Elevated CRP level is significantly associated with poor functional outcome in patients with AIS. Baseline CRP level has potential to improve risk stratification of function outcome in AIS patients.

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.

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.

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.

Salvianolic Acid D Alleviates Cerebral Ischemia-Reperfusion Injury by Suppressing the Cytoplasmic Translocation and Release of HMGB1-Triggered NF-κB Activation to Inhibit Inflammatory Response

Inflammatory response participates in the overall pathophysiological process of stroke. It is a promising strategy to develop antistroke drugs targeting inflammation. This study is aimed at investigating the therapeutic effect and anti-inflammatory mechanism of salvianolic acid D (SalD) against cerebral ischemia/reperfusion (I/R) injury. A rat middle cerebral artery occlusion/reperfusion (MCAO/R) injury model was established, and an oxygen-glucose deprivation/reoxygenation (OGD/R) injury model was established in PC12 cells. Neurological deficit score, cerebral infarction, and edema were studied in vivo. Cell viability was achieved using the MTT method in vitro. The Bax, Bcl-2, cytochrome c, HMGB1, TLR4, TRAF6, NF-κB p65, p-NF-κB p65, and cleaved caspase-3 and -9 were tested via the Western blot method. Cytokines and cytokine mRNA, including TNF-α, IL-1β, and IL-6, were studied via ELISA and PCR methods. The translocation of HMGB1 and NF-κB were studied by immunofluorescence assay. The HMGB1/NeuN, HMGB1/GFAP, and HMGB1/Iba1 double staining was carried out to observe the localization of HMGB1 in different cells. Results showed that SalD alleviated neurological impairment, decreased cerebral infarction, and reduced edema in I/R rats. SalD improved OGD/R-downregulated PC12 cell viability. SalD also promoted Bcl-2 expression and suppressed Bax, cytochrome c, and cleaved caspase-3 and -9 expression. SalD decreased the intensity of TLR4, MyD88, and TRAF6 proteins both in vivo and in vitro, and significantly inhibited the NF-κB nuclear translocation induced by I/R and OGD/R. What's more, SalD inhibited HMGB1 cytoplasmic translocation in neurons, astrocytes, and microglia in both the cortex and hippocampus regions of I/R rats. In conclusion, SalD can alleviate I/R-induced cerebral injury in rats and increase the PC12 cell viability affected by OGD/R. The anti-inflammatory mechanism of SalD might result from the decreased nuclear-to-cytoplasmic translocation of HMGB1 and the inhibition on its downstream TLR4/MyD88/NF-κB signaling.

The lncRNA Malat1 functions as a ceRNA to contribute to berberine-mediated inhibition of HMGB1 by sponging miR-181c-5p in poststroke inflammation

Long non-coding RNAs (lncRNAs) have been identified as essential mediators in neurological dysfunction. Our previous study shows that berberine (BBR) hampers the nuclear-to-cytosolic translocation of high-mobility group box 1 (HMGB1) in the process of poststroke inflammation. In this study, we explored the role of lncRNA metastasis-associated lung adenocarcinoma transcript 1 (Malat1) in the process of BBR-induced inhibition of HMGB1 in ischemic brain. Before the 60-min MCAO surgery, the mice were pretreated with BBR (50 mg· kg^-1 per day, ig) for 14 days or ICV injected with specific lentiviral vector or shRNA. We showed that MCAO caused marked increase in the expression Malat1 and HMGB1 in the ipsilateral cortex, which was significantly attenuated by pretreatment with BBR. Knockdown of Malat1 attenuated the inflammatory injury after brain ischemia, whereas overexpression of Malat1 exacerbated ischemic brain inflammation. Overexpression of Malat1 also reversed BBR-induced reduction of HMGB1 and proinflammatory cytokines. The above results suggested a potential correlation between Malat1 and stroke inflammation. Based on informatics analysis we predicted that HMGB1 was a direct downstream target of miR-181c-5p, whereas Malat1 acted as a competitive endogenous RNA (ceRNA) for miR-181c-5p targeted the 3'-UTR of HMGB1 to promote inflammation after ischemic stroke. Knockdown of Malat1 significantly decreased HMGB1 level, which could be abrogated by transfection with miR-181c-5p inhibitors. Taken together, our results demonstrate for the first time that Malat1/miR-181c-5p/HMGB1 axis may be a key pathway of BBR-induced antiinflammation effects in stroke, and they may provide a novel avenue for targeted therapy.

Neuroinflammation: friend and foe for ischemic stroke

Stroke, the third leading cause of death and disability worldwide, is undergoing a change in perspective with the emergence of new ideas on neurodegeneration. The concept that stroke is a disorder solely of blood vessels has been expanded to include the effects of a detrimental interaction between glia, neurons, vascular cells, and matrix components, which is collectively referred to as the neurovascular unit. Following the acute stroke, the majority of which are ischemic, there is secondary neuroinflammation that both promotes further injury, resulting in cell death, but conversely plays a beneficial role, by promoting recovery. The proinflammatory signals from immune mediators rapidly activate resident cells and influence infiltration of a wide range of inflammatory cells (neutrophils, monocytes/macrophages, different subtypes of T cells, and other inflammatory cells) into the ischemic region exacerbating brain damage. In this review, we discuss how neuroinflammation has both beneficial as well as detrimental roles and recent therapeutic strategies to combat pathological responses. Here, we also focus on time-dependent entry of immune cells to the ischemic area and the impact of other pathological mediators, including oxidative stress, excitotoxicity, matrix metalloproteinases (MMPs), high-mobility group box 1 (HMGB1), arachidonic acid metabolites, mitogen-activated protein kinase (MAPK), and post-translational modifications that could potentially perpetuate ischemic brain damage after the acute injury. Understanding the time-dependent role of inflammatory factors could help in developing new diagnostic, prognostic, and therapeutic neuroprotective strategies for post-stroke inflammation.

Harmful neutrophil subsets in patients with ischemic stroke: Association with disease severity

Objective

To better understand the functional state of circulating neutrophils in patients with ischemic stroke (IS) for planning future clinical trials.

Methods

We analyzed by flow cytometry activation state of circulating neutrophils and the distribution of neutrophil peripheral subsets in 41 patients with acute IS less than 6 hours before admission and compared them with 22 age-matched healthy controls.

Results

Our results demonstrated continuous basal hyperactivation of circulating neutrophils during acute IS, characterized by lower l-selectin expression and higher CD11b expression at the cell surface, increased ROS production by neutrophils, and greater circulating levels of neutrophil elastase. Neutrophil hyperactivation was associated with deregulation of the equilibrium between apoptotic and necrotic. Patients also had higher percentages than controls of the overactive senescent (CXCR4^bright/CD62L^dim) neutrophil subset and increased percentage of neutrophils with a reverse transendothelial migration (CD54^highCXCR1^low) phenotype. Importantly, neutrophil alterations were associated with the clinical severity of the stroke, evaluated by its NIH Stroke Scale score.

Conclusion

Altogether, our results indicate that during acute IS, the inflammatory properties of circulating neutrophils rise, associated with the expansion of harmful neutrophil subsets. These changes in neutrophil homeostasis, associated with disease severity, may play an instrumental role by contributing to systemic inflammation and to the blood-brain barrier breakdown. Our findings highlight new potential therapeutic approaches of stroke by rebalancing the ratio of senescent to immunosuppressive neutrophils or decreasing reverse neutrophil transmigration or both.

Anti-HMGB1 monoclonal antibody therapy for a wide range of CNS and PNS diseases

High mobility group box-1 (HMGB1), a representative damage associated-molecular pattern (DAMP), has been reported to be involved in many inflammatory diseases. Several drugs are thought to have potential to control the translocation and secretion of HMGB1, or to neutralize extracellular HMGB1 by binding to it. One of these drugs, anti-HMGB1 monoclonal antibody (mAb), is highly specific for HMGB1 and has been shown to be effective for the treatment of a wide range of CNS diseases when modeled in animals, including stroke, traumatic brain injury, Parkinson's disease, epilepsy and Alzheimer's disease. Thus, anti-HMGB1 mAb not only is useful for target validation but also has extensive potential for the treatment of the above-mentioned diseases. In this review, we summarize existing knowledge on the effects of anti-HMGB1 mAb on CNS and PNS diseases, the common features of translocation and secretion of HMGB1 and the functional roles of HMGB1 in these diseases. The existing literature suggests that anti-HMGB1 mAb therapy would be effective for a wide range of CNS and PNS diseases.

The role of high high-sensitivity C-reactive protein levels at admission on poor prognosis after acute ischemic stroke

OBJECTIVE

Plasma high hypersensitive C-reactive protein (hs-CRP) levels are associated with risk and prognosis of vascular diseases. The clinical implications of markedly elevated hs-CRP levels are more discovered in the onset and development of stroke. The aim of this study is to determine the association of plasma hs-CRP levels on the prognosis in patients with acute ischemic stroke.

METHODS

Retrospective analysis of a single-center database of consecutive cases for acute cerebral infarction (ACI) from January 1 2012 to December 30 2016 was performed. Significant predictors of the dependent variable variance were identified by standard linear, univariate and multivariate, or binary logistic regression modeling. Multivariate regression analysis was introduced to investigate the relationship between plasma hs-CRP levels at admission and change in National Institutes of Health Stroke Scale (NIHSS) score at discharge.

RESULTS

The percentages of hypertension, diabetes mellitus, hyperlipidemia, atrial fibrillation, body mass index (BMI) and chronic kidney disease were raised with the increase of hs-CRP plasma concentration at admission among all patients (p < 0.05). ACI patients with large-artery atherosclerosis had an increasing percentage with the increase of hs-CRP mean value (p < 0.05). The initial NIHSS scores, the acute infection rate and age advance also increased with the increase of hs-CRP plasma concentration at admission (p < 0.05). The ratio of neurological improvement increased with the decrease of plasma hs-CRP concentration (p < 0.05). The neurological deterioration and poor prognosis increased with the increase of plasma hs-CRP concentration (p < 0.05).

CONCLUSION

High plasma hs-CRP levels are associated with worse outcomes in the ACI patients. Monitoring plasma hs-CRP levels and cutting down the elevated plasma hs-CRP levels will be beneficial in screening and treatment decisions for the prognosis of acute ischemic stroke.

Association of circulating blood HMGB1 levels with ischemic stroke: a systematic review and meta-analysis

OBJECTIVES

Inflammation plays a key role in the pathogenesis and progression of ischemic stroke (IS). The high mobility group box 1 (HMGB1) nucleoprotein is involved in the amplification of inflammatory responses during acute ischemic injury. HMGB1 levels in patients with active disease are higher than those in healthy controls. We performed a meta-analysis to assess currently published data pertaining to circulating blood HMGB1 levels in IS and the relationship with stroke severity.

METHODS

We systematically searched for studies investigating the circulating blood HMGB1 levels in patients with IS in PubMed/Medline, Embase, the Cochrane Library, Web of science and China National Knowledge Infrastructure (CNKI). Two independent researchers used the Cochrane Collaboration tools for data extraction and quality assessment. Extracted data were analyzed by Review Manager version 5.3.

RESULTS

A total of 28 studies were included with a total of 4497 participants, including 2671 IS patients and 1826 matched controls. The meta-analysis revealed that compared with control, IS patients had higher circulating blood HMGB1 levels (n = 4497, standardized mean difference (SMD) = 5.70, 95%confidence interval (CI) = 4.79 to 6.62, Z = 12.23, P < 0.00001), and the HMGB1 level was positively correlated with severity (n = 507, SMD = -2.12, 95%CI = -3.41 to -0.82, Z = 3.20, P < 0.00001) and infarct volume (n = 582, 95%CI = -4.06 to -1.70, Z = 4.79, P < 0.00001).

CONCLUSIONS

This meta-analysis demonstrates that circulating blood HMGB1 levels elevate in IS and higher HMGB1 levels may indicate a more serious condition.

Berberine attenuates ischemia-reperfusion injury through inhibiting HMGB1 release and NF-κB nuclear translocation

Inflammatory damage plays an important role in cerebral ischemic pathogenesis and represents a new target for treatment of stroke. Berberine is a natural medicine with multiple beneficial biological activities. In this study, we explored the mechanisms underlying the neuroprotective action of berberine in mice subjected transient middle cerebral artery occlusion (tMCAO). Male mice were administered berberine (25, 50 mg/kg/d, intragastric; i.g.), glycyrrhizin (50 mg/kg/d, intraperitoneal), or berberine (50 mg/kg/d, i.g.) plus glycyrrhizin (50 mg/kg/d, intraperitoneal) for 14 consecutive days before tMCAO. The neurological deficit scores were evaluated at 24 h after tMCAO, and then the mice were killed to obtain the brain samples. We showed that pretreatment with berberine dose-dependently decreased the infarct size, neurological deficits, hispathological changes, brain edema, and inflammatory mediators in serum and ischemic cortical tissue. We revealed that pretreatment with berberine significantly enhanced uptake of ¹⁸F-fluorodeoxyglucose of ischemic hemisphere comparing with the vehicle group at 24 h after stroke. Furthermore, pretreatment with berberine dose-dependently suppressed the nuclear-to cytosolic translocation of high-mobility group box1 (HMGB1) protein, the cytosolic-to nuclear translocation of nuclear factor kappa B (NF-κB) and decreased the expression of TLR4 in ischemic cortical tissue. Moreover, co-administration of glycyrrhizin and berberine exerted more potent suppression on the HMGB1/TLR4/NF-κB pathway than berberine or glycyrrhizin administered alone. These results demonstrate that berberine protects the brain from ischemia-reperfusion injury and the mechanism may rely on its anti-inflammatory effects mediated by suppressing the activation of HMGB1/TLR4/NF-κB signaling.

The role of high mobility group box 1 protein in acute cerebrovascular diseases

The occurrence and development of acute cerebrovascular diseases involves an inflammatory response, and high mobility group box protein 1 (HMGB1) is a pro-inflammatory factor that is expressed not only in the early-injury stage of disease, but also during the post-repair process. In the initial stage of disease, HMGB1 is released into the outside of the cell to participate in the cascade amplification reaction of inflammation, causing vasospasm, destruction of the blood-brain barrier and apoptosis of nerve cells. In the recovery stage of disease, HMGB1 can promote tissue repair and remodeling, which can aid in nerve function recovery. This review summarizes the biological characteristics of HMGB1, and the role of HMGB1 in ischemic and hemorrhagic cerebrovascular disease, and cerebral venous thrombosis.

Reduced release of TNFα and IP-10 after ex vivo blood stimulation with endotoxin is associated with poor outcome after stroke

BACKGROUND AND AIMS

The immune response to acute cerebral ischemia plays an important role in the pathophysiology of stroke and could be a therapeutic target. Toll-like receptor 4 (TLR4) is a master regulator of innate immunity. The aim of our study was to determine the association between selected cytokine release after TLR4 activation in blood cells and the outcome after ischemic stroke.

METHODS

We included 156 ischemic stroke patients (median age: 69; 40.4% female). Venous blood was collected at day 3 after the onset of stroke and stimulated ex vivo with lipopolysaccharide (LPS). The LPS-induced level of tumor necrosis factor alpha (TNFα) was used as a proxy of the MyD88-dependent pathway, and interferon-gamma-inducible protein 10 (IP-10) was used as a proxy of the MyD88-independent pathway. The functional outcome was assessed at 3 months after stroke onset.

RESULTS

TNFα (median: 2.2 vs. 3.5 pg/10³ monocytes, p < .01) and IP-10 release (median: 0.3 vs. 0. 6 pg/10³ monocytes, p < .01) was reduced in patients with a poor outcome. In a multivariate logistic regression analysis adjusted for age, stroke severity, and pneumonia, low TNFα release was associated with a poor outcome (OR: 4.23, 95%CI: 1.64-10.90, p = .03). Similarly, low IP-10 release was related to an unfavorable prognosis (adjusted OR: 3.42, 95%CI: 1.49-8.21, p < .01).

CONCLUSIONS

The reduced release of TNFα and IP-10 after ex vivo blood stimulation with endotoxin is independently associated with poor outcome after stroke. Our results suggest that the inhibition of both the MyD88-dependent pathway and MyD88-independent pathway of TLR4 signaling in blood cells correlates with an unfavorable prognosis in stroke patients.