6-Gingerol protects against cerebral ischemia/reperfusion injury by inhibiting NLRP3 inflammasome and apoptosis via TRPV1 / FAF1 complex dissociation-mediated autophagy.

BACKGROUND: Our previous studies demonstrated that autophagy alleviates cerebral I/R injury by inhibiting NLRP3 inflammasome-mediated inflammation. 6-Gingerol, a phenolic compound extracted from ginger, was reported to possess potent antiapoptotic and anti-inflammatory activities and is associated with autophagy. However, the effects of 6-Gingerol in cerebral I/R injury have not been elucidated, and whether they involve autophagy-induced NLRP3 inflammasome inhibition remains unclear. METHODS: Adult male Sprague-Dawley (SD) rats were subjected to middle cerebral artery occlusion (MCAO) for 1 h, followed by reperfusion for 24 h. 6-Gingerol and 3-methyladenine (3-MA) were injected intraperitoneally, and si-TRPV1 was injected via the lateral ventricle. Cerebral infarct volume, brain edema, neurological deficits, HE and Nissl were used to evaluate the morphological and functional changes of brain tissue, respectively. TRPV1, FAF1, autophagy related (LC3II/I, P62, Beclin1), inflammation related (NLRP3, cleaved-caspase-1, caspase-1, cleaved-IL-1ß, IL-1ß, cleaved-IL-18, IL-18) and apoptosis related (Bcl-2, Bax, cleaved-caspase-3) proteins were assessed by Western blot, immunofluorescence staining and coimmunoprecipitation, respectively. Enzyme linked immunosorbent assay (ELISA) was used to evaluate the changes in the expression levels of interleukin-1 (IL-1ß) and interleukin-18(IL-18), respectively. The degree of neuronal apoptosis was evaluated by TUNEL staining. Neuronal ultrastructure was examined by transmission electron microscopy. RESULT: 6-Gingerol treatment significantly reduced cerebral infarct volume, improved brain edema and neurological scores, and reversed brain histomorphological damage after I/R injury. In addition, 6-Gingerol significantly reduced NLRP3 inflammasome-derived inflammation and neuronal apoptosis and upregulated autophagy. The autophagy inhibitor 3-MA rescued the effects of 6-Gingerol on the NLRP3 inflammasome and apoptosis. Moreover, the findings illustrated that 6-Gingerol inhibited autophagy-induced NLRP3 inflammasome activation and apoptosis through the dissociation of TRPV1 from FAF1. CONCLUSION: In brief, 6-Gingerol exerts antiapoptotic and anti-inflammatory effects via TRPV1/FAF1 complex dissociation-mediated autophagy during cerebral I/R injury. Therefore, 6-Gingerol may be an effective drug for the treatment of I/R injury.

Y-2 reduces oxidative stress and inflammation and improves neurological function of collagenase-induced intracerebral hemorrhage rats.

Intracerebral hemorrhage (ICH) is a devastating disease, and there is currently no specific pharmacological treatment that can improve clinical outcomes. Y-2 sublingual tablets, each containing 30 mg edaravone and 6 mg (+)-borneol, is undergoing a phase III clinical trial for treatment of ischemic stroke in China. The purpose of the present study is to investigate the efficacy and potential mechanism of Y-2 in a rat model of collagenase IV injection induced ICH. Sublingual administration of Y-2 at the dose of 1, 3 and 6 mg/kg improved ICH-induced sensorimotor dysfunction, alleviated cell death and histopathological change, restored the hippocampal long-term potentiation (LTP), reduced brain edema and maintained blood-brain barrier (BBB) integrality in ICH rats. Further study demonstrated that Y-2 could reduce inflammatory response and oxidative stress by decreasing the levels of myeloperoxidase (MPO), ionized calcium-binding adaptor protein-1 (Iba-1), inflammatory cytokines and oxidative products, inhibit transcription factor nuclear factor-κB (NF-κB) activation, cyclooxygenase-2 (COX-2) and matrix metallopeptidase 9 (MMP-9) expression in brain tissue around in the core regions of hematoma. Importantly, the protective efficacy of Y-2 from ICH-induced injury was superior to edaravone. In conclusion, Y-2 sublingual tablets might be a promising therapeutic agent for the treatment of ICH.

Bakuchiol ameliorates cerebral ischemia-reperfusion injury by modulating NLRP3 inflammasome and Nrf2 signaling.

Cerebral ischemia/reperfusion (I/R) injury is a common cerebrovascular disease with high mortality. Bakuchiol (BAK), extracted from the seeds of psoralea corylifolia, exhibits anti-inflammatory effects on lung, kidney and heart injuries. However, the effect of BAK on brain I/R injury remains elusive. In our study, a cerebral I/R model in mice was established by 1-h middle cerebral artery occlusion and 24-h reperfusion (1-h MCAO/24-h R). Prior to it, mice were gavaged with BAK (2.5 or 5 mg/kg) per day for 5 days. BAK pre-treatment improved neurological deficit, and reduced infarct volume, cerebral edema and neuronal injury in MCAO/R-injured mice. BAK decreased the number of Iba1-immunoreactive cells in the brain, indicating a reduction of microglial activation. BAK also reduced the expressions of NLRP3, ASC, cleaved-caspase-1, IL-1ß and IL-18. BAK triggered Nrf2 nuclear accumulation and elevated HO-1 level. Further, the role of BAK was explored in BV-2 microglia with 3-h oxygen-glucose deprivation/24-h reperfusion (3-h OGD/24-h R). It was found that the functions of BAK in vitro were consistent with those in vivo, as manifested by reduced NLRP3 inflammasome and activated Nrf2 signaling. In addition, BV-2 cells were treated with Brusatol, an Nrf2 inhibitor. Results showed that Brusatol partially reversed the protective effect of BAK on OGD/R-injured BV-2 cells, further confirming that BAK might exhibit its anti-inflammatory property via activating Nrf2 signaling. In short, BAK is more meaningful in improving cerebral ischemic injury through suppressing NLRP3-mediated inflammatory response and activating the Nrf2 signaling pathway.

Association of Isocitrate Dehydrogenase (IDH) Status With Edema to Tumor Ratio and Its Correlation With Immune Infiltration in Glioblastoma.

Purpose: The extent of preoperative peritumoral edema in glioblastoma (GBM) has been negatively correlated with patient outcome. As several ongoing studies are investigating T-cell based immunotherapy in GBM, we conducted this study to assess whether peritumoral edema with potentially increased intracranial pressure, disrupted tissue homeostasis and reduced local blood flow has influence on immune infiltration and affects survival. Methods: A volumetric analysis of preoperative imaging (gadolinium enhanced T1 weighted MRI sequences for tumor size and T2 weighted sequences for extent of edema (including the infiltrative zone, gliosis etc.) was conducted in 144 patients using the Brainlab® software. Immunohistochemical staining was analyzed for lymphocytic- (CD 3+) and myelocytic (CD15+) tumor infiltration. A retrospective analysis of patient-, surgical-, and molecular characteristics was performed using medical records. Results: The edema to tumor ratio was neither associated with progression-free nor overall survival (p=0.90, p=0.74). However, GBM patients displaying IDH-1 wildtype had significantly higher edema to tumor ratio than patients displaying an IDH-1 mutation (p=0.01). Immunohistopathological analysis did not show significant differences in lymphocytic or myelocytic tumor infiltration (p=0.78, p=0.74) between these groups. Conclusion: In our cohort, edema to tumor ratio had no significant correlation with immune infiltration and outcome. However, patients with an IDH-1wildtype GBM had a significantly higher edema to tumor ratio compared to their IDH-1 mutated peer group. Further studies are necessary to elucidate the underlying mechanisms.

Ischemic-time associated reductions in equol monosulfate plasma levels in a mouse model of ischemic stroke: support the existence of a 'brain-gut axis'.

BACKGROUND: Interest is growing in the role played by intestinal flora in the pathogeneses of diseases and in the possibility of treating disease by altering intestinal flora compositions. Recent studies have focused on the relationship between the intestinal microbiome and brain function as proposed by the brain-gut axis hypothesis. OBJECTIVES: To investigate the relation between ischemic stroke and plasma equol monosulfate levels (a soy isoflavone metabolite) in a middle cerebral artery occlusion (MCAO) mouse model. METHODS: Mice (C57BL/6) were subjected to MCAO for various times (30 min to 24 h), and degrees of cerebral damage were assessed using total infarction volumes, brain edema severities and neurological deficit scores. Hematoxylin and eosin and cresyl violet staining were used to observe morphological changes in ischemic brains. Levels of equol monosulfate in plasma and the relationships between these and degree of brain injury were investigated. RESULTS: Infarction volumes, brain edema severity and neurological deficit scores were significantly correlated with ischemic time, and morphological deteriorations of brain neuronal cells also increased with ischemic duration. Equol monosulfate contents were ischemic-time dependently lower in MCAO treated animals than in sham-operated controls. CONCLUSION: Ischemic stroke may time-dependently reduce plasma levels of equol monosulfate by lowering the metabolic rate of equol in MCAO-induced mice. This study provides indirect support of the brain-gut axis hypothesis.

Intravenous methadone causes acute toxic and delayed inflammatory encephalopathy with persistent neurocognitive impairments.

BACKGROUND: The mu-opioid agonist methadone is administered orally and used in opioid detoxification and in the treatment of moderate-to-severe pain. Acute oral methadone-use and -abuse have been associated with inflammatory and toxic central nervous system (CNS) damage in some cases and cognitive deficits can develop in long-term methadone users. In contrast, reports of intravenous methadone adverse effects are rare. CASE PRESENTATION: Here, we report a patient who developed acute bilateral hearing loss, ataxia and paraparesis subsequently to intravenous methadone-abuse. While the patient gradually recovered from these deficits, widespread magnetic resonance imaging changes progressed and delayed-onset encephalopathy with signs of cortical dysfunction persisted. This was associated with changes in the composition of monocyte and natural killer cell subsets in the cerebrospinal fluid. CONCLUSION: This case suggests a potential bi-phasic primary toxic and secondary inflammatory CNS damage induced by intravenous methadone.

Clemastine promotes recovery of neural function and suppresses neuronal apoptosis by restoring balance of pro-inflammatory mediators in an experimental model of intracerebral hemorrhage.

Intracerebral hemorrhage (ICH) represents a common acute cerebrovascular event that imparts high rates of disability. The microglia-mediated inflammatory response is a critical factor in determining cerebral damage post-ICH. Clemastine (CLM) is a histamine receptor H1 (HRH1) antagonist that has been shown to modulate the inflammatory response. However, the effects of CLM on ICH and the underlying mechanism remain to be determined. This investigation reveals that CLM resulted in reduction of cerebral hematoma volume, decreased cerebral edema and lower rates of neuronal apoptosis as well as improved behavioral scores in an acute ICH murine model. CLM treatment was noted to decrease pro-inflammatory effectors and increased anti-inflammatory effectors post-ICH. In addition, CLM reduced the deleterious effects of activated microglia on neurons in a transwell co-culture system. Our findings show that CLM likely mediates its therapeutic effect through inhibition of microglia-induced inflammatory response and apoptosis, thereby enhancing restoration of neuronal function.

Brain transforms natural killer cells that exacerbate brain edema after intracerebral hemorrhage.

Perihematomal edema (PHE) occurs within hours after intracerebral hemorrhage (ICH), leading to secondary injury manifested by impaired blood-brain barrier (BBB) integrity and destruction of adjacent tissue. To dissect the mechanisms underlying PHE formation, we profiled human and mouse perihematomal tissues and identified natural killer (NK) cells as the predominant immune cell subset that outnumbers other infiltrating immune cell types during early stages of ICH. Unbiased clustering of single-cell transcriptional profiles revealed two major NK cell subsets that respectively possess high cytotoxicity or robust chemokine production features in the brain after ICH, distinguishing them from NK cells of the periphery. NK cells exacerbate BBB disruption and brain edema after ICH via cytotoxicity toward cerebral endothelial cells and recruitment of neutrophils that augment focal inflammation. Thus, brain-bound NK cells acquire new features that contribute to PHE formation and neurological deterioration following ICH.

L-3-n-butylphthalide attenuates inflammation response and brain edema in rat intracerebral hemorrhage model.

L-3-n-butylphthalide(NBP), a compound found in Apium graveolens Linn seed extracts, has a therapeutic effect on acute ischemic stroke. The pathological inflammatory pathways and consequent brain edema in intracerebral hemorrhage (ICH) share some similar characteristics with ischemic stroke. We hypothesized that NBP has anti-inflammatory and therapeutic effects on rats with ICH. ICH was induced by an infusion of bacterial collagenase type IV into the unilateral striatum of anesthetized rats. The therapeutic effect of NBP was measured by assessing neurological function, brain water content, blood-brain barrier permeability, and expression of tumor necrosis factor-alpha (TNF-α) and matrix metalloproteinase-9 (MMP-9) around the hematoma 48 hours after surgery. Magnetic resonance imaging was performed 4 and 48 hours after ICH induction, and ICH-induced injured area volumes were measured using T2-weighted images. The NBP treatment group performed better in the neurological function test than the vehicle group. Moreover, in comparison with the vehicle group, NBP group showed a lower expanded hematoma volume, brain water content, blood-brain barrier permeability, and TNF-α/ MMP-9 expression level. Our results indicate that NBP attenuates inflammation and brain edema in rat ICH model. Therefore, our findings also provide a potential therapeutic strategy for the treatment of ICH with NBP.

Ammonia-Induced Brain Edema Requires Macrophage and T Cell Expression of Toll-Like Receptor 9.

BACKGROUND & AIM: Ammonia is central in the pathogenesis of brain edema in acute liver failure (ALF) with infection and systemic inflammation expediting development of intracranial hypertension (ICH). Patients with acetaminophen-induced ALF have increased neutrophil TLR9 expression which can be induced by ammonia. We determined whether ammonia-induced brain edema and immune dysfunction are mediated by TLR9 and if this could be prevented in a TLR9-deficient mouse model. METHODS: Ammonium acetate (NH4-Ac; 4mmol/kg) was injected intraperitoneally in wild type (WT), Tlr9-/- and Lysm-Cre Tlr9fl/fl mice (TLR9 absent in neutrophils and macrophages including Kupffer cells) and compared to controls. Six hours after NH4-Ac injection, intracellular cytokine production was determined in splenic macrophages, CD4+ and CD8+ T cells. Brain water (BW) and total plasma DNA (tDNA) were also measured. The impact of the TLR9 antagonist ODN2088 (50µg/mouse) was evaluated. RESULTS: Following NH4-Ac injection, BW, macrophage and T cell cytokine production increased (P < .0001) in WT but not Tlr9-/- mice (P < .001). ODN2088 inhibited macrophage and T cell cytokine production (P < .05) and prevented an increase in BW (P < .0001). Following NH4-Ac injection, macrophage cytokine production and BW were ameliorated in Lysm-Cre Tlr9fl/fl mice compared to WT mice (P < .05) but there was no difference compared to Tlr9-/- mice. Following NH4-Ac injection, plasma tDNA levels increased in WT and Tlr9-/- mice (P < .05) suggesting that TLR9 may be activated by DNA released from ammonia-stimulated cells. CONCLUSION: Ammonia-induced brain edema requires macrophage and T cell expression of TLR9. Amelioration of brain edema and lymphocyte cytokine production by ODN2088 supports exploration of TLR9 antagonism in early ALF to prevent progression to ICH.

Neuroinflammatory Reactions in the Brain of 1,2-DCE-Intoxicated Mice during Brain Edema.

We previously reported that expression of matrix metalloproteinase-9 (MMP-9) mRNA and protein was upregulated during 1,2-dichloroethane (1,2-DCE) induced brain edema in mice. We also found that the p38 mitogen-activated protein kinase (p38 MAPK) signaling pathway resulted in MMP-9 overexpression and nuclear factor-κB (NF-κB) activation in mice treated with 1,2-DCE. In this study, we further hypothesized that inflammatory reactions mediated by the p38 MAPK/ NF-κB signaling pathway might be involved in MMP-9 overexpression, blood-brain barrier (BBB) disruption and edema formation in the brain of 1,2-DCE-intoxicated mice. Our results revealed that subacute poisoning by 1,2-DCE upregulates protein levels of glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba-1), interleukin-1ß (IL-1ß), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), inducible nitric oxide synthase (iNOS) and p-p65 in mouse brains. Pretreatment with an inhibitor against p38 MAPK attenuates these changes. Moreover, pretreatment with an inhibitor against NF-κB attenuates alterations in brain water content, pathological indications notable in brain edema, as well as mRNA and protein expression on levels of MMP-9, VCAM-1, ICAM-1, iNOS, and IL-1ß, tight junction proteins (TJs), GFAP and Iba-1 in the brain of 1,2-DCE-intoxicated mice. Furthermore, pretreatment with an inhibitor against MMP-9 obstructs the decrease of TJs in the brain of 1,2-DCE-intoxicated mice. Lastly, pretreatment with an antagonist against the IL-1ß receptor also attenuates changes in protein levels of p-p38 MAPK, p-p65, p-IκB, VCAM -1, ICAM-1, IL-1ß, and Iba-1 in the brain of 1,2-DCE-intoxicated-mice. Taken together, findings from the current study indicate that the p38 MAPK/ NF-κB signaling pathway might be involved in the activation of glial cells, and the overproduction of proinflammatory factors, which might induce inflammatory reactions in the brain of 1,2-DCE-intoxicated mice that leads to brain edema.

Akinetic mutism and status epilepticus due to Epstein Barr virus encephalitis.

Neurological complications of Epstein Barr virus (EBV) infection are infrequent and may include occasionally encephalitis, usually with a benign evolution. We here report on an aggressive case of EBV encephalitis in a 14-year-old boy with extensive basal ganglia involvement, and to a lesser degree of brain cortex who presented atypically with akinetic mutism and non-convulsive status epilepticus, requiring intensive care but showed a favorable outcome. EBV encephalitis is uncommon and its best management is unclear. Its pathophysiology is not well understood but could include autoimmunity. Onconeuronal and synaptic antibodies were negative in serum and cerebrospinal fluid, including the dopamine D2 receptor. To the best of our knowledge, this is the first report to evaluate antibodies to D2 receptors in EBV encephalitis. Corticosteroid therapy is usually recommended but the use of acyclovir is controversial. Intensive care is required in severe cases to assure a favorable outcome.

Perilesional edema in brain metastases: potential causes and implications for treatment with immune therapy.

BACKGROUND: Little is known about tumor-associated vasogenic edema in brain metastasis, yet it causes significant morbidity and mortality. Our purpose was to characterize edema in patients treated with anti-PD-1 and to study potential causes of vessel leakage in humans and in pre-clinical models. METHODS: We analyzed tumor and edema volume in 18 non-small cell lung (NSCLC) and 18 melanoma patients with untreated brain metastases treated with pembrolizumab on a phase II clinical trial. Melanoma brain metastases were stained with anti-CD34 to assess vessel density and its association with edema. We employed an in vitro model of the blood-brain barrier using short-term cultures from melanoma brain and extracranial metastases to determine tight junction resistance as a measure of vessel leakiness. RESULTS: Edema volumes are similar in NSCLC and melanoma brain metastases. While larger tumors tended to have more edema, the correlation was weak (R2 = 0.30). Patients responding to pembrolizumab had concurrent shrinkage of edema volume and vice versa (R2 = 0.81). Vessel density was independent of the degree of edema (R2 = 0.037). Melanoma brain metastasis cells in culture caused loss of tight junction resistance in an in vitro blood-brain barrier model system in some cases, whereas extracerebral cell cultures did not. CONCLUSIONS: Edema itself should not preclude using anti-PD-1 with caution, as sensitive tumors have resultant decreases in edema, and anti-PD-1 itself does not exacerbate edema in sensitive tumors. Additional factors aside from tumor mass effect and vessel density cause perilesional edema. Melanoma cells themselves can cause decline in tight junction resistance in a system void of immune cells, suggesting they secrete factors that cause leakiness, which might be harnessed for pharmacologic targeting in patients with significant perilesional edema.

Emerging therapeutic targets associated with the immune system in patients with intracerebral haemorrhage (ICH): From mechanisms to translation.

Intracranial haemorrhage (ICH) is a life-threatening type of stroke with high mortality, morbidity, and recurrence rates. However, no effective treatment has been established to improve functional outcomes in patients with ICH to date. Strategies targeting secondary brain injury are of great interest in both experimental and translational studies. The immune system is increasingly considered to be a crucial contributor to ICH-induced brain injury because it participates in multiple phases of ICH, from the early vascular rupture events to brain recovery. Various pathobiological processes that contribute to secondary brain injury closely interact with the immune system, such as brain oedema, neuroinflammation, and neuronal damage. Hence, we summarize the immune response to ICH and recent progress in treatments targeting the immune system in this review. The emerging therapeutic strategies that target the immune system after ICH are a particular focus and have been summarized.

The Role of Mast Cells in Stroke.

Mast cells (MCs) are densely granulated perivascular resident cells of hematopoietic origin. Through the release of preformed mediators stored in their granules and newly synthesized molecules, they are able to initiate, modulate, and prolong the immune response upon activation. Their presence in the central nervous system (CNS) has been documented for more than a century. Over the years, MCs have been associated with various neuroinflammatory conditions of CNS, including stroke. They can exacerbate CNS damage in models of ischemic and hemorrhagic stroke by amplifying the inflammatory responses and promoting brain-blood barrier disruption, brain edema, extravasation, and hemorrhage. Here, we review the role of these peculiar cells in the pathophysiology of stroke, in both immature and adult brain. Further, we discuss the role of MCs as potential targets for the treatment of stroke and the compounds potentially active as MCs modulators.

In diabetic ketoacidosis brain injury including cerebral oedema and infarction is caused by interleukin-1.

BACKGROUND: Brain injury in diabetic ketoacidosis (DKA) is common but under recognized and affects up to 54% of patients with this complication. It's manifestations include cerebral oedema (CE) and cerebral infarction (CI). The etiology of CE in DKA has up to the present time been uncertain. Practical management had been guided by the assumption that rapid osmotic shifts due to rapid correction of hypovolemia and reduction of plasma glucose could cause a shift of water into the cells. The osmotic effect of glucose can cause inflammation by activation of inflammasomes. Recently it has been recognized that the body is in a pro-inflammatory state during DKA involving interleukin-1 production by inflammasomes. Interleukin-1 has been involved in the pathogenesis of cerebral oedema and CI. HYPOTHESIS: In diabetic ketoacidosis brain injury including cerebral oedema and infarction is caused by interleukin-1. CONFIRMATION OF HYPOTHESIS AND IMPLICATIONS: Inflammasome activity could be quantified in peripheral blood mononuclear cells and in patients with and without clinical and/or subclinical CE and/or stroke or features of cerebral ischemia on MRI. Surrogates of brain injury in peripheral blood like neuron specific enolase could be measured and correlated with inflammasome activity. Interleukin-1 receptor antagonists and inflammasome inhibitors including telmisartan could be assessed in their effect on MRI changes consistent with CE or CI in patients with DKA in randomised placebo-controlled trials.

Osteopontin attenuates inflammation via JAK2/STAT1 pathway in hyperglycemic rats after intracerebral hemorrhage.

Acute intracerebral hemorrhage (ICH) complicated by hyperglycemia is associated with aggravation of post-stroke inflammation, leading to exacerbation of brain edema and predicting poor neurological outcomes and higher mortality of patients. Osteopontin (OPN) is a neuroprotective glycoprotein, which is able to attenuate brain injury induced by hemorrhagic stroke. In the current study we investigated whether OPN will decrease the inflammatory post-ICH response as well as attenuate brain edema and neurological deficits in hyperglycemic rats. We employed a collagenase model of ICH on male Sprague-Dawley rats (n = 148) rats and 50% of Dextrose was injected intraperitoneally (i.p) 3 h after ICH (ICH + HG). Intranasal administration of recombinant OPN (rOPN) was performed 1 h after ICH. The development of brain injury was evaluated by brain water content (BWC) and neurological deficits, western blot and immunohistochemistry study. Small interfering ribonucleic acid (siRNA) for integrin-ß1 receptor and a JAK2 agonist, Coumermycin A1 (C-A1), were used for detailed investigation of the molecular pathway. The administration of OPN (3 µg) significantly improved neurobehavior and increased expression of OPN and integrin-ß1 receptor in the brain followed with decrease of neutrophil infiltration, JAK2, STAT1, TNF-a, IL-1b, MMP-9 and brain edema in the ICH + HG + OPN rats compared with ICH + HG rats. The effects of OPN were reversed by the intervention of intergrin-ß1 siRNA and C-A1. In conclusion, rOPN attenuated ICH-induced brain inflammation in hyperglycemic rats, leading to attenuation of brain edema and improving neurological functions. Effects of rOPN were mediated at least partly by integrin-ß1 induced inhibition of JAK2/STAT1 pathway.

HMGB1 a-Box Reverses Brain Edema and Deterioration of Neurological Function in a Traumatic Brain Injury Mouse Model.

BACKGROUND/AIMS: Traumatic brain injury (TBI) is a complex neurological injury in young adults lacking effective treatment. Emerging evidences suggest that inflammation contributes to the secondary brain injury following TBI, including breakdown of the blood brain barrier (BBB), subsequent edema and neurological deterioration. High mobility group box-1 (HMGB1) has been identified as a key cytokine in the inflammation reaction following TBI. Here, we investigated the therapeutic efficacy of HMGB1 A-box fragment, an antagonist competing with full-length HMGB1 for receptor binding, against TBI. METHODS: TBI was induced by controlled cortical impact (CCI) in adult male mice. HMGB1 A-box fragment was given intravenously at 2 mg/kg/day for 3 days after CCI. HMGB1 A-box-treated CCI mice were compared with saline-treated CCI mice and sham mice in terms of BBB disruption evaluated by Evan's blue extravasation, brain edema by brain water content, cell death by propidium iodide staining, inflammation by Western blot and ELISA assay for cytokine productions, as well as neurological functions by the modified Neurological Severity Score, wire grip and beam walking tests. RESULTS: HMGB1 A-box reversed brain damages in the mice following TBI. It significantly reduced brain edema by protecting integrity of the BBB, ameliorated cell degeneration, and decreased expression of pro-inflammatory cytokines released in injured brain after TBI. These cellular and molecular effects were accompanied by improved behavioral performance in TBI mice. Notably, HMGB1 A-box blocked IL-1ß-induced HMGB1 release, and preferentially attenuated TLR4, Myd88 and P65 in astrocyte cultures. CONCLUSION: Our data suggest that HMGB1 is involved in CCI-induced TBI, which can be inhibited by HMGB1 A-box fragment. Therefore, HMGB1 A-box fragment may have therapeutic potential for the secondary brain damages in TBI.

Neutrophil-Lymphocyte Ratio and Perihematomal Edema Growth in Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE: Although preclinical studies have shown inflammation to mediate perihematomal edema (PHE) after intracerebral hemorrhage, clinical data are lacking. Leukocyte count, often used to gauge serum inflammation, has been correlated with poor outcome but its relationship with PHE remains unknown. Our aim was to test the hypothesis that leukocyte count is associated with PHE growth. METHODS: We included patients with intracerebral hemorrhage admitted to a tertiary-care stroke center between 2011 and 2015. The primary outcome was absolute PHE growth during 24 hours, calculated using semiautomated planimetry. Linear regression models were constructed to study the relationship between absolute and differential leukocyte counts (monocyte count and neutrophil-lymphocyte ratio) and 24-hour PHE growth. RESULTS: A total of 153 patients were included. Median hematoma and PHE volumes at baseline were 14.4 (interquartile range, 6.3-36.3) and 14.0 (interquartile range, 5.9-27.8), respectively. In linear regression analysis adjusted for demographics and intracerebral hemorrhage characteristics, absolute leukocyte count was not associated with PHE growth (ß, 0.07; standard error, 0.15; P=0.09). In secondary analyses, neutrophil-lymphocyte ratio was correlated with PHE growth (ß, 0.22; standard error, 0.08; P=0.005). CONCLUSIONS: Higher neutrophil-lymphocyte ratio is independently associated with PHE growth. This suggests that PHE growth can be predicted using differential leukocyte counts on admission.

Colony stimulating factor 1 receptor inhibition eliminates microglia and attenuates brain injury after intracerebral hemorrhage.

Microglia are the first responders to intracerebral hemorrhage, but their precise role in intracerebral hemorrhage remains to be defined. Microglia are the only type of brain cells expressing the colony-stimulating factor 1 receptor, a key regulator for myeloid lineage cells. Here, we determined the effects of a colony-stimulating factor 1 receptor inhibitor (PLX3397) on microglia and the outcome in the context of experimental mouse intracerebral hemorrhage. We show that PLX3397 effectively depleted microglia, and the depletion of microglia was sustained after intracerebral hemorrhage. Importantly, colony-stimulating factor 1 receptor inhibition attenuated neurodeficits and brain edema in two experimental models of intracerebral hemorrhage induced by injection of collagenase or autologous blood. The benefit of colony-stimulating factor 1 receptor inhibition was associated with reduced leukocyte infiltration in the brain and improved blood-brain barrier integrity after intracerebral hemorrhage, and each observation was independent of lesion size or hematoma volume. These results demonstrate that suppression of colony-stimulating factor 1 receptor signaling ablates microglia and confers protection after intracerebral hemorrhage.