Unconjugated bilirubin contributes to early inflammation and edema after intracerebral hemorrhage

Top-Down and Bottom-Up Mechanisms of Motor Recovery Poststroke

Stroke remains a leading cause of disability. Motor recovery requires the interaction of top-down and bottom-up mechanisms, which reinforce each other. Injury to the brain initiates a biphasic neuroimmune process, which opens a window for spontaneous recovery during which the brain is particularly sensitive to activity. Physical activity during this sensitive period can lead to rapid recovery by potentiating anti-inflammatory and neuroplastic processes. On the other hand, lack of physical activity can lead to early closure of the sensitive period and downstream changes in muscles, such as sarcopenia, muscle stiffness, and reduced cardiovascular capacity, and blood flow that impede recovery.

Role of Inflammatory Processes in Hemorrhagic Stroke

Hemorrhagic stroke is the deadliest form of stroke and includes the subtypes of intracerebral hemorrhage and subarachnoid hemorrhage. A common cause of hemorrhagic stroke in older individuals is cerebral amyloid angiopathy. Intracerebral hemorrhage and subarachnoid hemorrhage both lead to the rapid collection of blood in the central nervous system and generate inflammatory immune responses that involve both brain resident and infiltrating immune cells. These responses are complex and can contribute to both tissue recovery and tissue injury. Despite the interconnectedness of these major subtypes of hemorrhagic stroke, few reviews have discussed them collectively. The present review provides an update on inflammatory processes that occur in response to intracerebral hemorrhage and subarachnoid hemorrhage, and the role of inflammation in the pathophysiology of cerebral amyloid angiopathy-related hemorrhage. The goal is to highlight inflammatory processes that underlie disease pathology and recovery. We aim to discuss recent advances in our understanding of these conditions and identify gaps in knowledge with the potential to develop effective therapeutic strategies.

Bile duct ligation increased dopamine levels in the cerebral cortex of rats partly due to induction of tyrosine hydroxylase

BACKGROUND AND PURPOSE

Liver failure is associated with psychiatric alterations, partly resulting from the increased brain dopamine levels. We investigated the relationship between increased dopamine levels and mental abnormalities using bile duct ligation (BDL) rats and the mechanism by which liver failure increased dopamine levels in SH-SY5Y cells. Behavioural tests were carried out on day 13 and 27 following BDL, along with measurements of dopamine and metabolites, expressions of enzymes and transporters related to dopamine metabolism, and its transport into the cortex and the hippocampus. SH-SY5Y cells were used to investigate whether NH₄ Cl, bile acids and bilirubin affected expression of tyrosine hydroxylase or not. Tyrosine hydroxylase (TH) expression in SH-SY5Y cells co-incubated with bilirubin and signal pathway inhibitors was measured.

KEY RESULTS

Open-field test results demonstrated BDL rats showed anxiety-like behaviour, accompanied by increased dopamine levels and expression of TH protein in the cortex. Membrane bound long form (MB)-COMT, slightly but significantly decreased. SH-SY5Y cells indicated that increased bilirubin levels was a factor in inducing TH expression. Both inhibitor of NF-κB pathway BAY 11-7082 and silencing NF-κB p65 reversed bilirubin-induced upregulation of TH protein. NF-κB activator TNF-α increased expression of TH protein. Roles of bilirubin in increases of TH protein expressions and dopamine levels were measured using hyperbilirubinemia rats. Anxiety-like behaviour, was associated with increased dopamine levels and TH protein expressions in hyperbilirubinemia rats.

CONCLUSION AND IMPLICATIONS

BDL significantly increased dopamine levels in rat cortex partly due to bilirubin-mediated TH induction. Increased bilirubin induced TH expression via activating NF-κB signalling pathway.

A New Product of Bilirubin Degradation by H2O2 and Its Formation in Activated Neutrophils and in an Inflammatory Mouse Model

Bilirubin (BR) is a tetrapyrrolic compound stemming from heme catabolism with diverse physiological functions. It can be oxidized by H₂O₂ to form several degradation products, some of which have been detected in vivo and may contribute to the pathogenesis of certain diseases. However, the oxidative degradation of BR is complex and the conditions that BR degradation occurs pathophysiologically remain obscure. Neutrophils are known to generate large amounts of reactive oxygen species, including H₂O₂, upon activation and they are mobilized to inflammatory sites; therefore, we hypothesized that activated neutrophils could cause BR degradation, which could occur at inflammatory sites. In the present study, we investigated BR degradation by H₂O₂ and identified hematinic acid (BHP1) and a new product BHP2, whose structure was characterized as 2,5-diformyl-4-methyl-1H-pyrrole-3-propanoic acid. An LC-MS/MS method for the quantitation of the two compounds was then established. Using the LC-MS/MS method, we observed the concentration-dependent formation of BHP1 and BHP2 in mouse neutrophils incubated with 10 and 30 μM of BR with the yields being 16 ± 3.2 and 31 ± 5.9 pmol/10⁶ cells for BHP1, and 25 ± 4.4 and 71 ± 26 pmol/10⁶ cells for BHP2, respectively. After adding phorbol 12-myristate 13-acetate, a neutrophil agonist, to 30 μM of BR-treated cells, the BHP1 yield increased to 43 ± 6.6 pmol/10⁶ cells, whereas the BHP2 one decreased to 47 ± 9.2 pmol/10⁶ cells. The two products were also detected in hemorrhagic skins of mice with dermal inflammation and hemorrhage at levels of 4.5 ± 1.9 and 0.18 ± 0.10 nmol/g tissue, respectively, which were significantly higher than those in the non-hemorrhagic skins. BHP2 was neurotoxic starting at 0.10 μM but BHP1 was not, as assessed using Caenorhabditis elegans as the animal model. Neutrophil-mediated BR degradation may be a universally pathophysiological process in inflammation and can be particularly important under pathological conditions concerning hemorrhage.

Minimally Invasive Surgery for ICH Evacuation Combined With Deferoxamine Treatment Increased Perihematomal Claudin-5 and ZO-1 Expression Levels and Decreased BBB Permeability in Rabbits

Objective

To investigate the role of minimally invasive surgery (MIS) in intracerebral hemorrhage (ICH) evacuation combined with deferoxamine (DFX) treatment on perihematomal tight junction protein (claudin-5 and ZO-1) expression levels and blood-brain barrier (BBB) permeability in rabbits.

Methods

We randomly assigned 65 male rabbits (weight: 1.9–2.6 kg) to a normal control group (NC group, 13 rabbits), hemorrhage model group (HM group, 13), DFX treatment group (DFX group, 13 rabbits), MIS group (MIS group, 13 rabbits), or MIS combined with DFX treatment group (MIS + DFX group, 13 rabbits). ICH was established in all of the groups except the NC group. MIS was performed to evacuate the hematoma 6 h after the ICH model was created in the MIS and MIS + DFX groups. The DFX and MIS + DFX groups were treated with DFX (100 mg/kg, dissolved in 2 mL of 0.9% saline solution, administered intramuscularly) at 2 h, and then every 12 h for 7 d. The same dose of 0.9% saline solution was administered to the NC, HM, and MIS groups at the same time points. Sixty-five rabbits were divided into 5 groups, and 13 rabbits in each group. Neurological deficit (i.e., Purdy's score) was recorded in all rabbits before euthanasia (N total = 65). In each group, 2 rabbits were used for iron concentration measurement (N total = 10), 2 rabbits were used for brain water content measurement (N total = 10), 3 rabbits were used for BBB permeability measurement (N total = 15), 3 rabbits were used for claudin-5, ZO-1 expression detection by Western Blotting (N total = 15), and 3 rabbits were used for claudin-5, ZO-1 mRNA detection by real-time PCR (N total = 15). On day 7, the rabbits were sacrificed and the perihematomal brain tissue was harvested to test the iron concentration, brain water content (BWC), tight junction proteins (claudin-5 and ZO-1) expression, and BBB permeability.

Results

Purdy's score, iron concentration, and BWC were lower in the MIS and MIS + DFX groups compared to the HM and DFX groups. The MIS + DFX group showed a significant decrease in these indicators. The use of MIS to evacuate the hematoma led to increased expression levels of claudin-5 and ZO-1, as well as decreased BBB permeability. The MIS + DFX group exhibited a remarkable increase in claudin-5 and ZO-1 expression levels and a significant decrease in BBB permeability.

Conclusions

MIS combined with DFX treatment could increase the expression levels of perihematomal tight junction proteins (claudin-5 and ZO-1) expression, reduce BBB permeability, and improve the neurological function. MIS combined with DFX treatment may also prevent secondary brain damage following ICH.

Temporal metabolomic alteration in rat brains of experimental intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is the top lethal and disabling form of stroke. The pathophysiology of ICH is not fully understood yet. Metabolites are indicators and regulators of cellular processes. However, the overall brain metabolic pattern and the temporal alterations after ICH remain unknown.

METHODS

A total of 40 male rats were randomly assigned to sham group and ICH group. ICH was induced by collagenase Ⅶ. Body weight was assessed. Neurological deficits were evaluated by modified neurological severity score. Then, the perihematomal brain tissues were collected for metabolites detection using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). The metabolic profiles were displayed by principal component analysis (PCA), partial least-squares-discriminant analysis (PLS-DA) and cluster analysis. The significant differential metabolites were screened by fold change > 2.0, the false discovery rate (FDR) < 0.05 and Variable Importance of Projection (VIP) > 1. Next, the relevant metabolic pathways were discerned by MetaboAnalyst website. A metabolite-protein interaction network was subsequentially constructed to further annotate the function of differential metabolites.

RESULTS

Rats suffered from compromised body weight increasement and impaired neurological function. The metabolomics profiles of brain tissues in the post-ICH rats were markedly different from those in the sham group on days 3 and 14. Thirty-four metabolites (bilirubin, uric acid, 6-Methylnicotinamide et al.) were abnormally upregulated in the acute stage, while 27 metabolites were disturbed in the recovery stage, including bilirubin, uric acid, and histamine et al. Seven and three metabolic pathways altered in the acute and recovery stage, respectively. Metabolite-protein interaction analysis revealed that the disturbed metabolites may participate in ICH pathophysiology by altering amino acid metabolism, peroxisome proliferators-activated receptor signaling pathway, fatty acid metabolism and urea cycle in the acute stage, while influencing amino acid metabolism, urea cycle and peroxisome in the recovery stage.

CONCLUSIONS

Our study mapped the pathological metabolomics profiles of the post-ICH rat brains in the acute and recovery phases. This work will assist in discovering novel therapeutic targets and treatments for ICH.

The Chemical Basis of Intracerebral Hemorrhage and Cell Toxicity With Contributions From Eryptosis and Ferroptosis

Intracerebral hemorrhage (ICH) is a particularly devastating event both because of the direct injury from space-occupying blood to the sequelae of the brain exposed to free blood components from which it is normally protected. Not surprisingly, the usual metabolic and energy pathways are overwhelmed in this situation. In this review article, we detail the complexity of red blood cell degradation, the contribution of eryptosis leading to hemoglobin breakdown into its constituents, the participants in that process, and the points at which injury can be propagated such as elaboration of toxic radicals through the metabolism of the breakdown products. Two prominent products of this breakdown sequence, hemin, and iron, induce a variety of pathologies including free radical damage and DNA breakage, which appear to include events independent from typical oxidative DNA injury. As a result of this confluence of damaging elements, multiple pathways of injury, cell death, and survival are likely engaged including ferroptosis (which may be the same as oxytosis but viewed from a different perspective) and senescence, suggesting that targeting any single cause will likely not be a sufficient strategy to maximally improve outcome. Combination therapies in addition to safe methods to reduce blood burden should be pursued.

The Role of Bilirubin and the Other "Yellow Players" in Neurodegenerative Diseases

Bilirubin is a yellow endogenous derivate of the heme catabolism. Since the 1980s, it has been recognized as one of the most potent antioxidants in nature, able to counteract 10,000× higher intracellular concentrations of H2O2. In the recent years, not only bilirubin, but also its precursor biliverdin, and the enzymes involved in their productions (namely heme oxygenase and biliverdin reductase; altogether the "yellow players"-YPs) have been recognized playing a protective role in diseases characterized by a chronic prooxidant status. Based on that, there is an ongoing effort in inducing their activity as a therapeutic option. Nevertheless, the understanding of their specific contributions to pathological conditions of the central nervous system (CNS) and their role in these diseases are limited. In this review, we will focus on the most recent evidence linking the role of the YPs specifically to neurodegenerative and neurological conditions. Both the protective, as well as potentially worsening effects of the YP's activity will be discussed.

Bilirubin: a novel predictor of hemorrhagic transformation and symptomatic intracranial hemorrhage after mechanical thrombectomy

BACKGROUND AND PURPOSE

The role of bilirubin in patients treated with mechanical thrombectomy (MT) is unknown. We investigated the relationship between admission bilirubin levels and hemorrhagic complication in acute ischemic stroke (AIS) patients treated with MT and detailed the roles of direct bilirubin (DB), indirect bilirubin (IDB), and total bilirubin (TB).

METHODS

Consecutive AIS patients treated with MT were enrolled from two stroke centers. Outcome measures included hemorrhagic transformation (HT) and symptomatic intracranial hemorrhage (sICH) within 48 h. An independent association of bilirubin with outcomes was identified by multivariate logistic regression analysis. The accuracies of bilirubin in predicting outcome were evaluated using receiver operating characteristic curve analysis.

RESULTS

Of the 153 enrolled patients, 64 (41.8%) were diagnosed with HT, of which 28 (18.3%) had sICH. In univariate analyses, DB, IDB, and TB were higher in patients with HT and sICH than in patients without. After adjustment for potential confounders, DB (odds ratio [OR], 1.364; 95% confidence interval [CI], 1.133-1.641; p = 0.001), IDB (OR, 1.143; 95% CI, 1.052-1.242; p = 0.002), and TB (OR, 1.106; 95% CI, 1.041-1.175; p = 0.001) were independently associated with HT. IDB (OR, 1.177; 95% CI, 1.064-1.303; p = 0.002) and TB (OR, 1.102; 95% CI, 1.027-1.182; p = 0.007) were independently associated with sICH. Receiver operating characteristic curve analysis showed no significant difference between the three indicators of predicting HT and sICH.

CONCLUSIONS

Elevated admission bilirubin is an independent predictor of HT and sICH in AIS patients treated with MT.

Bilirubin, urobilinogen, pancreas elastase and bile acid in drain fluid. The GBUP-study: Analysis of biomarkers for a colorectal anastomotic leakage

Purpose

A colorectal anastomotic leakage (CAL) is a major complication after colorectal surgery and leads to high rates of morbidity and prolonged hospital stay. The study aims to evaluate the benefit of using bilirubin, urobilinogen, pancreas elastase and bile acid in the drain fluid (DF) as a predictive marker for the CAL.

Methods

From June 2015 to October 2017 100 patients, who underwent left hemicolectomy (LH), sigma resection (SR), high anterior resection (HAR), low anterior resection (LAR) or reversal of Hartmann's Procedure (ROHP) were included in this monocentric non-randomized prospective clinical trial. During the first four postoperative days (POD) the concentration of bilirubin, urobilinogen, pancreas elastase and bile acid in the DF was measured.

Results

In total 100 patients were recruited. 17 were excluded due to intraoperative decisions to conduct a protective stoma. 6 patients had a CAL. The patients of the control group (n = 77) and the patients who suffered from a CAL (n = 6) had no increased concentration of urobilinogen and pancreas elastase in the DF. The concentration of bile acid in the DF of the patients who suffered from a CAL differed from those of the control group on the 4th POD (p = 0.055).

The concentration of bilirubin in the DF of the patients who suffered from a CAL significantly differed from those of the control group on the 1st POD (p = 0.031) and on the 3rd POD (p = 0.041).

Conclusion

Bilirubin and bile acid in the DF may function as a predictive marker for a CAL.

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Bilirubin in the DF may function as a predictive marker for a CAL.

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Bile acid in the DF may function as a predictive marker for a CAL.

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Pancreas elastase in the DF did not seem to be a predictive marker for a CAL.

Biliverdin reductase and bilirubin in hepatic disease

The buildup of fat in the liver (hepatic steatosis) is the first step in a series of incidents that may drive hepatic disease. Obesity is the leading cause of nonalcoholic fatty liver disease (NAFLD), in which hepatic steatosis progresses to liver disease. Chronic alcohol exposure also induces fat accumulation in the liver and shares numerous similarities to obesity-induced NAFLD. Regardless of whether hepatic steatosis is due to obesity or long-term alcohol use, it still may lead to hepatic fibrosis, cirrhosis, or possibly hepatocellular carcinoma. The antioxidant bilirubin and the enzyme that generates it, biliverdin reductase A (BVRA), are components of the heme catabolic pathway that have been shown to reduce hepatic steatosis. This review discusses the roles for bilirubin and BVRA in the prevention of steatosis, their functions in the later stages of liver disease, and their potential therapeutic application.

Bliverdin reductase-A improves neurological function in a germinal matrix hemorrhage rat model

Germinal matrix hemorrhage is induced by stereotaxic injection of collagenase into the germinal matrix of P7 Sprague-Dawley rats. Hemoglobin assay, western blot, immunofluorescence and neurobehavioral tests were used to test the effects of BLVRA on hematoma resolution and anti-inflammatory response. We showed that BLVRA triggered a signaling cascade that ameliorated post-hemorrhagic neurological deficits in both short-term and long-term neurobehavioral tests in a GMH rat model. Specifically, BLVRA inhibited toll-like receptor 4 (TLR4) expression by translocating to the nucleus in an endothelial nitric oxide (eNOS)/nitric oxide (NO)-dependent manner. BLVRA also induced the upregulation of CD36 scavenger receptor level in microglia/microphages, of which the prominent role is to enhance hematoma resolution. However, the beneficial effects of BLVRA were abolished with the knockdown of eNOS, indicating that the eNOS/NO system is an important downstream factor of BLVRA. Our results demonstrate a mechanism of BLVRA modulating hematoma resolution and suppressing inflammation through eNOS/NO/TLR4 pathway in the GMH rat model.

Anti-inflammatory effects of Simvastatin in patients with acute intracerebral hemorrhage in an intensive care unit

Intracerebral hemorrhage is one of the most common types of cerebrovascular disease in humans and often causes paralysis, a vegetative state and even death. Patients with acute intracerebral hemorrhage are frequently monitored in intensive care units (ICUs). Spontaneous intracerebral hemorrhage is associated with a higher rate of mortality and morbidity than other intracephalic diseases. The expression levels of inflammatory factors have important roles in inflammatory responses indicative of changes in a patient's condition and are therefore important in the monitoring and treatment of affected patients at the ICU as well as the development of therapeutic strategies for acute cerebral hemorrhage. The present study investigated the anti-inflammatory effects of Simvastatin in patients with acute intracerebral hemorrhage at an ICU, and inflammatory factors and cellular changes were systematically analyzed. The plasma concentrations of inflammatory factors, including interleukin (IL)-4, IL-6, IL-8 and IL-10, were evaluated by ELISAs. The plasma concentrations of inflammatory cellular changes were detected by using flow cytometry. The results demonstrated that after Simvastatin treatment of patients with acute cerebral hemorrhage at the ICU, the plasma concentrations of IL-4, IL-6, IL-8 and IL-10 were downregulated compared with those in placebo-treated controls. In addition, Simvastatin treatment at the ICU decreased lymphocytes, granulocytes and mononuclear cells in patients with acute cerebral hemorrhage. The levels of inflammatory factors were associated with brain edema in patients with acute cerebral hemorrhage treated at the ICU. In addition, the amount of bleeding was reduced in parallel with the inflammatory cell plasma concentration of lymphocytes, granulocytes and mononuclear cells. Importantly, Simvastatin treatment produced beneficial outcomes by improving brain edema and reducing the amount of bleeding. In conclusion, the present study demonstrated the efficacy of Simvastatin in treating acute intracerebral hemorrhage and evidenced the association between inflammatory responses and the progress of affected patients at the ICU, thereby providing insight for applying effective therapies for patients with acute intracerebral hemorrhage.

Platelet-Derived Growth Factor Receptor-β Regulates Vascular Smooth Muscle Cell Phenotypic Transformation and Neuroinflammation After Intracerebral Hemorrhage in Mice

OBJECTIVE

Platelet-derived growth factor-BB activates platelet-derived growth factor receptor-β and promotes vascular smooth muscle cell phenotypic transformation. Elevated levels of non-muscle myosin IIB (SMemb) are found in secretory smooth muscle cells along with inflammatory mediators, such as intercellular adhesion molecule-1, which can amplify neutrophil infiltration into the brain. In the present study, we investigated the role of platelet-derived growth factor-BB/platelet-derived growth factor receptor-β following intracerebral hemorrhage-induced brain injury in mice, with emphasis on its ability to promote vascular smooth muscle cell phenotypic transformation followed by increased intercellular adhesion molecule-1 expression and elevated neutrophil infiltration in the vicinity of the hematoma. We also determined the extent to which plasmin from the hematoma influences the platelet-derived growth factor-BB/platelet-derived growth factor receptor-β system subsequent to intracerebral hemorrhage.

DESIGN

Controlled in vivo laboratory study.

SETTING

Animal research laboratory.

SUBJECTS

One hundred and fifty six eight-week-old male CD1 mice.

INTERVENTIONS

Brain injury was induced by autologous arterial blood or plasmin injection into mouse brains. Small interfering RNA targeting platelet-derived growth factor receptor-β was administered 24 hours before intracerebral hemorrhage. A platelet-derived growth factor receptor antagonist, Gleevec, was administered following intracerebral hemorrhage. A mitogen-activated protein kinase-activated protein kinase 2 inhibitor (KKKALNRQLGVAA) was delivered with platelet-derived growth factor-BB in naïve animals. Platelet-derived growth factor-BB was injected with a plasmin inhibitor (ε-aminocaproic acid) in intracerebral hemorrhage mice. Plasmin-injected mice were given platelet-derived growth factor receptor-β small interfering RNA 24 hours before the operation. Neurological deficits, brain edema, western blots, and immunofluorescence were evaluated.

MEASUREMENTS AND MAIN RESULTS

Platelet-derived growth factor receptor-β small interfering RNA attenuated SMemb and intercellular adhesion molecule-1 expression and neutrophil infiltration at 24 hours post injury and reduced neurological deficits and brain edema at 24 and 72 hours following intracerebral hemorrhage. The platelet-derived growth factor receptor antagonist, Gleevec, reduced SMemb and intercellular adhesion molecule-1 expression. Platelet-derived growth factor receptor-β activation led to increased expression of intercellular adhesion molecule-1 and was reversed by KKKALNRQLGVAA in naïve mice. Plasmin inhibition suppressed platelet-derived growth factor receptor-β activation and neutrophil infiltration, whereas exogenous platelet-derived growth factor-BB increased platelet-derived growth factor receptor-β activation, regardless of plasmin inhibition. Platelet-derived growth factor receptor-β small interfering RNA decreased the expression of intercellular adhesion molecule-1 by plasmin injection.

CONCLUSION

The platelet-derived growth factor-BB/platelet-derived growth factor receptor-β system contributes to neuroinflammation through vascular smooth muscle cell phenotypic transformation near the hematoma via the p38 mitogen-activated protein kinase/mitogen-activated protein kinase-activated protein kinase 2 pathway following intracerebral hemorrhage. Plasmin is hypothesized to be upstream of the proposed neuroinflammatory system. The therapeutic intervention targeting the platelet-derived growth factor-BB/platelet-derived growth factor receptor-β is a novel strategy to prevent plasmin-induced brain injury following intracerebral hemorrhage.

Neuroprotective Effect of Erythropoietin on Phenylhydrazine-Induced Hemolytic Hyperbilirubinemia in Neonatal Rats

Neonatal unconjugated hyperbilirubinemia might cause severe bilirubin neurotoxicity in especially hemolytic conditions. The study aimed to elucidate the potential neuroprotective effects of erythropoietin (EPO) in hemolysis-induced hyperbilirubinemia. In newborn rats, hyperbilirubinemia secondary to hemolysis was induced by injecting with phenylhydrazine hydrochloride (PHZ) and rats were injected with either vehicle or EPO. At 54th hour of the PHZ injection, rats were decapitated. Serum levels of TNF-α, IL-1β, IL-10, brain-derived neurotrophic factor (BDNF) and S100-B and brain malondialdehyde, glutathione levels and myeloperoxidase activities were measured. TUNEL staining and NF-κB expression were evaluated. As compared to control pups, in vehicle-treated PHZ group, TNF-α and IL-1β levels, malondialdehyde level and myeloperoxidase activity were increased with concomitant decreases in IL-10 and glutathione. All EPO regimens reversed PHZ-induced alterations in IL-10, TNF-α, malondialdehyde and glutathione levels. Three-day-treatment abolished increases in myeloperoxidase activity and IL-1β levels, while BDNF and S100-B were elevated. Increased TUNEL (+) cells and NF-κB expressions in the brain of PHZ group were reduced in the 3-day-treated group. EPO exerted anti-inflammatory effects on PHZ-induced neural damage in newborn rats, while the neuroprotection was more obvious when the treatments were repeated successively. The results suggest that EPO treatment may have a therapeutic potential in supporting neuroplasticity in the hyperbilirubinemic neonates.

Arctigenin Treatment Protects against Brain Damage through an Anti-Inflammatory and Anti-Apoptotic Mechanism after Needle Insertion

Convection enhanced delivery (CED) infuses drugs directly into brain tissue. Needle insertion is required and results in a stab wound injury (SWI). Subsequent secondary injury involves the release of inflammatory and apoptotic cytokines, which have dramatic consequences on the integrity of damaged tissue, leading to the evolution of a pericontusional-damaged area minutes to days after in the initial injury. The present study investigated the capacity for arctigenin (ARC) to prevent secondary brain injury and the determination of the underlying mechanism of action in a mouse model of SWI that mimics the process of CED. After CED, mice received a gavage of ARC from 30 min to 14 days. Neurological severity scores (NSS) and wound closure degree were assessed after the injury. Histological analysis and immunocytochemistry were used to evaluated the extent of brain damage and neuroinflammation. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was used to detect universal apoptosis. Enzyme-linked immunosorbent assays (ELISA) was used to test the inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10) and lactate dehydrogenase (LDH) content. Gene levels of inflammation (TNF-α, IL-6, and IL-10) and apoptosis (Caspase-3, Bax and Bcl-2) were detected by reverse transcription-polymerase chain reaction (RT-PCR). Using these, we analyzed ARC’s efficacy and mechanism of action. Results: ARC treatment improved neurological function by reducing brain water content and hematoma and accelerating wound closure relative to untreated mice. ARC treatment reduced the levels of TNF-α and IL-6 and the number of allograft inflammatory factor (IBA)- and myeloperoxidase (MPO)-positive cells and increased the levels of IL-10. ARC-treated mice had fewer TUNEL+ apoptotic neurons and activated caspase-3-positive neurons surrounding the lesion than controls, indicating increased neuronal survival. Conclusions: ARC treatment confers neuroprotection of brain tissue through anti-inflammatory and anti-apoptotic effects in a mouse model of SWI. These results suggest a new strategy for promoting neuronal survival and function after CED to improve long-term patient outcome.

Glucose-6-Phosphate Dehydrogenase Deficiency and the Need for a Novel Treatment to Prevent Kernicterus

Hyperbilirubinemia occurs frequently in newborns, and in severe cases can progress to kernicterus and permanent developmental disorders. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, one of the most common human enzymopathies, is a major risk factor for hyperbilirubinemia and greatly increases the risk of kernicterus even in the developed world. Therefore, a novel treatment for kernicterus is needed, especially for G6PD-deficient newborns. Oxidative stress is a hallmark of bilirubin toxicity in the brain. We propose that the activation of G6PD via a small molecule chaperone is a potential strategy to increase endogenous defense against bilirubin-induced oxidative stress and prevent kernicterus.

IL-17A promotes microglial activation and neuroinflammation in mouse models of intracerebral haemorrhage

Microglial activation is an important contributor to neuroinflammation in intracerebral haemorrhage (ICH). IL-17A has been demonstrated to be involved in neuroinflammatory diseases such as multiple sclerosis. However, the exact mechanism of IL-17A mediated microglial activation in ICH has not been well identified. The purpose of this experiment is to investigate the role of IL-17A in ICH induced microglial activation and neuroinflammation. ICH mice were made by injection of autologous blood model. IL-17A expression and inflammatory factors in perihematomal region, and neurological function of mice were examined after ICH. In addition, IL-17A-neutralizing antibody was utilized to potentially prevent microglial activation and neuroinflammation in ICH mice. The expression of IL-17A, inflammatory factors and microglial activation in perihematomal region were significantly increased, and neurological function of mice was impaired after ICH. In addition, IL-17A Ab prevented ICH-induced cytokine expression, including TNF-α, IL-1β and IL-6, and downstream signaling molecules, including MyD88, TRIF, IκBα, and NF-κBp65 expression, and attenuated microglial activation. IL-17A Ab significantly reduced brain water content and improved neurological function of ICH mice. In conclusion, our results demonstrated that IL-17A was involved in ICH-induced microglial activation and neuroinflammation. IL-17A Ab might also provide a promising therapeutic strategy in ICH.

Autophagy Promotes Microglia Activation Through Beclin-1-Atg5 Pathway in Intracerebral Hemorrhage

Previous study demonstrates that intracerebral hemorrhage (ICH) promotes microglia activation and inflammation. However, the exact mechanism of microglia activation induced by ICH is not clear. In this experiment, microglia autophagy was examined using electron microscopy, conversion of light chain 3(LC3), and monodansylcadaverine (MDC) staining to detect autophagic vacuoles. We found that ICH induced microglia autophagy and activation. The suppression of autophagy using either pharmacologic inhibitors (3-methyladenine, bafilomycin A1) or RNA interference in essential autophagy genes (BECN1 and ATG5) decreased the microglia activation and inflammation in ICH. Moreover, autophagy inhibitors reduced brain damage in ICH. In conclusion, these data indicate that ICH contributes to microglia autophagic activation through BECN1 and ATG5 and provide the therapeutical strategy for ICH.

Intercellular cross-talk in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating cerebrovascular disorder with high mortality and morbidity. Currently, there are few treatment strategies for ICH-induced brain injury. A recent increase in interest in the pathophysiology of ICH has led to elucidation of the pathways underlying ICH-induced brain injury, pathways where intercellular and hematoma to cell signaling play important roles. In this review, we summarize recent advances in ICH research focusing on intercellular and hematoma:cell cross-talk related to brain injury and recovery after ICH. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Bilirubin and its oxidation products damage brain white matter

Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke.

Vascular disruption and blood-brain barrier dysfunction in intracerebral hemorrhage

This article reviews current knowledge of the mechanisms underlying the initial hemorrhage and secondary blood-brain barrier (BBB) dysfunction in primary spontaneous intracerebral hemorrhage (ICH) in adults. Multiple etiologies are associated with ICH, for example, hypertension, Alzheimer's disease, vascular malformations and coagulopathies (genetic or drug-induced). After the initial bleed, there can be continued bleeding over the first 24 hours, so-called hematoma expansion, which is associated with adverse outcomes. A number of clinical trials are focused on trying to limit such expansion. Significant progress has been made on the causes of BBB dysfunction after ICH at the molecular and cell signaling level. Blood components (e.g. thrombin, hemoglobin, iron) and the inflammatory response to those components play a large role in ICH-induced BBB dysfunction. There are current clinical trials of minimally invasive hematoma removal and iron chelation which may limit such dysfunction. Understanding the mechanisms underlying the initial hemorrhage and secondary BBB dysfunction in ICH is vital for developing methods to prevent and treat this devastating form of stroke.

CD36-mediated hematoma absorption following intracerebral hemorrhage: negative regulation by TLR4 signaling

Promoting hematoma absorption is a novel therapeutic strategy for intracerebral hemorrhage (ICH); however, the mechanism of hematoma absorption is unclear. The present study explored the function and potential mechanism of CD36 in hematoma absorption using in vitro and in vivo ICH models. Hematoma absorption in CD36-deficient ICH patients was examined. Compared with patients with normal CD36 expression, CD36-deficient ICH patients had slower hematoma adsorption and aggravated neurologic deficits. CD36 expression in perihematomal tissues in wild-type mice following ICH was increased, whereas the hematoma absorption in CD36(-/-) mice was decreased. CD36(-/-) mice also showed aggravated neurologic deficits and increased TNF-α and IL-1β expression levels. The phagocytic capacity of CD36(-/-) microglia for RBCs was also decreased. Additionally, the CD36 expression in the perihematoma area after ICH in TLR4(-/-) and MyD88(-/-) mice was significantly increased, and hematoma absorption was significantly promoted, which was significantly inhibited by an anti-CD36 Ab. In vitro, TNF-α and IL-1β significantly inhibited the microglia expression of CD36 and reduced the microglia phagocytosis of RBCs. Finally, the TLR4 inhibitor TAK-242 upregulated CD36 expression in microglia, promoted hematoma absorption, increased catalase expression, and decreased the H2O2 content. These results suggested that CD36 mediated hematoma absorption after ICH, and TLR4 signaling inhibited CD36 expression to slow hematoma absorption. TLR4 inhibition could promote hematoma absorption and significantly improve neurologic deficits following ICH.

Administration of S-methyl-L-thiocitrulline protects against brain injuries after intracerebral hemorrhage

Although intracerebral hemorrhage (ICH) increases the level of glutamate in the perihematomal area and cerebral spinal fluid (CSF) in the ICH acute phase, it is unclear whether elevated glutamate activates neuronal nitric oxide synthase (nNOS) in the ICH brain and whether nNOS is an important target for ICH treatment. Here, we assessed the role of the nNOS inhibitor S-methyl-l-thiocitrulline (SMTC) in the activity of NADPH-d and ICH-induced brain injuries. An autologous blood intracerebral infusion model in male rats was used. All of the rats were sacrificed 24h after ICH. ICH increased NADPH-d activity in the striatum. Administering SMTC 3h after ICH decreased the activity of NADH-d (p<0.05 vs. the ICH group). The activation of gelatinolytic enzymes in the perihematomal region of the striatum was reduced by SMTC treatment (p<0.01, vs. the ICH group). The loss of laminin- and occludin-stained vessels was significant in perihematomal regions after 24h of ICH and was significantly attenuated by the administration of SMTC (p<0.01 for laminin, p<0.05 for occluding, compared with the ICH group). Neuronal death and neurological deficits after ICH were also decreased in SMTC treatment rats (p<0.01, vs. the ICH group). The results suggest that the administration of the nNOS inhibitor SMTC after ICH protects against ICH-induced brain injuries and improves neurological function.

Microglial responses after ischemic stroke and intracerebral hemorrhage

Stroke is a leading cause of death worldwide. Ischemic stroke is caused by blockage of blood vessels in the brain leading to tissue death, while intracerebral hemorrhage (ICH) occurs when a blood vessel ruptures, exposing the brain to blood components. Both are associated with glial toxicity and neuroinflammation. Microglia, as the resident immune cells of the central nervous system (CNS), continually sample the environment for signs of injury and infection. Under homeostatic conditions, they have a ramified morphology and phagocytose debris. After stroke, microglia become activated, obtain an amoeboid morphology, and release inflammatory cytokines (the M1 phenotype). However, microglia can also be alternatively activated, performing crucial roles in limiting inflammation and phagocytosing tissue debris (the M2 phenotype). In rodent models, microglial activation occurs very early after stroke and ICH; however, their specific roles in injury and repair remain unclear. This review summarizes the literature on microglial responses after ischemic stroke and ICH, highlighting the mediators of microglial activation and potential therapeutic targets for each condition.

Elevated bilirubin after acute ischemic stroke linked to the stroke severity

BACKGROUND

Our previous study demonstrated that the level of serum bilirubin after acute ischemic stroke (AIS) was correlated to the severity of stroke, also there has the evidence of hyperbilirubinemia prevalent in AIS. We aimed to identify the exact change of bilirubin in the early phase of AIS, and study if this kind of change linked to the severity of stroke.

METHODS

Bilirubin and other biochemical indexes were measured in 608 AIS patients and 188 transient ischemic attack (TIA) patients which set as the control group. National Institutes of Health Stroke Scale (NIHSS) scores were assessed simultaneously with blood collection. First, the level of bilirubin and its distribution were compared between the AIS and control group. According to a cut-off point, we next analyzed the impacted factors of elevated bilirubin including the direct bilirubin (Dbil) and total bilirubin (Tbil), especially the correlation between elevated bilirubin and the severity of stroke. Finally, we compared the difference of concentration and percent of elevated bilirubin among the Oxford Community Stroke Project (OCSP) subtypes.

RESULTS

The level of serum Dbil and Tbil was significantly higher in the AIS group than that in the TIA group. Different distribution was observed between the two groups, which manifested as the percent of low bilirubin level group was lower while high level group was higher in AIS than that in TIA, the p value were 0.043 and 0.078 in Dbil and Tbil, respectively. When the cut-off point of elevated bilirubin was selected as Dbil≥6.84 μmol/L and Tbil≥22.2 μmol/L, we found that both NIHSS score and relative severity of AIS were significantly associated with elevated bilirubin whenever in Dbil or Tbil, so did the OCSP subtypes. This trend was still maintained by multivariable logistic regression analysis adjust for relative influence factors. In regard of OCSP subtypes, the highest level of bilirubin was found in TACI, so did the highest rate of elevated bilirubin.

CONCLUSION

The serum levels of Dbil and Tbil were increased after AIS, which linked to the severity of stroke.

TNF-alpha receptor antagonist, R-7050, improves neurological outcomes following intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH), the most common form of hemorrhagic stroke, exhibits the highest acute mortality and the worst long-term prognosis of all stroke subtypes. Unfortunately, treatment options for ICH are lacking due in part to a lack of feasible therapeutic targets. Inflammatory activation is associated with neurological deficits in pre-clinical ICH models and with patient deterioration after clinical ICH. In the present study, we tested the hypothesis that R-7050, a novel cell permeable triazoloquinoxaline inhibitor of the tumor necrosis factor receptor (TNFR) complex, attenuates neurovascular injury after ICH in mice. Up to 2h post-injury administration of R-7050 significantly reduced blood-brain barrier opening and attenuated edema development at 24h post-ICH. Neurological outcomes were also improved over the first 3 days after injury. In contrast, R-7050 did not reduce hematoma volume, suggesting the beneficial effects of TNFR inhibition were downstream of clot formation/resolution. These data suggest a potential clinical utility for TNFR antagonists as an adjunct therapy to reduce neurological injury and improve patient outcomes after ICH.

The evolving landscape of neurotoxicity by unconjugated bilirubin: role of glial cells and inflammation

Unconjugated hyperbilirubinemia is a common condition in the first week of postnatal life. Although generally harmless, some neonates may develop very high levels of unconjugated bilirubin (UCB), which may surpass the protective mechanisms of the brain in preventing UCB accumulation. In this case, both short-term and long-term neurodevelopmental disabilities, such as acute and chronic UCB encephalopathy, known as kernicterus, or more subtle alterations defined as bilirubin-induced neurological dysfunction (BIND) may be produced. There is a tremendous variability in babies' vulnerability toward UCB for reasons not yet explained, but preterm birth, sepsis, hypoxia, and hemolytic disease are comprised as risk factors. Therefore, UCB levels and neurological abnormalities are not strictly correlated. Even nowadays, the mechanisms of UCB neurotoxicity are still unclear, as are specific biomarkers, and little is known about lasting sequelae attributable to hyperbilirubinemia. On autopsy, UCB was shown to be within neurons, neuronal processes, and microglia, and to produce loss of neurons, demyelination, and gliosis. In isolated cell cultures, UCB was shown to impair neuronal arborization and to induce the release of pro-inflammatory cytokines from microglia and astrocytes. However, cell dependent sensitivity to UCB toxicity and the role of each nerve cell type remains not fully understood. This review provides a comprehensive insight into cell susceptibilities and molecular targets of UCB in neurons, astrocytes, and oligodendrocytes, and on phenotypic and functional responses of microglia to UCB. Interplay among glia elements and cross-talk with neurons, with a special emphasis in the UCB-induced immunostimulation, and the role of sepsis in BIND pathogenesis are highlighted. New and interesting data on the anti-inflammatory and antioxidant activities of different pharmacological agents are also presented, as novel and promising additional therapeutic approaches to BIND.

Depletion of GR-1-Positive Cells Is Associated with Reduced Neutrophil Inflammation and Astrocyte Reactivity after Experimental Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the stroke subtype with the highest mortality and morbidity with 25% of patients dying within the first 48 h and a high incidence of poor outcomes. Because of high early mortality rates, an understanding of acute brain injury mechanisms is essential. In this study, we have investigated the putative role of acute inflammation in brain injury after experimental ICH. We depleted GR-1(+) cells in mice by intraperitoneal administration of anti-GR-1 antibody or normal rat serum (control). We then induced ICH by infusion of autologous whole blood into the striatum and compared functional outcome and brain injury markers between the two groups. We found that administration of anti-GR-1 antibody led to a profound decrease in circulating GR-1(+) cells (1.5 ± 0.34% vs. 50.3 ± 8.3% of CD45(+) cells, p ≤ 0.01) and that brain neutrophils decreased by approximately 50% (p ≤ 0.05). We observed a reduction in astrocyte immunoreactivity in the GR-1(+) cell-depleted group (p ≤ 0.05). Conversely, we did not find attenuation of brain edema or differences in behavioral deficits between the two groups. In summary, our results are promising and suggest that larger studies or different neutrophil manipulations may produce greater attenuation of injury after ICH.

Cerebellar axon/myelin loss, angiogenic sprouting, and neuronal increase of vascular endothelial growth factor in a preterm infant with kernicterus

We performed histologic and immunohistochemical analysis of cerebellar sections from a preterm infant (32 weeks 5 days) dead on the 4th day of life with the diagnosis of kernicterus and compared the results with 1 age-matched nonicteric patient. Poorer Luxol fast blue-periodic acid Schiff and Bodian-Luxol fast blue stainings as well as neurofilament expression were observed in the kernicterus case, indicating loss of axon neurites and myelin fibers. Elevated claudin-5 and cluster of differentiation 34 expression associated with increased blood vessel density suggests bilirubin-induced angiogenic sprouting. Upregulation of vascular endothelial growth factor and its receptor 2 was observed in nucleus dentatus and Purkinje neurons. Although upregulation of multidrug resistance-associated protein 1 was increased in cerebellar neurons, it was not able to prevent bilirubin-induced neurotoxicity. These data add new insights into the pathophysiology of kernicterus, revealing vascular endothelial growth factor and its receptor 2, as well as angiogenic sprouting, as new players in neurologic damage by unconjugated bilirubin.