Targeting the Nrf2-Heme Oxygenase-1 Axis after Intracerebral Hemorrhage

MiRNAs as potential therapeutic targets and biomarkers for non-traumatic intracerebral hemorrhage

Non-traumatic intracerebral hemorrhage (ICH) is the most common type of hemorrhagic stroke, most often occurring between the ages of 45 and 60. Hypertension is most often the cause of ICH. Less often, atherosclerosis, blood diseases, inflammatory changes in cerebral vessels, intoxication, vitamin deficiencies, and other reasons cause hemorrhages. Cerebral hemorrhage can occur by diapedesis or as a result of a ruptured vessel. This very dangerous disease is difficult to treat, requires surgery and can lead to disability or death. MicroRNAs (miRNAs) are a class of non-coding RNAs (about 18-22 nucleotides) that are involved in a variety of biological processes including cell differentiation, proliferation, apoptosis, etc., through gene repression. A growing number of studies have demonstrated miRNAs deregulation in various cardiovascular diseases, including ICH. In addition, given that computed tomography (CT) and/or magnetic resonance imaging (MRI) are either not available or do not show clear signs of possible vessel rupture, accurate and reliable analysis of circulating miRNAs in biological fluids can help in early diagnosis for prevention of ICH and prognosis patient outcome after hemorrhage. In this review, we highlight the up-to-date findings on the deregulated miRNAs in ICH, and the potential use of miRNAs in clinical settings, such as therapeutic targets and non-invasive diagnostic/prognostic biomarker tools.

Immunological dimensions of neuroinflammation and microglial activation: exploring innovative immunomodulatory approaches to mitigate neuroinflammatory progression

The increasing life expectancy has led to a higher incidence of age-related neurodegenerative conditions. Within this framework, neuroinflammation emerges as a significant contributing factor. It involves the activation of microglia and astrocytes, leading to the release of pro-inflammatory cytokines and chemokines and the infiltration of peripheral leukocytes into the central nervous system (CNS). These instances result in neuronal damage and neurodegeneration through activated nucleotide-binding domain and leucine-rich repeat containing (NLR) family pyrin domain containing protein 3 (NLRP3) and nuclear factor kappa B (NF-kB) pathways and decreased nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Due to limited effectiveness regarding the inhibition of neuroinflammatory targets using conventional drugs, there is challenging growth in the search for innovative therapies for alleviating neuroinflammation in CNS diseases or even before their onset. Our results indicate that interventions focusing on Interleukin-Driven Immunomodulation, Chemokine (CXC) Receptor Signaling and Expression, Cold Exposure, and Fibrin-Targeted strategies significantly promise to mitigate neuroinflammatory processes. These approaches demonstrate potential anti-neuroinflammatory effects, addressing conditions such as Multiple Sclerosis, Experimental autoimmune encephalomyelitis, Parkinson's Disease, and Alzheimer's Disease. While the findings are promising, immunomodulatory therapies often face limitations due to Immune-Related Adverse Events. Therefore, the conduction of randomized clinical trials in this matter is mandatory, and will pave the way for a promising future in the development of new medicines with specific therapeutic targets.

Common Mutation in the HFE Gene Modifies Recovery After Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is characterized by bleeding into the brain parenchyma. During an ICH, iron released from the breakdown of hemoglobin creates a cytotoxic environment in the brain through increased oxidative stress. Interestingly, the loss of iron homeostasis is associated with the pathological process of other neurological diseases. However, we have previously shown that the H63D mutation in the homeostatic iron regulatory (HFE) gene, prevalent in 28% of the White population in the United States, acts as a disease modifier by limiting oxidative stress. The following study aims to examine the effects of the murine homolog, H67D HFE, on ICH.

METHODS

An autologous blood infusion model was utilized to create an ICH in the right striatum of H67D and wild-type mice. The motor recovery of each animal was assessed by rotarod. Neurodegeneration was measured using fluorojade-B and mitochondrial damage was assessed by immunofluorescent numbers of CytC+ (cytochrome C) neurons and CytC+ astrocytes. Finally, the molecular antioxidant response to ICH was quantified by measuring Nrf2 (nuclear factor-erythroid 2 related factor), GPX4 (glutathione peroxidase 4), and FTH1 (H-ferritin) levels in the ICH-affected and nonaffected hemispheres via immunoblotting.

RESULTS

At 3 days post-ICH, H67D mice demonstrated enhanced performance on rotarod compared with wild-type animals despite no differences in lesion size. Additionally, H67D mice displayed higher levels of Nrf2, GPX4, and FTH1 in the ICH-affected hemisphere; however, these levels were not different in the contralateral, non-ICH-affected hemisphere. Furthermore, H67D mice showed decreased degenerated neurons, CytC+ Neurons, and CytC+ astrocytes in the perihematomal area.

CONCLUSIONS

Our data suggest that the H67D mutation induces a robust antioxidant response 3 days following ICH through Nrf2, GPX4, and FTH1 activation. This activation could explain the decrease in degenerated neurons, CytC+ neurons, and CytC+ astrocytes in the perihematomal region, leading to the improved motor recovery. Based on this study, further investigation into the mechanisms of this neuroprotective response and the effects of the H63D HFE mutation in a population of patients with ICH is warranted.

Oxidative stress following spinal cord injury: From molecular mechanisms to therapeutic targets

Spinal cord injury (SCI) is a medical condition that results from severe trauma to the central nervous system; it imposes great psychological and economic burdens on affected patients and their families. The dynamic balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining normal cellular physiological functions. As important intracellular signaling molecules, ROS regulate numerous physiological activities, including vascular reactivity and neuronal function. However, excessive ROS can cause damage to cellular macromolecules, including DNA, lipids, and proteins; this damage eventually leads to cell death. This review discusses the mechanisms of oxidative stress in SCI and describes some signaling pathways that regulate oxidative injury after injury, with the aim of providing guidance for the development of novel SCI treatment strategies.

Zhilong Huoxue Tongyu capsule attenuates intracerebral hemorrhage induced redox imbalance by modulation of Nrf2 signaling pathway

Background: One of the severely debilitating and fatal subtypes of hemorrhagic stroke is intracerebral hemorrhage (ICH), which lacks an adequate cure at present. The Zhilong Huoxue Tongyu (ZLHXTY) capsule has been utilized effectively since last decade to treat ICH, in some provinces of China but the scientific basis for its mechanism is lacking. Purpose: To investigate the neuroprotective role of ZLHXTY capsules for ICH-induced oxidative injury through the regulation of redox imbalance with the Nrf2 signaling pathway. Methods: Autologous blood injection model of ICH in C57BL/6J mice was employed. Three treatment groups received ZLHXTY once daily through oral gavage at doses 0.35 g/kg, 0.7 g/kg, and 1.4 g/kg, started after 2 h and continued for 72 h of ICH induction. The neurological outcome was measured using a balance beam test. Serum was tested for inflammatory markers IL-1β, IL-6, and TNF-α through ELISA, oxidative stress through hydrogen peroxide content assay, and antioxidant status by total antioxidant capacity (T-AOC) assay. Nuclear extract from brain tissue was assayed for Nrf2 transcriptional factor activity. RT-qPCR was performed for Nfe2l2, Sod1, Hmox1, Nqo1, and Mgst1; and Western blotting for determination of protein expression of Nrf2, p62, Pp62, Keap, HO1, and NQO1. Fluoro-jade C staining was also used to examine neuronal damage. Results: ZLHXTY capsule treatment following ICH demonstrated a protective effect against oxidative brain injury. Neurological scoring showed improvement in behavioral outcomes. ELISA-based identification demonstrated a significant decline in the expression of serum inflammatory markers. Hydrogen peroxide content in serum was found to be reduced. The total antioxidant capacity was also reduced in serum, but the ZLHXTY extract showed a concentration-dependent increase in T-AOC speculating at its intrinsic antioxidant potential. Nrf2 transcriptional factor activity, mRNA and protein expression analyses revealed normalization of Nrf2 and its downstream targets, which were previously elevated as a result of oxidative stress induced by ICH. Neuronal damage was also reduced markedly after ZLHXTY treatment as revealed by Fluoro-jade C staining. Conclusion: ZLHXTY capsules possess an intrinsic antioxidant potential that can modulate the ICH-induced redox imbalance in the brain as revealed by the normalization of Nrf2 and its downstream antioxidant targets.

An enriched environment improves long-term functional outcomes in mice after intracerebral hemorrhage by mechanisms that involve the Nrf2/BDNF/glutaminase pathway

Post-stroke depression exacerbates neurologic deficits and quality of life. Depression after ischemic stroke is known to some extent. However, depression after intracerebral hemorrhage (ICH) is relatively unknown. Increasing evidence shows that exposure to an enriched environment (EE) after cerebral ischemia/reperfusion injury has neuroprotective effects in animal models, but its impact after ICH is unknown. In this study, we investigated the effect of EE on long-term functional outcomes in mice subjected to collagenase-induced striatal ICH. Mice were subjected to ICH with the standard environment (SE) or ICH with EE for 6 h/day (8:00 am-2:00 pm). Depressive, anxiety-like behaviors and cognitive tests were evaluated on day 28 with the sucrose preference test, tail suspension test, forced swim test, light-dark transition experiment, morris water maze, and novel object recognition test. Exposure to EE improved neurologic function, attenuated depressive and anxiety-like behaviors, and promoted spatial learning and memory. These changes were associated with increased expression of transcription factor Nrf2 and brain-derived neurotrophic factor (BDNF) and inhibited glutaminase activity in the perihematomal tissue. However, EE did not change the above behavioral outcomes in Nrf2-/- mice on day 28. Furthermore, exposure to EE did not increase BDNF expression compared to exposure to SE in Nrf2-/- mice on day 28 after ICH. These findings indicate that EE improves long-term outcomes in sensorimotor, emotional, and cognitive behavior after ICH and that the underlying mechanism involves the Nrf2/BDNF/glutaminase pathway.

Remote preconditioning combined with nebulized budesonide alleviate lipopolysaccharide induced acute lung injury via regulating HO-1 and NF-κB in rats

BACKGROUND

Acute lung injury (ALI) may result in severe systemic inflammation and is life-threatening. Remote inflammatory preconditioning (RIPC) has been confirmed to have an endogenous protective effect against ALI. Budesonide (BS) is a potent corticosteroid typically administered through nebulization that reduces inflammation in the lungs. We speculate that the combined use of RIPC and nebulized BS has a stronger protective effect on ALI.

METHODS

48 Sprague-Dawley male rats were used for the experiments. Animals were divided evenly and randomly into three groups, control (NS injection), LPS (LPS injection), and RIPC (LPS injection with RIPC). Each group was then divided into two subgroups with inhalation of nebulized normal saline (NS) or BS. Prior to injection of LPS, RIPC was performed by tying and untying the right hind limb for three cycles of five minutes each. Following LPS injection, animals in each subgroup were placed in a same cage for nebulized inhalation. Animals were sacrificed 6 hours after LPS injection. Histological evaluation of ALI and lung wet-to-dry weight ratio were measured. Serum lactate acid, inflammatory cytokines, oxidative stress indicators were detected. The expression of HO-1, NF-κB p65 and p-p65 was measured by western blotting.

RESULTS

RIPC combined with nebulized BS significantly attenuated the LPS-induced ALI in rats. Reduction of MDA, increasing of SOD activity were found significantly improved by the joint strategy. TNF- and IL-1β rise brought on by LPS was reduced, but IL-10 production dramatically enhanced when compared to the LPS group. The expression of HO-1 was significantly increased by RIPC combined with nebulized BS while the expression of NF-κB p65 and p-p65 was decreased when compared with the LPS group.

CONCLUSION

RIPC combined with nebulized budesonide is protective for ALI induced by LPS in rats.

Dimethyl Fumarate Triggers the Antioxidant Defense System in Human Retinal Endothelial Cells through Nrf2 Activation

Dimethyl fumarate (DMF) is a well-known activator of Nrf2 (NF-E2-related factor 2), used in the treatment of psoriasis and multiple sclerosis. The mechanism of action consists in the modification of the cysteine residues on the Nrf2-inhibitor Keap1, thus leading to the dissociation of these two proteins and the consequent activation of Nrf2. Considering the paucity of evidence of DMF effects in the context of retinal endothelium, this in vitro study investigated the role of DMF in human retinal endothelial cells (HREC). Here, we show for the first time in HREC that DMF activates the Nrf2 pathway, thus leading to an increase in HO-1 protein levels and a decrease in intracellular ROS levels. Furthermore, this molecule also shows beneficial properties in a model of hyperglucose stress, exerting cytoprotective prosurvival effects. The overall collected results suggest that DMF-mediated activation of the Nrf2 pathway may also be a promising strategy in ocular diseases characterized by oxidative stress. This study opens a new perspective on DMF and suggests its potential repositioning in a broader therapeutical context.

Semaphorin 6D regulate corralling, hematoma compaction and white matter injury in mice after intracerebral hemorrhage

OBJECTIVES

The Semaphorin 6D (SEMA6D) shows important roles in cell guidance and lipid metabolism, but the effects and mechanisms of SEMA6D on tissue repair, white matter injury and the recovery of neurological function after intracerebral hemorrhage have not been well studied.

MATERIALS AND METHODS

In this study, the autologous whole blood injection model of intracerebral hemorrhage was established in C57 male mice. SEMA6D knockout CRISPR utilized in the study. Assessments included neurological score evaluation and immunofluorescence.

RESULTS

SEMA6D increased and peaked at 7d after intracerebral hemorrhage, and mainly located in neurons, microglia and astrocytes. SEMA6D knockout CRISPR aggravated neurological function and showed signs of poorer corralling and hematoma resolution, with more compartments of well-established physical barrier and more extensive GFAP positive astrocytic border. Furthermore, SEMA6D can prevent the decrease of NF-H in the peri-hematoma region, while SEMA6D knockout aggravated WMI.

CONCLUSIONS

Our study suggested that SEMA6D could influence the recovery of neurological function by regulating the corralling, hematoma compaction and WMI in mice after intracerebral hemorrhage.

Targeting Oxidative Stress in Intracerebral Hemorrhage: Prospects of the Natural Products Approach

Intracerebral hemorrhage (ICH), the second most common subtype of stroke, remains a significant cause of morbidity and mortality worldwide. The pathological mechanism of ICH is very complex, and it has been demonstrated that oxidative stress (OS) plays an important role in the pathogenesis of ICH. Previous studies have shown that OS is a therapeutic target after ICH, and antioxidants have also achieved some benefits in the treatment of ICH. This review aimed to explore the promise of natural products therapy to target OS in ICH. We searched PubMed using the keywords “oxidative stress in intracerebral hemorrhage” and “natural products in intracerebral hemorrhage”. Numerous animal and cell studies on ICH have demonstrated the potent antioxidant properties of natural products, including polyphenols and phenolic compounds, terpenoids, alkaloids, etc. In summary, natural products such as antioxidants offer the possibility of treatment of OS after ICH. However, researchers still have a long way to go to apply these natural products for the treatment of ICH more widely in the clinic.

Targeting Oxidative Stress and Inflammatory Response for Blood-Brain Barrier Protection in Intracerebral Hemorrhage

Significance: Blood-brain barrier (BBB) disruption is a major pathological change after intracerebral hemorrhage (ICH) and is both the cause and result of oxidative stress and of the immune response post-ICH. These processes contribute to ICH-induced brain injury. Recent Advances: After the breakdown of cerebral vessels, blood components, including erythrocytes and their metabolites, thrombin, and fibrinogen, can access the cerebral parenchyma through the compromised BBB, triggering oxidative stress and inflammatory cascades. These aggravate BBB disruption and contribute to further infiltration of blood components, resulting in a vicious cycle that exacerbates brain edema and neurological injury after ICH. Experimental and clinical studies have highlighted the role of BBB disruption in ICH-induced brain injury. Critical Issues: In this review, we focus on the strategies to protect the BBB in ICH. Specifically, we summarize the evidence and the underlying mechanisms, including the ICH-induced process of oxidative stress and inflammatory response, and we highlight the potential therapeutic targets to protect BBB integrity after ICH. Future Directions: Future studies should probe the mechanism of ferroptosis as well as oxidative stress-inflammation coupling in BBB disruption after ICH and investigate the effects of antioxidants and immunomodulatory agents in more ICH clinical trials. Antioxid. Redox Signal. 37, 115-134.

Antioxidant potential of Pediococcus pentosaceus strains from the sow milk bacterial collection in weaned piglets

BACKGROUND

In modern animal husbandry, breeders pay increasing attention to improving sow nutrition during pregnancy and lactation to favor the health of neonates. Sow milk is a main food source for piglets during their first three weeks of life, which is not only a rich repository of essential nutrients and a broad range of bioactive compounds, but also an indispensable source of commensal bacteria. Maternal milk microorganisms are important sources of commensal bacteria for the neonatal gut. Bacteria from maternal milk may confer a health benefit on the host.

METHODS

Sow milk bacteria were isolated using culturomics followed by identification using 16S rRNA gene sequencing. To screen isolates for potential probiotic activity, the functional evaluation was conducted to assess their antagonistic activity against pathogens in vitro and evaluate their resistance against oxidative stress in damaged Drosophila induced by paraquat. In a piglet feeding trial, a total of 54 newborn suckling piglets were chosen from nine sows and randomly assigned to three treatments with different concentrations of a candidate strain. Multiple approaches were carried out to verify its antioxidant function including western blotting, enzyme activity analysis, metabolomics and 16S rRNA gene amplicon sequencing.

RESULTS

The 1240 isolates were screened out from the sow milk microbiota and grouped into 271 bacterial taxa based on a nonredundant set of 16S rRNA gene sequencing. Among 80 Pediococcus isolates, a new Pediococcus pentosaceus strain (SMM914) showed the best performance in inhibition ability against swine pathogens and in a Drosophila model challenged by paraquat. Pretreatment of piglets with SMM914 induced the Nrf2-Keap1 antioxidant signaling pathway and greatly affected the pathways of amino acid metabolism and lipid metabolism in plasma. In the colon, the relative abundance of Lactobacillus was significantly increased in the high dose SMM914 group compared with the control group.

CONCLUSION

P. pentosaceus SMM914 is a promising probiotic conferring antioxidant capacity by activating the Nrf2-Keap1 antioxidant signaling pathway in piglets. Our study provided useful resources for better understanding the relationships between the maternal microbiota and offspring. Video Abstract.

Crocin Alleviates Intracerebral Hemorrhage-Induced Neuronal Ferroptosis by Facilitating Nrf2 Nuclear Translocation

Intracerebral hemorrhage (ICH) is the deadliest type of stroke. Oxidative stress was considered to play an important role in ICH-induced secondary injury. Crocin, the main compound isolated from Crocus sativus L., possesses a potential anti-oxidative function in many types of diseases including ICH. In the current study, the protective role of crocin in ICH-induced brain injury was investigated in the ICH model. The ICH-induced brain edema and neurological deficits were analyzed by brain edema measurement and neurological testing. The superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activity and the content of malondialdehyde (MDA) were assessed by a total superoxide dismutase assay kit. The expressions of ferroptosis-related genes were verified by quantitative real-time PCR (qPCR) and western blotting. The ICH-induced brain edema and neurological deficits were significantly decreased after treatment with crocin. Moreover, the SOD and GSH-px activities were obviously increased in the ICH with crocin-treated group compared with the ICH group, while the content of MDA was markedly decreased after treatment with crocin. Crocin inhibited ferroptosis of neuron cells, as evidenced by increased Fe²⁺ concentration and the expression of GPX4, FTH1, and SLC7A11. Mechanistically, crocin treatment increased the expression and nuclear translocation of Nrf2. Our data suggest that crocin alleviates intracerebral hemorrhage-induced neuronal ferroptosis by facilitating Nrf2 nuclear translocation.

Oxidative Stress Following Intracerebral Hemorrhage: From Molecular Mechanisms to Therapeutic Targets

Intracerebral hemorrhage (ICH) is a highly fatal disease with mortality rate of approximately 50%. Oxidative stress (OS) is a prominent cause of brain injury in ICH. Important sources of reactive oxygen species after hemorrhage are mitochondria dysfunction, degradated products of erythrocytes, excitotoxic glutamate, activated microglia and infiltrated neutrophils. OS harms the central nervous system after ICH mainly through impacting inflammation, killing brain cells and exacerbating damage of the blood brain barrier. This review discusses the sources and the possible molecular mechanisms of OS in producing brain injury in ICH, and anti-OS strategies to ameliorate the devastation of ICH.

Revisiting Minocycline in Intracerebral Hemorrhage: Mechanisms and Clinical Translation

Intracerebral hemorrhage (ICH) is an important subtype of stroke with an unsatisfactory prognosis of high mortality and disability. Although many pre-clinical studies and clinical trials have been performed in the past decades, effective therapy that meaningfully improve prognosis and outcomes of ICH patients is still lacking. An active area of research is towards alleviating secondary brain injury after ICH through neuroprotective pharmaceuticals and in which minocycline is a promising candidate. Here, we will first discuss new insights into the protective mechanisms of minocycline for ICH including reducing iron-related toxicity, maintenance of blood-brain barrier, and alleviating different types of cell death from preclinical data, then consider its shortcomings. Finally, we will review clinical trial perspectives for minocycline in ICH. We hope that this summary and discussion about updated information on minocycline as a viable treatment for ICH can facilitate further investigations.

BMAL1 attenuates intracerebral hemorrhage-induced secondary brain injury in rats by regulating the Nrf2 signaling pathway

Background

Intracerebral hemorrhage (ICH) is a severe cerebrovascular disease with high morbidity and mortality rates. Oxidative stress and inflammation are important pathological mechanisms of secondary brain injury (SBI) after ICH. Brain and muscle Arnt-like protein 1 (BMAL1), which forms the core component of the circadian clock, was previously shown to be involved in many diseases and to participate in oxidative stress and inflammatory responses. However, the role of BMAL1 in SBI following ICH is unknown. In addition, treatments targeting miR-155 and its downstream signaling pathway may exert a beneficial effect on SBI after ICH, while miR-155 may regulate Bmal1 mRNA stability and translation. Nevertheless, researchers have not clearly determined whetheantagomir-155 upregulates BMAL1 expression and subsequently attenuates ICH-induced brain injury in rats.

Methods

After establishing an ICH rat model by injecting autologous blood, the time course of changes in levels of the BMAL1 protein after ICH was analyzed. Subsequently, this study was designed to investigate the potential role and mechanisms of BMAL1 in SBI following ICH using lentiviral overexpression and antagomir-155 treatments.

Results

BMAL1 protein levels were significantly decreased in the ICH group compared to the sham group. Genetic overexpression of BMAL1 alleviated oxidative stress, inflammation, brain edema, blood-brain barrier injury, neuronal death, and neurological dysfunction induced by ICH. On the other hand, we observed that inhibiting miRNA-155 using antagomir-155 promoted the expression of BMAL1 and further activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway to attenuate brain injury after ICH.

Conclusions

These results reveal that BMAL1 serves as a neuroprotective agent in ICH and upregulation of BMAL1 attenuates ICH-induced SBI. Therefore, BMAL1 may be a promising therapeutic target for SBI following ICH.

Neuroprotective effects of adipose‐derived stem cells on ferrous sulfate‐induced neurotoxicity

Background:

Ferrous ion, a degradation product of hematomas, induces inflammatory reactions and other secondary injuries after intracerebral hemorrhage (ICH). Our study aimed to investigate the specific neuroprotective mechanism of adipose‐derived stem cells (ADSCs) on ferrous ion‐induced neural injury in vitro.

Methods:

ADSCs were co‐cultured with primary cortical neurons in a transwell system treated with ferrous sulfate to generate an in vitro ICH model. ADSCs and cortical neurons were cultured in the upper and lower chambers, respectively. Neuron apoptosis was determined by flow cytometry. The levels of insulin‐like growth factor‐1 (IGF‐1), malondialdehyde (MDA) and nitric oxide synthase (NOS) activity in neuron culture medium were detected with commercial kits. In neurons, protein expression in phosphatidylinositol‐3‐kinase (PI3K)/protein kinase B (Akt) signaling pathway, nuclear factor erythroid 2‐related factor 2 (Nrf2)/heme oxygenase‐1 (HO‐1) signaling pathway and apoptosis‐related proteins were detected by western blot.

Results:

ADSCs attenuated neural apoptosis, reduced MDA levels and NOS activity induced by ferrous sulfate. In neurons, IGF‐1 was increased, as were p‐PI3K, p‐Akt, Nrf2, HO‐1, and Bcl‐2 while cleaved caspase 3 was down‐regulated.

Conclusions:

ADSCs exert neuroprotective effects against ferrous iron‐induced neuronal damage by secreting IGF‐1 and increasing the levels of Akt‐dependent Nrf2/ARE signaling pathway.

Exogenous Carbon Monoxide Produces Rapid Antidepressant- and Anxiolytic-Like Effects

Carbon monoxide (CO), a byproduct of heme catalyzed by heme oxygenase (HO), has been reported to exert antioxidant and anti-inflammatory actions, and to produce significant neuroprotective effects. The potential effects of CO and even HO on depressive-like behaviors are still poorly understood. Utilizing several approaches including adeno-associated virus (AAV)-mediated overexpression of HO-1, systemic CO-releasing molecules (CO-RMs), CO-rich saline or CO gas treatment procedures in combination with hydrogen peroxide (H₂O₂)-induced PC12 cell injury model, and lipopolysaccharide (LPS)-induced depression mouse model, the present study aimed to investigate the potential antidepressant- and anxiolytic-like effects of endogenous and exogenous CO administration in vivo and in vitro. The results of in vitro experiments showed that both CO-RM-3 and CO-RM-A1 pretreatment blocked H₂O₂-induced cellular injuries by increasing cell survival and decreasing cell apoptosis and necrosis. Similar to the effects of CO-RM-3 and CO-RM-A1 pretreatment, AAV-mediated HO-1 overexpression in the dorsal hippocampus produced significant antidepressant-like activities in mice under normal conditions. Further investigation showed that the CO gas treatment significantly blocked LPS-induced depressive- and anxiety-like behaviors in mice. Taken together, our results suggest that the activation of HO-1 and/or exogenous CO administration produces protective effects and exerts antidepressant- and anxiolytic-like effects. These data uncover a novel function of the HO-1/CO system that appears to be a promising therapeutic target for the treatment of depression and anxiety.

Microglia Phenotype and Intracerebral Hemorrhage: A Balance of Yin and Yang

Intracerebral hemorrhage (ICH) features extremely high rates of morbidity and mortality, with no specific and effective therapy. And local inflammation caused by the over-activated immune cells seriously damages the recovery of neurological function after ICH. Fortunately, immune intervention to microglia has provided new methods and ideas for ICH treatment. Microglia, as the resident immune cells in the brain, play vital roles in both tissue damage and repair processes after ICH. The perihematomal activated microglia not only arouse acute inflammatory responses, oxidative stress, excitotoxicity, and cytotoxicity to cause neuron death, but also show another phenotype that inhibit inflammation, clear hematoma and promote tissue regeneration. The proportion of microglia phenotypes determines the progression of brain tissue damage or repair after ICH. Therefore, microglia may be a promising and imperative therapeutic target for ICH. In this review, we discuss the dual functions of microglia in the brain after an ICH from immunological perspective, elaborate on the activation mechanism of perihematomal microglia, and summarize related therapeutic drugs researches.

Dysregulation of microRNA and Intracerebral Hemorrhage: Roles in Neuroinflammation

Intracerebral hemorrhage (ICH) is a major public health problem and devastating subtype of stroke with high morbidity and mortality. Notably, there is no effective treatment for ICH. Neuroinflammation, a pathological hallmark of ICH, contributes to both brain injury and repair and hence, it is regarded as a potential target for therapeutic intervention. Recent studies document that microRNAs, small non-coding RNA molecules, can regulate inflammatory brain response after ICH and are viable molecular targets to alter brain function. Therefore, there is an escalating interest in studying the role of microRNAs in the pathophysiology of ICH. Herein, we provide, for the first time, an overview of the microRNAs that play roles in ICH-induced neuroinflammation and identify the critical knowledge gap in the field, as it would help design future studies.

Novel therapeutics for hydrocephalus: Insights from animal models

Hydrocephalus is a cerebrospinal fluid physiological disorder that causes ventricular dilation with normal or high intracranial pressure. The current regular treatment for hydrocephalus is cerebrospinal fluid shunting, which is frequently related to failure and complications. Meanwhile, considering that the current nonsurgical treatments of hydrocephalus can only relieve the symptoms but cannot eliminate this complication caused by primary brain injuries, the exploration of more effective therapies has become the focus for many researchers. In this article, the current research status and progress of nonsurgical treatment in animal models of hydrocephalus are reviewed to provide new orientations for animal research and clinical practice.

Is the CT Blend Sign Composed of Two Parts of Blood with Different Age?

BACKGROUND

Blend sign on initial computed tomography (CT) is associated with poor outcome in patients with intracerebral hemorrhage (ICH). However, the mechanisms underlying the blend sign formation are poorly understood. The present study aimed to explore the possible mechanism of the CT blend sign in patients with ICH.

METHODS

Seventy healthy rabbits were selected to prepare an ICH model. The animals were assigned to a whole blood group + whole blood group (ww group, 50 rabbits), a whole blood + plasma group (wp group, 10 rabbits) or a whole blood + serum group (ws group, 10 rabbits). The animals of the ww group were allocated to five subgroups based on the interval between the first infusion of blood and the second one. The subgroups included ww 1 h group (with an interval of 1 h), ww 2 h group, ww 3 h group, ww 4 h group and ww 5 h group. The rabbits from each group received first infusion of 0.3 mL of whole blood into the basal ganglia area to form a hematoma. Then, they received a second infusion of the same amount of whole blood, plasma or serum into the brain to form another hematoma adjacent to the first one.

RESULTS

A hematoma with two densities on brain CT could be formed in each group after a second infusion of blood into the brain. A significant difference in CT attenuation values was observed between the hyperattenuation and the hypoattenuation in all the groups. However, only the morphological features of the hematoma in the ww group was in accordance with the CT blend sign observed in humans. The CT attenuation values in the hypodensity area of the ww 4 h group or the ww 5 h group were decreased compared with the ww 1 h group to the ww 3 h group.

CONCLUSIONS

The CT blend sign observed in humans might be composed of two parts of blood with different ages. The hypodense area might be blood with older age and the hyperdense area might be new bleeding.

TGF-β1-Mediated Activation of SERPINE1 is Involved in Hemin-Induced Apoptotic and Inflammatory Injury in HT22 Cells

BACKGROUND

Intracerebral hemorrhage (ICH) is a severe subtype of stroke with high mortality and morbidity. Serpin Family E Member 1 (SERPINE1) has been documented to be upregulated following ICH, however, the participation of SERPINE1 in the development of ICH has never been studied.

METHODS

Hemin was utilized to develop an in vitro model of ICH. Gene levels were evaluated by the use of quantitative reverse transcription polymerase chain reaction, Western blot, as well as enzyme-linked immunoassay assay. The activity of caspase-3 was determined using a commercial kit. Cell viability and apoptosis were assessed using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Terminal deoxynucleotidyl transferase (TdT) d UTP Nick-End Labeling assay.

RESULTS

SERPINE1 was upregulated in hemin-treated HT22 cells. Silencing of SERPINE1 attenuated hemin-induced inhibition of cell viability. Moreover, knockdown of SERPINE1 repressed hemin-induced apoptosis in HT22 cells, as evidenced by the decrease in the number of TUNEL positive cells, caspase-3 activity, and Bax expression, and the increase in Bcl-2 expression. Meanwhile, knockdown of SERPINE1 repressed hemin-induced inflammation in HT22 cells, as indicated by reduced levels of tumor necrosis factor-α, interleukin-6 (IL-6), IL-1β, and inducible nitric oxide synthase. We also found that transforming growth factor-beta 1 (TGF-β1) induced SERPINE1 expression in a dose-dependent manner. Besides, SERPINE1 knockdown attenuated the effects of TGF-β1 on hemin-induced neuronal damage.

CONCLUSION

TGF-β1-induced SERPINE1 activation exacerbated hemin-induced apoptosis and inflammation in HT22 cells, manifesting a novel mechanism for ICH progression.

Novel Heme Oxygenase-1 (HO-1) Inducers Based on Dimethyl Fumarate Structure

Novel heme oxygenase-1 (HO-1) inducers based on dimethyl fumarate (DMF) structure are reported in this paper. These compounds are obtained by modification of the DMF backbone. Particularly, maintaining the α, β-unsaturated dicarbonyl function as the central chain crucial for HO-1 induction, different substituted or unsubstituted phenyl rings are introduced by means of an ester or amide linkage. Symmetric and asymmetric derivatives are synthesized. All compounds are tested on a human hepatic stellate cell line LX-2 to assay their capacity for modifying HO-1 expression. Compounds 1b, 1l and 1m stand out for their potency as HO-1 inducers, being 2–3 fold more active than DMF, and for their ability to reverse reactive oxygen species (ROS) production mediated using palmitic acid (PA). These properties, coupled with a low toxicity toward LX-2 cell lines, make these compounds potentially useful for treatment of diseases in which HO-1 overexpression may counteract inflammation, such as hepatic fibrosis. Docking studies show a correlation between predicted binding free energy and experimental HO-1 expression data. These preliminary results may support the development of new approaches in the management of liver fibrosis.

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 protective effects of memantine against inflammation and impairment of endothelial tube formation induced by oxygen-glucose deprivation/reperfusion

Acute myocardial infarction (AMI) is one of the leading causes of death and disability. The dysregulation of cardiac endothelial cells plays a significant role in the pathogenesis of AMI. In the present study, we investigated the potential of memantine, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist used in the treatment of Alzheimer's disease, to mitigate the effects of ischemia-reperfusion injury in the peripheral vasculature using human umbilical cord endothelial cells (HUVECs). Previous studies have identified anti-inflammatory and antioxidant effects of memantine, but the effects of memantine on angiogenesis and microtubule formation have not been fully elucidated. Our findings indicate that pretreatment with memantine significantly reduced the expression of interleukin (IL)-6 and IL-8, which are both serum markers if AMI severity. We also demonstrate that memantine could prevent mitochondrial dysfunction and oxidative stress by rescuing mitochondrial membrane potential and reducing the production of reactive oxygen species (ROS) by NADPH oxidase-4 (NOX-4). Importantly, memantine also promoted the expression of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) antioxidant signaling pathway. Importantly, memantine pretreatment improved cell viability and prevented the decrease in microtubule formation induced by OGD/R. Through a phosphoinositide-3-kinase (PI3K) inhibition experiment, we determined that the PI3K/protein kinase B (Akt) pathway is essential for the effects of memantine on angiogenesis. Together, our findings suggest a potential role for memantine in the prevention and treatment of AMI.

Dimethyl fumarate prevents osteoclastogenesis by decreasing NFATc1 expression, inhibiting of erk and p38 MAPK phosphorylation, and suppressing of HMGB1 release

Osteoclasts are multinucleated bone-resorbing cells derived from monocyte/macrophage progenitor cells. Excessive formation and resorbing activities of osteoclasts are involved in the bone-destructive pathologies of rheumatoid arthritis and osteoporosis. Recently, it has been found that nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor for anti-oxidative stress genes, functions in osteoclastogenesis. Dimethyl fumarate (DMF) is a potent activator of Nrf2 and has been shown to inhibit osteoclastogenesis. Here, we investigated the mechanisms of this inhibition by examining the activation of several signalling pathways during the differentiation of bone marrow-derived macrophages into osteoclasts. DMF inhibited the differentiation of osteoclasts in a dose-dependent manner and suppressed the bone-resorbing activity of osteoclasts. DMF treatment decreased the expression of nuclear factor of activated T-cells cytoplasmic-1, and significantly decreased phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase in osteoclasts. We also found that DMF inhibited the extracellular release of high mobility group box 1, associated with an up-regulation of heme oxygenase-1, likely mediated through Nrf2 activation. Our results indicate that DMF inhibits osteoclast differentiation through multiple pathways.

Molecular Effects of FDA-Approved Multiple Sclerosis Drugs on Glial Cells and Neurons of the Central Nervous System

Multiple sclerosis (MS) is characterized by peripheral and central inflammatory features, as well as demyelination and neurodegeneration. The available Food and Drug Administration (FDA)-approved drugs for MS have been designed to suppress the peripheral immune system. In addition, however, the effects of these drugs may be partially attributed to their influence on glial cells and neurons of the central nervous system (CNS). We here describe the molecular effects of the traditional and more recent FDA-approved MS drugs Fingolimod, Dimethyl Fumarate, Glatiramer Acetate, Interferon-β, Teriflunomide, Laquinimod, Natalizumab, Alemtuzumab and Ocrelizumab on microglia, astrocytes, neurons and oligodendrocytes. Furthermore, we point to a possible common molecular effect of these drugs, namely a key role for NFκB signaling, causing a switch from pro-inflammatory microglia and astrocytes to anti-inflammatory phenotypes of these CNS cell types that recently emerged as central players in MS pathogenesis. This notion argues for the need to further explore the molecular mechanisms underlying MS drug action.

Akebia Saponin D ameliorated kidney injury and exerted anti-inflammatory and anti-apoptotic effects in diabetic nephropathy by activation of NRF2/HO-1 and inhibition of NF-KB pathway

Diabetic nephropathy (DN), a common microvascular complication of type 2 diabetes mellitus (T2DM), causes increasing mortality and morbidity due to its high prevalence and severe consequences. Hence, it is urgent to search for effective agents that provide new insights into novel molecular therapeutic targets for DN. This study was designed to investigate the critical role of Akebia saponin D (ASD) in kidney damage, inflammation and apoptosis of renal tubular cells in DN. To probe the protective effects of ASD on DN in vivo, diabetes mellitus model was established by intraperitoneal (ip) injection of STZ (60 mg/kg) for 5 days consecutively. Besides, HG-induced human renal tubular cells (HK-2) were used to analyze the defined effects and underlying mechanism of ASD on DN in vitro. Blood glucose, insulin, serum creatinine (Scr), blood urea nitrogen (BUN), renal injury, inflammation, oxidative stress and apoptosis of renal tubular cells were respectively measured and evaluated. ASD prevented kidney damage, improved renal function and inflammatory reaction, ameliorated oxidative stress and inhibited apoptosis of renal tubular cells in DN mice via activation of NRF2/HO-1 pathway and inhibition of NF-KB pathway.

Nrf2 and Ferroptosis: A New Research Direction for Neurodegenerative Diseases

Ferroptosis is a kind of regulated cell death (RCD) caused by the redox state disorder of intracellular microenvironment controlled by glutathione (GSH) peroxidase 4 (GPX4), which is inhibited by iron chelators and lipophilic antioxidants. In addition to classical regulatory mechanisms, new regulatory factors for ferroptosis have been discovered in recent years, such as the P53 pathway, the activating transcription factor (ATF)3/4 pathway, Beclin 1 (BECN1) pathway, and some non-coding RNA. Ferroptosis is closely related to cancer treatment, neurodegenerative diseases, ischemia–reperfusion of organ, neurotoxicity, and others, in particular, in the field of neurodegenerative diseases treatment has aroused people’s interest. The nuclear factor E2 related factor 2 (Nrf2/NFE2L2) has been proved to play a key role in neurodegenerative disease treatment and ferroptosis regulation. Ferroptosis promotes the progression of neurodegenerative diseases, while the expression of Nrf2 and its target genes (Ho-1, Nqo-1, and Trx) has been declined with aging; therefore, there is still insufficient evidence for ferroptosis and Nrf2 regulatory networks in the field of neurodegenerative diseases. In this review, we will provide a brief overview of ferroptosis regulatory mechanisms, as well as an emphasis on the mechanism of Nrf2 regulating ferroptosis. We also highlight the role of ferroptosis and Nrf2 during the process of neurodegenerative diseases and investigate a theoretical basis for further research on the relationship between Nrf2 and ferroptosis in the process of neurodegenerative diseases treatment.

Pervasive Genomic Damage in Experimental Intracerebral Hemorrhage: Therapeutic Potential of a Mechanistic-Based Carbon Nanoparticle

Therapy for intracerebral hemorrhage (ICH) remains elusive, in part dependent on the severity of the hemorrhage itself as well as multiple deleterious effects of blood and its breakdown products such as hemin and free iron. While oxidative injury and genomic damage have been seen following ICH, the details of this injury and implications remain unclear. Here, we discovered that, while free iron produced mostly reactive oxygen species (ROS)-related single-strand DNA breaks, hemin unexpectedly induced rapid and persistent nuclear and mitochondrial double-strand breaks (DSBs) in neuronal and endothelial cell genomes and in mouse brains following experimental ICH comparable to that seen with γ radiation and DNA-complexing chemotherapies. Potentially as a result of persistent DSBs and the DNA damage response, hemin also resulted in senescence phenotype in cultured neurons and endothelial cells. Subsequent resistance to ferroptosis reported in other senescent cell types was also observed here in neurons. While antioxidant therapy prevented senescence, cells became sensitized to ferroptosis. To address both senescence and resistance to ferroptosis, we synthesized a modified, catalytic, and rapidly internalized carbon nanomaterial, poly(ethylene glycol)-conjugated hydrophilic carbon clusters (PEG-HCC) by covalently bonding the iron chelator, deferoxamine (DEF). This multifunctional nanoparticle, DEF-HCC-PEG, protected cells from both senescence and ferroptosis and restored nuclear and mitochondrial genome integrity in vitro and in vivo. We thus describe a potential molecular mechanism of hemin/iron-induced toxicity in ICH that involves a rapid induction of DSBs, senescence, and the consequent resistance to ferroptosis and provide a mechanistic-based combinatorial therapeutic strategy.

Neutrophil-to-lymphocyte ratio as an independent predictor for unfavorable functional outcome in aneurysmal subarachnoid hemorrhage

OBJECTIVE

Stroke-associated immunosuppression and inflammation are increasingly recognized as factors triggering infections and thus potentially influencing outcome after stroke. Several studies have demonstrated that elevated neutrophil-to-lymphocyte ratio (NLR) is a significant predictor of adverse outcomes for patients with ischemic stroke or intracerebral hemorrhage. Thus far, in patients with subarachnoid hemorrhage the association between NLR and outcome is insufficiently established. The authors sought to investigate the association between NLR on admission and functional outcome in aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

This observational study included all consecutive aSAH patients admitted to a German tertiary center over a 5-year period (2008–2012). Data regarding patient demographics and clinical, laboratory, and in-hospital measures, as well as neuroradiological data, were retrieved from institutional databases. Functional outcome was assessed at 3 and 12 months using the modified Rankin Scale (mRS) score and categorized into favorable (mRS score 0–2) and unfavorable (mRS score 3–6). Patients’ radiological and laboratory characteristics were compared between aSAH patients with favorable and those with unfavorable outcome at 3 months. In addition, multivariate analysis was conducted to investigate parameters independently associated with favorable outcome. Receiver operating characteristic (ROC) curve analysis was undertaken to identify the best cutoff for NLR to discriminate between favorable and unfavorable outcome in these patients. To account for imbalances in baseline characteristics, propensity score matching was carried out to assess the influence of NLR on outcome measures.

RESULTS

Overall, 319 patients with aSAH were included. Patients with unfavorable outcome at 3 months were older, had worse clinical status on admission (Glasgow Coma Scale score and Hunt and Hess grade), greater amount of subarachnoidal and intraventricular hemorrhage (modified Fisher Scale grade and Graeb score), and higher rates of infectious complications (pneumonia and sepsis). A significantly higher NLR on admission was observed in patients with unfavorable outcome according to mRS score (median [IQR] NLR 5.8 [3.0–10.0] for mRS score 0–2 vs NLR 8.3 [4.5–12.6] for mRS score 3–6; p < 0.001). After adjustments, NLR on admission remained a significant predictor for unfavorable outcome in SAH patients (OR [95% CI] 1.014 [1.001–1.027]; p = 0.028). In ROC analysis, an NLR of 7.05 was identified as the best cutoff value to discriminate between favorable and unfavorable outcome (area under the curve = 0.614, p < 0.001, Youden’s index = 0.211; mRS score 3–6: 94/153 [61.4%] for NLR ≥ 7.05 vs 67/166 [40.4%] for NLR < 7.05; p < 0.001). Subanalysis of patients with NLR levels ≥ 7.05 vs < 7.05, performed using 2 propensity score–matched cohorts (n = 133 patients in each group), revealed an increased proportion of patients with unfavorable functional outcome at 3 months in patients with NLR ≥ 7.05 (mRS score 3–6 at 3 months: NLR ≥ 7.05 82/133 [61.7%] vs NLR < 7.05 62/133 [46.6%]; p = 0.014), yet without differences in mortality at 3 months (NLR ≥ 7.05 37/133 [27.8%] vs NLR < 7.05 27/133 [20.3%]; p = 0.131).

CONCLUSIONS

Among aSAH patients, NLR represents an independent parameter associated with unfavorable functional outcome. Whether the impact of NLR on functional outcome is related to preexisting comorbidities or represents independent causal relationships in the context of stroke-associated immunosuppression should be investigated in future studies.

Akebia Saponin D suppresses inflammation in chondrocytes via the NRF2/HO-1/NF-κB axis and ameliorates osteoarthritis in mice

Akebia Saponin D promotes the translocation of NRF2 into nucleus, activates NRF2/HO-1 pathway and inhibits NF-κB pathway in chondrocytes, and ultimately alleviates osteoarthritis development.

Methyl Jasmonate Protects Microglial Cells Against β-Amyloid-Induced Oxidative Stress and Inflammation via Nrf2-Dependent HO-1 Pathway

BACKGROUND

β-Amyloid (Aβ) induces oxidative stress and inflammation of microglial cells, thus leading to Alzheimer's disease. Methyl jasmonate (MeJA) is reported to have anti-inflammatory and anti-oxidant effects. However, the potential roles of MeJA in Aβ-induced cell activities and the underlying mechanism are unclear.

METHODS

Microglial cell line BV-2 was stimulated by 20 μM Aβ and/or 20 μM MeJA and then divided into four groups (control, Aβ, MeJA, and Aβ+MeJA). Cell viability was detected by MTT assay. MDA, SOD activity, and ROS were detected by fluorescence spectrophotometry and immunofluorescence assay. Nrf2 and HO-1 were detected by qRT-PCR and Western blot. Furthermore, inflammatory cytokines (p-NFκB, TLR4, TNF-α, IL-1β, and IL-6) and apoptosis factors (Bcl-2, Bax, and cl-casp-3) were detected by Western blot. TUNEL assay was applied to investigate apoptosis rate. Moreover, the mechanism of how MeJA played anti-oxidative stress and anti-inflammatory roles was investigated by silencing of Nrf2 via siRNA.

RESULTS

The result of MTT assay showed that MeJA improved the decreased viability of BV-2 cells induced by Aβ. The detection of MDA, SOD activity, and ROS showed the oxidative stress levels were decreased in Aβ+MeJA group compared with Aβ group. Nrf2, HO-1, and SOD were significantly up-regulated in Aβ+MeJA group compared with Aβ group (p<0.01). In contrast, inflammatory cytokines were significantly down-regulated in Aβ+MeJA group compared with Aβ group (p<0.05). Similarly, the expressions of apoptosis cytokines and TUNEL assay suggested a decreased apoptosis rate in Aβ+MeJA group compared to Aβ group (p<0.01). Finally, results of Nrf2 knockdown experiment showed down-regulations of anti-oxidative stress factors (Nrf2, HO-1 and SOD), up-regulations of inflammatory cytokines, and increased ratio of Bax to Bcl in Aβ+MeJA+si-Nrf2 group compared with Aβ+MeJA group (p<0.01).

CONCLUSION

MeJA could relieve Aβ-induced oxidative stress and inflammatory response in microglial cells by activating Nrf2/HO-1 pathway.

Time-dependent hemeoxygenase-1, lipocalin-2 and ferritin induction after non-contusion traumatic brain injury

Traumatic brain injury (TBI) often presents with focal contusion and parenchymal bleeds, activating heme oxygenase (HO) to degrade released hemoglobin. Here we show that diffuse, midline fluid percussion injury causes time-dependent induction of HO-1 and iron binding proteins within both hemorrhagic neocortex and non-hemorrhagic hippocampus. Rats subjected to midline fluid percussion injury (FPI) survived 1-15d postinjury and tissue was collected for Western blot and immunohistochemical assays. HO-1 was elevated 1d after FPI, peaked at 3d, and returned to control baseline 7-15d. Iron management proteins lipocalin 2 (LCN2) and ferritin (FTL) exhibited distinct postinjury time courses, where peak LCN2 response preceded, and FTL followed that of HO-1. LCN2 elevation supported not only its role in iron transport, but also mediation of matrix metalloproteinase 9 (MMP9) activity. Upregulation of FTL for intracellular iron sequestration was delayed relative to both HO-1 and LCN2 induction. In the neocortex IBA-1+ microglia around the injury core expressed HO-1, but astrocytes co-localized with HO-1 in perilesional parenchyma. Non-hemorrhagic dentate gyrus showed predominant HO-1 labeling in hilar microglia and in molecular layer astrocytes. At 1d postinjury, LCN2 and HO-1 co-localized in a subpopulation of reactive glia within both brain regions. Notably, FTL was distributed within cells around injured vessels, damaged subcortical white matter, and along vessels of the hippocampal fissure. Together these results confirm that even the moderate, non-contusional insult of diffuse midline FPI can significantly activate postinjury HO-1 heme processing pathways and iron management proteins. Moreover, this activation is time-dependent and occurs in the absence of overt hemorrhage.

The role and therapeutic potential of heat shock proteins in haemorrhagic stroke

Heat shock proteins (HSPs) are induced after haemorrhagic stroke, which includes subarachnoid haemorrhage (SAH) and intracerebral haemorrhage (ICH). Most of these proteins function as neuroprotective molecules to protect cerebral neurons from haemorrhagic stroke and as markers to indicate cellular stress or damage. The most widely studied HSPs in SAH are HSP70, haeme oxygenase-1 (HO-1), HSP20 and HSP27. The subsequent pathophysiological changes following SAH can be divided into two stages: early brain injury and delayed cerebral ischaemia, both of which determine the outcome for patients. Because the mechanisms of HSPs in SAH are being revealed and experimental models in animals are continually maturing, new agents targeting HSPs with limited side effects have been suggested to provide therapeutic potential. For instance, some pharmaceutical agents can block neuronal apoptosis signals or dilate cerebral vessels by modulating HSPs. HO-1 and HSP70 are also critical topics for ICH research, which can be attributed to their involvement in pathophysiological mechanisms and therapeutic potential. However, the process of HO-1 metabolism can be toxic owing to iron overload and the activation of succedent pathways, for example, the Fenton reaction and oxidative damage; the overall effect of HO-1 in SAH and ICH tends to be protective and harmful, respectively, given the different pathophysiological changes in these two types of haemorrhagic stroke. In the present study, we focus on the current understanding of the role and therapeutic potential of HSPs involved in haemorrhagic stroke. Therefore, HSPs may be potential therapeutic targets, and new agents targeting HSPs are warranted.

Rapid loss of perihematomal cell viability in the collagenase intracerebral hemorrhage model

The effective time window of any therapeutic in an experimental stroke model is limited by the rate of injury progression. Intracerebral hemorrhage in rodents is commonly induced by striatal injection of either autologous blood or bacterial collagenase, which digests local blood vessels. During time window studies of the heme oxygenase-1 inducer hemin, which is protective when administered within 1-3 h in both models, the rate of perihematomal injury was directly compared after striatal blood or collagenase injection. Surprisingly, about 80% of the loss of perihematomal cell viability as measured by MTT reduction assay occurred within 6 h of collagenase injection. In contrast, significant viability loss was not observed at this time point after autologous blood injection, but rather it progressed over the subsequent four days to a level similar to that produced by collagenase. Consistent with these observations, systemic hemin therapy reduced blood-brain barrier disruption and perihematomal cell injury when initiated at 6 h after striatal injection of blood but not collagenase. These results indicate that the rate of early cell injury differs markedly in the collagenase and blood injection ICH models, which may contribute to inconsistent results in time window studies. The blood injection model may be more appropriate for prolonged time window studies of a neuroprotective agent.

Research Progress in Understanding the Relationship Between Heme Oxygenase-1 and Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a fatal acute cerebrovascular disease, with a high morbidity and mortality. Following ICH, erythrocytes release heme and several of its metabolites, thereby contributing to brain edema and secondary brain damage. Heme oxygenase is the initial and rate-limiting enzyme of heme catabolism, and the expression of heme oxygenase-1 (HO-1) is rapidly induced following acute brain injury. As HO-1 exerts it effects via various metabolites, its role during ICH remains complex. Therefore, in-depth studies regarding the role of HO-1 in secondary brain damage following ICH may provide a theoretical basis for neuroprotective function after ICH. The present review aims to summarize recent key studies regarding the effects of HO-1 following ICH, as well as its influence on ICH prognosis.

Neutrophil-to-Lymphocyte Ratio Is an Independent Predictor for In-Hospital Mortality in Spontaneous Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Stroke-associated immunosuppression and inflammation are increasingly recognized as factors that trigger infections and thus, potentially influence the outcome after stroke. Several studies demonstrated that elevated neutrophil-to-lymphocyte ratio (NLR) is a significant predictor of adverse outcomes in patients with ischemic stroke. However, little is known about the impact of NLR on short-term mortality in intracerebral hemorrhage (ICH).

METHODS

This observational study included 855 consecutive ICH-patients. Patient demographics, clinical, laboratory, and in-hospital measures as well as neuroradiological data were retrieved from institutional databases. Functional 3-months-outcome was assessed and categorized as favorable (modified Rankin Scale [mRS] 0-3) and unfavorable (mRS 4-6). We (i) studied the natural course of NLR in ICH, (ii) analyzed parameters associated with NLR on admission (NLROA), and (iii) evaluated the clinical impact of NLR on mortality and functional outcome.

RESULTS

The median NLROA of the entire cohort was 4.66 and it remained stable during the entire hospital stay. Patients with NLR ≥4.66 showed significant associations with poorer neurological status (National Institute of Health Stroke Scale [NIHSS] 18 [9-32] vs. 10 [4-21]; p < 0.001), larger hematoma volume on admission (17.6 [6.9-47.7] vs. 10.6 [3.8-31.7] mL; p = 0.001), and more frequently unfavorable outcome (mRS 4-6 at 3 months: 317/427 [74.2%] vs. 275/428 [64.3%]; p = 0.002). Patients with an NLR under the 25th percentile (NLR <2.606) - compared to patients with NLR >2.606 - presented with a better clinical status (NIHSS 12 [5-21] vs. 15 [6-28]; p = 0.005), lower hematoma volumes on admission (10.6 [3.6-30.1] vs. 15.1 [5.7-42.3] mL; p = 0.004) and showed a better functional outcome (3 months mRS 0-3: 82/214 [38.3%] vs. 185/641 [28.9%]; p = 0.009). Patients associated with high NLR (≥8.508 = above 75th-percentile) showed the worst neurological status on admission (NIHSS 21 [12-32] vs. 12 [5-23]; p < 0.001), larger hematoma volumes (21.0 [8.6-48.8] vs. 12.2 [4.1-34.9] mL; p < 0.001), and higher proportions of unfavorable functional outcome at 3 months (mRS 4-6: 173/214 vs. 418/641; p < 0.001). Further, NLR was linked to more frequently occurring infectious complications (pneumonia 107/214 vs. 240/641; p = 0.001, sepsis: 78/214 vs. 116/641; p < 0.001), and increased c-reactive-protein levels on admission (p < 0.001; R2 = 0.064). Adjusting for the above-mentioned baseline confounders, multivariable logistic analyses revealed independent associations of NLROA with in-hospital mortality (OR 0.967, 95% CI 0.939-0.997; p = 0.029).

CONCLUSIONS

NLR represents an independent parameter associated with increased mortality in ICH patients. Stroke physicians should focus intensely on patients with increased NLR, as these patients appear to represent a population at risk for infectious complications and increased short-mortality. Whether these patients with elevated NLR may benefit from a close monitoring and specially designed therapies should be investigated in future studies.

Astrocyte heme oxygenase-1 reduces mortality and improves outcome after collagenase-induced intracerebral hemorrhage

Pharmacotherapies that increase CNS expression of heme oxygenase-1 (HO-1) and other antioxidant proteins have improved outcome in experimental models of spontaneous intracerebral hemorrhage (ICH). In order to more specifically investigate the relationship between HO-1 and ICH outcome, mice expressing human HO-1 driven by the glial fibrillary acidic protein (GFAP) promoter (GFAP·HMOX1 mice) were tested in a model of in situ parenchymal hemorrhage. Injection of collagenase into the striata of wild-type (WT) mice resulted in a 26.3% mortality rate, with deaths equally distributed between males and females. Mortality was reduced to 4.48% in GFAP·HMOX1 mice. Cell viability in the injected striata of surviving WT mice was reduced by about half at one week and was significantly increased in transgenics; this benefit persisted over a 22day observation period. Cell counts guided by design-based stereology indicated loss of ~40% of neurons in WT hemorrhagic striata at one week, which was decreased by half in transgenics; no significant differences in microglia or astrocyte numbers were observed. Blood-brain barrier disruption and short-term neurological deficits were also mitigated in GFAP·HMOX1 mice, but long-term outcome did not differ from that of WT survivors. These results suggest that astrocyte HO-1 overexpression provides robust neuroprotection after acute intracerebral hemorrhage. Further investigation of drug or genetic therapies that selectively increase astrocyte HO-1 is warranted.