Distinct role of heme oxygenase-1 in early- and late-stage intracerebral hemorrhage in 12-month-old mice

CircTrim37 Ameliorates Intracerebral Hemorrhage Outcomes by Modulating Microglial Polarization via the miR-30c-5p/SOCS3 Axis

Circular RNAs (circRNAs) have been progressively recognized as critical regulators in the pathology and pathophysiology of central nervous system disease. However, the potential role of circRNAs in intracerebral hemorrhage (ICH) is still largely unclear. Here, we demonstrate that circTrim37 expression was significantly upregulated at 3 days after ICH by circular RNA microarray and qPCR assays. Overexpression of circTrim37 could significantly ameliorate brain injury volume, brain edema, neurologic deficits, and inflammation in vivo after ICH. CircTrim37 promotes M2 polarization while restrains M1 polarization in vitro. Furthermore, circTrim37 acts as an endogenous sponge for miR-30c-5p, thereby inhibiting miR-30c-5p activity, leading to the upregulation of SOCS3 and making the balance of microglial response towards an M2 phenotype. Taken together, our results indicate the participation of circTrim37 and its coupling mechanism in ICH and provide a novel therapeutic target for ICH.

Microglial SLC25A28 Deficiency Ameliorates the Brain Injury After Intracerebral Hemorrhage in Mice by Restricting Aerobic Glycolysis

The microglia overactivation-induced neuroinflammation is a significant cause of the brain injury after intracerebral hemorrhage (ICH). Iron homeostasis is crucial for microglia activation, but the mechanism and causality still need further study. This study aimed to explore the roles and mechanism of the mitochondrial iron transporter SLC25A28 in microglia activation after ICH. Intrastriatal injection of autologous blood was used to establish ICH model, and the neuroinflammation, iron metabolism and brain injuries were assessed in wildtype or microglia-specific SLC25A28 knockout mice after ICH. Mitochondria iron levels and microglial function were determined in SLC25A28 overexpressed or deleted microglia. The extracellular acidification rate (ECAR), lactate production, and glycolytic enzyme levels were used to determine aerobic glycolysis. The results showed that ICH stimulated mitochondrial iron overload, and synchronously upregulated the SLC25A28 expression. In vitro, SLC25A28 overexpression increased mitochondrial iron levels in microglia. Interestingly, microglial SLC25A28 deficiency ameliorated neuroinflammation, brain edema, blood-brain barrier injury and ethological alterations in mice after ICH. Mechanically, SLC25A28 deficiency inhibited microglial activation by restricting the aerobic glycolysis. Moreover, zinc protoporphyrin could reduce SLC25A28 expression and mitigated brain injury. SLC25A28 plays crucial roles in mitochondrial iron homeostasis and microglia activation after ICH, and it might be a potential therapeutic target for ICH.

Microglial FoxO3a deficiency ameliorates ferroptosis-induced brain injury of intracerebral haemorrhage via regulating autophagy and heme oxygenase-1

Microglial HO-1 regulates iron metabolism in the brain. Intracerebral haemorrhage (ICH) shares features of ferroptosis and necroptosis; hemin is an oxidized product of haemoglobin from lysed red blood cells, leading to secondary injury. However, little is known about the underlying molecular mechanisms attributable to secondary injury by hemin or ICH. In this study, we first show that FoxO3a was highly co-located with neurons and microglia but not astrocytes area of ICH model mice. Hemin activated FoxO3a/ATG-mediated autophagy and HO-1 signalling resulting in ferroptosis in vitro and in a mice model of brain haemorrhage. Accordingly, autophagy inhibitor Baf-A1 or HO-1 inhibitor ZnPP protected against hemin-induced ferroptosis. Hemin promoted ferroptosis of neuronal cells via FoxO3a/ATG-mediated autophagy and HO-1 signalling pathway. Knock-down of FoxO3a inhibited autophagy and prevented hemin-induced ferroptosis dependent of HO-1 signalling. We first showed that hemin stimulated microglial FoxO3a/HO-1 expression and enhanced the microglial polarisation towards the M1 phenotype, while knockdown of microglial FoxO3a inhibited pro-inflammatory cytokine production in microglia. Furthermore, the microglia activation in the striatum showed significant along with a high expression level of FoxO3a in the ICH mice. We found that conditional knockout of FoxO3a in microglia in mice alleviated neurological deficits and microglia activation as well as ferroptosis-induced striatum injury in the autologous blood-induced ICH model. We demonstrate, for the first time, that FoxO3a/ATG-mediated autophagy and HO-1 play an important role in microglial activation and ferroptosis-induced striatum injury of ICH, identifying a new therapeutic avenue for the treatment of ICH.

Hmox1 is Identified as a Ferroptosis Hub Gene and Associated with the M1 Type Microglia/Macrophage Polarization in Spinal Cord Injury: Bioinformatics and Experimental Validation

Ferroptosis and immune cell infiltration are important pathological events in spinal cord injury (SCI), but links between ferroptosis and immune microenvironment after SCI were rare reported. In our study, 77 FRDEGs were screened at 7 days after SCI. GO analysis of FRDEGs showed that aging (GO:0007568; P-value = 1.11E-05) was the most remarkable enriched for biological process, protein binding (GO:0005515; adjusted P-value = 4.44E-06) was the most significantly enriched for molecular function, cytosol (GO:0005829; adjusted P-value = 1.51E-04) was the most prominent enriched for cellular component. Meanwhile, Ferroptosis was significantly enriched both in KEGG (rno04216; adjusted P-value = 0.001) and GSEA (NES = 1.35; adjusted P-value = 0.004) analysis. Next, Hmox1 (Log2Fold change = 6.52; adjusted P-value = 0.004) was identified as one of hub genes in SCI-induced ferroptosis. In the results of immune cell infiltration analysis, proportion of microglia/macrophage was significantly increased after SCI, and Hmox1 was found to positively correlate to the M1 type microglia/macrophage abundance. Finally, effects of Hmox1 on ferroptosis and M1 type polarization were validated in vivo and in vitro. Summarily, we found that Hmox1 was the hub gene in SCI-induced ferroptosis and associated with the M1 type polarization.

Iron homeostasis imbalance and ferroptosis in brain diseases

Brain iron homeostasis is maintained through the normal function of blood-brain barrier and iron regulation at the systemic and cellular levels, which is fundamental to normal brain function. Excess iron can catalyze the generation of free radicals through Fenton reactions due to its dual redox state, thus causing oxidative stress. Numerous evidence has indicated brain diseases, especially stroke and neurodegenerative diseases, are closely related to the mechanism of iron homeostasis imbalance in the brain. For one thing, brain diseases promote brain iron accumulation. For another, iron accumulation amplifies damage to the nervous system and exacerbates patients' outcomes. In addition, iron accumulation triggers ferroptosis, a newly discovered iron-dependent type of programmed cell death, which is closely related to neurodegeneration and has received wide attention in recent years. In this context, we outline the mechanism of a normal brain iron metabolism and focus on the current mechanism of the iron homeostasis imbalance in stroke, Alzheimer's disease, and Parkinson's disease. Meanwhile, we also discuss the mechanism of ferroptosis and simultaneously enumerate the newly discovered drugs for iron chelators and ferroptosis inhibitors.

Pharmacological Inhibition of Ferroptosis as a Therapeutic Target for Neurodegenerative Diseases and Strokes

Emerging evidence suggests that ferroptosis, a unique regulated cell death modality that is morphologically and mechanistically different from other forms of cell death, plays a vital role in the pathophysiological process of neurodegenerative diseases, and strokes. Accumulating evidence supports ferroptosis as a critical factor of neurodegenerative diseases and strokes, and pharmacological inhibition of ferroptosis as a therapeutic target for these diseases. In this review article, the core mechanisms of ferroptosis are overviewed and the roles of ferroptosis in neurodegenerative diseases and strokes are described. Finally, the emerging findings in treating neurodegenerative diseases and strokes through pharmacological inhibition of ferroptosis are described. This review demonstrates that pharmacological inhibition of ferroptosis by bioactive small-molecule compounds (ferroptosis inhibitors) could be effective for treatments of these diseases, and highlights a potential promising therapeutic avenue that could be used to prevent neurodegenerative diseases and strokes. This review article will shed light on developing novel therapeutic regimens by pharmacological inhibition of ferroptosis to slow down the progression of these diseases in the future.

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.

Exploring a shared genetic signature and immune infiltration between spontaneous intracerebral hemorrhage and Helicobacter pylori infection

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) is a devastating form of stroke with high morbidity, disability and mortality. Helicobacter pylori is a major pathogen responsible for chronic gastritis, leading to gastric ulcers and ultimately gastric cancer. Although it remains controversial whether H. pylori infection causes peptic ulcers under various traumatic stimuli, some related studies suggest that H. pylori infection may be an important factor in delaying peptic ulcer healing. However, the linking mechanism between ICH and H. pylori infection remain unclear. The purpose of this study was to examine the genetic features and pathways shared in ICH and H. pylori infection, and compare immune infiltration.

METHODS

We used microarray data for ICH and H. pylori infection from the Gene Expression Omnibus (GEO) database. Differential gene expression analysis was performed on both datasets using the R software and the limma package to find the common differentially expressed genes (DEGs). In addition, we performed functional enrichment analysis on DEGs, determined protein-protein interactions (PPIs), identified Hub genes using the STRING database and Cytoscape software, and constructed microRNA-messenger RNA (miRNA-mRNA) interaction networks. Additionally, immune infiltration analysis was performed with the R software and related R packages.

RESULTS

A total of 72 DEGs were identified between ICH and H. pylori infection, including 68 upregulated genes and 4 downregulated genes. Functional enrichment analysis revealed that multiple signaling pathways are closely linked to both diseases. In addition, the cytoHubba plugin identified 15 important hub genes, namely PLEK, NCF2, CXCR4, CXCL1, FGR, CXCL12, CXCL2, CD69, NOD2, RGS1, SLA, LCP1, HMOX1, EDN1, and ITGB3.Also, the correlation analysis of immune cell fractions revealed a limited link between their immune-related common genes and immune cells.

CONCLUSION

Through bioinformatics methods, this study revealed that there are common pathways and hub genes between ICH and H. pylori infection. Thus, H. pylori infection may have common pathogenic mechanisms with the development of peptic ulcer after ICH. This study provided new ideas for early diagnosis and prevention of ICH and H. pylori infection.

Research progress of endogenous hematoma absorption after intracerebral hemorrhage

Non-traumatic intraparenchymal brain hemorrhage is referred to as intracerebral hemorrhage (ICH). Although ICH is associated with a high rate of disability and case fatality, active intervention can significantly lower the rate of severe disability. Studies have shown that the speed of hematoma clearance after ICH determines the patient's prognosis. Following ICH, depending on the hematoma volume and mass effect, either surgical- or medication-only conservative treatment is chosen. The goal of promoting endogenous hematoma absorption is more relevant because surgery is only appropriate for a small percentage of patients, and open surgery can cause additional trauma to patients. The primary method of removing hematoma after ICH in the future will involve understanding how to produce and manage macrophage/microglial endogenous phagocytic hematomas. Therefore, it is necessary to elucidate the regulatory mechanisms and key targets for clinical purposes.

Augmenting hematoma-scavenging capacity of innate immune cells by CDNF reduces brain injury and promotes functional recovery after intracerebral hemorrhage

During intracerebral hemorrhage (ICH), hematoma formation at the site of blood vessel damage results in local mechanical injury. Subsequently, erythrocytes lyse to release hemoglobin and heme, which act as neurotoxins and induce inflammation and secondary brain injury, resulting in severe neurological deficits. Accelerating hematoma resorption and mitigating hematoma-induced brain edema by modulating immune cells has potential as a novel therapeutic strategy for functional recovery after ICH. Here, we show that intracerebroventricular administration of recombinant human cerebral dopamine neurotrophic factor (rhCDNF) accelerates hemorrhagic lesion resolution, reduces peri-focal edema, and improves neurological outcomes in an animal model of collagenase-induced ICH. We demonstrate that CDNF acts on microglia/macrophages in the hemorrhagic striatum by promoting scavenger receptor expression, enhancing erythrophagocytosis and increasing anti-inflammatory mediators while suppressing the production of pro-inflammatory cytokines. Administration of rhCDNF results in upregulation of the Nrf2-HO-1 pathway, but alleviation of oxidative stress and unfolded protein responses in the perihematomal area. Finally, we demonstrate that intravenous delivery of rhCDNF has beneficial effects in an animal model of ICH and that systemic application promotes scavenging by the brain's myeloid cells for the treatment of ICH.

Roles of Bilirubin in Hemorrhagic Transformation of Different Types and Severity

BACKGROUND

Hemorrhagic transformation (HT) is a severe complication in patients with acute ischemic stroke (AIS). This study was performed to explore and validate the relation between bilirubin levels and spontaneous HT (sHT) and HT after mechanical thrombectomy (tHT).

METHODS

The study population consisted of 408 consecutive AIS patients with HT and age- and sex-matched patients without HT. All patients were divided into quartiles according to total bilirubin (TBIL) level. HT was classified as hemorrhagic infarction (HI) and parenchymal hematoma (PH) based on radiographic data.

RESULTS

In this study, the baseline TBIL levels were significantly higher in the HT than non-HT patients in both cohorts (p < 0.001). Furthermore, the severity of HT increased with increasing TBIL levels (p < 0.001) in sHT and tHT cohorts. The highest quartile of TBIL was associated with HT in sHT and tHT cohorts (sHT cohort: OR = 3.924 (2.051-7.505), p < 0.001; tHT cohort: OR = 3.557 (1.662-7.611), p = 0.006).

CONCLUSIONS

Our results suggest that an increased TBIL is associated with a high risk of patients with sHT and tHT, and that TBIL is more suitable as a predictor for sHT than tHT. These findings may help to identify patients susceptible to different types and severity of HT.

Molecular, Pathological, Clinical, and Therapeutic Aspects of Perihematomal Edema in Different Stages of Intracerebral Hemorrhage

Acute intracerebral hemorrhage (ICH) is a devastating type of stroke worldwide. Neuronal destruction involved in the brain damage process caused by ICH includes a primary injury formed by the mass effect of the hematoma and a secondary injury induced by the degradation products of a blood clot. Additionally, factors in the coagulation cascade and complement activation process also contribute to secondary brain injury by promoting the disruption of the blood-brain barrier and neuronal cell degeneration by enhancing the inflammatory response, oxidative stress, etc. Although treatment options for direct damage are limited, various strategies have been proposed to treat secondary injury post-ICH. Perihematomal edema (PHE) is a potential surrogate marker for secondary injury and may contribute to poor outcomes after ICH. Therefore, it is essential to investigate the underlying pathological mechanism, evolution, and potential therapeutic strategies to treat PHE. Here, we review the pathophysiology and imaging characteristics of PHE at different stages after acute ICH. As illustrated in preclinical and clinical studies, we discussed the merits and limitations of varying PHE quantification protocols, including absolute PHE volume, relative PHE volume, and extension distance calculated with images and other techniques. Importantly, this review summarizes the factors that affect PHE by focusing on traditional variables, the cerebral venous drainage system, and the brain lymphatic drainage system. Finally, to facilitate translational research, we analyze why the relationship between PHE and the functional outcome of ICH is currently controversial. We also emphasize promising therapeutic approaches that modulate multiple targets to alleviate PHE and promote neurologic recovery after acute ICH.

Withaferin A inhibits ferroptosis and protects against intracerebral hemorrhage

Recent studies have indicated that suppressing oxidative stress and ferroptosis can considerably improve the prognosis of intracerebral hemorrhage (ICH). Withaferin A (WFA), a natural compound, exhibits a positive effect on a number of neurological diseases. However, the effects of WFA on oxidative stress and ferroptosis-mediated signaling pathways to ICH remain unknown. In this study, we investigated the neuroprotective effects and underlying mechanism for WFA in the regulation of ICH-induced oxidative stress and ferroptosis. We established a mouse model of ICH by injection of autologous tail artery blood into the caudate nucleus and an in vitro cell model of hemin-induced ICH. WFA was injected intracerebroventricularly at 0.1, 1 or 5 µg/kg once daily for 7 days, starting immediately after ICH operation. WFA markedly reduced brain tissue injury and iron deposition and improved neurological function in a dose-dependent manner 7 days after cerebral hemorrhage. Through in vitro experiments, cell viability test showed that WFA protected SH-SY5Y neuronal cells against hemin-induced cell injury. Enzyme-linked immunosorbent assays in vitro and in vivo showed that WFA markedly decreased the level of malondialdehyde, an oxidative stress marker, and increased the activities of anti-oxidative stress markers superoxide dismutase and glutathione peroxidase after ICH. Western blot assay, quantitative polymerase chain reaction and immunofluorescence results demonstrated that WFA activated the nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling axis, promoted translocation of Nrf2 from the cytoplasm to nucleus, and increased HO-1 expression. Silencing Nrf2 with siRNA completely reversed HO-1 expression, oxidative stress and protective effects of WFA. Furthermore, WFA reduced hemin-induced ferroptosis. However, after treatment with an HO-1 inhibitor, the neuroprotective effects of WFA against hemin-induced ferroptosis were weakened. MTT test results showed that WFA combined with ferrostatin-1 reduced hemin-induced SH-SY5Y neuronal cell injury. Our findings reveal that WFA treatment alleviated ICH injury-induced ferroptosis and oxidative stress through activating the Nrf2/HO-1 pathway, which may highlight a potential role of WFA for the treatment of ICH.

Leptin Promotes Angiogenesis via Pericyte STAT3 Pathway upon Intracerebral Hemorrhage

Angiogenesis is a vital endogenous brain self-repair processes for neurological recovery after intracerebral hemorrhage (ICH). Increasing evidence suggests that leptin potentiates angiogenesis and plays a beneficial role in stroke. However, the proangiogenic effect of leptin on ICH has not been adequately explored. Moreover, leptin triggers post-ICH angiogenesis through pericyte, an important component of forming new blood vessels, which remains unclear. Here, we reported that exogenous leptin infusion dose-dependent promoted vascular endothelial cells survival and proliferation at chronic stage of ICH mice. Additionally, leptin robustly ameliorated pericytes loss, enhanced pericytes proliferation and migration in ICH mice in vivo, and in ICH human brain microvascular pericytes (HBVPC) in vitro. Notably, we showed that pericytes-derived pro-angiogenic factors were responsible for enhancing the survival, proliferation and tube formation followed leptin treatment in human brain microvascular endothelial cells (HCMEC/D3)/HBVPC co-culture models. Importantly, considerable improvements in neurobehavioral function and hostile microenvironment were observed in leptin treatment ICH mice, indicating that better vascular functionality post ICH improves outcome. Mechanistically, this study unveiled that leptin boost post-ICH angiogenesis potentially through modulation of leptin receptor (leptinR)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway in pericyte. Thus, leptin may be a lucrative option for the treatment of ICH.

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.

Microglia Phenotypes in Aging and Neurodegenerative Diseases

Neuroinflammation is a hallmark of many neurodegenerative diseases (NDs) and plays a fundamental role in mediating the onset and progression of disease. Microglia, which function as first-line immune guardians of the central nervous system (CNS), are the central drivers of neuroinflammation. Numerous human postmortem studies and in vivo imaging analyses have shown chronically activated microglia in patients with various acute and chronic neuropathological diseases. While microglial activation is a common feature of many NDs, the exact role of microglia in various pathological states is complex and often contradictory. However, there is a consensus that microglia play a biphasic role in pathological conditions, with detrimental and protective phenotypes, and the overall response of microglia and the activation of different phenotypes depends on the nature and duration of the inflammatory insult, as well as the stage of disease development. This review provides a comprehensive overview of current research on the various microglia phenotypes and inflammatory responses in health, aging, and NDs, with a special emphasis on the heterogeneous phenotypic response of microglia in acute and chronic diseases such as hemorrhagic stroke (HS), Alzheimer’s disease (AD), and Parkinson’s disease (PD). The primary focus is translational research in preclinical animal models and bulk/single-cell transcriptome studies in human postmortem samples. Additionally, this review covers key microglial receptors and signaling pathways that are potential therapeutic targets to regulate microglial inflammatory responses during aging and in NDs. Additionally, age-, sex-, and species-specific microglial differences will be briefly reviewed.

Heme Oxygenase-1 may Mediate Early Inflammatory Response of Intracerebral Hemorrhage through Toll-like Receptor 4 Signaling Pathway

OBJECTIVE

The aim of this study was to investigate whether heme oxygenase-1 (HO-1) promotes an early neuroinflammatory response after intracerebral hemorrhage (ICH) by regulating the toll-like receptor 4 (TLR4) signaling pathway.

METHODS

We used a stereotaxic instrument to induce a mouse model of ICH through collagenase. We divided the participants into a control group, an ICH group, and an ICH and zinc protoporphyrin IX (ZnPP) group. The temporal expression pattern and cell localization of HO-1 and TLR4 after the ICH were detected by immunofluorescence and western blot; after the expression of HO-1 was inhibited, the expression levels of the TLR4 protein, the downstream molecule myeloid differentiation factor 88 (MyD88), the Toll and interleukin-1 receptor (TIR) -domain-containing adapter-inducing interferon-β (TRIF) and the inflammatory factors were measured by western blotting.

RESULTS

Immunofluorescence showed that HO-1 and TLR4 had similar temporal expression patterns and cellular localization after ICH, and we found that inhibiting HO-1 reduces the expression of TLR4 protein pathways, including TLR4, MyD88, TRIF, and related inflammatory factors, by studying the inhibitor ZnPP.

CONCLUSION

These results indicate that HO-1 may promote early neuroinflammation after ICH through the TLR4/MyD88/TRIF signaling pathway.

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.

Diet-Induced High Serum Levels of Trimethylamine-N-oxide Enhance the Cellular Inflammatory Response without Exacerbating Acute Intracerebral Hemorrhage Injury in Mice

Trimethylamine-N-oxide (TMAO), an intestinal flora metabolite of choline, may aggravate atherosclerosis by inducing a chronic inflammatory response and thereby promoting the occurrence of cerebrovascular diseases. Knowledge about the influence of TMAO-related inflammatory response on the pathological process of acute stroke is limited. This study was designed to explore the effects of TMAO on neuroinflammation, brain injury severity, and long-term neurologic function in mice with acute intracerebral hemorrhage (ICH). We fed mice with either a regular chow diet or a chow diet supplemented with 1.2% choline pre- and post-ICH. In this study, we measured serum levels of TMAO with ultrahigh-performance liquid chromatography-tandem mass spectrometry at 24 h and 72 h post-ICH. The expression level of P38-mitogen-protein kinase (P38-MAPK), myeloid differentiation factor 88 (MyD88), high-mobility group box1 protein (HMGB1), and interleukin-1β (IL-1β) around hematoma was examined by western blotting at 24 h. Microglial and astrocyte activation and neutrophil infiltration were examined at 72 h. The lesion was examined on days 3 and 28. Neurologic deficits were examined for 28 days. A long-term choline diet significantly increased serum levels of TMAO compared with a regular diet at 24 h and 72 h after sham operation or ICH. Choline diet-induced high serum levels of TMAO did not enhance the expression of P38-MAPK, MyD88, HMGB1, or IL-1β at 24 h. However, it did increase the number of activated microglia and astrocytes around the hematoma at 72 h. Contrary to our expectations, it did not aggravate acute or long-term histologic damage or neurologic deficits after ICH. In summary, choline diet-induced high serum levels of TMAO increased the cellular inflammatory response probably by activating microglia and astrocytes. However, it did not aggravate brain injury or worsen long-term neurologic deficits. Although TMAO might be a potential risk factor for cerebrovascular diseases, this exploratory study did not support that TMAO is a promising target for ICH therapy.

Lymphocyte-Related Immunomodulatory Therapy with Siponimod (BAF-312) Improves Outcomes in Mice with Acute Intracerebral Hemorrhage

Modulators of the sphingosine-1-phosphate receptor (S1PR) have been proposed as a promising strategy for treating stroke. However, the detailed mechanisms and the potential translational value of S1PR modulators for intracerebral hemorrhage (ICH) therapy warrant exploration. Using collagenase VII-S-induced ICH in the left striatum of mice, we investigated the effects of siponimod on cellular and molecular immunoinflammatory responses in the hemorrhagic brain in the presence or absence of anti-CD3 monoclonal antibodies (Abs). We also assessed the severity of short- and long-term brain injury and evaluated the efficacy of siponimod in long-term neurologic function. Siponimod treatment significantly decreased brain lesion volume and brain water content on day 3 and the volume of the residual lesion and brain atrophy on day 28. It also inhibited neuronal degeneration on day 3 and improved long-term neurologic function. These protective effects may be associated with a reduction in the expression of lymphotactin (XCL1) and T-helper 1 (Th1)-type cytokines (interleukin 1β and interferon-γ). It may also be associated with inhibition of neutrophil and lymphocyte infiltration and alleviation of T lymphocyte activation in perihematomal tissues on day 3. However, siponimod did not affect the infiltration of natural killer cells (NK) or the activation of CD3-negative immunocytes in perihematomal tissues. Furthermore, it did not influence the activation or proliferation of microglia or astrocytes around the hematoma on day 3. Siponimod appears to have a profound impact on infiltration and activation of T lymphocytes after ICH. The effects of neutralized anti-CD3 Abs-induced T-lymphocyte tolerance on siponimod immunomodulation further confirmed that siponimod alleviated the cellular and molecular Th1 response in the hemorrhagic brain. This study provides preclinical evidence that encourages future investigation of immunomodulators, including siponimod, which target the lymphocyte-related immunoinflammatory reaction in ICH therapy.

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.

The pros and cons of motor, memory, and emotion-related behavioral tests in the mouse traumatic brain injury model

Traumatic brain injury (TBI) is a medical emergency with high morbidity and mortality. Motor, memory, and emotion-related deficits are common symptoms following TBI, yet treatment is very limited. To develop new drugs and find new therapeutic avenues, a wide variety of TBI models have been established to mimic the heterogeneity of TBI. In this regard, along with histologic measures, behavioral functional outcomes provide valuable insight into the underlying neuropathology and guide neurorehabilitation efforts for neuropsychiatric impairment after TBI. Development, characterization, and application of behavioral tests that can assess functional neurologic deficits are essential to the development of translational therapies. This comprehensive review aims to summarize 19 common behavioral tests from three aspects (motor, memory, and emotion-related) that are associated with TBI pathology. Discussion covers the apparatus, the test steps, the evaluation indexes, data collection and analysis, animal performance and applications, advantages and disadvantages as well as precautions to eliminate bias wherever possible. We discussed recent studies on TBI-related preconditioning, biomarkers, and optimized behavioral protocols. The neuropsychologic tests employed in clinics were correlated with those used in mouse TBI models. In summary, this review provides a comprehensive, up-to-date reference for TBI researchers to choose the right neurobehavioral protocol according to the research objectives of their translational investigation.

Temporal Expression Pattern of Hemoxygenase-1 Expression and Its Association with Vasospasm and Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Background

Red blood cell-induced cerebral inflammation and toxicity has been shown to be attenuated by induction of the heme-catalyzing enzyme, hemoxygenase-1 (HO-1), in animal models of subarachnoid hemorrhage (SAH). Although inflammatory mechanisms leading to secondary neuronal injury in SAH are becoming increasingly well understood, markers of cerebral inflammation have so far not been implemented in clinical prediction models of SAH.

Methods

In this biomarker observational study, HO-1 messenger ribonucleic acid (mRNA) expression levels were determined in cerebrospinal fluid (CSF) and blood of 66 patients with aneurysmal SAH on days 1, 7, and 14 after the SAH event. HO-1 mRNA expression was determined via real time polymerase chain reaction (PCR), and relative expression changes were quantified in comparison with expression levels in nonhemorrhagic control CSF. Subarachnoid blood burden, as well as presence of vasospasm and delayed cerebral ischemia (DCI), were recorded. Short and long-term clinical outcomes were assessed using the Modified Rankin Scale at discharge and 1 year after the SAH event.

Results

CSF HO-1 expression levels showed a significant increase over the 14-day observation period (p < 0.001, F = 22.53) and correlated with intracranial hematoma burden (ρ = 0.349, p = 0.025). In multivariate analyses, CSF HO-1 expression levels did not reach significance as independent predictors of outcome. Vasospasm on computed tomographic angiography was associated with lower CSF HO-1 expression levels on day 7 after SAH (n = 53, p = 0.010), whereas patients with DCI showed higher CSF HO-1 expression levels on day 14 after SAH (n = 21, p = 0.009).

Conclusions

HO-1 expression in CSF in patients with SAH follows a distinct temporal induction pattern and is dependent on intracranial hematoma burden. CSF HO-1 expression was unable to predict functional outcome. Associations of early low HO-1 expression with vasospasm and late elevated HO-1 expression with DCI may point to detrimental effects of late HO-1 induction, warranting the need for further investigation in a larger study population.

Potential therapeutic effects of Nrf2 activators on intracranial hemorrhage

Intracranial hemorrhage (ICH) is a devastating disease which induces high mortality and poor outcomes including severe neurological dysfunctions. ICH pathology is divided into two types: primary brain injury (PBI) and secondary brain injury (SBI). Although there are numerous preclinical studies documenting neuroprotective agents in experimental ICH models, no effective drugs have been developed for clinical use due to complicated ICH pathology. Oxidative and inflammatory stresses play central roles in the onset and progression of brain injury after ICH, especially SBI. Nrf2 is a crucial transcription factor in the anti-oxidative stress defense system. Under normal conditions, Nrf2 is tightly regulated by the Keap1. Under ICH pathological conditions, such as overproduction of reactive oxygen species (ROS), Nrf2 is translocated into the nucleus where it up-regulates the expression of several anti-oxidative phase II enzymes such as heme oxygenase-1 (HO-1). Recently, many reports have suggested the therapeutic potential of Nrf2 activators (including natural or synthesized compounds) for treating neurodegenerative diseases. Moreover, several Nrf2 activators attenuate ischemic stroke-induced brain injury in several animal models. This review summarizes the efficacy of several Nrf2 activators in ICH animal models. In the future, Nrf2 activators might be approved for the treatment of ICH patients.

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.

Neuroprotection of Heme Oxygenase-2 in Mice AfterIntracerebral Hemorrhage

There are few effective preventive or therapeutic strategies to mitigate the effects of catastrophic intracerebral hemorrhage (ICH) in humans. Heme oxygenase is the rate-limiting enzyme in heme metabolism; heme oxygenase-2 (HO-2) is a constitutively expressed heme oxygenase. We explored the involvement of HO-2 in a collagenase-induced mouse model of ICH in C57BL/6 wild-type and HO-2 knockout mice. We assessed oxidative stress injury, blood-brain barrier permeability, neuronal damage, late-stage angiogenesis, and hematoma clearance using immunofluorescence, Western blot, MRI, and special staining methods. Our results show that HO-2 reduces brain injury volume and brain edema, alleviates cytotoxic injury, affects vascular function in the early stage of ICH, and improves hematoma absorbance and angiogenesis in the late stage of ICH in this model. Thus, we found that HO-2 has a protective effect on brain injury after ICH.

Intracerebral Injection of Heme Induces Lipid Peroxidation, Neuroinflammation, and Sensorimotor Deficits

[Figure: see text].

Role of mass effect and trehalose on early erythrolysis after experimental intracerebral hemorrhage

The mechanisms of brain injury after intracerebral hemorrhage (ICH) involve mass effect-induced primary injury and secondary injury caused by a pathologic response to the hematoma. Considerable attentions have recently been paid to the mechanisms and therapeutic strategy for secondary brain injury due to no overall benefit from early surgery compared with initial conservative treatment. However, it is unclear whether there is a causal relationship between mass effect and secondary brain injury. Here, the role of mass effect on early erythrolysis after experimental ICH was investigated based on the poly(N-isopropylacrylamide) (PNIPAM) ICH model. Autologous blood and PNIPAM hydrogel were co-injected into the right basal ganglia of rats to induce different degrees of mass effect, but with a constant hematoma. The influences of different mass effect and time courses on erythrolysis and brain damages after ICH were investigated. Furthermore, the protective effect of trehalose against erythrolysis after ICH was evaluated. The results showed that mass effect caused erythrocyte morphological change at 24 hr after ICH. The released hemoglobin was quantitatively evaluated by a polynomial concerning with the mass effect, the volume of hematoma, and the time of ICH. An obvious increase in heme oxygenase-1 (HO-1) and ionized calcium binding adaptor molecule-1 (Iba-1) expression, iron deposition, cell death, and neurological deficits was observed with increasing mass effect. Moreover, trehalose alleviated brain injury by inhibiting erythrolysis after ICH. These data demonstrated that mass effect accelerated the erythrolysis and brain damages after ICH, which could be relieved through trehalose therapy.

Protocatechuic acid attenuates brain edema and blood-brain barrier disruption after intracerebral hemorrhage in mice by promoting Nrf2/HO-1 pathway

The brain edema following intracerebral hemorrhage (ICH) plays a key role in the recovery process. Protocatechuic acid (PCA) has been proved possessing neuroprotection in ICH. Here we tried to explore its value in brain edema after ICH and reveal underlying mechanisms. ICH model was created in C57 mice using collagenase IV. PCA was injected intraperitoneally at 30 mg/kg every 24 h in PCA group. On day 3 after ICH, the water content of hemorrhagic ipsilateral hemisphere in PCA group was significantly reduced compared with vehicle group. AQP4, the main water channel, was remarkably decreased in PCA group. Additionally, ZO-1 and occludin expression were increased in PCA group. The bEnd.3 cells were cultured to understand the effect of PCA on the blood-brain barrier (BBB) integrity. Compare to hemin treated group, plus PCA enhanced the expression of HO-1 and Nrf2 nuclear translocation. Furtherly, the overexpression of HO-1, ZO-1, occludin, in the PCA treatment group was inhibited after knockdown of Nrf2. Taken together, our results proved PCA alleviated brain edema and BBB disruption in ICH by promoting the Nrf2/HO-1 signaling pathway.

Oxidative Stress at the Crossroads of Aging, Stroke and Depression

Epidemiologic studies have shown that in the aging society, a person dies from stroke every 3 minutes and 42 seconds, and vast numbers of people experience depression around the globe. The high prevalence and disability rates of stroke and depression introduce enormous challenges to public health. Accumulating evidence reveals that stroke is tightly associated with depression, and both diseases are linked to oxidative stress (OS). This review summarizes the mechanisms of OS and OS-mediated pathological processes, such as inflammation, apoptosis, and the microbial-gut-brain axis in stroke and depression. Pathological changes can lead to neuronal cell death, neurological deficits, and brain injury through DNA damage and the oxidation of lipids and proteins, which exacerbate the development of these two disorders. Additionally, aging accelerates the progression of stroke and depression by overactive OS and reduced antioxidant defenses. This review also discusses the efficacy and safety of several antioxidants and antidepressants in stroke and depression. Herein, we propose a crosstalk between OS, aging, stroke, and depression, and provide potential therapeutic strategies for the treatment of stroke and depression.

Protective role of microglial HO-1 blockade in aging: Implication of iron metabolism

Heme oxygenase-1 (HO-1) is an inducible enzyme known for its anti-inflammatory, antioxidant and neuroprotective effects. However, increased expression of HO-1 during aging and age-related neurodegenerative diseases have been associated to neurotoxic ferric iron deposits. Being microglia responsible for the brain's innate immune response, the aim of this study was to understand the role of microglial HO-1 under inflammatory conditions in aged mice. For this purpose, aged wild type (WT) and LysMCreHmox1^△△ (HMOX1^M-KO) mice that lack HO-1 in microglial cells, were used. Aged WT mice showed higher basal expression levels of microglial HO-1 in the brain than adult mice. This increase was even higher when exposed to an inflammatory stimulus (LPS via i.p.) and was accompanied by alterations in different iron-related metabolism proteins, resulting in an increase of iron deposits, oxidative stress, ferroptosis and cognitive decline. Furthermore, microglia exhibited a primed phenotype and increased levels of inflammatory markers such as iNOS, p65, IL-1β, TNF-α, Caspase-1 and NLRP3. Interestingly, all these alterations were prevented in aged HMOX1^M-KO and WT mice treated with the HO-1 inhibitor ZnPPIX. In order to determine the effects of microglial HO-1-dependent iron overload, aged WT mice were treated with the iron chelator deferoxamine (DFX). DFX caused major improvements in iron, inflammatory and behavioral alterations found in aged mice exposed to LPS. In conclusion, this study highlights how microglial HO-1 overexpression contributes to neurotoxic iron accumulation providing deleterious effects in aged mice exposed to an inflammatory insult.

•

Microglial HO-1 increases with aging and under an acute inflammatory stimulus.

•

LPS-dependent microglial HO-1 upregulation during aging leads to iron overload.

•

Microglial HO-1-dependent iron accumulation leads to ferroptosis.

•

HO-1-dependent iron alterations lead to neuroinflammation.

•

HO-1 inhibitors/iron chelators reduce iron accumulation and neuroinflammation.

Combined Ischemic Preconditioning and Resveratrol Improved Bloodbrain Barrier Breakdown via Hippo/YAP/TAZ Signaling Pathway

BACKGROUND

Transient Ischemia/Reperfusion (I/R) is the main reason for brain injury and results in disruption of the Blood-Brain Barrier (BBB). It had been reported that BBB injury is one of the main risk factors for early death in patients with cerebral ischemia. Numerous investigations focus on the study of BBB injury which have been carried out.

OBJECTIVE

The objective of this study was to investigate the treatment function of the activation of the Hippo/Yes-Associated Protein (YAP) signaling pathway by combined Ischemic Preconditioning (IPC) and resveratrol (RES) before brain Ischemia/Reperfusion (BI/R) improves Blood-Brain Barrier (BBB) disruption in rats.

METHODS

Sprague-Dawley (SD) rats were pretreated with 20 mg/kg RES and IPC and then subjected to 2 h of ischemia and 22 h of reperfusion. The cerebral tissues were collected; the cerebral infarct volume was determined; the Evans Blue (EB) level, the brain Water Content (BWC), and apoptosis were assessed; and the expressions of YAP and TAZ were investigated in cerebral tissues.

RESULTS

Both IPC and RES preconditioning reduced the cerebral infarct size, improved BBB permeability, lessened apoptosis, and upregulated expressions of YAP and transcriptional co-activator with PDZ-binding motif (TAZ) compared to the Ischemia/Reperfusion (I/R) group, while combined IPC and RES significantly enhanced this action.

CONCLUSION

combined ischemic preconditioning and resveratrol improved blood-brain barrier breakdown via Hippo/YAP/TAZ signaling pathway.

miR-183-5p alleviates early injury after intracerebral hemorrhage by inhibiting heme oxygenase-1 expression

Differences in microRNA (miRNA) expression after intracerebral hemorrhage (ICH) have been reported in human and animal models, and miRNAs are being investigated as a new treatment for inflammation and oxidative stress after ICH. In this study, we found that microRNA-183-5p expression was decreased in the mouse brain after ICH. To investigate the effect of miRNA-183-5p on injury and repair of brain tissue after ICH, saline, miRNA-183-5p agomir, or miRNA-183-5p antagomir were injected into the lateral ventricles of 8-week-old mice with collagenase-induced ICH. Three days after ICH, mice treated with exogenous miRNA-183-5p showed less brain edema, neurobehavioral defects, inflammation, oxidative stress, and ferrous deposition than control mice. In addition, by alternately treating mice with a heme oxygenase-1 (HO-1) inducer, a HO-1 inhibitor, a nuclear factor erythroid 2-related factor (Nrf2) activator, and Nrf2 knockout, we demonstrated an indirect, HO-1-dependent regulatory relationship between miRNA-183-5p and Nrf2. Our results indicate that miRNA-183-5p and HO-1 are promising therapeutic targets for controlling inflammation and oxidative damage after hemorrhagic stroke.

Brainstem iron overload and injury in a rat model of brainstem hemorrhage

BACKGROUND AND PURPOSE

Brainstem hemorrhage (BSH) is the most devastating subtype of intracerebral hemorrhage (ICH) with the highest mortality ranging from 56 % to 61.2 %. However, there is no effective medical or surgical therapy to improve its outcomes in clinic to date due to lack of understanding of its injury mechanisms. Herein, we explored the brainstem iron overload and injury in a rat model of BSH.

METHODS

Neurological scores were examined on day 1, 3, and 7 after modeling, and mortality of the rats was recorded to draft a survival curve. Rats were monitored by MRI using T2 and susceptibility weighted imaging (SWI) before sacrifice for examination of histology and immunofluorescence on day 1, 3, and 7.

RESULTS

BSH rats had a high mortality of 56 % and demonstrated the severe neurological deficits mimicking the clinical conditions. SWI showed that the same increasing tendency in change of hypointense area with that in iron deposition by Perls staining from day 1 to 7. Expression of heme oxygenase 1 (HO-1) and generation of reactive oxygen species (ROS) had similar tendency and both peaked on day 3. Neuronal degeneration occurred and stayed elevated from day 1 to 7, while myelin sheath injury was initially observed on day 1 but without significant difference within 7 days.

CONCLUSIONS

The time courses of erythrocyte lysis, HO-1 expression, iron deposition and ROS generation are related to each other after BSH. Besides, brainstem injury including neuronal degeneration and myelin damage were observed and discussed.

Danhong Injection Protects Hemorrhagic Brain by Increasing Peroxiredoxin 1 in Aged Rats

Intracerebral hemorrhage (ICH) is a severe cerebrovascular disease with a high incidence, mortality and disability rate. Danhong injection (DHI) is beneficial for ischemic stroke, but is prohibited for ICH due to risk of bleeding. The present study aims to explore the potential therapeutic time window and molecular mechanism of DHI in a collagenase-induced ICH model in aged rats. DHI administration after ICH could significantly improve body weight and neurological deficits, and reduce the hematoma volume and brain water content when compared to the vehicle control. Furthermore, the protective effect of DHI administration on days 1–3 after ICH was superior to those on days 3–5 or 7–9 after ICH. DHI remarkably increased the Peroxiredoxin 1 (Prx1) expression in astrocytes and reduced the expression of inflammatory factors tumor necrosis factor-α (TNF-α) and interleukin-β (IL-1β) after ICH. The immediate treatment of Prx1 inhibiter chelerythrine (Che) after ICH abolished the protective effect of DHI. Furthermore, the Che treatment reduced the expression of Prx1 in astrocytes, but increased the expression of TNF-α and IL-1β after ICH. DHI treatment could not reverse these changes. Therefore, the earlier DHI is administered, the better the neuroprotective effect. DHI exerts antioxidative and anti-inflammatory function by increasing Prx1 in astrocytes. These present results may change the established understanding of DHI, and reveal a novel treatment approach for ICH.

Effects of RO27-3225 on neurogenesis, PDGFRβ+ cells and neuroinflammation after cerebral infarction

Cerebral infarction causes severe social and economic burdens to patients due to its high morbidity and mortality rates, and the available treatments are limited. RO27-3225 is a highly selective melanocortin receptor 4 agonist that alleviates damage in many nervous system diseases, such as cerebral hemorrhage, traumatic brain injury and chronic neurodegenerative diseases. However, the effect of RO27-3225 on cerebral infarction remains unclear. In this study, we used a mouse model of transient middle cerebral artery occlusion (tMCAO) and administered RO27-3225 or saline to the mice through intraperitoneal injection. RO27-3225 increased the number of Nestin⁺/BrdU⁺ cells and doublecortin (DCX)⁺/BrdU⁺ cells in the subventricular zone (SVZ) and the number of DCX⁺/BrdU⁺ cells in the peri-infarct area on day 7 after tMCAO. Furthermore, RO27-3225 decreased the number of activated microglia (Iba1⁺ cells with a specific morphology) and the expression levels of Iba1, TNFα, IL6, and iNOS proteins and increased the number of PDGFRβ⁺ cells in the peri-infarct region on day 3 after tMCAO. Finally, RO27-3225-treated mice exhibited significantly decreased infarct volumes, brain water contents, and neurological deficits after cerebral infarction. Thus, RO27-3225 can improve the outcomes following cerebral infarction, partially by regulating neurogenesis in the SVZ, PDGFRβ⁺ cell survival and neuroinflammation in the peri-infarct zone. Our research reveals that RO27-3225 is a potential new treatment for cerebral infarction.

Microglia and macrophage phenotypes in intracerebral haemorrhage injury: therapeutic opportunities

The prognosis of intracerebral haemorrhage continues to be devastating despite much research into this condition. A prominent feature of intracerebral haemorrhage is neuroinflammation, particularly the excessive representation of pro-inflammatory CNS-intrinsic microglia and monocyte-derived macrophages that infiltrate from the circulation. The pro-inflammatory microglia/macrophages produce injury-enhancing factors, including inflammatory cytokines, matrix metalloproteinases and reactive oxygen species. Conversely, the regulatory microglia/macrophages with potential reparative and anti-inflammatory roles are outcompeted in the early stages after intracerebral haemorrhage, and their beneficial roles appear to be overwhelmed by pro-inflammatory microglia/macrophages. In this review, we describe the activation of microglia/macrophages following intracerebral haemorrhage in animal models and clinical subjects, and consider their multiple mechanisms of cellular injury after haemorrhage. We review strategies and medications aimed at suppressing the pro-inflammatory activities of microglia/macrophages, and those directed at elevating the regulatory properties of these myeloid cells after intracerebral haemorrhage. We consider the translational potential of these medications from preclinical models to clinical use after intracerebral haemorrhage injury, and suggest that several approaches still lack the experimental support necessary for use in humans. Nonetheless, the preclinical data support the use of deactivator or inhibitor of pro-inflammatory microglia/macrophages, whilst enhancing the regulatory phenotype, as part of the therapeutic approach to improve the prognosis of intracerebral haemorrhage.

MiR-21-5p/dual-specificity phosphatase 8 signalling mediates the anti-inflammatory effect of haem oxygenase-1 in aged intracerebral haemorrhage rats

Intracerebral haemorrhage (ICH) is a severe neurological disorder caused by bleeding within the brain tissue. Inflammation has been implicated in ICH pathogenesis and is a potential therapeutic target for ICH. Haemin, an activator of haem oxygenase-1 (HO-1), rapidly increases HO-1 protein expression and activity and has been shown to distinctly affect anti-inflammatory functions after central nervous system (CNS) injury. However, less is known about the mechanisms that underlie the anti-inflammatory effects of haemin in aged rats post-ICH. Here, we performed microarray analysis to identify miRNAs that respond strongly to HO-1 regulation in ICH rats and found that miR-21-5p induced the most significant change. Using Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and Gene Ontology (GO) analysis, we focused on dual-specificity phosphatase 8 (DUSP8) from the predicted miR-21-5p targets. Luciferase reporter assays confirmed that miR-21-5p bound directly to DUSP8. MiR-21-5p upregulation in vitro downregulated DUSP8 expression. Importantly, intracerebroventricularly injecting antagomir for miR-21-5p (A-miR-21-5p), which was used to inhibit miR-21-5p in aged ICH rats, significantly reduced the neurological defects, repaired cognitive impairment, alleviated blood-brain barrier (BBB) permeability, inhibited neuronal apoptosis posthaemorrhage and accelerated haematoma absorption. In addition, serum miR-21-5p levels were notably elevated in patients relative to healthy individuals and were correlated with National Institutes of Health Stroke Scale (NIHSS) scores and clinical outcomes. In summary, A-miR-21-5p increased HO-1 expression in cerebral haematomas, thus eliciting the DUSP8-modulated perifocal neuroprotective effect of haemin. MiR-21-5p with haemin therapy may be a potential therapy post-ICH.

Intracerebral Hemorrhage: Blood Components and Neurotoxicity

Intracerebral hemorrhage (ICH) is a subtype of stroke which is associated with the highest mortality and morbidity rates of all strokes. Although it is a major public health problem, there is no effective treatment for ICH. As a consequence of ICH, various blood components accumulate in the brain parenchyma and are responsible for much of the secondary brain damage and ICH-induced neurological deficits. Therefore, the strategies that could attenuate the blood component-induced neurotoxicity and improve hematoma resolution are highly needed. The present article provides an overview of blood-induced brain injury after ICH and emphasizes the need to conduct further studies elucidating the mechanisms of hematoma resolution after ICH.

Haemoglobin scavenging in intracranial bleeding: biology and clinical implications

Haemoglobin is released into the CNS during the breakdown of red blood cells after intracranial bleeding. Extracellular free haemoglobin is directly neurotoxic. Haemoglobin scavenging mechanisms clear haemoglobin and reduce toxicity; these mechanisms include erythrophagocytosis, haptoglobin binding of haemoglobin, haemopexin binding of haem and haem oxygenase breakdown of haem. However, the capacity of these mechanisms is limited in the CNS, and they easily become overwhelmed. Targeting of haemoglobin toxicity and scavenging is, therefore, a rational therapeutic strategy. In this Review, we summarize the neurotoxic mechanisms of extracellular haemoglobin and the peculiarities of haemoglobin scavenging pathways in the brain. Evidence for a role of haemoglobin toxicity in neurological disorders is discussed, with a focus on subarachnoid haemorrhage and intracerebral haemorrhage, and emerging treatment strategies based on the molecular pathways involved are considered. By focusing on a fundamental biological commonality between diverse neurological conditions, we aim to encourage the application of knowledge of haemoglobin toxicity and scavenging across various conditions. We also hope that the principles highlighted will stimulate research to explore the potential of the pathways discussed. Finally, we present a consensus opinion on the research priorities that will help to bring about clinical benefits.

Tanshinone IIA attenuates demyelination and promotes remyelination in A. cantonensis-infected BALB/c mice

BACKGROUND

Angiostrongylus cantonensis infection can cause demyelination in the central nervous system, and there is no effective treatment.

METHODS

We used dexamethasone, Tanshinone IIA (TSIIA) and Cryptotanshinone(Two traditional Chinese medicine monomers) in combination with albendazole (AB, a standard anti-helminthic compound) to observe their therapeutic effect on demyelination in A. cantonensis-infected mice. Luxol fast blue staining and electron microscope of myelin sheath, Oligodendrocyte (OL) number and myelin basic protein (MBP) expression in brain was detected in above groups.

RESULTS

TSIIA+AB facilitated OL proliferation and significantly increased both myelin sheath thickness and the population of small-diameter axons. In addition, TSIIA treatment inhibited the expression of inflammation-related factors (interleukin [IL]-6, IL-1β, tumor necrosis factor [TNF]-α, inducible nitric oxide synthase [iNOS]) rather than inhibiting eosinophil infiltration in brain. TSIIA also decreased microglial activation and shifted their phenotype from M1 to M2.

CONCLUSIONS

Taken together, these results provide evidence that TSIIA combined with AB may be an effective treatment for demyelination caused by A. cantonensis infection and other demyelinating diseases.

Heme, Heme Oxygenase, and Endoplasmic Reticulum Stress-A New Insight into the Pathophysiology of Vascular Diseases

The prevalence of vascular disorders continues to rise worldwide. Parallel with that, new pathophysiological pathways have been discovered, providing possible remedies for prevention and therapy in vascular diseases. Growing evidence suggests that endoplasmic reticulum (ER) stress is involved in a number of vasculopathies, including atherosclerosis, vascular brain events, and diabetes. Heme, which is released from hemoglobin or other heme proteins, triggers various pathophysiological consequence, including heme stress as well as ER stress. The potentially toxic free heme is converted by heme oxygenases (HOs) into carbon monoxide (CO), iron, and biliverdin (BV), the latter of which is reduced to bilirubin (BR). Redox-active iron is oxidized and stored by ferritin, an iron sequestering protein which exhibits ferroxidase activity. In recent years, CO, BV, and BR have been shown to control cellular processes such as inflammation, apoptosis, and antioxidant defense. This review covers our current knowledge about how heme induced endoplasmic reticulum stress (HIERS) participates in the pathogenesis of vascular disorders and highlights recent discoveries in the molecular mechanisms of HO-mediated cytoprotection in heme stress and ER stress, as well as crosstalk between ER stress and HO-1. Furthermore, we focus on the translational potential of HIERS and heme oxygenase-1 (HO-1) in atherosclerosis, diabetes mellitus, and brain 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.

Crocin attenuation of neurological deficits in a mouse model of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke that is associated with high morbidity and mortality. However, up to now, there are no effective prevention methods or specific therapies to improve its clinical outcomes. Herein, we explore preliminarily the efficacy of crocin, a carotenoid extracted from the stigma of saffron known for its anti-oxidation and free radical scavenging activities, in a mouse ICH model induced with collagenase infusion. Crocin or saline was administrated 6 h after ICH and then every 12 h for up to 7 days. Neurological scores were examined on days 1, 3, and 7 after ICH. Mice were sacrificed after1, 3, and 7 days of crocin treatment for examination of histology and immunohistochemistry. The results showed that oral administration of crocin attenuated the neurological deficits and reduced the myelin loss, neuron degeneration, iron deposition, reactive oxygen species (ROS) production and heme oxygenase-1 (HO-1) expression in the early stage of ICH, making it potential to be an ideal candidate for medical therapy of ICH in clinic.

Iron Metabolism and Brain Development in Premature Infants

Iron is important for a remarkable array of essential functions during brain development, and it needs to be provided in adequate amounts, especially to preterm infants. In this review article, we provide an overview of iron metabolism and homeostasis at the cellular level, as well as its regulation at the mRNA translation level, and we emphasize the importance of iron for brain development in fetal and early life in preterm infants. We also review the risk factors for disrupted iron metabolism that lead to high risk of developing iron deficiency and subsequent adverse effects on neurodevelopment in preterm infants. At the other extreme, iron overload, which is usually caused by excess iron supplementation in iron-replete preterm infants, might negatively impact brain development or even induce brain injury. Maintaining the balance of iron during the fetal and neonatal periods is important, and thus iron status should be monitored routinely and evaluated thoroughly during the neonatal period or before discharge of preterm infants so that iron supplementation can be individualized.

Intracellular Fe2+ accumulation in endothelial cells and pericytes induces blood-brain barrier dysfunction in secondary brain injury after brain hemorrhage

After intracranial hemorrhage (ICH), iron is released from the hematoma and induces secondary brain injury. However, the detail effect of iron on blood-brain barrier (BBB) function is still unknown. We investigated whether hemoglobin (Hb), ferrous ammonium sulfate (FAS) or hemin which contains iron have the detrimental effect on both human brain microvascular endothelial cells and pericytes by cellular function analysis in vitro. We developed an iron (Fe²⁺)-detectable probe, Si-RhoNox-1, to investigate intracellular Fe²⁺ accumulation (Fe²⁺_intra). After FAS treatment, there was the correlation between Fe²⁺_intra and cell death. Moreover, Hb or hemin treatment induced cell death, increased reactive oxygen species and promoted Fe²⁺_intra in both cells. These changes were inhibited by the Fe²⁺ chelator, 2,2′-bipyridil (BP). Furthermore, hemin induced endothelial barrier dysfunction via disruption of junction integrity. Based on in vitro studies, we used a hemin-injection ICH mice model in vivo. Hemin injection (10 mM/10 µL, i.c.) induced deleterious effects including BBB hyper-permeability, neuronal deficits, neuronal damage, altered proteins expression, and Fe²⁺_intra in BBB composed cells. Lastly, BP (40 mg/kg, i.p.) administration attenuated neuronal deficits at 3 days after surgery. Collectively, Hb or hemin damaged BBB composed cells via Fe²⁺_intra. Therefore, the regulation of the Fe²⁺ movement in BBB might be effective for treatment of ICH.

Acute intranasal osteopontin treatment in male rats following TBI increases the number of activated microglia but does not alter lesion characteristics

Intranasal recombinant osteopontin (OPN) has been shown to be neuroprotective in different models of acquired brain injury but has never been tested after traumatic brain injury (TBI). We used a model of moderate-to-severe controlled cortical impact in male adult Sprague Dawley rats and tested our hypothesis that OPN treatment would improve neurological outcomes, lesion and brain tissue characteristics, neuroinflammation, and vascular characteristics at 1 day post-injury. Intranasal OPN administered 1 hr after the TBI did not improve neurological score, lesion volumes, blood-brain barrier, or vascular characteristics. When assessing neuroinflammation, we did not observe any effect of OPN on the astrocyte reactivity but discovered an increased number of activated microglia within the ipsilateral hemisphere. Moreover, we found a correlation between edema and heme oxygenase-1 (HO-1) expression which was decreased in OPN-treated animals, suggesting an effect of OPN on the HO-1 response to injury. Thus, OPN may increase or accelerate the microglial response after TBI, and early response of HO-1 in modulating edema formation may limit the secondary consequences of TBI at later time points. Additional experiments and at longer time points are needed to determine if intranasal OPN could potentially be used as a treatment after TBI where it might be beneficial by activating protective signaling pathways.

Iron Regulation: Macrophages in Control

Macrophages are sentinel cells of the innate immune system and have important functions in development, tissue homeostasis, and immunity. These phylogenetically ancient cells also developed a variety of mechanisms to control erythropoiesis and the handling of iron. Red pulp macrophages in the spleen, Kupffer cells in the liver, and central nurse macrophages in the bone marrow ensure a coordinated metabolism of iron to support erythropoiesis. Phagocytosis of senescent red blood cells by macrophages in the spleen and the liver provide a continuous delivery of recycled iron under steady-state conditions and during anemic stress. Central nurse macrophages in the bone marrow utilize this iron and provide a cellular scaffold and niche to promote differentiation of erythroblasts. This review focuses on the role of the distinct macrophage populations that contribute to efficient iron metabolism and highlight important cellular and systemic mechanisms involved in iron-regulating processes.

MicroRNA-182 Alleviates Neuropathic Pain by Regulating Nav1.7 Following Spared Nerve Injury in Rats

The sodium channel 1.7 (Nav1.7), which is encoded by SCN9A gene, is involved in neuropathic pain. As crucial regulators of gene expression, many miRNAs have already gained importance in neuropathic pain, including miR-182, which is predicted to regulate the SCN9A gene. Nav1.7 expression in L4-L6 dorsal root ganglions (DRGs) can be up regulated by spared nerve injury (SNI), while miR-182 expression was down regulated following SNI model. Exploring the connection between Nav1.7 and miR-182 may facilitate the development of a better-targeted therapy. In the current study, direct pairing of miR-182 with the SCN9A gene was verified using a luciferase assay in vitro. Over-expression of miR-182 via microinjection of miR-182 agomir reversed the abnormal increase of Nav1.7 at both mRNA and protein level in L4-6 DRGs of SNI rats, and significantly attenuated the hypersensitivity to mechanical stimulus in the rats. In contrast, administration of miR-182 antagomir enhanced the Nav1.7 expression at both mRNA and protein level in L4-6 DRGs, companied with the generation of mechanical hypersensitivity in naïve rats. Collectively, we concluded that miR-182 can alleviate SNI- induced neuropathic pain through regulating Nav1.7 in rats.