Role of iron in brain injury after intraventricular hemorrhage

Complement Inhibition Reduces Early Erythrolysis, Attenuates Brain Injury, Hydrocephalus, and Iron Accumulation after Intraventricular Hemorrhage in Aged Rats

Blood components released by erythrolysis play an important role in secondary brain injury and posthemorrhagic hydrocephalus (PHH) after intraventricular hemorrhage (IVH). The current study examined the impact of N-acetylheparin (NAH), a complement inhibitor, on early erythrolysis, PHH and iron accumulation in aged rats following IVH. This study, on 18-months-old male Fischer 344 rats, was in 3 parts. First, rats had an intracerebroventricular injection of autologous blood (IVH) mixed with NAH or saline, or saline alone. After MRI at four hours, Western blot and immunohistochemistry examined complement activation and electron microscopy choroid plexus and periventricular damage. Second, rats had an IVH with NAH or vehicle, or saline. Rats underwent serial MRI at 4 h and 1 day to assess ventricular volume and erythrolysis. Immunohistochemistry and H&E staining examined secondary brain injury. Third, rats had an IVH with NAH or vehicle. Serial MRIs on day 1 and 28 assessed ventricular volume and iron accumulation. H&E staining and immunofluorescence evaluated choroid plexus phagocytes. Complement activation was found 4 h after IVH, and co-injection of NAH inhibited that activation. NAH administration attenuated erythrolysis, reduced ventricular volume, alleviated periventricular and choroid plexus injury at 4 h and 1 day after IVH. NAH decreased iron accumulation, the number of choroid plexus phagocytes, and attenuated hydrocephalus at 28 days after IVH. Inhibiting complement can reduce early erythrolysis, attenuates hydrocephalus and iron accumulation after IVH in aged animals.

Disseminated Rasamsonia argillacea complex infection presenting as intraventricular brain hemorrhage in a German shepherd dog in Australia

A German Shepherd Dog diagnosed with Rasamsonia argillacea based on fungal culture and DNA sequencing, is the first documented case in Australia, and the Southern Hemisphere. This species is part of R. argillacea complex, which is an emerging concern in immunocompromised human and veterinary patients. Intraventricular brain hemorrhage, noted on MRI, has not been reported previously in a dog with fungal encephalitis. The patient was euthanized due to progression of clinical signs before a final diagnosis was made, so no treatment was attempted in this case.

Choroid plexus immune cell response in murine hydrocephalus induced by intraventricular hemorrhage

BACKGROUND

Intraventricular hemorrhage (IVH) and associated hydrocephalus are significant complications of intracerebral and subarachnoid hemorrhage. Despite proximity to IVH, the immune cell response at the choroid plexus (ChP) has been relatively understudied. This study employs CX3CR-1GFP mice, which marks multiple immune cell populations, and immunohistochemistry to outline that response.

METHODS

This study had four parts all examining male adult CX3CR-1GFP mice. Part 1 examined naïve mice. In part 2, mice received an injection 30 µl of autologous blood into right ventricle and were euthanized at 24 h. In part 3, mice underwent intraventricular injection of saline, iron or peroxiredoxin 2 (Prx-2) and were euthanized at 24 h. In part 4, mice received intraventricular iron injection and were treated with either control or clodronate liposomes and were euthanized at 24 h. All mice underwent magnetic resonance imaging to quantify ventricular volume. The ChP immune cell response was examined by combining analysis of GFP(+) immune cells and immunofluorescence staining.

RESULTS

IVH and intraventricular iron or Prx-2 injection in CX3CR-1GFP mice all induced ventriculomegaly and activation of ChP immune cells. There were very marked increases in the numbers of ChP epiplexus macrophages, T lymphocytes and neutrophils. Co-injection of clodronate liposomes with iron reduced the ventriculomegaly which was associated with fewer epiplexus and stromal macrophages but not reduced T lymphocytes and neutrophils.

CONCLUSION

There is a marked immune cell response at the ChP in IVH involving epiplexus cells, T lymphocytes and neutrophils. The blood components iron and Prx-2 may play a role in eliciting that response. Reduction of ChP macrophages with clodronate liposomes reduced iron-induced ventriculomegaly suggesting that ChP macrophages may be a promising therapeutic target for managing IVH-induced hydrocephalus.

Examining the effect of iron (ferric) on physiological processes: Invertebrate models

Iron is a common and essential element for maintaining life in bacteria, plants and animals and is found in soil, fresh waters and marine waters; however, over exposure is toxic to organisms. Iron is used in electron transport complexes within mitochondria as well as a co-factor in many essential proteins. It is also established that iron accumulation in the central nervous system in mammals is associated with various neurological disorders. Ample studies have investigated the long-term effects of iron overload in the nervous system. However, its acute effects in nervous tissue and additional organ systems warrant further studies. This study investigates the effects of iron overload on development, behavior, survival, cardiac function, and glutamatergic synaptic transmission in the Drosophila melanogaster. Additionally, physiological responses in crayfish were examined following Fe3+ exposure. Fe3+ reduced neuronal excitability in proprioceptive neurons in a crayfish model. Thus, Fe3+ may block stretch activated channels (SACs) as well as voltage-gated Na+ channels. Exposure also rapidly reduces synaptic transmission but does not block ionotropic glutamatergic receptors, suggesting a blockage of pre-synaptic voltage-gated Ca2+ channels in both crustacean and Drosophila models. The effects are partly reversible with acute exposure, indicating the cells are not rapidly damaged. This study is relevant in demonstrating the effects of Fe3+ on various physiological functions in different organisms in order to further understand the acute and long-term consequences of overload.

Aquaporin 4 Mediates the Effect of Iron Overload on Hydrocephalus After Intraventricular Hemorrhage

BACKGROUND

Iron overload plays an important role in hydrocephalus development following intraventricular hemorrhage (IVH). Aquaporin 4 (AQP4) participates in the balance of cerebrospinal fluid secretion and absorption. The current study investigated the role of AQP4 in the formation of hydrocephalus caused by iron overload after IVH.

METHODS

There were three parts to this study. First, Sprague-Dawley rats received an intraventricular injection of 100 µl autologous blood or saline control. Second, rats had IVH and were treated with deferoxamine (DFX), an iron chelator, or vehicle. Third, rats had IVH and were treated with 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020), a specific AQP4 inhibitor, or vehicle. Rats underwent T2-weighted and T2* gradient-echo magnetic resonance imaging to assess lateral ventricular volume and intraventricular iron deposition at 7, 14, and 28 days after intraventricular injection and were then euthanized. Real-time quantitative polymerase chain reaction, western blot analysis, and immunofluorescence analyses were conducted on the rat brains to evaluate the expression of AQP4 at different time points. Hematoxylin and eosin-stained brain sections were obtained to assess the ventricular wall damage on day 28.

RESULTS

Intraventricular injection of autologous blood caused a significant ventricular dilatation, iron deposition, and ventricular wall damage. There was increased AQP4 mRNA and protein expression in the periventricular tissue in IVH rats through day 7 to day 28. The DFX treatment group had a lower lateral ventricular volume and less intraventricular iron deposition and ventricular wall damage than the vehicle-treated group after IVH. The expression of AQP4 protein in periventricular tissue was also inhibited by DFX on days 14 and 28 after IVH. The use of TGN-020 attenuated hydrocephalus development after IVH and inhibited the expression of AQP4 protein in the periventricular tissue between day 14 and day 28 without a significant effect on intraventricular iron deposition or ventricular wall damage.

CONCLUSIONS

AQP4 located in the periventricular area mediated the effect of iron overload on hydrocephalus after IVH.

Iron homeostasis and post-hemorrhagic hydrocephalus: a review

Iron physiology is regulated by a complex interplay of extracellular transport systems, coordinated transcriptional responses, and iron efflux mechanisms. Dysregulation of iron metabolism can result in defects in myelination, neurotransmitter synthesis, and neuronal maturation. In neonates, germinal matrix-intraventricular hemorrhage (GMH-IVH) causes iron overload as a result of blood breakdown in the ventricles and brain parenchyma which can lead to post-hemorrhagic hydrocephalus (PHH). However, the precise mechanisms by which GMH-IVH results in PHH remain elusive. Understanding the molecular determinants of iron homeostasis in the developing brain may lead to improved therapies. This manuscript reviews the various roles iron has in brain development, characterizes our understanding of iron transport in the developing brain, and describes potential mechanisms by which iron overload may cause PHH and brain injury. We also review novel preclinical treatments for IVH that specifically target iron. Understanding iron handling within the brain and central nervous system may provide a basis for preventative, targeted treatments for iron-mediated pathogenesis of GMH-IVH and PHH.

Porous Three-Dimensional Polyurethane Scaffolds Promote Scar-Free Endogenous Regeneration After Acute Brain Hemorrhage

Intracerebral hemorrhage (ICH) is the most lethal subtype of stroke and is associated with significant morbidity and mortality. Despite advances in the clinical treatment of ICH, limited progress has been made regarding endogenous brain regeneration after ICH. Failure of brain regeneration is mainly attributed to the inhibitive regenerative microenvironment caused by secondary injury after ICH. In this study, we investigated a three-dimensional biodegradable waterborne polyurethane (BWPU) scaffold as a tool to promote brain regeneration after ICH. After implantation into the cavity following hematoma evacuation, these implanted scaffolds could act as a reservoir; store a series of necrotic debris, cytokines, and chemokines; and attract microglia/macrophages to their pores. Subsequently, these microglia/macrophages were polarized into the M1-like subtype to eliminate these substances. This process disperses M1-like immune cells and prevents the formation of dense glial scar-free structures after ICH. Inflammatory cells in scaffolds include scar-free secreted growth factors and extracellular matrix (ECM) proteins, and further induce a M2-like immune cells enriched regeneration-predominant microenvironment to promote endogenous brain regeneration with functional recovery. In summary, in this work, we have revealed the potential and mechanism of the BWPU scaffold as a tool to promote endogenous brain tissue regeneration after ICH.

Minocycline attenuates hydrocephalus and inhibits iron accumulation, ependymal damage and epiplexus cell activation after intraventricular hemorrhage in aged rats

Intracerebral hemorrhage is primarily a disease of the elderly and it is frequently accompanied by intraventricular hemorrhage (IVH) which can lead to posthemorrhagic hydrocephalus and poor prognosis. Red blood cell iron has been implicated in brain injury after cerebral hemorrhage. The current study examined using T2* magnetic resonance imaging (MRI) to detect periventricular iron deposition after IVH and investigated the effects of minocycline on hydrocephalus in an aged rat IVH model. It had three parts. In part 1, male aged rats received a 200 μl injection of saline or autologous blood into the lateral ventricle and were euthanized at day 14. In parts 2 and 3, aged IVH rats were treated with vehicle or minocycline and euthanized at day 7 or 14. Rats underwent MRI to quantify hydrocephalus and iron deposition followed by brain histology and immunohistochemistry. Periventricular iron overload was found after IVH using T2* MRI and confirmed by histology. IVH also caused ventricular wall damage and increased the number of CD68(+) choroid plexus epiplexus cells. Minocycline administration reduced iron deposition and ventricular volume at days 7 and 14 after IVH, as well as ventricle wall damage and epiplexus cell activation. In summary, IVH-induced hydrocephalus is associated with periventricular iron deposition, ependymal damage and choroid plexus epiplexus cell activation in aged rats. Minocycline attenuated those effects and might be a potential treatment for posthemorrhagic hydrocephalus in the elderly.

A nomogram for predicting post-operative hydrocephalus in children with medulloblastoma

Post-operative hydrocephalus is common among children with medulloblastoma after initial tumor resection. This study aimed to establish a novel model for predicting the development of post-operative hydrocephalus in children with medulloblastoma. Only pediatric patients who received initial medulloblastoma resection at Beijing Tiantan Hospital between January 2018 and May 2021 were included in this study. The potential risk factors associated with post-operative hydrocephalus were identified based on multivariate logistic regression and the nomogram. Receiver operating characteristic (ROC) curve were used to evaluate the performance of the nomogram model based on an independent cohort of medulloblastoma patients who underwent surgery from June 2021 to March 2022. A total of 105 patients were included in the primary cohort. Superior invasion (P = 0.007), caudal invasion (P = 0.025), and intraventricular blood ≥ 5 mm (P = 0.045) were significantly related to the development of post-operative hydrocephalus and thus were assembled into the nomogram model. The model accurately predicted post-operative hydrocephalus based on the calibration curve. The area under the ROC curves for the primary and validation cohorts was 0.849 and 0.855, respectively. In total, the nomogram we developed may aid clinicians in assessing the potential risk of pediatric patients with MB developing post-operative hydrocephalus, especially those who would otherwise not have received a diversionary procedure at presentation.

Intraventricular hemorrhage in term infants: a single institutional experience between 2016 and 2020

PURPOSE

Intraventricular hemorrhage (IVH) of prematurity is a known complication of preterm birth. Intraventricular hemorrhage in term infants is much less commonly encountered. To address the lack of information in the current literature concerning this demographic, we offer demographic and image findings that demonstrate etiology and predict the need for permanent cerebrospinal fluid (CSF) diversion.

METHODS

A prospectively maintained database was queried for all patients with intraventricular hemorrhage from 2016 to 2020 treated at our institution. Demographic data and etiology were collected, along with need for and timing of surgical intervention.

RESULTS

A total of 150 IVH patients were identified. Of these patients, 138 were excluded due to prematurity. Twelve patients were born at term with IVH. All patients were followed for at least 8 months. Seven patients (58.3%) underwent ventriculoperitoneal (VP) shunt placement, performed between 4 days and 4 months of age. Superficial siderosis detected by MRI during in-patient stay or follow-up showed a sensitivity of 100% and specificity of 60% for the future development of post-hemorrhagic hydrocephalus (PHH) (p < 0.05). All full-term infants who developed PHH (n = 7, 58.3%) obtained a VP shunt.

CONCLUSION

IVH in term infants occurs infrequently when compared to IVH of prematurity. Etiology of IVH in term infants remains difficult to ascertain, but the majority of patients did demonstrate risk factors. The presence of superficial siderosis on MRI significantly predicted the development of PHH and eventual need for CSF diversion.

Complement Drives Chronic Inflammation and Progressive Hydrocephalus in Murine Neonatal Germinal Matrix Hemorrhage

Germinal matrix hemorrhage (GMH) is a pathology that occurs in infancy, with often devastating long-term consequences. Posthemorrhagic hydrocephalus (PHH) can develop acutely, while periventricular leukomalacia (PVL) is a chronic sequala. There are no pharmacological therapies to treat PHH and PVL. We investigated different aspects of the complement pathway in acute and chronic outcomes after murine neonatal GMH induced at postnatal day 4 (P4). Following GMH-induction, the cytolytic complement membrane attack complex (MAC) colocalized with infiltrating red blood cells (RBCs) acutely but not in animals treated with the complement inhibitor CR2-Crry. Acute MAC deposition on RBCs was associated with heme oxygenase-1 expression and heme and iron deposition, which was reduced with CR2-Crry treatment. Complement inhibition also reduced hydrocephalus and improved survival. Following GMH, there were structural alterations in specific brain regions linked to motor and cognitive functions, and these changes were ameliorated by CR2-Crry, as measured at various timepoints through P90. Astrocytosis was reduced in CR2-Crry-treated animals at chronic, but not acute, timepoints. At P90, myelin basic protein and LAMP-1 colocalized, indicating chronic ongoing phagocytosis of white matter, which was reduced by CR2-Crry treatment. Data indicate acute MAC-mediated iron-related toxicity and inflammation exacerbated the chronic effects of GMH.

An invertebrate model in examining the effect of acute ferric iron exposure on proprioceptive neurons

Iron is an essential element for plant and animal life and is found in soil, fresh waters and marine waters. The Fe³⁺ ion is a vital prosthetic group and cofactor to mitochondrial electron transport complexes and numerous proteins involved in normal functioning. Despite its importance to life-sustaining processes, overexposure results in toxicity. For example, ferric iron (Fe³⁺) accumulation in the mammalian central nervous system is associated with various neurological disorders. Although current literature addresses the long-term effects of Fe³⁺ overload, fewer studies exist examining the effects of acute exposure. Using the blue crab (Callinectes sapidus), we investigate the effects of acute Fe³⁺ overload on proprioception within the propodite-dactylopodite (PD) nerve. For proprioceptive studies, 10- and 20-mM ferric chloride and ferric ammonium citrate solutions were used at 5- and 20- min exposure times. Exposure to 20 mM concentrations of ferric chloride and ferric ammonium citrate reduced excitability in proprioceptive neurons. Thus, Fe³⁺ likely blocks stretch-activated channels or voltage-gated Na⁺ channels. The depressive effects of Fe³⁺ are partly reversible following saline washout, indicating cells are not acutely damaged. Gadolinium (GdCl₃, 1 and 10 mM) was used to examine the effects of an additional trivalent ion comparator. Gd³⁺ depressed PD nerve compound action potential amplitude while increasing the compound action potential duration. This study is relevant in demonstrating the dose-dependent effects of acute Fe³⁺ and Gd³⁺ exposure on proprioception and provides a model system to further investigate the mechanisms by which metals act on the nervous system.

Iron-Induced Hydrocephalus: the Role of Choroid Plexus Stromal Macrophages

Evidence indicates that erythrocyte-derived iron and inflammation both play a role in intraventricular hemorrhage-induced brain injury including hydrocephalus. Many immune-associated cells, primarily stromal macrophages, reside at the choroid plexus where they are involved in inflammatory responses and antigen presentation. However, whether intraventricular iron impacts those stromal cells is unknown. The aim of this study was to evaluate the relationship between choroid plexus stromal macrophages and iron-induced hydrocephalus in rats and the impact of minocycline and clodronate liposomes on those changes. Aged (18-month-old) and young (3-month-old) male Fischer 344 rats were used to study choroid plexus stromal macrophages. Rats underwent intraventricular iron injection to induce hydrocephalus and treated with either minocycline, a microglia/macrophage inhibitor, or clodronate liposomes, a macrophage depleting agent. Ventricular volume was measured using magnetic resonance imaging, and stromal macrophages were quantified by immunofluorescence staining. We found that stromal macrophages accounted for about 10% of the total choroid plexus cells with more in aged rats. In both aged and young rats, intraventricular iron injection resulted in hydrocephalus and increased stromal macrophage number. Minocycline or clodronate liposomes ameliorated iron-induced hydrocephalus and the increase in stromal macrophages. In conclusion, stromal macrophages account for ~10% of all choroid plexus cells, with more in aged rats. Treatments targeting macrophages (minocycline and clodronate liposomes) are associated with reduced iron-induced hydrocephalus.

Brain edema formation and therapy after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) accounts for about 10% of all strokes in the United States of America causing a high degree of disability and mortality. There is initial (primary) brain injury due to the mechanical disruption caused by the hematoma. There is then secondary injury, triggered by the initial injury but also the release of various clot-derived factors (e.g., thrombin and hemoglobin). ICH alters brain fluid homeostasis. Apart from the initial hematoma mass, ICH causes blood-brain barrier disruption and parenchymal cell swelling, which result in brain edema and intracranial hypertension affecting patient prognosis. Reducing brain edema is a critical part of post-ICH care. However, there are limited effective treatment methods for reducing perihematomal cerebral edema and intracranial pressure in ICH. This review discusses the mechanisms underlying perihematomal brain edema formation, the effects of sex and age, as well as how edema is resolved. It examines progress in pharmacotherapy, particularly focusing on drugs which have been or are currently being investigated in clinical trials.

The role of lipocalin 2 in brain injury and recovery after ischemic and hemorrhagic stroke

Ischemic and hemorrhagic stroke (including intracerebral hemorrhage, intraventricular hemorrhage, and subarachnoid hemorrhage) is the dominating cause of disability and death worldwide. Neuroinflammation, blood–brain barrier (BBB) disruption, neuronal death are the main pathological progress, which eventually causes brain injury. Increasing evidence indicated that lipocalin 2 (LCN2), a 25k-Da acute phase protein from the lipocalin superfamily, significantly increased immediately after the stroke and played a vital role in these events. Meanwhile, there exists a close relationship between LCN2 levels and the worse clinical outcome of patients with stroke. Further research revealed that LCN2 elimination is associated with reduced immune infiltrates, infarct volume, brain edema, BBB leakage, neuronal death, and neurological deficits. However, some studies revealed that LCN2 might also act as a beneficial factor in ischemic stroke. Nevertheless, the specific mechanism of LCN2 and its primary receptors (24p3R and megalin) involving in brain injury remains unclear. Therefore, it is necessary to investigate the mechanism of LCN2 induced brain damage after stroke. This review focuses on the role of LCN2 and its receptors in brain injury and aiming to find out possible therapeutic targets to reduce brain damage following stroke.

Immune activation after intraventricular hemorrhage

OBJECTIVES

Intraventricular hemorrhage (IVH) is a subtype of stroke which has high mortality and morbidity, while comprehensive mechanism investigations and effective therapies are still in great need. Plenty of studies have shown that inflammation after stroke plays a critical role in disease outcomes. However, the inflammation after IVH remains unclear. This study aims to observe the immune response after IVH, thus providing therapeutic targets for IVH treatments.

MATERIALS AND METHODS

IVH was induced by autologous blood infusion model in SD rats. Totally 588 rats were assigned either in the sham or IVH group. T2* lesion and hemoglobin quantities, ventricular volume, brain edema, ventricular wall damage, blood-brain-barrier (BBB) continuity and immune response were observed by magnetic resonance image (MRI), hematoxylin-eosin staining (HE), Evans Blue, flow cytometry (FACS), and enzyme-linked immunosorbent assay (ELISA) at baseline, 6 h, 1 d, 3 d, 7 d, 14 d after surgery.

RESULTS

We found that ventricular volume enlargement occurred hours after IVH and peaked at 3 d after IVH, then mildly reduced till 14 d. Similar changes happened in brain edema, ventricular wall damage and BBB leakage. Immune cells and cytokines in the central nervous system and peripheral blood also increased after IVH and experienced similar trends as ventricular enlargement. T2* lesion and hemoglobin degradation occurred 6 h after IVH and kept decreasing till 14 d after IVH.

CONCLUSIONS

Our investigation illustrates that immune response exists after IVH, which may have a close relationship with disease outcomes. These results may provide promising immune related clues for mechanism and intervention studies in IVH.

Posthemorrhagic hydrocephalus associates with elevated inflammation and CSF hypersecretion via activation of choroidal transporters

INTRODUCTION

Posthemorrhagic hydrocephalus (PHH) often develops following hemorrhagic events such as intraventricular hemorrhage (IVH) and subarachnoid hemorrhage (SAH). Treatment is limited to surgical diversion of the cerebrospinal fluid (CSF) since no efficient pharmacological therapies are available. This limitation follows from our incomplete knowledge of the molecular mechanisms underlying the ventriculomegaly characteristic of PHH. Here, we aimed to elucidate the molecular coupling between a hemorrhagic event and the subsequent PHH development, and reveal the inflammatory profile of the PHH pathogenesis.

METHODS

CSF obtained from patients with SAH was analyzed for inflammatory markers using the proximity extension assay (PEA) technique. We employed an in vivo rat model of IVH to determine ventricular size, brain water content, intracranial pressure, and CSF secretion rate, as well as for transcriptomic analysis. Ex vivo radio-isotope assays of choroid plexus transport were employed to determine the direct effect of choroidal exposure to blood and inflammatory markers, both with acutely isolated choroid plexus and after prolonged exposure obtained with viable choroid plexus kept in tissue culture conditions.

RESULTS

The rat model of IVH demonstrated PHH and associated CSF hypersecretion. The Na+/K+-ATPase activity was enhanced in choroid plexus isolated from IVH rats, but not directly stimulated by blood components. Inflammatory markers that were elevated in SAH patient CSF acted on immune receptors upregulated in IVH rat choroid plexus and caused Na+/K+/2Cl- cotransporter 1 (NKCC1) hyperactivity in ex vivo experimental conditions.

CONCLUSIONS

CSF hypersecretion may contribute to PHH development, likely due to hyperactivity of choroid plexus transporters. The hemorrhage-induced inflammation detected in CSF and in the choroid plexus tissue may represent the underlying pathology. Therapeutic targeting of such pathways may be employed in future treatment strategies towards PHH patients.

Metformin Preserves VE–Cadherin in Choroid Plexus and Attenuates Hydrocephalus via VEGF/VEGFR2/p-Src in an Intraventricular Hemorrhage Rat Model

Hydrocephalus induced by intraventricular hemorrhage (IVH) is associated with unfavorable prognosis. The increased permeability of choroid plexus and breakdown of the blood–brain barrier (BBB) was reported as a prominent mechanism of IVH-induced hydrocephalus, and vascular endothelial–cadherin (VE–cadherin) was demonstrated to be relevant. Metformin was reported to protect endothelial junction and preserve permeability widely; however, its role in hydrocephalus remains unclear. In this study, the decreased expression of VE–cadherin in the choroid plexus, accompanied with ventricle dilation, was investigated in an IVH rat model induced by intraventricular injection of autologous blood. Metformin treatment ameliorated hydrocephalus and upregulated VE–cadherin expression in choroid plexus meanwhile. We then observed that the internalization of VE–cadherin caused by the activation of vascular endothelial growth factor (VEGF) signaling after IVH was related to the occurrence of hydrocephalus, whereas it can be reversed by metformin treatment. Restraining VEGF signaling by antagonizing VEGFR2 or inhibiting Src phosphorylation increased the expression of VE–cadherin and decreased the severity of hydrocephalus after IVH. Our study demonstrated that the internalization of VE–cadherin via the activation of VEGF signaling may contribute to IVH-induced hydrocephalus, and metformin may be a potential protector via suppressing this pathway.

Elevated cerebrospinal fluid iron and ferritin associated with early severe ventriculomegaly in preterm posthemorrhagic hydrocephalus

OBJECTIVE

Posthemorrhagic hydrocephalus (PHH) following preterm intraventricular hemorrhage (IVH) is among the most severe sequelae of extreme prematurity and a significant contributor to preterm morbidity and mortality. The authors have previously shown hemoglobin and ferritin to be elevated in the lumbar puncture cerebrospinal fluid (CSF) of neonates with PHH. Herein, they evaluated CSF from serial ventricular taps to determine whether neonates with PHH following severe initial ventriculomegaly had higher initial levels and prolonged clearance of CSF hemoglobin and hemoglobin degradation products compared to those in neonates with PHH following moderate initial ventriculomegaly.

METHODS

In this observational cohort study, CSF samples were obtained from serial ventricular taps in premature neonates with severe IVH and subsequent PHH. CSF hemoglobin, ferritin, total iron, total bilirubin, and total protein were quantified using ELISA. Ventriculomegaly on cranial imaging was assessed using the frontal occipital horn ratio (FOHR) and was categorized as severe (FOHR > 0.6) or moderate (FOHR ≤ 0.6).

RESULTS

Ventricular tap CSF hemoglobin (mean) and ferritin (initial and mean) were higher in neonates with severe versus moderate initial ventriculomegaly. CSF hemoglobin, ferritin, total iron, total bilirubin, and total protein decreased in a nonlinear fashion over the weeks following severe IVH. Significantly higher levels of CSF ferritin and total iron were observed in the early weeks following IVH in neonates with severe initial ventriculomegaly than in those with initial moderate ventriculomegaly.

CONCLUSIONS

Among preterm neonates with PHH following severe IVH, elevated CSF hemoglobin, ferritin, and iron were associated with more severe early ventricular enlargement (FOHR > 0.6 vs ≤ 0.6 at first ventricular tap).

Navigating the ventricles: Novel insights into the pathogenesis of hydrocephalus

Congenital hydrocephalus occurs in one in 500-1000 babies born in the United States and acquired hydrocephalus may occur as the consequence of stroke, intraventricular and subarachnoid hemorrhage, traumatic brain injuries, brain tumors, craniectomy or may be idiopathic, as in the case of normal pressure hydrocephalus. Irrespective of its prevalence and significant impact on quality of life, neurosurgeons still rely on invasive cerebrospinal fluid shunt systems for the treatment of hydrocephalus that are exceptionally prone to failure and/or infection. Further understanding of this process at a molecular level, therefore, may have profound implications for improving treatment and quality of life for millions of individuals worldwide. The purpose of this article is to review the current research landscape on hydrocephalus with a focus on recent advances in our understanding of cerebrospinal fluid pathways from an evolutionary, genetics and molecular perspective.

Mechanisms of neuroinflammation in hydrocephalus after intraventricular hemorrhage: a review

Intraventricular hemorrhage (IVH) is a significant cause of morbidity and mortality in both neonatal and adult populations. IVH not only causes immediate damage to surrounding structures by way of mass effect and elevated intracranial pressure; the subsequent inflammation causes additional brain injury and edema. Of those neonates who experience severe IVH, 25-30% will go on to develop post-hemorrhagic hydrocephalus (PHH). PHH places neonates and adults at risk for white matter injury, seizures, and death. Unfortunately, the molecular determinants of PHH are not well understood. Within the past decade an emphasis has been placed on neuroinflammation in IVH and PHH. More information has come to light regarding inflammation-induced fibrosis and cerebrospinal fluid hypersecretion in response to IVH. The aim of this review is to discuss the role of neuroinflammation involving clot-derived neuroinflammatory factors including hemoglobin/iron, peroxiredoxin-2 and thrombin, as well as macrophages/microglia, cytokines and complement in the development of PHH. Understanding the mechanisms of neuroinflammation after IVH may highlight potential novel therapeutic targets for PHH.

Canonical Wnt Signaling in the Pathology of Iron Overload-Induced Oxidative Stress and Age-Related Diseases

Iron accumulates in the vital organs with aging. This is associated with oxidative stress, inflammation, and mitochondrial dysfunction leading to age-related disorders. Abnormal iron levels are linked to neurodegenerative diseases, liver injury, cancer, and ocular diseases. Canonical Wnt signaling is an evolutionarily conserved signaling pathway that regulates many cellular functions including cell proliferation, apoptosis, cell migration, and stem cell renewal. Recent evidences indicate that iron regulates Wnt signaling, and iron chelators like deferoxamine and deferasirox can inhibit Wnt signaling and cell growth. Canonical Wnt signaling is implicated in the pathogenesis of many diseases, and there are significant efforts ongoing to develop innovative therapies targeting the aberrant Wnt signaling. This review examines how intracellular iron accumulation regulates Wnt signaling in various tissues and their potential contribution in the progression of age-related diseases.

The role of cell-free DNA in fibrinolysis for intraventricular hemorrhage

OBJECTIVE

Tissue plasminogen activator (tPA) fibrinolysis did not improve functional outcomes of patients with intraventricular hemorrhage (IVH), largely because of the unsatisfactory clot clearance. The presence of neutrophil extracellular traps (NETs) within the clot has been confirmed to impair tPA fibrinolysis, but the mechanism has been unclear. The authors hypothesized that cell-free DNA (cfDNA), the main framework of NETs, might be the important reason for the fibrinolysis resistance, and they validated the hypothesis, hoping to provide a new target to promote intraventricular fibrinolysis.

METHODS

First, cfDNA was detected in IVH clots by immunofluorescence staining in a rat model of IVH. Second, after blood (with or without exogenous cfDNA) intraventricular injection, IVH rats were given intraventricular infusion of 2 μl of saline, tPA, or tPA + DNase1 randomly. Then, the ventricular volume, animal behavior, and reactive astrocyte proliferation were assessed. Third, the IVH clots were collected for fibrinolysis assay in vitro. Finally, the effects of exogenous cfDNA in IVH were evaluated.

RESULTS

The presence of cfDNA in clots was observed as early as 1 hour after IVH. Compared with the whole-blood model, blood + cfDNA caused more severe ventricular dilation (day 7: blood 32.47 ± 2.096 mm3 vs blood + DNA 40.09 ± 2.787 mm3, p < 0.05), increased fibrinolysis resistance to tPA (day 7: tPA + DNA 26.04 ± 1.318 mm3 vs tPA 22.15 ± 1.706 mm3, p < 0.05), and further deteriorated the functional defects in rats (blood vs blood + DNA, p < 0.05). Degradation of cfDNA by DNase1 further enhanced the fibrinolysis effects on relieving the ventricular dilation (day 7: tPA + DNase1 11.67 ± 2.023 mm3 vs tPA, p < 0.05), improving the functional outcome (tPA vs tPA + DNase1, p < 0.05) and reducing periventricular astrocyte proliferation.

CONCLUSIONS

cfDNA impaired tPA fibrinolysis for IVH, and degradation of cfDNA may be a new target to improve this condition.

External ventricular drainage for posthemorrhagic ventricular dilatation in preterm infants: insights on efficacy and failure

OBJECTIVE

The objective of this study was to describe the clinical and neuroradiological characteristics of a cohort of preterm infants who had undergone external ventricular drain insertion as a temporary measure to treat posthemorrhagic ventricular dilatation. In addition, the authors investigated the factors predicting permanent shunt dependency.

METHODS

The authors retrospectively reviewed the medical records of a cohort of preterm infants who had undergone external ventricular drain insertion at Gaslini Children's Hospital (Genoa, Italy) between March 2012 and February 2018. They also analyzed clinical characteristics and magnetic resonance imaging data, including diffusion- and susceptibility-weighted imaging studies, which were obtained before both catheter insertion and removal.

RESULTS

Twenty-eight infants were included in the study. The mean gestational age was 28.2 ± 2.7 weeks, and the mean birth weight was 1209 ± 476 g. A permanent ventriculoperitoneal shunt was inserted in 15/28 (53.6%) infants because of the failure of external ventricular drainage as a temporary treatment option. Compared with the shunt-free group, the shunt-dependent group had a significantly lower gestational age (29.3 ± 2.3 vs 27.2 ± 2.7 weeks, p = 0.035) and tended toward a lower birth weight (p = 0.056). None of the clinical and neuroradiological characteristics significantly differed between the shunt-free and shunt-dependent groups at the time of catheter insertion. As expected, ventricular parameters as well as the intraventricular extension of intracerebral hemorrhage, as assessed using the intraventricular hemorrhage score, were reportedly higher in the shunt-dependent group than in the shunt-free group before catheter removal.

CONCLUSIONS

External ventricular drainage is a reliable first-line treatment for posthemorrhagic hydrocephalus. However, predicting its efficacy as a unique treatment remains challenging. A lower gestational age is associated with a higher risk of posthemorrhagic hydrocephalus progression, suggesting that the more undeveloped the mechanisms for the clearance of blood degradation products, the greater the risk of requiring permanent cerebrospinal fluid diversion, although sophisticated MRI investigations are currently unable to corroborate this hypothesis.

Turkish Neonatal Society Guideline on the Diagnosis and Management of Germinal Matrix Hemorrhage-Intraventricular Hemorrhage and Related Complications

Germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH) remains an important cause of brain injury in preterm infants, and is associated with high rates of mortality and adverse neurodevelopmental outcomes, despite the recent advances in perinatal care. Close neuroimaging is recommended for both the detection of GMH-IVH and for the follow-up of serious complications, such as post-hemorrhagic ventricular dilatation (PHVD). Although the question when best to treat PHVD remains a matter of debate, recent literature on this topic shows that later timing of interventions predicted higher rates of neurodevelopmental impairment, emphasizing the importance of a well-structured neuroimaging protocol and timely interventions. In this guideline, pathophysiologic mechanisms, preventive measures, and clinical presentations of GMH-IVH and PHVD will be presented, and a neuroimaging protocol as well as an optimal treatment approach will be proposed in light of the recent literature.

Impact of sex differences on thrombin-induced hydrocephalus and white matter injury: the role of neutrophils

BACKGROUND

Thrombin has been implicated in playing a role in hydrocephalus development following intraventricular hemorrhage (IVH). However, the mechanisms underlying the sex differences to the detrimental effects of thrombin post-IVH remain elusive.

METHOD

Three-month old male and female Sprague-Dawley rats underwent unilateral intracerebroventricular (ICV) injections of 3U or 5U thrombin, or saline, to examine differences in thrombin-induced hydrocephalus and white matter injury. Mortality, and lateral ventricle volume and white matter injury were measured on magnetic resonance imaging evaluation at 24 h post-injection. In addition, male rats were pretreated with 17-β estradiol (E2, 5 mg/kg) or vehicle at 24 and 2 h prior to ICV injection of 3U thrombin. All rats were euthanized at 24 h post-injection for histology and immunohistochemistry.

RESULTS

ICV injection of 5U thrombin caused 100 and 0% mortality in female and male rats, respectively. 3U of thrombin resulted in significant ventricular dilation and white matter damage at 24 h in both male and female rats, but both were worse in females (p < 0.05). Furthermore, neutrophil infiltration into choroid plexus and periventricular white matter was enhanced in female rats and may play a critical role in the sex difference in brain injury. Pre-treating male rats with E2, increased thrombin (3U)-induced hydrocephalus, periventricular white matter injury and neutrophil infiltration into the choroid plexus and white matter.

CONCLUSIONS

ICV thrombin injection induced more severe ventricular dilation and white matter damage in female rats compared to males. Estrogen appears to contribute to this difference which may involve greater neutrophil infiltration in females. Understanding sex differences in thrombin-induced brain injury may shed light on future interventions for hemorrhagic stroke.

Cumulative Damage: Cell Death in Posthemorrhagic Hydrocephalus of Prematurity

Globally, approximately 11% of all infants are born preterm, prior to 37 weeks’ gestation. In these high-risk neonates, encephalopathy of prematurity (EoP) is a major cause of both morbidity and mortality, especially for neonates who are born very preterm (<32 weeks gestation). EoP encompasses numerous types of preterm birth-related brain abnormalities and injuries, and can culminate in a diverse array of neurodevelopmental impairments. Of note, posthemorrhagic hydrocephalus of prematurity (PHHP) can be conceptualized as a severe manifestation of EoP. PHHP impacts the immature neonatal brain at a crucial timepoint during neurodevelopment, and can result in permanent, detrimental consequences to not only cerebrospinal fluid (CSF) dynamics, but also to white and gray matter development. In this review, the relevant literature related to the diverse mechanisms of cell death in the setting of PHHP will be thoroughly discussed. Loss of the epithelial cells of the choroid plexus, ependymal cells and their motile cilia, and cellular structures within the glymphatic system are of particular interest. Greater insights into the injuries, initiating targets, and downstream signaling pathways involved in excess cell death shed light on promising areas for therapeutic intervention. This will bolster current efforts to prevent, mitigate, and reverse the consequential brain remodeling that occurs as a result of hydrocephalus and other components of EoP.

Longitudinal CSF Iron Pathway Proteins in Posthemorrhagic Hydrocephalus: Associations with Ventricle Size and Neurodevelopmental Outcomes

OBJECTIVE

Iron has been implicated in the pathogenesis of brain injury and hydrocephalus after preterm germinal matrix hemorrhage-intraventricular hemorrhage, however, it is unknown how external or endogenous intraventricular clearance of iron pathway proteins affect the outcome in this group.

METHODS

This prospective multicenter cohort included patients with posthemorrhagic hydrocephalus (PHH) who underwent (1) temporary and permanent cerebrospinal fluid (CSF) diversion and (2) Bayley Scales of Infant Development-III testing around 2 years of age. CSF proteins in the iron handling pathway were analyzed longitudinally and compared to ventricle size and neurodevelopmental outcomes.

RESULTS

Thirty-seven patients met inclusion criteria with a median estimated gestational age at birth of 25 weeks; 65% were boys. Ventricular CSF levels of hemoglobin, iron, total bilirubin, and ferritin decreased between temporary and permanent CSF diversion with no change in CSF levels of ceruloplasmin, transferrin, haptoglobin, and hepcidin. There was an increase in CSF hemopexin during this interval. Larger ventricle size at permanent CSF diversion was associated with elevated CSF ferritin (p = 0.015) and decreased CSF hemopexin (p = 0.007). CSF levels of proteins at temporary CSF diversion were not associated with outcome, however, higher CSF transferrin at permanent CSF diversion was associated with improved cognitive outcome (p = 0.015). Importantly, longitudinal change in CSF iron pathway proteins, ferritin (decrease), and transferrin (increase) were associated with improved cognitive (p = 0.04) and motor (p = 0.03) scores and improved cognitive (p = 0.04), language (p = 0.035), and motor (p = 0.008) scores, respectively.

INTERPRETATION

Longitudinal changes in CSF transferrin (increase) and ferritin (decrease) are associated with improved neurodevelopmental outcomes in neonatal PHH, with implications for understanding the pathogenesis of poor outcomes in PHH. ANN NEUROL 2021;90:217-226.

When the Blood Hits Your Brain: The Neurotoxicity of Extravasated Blood

Hemorrhage in the central nervous system (CNS), including intracerebral hemorrhage (ICH), intraventricular hemorrhage (IVH), and aneurysmal subarachnoid hemorrhage (aSAH), remains highly morbid. Trials of medical management for these conditions over recent decades have been largely unsuccessful in improving outcome and reducing mortality. Beyond its role in creating mass effect, the presence of extravasated blood in patients with CNS hemorrhage is generally overlooked. Since trials of surgical intervention to remove CNS hemorrhage have been generally unsuccessful, the potent neurotoxicity of blood is generally viewed as a basic scientific curiosity rather than a clinically meaningful factor. In this review, we evaluate the direct role of blood as a neurotoxin and its subsequent clinical relevance. We first describe the molecular mechanisms of blood neurotoxicity. We then evaluate the clinical literature that directly relates to the evacuation of CNS hemorrhage. We posit that the efficacy of clot removal is a critical factor in outcome following surgical intervention. Future interventions for CNS hemorrhage should be guided by the principle that blood is exquisitely toxic to the brain.

CD47 blocking antibody accelerates hematoma clearance and alleviates hydrocephalus after experimental intraventricular hemorrhage

Background CD47, a glycoprotein on red blood cell membranes, inhibits phagocytosis via interaction with signal regulatory protein α on phagocytes. Our previous research has demonstrated that blocking CD47 accelerates hematoma clearance and reduces brain injury after intracerebral hemorrhage. The current study investigated whether phagocytosis or erythrocyte CD47 impacts hematoma resolution and hydrocephalus development after intraventricular hemorrhage (IVH). Methods Adult (3-month-old) male Fischer 344 rats were intraventricularly injected with 200 μl autologous blood, mixed with either CD47 blocking antibody or isotype IgG, or 200 μl saline as control. In subgroups of CD47 blocking antibody treated rats, clodronate liposomes (to deplete microglia/monocyte-derived macrophages) or control liposomes were co-injected. Magnetic resonance imaging (MRI) was used to evaluate ventricular volume and intraventricular T2* lesion volume (estimating hematoma volume). The brains were harvested after 4 or 72 h for histology to evaluate phagocytosis. Results In adult male rats, CD47 blocking antibody alleviated hydrocephalus development by day 3. In addition, the CD47 blocking antibody reduced intraventricular T2* lesion and T2* non-hypointense lesion size after IVH through day 1 to day 3. Erythrophagocytosis was observed as soon as 4 h after IVH and was enhanced on day 3. Furthermore, intra-hematoma infiltration of CD68, heme oxygenase-1 and ferritin positive phagocytes were upregulated by CD47 blockade by day 3. Clodronate liposomes co-injection caused more severe hydrocephalus and weight loss. Conclusion Blocking CD47 in the hematoma accelerated hematoma clearance and alleviated hemolysis and hydrocephalus development after IVH, suggesting CD47 might be valuable in the future treatment for IVH.

Hemoglobin induces oxidative stress and mitochondrial dysfunction in oligodendrocyte progenitor cells

Oligodendrocyte progenitor cells (OPCs) in the infant brain give rise to mature oligodendrocytes that myelinate CNS axons. OPCs are particularly vulnerable to oxidative stress that occurs in many forms of brain injury. One common cause of infant brain injury is neonatal intraventricular hemorrhage (IVH), which releases blood into the CSF and brain parenchyma of preterm infants. Although blood contains the powerful oxidant hemoglobin, the direct effects of hemoglobin on OPCs have not been studied. We utilized a cell culture system to test if hemoglobin induced free radical production and mitochondrial dysfunction in OPCs. We also tested if phenelzine (PLZ), an FDA-approved antioxidant drug, could protect OPCs from hemoglobin-induced oxidative stress. OPCs were isolated from Sprague Dawley rat pups and exposed to hemoglobin with and without PLZ. Outcomes assessed included intracellular reactive oxygen species levels using 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA) fluorescent dye, oxygen consumption using the XFe96 Seahorse assay, and proliferation measured by BrdU incorporation assay. Hemoglobin induced oxidative stress and impaired mitochondrial function in OPCs. PLZ treatment reduced hemoglobin-induced oxidative stress and improved OPC mitochondrial bioenergetics. The effects of hemoglobin and PLZ on OPC proliferation were not statistically significant, but showed trends towards hemoglobin reducing OPC proliferation and PLZ increasing OPC proliferation (P=0.06 for both effects). Collectively, our results indicate that hemoglobin induces mitochondrial dysfunction in OPCs and that antioxidant therapy reduces these effects. Therefore, antioxidant therapy may hold promise for white matter diseases in which hemoglobin plays a role, such as neonatal IVH.

Hydrocephalus Induced by Intraventricular Peroxiredoxin-2: The Role of Macrophages in the Choroid Plexus

The choroid plexus (CP) is the primary source of cerebrospinal fluid in the central nervous system. Recent evidence indicates that inflammatory pathways at the CP may be involved in hydrocephalus development. Peroxiredoxin 2 (Prx2) is a major component of red blood cells. Extracellular Prx2 is proinflammatory, and its release after red blood cell lysis may contribute to hydrocephalus after intraventricular hemorrhage. This study aimed to identify alterations in CP macrophages and dendritic cells following intracerebroventricular Prx2 injection and investigate the relationship between macrophages/dendritic cells and hydrocephalus. There were two parts to this study. In the first part, adult male Sprague-Dawley rats received an intracerebroventricular injection of Prx2 or saline. In the second part, Prx2 was co-injected with clodronate liposomes or control liposomes. All animals were euthanized at 24 h after magnetic resonance imaging. Immunohistochemistry was used to evaluate macrophages in CP, magnetic resonance imaging to quantify hydrocephalus, and histology to assess ventricular wall damage. The intracerebroventricular injection of Prx2 not only increased the OX-6 positive cells, but it also altered their location in the CP and immunophenotype. Co-injecting clodronate liposomes with Prx2 decreased the number of macrophages and simultaneously attenuated Prx2-induced hydrocephalus and ventricular wall damage. These results suggest that CP macrophages play an essential role in CP inflammation-induced hydrocephalus. These macrophages may be a potential therapeutic target in post-hemorrhagic hydrocephalus.

Cerebrospinal Fluid from Aneurysmal Subarachnoid Hemorrhage Patients Leads to Hydrocephalus in Nude Mice

OBJECTIVE

Our prior studies have found that intracerebroventricular injection of blood components can cause hydrocephalus and choroid plexus epiplexus cell activation in rats. To minimize the cross-species reaction, the current study examines whether intraventricular injection of acellular components of cerebrospinal fluid (CSF) from subarachnoid hemorrhage patients can cause hydrocephalus and epiplexus macrophage activation in nude mice which lack a T cell inflammatory response.

METHODS

Adult male nude mice received intraventricular injections of acellular CSF from subarachnoid hemorrhage patients or a control patient. All mice had preoperative magnetic resonance imaging as baseline and postoperative scans at 24 h after CSF injection to determine ventricular volume. Brains were harvested at 24 h for brain histology, immunohistochemistry, and electron microscopy.

RESULTS

Intraventricular injection of CSF from two of five subarachnoid hemorrhage patients obtained < 48 h from ictus resulted in ventricular enlargement at 24 h. CSF-related hydrocephalus was associated with activation of epiplexus macrophages and ependymal injury.

CONCLUSIONS

Components of the acellular CSF of subarachnoid hemorrhage patients can cause epiplexus macrophage activation, ependymal cell damage, and ventricular enlargement in nude mice. This may serve as a unique model to study mechanisms of hydrocephalus development following subarachnoid hemorrhage.

Optimized lactoferrin as a highly promising treatment for intracerebral hemorrhage: Pre-clinical experience

Intracerebral hemorrhage (ICH) is the deadliest form of stroke for which there is no effective treatment, despite an endless number of pre-clinical studies and clinical trials. The obvious therapeutic target is the neutralization of toxic products of red blood cell (RBC) lysis that lead to cytotoxicity, inflammation, and oxidative damage. We used rigorous approaches and translationally relevant experimental ICH models to show that lactoferrin-(LTF)-based monotherapy is uniquely robust in reducing brain damage after ICH. Specifically, we designed, produced, and pharmacokinetically/toxicologically characterized an optimized LTF, a fusion of human LTF and the Fc domain of human IgG (FcLTF) that has a 5.8-fold longer half-life in the circulation than native LTF. Following dose-optimization studies, we showed that FcLTF reduces neurological injury caused by ICH in aged male/female mice, and in young male Sprague Dawley (SD) and spontaneously hypertensive rats (SHR). FcLTF showed a remarkably long 24-h therapeutic window. In tissue culture systems, FcLTF protected neurons from the toxic effects of RBCs and promoted microglia toward phagocytosis of RBCs and dead neurons, documenting its pleotropic effect. Our findings indicate that FcLTF is safe and effective in reducing ICH-induced damage in animal models used in this study.

Neuroprotective Methodologies of Co-Enzyme Q10 Mediated Brain Hemorrhagic Treatment: Clinical and Pre-Clinical Findings

Cerebral brain hemorrhage is associated with the highest mortality and morbidity despite only constituting approximately 10-15% of all strokes classified into intracerebral and intraventricular hemorrhage where most of the patients suffer from impairment in memory, weakness or paralysis in arms or legs, headache, fatigue, gait abnormality and cognitive dysfunctions. Understanding molecular pathology and finding the worsening cause of hemorrhage will lead to explore the therapeutic interventions that could prevent and cure the disease. Mitochondrial ETC-complexes dysfunction has been found to increase neuroinflammatory cytokines, oxidative free radicals, excitotoxicity, neurotransmitter and energy imbalance that are the key neuropathological hallmarks of cerebral hemorrhage. Coenzyme Q10 (CoQ10), as a part of the mitochondrial respiratory chain can effectively restore these neuronal dysfunctions by preventing the opening of mitochondrial membrane transition pore, thereby counteracting cell death events as well as exerts an anti-inflammatory effect by influencing the expression of NF-kB1 dependent genes thus preventing the neuroinflammation and energy restoration. Due to behavior and biochemical heterogeneity in post cerebral brain hemorrhagic pattern different preclinical autologous blood injection models are required to precisely investigate the forthcoming therapeutic strategies. Despite emerging pre-clinical research and resultant large clinical trials for promising symptomatic treatments, there are very less pharmacological interventions demonstrated to improve post operative condition of patients where intensive care is required. Therefore, in current review, we explore the disease pattern, clinical and pre-clinical interventions under investigation and neuroprotective methodologies of CoQ10 precursors to ameliorate post brain hemorrhagic conditions.

Mechanical injury and blood are drivers of spatial memory deficits after rapid intraventricular hemorrhage

Aneurysmal intraventricular hemorrhage (IVH) survivors may recover with significant deficits in learning and memory. The goal of this study was to investigate the mechanism of memory decline after intraventricular aneurysm rupture. We developed an aneurysmal IVH rat model by injecting autologous, arterial blood over the period of two minutes into the right lateral ventricle. We also evaluated the effects of a volume-matched artificial cerebrospinal fluid (CSF) control, thrombin and the mode of delivery (pulsed hand injection versus continuous pump infusion). We performed magnetic resonance brain imaging after 1 and 5 weeks to evaluate for hydrocephalus and histological analysis of the dentate gyrus after 6 weeks. Only animals which underwent a whole blood pulsed hand injection had a spatial memory acquisition and retention deficit 5 weeks later. These animals had larger ventricles at 1 and 5 weeks than animals which underwent a continuous pump infusion of whole blood. We did not find a decline in dentate gyrus granule cell neurons or an impairment in dentate gyrus neurogenesis or differentiation 6 weeks after IVH. Rapid injections of blood or volume resulted in microglial activation in the dentate gyrus. In conclusion, our results point to mechanical injury as the predominant mechanism of memory decline after intraventricular aneurysmal rupture. However, volume-matched pulsed injections of artificial CSF did not create a spatial memory deficit at 5 weeks. Therefore, whole blood itself must play a role in the mechanism. Further research is required to evaluate whether the viscosity of blood causes additional mechanical disruption and hydrocephalus through a primary injury mechanism or whether the toxicity of blood causes a secondary injury mechanism that leads to the observed spatial memory deficit after 5 weeks.

Lactoferrin and hematoma detoxification after intracerebral hemorrhage

In this minireview we discuss the role of lactoferrin (LTF) in detoxifying hematoma after intracerebral hemorrhage (ICH). Subsequent to ICH, neutrophils enter the ICH-affected brain, where they release various granule contents, including LTF. LTF is an iron-binding glycoprotein that binds Fe³⁺ with high affinity. Unlike other iron-binding proteins, LTF can retain Fe³⁺ at the low pH associated with inflamed tissue. LTF's ability to sequester Fe³⁺ is of particular importance to ICH pathogenesis, because large quantities of free iron, which is pro-oxidative and pro-inflammatory, are generated in the ICH-affected brain owing to blood hemolysis. LTF delivered to ICH-affected brain, either as a therapeutic agent or through infiltrated polymorphonuclear neutrophils (cells containing high levels of LTF), could limit the pathogenesis of ICH. LTF is a protein with a high isoelectric point (8.7), a property that enables it to bind to negatively-charged apoptotic cells or proteins. Here, LTF could act as a bridging molecule that couples the apoptotic cells to LTF receptors on the cellular membranes of microglia/macrophages to facilitate the efferocytosis/erythrophagocytosis of apoptotic cells and damaged red blood cells. Thus, by virtue of sequestrating iron and facilitating efferocytosis, LTF may contribute to hematoma detoxification and hematoma/inflammation resolution after ICH.

Intraventricular Hemorrhage and White Matter Injury in Preclinical and Clinical Studies

Germinal matrix-intraventricular hemorrhage (IVH) occurs in nearly half of infants born at less than 26 weeks' gestation. Up to 50% of survivors with IVH develop cerebral palsy, cognitive deficits, behavioral disorders, posthemorrhagic ventricular dilatation, or a combination of these sequelae. After the initial bleeding and the primary brain injury, inflammation and secondary brain injury might lead to periventricular leukomalacia or diffuse white matter injury. Potential factors that are involved include microglia and astrocyte activation, degradation of blood components with release of "toxic" products, infiltration of the brain by systemic immune cells, death of neuronal and glial cells, and arrest of preoligodendrocyte maturation. In addition, impairment of the blood-brain barrier may play a major role in the pathophysiology. A wide range of animal models has been used to explore causes and mechanisms leading to IVH-induced brain injury. Preclinical studies have identified potential targets for enhancing brain repair. However, little has been elucidated about the effectiveness of potential interventions in clinical studies. A systematic review of available preclinical and clinical studies might help identify research gaps and which types of interventions may be prioritized. Future trials should report clinically robust and long-term outcomes after IVH.

uPA alleviates kaolin-induced hydrocephalus by promoting the release and activation of hepatocyte growth factor in rats

Urokinase-type plasminogen activator (uPA) was demonstrated to alleviate kaolin-induced communicating hydrocephalus via inhibiting subarachnoid space fibrosis, but the exact mechanism remains elusive. Thus, this study was designed to investigate if hepatocyte growth factor (HGF), which plays a vital role in uPA-triggered inhibiting of fibrosis in multiple systems, is involved in this process in hydrocephalus. There were 2 parts in this study. First, hydrocephalus was induced in rats by basal cistern injection of kaolin. Then rats were treated with saline or uPA and brain tissue and CSF were collected for Western blot and enzyme-linked immuno sorbent assay (ELISA) four days later. Second, kaolin-induced hydrocephalus rats were treated with saline, uPA, uPA + PHA665752 (antagonist of HGF) or PHA665752. Some animals received MRI four weeks later and brains were used for immunofluorescence. The others were euthanized four days later for ELISA. Both levels of total and activated HGF in the CSF was increased after uPA injections, but related mRNA expression of HGF showed no statistical significance when compared with the control group. Further, the effects of uPA that alleviating ventricular enlargement, subarachnoid fibrosis and reactive astrocytosis were partially reversed by PHA665752. Moreover, PHA665752 partially abolished uPA-induced reduction of transforming growth factor- β1(TGF- β1) level in CSF. Our data suggest that uPA effectively inhibited subarachnoid fibrosis and restricted the development of communicating hydrocephalus in rats in part by promoting HGF release and activation, which may further regulate the TGF-β1 expression in CSF.

Intraventricular Hemorrhage Clearance in Human Neonatal Cerebrospinal Fluid: Associations With Hydrocephalus

Background and Purpose- Preterm neonates with intraventricular hemorrhage (IVH) are at risk for posthemorrhagic hydrocephalus and poor neurological outcomes. Iron has been implicated in ventriculomegaly, hippocampal injury, and poor outcomes following IVH. We hypothesized that levels of cerebrospinal fluid blood breakdown products and endogenous iron clearance proteins in neonates with IVH differ from those of neonates with IVH who subsequently develop posthemorrhagic hydrocephalus. Methods- Premature neonates with an estimated gestational age at birth <30 weeks who underwent lumbar puncture for clinical evaluation an average of 2 weeks after birth were evaluated. Groups consisted of controls (n=16), low-grade IVH (grades I-II; n=4), high-grade IVH (grades III-IV; n=6), and posthemorrhagic hydrocephalus (n=9). Control subjects were preterm neonates born at <30 weeks' gestation without brain abnormality or hemorrhage on cranial ultrasound, who underwent lumbar puncture for clinical purposes. Cerebrospinal fluid hemoglobin, total bilirubin, total iron, ferritin, ceruloplasmin, transferrin, haptoglobin, and hemopexin were quantified. Results- Cerebrospinal fluid hemoglobin levels were increased in posthemorrhagic hydrocephalus compared with high-grade IVH (9.45 versus 6.06 µg/mL, P<0.05) and cerebrospinal fluid ferritin levels were increased in posthemorrhagic hydrocephalus compared with controls (511.33 versus 67.08, P<0.01). No significant group differences existed for the other cerebrospinal fluid blood breakdown and iron-handling proteins tested. We observed positive correlations between ventricular enlargement (frontal occipital horn ratio) and ferritin (Pearson r=0.67), hemoglobin (Pearson r=0.68), and total bilirubin (Pearson r=0.69). Conclusions- Neonates with posthemorrhagic hydrocephalus had significantly higher levels of hemoglobin than those with high-grade IVH. Levels of blood breakdown products, hemoglobin, ferritin, and bilirubin correlated with ventricular size. There was no elevation of several iron-scavenging proteins in cerebrospinal fluid in neonates with posthemorrhagic hydrocpehalus, indicative of posthemorrhagic hydrocephalus as a disease state occurring when endogenous iron clearance mechanisms are overwhelmed.

Prx2 (Peroxiredoxin 2) as a Cause of Hydrocephalus After Intraventricular Hemorrhage

Background and Purpose- Our recent study demonstrated that release of Prx2 (peroxiredoxin 2) from red blood cells (RBCs) is involved in the inflammatory response and brain injury after intracerebral hemorrhage. The current study investigated the role of extracellular Prx2 in hydrocephalus development after experimental intraventricular hemorrhage. Methods- There were 4 parts in this study. First, Sprague-Dawley rats received an intraventricular injection of lysed RBC or saline and were euthanized at 1 hour for Prx2 measurements. Second, rats received an intraventricular injection of Prx2, deactivated Prx2, or saline. Third, lysed RBC was coinjected with conoidin A, a Prx2 inhibitor, or vehicle. Fourth, rats received Prx2 injection and were treated with minocycline or saline (i.p.). The effects of Prx2 and the inhibitors were examined using magnetic resonance imaging assessing ventriculomegaly, histology assessing ventricular wall damage, and immunohistochemistry to assess inflammation, particularly at the choroid plexus. Results- Intraventricular injection of lysed RBC resulted in increased brain Prx2 and hydrocephalus. Intraventricular injection of Prx2 alone caused hydrocephalus, ventricular wall damage, activation of choroid plexus epiplexus cells (macrophages), and an accumulation of neutrophils. Conoidin A attenuated lysed RBC-induced injury. Systemic minocycline treatment reduced the epiplexus cell activation and hydrocephalus induced by Prx2. Conclusions- Prx2 contributed to the intraventricular hemorrhage-induced hydrocephalus, probably by inducing inflammatory responses in choroid plexus and ventricular wall damage.

Cranial ultrasound findings in preterm germinal matrix haemorrhage, sequelae and outcome

Germinal matrix-intraventricular haemorrhage (GMH-IVH), periventricular haemorrhagic infarction (PHI) and its complication, post-haemorrhagic ventricular dilatation (PHVD), are still common neonatal morbidities in preterm infants that are highly associated with adverse neurodevelopmental outcome. Typical cranial ultrasound (CUS) findings of GMH-IVH, PHI and PHVD, their anatomical substrates and underlying mechanisms are discussed in this paper. Furthermore, we propose a detailed descriptive classification of GMH-IVH and PHI that may improve quality of CUS reporting and prediction of outcome in infants suffering from GMH-IVH/PHI.

Effects of aging on hydrocephalus after intraventricular hemorrhage

BACKGROUND

Hydrocephalus is a common and major complication that affects outcome after intraventricular hemorrhage (IVH). While aging impacts the occurrence of hydrocephalus in patients with IVH this and the underlying mechanisms have received little attention. The present investigation, therefore, studied the impact of aging on hydrocephalus after IVH in a rat model.

METHODS

Young and aged (3 and 18 months old, respectively) male Fischer 344 rats had an intraventricular injection of 200 μl autologous blood or saline. Ventricular volume was estimated using magnetic resonance imaging (MRI), while ventricular wall damage, heme oxygenase-1 (HO-1) and epiplexus cell activation were quantified by histological staining and Western blot. Additionally, the impact of intraventricular iron injection was examined in young and aged rats.

RESULTS

Intraventricular injection of autologous blood induced hydrocephalus in both young and aged rats but ventricular volumes were larger in aged rats compared to young rats from day 3 to day 14 followed IVH. In addition, ventricular wall damage and periventricular HO-1 upregulation were greater in aged versus young rats on day 1 after IVH. Aged rats also had more choroid plexus epiplexus cells on day 14 after IVH. Additionally, organized hematomas were observed in 23% (3/13) of aged rats but not in young rats after IVH. Organized hematomas in aged rats showed larger T2* lesions on MRI compared to rats with non-organized hematomas. Similar to the effects of IVH, intraventricular injection of iron resulted in more epiplexus cells activation and more severe hydrocephalus in aged compared to young rats.

CONCLUSIONS

IVH causes more severe hydrocephalus in aged compared to young rats. Enhanced ventricular wall damage, epiplexus cell activation and iron overload may contribute to this aggravated hydrocephalus development in aged animals.

Randomized Control Trial of Postnatal rhIGF-1/rhIGFBP-3 Replacement in Preterm Infants: Post-hoc Analysis of Its Effect on Brain Injury

Background: Postnatal insulin-like growth factor-1 (IGF-1) replacement with recombinant human (rh)IGF-1 and IGF binding protein-3 (rhIGF-1/rhIGFBP-3) is being studied as a potential treatment to reduce comorbidities of prematurity. We have recently reported on a phase II, multicenter, randomized, controlled trial comparing postnatal rhIGF-1/rhIGFBP-3 replacement with standard of care (SOC) in extremely preterm infants (NCT01096784). Maximum severity of retinopathy of prematurity was the primary endpoint of the trial and presence of GMH-IVH/PHI one of the pre-specified secondary endpoints. Infants therefore received serial cranial ultrasound scans (CUS) between birth and term age. In this post-hoc analysis we present a detailed analysis of the CUS data of this trial and evaluate the effect of postnatal rhIGF-1/rhIGFBP-3 replacement on the incidence of different kinds of brain injury in extremely preterm infants. Methods: This report is an exploratory post-hoc analysis of a phase II trial in which infants <28 weeks gestational age were randomly allocated to rhIGF-1/rhIGFBP-3 or SOC. Serial cranial ultrasounds were performed between birth and term-equivalent age. Presence of germinal matrix hemorrhage and intraventricular hemorrhage (GMH-IVH), periventricular hemorrhagic infarction (PHI), post-hemorrhagic ventricular dilatation, and white matter injury (WMI) were scored by two independent masked readers. Results: The analysis included 117 infants; 58 received rhIGF-1/rhIGFBP-3 and 59 received SOC. A trend toward less grade II-III GMH-IVH and PHI was observed in treated infants vs. SOC. A subanalysis of infants without evidence of GMH-IVH at study entry (n = 104) showed reduced progression to GMH-IVH in treated infants (25.0% [13/52] vs. 40.4% [21/52]; not significant). No effects of rhIGF-1/rhIGFBP-3 on WMI were observed. Conclusion: The potential protective effect of rhIGF-1/rhIGFBP-3 on the occurrence of GMH-IVH/PHI appeared most pronounced in infants with no evidence of GMH-IVH at treatment start.

Posthemorrhagic hydrocephalus development after germinal matrix hemorrhage: Established mechanisms and proposed pathways

In addition to being the leading cause of morbidity and mortality in premature infants, germinal matrix hemorrhage (GMH) is also the leading cause of acquired infantile hydrocephalus. The pathophysiology of posthemorrhagic hydrocephalus (PHH) development after GMH is complex and vaguely understood, although evidence suggests fibrosis and gliosis in the periventricular and subarachnoid spaces disrupts normal cerebrospinal fluid (CSF) dynamics. Theories explaining general hydrocephalus etiology have substantially evolved from the original bulk flow theory developed by Dr. Dandy over a century ago. Current clinical and experimental evidence supports a new hydrodynamic theory for hydrocephalus development involving redistribution of vascular pulsations and disruption of Starling forces in the brain microcirculation. In this review, we discuss CSF flow dynamics, history and development of theoretical hydrocephalus pathophysiology, and GMH epidemiology and etiology as it relates to PHH development. We highlight known mechanisms and propose new avenues that will further elucidate GMH pathophysiology, specifically related to hydrocephalus.

Attenuation of White Matter Damage Following Deferoxamine Treatment in Rats After Spinal Cord Injury

BACKGROUND

With little information available on axonal and myelin damage surrounding the contusion, the study of spinal cord injury (SCI) so far has focused on neuronal death. In this study, we investigated the role of iron overload in long-term oligodendroglia death and progressive white matter damage to rats after SCI using the iron chelator, deferoxamine (DFX).

METHODS

Female Sprague-Dawley rats received either a contusion at T10 or sham-surgery. The rats were treated with DFX or vehicle. All rats were evaluated in behavioral assessments and then euthanized at different time points. Spinal cords were analyzed by diaminobenzidine-enhanced Perls' staining, non-heme iron measurements, Western blotting, immunohistochemistry, and transmission electron microscopy.

RESULTS

Iron accumulation after SCI resulted in the upregulation of transferrin receptor and divalent metal transporter 1, which exacerbated the intracellular iron overload. DFX treatment reduced iron overload-induced delayed oligodendrocyte death (e.g., 21 days: 47.12 ± 10.5 vs. 20.02 ± 9.4 x 10³/mm² in the vehicle-treated group, n = 4, P < 0.05). After SCI, the markers of axonal damage and demyelination were increased in white matter in the vehicle-treated group compared with the DFX-treated group (P < 0.05).

CONCLUSIONS

Iron overload plays an important role in progressive white matter damage after SCI. DFX may be an effective treatment for white matter damage after SCI.

New and expanding ventricular hemorrhage predicts poor outcome in acute intracerebral hemorrhage

OBJECTIVE

To describe the relationship between intraventricular hemorrhage (IVH) expansion and long-term outcome and to use this relationship to select and validate clinically relevant thresholds of IVH expansion in 2 separate intracerebral hemorrhage (ICH) populations.

METHODS

We used fractional polynomial analysis to test linear and nonlinear models of 24-hour IVH volume change and clinical outcome with data from the Predicting Hematoma Growth and Outcome in Intracerebral Hemorrhage Using Contrast Bolus CT (PREDICT)-ICH study. The primary outcome was poor clinical outcome (modified Rankin Scale [mRS] score 4-6) at 90 days. We derived dichotomous thresholds from the selected model and calculated diagnostic accuracy measures. We validated all thresholds in an independent single-center ICH cohort (Massachusetts General Hospital).

RESULTS

Of the 256 patients from PREDICT, 127 (49.6%) had an mRS score of 4 to 6. Twenty-four-hour IVH volume change and poor outcome fit a nonlinear relationship, in which minimal increases in IVH were associated with a high probability of an mRS score of 4 to 6. IVH expansion ≥1 mL (n = 53, sensitivity 33%, specificity 92%, adjusted odds ratio [aOR] 2.68, 95% confidence interval [CI] 1.11-6.46) and development of any new IVH (n = 74, sensitivity 43%, specificity 85%, aOR 2.53, 95% CI 1.22-5.26) strongly predicted poor outcome at 90 days. The dichotomous thresholds reproduced well in a validation cohort of 169 patients.

CONCLUSION

IVH expansion as small as 1 mL or any new IVH is strongly predictive of poor outcome. These findings may assist clinicians with bedside prognostication and could be incorporated into definitions of hematoma expansion to inform future ICH treatment trials.

The correlation between accumulation of amyloid beta with enhanced neuroinflammation and cognitive impairment after intraventricular hemorrhage

OBJECTIVE

Intraventricular hemorrhage (IVH) is found in approximately 40% of intracerebral hemorrhages and is associated with increased mortality and poor functional outcome. Cognitive impairment is one of the complications and occurs due to various pathological changes. Amyloid beta (Aβ) accumulation and neuroinflammation, and the Alzheimer disease-like pathology, may contribute to cognitive impairment. Iron, the degradation product of hemoglobin, correlates with Aβ. In this study, the authors investigated the correlation between Aβ accumulation with enhanced neuroinflammation and cognitive impairment in a rat model of IVH.

METHODS

Nine male Sprague-Dawley rats underwent an intraventricular injection of autologous blood. Another 9 rats served as controls. Cognitive function was assessed by the Morris water maze and T-maze rewarded alternation tests. Biomarkers of Aβ accumulation, neuroinflammation, and c-Jun N-terminal kinase (JNK) activation were examined.

RESULTS

Cognitive function was impaired in the autologous blood injection group compared with the control group. In the blood injection group, Aβ accumulation was observed, with a co-located correlation between iron storage protein ferritin and Aβ. Beta-site amyloid precursor protein cleaving enzyme-1 (BACE1) activity was elevated. Microgliosis and astrogliosis were observed in hippocampal CA1, CA2, CA3, and dentate gyrus areas, with elevated proinflammatory cytokines tumor necrosis factor-α and interleukin-1. Protein levels of phosphorylated JNK were increased after blood injection.

CONCLUSIONS

Aβ accumulation and enhanced neuroinflammation have a role in cognitive impairment after IVH. A potential therapeutic method requires further investigation.