Statins Protect the Blood Brain Barrier Acutely after Experimental Intracerebral Hemorrhage

Unveiling the impact of aging on BBB and Alzheimer's disease: Factors and therapeutic implications

Alzheimer's disease (AD) is a highly prevalent neurodegenerative condition that has devastating effects on individuals, often resulting in dementia. AD is primarily defined by the presence of extracellular plaques containing insoluble β-amyloid peptide (Aβ) and neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein (P-tau). In addition, individuals afflicted by these age-related illnesses experience a diminished state of health, which places significant financial strain on their loved ones. Several risk factors play a significant role in the development of AD. These factors include genetics, diet, smoking, certain diseases (such as cerebrovascular diseases, obesity, hypertension, and dyslipidemia), age, and alcohol consumption. Age-related factors are key contributors to the development of vascular-based neurodegenerative diseases such as AD. In general, the process of aging can lead to changes in the immune system's responses and can also initiate inflammation in the brain. The chronic inflammation and the inflammatory mediators found in the brain play a crucial role in the dysfunction of the blood-brain barrier (BBB). Furthermore, maintaining BBB integrity is of utmost importance in preventing a wide range of neurological disorders. Therefore, in this review, we discussed the role of age and its related factors in the breakdown of the blood-brain barrier and the development of AD. We also discussed the importance of different compounds, such as those with anti-aging properties, and other compounds that can help maintain the integrity of the blood-brain barrier in the prevention of AD. This review builds a strong correlation between age-related factors, degradation of the BBB, and its impact on AD.

Treatment of Ischemic Stroke by Atorvastatin-Loaded PEGylated Liposome

There is insufficient evidence on the effect of nanoparticles, particularly liposomes loaded with a statin, on acute ischemic stroke. We investigated the impact of atorvastatin-loaded PEG (polyethylene glycol) conjugated liposomes (LipoStatin) on the outcomes in rats with cerebral ischemia-reperfusion. PEGylated liposome loaded with atorvastatin was developed as a nanoparticle to specifically accumulate in an ischemic region and release the drug to ameliorate the harmful effects of the stroke. LipoStatin was administered to rats with transient middle cerebral artery occlusion through the tail vein immediately after reperfusion (LipoStatin group). LipoStatin efficiently accumulated at the cerebral ischemic injury site of the rat. The LipoStatin group showed a significantly reduced infarct volume (p < 0.01) in brain micro-MR imaging and improved neurological function recovery compared to the control group (p < 0.05). In addition, markedly improved brain metabolism using fluorine-18 fluorodeoxyglucose micro-PET/CT imaging was demonstrated in the LipoStatin group compared with the control group (p < 0.01). Mechanistically, as a result of evaluation through IL-1 beta, TNF-alpha, ICAM-1, and Iba-1 mRNA expression levels at 5 days after cerebral ischemia, LipoStatin showed significant anti-inflammatory effects. Protein expression of occludin, JAM-A, Caveolin-1, and eNOS by western blot at 3 days and fluorescent images at 7 days showed considerable recovery of blood-brain barrier breakdown and endothelial dysfunction. PEGylated LipoStatin can be more effectively delivered to the ischemic brain and may have significant neuroprotective effects. Thus, PEGylated LipoStatin can be further developed as a promising targeted therapy for ischemic stroke and other major vascular diseases.

Relationship between prior statin therapy and radiological features and clinical outcomes of intracerebral hemorrhage

OBJECTIVES

A post-hoc analysis of the ICH Deferoxamine (i-DEF) trial was performed to examine any associations pre-ICH statin use may have with ICH volume, PHE volume, and clinical outcomes.

MATERIALS AND METHODS

Baseline characteristics were assessed. Various ICH and PHE parameters were measured via a quantitative, semi-automated method at baseline and follow-up CT scans 72-96 h later. A multivariable logistic regression model was created, adjusting for the variables that were significantly different on univariable analyses (p < 0.05), to assess any associations between pre-ICH statin use and measures of ICH and PHE, as well as good clinical outcome (mRS ≤2), at 90 and 180 days.

RESULTS

262 of 291 i-DEF participants had complete data available for analysis. 69 (26.3 %) used statins prior to ICH onset. Pre-ICH statin users had higher prevalences of hypertension, diabetes, and prior ischemic stroke; higher concomitant use of antihypertensives and antiplatelets; and higher blood glucose level at baseline. On univariable analyses, pre-ICH statin users had smaller baseline ICH volume and PHE volume on repeat scan, as well as smaller changes in relative PHE (rPHE) volume and edema extension distance (EED) between the baseline and repeat scans. In the multivariable analysis, none of the ICH and PHE measures or good clinical outcome was significantly associated with pre-ICH statin use.

CONCLUSION

Pre-ICH statin use was not associated with measures of ICH or PHE, their growth, or clinical outcomes. These findings do not lend support to either overall protective or deleterious effects from statin use before or after ICH.

Neutrophil extracellular traps in intracerebral hemorrhage: implications for pathogenesis and therapeutic targets

Intracerebral hemorrhage is a common neurological disease, and its pathological mechanism is complex. As the first recruited leukocyte subtype after intracerebral hemorrhage, neutrophils play an important role in tissue damage. In the past, it was considered that neutrophils performed their functions through phagocytosis, chemotaxis, and degranulation. In recent years, studies have found that neutrophils also have the function of secreting extracellular traps. Extracellular traps are fibrous structure composed of chromatin and granular proteins, which plays an important role in innate immunity. Studies have shown a large number of neutrophil extracellular traps in hematoma samples, plasma samples, and drainage samples after intracerebral hemorrhage. In this paper, we summarized the related mechanisms of neutrophil external traps and injury after intracerebral hemorrhage. Neutrophil extracellular traps are involved in the process of brain injury after intracerebral hemorrhage. The application of related inhibitors to inhibit the formation of neutrophil external traps or promote their dissolution can effectively alleviate the pathological damage caused by intracerebral hemorrhage.

Suppressive role of lovastatin in intracerebral hemorrhage through repression of autophagy

Statins possess critical function in the brain. Here, we intended to investigate the role of lovastatin in brain damage after intracerebral hemorrhage (ICH). A collagenase-induced ICH rat model was established followed by lovastatin treatment. Then, the effect of lovastatin on ICH-induced brain damage was explored with cognitive function, learning and memory abilities, and neurological damage of rats analyzed. Besides, brain water content, number of degenerate neurons, Nissl's body, and apoptosis of neurons were detected. Oxidative stress levels, inflammation, and autophagy levels in ICH were measured after treatment of lovastatin. Lovastatin improved the cognitive impairment of rats, enhanced their spatial learning and memory abilities, reduced nervous system damage, lesion area, and brain water content after ICH. Lovastatin was capable of reducing the number of degenerated neurons, the apoptosis level, autophagy level, and increasing the number of Nissl's body. Lovastatin inhibited the oxidative stress response and inflammatory factors in the brain tissue after ICH, and increased the expression of anti-inflammatory factor IL-10. Lovastatin inhibited AMPK/mTOR signaling pathway after ICH. Our study highlighted the suppressive role of lovastatin in ICH-induced brain damage.

Prior statin and short-term outcomes of primary intracerebral hemorrhage: From a large-scale nationwide longitudinal registry

Introduction

The relationship between statins and intracerebral hemorrhage outcomes is unclear.

Aim

We aimed to compare the in‐hospital mortality and evacuation of intracranial hematoma rates in patients with primary intracerebral hemorrhage between prior statin users and nonusers.

Results

The final study population included 66,263 patients. Multivariable logistics analyses showed that prior statin use was not associated with in‐hospital mortality for primary intracerebral hemorrhage (adjusted odd ratio 0.78, 95% CI 0.61–1.01), but reduced the proportion of patients undergoing evacuation of intracranial hematoma (adjusted odd ratio 0.70, 95% CI 0.61–0.82). Propensity score matching analyses yielded similar results.

Conclusion

Prior statin use was not associated with in‐hospital mortality but did reduce evacuation of intracranial hematoma rates.

Beyond Lipid-Lowering: Effects of Statins on Cardiovascular and Cerebrovascular Diseases and Cancer

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, also known as statins, are administered as first-line therapy for hypercholesterolemia, both as primary and secondary prevention. Besides the lipid-lowering effect, statins have been suggested to inhibit the development of cardiovascular disease through anti-inflammatory, antioxidant, vascular endothelial function-improving, plaque-stabilizing, and platelet aggregation-inhibiting effects. The preventive effect of statins on atherothrombotic stroke has been well established, but statins can influence other cerebrovascular diseases. This suggests that statins have many neuroprotective effects in addition to lowering cholesterol. Furthermore, research suggests that statins cause pro-apoptotic, growth-inhibitory, and pro-differentiation effects in various malignancies. Preclinical and clinical evidence suggests that statins inhibit tumor growth and induce apoptosis in specific cancer cell types. The pleiotropic effects of statins on cardiovascular and cerebrovascular diseases have been well established; however, the effects of statins on cancer patients have not been fully elucidated and are still controversial. This review discusses the recent evidence on the effects of statins on cardiovascular and cerebrovascular diseases and cancer. Additionally, this study describes the pharmacological action of statins, focusing on the aspect of ‘beyond lipid-lowering’.

A functional cerebral endothelium is necessary to protect against cognitive decline

A vascular insult occurring early in disease onset may initiate cognitive decline leading to dementia, while pharmacological and lifestyle interventions can prevent this progression. Mice with a selective, tamoxifen-inducible deletion of NF-κB essential modulator (Nemo) in brain endothelial cells were studied as a model of vascular cognitive impairment. Groups included NemoFl controls and three NemobeKO groups: One untreated, and two treated with simvastatin or exercise. Social preference and nesting were impaired in NemobeKO mice and were not countered by treatments. Cerebrovascular function was compromised in NemobeKO groups regardless of treatment, with decreased changes in sensory-evoked cerebral blood flow and total hemoglobin levels, and impaired endothelium-dependent vasodilation. NemobeKO mice had increased string vessel pathology, blood-brain barrier disruption, neuroinflammation, and reduced cortical somatostatin-containing interneurons. These alterations were reversed when endothelial function was recovered. Findings strongly suggest that damage to the cerebral endothelium can trigger pathologies associated with dementia and its functional integrity should be an effective target in future therapeutic efforts.

MicroRNAs hsa-miR-618 and hsa-miR-297 Might Modulate the Pleiotropic Effects Exerted by Statins in Endothelial Cells Through the Inhibition of ROCK2 Kinase: in-silico Approach

Several studies show that statin therapy improves endothelial function by cholesterol-independent mechanisms called “pleiotropic effects.” These are due to the inhibition of the RhoA/ROCK kinase pathway, its inhibition being an attractive atheroprotective treatment. In addition, recent work has shown that microRNAs, posttranscriptional regulators of gene expression, can affect the response of statins and their efficacy. For this reason, the objective of this study was to identify by bioinformatic analysis possible new microRNAs that could modulate the pleiotropic effects exerted by statins through the inhibition of ROCK kinases. A bioinformatic study was performed in which the differential expression of miRNAs in endothelial cells was compared under two conditions: Control and treated with simvastatin at 10 μM for 24 h, using a microarray. Seven miRNAs were differentially expressed, three up and four down. Within the up group, the miRNAs hsa-miR-618 and hsa-miR-297 present as a predicted target to ROCK2 kinase. Also, functional and enriched pathway analysis showed an association with mechanisms associated with atheroprotective effects. This work shows an in-silico approach of how posttranscriptional regulation mediated by miRNAs could modulate the pleiotropic effects exerted by statins on endothelial cells, through the inhibition of ROCK2 kinase and its effects.

Neuroprotective Therapies for Spontaneous Intracerebral Hemorrhage

Patients who survive the initial ictus of spontaneous intracerebral hemorrhage (ICH) remain vulnerable to subsequent injury of the perilesional parenchyma by molecular and cellular responses to the hematoma. Secondary brain injury after ICH, which contributes to long-term functional impairment and mortality, has emerged as an attractive therapeutic target. This review summarizes preclinical and clinical evidence for neuroprotective therapies targeting secondary injury pathways following ICH. A focus on therapies with pleiotropic antiinflammatory effects that target thrombin-mediated chemotaxis and inflammatory cell migration has led to studies investigating statins, anticholinergics, sphingosine-1-phosphate receptor modulators, peroxisome proliferator activated receptor gamma agonists, and magnesium. Attempts to modulate ICH-induced blood-brain barrier breakdown and perihematomal edema formation has prompted studies of nonsteroidal antiinflammatory agents, matrix metalloproteinase inhibitors, and complement inhibitors. Iron chelators, such as deferoxamine and albumin, have been used to reduce the free radical injury that ensues from erythrocyte lysis. Stem cell transplantation has been assessed for its potential to enhance subacute neurogenesis and functional recovery. Despite promising preclinical results of numerous agents, their outcomes have not yet translated into positive clinical trials in patients with ICH. Further studies are necessary to improve our understanding of the molecular events that promote damage and inflammation of the perihematomal parenchyma after ICH. Elucidating the temporal and pathophysiologic features of this secondary brain injury could enhance the clinical efficacy of neuroprotective therapies for ICH.

Statins for neuroprotection in spontaneous intracerebral hemorrhage

Statins, a common drug class for treatment of dyslipidemia, may be neuroprotective for spontaneous intracerebral hemorrhage (ICH) by targeting secondary brain injury pathways in the surrounding brain parenchyma. Statin-mediated neuroprotection may stem from downregulation of mevalonate and its derivatives, targeting key cell signaling pathways that control proliferation, adhesion, migration, cytokine production, and reactive oxygen species generation. Preclinical studies have consistently demonstrated the neuroprotective and recovery enhancement effects of statins, including improved neurologic function, reduced cerebral edema, increased angiogenesis and neurogenesis, accelerated hematoma clearance, and decreased inflammatory cell infiltration. Retrospective clinical studies have reported reduced perihematomal edema, lower mortality rates, and improved functional outcomes in patients who were taking statins before ICH. Several clinical studies have also observed lower mortality rates and improved functional outcomes in patients who were continued or initiated on statins after ICH. Subgroup analysis of a previous randomized trial has raised concerns of a potentially elevated risk of recurrent ICH in patients with previous hemorrhagic stroke who are administered statins. However, most statin trials failed to show an association between statin use and increased hemorrhagic stroke risk. Variable statin dosing, statin use in the pre-ICH setting, and selection biases have limited rigorous investigation of the effects of statins on post-ICH outcomes. Future prospective trials are needed to investigate the association between statin use and outcomes in ICH.

Simvastatin Reduces Neutrophils Infiltration Into Brain Parenchyma After Intracerebral Hemorrhage via Regulating Peripheral Neutrophils Apoptosis

Statins, known for their lipid-lowering effects, also have immunomodulatory properties. This study aims to examine whether systematic simvastatin administration could decrease polymorphonuclear neutrophils (PMNs) infiltration into brain tissue, as well as alleviate neuroinflammation in a rat model of intracerebral hemorrhage (ICH). The ICH model was induced in adult male Sprague-Dawley rats by an injection of autologous blood. Animals randomly received simvastatin (i.p. 2 mg/kg) or vehicle daily from 5 days before ICH until sacrificed. Routine blood counts, brain water content, neurological scoring, immunofluorescence and RT-PCR were conducted to evaluate the anti-inflammatory effect of simvastatin following ICH. Furthermore, flow cytometric and western blotting analysis were implemented for elucidating the mechanisms involved in simvastatin-induced reduction of neutrophil brain-invading. Elevated PMNs count and neutrophil-to-lymphocyte ratio in circulation were detected in rat model of ICH, which was reversed by using simvastatin. Simvastatin effectively alleviated PMNs infiltration and proinflammatory factors release in perihematomal area, as well as attenuated ICH-induced brain edema and neurological deficits. Simvastatin significantly downregulated the expression of antiapoptotic protein-Mcl-1 while increased the level of proapoptotic protein-Bax and cleaved caspase 3 in PMNs. Simvastatin treatment significantly alleviated PMNs brain-infiltrating and subsequent neuroinflammatory reaction after ICH, in part by accelerating peripheral PMNs apoptosis through disorganized the expression of apoptotic related proteins. Our data provided new evidence for simvastatin application on patients with ICH.

Discontinuing or continuing statin following intracerebral hemorrhage from the view of a national cohort study

BACKGROUND AND AIMS

Statins improve clinical outcomes in patients with ischemic stroke but there is no evidence of the effect of continuing long-term statin therapy in patients with intracerebral hemorrhage (ICH). The aim of this study was to evaluate the impact of continuing statin after ICH.

METHODS

Data on patients with ICH was retrieved from the National Health Insurance Research Database of Taiwan. The final population was separated into two groups according to those who continued and those who discontinued statin treatment. All-cause mortality and cardiovascular outcomes were analyzed after a 3 year follow-up after propensity score matching (PSM).

RESULTS

Of the 114,101 patients with ICH, who were initially enrolled, 2468 patients with dyslipidemia and ICH were included. After PSM, the benefit of statin therapy on mortality appeared from 1 year to the end of the 3-year follow-up period after discharge (statin group versus non-statin group: 4.9% vs.12.3% at 1 year (hazard ratio [HR], 0.38; 95% confidence interval [CI], 0.26-0.57) and 12.9% vs. 25.3% at the end of the 3 year follow-up period (HR, 0.45; 95% CI, 0.35-0.58). Compared with the patients using lipophilic statins, those using hydrophilic statins had a significantly lower incidence of all-cause mortality (HR = 0.65, 95% CI = 0.43-0.99). There were no differences between those prescribed moderate-intensity statins and those prescribed high-intensity statins in terms of stroke and all-cause mortality (HR = 0.76; 95% CI = 0.40-1.46).

CONCLUSIONS

There was a lower risk of all-cause mortality following ICH in patients who continued statin treatment compared with those without statin treatment, especially in those treated with hydrophilic statins.

Genetic, Transcriptome, Proteomic, and Epidemiological Evidence for Blood-Brain Barrier Disruption and Polymicrobial Brain Invasion as Determinant Factors in Alzheimer's Disease

Diverse pathogens are detected in Alzheimer's disease (AD) brains. A bioinformatics survey showed that AD genome-wide association study (GWAS) genes (localized in bone marrow, immune locations and microglia) relate to multiple host/pathogen interactomes (Candida albicans, Cryptococcus neoformans, Bornavirus, Borrelia burgdorferri, cytomegalovirus, Ebola virus, HSV-1, HERV-W, HIV-1, Epstein-Barr, hepatitis C, influenza, Chlamydia pneumoniae, Porphyrymonas gingivalis, Helicobacter pylori, Toxoplasma gondii, Trypanosoma cruzi). These interactomes also relate to the AD hippocampal transcriptome and to plaque or tangle proteins. Upregulated AD hippocampal genes match those upregulated by multiple bacteria, viruses, fungi, or protozoa in immunocompetent cells. AD genes are enriched in GWAS datasets reflecting pathogen diversity, suggesting selection for pathogen resistance, as supported by the old age of AD patients, implying resistance to earlier infections. APOE4 is concentrated in regions of high parasitic burden and protects against childhood tropical infections and hepatitis C. Immune/inflammatory gain of function applies to APOE4, CR1, and TREM2 variants. AD genes are also expressed in the blood-brain barrier (BBB), which is disrupted by AD risk factors (age, alcohol, aluminum, concussion, cerebral hypoperfusion, diabetes, homocysteine, hypercholesterolemia, hypertension, obesity, pesticides, pollution, physical inactivity, sleep disruption, smoking) and by pathogens, directly or via olfactory routes to basal-forebrain BBB control centers. The BBB benefits from statins, NSAIDs, estrogen, melatonin, memantine, and the Mediterranean diet. Polymicrobial involvement is supported by upregulation of bacterial, viral, and fungal sensors/defenders in the AD brain, blood, or cerebrospinal fluid. AD serum amyloid-β autoantibodies may attenuate its antimicrobial effects favoring microbial survival and cerebral invasion leading to activation of neurodestructive immune/inflammatory processes, which may also be augmented by age-related immunosenescence. AD may thus respond to antibiotic, antifungal, or antiviral therapy.

Use of Statins and Outcomes in Intracerebral Hemorrhage Patients

BACKGROUND AND PURPOSE

Statin use may be associated with improved outcome in intracerebral hemorrhage patients. However, the topic remains controversial. Our analysis examined the effect of prior, continued, or new statin use on intracerebral hemorrhage outcomes using the ERICH (Ethnic/Racial Variations of Intracerebral Hemorrhage) data set.

METHODS

We analyzed ERICH (a multicenter study designed to examine ethnic variations in the risk, presentation, and outcomes of intracerebral hemorrhage) to explore the association of statin use and hematoma growth, mortality, and 3-month disability. We computed subset analyses with respect to 3 statin categories (prior, continued, or new use).

RESULTS

Two thousand four hundred and fifty-seven enrolled cases (mean age, 62 years; 42% females) had complete data on mortality and 3-month disability (modified Rankin Scale). Among those, 1093 cases were on statins (prior, n=268; continued, n=423; new, n=402). Overall, statin use was associated with reduced mortality and disability without any effect on hematoma growth. This association was primarily driven by continued/new statin use. A multivariate analysis adjusted for age and major predictors for poor outcome showed that continued/new statins users had good outcomes compared with prior users. However, statins may have been continued/started more frequently among less severe patients. When a propensity score was developed based on factors that could influence a physician's decision in prescribing statins and used as a covariate, continued/new statin use was no longer a significant predictor of good outcome.

CONCLUSIONS

Although statin use, especially continued/new use, was associated with improved intracerebral hemorrhage outcomes, this effect may merely reflect the physician's view of a patient's prognosis rather than a predictor of survival.

Simvastatin Promotes Hematoma Absorption and Reduces Hydrocephalus Following Intraventricular Hemorrhage in Part by Upregulating CD36

We previously found that hematoma worsens hydrocephalus after intraventricular hemorrhage (IVH) via increasing iron deposition and aggravating ependymal cilia injury; therefore, promoting hematoma absorption may be a promising strategy for IVH. Recently, some investigations imply that simvastatin has the ability of accelerating hematoma absorption. Thus, this study was designed to examine the efficacy of simvastatin for IVH in rats. Intracerebral hemorrhage with ventricular extension was induced in adult male Sprague-Dawley rats after autologous blood injection. Simvastatin or vehicle was administered orally at 1 day after IVH and then daily for 1 week. MRI studies were performed to measure the volumes of intracranial hematoma and lateral ventricle at days 1, 3, 7, 14, and 28 after IVH. Motor and neurocognitive functions were assessed at days 1 to 7 and 23 to 28, respectively. Iron deposition, iron-related protein expression, ependymal damage, and histology were detected at day 28. Expression of CD36 scavenger receptor (facilitating phagocytosis) was examined at day 3 after IVH using western blotting and immunofluorescence. Simvastatin significantly increased hematoma absorption ratio, reduced ventricular volume, and attenuated neurological dysfunction post-IVH. In addition, less iron accumulation and more cilia survival was observed in the simvastatin group when compared with the control. What's more, higher expression of CD36 was detected around the hematoma after simvastatin administration. Simvastatin significantly enhanced brain hematoma absorption, alleviated hydrocephalus, and improved neurological recovery after experimental IVH, which may in part by upregulating CD36 expression. Our data suggest that early simvastatin use may be a novel therapy for IVH patients.

Multimodality MRI assessment of grey and white matter injury and blood-brain barrier disruption after intracerebral haemorrhage in mice

In this study, we examined injury progression after intracerebral haemorrhage (ICH) induced by collagenase in mice using a preclinical 11.7 Tesla MRI system. On T2-weighted MRI, lesion and striatal volumes were increased on day 3 and then decreased from days 7 to 28. On day 3, with an increase in striatal water content, vasogenic oedema in the perihaematomal region presented as increased T2 and increased apparent diffusion coefficient (ADC) signal. With a synchronous change in T2 and ADC signals, microglial activation peaked on day 3 in the same region and decreased over time. Iron deposition appeared on day 3 around the haematoma border but did not change synchronously with ADC signals. Vascular permeability measured by Evans blue extravasation on days 1, 3, and 7 correlated with the T1-gadolinium results, both of which peaked on day 3. On diffusion tensor imaging, white matter injury was prominent in the corpus callosum and internal capsule on day 3 and then partially recovered over time. Our results indicate that the evolution of grey/white matter injury and blood-brain barrier disruption after ICH can be assessed with multimodal MRI, and that perihaematomal vasogenic oedema might be attributable to microglial activation, iron deposition, and blood-brain barrier breakdown.

Intracerebral Hemorrhage: Perihemorrhagic Edema and Secondary Hematoma Expansion: From Bench Work to Ongoing Controversies

Intracerebral hemorrhage (ICH) is a medical emergency, which often leads to severe disability and death. ICH-related poor outcomes are due to primary injury causing structural damage and mass effect and secondary injury in the perihemorrhagic region over several days to weeks. Secondary injury after ICH can be due to hematoma expansion (HE) or a consequence of repair pathway along the continuum of neuroinflammation, neuronal death, and perihemorrhagic edema (PHE). This review article is focused on PHE and HE and will cover the animal studies, related human studies, and clinical trials relating to these mechanisms of secondary brain injury in ICH patients.

Statin use after intracerebral hemorrhage: a 10-year nationwide cohort study

INTRODUCTION

Although statin therapy is beneficial to patients with ischemic stroke, statin use, and intracerebral hemorrhage (ICH) remain a concern. ICH survivors commonly have comorbid cardiovascular risk factors that would otherwise warrant cholesterol-lowering medication, thus emphasizing the importance of assessing the characteristics of statin therapy in this population.

METHODS

We performed a cohort study by using 10 years of data collected from the National Health Insurance Research Database in Taiwan. We enrolled 726 patients admitted for newly diagnosed ICH from January 1, 2001 to December 31, 2010. The patients were categorized into high- (92), moderate- (545), and low-intensity (89) statin groups, and into hydrophilic (295) and lipophilic (431) statin groups. The composite outcomes included all-cause mortality, recurrent ICH, ischemic stroke, transient ischemic attack, and acute coronary events.

RESULTS

The patients in the low-intensity group did not differ significantly from the patients in the high-intensity group in risk of all-cause mortality (adjusted hazard ratio [aHR] = 0.65, 95% confidence interval [CI] = 0.28-1.55) and recurrent ICH (aHR = 0.66, 95% CI = 0.30-1.44). In contrast, the patients in the hydrophilic group had a significantly lower risk of recurrent ICH than did those in the lipophilic group (aHR = 0.69, 95% CI = 0.48-0.99). We determined no significant differences in other composite endpoints between hydrophilic and lipophilic statin use.

CONCLUSION

Hydrophilic statin therapy is associated with a reduced risk of recurrent ICH in post-ICH patients. The intensity of statin use had no significant effect on recurrent ICH or other components of the composite outcome. Additional studies are required to clarify the biological mechanisms underlying these observations.

A Prospective Safety Trial of Atorvastatin Treatment to Assess Rebleeding after Spontaneous Intracerebral Hemorrhage: A Serial MRI Investigation

AIM

This study was designed to determine any rebleeding after atorvastatin treatment following spontaneous intracerebral hemorrhage (ICH) in a prospective safety trial.

PATIENTS

Atorvastatin (80 mg/day) therapy was initiated in 6 patients with primary ICH with admission Glasgow Coma Score (GCS) >5 within 24 hours of ictus and continued for 7 days, with the dose tapered and treatment terminated over the next 5 days. Patients were studied longitudinally by multiparametric magnetic resonance imaging (MRI) at three time points: acute (3 to 5 days), subacute (4 to 6 weeks) and chronic (3 to 4 months). Imaging sequences included T₁, T₂-weighted imaging (T₂WI), diffusion tensor imaging (DTI) and contrast-enhanced MRI measures of cerebral perfusion, blood volume and blood-brain barrier (BBB) permeability. Susceptibility weighted imaging (SWI) was used to identify primary ICH and to check for secondary rebleeding. Final outcome was assessed using Glasgow Outcome Score (GOS) at 3-4 months.

RESULTS

Mean admission GCS was 13.2±4.0 and mean GOS at 3 months was 4.5±0.6. Hemorrhagic lesions were segmented into core and rim areas. Mean lesion volumes decreased significantly between the acute and chronic study time points (p=0.008). Average ipsilateral hemispheric tissue loss at 3 to 4 months was 11.4±4.6 cm³. MRI showed acutely reduced CBF (p=0.004) and CBV (p=0.002) in the rim, followed by steady normalization. Apparent diffusion coefficient of water (ADC) in the rim demonstrated no alterations at any of the time points (p>0.2). The T₂ values were significantly elevated in the rim acutely (p=0.02), but later returned to baseline. The ICH core showed sustained low CBF and CBV values concurrent with a small reduction in ADC acutely, but significant ADC elevation at the end suggestive of irreversible injury.

CONCLUSION

Despite the presence of a small, probably permanent, cerebral lesion in the ICH core, no patients exhibited post-treatment rebleeding. These data suggest that larger, Phase 2 trials are warranted to establish long term clinical safety of atorvastatin in spontaneous ICH.

Statins Inhibit Fibrillary β-Amyloid Induced Inflammation in a Model of the Human Blood Brain Barrier

Background

Astrocytes and cerebral endothelial cells are important components of the blood-brain barrier (BBB). Disruption to this barrier through inflammation is a major contributor to Alzheimer’s disease (AD) pathology. The amyloid beta (Aβ) protein is known to exist in several forms and is a key modulator of AD that is known to cause inflammation and changes to BBB function. While one of these forms, fibrillary Aβ (fAβ), is known to cause endothelial cell death at the BBB, no studies have looked specifically at its role on inflammation in a model of the human BBB.

Aims

To determine if fAβ is inflammatory to the human BBB. As statins have been shown to be anti-inflammatory and protective in AD, we also tested if these could inhibit the inflammatory effect of fAβ.

Methods

Using cultured cerebral endothelial cells and astrocytes we determined changes in cytokine release, cell toxicity and barrier function in response to fibrillary β-amyloid_1–42 (fAβ_1–42) alone and in combination with statins.

Results

fAβ_1–42 induced inflammatory cytokine release from endothelial cells in the absence of cell toxicity. It also induced astrocyte cytokine release and cell death and caused a loss of barrier integrity. Statin treatment inhibited all of these effects.

Conclusions

We conclude that fAβ_1–42 has both inflammatory and cytotoxic effects on the BBB and the protective effect of statins in AD may in part be through inhibiting these effects.

Stages of the Inflammatory Response in Pathology and Tissue Repair after Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a major health concern, with high rates of mortality and morbidity and no highly effective clinical interventions. Basic research in animal models of ICH has provided insight into its complex pathology, in particular revealing the role of inflammation in driving neuronal death and neurologic deficits after hemorrhage. The response to ICH occurs in four distinct phases: (1) initial tissue damage and local activation of inflammatory factors, (2) inflammation-driven breakdown of the blood-brain barrier, (3) recruitment of circulating inflammatory cells and subsequent secondary immunopathology, and (4) engagement of tissue repair responses that promote tissue repair and restoration of neurologic function. The development of CNS inflammation occurs over many days after initial hemorrhage and thus may represent an ideal target for treatment of the disease, but further research is required to identify the mechanisms that promote engagement of inflammatory versus anti-inflammatory pathways. In this review, the authors examine how experimental models of ICH have uncovered critical mediators of pathology in each of the four stages of the inflammatory response, and focus on the role of the immune system in these processes.

Statins in Intracerebral Hemorrhage

While statins play an indisputable role in primary and secondary prevention of ischemic cardiovascular and cerebrovascular disease, a concern exists regarding a possible association between low lipoprotein levels and statin use on the risk of intracerebral hemorrhage (ICH). While these data may incline physicians to discontinue statins after ICH, an increasing amount of preclinical and clinical evidence suggests that statins might have a beneficial effect on outcome and recovery in this context that goes beyond lipid lowering effects. Different etiologies of ICH and the related risk of recurrence should also be taken into account when deciding about statin use/avoidance in patients with high risk of ICH. The problem is compounded by paucity of data from randomized controlled trials and well-designed prospective observational studies. This review will discuss the existing evidence on potential interactions between statins and risk of ICH as well as outcomes in order to provide practical recommendations for clinical decision-making.

Blood lipid levels, statin therapy and the risk of intracerebral hemorrhage

Dyslipidemia has been proven to play an important role in the occurrence and development of the ischemic stroke and lipid-lowering therapy could significantly decrease the risk of the ischemic stroke. However, the association between lipid levels, lipid-lowering therapy and the risk of intracerebral hemorrhage (ICH) is not clear. Studies have shown that low serum levels of total cholesterol might be associated with increasing risk of ICH, whereas the SPARCL study, a large prospective, randomized, placebo-controlled trial, demonstrated an increased risk of hemorrhagic stroke during high-dose statin therapy among the patients with previous stroke. The relationship between lipid-lowering therapy and ICH has become a hot topic in the recent years. We searched PubMed for articles published in English to review the existing evidence on the association of lipid levels, statin therapy and risk of ICH as well as the underlying mechanisms in order to provide practical recommendations for clinical decision-making and a foundation for further researches.

Meta-analysis of Statin Use for the Acute Therapy of Spontaneous Intracerebral Hemorrhage

BACKGROUND

Growing evidence demonstrates the neuroprotective effects of statins, and the risk to develop an intracerebral hemorrhage (ICH) using statins has been refuted. However, some controversy remains regarding their role in the acute phase after ICH onset. Therefore, we performed a systematic review to investigate this issue.

METHODS

We searched in MEDLINE, Web of Knowledge, and Scopus databases for studies examining the outcome in patients with spontaneous ICH and statin use. The analysis was performed for short-term (≤3 months) and long-term outcome (≥6 months) and a further subanalysis considered studies seeking for the effects of the discontinuation of statin after ICH onset. A random-effect model was applied, and country was used as a cofactor for meta-regression; odds ratios (ORs) with 95% confidence intervals (CIs) are offered.

RESULTS

A total of 17 studies were included, only 1 pseudo cohort trial assessed the new use of statin after ICH onset and 3 studies evaluated the suspension of statin after ICH onset, the rest of the studies focused on the effect of the regular use of statin before ICH onset. The number of patients with an ICH exposed and not exposed to statins were 3455 and 11,821, respectively. The absolute short-term mortality was 27.3% in statin users and 33% in nonusers that represented a significant risk reduction of mortality (OR, .73; 95% CI, .54-.97). For long-term mortality, the effect was less evident (OR, .71; 95% CI, .43-1.15). The analysis of the 3 studies assessing the discontinuation of statins suggested a reduction of mortality risk by continuing statin (OR, .14; 95% CI, .1-.20).

CONCLUSIONS

The current evidence suggests that continuing statin after ICH onset might be highly related to improvement of the outcome of patients with ICH. Despite this strong suggestion, randomized controlled trials should be performed to further investigate this association.

Perihematoma cerebral blood flow is unaffected by statin use in acute intracerebral hemorrhage patients

Statin therapy has been associated with improved cerebral blood flow (CBF) and decreased perihematoma edema in animal models of intracerebral hemorrhage (ICH). We aimed to assess the relationship between statin use and cerebral hemodynamics in ICH patients. A post hoc analysis of 73 ICH patients enrolled in the Intracerebral Hemorrhage Acutely Decreasing Arterial Pressure Trial (ICH ADAPT). Patients presenting <24 hours from ICH onset were randomized to a systolic blood pressure target <150 or <180 mm Hg with computed tomography perfusion imaging 2 hours after randomization. Cerebral blood flow maps were calculated. Hematoma and edema volumes were measured planimetrically. Regression models were used to assess the relationship between statin use, perihematoma edema and cerebral hemodynamics. Fourteen patients (19%) were taking statins at the time of ICH. Statin-treated patients had similar median (IQR Q25 to 75) hematoma volumes (21.1 (9.5 to 38.3) mL versus 14.5 (5.6 to 27.7) mL, P=0.25), but larger median (IQR Q25 to 75) perihematoma edema volumes (2.9 (1.7 to 9.0) mL versus 2.2 (0.8 to 3.5) mL, P=0.02) compared with nontreated patients. Perihematoma and ipsilateral hemispheric CBF were similar in both groups. A multivariate linear regression model revealed that statin use and hematoma volumes were independent predictors of acute edema volumes. Statin use does not affect CBF in ICH patients. Statin use, along with hematoma volume, are independently associated with increased perihematoma edema volume.

Apolipoprotein E ε-4 as a genetic determinant of Alzheimer's disease heterogeneity

Alzheimer's disease (AD) displays a high degree of heterogeneity in terms of its etiology, presentation, prognosis, and treatment response. This can partly be explained by high-penetrance mutations in the amyloid precursor protein, presenilin 1 and presenilin 2 genes causing amyloid beta aggregation, which is a major pathogenic mechanism in the development of early-onset AD in a small subgroup of patients. Late-onset AD is considered a polygenic disorder in which cumulative risk resulting from interaction with modifiable environmental risk factors may be responsible for the majority of cases. The ε-4 allele of the apolipoprotein E (APOE) gene has emerged as the most significant genetic risk factor for late-onset AD, influencing nearly every pathogenic domain affected in AD. It is a major risk factor for cerebral amyloid angiopathy, recognized as a common pathological finding in an AD subtype associated with white matter dysfunction. The APOE ε-4 allele is also a known risk factor for ischemic stroke, which can result in vascular dementia or contribute to subcortical vascular dysfunction. In this review, we evaluate the clinical relevance of APOE genotyping in relation to cholesterol metabolism and available evidence on risk reduction strategies applicable to AD.

Targeting transporters: promoting blood-brain barrier repair in response to oxidative stress injury

The blood-brain barrier (BBB) is a physical and biochemical barrier that precisely regulates the ability of endogenous and exogenous substances to accumulate within brain tissue. It possesses structural and biochemical features (i.e., tight junction and adherens junction protein complexes, influx and efflux transporters) that work in concert to control solute permeation. Oxidative stress, a critical component of several diseases including cerebral hypoxia/ischemia and peripheral inflammatory pain, can cause considerable injury to the BBB and lead to significant CNS pathology. This suggests a critical need for novel therapeutic approaches that can protect the BBB in diseases with an oxidative stress component. Recent studies have identified molecular targets (i.e., putative membrane transporters, intracellular signaling systems) that can be exploited for optimization of endothelial drug delivery or for control of transport of endogenous substrates such as the antioxidant glutathione (GSH). In particular, targeting transporters offers a unique approach to protect BBB integrity by promoting repair of cell-cell interactions at the level of the brain microvascular endothelium. This review summarizes current knowledge in this area and emphasizes those targets that present considerable opportunity for providing BBB protection and/or promoting BBB repair in the setting of oxidative stress. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Targeting secondary injury in intracerebral haemorrhage--perihaematomal oedema

Perihaematomal oedema (PHO) is an important pathophysiological marker of secondary injury in intracerebral haemorrhage (ICH). In this Review, we describe a novel method to conceptualize PHO formation within the framework of Starling's principle of movement of fluid across a capillary wall. We consider progression of PHO through three stages, characterized by ionic oedema (stage 1) and progressive vasogenic oedema (stages 2 and 3). In this context, possible modifiers of PHO volume and their value in identifying patients who would benefit from therapies that target secondary injury are discussed; the practicalities of using neuroimaging to measure PHO volume are also considered. We examine whether PHO can be used as a predictor of neurological outcome following ICH, and we provide an overview of emerging therapies. Our discussion emphasizes that PHO has clinical relevance both as a therapeutic target, owing to its augmentation of the mass effect of a haemorrhage, and as a surrogate marker for novel interventions that target secondary injury.

The Role of Circulating Tight Junction Proteins in Evaluating Blood Brain Barrier Disruption following Intracranial Hemorrhage

Brain injury after intracranial hemorrhage (ICH) results in significant morbidity and mortality. Blood brain barrier (BBB) disruption is a hallmark of ICH-induced brain injury; however, data mirroring BBB disruption in human ICH are scarce. The aim of this study was to assess the significance of circulating biomarkers in evaluating BBB disruption after ICH. Twenty-two patients with ICH were recruited in this study. Concentrations of the tight junction proteins (TJs) Claudin-5 (CLDN5), Occludin (OCLN), and zonula occludens 1 (ZO-1) and vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were measured by using enzyme-linked immunosorbent assay in serum and cerebrospinal fluid (CSF) samples obtained from patients with ICH. The white blood cell (WBC) count in blood and CSF, albumin (ALB) levels in the CSF (ALBCSF), and the BBB ratio were significantly higher in the ICH than in controls (p < 0.05). Significantly higher levels of CLDN5, OCLN, ZO-1, MMP-9, and VEGF in CSF were observed in the ICH group; these biomarkers were also positively associated with BBB ratio (p < 0.05). Our data revealed that circulating TJs could be considered the potential biomarkers reflecting the integrity of the BBB in ICH.

Intrastriatal injection of autologous blood or clostridial collagenase as murine models of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a common form of cerebrovascular disease and is associated with significant morbidity and mortality. Lack of effective treatment and failure of large clinical trials aimed at hemostasis and clot removal demonstrate the need for further mechanism-driven investigation of ICH. This research may be performed through the framework provided by preclinical models. Two murine models in popular use include intrastriatal (basal ganglia) injection of either autologous whole blood or clostridial collagenase. Since, each model represents distinctly different pathophysiological features related to ICH, use of a particular model may be selected based on what aspect of the disease is to be studied. For example, autologous blood injection most accurately represents the brain's response to the presence of intraparenchymal blood, and may most closely replicate lobar hemorrhage. Clostridial collagenase injection most accurately represents the small vessel rupture and hematoma evolution characteristic of deep hemorrhages. Thus, each model results in different hematoma formation, neuroinflammatory response, cerebral edema development, and neurobehavioral outcomes. Robustness of a purported therapeutic intervention can be best assessed using both models. In this protocol, induction of ICH using both models, immediate post-operative demonstration of injury, and early post-operative care techniques are demonstrated. Both models result in reproducible injuries, hematoma volumes, and neurobehavioral deficits. Because of the heterogeneity of human ICH, multiple preclinical models are needed to thoroughly explore pathophysiologic mechanisms and test potential therapeutic strategies.

Anticoagulant effects of statins and their clinical implications

There is evidence indicating that statins (3-hydroxy-methylglutaryl coenzyme A reductase inhibitors) may produce several cholesterol-independent antithrombotic effects. In this review, we provide an update on the current understanding of the interactions between statins and blood coagulation and their potential relevance to the prevention of venous thromboembolism (VTE). Anticoagulant properties of statins reported in experimental and clinical studies involve decreased tissue factor expression resulting in reduced thrombin generation and attenuation of pro-coagulant reactions catalysed by thrombin, such as fibrinogen cleavage, factor V and factor XIII activation, as well as enhanced endothelial thrombomodulin expression, resulting in increased protein C activation and factor Va inactivation. Observational studies and one randomized trial have shown reduced VTE risk in subjects receiving statins, although their findings still generate much controversy and suggest that the most potent statin rosuvastatin exerts the largest effect.