Blood-Brain Barrier Dysfunction in Small Vessel Disease Related Intracerebral Hemorrhage

Decreased microvascular claudin-5 levels in cerebral amyloid angiopathy associated with intracerebral haemorrhage

Decreased microvascular levels of claudin-5 in the occipital and temporal lobe of patients with cerebral amyloid angiopathy are associated with intracerebral haemorrhage.

Blood-based biomarkers of cerebral small vessel disease

Age-associated cerebral small vessel disease (CSVD) represents a clinically heterogenous condition, arising from diverse microvascular mechanisms. These lead to chronic cerebrovascular dysfunction and carry a substantial risk of subsequent stroke and vascular cognitive impairment in aging populations. Owing to advances in neuroimaging, in vivo visualization of cerebral vasculature abnormities and detection of CSVD, including lacunes, microinfarcts, microbleeds and white matter lesions, is now possible, but remains a resource-, skills- and time-intensive approach. As a result, there has been a recent proliferation of blood-based biomarker studies for CSVD aimed at developing accessible screening tools for early detection and risk stratification. However, a good understanding of the pathophysiological processes underpinning CSVD is needed to identify and assess clinically useful biomarkers. Here, we provide an overview of processes associated with CSVD pathogenesis, including endothelial injury and dysfunction, neuroinflammation, oxidative stress, perivascular neuronal damage as well as cardiovascular dysfunction. Then, we review clinical studies of the key biomolecules involved in the aforementioned processes. Lastly, we outline future trends and directions for CSVD biomarker discovery and clinical validation.

Histopathological characterization of cerebral small vessel disease in epilepsy patients with temporal lobe epilepsy submitted to surgery: A case-control study

BACKGROUND

Cerebrovascular disease (CVD) is a major contributor to epilepsy; however, patients with epilepsy also have a significantly increased risk of stroke. The way in which epilepsy contributes to the increased risk of stroke is still uncertain and is ill-characterized in neuropathological studies. A neuropathological characterization of cerebral small vessel disease (cSVD) in patients with chronic epilepsy was performed.

METHODS

Thirty-three patients with refractory epilepsy and hippocampal sclerosis (HS) submitted to epilepsy surgery from a reference center were selected between 2010 and 2020 and compared with 19 autopsy controls. Five randomly selected arterioles from each patient were analyzed using a previously validated scale for cSVD. The presence of CVD disease imaging markers in pre-surgical brain magnetic resonance imaging (MRI) was studied.

RESULTS

There were no differences in age (43.8 vs. 41.6 years; p = 0.547) or gender distribution (female gender 60.6% vs. male gender 52.6%; p = 0.575) between groups. Most CVD findings in brain MRI were mild. Patients had a mean time between the epilepsy onset and surgery of 26 ± 14.7 years and were medicated with a median number of three antiseizure medication (ASMs) [IQR 2-3]. Patients had higher median scores in arteriolosclerosis (3 vs. 1; p < 0.0001), microhemorrhages (4 vs. 1; p < 0.0001) and total score value (12 vs. 8.9; p = 0.031) in comparison with controls. No correlation was found between age, number of years until surgery, number of ASMs or cumulative defined daily dosage of ASM.

CONCLUSION

The present study provides evidence supporting the increased burden of cSVD in the neuropathological samples of patients with chronic epilepsy.

A Complex Intracerebral Hemorrhage Case Report: Intracerebral Hemorrhage, Intraventricular Hemorrhage, and Hydrocephalus in an Addicted Patient

BACKGROUND

Despite progression, the mortality rate following intracerebral hemorrhage (ICH) is still high; only 25 % of subjects achieve functional independence at three months. The survey presents a complex addicted case report with ICH, intraventricular hemorrhage (IVH), and hydrocephalus co-occurrence.

CASE PRESENTATION

The patient was a 48-year-old man with a history of hypertension and addiction. On admission time, his GCS was 4/15, desperate in response to painful stimulation. There were no traumatic effects on the body. In response to painful stimulation with his right upper limb, he localized the site of pain.

DISCUSSION

According to the function of EVD, it was removed three days after surgical treatment, and the patient was extubated seven days after surgery. On the 13th day after surgery, the patient's GCS increased to 12; the patient was OBEY.

CONCLUSION

In the current survey, we tried to discuss the management of ICH through a complex case and an inferior prognosis. Our data indicated that with proper interpretation and surgical management of ICH, it is possible to save the survival of ICH patients even in complex situations.

Histopathology of Cerebral Microinfarcts and Microbleeds in Spontaneous Intracerebral Hemorrhage

In patients with spontaneous intracerebral hemorrhage caused by different vasculopathies, cerebral microinfarcts have the same aspect on MRI and the same applies to cerebral microbleeds. It is unclear what pathological changes underlie these cerebral microinfarcts and cerebral microbleeds. In the current study, we explored the histopathological substrate of these lesions by investigating the brain tissue of 20 patients (median age at death 77 years) who died from ICH (9 lobar, 11 non-lobar) with a combination of post-mortem 7-T MRI and histopathological analysis. We identified 132 CMIs and 204 CMBs in 15 patients on MRI, with higher numbers of CMIs in lobar ICH patients and similar numbers of CMBs. On histopathology, CMIs and CMBs were in lobar ICH more often located in the superficial than in the deep layers of the cortex, and in non-lobar ICH more often in the deeper layers. We found a tendency towards more severe CAA scores in lobar ICH patients. Other histopathological characteristics were comparable between lobar and non-lobar ICH patients. Although CMIs and CMBs were found in different segments of the cortex in lobar ICH compared to non-lobar ICH patients, otherwise similar histopathological features of cortical CMIs and CMBs distant from the ICH suggest shared pathophysiological mechanisms in lobar and non-lobar ICH caused by different vasculopathies.

Normal cerebrospinal fluid concentrations of PDGFRβ in patients with cerebral amyloid angiopathy and Alzheimer's disease

BACKGROUND

Cerebrospinal fluid (CSF) platelet-derived growth factor receptor-β (PDGFRβ) has been proposed as a biomarker of blood-brain barrier (BBB) breakdown. We studied PDGFRβ levels as a biomarker for cerebral amyloid angiopathy (CAA), amnestic mild cognitive impairment (aMCI), or Alzheimer's disease (AD).

METHODS

CSF PDGFRβ levels were quantified by enzyme-linked immunosorbent assay in patients with CAA, patients with aMCI/AD, and in matched controls. In aMCI/AD we evaluated CSF PDGFRβ both by clinical phenotype and by using the AT(N) biomarker classification system defined by CSF amyloid (A), tau (T), and neurodegeneration (N) biomarkers.

RESULTS

PDGFRβ levels were similar in CAA patients and controls (P = .78) and in aMCI/AD clinical phenotype and controls (P = .91). aMCI/AD patients with an AD+ biomarker profile (A+T+[N+]) had increased PDGFRβ levels compared to (A-T-[N-]) controls (P = .006).

CONCLUSION

Our findings indicate that PDGFRβ levels are associated with an AD+ biomarker profile but are not a suitable biomarker for CAA or aMCI/AD clinical syndrome.

Cerebral small vessel disease and perihematomal edema formation in spontaneous intracerebral hemorrhage

Objective

Blood-brain barrier (BBB) dysfunction is implicated in the pathophysiology of cerebral small vessel disease (cSVD)-related intracerebral hemorrhage (ICH). The formation of perihematomal edema (PHE) is presumed to reflect acute BBB permeability following ICH. We aimed to assess the association between cSVD burden and PHE formation in patients with spontaneous ICH.

Methods

We selected patients with spontaneous ICH who underwent 3T MRI imaging within 21 days after symptom onset from a prospective observational multicenter cohort study. We rated markers of cSVD (white matter hyperintensities, enlarged perivascular spaces, lacunes and cerebral microbleeds) and calculated the composite score as a measure of the total cSVD burden. Perihematomal edema formation was measured using the edema extension distance (EED). We assessed the association between the cSVD burden and the EED using a multivariable linear regression model adjusting for age, (log-transformed) ICH volume, ICH location (lobar vs. non-lobar), and interval between symptom onset and MRI.

Results

We included 85 patients (mean age 63.5 years, 75.3% male). Median interval between symptom onset and MRI imaging was 6 days (IQR 1–19). Median ICH volume was 17.0 mL (IQR 1.4–88.6), and mean EED was 0.54 cm (SD 0.17). We found no association between the total cSVD burden and EED (B = −0.003, 95% CI −0.003–0.03, p = 0.83), nor for any of the individual radiological cSVD markers.

Conclusion

We found no association between the cSVD burden and PHE formation. This implies that mechanisms other than BBB dysfunction are involved in the pathophysiology of PHE.

Common Shared Pathogenic Aspects of Small Vessels in Heart and Brain Disease

Small-vessel disease (SVD), also known as microvascular endothelial dysfunction, is a disorder with negative consequences for various organs such as the heart and brain. Impaired dilatation and constriction of small vessels in the heart lead to reduced blood flow and ischemia independently of coronary artery disease (CAD) and are associated with major cardiac events. SVD is usually a silent form of subcortical vascular burden in the brain with various clinical manifestations, such as silent-lacunar-ischemic events and confluent white-matter hyperintensities. Imaging techniques are the main help for clinicians to diagnose cardiac and brain SVD correctly. Markers of inflammation, such as C-reactive protein, tumor-necrosis-factor α, and interleukin 6, provide insight into the disease and markers that negatively influence nitric-oxide bioavailability and promote oxidative stress. Unfortunately, the therapeutic approach against SVD is still not well-defined. In the last decades, various antioxidants, oxidative stress inhibitors, and superoxide scavengers have been the target of extensive investigations due to their potential therapeutic effect, but with unsatisfactory results. In clinical practice, traditional anti-ischemic and risk-reduction therapies for CAD are currently in use for SVD treatment.

Glycemic control is not related to cerebral small vessel disease in neurologically asymptomatic individuals with type 1 diabetes

AIMS

To determine if medium- and long-term blood glucose control as well as glycemic variability, which are known to be strong predictors of vascular complications, are associated with underlying cerebral small vessel disease (cSVD) in neurologically asymptomatic individuals with type 1 diabetes.

METHODS

A total of 189 individuals (47.1% men; median age 40.0, IQR 33.0-45.2 years) with type 1 diabetes (median diabetes duration of 21.7, IQR 18.3-30.7 years) were enrolled in a cross-sectional retrospective study, as part of the Finnish Diabetic Nephropathy (FinnDiane) Study. Glycated hemoglobin (HbA_1c) values were collected over the course of ten years before the visit including a clinical examination, biochemical sampling, and brain magnetic resonance imaging. Markers of glycemic control, measured during the visit, included HbA_1c, fructosamine, and glycated albumin.

RESULTS

Signs of cSVD were present in 66 (34.9%) individuals. Medium- and long-term glucose control and glycemic variability did not differ in individuals with signs of cSVD compared to those without. Further, no difference in any of the blood glucose variables and cSVD stratified for cerebral microbleeds (CMBs) or white matter hyperintensities were detected. Neither were numbers of CMBs associated with the studied glucose variables. Additionally, after dividing the studied variables into quartiles, no association with cSVD was observed.

CONCLUSIONS

We observed no association between glycemic control and cSVD in neurologically asymptomatic individuals with type 1 diabetes. This finding was unexpected considering the large number of signs of cerebrovascular pathology in these people after two decades of chronic hyperglycemia and warrants further studies searching for underlying factors of cSVD.

LncRNA FGD5-AS1 accelerates intracerebral hemorrhage injury in mice by adsorbing miR-6838-5p to target VEGFA

Intracerebral hemorrhage (ICH) can usually cause severe neuroinflammation and blood-brain barrier (BBB) damage. Previous studies supported the important role of long non-coding RNAs (lncRNAs) in ICH treatment. This study aimed to explore the effect of lncRNA FGD5 antisense RNA 1 (FGD5-AS1) on ICH and its potential molecular mechanisms. C57BL/6 mice were injected with collagenase VII to establish an ICH mice model. In addition, brain cerebral microvascular endothelial cells (BMVECs) were treated by oxygen-glucose deprivation (OGD)/hemin to simulate ICH. RT-qPCR revealed that FGD5-AS1 was upregulated in serum of ICH patients and mice and in OGD/hemin-treated BMVECs. Luciferase reporter gene and pull-down assays predicted and verified that FGD5-AS1 bound to miR-6838-5p, and VEGFA was a target of miR-6838-5p. FGD5-AS1 knockdown decreased the inflammatory factor contents in brain tissues and BMVECs. FGD5-AS1 overexpression inhibited cell proliferation, invasion and tight junction protein levels, and promoted apoptosis, increased the permeability of BBB and secretion of pro-inflammatory factors. In addition, miR-6838-5p knockdown reversed the inhibitory effect of FGD5-AS1 knockdown on the PI3K/Akt signaling pathway. In conclusion, FGD5-AS1 may act as an important regulator to promote apoptosis, cell permeability and inflammatory response of BMVECs via the miR-6838-5p/VEGFA axis in ICH mice.

Dysfunction of the Blood-brain Barrier in Cerebral Microbleeds: from Bedside to Bench

Cerebral microbleeds (CMBs) are a disorder of cerebral microvessels that are characterized as small (<10 mm), hypointense, round or ovoid lesions seen on T2*-weighted gradient echo MRI. There is a high prevalence of CMBs in community-dwelling healthy older people. An increasing number of studies have demonstrated the significance of CMBs in stroke, dementia, Parkinson's disease, gait disturbances and late-life depression. Blood-brain barrier (BBB) dysfunction is considered to be the event that initializes CMBs development. However, the pathogenesis of CMBs has not yet been clearly elucidated. In this review, we introduce the pathogenesis of CMBs, hypertensive vasculopathy and cerebral amyloid angiopathy, and review recent research that has advanced our understanding of the mechanisms underlying BBB dysfunction and CMBs presence. CMBs-associated risk factors can exacerbate BBB breakdown through the vulnerability of BBB anatomical and functional changes. Finally, we discuss potential pharmacological approaches to target the BBB as therapy for CMBs.

Neurovascular Coupling Is Impaired in Hypertensive and Diabetic Subjects Without Symptomatic Cerebrovascular Disease

The mechanistic link between hypertension, diabetes and cerebral small vessel disease (CSVD) is still poorly understood. We hypothesized that hypertension and diabetes could impair cerebrovascular regulation prior to irreversibly established cerebrovascular disease. In this study, 52 hypertensive patients [54% males; age 64 ± 11 years; 58% with comorbid diabetes mellitus (DM)] without symptomatic cerebrovascular disease underwent transcranial Doppler (TCD) monitoring in the middle (MCA) and posterior (PCA) cerebral arteries, to assess vasoreactivity to carbon dioxide (VRCO₂) and neurovascular coupling (NVC). 1.5T magnetic resonance imaging was also performed and white matter hyperintensity volume was automatically segmented from FLAIR sequences. TCD data from 17 healthy controls were obtained for comparison (47% males; age 60 ± 16 years). Hypertensive patients showed significant impairment of NVC in the PCA, with reduced increment in cerebral blood flow velocity during visual stimulation (22.4 ± 9.2 vs. 31.6 ± 5.7, p < 0.001), as well as disturbed NVC time-varying properties, with slower response (lower rate time: 0.00 ± 0.02 vs. 0.03 ± 6.81, p = 0.001), and reduced system oscillation (reduced natural frequency: 0.18 ± 0.08 vs. 0.22 ± 0.06, p < 0.001), when compared to controls. VRCO₂ remained relatively preserved in MCA and PCA. These results were worse in hypertensive diabetic patients, with lower natural frequency (p = 0.043) than non-diabetic patients. White matter disease burden did not predict worse NVC. These findings suggest that hypertensive diabetic patients may have a precocious impairment of NVC, already occurring without symptomatic CSVD. Future research is warranted to evaluate whether NVC assessment could be useful as an early, non-invasive, surrogate marker for CSVD.

Inhibition of Aryl Hydrocarbon Receptor Attenuates Hyperglycemia-Induced Hematoma Expansion in an Intracerebral Hemorrhage Mouse Model

Background

Hyperglycemia is associated with greater hematoma expansion (HE) and worse clinical prognosis after intracerebral hemorrhage (ICH). However, the clinical benefits of intensive glucose normalization remain controversial, and there are no approved therapies for reducing HE. The aryl hydrocarbon receptor (AHR) has been shown to participate in hyperglycemia‐induced blood–brain barrier (BBB) dysfunction and brain injury after stroke. Herein, we investigated the role of AHR in hyperglycemia‐induced HE in a male mouse model of ICH.

Methods and Results

CD1 mice (n=387) were used in this study. Mice were subjected to ICH by collagenase injection. Fifty percent dextrose was injected intraperitoneally 3 hours after ICH. AHR knockout clustered regularly interspaced short palindromic repeat was administered intracerebroventricularly to evaluate the role of AHR after ICH. A selective AHR inhibitor, 6,2′,4′‐trimethoxyflavone, was administered intraperitoneally 2 hours or 6 hours after ICH for outcome study. To evaluate the effect of AHR on HE, 3‐methylcholanthrene, an AHR agonist, was injected intraperitoneally 2 hours after ICH. The results showed hyperglycemic ICH upregulated AHR accompanied by greater HE. AHR inhibition provided neurological benefits by restricting HE and preserving BBB function after hyperglycemic ICH. In vivo knockdown of AHR further limited HE and enhanced the BBB integrity. Hyperglycemia directly activated AHR as a physiological stimulus in vivo. The thrombospondin‐1/transforming growth factor‐β/vascular endothelial growth factor axis partly participated in AHR signaling after ICH, which inhibited the expressions of BBB‐related proteins, ZO‐1 and Claudin‐5.

Conclusions

AHR may serve as a potential therapeutic target to attenuate hyperglycemia‐induced hematoma expansion and to preserve the BBB in patients with ICH.

Iron chelation suppresses secondary bleeding after intracerebral hemorrhage in angiotensin II-infused mice

AIMS

Secondary bleeding and further hematoma expansion (HE) aggravate brain injury after intracerebral hemorrhage (ICH). The majority of HE results from hypertensive ICH. Previous study reported higher iron content in the brains of hypertensive patients. Iron overload exacerbates the risk of hemorrhagic transformation in thromboembolic stroke mice. Whether iron overload during the process of hypertension participates in secondary bleeding of hypertensive ICH remains unclear.

METHODS

Hypertension was induced by continuous infusion of angiotensin II (Ang II) with an osmotic pump into C57BL/6 mice. ICH was simulated by intrastriatal injection of the liquid polymer Onyx-18. Iron chelation and iron overload was achieved by deferoxamine mesylate or iron dextran injection. Secondary bleeding was quantified by measuring the hemoglobin content in the ipsilateral brain hemisphere.

RESULTS

Ang II-induced hypertensive mice showed increased iron accumulation in the brain and expanded secondary hemorrhage after ICH modeling. Moreover, iron chelation suppressed while iron overload aggravated secondary bleeding. Mechanistically, iron exacerbated the loss of contractile cerebral vascular smooth muscle cells (VSMCs), aggravated blood-brain barrier (BBB) leakage in Ang II-induced hypertensive mice, and increased glial and MMP9 accumulation after ICH.

CONCLUSION

Iron overload plays a key role in secondary bleeding after ICH in Ang II-induced hypertensive mice. Iron chelation during the process of Ang II-induced hypertension suppresses secondary bleeding after ICH.

Blood-Brain Barrier Breakdown in Relationship to Alzheimer and Vascular Disease

Objective:

Blood–brain barrier (BBB) breakdown has been suggested to be an early biomarker in human cognitive impairment. However, the relationship between BBB breakdown and brain pathology, most commonly Alzheimer disease (AD) and vascular disease, is still poorly understood. The present study measured human BBB function in mild cognitive impairment (MCI) patients on 2 molecular scales, specifically BBB’s permeability to water and albumin molecules.

Methods:

Fifty-five elderly participants were enrolled, including 33 MCI patients and 22 controls. BBB permeability to water was measured with a new magnetic resonance imaging technique, water extraction with phase contrast arterial spin tagging. BBB permeability to albumin was determined using cerebrospinal fluid (CSF)/serum albumin ratio. Cognitive performance was assessed by domain-specific composite scores. AD pathology (including CSF Aβ and ptau) and vascular risk factors were examined.

Results:

Compared to cognitively normal subjects, BBB in MCI patients manifested an increased permeability to small molecules such as water but was no more permeable to large molecules such as albumin. BBB permeability to water was found to be related to AD markers of CSF Aβ and ptau. On the other hand, BBB permeability to albumin was found to be related to vascular risk factors, especially hypercholesterolemia, but was not related to AD pathology. BBB permeability to small molecules, but not to large molecules, was found to be predictive of cognitive function.

Interpretation:

These findings provide early evidence that BBB breakdown is related to both AD and vascular risks, but their effects can be differentiated by spatial scales. BBB permeability to small molecules has a greater impact on cognitive performance.

Relationship Between Hematoma Expansion Induced by Hypertension and Hyperglycemia and Blood-brain Barrier Disruption in Mice and Its Possible Mechanism: Role of Aquaporin-4 and Connexin43

We aimed to select an optimized hematoma expansion (HE) model and investigate the possible mechanism of blood-brain barrier (BBB) damage in mice. The results showed that HE occurred in the group with hypertension combined with hyperglycemia (HH-HE) from 3 to 72 h after intracerebral hemorrhage; this was accompanied by neurological deficits and hardly influenced the survival rate. The receiver operating characteristic curve suggested the criterion for this model was hematoma volume expansion ≥ 45.0%. Meanwhile, HH-HE aggravated BBB disruption. A protector of the BBB reduced HH-HE, while a BBB disruptor induced a further HH-HE. Aquaporin-4 (AQP4) knock-out led to larger hematoma volume and more severe BBB disruption. Furthermore, hematoma volume and BBB disruption were reduced by multiple connexin43 (Cx43) inhibitors in the wild-type group but not in the AQP4 knock-out group. In conclusion, the optimized HE model is induced by hypertension and hyperglycemia with the criterion of hematoma volume expanding ≥ 45.0%. HH-HE leads to BBB disruption, which is dependent on AQP4 and Cx43.

Fgr contributes to hemorrhage-induced thalamic pain by activating NF-κB/ERK1/2 pathways

Thalamic pain, a type of central poststroke pain, frequently occurs following ischemia/hemorrhage in the thalamus. Current treatment of this disorder is often ineffective, at least in part due to largely unknown mechanisms that underlie thalamic pain genesis. Here, we report that hemorrhage caused by microinjection of type IV collagenase or autologous whole blood into unilateral ventral posterior lateral nucleus and ventral posterior medial nucleus of the thalamus increased the expression of Fgr, a member of the Src family nonreceptor tyrosine kinases, at both mRNA and protein levels in thalamic microglia. Pharmacological inhibition or genetic knockdown of thalamic Fgr attenuated the hemorrhage-induced thalamic injury on the ipsilateral side and the development and maintenance of mechanical, heat, and cold pain hypersensitivities on the contralateral side. Mechanistically, the increased Fgr participated in hemorrhage-induced microglial activation and subsequent production of TNF-α likely through activation of both NF-κB and ERK1/2 pathways in thalamic microglia. Our findings suggest that Fgr is a key player in thalamic pain and a potential target for the therapeutic management of this disorder.

CSF enhancement on post-contrast fluid-attenuated inversion recovery images; a systematic review

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CSF enhancement on post-contrast FLAIR images is a novel marker for BBB leakage.

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This neuroradiological marker is frequently observed in neurological diseases.

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Post-contrast FLAIR CSF enhancement is associated with higher age and brain atrophy.

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There is large methodological heterogeneity between studies that use this technique.

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We provide recommendations for future methodological standardization.

Cerebrospinal fluid (CSF) enhancement on T2-weighted post-contrast fluid-attenuated inversion recovery (pcT2wFLAIR) images is a relatively unknown neuroradiological marker for gadolinium-based contrast agent extravasation due to blood–brain barrier (BBB) disruption. We systematically reviewed human studies reporting on CSF enhancement on pcT2wFLAIR images to provide a comprehensive overview of prevalence of this new biomarker in healthy and diseased populations as well as its etiology and optimal detection methodology. We extracted information on the prevalence of CSF enhancement, its vascular risk factor and neuroimaging correlates, and methodological attributes of each study. Forty-four eligible studies were identified. By pooling data, we found that the prevalence of CSF enhancement was 82% (95% confidence interval (CI) 80–89) in meningitis (4 studies, 65 patients), 73% (95%CI 62–81) in cases with (post-) acute intracerebral hemorrhage (2 studies, 77 cases), 64% (95% CI 54–73) in cases who underwent surgery for aneurysm treatment (2 studies, 99 patients), 40% (95% CI 30–51) in cases who underwent surgery for carotid artery disease treatment (3 studies, 76 patients), 27% (95% CI 25–30) in cases with acute ischemic stroke (9 studies, 1148 patients), 21% (95% CI 17–23) in multiple sclerosis (6 studies, 897 patients), and 13% (95% CI 7–21) in adult controls (4 studies, 112 cases). Presence of CSF enhancement was associated with higher age in eleven studies, with lobar cerebral microbleeds in one study, and with cerebral atrophy in four studies. PcT2wFLAIR imaging represents a promising method that can provide novel perspectives on BBB leakage into CSF compartments, with the potential to reveal important new insights into the pathophysiological mechanisms of varying neurological diseases.

CAR-T Cell Therapy-Related Neurotoxicity in Pediatric Acute Lymphoblastic Leukemia: Spectrum of Imaging Findings

The emergence of CD19-targeted chimeric antigen receptor-T (CAR-T) cell therapy has created a new era in the management of pediatric patients with refractory B-cell malignancies such as B-cell acute lymphoblastic leukemia. Immune effector cell-associated neurotoxicity syndrome (ICANS) is frequently encountered in the postinfusion period of CD19-targeted chimeric antigen receptor-T cell therapy and in some cases may be fatal. Knowledge related to the spectrum of imaging findings of CD19-targeted CAR-T cell therapy-related ICANS is, however, still very much lacking, underscoring the need for continued research in this area. In this review, we hope to provide an overview of current knowledge and provide an in-depth literature review related to this topic. A brief discussion of possible imaging differential diagnoses, specifically in children with acute lymphoblastic leukemia, will also be included. Illustrative cases for each imaging phenotype will be provided to facilitate a better understanding. A greater level of insight of the spectrum of imaging findings related to ICANS will improve patients' management and enhance efforts to safely deliver CAR-T cell immunotherapy. It will also facilitate further studies to derive mechanistic insights of ICANS and potentially assist in the testing and monitoring of therapeutic interventions.

The brains of aged mice are characterized by altered tissue diffusion properties and cerebral microbleeds

Background

Brain aging is a major risk factor in the progression of cognitive diseases including Alzheimer’s disease (AD) and vascular dementia. We investigated a mouse model of brain aging up to 24 months old (mo).

Methods

A high field (11.7T) MRI protocol was developed to characterize specific features of brain aging including the presence of cerebral microbleeds (CMBs), morphology of grey and white matter, and tissue diffusion properties. Mice were selected from age categories of either young (3 mo), middle-aged (18 mo), or old (24 mo) and fed normal chow over the duration of the study. Mice were imaged in vivo with multimodal MRI, including conventional T2-weighted (T2W) and T2*-weighted (T2*W) imaging, followed by ex vivo diffusion-weighted imaging (DWI) and T2*W MR-microscopy to enhance the detection of microstructural features.

Results

Structural changes observed in the mouse brain with aging included reduced cortical grey matter volume and enlargement of the brain ventricles. A remarkable age-related change in the brains was the development of CMBs found starting at 18 mo and increasing in total volume at 24 mo, primarily in the thalamus. CMBs presence was confirmed with high resolution ex vivo MRI and histology. DWI detected further brain tissue changes in the aged mice including reduced fractional anisotropy, increased radial diffusion, increased mean diffusion, and changes in the white matter fibers visualized by color-coded tractography, including around a large cortical CMB.

Conclusions

The mouse is a valuable model of age-related vascular contributions to cognitive impairment and dementia (VCID). In composite, these methods and results reveal brain aging in older mice as a multifactorial process including CMBs and tissue diffusion alterations that can be well characterized by high field MRI.

Disturbed balance in the expression of MMP9 and TIMP3 in cerebral amyloid angiopathy-related intracerebral haemorrhage

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of the amyloid β (Aβ) protein in the cerebral vasculature and poses a major risk factor for the development of intracerebral haemorrhages (ICH). However, only a minority of patients with CAA develops ICH (CAA-ICH), and to date it is unclear which mechanisms determine why some patients with CAA are more susceptible to haemorrhage than others. We hypothesized that an imbalance between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) contributes to vessel wall weakening. MMP9 plays a role in the degradation of various components of the extracellular matrix as well as of Aβ and increased MMP9 expression has been previously associated with CAA. TIMP3 is an inhibitor of MMP9 and increased TIMP3 expression in cerebral vessels has also been associated with CAA. In this study, we investigated the expression of MMP9 and TIMP3 in occipital brain tissue of CAA-ICH cases (n = 11) by immunohistochemistry and compared this to the expression in brain tissue of CAA cases without ICH (CAA-non-haemorrhagic, CAA-NH, n = 18). We showed that MMP9 expression is increased in CAA-ICH cases compared to CAA-NH cases. Furthermore, we showed that TIMP3 expression is increased in CAA cases compared to controls without CAA, and that TIMP3 expression is reduced in a subset of CAA-ICH cases compared to CAA-NH cases. In conclusion, in patients with CAA, a disbalance in cerebrovascular MMP9 and TIMP3 expression is associated with CAA-related ICH.

Periodontal Disease and Periodontal Disease-Related Bacteria Involved in the Pathogenesis of Alzheimer's Disease

Alzheimer’s disease (AD) is the most common cause of dementia, and it exhibits pathological properties such as deposition of extracellular amyloid β (Aβ) and abnormally phosphorylated Tau in nerve cells and a decrease of synapses. Conventionally, drugs targeting Aβ and its related molecules have been developed on the basis of the amyloid cascade hypothesis, but sufficient effects on the disease have not been obtained in past clinical trials. On the other hand, it has been pointed out that chronic inflammation and microbial infection in the brain may be involved in the pathogenesis of AD. Recently, attention has been focused on the relationship between the periodontopathic bacterium Porphylomonas gingivalis and AD. P. gingivalis and its toxins have been detected in autopsy brain tissues from patients with AD. In addition, pathological conditions of AD are formed or exacerbated in mice infected with P. gingivalis. Compounds that target the toxins of P. gingivalis ameliorate the pathogenesis of AD triggered by P. gingivalis infection. These findings indicate that the pathological condition of AD may be regulated by controlling the bacteria in the oral cavity and the body. In the current aging society, the importance of oral and periodontal care for preventing the onset of AD will increase.

Contrast leakage distant from the hematoma in patients with spontaneous ICH: A 7 T MRI study

Disruption of the blood-brain barrier (BBB) might play a role in the pathophysiology of cerebral small vessel disease-related ICH. The aim of this study was to assess presence and extent of contrast agent leakage distant from the hematoma as a marker of BBB disruption in patients with spontaneous ICH. We prospectively performed 7 tesla MRI in adult patients with spontaneous ICH and assessed contrast leakage distant from the hematoma on 3D FLAIR images. Thirty-one patients were included (mean age 60 years, 29% women). Median time between ICH and MRI was 20 days (IQR 9-67 days). Seventeen patients (54%; seven lobar, nine deep, one infratentorial ICH) had contrast leakage, located cortical in 16 and cortical and deep in one patient. Patients with contrast leakage more often had lobar cerebral microbleeds (CMBs; 77%) than those without (36%; RR 2.5, 95% CI 1.1-5.7) and a higher number of lobar CMBs (patients with contrast leakage: median 2, IQR 1-8 versus those without: median 0, IQR 0-2; p = 0.02). This study shows that contrast leakage distant from the hematoma is common in days to weeks after spontaneous ICH. It is located predominantly cortical and related to lobar CMBs and therefore possibly to cerebral amyloid angiopathy.

Apolipoprotein D: a potential biomarker for cerebral amyloid angiopathy

AIMS

We investigated the potential of apolipoprotein D (apoD) as cerebrospinal fluid (CSF) biomarker for cerebral amyloid angiopathy (CAA) after confirmation of its association with CAA pathology in human brain tissue.

METHODS

The association of apoD with CAA pathology was analysed in human occipital lobe tissue of CAA (n = 9), Alzheimer's disease (AD) (n = 11) and healthy control cases (n = 11). ApoD levels were quantified in an age- and sex-matched CSF cohort of CAA patients (n = 31), AD patients (n = 27) and non-neurological controls (n = 67). The effects of confounding factors (age, sex, serum levels) on apoD levels were studied using CSF of non-neurological controls (age range 16-85 years), and paired CSF and serum samples.

RESULTS

ApoD was strongly associated with amyloid deposits in vessels, but not with parenchymal plaques in human brain tissue. CSF apoD levels correlated with age and were higher in men than women in subjects >50 years. The apoD CSF/serum ratio correlated with the albumin ratio. When controlling for confounding factors, CSF apoD levels were significantly lower in CAA patients compared with controls and compared with AD patients (P = 0.0008).

CONCLUSIONS

Our data show that apoD is specifically associated with CAA pathology and may be a CSF biomarker for CAA, but clinical application is complicated due to dependency on age, sex and blood-CSF barrier integrity. Well-controlled follow-up studies are required to determine whether apoD can be used as reliable biomarker for CAA.