Changes In Blood-brain Barrier Permeability Research Articles

Chapter 4 - Physiology of the cerebrovascular adaptation to pregnancy

The adaptation of the cerebral circulation to pregnancy is unique compared with other organs and circulatory systems, because the brain requires relatively constant blood flow and water and solute composition to maintain homeostasis. Thus, a major adaptation of the maternal cerebrovasculature to pregnancy is to maintain normalcy in the face of expanded plasma volume, increased cardiac output, and high levels of permeability factors. In this chapter, the effect of pregnancy on critical functions of the cerebral circulation is discussed, including changes occurring at the endothelium and blood-brain barrier (BBB), which protect the maternal brain from changes in BBB permeability. Further, pregnancy-induced changes in the structure and function of cerebral arteries, arterioles, and veins will be discussed as they relate to cerebral vascular resistance, hemodynamics, and cerebral blood flow autoregulation.

Alzheimer Dementia and Microvascular Pathology: Blood-Brain Barrier Permeability Imaging

최근의 연구들은 알츠하이머병의 병리가 단순히 아밀로이드와 타우단백질의 축적만이 아닌, 혈액뇌장벽(blood brain barrier; 이하 BBB) 이상과 같은 미세혈관병리와 밀접한 관련이 있음을 밝히고 있다. BBB 투과도 변화는 아밀로이드 및 타우 단백질 축적뿐 아니라 신경염증과 신경 퇴행성변화를 일으킴으로써 결국 임상 치매를 야기한다. 최근에는 알츠하이머 및 관련 질환의 BBB 이상을 보기 위한 MR 영상의 이용이 증가하고 있다. 이 종설에서는 알츠하이머병에서 BBB와 관련된 병리를 소개하고, BBB 투과도 변화에 대한 MR 영상 연구들을 소개할 것이다. 또한 BBB 투과도 측정을 위한 MR 방법론 개요와 문제점들을 제시할 것이다.

Alteration in the Function and Expression of SLC and ABC Transporters in the Neurovascular Unit in Alzheimer's Disease and the Clinical Significance.

The neurovascular unit (NVU) plays an important role in maintaining the function of the central nervous system (CNS). Emerging evidence has indicated that the NVU changes function and molecules at the early stage of Alzheimer’s disease (AD), which initiates multiple pathways of neurodegeneration. Cell types in the NVU have become attractive targets in the interventional treatment of AD. The NVU transportation system contains a variety of proteins involved in compound transport and neurotransmission. Brain transporters can be classified as members of the solute carrier (SLC) and ATP-binding cassette (ABC) families in the NVU. Moreover, the transporters can regulate both endogenous toxins, including amyloid-beta (Aβ) and xenobiotic homeostasis, in the brains of AD patients. Genome-wide association studies (GWAS) have identified some transporter gene variants as susceptibility loci for late-onset AD. Therefore, the present study summarizes changes in blood-brain barrier (BBB) permeability in AD, identifies the location of SLC and ABC transporters in the brain and focuses on major SLC and ABC transporters that contribute to AD pathology.

A20/TNFAIP3 heterozygosity predisposes to behavioral symptoms in a mouse model for neuropsychiatric lupus

BackgroundNeuropsychiatric lupus (NPSLE) refers to the neurological and psychiatric manifestations that are commonly observed in patients with systemic lupus erythematosus (SLE). An important question regarding the pathogenesis of NPSLE is whether the symptoms are caused primarily by CNS-intrinsic mechanisms or develop as a consequence of systemic autoimmunity. Currently used spontaneous mouse models for SLE have already contributed significantly to unraveling how systemic immunity affects the CNS. However, they are less suited when interested in CNS primary mechanisms. In addition, none of these models are based on genes that are associated with SLE. In this study, we evaluate the influence of A20, a well-known susceptibility locus for SLE, on behavior and CNS-associated changes in inflammatory markers. Furthermore, given the importance of environmental triggers for disease onset and progression, the influence of an acute immunological challenge was evaluated. MethodsFemale and male A20 heterozygous mice (A20+/−) and wildtype littermates were tested in an extensive behavioral battery. This was done at the age of 10±2weeks and 24 ​± ​2 weeks to evaluate the impact of aging. To investigate the contribution of an acute immunological challenge, LPS was injected intracerebroventricularly at the age of 10±2weeks followed by behavioral analysis. Underlying molecular mechanisms were evaluated in gene expression assays on hippocampus and cortex. White blood cell count and blood-brain barrier permeability were analyzed to determine whether peripheral inflammation is a relevant factor. ResultsA20 heterozygosity predisposes to cognitive symptoms that were observed at the age of 10 ​± ​2 weeks and 24 ​± ​2 weeks. Young A20+/− males and females showed a subtle cognitive phenotype (10±2weeks) with distinct neuroinflammatory phenotypes. Aging was associated with clear neuroinflammation in female A20+/− mice only. The genetic predisposition in combination with an environmental stimulus exacerbates the behavioral impairments related to anxiety, cognitive dysfunction and sensorimotor gating. This was predominantly observed in females. Furthermore, signs of neuroinflammation were solely observed in female A20+/− mice. All above observations were made in the absence of peripheral inflammation and of changes in blood-brain barrier permeability, thus consistent with the CNS-primary hypothesis. ConclusionsWe show that A20 heterozygosity is a predisposing factor for NPSLE. Further mechanistic insight and possible therapeutic interventions can be studied in this mouse model that recapitulates several key hallmarks of the disease.

Acute cocaine administration alters permeability of blood-brain barrier in freely-moving rats— Evidence using miniaturized fluorescence microscopy

BackgroundCocaine has a variety of negative effects on the central nervous system, including reports of decreased barrier function of brain microvascular endothelial cells. However, few studies have directly shown the effects of cocaine on blood-brain barrier (BBB) function in vivo. The miniature integrated fluorescence microscope (i.e., miniscope) technology was used to visualize cocaine-induced changes in BBB permeability in awake, freely-moving rats. MethodsThe miniscope was implanted in the prefrontal cortex of adult male rats. After recovery and acclimation, rats received an injection of cocaine (5-20 mg/kg ip) 15 minutes following iv infusion of sodium fluorescein, a low molecular weight tracer. Fluorescence intensity was recordedin vivo via the miniscope for 30 minutes or 24 hours post cocaine administration and served as an indicator of BBB permeability. ResultsResults demonstrate that cocaine increased the sodium fluorescein extravasation in brain microcirculation in a dose-dependent manner 30 minutes, but not 24 hours after administration. ConclusionWe report for the first time using direct visualization of brain microcirculation with the miniscope technology in awake, freely-moving rats, that acute cocaine administration produced a transient increase in the BBB permeability.

Pre- and Post-natal High Fat Feeding Differentially Affects the Structure and Integrity of the Neurovascular Unit of 16-Month Old Male and Female Mice.

Compelling experimental and clinical evidence supports a role for maternal obesity in offspring health. Adult children of obese mothers are at greater risk of obesity, diabetes, coronary heart disease and stroke. These offspring may also be at greater risk of age-related neurodegenerative diseases for which mid-life obesity is a risk factor. Rodent diet-induced obesity models have shown that high fat (HF) diet consumption damages the integrity of the blood–brain barrier (BBB) in the adult brain. However, there is currently little information about the effect of chronic HF feeding on the BBB of aged animals. Moreover, the long-term consequences of maternal obesity on the cerebrovasculature of aged offspring are not known. This study determined the impact of pre- and post-natal HF diet on the structure and integrity of cerebral blood vessels in aged male and female mice. Female C57Bl/6 mice were fed either a 10% fat control (C) or 45% HF diet before mating and during gestation and lactation. At weaning, male and female offspring were fed the C or HF diet until sacrifice at 16-months of age. Both dams and offspring fed the HF diet weighed significantly more than mice fed the C diet. Post-natal HF diet exposure increased hippocampal BBB leakiness in female offspring, in association with loss of astrocyte endfoot coverage of arteries. Markers of tight junctions, pericytes or smooth muscle cells were not altered by pre- or post-natal HF diet. Male offspring born to HF-fed mothers showed decreased parenchymal GFAP expression compared to offspring of mothers fed C diet, while microglial and macrophage markers were higher in the same female diet group. In addition, female offspring exposed to the HF diet for their entire lifespan showed more significant changes in vessel structure, BBB permeability and inflammation compared to male animals. These results suggest that the long-term impact of prenatal HF diet on the integrity of cerebral blood vessels differs between male and female offspring depending on the post-natal diet. This may have implications for the prevention and management of age- and obesity-related cerebrovascular diseases that differentially affect men and women.

Changes in blood-brain barrier permeability and ultrastructure, and protein expression in a rat model of cerebral hypoperfusion

Cerebral hypoperfusion involved a reduction in cerebral blood flow, leading to neuronal dysfunction, microglial activation and white matter degeneration. The effects on the blood-brain barrier (BBB) however, have not been well-documented. Here, two-vessel occlusion model was adopted to mimic the condition of cerebral hypoperfusion in Sprague-Dawley rats. The BBB permeability to high and low molecular weight exogenous tracers i.e. Evans blue dye and sodium fluorescein respectively, showed marked extravasation of the Evans blue dye in the frontal cortex, posterior cortex and thalamus-midbrain at day 1 following induction of cerebral hypoperfusion. Transmission electron microscopy revealed brain endothelial cell and astrocyte damages including increased pinocytotic vesicles and formation of membrane invaginations in the endothelial cells, and swelling of the astrocytes’ end-feet. Investigation on brain microvessel protein expressions using two-dimensional (2D) gel electrophoresis coupled with LC–MS/MS showed that proteins involved in mitochondrial energy metabolism, transcription regulation, cytoskeleton maintenance and signaling pathways were differently expressed. The expression of aconitate hydratase, heterogeneous nuclear ribonucleoprotein, enoyl Co-A hydratase and beta-synuclein were downregulated, while the opposite observed for calreticulin and enhancer of rudimentary homolog. These findings provide insights into the BBB molecular responses to cerebral hypoperfusion, which may assist development of future therapeutic strategies.

Synergistic Role of Oxidative Stress and Blood-Brain Barrier Permeability as Injury Mechanisms in the Acute Pathophysiology of Blast-induced Neurotrauma

Blast-induced traumatic brain injury (bTBI) has been recognized as the common mode of neurotrauma amongst military and civilian personnel due to an increased insurgent activity domestically and abroad. Previous studies from our laboratory have identified enhanced blood-brain barrier (BBB) permeability as a significant, sub-acute (four hours post-blast) pathological change in bTBI. We also found that NADPH oxidase (NOX)-mediated oxidative stress occurs at the same time post-blast when the BBB permeability changes. We therefore hypothesized that oxidative stress is a major causative factor in the BBB breakdown in the sub-acute stages. This work therefore examined the role of NOX1 and its downstream effects on BBB permeability in the frontal cortex (a region previously shown to be the most vulnerable) immediately and four hours post-blast exposure. Rats were injured by primary blast waves in a compressed gas-driven shock tube at 180 kPa and the BBB integrity was assessed by extravasation of Evans blue and changes in tight junction proteins (TJPs) as well as translocation of macromolecules from blood to brain and vice versa. NOX1 abundance was also assessed in neurovascular endothelial cells. Blast injury resulted in increased extravasation and reduced levels of TJPs in tissues consistent with our previous observations. NOX1 levels were significantly increased in endothelial cells followed by increased superoxide production within 4 hours of blast. Blast injury also increased the levels/activation of matrix metalloproteinase 3 and 9. To test the role of oxidative stress, rats were administered apocynin, which is known to inhibit the assembly of NOX subunits and arrests its function. We found apocynin completely inhibited dye extravasation as well as restored TJP levels to that of controls and reduced matrix metalloproteinase activation in the sub-acute stages following blast. Together these data strongly suggest that NOX-mediated oxidative stress contributes to enhanced BBB permeability in bTBI through a pathway involving increased matrix metalloproteinase activation.

Epileptiform activity contralateral to unilateral hippocampal sclerosis does not cause the expression of brain damage markers.

Patients with epilepsy often ask if recurrent seizures harm their brain and aggravate their epileptic condition. This crucial question has not been specifically addressed by dedicated experiments. We analyze here if intense bilateral seizure activity induced by local injection of kainic acid (KA) in the right hippocampus produces brain damage in the left hippocampus. Adult guinea pigs were bilaterally implanted with hippocampal electrodes for continuous video-electroencephalography (EEG) monitoring. Unilateral injection of 1μg KA in the dorsal CA1 area induced nonconvulsive status epilepticus (ncSE) characterized by bilateral hippocampal seizure discharges. This treatment resulted in selective unilateral sclerosis of the KA-injected hippocampus. Three days after KA injection, the animals were killed, and the brains were submitted to ex vivo magnetic resonance imaging (MRI) and were processed for immunohistochemical analysis. During ncSE, epileptiform activity was recorded for 27.6±19.1hours in both the KA-injected and contralateral hippocampi. Enhanced T1-weighted MR signal due to gadolinium deposition, mean diffusivity reduction, neuronal loss, gliosis, and blood-brain barrier permeability changes was observed exclusively in the KA-injected hippocampus. Despite the presence of a clear unilateral hippocampal sclerosis at the site of KA injection, no structural alterations were detected by MR and immunostaining analysis performed in the hippocampus contralateral to KA injection 3days and 2months after ncSE induction. Fluoro-Jade and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining at the same time points confirmed the absence of degenerating cells in the hippocampi contralateral to KA injection. We demonstrate that intense epileptiform activity during ncSE does not cause obvious brain damage in the hippocampus contralateral to unilateral hippocampal KA injection. These findings argue against the hypothesis that epileptiform activity per se contributes to focal brain injuryin previously undamaged cortical regions.

CCL26 and CCR3 are associated with the acute inflammatory response in the CNS in experimental autoimmune encephalomyelitis

Chemokine ligand 26 (CCL26) is a member of the eotaxin family. It works by interacting exclusively with chemokine receptor 3 (CCR3) and acts as an eosinophil-selective chemoattractant. There is an emerging role for eotaxins in autoimmune diseases. Studies have reported that chemokine ligand 11 (CCL11) and CCL26 are upregulated in patients with neuromyelitis optica spectrum disorder (NMOSD) during remission, CCL26 levels appear to be decreased in relapsing-remitting multiple sclerosis (RRMS), whereas CCL26 levels are significantly increased in secondary progressive multiple sclerosis (SPMS), indicating that CCL26 participates in the pathogenesis of multiple sclerosis (MS). We investigated the levels of CCL26, CCR3 and claudin-5 (a marker of changes in BBB (blood-brain barrier) permeability) at different stages of experimental autoimmune encephalomyelitis (EAE) to explore the underlying immune mechanisms of EAE. Our results showed that the levels of CCL26 and CCR3 in EAE rats were significantly increased compared with those in the control group. The levels of CCL26 in the serum and in brain tissues as well as the protein expression of CCR3 in brain tissues were positively correlated with the inflammatory scores of brain tissues from EAE rats and were negatively correlated with the protein expression of claudin-5. We concluded that CCL26, which in turn binds to the receptor CCR3, showed pro-inflammatory effects and aggravated tissue damage involving BBB impairment, especially in the acute stage of EAE. Our study uncovers another possible immunopathological mechanism of MS and provides a possible target for immune therapy.

Invasion of a murine in vitro blood-brain barrier co-culture model by dengue virus serotypes 1 to 4.

The blood-brain barrier (BBB) is a physical barrier that restricts the passage of cells and molecules as well as pathogens into the central nervous system (CNS). Some viruses enter the CNS by disrupting the BBB, while others can reach the CNS without altering the integrity of the BBB. Even though dengue virus (DENV) is not a distinctive neurotropic virus, the virus is considered to be one of the leading causes of neurological manifestations. In this study, we found that DENV is able to compromise the integrity of a murine in vitro blood-brain barrier (BBB) model, resulting in hyperpermeability, as shown by a significant increase in sucrose and albumin permeability. Infection of brain endothelial cells (ECs) was facilitated by the presence of glycans, in particular, mannose and N-acetyl glucosamine residues, on cell surfaces and viral envelope proteins, and the requirement for glycan moieties for cell infection was serotype-specific. Direct viral disruption of brain ECs was observed, leading to a significant decrease in tight-junction protein expression and peripheral localization, which contributed to the changes in BBB permeability. In conclusion, the hyperpermeability and breaching mechanism of BBB by DENV are primarily due to direct consequences of viral infection of ECs, as shown in this in vitro study.

Abstract # 2065 Markers of peripheral immune cells are increased in regions of blood-brain barrier disruption after repetitive blast injury

Cycles of blood-brain barrier (BBB) disruption have been observed in a variety of rodent brain injury models. Changes in BBB permeability are correlated with pro-inflammatory cytokine production and brain infiltration of peripheral leukocytes. Whether the influx of peripheral leukocytes through a permeable BBB affords prolonged neuroprotection, or promotes detrimental changes to the anatomical site of entry remains to be elucidated. In a mouse model of blast-induced traumatic brain injury (TBI), we observed brain-region specific BBB permeability to radiolabeled albumin at 72 h. Moreover, we measured an increase in pro-inflammatory tumor necrosis factor alpha (TNF α ) protein expression and mRNA abundance in brain regions vulnerable to BBB disruption. The nitric oxide synthase inhibitor N(G)-nitro- l -arginine methyl ester (L-NAME) attenuated TNF α levels and abrogated albumin permeability. We hypothesize that leukocyte infiltration into vulnerable brain regions after TBI may also be mediated by nitric oxide dependent mechanisms. Using flow cytometry, we measured an increase of blood-derived monocytes (Ly6C/G-high and CD45-high) and T-cells (CD3+ and CD4+) in brain regions vulnerable to BBB disruption at 72 h post-TBI. The physiological process of leukocyte infiltration could be driven by nitric oxide dependent mechanisms, which could be exploited, at the right time, to assist in chronic neurotrauma resolution.

Abstract TP439: Temporal Evolution of Blood-brain Barrier Permeability After Acute Spontaneous Intracerebral Hemorrhage: A CT Perfusion Study

Introduction: Spontaneous intracerebral hemorrhage (ICH) is associated with increased blood-brain barrier (BBB) permeability, potentially contributing to hematoma expansion, edema development and exacerbation of brain injury. Though we know BBB permeability with time after the onset of ICH, little is about the temporal evolution of BBB permeability in humans after ICH. A more detailed understanding the timeline of BBB permeability change after ICH would be important for guiding future ICH treatments. Hypothesis: We want to test the hypothesis there is two increase in BBB permeability in ICH patients. Methods: Patients with ICH were divided into five groups based on the period between ICH onset and computed tomography perfusion (CTP) assessed, which are hyperacute (<24 hours), acute (1~3 days), early subacute (3~7 days), late subacute (7~14 days) and chronic (>14 days) groups. Maps of BBB permeability-surface area product (PS), a measure of extravascular contrast leakage rate, were calculated from CTP source images. Mean PS was measured in regions of interest defining the hematoma, a 1cm radial peri-hematoma region,in both ICH and contralateral non-ICH hemispheres. Results: PS maps were generated in 61 patients (17 female, mean age 53 years old). The median (interquartile range) PS in ICH hemisphere of 31 patients underwent CTP in hyperacute phase is 1.4 (5.3), 8 patients in acute phase is 1.6 (3.2), 11 patients in early subacute phase is 1.2 (0.8), 8 patients in late subacute phase is 0.7 (1.2), and 3 patients in chronic phase is 0.9. The BBB permeability has an early increase in hyperacute phase, is followed by a decrease period in acute and subacute phases, and a delayed second increase in chronic phase. The permeability pattern is similar in non-ICH hemisphere; however, the second increase in permeability was from late subacute phase. Discussions: In conclusion, acute ICH patients have a generalized increase in BBB permeability, which affects the entire brain diffusely. The BBB permeability is not continually elevated but follows a triphasic course in ICH patients.

Memory deficits in males and females long after subchronic immune challenge.

Memory impairments and cognitive decline persist long after recovery from major illness or injury, and correlate with increased risk of later dementia. Here we developed a subchronic peripheral immune challenge model to examine delayed and persistent memory impairments in females and in males. We show that intermittent injections of either lipopolysaccharides or Poly I:C cause memory decline in both sexes that are evident eight weeks after the immune challenge. Importantly, we observed sex-specific patterns of deficits. Females showed impairments in object recognition one week after challenge that persisted for at least eight weeks. In contrast, males had intact memory one week after the immune challenge but exhibited broad impairments in memory tasks including object recognition, and both context and tone fear conditioning several months later. The differential patterns of memory deficits in males and in females were observed without sustained microglial activation or changes in blood-brain barrier permeability. Together, these data suggest that transient neuroimmune activity results in differential vulnerabilities of females and males to memory decline after immune challenge. This model will be an important tool for determining the mechanisms in both sexes that contribute to memory impairments that develop over the weeks and months after recovery from illness. Future studies using this model will provide new insights into the role of chronic inflammation in the pathogenesis of long-lasting memory decline and dementias.

Изменения проницаемости гематоэнцефалического барьера под воздействием громкого звука

Изменения проницаемости гематоэнцефалического барьера под воздействием громкого звука

Blood-brain barrier and innate immunity in the pathogenesis of Alzheimer's disease.

The pathogenesis of Alzheimer's disease (AD) is only partly understood. This is the probable reason why significant efforts to treat or prevent AD have been unsuccessful. In fact, as of April 2019, there have been 2094 studies registered for AD on the clinicaltrials.gov U.S. National Library of Science web page, of which only a few are still ongoing. In AD, abnormal accumulation of amyloid and tau proteins in the brain are thought to begin 10-20 years before the onset of overt symptoms, suggesting that interventions designed to prevent pathological amyloid and tau accumulation may be more effective than attempting to reverse a pathology once it is established. However, to be successful, such early interventions need to be selectively administered to individuals who will likely develop the disease long before the symptoms occur. Therefore, it is critical to identify early biomarkers that are strongly predictive of AD. Currently, patients are diagnosed on the basis of a variety of clinical scales, neuropsychological tests, imaging and laboratory modalities, but definitive diagnosis can be made only by postmortem assessment of underlying neuropathology. People suffering from AD thus may be misdiagnosed clinically with other primary causes of dementia, and vice versa, thereby also reducing the power of clinical trials. The amyloid cascade hypothesis fits well for the familial cases of AD with known mutations, but is not sufficient to explain sporadic, late-onset AD (LOAD) that accounts for over 95% of all cases. Since the earliest descriptions of AD there have been neuropathological features described other than amyloid plaques (AP) and neurofibrillary tangles (NFT), most notably gliosis and neuroinflammation. However, it is only recently that genetic and experimental studies have implicated microglial dysfunction as a causal factor for AD, as opposed to a merely biological response of its accumulation around AP. Additionally, many studies have suggested the importance of changes in blood-brain barrier (BBB) permeability in the pathogenesis of AD. Here we suggest how these less investigated aspects of the disease that have gained increased attention in recent years may contribute mechanistically to the development of lesions and symptoms of AD.

In vivo monitoring blood-brain barrier permeability using spectral imaging through optical clearing skull window.

The blood-brain barrier (BBB) plays a key role in the health of the central nervous system. Opening the BBB is very important for drug delivery to brain tissues to enhance the therapeutic effect on brain diseases. It is necessary to in vivo monitor the BBB permeability for assessing drug release with high resolution; however, an effective method is lacking. In this work, we developed a new method that combined spectral imaging with an optical clearing skull window to in vivo dynamically monitor BBB opening caused by 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy (PDT), in which the Evans blue dye (EBd) acted as an indicator of the BBB permeability. Using this method, we effectively monitored the cerebrovascular EBd leakage process. Moreover, the analysis of changes in the vascular and extravascular EBd concentrations demonstrated that the PDT-induced BBB opening exhibited spatiotemporal differences in the cortex. This spectral imaging method based on the optical clearing skull window provides a low-cost and simply operated tool for in vivo monitoring BBB opening process. This has a high potential for the visualization of drug delivery to the central nervous system. Thus, it is of tremendous significance in brain disease therapy. Monitoring the changes in PDT-induced BBB permeability by evaluating the EBd concentration using an optical clearing skull window. (A) Entire brains and coronal sections following treatment of PDT with/without an optical clearing skull window after injection of EBd. (B) Typical EBd distribution maps before and after laser irradiation captured by the spectral imaging method. (Colorbar represents the EBd concentration).

R-CHOP Preceded By Engineered Tumor Necrosis Factor (TNF) in Patients with Relapsed or Refractory (r/r) Primary CNS Lymphoma (PCNSL): Results of Antitumor Activity, Safety and Blood-Brain Barrier (BBB) Permeabilization in the “Ingrid” Phase II Trial

Background: Almost all PCNSL belong to the category of DLBCL. However, affected pts are treated with high-dose methotrexate-based combinations that are not currently used in other DLBCL and require hospitalization and extensive expertise to manage toxicity. The use of R-CHOP could overcome these difficulties, but CNS availability of related drugs is poor. TNF induces BBB permeabilization and enhances CNS access of anticancer drugs. Coupling TNF with NGR, a peptide that targets CD13+ tumor vessels, improves its biological effects and therapeutic index. Thus, we tested the hypothesis that this conjugate (called NGR-hTNF) can break the BBB, thereby improving CNS access and activity of R-CHOP in pts with r/rPCNSL enrolled in a phase II trial (NCT03536039). Herein, we report results of activity, safety and BBB permeabilization.Methods: HIV-neg adults with PCNSL failed after methotrexate-based chemo and measurable disease were enrolled and treated with 1 course of R-CHOP, followed by 5 courses of R-CHOP21 preceded by NGR-hTNF (0.8 μg/m², 1-h inf). Overall response rate (ORR) was the primary endpoint. The two-stage Simon Minimax design was used; sample size estimated to demonstrate an improvement from 30% ORR (P0) to 50% (P1) (one-sided test; α 10%; β 90%) was 28 pts. NGR-hTNF/RCHOP would be declared active if ≥12 responses were recorded.As secondary endpoints, changes in vessel permeability, CD13 expression and anticancer drugs pharmacokinetics were assessed in the first 10 pts. Changes in BBB permeability were assessed by Dynamic Contrast Enhanced MRI (DCE-MRI) and 99mTc-DTPA-SPECT in tumor lesions, perilesional areas and normal appearing brain. DCE-MRI findings recorded before/after the 1st course (RCHOP alone - baseline) and before/after the 2nd and 6th courses (NGR-hTNF/RCHOP) were compared to establish the effect of TNF, and results were expressed as Ktrans values normalized using contralateral white matter. SPECT was performed before and after the 3rd course, and results were expressed as changes in the volume of ≥30% 99mTc-DTPA uptake (cm3). CD13 expression was assessed by immunohistochemistry on diagnostic tissue samples. Rituximab, cyclophosphamide and doxorubicin concentrations on matched CSF/plasma samples collected before/after the 1st, 2nd and 6th courses were tested to exclude a non-specific effect of NGR-hTNF on pharmacokinetics.Results: 22 pts (median age: 58 yo, range 26-78; 11 males) were enrolled; 18 pts had intermediate-high IELSG score. Pts were heavily pretreated: 13 had received ASCT, WBRT or both; 13 had refractory disease. Twenty pts were evaluable for the primary endpoint.NGR-hTNF/RCHOP combination was active: the predetermined activity threshold (≥12 responses) was achieved, with confirmed tumor response in 13 pts (65%; 95%CI= 45-85%), which was complete in 9. At a median follow-up of 8 months (2-26), 9 pts remain relapse free and 12 pts are alive.Treatment was well tolerated; toxicities were quickly solved without dose reductions or interruptions. G4 toxicities were neutropenia (49% of courses) and thrombocytopenia (15%), anemia (1%), and FN (1%). Ten SAEs were recorded in 8 pts: g2 seizures (n= 2), g2 DVT (2), g3 infections (2), g3 syncope (2), g4 FN and g2 LVEF reduction. There were 3 cases of g1-2 TNF infusion reaction.DCE-MRI studies showed an increase of vascular permeability after NGR-hTNF infusion as median (range) Ktrans of tumor and perilesional areas raised from baseline values of 23.5 (6.8-98.8) and 2.5 (0.4-3.9) to 35.3 (23.9-887.7; p= 0.39) and 4.7 (2.2-37.7; p= 0.01), respectively. Likewise, SPECT studies showed a significant enlargement of the volume ≥30% 99mTc-DTPA uptake, with median (range) values before and after NGR-hTNF infusion of 26 cm3 (5 - 67) and 40 cm3 (10 - 92), respectively (p= 0.02), with a median volume increase of 45% (14-87%). As important features supporting the specificity of the effect of NGR-hTNF, CD13 was expressed in all diagnostic samples, and drug levels in CSF/plasma samples were not influenced by NGR-hTNF.Conclusions: NGR-hTNF/RCHOP is active and safe in pts with r/rPCNSL. NGR-hTNF enhances vascular permeability specifically in tumor lesions and perilesional areas, which was consistently demonstrated by DCE-MRI, SPECT and plasma/CSF pharmacokinetics studies and was in line with CD13 expression. Accrual completion is warranted. This innovative approach deserves to be addressed as first-line treatment in PCNSL pts. DisclosuresAngelucci:Novartis: Honoraria, Other: Chair Steering Comiittee TELESTO Protocol; Vertex Pharmaceuticals Incorporated (MA) and CRISPR CAS9 Therapeutics AG (CH): Other: Chair DMC; Jazz Pharmaceuticals Italy: Other: Local ( national) advisory board; Roche Italy: Other: Local (national) advisory board; Celgene: Honoraria, Other: Chair DMC.

Prolonged systemic hyperglycemia does not cause pericyte loss and permeability at the mouse blood-brain barrier

Diabetes mellitus is associated with cognitive impairment and various central nervous system pathologies such as stroke, vascular dementia, or Alzheimer’s disease. The exact pathophysiology of these conditions is poorly understood. Recent reports suggest that hyperglycemia causes cerebral microcirculation pathology and blood-brain barrier (BBB) dysfunction and leakage. The majority of these reports, however, are based on methods including in vitro BBB modeling or streptozotocin-induced diabetes in rodents, opening questions regarding the translation of the in vitro findings to the in vivo situation, and possible direct effects of streptozotocin on the brain vasculature. Here we used a genetic mouse model of hyperglycemia (Ins2AKITA) to address whether prolonged systemic hyperglycemia induces BBB dysfunction and leakage. We applied a variety of methodologies to carefully evaluate BBB function and cellular integrity in vivo, including the quantification and visualization of specific tracers and evaluation of transcriptional and morphological changes in the BBB and its supporting cellular components. These experiments did neither reveal altered BBB permeability nor morphological changes of the brain vasculature in hyperglycemic mice. We conclude that prolonged hyperglycemia does not lead to BBB dysfunction, and thus the cognitive impairment observed in diabetes may have other causes.

Mechanisms of Blood-Brain Barrier Disruption in Herpes Simplex Encephalitis.

Herpes simplex encephalitis (HSE) is often caused by infection with herpes simplex virus 1 (HSV-1), a neurotropic double-stranded DNA virus. HSE infection always impacts the temporal and frontal lobes or limbic system, leading to edema, hemorrhage, and necrotic changes in the brain parenchyma. Additionally, patients often exhibit severe complications following antiviral treatment, including dementia and epilepsy. HSE is further associated with disruptions to the blood-brain barrier (BBB), which consists of microvascular endothelial cells, tight junctions, astrocytes, pericytes, and basement membranes. Following an HSV-1 infection, changes in BBB integrity and permeability can result in increased movement of viruses, immune cells, and/or cytokines into the brain parenchyma. This leads to an enhanced inflammatory response in the central nervous system and further damage to the brain. Thus, it is important to protect the BBB from pathogens to reduce brain damage from HSE. Here, we discuss HSE and the normal structure and function of the BBB. We also discuss growing evidence indicating an association between BBB breakdown and the pathogenesis of HSE, as well as future research directions and potential new therapeutic targets. Graphical Abstract During herpes simplex encephalitis, the functions and structures of each composition of BBB have been altered by different factors, thus the permeability and integrity of BBB have been broken. The review aim to explore the potential mechanisms and factors in the process, probe the next research targets and new therapeutic targets.