It is unclear whether severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019, can enter the brain. Severe acute respiratory syndrome coronavirus 2 binds to cells via ...the S1 subunit of its spike protein. We show that intravenously injected radioiodinated S1 (I-S1) readily crossed the blood-brain barrier in male mice, was taken up by brain regions and entered the parenchymal brain space. I-S1 was also taken up by the lung, spleen, kidney and liver. Intranasally administered I-S1 also entered the brain, although at levels roughly ten times lower than after intravenous administration. APOE genotype and sex did not affect whole-brain I-S1 uptake but had variable effects on uptake by the olfactory bulb, liver, spleen and kidney. I-S1 uptake in the hippocampus and olfactory bulb was reduced by lipopolysaccharide-induced inflammation. Mechanistic studies indicated that I-S1 crosses the blood-brain barrier by adsorptive transcytosis and that murine angiotensin-converting enzyme 2 is involved in brain and lung uptake, but not in kidney, liver or spleen uptake.
Aneurysmal subarachnoid hemorrhage (SAH) can lead to devastating outcomes including vasospasm, cognitive decline, and even death. Currently, treatment options are limited for this potentially life ...threatening injury. Recent evidence suggests that neuroinflammation plays a critical role in injury expansion and brain damage. Red blood cell breakdown products can lead to the release of inflammatory cytokines that trigger vasospasm and tissue injury. Preclinical models have been used successfully to improve understanding about neuroinflammation following aneurysmal rupture. The focus of this review is to provide an overview of how neuroinflammation relates to secondary outcomes such as vasospasm after aneurysmal rupture and to critically discuss pharmaceutical agents that warrant further investigation for the treatment of subarachnoid hemorrhage. We provide a concise overview of the neuroinflammatory pathways that are upregulated following aneurysmal rupture and how these pathways correlate to long-term outcomes. Treatment of aneurysm rupture is limited and few pharmaceutical drugs are available. Through improved understanding of biochemical mechanisms of injury, novel treatment solutions are being developed that target neuroinflammation. In the final sections of this review, we highlight a few of these novel treatment approaches and emphasize why targeting neuroinflammation following aneurysmal subarachnoid hemorrhage may improve patient care. We encourage ongoing research into the pathophysiology of aneurysmal subarachnoid hemorrhage, especially in regards to neuroinflammatory cascades and the translation to randomized clinical trials.
A growing body of evidence indicates that the microbiome interacts with the central nervous system (CNS) and can regulate many of its functions. One mechanism for this interaction is at the level of ...the blood–brain barriers (BBBs). In this minireview, we examine the several ways the microbiome is known to interact with the CNS barriers. Bacteria can directly release factors into the systemic circulation or can translocate into blood. Once in the blood, the microbiome and its factors can alter peripheral immune cells to promote interactions with the BBB and ultimately with other elements of the neurovascular unit. Bacteria and their factors or cytokines and other immune-active substances released from peripheral sites under the influence of the microbiome can cross the BBB, alter BBB integrity, change BBB transport rates, or induce release of neuroimmune substances from the barrier cells. Metabolic products produced by the microbiome, such as short-chain fatty acids, can cross the BBB to affect brain function. Through these and other mechanisms, microbiome–BBB interactions can influence the course of diseases as illustrated by multiple sclerosis.
Impact statement
The connection between the gut microbiome and central nervous system (CNS) disease is not fully understood. Host immune systems are influenced by changes to the microbiota and offers new treatment strategies for CNS disease. Preclinical studies provide evidence of changes to the blood–brain barrier when animals are subject to experimental gut infection or when the animals lack a normal gut microbiome. The intestine also contains a barrier, and bacterial factors can translocate to the blood and interact with host immune cells. These metastatic bacterial factors can signal T-cells to become more CNS penetrant, thus providing a novel intervention for treating CNS disease. Studies in humans show the therapeutic effects of T-cell engineering for the treatment of leukemia, so perhaps a similar approach for CNS disease could prove effective. Future research should begin to define the bacterial species that can cause immune cells to differentiate and how these interactions vary amongst CNS disease models.
The blood-brain barrier (BBB) protects the central nervous system (CNS) from unregulated exposure to the blood and its contents. The BBB also controls the blood-to-brain and brain-to-blood permeation ...of many substances, resulting in nourishment of the CNS, its homeostatic regulation and communication between the CNS and peripheral tissues. The cells forming the BBB communicate with cells of the brain and in the periphery. This highly regulated interface changes with healthy aging. Here, we review those changes, starting with morphology and disruption. Transporter changes include those for amyloid beta peptide, glucose and drugs. Brain fluid dynamics, pericyte health and basement membrane and glycocalyx compositions are all altered with healthy aging. Carrying the
allele leads to an acceleration of most of the BBB's age-related changes. We discuss how alterations in the BBB that occur with healthy aging reflect adaptation to the postreproductive phase of life and may affect vulnerability to age-associated diseases.
Mild blast-induced traumatic brain injury (TBI) is associated with blood-brain barrier (BBB) disruption. However, the mechanisms whereby blast disrupts BBB integrity are not well understood. To ...address this issue BBB permeability to peripherally injected
C-sucrose and
Tc-albumin was quantified in ten brain regions at time points ranging from 0.25 to 72 hours. In mice, repetitive (2X) blast provoked BBB permeability to
C-sucrose that persisted in specific brain regions from 0.25 to 72 hours. However,
Tc-albumin revealed biphasic BBB disruption (open-closed-open) over the same interval, which was most pronounced in frontal cortex and hippocampus. This indicates that blast initiates interacting BBB disruption and reparative processes in specific brain regions. Further investigation of delayed (72 hour) BBB disruption revealed that claudin-5 (CLD5) expression was disrupted specifically in the hippocampus, but not in dorsal striatum, a brain region that showed no blast-induced BBB permeability to sucrose or albumin. In addition, we found that delayed BBB permeability and disrupted CLD5 expression were blocked by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). These data argue that latent nitric oxide-dependent signaling pathways initiate processes that result in delayed BBB disruption, which are manifested in a brain-region specific manner.
Circulating levels of inter-alpha inhibitor proteins change dramatically in acute inflammatory disorders, which suggest an important contribution to the immunomodulatory system. Human blood-derived ...inter-alpha inhibitor proteins are neuroprotective and improve survival of neonatal mice exposed to lipopolysaccharide. Lipopolysaccharide augments inflammatory conditions and disrupts the blood–brain barrier. There is a paucity of therapeutic strategies to treat blood–brain barrier dysfunction, and the neuroprotective effects of human blood-derived inter-alpha inhibitor proteins are not fully understood. To examine the therapeutic potential of inter-alpha inhibitor proteins, we administered human blood-derived inter-alpha inhibitor proteins to male and female CD-1 mice after lipopolysaccharide exposure and quantified blood–brain barrier permeability of intravenously injected 14C-sucrose and 99mTc-albumin. We hypothesized that human blood-derived inter-alpha inhibitor protein treatment would attenuate lipopolysaccharide-induced blood–brain barrier disruption and associated inflammation. Lipopolysaccharide increased blood–brain barrier permeability to both 14C-sucrose and 99mTc-albumin, but human blood-derived inter-alpha inhibitor protein treatment only attenuated increases in 14C-sucrose blood–brain barrier permeability in male mice. Lipopolysaccharide stimulated a more robust elevation of male serum inter-alpha inhibitor protein concentration compared to the elevation measured in female serum. Lipopolysaccharide administration also increased multiple inflammatory factors in serum and brain tissue, including interleukin 6. Human blood-derived inter-alpha inhibitor protein treatment downregulated serum interleukin 6 levels, which were inversely correlated with serum inter-alpha inhibitor protein concentration. We conclude that inter-alpha inhibitor proteins may be neuroprotective through mechanisms of blood–brain barrier disruption associated with systemic inflammation.
Type II diabetes is a vascular risk factor for cognitive impairment and increased risk of dementia. Disruption of the blood-retinal barrier (BRB) and blood-brain barrier (BBB) are hallmarks of ...subsequent retinal edema and central nervous system dysfunction. However, the mechanisms by which diet or metabolic syndrome induces dysfunction are not understood. A proposed mechanism is an increase in reactive oxygen species (ROS) and oxidative stress. Inhibition of mitochondrial carbonic anhydrase (mCA) decreases ROS and oxidative stress. In this study, topiramate, a mCA inhibitor, was examined for its ability to protect the BRB and BBB in diet-induced obese type II diabetic mice.
BBB and BRB permeability were assessed using
C-sucrose and
Tc-albumin in CD-1 mice fed a low-fat (control) or a high-fat diet. Topiramate administration was compared to saline controls in both preventative and efficacy arms examining BRB and BBB disruption. Body weight and blood glucose were measured weekly and body composition was assessed using EchoMRI. Metabolic activity was measured using a comprehensive laboratory animal monitoring system. Brain tissues collected from the mice were assessed for changes in oxidative stress and tight junction proteins.
High-fat feeding caused increased entry of
C-sucrose and
Tc-albumin into the brains of diet-induced obese type II diabetic mice. Increased permeability to
C-sucrose was observed in the hypothalamus and hippocampus, and attenuated by topiramate treatment, while increased permeability to
Tc-albumin occurred in the whole brain and was also attenuated by topiramate. Treatment with topiramate decreased measures of oxidative stress and increased expression of the tight junction proteins ZO-1 and claudin-12. In the retina, we observed increased entry of
Tc-albumin simultaneously with increased entry into the whole brain during the preventative arm. This occurred prior to increased entry to the retina for
C-sucrose which occurred during the efficacy arm. Treatment with topiramate had no effect on the retina.
Blood-brain barrier and blood-retinal barrier dysfunction were examined in a mouse model of diet-induced obese type II diabetes. These studies demonstrate that there are spatial and temporal differences in
C-sucrose and
Tc-albumin permeability in the brain and retina of diet-induced obese type II diabetic mice. Topiramate, a mitochondrial carbonic anhydrase inhibitor, is efficacious at both preventing and treating BBB disruption in this diet-induced obese type II diabetic mouse model.
Abstract Traumatic brain injury (TBI) is the leading cause of trauma related morbidity in the developed world. TBI has been shown to trigger secondary injury cascades including endoplasmic reticulum ...(ER) stress, oxidative stress, and neuroinflammation. The link between secondary injury cascades and behavioral outcome following TBI is poorly understood warranting further investigation. Using our validated rodent blast TBI model, we examined the interaction of secondary injury cascades following single injury and how these interactions may contribute to impulsive-like behavior after a clinically relevant repetitive TBI paradigm. We targeted these secondary pathways acutely following single injury with the cellular stress modulator, salubrinal (SAL). We examined the neuroprotective effects of SAL administration on significantly reducing ER stress: janus-N-terminal kinase (JNK) phosphorylation and C/EBP homology protein (CHOP), oxidative stress: superoxide and carbonyls, and neuroinflammation: nuclear factor kappa beta (NFκB) activity, inducible nitric oxide synthase (iNOS) protein expression, and pro-inflammatory cytokines at 24 hours post-TBI. We then used the more clinically relevant repeat injury paradigm and observed elevated NFκB and iNOS activity. These injury cascades were associated with impulsive-like behavior measured on the elevated plus maze. SAL administration attenuated secondary iNOS activity at 72 hours following repetitive TBI, and most importantly prevented impulsive-like behavior. Overall, these results suggest a link between secondary injury cascades and impulsive-like behavior that can be modulated by SAL administration.
Blood-Brain Barriers in Obesity Rhea, Elizabeth M.; Salameh, Therese S.; Logsdon, Aric F. ...
The AAPS journal,
07/2017, Letnik:
19, Številka:
4
Journal Article
Recenzirano
Odprti dostop
After decades of rapid increase, the rate of obesity in adults in the USA is beginning to slow and the rate of childhood obesity is stabilizing. Despite these improvements, the obesity epidemic ...continues to be a major health and financial burden. Obesity is associated with serious negative health outcomes such as cardiovascular disease, type II diabetes, and, more recently, cognitive decline and various neurodegenerative dementias such as Alzheimer’s disease. In the past decade, major advancements have contributed to the understanding of the role of the central nervous system (CNS) in the development of obesity and how peripheral hormonal signals modulate CNS regulation of energy homeostasis. In this article, we address how obesity affects the structure and function of the blood-brain barrier (BBB), the impact of obesity on Alzheimer’s disease, the effects of obesity on circulating proteins and their transport into the brain, and how these changes can potentially be reversed by weight loss.
Highlights • No current treatments are available for post-traumatic epilepsy. • Post-traumatic epilepsy is a serious concern for patients following neurotrauma. • Mechanisms of injury may include ...glutamate excitotoxicity and neuroinflammation. • Novel treatments can be grouped into rescue therapies or preventative options. • Future work will need to incorporate well-designed preclinical models.
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