scholarly journals The Glymphatic System (En)during Inflammation

2021 ◽  
Vol 22 (14) ◽  
pp. 7491
Author(s):  
Frida Lind-Holm Mogensen ◽  
Christine Delle ◽  
Maiken Nedergaard
Keyword(s):  
Fluid Transport ◽  
Neurological Diseases ◽  
Lymphatic Vessels ◽  
Perivascular Spaces ◽  
Fluid Exchange ◽  
Glymphatic System ◽  
The Central Nervous System ◽  
The Brain ◽  
Privileged Site ◽  
Vascular Compartment

The glymphatic system is a fluid-transport system that accesses all regions of the brain. It facilitates the exchange of cerebrospinal fluid and interstitial fluid and clears waste from the metabolically active brain. Astrocytic endfeet and their dense expression of the aquaporin-4 water channels promote fluid exchange between the perivascular spaces and the neuropil. Cerebrospinal and interstitial fluids are together transported back to the vascular compartment by meningeal and cervical lymphatic vessels. Multiple lines of work show that neurological diseases in general impair glymphatic fluid transport. Insofar as the glymphatic system plays a pseudo-lymphatic role in the central nervous system, it is poised to play a role in neuroinflammation. In this review, we discuss how the association of the glymphatic system with the meningeal lymphatic vessel calls for a renewal of established concepts on the CNS as an immune-privileged site. We also discuss potential approaches to target the glymphatic system to combat neuroinflammation.

scholarly journals Brain lymphatic drainage system – visualization opportunities and current state of the art

2020 ◽  
Vol 9 (3) ◽  
pp. 81-89
Author(s):  
G. S. Yankova ◽  
O. B. Bogomyakova
Keyword(s):  
Neurodegenerative Diseases ◽  
Immune Surveillance ◽  
Lymphatic Vessels ◽  
Drainage System ◽  
Lymphatic Drainage ◽  
Waste Products ◽  
Glymphatic System ◽  
Age Related ◽  
The Central Nervous System ◽  
The Brain

The lymphatic drainage system of the brain is assumed to consist of the lymphatic system and a network of meningeal lymphatic vessels. This system supports brain homeostasis, participates in immune surveillance and presents a new therapeutic target in the treatment of neurological disorders.The article analyzes and systematizes data on the brain lymphatic drainage system. The key components of this system are considered: recently described meningeal lymphatic vessels and their relationship with the glymphatic system, which provides perfusion of the central nervous system with cerebrospinal and interstitial fluids. The lymphatic drainage system helps to maintain water and ion balances of the interstitial fluid and to remove metabolic waste products, assists in reabsorption of macromolecules. Disorders in its work play a crucial role in age-related changes in the brain, the pathogenesis of neurovascular and neurodegenerative diseases, as well as injuries and brain tumors. The review also presents the results of human studies concerning the presence, anatomy and structure of meningeal lymphatic vessels and the glymphatic system. The discovery of the brain lymphatic drainage system has not only changed our understanding of cerebrospinal fluid circulation, but also contributed to understanding the pathology and mechanisms of neurodegenerative diseases.

Physiology and Clinical Relevance of Enlarged Perivascular Spaces in the Aging Brain

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000013077
Author(s):  
Corey W Bown ◽  
Roxana O Carare ◽  
Matthew S Schrag ◽  
Angela L Jefferson
Keyword(s):  
Fluid Transport ◽  
Small Vessel Disease ◽  
Treatment Strategies ◽  
Small Vessel ◽  
Aging Brain ◽  
Perivascular Spaces ◽  
Vessel Disease ◽  
Clinical Consequences ◽  
The Brain

Perivascular spaces (PVS) are fluid filled compartments that are part of the cerebral blood vessel wall and represent the conduit for fluid transport in and out of the brain. PVS are considered pathologic when sufficiently enlarged to be visible on magnetic resonance imaging. Recent studies have demonstrated that enlarged PVS (ePVS) may have clinical consequences related to cognition. Emerging literature points to arterial stiffening and abnormal protein aggregation in vessel walls as two possible mechanisms that drive ePVS formation. In this review, we describe the clinical consequences, anatomy, fluid dynamics, physiology, risk factors, and in vivo quantification methods of ePVS. Given competing views of PVS physiology, we detail the two most prominent theoretical views and review ePVS associations with other common small vessel disease markers. As ePVS are a marker of small vessel disease and ePVS burden is higher in Alzheimer’s disease, a comprehensive understanding about ePVS is essential in developing prevention and treatment strategies.

Neural glymphatic system: Clinical implications and potential importance of melatonin

2021 ◽  
Vol 4 (4) ◽  
pp. 551-565
Author(s):  
Ryan D Bitar ◽  
Jorge L Torres-Garza ◽  
Russel J Reiter ◽  
William T Phillips
Keyword(s):  
Lymph Nodes ◽  
Subarachnoid Space ◽  
Slow Wave Sleep ◽  
Lymphatic Vessels ◽  
Amyloid Β ◽  
Secretory Product ◽  
Cervical Lymph Nodes ◽  
Waste Products ◽  
Glymphatic System ◽  
The Brain

The central nervous system was thought to lack a lymphatic drainage until the recent discovery of the neural glymphatic system.  This highly specialized waste disposal network includes classical lymphatic vessels in the dura that absorb fluid and metabolic by-products and debris from the underlying cerebrospinal fluid (CSF) in the subarachnoid space. The subarachnoid space is continuous with the Virchow-Robin peri-arterial and peri-vascular spaces which surround the arteries and veins that penetrate into the neural tissue, respectively.  The dural lymphatic vessels exit the cranial vault via an anterior and a posterior route and eventually drain into the deep cervical lymph nodes. Aided by the presence of aquaporin 4 on the perivascular endfeet of astrocytes, nutrients and other molecules enter the brain from peri-arterial spaces and form interstitial fluid (ISF) that baths neurons and glia before being released into peri-venous spaces.  Melatonin, a pineal-derived secretory product which is in much higher concentration in the CSF than in the blood, is believed to follow this route and to clear waste products such as amyloid-β from the interstitial space. The clearance of amyloid-β reportedly occurs especially during slow wave sleep which happens concurrently with highest CSF levels of melatonin.  Experimentally, exogenously-administered melatonin defers amyloid-β buildup in the brain of animals and causes its accumulation in the cervical lymph nodes. Clinically, with increased age CSF melatonin levels decrease markedly, co-incident with neurodegeneration and dementia.  Collectively, these findings suggest a potential association between the loss of melatonin, decreased glymphatic drainage and neurocognitive decline in the elderly.

scholarly journals Glymphatic System in the Central Nervous System, a Novel Therapeutic Direction Against Brain Edema After Stroke

2021 ◽  
Vol 13 ◽  
Author(s):  
Xiangyue Zhou ◽  
Youwei Li ◽  
Cameron Lenahan ◽  
Yibo Ou ◽  
Minghuan Wang ◽  
...  
Keyword(s):  
Brain Edema ◽  
Brain Tissue ◽  
Molecular Mechanisms ◽  
Glymphatic System ◽  
System A ◽  
Function Recovery ◽  
The Central Nervous System ◽  
The Stability ◽  
The Brain

Stroke is the destruction of brain function and structure, and is caused by either cerebrovascular obstruction or rupture. It is a disease associated with high mortality and disability worldwide. Brain edema after stroke is an important factor affecting neurologic function recovery. The glymphatic system is a recently discovered cerebrospinal fluid (CSF) transport system. Through the perivascular space and aquaporin 4 (AQP4) on astrocytes, it promotes the exchange of CSF and interstitial fluid (ISF), clears brain metabolic waste, and maintains the stability of the internal environment within the brain. Excessive accumulation of fluid in the brain tissue causes cerebral edema, but the glymphatic system plays an important role in the process of both intake and removal of fluid within the brain. The changes in the glymphatic system after stroke may be an important contributor to brain edema. Understanding and targeting the molecular mechanisms and the role of the glymphatic system in the formation and regression of brain edema after stroke could promote the exclusion of fluids in the brain tissue and promote the recovery of neurological function in stroke patients. In this review, we will discuss the physiology of the glymphatic system, as well as the related mechanisms and therapeutic targets involved in the formation of brain edema after stroke, which could provide a new direction for research against brain edema after stroke.

scholarly journals Intranasal Delivery of Nanoformulations: A Potential Way of Treatment for Neurological Disorders

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1929 ◽  
Author(s):  
Salman Ul Islam ◽  
Adeeb Shehzad ◽  
Muhammad Bilal Ahmed ◽  
Young Sup Lee
Keyword(s):  
Drug Delivery ◽  
Neurological Disorders ◽  
Neurological Diseases ◽  
Nasal Delivery ◽  
Intranasal Route ◽  
Drug Molecules ◽  
Surface Enhanced ◽  
Effective Delivery ◽  
The Central Nervous System ◽  
The Brain

Although the global prevalence of neurological disorders such as Parkinson’s disease, Alzheimer’s disease, glioblastoma, epilepsy, and multiple sclerosis is steadily increasing, effective delivery of drug molecules in therapeutic quantities to the central nervous system (CNS) is still lacking. The blood brain barrier (BBB) is the major obstacle for the entry of drugs into the brain, as it comprises a tight layer of endothelial cells surrounded by astrocyte foot processes that limit drugs’ entry. In recent times, intranasal drug delivery has emerged as a reliable method to bypass the BBB and treat neurological diseases. The intranasal route for drug delivery to the brain with both solution and particulate formulations has been demonstrated repeatedly in preclinical models, including in human trials. The key features determining the efficacy of drug delivery via the intranasal route include delivery to the olfactory area of the nares, a longer retention time at the nasal mucosal surface, enhanced penetration of the drugs through the nasal epithelia, and reduced drug metabolism in the nasal cavity. This review describes important neurological disorders, challenges in drug delivery to the disordered CNS, and new nasal delivery techniques designed to overcome these challenges and facilitate more efficient and targeted drug delivery. The potential for treatment possibilities with intranasal transfer of drugs will increase with the development of more effective formulations and delivery devices.

scholarly journals Cerebrospinal fluid influx drives acute ischemic tissue swelling

Science ◽  
2020 ◽  
Vol 367 (6483) ◽  
pp. eaax7171 ◽  
Author(s):  
Humberto Mestre ◽  
Ting Du ◽  
Amanda M. Sweeney ◽  
Guojun Liu ◽  
Andrew J. Samson ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Treatment Options ◽  
Treatment Strategies ◽  
Perivascular Spaces ◽  
Fluid Accumulation ◽  
Multiphoton Imaging ◽  
Flow Channels ◽  
Ischemic Tissue ◽  
The Brain ◽  
Vascular Compartment

Stroke affects millions each year. Poststroke brain edema predicts the severity of eventual stroke damage, yet our concept of how edema develops is incomplete and treatment options remain limited. In early stages, fluid accumulation occurs owing to a net gain of ions, widely thought to enter from the vascular compartment. Here, we used magnetic resonance imaging, radiolabeled tracers, and multiphoton imaging in rodents to show instead that cerebrospinal fluid surrounding the brain enters the tissue within minutes of an ischemic insult along perivascular flow channels. This process was initiated by ischemic spreading depolarizations along with subsequent vasoconstriction, which in turn enlarged the perivascular spaces and doubled glymphatic inflow speeds. Thus, our understanding of poststroke edema needs to be revised, and these findings could provide a conceptual basis for development of alternative treatment strategies.

scholarly journals The glymphatic system and its role in cerebral homeostasis

2020 ◽  
Vol 129 (6) ◽  
pp. 1330-1340
Author(s):  
Helene Benveniste ◽  
Rena Elkin ◽  
Paul M. Heerdt ◽  
Sunil Koundal ◽  
Yuechuan Xue ◽  
...  
Keyword(s):  
Brain Parenchyma ◽  
Toxic Waste ◽  
Normal Brain ◽  
Fluid Exchange ◽  
Glymphatic System ◽  
The Past ◽  
System A ◽  
Waste Production ◽  
Lymphatic Vasculature ◽  
The Brain

The brain’s high bioenergetic state is paralleled by high metabolic waste production. Authentic lymphatic vasculature is lacking in brain parenchyma. Cerebrospinal fluid (CSF) flow has long been thought to facilitate central nervous system detoxification in place of lymphatics, but the exact processes involved in toxic waste clearance from the brain remain incompletely understood. Over the past 8 yr, novel data in animals and humans have begun to shed new light on these processes in the form of the “glymphatic system,” a brain-wide perivascular transit passageway dedicated to CSF transport and interstitial fluid exchange that facilitates metabolic waste drainage from the brain. Here we will discuss glymphatic system anatomy and methods to visualize and quantify glymphatic system (GS) transport in the brain and also discuss physiological drivers of its function in normal brain and in neurodegeneration.

scholarly journals The Glymphatic System: A Review

2018 ◽  
Vol 37 (03) ◽  
pp. 190-195 ◽  
Author(s):  
Louise Oliveira ◽  
Eberval Figueiredo ◽  
Carlos Peres
Keyword(s):  
Lymphatic Vessels ◽  
Normal Pressure ◽  
Therapeutic Interventions ◽  
Glymphatic System ◽  
Adult Body Mass ◽  
System A ◽  
Optimal Function ◽  
The Central Nervous System ◽  
Glymphatic Pathway ◽  
The One

AbstractThe brain represents ∼ 2% of the adult body mass; conversely, it is responsible for 20% to 25% of the glucose and 20% of the oxygen consumption, receiving 15% of the cardiac output. This substantial metabolic rate is associated with a significant production of biological debris, which is potentially toxic. Therefore, a complex and efficient clearance system is required to prevent the accumulation of byproducts and ensure optimal function. However, until today, there is little knowledge about this topic. The glymphatic system, also known as perivascular pathway, is a recently described glial-dependent network that is responsible for the clearance of metabolites from the central nervous system (CNS), playing a role equivalent to the one played by the lymphatic vessels present in other organs. Studies have demonstrated that the glymphatic pathway has a paramount role in protein homeostasis, and that the malfunction of this system may be related to the development of neurodegenerative disorders such as Alzheimer disease and normal pressure hydrocephalus. They also showed that body posture, exercise and the state of consciousness influence the glymphatic transport. In this context, the understanding of this clearance system could not only clarify the pathophysiology of several diseases, but also contribute to future therapeutic interventions. In the present article, we will evaluate the glymphatic pathway, focusing on the factors that regulate its flow, as well as on its role in CNS physiology and in disease initiation and progression, including dementia, hydrocephalus, glaucoma and traumatic brain injury. Ultimately, this review also aims to encourage further research on novel therapeutic targets.

scholarly journals Current Understanding of Central Nervous System Drainage Systems: Implications in the Context of Neurodegenerative Diseases

2020 ◽  
Vol 18 (11) ◽  
pp. 1054-1063 ◽  
Author(s):  
Vladimir N. Nikolenko ◽  
Marine V. Oganesyan ◽  
Angela D. Vovkogon ◽  
Arina T. Nikitina ◽  
Ekaterina A. Sozonova ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neurodegenerative Diseases ◽  
Lymphatic Vessels ◽  
Basal Area ◽  
Waste Products ◽  
Glymphatic System ◽  
The Central Nervous System ◽  
New Perspective ◽  
And Function

Until recently, it was thought that there were no lymphatic vessels in the central nervous system (CNS). Therefore, all metabolic processes were assumed to take place only in the circulation of the cerebrospinal fluid (CSF) and through the blood-brain barrier’s (BBB), which regulate ion transport and ensure the functioning of the CNS. However, recent findings yield a new perspective: There is an exchange of CSF with interstitial fluid (ISF), which is drained to the paravenous space and reaches lymphatic nodes at the end. This circulation is known as the glymphatic system. The glymphatic system is an extensive network of meningeal lymphatic vessels (MLV) in the basal area of the skull that provides another path for waste products from CNS to reach the bloodstream. MLV develop postnatally, initially appearing around the foramina in the basal part of the skull and the spinal cord, thereafter sprouting along the skull’s blood vessels and spinal nerves in various areas of the meninges. VEGF-C protein (vascular endothelial growth factor), expressed mainly by vascular smooth cells, plays an important role in the development of the MLV. The regenerative potential and plasticity of MLV and the novel discoveries related to CNS drainage offer potential for the treatment of neurodegenerative diseases such as dementia, hydrocephalus, stroke, multiple sclerosis, and Alzheimer disease (AD). Herein, we present an overview of the structure and function of the glymphatic system and MLV, and their potential involvement in the pathology and progression of neurodegenerative diseases.

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