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R.O. Weller

Bio: R.O. Weller is an academic researcher from Southampton General Hospital. The author has contributed to research in topics: Perivascular space & Interstitial fluid. The author has an hindex of 1, co-authored 1 publications receiving 245 citations.

Papers
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Journal ArticleDOI
TL;DR: A mathematical model is constructed in order to test the hypothesis that periv vascular drainage of interstitial fluid and solutes out of brain tissue is driven by pulsations of the blood vessel walls, and it is shown that successful drainage may depend upon some attachment of solutes to the lining of the perivascular space, although an alternative without this requirement is also postulated.

276 citations


Cited by
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Journal ArticleDOI
TL;DR: An anatomically distinct clearing system in the brain that serves a lymphatic-like function is described and may have relevance for understanding or treating neurodegenerative diseases that involve the mis-accumulation of soluble proteins, such as amyloid β in Alzheimer's disease.
Abstract: Because it lacks a lymphatic circulation, the brain must clear extracellular proteins by an alternative mechanism. The cerebrospinal fluid (CSF) functions as a sink for brain extracellular solutes, but it is not clear how solutes from the brain interstitium move from the parenchyma to the CSF. We demonstrate that a substantial portion of subarachnoid CSF cycles through the brain interstitial space. On the basis of in vivo two-photon imaging of small fluorescent tracers, we showed that CSF enters the parenchyma along paravascular spaces that surround penetrating arteries and that brain interstitial fluid is cleared along paravenous drainage pathways. Animals lacking the water channel aquaporin-4 (AQP4) in astrocytes exhibit slowed CSF influx through this system and a ~70% reduction in interstitial solute clearance, suggesting that the bulk fluid flow between these anatomical influx and efflux routes is supported by astrocytic water transport. Fluorescent-tagged amyloid β, a peptide thought to be pathogenic in Alzheimer's disease, was transported along this route, and deletion of the Aqp4 gene suppressed the clearance of soluble amyloid β, suggesting that this pathway may remove amyloid β from the central nervous system. Clearance through paravenous flow may also regulate extracellular levels of proteins involved with neurodegenerative conditions, its impairment perhaps contributing to the mis-accumulation of soluble proteins.

3,368 citations

Journal ArticleDOI
16 Jul 2015-Nature
TL;DR: In searching for T-cell gateways into and out of the meninges, functional lymphatic vessels lining the dural sinuses are discovered, which may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.
Abstract: One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.

2,897 citations

Journal ArticleDOI
TL;DR: Potential mechanisms, detectable with neuroimaging, that might better fit the available evidence and provide testable hypotheses for future study are discussed.
Abstract: The term cerebral small vessel disease (SVD) describes a range of neuroimaging, pathological, and associated clinical features. Clinical features range from none, to discrete focal neurological symptoms (eg, stroke), to insidious global neurological dysfunction and dementia. The burden on public health is substantial. The pathogenesis of SVD is largely unknown. Although the pathological processes leading to the arteriolar disease are associated with vascular risk factors and are believed to result from an intrinsic cerebral arteriolar occlusive disease, little is known about how these processes result in brain disease, how SVD lesions contribute to neurological or cognitive symptoms, and the association with risk factors. Pathology often shows end-stage disease, which makes identification of the earliest stages difficult. Neuroimaging provides considerable insights; although the small vessels are not easily seen themselves, the effects of their malfunction on the brain can be tracked with detailed brain imaging. We discuss potential mechanisms, detectable with neuroimaging, that might better fit the available evidence and provide testable hypotheses for future study.

1,204 citations

Journal ArticleDOI
TL;DR: The clearance systems of the brain as they relate to proteins implicated in AD pathology are described, with the main focus on Aβ.
Abstract: Accumulation of toxic protein aggregates-amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles-is the pathological hallmark of Alzheimer disease (AD). Aβ accumulation has been hypothesized to result from an imbalance between Aβ production and clearance; indeed, Aβ clearance seems to be impaired in both early and late forms of AD. To develop efficient strategies to slow down or halt AD, it is critical to understand how Aβ is cleared from the brain. Extracellular Aβ deposits can be removed from the brain by various clearance systems, most importantly, transport across the blood-brain barrier. Findings from the past few years suggest that astroglial-mediated interstitial fluid (ISF) bulk flow, known as the glymphatic system, might contribute to a larger portion of extracellular Aβ (eAβ) clearance than previously thought. The meningeal lymphatic vessels, discovered in 2015, might provide another clearance route. Because these clearance systems act together to drive eAβ from the brain, any alteration to their function could contribute to AD. An understanding of Aβ clearance might provide strategies to reduce excess Aβ deposits and delay, or even prevent, disease onset. In this Review, we describe the clearance systems of the brain as they relate to proteins implicated in AD pathology, with the main focus on Aβ.

1,047 citations

Journal ArticleDOI
TL;DR: This review focuses on the current understanding of the mechanisms underlying intranasal delivery to the central nervous system involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system.

968 citations