Unraveling the link between brain, lymphatic system

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RitaA
Posts: 2768
Joined: Thu 1 Jul 2010 8:33

Unraveling the link between brain, lymphatic system

Postby RitaA » Tue 16 Jun 2015 5:07

http://www.sciencedaily.com/releases/20 ... 094258.htm

Unraveling the link between brain, lymphatic system

Date: June 15, 2015

Source: University of Helsinki

Summary: A surprising finding that challenges current anatomy and histology textbook knowledge has been released by researchers: Lymphatic vessels are found in the central nervous system where they were not known to exist. Researchers discovered the meningeal linings of brain have a lymphatic vessel network that has direct connections to the systemic lymphatic network elsewhere in the body.

In a study published in The Journal of Experimental Medicine, researchers working at the Wihuri Research Institute and the University of Helsinki report a surprising finding that challenges current anatomy and histology textbook knowledge: Lymphatic vessels are found in the central nervous system where they were not known to exist. Aleksanteri Aspelund and colleagues discovered the meningeal linings of brain have a lymphatic vessel network that has direct connections to the systemic lymphatic network elsewhere in the body.


Lymphatic circulation forms a network that covers almost the whole body and is especially important to the tissue clearance of fluids and macromolecules as well as for immune defense mechanisms. Until now, the central nervous system has been considered an immune-privileged organ devoid of lymphatic vasculature.

- We have recently discovered that in the eye, which is another immune-privileged organ previously considered to lack lymphatic circulation, there exists a lymphatic-like vessel that is important for the regulation of eye pressure. This led me to reinvestigate the brain in this regard, says Aleksanteri Aspelund, who is working in Academy Professor Kari Alitalo's research group.

- We were stunned to find such an extensive network in connection to the brain. This incredible finding completely changes our understanding of how to brain is cleared of excess fluid and gives a chance to look at brain diseases from a completely new angle, he continues.

The researchers performed a thorough job in characterizing the structure and function of these previously unknown vessels. They showed that these meningeal lymphatic vessels drain out of the skull alongside arteries, veins and cranial nerves. These vessels show all molecular hallmarks of the lymphatic vessels and function as a direct clearance routes for the brain and cerebrospinal fluid macromolecules out of the skull and into the deep cervical lymph nodes.

How did the lymphatic vessels manage to escape notice until now?

- This is no wonder, says medical student Salli Antila, who has also been working with the project.

Lymphatic vessels are collapsed structures between the meninges, and if one does not know how to look, they cannot be found. Although we had already found the vessels, it took some time to develop good imaging methods to visualize these vessels.

The discovery has raised several new questions concerning some fundamental brain functions and the mechanisms of brain diseases. Researchers find it highly possible that lymphatic clearance of the brain proves to be important in neuro-immunological diseases as well as in diseases characterized by the pathological accumulation of misfolded proteins or fluid into the brain parenchyma, for example in Alzheimer's disease, which affects tens of millions of people worldwide.

Story Source:

The above post is reprinted from materials provided by University of Helsinki. Note: Materials may be edited for content and length.

Journal Reference:

1.Aleksanteri Aspelund, Salli Antila, Steven Proulx, Tine Karlsen, Sinem Karaman, Michael Detmar, Helge Wiig and Kari Alitalo. A dural lymphatic vascular system that drains brain interstitial fluid and macromolecules. The Journal of Experimental Medicine, June 2015 DOI: 10.1084/jem.20142290

RitaA
Posts: 2768
Joined: Thu 1 Jul 2010 8:33

Re: Unraveling the link between brain, lymphatic system

Postby RitaA » Wed 24 Jun 2015 7:13

http://jem.rupress.org/content/early/20 ... m.20142290

Published June 15, 2015
The Rockefeller University Press, doi: 10.1084/jem.20142290
© 2015 Aspelund et al.

Brief Definitive Report

A dural lymphatic vascular system that drains brain interstitial fluid and macromolecules

Aleksanteri Aspelund,1,2
Salli Antila,1,2
Steven T. Proulx,3
Tine Veronica Karlsen,4
Sinem Karaman,3
Michael Detmar,3
Helge Wiig,4 and
Kari Alitalo1,2

Author Affiliations

1 Wihuri Research Institute and
2 Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, 00014 Helsinki, Finland
3 Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH Zurich), CH-8093 Zurich, Switzerland
4 Department of Biomedicine, University of Bergen, 5009 Bergen, Norway

ABSTRACT

The central nervous system (CNS) is considered an organ devoid of lymphatic vasculature. Yet, part of the cerebrospinal fluid (CSF) drains into the cervical lymph nodes (LNs). The mechanism of CSF entry into the LNs has been unclear. Here we report the surprising finding of a lymphatic vessel network in the dura mater of the mouse brain. We show that dural lymphatic vessels absorb CSF from the adjacent subarachnoid space and brain interstitial fluid (ISF) via the glymphatic system. Dural lymphatic vessels transport fluid into deep cervical LNs (dcLNs) via foramina at the base of the skull. In a transgenic mouse model expressing a VEGF-C/D trap and displaying complete aplasia of the dural lymphatic vessels, macromolecule clearance from the brain was attenuated and transport from the subarachnoid space into dcLNs was abrogated. Surprisingly, brain ISF pressure and water content were unaffected. Overall, these findings indicate that the mechanism of CSF flow into the dcLNs is directly via an adjacent dural lymphatic network, which may be important for the clearance of macromolecules from the brain. Importantly, these results call for a reexamination of the role of the lymphatic system in CNS physiology and disease.

Submitted: 8 December 2014
Accepted: 4 June 2015

This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).

velvetmagnetta
Posts: 469
Joined: Sun 23 Feb 2014 22:47

Re: Unraveling the link between brain, lymphatic system

Postby velvetmagnetta » Sat 27 Jun 2015 16:14

Thank you for posting this, Rita!

It says that the article will be available after 6 months via a Creatve Commons license. Does anyone know if this means anyone can read it for free? Does anyone know where to get the full article now?

If anybody catches any other articles on this subject, please post a link here! Thanks!


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