New Study: The Immune System Link To Alzheimer’s

The human brain is often described as the most complex organ in the human body, its functioning and features still relatively unmapped in comparison to other parts of ourselves. But it still came as a surprise when researchers discovered a new part: and the implications are huge.

A group of researchers from the University of Virginia in Charlottesville in the US have discovered previously unknown and undocumented lymphatic vessels in the brain. The finding has enormous and far-reaching implications for the medical world, in particular those concerned with the study and treatment of neurological diseases like Alzheimer’s.

The Immune System/Alzheimer’s Study

Alzheimer’s disease

Lymphatic vessels (known as the lymph system) are the pathway through which our bodies’ immune cells move as they fight infections and diseases.

For a while it has been suspected that there is a link between the immune system and a host of neurological disorders, including Alzheimer’s and depression, but researchers were certain that there were no lymph vessels in the brain.

The findings of the Center for Brain Immunology and Glia at the University of Virginia in Charlottesville have immense significance for our understanding of the brain-body link.

Says Professor Jonathan Kipnis, Professor of Neuroscience and Director at the Center for Brain Immunology and Glia (BIG), “the immune link with so many neurological disorders is now obvious.”

 

Professor Jonathan Kipnis

“If the immune system is involved with those disorders, then the communication between the brain and the immune system is mediated by these vessels. We believe that they probably will be found to play a major role in most, if not all, neurological conditions where the immune system is involved.”

The Reaction To The Study

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Not surprisingly, when the discovery was published in the prestigious journal Nature, it warranted excitement and surprise among the research community.

Initially, Kipnis revealed in an interview following the publishing of the results, that he did not believe the findings.

“I really did not believe there are structures in the body that we are not aware of. I thought the body was mapped. I thought that these discoveries ended somewhere around the middle of the last century. But apparently they have not.”

“If you open today’s textbooks, it says that the central nervous system is an immune-privileged site and it has no lymphatic vessels,” he continued. “I think this immune-privileged site has lymphatic vessels.”

“We need to rewrite all the anatomy textbooks,” he concluded.

And we certainly do: not only do we having mounting evidence of the linking between the immune system and the brain, but evidence of the mechanism through which it works.

The discovery was made by a post-doctoral fellow in Kipnis’ lab, Dr. Antoine Louveau. Louveau developed a technique for mounting entire meninges (membranes in the brain) onto a single slide that could be viewed through a microscope.

Antoine Louveau
Dr. Antoine Louveau

The lymph vessels were found to be quite obviously located, “hiding in plain sight” as it were, between blood vessels in the sinus cavity. The newly discovered “central nervous system lymphatic system vessels” seem to follow one of these major blood vessels the sinuses, an area which is difficult to image.

The presence of these vessels explains why Alzheimer’s patients have accumulations of large protein plaques in the brain. Kipnis and his team believe that this “missing link” between the brain and the immune system could explain why some diseases like Alzheimer’s cause such plaque build-up in the brain: the plaque could result from the meningeal lymphatic vessels not efficiently removing build-up before it reaches the brain.

This plaque build-up is hypothesized to play a role in the cell death and tissue loss in the brain associated with Alzheimer’s.

But the discovery could herald exciting avenues for research into previously obscure links in neurological diseases other than Alzheimer’s: according to Kipnis the finding could completely change the way the neuro-immune interaction is thought about and studied.

“We believe that for every neurological disease that has an immune component to it, these vessels may play a major role,” Kipnis said. “Hard to imagine that these vessels would not be involved in a [neurological] disease with an immune component.”