Neuroinflammation vs Neurodegeneration

I’ve been reading an interesting 2016 review article called Cytokine networks in neuroinflammation.*

Click here for the abstract.

Some of the differences between neuroinflammation and neurodegeneration are beautifully explained. Both diagrams come from this article.

Background

Cells in our body and brain produce cytokines, small proteins that are powerful and wilful little beasties. They provide a very effective means of cell communication, and can “orchestrate complex multicellular behaviour”.

Over 300 different cytokines have been identified, but some of them have shown that in one situation they will behave in one way, but in another situation the same cytokine will do the complete opposite.

Cytokines are part of the body and brain’s response to something going wrong. But cytokines themselves can go haywire (called cytokine network dysfunction or dysregulation) and set up and maintain cascades of activity that can ultimately cause harm to the tissue.

Normal brain

In a brain without disease, the immune (white blood) cells stay inside the blood vessel and don’t cross over the blood brain barrier. Meanwhile the brain has its own immune management system, with various cell types actively protecting the brain. These cells include microglia and astrocytes.

In a healthy brain, cytokines are produced by brain cells, they are all best friends and behave themselves with due decorum.

Neurodegeneration

This diagram shows the brain tissue on the right and on the left is the blood vessel with blood cells inside. The comment “limited contribution by blood-borne leukocytes” refers to the white cells keeping out of the brain.

Neurodegenerative diseases include Alzheimer’s, Parkinson’s and ALS (Stephen Hawking’s disease). In these diseases, the immune (white blood) cells do what they are supposed to do, and stay inside the blood vessels.

However, these diseases have their own mechanisms that act on the brain, and not in a good way (more on that another time).

When these changes start, cytokines produced in the brain start to take notice. They ramp up their numbers, roll up their shirtsleeves and expect to sort out the problem pretty quickly. The problem isn’t so easily sorted, though, and as the cytokines keep battling on, their prolonged activity can itself be a danger to the brain. They go haywire, creating cytokine network dysfunction or dysregulation.

Over time, the cytokine dysfunction seems to knock out the cells and disrupt the normal brain function.

Neuroinflammation

This diagram shows the blood-borne cells, the monocytes and T cells inside the brain tissue.

In Neuroinflammatory diseases, such as Multiple Sclerosis, Meningitis and Encephalitis, the white blood cells from the blood stream break through the blood-brain barrier, and they start spreading their cytokines into the brain. The cytokines produced by these external cells throw the equivalent of petrol onto a brain fire.

The brain is besieged and not happy.

Why does this matter?

Fair question.

1. It reminds us that brain diseases are complicated, and that every time researchers identify some new part of a disease process, new layers of complexities are revealed.

2. It shows us that while different diseases may have different origins, they stimulate similar responses. For example, the initial brain change in Alzheimer’s and Parkinson’s are quite different, but the brain reaction with the fighting cytokines is similar.

3. Research has shown that red and near infrared light has a direct and positive effect on the activities of some cytokines, increasing the calming cytokines and dowsing the cytokines that promote inflammation.

4. Red and near infrared light seems to reduce cytokine dysregulation, and thus protect brain cells and brain cell function.

Thinking about Alzheimer’s, the drugs developed to treat it have not shown much effectiveness. In theory, and in early research evidence, exploring the use of red and near infrared lights might be a better way to spend medical research dollars.

* Becher, Burkhard & Spath, Sabine & Goverman, Joan. (2016). Cytokine networks in neuroinflammation. Nature Reviews Immunology. 17. 10.1038/nri.2016.123.

Author: RedlightsontheBrain

Redlightsonthebrain is written by Catherine, a retired doctor on behalf of Light Ahead Inc, a Tasmanian-based not-for-profit organisation. Light Ahead Inc aims to help people to learn about neurogenerative diseases and the practical, safe and scientifically-based things that may be able to help. Part of this is to provide low-cost access to red light devices, hence the DIY instructions on this blog.