How is tissue donation helping us to solve the MND puzzle?

Each year, the MND Association dedicates the month of June to raising MND awareness. This year, we focus on the eyes – in most people with MND the only part of their body they can still move and the only way left for them to communicate. Alongside the Association-wide campaign, the Research Development team selected six most-enquired about topics, which we will address through six dedicated blogs.

Last year, I wrote about our trip to a brain bank. Here, we learned about how people can arrange to donate their tissue (brain and spinal cord) to tissue banks after they die, and how it is stored and used in MND research all around the UK.

What you might be asking is: what can tissue actually tell us about MND, and how will this help us find new treatments?

To find new drugs that can beat this disease we first need to understand what is going on in the brain, which is very difficult to study in living people. This is why post-mortem tissue from people with MND is an invaluable resource. Below are four reasons why tissue donation is so important. Continue reading

The role of the protein TDP-43 in MND due to C9orf72 mutations

Mistakes in the C9orf72 gene are the most common cause of inherited MND, and can be linked to about 40% of all cases. Now that we know that damage to the C9orf72 gene causes MND the next step is to understand how this mutation causes the motor neurones to die. In particular Dr Jakub Scaber is looking at how another cause of MND – the formation of clumps of protein called TDP-43 are linked to changes to C9orf72. (You can read more about TDP-43 in the post about Dr Mitchell’s project yesterday).

Jakub Scaber

Dr Jakub Scaber, University of Oxford

Dr Jakub Scaber is a MND Association/ MRC Lady Edith Wolfson Clinical Research Fellow at the University of Oxford, he is studying how mistakes in the C9orf72 gene and TDP-43 protein cause MND (our grant reference: 945-795).

These fellowships are jointly funded by the Association and the Medical Research Council (MRC). They support clinicians (practising doctors) wishing to pursue scientific research and aim to strengthen the links between laboratory and clinic. Our financial commitment to these fellowships varies between £86,000 and £280,000 for up to five years. For this project the total cost of the grant is £173,697 and the MND Association contributes £86,848 with the MRC paying the rest of the money. Continue reading

The 11th Annual ENCALS meeting highlights how TDP-43 spreads in MND

The European Network for a cure of ALS (ENCALS) held its 11th Annual meeting in Sheffield from 31 May to the 2 June. The weekend was full of glorious British sunshine and more than 200 international scientists and clinicians were also able to enjoy a range of incredibly interesting talks about the latest developments in MND research.

A particular talk caught my attention on the first day by Dr Johannes Brettschneider from the University of Ulm in Germany. Dr Brettschneider explained how his research had shown the stages and spread of the protein TDP-43 in ALS (the commonest form of MND).

Dr Brian Dickie, Director of Research Development, said: “The key to defeating MND lies in fostering strong collaborations between neurologists, healthcare professionals, research scientists, early career investigators and students in the field of MND and the 11th Annual ENCALS meeting in Sheffield provided that opportunity. The MND Association was proud to support this event.”

‘Special’ staining

At the end of an afternoon of talks on the MND- causing genes C9orf72, FUS and SOD1, Dr Brettschneider engrossed over 200 delegates with his talk on the TDP-43 protein and how it spreads in ALS.

Although TDP-43 genetic mistakes are a rare cause of MND, scientists are especially interested in the TDP-43 protein because in the vast majority of cases of MND (irrespective of whether it was caused by an inherited genetic mistake), TDP-43 protein forms pathological clumps inside motor neurons.

The study (which is a collaboration between Dr. John Trojanowski and Dr. Virginia Lee from the Penn University Center of Neurodegenerative Disease Research in Philadelphia, America and the group of Dr. Heiko Braak in Ulm) used a technique known as ‘immunohistochemistry’.  This technique involves taking tissue samples of the brain and spinal cord from people who have died from ALS. The researchers would then make extremely thin slices of the tissue, which could then be stained using a ‘special stain’ and viewed under a microscope.

The stain used by Dr Brettschneider only ‘stained’ the TDP-43 protein in the samples, meaning that he could see the amount of TDP-43 in different areas of the brain and spinal cord.

Using the clinical information and TDP-43 staining this would allow Dr Brettschneider to stage the disease.

Image kindly provided by Dr Robin Highley, SITraN: (top left) a motor neurone with a skein-like neuronal cytoplasmic inclusion, next to a normal motor neurone (bottom left) on TDP-43 immunohistochemistry.

Image kindly provided by Dr Robin Highley, SITraN: (top left) a motor neurone with a skein-like neuronal cytoplasmic inclusion, next to a normal motor neurone (bottom left) on TDP-43 immunohistochemistry.

Axonal ‘telephone wires’ do more than just talking

Dr Brettschneider showed that TDP-43 increased in different areas of the brain and spinal cord during different stages of the disease. Amazingly, he also showed how ALS (characterized by clumps of TDP-43) spreads from one are of the body to another.

A motor neurone consists of three parts; the cell body, axon and nerve ending. The cell body contains the nucleus, or the control centre of the cell. When a message travels from the brain the cell body sends the message down the axon. Like telephone wires, the axon carries the message to the muscle, where the nerve endings cause the muscle to move.

However, in ALS it seems that these ‘telephone wires’ do more than just carry a message. The protein TDP-43 forms ‘clumps’ in the motor neurones and it seems that these clumps use the axon to travel from one motor neurone to the next (possibly explaining why someone get’s weakness in their arm and then their hand).

Another key finding was that TDP-43 clumps develop in the front part of the brain (prefrontal cortex), which is responsible for personality and may explain the development of cognitive symptoms.

Dr Brettschneider explained the importance of this research While spreading of disease-related proteins has been described for other neurodegenerative diseases like Alzheimer’s disease or Parkinson’s disease, this had not been previously shown in ALS. Now, we can show evidence that supports a spreading of the major disease protein TDP-43 in ALS across specific regions of the brain and spinal cord with ongoing disease.

 If these findings can be confirmed (for example in cell culture or mouse model studies) then this could lead to the design of new treatments specifically aiming to impair the spread of TDP-43 protein clumps.

Dr Johannes Brettschneider from the University of Ulm in Germany at ENCALS

Dr Johannes Brettschneider from the University of Ulm in Germany at ENCALS

Furthermore, we believe that our findings offer a better understanding of disease progression in ALS.  Our data implies that TDP-43 spreads throughout the prefrontal cortex with ongoing disease, thereby lending support to the idea that all ALS patients could eventually develop “frontal type” cognitive deficits.”

The future

Dr Brettschneider commented why this research is important to people living with MND explaining that “If these stages can be reproduced in patients with ALS they could offer a new way to assess disease progression and response to new treatments. We hope that our study provides the essential groundwork for strategies designed to prevent pTDP-43 spread.”

This research is only the beginning and more work is needed, Dr Brettschneider also explained what he hoped to do next with these exciting results. “There were restrictions in time and availability of the tissue samples during this study, so we were unable to determine how and where exactly ALS begins in the very early stage of the disease. Therefore, an important next step in our work would be to analyze very early cases with ALS to look at TDP -43 spread as this offers the most promising window for therapeutic intervention.”

Reference

Brettschneider J, Del Tredici K, Toledo JB, Robinson JL, Irwin DJ, Grossman M, Suh E, Van Deerlin VM, Wood EM, Baek Y, Kwong L, Lee EB, Elman L, McCluskey L, Fang L, Feldengut S, Ludolph AC, Lee VM, Braak H, Trojanowski JQ. Stages of pTDP-43 pathology in amyotrophic lateral sclerosis. Ann Neurol. 2013 May 20. doi: 10.1002/ana.23937. [Epub ahead of print]

Mediating the delicate balance between protection and damage

The Opening Session theme on how the disease progresses within the Central Nervous System (CNS) continued with the presentation by Prof Stan Appel from Baylor College of Medicine, Huston on neuroinflammation.

Examination of post-mortem brain and spinal cords from people with MND shows clear evidence of inflammation (although Prof Appel was quick to point out that this is not the same as occurs in ‘primary’ inflammatory conditions such as multiple sclerosis). Similar patterns are seen in human MND spinal cord and in SOD1 mice, suggesting that at least for this aspect of the disease, SOD1 mice may be a good model of human MND.

He went on to explain how migroglia, the ‘innate’ immune cells of the CNS, help mediate a delicate balance between protection and damage. The speed of progression in MND appears to be dictated by this balance.

Prof Appel showed that SOD1 mice exhibit two phases of disease: an early slow phase, where the microglia release a series of protective factors, and a rapid secondary progressive phase where levels of these protective markers fall and are replaced by a rise in ‘pro-inflammatory’ toxic factors. Of course, strains of lab mice are so inbred that they are genetically very similar and develop the disease in a uniform manner. Humans on the other hand are very different, as is the way the disease progresses between one individual and the next, so the two stages of disease are not easy to demonstrate in MND patients. However, by examining the inflammatory factors present in patients with very rapid progression against those with slower progression, he was able to show that the factors associated with the second ‘rapid progression’ phase in mice were also present in the rapidly progressing patients. He suggested that this may assist clinicians in predicting how the disease is likely to progress in patients at an early stage in the disease.

It is relatively easy in cell culture studies to tilt this balance from protective to toxic, but could the balance be tilted the other way in patients, as a therapeutic strategy? Certainly, in response to a question from the floor, he suggested that greater attempts should be made in this direction, commenting, “The whole issue of immunosuppressant drugs in MND needs to be re-opened. But – you can’t just take down all immune responses in an uncontrolled way. You need drugs that are much more selective”.

Read our official day one symposium press release on our website.