Narcolepsy and flu

Kat - And now it's time to take a look at the latest genetics news with science writer Nell Barrie. So, the first story that I wanted to talk about was one about narcolepsy and flu.  So, an interesting connection between randomly falling asleep, which is the disease narcolepsy, and the flu virus.  What's this about?

Nell -  Well, it seems that the link here is to do with the immune system which as always is very fascinating and very complicated.  What these researchers have found, it's these people at Stanford University School of Medicine in the US and it's published in Science Translational Medicine.  They've actually discovered that narcolepsy seems to be an autoimmune disease.  So, it's being caused by the immune system going a little bit haywire and attacking cells in the body that it shouldn't be targeting, which is really fascinating.

Kat -  It's very interesting because this affects about 1 in 3,000 people and the cause of it has been a complete mystery.  It just causes people to randomly fall asleep, they have a lot of muscle weakness, a lot of problems.  So, what's the connection then with flu and the immune system?  What's going on here?

Nell -  Well, it seems that what the immune system is doing in people with narcolepsy is it's actually latching on to a molecule that's found in some types of brain cells, some types of neuron.  The reason it's doing that is because it's found a similarity between this particular molecule and another one that's found in a type of flu called H1N1.  So, it's an accidental kind a bit of mimicry, almost, that's going on.

Kat -  So, the immune system thinks, "That's a bit of flu" and starts destroying whatever it is.  But in fact, it's these brain cells that are involved in wakefulness.

Nell -  Exactly.  So, the immune system is going wrong.  It's trying to do its job.  It's trying to track down harmful pathogens in the body and destroy them which it works very well at doing that.  But clearly, in this particular instance, it's being a little bit too clever.  It's very specific.  It's found this bit of a protein that just randomly happens to match this part of the flu protein.  It's also in these brain cells and that means that immune system is actually attacking the brain cells and completely getting rid of them.

Kat -  This sounds like very interesting coincidence, but is it actually relevant to people?  Do we know that?

Nell -  Well, it looks like it could be interesting because it could mean that researchers can find a better way to help tackle the disease.  They may even be able to find a way to test for narcolepsy using a blood test, which would be really valuable because as you were saying, we haven't known up until now what the cause is.  So, it's very, very difficult to figure out who might have it, why they've got it, all these different types of things that we need to find out if we're going to be able to help people a bit better.

Kat -  I thought it was really interesting that they highlighted that in 2010, there was a study in China that showed there was an increase in narcolepsy in a certain group of children living in areas where there was this big H1N1 flu pandemic.  It's certainly very interesting link that needs more research 

Nell -  Yeah, it's really interesting.  There's also some evidence from Scandinavia that when an H1N1 vaccine was used there, it actually led to a small increase in narcolepsy.  It seems to be because they were training the immune system to react to H1N1 and it was also causing it to react to these cells in the brain at the same time.  So, interesting to see how that can work and how the immune system can have these different effects across the body. 

Kat -  And certainly, informs the development of flu vaccines as well.  It would be very interesting to see if these kind of accidental immune responses are behind other brain disorders.  Things like schizophrenia which has been shown to have a link with autoimmunity.

Nell -  Yeah, absolutely.  I mean, it just seems like more and more, the immune system has a part to play in many different kinds of illness, many types of reactions to different diseases.  I always think this type of stuff is really fascinating.