The Science of Celiac Disease

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Show Me the Science with Luke O'Neill 12 min 2 speakers 8 chapters transcribed 1 day ago

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What is celiac disease and why is it considered both an immune and autoimmune disorder?

Pat Kenny 0:00

Show Me The Science with Professor Luke O'Neill, a Newstalk original podcast.

Luke O'Neill 0:08

Hello, Luke O'Neill here and welcome to Show Me The Science, my weekly podcast. Now, this week a request has come in from Monica, Monica Nolan. And Monica said, well, I do the science of celiac disease. And again, it's a common enough topic, actually, because lots of people in Ireland have celiac. I often meet people. And they asked me to go into it. So I'm glad Monica's recommended this one. And it's up my street because this is very much an immune disease. And it's intriguing if you're an immunologist because it's an immune disease against wheat and barley, but also it's an autoimmune disease at the same time. You develop a reaction to a protein in your own body as well. So it's like a double whammy, I suppose.

Luke O'Neill 0:46

You overreact to something in your diet and then you develop a real autoimmune disease. So people work on it because if we understand more about it, who knows, we may discover other aspects of autoimmune diseases like rheumatoid arthritis, for instance, because... There's overlap there with the autoimmune part of celiac and with rheumatoid. Now, it's been studied for a good while, actually, and Ireland has had a big focus on this. My dear old pals, Con Ferry, Clino Farrelly, they had worked on celiac up in St. James's Hospital because it's quite common in Ireland. And that tells us something. There's a bit of genetics behind this as well. So it's quite a common thing for Irish scientists to be working on.

Luke O'Neill 1:24

And there's been great progress.

How do genetics and HLA‑DQ2/DQ8 increase the risk of developing celiac disease?

Luke O'Neill 1:26

And in fact, towards the end, they'll tell you about new therapies that are coming that will give people great hope. Now, it's caused by a protein in wheat, barley and rye. They're the three main offending compounds. crops that contain this protein. The protein is called gliadin and it's in a thing called gluten. So gluten is a substance in those plants but it has a protein called gliadin and you're overreacting to gluten and in particular you're overreacting to a protein called gliadin. in the food stuff that you're eating and then as a result you get an immune reaction to the gliadin in your intestine mainly in the small intestine the immune system goes crazy against this and all these immune factors are made and you get diarrhea bloating you can lose weight you'll feel very tired because of the immune system kicking off and sometimes there's an iron deficiency because you can't absorb food properly because the intestine is damaged

Luke O'Neill 2:17

by the immune system. People are inclined to be slightly shorter in stature as well, overall, if they have in their lives. And then mouth ulcers can feature and dermatitis, skin involvement. And all these are caused by the immune system attacking the gliadin in the diet and going off kilter and then driving this big immune reaction, which eventually damages your own body. And of course, as I often say, the immune system lies at the heart of so many diseases. It's got powerful weapons to fight infection. If they turn on your own body, you begin to see all these symptoms. And in particular, because it's in food, you see these symptoms in the gut and especially in the small intestine. Now, that was discovered, oh, a good few years ago.

Luke O'Neill 2:55

But then in the 90s, a big breakthrough happened, which was that it becomes autoimmune. That was kind of known already because the immune system was still firing. even when you don't have the gluten in your diet in some people. And what's happening here is one of your own proteins, you begin to react to that as well. And this is a protein called transglutaminase. There's a mouthful for you, TG for short.

What are the common symptoms and health impacts of untreated celiac disease?

Luke O'Neill 3:17

What is transglutaminase? It's an enzyme. It locks onto the gliadin, actually. So it's binding onto the protein that's coming from the wheat. And it has a biochemical reaction called translutamination. It modifies the gliadin. And now that really drives the immune system crazy. So you're modifying a protein in the diet to become even more what's called immunogenic. And that translutamination reaction makes bits of gliadin, little peptides actually from gliadin,