What is celiac disease

- [Voiceover] The name celiac disease doesn't actually tell us much about what the disease does, but there's another name that I think is a little bit more informative. And that's gluten-sensitive enteropathy. Entero refers to small intestine and pathy refers to disease, so there's a disease of the small intestine that's caused by gluten. It's also important to note that celiac disease is an autoimmune disease, that is, the immune system is attacking the small intestine. We don't actually know why that's happening, but we do know that some people have a genetic predisposition towards developing the disease. We also know that people who have celiac disease are more likely to develop other autoimmune diseases as well, such as type 1 diabetes or thyroid disease, and we know that it's more common in people who have down syndrome. Now even though we don't exactly know why the immune system is attacking the small intestine, we can still kind of look at the pathophysiology and what's exactly going on in there. Now remember that gluten is composed of two different proteins. There's gliadin and there's glutenin. We'll mostly focus on gliadin. Now let's say you eat something that contains gluten. That gluten will eventually make its way into the small intestine, and here I kind of have a diagram of the different layers of the small intestine. Once it reaches this point, for some reason, your body will start to produce antibodies against the gliadin. This will then recruit all sorts of lymphocytes, or white blood cells, into your small intestine. Because you have a lot of lymphocytes and antibodies in your small intestine, we say that there is inflammation in there. So it's almost as if there's a war zone going on in your small intestine, and that war zone kind of causes damage to the wall of the small intestine. Now remember that the wall is responsible for absorbing food and water, so, the process of absorption will be disrupted. For example, you can't really absorb much water anymore. That water will just end up in your stools, in a condition simply known as diarrhea. Similarly, you can't absorb fats very well either, and that will manifest in your stools in a condition known as steatorrhea. And finally, you may be unable to absorb iron or vitamin B12. As a result, you may start to experience anemia. So these are some of the major symptoms associated with problems in absorption, but there's actually one more symptom that's not really associated with absorption. Let's say that here we have the body of someone who has celiac disease, and they've eaten something that contains gluten in it. All of a sudden, they may start to see these rashes and blisters forming on their abdomen and their arms. These rashes and these blisters are going to be extremely itchy. This is a condition known as dermatitis herpetiformis. It's not too common. It affects about 10% of people who have celiac disease, but, it's one of the many symptoms that doctors may look for when diagnosing the disease. Now, speaking of diagnosis, I want to talk a little bit more about how some doctors can determine if someone has celiac disease. First, what they'll do is they'll determine if you have a high probability or low probability of developing the disease. They'll determine this by looking at your family history, because remember that people have a genetic predisposition towards developing it. If they see a lot of family members having the disease, then they may order what's called a biopsy. A biopsy's when we collect a small sample of the tissue that we're interested in. After you collect that sample, you then look at it under a microscope to see if it looks healthy or not. The way we collect this tissue is through a procedure called an upper endoscopy. They basically take this camera that looks like a tube called an endoscope, and they put it through your mouth, down your esophagus, through your stomach, and then eventually, into your small intestine. Because it's a camera, the doctors can then actually see what's going on in the small intestine, and, they can collect that sample. Now, let's say that you may have a low probability instead. If, for example, you don't have a lot of family members who have celiac disease, or even any other autoimmune disease, you may not want to subject the patient to this really invasive procedure, so first, what we'll do is a few blood tests. We're mostly going to be looking for different antibodies that are characteristic of celiac disease, because remember, that this is an autoimmune disease. So there are five classes of antibodies, called IgA, IgD, IgE, IgG, and IgM. We're mostly going to look for antibodies that fall in the IgA category, and there are two different types. There's anti-tissue transglutaminase, and there's anti-endomysial. If these blood tests turn out positive, that is, you have these antibodies in your system, then there's a chance that you may have celiac disease, so then the doctor may go on to continue with a biopsy, just to confirm things. Now, let's take a look at that biopsy in a little bit more detail, so here we have two different pictures of the small intestine under the microscope. On the right, we have a healthy small intestine, and on the left, we have the small intestine of someone who has celiac disease. First, I want to highlight what's good about the healthy one. You'll notice that it has these finger-like protrusions called the villi. These guys are responsible for absorption in the small intestine. There are also these grooves between the villi known as crypts. In the disease sample, you'll notice that these villi are actually blunted. This is known as villous atrophy. In addition, those crypts are actually elongated so they're becoming a little bit bigger. And that's because all sorts of cells are dividing there, so we call this crypt hyperplasia, so it's kind of like the mountains of the villi are getting smaller, and the valleys of the crypts are getting deeper. Now, there's one more comparison picture that I want to show you as well. In this case, on the left, we have someone who is healthy, and on the right, we have someone who has celiac disease. Now, remember, that in celiac disease, you have a lot of inflammation in the small intestine. That means that you have a lot of lymphocytes in there. So it would be a good idea to actually look for these lymphocytes, so, you'll see these kind of blobs that are in the villi of the small intestine, right? And, the celiac disease tissue actually has a lot more of them. Now, these blobs are corresponding to the lymphocytes, and it's pretty clear in this picture that there are way more lymphocytes in the disease tissue than in the healthy. Now, these are really the main signs that we look for with regards to celiac disease, and if the tissue sample shows this, then that's how we can diagnose it, but diagnosing it is one thing. I mean, how can we really treat it? Well, unfortunately, there aren't really many medicines or procedures available to treat celiac disease. Once the gliadin from the gluten makes its way into the body, it's pretty difficult to stop the antibodies from marking them, so, ultimately, the best thing that anyone can do is to simply go on a gluten-free diet. Now, usually, these gluten-free diets are pretty strict. But I think that now, given that there's this rise of gluten-free diets, it's becoming a little bit more easy for people to maintain these diets. As long as you don't consume gluten, then you should be okay, even if you have celiac disease.