Presented by: Nielsen Fernandez-Becker, MD, PhD
Clinical Assistant Professor, Gastroenterology and Hepatology
May 5, 2016
Celiac disease is a chronic inflammatory disease of the gastrointestinal tract that is triggered by eating gluten, the protein found in wheat, rye, and barley. When people with celiac disease eat gluten, their body mounts an an immune response that results in destruction of the villi, small finger-like projections that line the small intestine. The damaged villi are not able to absorb nutrients properly, which over time can cause vitamin deficiencies that lead to systemic complications such as bone disease, fatigue, anemia, arthritis, and other problems.
Celiac disease was first noted by Areatus of Cappadocia in the second century, who described the symptoms as koiliakos, meaning abdominal. In the late 1880s Samuel Gee first linked the condition with diet, and 70 years later Dutch pediatrician Willem Dicke made the diet connection directly to wheat protein. More recent research identified specific antibodies that cause the immune reaction and identified genes that put people at higher risk for developing the disease.
“We are only seeing the tip of the iceberg in terms of diagnosing celiac disease,” said Nielsen Fernandez-Becker, MD, PhD, a clinical assistant professor of gastroenterology and hepatology, who spoke at a presentation sponsored by the Stanford Health Library. “Like other complex diseases, it is due to a combination of various factors, including genetics, a malfunction of the innate and adaptive immune systems, and the environment.”
Celiac disease affects about 3 million people in the United States—about 1 percent of the population. Two genes—DQ2 and DQ8—have been associated in 99.9 percent of people with the condition: While carrying one of these genes puts an individual at risk of developing celiac disease, it does not mean the individual will definitively develop the disease. In fact, about 30 percent of the population have one or the other of these genes, but only 4 percent of that group goes on to develop celiac.
The 20 or more feet of the small intestine are lined with tiny, finger-like projections called villi that absorb vitamins, minerals, and other nutrients. Gliadin, the toxic component of gluten in celiac disease patients, binds special immune cells called antigen-presenting cells (APC) via HLA molecules. This causes the activation of the body’s T cells and the inflammatory response that damages the intestinal mucosa.
“In a sense, the immune cells think the gliadin is a pathogen,” said Dr. Fernandez-Becker. “It’s like friendly fire. Every time the immune response is activated, it causes damage to the small intestine. In time, the villi are destroyed.”
Normally the intestinal lining, or mucosa, looks velvety, like a plush carpet inside the small intestine. Celiac disease corrodes the lining so it becomes smooth, with scalloping, nodules and fissures. With continued inflammation, additional problems can arise, including osteoporosis, anemia, malnutrition, liver abnormalities, and cancer.
Signs and symptoms of celiac disease may range from mild abdominal discomfort to severe diarrhea and bloating. It is possible to have celiac disease without any symptoms or to have a refractory condition that prevails despite no exposure to gluten. Some doctors may monitor these people carefully or introduce a no-gluten diet as a preventive measure, Dr. Fernandez-Becker said. The disease is often misdiagnosed since its symptoms can be non-specific and similar to other disorders, such as irritable bowel syndrome.
Diagnosis and Treatment
Other conditions that mimic celiac include gluten sensitivity, which causes similar symptoms but does not cause damage to the small intestine, and wheat allergy, caused by a specific immune response to a particular antibody (IgE) in food. Neither of these conditions is considered an autoimmune disorder nor do they involve an identified genetic marker. Adopting a gluten free diet will not provide an accurate diagnosis since all three conditions will improve with gluten exclusion.
There are two steps to confirm whether you have celiac disease. Screening involves a blood test to measure certain immune system antibodies. The most common is called a tTG-IgA test, which accurately identifies the disease in more than 90 percent of cases. If test results suggest celiac disease, an endoscopic exam can check for changes in the small intestine to confirm the diagnosis.
“You must be on a diet containing gluten when undergoing these tests,” Dr. Fernandez-Becker said. “If you have stopped eating gluten it may make the diagnosis very difficult, and gluten may need to be reintroduced to clarify the diagnosis. You need to have an accurate diagnosis because of the long-term complications of the disease, even if you feel better without gluten.”
There is no cure for celiac disease: The only effective treatment is to remove gluten from the diet. Once gluten is eliminated, inflammation in the small intestine typically begins to subside fairly quickly, but it may take many months for mucosa to heal completely.
A gluten-free diet means no wheat-containing beer, pasta, bread, or crackers are allowed. There are also “hidden sources” of gluten, such as soy sauce, vinegar, processed foods, and even toothpaste and medication. Even a small amount of gluten is enough to cause symptoms and complications, so read labels carefully. Quinoa, corn, millet, wild rice, soy, grits and tapioca are still okay to eat.
Patients benefit from seeing an experienced dietician for guidance on following a gluten-free diet long-term, which involves a lifelong lifestyle change. Studies found that patients who do not respond to diet changes either were still exposed to gluten (35 percent), had an overlapping condition of irritable bowel syndrome (25 percent), or had another condition (10 percent), including bacterial overgrowth, colitis, lactose deficiency, or refractory celiac disease.
Researchers are studying the basic biology of the triggers to celiac, clarifying the role of T cells and the small intestine’s epithelial cells, and tracing what factors causes only some people with the DQ2 or DQ8 gene to develop celiac. Once promising trial involves using a peptide that breaks down gluten into components so small they do not induce an immune response; another is looking at a molecule that tightens connections between intestinal cells to prevent gluten from coming into contact with immune cells. There also are efforts under way to develop a vaccine to suppress immune response to gluten.
In the meantime, Dr. Fernandez-Becker suggested patients follow CELIAC guidelines: Consultations; Education; Lifelong adherence; Identify and treat deficiencies; Advocacy access; and Continuous long-term following.
About the Speaker
Nielsen Q. Fernandez-Becker is a clinical assistant professor of gastroenterology who specializes in celiac disease. She received her medical education at Albert Einstein College of Medicine in New York, did her residency and internship at Massachusetts General Hospital, and completed her fellowship at Beth Israel Deaconess Medical Center. She joined Stanford in 2009.
For More Information: