Amy Taylor
BIOL 1101
4/15/2011

Anatomy and Physiology of Crohn’s Disease

Crohn’s disease (CD) is a chronic, relapsing inflammatory disease of the intestines with usually peak between 15 and 35. It is one of many Inflammatory bowl disease (IBD), and is sometimes also called Regional enteritis, Morbus Crohn’s, Terminal iletis, or Granulomatous enteritis. It primarily affects the small and large intestine, but can affect the digestive system anywhere between the mouth and the anus. It is named after the physician who examined the disease in a landmark paper written in 1932. Crohn's disease lasts for many years throughout life, and many patients require surgery at some point and even then they can have recurring symptoms. The cause of CD is unknown, although there are two major theories. One theory is that the structural changes in the cells of the bowel are perceived by the immune system as foreign and are attacked, leading to constant inflammation. The second theory is that an unknown type of bacterium persistently attacks the bowel, which also leads to constant inflammation. Patients with CD are usually nutritionally deficient which is mainly due to a decreased intake and malabsorption of nutrients. This tends to happen because certain parts of the abdomen might be inflamed so the patient may not be able to properly absorb the food, which can cause them to be deficient in certain vitamins and other nutrients. Although diet may affect the symptoms in patients with this disease, it appears unlikely that diet is responsible for the onset of the disease. Over the past few decades, the occurrence of CD has increased in Western populations. It is estimated that 4000,000 to 600,000 patients in North America have it. CD occurs equally in both sexes, and is more common among individuals of Jewish descent, which are four to five times more likely to develop the disease. 149 out of 100,000 whites have the disease, and African Americans have started to develop the disease more readily. However, Asians and Hispanics have a lower chance of developing the disease. Studies have also shown that people who smoke have a higher risk of developing this disease. They have found that people in developed countries who live in urban and rural areas, and live in northern climate are more likely to get the disease. The frequency of the disease also increases when people move from developed countries to undeveloped countries, and vice versa. There is also a genetic link with CD; about 3 in 20 people who have CD have a close relative who also has it. The most common symptoms of CD are persistent diarrhea, abdominal and back pain, weight loss, mouth ulcers, nutritional deficiencies and a greater risk of developing colorectal cancer. CD is often mistaken as appendicitis at first due to the severe pain in the right side at times of flare up. Most generally feel unwell a lot of the time which can include fever and fatigue even after getting plenty of rest. Due to the fact that CD can often mistake bacteria and foods as being “invaders”, many people find that eating things that are good for you (fruit, granola, etc.) can actually cause a flare up. For most people with CD figuring out what foods to eat just becomes a trial and error process, because it is different for everyone. The disease can also affect the liver, eyes, skin (usually rash’s), and joints. Children with CD often suffer from delayed growth and sexual development. Most medical professionals consider CD an autoimmune disease in which the immune system reacts against normal bowel bacteria and attacks the intestinal tissues. It is a heterogeneous disease, which means that it does not manifest itself in the same way in every patient. Inflammation of the small intestine and colon is very common for patients who have CD. This can lead to mucosal damage and further disturbance of the epithelial barrier function. The intestinal tract is a diverse microenvironment where more than 500 species of bacteria thrive. Often times in CD, most patient either lacks the good bacteria or the immune system confuses the good bacteria as an invader and tries to rid the body of it. The epithelia barrier function is a key component in the defense mechanisms required to prevent infection and inflammation. It also helps to maintain homeostasis in the intestinal tract by protecting it from pathogens. A single layer of epithelium is all that separates these microorganisms and pathogens from the underlying immune cells. The epithelial barrier consists of a dense mucous layer containing secretory IgA and antimicrobial peptides as well as dynamic junctional complexes that regulate permeability between cells.
Inflamed ulcers burrow through the bowel wall, and can tunnel into adjacent structures. If the ulcer tract reaches an adjacent empty space inside the abdomen, a collection of infected material (abscess) is formed. Patients with abdominal abscesses may develop high fevers and intense pain in the abdomen. A fistula is an abnormal passage or tunnel from one part of the intestine, skin, abdominal wall, vagina, bladder, or another nearby organs. When the ulcer burrows into an adjacent organ a fistula is formed. When a fistula develops between the bowel and the bladder, the patient can develop recurrent urinary infections, and passage of air and feces in the urine. A fistula can also occur between the intestine and the skin, leading to the discharge of pus or mucus through a small painful opening on the skin of the abdomen. Inflammation can also causes a thickening of the intestinal wall, which sometimes causes an obstruction in these areas, or scar tissue, which narrows the passageways.
Treatment of CD depends of the location and the severity of the disease. It used to be that they would give patients steroids to help control inflammation, but now later realized the damaging affects of someone being on steroids for long periods of time. They now try to only use steroids as a last resort if the patients other medications aren’t working. There are two major types of drugs to treat CD right now. Biological therapies are genetically engineered proteins that contain special antibodies. They have found that there is a chemical called cytokine tumour necrosis factor (TNF-alpha) that causes inflammation in CD patients. This drug works to block this chemical and suppressing the disease. The second drug is Immunomodulators which modifies and suppresses the immune system. They tend to only use this drug when biological therapies haven’t work and in more severe cases. Many doctors have started treating their patients with different types of antibiotics that are used to treat different kinds of bacteria that are associated with CD. Many patients also find that staying away from spicy, greasy, and over processed food tends to help control their flare ups. Others also find that taking daily vitamins such as vitamin D, iron, probiotics, and vitamins with enzymes that help to break down food. Most people who suffer from CD will have to have surgery at some point. Surgery becomes necessary when medications can no longer control symptoms. Surgery is used either to relieve symptoms that do not respond to medical therapy or to correct complications such as blockage, perforation, abscess, or bleeding in the intestine. If the inflammation in one area spreads all the way through the intestinal wall, the inflamed area can stick to other organs and structures in the abdomen. This is what happens for a lot of women; their uterus begins to stick to their other organs and often times end up having to have a hysterectomy to fix this problem. Surgery does seem to help minimize flare-ups for a year or so, but there is a high recurrence rate. This means that the disease often returns at some point after surgery.
Chron’s Disease has come a long way since 1932, and a great deal of research and clinical trials are still being done to try and better understand this disease. Although there may never be a cure for this disease, researchers are very hopeful about developing new medicine to better control and manage patient’s symptoms.

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“About Crohn’s Disease.” Crohn’s and Colitis Foundation of America. 2009. March 28, 2011. < http://www.ccfa.org/info/about/crohns>

Moorthy, Denish, Kathleen L. Cappellano, and Irwin H. Rosenberg. "Nutrition and Crohn's disease: an update of print and Web-based guidance." Nutrition Reviews 66.7 (2008): 387-397.

Drobot, Chantelle. "Crohn's disease." Alive: Canadian Journal of Health & Nutrition 278 (2005): 40-41. Alt HealthWatch. Taylor, Catriona, G. “Learning to live with Crohn’s disease.” Personal Interview. March 15, 2011.