Crohn’s Disease (CD) is one of two main diseases, along with Ulcerative Colitis (UC), in a group of diseases known as Inflammatory Bowel Disease (IBD). Crohn’s is a disease characterized by inflammation of the gastrointestinal (GI) tract; CD can affect any area of the GI tract, which includes the entire digestive tract from the mouth to the anus, but most often happens in areas of the intestines (which include the colon and small intestine). CD is a chronic disorder that continues to affect the patient rather than just for a brief set of symptoms that eventually resolve. CD is named after a doctor who, along with 2 others, published the first paper that described the symptoms and disease course of CD. Both CD and UC are autoimmune conditions, where the body’s immune system acts wrongly by attacking cells that are supposed to be in the body, not cells that are a threat to the body. CD is believed to occur when the immune system attacks the “good” bacteria that reside in the GI tract of a healthy human. The immune system’s attack brings white blood cells into the lining of the intestines and inflammation occurs. The cells brought to the intestines by the immune system cause chronic inflammation that leads to injury to the GI tract and to ulcerations, and the patient with IBD has symptoms. CD and UC have symptoms that are very similar, so much so that up to 10% of patients with colitis are classified as having “indeterminate colitis,” meaning a diagnosis of CD versus UC cannot be made. One difference between the two diseases is the fact that CD can happen at any point in the GI tract (though primarily occurs at the ileum, the end of the small intestine, or the colon, the beginning of the large intestine), while UC only affects the colon. Another difference between UC and CD is the way the disease affects the diseased tissue. In UC, only the surface layers (the innermost cells) of the colon (called the mucosa) are affected by the disease, and the damage and inflammation to cells is evenly spread without any areas of normal tissue. On the other hand, CD may involve cells at any layer of the GI tract, and there are sometimes areas of normal, healthy tissue in between the damaged cells.
About 1.4 million people in the US have IBD, with UC and CD each representing about half of those cases. There are many factors that correlate with increased incidence of IBD, and not all of these are fully understood. Some factors include genetics (many IBD sufferers have a relative with the disease, around 20-25%), race/ethnicity (some differences appear between groups, though this seems to be changing over time), and environment (though the cause is not completely understood, people in some areas of the world as well as in some areas of the US more frequently develop IBD.
Symptoms of CD
Though symptoms can vary greatly in type and severity from person to person, there are some symptoms that are characteristic of CD (they occur in most or many CD patients). Also, CD is a disease that flares up, with the patient experiencing symptoms and GI inflammation and damage taking place, then dies back down, with symptoms lessening and the disease going into remission (a time when CD is not or less active and the patient is in good health). With management, most patients with CD are able to live normal and productive lives. The characteristic symptoms of CD include: diarrhea, abdominal pain or cramps, fever, and sometimes bleeding from the rectum. Because of CD symptoms, patients may experience fatigue, loss of appetite, and weight loss. Some CD patients develop anal fissures (tears in the lining of the anus), which cause moderate to severe pain, particularly when the patient has a bowel movement. Fistulas can also form as a result of inflammation from CD. Fistulas occur mainly in the anal area and are a malformation of the intestine where a tunnel forms between the loops of the intestines or between the intestines and the skin, the bladder, or the vagina. Complications of a fistula are noticed when feces, pus, and/or mucus drains from the opening.
Treatment of CD
Since CD is a chronic illness (a person experiences it throughout his/her life and there is not a cure), the goal of treatment is to decrease inflammation and therefore lessen the symptoms caused by it. When inflammation declines, the GI tissue has time to heal and remission hopefully occurs (symptoms are brought under control and subside for a time). Treatment is also used to maintain remission and decrease the frequency of flare-ups. Several classes of drugs are often used in treatment of CD:
- Aminosalicylates (5-ASA): A class of anti-inflammatory drugs, these are used to treat mild or moderate CD symptoms. Examples are oral sulfasalazine (brand names Asacol, Colazal, Pentasa, Dipentum) and rectal 5-ASA (brand names Rowasa and Canasa).
- Corticosteroids: This class is used to treat CD that is active and moderate or severe. These drugs work by generally suppressing the immune system (not targeting a specific part of the immune system that causes inflammation). Corticosteroids should not be used as maintenance drugs due to their many short term and long term side effects. Examples include prednisone and methylprednisolone.
- Immune Modifiers: These medications are used to maintain remission of CD, to heal fistulas, and to decrease the dosage patients need of corticosteroids. Examples are azathioprine (Imuran), 6-MP (Purinethol), and methotrexate.
- Antibiotics: Metronidazole, ampicllin, ciprofloxacin and others have a role in preventing and eliminating infection in the GI tract.
- Biologic Therapies: These medications are used for CD patients with moderate to severe disease who do not respond to other therapies to decrease inflammation. Biologic medications are genetically engineered from living organisms (like genes and proteins). They reduce inflammation and decrease CD symptoms by acting on a specific part of the immune system and blocking its attack on cells that the immune system is erroneously attacking. Examples of biologics are infliximab (Remicade), adalimumab (Humira), and certolizumab (Cimzia). Another biologic is natalizumab (Tysabri), which is typically used when patients cannot tolerate or do not respond to other Crohn’s therapies, including other biologics.
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