What causes UC?
Scientists are not certain what causes UC, so it is known as an idiopathic disease, or a disease with unknown cause. However, there are several theories about the origins of UC and conditions that may contribute to its development.
UC (like Crohn’s disease) is an autoimmune disease, a disease that is triggered by the immune system. Seasonal flare-ups sometimes occur in people with IBD. Some people experience problems only in the spring or autumn seasons. One theory is that this is a IgE-mediated allergic response.
IgE is a type of immunoglobulin isotype, which is a special protein that helps inactivate organisms that may cause disease. The function of IgE is to bind itself to an antigen and inactivate or remove offending toxins, microbes, or foreign substance. However, IgE tends to attach itself to receptors on mast cells which triggers allergy symptoms such as a runny nose. If an antigen binds itself to one of these IgE cells, the mast cells are activated, and release histamine, heparin, cytokines, leukotrines, and other chemicals.
The presense of leukotrines attracts a new type of cell called an eosinophil. These cells fight off the allergic response, but the chemicals that they use to do so are toxic to the body as well as to the invading infection. The connection between eosinophils and IBD is that three of the four toxic compounds that are released by eosinophil cells are found in in the stool of IBD patients.
A similar theory is that UC is caused by the immune system attacking the healthy bacteria found in the colon. Cells in the body called TH1 cells are responsible for initiating the immunologic response–the process that removes foreign bodies or unhealthy bacteria. Cells called TH2 cells tell the body to stop this process of removing any alien materials. In people with UC, the TH2 cells do not do their duty, which causes an attack on the billions of healthy bacteria living in the colon and results in an inflammatory response.
Scientists have also noticed trends in the epidemiology of IBD. IBD tends to occur most often in Canada, the United States, Australia and western European countries. This leads researchers to think that there may be some connection between IBD and the lifestyles or environment of people living in these countries.
Are there different forms of UC?
Typically, inflammation from UC begins at the end of the digestive tract, in the rectum, and may spread up the colon. Unlike Crohn’s disease, UC does not skip around to different areas of the colon; the inflammation encompasses one entire section.
Physicians may use different terms to describe UC, depending on how much of the colon is affected.
Ulcerative proctitis is inflammation located in the rectum and symptoms include diarrhea, bloody stool, rectal pain, and an urgent need to move the bowels. Proctosigmoiditis is inflammation located in the rectum and sigmoid colon and symptoms include diarrhea, bloody stool, crampy pain, and pain on the left side of the abdomen. Left-sided colitis (also called limited or distal colitis) is inflammation in the left side of the colon (rectum and sigmoid and descending colon) and symptoms include diarrhea, bloody stools, weight loss, loss of appetite, and occasionally severe left-sided pain. Pancolitis is inflammation throughout the whole colon and symptoms include diarrhea, cramps, significant weight loss and severe abdominal pain.
Ulcerative proctitis, proctosigmoiditis, and left-sided colitis may all be treated with medicines that are introduced through the anus such as a foam or suppository. Pancolitis must be treated with oral medication in order for the drugs to reach the entire colon and have the best effect.
