Interstitial Cystitis (cont.)
Interstitial Cystitis Causes
Although many theories have been put forward, the cause of IC is unknown. The theories for the cause of IC include the following:
- Autoimmune: An autoimmune response is a physical response in which cells and antibodies of a person's body are directed against that person's own tissues. An autoimmune response to a bladder infection destroys the lining of the bladder wall. An unexplained association of IC has been found to exist with other autoimmune diseases such as inflammatory bowel disease, systemic lupus erythematosus, scleroderma, Sjogren syndrome, fibromyalgia, and atopic allergy. IC has a very high association with disorders of the bowel such as inflammatory bowel disease.
- Hereditary: Studies of mothers, daughters, and twins who have IC suggest a hereditary risk factor. However, no gene has yet been implicated as a cause of IC.
- Mast cell abnormalities: In some people with IC, special white blood cells called mast cells (associated with inflammation) are found in the bladder lining. Mast cells release histamine and other chemicals that cause inflammation of the bladder.
- Defect in bladder epithelium: The bladder has a specialized natural lining called the epithelium. The epithelium is protected from toxins in the urine by a layer of protein called glycoaminoglycan. In people with IC, this protective layer breaks down, allowing toxins to irritate the bladder wall and cause inflammation of the bladder.
- Neurogenic: The nerves that carry bladder sensations are inflamed, so pain is caused by events that are not normally painful (such as filling of the bladder).
- Infectious: Although no causative infective agent has been found in the urine of people with IC, an unidentified infectious agent may be the cause.
Probably, different processes occur in different groups of people with IC. It is also likely that different processes may affect each other, for example, a defect in the bladder epithelium may start the inflammation and stimulate mast cells to release histamine.
George Lazarou, MD, FACOG
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