Crohn's disease and ulcerative colitis, the major forms of inflammatory bowel disease (IBD), were thought to be autoimmune diseases. The fact that a genetic component existed was only recognized in the mid-1970s, and the influence of both genetics and environment in IBD was not understood until about 20 years ago.
The different forms of IBD were difficult to differentiate, and doctors often prescribed broad-spectrum anti-inflammatory drugs to treat all forms of IBD. "A lot of patients underwent surgery (i.e., to remove diseased segments of the intestine) when those drug therapies failed," explained Dr. Brian Feagan, a professor of medicine and epidemiology and biostatistics at the University of Western Ontario and an internationally recognized expert in IBD therapy.
There is no cure for IBD, which generally begins in early adulthood and continues throughout life. However, most people with IBD are able to lead normal lives with the use of medication and surgery. In the past 15 years, better ways to treat IBD have been introduced, including biologic therapy to decrease inflammation and early immune suppression to prevent disease progression.
The causes of IBD are still unknown, but researchers believe it may be inherited and set off by environmental factors. Canada and Sweden have the highest incidence of Crohn's disease and ulcerative colitis worldwide. There are more than 5,000 new diagnoses of Crohn's disease and 4,000 of ulcerative colitis every year. More than 200,000 Canadians live with one of these diseases.
"We did not understand the combination of genetics and environments until the late 1980s, when researchers examining certain immune genes discovered by serendipity that animals developed what looked like the human form of IBD as a result of gene abnormalities," said Dr. Feagan. Within the last decade, researchers have identified upwards of 20 gene associations with IBD, more than any other chronic inflammatory disease.
The medical community is still uncertain of what is happening in the bowels of people with Crohn's disease or colitis. Dr. Feagan has suggested that T cell lymphocytes may be reacting to bacteria in the intestines and setting in motion a process that leads to tissue damage and the onset of disease. "We think what's going on is the body is reacting against microbes," said Dr. Feagan.
While the Crohn's and Colitis Foundation of Canada (CCFC) believes that medical researchers will find a cure for Crohn's disease and ulcerative colitis, Dr. Feagan believes that "the puzzle is still not complete. We need to know which bacteria reacts with which gene defect."
A Canadian study – the Genetics, Environmental and Microbial (GEM) Project – is following patients with Crohn's disease and their families for 5 years to determine risk factors for the disease.
More rapid and dramatic changes, according to Dr. Feagan, will come in the use of new drug therapies. In the past 10 years, four new TNF-alpha inhibitors that can suppress the inflammatory process, have been introduced in Canada. "There is evidence they are more effective when used with early immune suppressants and given early in the course of the disease,” Dr. Feagan explained. “Rates of surgery are also decreased."