By Pat Anson, Editor
A team of international researchers may have unlocked an ancient secret in the human immune system that could lead to new treatments for rheumatoid arthritis, multiple sclerosis and inflammatory bowel disease (IBD).
"Innate immunity is so old it goes all the way down to frogs, fish and even insects," says Professor Matt Cooper of the University of Queensland’s Institute of Molecular Bioscience.
Cooper and colleagues at Kings College London and the U. S. National Institutes of Health say the human immune system is basically comprised of two parts: the adaptive immune system, which produces antibodies against infection, and a very ancient pathway, known as the innate immune system.
"It stops us getting infections, but it also drives a lot of inflammatory diseases,” explains Cooper. "So, in one case it's keeping us alive by stopping the bugs getting us, but if it goes wrong, we start to get diseases like arthritis, multiple sclerosis and IBDs such as colitis.
"Researchers always thought key components of these pathways acted alone, but our teams have discovered they can communicate and work together."
IBD is a chronic and painful inflammation of the gastrointestinal tract. Inflammation affects the entire digestive tract in Crohn’s disease, but only the large intestine in ulcerative colitis.
The study findings, published in the journal Science, may have significant implications for treating millions of people who suffer from inflammatory diseases.
"Inflammation in diseases such as colitis occurs when the immune system is activated inappropriately, and causes symptoms including pain, diarrhea, fever and weight loss," said Cooper. "Current treatments are not always effective, possibly because they are only blocking one of the key pathways and inflammation still occurs through the other pathway."
Researchers have developed two small molecules that each block one pathway.
"We have tested these molecules and the results show that they both reduce inflammation when administered separately," Cooper said. "This work is still in the early stages but we are hopeful our ongoing research will lead to more effective treatments for the millions of IBD sufferers.
"It may give other scientists opportunities to develop new drugs against these diseases."
A healthy immune system is activated when the body recognizes invading microbes and alerts immune cells, such as T cells. Disease begins when the immune response spirals out of control and begins attacking healthy tissue.
Researchers at New York University’s Langone Medical Center are also working on a theory known as the "hygiene hypothesis" that may explain why there is an increase in inflammatory bowel disease worldwide. They believe intestinal parasites and bacteria that humans were long exposed to are beneficial and help balance the immune system.
Sanitary practices have sharply reduced these parasitic and bacterial infections in developed nations, which now have some of the highest rates of Crohn’s and colitis. Researchers believe the immune response to infections triggers the growth of Clostridia, a bacterium known to counter inflammation.