Researchers have not yet identified the cause of Crohns disease, so it is described as an “idiopathic” disease. It is known that inflammation is part of the body’s immune response, and an immune response is usually triggered by something. But to date no specific “trigger” has been found to cause the inflammatory response seen in Crohns disease.

There is some evidence that Crohns disease has a genetic component. While there is no simple correlation from parent(s) to offspring, the disease tends to “run” in families. As many as 20 to 25 percent of patients with Crohns disease have a relative with CD or ulcerative colitis.

There is also a higher incidence among certain ethnic groups.In addition, some possible environmental factors have been linked to initial episodes or relapses. Crohns disease appears to be a disease that primarily affects those living in Western, industrialized societies. Whether this is due to some condition of the environment in which people live or their diet has not been determined.

The Role Of Heredity
Physicians classify Crohns disease as one of the “familial” or “complex” genetic diseases, as opposed to a “simple” genetic disease. In simple genetic diseases, such as sickle cell disease or cystic fibrosis, a person who inherits a copy of the defective gene from each parent is certain to get the disease. In Crohns disease, this is not the case. In fact, 75 to 80 percent of people with Crohns disease have no relative with either Crohns disease or ulcerative colitis.

But because there are fewer than 500,000 Americans with Crohns disease, the level of multiple incidence in families (20 to 25 percent of Crohn’s patients) means that the risk of being diagnosed with the disease is statistically somewhat higher in individuals who have a family member with either Crohns disease or ulcerative colitis.

Other evidence that suggests a genetic basis for Crohns disease is the fact that populations who have intermarried closely within their communities for many generations, such as Eastern European Jews, have a higher incidence of inflammatory bowel disease than do other groups.

Weakened Immune Response
In the healthy intestine, certain types of bacteria (enteric microflora) are present and necessary. In fact, between one billion and one trillion normal intestinal bacteria exist in every gram of intestinal content. These “normal” bacteria contribute to the process of digestion and keep abnormal bacteria, which can enter the GI tract in food, water, etc., from surviving and causing illness. If abnormal bacteria do survive and multiply, the body recognizes them as invading organisms, or “antigens.”

To a certain extent, these antigens are ignored in the GI tract – the immune system has a certain level of tolerance for them. But immunologic evidence shows that in the intestines of those with inflammatory bowel disease, some of this tolerance for bacteria is lost.

The TH1 cells, which are responsible for activating the immune response against invading organisms, do their job. But the TH2 cells, which are responsible for deactivating the immunologic response after invading organisms are destroyed, fail to perform theirs. The result is an inflammatory overreaction, resulting in pain, fever, and, sometimes, tissue damage.Some evidence also suggests that flare-ups of Crohns disease or ulcerative colitis are a heightened response to seasonal allergies, upper-respiratory infections, or other transient illnesses.

While well known for its effect on blood flow, until now Viagra has not been used to boost circulation in the intestine. That could change with the finding that Viagra can help treat Crohns disease. People with the long-term, inflammatory condition develop holes and ulcers in the intestine.

A team from University College London wondered whether an overactive immune reaction was the problem.The team carried out biopsies on six Crohns disease patients and nine healthy volunteers. The operation triggered an acute immune response in the healthy people, producing white blood cells to heal damage caused by the removal of cells. But the Crohn’s patients responded by producing far lower amounts of white blood cells. The researchers used Viagra to boost blood flow to the intestine in the patients with Crohns disease, thus increasing the flow of white cells to the damaged area.

Researchers in the U.K. have a new theory to explain the cause of Crohns disease, and they say medications like the erectile dysfunction drug Viagra may prove useful for treating the bowel disorder if they are right.In Crohns disease, chronic inflammation causes ulcers within the digestive tract that can lead to severe gastrointestinal symptoms, including abdominal pain, persistent diarrhea, and rectal bleeding.The most widely accepted theory is that an overactive immune system causes the damaging inflammation.

But researchers from the University College London say the opposite appears to be true.They believe a weaker-than-normal immune response triggers the bowel inflammation that leads to Crohns disease. The researchers tested this theory by treating 10 Crohn’s patients with 50 milligrams of Viagra after injecting them with the killed gut bacteria. They found that blood flow to the infected area improved.

“Increasing blood flow is an important part of the inflammatory response, and that is why this drug may work,” Segal says. “But we don’t yet know if this will give rise to successful treatment. We need to study this further to find out.” The disease usually affects the small intestine and one in every thousand people in the UK is afflicted with this miserable complaint.

But now scientists believe they have found the cause of Crohns disease, and they think it could be treated with Viagra.The team of researchers from University College London say they believe the cause is the opposite of what has been supposed and is triggered by a weak immune system, rather than an overactive one where cells are attacked by the body’s own immune system.

Crohn’s was previously thought to be an auto-immune disease and was treated with immuno-suppressant drugs. But the researchers led by Anthony Segal and colleagues have discovered that people with Crohn’s have a weak and unresponsive immune system which does not repair damage easily. They say the flow of blood to damaged cells is substantially reduced, and a drug such as Viagra, best known for its effects on erectile dysfunction, could help the healing process as it stimulates blood flow.

Since it was identified in the 1920s there have been many theories as to the cause of Crohn’s and it was often compared with tuberculosis, but attempts to find an infectious agent have failed.
The research team compared the immune system response of Crohn’s patients and healthy individuals to minor injuries, such as skin abrasions and discovered a difference in the number of white blood cells called neutrophils produced by the body to heal the damage in the bowel and on the surface of the skin.

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