Crohn's disease can spread from the mouth to the anus. Chronic inflammatory bowel disease can affect the entire digestive tract. The inflammations can go through all layers of the intestinal wall and are often located in the transition between the small intestine and the large intestine. The illness doesn't always affect the entire intestine – there can be healthy sections, too.
Doctors can only alleviate the incurable disease's symptoms. But intense research is being done on Crohn's disease, says Raja Atreya. The senior physician has been the Heisenberg Professor of Immunology for Chronic Inflammatory Bowel Diseases at the University of Erlangen-Nuremberg since 2016.
"We are in the process of finding out how such an intestinal inflammation develops in order to better and better identify the molecules involved," Atreya told DW. "More is happening in this area than ever before. We expect more and hopefully better drugs to come onto the market."
Crohn's disease occurs in flare-ups. "It is possible that patients have no symptoms between flare-up episodes and hardly any discomfort. But there are also patients who suffer from flare-ups permanently," said Atreya. "That would be a very severe form."
Because of the severe diarrhea patients have to struggle with, they have to go to the restroom frequently.
"We've all been through that," Atreya said. "When we have diarrhea, we feel pretty miserable. Our social life suffers as well. You always have to make sure that there is a restroom somewhere nearby. Because when diarrhea comes along, you don't have much time and you can't hold it. You have to go right away. This can happen more than ten times a day in an acute episode."
Crohn's disease is a burden for the body and the psyche. Going to the movies or the theater and meeting friends can be more like torture than relaxing. Most people are between the ages of 15 and 35 when they are first diagnosed, but the disease increasingly manifests in older patients as well.
It is often very stressful and permanently affects the quality of life. Those affected often encounter incomprehension. Some friends, acquaintances and colleagues may not understand that Crohn's disease is indeed something very serious and might make comments such as: "I've had diarrhea before. It's not that bad and it'll pass."
Bad, worse, worst
Inflammations can narrow the intestinal mucosa. This leads to so-called stenoses.
"At some point, not even porridge or stool can pass through," Atreya said. "That's when we have to operate."
Patients who have undergone several surgeries may have had their bowels shortened significantly over the years.
Inflammation can be accompanied by ulcers in the intestines, or fistulas. They occur when epithelial cells, the cells making up the tissue that covers organs, form a tube-like connection.
These fistulas originate in the intestines. They can spread to other parts of the intestine, to the skin or, for example, to the bladder. This creates a kind of tube connection from the intestine directly to other organs.
More and more cases
In Germany, it is estimated that one to two in 1,000 people suffer from Crohn's disease.
"The number of Crohn's disease cases is increasing worldwide," Atreya said. "You could say that it has changed from a disease of the western world to a global disease. Crohn's disease now exists in countries where it has not been described before."
Genetic predisposition and environmental influences play a role in the development of Crohn's disease. In addition to that, there's the influence of the microbiome, which is the totality of microorganisms that colonize us and our stomach and intestines.
"The interaction of these factors ultimately leads to the immune system overreacting in the intestine, and this is how these inflammations occur," Atreya explained.
Raja Atreya has developed a promising method for predicting how Crohn's disease patients will respond to an anti-TNF antibody therapy.
In a study involving 25 patients, Atreya developed a spray of dye-labelled anti-TNF antibodies. This enables the detection of certain cells in the intestinal mucosa that carry the target structure of antibody therapy on the surface. If many of these cells appear in patients, the therapy works better than in patients with only a few cells.
According to Atreya, this has the advantage that patients don't have to undergo unnecessary therapies that do not help them and also have potential side effects. For this development he received the renowned Paul Ehrlich and Ludwig Darmstaedter Young Talent Award in 2015.