A blood test finds antibodies typical of Crohn’s disease two and a half years before symptoms appear. Towards a vaccine for those at risk?
A simple sample traces the signs of the onset of Crohn’s disease in the blood, just under two and a half years before the onset of symptoms. The test, developed by Canadian researchers, detects traces of antibodies against flagellin, a protein normally produced by intestinal bacteria that triggers improper immune reactions in those suffering from this intestinal disease. The discovery, published in the scientific journal Clinical Gastroenterology and Hepatologycould pave the way for a future vaccine against Crohn’s disease.
A defense that makes you sick
Crohn’s disease is a chronic inflammatory bowel disease that can affect any part of the intestine, and causes diarrhea, often intestinal bleeding, digestive difficulty, poor absorption of nutrients, chronic fatigue and abdominal pain. Scientists at the Lunenfeld-Tanenbaum Research Institute, a medical research institute in Toronto, Canada, had previously discovered that, long before Crohn’s disease manifests itself, the immune system can unleash a disproportionate inflammatory response that targets intestinal bacteria. In healthy people, these bacteria peacefully inhabit the intestine and are indeed essential for proper digestion.
Another research team, from the University of Alabama, had also developed a test to find traces of this exaggerated self-defense reaction in the blood: antibodies directed against flagellin, a protein that makes up the flagella, those “tails” that bacteria use for locomotion. People who suffer from Crohn’s disease show high levels of antibodies directed against the flagellin family of bacteria Lachnospiraceaewhich colonize the human intestine from birth.
Worrying signs
The study followed 381 first-degree relatives of people with Crohn’s disease for whom genetic, biological and environmental data had been collected: the sample was extracted from a database of the Genetic, Environmental and Microbial (GEM) Project, aimed at better understanding the origin of inflammatory bowel diseases. Over time, 77 of the participants developed the disease. Scientists were thus able to follow the phases preceding the onset of symptoms in unexpected detail.
Among these patients, more than a third (28 people) showed elevated levels of antibodies against the bacteria’s flagellin Lachnospiraceae already almost two and a half years before the diagnosis. The response seemed more marked in the siblings of those who had already been diagnosed with Crohn’s disease. The presence of harmful antibodies was accompanied by inflammation of the intestine and intestinal permeability, that is, the inability of the intestine to act as a barrier preventing the passage of toxins and other unwelcome elements into the blood: both of these symptoms are characteristic of Crohn’s disease.
Play early
The discovery opens up the possibility of developing vaccines directed against flagellin in people considered most at risk of developing Crohn’s disease, and offers an early intervention window to intervene to protect the intestines of future patients.
