bad news. In Crohn's disease, intestinal barrier becomes inflamed and disrupted (characterized by pink circles, called granulomas).
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The largest clinical study of this kind is revealing new insights into the causes of Crohn's disease, a periodic inflammation of the intestines. Mark, which involved 668 children, shows that the number of beneficial bacteria in the decrease of the intestine in Crohn's patients, while the number of potentially harmful bacteria increases. The study could lead to new less invasive diagnostic tests ,; it also shows that the antibiotics are not recommended for Crohn's disease but are often given when patients first present-symptoms may actually worsen the disease.
Crohn's disease is one of two major inflammatory bowel disease (IBD); the other is ulcerative colitis, a similar condition that affects only the colon. Both have been on the rise in the developing world since the early 1950s; Now, an estimated 1.4 million people suffer from IBD in the United States alone. Symptoms include diarrhea, abdominal pain and cramps, and intestinal ulcers.
Genetic studies turned up several genes that seem to predispose to IBD , most of them involved in the body's immune response. But genes alone can not explain the sharp increase in the incidence IBD, and scientists have focused on the environment, in particular the supply and use of responses to antibiotics.
Several studies have shown that Crohn's disease is characterized by microbial dysbiosis, a change in the microbial populations in the gut, but it is difficult to disentangle cause and effect a change in the intestinal microflora can cause inflammation, but the opposite can also occur. Complicating the picture is the fact that, before being diagnosed with IBD, patients often receive antibiotics to repel a supposed intestinal infection that could be causing the symptoms, which also have a powerful impact on microbial populations in our guts.
Now, a group led by Ramnik Xavier, a gastroenterologist at Harvard Medical School in Boston, collected fecal samples and take biopsies from the lower part of the small intestine and rectum of 447 children who had just being diagnosed with Crohn's disease, and group of 221 children who had non-inflammatory abdominal symptoms such as bloating and diarrhea control. In contrast to previous studies, the majority of the patients had not received antibiotics or anti-inflammatory. Based on their genetic makeup, the researchers determined the relative abundance of a range of microbial species in the samples.
Some potentially harmful microbial species were more abundant in patients with Crohn's, such as those belonging to the Enterobacteriaceae , Pasteurellaceae , Veillonellaceae and Fusobacteriaceae ; number of Erysipelotrichales Bacteroidales and Clostridiales , generally considered beneficial, were lower. The appearance and disappearance of species may be equally important, says Dirk Gevers the Broad Institute in Cambridge, Massachusetts, who performed most of the work. "There has been a change in the ecosystem, which affects both types."
But these differences were found mainly in the biopsy specimens, there was not much difference between the feces of Crohn's patients and the control group. At this early stage of the disease, "dysbiosis seems to have reached the stool," said Gevers.
dysbiosis was almost as severe in biopsies from the rectum than in the portion lower part of the small intestine , reports the team today in the Cell Host & Microbe . This means that in the future, a disease diagnostic test Crohn can be based on a simple rectal swab rather than a colonoscopy, which is the current standard, Gevers said a lot less stressful procedure for the patient.
dysbiosis was also more pronounced in patients who had received antibiotics. "This study confirms that these drugs are not good for people with Crohn's disease," says gastroenterologist Severine Vermeire of Katholieke Universiteit Leuven in Belgium, who was not involved in 'study. "We knew that the use of antibiotics increases the risk of developing the disease ;. We now know that they can aggravate it, too "
The results are" very encouraging diagnostic signals, "adds Pierre Rimbaud, chief medical officer at Enterome, a Paris-based company that develops based diagnostics on microbiota. But he stressed that the study still does not show if the dysbiosis is the cause or the effect of inflammation seen in Crohn's disease. Gevers appropriate; namely, scientists could inoculate mice raised in a completely sterile environment, allowing them to test the effect of individual microbial species. One of these microbes, F aecalibacterium prausnitzii , has already been described as an anti-inflammatory species that could become a probiotic supposedly for the treatment of IBD.
Vermeire says it is a "missed opportunity" that the researchers did not look at the diets of patients. "It could have help elucidate why this disease occurs much more in the West than elsewhere." In 2011, the group Vermeire has published a study showing that the health of family of patients with Crohn's disease have a slight dysbiosis as well . Vermeire is convinced that even in these families, it is not genetic, but some lifestyle factors causing the phenomenon. "If we could identify dysbiosis at an early stage, and we knew that the causative factors," she said, "we could prevent the onset of the disease by making lifestyle changes."
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