Crohn's Disease: Which came first, dysbiosis or inflamation?

Sounds like kind of a technical question.

In Irritable Bowl Disease, including Crohn's Disease, it may be the case that bad bacteria cause intestinal wall inflammation. Or, inflammation could allow bad bacteria to do better than good bacteria. And, that might be an oversimplification because there could be other factors as well, including genetic predispositions.

Many younger people who present with various abdominal symptoms are treated with antibiotics. These antibiotics could disproportionately favor bad bacteria.

Whether from inflammation, genes, or use of antibiotics, it does seem that "dysbiosis" (having bad bacteria along with the good ones in your gut) is a problem.

The results of a large study are now being released that looks at this problem in a way that might untangle some of these questions. From Science (News):

The research, which involved 668 children, shows that numbers of some beneficial bacteria in the gut decrease 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 antibiotics—which aren't recommended for Crohn's but are often given when patients first present with symptoms—may actually make the disease worse.


Some potentially harmful microbial species were more abundant in Crohn's patients, such as those belonging to the Enterobacteriaceae, Pasteurellaceae, Veillonellaceae, and Fusobacteriaceae; numbers of the Erysipelotrichales, Bacteroidales, and Clostridiales, generally considered to be beneficial, were lower. The disappearance and appearance of species can be equally important, says Dirk Gevers of the Broad Institute in Cambridge, Massachusetts, who performed most of the work. "There has been a shift in the ecosystem, which affects both types.”

The subjects tended to not have been treated with antibiotics, or at least, not much (yet), but there was variation and those who had received more antibiotic treatments seemed to have more dysbiosis.

The dysbiosis was also more pronounced in patients who had received antibiotics. "This study confirms that these drugs don’t do any good to people with Crohn’s disease," says gastroenterologist Séverine Vermeire of the Catholic University of Leuven in Belgium, who was not involved in the study. "We knew antibiotic use increases the risk to develop the disease; now we know they can worsen it, too."

The main outcome of this research may be the development of easier to implement and more reliable diagnostic techniques. But it also seems to advance understanding of Crohn's. What this study does not do directly, though, is address the strange epidemiological signal whereby Crohn's seems to be increasing in western populations. Something we are doing may be involved. Most people seem to assume this is dietary, but I won't bet a dime on that. This could have to do with all sorts of other practices that ultimately influence gut flora, from hand washing and diapering practices to food related but not strictly dietary choice related changes, such as how bacteria is removed from food during processing.

Vermeire says it's a "missed opportunity" that the researchers didn't look at the patients' diets. "That could have helped elucidate why this disease occurs so much more in the Western world than elsewhere." In 2011, Vermeire’s group published a study showing that healthy family members of Crohn’s disease patients have a slight dysbiosis as well. Vermeire is convinced that even in these families, it's not genetics but some lifestyle factor that causes the phenomenon. "If we could identify the dysbiosis in an early stage, and we knew the causative factors,” she says, “we could prevent disease occurrence by bringing about lifestyle changes.”


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I have an idle curiosity, as to whether there is a difference, between home birth and hospital birth, in the subsequent intestinal biome and the incidence of inflammatory bowel disease.

By Joseph Yaroch (not verified) on 15 Mar 2014 #permalink

Interesting! My husband was diagnosed with Crohn's at the same time they found his small intestine and colon cancer. He was on antibiotics all through chemo, and now the Chron's is acting up again.

Joseph, I'm going to guess not. The whole process of developing gut flora is slower and the real business probably starts later, so what happens in the first few days, and thus the difference between home and hospital, is probably not a factor. One could do a preliminary study to see if there is anything at all there, but I doubt it. But, I'm just guessing here.

I once heard a lecturer saying, among other things, that the increase in such problems might be a consequence not of hospital birth, but of C section birth. His recommendation was that immediately after birth an attendant, or the mother herself, could take a swab of her vaginal flora and swish it around the infant's mouth to imitate the normal transfer of flora during vaginal birth.

It's an idea. Can't possibly suggest an estimate of its worth. It wouldn't explain the increase in inflammatory bowel conditions in people whose birth was not C section.

There's considerable reason to suspect that could reduce the risk of allergies associated with C-sections, and it's hard to prohibit. Most American mothers are too biophobic to dare do it, though.

Interesting article, although it should be noted that a acute bout of gastroenteritis itself is also a known risk factor for IBD: (Porter CK, Gastroenterology. 2008;135(3):781)

Greg, small correction, there is no such thing as Irritable Bowl Disease. This is a mix-up of Inflammatory Bowel Disease (IBD), that includes Crohn, and Irritable Bowel syndrome (IBS)

Although most studies agree that having a C-section is associated with a higher rate of (food) allergy, no causative mechanism has been proven. There is no evidence that swabbing kids with vaginal flora would be effective, let alone safe. The risk increase of a C-section is small. Accepting an absolute risk of milk allergy of 0.50%, having a C-section would increase this absolute risk to 0.59%. (Metsala et al. 2010) Not that scary of a number, meaning that any intervention needs to be very safe.

Dr. Death - Did either Adelady or I confine our comments to milk allergy? There are also multiple studies reporting substantial increases in childhood hay fever and possibly asthma, with the number harmed being enormously more than 0.09%. A plausible causative mechanism has been proposed. It will be impossible to prove that or any other mechanism, no matter how many studies showing the same association pile up, until a large prospective clinical trial of vaginal swabbing vs. non-swabbing is done. In fact, in America such a method would not be recommended by most doctors until many such trials had been done, taking many years. In the meantime, people who know that there probably are harms associated with C-sections cannot be blamed for considering harmless ways of avoiding needless harm.

As for the safety of the proposed method: The normal means of childbirth for us, as for all mammals, involves pushing the baby's face through, horrors!, an icky moist mucous-membrane-lined non-sterilized woman's vagina. We can therefore conclude that contact between pure little face and icky vagina is not lethal, or we would still be oviparous today. Taking a little swab and quickly wiping it across the baby's lower face would be a much briefer and less intense exposure to the same icky (though often biologically necessary) germs. In most cases, that should not pose any safety risk whatsoever.

There's a lot of confusion inside and outside the IBD community on the difference of Crohn's disease, ulcerative colitis and colitis. Can you please enlighten us?

By Raymond Dee (not verified) on 01 May 2014 #permalink