Inflammatory Bowel Disease and the Microbiome

Inflammatory bowel disease (IBD) is a class of inflammatory diseases of the colon and small intestine. Crohn's disease (CD) and ulcerative colitis (UC) are the principal types of inflammatory bowel disease. Additionally, CD can affect the mouth, esophagus, stomach and anus. 

                                           [9]

                                           [9]

The first case of UC was reported in 1859. Soon after, industrialization started and diets changed drastically. A study connducted in Minnesota looked into the increase of Crohn's disease from 1965 to 2011. In 1965, the prevalence of Crohn's disease was only 28 cases per 100,000 people, increasing almost 100-fold to up to 246 cases in 100,000 people by 2011 [10].

 
                                                              [10]

                                                              [10]

 

Something that can make your gut run amok is when you have more of certain bacterial species and therefore less of other beneficial ones. A so-called imbalance. In fact, scientist found that the microbiome of patients with Crohn’s disease shows such an imbalance. The researchers observed a downregulation of certain classes of bacteria normally found in healthy people and an upregulation of bacteria considered harmful if too abundant [1].

 
                                                                                     [10]

                                                                                     [10]

 


Analysis of the mircobiota in CD patients revealed a reduction in a species of beneficial Firmicutes, especially of Faeclibacterium prausnitzii. The use of F. prausnitzii as a probiotic significantly reduced symptoms of CD, with a reduction in pro-inflammatory cytokines (proteins that signal inflammation) and a increase in anti-infammatory ones [2]. The researchers found that the benefit of F. prausnitzii can be traced back to something that the bacterium secretes (releases). 
Introdution of a Lactobacillus as probiotic supplement had a significant effect on cytokines secretion leading to remission of 31% of the subjects [3]. Something that is rarely achieved by commercial drug treatments of this disease.
Another probiotic product, called VSL#3, contains a cocktail of eight different bacteria (four species of lactobacilli, three species of bifidobacteria, and Streptococcus thermophilus) has been quite extensively evaluated in patients with UC and it was shown that the probiotic cocktaill induces remission in IBD patients. Even more strikingly, when effects of VSL#3 treatment were compared to the highly effective corticosteroid treatment both were observed to be equally effective in reducing inflammatory processes in colonic innate immune cells of UC patients [4].

Toll-like receptor (TLR2) expression before and after probiotics treatment [4]

Toll-like receptor (TLR2) expression before and after probiotics treatment [4]

A clinic trial using bifidobacteria , which are strongly associated with a healthy microbiome, identified an increase in butyrate and other short-chain fatty acids (SCFA)[5]. SCFA are fermentation products of bacteria in our guts. They have a variety of health benefits. If you want to learn more about them, clicke here. 
Additionally, a mix of Bifidobacterium species was found to positively influence relapse rates in IBD and demonstrated a variety of anti-inflammatory effects [6].
A common diet for patients with CD is a easy digestable low-residue diet. A study in 2015 challenged this dogma and ask the patients to change to a high-fiber diet rich in vegetables. More precicesly, the subjects were set on a so-called "semi-vegeterian diet" (SVD), meaning they were allowed to eat dairy products on a daily base but fish and meat only once every week. The results of this study were astonishing, as it shows that even 2 years after the change to a SVD 92% of patients sustained remission, which is defined by being symptoms free [7].

                                Crohn's disease patients on high-fiber diet stay in remission [7]

                                Crohn's disease patients on high-fiber diet stay in remission [7]

A study published in the journal Gut, used the prebiotic Fructooligosaccharide in patients with active CD and observed an increased in the abundance of fecal bifidobacteria, which led to an increase in secretion of anti-inflammatory cytokines [8]. After fructose got a lot of negative press recentely, this study gives another hint why frutctose, if taken up by unprocessed in form from fuits, can be benifical for us after all.

Another feature which is very important when it comes down to overall gut health is the diversity of the microbes. A study from 2004 found that inflammatory bowel diseases are strongly connected to a reduced diversity of the microbiome.They found that the diversity is reduced by 50% in Crohn’s disease and by 30% in Ulcerative Colitis [11].

Ways to Improve Microbial diversity and decrease intestinal permeability

 

 

References

  1. Willing et al., Twin studies reveal specific imbalances in the mucosa-associated microbiota of patients with ileal crohn's disease, Inflamm Bowel Dis, 2009
  2. Sokol et al., Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients, PNAS, 2008
  3. Oliva et al., Randomised clinical trial: the effectiveness of Lactobacillus reuteri ATCC 55730 rectal enema in children with active distal ulcerative colitis, APT, 2011

  4. Ng et al., Immunosuppressive effects via human intestinal dendritic cells of probiotic bacteria and steroids in the treatment of acute ulcerative colitis., Inflamm Bowel Dis., 2010

  5. Kato et al., Randomized placebo-controlled trial assessing the effect of bifidobacteria-fermented milk on active ulcerative colitis K., Alinment Pharmacol, 2004

  6. Hai-Hong et al., Effects of probiotic on intestinal mucosa of patients with ulcerative colitis Hai-Hong, World J Gastroenterol, 2004

  7. Chiba et al., High Amount of Dietary Fiber Not Harmful But Favorable for Crohn Disease, Perm J 2015

  8. Lindsay et al., Clinical, microbiological, and immunological effects of fructo-oligosaccharide in patients with Crohn’s disease, 2006, Gut

  9. http://autoimmunesociety.org/inflammatory-bowel-disease/

  10. Kaplan and Ng, Understanding and Preventing the Global Increase of Inflammatory Bowel Disease

  11. Ott et al., Reduction in diversity of the colonic mucosa associated bacterial microflora in patients with active inflammatory bowel disease, Gut, 2044