How does microbiome affect Crohn’s disease?
The intestinal microbiota, also called the intestinal flora, is composed of millions of micro-organisms, including bacteria, which live in perfect harmony when everything is going well.
As a whole, environmental factors play a crucial role in Crohn’s disease. Microbiota itself works under a genetic and environmental influence and sufferers’ microbiota is found to be unstable and very sensitive to environmental variations, but research is not advanced enough yet to offer solutions.
Crohn’s disease involves inflammation of the intestinal lining.
But is there a link between this disease and our microbiota? Read on to learn what scientists have discovered.
Table of Contents
- 1 How does microbiome affect Crohn’s disease? Introduction
- 2 Crohn’s disease is a digestive autoimmune disease
- 3 What is the microbiota and what is its role?
- 4 What are the links between Crohn’s disease and our microbiome?
- 5 Can we act on the intestinal flora to improve Crohn’s disease?
- 6 Treatment of dysbiosis and Crohn’s disease
- 7 How does microbiome affect Crohn’s disease? Conclusion
How does microbiome affect Crohn’s disease? Introduction
The intestinal flora provides many services to our body by contributing to digestion, metabolism, immunity, and even the management of stress and emotions.
However, a slump can quickly be felt when our intestinal microbiota is unbalanced.
Today, research has been conducted to determine if there is a link between Crohn’s disease and the gut microbiota.
In this article, we will discover together if an imbalance of our intestinal flora can favor the appearance of this disease.
Crohn’s disease is a digestive autoimmune disease
Rectocolic hemorrhagic disease and Crohn’s disease are the primary chronic inflammatory bowel diseases in humans.
Crohn’s disease evolves in flare-ups interspersed with remissions. It affects mainly the colon and the terminal part of the small intestine.
However, this disease can also affect all segments of the digestive tract. For example, anorectal damage is quite common.
The frequency of Crohn’s disease is highest in Western countries.
The peak of the disease is between 20 and 30 years old, but it is possible to have this disease at any age.
Sometimes, digestive lesions are associated with inflammatory lesions of the joints and skin.
Regarding the identified risk factors, we can mention:
- The existence of a family factor that multiplies by three the risk of developing the disease
- The harmful role of smoking on the risk and severity of Crohn’s disease
- And finally, the probable involvement of intestinal dysbiosis.
Some populations from areas of the world where the disease is rare and migrate to a high-risk area quickly take on the risk of the host country.
Therefore, this shows the significant role of environmental factors in the risk of Crohn’s disease.
The disease, which often appears following a genetic predisposition, is due to a hyperactivity of the digestive immunity.
The latter is favored by abnormalities in the permeability of the intestinal barrier, which would come from a bacterial translocation.
Lymphocytes derived from patients with Crohn’s disease are abnormally reactive, secreting excessive pro-inflammatory cytokines when exposed to certain bacteria.
Source: Cadwell, et al., Virus-Plus-Susceptibility Gene Interaction Determines Crohn’s Disease Gene Atg16L1 Phenotypes in Intestine, Cell, 2010
What is the microbiota and what is its role?
By definition, the microbiota refers to all the micro-organisms present in our digestive tract and play an essential role in our own physiology.
Indeed, these micro-organisms are mainly represented by bacteria, fungi and viruses.
Studies estimate at least ten times more bacteria in the gut than cells in our bodies.
In addition, research also estimates that the genetic capabilities of our microbiota are more than 100 times greater than those of the human genome.
Our microbiota plays a role in many biological processes. Indeed, it plays a role in:
- Energy regulation
- The production of vitamins and specific fatty acids
- The development of the immune system, even outside the gut, or in the defenses against intestinal infections.
The microbiota also plays a role in brain function through different pathways.
For example, this is the case with metabolites produced by bacteria that pass through the bloodstream and reach the brain.
There is also a direct connection between the gut and the brain involving nerves stimulated by gut receptors.
What are the links between Crohn’s disease and our microbiome?
As previously discussed, Crohn’s disease is a chronic inflammatory bowel disease that can affect any part of the digestive tract, from the mouth to the anus.
This chronic inflammation of the intestinal mucosa, which most often occurs in young people, evolves in bouts, causing symptoms such as diarrhea, abdominal pain and fever that can seriously affect one’s daily life.
Crohn’s disease is multifactorial, meaning that besides involving genetic and environmental factors, it affects intestinal microbiota, which is itself under a genetic and environmental influence.
In addition, Crohn’s disease is also thought to be related to an abnormal response of the intestinal immune system.
Today, many studies are trying to understand the exact role of the intestinal microbiota and its involvement in this intestinal disease, hoping to find treatments that will cure or prevent the symptoms of this disease.
Can we act on the intestinal flora to improve Crohn’s disease?
This area is still in the research stage. However, given the evidence available and the microbiota playing an essential role in our general physiology, it is not surprising that its degradation impacts intestinal diseases.
Studies have observed that the microbiota is abnormal in its bacterial composition in inflammatory diseases (including Crohn’s disease).
Indeed, some bacteria were in greater quantity at the expense of others.
But these bacteria in large quantities have a pro-inflammatory activity, while those in smaller amounts are more anti-inflammatory.
Therefore, therapeutic strategies have been devised and implemented to correct this bacterial imbalance in the gut.
For example, one strategy has suggested bringing the missing type of bacteria into the gut. In contrast, other processes think of using flora transplantation.
Another strategy would be identifying molecules produced by intestinal bacteria with anti-inflammatory properties and then using them as drugs.
The microbiota and Crohn’s disease
Decreased intestinal diversity is one of the hallmarks of the intestinal dysbiosis present in Crohn’s disease, with approximately a 25% decrease in the number of bacterial species.
Beneficial bacteria such as Faecalibacterium prausnitzii (with anti-inflammatory and analgesic properties) and Roseburia spp., producer of butyrate (a short-chain fatty acid necessary for the good quality of the intestinal barrier), are deficient in Crohn’s disease patients.
Moreover, the intestinal microbiota of these patients is unstable and very sensitive to environmental variations.
The intestinal flora is marked by an increase in hydrogen sulfide-producing bacteria, which aggravate the damage to the intestinal barrier by a direct toxic action on the intestinal epithelial cells and diminishes the beneficial effects of butyrate on these cells.
In addition to all these anomalies, there is an abnormally high concentration of pathogenic bacteria such as Escherichia coli.
Studies suspect mycobiont (yeast) abnormalities in the activation of immunity reported in Crohn’s disease. However, this area is still in the exploration stage.
Source: Sartor & Wu, Roles for Intestinal Bacteria, Viruses, and Fungi in Pathogenesis of Inflammatory Bowel Diseases and Therapeutic Approaches, Gastroenterology, 2017
Treatment of dysbiosis and Crohn’s disease
Some studies have tried to find different treatments to cure Crohn’s disease and possible intestinal dysbiosis.
Dietary measures for Crohn’s disease
Research has been conducted by testing dietary interventions to treat active Crohn’s disease or prevent relapse in patients in remission.
However, the diversity of dietary interventions tested and the variety of diets of the groups tested made it difficult to interpret the results.
Indeed, none of the interventions tested (such as a diet rich in fiber and low in refined sugars, free of micro and nanoparticles, rich in calcium, and organic food) has shown effectiveness in the remission of the active disease or in the prevention of relapses.
Source: Durchschein, et al., Diet therapy for inflammatory bowel diseases: The established and the new, World Journal of Gastroenterology, 2016
Taking probiotics for Crohn’s disease
Other studies have attempted to test the efficacy of probiotics in the remission of relapses of the disease or in the prevention of new relapses.
However, the results showed too moderate an improvement to affirm the effectiveness of these probiotic treatments in adults.
However, it would appear that the benefit of probiotics is much more significant in childhood Crohn’s disease.
Source: Derwa, et al., Systematic review with meta-analysis: the efficacy of probiotics in inflammatory bowel disease, Alimentary Pharmacology & Therapeutics, 2017
Fecal transplantation for Crohn’s disease
Fecal transplantation in active Crohn’s disease increases the diversity and density of the intestinal flora.
These changes are accompanied by increased regulatory T cells, reducing immunological hyperactivity and bringing clinical improvement.
Studies have shown that fecal transplantation allows remission of the disease in one-third of cases (slightly more in children than adults).
In severe forms associated with inflammatory masses in the abdomen, repeated fecal transplants have improved the patient’s condition in nearly 70% of cases.
In the future, it would be interesting to conduct research that would determine the respective places of fecal transplantation and anti-inflammatory and immunological treatments for Crohn’s disease.
Source: Fang, et al., Protocol for Fecal Microbiota Transplantation in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis, BioMed Research International, 2018
What are the results and current dietary recommendations?
Currently, there is no specific dietary recommendation for Crohn’s disease.
Many studies have been conducted concerning probiotics because there is a potentially large market.
However, none of the classical probiotics (lactic ferments) have shown apparent efficacy in human studies.
Only two probiotics had a small effect in the minimal form of ulcerative colitis.
But today, there is insufficient evidence to use them instead of conventional treatments for chronic inflammatory bowel diseases.
Source: Derikx, et al., Probiotics and prebiotics in ulcerative colitis, Best Practice & Research Clinical Gastroenterology, 2016
How does microbiome affect Crohn’s disease? Conclusion
Crohn’s disease is one of those intestinal diseases that can be disabling in our daily lives.
Indeed, symptoms such as diarrhea or stomach aches can be embarrassing in certain situations. So how does microbiome affect Crohn’s disease?
Currently, there is a lot of research that tries to link our gut microbiota to this disease.
In both cases, our intestinal flora is unbalanced, and it is essential to find a treatment that would improve the lives of people with this disease.
In the future, it is not excluded that we will be able to better understand the effect of food on the microbiota and the consequences on our health.
For example, one could imagine new generation probiotics that would come from the intestine and would be selected for their anti-inflammatory properties.