Microbiome Bites February 27th: New Insights on the Microbiome in Crohn’s disease and Autism Spectrum Disorders

Crohn's disease | Microbiome

We're keeping it short this week with two papers looking at the role of the gut microbiome in Crohn's disease and autism spectrum disorders.


1.  The Distinct Microbiome Dysbiosis of Crohn’s Disease Does Not Occur in Healthy Relatives

Crohn’s disease is a complex disorder with both genetic and environmental factors linked to its onset. A distinct gut microbiome dysbiosis is found in Crohn’s patients and is generally believed to be a part of the cause. There is now a need to move from describing the composition of the microbiome associated with various disease states to understanding the function of the microbiome in either the initiation or progression of disease.

Toward this end, a study published this week in the journal PLoS ONE seeks to explore the functionality of the microbiome in Crohn’s disease. The study compares the gut microbiomes of Crohn’s patients with their unaffected relatives. The study reveals that the distinct microbiome dysbiosis seen in Crohn’s patients is much less frequent in their healthy relatives. This finding leads the authors to conclude that the loss of the “normal” healthy microbiome occurs close to the disease onset or is a secondary effect of the illness.

This study is a great step in the right direction, but suffers from a relatively small sample size. The key to understanding the development of the disease most likely lies in understanding what happens during the transition stage, from healthy to diseased.

You can read the study here.


2. New Evidence on the Altered Gut Microbiome in Autism Spectrum Disorders

Autism spectrum disorders (ASD) are neurodevelopmental conditions that affect behavior and social awareness. As with many neurological disorders (such as Parkinson’s disease or ALS), ASD patients frequently suffer with a gastrointestinal disorder, which implies that there is a role that the gut microbiome plays.

In a study published in the journal Microbiome this week, researchers analyzed the gut microbiomes of autistic individuals. The team found a significant increase in the Firmicutes/Bacteroidetes ratio in autistic patients, due to a decrease in the general numbers of Bacteroidetes. Quite unusually for this type of study, the team found that the amount of the fungus Candida was more than double in the autistic patients.

The authors speculate that, “since the two different microbial communities (fungi and bacteria) mutually influence each other, reduced early life encounters with foodborne and environmental bacteria and fungi in urban areas of the globalized world could be a cause of the increased colonization with some major commensals, such as Candida and E. coli.

You can read the study here.