Summary: A new study reveals an association between gut microbiota and brain regions responsible for processing sensory information in those with IBS.
A new study by researchers at UCLA has revealed two key findings for people with irritable bowel syndrome about the relationship between the microorganisms that live in the gut and the brain.
For people with IBS research shows for the first time that there is an association between the gut microbiota and the brain regions involved in the processing of sensory information from their bodies. The results suggest that signals generated by the brain can influence the composition of microbes residing in the intestine and that the chemicals in the gut can shape the human brain’s structure.
Additionally, the researchers gained insight into the connections among childhood trauma, brain development and the composition of the gut microbiome.
Previous studies performed in mice have demonstrated effects of gut microbiota on brain function and behavior, as well as the influence of the brain on the composition of microbes in the gut. However, to date, only one study performed in human subjects has confirmed the translatability of such findings to the human brain.
Studies have also reported evidence for alterations in the composition of gut microbiota in people with irritable bowel syndrome, but there has been little consistency among studies regarding the specific microbial alterations and the relationship of such alterations with the cardinal symptoms of IBS, recurring abdominal pain and altered bowel habits.
In relation to a person’s history with childhood trauma, it has been shown to be associated with structural and functional brain changes; trauma in young children has also been shown to alter gut microbial composition. But how they are related has been unknown.
The UCLA researchers collected behavioral and clinical measures, stool samples and structural brain images from 29 adults diagnosed with IBS, and 23 healthy control subjects. They used DNA sequencing and various mathematical approaches to quantify composition, abundance and diversity of the gut microbiota. They also estimated the microbial gene content and gene products of the stool samples. Then the researchers cross-referenced these gut microbial measures with structural features of the brain.
Based on the composition of the microbes in the gut, the samples from those diagnosed with IBS clustered into two subgroups. One group was indistinguishable from the healthy control subjects, while the other differed. Those in the group with an altered gut microbiota had more history of early life trauma and longer duration of IBS symptoms.
The two groups also displayed differences in brain structure.
Analysis of a person’s gut microbiota may become a routine screening test for people with IBS in clinical practice, and in the future, therapies such as certain diets and probiotics may become personalized based on an individual’s gut microbial profile. At the same time, subgroups of people with IBS distinguished by brain and microbial signatures may show different responsiveness to brain-directed therapies such as mindfulness-based stress reduction, cognitive behavioral therapy and targeted drugs.
A history of early life trauma has been shown to be associated with structural and functional brain changes and to alter gut microbial composition. It is possible that the signals the gut and its microbes get from the brain of an individual with a history of childhood trauma may lead to lifelong changes in the gut microbiome. These alterations in the gut microbiota may feed back into sensory brain regions, altering the sensitivity to gut stimuli, a hallmark of people with IBS.
The authors of the study are Jennifer Labus, Dr. Jonathan Jacobs, Arpana Gupta, Jonathan Acosta, Elaine Hsiao, Dr. Kirsten Tillisch, and Dr. Emeran Mayer, all of UCLA; Emily Hollister, Numan Oezguen, Ruth Ann Luna, Dr. Kjersti Aagaard, Dr. James Versalovic and Tor Savidge of Baylor College of Medicine; and Kyleigh Kirbach of Washington University.
Funding: The National Institute of Diabetes and Digestive and Kidney Diseases and the National Center for Complementary and Alternative Medicine funded this research.
Source: Enrique Rivero – UCLA
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “Differences in gut microbial composition correlate with regional brain volumes in irritable bowel syndrome” by Jennifer S. Labus, Emily B. Hollister, Jonathan Jacobs, Kyleigh Kirbach, Numan Oezguen, Arpana Gupta, Jonathan Acosta, Ruth Ann Luna, Kjersti Aagaard, James Versalovic, Tor Savidge, Elaine Hsiao, Kirsten Tillisch and Emeran A. Mayer in Microbiome. Published online May 1 2017 doi:10.1186/s40168-017-0260-z
Differences in gut microbial composition correlate with regional brain volumes in irritable bowel syndrome
Preclinical and clinical evidence supports the concept of bidirectional brain-gut microbiome interactions. We aimed to determine if subgroups of irritable bowel syndrome (IBS) subjects can be identified based on differences in gut microbial composition, and if there are correlations between gut microbial measures and structural brain signatures in IBS.
Behavioral measures, stool samples, and structural brain images were collected from 29 adult IBS and 23 healthy control subjects (HCs). 16S ribosomal RNA (rRNA) gene sequencing was used to profile stool microbial communities, and various multivariate analysis approaches were used to quantitate microbial composition, abundance, and diversity. The metagenomic content of samples was inferred from 16S rRNA gene sequence data using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). T1-weighted brain images were acquired on a Siemens Allegra 3T scanner, and morphological measures were computed for 165 brain regions.
Using unweighted Unifrac distances with hierarchical clustering on microbial data, samples were clustered into two IBS subgroups within the IBS population (IBS1 (n = 13) and HC-like IBS (n = 16)) and HCs (n = 23) (AUROC = 0.96, sensitivity 0.95, specificity 0.67). A Random Forest classifier provided further support for the differentiation of IBS1 and HC groups. Microbes belonging to the genera Faecalibacterium, Blautia, and Bacteroides contributed to this subclassification. Clinical features distinguishing the groups included a history of early life trauma and duration of symptoms (greater in IBS1), but not self-reported bowel habits, anxiety, depression, or medication use. Gut microbial composition correlated with structural measures of brain regions including sensory- and salience-related regions, and with a history of early life trauma.
The results confirm previous reports of gut microbiome-based IBS subgroups and identify for the first time brain structural alterations associated with these subgroups. They provide preliminary evidence for the involvement of specific microbes and their predicted metabolites in these correlations.
“Differences in gut microbial composition correlate with regional brain volumes in irritable bowel syndrome” by Jennifer S. Labus, Emily B. Hollister, Jonathan Jacobs, Kyleigh Kirbach, Numan Oezguen, Arpana Gupta, Jonathan Acosta, Ruth Ann Luna, Kjersti Aagaard, James Versalovic, Tor Savidge, Elaine Hsiao, Kirsten Tillisch and Emeran A. Mayer in Microbiome. Published online May 1 2017 doi:10.1186/s40168-017-0260-z