Episode 6 of The Microbiome Podcast: The microbiome, autism, and serotonin production with Dr. Elaine Hsiao

The sixth episode of The Microbiome Podcast is now available. We had a great chat with Dr. Elaine Hsiao, a new professor at California Institute of Technology. Elaine was the first author on the seminal paper from 2013 that showed a connection in mice of the microbiome and autism spectrum disorder related behaviors. We talked with her about that work as well as more recent work that she published from her own laboratory describing the microbiome’s role in regulating serotonin production.

Listen to the podcast here on our website. Here on iTunes. And here on Stitcher. 

Below are more detailed show notes:

• (2:20) Last week’s guests Erica and Justin Sonnenburg were featured in a New York Magazine article. Read the article. 
• (3:48) The Gates Foundation’s Grand Challenges in Global Health launched a grand challenge titled Addressing Newborn and Infant Gut Health Through Bacteriophage-Mediated Microbiome Engineering. Learn more. 
• (6:22) uBiome launched a clinical laboratory. Read more. 
• (7:56) Second Genome partnered with the University of Cork in Ireland to develop therapies for inflammatory bowel diseases. Read more.
• (9:02) Dupont recently acquired Taxon Biosciences, a microbiome company. Read more. 
• (11:15) A caller asked how long his microbiome would take to recover to it’s previous state after taking antibiotics. We based the answer on a paper by David Relman published in 2010. Read the paper.
• (16:19) We start the interview with Elaine Hsiao. Check out her laboratory webpage.
• (18:00) We talked with Elaine about her seminal paper on the microbiome and it’s possible connection to autism spectrum disorders. Read the paper.
• (31:06) We talked with Elaine about her recent paper showing that gut bacteria are important for production of serotonin. Read the paper.

We will be back in two weeks with Drs. Eugene Chang and Vanessa Leone from the University of Chicago discussing how the microbiome may be involved in the complex relationship between disruptions to circadian rhythms and obesity. Please call in with any questions for Bill and David or for Drs. Chang and Leone to 518-945-8583. 

The role of the gut microbiome in Down Syndrome

Down Syndrome is the most common genetic cause of intellectual disability and occurs when there is an extra 21st chromosome, trisomy 21. Down Syndrome patients often experience premature aging and are therefore at early risk for age-related conditions like Alzheimer’s disease. Scientists from Italy published a study in November in PLOS One that compared the gut microbiome of Down Syndrome patients with that of healthy individuals.

The scientists hypothesized that the gut microbiome of Down Syndrome (DS) patients was contributing to the aging of the patients and would present similarly to the microbiome of an aged individual. They compared the gut microbiome of 17 patients with DS with previously published data for 16 age-matched individuals as well as 5 elderly individuals and 3 individuals who were 100 years old.  Interestingly, they found that the microbiomes of patients with DS were very similar to the microbiomes of healthy individuals. In this case, their hypothesis did not end up as they predicted. 

It is important to note that this study only included 17 test subjects who were all under the age of 35.  Future studies will need to be conducted with larger patient cohorts as well as older patients to truly get a good understanding of the gut microbiome profiles of the entire population of patients and better understand this hypothesis. 

There was, however, an unexpected finding that I found to be quite interesting. While the general makeup of the DS patients' microbiomes were similar to those of healthy individuals, there were subpopulations of bacteria that were more or less abundant in DS patients. Individuals with DS had elevated levels of Parasporobacterium and Sutterella and reduced levels of Veilonellaceae. This increase of Sutterella and decrease of Veilonellaceae has previously been described in autistic children with stomach problems. Specifically in this study, Sutterella abundance was positively correlated with Aberrant Behavior Checklist (ABC) scores for the DS individuals. The ABC test is a 58 item report checklist used to assess maladaptive behavior in people with developmental disabilities. 

This positive correlation tells us that this bacterium in the gut may play a role in maladaptive behavior in patients with various conditions. Although the original hypothesis was not confirmed, this very interesting result will need to be further explored to better understand the role of the gut microbiome in individuals with autism spectrum disorder and Down Syndrome.