Whole Metagenome Analysis Helps Identify Depressive Gut Microbe

In a three-year study, researchers from Skoltech, the RAS Vavilov Institute of General Genetics, Moscow Mental Health Clinic No. 1 named after NA Alexeev, and the Federal Medical Research Center of Psychiatry and Serbsky’s Narcology examined how gut microbes in patients with major depressive disorder are different from those in mentally healthy people. After analyzing all the genes present in the gut microbiome, the team identified one particular bacterium – Faecalibacterium prausnitzii —responsible for the largest functional gap between healthy and depressed datasets. The findings, which hold promise for express mental health diagnostics and “psychobiotic” medications, are reported in Biomedicines.

If you know which genes are more or less represented in depressed patients compared to the healthy population, and which bacteria are responsible, you can try to do two things. First, you can use faecal microbiota analysis as a complementary tool to diagnosing mental disorder. Second, you can try to develop drugs that would “normalize” the gut microbiome in depressed patients. »

Alexey Kovtun, Study Lead Author, Biological Research Intern, Skoltech

To identify the “depressing” gut germs, the researchers performed a so-called complete metagenome analysis. That is, they recovered and sequenced the entire bacterial DNA from fecal samples of a cohort of patients diagnosed with major depressive disorder and a cohort of individuals in good mental health. “The result is that we know both which genes and which bacterial species are present in each group’s microbiome, and how well they are represented,” Kovtun said.

The next step is to identify the set of genes that vary widely between healthy individuals and those with mental disorders and zoom in on those particular genes to find out which of the bacteria that carry them are actually overrepresented or underrepresented in the microbiome of depressed patients. .

One particular bacterium really stood out. It is called Faecalibacterium prausnitzii, and it is significantly less abundant in the gut of patients with major depressive disorder. We have linked it to three groups of genes that are strongly underrepresented in the metagenome of the microbiome of these patients.

Alexei Kovtun

The first of three sets of notable genes is involved in the production of the hormone melatonin, which regulates the sleep-wake cycle. The second is associated with the formation of the classic neurotransmitters glutamate and gamma-aminobutyric acid. The third is made up of several genes responsible for the synthesis of short-chain acids, the deficiency of which has been linked to depression.

According to the authors of the article, the microbe whose study highlights the role – Faecalibacterium prausnitzii — is attracting increasing attention from researchers in the development of therapeutic options and diagnostic approaches for various diseases based on certain bacterial strains. The professional community is enthusiastic about this bacterium.

Hopefully, it might prove useful as a target for express test kits for diagnosing mental disorders and psychobiotic drugs that promote mental well-being by harmonizing the patient’s microbiome. We hear a lot about prebiotics and probiotics – well, psychobiotics could be the next big thing, and our team is part of the global effort to make it a reality.

Alexei Kovtun

The study reported in this article featured researchers from the RAS Vavilov Institute of General Genetics, Skolkovo Institute of Science and Technology, Moscow Institute of Physics and Technology, Clinic No. 1 mental health center named after NA Alexeev, of the Serbsky Federal Center for Medical Research in Psychiatry. and Narcology, Moscow State University of Food Production and Caspian University.