Finding the needle in the haystack: systematic identification of psychobiotics

Abstract

The brain-gut-microbiota axis is increasingly viewed as a novel paradigm in neuroscience with the capacity to generate innovative therapies for patients with psychiatric illnesses. Psychobiotics, defined as live bacteria, which when ingested in adequate amounts, confer mental health benefits, are increasingly of interest, as preclinical trials continue to show promising results. Particularly in stress-related, anxiety and depressive disorders, there is potential for psychobiotics to deliver new therapies. The question of which microbes may prove to be the most promising psychobiotic in delivering such therapies at a clinical level is of great importance. Here we look at the characteristics of psychobiotics, in an attempt to present an outline from which the identification of potential new psychobiotics may be possible. LINKED ARTICLES: This article is part of a themed section on When Pharmacology Meets the Microbiome: New Targets for Therapeutics? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.24/issuetoc.

Figure 1

The search for psychobiotics. This illustrates the potential pathway for psychobiotic identification. The first step in the process is genome sequencing and comparison with strains known to have psychobiotic potential. Determining the potential to generate short‐chain fatty acids (SCFAs) and tryptophan is a fundamental step in the process, as is the ability to demonstrate anti‐inflammatory activity and have an effect on the intestinal barrier function. Behavioural studies in animals precede any human intervention studies.

Figure 2

The gut–brain axis. Comparison between a healthy gut–brain system and an abnormal system. In negative affective states such as stress, anxiety or depression, the expression of pro‐inflammatory markers increases, gut microbiota and gut permeability are altered and the gut–brain axis is in a state of dysbiosis.