In a recent study published in the Journal of Neuroscience, a team of researchers from the University of Calgary found that probiotics might be able to improve the behavioral symptoms of chronic inflammatory conditions by modifying the interaction between the brain and the immune system.
Chronic inflammatory diseases including inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) are associated with behavioural symptoms such as social withdrawal, fatigue and depression. Microbiota are microorganisms that inhabit in the gastrointestinal tract and are responsible for digestion and immune system health. Probiotics are live bacteria and yeasts that are commonly ingested to support the microbiota.
Results from previous studies have shown that probiotics have a positive effect on cognition and mood. However, the underlying mechanisms of this process remains poorly understood, but it is thought to be associated with immunological alterations.
In their study, researchers fed mice with a placebo or with a probiotic combination. To assess behavioural symptoms’ alterations, the time mice spent engaging in social behaviours was compared to the time they spent alone. Results from previous studies have shown that alterations in brain function and behavior is linked to an increase in the production of the inflammatory signaling molecule tumor necrosis factor alpha (TNF-α). As such, researchers also evaluated the levels of TNF-α in the animal’s blood and the amount of TNF-α that was produced by activated immune cells in the brain.
The results revealed that when compared to mice fed with the placebo, those receiving a probiotic mixture spent more time engaging in social behaviours, had lower levels of TNF-α in the blood and fewer activated immune cells in the brain. Probiotics did not change liver inflammation severity.
According to the team, these results indicate that probiotics improved behavioral symptoms by changing the communication between the brain and the immune system. “In the setting of inflammatory disease, eating probiotics may be a novel way to improve the disease-associated symptoms that negatively impact the lives of patients,” study author Mark Swain said in a news release.
According to Keith Kelley from the University of Illinois, the study findings have wider implications for the field. “The global implication of these data is that the gut microbiome can perhaps be manipulated to not only regulate immunity but also to regulate the neural circuitry that affects behavior”, he explained.