Viruses living in the human gut may help regulate stress, research suggests
Viruses are widely considered harmful to our health, but a subset of viruses that live in the gut could play a crucial role in regulating stress, research suggests.
The discovery adds to mounting evidence that interactions between the gut and the brain influence human behavior, and could ultimately lead to new treatments for stress-related conditions that target the vast community of viruses living within us.
Although previous studies have suggested that the composition of microbes living in the gut changes in response to stress, these have largely focused on bacteria, rather than this ‘virome’.
“The way the virome interacts with bacteria, and how these influence stress-related health and disease status, is largely unexplored,” says Dr Nathaniel Ritz from the APC Microbiome Ireland research center at University College Cork. “Our research opens the possibility of targeting the virome to treat and reduce the effects of stress.”
Ritz and his colleagues focused on a subset of viruses called bacteriophages, which infect bacteria and multiply alongside them. They studied what happened to these viruses when the mice they lived in were exposed to chronic social stress, such as living alone or in overcrowded conditions, and found that exposure to stress led to changes in the composition of the viruses and bacteria in the animals . intestines.
They then collected viruses from the feces of healthy animals that were not under stress and transplanted them back into them after exposing the mice to chronic social stress. The research, published in Natural microbiologysuggested that these transplants reduced levels of stress hormones and curbed depression- and anxiety-like behavior in the mice.
Although further research is needed to assess whether virus transplants are beneficial for people suffering from stress-related conditions, the study provides some of the first evidence that intestinal viruses are involved in the response to stress, and that manipulating them could have therapeutic benefits.
“Given that the composition of the virome varies widely from person to person, this could open the door to personalized therapeutics for stress-related conditions in the future,” says Prof. John Cryan of APC Microbiome Ireland, who led the research. “One thing is for sure: we need to recognize that not all viruses are bad and that they can play a key role in keeping the bad bacteria in our gut at bay, especially during times of stress.”