US – The injections of the bacterium Mycobacterium vaccae, which lives naturally in soil, help to recover from stress and improve behavior in mice, according to a new study published in the journal Proceedings of the National Academy of Sciences.

Researchers from University of Colorado (US) found that M.vaccae also prevented the development of colitis by stress, a typical symptom of induced inflammatory bowel disease (IBD), suggesting that immunization with bacteria they can have a wide range of health benefits.

“The immunized mice responded with a pattern of confrontation to more proactive stress, a strategy that has been associated with the resilience of stress in animals and humans,” said Christopher Lowry, associate professor in the Department of Integrative Physiology professor the University of Colorado and the principle investigator of the research.

The team found that mice given a high dose of the bacteria had about half of behaviors of escape and stress against aggression than mice that were not treated, only during the first hour of experiment.

Immunized mice continued to show decreased levels of submissive behavior of one to two weeks after treatment.

The data disclosed on colitis, measured by cellular damage in the colon, also experienced a 50% improvement compared to animals that had not been exposed to the bacteria.

The research highlights the importance of the microbiome of a body to prevent and cope with diseases related to inflammation and psychiatric diseases.

“An injection of M.vaccae is not designed to target a particular antigen in the way you would a vaccine, but in its active place immunoregulatory responses of the individual to protect it from inappropriate inflammation,” Lowry said.

The well-known “hygiene hypothesis” holds that health habits, use of antibiotics and changes in diet in the modern era have greatly reduced human exposure to environmental bacteria and other immunoregulatory organisms, thus reducing diversity human microbiome and its ability to deal with certain diseases.

The lack of exposure to these organisms is thought to contribute to the current epidemic of inflammatory diseases in modern urban societies.

“We continue to see how these naturally occurring bacteria can modulate the immune system in ways that might be beneficial for humans,” said Lowry.