Johns Hopkins Medicine researchers have discovered an immune cell in the intestine that affects the gut microbiome, which can impact brain functions associated with depression.
Published in Nature Immunology, the study found that targeting these immune cells with medication or therapy may be possible to develop new treatments for depression.
“The results of our study highlight the previously unrecognized role of intestinal gamma delta T cells (γδ T cells) in modifying psychological stress responses, and the importance of a protein receptor known as dectin-1, found on the surface of immune cells, as a potential therapeutic target for the treatment of stress-induced behaviors,” said Atsushi Kamiya, MD, PhD, professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study’s senior author.
According to researchers, Dectin-1, a receptor, binds to specific proteins or antigens to activate immune cells in a particular manner. The receptor might be involved in immune-inflammatory responses and microbiome changes in the colon of mice, implying its role in stress responses through γδ T cells in the intestinal immune system.
Kamiya and the team investigated the relationship between gut microbiota imbalance and stress-induced behaviors related to depression.
The findings indicated that stress-susceptible mice had lower microbial diversity in their intestines than stress-resilient mice. The stressed mice were also lacking in the beneficial bacteria Lactobacillus johnsonii.
To gain insight into human brain responses, the researchers examined the gut microbiota of people with major depressive disorder (MDD) and non-depressed people. The study enrolled 66 participants aged 20 years or older, from June 2017 to September 2020, recruited from three hospitals in Tokyo, Japan.
“Despite the differences in intestinal microbiota between mice and humans, the results of our study indicate that the amount of Lactobacillus in the gut may potentially influence stress responses and the onset of depression and anxiety,” says Kamiya.
Zhu, X., Sakamoto, S., Ishii, C. et al. Dectin-1 signaling on colonic γδ T cells promotes psychosocial stress responses. Nat Immunol, 2023 DOI: 10.1038/s41590-023-01447-8
Johns Hopkins Medicine. (2023, March 20). New evidence: Immune system cells in the gut linked to stress-induced depression. ScienceDaily. Retrieved March 24, 2023 from www.sciencedaily.com/releases/2023/03/230320143713.htm