Microbial stimulation can overturn age-related decline in cells that are key to fighting infection, a study in mice shows. Image Aged mice have few if any M cells (green) in their intestines reducing their ability to survey the intestine for pathogens. Exposing elderly mice to gut microbes of young mice or to a common bacterial protein reverses the decline of specialised immune cells, research has shown. M cells are specialised cells in the lining of the gut and respiratory tract that act like CCTV cameras, surveying their surroundings for pathogens and are key to initiating immune responses to certain infections. Aged mice have few, if any, M cells and, as a consequence, the immune responses of aged mice are much less effective than in young mice. Treatment of elderly people with a bacterial protein, called flagellin, or a probiotic containing certain bacteria from young individuals, may help their immune system, the results suggest. Restoring immune cells The researchers, led by Professor Neil Mabbott of the Roslin Institute, tested if exposing aged mice to gut microbes from young mice would help recover M cells. They did this by housing elderly mice in contact with bedding that had previously been used by young mice. In an additional experiment, the team treated elderly mice with flagellin, as an alternative method to improve M cell maturation. Both these experiments led to M cells being restored in elderly mice, improving their immune responses to certain pathogens. Human health Further research by the team will determine whether elderly humans also have a similar reduction in M cells, and whether exposure to other bacteria or bacterial components has the same effect as in mice. Ageing has a profound effect on the immune system, resulting in increased incidence and severity of infections and decreased efficacy of vaccinations. Our study suggests that it may be possible to reverse this process through a simple treatment with the bacterial protein flagellin or probiotic containing certain bacteria. Professor Neil MabbottPersonal Chair of Immunopathology, the Roslin Institute The study is published in the journal iScience and it has been funded by the UK Research and Innovation’s Biotechnology and Biological Sciences Research Council and Medical Research Council. ** The Roslin Institute receives strategic investment funding from the Biotechnology and Biological Sciences Research Council and it is part of the University of Edinburgh’s Royal (Dick) School of Veterinary Studies. ** Related links Scientific publication Gut infection can speed development of brain diseases Chicken study probes resistance to food bug
