Babraham Institute study suggests faecal transplants could be the key to healthy ageing
It is a curious trait of the mouse that it naturally likes to sample the faecal pellets of other mice.
This coprophagia, which is not unique to the species, might strike us as grotesque but there is clear evidence it has a beneficial effect for them.
A study by immunologists at the Babraham Institute found that cohousing young and aged mice led to the replenishment of the gut microbiome and a boost to the gut immune system in the older animals.
They further proved this by - wait for it - conducting faecal transplants from young to aged mice, a somewhat delicate process that partly corrected the age-related decline in the health of the gut immune response.
The gut is one of the organs worse affected by ageing.
As we grow older, changes to our own gut microbiome - the ecosystem of organisms living inside us that can weigh a total of 2kg - are linked to frailty, inflammation and increased susceptibility to intestinal disorders.
The Babraham study has shown, for the first time, this is directly linked to the decline in function of the gut immune system.
Lead researcher Dr Marisa Stebegg said: “Our gut microbiomes are made up of hundreds of different types of bacteria and these are essential to our health, playing a role in our metabolism, brain function and immune response.
“Our immune system is constantly interacting with the bacteria in the gastrointestinal tract. As immunologists who study why our immune system doesn’t work as well as we age, we were interested to explore whether the make-up of the gut microbiome might influence the strength of the gut immune response.”
The study on mice, published in Nature Communications, shows that the decline in this response can be reversed.
Dr Michelle Linterman, group leader in the immunology programme at the Babraham Institute, added: “To our surprise, co-housing rescued the reduced gut immune response in aged mice. Looking at the numbers of the immune cells involved, the aged mice possessed gut immune responses that were almost indistinguishable from those of the younger mice.”
With the right stimuli, the clock can be turned back, findings that have implications for age-related conditions.
A 2011 study in America found that swapping faecal bacteria from mice with resistance to Citrobacter rodentium - an E. coli like bacterium - could help save the lives of those who would typically succumb it.
Following this latest study, the good news - if you can call it that - is that faecal transplants, probiotics, co-habitation and diet could all help facilitate healthy ageing.
There are, in fact, reasons why some people have engaged in the somewhat horrifying process of transplanting poo - such as seeing off a potentially deadly case of Clostridium difficile (C. difficile), which can overwhelm our bowels, lead to constant diarrhoea and be difficult to treat with antibiotics.
A trans-poo-sion, as it has also been known, involves taking part of a stool from one person - and given to the other, either rectally or (gulp) orally. Normally, the donor is a relative, as they will have similar gut microbiota.
The aim is to restore a healthy colony of bacteria. There is, of course, the obvious danger of transplanting disease-causing microbes.
This latest study is further evidence that developing a poo-in-a-pill, or other method of harnessing healthy gut microbiota, could have a positive impact.