The connection comes as the Babraham Institute in Cambridge show how faecal microbial transplants (FMT) from young mice replenish the gut microbiome and strengthens the gut immune system in older mice.
The study also suggests that the age-related decline in the gut immune response is reversible and can be improved upon in older individuals.
“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," said study lead researcher Dr Marisa Stebegg.
"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 research team put forward a hypothesis that dysbiosis of the intestinal microbiome in older individuals may be driven by altered cross-talk between the host immune system and the microbiota.
Germinal centres – structures of importance in immune system function, may play a role in microbiome regulation. Previous studies have shown GC reactions may causally influence the microbiome.
However, the mechanism is not fully understood with the direction of causation unclear in gut-associated defects seen with advancing age in the GC reaction and gut microbiota.
The team began by co-housing young and aged mice, 4-6 in number in which they relied on mice naturally sampling the faecal pellets of other mice.
The team then went on to perform a direct faecal transfer from young to aged mice, which they found boosted the gut immune system in the aged mice, partly correcting the age-related decline.
"To our surprise, co-housing rescued the reduced gut immune response in aged mice,” said Dr Michelle Linterman, group leader in the Immunology programme at the Babraham Institute.
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."
“Our results indicate that replenishing the microbiome of aged mice with that of a younger animal can boost the local GC reaction, which may have implications for the overall health of the organism,” the study added.
“This makes the gut microbiome a possible target for the treatment of a range of age-associated symptoms.
“FMT, probiotics, co-habitation and diet all have an impact on the composition of the gut microbiome and could prove to be innovative interventions to facilitate healthy ageing.”
Consistent with the study’s findings, the team noted research that found the remodelling of the gut microbiome in Drosophila melanogaster might increase lifespan.
Similarly, middle-aged killifish colonised with a young microbiome appeared to live longer than untreated fish and bacterial-derived indoles were shown to increase the lifespan of mice.
Additional studies show that supplementation of older humans or mice with prebiotics and probiotics results in changes of gut microbial composition and can improve gut immunity in older individuals.
Furthermore, the transfer of a young microbiome into aged mice increases protection against C. difficile infection, indicating that the microbiota of young animals can functionally boost intestinal protection.
Source: Nature Communications
Published online: doi.org/10.1038/s41467-019-10430-7
“Heterochronic faecal transplantation boosts gut germinal centres in aged mice.”
Authors: Marisa Stebegg et al.