The study advocates analyzing intestinal bacteria to predict health outcomes as people age. The researchers found changes within intestinal microbes that precede and predict the death of fruit flies. The findings were published in the open-source journal Cell Reports and reported in Bioscience Technology.
According to David Walker, a UCLA professor of integrative biology and physiology, and senior author of the research, “Age-onset decline is very tightly linked to changes within the community of gut microbes. With age, the number of bacterial cells increase substantially and the composition of bacterial groups changes.”
The researchers used fruit flies in part because although their typical life span is just eight weeks, some live to what would be the equivalent of humans’ 80s and 90s, while others age and die much younger. Also, scientists have identified all of the fruit fly’s genes and know how to turn individual genes on and off. Previously, the UCLA researchers found that five or six days before flies died, their intestinal tracts became more permeable and started leaking.
In the new study, which analyzed more than 10,000 female flies, the scientists discovered that they could detect bacterial changes in the intestine before the leaking started. Some fruit flies were given antibiotics that significantly reduce bacterial levels in the intestine. These antibiotics prevented the age-related increase in bacteria levels and improved intestinal function during aging. The biologists also demonstrated that reducing bacterial levels in old flies can considerably prolong their life span.
As Walker said, “When we prevented the changes in the intestinal microbiota that were linked to the flies’ imminent death by feeding them antibiotics, we dramatically extended their lives and improved their health. Microbiota are the bacteria and other microorganisms that are abundant in humans, other mammals, fruit flies and many other animals.”
When flies had leaky intestines and were given antibiotics, they lived an average of 20 days after the leaking began, a big part of the fly’s life span. If flies with leaky intestines did not receive antibiotics, they died within a week. The intestine provides a barrier that protects organs and tissue from environmental damage.
“The health of the intestine — in particular the maintenance of the barrier protecting the rest of the body from the contents of the gut — is very important and might break down with aging,” said Rebecca Clark, the study’s lead author, who was a UCLA postdoctoral scholar when the research was conducted and is now a lecturer at England’s Durham University.
“One of the big questions in the biology of aging relates to the large variation in how we age and how long we live,” said Walker, who added that scientific interest in intestinal microbes has exploded in the last five years. When a fruit fly’s intestine begins to leak, its immune response increases significantly and chronically throughout its body. Chronic immune activation is linked with age-related diseases in people as well, according to Walker, who said that the study could lead to realistic ways for scientists to intervene in the aging process and delay the onset of Parkinson’s disease, Alzheimer’s disease, cancer, stroke, cardiovascular disease, diabetes and other diseases of aging.