Telomeres Are Shorter in Adults Who Had More Diarrheal Infections as Infants

University of Washington researchers have discovered that telomeres are shorter in adults who had experienced more diarrheal infections as infants.

Researchers from the University of Washington have discovered a number of insights pertaining to telomeres and their role in the fight against infection. According to the researchers, the length of these protective DNA strands matters when it comes to the strength of immune response; individuals who experienced more diarrheal infections as babies were found to have shorter telomeres as adults, compared with those who were healthier infants. The shorter the telomeres, the harder it may be for the body’s immune system to effectively respond when faced with a harmful pathogen.

According to a press release put out by the university, these findings offer new insight into the relationship between how both genetics and the environment influence the health of individuals.

When speaking of the implications of these findings, lead author Dan Eisenberg, assistant professor of anthropology at the University of Washington explained, “These are important and surprising findings because—generally speaking—shorter chromosome ‘caps’ are associated with a higher burden of disease later in life.”

The Centers for Disease Control and Prevention (CDC) define these chromosome “caps,” or telomeres, as “structures at the end of chromosomes that contain repetitive stretches of DNA.” Their purpose? “They ‘seal’ chromosomes at the tips, preventing them from unraveling or sticking together.” They also work to protect the DNA sequence of chromosomes during cell division. However, each time the cell divides, the telomere grows shorter.

In her own research, Elizabeth H. Blackburn, PhD, and Nobel Prize-winning scientist has compared telomeres to aglets, or the “caps” at the ends of shoelaces to better illustrate how they function. Aglets are important because they protect the ends of the shoelaces from degradation or fraying. Once the aglet is damaged, you’re going to need new shoelaces. Telomeres are essentially genetic aglets in that they serve to protect the DNA from damage. However, just like shoelaces, they do not have live on indefinitely. When telomeres become too short, the cell either ceases to divide or dies altogether.

The length of these telomeres is particularly important in immune system response. When up against a pathogen, white blood cells will “undergo rapid rounds of cell division” but the shorter the telomeres are in the white blood cells, the harder the body may struggle with initiating immune response against the infectious disease.

Dr. Eidenberg noted, “Many studies—in laboratory animals and humans—have associated shorter telomeres with poor health outcomes, especially in adults.”

In order to reach these conclusions, Dr. Eidenberg and his team utilized data from the Cebu Longitudinal Health and Nutrition Survey, a survey that has kept tabs on the health of more than 3,000 infants who had been born in Cebu City in the Philippines between 1983 and 1984. Every two months, the researchers collected data on two factors from the mothers of these infants: how often their babies were breastfed, as well as how frequent their babies had diarrhea.

Over the course of 20 years, through the use of follow-up surveys, the researchers kept tabs on the babies as they grew older. By the time the babies were 21 or 22 years old, 1,776 blood samples had been taken from them for analysis.

Dr. Eisenberg and his team looked specifically at the length of the telomeres in the offspring’s blood samples and combined that data with the reports provided by the mothers on diarrhea incidence and breastfeeding when the subjects were infants.

Their findings? The subjects that presented with the shorter telomeres as adults had reportedly experienced diarrhea more frequently between 6 to 12 months of age—which is the common weaning period for most infants. According to the press release, it is during that period that “infectious diseases in infants reach their peak.” Dr. Eisenberg noted that when taking into consideration Cebu City’s environment and public health situation, the diarrhea that the babies experienced was most likely a result of infection.

Taking into consideration the brevity of diarrheal infection, and the fact that it remains the second leading cause of death amongst children under five years old, the researchers feel that the potential link established between telomeres length and this infection could be an important influencer when it comes to aging. According to the press release, “For example, those with an average level of diarrheal infection as babies, compared to those with no reported infections, showed the equivalent of three additional years of telomere ‘aging’—based on the rate of telomere shortening among middle-age adults.”

Although breastmilk has been known to provide nutrients to infants that help them fight off harmful pathogens, the researchers did not find a link between breastfeeding and telomere length.

The researchers’ findings offer further insight into telomeres and their role in infection. By looking at the length of these telomeres, researchers may be able to identify if children will have diarrheal infections or not, which is important in that these infections remain such a serious health concern worldwide. In order to further understand the potential links between the environment, telomeres, and human health, more data needs to be collected, according to Dr. Eisenberg.