Compared to adults who were healthier during infancy, those who experienced multiple infections have shorter DNA telomeres in adulthood. As these telomeres act as end caps for chromosomes which prevent that DNA from degrading, this finding could have implications in premature cellular aging.
“These are important and surprising findings because — generally speaking — shorter chromosome ‘caps’ are associated with a higher burden of disease later in life,” said Dan Eisenberg, an assistant professor of anthropology at the University of Washington, and lead author of the study. The article was published in the American Journal of Human Biology.
Telomeres are long DNA sequences at the end of chromosomes which tend to get shorter following each cell division. Their role is to protect the important coding DNA on each chromosome from damage, however when these telomeres are shortened beyond a threshold, the cell dies or ceases to divide.
While telomeres serve an important role for a variety of different cell types, their length is especially important in the white blood cells that contribute to the body’s immune system. When the body is challenged by an antigen – such as that displayed on the surface of an invading bacterium or virus – white blood cells must quickly divide and multiply to conquer the pathogen. However, if the telomeres on the ends of the white blood cell chromosomes are too short, the cells may not be able to divide to the extent necessary for a robust immune response.
“Many studies — in laboratory animals and humans — have associated shorter telomeres with poor health outcomes, especially in adults,” said Eisenberg. But the current study is one of the first to study the effect of early life infections and telomere length.
Using health data collected from over 3,000 infants born in the Philippines between 1983 and 1984, Eisenberg and his colleagues studied the incidence of diarrhea – which could be indicative of infection – among the cohort. In 2005, 1,776 of the study participants – now adults – donated a blood sample which was analyzed for telomere length.
The researchers found that infants with more reported cases of diarrhea between aged six and 12 months had the shortest adult telomere lengths. When compared to babies with no reported diarrheal infections, those who experienced even an average number of these events as infants showed three additional years of telomere aging as adults.
Since infections increase the rate of cell division, it’s possible that they could shorten telomeres. While the infections during infancy could have a negative effect on telomere length when those individuals reach adulthood, Eisenberg believes that this is not the only possible explanation.
“It could also be that they had shorter telomeres at birth,” said Eisenberg. “And perhaps as a result, they were more susceptible to infections at six to 12 months and maintained these short telomeres into adulthood.”
In this case, telomere length could be a predictor of the severity and potential outcome of childhood infections. According to Eisenberg, more study of the association between telomere length and the environment must be conducted before true conclusions can be made.