Research finds association between infancy infection and length of protective DNA stretches – Dailyuw

The age old adage asserts What doesnt kill you makes you stronger. However, this might not be the case for people who suffer from more viral infections.

A new joint study led by UW assistant professor of anthropology Dan Eisenberg indicates that peoples protective stretches of DNA, which cap the ends of their chromosomes, appear shorter if they experience more infections during infancy.

Understanding humans from evolution

The study is part of human biology research, which aims to understand humans from an evolutionary perspective.

[We are] looking at [what] our roots say as mammals, and primates, Eisenberg said. And how that may influence our biology as it is today.

Eisenberg looks across different places around the world where culture, ecology, and evolution may affect different populations in various ways. In this recent study, he used health data from the Cebu Longitudinal Health and Nutrition Survey, which keeps health records of over 3,000 infants born between 1983-84 in Cebu City in the Philippines.

Detailed health data and feeding habits were collected every two months from these infants up to age 2. Researchers recorded the frequencies of diarrhea in particular, since they most likely indicated infections due to environmental and public health concerns in Cebu City at the time. Researchers kept collecting data over the next 20 years. Of these babies, 1,776 provided their blood samples once again as young adults in 2005.

Eisenberg found that adults with more diarrhea infections as infants showed shorter protective stretches of DNA, which may bring them a higher burden of diseases later in their lives.

Telomeres, the protective stretches of our DNA

Telomeres, which cap the ends of chromosomes, play an important role in cellular aging. They protect genes from damage and improper regulation.

The analogy is that telomeres are like little plastic tips at the ends of our shoelaces, Eisenberg said. When these fray, you shoelaces dont work as well.

The telomeres get a bit shorter each time a cell in our body replicates. Eventually, the cell stops replicating when the telomeres become too short. Thus telomeres in peoples cells become shorter and shorter as they become older, making them more vulnerable to health and environmental issues.

Short telomeres are part of the reason why our bodies do not work well as we get older, Eisenberg said. For example, if you accidentally cut yourself, your skin has to make new cells to heal the wound. When your telomeres are shorter, you are less likely able to regrow skin as quickly.

Similar processes happen everywhere in our bodies while cells are being replaced. Shorter telomeres appear to predict increased sickness and earlier death.

Cells of the immune system, such as white blood cells in the bloodstream, have to replicate and create an army of cells to fight off pathogens. If telomeres in these cells are too short, the immune system may take more effort. On the other hand, overcoming infections also shortens telomeres.

There are good reasons to predict [how] early-life infections might be associated with telomeres in later life, Eisenberg said.

Research findings and further questions

While one could quickly draw the conclusion that more infections in infancy results in shorter telomeres and shorter lives, interpreting current research findings turned out to be more complicated.

This was only an association that we found, but we had to consider whether there could be other reasons why we saw this, Eisenberg said. Part of the ways that longer telomeres help to protect our health is [that] they actually can promote better immune function. So another possible explanation for our findings is that infants born with longer telomeres were better able to fight off the infections.

In the midst of receiving more samples from the Philippines as the study continues, Eisenberg is looking into ways to improve the study.

If you manage to get samples very early in peoples life, maybe right after they were born or within the first few months, you can look to see whether kids with longer telomeres have decreased infections, Eisenberg said. When they do get infections, we can get samples later on to see if their telomeres become shorter. That will be an ideal way to study.

Reach reporter Zezhou Jing at science@dailyuw.com. Twitter: @Zz_Jing

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Research finds association between infancy infection and length of protective DNA stretches - Dailyuw