Biomarker explains why some people catch colds more often than others

Researchers from the Carnegie Mellon University have identified a biological marker in the immune system that (starting from about age 22), predicts the probability of getting a common cold.

telomereThey found that telomeres play a big part in this likelihood. Telomeres are regions of repetitive nucleotide sequences at each end of a chromatid, which protect the end of the chromosome from deterioration or from fusion with neighboring chromosomes. Telomeres are alsoa biomarker of aging, with telomeres shortening as you advance in age. As a cell’s telomeres shorten, it loses its ability to function normally. Basically, shorter telomeres make you more susceptible to a number of diseases, such as cancer or cardiovascular disease – especially in older people. However, as it turns out, it plays a big role in younger adults, and has a tight connection with the common cold as well.

“Our work suggests the possibility that telomere length is a relatively consistent marker across the life span and that it can start predicting disease susceptibility in young adulthood,” said Sheldon Cohen who conducted the study, the Robert E. Doherty Professor of Psychology in CMU’s Dietrich College of Humanities and Social Sciences. “We knew that people in their late 50s and older with shorter telomeres are at a greater risk for illness and mortality. We also knew that factors other than aging, such as chronic stress and poor health behaviors, are associated with shorter telomeres in older people. Consequently, we expected that younger people would vary in their telomere length as well and wanted to see what this would mean for their health.”

He and his team measured the telomere length of white blood cells from 152 healthy volunteers aged 18-55 – inviduals who had been previously exposed to a rhinovirus, which causes a common cold, and quarantined for five days to see if they developed the cold.

The results clearly showed that that particpiants with shorter telomeres were much more likely to become infected with the virus. There was no connection to telomere length and this occurence in people 21 or younger, but after 22 years, telomere length started to predict whether individuals would develop an infection. As participant age increased, telomere length became an even stronger predictor; one telomere especially, of a specific white blood cell (a CD8CD28- T-cytolytic cell) was a superior predictor of infection and cold symptoms than other white blood cell types.

sheldon cohen“These cells are important in eliminating infected cells and those with shorter telomeres in the CD8CD28- cell population may be at greater risk for infection because they have fewer functional cells available to respond to the [cold] virus,” Cohen said. “The superior ability of CD8CD28- T-cytolytic cells to predict infection gives us an idea of which cells to focus on in future work on how telomere length influences the immune system’s response to infection and other immune-related challenges.”

Cohen then added:

“The increased importance of telomere length with age is likely because the younger participants had fewer very short telomeres, or that their young immune systems were able to compensate for the loss of effective cells.”

It has to be emphasized however that these are just the preliminary results, and much more research has to be conducted to clarify the implications of such an association.

The research was published in the Journal of the American Medical Association (JAMA)

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