SciTech

Susceptibility to flu may be found in your chromosomes

Credit: Kelsey Scott/Operations Manager Credit: Kelsey Scott/Operations Manager

How often do you get a cold? Have you noticed that you get sick more or less often than your friends? Carnegie Mellon Robert E. Doherty Professor of Psychology Sheldon Cohen recently identified a biological marker — an indicator of a biological state — that corresponds with one’s susceptibility to the common cold.

Telomeres are cap-like protein complexes found at the ends of chromosomes whose function is to protect those chromosomes during replication. It has long been known that as you age and undergo more cell replication, your telomeres shorten, leading to the possibility of aging-related diseases. What is remarkable about Cohen’s work is the discovery that telomere length not only predicts susceptibility of disease in the elderly, but also does so for younger people.

Cohen cites two reasons that led him to conduct a study on the correlation between telomere length in young adults and their ability to fight off disease: “First, even though telomere length decreases as we age, the evidence suggested that there was variation in telomere length even in young adults. Second, telomere length is often measured in white blood cells. Our interest is in how the immune system responds to infectious agents like cold viruses,” he said. “The most prevalent diseases in the age group we study, 18-to-55-year-olds, are upper respiratory infections, and it seemed to us that those with shorter telomeres in key white blood cells would be less able to prevent cold viruses from replicating.”

Indeed, the results of Cohen’s experiments aligned with his prediction. Cohen and his team measured the telomere length of white blood cells in 152 volunteers between the ages of 18 and 55. These volunteers were then quarantined for five days after being exposed to the virus that causes the common cold. “We have studied the role of psychological and behavioral factors in the common cold for over 30 years. Unlike most diseases, we can actually experimentally expose people to the disease-causing agent. Hence, colds have provided an excellent model for us,” Cohen said.

The results of the experiment showed that individuals with shorter telomere length were more likely to contract the common cold than those with longer telomeres. Another result of their experiment was the discovery that telomere length only started predicting an individual’s susceptibility to the common cold for those who were about 22 or older. Telomere length was increasingly indicative of an individual’s ability to fight off disease as the age of the individual increased. “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,” Cohen said in a university press release.

Sheldon and his team also found that a particular type of white blood cell — a CD8CD28- T-cytolytic cell — was the best indicator of the likelihood of contracting the cold because the telomeres found in CD8CD28- cells shorten at a more rapid speed than those found in other cell types.

Now that it’s known that telomere length corresponds with an individual’s ability to fight off disease, the obvious question one might ask is, what factors — besides natural aging — affect telomere length?

“Shorter telomere length is associated with traumaatic childhood experiences, with exposure to chronic enduring stressors, with poor health behaviors such as smoking and excessive consumption of alcohol, with lower levels of education, and with stable psychological dispositions like hostility,” Cohen said. These factors may decrease telomere length through their effects on telomerase — an enzyme that rebuilds telomeres.

Further studies with other viruses and natural infections will increase the understanding of how telomere length corresponds to susceptibility to disease. Perhaps, in the future, telomeres will be the key to improving human health.How often do you get a cold? Have you noticed that you get sick more or less often than your friends? Carnegie Mellon Robert E. Doherty Professor of Psychology Sheldon Cohen recently identified a biological marker — an indicator of a biological state — that corresponds with one’s susceptibility to the common cold.

Telomeres are cap-like protein complexes found at the ends of chromosomes whose function is to protect those chromosomes during replication. It has long been known that as you age and undergo more cell replication, your telomeres shorten, leading to the possibility of aging-related diseases. What is remarkable about Cohen’s work is the discovery that telomere length not only predicts susceptibility of disease in the elderly, but also does so for younger people.

Cohen cites two reasons that led him to conduct a study on the correlation between telomere length in young adults and their ability to fight off disease: “First, even though telomere length decreases as we age, the evidence suggested that there was variation in telomere length even in young adults. Second, telomere length is often measured in white blood cells. Our interest is in how the immune system responds to infectious agents like cold viruses,” he said. “The most prevalent diseases in the age group we study, 18-to-55-year-olds, are upper respiratory infections, and it seemed to us that those with shorter telomeres in key white blood cells would be less able to prevent cold viruses from replicating.”

Indeed, the results of Cohen’s experiments aligned with his prediction. Cohen and his team measured the telomere length of white blood cells in 152 volunteers between the ages of 18 and 55. These volunteers were then quarantined for five days after being exposed to the virus that causes the common cold. “We have studied the role of psychological and behavioral factors in the common cold for over 30 years. Unlike most diseases, we can actually experimentally expose people to the disease-causing agent. Hence, colds have provided an excellent model for us,” Cohen said.

The results of the experiment showed that individuals with shorter telomere length were more likely to contract the common cold than those with longer telomeres. Another result of their experiment was the discovery that telomere length only started predicting an individual’s susceptibility to the common cold for those who were about 22 or older. Telomere length was increasingly indicative of an individual’s ability to fight off disease as the age of the individual increased. “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,” Cohen said in a university press release.

Sheldon and his team also found that a particular type of white blood cell — a CD8CD28- T-cytolytic cell — was the best indicator of the likelihood of contracting the cold because the telomeres found in CD8CD28- cells shorten at a more rapid speed than those found in other cell types.

Now that it’s known that telomere length corresponds with an individual’s ability to fight off disease, the obvious question one might ask is, what factors — besides natural aging — affect telomere length?

“Shorter telomere length is associated with traumaatic childhood experiences, with exposure to chronic enduring stressors, with poor health behaviors such as smoking and excessive consumption of alcohol, with lower levels of education, and with stable psychological dispositions like hostility,” Cohen said. These factors may decrease telomere length through their effects on telomerase — an enzyme that rebuilds telomeres.

Further studies with other viruses and natural infections will increase the understanding of how telomere length corresponds to susceptibility to disease. Perhaps, in the future, telomeres will be the key to improving human health.