Cold Symptoms May Depend on Length of Chromosome Cap
DNA bits linked to age-related illnesses may also determine cold symptoms, according to a study that suggests the telomeres may affect human health at all stages of life.
Telomeres cap the ends of chromosomes and protect them from degeneration, and length of the structures correlates with aging and mortality in older adults. In a study published today in the Journal of the American Medical Association, scientists found that people with the shortest telomeres caught more colds and were less likely to fight off the virus than those with the longest telomeres.
The study is one of the first to look at telomere length in younger adults, said lead study author Sheldon Cohen. Short telomeres have been associated with aging-related illnesses such as heart disease and cancer. The findings suggest how long telomeres are may play a role in disease susceptibility in younger people as well, Cohen said.
“There is growing evidence that this is an aging biomarker that may have implications for health and well-being over our life course,” said Cohen, a professor of psychology at Carnegie Mellon University in Pittsburgh, in a Feb. 15 telephone interview.
Telomeres decrease in length every time a cell divides, eventually leading to the cell’s demise. It’s thought that these DNA structures put a time frame on an organism’s lifespan by limiting the number of times cells can replicate before DNA damage occurs.
Telomere length may be affected by a number of things besides aging, including chronic stress, lower levels of education, genetic markers and negative experiences in early childhood, Cohen said.
Researchers wanted to find out whether there was any variation in telomere length in younger people and whether those with shorter telomeres were at greater risk of disease. So they focused on white blood cells called T-cells, which help fight off infection in the body.
Between 2008 and 2011 they measured telomere length in three types of these T-cells and another type of cell in 152 healthy Pittsburgh residents ages 18 to 55. The participants were then quarantined in single rooms and given nasal drops containing the common cold virus. They were then monitored for signs of infection and symptoms.
Almost 70 percent of the study’s participants showed signs of infection with the cold virus, based on a blood test, while 22 percent went on to develop a verified infection with cold symptoms.
When scientists took a closer look at one particular T-cell subset that’s been associated with immune function, they found that 77 percent of those infected were in the group with the shortest telomeres compared with 50 percent of those with the longest telomeres. Among those who developed colds, 26 percent were in the short telomere group compare with 13 percent with longest telomeres.
Scientists also found that a greater percentage of those with short telomeres were among older people in the study.
The findings, if duplicated in further research, may mean that telomere length could help predict who needs extra protection from vaccines or medications such as cholesterol- lowering drugs to reduce risk of heart disease, said Elissa Epel, a study author and an associate professor in the Department of Psychology at the University of California, San Francisco.
Still, she said it’s unclear whether knowing one’s telomere length is helpful. Epel was a founding member of Telomere Health Inc., a Menlo Park, California-based company that provides telomere length data to doctors and interested people. She is on the advisory board of the company, along with Elizabeth Blackburn, who was one of three who won the 2009 Nobel Prize in Medicine for her work on telomeres.
“There is a lot of hype around telomere length, because it appears to be a stronger risk factor for early disease and mortality than traditional risk factors,” Epel said in an e- mail today. “It also tends to predict the range of diseases of aging, not just cardiovascular disease. But essentially it is just like cholesterol in that it is a risk factor that is partly inherited, partly determined by lifestyle and is malleable.”
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