Telomeres are protective caps made of DNA proteins that are found on the ends of our cells' chromosomes. Scientists have previously linked telomere length to signs of aging, risk for genetic disorders and longevity.
A new study shows that the length of telomeres may also predict risk for the common cold.
Telomere length is recognized as a "biomarker" of aging, with the caps shortening over time as people age. Some studies have found people who inherited longer telomeres mayor . Having shorter telomeres has also been linked to early onset of aging-related heart disease and cancer, according to the authors of the new study.
They, however, wanted to see whether telomere length could predict disease risk in young to middle-aged adults.
"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," study co-author Dr. Sheldon Cohen, professor of psychology at CMU's Dietrich College of Humanities and Social Sciences in Pittsburgh, Pa., said in written statement. "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."
The researchers measured telomere length from white blood cell samples collected from 152 healthy volunteers between the ages of 18 and 55, and then exposed each subject to the virus that causes the common cold, rhinovirus. Subjects were quarantined in single rooms for five days to see if they got sick.
More than 100 of the participants of the participants developed respiratory infections, 33 of whom had clinical symptoms of the common cold. Those with shorter telomeres were more likely to get infected by the virus, however the link was not seen in the youngest participants who were 18 to 21 years old. Starting at age 22, telomere length predicted risk for the respiratory infection, with it becoming a stronger predictor as the subject's ages increased.
The link between common colds and telomeres was strongest when the researchers looked at specific type of white blood cell, called CD8CD28 T- cells. Seventy-seven percent of subjects with the shortest telomere lengths got infected with a respiratory virus, compared with 50 percent of those in the group with the longest telomeres. Among those with the shortest telomeres, 26 percent became clinically sick with the common cold, compared to 13 percent of those in the group with the longest telomeres.
CD8CD28 telomeres shorten faster than those found in other cells, according to the researchers, and previous studies have linked shortened telemores in these cells to decreases in immune system strength.
"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," said Cohen.
The research, which is considered preliminary, was published Feb. 19 in JAMA, the Journal of the American Medical Association.
"This is something new and provocative," Dr. William Schaffner, an infectious disease specialist at Vanderbilt University School of Medicine in Nashville, Tenn., who was not involved in the research, told HealthDay. "All of us know some people who get one cold after another, and others who seem like they're able to be around people with colds but remain robust."
"It's quite a small study to make such a profound discovery," added James Crowe, a professor at Vanderbilt University Medical Center in Nashville not involved in the study, in an interview USA Today. "It's not a validated study, but it's unusual and interesting, and it needs to be followed up. That's how science works. We get many ideas, and many of them don't pan out."