Short Telomeres Linked to Risk for Common Cold

Telomeres are the end caps of chromosomes, protecting the DNA complexes from deterioration during cell division. Telomere shortening is considered a marker of cellular aging, and prematurely shortened telomeres have been linked to increased risk of cancers, heart disease, dementia and death.  Sheldon Cohen, from Carnegie Mellon University (Pennsylvania, USA), and colleagues enrolled 152 men and women, ages 18 to 55 years, measuring each subject’s telomere length on four types of immune cells: peripheral blood mononuclear cells, CD4-positive cells, CD8 cells positive for CD28, and CD8 cells negative for CD28.  Participants spent 24 hours in the laboratory under quarantine and then were given nasal drops containing 100 tissue culture infectious doses of rhinovirus 39. They were monitored for 5 days for development of cold symptoms. Relative risks for becoming infected by either of these definitions ranged from 1.22 for each standard deviation decrease in telomere length on peripheral blood mononuclear cells, to 1.38 on CD8/CD28-negative cells.  For clinical illness, each standard deviation decrease in telomere length brought a significant increase in risk only for measurements on CD8/CD28-negative cells.  Further, the team observed that for telomere length measured in all four cell types, about 80% of individuals in the shortest tertile became infected, compared with fewer than 60% in the longest tertile.  Only when telomere length was measured in CD8/CD28-negative cells was there a significant difference in clinical illness rates among tertiles: about 25% of those in the shortest tertile developed clinical colds versus about 13% of the longest tertile.  The study authors conclude that: “shorter CD8CD28− T-cell telomere length was associated with increased risk for experimentally induced acute upper respiratory infection and clinical illness.”