Smoking shortens the end fragments of chromosomes — called telomeres — in white blood cells, according to work presented at the European Respiratory Society International Congress in Milan, Italy. The length of these end sections indicates how quickly we age and our cells’ ability to repair and regenerate.
“Our study shows that smoking status and cigarette quantity can result in the shortening of leucocyte telomere length, which is an indicator of tissue self-repair, regeneration, and ageing. In other words, smoking can accelerate the process of ageing, while quitting may considerably decrease the related risk,” said Dr. Siyu Dai, assistant professor at the School of Clinical Medicine, Hangzhou Normal University.
Telomeres protect the ends of chromosomes. Each time a cell divides, the telomeres get a little shorter and eventually become so short that the cell can no longer divide and dies. This is part of the ageing process. Further changes in telomere length can be caused by many factors, but there is limited research to find out whether smoking can actually cause a shortening in telomere length in white blood cells.
A group of researchers analysed data from the UK biobank, which contains genetic and health information from half million UK participants. They looked at whether a person was a current smoker, ex-smoker, or non-smoker, as well as how many cigarettes they smoked (for smokers and ex-smokers). Then, they compared these results with information collected about the telomere length of their white blood cells (collected from blood samples).
“We found that current smoking status was statistically significantly associated with shorter leucocyte telomere length, whereas previous smokers and people who had never smoked didn’t show significantly shorter leucocyte telomere length. Among people who used to smoke, there was a trend towards shorter telomere length, but this was not statistically significant. People who smoked the greater number of cigarettes had significantly shorter leucocyte telomere length. In summary, smoking may cause the shortening of leucocyte telomere length, and the more cigarettes smoked, the stronger the shortening effect,” said Dr Dai.
“In recent years, observational studies have linked shortened leucocyte telomere length with many diseases, such as cardiovascular disease, diabetes, and muscle loss. This means that the effect of smoking on telomere length probably plays a critical role in these diseases, although more research is needed to understand the underlying mechanisms. Our study adds to the evidence that smoking causes ageing. As there are clear health benefits of smoking cessation, it is time to include cessation support as well as treatment into daily clinical management to help us create a smoke-free environment for the next generation.”
The team wants to continue with this research. They are particularly interested in finding out whether second-hand smoke has similar effects on cell regeneration and ageing, especially in children.
“This study addresses the question of whether smoking affects telomere lengths. Telomeres protect the ends of chromosomes. If telomeres become short, cells can no longer divide successfully, and they die. Dr Dai and her colleagues, in a study of half a million adults, show a clear association between smoking and reduced telomere length. It will be interesting to see what the researchers have found in relation to the effects of passive smoking on telomere length,” added Professor Jonathan Grigg, Chair of the European Respiratory Society Tobacco Control Committee, who was not involved with this research.
Abstract no: OA4230. “The causal relationship between smoking conditions and telomere length: a mendelian randomization study in UK biobank”, by Dr Siyu Dai et al; Presented in session, “Selected Tobacco and Nicotine Research” at 09.30-10.45 hrs CEST on Tuesday 12 September 2023. https://k4.ersnet.org/prod/v2/Front/Program/Session?e=379&session=16433