Seasonal variation of peripheral blood leukocyte telomere length in Costa Rica: A population‐based observational study

Abstract

Objectives Peripheral blood leukocyte telomere length is increasingly being used as a biomarker of aging, but its natural variation in human populations is not well understood. Several other biomarkers show seasonal variation, as do several determinants of leukocyte telomere length. We examined whether there was monthly variation in leukocyte telomere length in Costa Rica, a country with strong seasonal differences in precipitation and infection. Methods We examined a longitudinal population based cohort of 581 Costa Rican adults age 60 and above, from which blood samples were drawn between October 2006 and July 2008. Leukocyte telomere length was assayed from these samples using the quantitative PCR method. Multivariate regression models were used to examine correlations between month of blood draw and leukocyte telomere length. Results Telomere length from peripheral blood leukocytes varied by as much as 200 base pairs depending on month of blood draw, and this difference is not likely to be due to random variation. A moderate proportion of this association is statistically accounted for by month and region specific average rainfall. We found shorter telomere length associated with greater rainfall. Conclusions There are two possible explanations of our findings. First, there could be relatively rapid month-to-month changes in leukocyte telomere length. This conclusion would have implications for understanding the natural population dynamics of telomere length. Second, there could be seasonal differences in constituent cell populations. This conclusion would suggest that future studies of leukocyte telomere length use methods to account for the potential impact of constituent cell type.

Mind the cell: Seasonal variation in telomere length mirrors changes in leucocyte profile

“…In mandrills, infection and stress are strongly intertwined, and their respective effects on leucocyte composition and telomere length therefore appear difficult to disentangle. A previous study conducted on humans in Costa Rica suggested that seasonal changes in infection pressure may be sufficient to lead to seasonal changes in telomere length, with shorter telomeres when infection pressure was maximal (although lymphocyte proportion and stress levels were not measured in this study) (Rehkopf, Dow, & Rosero‐Bixby, ). Because infection and stress are likely to often co‐occur in nature, further experimental studies should examine whether these factors really underlie the seasonal differences in leucocyte composition and telomere length that we observed, and, if so, whether their effects on leucocyte composition and telomere length are self‐sufficient, intermingled, additive or synergistic.…”

Circulating cell-free DNA, telomere length and bilirubin in the Vienna Active Ageing Study: exploratory analysis of a randomized, controlled trial

“…Moreover, studies in humans often use blood cells as a test material for measuring telomere length78. As blood cells comprise a mixture of different individual cell types with different mitotic history, telomere length measured in these samples can additionally show a large intra-individual variability79. Therefore, there is an increased need for identifying reliable and clinically accessible molecular markers of ageing, which would complement telomere length as a marker10.…”

Telomere Length and Neighborhood Circumstances: Evaluating Biological Response to Unfavorable Exposures

“…This study also did not report potential effects of DNA extraction method or date of blood draw on TL, when previous studies suggest that seasonal effects (date of blood draw) and type of laboratory methods used could influence TL measures(30, 46, 47). We found that neighborhood effects remained even after adjustment for individual-level covariates and psychosocial factors.…”

“…Laboratory factors known to affect TL measures in prior studies, including DNA extraction method(30, 46) and date of blood draw (given potential seasonal(47) and storage effects(48) on TL measures) were also included as covariates in statistical models.…”