DNA methylation and sex-specific expression of FKBP5 as correlates of one-month bedtime cortisol levels in healthy individuals

摘要

Chronic exposure to cortisol is associated with cardiovascular, metabolic, and psychiatric disorders. Although cortisol can be readily measured from peripheral sources such as blood, urine, or saliva, multiple samplings spanning several days to weeks are necessary to reliably assess chronic cortisol exposure levels (referred to as cortisol load). Although cortisol levels in hair have been proposed as a measure of cortisol load, measurement is cumbersome and many people are not candidates due to short hair length and use of hair dyes. To date, there are no blood biomarkers that capture cortisol load.To identify a blood biomarker capable of integrating one-month cortisol exposure levels, 75 healthy participants provided 30+ days of awakening and bedtime saliva cortisol and completed psychosocial measures of anxiety, depression, and stress. Mean daily awakening and bedtime cortisol levels were then compared to CpG methylation levels, gene expression, and genotypes of the stress response geneFKBP5obtained from blood drawn on the last day of the study.We found a correlation betweenFKBP5methylation levels and mean 30+day awakening and bedtime cortisol levels (|r|≥0.32, p?≤?0.006). We also observed a sex-specific correlation between bedtime cortisol levels andFKBP5mRNA expression in female participants (r?=?0.42, p?=?0.005). Dividing the 30-day sampling period into four weekly bins showed that the correlations for both methylation and expression were not being driven by cortisol levels in the week preceding the blood draw. We also identified a female-specific association betweenFKBP5mRNA expression and scores on the Beck Anxiety Inventory (r?=?0.37, p?=?0.013) and Beck Depression Inventory-II (r?=?0.32, p?=?0.033). Finally, DNA was genotyped at four SNPs, and variation in rs4713902 was shown to have an effect onFKBP5expression under a codominant model (f?=?3.41, p?=?0.048) for females only.Our results suggest that bloodFKBP5DNA methylation and mRNA expression levels may be a useful marker for determining general or sex-specific 30-day cortisol load and justifies genome-wide approaches that can potentially identify additional cortisol markers with broader clinical utility.