Immune cell dynamics in response to an acute laboratory stressor: a within-person between-group analysis of the biological impact of early life adversity.

Early life adversity (ELA) is a risk factor for early onset morbidities and mortality, a relationship that may be driven in part by immune system dysregulation. One mechanism of dysregulation that has yet to be fully examined in the context of ELA is alterations to immune cell dynamics in response to acute stress. Using a within-person between-group experimental design, we investigated stress-induced changes in immune cell populations, and how these changes may be altered in individuals with a history of ELA. Participants were young adults (N = 34, aged 18-25 years, 53% female, 47% with a history of ELA). Complete immune cell counts were measured at four time-points over a 5-hour window across two sessions (Trier Social Stress Test [TSST] vs. no-stress) separated by a week. Across all participants, total white blood cells increased over time (F(3,84)=38.97, p < .001) with a greater increase in response to the TSST compared to the no-stress condition at 240 minutes post-test (b = 0.43±.19; t(179)=2.22, p = .027). This pattern was mirrored by neutrophil counts. Lymphocyte counts were initially depressed by TSST exposure (b =-205±.67; t(184)=-3.07, p = .002) but recovered above baseline. ELA status was associated with higher stress-induced immune cell counts, a difference likely driven by increases in neutrophils (F(1,22)=4.45, p = .046). Overall, these results indicate differential immune cell dynamics in response to acute stress in individuals with a history of ELA. This points to altered immune system functioning in the context of stress, a finding that may be driving increased morbidity and mortality risk for ELA-exposed individuals.

Elevated glucocorticoids during gestation suggest sex-specific effects on offspring telomere lengths in a wild lizard.

The effects of maternal glucocorticoids (e.g. corticosterone, CORT) on offspring interest biologists due to increasing environmental perturbations. While little is known about the impact of maternal CORT on offspring fitness, it may modulate telomere length and compromise offspring health. Here, we use a modified real-time quantitative PCR assay to assess telomere length using small DNA quantities (<60 ng). We tested the hypothesis that increased maternal CORT during gestation decreases offspring telomere length. While CORT-driven telomere shortening is well established within individuals, cross-generational effects remain unclear. We treated wild-caught gravid female eastern fence lizards (Sceloporus undulatus) with daily transdermal applications of CORT, at ecologically relevant levels, from capture to laying. Maternal CORT treatment did not alter maternal telomere length, although baseline maternal CORT concentrations had a weak, negative correlation with maternal telomere length. There was no relation between mother and offspring telomere length. There was a trend for maternal CORT treatment to shorten telomeres of sons but not daughters. Our treatment replicated exposure to a single stressor per day, likely underestimating effects seen in the wild where stressors may be more frequent. Future research should further explore fitness consequences of maternal CORT effects.

The future of direct-to-consumer clinical genetic tests.

In light of the meeting of the US Food and Drug Administration (FDA) in March 2011 to discuss the regulation of clinical direct-to-consumer (DTC) genetic tests, we have invited five experts to consider the best means of overseeing the ordering and interpretation of these tests. Should these tests be regulated? If so, who, if anyone, should communicate results to consumers?

Comparison qPCR study for selecting a valid single copy gene for measuring absolute telomere length.

Telomere shortening is a well-known biomarker for biological aging. A previous review of the methods used to measure telomere length (TL) noted how challenging it is to compare results from different studies using diverse methodological techniques. The most commonly used high throughput method for measuring average TL is the quantitative PCR (qPCR) method, where there are two protocols available; the relative TL and the absolute TL (aTL) method. All qPCR methods have similarities in that they use two different primer sets to measure the telomere repeat sequence (TTAGGG)n and a single copy gene region to calculate the average TL, (T/S) ratio. The difference between the relative TL and the aTL assay lies with the introduction of duplex oligomer standards to identify TL in kilobase pairs rather than using the traditional relative TL, T/S ratio method. Problems were noted using 36B4 (RPLP0), which was originally used as a suitable single copy gene qPCR assay. A previous aTL publication attempted to replace the 36B4 (RPLP0) single copy gene using the Interferon beta 1 gene (IFNB1) but results showed a lack of agreement with the TL results when compared to the DNAmTL assay. Here, we compare the two single copy gene assays previously used for the aTL assay and offer an alternative IFNB1 single copy gene assay without non-specific priming amplification to provide more consistent diploid copy number determination and a more robust and reproducible assay for measuring absolute TL.

Biological stability of DNA methylation measurements over varying intervals of time and in the presence of acute stress.

Identifying factors that influence the stability of DNA methylation measurements across biological replicates is of critical importance in basic and clinical research. Using a within-person between-group experimental design (n = 31, number of observations = 192), we report the stability of biological replicates over a variety of unique temporal scenarios, both in the absence and presence of acute psychosocial stress, and between individuals who have experienced early life adversity (ELA) and non-exposed individuals. We found that varying time intervals, acute stress, and ELA exposure influenced the stability of repeated DNA methylation measurements. In the absence of acute stress, probes were less stable as time passed; however, stress exerted a stabilizing influence on probes over longer time intervals. Compared to non-exposed individuals, ELA-exposed individuals had significantly lower probe stability immediately following acute stress. Additionally, we found that across all scenarios, probes used in most epigenetic-based algorithms for estimating epigenetic age or immune cell proportions had average or below-average stability, except for the Principal Component and DunedinPACE epigenetic ageing clocks, which were enriched for more stable probes. Finally, using highly stable probes in the absence of stress, we identified multiple probes that were hypomethylated in the presence of acute stress, regardless of ELA status. Two hypomethylated probes are located near the transcription start site of the glutathione-disulfide reductase gene (GSR), which has previously been shown to be an integral part of the stress response to environmental toxins. We discuss implications for future studies concerning the reliability and reproducibility of DNA methylation measurements.Abbreviations: DNAm - DNA methylation, CpG - 5'-cytosine-phosphate-guanine-3,' ICC - Interclass correlation coefficient, ELA - Early-life adversity, PBMCs - Peripheral blood mononuclear cells, mQTL - Methylation quantitative trait loci, TSS - Transcription start site, GSR - Glutathione-disulfide reductase gene, TSST - Trier social stress test, PC - Principal component.

Circulating microRNAs involved in multiple sclerosis.

Multiple sclerosis (MS) is an immune-mediated, demyelinating and neurodegenerative disease of the central nervous system. After traumatic brain injury, it is the leading cause of neurology disability in young adults. Considerable advances have been made in identifying genes involved in MS but the genetic and phenotypic complexity associated with this disease significantly hinders any progress. A novel class of small RNA molecules, microRNAs (miRNAs) has acquired much attention because they regulate the expression of up to 30% of protein-coding genes and may play a pivotal role in the development of many, if not all, complex diseases. Seven published studies investigated miRNAs from peripheral blood mononuclear cells, CD4+, CD8+ T cell, B lymphocytes, peripheral blood leukocytes, whole blood and brain astrocytes with MS risk. The absence of MS studies investigating plasma miRNA prompted the current investigation of identifying a circulating miRNA signature in MS. We conducted a microarray analysis of over 900 known miRNA transcripts from plasma samples collected from four MS individuals and four sex-aged and ethnicity matched healthy controls. We identified six plasma miRNA (miR-614, miR-572, miR-648, miR-1826, miR-422a and miR-22) that were significantly up-regulated and one plasma miRNA (miR-1979) that was significantly down-regulated in MS individuals. Both miR-422a and miR-22 have previously been implicated in MS. The present study is the first to show a circulating miRNA signature involved in MS that could serve as a potential prognostic and diagnostic biomarker for MS.

Telomere shortening and the transition to family caregiving in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study.

Telomere length (TL) is widely studied as a possible biomarker for stress-related cellular aging and decreased longevity. There have been conflicting findings about the relationship between family caregiving stress and TL. Several initial cross-sectional studies have found associations between longer duration of caregiving or perceived stressfulness of caregiving and shortened TL, suggesting that caregiving poses grave risks to health. Previous reviews have suggested the need for longitudinal methods to investigate this topic. This study examined the association between the transition to family caregiving and change in TL across ~9 years. Data was utilized from the Caregiving Transitions Study, an ancillary study to the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study. TL was assayed using qPCR and analyzed as the telomere-to-single copy gene ratio for each participant at baseline and follow-up. General linear models examined the association between caregiving status and the change in TL for 208 incident caregivers and 205 controls, as well as associations between perceived stress and TL among caregivers. No association was found between TL change and caregiving (p = 0.494), and fully adjusted models controlling for health and socioeconomic factors did not change the null relationship (p = 0.305). Among caregivers, no association was found between perceived caregiving stress and change in TL (p = 0.336). In contrast to earlier cross-sectional studies, this longitudinal, population-based study did not detect a significant relationship between the transition into a family caregiving role and changes in TL over time. Given the widespread citation of previous findings suggesting that caregiving shortens telomeres and places caregivers at risk of early mortality, these results demonstrate the potential need of a more balanced narrative about caregiving.

Investigating the impact of early-life adversity on physiological, immune, and gene expression responses to acute stress: A pilot feasibility study.

OBJECTIVE: Exposure to early-life adversity (ELA) can result in long-term changes to physiological systems, which predispose individuals to negative health outcomes. This biological embedding of stress-responsive systems may operate via dysregulation of physiological resources in response to common stressors. The present pilot study outlines a novel experimental design to test how young adults' exposure to ELA influences neuroendocrine and inflammatory responses to acute stress. MATERIALS AND METHODS: Participants were 12 males (mean age = 21.25), half of whom endorsed at least three significant adverse events up to age 18 years ('ELA group'), and half who confirmed zero ('controls'). Using a randomized within-subjects, between-groups experimental design, we induced acute psychosocial stress (Trier Social Stress Test, TSST), and included a no-stress control condition one week apart. During these sessions, we obtained repeated measurements of physiological reactivity, gene expression of the glucocorticoid receptor (NR3C1), and plasma levels of pro-inflammatory cytokines (IL-1ß, IL-6, IL-8 and TNFα) over a 4-hour window post-test. RESULTS: In this pilot study, the ELA group evinced higher cortisol response and blunted NR3C1 gene expression in response to the TSST compared with controls, while no differences were observed in the no-stress condition. For pro-inflammatory cytokines, only IL-6 increased significantly in response to the TSST, with no differences between the two groups. CONCLUSION: Overall, this pilot feasibility study provides a framework to investigate the biological embedding of early-adversity via dysregulation across physiological and genomic systems in response to acute psychosocial stress. ELA may program such systems in a maladaptive manner more likely to manifest during times of duress, predisposing individuals to the negative health consequences of everyday stressors. Future studies with larger sample size including both males and females are needed to replicate and expand upon these preliminary findings.