Maternal human telomerase reverse transcriptase variants are associated with preterm labor and preterm premature rupture of membranes

Accelerated epigenetic clock aging in maternal peripheral blood and preterm birth

BACKGROUND

Epigenetic clocks use CpG DNA methylation to estimate biological age. Acceleration is associated with cancer, heart disease, and shorter life span. Few studies evaluate DNA methylation age and pregnancy outcomes. AgeAccelGrim is a novel epigenetic clock that combines 7 DNA methylation components.

OBJECTIVE

This study aimed to determine whether maternal biological aging (via AgeAccelGrim) is associated with early preterm birth.

STUDY DESIGN

A prospective cohort of patients with singleton pregnancies and at high risk of spontaneous preterm birth delivering at a tertiary university hospital were included in this study. Genome-wide CpG methylation was measured using the Illumina EPIC BeadChip (Illumina, Inc, San Diego, CA) from maternal blood samples obtained at <28 weeks of gestation. AgeAccelGrim and its 7 DNA methylation components were estimated by the Horvath DNA methylation age online tool. Positive values are associated with accelerated biological aging, whereas negative values are associated with slower biological aging relative to each subject's age. The primary outcome was preterm birth at <34 weeks of gestation (any indication). The secondary outcomes were preterm birth at <37 and <28 weeks of gestation. AgeAccelGrim was analyzed as a continuous variable and in quartiles. Exploratory analyses evaluated each of the 7 DNA methylation components included in the composite AgeAccelGrim. Data were analyzed by chi-square test, t test, rank-sum test, logistic regression (controlling a priori for maternal age, cell counts, low socioeconomic status, and gestational age at the time of sample collection), and Kaplan-Meier survival analyses. The log-rank test was used to test the equality of the survival functions.

RESULTS

Overall, 163 patients met the inclusion criteria. Of the patients, 48%, 39%, and 21% delivered at <37, <34, and <28 weeks of gestation, respectively. The median AgeAccelGrim was -0.35 years (interquartile range, -2.24 to 1.31) for those delivering at term. Those delivering preterm had higher AgeAccelGrim values that were inversely proportional to delivery gestational age (preterm birth at <37 weeks of gestation: +0.40 years [interquartile range: -1.21 to +2.28]; preterm birth at <34 weeks of gestation: +0.51 years [interquartile range: -1.05 to +2.67]; preterm birth at <28 weeks of gestation: +1.05 years [interquartile range: -0.72 to +2.72]). Estimated DNA methylation of the 7 epigenetic clock component values was increased among those with preterm birth at <34 weeks of gestation, although the differences were only significant for DNA methylation of plasminogen activation inhibitor 1. In regression models, AgeAcccelGrim was associated with an elevated risk of preterm birth with increasing magnitude for increasing severity of preterm birth. For each 1-year increase in the AgeAccelGrim value (ie, each 1-year increase in biological age compared with chronologic age), the adjusted odds of preterm birth were 11% (adjusted odds ratio, 1.11; 95% confidence interval, 1.00-1.24), 13% (adjusted odds ratio, 1.13; 95% confidence interval, 1.01-1.26), and 18% (adjusted odds ratio, 1.18; 95% confidence interval, 1.04-1.35) higher for preterm birth at <37, <34, and <28 weeks of gestation, respectively. Similarly, individuals with accelerated biological aging (≥75th percentile AgeAccelGrim) had more than double the odds of preterm birth at <34 weeks of gestation (adjusted odds ratio, 2.36; 95% confidence interval, 1.10-5.08) and more than triple the odds of preterm birth at <28 weeks of gestation (adjusted odds ratio, 3.89; 95% confidence interval, 1.61-9.38). The adjusted odds ratio for preterm birth at <37 weeks of gestation was 1.73 but spanned the null (adjusted odds ratio, 1.73; 95% confidence interval, 0.81-3.69). In Kaplan-Meier survival analyses, those in the highest AgeAccelGrim quartile delivered the earliest (log-rank P value of <.001).

CONCLUSION

Accelerated biological aging was associated with preterm birth among high-risk patients. Future research confirming these findings and elucidating factors that slow biological aging may improve birth outcomes.

Telomere length and hTERT genetic variants as potential prognostic markers in multiple myeloma

Telomere dysfunction is a notable event observed in many cancers contributing to their genomic instability. A major factor controlling telomere stability is the human telomerase reverse transcriptase catalytic subunit (hTERT). Telomere shortening has been observed in multiple myeloma (MM), a plasma cell malignancy with a complex and heterogeneous genetic background. In the present study, we aimed to analyse telomere length and hTERT genetic variants as potential markers of risk and survival in 251 MM patients. We found that telomere length was significantly shorter in MM patients than in healthy individuals, and patients with more advanced disease (stage III according to the International Staging System) had shorter telomeres than patients with less advanced disease. MM patients with hTERT allele rs2736100 T were characterized with significantly shorter progression-free survival (PFS). Moreover, allele rs2736100 T was also found to be less common in patients with disease progression in response to treatment. hTERT rs2853690 T was associated with higher haemoglobin blood levels and lower C-reactive protein. In conclusion, our results suggest that telomere length and hTERT genetic variability may affect MM development and can be potential prognostic markers in this disease.

Spontaneous Preterm Birth: Elevated Galectin-3 and Telomere Shortening May Reflect a Common Pathway of Enhanced Inflammation and Senescence

Preterm delivery complicates 5-12% of pregnancies and is the primary cause of neonatal morbidity and mortality. The pathophysiology of preterm labor and parturition is not fully known, although it is probably related to inflammation and placental senescence. Telomere shortening is related to senescence and galectin-3 (Gal-3) protein is involved in cell growth, differentiation, inflammation, and fibrosis. This study examined changes in Gal-3 expression and telomere homeostasis (which represent inflammatory and stress markers) in maternal blood and placental tissue of spontaneous preterm births (SPTB) and uncomplicated, spontaneous term pregnancies (NTP) during labor. Participants included 19 women with NTP and 11 with SPTB who were enrolled during admission for delivery. Maternal blood samples were obtained along with placental tissue for Gal-3 analysis and telomere length evaluation. Gal-3 protein expression in placental tissue was increased in SPTB compared to NTP (fold change: 1.89 ± 0.36, P < 0.05). Gal-3 immunohistochemistry demonstrated strong staining in placental extravillous trophoblast tissue from SPTB. Maternal blood levels of Gal-3 protein were elevated in SPTB compared to NTP (19.3 ± 1.3 ng/ml vs. 13.6 ± 1.07 ng/ml, P = 0.001). Placental samples from SPTB had a higher percentage of trophoblasts with short telomeres (47.6%) compared to NTP (15.6%, P < 0.0001). Aggregate formation was enhanced in SPTB (7.8%) compared to NTP (1.98%, P < 0.0001). Maternal blood and placental samples from SPTB had shorter telomeres and increased Gal-3 expression compared to NTP. These findings suggest that increased senescence and inflammation might be factors in the abnormal physiology of spontaneous preterm labor.

Molecular and endocrine mechanisms involved in preterm birth

Preterm birth is a worldwide social problem. Incidence rates may vary from 5 to 18% of all deliveries, with important differences observed between developed and developing countries. Preterm birth has a negative impact on newborns and neonatal mortality and morbidity are high. Despite improvements in modern neonatal care, we know little of the mechanisms that determine the onset and development of preterm birth. Infections seem to be one the most important triggers, determining the activation of protective mechanisms aimed at ending the pregnancy and safeguarding the health of the woman. However, threatened preterm birth often occurs even in women who do not have any ongoing infectious process. Of these, which are the majority, the causes and the activation mechanisms remain unknown or unclear; however, there are several molecular and endocrine mechanisms that finally lead to preterm birth. In this review, we seek to shed light and summarize the molecular and endocrine mechanisms underlying the development of preterm birth. Their understanding could help us to understand the dynamics of premature birth but, above all, to allow an early diagnosis and primary prevention of the problem.

Epigenetic age and pregnancy outcomes: GrimAge acceleration is associated with shorter gestational length and lower birthweight

BACKGROUND

Advanced biological aging, as measured by epigenetic aging indices, is associated with early mortality and morbidity. Associations between maternal epigenetic aging indices in pregnancy and pregnancy outcomes, namely gestational length and birthweight, have not been assessed. The purpose of this study was to examine whether epigenetic age during pregnancy was associated with gestational length and birthweight.

RESULTS

The sample consisted of 77 women from the Los Angeles, CA, area enrolled in the Healthy Babies Before Birth study. Whole blood samples for DNA methylation assay were obtained during the second trimester (15.6 ± 2.15 weeks gestation). Epigenetic age indices GrimAge acceleration (GrimAgeAccel), DNAm PAI-1, DNAm ADM, and DNAm cystatin C were calculated. Gestational length and birthweight were obtained from medical chart review. Covariates were maternal sociodemographic variables, gestational age at blood sample collection, and pre-pregnancy body mass index. In separate covariate-adjusted linear regression models, higher early second trimester GrimAgeAccel, b(SE) = - .171 (.056), p = .004; DNAm PAI-1, b(SE) = - 1.95 × 10-4 (8.5 × 10-5), p = .004; DNAm ADM, b(SE) = - .033 (.011), p = .003; and DNAm cystatin C, b(SE) = 2.10 × 10-5 (8.0 × 10-5), p = .012, were each associated with shorter gestational length. Higher GrimAgeAccel, b(SE) = - 75.2 (19.7), p < .001; DNAm PAI-1, b(SE) = - .079(.031), p = .013; DNAm ADM, b(SE) = - 13.8 (3.87), p = .001; and DNAm cystatin C, b(SE) = - .010 (.003), p = .001, were also associated with lower birthweight, independent of gestational length.

DISCUSSION

Higher maternal prenatal GrimAgeAccel, DNAm PAI-1, DNAm ADM, and DNAm cystatin C were associated with shorter gestational length and lower birthweight. These findings suggest that biological age, as measured by these epigenetic indices, could indicate risk for adverse pregnancy outcomes.

Telomere Length and Telomerase Activity in Foetal Membranes from Term and Spontaneous Preterm Births

The reduction of telomere length, the protective cap structures of chromosomes, is one of the biomarkers of senescence (a mechanism of ageing), and ageing of foetal gestational tissues is associated with both term and preterm parturition. A mechanism regulating telomere length is the activity of telomerase, an enzyme that adds telomere fragments during DNA replication and cell division; however, its role in regulating telomere length is not well studied in gestational tissues. The objective of this study is to correlate telomere length and telomerase activity in foetal membranes from term and spontaneous preterm births. Foetal membrane samples were collected from pregnant women experiencing term labour (TL), term not in labour (TNL), preterm premature rupture of membranes (pPROM) and spontaneous preterm labour (PTL) with intact membranes (n = 20/group). Telomere length and telomerase activity were analyzed by relative quantification (T/S), real-time PCR and PCR-based fluorometric detection, respectively. Data were analyzed by ANOVA or the Kruskal-Wallis test. Demographic variables were not statistically different among the groups. Foetal membranes from the TL group showed telomere length reduction compared with those from the others (p < 0.0002). Telomerase activity did not change in foetal membranes irrespective of pregnancy outcome. Telomere shortening in foetal membranes is suggestive of senescence associated with triggering of labour at term; however, this is likely independent of telomerase activity, while prematurity may be associated with senescence, but due to other mechanisms than telomere length reduction in foetal membranes.