Mitochondrial dysfunction and ovarian aging

Mitochondrial DNA Copy Number in Peripheral Blood in the First Trimester of Pregnancy and Different Preeclampsia Clinical Phenotypes Development: A Pilot Study

Inflammation and oxidative stress are intrinsically linked to early poor placentation, typical of pregnancies complicated by preeclampsia associated with intrauterine growth restriction (PE-IUGR). Low mitochondrial DNA copy number (mtDNAcn) in peripheral blood constitutes a good peripheral surrogate marker of inflammation and oxidative stress. On these basis, we explored a possible correlation between mtDNAcn in peripheral blood in the first trimester of pregnancy and the PE-IUGR onset. To shed light on this issue, we setup a nested case-control study from a prospective cohort of pregnant women undergoing first-trimester aneuploidies screening. Two groups of patients affected by PE classified according to the clinical phenotype were identified: (1) patients who developed PE-IUGR and (2) patients who developed PE associated with appropriate for gestational age intrauterine fetal growth (PE-AGAf). Controls were women with a physiologic pregnancy matched to cases on the basis of age (±6 months, ratio 2:1). Mitochondrial DNA copy number was quantified using real-time polymerase chain reaction and normalized to nuclear DNA. The median (interquartile range) mtDNAcn in peripheral blood in patients with PE-IUGR (n = 12) and in patients with PE-AGAf (n = 16) was 70 (44-97) and 108 (95-145), respectively (P = .004). Both these values were significantly lower than that detected in the control group (161[133-183], P < .001). The area under the receiver-operator curve for PE-IUGR and PE-AGAf were 0.94 (95% confidence interval [CI]: 0.88-1.00, P < .001) and 0.81 (95%CI: 0.70-0.91, P < .001), respectively. In conclusion, MtDNAcn in peripheral blood resulted significantly lower both in patients affected by PE-IUGR and in those affected by PE-AGAf when compared to controls. The accuracy of this biomarker resulted particularly good in predicting PE-IUGR.

Astragalus root induces ovarian β‑oxidation and suppresses estrogen‑dependent uterine proliferation

Continuous estrogen stimulation in the uterus has been known to cause excess proliferation of the functional layer of endometrium, resulting in endometrial hyperplasia and leading to infertility. Estrogens can modulate other nuclear receptor signaling pathways, such as peroxisome proliferator‑activated receptors (PPARs). Astragalus root (AsR) has exhibited strong PPARα agonistic activity. Female Imprinting Control Region mice were fed a powder diet that included 5% AsR hot water extract or 0.1% bezafibrate as a positive control for 56 days to investigate AsR effects on the reproductive tract, ovary and uterus. AsR resulted in upregulation of the expression of uterine and ovarian PPARα mRNA by 2.5‑fold, and 1.5‑fold, respectively, compared with controls. AsR significantly increased ovarian expression levels of mitochondrial 2,4‑dienoyl‑CoA reductase (mDECR), an auxiliary enzyme involved in β‑oxidation. AsR‑fed mice also exhibited a significant increase in blood estradiol levels and tended to have higher ovary weight. AsR resulted in significantly decreased uterine weight and mDECR expression levels. It has been reported that a PPARα agonist suppresses the development of estrogen‑dependent endometrial hyperplasia. These findings raise the possibility that AsR suppresses estrogen‑dependent endometrial hyperplasia and ovarian dysfunction leading to infertility.

Mitochondrial DNA copy number in peripheral blood: a potential non-invasive biomarker for female subfertility

PURPOSE

Low mitochondrial DNA (mtDNA) content in oocytes and in cumulus cells is an indicator of poor oocyte quality. Moreover, initial evidence showed a correlation between mtDNA content in cumulus cells and mtDNA copy number in peripheral blood cells. On these bases, we deemed of interest investigating the correlation between mtDNA copy number in peripheral blood and natural fecundity.

METHODS

This is a nested case-control study drawn from a prospective cohort of pregnant women referred for routine first trimester screening for aneuploidies (from 11 + 0 to 12 + 6 weeks of gestation) between January 2012 and March 2013 at the "Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico" of Milan, Italy. Cases were subfertile women who attempted to become pregnant for 12-24 months. Controls were the two subsequently age-matched women who became pregnant in less than 1 year. MtDNA was quantified using real-time PCR and normalized to nuclear DNA.

RESULTS

One hundred and four subfertile women and 208 controls were selected. The median (IQR) mtDNA copy number was 95 (73-124) and 145 (106-198), respectively (p < 0.001). The area under the ROC curve was 0.73 (95% CI 0.67-0.79) (p < 0.001). The Youden index was 105 mtDNA copy number. The crude OR for subfertility in women with mtDNA copy number below this threshold was 5.72 (95% CI 3.43-9.55). The accuracy of mtDNA copy number assessment in peripheral blood progressively decreased with increasing female age.

CONCLUSIONS

Low mtDNA copy number in peripheral blood is associated with an increased risk of subfertility and may represent a biomarker of natural fecundity.