The maternal serum thiol/disulfide homeostasis is impaired in pregnancies complicated by idiopathic intrauterine growth restriction

A comprehensive assessment of redox balance in small for gestational age newborns and their mothers

OBJECTIVE

The objective of this study was to assess oxidative stress in small for gestational age (SGA) newborns and their mothers by evaluating intra- and extracellular thiol homeostasis and the quantification of major oxidants and antioxidants.

METHODS

A total of 75 mothers and their 75 newborns (43 SGA) were enrolled in this study. Thiol-disulfide homeostasis, serum myeloperoxidase, catalase, total oxidant, and antioxidant status were analyzed. Additionally, erythrocytic glutathione (GSH) homeostasis was measured.

RESULTS

Although native and total thiol levels were decreased, disulfide levels were increased in SGA groups. Additionally, myeloperoxidase activity and total oxidant status levels were significantly elevated whereas total antioxidant status levels and enzymatic antioxidant systems were diminished in SGA groups. Similarly, intra-erythrocytic GSH homeostasis was shifted in favor of oxidants in SGA groups.

CONCLUSION

Our results demonstrate that insufficient antioxidant systems in mothers and a robust source of oxidative stress in SGA might contribute to the pathophysiology of SGA births.

The evaluation of maternal systemic thiol/disulphide homeostasis for the short-term prediction of preterm birth in women with threatened preterm labour: a pilot study

The aim of this study was to investigate maternal systemic thiol/disulphide homeostasis (TDH) for the short-term prediction of preterm birth in women with threatened preterm labour (TPL). This prospective study included 75 pregnant women whose pregnancies were complicated by TPL. Thirty-seven of them delivered within 7 days and 38 of them delivered beyond 7 days. Maternal serum samples were collected at the day of diagnosis and the TDH was measured. The maternal disulphide level was significantly higher in pregnant women who delivered within 7 days (25.0 ± 9.8 μmol/L vs 19.4 ± 9.8 μmol/L, p: .015). The threshold value of 22.1 μmol/L for maternal disulphide level predicted delivery within 7 days with 62.2% sensitivity and 60.5% specificity (area under curve 0.651, confidence interval 0.53-0.78). The likelihood ratios for short cervix (≤25 mm) and maternal disulphide level (≥22 μmol/L) to predict delivery within 7 days was found to be 8.7 and 7.3, respectively. The likelihood ratio of combining two tests to predict delivery within 7 days was found to be 11.4. The maternal TDH, which is an indicator of oxidative stress status in maternal compartment, is disturbed in TPL cases who delivered within 7 days. Elevated maternal disulphide level along with cervical length screening predicts a short latency period in pregnancies with TPL. IMPACT STATEMENTWhat is already known on this subject? Spontaneous preterm delivery is one of the major complication of pregnancy and the common cause of neonatal morbidity and mortality. Threatened preterm labour (TPL) is also a frequent complaint in obstetric emergency care units in all around the world. Triaging women with TPL is mandatory for planning further management therapies, since the most of them will eventually deliver at term. Only the measurement of cervical length in symptomatic women has moderate accuracy in predicting preterm delivery. Short cervix is described as an independent predictor of preterm delivery in women with TPL, its predictive accuracy as a single measurement is relatively limited. On this account, several potential markers like foetal fibronectin in the cervicovaginal fluid, salivary oestriol, prolactin in vaginal discharge, maternal serum calponin and interleukin-6 in the amniotic fluid were examined to predict preterm delivery in previous studies. However, none of them represented an excessive predictive accuracy like high sensitivity, PPV or NPV.What do the results of this study add? We report a method which has higher diagnostic and predictive performance to identifying TPL women with high risk of preterm delivery. According to the current literature, there are accumulated data about the correlation between oxidative stress (OS) and preterm delivery regardless of the amniotic membrane status. However, it is still debated whether OS is a trigger or a consequence of preterm delivery. Our study provides evidence for the first time that maternal serum thiol/disulphide homeostasis, which is an indicator of OS in maternal compartment, is disturbed in TPL cases who delivered within 7 days. The high disulphide level in maternal serum, along with cervical length measurement (short cervix) accurately predicts a short latency period in TPL cases.What are the implications of these findings for clinical practice and/or further research? This novel test combination (maternal serum disulphide level and cervical length measurement) could be used clinically to triage pregnant women presenting with TPL, avoiding overtreatment, unnecessary hospitalisations and increased medical costs. The future research would be addressed on reducing maternal OS by using new antioxidant treatment strategies to improve perinatal and long-term childhood outcomes.

Thiol-disulfide homeostasis: an integrated approach with biochemical and clinical aspects

Dynamic thiol-disulfide homeostasis (TDH) is a new area has begun to attract more scrutiny. Dynamic TDH is reversal of thiol oxidation in proteins and represents the status of thiols (-SH) and disulfides (-S-S-). Organic compounds containing the sulfhydryl group is called thiol, composed of sulfur and hydrogen atoms. Disulfides are the most important class of dynamic, redox responsive covalent bonds build in between two thiol groups. For many years, thiol levels were analyzed by several methods. During last years, measurements of disulfide levels have been analyzed by a novel automated method, developed by Erel and Neselioglu. In this method, addition to thiol (termed as native thiol) levels, disulfide levels were also measured and sum of native thiol and disulfide levels were termed as total thiol. Therefore, TDH was begun to be understood in organism. In healthy humans, TDH is maintained within a certain range. Dysregulated dynamic TDH has been implicated several disorders with unknown etiology. A growing body of evidence has demonstrated that the thiol-disulfide homeostasis is involved in variety diseases, such as diabetes mellitus, hypertension, nonsmall cell lung cancer, familial Mediterranean fever (FMF), inflammatory bowel diseases, occupational diseases, gestational diabetes mellitus and preeclampsia. These results may elucidate some pathogenic mechanism or may be a predictor indicating diagnostic clue, prognostic marker or therapeutic sign. In conclusion, protection of the thiol-disulfide homeostasis is of great importance for the human being. Evidence achieved so far has proposed that thiol-disulfide homeostasis is an important issue needs to elucidate wholly.

Evaluation of thiol/disulfide homeostasis in patients with gestational diabetes mellitus

This study aimed to study the dynamic thiol/disulfide homeostasis in pregnant women with gestational diabetes mellitus (GDM). Forty-five pregnant women with GDM and 45 age-matched healthy pregnancies were included in this study. Thiol/disulfide homeostasis was measured using a commercial kit (Rel Assay Diagnostics). The patients with GDM had significantly higher disulfide concentrations than healthy pregnant patients (p = .001). Besides, the GDM group had significantly higher disulfide/total thiol, disüplhide/native thiol, and native thiol/total thiol ratio than healthy pregnant patients (p = .001, p = .001 and p = .001, respectively). The significantly higher concentrations of disulfide, disulfide/total thiol, disüplhide/native thiol, and native thiol/total thiol ratio in women with GDM could be considered as the increased oxidative stress.

Dynamic Thiol/Disulfide Homeostasis in Predicting Adverse Neonatal Outcomes in Fetal Growth Restriction

Aim: The main aim of this study was to investigate thiol/disulfide homeostasis associated with fetal growth restriction (FGR) and to evaluate whether alterations are predictive for adverse neonatal outcomes. Methods: 273 pregnant women (77 with FGR and 196 with normal fetal growth) were enrolled in this prospective case-control study. Results: Native thiol and total thiol were decreased in FGR compared to the control group (p < .001; p < .001). Decreased levels of maternal serum native and total thiol were significantly associated with adverse neonatal outcomes in FGR (OR: 0.983, 95% CI 0.976-0.991, p < .001; OR: 0.983, 95% CI 0.976-0.991, p < .001). Decreased maternal serum total thiol levels were the only significantly associated risk factor with adverse neonatal outcomes in FGR (OR: 0.981, 95% CI 0.963-1.000, p = .046). Conclusion: The decrease in the antioxidants of thiol/disulfide mechanism may be related to the development of both FGR and adverse neonatal outcome in FGR.

Maternal and fetal thiol/disulfide homeostasis in fetal growth restriction

PURPOSE

To evaluate thiol/disulfide homeostasis in both maternal and fetal compartment in the presence of fetal growth restriction (FGR).

MATERIALS AND METHODS

A prospective case-control study was carried out in women with FGR (n: 40) or normally growing fetus (n: 40). FGR was defined as estimated fetal weight below the 10th percentile for the gestational age. Maternal serum and fetal cord blood samples were collected from all participants and native thiol-disulfide exchanges were examined with automated method enabling the measurement of both sides of thiol-disulfide balance.

RESULTS

Native thiol, total thiol and disulfide amounts were decreased in the maternal serum and fetal cord blood of babies born to women with FGR (p < .05). The most sensitive marker was maternal native thiol (82.5, 95% confidence interval, 67.22-92.66%), while the maternal total thiol had highest specificity value (77.5, 95% confidence interval, 61.55-89.16%).

CONCLUSIONS

Maternal and fetal serum thiol/disulfide profiles may use prediction of FGR severity and its neonatal outcome.

Urotensin 2 and Oxidative Stress Levels in Maternal Serum in Pregnancies Complicated by Intrauterine Growth Restriction

Background and objectives: In this study, the aim was to investigate Urotensin 2 (U-II) levels and oxidant/antioxidant system parameters in pregnancies with intrauterine growth restriction (IUGR). Materials and Methods: A total of 36 healthy, pregnant women who had not been diagnosed with IUGR and 36 pregnant women who had been diagnosed with IUGR at the Obstetrics and Gynecology Outpatient Clinic at Gaziantep University Hospital were enrolled in this study. The serum total antioxidant status (TAS), total oxidant status (TOS), thiol-disulfide levels, U-II measurements, and oxidative stress index (OSI) calculations were carried out at the biochemistry laboratory at Gaziantep University. Results: According to this study, there was no statistically significant difference between the group with IUGR and the control group of healthy, pregnant women in terms of total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), native thiol, total thiol, disulfide, disulfide/native thiol, disulfide/total thiol, native thiol/total thiol, and U-II values. There was, however, a positive linear correlation between TOS and total thiol levels in the group with IUGR (p = 0.021, r = 0.384), and a positive linear correlation between OSI and total thiol values in the control group (p = 0.049, r = 0.330). In addition, there was a negative correlation between disulfide levels and gestational weeks at birth in the group with IUGR (p = 0.027, r = 0.369). Conclusions: Consequently, there was no significant difference between the control group and the group with pregnancies complicated by idiopathic IUGR in terms of serum oxidant/antioxidant system parameters and U-II levels. It is necessary to conduct more extensive studies evaluating placental, maternal, and fetal oxidative stress in conjunction in order to investigate the role of oxidative stress in IUGR.

Serum ischemia modified albumin level and its relationship with the thiol/disulfide balance in placenta percreta patients

The pathogenesis of placenta percreta (PP) is not very well known. This study was designed to analyse the oxidative stress (OS), the thiol/disulphide balance, and ischaemia-modified albumin (IMA) the women with PP. The study included 38 pregnant women with PP and 40 similarly aged healthy pregnant women in their third trimester of gestation. We measured the IMA, native and total thiols, and disulphide concentrations in the maternal sera of all of the participating women. The IMA levels were higher and the native and total thiols were lower in the PP group than in the control group. However, there was no statistical significance with respect to the thiol/disulphide balance between the two groups. The results of this study suggest that an increase in the ischaemia and OS and a decrease in the antioxidant status may contribute to the pathogenesis of PP. Impact statement What is already known on this subject? Placenta percreta (PP) is a serious complication of pregnancy. Although there are several studies investigating the pathophysiological mechanism of PP, whether the pathology results from a lack of decidua or from the over-invasiveness of trophoblasts remains controversial. The pathology of PP is poorly understood. What do the results of this study add? This prospective study has shown an increased ischaemia modified albumin (IMA) and a decreased antioxidant capacity in the patients with placenta percreta. The results from 38 women with PP suggest that the serum concentrations of IMA and the oxidative stress parameters may be able to predict PP in cases of uncertainty. What are the implications of these findings for clinical practice and/or further research? The implication of these findings shed light on understanding the pathogenesis of PP for further research.

Evaluation of dynamic thiol-disulfide homeostasis in very low-birth-weighted preterms

BACKGROUND

Thiols are organic compounds containing sulfhydryl groups which exert antioxidant effects via dynamic thiol-disulfide homeostasis. The shift towards disulfides indicates the presence of oxidative environment. Thiol-disulfide homeostasis has not been evaluated in neonates. We aimed to evaluate dynamic thiol-disulfide homeostasis in preterm infants.

METHODS

Preterm infants with birth weight less than 1500 g (25-32 weeks of gestation) were included. Infants with major congenital anomaly, perinatal asphyxia, twin to twin transfusion and infants who were mechanically ventilated and nil by mouth for more than 3 days or fed with formula, had intraventricular hemorrhage ≥ grade 2 or sepsis, received blood/blood product transfusion or inotrope treatment and developed bronchopulmonary dysplasia or retinopathy of prematurity (≥ stage 3), and died were excluded thereafter. Serum thiol-disulfide homeostasis was evaluated for three times: (Baseline, first week, third week). Serum native thiol, total thiol and disulfide were measured (µmol/Lt), disulfide:native thiol, disulfide:total thiol, and native thiol:total thiol ratios were calculated. Wilcoxon's test was used to analyze the significance of change in measurements. Baseline results were analyzed for gender and mode of delivery.

RESULTS

Eighty preterm infants [1255 (1080-1415) grams] were included. Baseline values were native thiol: 209.54 ± 41.83 µmol/L; total thiol: 251.70 ± 45.82 µmol/L; disulfide: 21.08 ± 7.43 µmol/Lt; disulfide:native thiol: 10.49 ± 4.62; disulfide:total thiol: 8.45 ± 2.93; native thiol:total thiol: 83.10 ± 5.87. Thiol levels increased in each measurement, disulfide and disulfide/thiol ratios increased in the first week, decreased in the third week, ratio of native/total thiol decreased in the first week, increased in the third week. No effect of gender or mode of delivery on baseline thiol-disulfide homeostasis was detected.

CONCLUSIONS

The shift in the thiol-disulfide equilibrium towards disulfides in the first week can be attributed to subjection of infants to many oxidative insults. Furthermore, the thiol predominance in the third week could be explained by the decrease in oxidative events and increase in feeding as a supply of antioxidants. This study, displaying the levels of the dynamic thiol-disulfide homeostasis in preterm infants without obvious risks for increased oxidative stress, may provide acceptable range for thiol-disulfide homeostasis in recovering preterm infants.