Dissertation committee:
Καλανταρίδου Σοφία , Καθηγήτρια Ιατρική Σχολή, ΕΚΠΑ
Αλεξοπούλου Ευθυμία, Καθηγήτρια Ιατρική Σχολή, ΕΚΠΑ
Παπαδημητρίου Αναστάσιος. Ομότiμος καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Παπαευαγγέλου Βασιλική, Καθηγήτρια, Σχολή , ΕΚΠΑ
Μπριάνα Δέσποινα, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Πέππα Μελπωμένη, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Οικονομίδης Ιγνάτιος, Καθηγητής,Ιατρική Σχολή, ΕΚΠΑ
Summary:
Introduction
Gestational diabetes mellitus GDM is commonly defined as any degree of glucose intolerance recognized during pregnancy.
GDM prevalence ranges between 1-14%, depending on the population studied and the diagnostic tests used. An increasing trend is observed over the past decades.
It is estimated that by 2030, the prevalence of GDM may reach 30% of all pregnancies.
Since GDM is associated with health complications for both mother and offspring, it implies substantial implications for public health with both social and economic burden.
The disturbance in glucose metabolism in pregnant women results in the impairment of many biochemical pathways. Consequently, the cell is exposed to enhanced oxidative stress, cellular antioxidant defense systems are activated, and inflammation ensues. Αlthough placenta appears to act as a barrier, exposure of the fetus to this biochemical cascade, has important implications.
Assessment of oxidative stress is accomplished via measurement of either the amount of antioxidant systems or the derivatives of overwhelming oxidation of cellular molecules. One of the well-recognised antioxidant systems is that of NADPH- Thioredoxin -Thioredoxin Interacting Protein (TXNIP). TXNIP is induced by hyperglycemia and results in increase of the oxidative stress and inflammation, dysfunction of pancreatic beta cells and atherogenesis. Primary goal of this research proposal is to examine the TXNIP expression on placenta and umbilical blood and how this may be altered in pregnancies complicated with GDM.
The manifestation of metabolic syndrome in adult life of offsprings of women with GDM has been recognised as a long term consequence of GDM. Atherosclerosis is one of the main consequences of metabolic syndrome. Long before clinical overt atherosclerosis develops, a subclinical endothelial injury that may last for decades is visible as a thickening of the intima media of great and medium size vessels.
Τhe thioredoxin system consists of NADPH, thioredoxin reductase (TrxR) and thioredoxin (Trx) and is a key antioxidant system. Thioredoxin act as an antioxidant via two cysteine residues of the active site (disulfide domains) reducing NADP to NADPH. Thioredoxin interactive protein (TXNIP) is a component of this system that bounds thioredoxin and renders it unable to fulfill its antioxidant role . Consequently, an increase in TXNIP results in increase of the total oxidative burden of the cell.
Previous studies have made clear the association between gestational diabetes mellitus and metabolic syndrome in offspring΄s adult life. That is probably one of the most well-known long term complications of GDM at the fetus. Major components of metabolic syndrome include atherosclerosis, obesity, glucose intolerance and type 2 DM.
Increased IMT of abdominal aorta is considered a more sensitive marker in detection of early atherosclerosis compared to IMT of carotid artery .
OBJECTIVE:
Focused on the long term consequences of gestational diabetes mellitus and since offspring of DGM women manifest with greater probability metabolic syndrome in adult life, we aim to study the presence of proatheromatic lesions in neonates and correlate them with possible biochemical markers based on the current knowledge in the pathophysiology of diabetes.
Our objective was to explore the prognostic role of abdominal aorta intima-media thickness (aIMT) in neonates exposed to GDM as a possible biomarker for later atherogenesis and its possible correlation with thioredoxin-interacting protein (TXNIP), a protein involved in oxidative stress.
METHODS:
1)Study design
In this prospective, observational study, mother-infant pairs were studied in 2 groups (57 patients with GDM and 51 controls without GDM). In the study are enrolled women of singleton pregnancy, of Caucasian origin who are in a follow up in the outpatient clinic in the 3rd Clinic of Obstetrics and Gynecology of UOA.
During follow up visits anthropometric data (height, body weight, weight gain during pregnancy, BMI calculation) and biochemical parameters are registered.
In the visit at 24-28weeks OGTT test will be performed (75gr glucose load-glucose measurement at O- 1 hour-2 hours from glucose load). GDM was diagnosed according to IADPSG criteria
TXNIP levels were measured in the placenta, as well as in the umbilical and neonatal blood. The data were correlated with aIMT in neonates.
2) Sample collection at labor
Collection of the placenta and umbilical blood samples is done within minutes from labor and was stored at -80C until further processing. Samples from placenta lysates near the umbilical was investigated, for TXNIP protein with Western blot.
Placenta residuals was stored in formalin. Pathology study of TXNIP protein with immunohistochemistry (in situ hybridization with fluorescent antibodies) has taken place in these residuals intersections, in places near the above mentioned spots.
Samples of umbilical blood are centrifigured and serum was examined for TXNIP with ELISA test and biochemical parameters (vit D, TG, Chol, glu and insulin).
3) Neonatal examination
The neonates were examined at the 3rd to 10th day of life, and birth weight, BMI and ponderal index was recorded. Neonatal blood samples were examined for TXNIP with ELISA method.
The thickness of intima-media of abdominal aorta in neonates was measured by an experienced pediatric radiologist at the 3rd to 10th day of life, using the ultrasound system Mindray DC-8 expert (Shenzhen, P. R. China), with linear probe 3-12 Hz and automated IMT program. Ultrasound examination of the abdominal aorta is a non-invasive and well tolerated method for neonates. aIMT is measured twice in a straight non-branched longitudinal segment of abdominal aorta, distal to kidney arteries and above aortic bifurcation according to Mannheim consensus for measurement of IMT in carotid arteries.
RESULTS
In our study body weight of the mother and BMI of mother as birth weight of the neonates were not statistically different between the 2 groups (patients and controls).
aIMT was increased in GDM offspring (patients: median [range]=0.39 mm [0.31-0.46] vs controls: median=0.28 mm [0.23-0.33]; p=0.001) and remained significant after adjusting for possible confounders (e.g., triglycerides, blood pressure, vitamin D, birth weight and gender) with cases having 0,13 points higher IMT value than controls (95% CI: 0.001-0.261 p=0.049).
AIMT was not statistically significant different in offsprings of patients treated with insulin than in patients treated with diet only.
In total TXNIP levels in the placenta, as recorded with total-TXNIP h score in immunohistochemistry were significantly associated with GDM (p=0.001). TXNIP levels were increased in trophoblasts (p=0.001) and syncytiotrophoblasts (p=0.001) and were decreased in endothelial cells (p=0.022) in GDM offspring vs controls. Moreover, TXNIP levels in trophoblasts positively correlated with aIMT (r=0.369; p=0.001).
TXNIP levels in umbilical/neonatal blood measured with ELISA and placenta TXNIP measured with Western blot was not associated with GDM.
CONCLUSIONS
Increased aIMT was demonstrated in the offspring of mothers with GDM. Non-invasive measurement of aIMT could be used as a biomarker to identify children at increased risk for atherogenesis later in life. TXNIP may be associated with GDM and/or aIMT but more studies are needed to examine this relationship.
Early detection of high-risk population is a prerequisite for preventing intervention at suitable time points. The population of children at high risk need to be in a more concrete pediatric follow up with scheduled anthropometric and arterial pressure measurements along with parents-child consultation for potential dietary interventions and adoption of a heathy lifestyle.
Data from recent studies have illustrated the link between food supplements – such as antioxidants ex quercetin, curcumin - and reduction of oxidative stress, showed by reduction of TXNIP levels. Τherefore identification of high risk population is important for future studies concerning dietary interventions and possible drug therapy
Keywords:
Abdominal aorta intima-media thickness, Νeonate, Gestational diabetes mellitus (GDM), Oxidative stress, Thioredoxin-interacting protein TXNIP, Placenta
