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Comparison of Placental Morphology and Glycosylation Patterns of Proteins between normal Pregnancy and IUGR – a pilot study

Abnormal development of placental terminal villi and changes of a nutrient exchange surface alter fetoplacental weight ratio and ponderal index (PI). These measures of neonatal nutritional status are indicators of decreased placental functional efficiency associated with fetal growth restriction. Intrauterine growth restriction (IUGR) provides a significant risk for potential adult diseases, e.g. diabetes type 2, coronary artery disease and hypertension. In our pilot study we analysed 10 placentas quantitatively by stereological methods. 5 placentas were from IUGR pregnancies, and 5 placentas from normal pregnancies were control group. IUGR neonates have significantly lower birthweight (p<0.01), length (p<0.01) and PI=2.2. Stereologic measurements were performed on terminal villi and their compartments: trophoblast, mesenchyme and blood vessels. Results for IUGR placentas have shown: a) significantly smaller absolute volume of terminal villi (Vtv, p<0.05) and volume of their mesenchyme (Vm, p<0.01) ; b) significantly smaller surface area of terminal villi (Stv, p<0.05), their trophoblast (St, p<0.01), mesenchyme (Sm, p<0.01) and blood vessels (Sbv, p<0.05). Therefore, we have undertaken comparison of glycosylation patterns of placental proteins between normal pregnancy and IUGR. Tissues of 7 normal and 11 pathological placentas (IUGR) were homogenized and concentrations of proteins were estimated. Oligosaccharide branches were detected by Western-blot using lectins: SNA, DBA, UEA-I and PHA-E, after discontinuous SDS-PAGE. Comparison of detected sugars in samples of the same gestational age enabled identification of changes in protein glycosylation between normal and pathological placentas. Glycoprotein GP66 was present in most of the analysed samples, showing the same intensity, except in the 39th week of gestation, where it was present only in control sample detected with UEA-I. Two other glycoproteins were detected in control group GP86 in 37th and GP180 in 35th week of gestation with lectin DBA while those were not expressed in IUGR group. With PHA-E we detected GP170 only in pathological placentas of 33-35 weeks of gestation, not in controls. We detected GP52 with lectin SNA only in pathological group not in controls. Our results support the hypothesis that oligosaccharide structures of glycoproteins play an important role during placental development.

IUGR; human placenta; terminal villi; glycoproteins

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