Uterine protein oxidative modifications may condition trophoblast function

Abstract

Aim: Evaluate whether protein carbonylation resulting from uterine altered redox imbalance interferes with extravillous trophoblast viability. Introduction: Local redox homeostasis is believed to have a pivot role in uterine transformation necessary for blastocyst implantation and placenta development. By contrast, redox status imbalance plays a role in deficient placentation and the development of pregnancy-related complications (e.g. preeclampsia or gestational diabetes) with increased incidence in older women. Thus, it was hypothesized that at an older reproductive age, loss of redox homeostasis is a contributor to disruption of foetal/placental interactions and the development of such complications. Methods: Uterine human samples were collected at delivery by elective caesarean section. The protocol was approved by the ethical committee of “Centro Materno-Infantil do Porto”, volunteers gave written consent to be included in the study. Total protein carbonylation was detected by oxyblot and protein expression was quantified by western blotting. Specific protein carbonylation was verified by immunoprecipitation. Albumin was carbonylated using hydrogen peroxide (H2O2), followed by dialysis, and western blotting to confirm carbonylated albumin. HST-8SV neo extravillous trophoblasts were treated with carbonylated/non-carbonylated albumin, followed by cell viability assay. A P value less than 0.05 was assumed to denote significant difference. Results: At the placental site, carbonylated albumin normalized to total albumin expression showed a positive and significant association with maternal age. (r=0.6909, P=0.0021) In vitro, carbonylated albumin displayed a cytotoxic effect, at concentrations ranging from 10 to 100μg/ml. Lower concentrations did not affect trophoblast viability. Conclusion: Uterine aging is accompanied by selective albumin oxidative modifications, which appears to interfere with trophoblast ability to invade and transform the maternal placental site.