Identification of autophagic vacuoles and regulators of autophagy in villous trophoblast from normal term pregnancies and in fetal growth restriction

Abstract

Fetal growth restriction (FGR) is a serious pregnancy complication associated with increased perinatal mortality and morbidity. Although the majority of cases with FGR result from placental dysfunction, the pathophysiology is incompletely understood. Autophagy is a physiological form of cell degradation exacerbated by nutrient and oxygen restriction, which are both thought to play a role in the aetiology of FGR. We hypothesized that autophagy is present in the normal human placenta and is exaggerated in FGR. Autophagy was assessed in electron micrographs from normal and FGR placentas and by Western blotting for LC3B and LAMP-2. The localization of regulators of autophagy was examined by immunohistochemistry. Culture of BeWo cells was used to investigate whether nutrient and/or oxygen deprivation can induce autophagy in trophoblast. Autophagy predominantly localized to the syncytiotrophoblast layer and autophagosomes were more frequent in FGR. The regulators LAMP-2, LC3B, Beclin-1, ATG 5, ATG9 and ATG16L1 were all present in villous trophoblast. LAMP-2 immunostaining was more punctate in FGR. In BeWo cells, culture in reduced oxygen tension and/or serum depleted conditions led to the appearance of autophagosomes which was associated with changes in LAMP-2 configuration. We conclude that autophagy in human term placenta may be involved in the placental dysfunction present in FGR.

Keywords::

• Autophagy
• fetal growth restriction
• LAMP-2
• LC3B
• programmed cell death
• placenta

Acknowledgements

The authors would like to thank Dr. Susan Greenwood for critical appraisal of the manuscript.

Declaration of Interest: This work was supported by grants from the Peel Medical Research Trust and the Holly Martin Stillbirth Research Fund. The authors have no conflicts of interest regarding the content of this work. The authors alone are responsible for the content and writing of this manuscript.