E-Poster Presentation ESA-SRB-ANZBMS 2021

Leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and its ligands are reduced in preeclamptic placentas. (#569)

Georgia P Wong 1 2 , Natalie J Hannan 1 2 , Stephen Tong 1 2 , David G Simmons 3 , Ping Cannon 1 2 , Manju Kandel 1 2 , Josh Masci 1 2 , Tuong-Vi Nguyen 1 2 , Tu'uhevaha J Kaitu'u-Lino 1 2
  1. Obstetrics and Gynaecology, Mercy Hospital for Women, University of Melbourne, Heidelberg, Victoria, Australia
  2. Mercy Perinatal, Mercy Hospital for Women, Heidelberg, Victoria, Australia
  3. School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia

Lgr5 is an established stem cell marker and Wnt signalling pathway member with abundance in high surface area tissues, namely the colon and lung. The placenta is a complex organ of high surface area and significant branching dedicated to maternal-fetal exchange. Lgr5 has not been explored in human placental development, nor in placental diseases including preeclampsia. This study sought to characterise Lgr5 in preeclampsia and assess its role in isolated human (cyto)trophoblast (placental) stem cells (hTSCs).

Lgr5 was measured in placentas of patients presenting with early-onset (<34-weeks gestation, n=81 vs n=19 controls) and late-onset preeclampsia (≥34-weeks, n=20 vs n=61 controls). In both cohorts’ preeclamptic placental samples, Lgr5 mRNA was significantly reduced (p<0.0001, p=0.0046 respectively). Western blot of preeclamptic vs preterm control placental lysates confirmed this. Immunohistochemistry localised Lgr5’s expression to both cytotrophoblast (progenitor) and syncytiotrophoblast (terminally differentiated) populations in human placenta. In contrast to primary first trimester placental cells, the hTSCs have very low expression of Lgr5. Thus, we over-expressed Lgr5 to assess its functional role in proliferation and differentiation. Preliminary data suggests increasing cytotrophoblast Lgr5 alone does not alter cytotrophoblast proliferation or differentiation to syncytiotrophoblasts or extra-villous cytotrophoblasts.

Since Lgr5-mediated signalling requires binding of its ligands, R-spondins 1, -3 and -4; their expression was investigated in control vs preeclamptic placentas and maternal plasma. R-spondins 1 and -4 were reduced in pre-term preeclamptic placentas (p=0.0005, p=0.0003 respectively), while R-spondin 3 was unaltered. In maternal plasma, R-spondin 4 was undetectable yet R-spondins 1 and -3 were elevated in preeclampsia. Additional functional studies modulating both Lgr5 and its ligands are currently underway.

This study demonstrates placental Lgr5 and its ligands R-spondins 1 and -4 are reduced in preeclampsia. Their effects on placental cell function and placental development are currently being explored in detail to elucidate potential roles in preeclampsia pathogenesis.