Circulating Chemerin Is Elevated in Women With Preeclampsia.

BACKGROUND: Preeclampsia is a severe complication of pregnancy. Chemerin is an adipokine secreted from adipose tissue and highly expressed in placenta. This study evaluated the biomarker potential of circulating chemerin to predict preeclampsia. METHODS: Maternal plasma and placenta were collected from women with early-onset preeclampsia (<34 weeks), with preeclampsia and eclampsia, or before preeclampsia diagnosis (36 weeks). Human trophoblast stem cells were differentiated into syncytiotrophoblast or extravillous trophoblasts across 96 hours. Cells were cultured in 1% O2 (hypoxia) or 5% O2 (normoxia). Chemerin was measured by enzyme-linked immunosorbent assay (ELISA) and RARRES2 (gene coding chemerin) by reverse transcription-quantitative polymerase chain reaction. RESULTS: Circulating chemerin was increased in 46 women with early-onset preeclampsia (<34 weeks) compared to 17 controls (P < .0006). Chemerin was increased in placenta from 43 women with early-onset preeclampsia compared to 24 controls (P < .0001). RARRES2 was reduced in placenta from 43 women with early-onset preeclampsia vs 24 controls (P < .0001). Chemerin was increased in plasma from 26 women with established preeclampsia (P = .006), vs 15 controls. Circulating chemerin was increased in 23 women who later developed preeclampsia vs 182 who did not (P = 3.23 × 10-6). RARRES2 was reduced in syncytiotrophoblast (P = .005) or extravillous trophoblasts (P < .0001). Hypoxia increased RARRES2 expression in syncytiotrophoblast (P = .01) but not cytotrophoblast cells. CONCLUSIONS: Circulating chemerin was elevated in women with early-onset preeclampsia, established preeclampsia, and preceding preeclampsia diagnosis of preeclampsia. RARRES2 was dysregulated in placenta complicated by preeclampsia and may be regulated through hypoxia. Chemerin may have potential as a biomarker for preeclampsia but would need to be combined with other biomarkers.

Endothelial protein C receptor is increased in preterm preeclampsia and fetal growth restriction.

Placental dysfunction is the leading cause of both preeclampsia and fetal growth restriction. This study aimed to characterize endothelial protein C receptor (EPCR) in preterm preeclampsia, term preeclampsia, and fetal growth restriction (defined by delivery of a small for gestational age [SGA] infant [<10% birthweight centile]) and examine its regulation in primary syncytiotrophoblast. Placental EPCR mRNA and protein were significantly increased in patients with preterm preeclampsia (<34 weeks gestation) compared to gestation-matched controls (p < .0001). In the plasma, EPCR was also significantly elevated (p = .01) in established preterm preeclampsia while its substrate, protein C (PC) was significantly reduced (p = .0083). Placentas from preterm small for gestational age (SGA) cases, had elevated EPCR mRNA expression (p < .0001) relative to controls. At 36 weeks, no significant changes in plasma EPCR were detected in samples from patients destined to develop preeclampsia or deliver an SGA infant at term. In terms of syncytiotrophoblast, hypoxia significantly increased EPCR mRNA expression (p = .008), but Tumor Necrosis Factor Alpha (TNF-α) decreased EPCR mRNA. Interleukin-6 (IL-6) had no significant effect on EPCR mRNA expression. When isolated syncytiotrophoblast was treated with metformin under hypoxia (1% O2 ) or normoxia (8% O2 ), EPCR mRNA expression was significantly reduced (p = .008) relative to control. In conclusion, EPCR is markedly elevated in the placenta and the circulation of patients with established preterm preeclampsia and placental increases may be associated with hypoxia. Additionally, fetal growth-restricted pregnancies (as defined by the delivery of an SGA infant) also demonstrated elevated placental EPCR.

Circulating Activin A is elevated at 36 weeks' gestation preceding a diagnosis of preeclampsia.

Activin A is aberrantly expressed by the preeclamptic placenta and circulating levels have been investigated as a potential biomarker for the disease. In a nested case-control study we measured Activin A levels in maternal plasma at 28- and 36-weeks' gestation preceding term preeclampsia diagnosis. At 28 weeks Activin A was not significantly altered (n = 73 destined to develop preeclampsia vs n = 191 controls). At 36 weeks' gestation Activin A was significantly increased in 40 women destined to develop preeclampsia relative to 201 controls (p < 0.0001). These findings provide further validation of Activin A as a potential biomarker for subsequent term preeclampsia.

A disintegrin and metalloproteinase 12 (ADAM12) is reduced at 36 weeks' gestation in pregnancies destined to deliver small for gestational age infants.

First trimester circulating ADAM12 is reduced in fetal growth restriction (FGR) and preeclampsia. We measured plasma ADAM12 at 36 weeks' gestation preceding diagnosis of term preeclampsia or delivery of a small for gestational age (SGA; birthweight <10th centile) infant in two independent cohorts (Cohort 1 90 SGA, 41 preeclampsia, 862 controls; Cohort 2121 SGA 23 preeclampsia; 190 controls). ADAM12 was reduced with SGA in both cohorts (p = 0.0015 and 0.011 respectively), and further reduced with birthweight <5th centile (p = 0.0013 and 0.0058 respectively). This validates ADAM12 as an SGA biomarker near term. Circulating ADAM12 preceding preeclampsia was not consistently altered.

Circulating syndecan-1 is reduced in pregnancies with poor fetal growth and its secretion regulated by matrix metalloproteinases and the mitochondria.

Fetal growth restriction is a leading cause of stillbirth that often remains undetected during pregnancy. Identifying novel biomarkers may improve detection of pregnancies at risk. This study aimed to assess syndecan-1 as a biomarker for small for gestational age (SGA) or fetal growth restricted (FGR) pregnancies and determine its molecular regulation. Circulating maternal syndecan-1 was measured in several cohorts; a large prospective cohort collected around 36 weeks' gestation (n = 1206), a case control study from the Manchester Antenatal Vascular service (285 women sampled at 24-34 weeks' gestation); two prospective cohorts collected on the day of delivery (36 + 3-41 + 3 weeks' gestation, n = 562 and n = 405 respectively) and a cohort who delivered for preterm FGR (< 34 weeks). Circulating syndecan-1 was consistently reduced in women destined to deliver growth restricted infants and those delivering for preterm disease. Syndecan-1 secretion was reduced by hypoxia, and its loss impaired proliferation. Matrix metalloproteinases and mitochondrial electron transport chain inhibitors significantly reduced syndecan-1 secretion, an effect that was rescued by coadministration of succinate, a mitochondrial electron transport chain activator. In conclusion, circulating syndecan-1 is reduced among cases of term and preterm growth restriction and has potential for inclusion in multi-marker algorithms to improve detection of poorly grown fetuses.