Introduction: Recurrent miscarriage (RM; ≥3 consecutive pregnancy losses) occurs in 1-3% of fertile couples. No biomarkers with high predictive value of threatening miscarriage have been identified. We aimed to profile whole-genome differential gene expression in RM placental tissue, and to determine the protein levels of identified loci in maternal sera in early pregnancy.
Methods: GeneChips (Affymetrix(®)) were used for discovery and Taqman RT-qPCR assays for replication of mRNA expression in placentas from RM cases (n = 13) compared to uncomplicated pregnancies matched for gestational age (n = 23). Concentrations of soluble TRAIL (sTRAIL) and calprotectin in maternal serum in normal first trimester (n = 35) and failed pregnancies (early miscarriage, n = 18, late miscarriage, n = 4; tubal pregnancy, n = 11) were determined using ELISA.
Results: In RM placentas 30 differentially expressed (with nominal P-value < 0.05) transcripts were identified. Significantly increased placental mRNA expression of TNF-related apoptosis-inducing ligand (TRAIL; P = 1.4 × 10(-3); fold-change 1.68) and S100A8 (P = 7.9 × 10(-4); fold-change 2.56) encoding for inflammatory marker calprotectin (S100A8/A9) was confirmed by RT-qPCR. When compared to normal first trimester pregnancy (sTRAIL 16.1 ± 1.6 pg/ml), significantly higher maternal serum concentration of sTRAIL was detected at the RM event (33.6 ± 4.3 pg/ml, P = 0.00027), and in pregnant women, who developed an unpredicted miscarriage 2-50 days after prospective serum sampling (28.5 ± 4.4 pg/ml, P = 0.039). Women with tubal pregnancy also exhibited elevated sTRAIL (30.5 ± 3.9 pg/ml, P = 0.035). Maternal serum levels of calprotectin were neither diagnostic nor prognostic to early pregnancy failures (P > 0.05).
Conclusions: The study indicated of sTRAIL as a potential predictive biomarker in maternal serum for early pregnancy complications.
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