Placental protein 14 as a potential biomarker for diagnosis of preterm premature rupture of membranes

Abstract

Premature rupture of membranes (PROM) is a common pregnancy complication that frequently results in maternal and perinatal morbidity. The present methods for diagnosing PROM do not satisfy clinical requirements. The present study aimed to examine the proteome profile of amniotic fluid (AF) and maternal plasma, screen unique proteins in AF, and evaluate their diagnostic value for diagnosing PROM. The proteome profiles of AF and maternal plasma were examined via liquid chromatography coupled with tandem mass spectrometry‑based proteomic techniques. The protein expression levels of diagnostic candidates in AF, maternal plasma and vaginal fluid were determined by ELISA analysis and Magnetic Luminex® screening assays. The diagnostic value of potential biomarkers was evaluated using receiver operating characteristic curves. A lateral flow assay was developed based on colloidal gold immunochromatography technology. The present study identified 540 unique proteins in AF, 12 of which were chosen for further detection. The present results demonstrated that expression levels of pulmonary surfactant‑associated protein B, BPI fold‑containing family A member 1, zymogen granule protein 16 homolog B, EGF‑containing fibulin‑like extracellular matrix protein 1, keratin, type II cytoskeletal 4, keratin, type I cytoskeletal 19, placental protein 14 (PP14), insulin‑like growth factor‑binding protein 2, mesothelin and serpin family B member 3 were significantly higher in AF compared with in maternal plasma (P<0.01). Furthermore, PP14 was observed to have excellent diagnostic accuracy for preterm PROM (PPROM), with a respective sensitivity and specificity of 100 and 87.5% when the cutoff value was 0.008 µg/ml. The PP14‑based lateral flow assay demonstrated a visual detection threshold of 0.008 µg/ml. The results from the present study suggested that PP14 may be a novel potential biomarker for PPROM, and may be developed into a lateral flow assay for bedside application to rapidly diagnose PPROM.

Figure 1.

Criteria of selecting proteins for further detection.

Figure 2.

Concentrations of SFTPB, PLUNC, ZG16B, EFEMP1, KRT4, KRT19, PP14, IGFBP2, mesothelin and serpin B3 in AF and maternal plasma. Blank bars mean continuous variables are normally distributed. Filled bars mean continuous variables are non-normally distributed. The normal variables are presented as the mean ± standard deviation (above error bar); the non-normal variable error bars are presented as the median (interquartile range). *P<0.05, **P<0.001. SFTPB, pulmonary surfactant-associated protein B; PLUNC, BPI fold-containing family A member 1; ZG16B, zymogen granule protein 16 homolog B; EFEMP1, EGF-containing fibulin-like extracellular matrix protein 1; KRT4, keratin, type II cytoskeletal 4; KRT19, keratin, type I cytoskeletal 19; PP14, placental protein 14; IGFB2, insulin-like growth factor-binding protein 2; serpin B3, serpin family B member 3; AF, amniotic fluid; ST, second trimester; TT, third trimester.

Figure 3.

Concentrations of KRT19, PP14, IGFBP2, mesothelin and serpin B3 in the VF of women with overall PROM, PROM (<37 weeks) and PROM (≥37 weeks) and overall control, control (<37 weeks) and control (≥37 weeks). Blank bars mean continuous variables are normally distributed. Filled bars mean continuous variables are non-normally distributed. The normal variables are presented as the mean ± standard deviation (above error bar); the normal variables are presented as the median (interquartile range). *P<0.05, **P<0.001. KRT19, keratin, type I cytoskeletal 19; PP14, placental protein 14; IGFBP2, insulin-like growth factor-binding protein 2; serpin B3, serpin family B member 3; VF, vaginal fluid; PROM, premature rupture of membranes.

Figure 4.

Receiver operating characteristic curves of mesothelin, IGFBP2 and PP14 for diagnosing PROM. IGFBP2, insulin-like growth factor-binding protein 2; PP14, placental protein 14; PROM, premature rupture of membranes.

Figure 5.

Results of PP14-based lateral flow assay. (A) A total of 0.005 µg/ml PP14 recombinant protein was added. The strip was negative. (B) A total of 0.008 µg/ml PP14 recombinant protein was added. The strip was positive. PP14, placental protein 14; C, control line; T, test line; S, sample well.