A new method for measurement of surfactant specific apoprotein in amniotic fluid

Complement component C4A and apolipoprotein A-I in plasmas as biomarkers of the severe, early-onset preeclampsia

Preeclampsia is a common pregnancy complication that is associated with maternal perinatal morbidity and mortality. Because of its early onset (before 34 weeks) and the potential for serious outcomes, severe, early-onset preeclampsia (sePE) should be regarded as a different form of preeclampsia. It is an important cause of preterm birth and fetal growth restriction and adverse maternal and neonatal outcomes. As there is no diagnostic test yet available for this disease, we used a proteomic approach to identify novel plasma biomarkers for developing severe, early-onset preeclampsia. We conducted case-control studies comparing nulliparous women with severe preeclampsia requiring delivery prior to 34 weeks of gestation with healthy nulliparous women matched by gestational age at sampling. Plasma was depleted of albumin and IgG and analyzed by two-dimensional gel electrophoresis (2DE). Seven specific plasma proteins for early-onset preeclampsia were detected by mass spectrometry had statistically significant expression differences when compared to controls. The expression of complement component C4A and apolipoprotein A-I were validated by immunoblotting. The complement component C4A in the plasmas of sePE women is lower than the severe, late-onset PE (slPE) women [mean ± SD; 3.05 ± 0.14 times reference level (normal/sePE) in sePE women vs. 2.73 ± 0.10 times reference level (normal/slPE) in slPE women, P < 0.05]. Apolipoprotein A-I is higher in sePE women than slPE women [mean ± SD; 1.58 ± 0.14 times reference level (sePE/normal) in sePE women vs. 1.04 ± 0.16 times reference level (slPE/normal) in slPE women, P < 0.05]. Furthermore, C4A can accurately distinguish severe PE (sePE and slPE) from mild PE (mePE and mlPE) and was proved by the results of ELISA. Further studies have been done to determine the relation between PE and hypoxia. JAR cells were cultured under hypoxia for 72 h. Total cellular proteins were gathered and lysed. Lower C4A and higher apolipoprotein A-I had been observed in JAR of hypoxia conditions than normoxia conditions through western blotting. The result proved that PE is correlated with hypoxia. In summary, C4A and apolipoprotein A-I are able to function as markers to distinguish ePE women from lPE women, and severe PE from mild PE, or perhaps even as disease predictors that might become relevant for diagnostics.

Identification of proteomic biomarkers of preeclampsia in amniotic fluid using SELDI-TOF mass spectrometry

OBJECTIVE

To identify proteomic biomarkers in amniotic fluid (AF) that can distinguish preeclampsia (PE) from chronic hypertension (CHTN) and normotensive controls (CTR).

METHODS

AF from women with PE, CHTN, and CTR were subjected to proteomic analysis by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

Proteomic profiling of AF identified 2 biomarkers: peak X (17399.11 Da), which distinguished PE from CTR, and peak Y (28023.34 Da), which distinguished PE and CHTN from CTR. High performance liquid chromatography fractions containing the biomarkers were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in-gel tryptic digestion. The biomarkers were matched to proapolipoprotein A-I (peak Y) and a functionally obscure peptide, SBBI42 (peak X). Western blot analysis confirmed that AF from PE and CHTN had higher proapolipoprotein A-I levels than CTR.

CONCLUSION

Proteomic analysis of AF can distinguish PE from CHTN and CTR. The discriminatory proteins were identified as proapolipoprotein A-I and SBBI42.