Investigating the molecular structure of placenta and plasma in pre-eclampsia by infrared microspectroscopy

Abstract Pre-eclampsia (PE) is a serious hypertensive disorder with unclear etiology and lack of reliable diagnostic tests. In this study, IR microspectroscopy was applied to identify molecular changes associated with the pathogenesis of PE in placental tissues and plasma samples from pre-eclamptic women and normotensive matched controls. The obtained spectra were analyzed by multivariate analysis in the spectral ranges of 3050–2800 cm−1 and 1855–1485 cm−1 corresponding to lipid and protein-carbonyl components, respectively. In the lipid region, an increase in CH2/CH3 ratio was noticed and higher level of unsaturation index in placenta was evident. New lipid species emerged as a consequence of oxidative stress. The more intense peak at 1740 cm−1 in PE reflected higher level of LDL and VLDL. In the protein region, a decrease in the α-helix structure associated with gain in β-sheet and β-turn structures was detected. Our results revealed significant conformational changes in the protein secondary structure in PE illustrated by peak shifts and intensity alterations, particularly in amide I component. Variations in lipid order, membrane integrity, fatty acid saturation and plasma lipid profile were also detected in PE. The ROC curve generated from plasma samples yielded AUC values of 98.4% and 99.9% for lipid and protein-carbonyl regions, respectively. The current study shed light on the promising role of IR microspectroscopy as a new analytical tool that can aid in providing better diagnosis and understanding of the pathophysiology of PE.