Increased Expression of Neprilysin Is Associated with Inflammation in Preeclampsia

Preeclampsia (PE) is associated with a finely tuned equilibrium between trophoblast cell invasion and fetal-maternal immunological tolerance. An imbalance between proinflammatory (IL-6) and anti-inflammatory (IL-10) cytokines is a hallmark of PE. Neprilysin (NEP), a membrane-bound metalloprotease, is vulnerable to the inflammatory environment and plays a significant role in modulating vascular tone. The aim of this study was to determine the correlation between NEP (mRNA and protein) levels and the inflammatory status in PE patients compared to healthy pregnant women and to identify the role of NEP in evaluating the severity of preeclampsia. The study group comprised 52 pregnant women with PE while the control group comprised 47 normotensive pregnant women. After a caesarean section, placental tissue samples from patients and controls were collected to measure the expression levels of IL-6, TGF-β, IL-10, and NEP mRNA. In addition, an enzyme-linked immunosorbent assay was used to assess the quantity of NEP protein in blood samples. Our results revealed a significant positive correlation between NEP (mRNA and protein) and proinflammatory markers IL-6 and TGF-β levels in patients compared to controls and a significant inverse correlation between NEP and anti-inflammatory cytokine IL-10. Moreover, this is the first study to find a strong positive correlation between NEP level and PE severity. In conclusion, in PE patients, there is a substantial relationship between NEP, the degree of inflammation, and PE severity. NEP could act as a potential biomarker for diagnosis and prognosis of PE.