Accumulating evidence has shown that preeclampsia (PE) was associated with an aberrant maternal-fetal inflammatory response. In the present study, we first found that in human PE placentas levels of toll-like receptor 4 (TLR4), phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) and inflammatory cytokines IL-6 and MCP-1 were significantly upregulated. Next, we demonstrated a notable increase in systolic blood pressure (SBP) and proteinuria in lipopolysaccharide (LPS)-treated pregnant rats and concomitant high levels of TLR4 and p-p38 in these PE-like rat placentas, which led to aberrant overexpression of both IL-6 and MCP-1, as well as deficient trophoblast invasion and spiral artery (SA) remodeling, and these abnormalities were ameliorated by SB203580, a reported inhibitor of p38. In vitro we further confirmed that LPS triggered the activation of TLR4/p38 signaling pathway, which promoted trophoblast apoptosis and damaged trophoblastic invasion via downstream effectors IL-6 and MCP-1; these mutations were rectified by silencing this signaling pathway. These findings elaborated potential mechanisms that aberrant TLR4/p38 signaling might contribute to PE and LPS-induced PE-like symptom by damaging trophoblast invasion and SA remodeling via activating inflammatory cytokines including IL-6 and MCP-1.
Keywords: inflammation; lipopolysaccharide; p38 MAPK; preeclampsia; spiral artery; toll-like receptor 4.