TLR4 regulation in human fetal membranes as an explicative mechanism of a pathological preterm case.

Abstract

The integrity of human fetal membranes is crucial for harmonious fetal development throughout pregnancy. Their premature rupture is often the consequence of a physiological phenomenon previously exacerbated. Beyond all biological processes implied, inflammation is of primary importance and is qualified as "sterile" at the end of pregnancy. Complementary methylomic and transcriptomic strategies on amnion and choriodecidua explants taken from the altered (cervix zone) and intact fetal membranes at term and before labor were used in this study. By cross-analyzing genome-wide studies strengthened by in vitro experiments, we deciphered how the expression of Toll-like receptor 4 (TLR4), a well-known actor of pathological fetal membrane rupture, is controlled. Indeed, it is differentially regulated in the altered zone and between both layers by a dual mechanism: 1) the methylation of TLR4 and miRNA promoters and 2) targeting by miRNA (let-7a-2 and miR-125b-1) acting on the 3-UTR of TLR4. Consequently, this study demonstrates that a fine regulation of TLR4 is required for sterile inflammation establishment at the end of pregnancy and that it may be dysregulated in the pathological premature rupture of membranes.