Amniotic Fluid Soluble Myeloid Differentiation-2 (sMD-2) as Regulator of Intra-amniotic Inflammation in Infection-induced Preterm Birth

Abstract

Problem TLR4 mediates host responses to pathogens through a mechanism that involves protein myeloid differentiation-2 (MD-2) and its soluble form sMD-2. The role of sMD2 in intra-amniotic inflammation induced preterm birth has not been previously explored. Method of study Human amniotic fluid (AF) sMD-2 was studied by Western blotting in 152 AF samples of patients who had an amniocentesis to rule-out infection (yes infection, n=50; no infection, n=50) or women with normal pregnancy outcome (2nd trimester genetic karyotyping, n=26; 3rd trimester lung maturity testing, n=26). Histologic localization and mRNA expression of MD2 in fetal membranes were studied by immunohistochemistry and RT-PCR. The ability of fetal membrane to release sMD-2 and inflammatory cytokines was studied in-vitro. Results Human AF contains three sMD-2 proteoforms whose levels of expression were lower at term. Intra-amniotic infection up-regulated sMD-2. MD-2 mRNA and immunohistochemistry findings concurred. In vitro, LPS and monensin increased while cycloheximide decreased sMD-2 production. Recombinant sMD-2 modulated TNF-α and IL-6 levels in a dose and time-dependent fashion. Conclusion sMD2 proteoforms are constitutively present in human AF. The intensity of the intra-amniotic inflammatory response to bacteria or perhaps to other TLR4 ligands may be facilitated through synthesis and release of sMD2 by the amniochorion.

Mass spectrometry for the discovery of biomarkers of sepsis

“…This field has primarily been pioneered over the last decade through work performed by Buhimschi et al 107, 119–122 . They have examined amniotic fluid and cord blood from infants that were born prematurely to detect biomarkers of inflammation, infection, and neonatal sepsis.…”

Integrated microRNA and mRNA network analysis of the human myometrial transcriptome in the transition from quiescence to labor†,‡

“…Myometrial biopsy samples were collected from 20 women with singleton gestations undergoing primary Cesarean deliveries in four settings which defined their clinical phenotype as either: (1) spontaneous onset of TL (n = 5, gestational age [GA] median [range]: 39 [38][39][40] weeks), (2) term nonlabor (TNL, n = 5, GA: 39 weeks), (3) spontaneous onset of PTB in the context of histologic chorioamnionitis (PTB-HCA, GA; n = 5, 29 [27][28][29][30][31]; (4) providerinitiated PTB in the absence of labor (PTB-NL, n = 5, GA: 2 [25][26][27][28][29][30][31][32] weeks). An additional set of seven term women (TNL, n = 4; and TL, n = 3) provided tissues solely for immunohistochemistry (IHC) validation, while an additional set of 25 term and preterm women provided tissues solely for quantitative PCR (qPCR) validation (as indicated in text and figure legends).…”

Tenascin-X in amniotic fluid and reproductive tissues of pregnancies complicated by infection and preterm prelabor rupture of membranes†

“…N-linked de-glycosylation was carried out using N-glycosidase F, α-2-3,6,8,9-neuraminidase, and endo-α-N-acetyl-galactosaminidase as previously described [32]. This was done under reducing conditions with β-mercaptoethanol according to the manufacturer's instructions (Calbiochem-EMD Chemicals Inc., Gibbstown, NJ).…”