Is there an inflammatory stimulus to human term labour?

Area of Science:

• Reproductive biology
• Immunology
• Obstetrics

Background:

• Inflammation is implicated in term and preterm labor onset.
• Recent findings suggest myometrial inflammation is a consequence, not a cause, of term labor.
• The role of other reproductive tissues in labor initiation requires investigation.

Purpose of the Study:

• To investigate the role of amnion, choriodecidua parietalis, and decidua basalis in labor-induced inflammation.
• To determine inflammatory cytokine profiles and pro-labor gene expression in these tissues during pregnancy and labor.
• To identify the primary site of inflammatory stimulus for term labor.

Main Methods:

• Collection of amnion, choriodecidua parietalis, and decidua basalis samples from women at various pregnancy stages and during spontaneous labor.
• Quantification of inflammatory cytokine profiles using Bio-Plex Pro® cytokine multiplex assays and quantitative RT-PCR.
• Analysis of pro-labor gene expression (PGHS-2, PGDH, OTR, CX43) and oxytocin (OT) mRNA levels via quantitative RT-PCR.

Main Results:

• Cytokine mRNA levels decreased from preterm to term non-labor, but protein levels remained unchanged in amnion and choriodecidua parietalis.
• Increased IL-1β and IL-6 protein levels were observed in choriodecidua parietalis during term early labor.
• Cytokine protein levels rose in amnion and decidua basalis during term established labor, with elevated levels in choriodecidua parietalis during early and established labor.

Conclusions:

• The choriodecidua parietalis may be the primary site of the inflammatory stimulus initiating term labor.
• Despite inflammatory changes, pro-labor gene expression in the myometrium did not change, suggesting indirect cytokine action.
• Further research is needed to elucidate the signaling pathways linking choriodecidual inflammation to myometrial activation.