Gestational tissue inflammatory biomarkers at term labor: A systematic review of literature

Abstract

Parturition at term is characterized by inflammatory overload in both feto-maternal tissues. Despite the large number of individual studies on changes in inflammatory biomarkers linked to labor, a comprehensive profile of them in each of the uterine compartments is not available to better understand their mechanistic contributions to labor. This systematic review investigated the pro- and anti-inflammatory biomarkers reported in intra-uterine tissues (amnion, chorion, decidua, placenta, and myometrium) at term labor. We conducted a systematic review of studies on pro- and anti-inflammatory biomarkers (mRNA and/or protein) reported in feto-maternal tissues during normal human term labor, published in English (1980-2016), in 3 electronic data bases. From a total of 3712 citations, 172 were included for final review. Each tissue expresses a unique set of biomarkers at the time of term labor, but there is significant overlap between tissues. All tissues had IL-6, IL-8, IL-1β, COX-2, PGE-2, TNF-α, and hCAP18 in common at term labor. Common and unique inflammatory biomarkers are expressed in various feto-maternal compartments at term labor. Increase in pro-inflammatory markers in all gestational tissue signifies their harmonious functional role in promoting labor. Anti-inflammatory markers at term labor are hardly reported.

Keywords: decidua; fetal membranes; inflammation; myometrium; placenta; systematic review.

Figure 1

PRISMA flow diagram of record processing and elimination

Figure 2

The five gestational cell types included in our review are shown as different colored ovals. The numbers listed represent the number of unique biomarker (protein or mRNA) present in the tissue at the time of term labor. The numbers present in overlapping section represent the number of common biomarkers between the two tissues. The central number, 7, is the number of biomarkers present in all tissues at the time of term labor.

Figure 3

Results of quality assessment of included reports. Q1–Q10 correspond to questions 1–10 as listed in table 1. The Y axis is the value assigned for the component question for the study evaluated and the x axis is the number of high, acceptable and low quality studies in each response category.