Characterization of the myometrial transcriptome and biological pathways of spontaneous human labor at term

Abstract

Aims: To characterize the transcriptome of human myometrium during spontaneous labor at term. Methods: Myometrium was obtained from women with (ns19) and without labor (ns20). Illumina ᭨ HumanHT-12 microarrays were utilized. Moderated t-tests and false discovery rate adjustment of P-values were applied. Real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for a select set of differentially expressed genes in a separate set of samples. Enzyme-linked immunosorbent assay and Western blot were utilized to confirm differential protein production in a third sample set. Results: 1) Four hundred and seventy-one genes were differentially expressed; 2) gene ontology analysis indicated enrichment of 103 biological processes and 18 molecular functions including: a) inflammatory response; b) cytokine activity; and c) chemokine activity; 3) systems biology pathway analysis using signaling pathway impact analysis indicated six significant pathways: a) cytokine-cytokine receptor interaction; b) Jak-STAT signaling; and c) complement and coagulation cascades; d) NOD-like receptor signaling pathway; e) systemic lupus erythematosus; and f) chemokine signaling pathway; 4) qRT-PCR confirmed over-expression of prostaglandin-endoperoxide synthase-2, heparin binding epidermal growth factor (EGF)-like growth factor, chemokine C-C motif ligand 2 (CCL2/MCP1), leukocyte immunoglobulin-like receptor, subfamily A member 5, interleukin (IL)-8, IL-6, chemokine C-X-C motif ligand 6 (CXCL6/GCP2), nuclear factor of kappa light chain gene enhancer in B-cells inhibitor zeta, suppressor of cytokine signaling 3 (SOCS3) and decreased expression of FK506 binding-protein 5 and aldehyde dehydrogenase in labor; 5) IL-6, CXCL6, CCL2 and SOCS3 protein expression was significantly higher in the term labor group compared to the term not in labor group. Conclusions: Myometrium of women in spontaneous labor at term is characterized by a stereotypic gene expression pattern consistent with over-expression of the inflammatory response and leukocyte chemotaxis. Differential gene expression identified with microarray was confirmed with qRT-PCR using an independent set of samples. This study represents an unbiased description of the biological processes involved in spontaneous labor at term based on transcriptomics.

Stretch-induced human myometrial cytokines enhance immune cell recruitment via endothelial activation

“…14,37,38 Recent reports of transcriptome data in spontaneous human labouring myometrial samples identified IL-6, CXCL1 and CXCL8 as highly expressed genes, with CXCL8 exhibiting the highest fold change in TL compared to term not-in-labour samples. 3,37 In line with our observations, Hua et al 31 showed that mechanical stretch augmented the expression of various chemokines in primary human myometrial myocytes including CCL2, CXCL8 and CXCL1. Interestingly, growth factors can also act as chemoattractants and are involved in ECM remodeling and cytokine release.…”

Myometrial cytokines and their role in the onset of labour

“…IL-8 is a potent chemokine for neutrophils; and its mRNA expression is increased in myometrium of women in PTL and TL (Keelan et al 2003). Indeed, a recent myometrial transcriptome study reported that IL-6, CXCL1 and IL-8 exhibited the greatest increase in labouring samples (Mittal et al 2010). A more detailed study revealed that IL-8 levels increased in parallel with cervical dilation (Hebisch et al 2001).…”

Clinical chorioamnionitis at term: the amniotic fluid fatty acyl lipidome

“…Spontaneous parturition at term is characterized by increased expression of PUFAs metabolizing enzymes such as COX-2 (65, 66), elevated cytokine expression (44,45,48,49,67), and leukocyte chemotaxis (44) and is generally considered a physiological inflammatory response. Recent unbiased, myometrial transcriptomic analysis further confirmed the overexpression of inflammatory genes in TLB (68,69). Despite the heightened inflammatory molecular signatures during spontaneous parturition at term, return to homeostasis is normally uneventful, except in clinical chorioamnionitis.…”