A Broad-Spectrum Chemokine Inhibitor Blocks Inflammation-Induced Myometrial Myocyte-Macrophage Crosstalk and Myometrial Contraction.

Adam Boros-Rausch,Stephen James Lye,Oksana Shynlova

doi:10.3390/cells11010128

Abstract

Prophylactic administration of the broad-spectrum chemokine inhibitor (BSCI) FX125L has been shown to suppress uterine contraction, prevent preterm birth (PTB) induced by Group B Streptococcus in nonhuman primates, and inhibit uterine cytokine/chemokine expression in a murine model of bacterial endotoxin (LPS)-induced PTB. This study aimed to determine the mechanism(s) of BSCI action on human myometrial smooth muscle cells. We hypothesized that BSCI prevents infection-induced contraction of uterine myocytes by inhibiting the secretion of pro-inflammatory cytokines, the expression of contraction-associated proteins and disruption of myocyte interaction with tissue macrophages. Myometrial biopsies and peripheral blood were collected from women at term (not in labour) undergoing an elective caesarean section. Myocytes were isolated and treated with LPS with/out BSCI; conditioned media was collected; cytokine secretion was analyzed by ELISA; and protein expression was detected by immunoblotting and immunocytochemistry. Functional gap junction formation was assessed by parachute assay. Collagen lattices were used to examine myocyte contraction with/out blood-derived macrophages and BSCI. We found that BSCI inhibited (1) LPS-induced activation of transcription factor NF-kB; (2) secretion of chemokines (MCP-1/CCL2 and IL-8/CXCL8); (3) Connexin43-mediated intercellular connectivity, thereby preventing myocyte–macrophage crosstalk; and (4) myocyte contraction. BSCI represents novel therapeutics for prevention of inflammation-induced PTB in women.

Highlights

Preterm birth (PTB) is defined as the delivery of a baby before 37 completed weeks of gestation and affects almost 10% of all pregnancies [1]
We recently reported that human myocytes isolated from myometrial tissue of term labouring women secrete higher levels of three cytokines (IL-8, MCP-1, and IL-6) in vitro as compared to myocytes isolated from term not in labour (TNL) myometrial samples [26]
We have shown that the broad-spectrum chemokine inhibitor (BSCI) decreases in vivo infection-induced uterine inflammation by inhibiting chemokine-mediated monocyte and neutrophil infiltration into the myometrium [40], while in vitro, it prevents trans-endothelial migration of human leukocytes towards media conditioned by labouring myometrial cells [26]

Summary

Introduction

Preterm birth (PTB) is defined as the delivery of a baby before 37 completed weeks of gestation and affects almost 10% of all pregnancies [1]. PTB is the major cause of death for neonates in high and low-income countries [1]. Depending on the study population, about half of spontaneous-onset (s)PTB is attributed to intrauterine infective processes with preterm premature rupture of membranes (pPROM) and half are of unknown etiology [2–4]. Intrauterine or systemic maternal infections that cause sPTBs can damage the fetus, leading to brain and lung injury [5–7]. Chorioamnionitis, local inflammation detected in the amniotic fluid, placenta, and fetal membranes/decidua, results in increased infiltration of maternal immune cells into the placenta and/or fetal membranes [8]. Uterine infection causing PTB could originate from ascending bacteria, Gram-negative bacteria such as Escherichia coli (E. coli), as well as Gram-positive bacteria Group B Streptococcus agalactiae (GBS) [6,9,10]

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