Lipopolysaccharide promotes contraction of uterine myocytes via activation of Rho/ROCK signaling pathways.
Myometrial contraction is a central feature of labor. Although a link between infection and preterm labor is widely accepted, surprisingly little is known about the mechanisms coupling infection-induced inflammation to myocyte contractile machinery. This study explores the myocyte response to pathogen-derived ligands in vitro. The pregnant human myometrial cell line PHM1-41 and primary cultured uterine myocytes responded to Toll-like receptor (TLR) ligands, including the bacterial wall component LPS, which at 100 ng/ml increased contraction of cells embedded within collagen gels over 72 h compared to PBS. LPS-treated myocytes secreted inflammatory mediators, including prostaglandin F2α, the cytokines TNF-α and IL-6, and a range of chemokines. The contractile response to LPS required TLR4 signaling and was independent of prostaglandin synthesis. Neutralizing TNF-α had no effect on LPS-mediated contraction; however, the Rho-associated protein kinase (ROCK) inhibitors Y-27632 (10 μM) and GSK-269962 (50 nM) both abrogated the contractile response. The finding of LPS-mediated contraction was supported by a 1.38 ± 0.072-fold (mean±SE) increase in myosin light-chain phosphorylation 48 h post-treatment, assessed by in-cell Western blot analysis. Together, these data suggest that, in addition to modulating the local inflammatory environment, pathogen-derived ligands may directly promote myometrial contractility via Rho/ROCK signaling, thus contributing to preterm labor-mediated preterm birth.
1MRC Centre for Reproductive Health, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, UK. jlawrencehutchinson@gmail.com.
James L
JL
Hutchinson
Shalini P
SP
Rajagopal
Mei
M
Yuan
Jane E
JE
Norman
D000577:Amides / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007231:Infant, Newborn; D008070:Lipopolysaccharides / Q000494:pharmacology*; D032342:Muscle Cells / Q000166:cytology* / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects; D010069:Oxadiazoles / Q000494:pharmacology; D011247:Pregnancy; D011725:Pyridines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D014590:Uterine Contraction / Q000187:drug effects*; D014599:Uterus / Q000166:cytology*
D000577:Amides; D007093:Imidazoles; D008070:Lipopolysaccharides; C516969:N-(3-((2-(4-amino-1,2,5-oxadiazol-3-yl)-1-ethyl-1H-imidazo(4,5-c)pyridin-6-yl)oxy)phenyl)-4-((2-(4-morpholinyl)ethyl)oxy)benzamide; D010069:Oxadiazoles; D011725:Pyridines; C108830:Y 27632
infection; labor; myometrium; preterm