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In utero LPS exposure impairs preterm diaphragm contractility

Citation

Song, Y and Karisnan, K and Noble, PB and Berry, CA and Lavin, T and Moss, TJM and Bakker, AJ and Pinniger, GJ and Pillow, JJ, In utero LPS exposure impairs preterm diaphragm contractility, American Journal of Respiratory Cell and Molecular Biology, 49, (5) pp. 866-874. ISSN 1535-4989 (2013) [Refereed Article]


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Copyright Statement

Copyright 2013 by the American Thoracic Society

DOI: doi:10.1165/rcmb.2013-0107OC

Abstract

Preterm birth is associated with inflammation of the fetal membranes (chorioamnionitis). We aimed to establish how chorioamnionitis affects the contractile function and phenotype of the preterm diaphragm. Pregnant ewes received intra-amniotic injections of saline or 10 mg LPS, 2 days or 7 days before delivery at 121 days of gestation (term = 150 d). Diaphragm strips were dissected for the assessment of contractile function after terminal anesthesia. The inflammatory cytokine response, myosin heavy chain (MHC) fibers, proteolytic pathways, and intracellular molecular signaling were analyzed using quantitative PCR, ELISA, immunofluorescence staining, biochemical assays, and Western blotting. Diaphragm peak twitch force and maximal tetanic force were approximately 30% lower than control values in the 2-day and 7-day LPS groups. Activation of the NF-κB pathway, an inflammatory response, and increased proteasome activity were observed in the 2-day LPS group relative to the control or 7-day LPS group. No inflammatory response was evident after a 7-day LPS exposure. Seven-day LPS exposure markedly decreased p70S6K phosphorylation, but no effect on other signaling pathways was evident. The proportion of MHC IIa fibers was lower than that for control samples in the 7-day LPS group. MHC I fiber proportions did not differ between groups. These results demonstrate that intrauterine LPS impairs preterm diaphragmatic contractility after 2-day and 7-day exposures. Diaphragm dysfunction, resulting from 2-day LPS exposure, was associated with a transient activation of proinflammatory signaling, with subsequent increased atrophic gene expression and enhanced proteasome activity. Persistently impaired contractility for the 7-day LPS exposure was associated with the down-regulation of a key component of the protein synthetic signaling pathway and a reduction in the proportions of MHC IIa fibers.

Item Details

Item Type:Refereed Article
Keywords:chorioamnionitis, preterm infant, diaphragm, contractile dysfunction, molecular signaling
Research Division:Medical and Health Sciences
Research Group:Cardiorespiratory Medicine and Haematology
Research Field:Respiratory Diseases
Objective Division:Health
Objective Group:Clinical Health (Organs, Diseases and Abnormal Conditions)
Objective Field:Respiratory System and Diseases (incl. Asthma)
UTAS Author:Song, Y (Dr Yong Song)
ID Code:135708
Year Published:2013
Web of Science® Times Cited:11
Deposited By:Menzies Institute for Medical Research
Deposited On:2019-11-08
Last Modified:2019-12-05
Downloads:2 View Download Statistics

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