135708 - In utero LPS exposure impairs preterm diaphragm contractility.pdf (1.13 MB)
In utero LPS exposure impairs preterm diaphragm contractility
journal contribution
posted on 2023-05-20, 08:14 authored by Yong SongYong Song, Karisnan, K, Noble, PB, Berry, CA, Lavin, T, Moss, TJM, Bakker, AJ, Pinniger, GJ, Pillow, JJPreterm 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.
History
Publication title
American Journal of Respiratory Cell and Molecular BiologyVolume
49Issue
5Pagination
866-874ISSN
1535-4989Department/School
Menzies Institute for Medical ResearchPublisher
American Thoracic SocietyPlace of publication
United StatesRights statement
Copyright 2013 by the American Thoracic SocietyRepository Status
- Open