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Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats
Published on: November 20, 2015
In utero LPS exposure impairs preterm diaphragm contractility
Yong Song1, Kanakeswary Karisnan, Peter B Noble
11 School of Anatomy, Physiology, and Human Biology, and.
Summary
Intrauterine inflammation from LPS exposure impairs preterm lamb diaphragm function. This dysfunction involves inflammatory signaling, proteasome activity, and altered myosin heavy chain fibers, impacting respiratory muscle development.
Area of Science:
- Perinatal Medicine
- Respiratory Physiology
- Developmental Biology
Background:
- Preterm birth is frequently linked to chorioamnionitis, an inflammation of fetal membranes.
- The diaphragm's contractile function and cellular phenotype in preterm neonates are not fully understood in the context of intrauterine inflammation.
Purpose of the Study:
- To investigate the impact of intrauterine lipopolysaccharide (LPS) exposure on preterm lamb diaphragm contractile function and phenotype.
- To elucidate the molecular mechanisms underlying diaphragm dysfunction following chorioamnionitis.
Main Methods:
- Pregnant ewes were exposed to intra-amniotic LPS or saline at two time points before preterm delivery.
- Diaphragm contractile function was assessed, alongside analysis of inflammatory cytokines, myosin heavy chain (MHC) fiber types, proteolytic pathways, and intracellular signaling.
- Quantitative PCR, ELISA, immunofluorescence, biochemical assays, and Western blotting were employed.
Main Results:
- LPS exposure significantly reduced diaphragm peak twitch and maximal tetanic forces at both 2 and 7 days.
- Diaphragm dysfunction after 2-day LPS exposure was linked to transient NF-κB activation, inflammation, and increased proteasome activity.
- Seven-day LPS exposure resulted in persistent contractile impairment, associated with decreased p70S6K phosphorylation and reduced MHC IIa fiber proportion.
Conclusions:
- Intrauterine LPS exposure impairs preterm diaphragmatic contractility, with distinct molecular profiles depending on exposure duration.
- Early LPS exposure triggers transient inflammation and proteasome-mediated atrophy, while later exposure leads to persistent dysfunction via suppressed protein synthesis signaling and altered fiber type.
