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Stojanovska V, Atta J, Kelly SB, Zahra VA, Matthews-Staindl E, Nitsos I, Moxham A, Pham Y, Hooper SB, Herlenius E, Galinsky R, Polglase GR. Increased Prostaglandin E2 in Brainstem Respiratory Centers Is Associated With Inhibition of Breathing Movements in Fetal Sheep Exposed to Progressive Systemic Inflammation. Front Physiol 2022; 13:841229. [PMID: 35309054 PMCID: PMC8928579 DOI: 10.3389/fphys.2022.841229] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/08/2022] [Indexed: 12/11/2022] Open
Abstract
Background Preterm newborns commonly experience apnoeas after birth and require respiratory stimulants and support. Antenatal inflammation is a common antecedent of preterm birth and inflammatory mediators, particularly prostaglandin E2 (PGE2), are associated with inhibition of vital brainstem respiratory centers. In this study, we tested the hypothesis that exposure to antenatal inflammation inhibits fetal breathing movements (FBMs) and increases inflammation and PGE2 levels in brainstem respiratory centers, cerebrospinal fluid (CSF) and blood plasma. Methods Chronically instrumented late preterm fetal sheep at 0.85 of gestation were randomly assigned to receive repeated intravenous saline (n = 8) or lipopolysaccharide (LPS) infusions (experimental day 1 = 300 ng, day 2 = 600 ng, day 3 = 1200 ng, n = 8). Fetal breathing movements were recorded throughout the experimental period. Sheep were euthanized 4 days after starting infusions for assessment of brainstem respiratory center histology. Results LPS infusions increased circulating and cerebrospinal fluid PGE2 levels, decreased arterial oxygen saturation, increased the partial pressure of carbon dioxide and lactate concentration, and decreased pH (p < 0.05 for all) compared to controls. LPS infusions caused transient reductions in the % of time fetuses spent breathing and the proportion of vigorous fetal breathing movements (P < 0.05 vs. control). LPS-exposure increased PGE2 expression in the RTN/pFRG (P < 0.05 vs. control) but not the pBÖTC (P < 0.07 vs. control) of the brainstem. No significant changes in gene expression were observed for PGE2 enzymes or caspase 3. LPS-exposure reduced the numbers of GFAP-immunoreactive astrocytes in the RTN/pFRG, NTS and XII of the brainstem (P < 0.05 vs. control for all) and increased microglial activation in the RTN/pFRG, preBÖTC, NTS, and XII brainstem respiratory centers (P < 0.05 vs. control for all). Conclusion Chronic LPS-exposure in late preterm fetal sheep increased PGE2 levels within the brainstem, CSF and plasma, and was associated with inhibition of FBMs, astrocyte loss and microglial activation within the brainstem respiratory centers. Further studies are needed to determine whether the inflammation-induced increase in PGE2 levels plays a key role in depressing respiratory drive in the perinatal period.
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Affiliation(s)
- Vanesa Stojanovska
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - John Atta
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Sharmony B. Kelly
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Valerie A. Zahra
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Eva Matthews-Staindl
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Ilias Nitsos
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Alison Moxham
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Yen Pham
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
| | - Stuart B. Hooper
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
| | - Eric Herlenius
- Department of Women’s and Children’s Health, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
- Astrid Lindgren Childrens Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Robert Galinsky
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
- *Correspondence: Robert Galinsky,
| | - Graeme R. Polglase
- The Ritchie Center, Hudson Institute of Medical Research, Melbourne, VIC, Australia
- Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, Australia
- Graeme R. Polglase,
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Kalhoff H. Mild dehydration: a risk factor of broncho-pulmonary disorders? Eur J Clin Nutr 2005; 57 Suppl 2:S81-7. [PMID: 14681718 DOI: 10.1038/sj.ejcn.1601906] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Several expert committees recommend a high fluid intake in patients with chronic bronchitis and asthma. Is there a relationship between fluid intake or hydration status and broncho-pulmonary disorders like bronchitis and asthma? First, basic physiologic mechanisms like regulation of lung fluid balance and water transport at pulmonary surfaces were analyzed, in order to characterize the role of local hydration status in lung and airways. Second, making use of the computer-based literature searches (PubMed), evidence for a role of hydration status in complex physiological and pathophysiological conditions of lungs and airways like perinatal lung adaptation (PLA) (in prematures), mucociliary clearance(MC) and asthma was categorized. The movement of fluid between the airspaces, interstitium, and vascular compartments in the lungs plays an important physiological role in the maintenance of hydration and protection of the lung epithelium and significantly contributes to a proper airway clearance. PLA is characterized by a rapid change from fluid secretion to fluid absorption in the distal respiratory tract, with the literature data confirming a critical role of the epithelial sodium channel. Only few studies have investigated the effect of different fluid input regimens on PLA in prematures. MC relies on the interaction between epithelial water fluxes, mucus secretions, and ciliary activity. Whereas animal data show that drying of the airway epithelium decreases MC, few clinical studies investigating the effect of local or systemic hydration on MC have led to ambiguous results. Asthma (A) is characterized by chronic airway inflammation and episodic airway obstruction. Data in animals and humans indicate an association between exercise-induced-A and conditioning (humidity and heat exchange) of inspired air. However, epidemiological studies (children and adults), investigating the role of fluid (and salt) input in the etiology of the disease as well as studies analyzing different markers of hydration status during asthmatic attacks have so far led to conflicting results. Some expert groups recommend sufficient hydration as a complementary A-therapy. Analysis of basic physiological mechanisms in lungs and airways clearly demonstrates a critical role for water transport and local hydration status. In broncho-pulmonary diseases, however, analysis of the complex pathophysiological mechanisms is difficult. Thus, we still need more studies to confirm or refute mild dehydration or hypohydration as a risk factor of broncho-pulmonary disorders.
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Affiliation(s)
- H Kalhoff
- Pediatric Clinic, Dortmund, Germany.
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Mitchell BF, Olson DM. Prostaglandin endoperoxide H synthase inhibitors and other tocolytics in preterm labour. Prostaglandins Leukot Essent Fatty Acids 2004; 70:167-87. [PMID: 14683691 DOI: 10.1016/j.plefa.2003.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Preterm delivery (<37 weeks of gestation) is the major obstetrical complication in developed countries, yet attempts to delay labour and prolong pregnancy have largely been unsuccessful. One of the many reasons it is so difficult to prevent preterm birth is that the nature of preterm labour changes as a function of gestational age, maternal lifestyle factors or infection, to list a few of the reasons. The inhibitors of prostaglandin endoperoxide H synthase (PGHS), known as the Non-steroidal Antiinflammatory Drugs, have been viewed with interest as tocolytics with promising effectiveness under most conditions of preterm labour. Three isoforms of PGHS exist; the first two, PGHS-1 and -2, have been studied for their catalytic activity, X-ray crystallographic structure, and physiological roles in the adult and the foetus. Mixed inhibitors and isoform-specific inhibitors of PGHS have been developed, and their roles in delaying preterm labour are examined and compared to other tocolytics.
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Affiliation(s)
- Bryan F Mitchell
- Department of Obstetrics and Gynaecology, Perinatal Research Centre, CIHR Group in Perinatal Health and Disease, University of Alberta, 220 HMRC, Edmonton, Alberta, Canada T6G2S2
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