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Mitochondrial DNA damage analysis in bronchoalveolar lavage cells of preterm infants
Bea Zoer1, Jasper Valentijn Been, Eveline Jongen
1Department of Pediatrics Maastricht University Medical Center, GROW School for Oncology and Developmental Biology, 6202 AZ Maastricht, The Netherlands.
Abstract:
In mechanically ventilated preterm infants, the combination of immaturity, volutrauma, oxidative stress, and inflammatory processes can lead to chronic lung injury. Mitochondrial DNA (mtDNA) is more susceptible to oxidative damage than nuclear DNA. We aimed to investigate the level of mtDNA damage (deletions, mutations and changes in copy number) in bronchoalveolar lavage (BAL) cells from 10 preterm infants (27-30 weeks). A first BAL (BAL1) was done within 24 h of endotracheal intubation and BAL2 was performed 30-103 h thereafter. Deletions were analyzed by long range PCR, point mutations by heteroduplex analysis of the D-loop region, and copy number changes by real-time PCR. Using these methods, no deletions were found in any of the BAL samples. When BAL1 and BAL2 samples were compared no new mutations were found. In contrast, a marked decrease in mtDNA copy number was observed in 5 patients. In conclusion, we found that exposure of preterm infants to short term mechanical ventilation did not lead to detrimental consequences for the mtDNA in the form of mutations or deletions.
Insights
Short-term mechanical ventilation in preterm infants did not cause mitochondrial DNA (mtDNA) mutations or deletions. However, a significant decrease in mtDNA copy number was observed in some infants, suggesting potential early cellular stress.
Area of Science:
- Neonatal Medicine
- Mitochondrial Biology
- Respiratory Physiology
Background:
- Mechanically ventilated preterm infants face risks of chronic lung injury due to immaturity, volutrauma, oxidative stress, and inflammation.
- Mitochondrial DNA (mtDNA) is particularly vulnerable to oxidative damage compared to nuclear DNA.
- Understanding mtDNA integrity is crucial for assessing lung injury in vulnerable neonates.
Purpose of the Study:
- To investigate the levels of mtDNA damage, including deletions, mutations, and copy number changes, in bronchoalveolar lavage (BAL) cells of preterm infants.
- To assess the impact of short-term mechanical ventilation on mtDNA integrity in this population.
Main Methods:
- Bronchoalveolar lavage (BAL) samples were collected from 10 preterm infants (27-30 weeks gestation) at two time points: within 24 hours of intubation (BAL1) and 30-103 hours later (BAL2).
- mtDNA deletions were analyzed using long-range PCR.
- Point mutations in the D-loop region were assessed via heteroduplex analysis.
- mtDNA copy number was quantified using real-time PCR.
Main Results:
- No mtDNA deletions were detected in any of the BAL samples.
- No new mtDNA point mutations were identified when comparing BAL1 and BAL2 samples.
- A significant decrease in mtDNA copy number was observed in 5 out of 10 infants between the two sampling points.
Conclusions:
- Short-term mechanical ventilation in preterm infants does not appear to induce mtDNA mutations or deletions.
- The observed decrease in mtDNA copy number suggests potential early cellular stress or mitochondrial dysfunction.
- Further research is needed to elucidate the clinical significance of reduced mtDNA copy number in ventilated preterm infants.