Oxygen toxicity and oxidant stress in the developing lung

Developmental regulation of antioxidant enzymes and their impact on neonatal lung disease

SIGNIFICANCE

Deficient antioxidant defenses and compromised ability to respond to oxidative stress burden the immature lung. Routine neonatal therapies can cause increased oxidative stress with subsequent injury to the premature lung. Novel therapeutic approaches to protect the premature lung are greatly needed.

RECENT ADVANCES

Live cell imaging with targeted redox probes allows for the measurement of subcellular oxidative stress and for comparisons of oxidative stress across development. Comprehension of subcellular and cell-type-specific responses to oxidative stress may influence the targeting of future antioxidant therapies.

CRITICAL ISSUES

Challenges remain in identifying the optimal cellular targets, degree of enzyme activity, and appropriate antioxidant therapy. Further, the efficacy of delivering exogenous antioxidants to specific cell types or subcellular compartments remains under investigation. Treatment with a nonselective antioxidant could unintentionally compromise cellular function or impact cellular defense mechanisms and homeostasis.

FUTURE DIRECTIONS

Genetic and/or biomarker screening may identify infants at the greatest risk for oxidative lung injury and guide the use of more selective antioxidant therapies. Novel approaches to the delivery of antioxidant enzymes may allow cell type- or cellular organelle-specific therapy. Improved comprehension of the antioxidant enzyme regulation across cell type, cell compartment, gender, and developmental stage is critical to the design and optimization of therapy.

Protecting TPN and lipid infusions from light: reducing hydroperoxides in NICU patients

The use of total parenteral nutrition (TPN) and intravenous fat emulsions in sick or preterm infants is often required to maintain adequate nutrition, yet recent research has shown that when exposed to light these nutrients are altered and deliver a high load of exogenous toxic hydroperoxides to already compromised infants. Hydroperoxides cause damage at the cellular level unless mediated by the body's antioxidant systems. NICU patients are, by definition, patients at risk. Preterm infants have low antioxidant reserves and, like sick term infants, typically suffer significant oxidative stress. Endogenous hydroperoxides alone may overwhelm defenses. The addition of hyperperoxides from light-exposed TPN or fat emulsions increases the risk of tissue damage. Hydroperoxides have been associated with hypoxic-ischemic encephalopathy, intraventricular hemorrhage, periventricular leukomalacia, chronic lung disease, retinopathy of prematurity, and necrotizing enterocolitis. By protecting these infusates from light, bedside nurses can reduce the amount of hydroperoxides infused and protect NICU patients from the associated risks.