Liposome-entrapped antioxidant enzymes prevent lethal O2 toxicity in the newborn rat

Area of Science:

• Biomedical Science
• Toxicology
• Biochemistry

Background:

• Hyperoxia, or exposure to high oxygen concentrations, poses a significant threat to newborn survival.
• Oxidative stress induced by hyperoxia is a primary mechanism of lung injury in neonates.
• Antioxidant enzymes like superoxide dismutase and catalase play crucial roles in mitigating oxidative damage.

Purpose of the Study:

• To investigate the protective effects of liposome-encapsulated antioxidant enzymes against hyperoxia-induced mortality in newborn rats.
• To determine the contribution of both the liposome vehicle and the antioxidant enzymes to the observed protective effect.

Main Methods:

• Newborn rat pups were exposed to hyperoxia (>95% O2).
• Daily intraperitoneal injections were administered, including buffered saline, control liposomes, and liposomes containing superoxide dismutase and catalase.
• Survival rates were monitored and compared between treatment groups.

Main Results:

• Hyperoxia exposure resulted in a lethal time for 50% of the population (LT50) of 13 days.
• Liposome-encapsulated superoxide dismutase and catalase significantly increased survival rates to 95 +/- 4% compared to saline controls (40 +/- 7%).
• Control liposomes without enzymes also provided a partial protective effect (71 +/- 7%), indicating a contribution from the lipid vehicle. The protective effect of the enzymes was dependent on their activity, as inactive catalase failed to confer protection.

Conclusions:

• Liposome-encapsulated antioxidant enzymes, specifically superoxide dismutase and catalase, offer significant protection against hyperoxia-induced mortality in newborn rats.
• Both the liposome delivery system and the antioxidant enzymes contribute to the overall protective effect against oxidative stress.
• This approach holds potential for therapeutic interventions in conditions involving hyperoxia exposure.