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Caffeine ameliorates hyperoxia-induced lung injury by protecting GCH1 function in neonatal rat pups
Xigang Jing1, Yi-Wen Huang2, Jason Jarzembowski3
1Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin.
Insights
Early caffeine treatment protects premature infants from bronchopulmonary dysplasia by enhancing lung repair mechanisms. Caffeine improves blood vessel formation and lung structure in hyperoxia-exposed rat pups, reducing BPD incidence.
Area of Science:
- Neonatal physiology
- Pulmonary medicine
- Pharmacology
Background:
- Bronchopulmonary dysplasia (BPD) is a significant cause of illness in premature infants.
- Impaired blood vessel formation (angiogenesis) is a key factor in BPD development.
- The protective mechanism of early caffeine administration against BPD is not fully understood.
Purpose of the Study:
- To investigate the protective effects of early caffeine treatment on lung development in a hyperoxia-induced BPD rat model.
- To elucidate the molecular mechanisms underlying caffeine's protective role, focusing on nitric oxide synthase (eNOS) and tetrahydrobiopterin (BH4) pathways.
Main Methods:
- Sprague-Dawley rat pups were exposed to hyperoxia from birth and treated daily with caffeine (20 mg/kg) or saline.
- Lung tissues were analyzed at postnatal days 10 and 21.
- Levels of cyclic AMP (cAMP), BH4, phosphorylated eNOS, and GTP cyclohydrolase 1 (GCH1) were measured.
Main Results:
- Hyperoxia impaired pup growth and lung development, reducing cAMP and BH4 levels.
- Caffeine treatment increased lung cAMP, phosphorylated eNOS, GCH1, and BH4 levels in hyperoxia-exposed pups.
- Caffeine improved alveolar structure and angiogenesis in hyperoxia-exposed lungs.
- Reduced GCH1 in hyperoxia was partly due to increased proteasome degradation.
Conclusions:
- Early caffeine administration protects against hyperoxia-induced lung injury in developing rats.
- Caffeine enhances eNOS activity by increasing BH4 bioavailability, thereby improving angiogenesis and lung structure.
- This study provides a molecular basis for using caffeine to prevent BPD in premature infants.
Abstract:
BackgroundBronchopulmonary dysplasia (BPD) is a major morbidity in premature infants, and impaired angiogenesis is considered a major contributor to BPD. Early caffeine treatment decreases the incidence of BPD; the mechanism remains incompletely understood.MethodsSprague-Dawley rat pups exposed to normoxia or hyperoxia since birth were treated daily with either 20 mg/kg caffeine or normal saline by an intraperitoneal injection from day 2 of life. The lungs were obtained for studies at days 10 and 21.ResultsHyperoxia impaired somatic growth and lung growth in the rat pups. The impaired lung growth during hyperoxia was associated with decreased levels of cyclic AMP (cAMP) and tetrahydrobiopterin (BH4) in the lungs. Early caffeine treatment increased cAMP levels in the lungs of hyperoxia-exposed pups. Caffeine also increased the levels of phosphorylated endothelial nitric oxide synthase (eNOS) at serine1177, total and serine51 phosphorylated GTP cyclohydrolase 1 (GCH1), and BH4 levels, with improved alveolar structure and angiogenesis in hyperoxia-exposed lungs. Reduced GCH1 levels in hyperoxia were due, in part, to increased degradation by the ubiquitin-proteasome system.ConclusionOur data support the notion that early caffeine treatment can protect immature lungs from hyperoxia-induced damage by improving eNOS activity through increased BH4 bioavailability.