Cytidine 5′-diphosphocholine ameliorates hyperoxic lung injury in a neonatal rat model

Articles nature publishing group Translational Investigation Cytidine 5′-diphosphocholine ameliorates hyperoxic lung injury in a neonatal rat model Merih Cetinkaya1, Mehmet Cansev2, Ilker M. Kafa3, Cuneyt Tayman1, Ferhat Cekmez1, Fuat Emre Canpolat1, Turan Tunc1 and S. Umit Sarici1 Background: Bronchopulmonary dysplasia (BPD) is an important cause of morbidity. The aim of this study was to evaluate the preventive effect of cytidine 5′-diphosphocholine (CDP-choline) treatment on hyperoxic lung injury in a neonatal rat model. Methods: A total of 30 newborn pups were divided into control, hyperoxia, and hyperoxia + CDP-choline groups. After birth, pups in the control group were kept in room air and received saline injections, whereas those in hyperoxia and hyperoxia + CDP-choline groups were exposed to 95% O2 and received daily injections of saline and CDP-choline throughout postnatal day 10, respectively. Histopathological scoring, radial alveolar count, lamellar body membrane protein expression, fibrosis, proinflammatory cytokine levels, lung tissue and bronchoalveolar lavage (BAL) fluid phospholipid content, and apoptosis were evaluated. Results: Hyperoxia-induced severe lung damage was reduced significantly by CDP-choline treatment. Radial alveolar count and lamellar body membrane protein expression were significantly recovered, and the number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling–positive cells, active caspase-3 expression, and tissue proinflammatory cytokine levels were decreased by CDP-choline administration. Lung tissue and BAL phospholipid contents showed significant increases after CDP-choline administration. Conclusion: These data show that CDP-choline ameliorates hyperoxic lung injury in a neonatal rat model. It may therefore be suggested that CDP-choline may be a novel therapeutic option for the prevention of BPD. B ronchopulmonary dysplasia (BPD) is an important cause of morbidity in preterm infants that results in prolonged hospitalization, discharge from hospital with oxygen therapy, frequent readmission to the hospital with respiratory problems, and increased neurodevelopmental risk (1). Although BPD has a multifactorial etiology, major risk factors for BPD development include preterm birth, lower gestational age and birth weight, need for supplemental oxygen and ventilatory support, oxygen toxicity, decreased host antioxidant defenses, patent ductus arteriosus, and pre- and postnatal infections (2). Therefore, treatment of evolving BPD may be challenging due to the complex balance between these contributing risk factors. Efficacy of parenteral administration of vitamin A or caffeine, the two successful treatments developed to prevent BPD, was supported by evidence from randomized, controlled studies (3), whereas many other treatments aiming at preventing BPD have failed to demonstrate a reduction in BPD rates (2). Therefore, newer strategies and pharmacological approaches to prevent BPD are required in order to decrease BPD incidence and severity. Cytidine 5′-diphosphocholine (CDP-choline), which is composed of cytidine and choline linked by a diphosphate bridge, is an endogenous intermediate in the synthesis of the major membrane phospholipid, phosphatidylcholine (PC) (4). PC is quantitatively the most important phospholipid, accounting for 70–85% of the total surfactant phospholipids, which are major constituents of surfactant lipids (5). The primary function of surfactant is to decrease surface tension at the air–liquid surface in the alveoli and distal bronchioli, to promote lung expansion during inspiration in order to prevent atelectasis at end expiration. It also plays an important role in pulmonary host defense and local immunomodulation by enhancing the stability of the film that floats on the alveolar linings, facilitating mucociliary transport, exhibiting antioxidant activity with antibacterial/antiviral properties (5). Due to persisting surfactant abnormalities including an ongoing quantitative deficiency in surfactant components, decreased function of endogenous surfactant, and increased surfactant turnover in ventilated preterms with evolving BPD, surfactant therapy was suggested to show benefits in prevention of BPD (6). In addition, the beneficial effects of additional surfactant therapy for prevention of BPD were also evaluated (7). In addition, in a few studies with conflicting outcomes, CDP-choline was administered parenterally at a dose range of 100–300 mg/kg/d to preterm infants to increase the synthesis of lung phospholipids for alleviating the symptoms of respiratory distress syndrome (8,9). However, to the best of our knowledge, no study evaluated the efficacy of CDP-choline for preventing BPD. Therefore, the aim of this experimental study was to investigate the possible protective effect of CDP-choline against hyperoxic lung injury in a neonatal rat model. Division of Neonatology, Department of Pediatrics, Gulhane Military Medical Academy, Ankara, Turkey; 2Department of Pharmacology, Uludag University Faculty of Medicine, Bursa, Turkey; 3Department of Anatomy, Uludag University Faculty of Medicine, Bursa, Turkey. Correspondence: Merih Cetinkaya () 1 Received 2 August 2012; accepted 26 December 2012; advance online publication 29 May 2013. doi:10.1038/pr.2013.68 26 Pediatric Research      Volume 74 | Number 1 | July 2013 CDP-choline in hyperoxic lung injury RESULTS No significant difference was detected between mean birth weights of pups in the control, hyperoxia, and hyperoxia + CDP-choline groups (5.0 ± 0.4 vs. 4.9 ± 0.2 vs. 5.0 ± 0.3 g, respectively) (P > 0.05). However, the mean body weight of pups in the hyperoxia + CDP-choline group (15.2 ± 1.2 g) was significantly greater than that of pups in the hyperoxia group (12.2 ± 0.9 g) (P = 0.02), but not in the control group (17.4 ± 1.6 g; P > 0.05) at end of the study (postnatal day (P)10). During the experimental procedures, two pups in the hyperoxia group and one pup in the hyperoxia + CDP-choline group died. However, no significant difference was found between these two groups in terms of survival (P > 0.05). Severity of lung damage was evaluated between grades 1 and 4 by histopathologic examination (Figures 1a–c and 2). Thickening of the alveolar septi or cell infiltration was not observed in the control and hyperoxia + CDP-choline groups. CDP-choline treatment significantly improved histological grading of lung injury as compared with saline treatment in the hyperoxia group (P = 0.01) (Figure 1a–c). Masson’s trichrome stained sections also showed cell infiltration, edema, and fibrosis in the hyperoxia group, which were not noticeably observed in the control and hyperoxia + CDP-choline groups (Figure 1d–f). Radial alveolar count, reflected by the number of intact alveoli, was also significantly greater in the hyperoxia + CDP-choline group as compared with the hyperoxia group (P < 0.05) (Figure 2). Control Ar (...truncated)