158 - A toll-like receptor 4 antagonist attenuates inflammation and alveolar simplification in hyperoxia exposed neonatal mice

Poster Number: 158
Publication Number: 158.311

Yi Jin, Research Institute at nationwide Children's Hospital, COLUMBUS, OH, United States; Bernadette Chen, The Ohio State University College of Medicine, Columbus, OH, United States; Jennifer K. Trittmann, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, United States; Yusen Liu, Nationwide Children's Hospital, Columbus, OH, United States; Leif D. Nelin, Nationwide Children's Hospital, Coumbus, OH, United States

Background: Bronchopulmonary dysplasia (BPD) is the chronic lung disease that follows preterm birth. The characteristic lung phenotype of BPD is impaired alveolarization, and a pre-clinical neonatal mouse model using neonatal hyperoxic exposure recapitulates aspects of the characteristic lung phenotype seen in BPD. The inflammatory response is an important mechanism in the lung injury and altered lung development that leads to BPD. Inflammation activates a variety of signal transduction pathways and the toll-like receptor 4 (TLR4) pathway is critical in the inflammatory response.

Objective: To test the hypothesis that neonatal mice treated with TAK-242, a TLR4 antagonist, would be protected from hyperoxia-induced inflammation and the resultant alveolar simplification.

Design/Methods: Neonatal mice on post-natal day 1 (P1) were placed in either room air (Normo) or 85% oxygen (Hyper) using a Biospherix® chamber. Dams were rotated daily to prevent oxygen toxicity to the dam. Mice were given either TAK-242 (TAK), 2 mg/kg or an equal volume of vehicle (DMSO) i.p. daily during the exposure. After 14 days (P14) the lungs were inflation-fixed for H&E staining for determination of alveolar area, perimeter, and number, while in another group of animals bronchoalveolar lavage (BAL) fluid was collected and the lungs harvested for real-time PCR.

Results: BAL cell number from HyperDMSO mice was significantly higher than that from NormoDMSO mice, while HyperTAK mice had substantially fewer BAL cells than did HyperDMSO mice (Table). HyperDMSO mice had significantly greater BAL HMGB1 levels than did NormoDMSO mice, and HyperTAK mice had significantly lower HMGB1 levels in the BAL than did HyperDMSO mice (Table). The mRNA levels of Ccl2 and Ccl7 were highly up-regulated in the lungs from HyperDMSO mice compared to those in the lungs from NormoDMSO mice, and HyperTAK mice had significantly lower Ccl2 and Ccl7 mRNA levels than did HyperDMSO mice (Table). The HyperDMSO mice on P14 had significantly (p < 0.01) greater alveolar area and perimeter, with lower alveolar numbers than did the P14 NormoDMSO mice. In the HyperTAK mice on P14 there were significantly (p < 0.01) lower alveolar area and perimeter, with greater alveolar numbers than in the HyperDMSO mice.Conclusion(s): These data demonstrate that a TLR4 antagonist attenuated lung inflammation and the alveolar simplification caused by hyperoxia in neonatal mice. These findings suggest that TLR4 antagonists may represent novel therapeutic agents for preventing or attenuating BPD.
Table. Inflammatory markers*HyperDMSO different from NormoDMSO, p < 0.001
#HyperTAK different from HyperDMSO, p < 0.001
&HyperTAK different from HyperDMSO, p < 0.01