Protective effect of chorioamnionitis on the development of bronchopulmonary dysplasia triggered by postnatal systemic inflammation in neonatal rats

BACKGROUND: Prenatal or postnatal systemic inflammation can contribute to the development of bronchopulmonary dysplasia (BPD). We investigated whether prenatal intra-amniotic (i.a.) inflammation or early postnatal systemic inflammation can induce BPD in a rat model. METHODS: One microgram of lipopolysaccharide (LPS) or vehicle was injected into the amniotic sacs 2 d before delivery (E20). After birth, 0.25 mg/kg of LPS or vehicle was injected into the peritoneum of pups on postnatal day (P)1, P3, and P5. On P7 and P14, peripheral blood (PB), bronchoalveolar lavage fluid (BALF), and lung tissue were obtained and analyzed. RESULTS: Postnatal i.p. injections of LPS significantly increased neutrophil counts in PB and BALF on P7 and P14. Similarly, pro inflammatory cytokine and angiogenic factor transcript levels were increased in the lung by i.p. LPS on P7. Alveolar and pulmonary vascular development was markedly disrupted by i.p. LPS on P14. However, pretreatment with i.a. LPS significantly negated the detrimental effects of postnatal i.p. LPS on PB and BALF neutrophil counts and on lung proinflammatory cytokine expression and histopathological changes. CONCLUSION: Exposure to early postnatal systemic LPS induces BPD, an arrest in alveolarization, in neonatal rats. Preceding exposure to i.a. LPS protects the lungs against BPD triggered by postnatal systemic inflammation.