422 - Chorioamnionitis induces perinatal imbalance of pro- and anti-angiogenic factors leading to late pulmonary hypertension

Poster Number: 422
Publication Number: 422.429

April W. Tan, Holtz Children's Hospital Jackson Memorial Hospital, Miami, FL, United States; Pingping Chen, University of Miami, Miami, FL, United States; Silvia Alvarez Cubela, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Shathiyah Kulandavelu, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Xiaoying Tong, University of Miami Leonard M. Miller School of Medicine, Palmetto bay, FL, United States; Shaoyi Chen, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Vanessa Nunes de Paiva, University of Miami, Miami, FL, United States; Shu Wu, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States; Juan Dominguez-Bendala, University of Miami, Miami, FL, United States; Karen Young, University of Miami, Miami, FL, United States; Claudia Rodrigues, Charles E. Schmidt College of Medicine at Florida Atlantic University, Boca Raton, FL, United States; Augusto F. Schmidt, University of Miami Leonard M. Miller School of Medicine, Miami, FL, United States

Background: Chorioamnionitis occurs in 85% of preterm births before 30 weeks’ gestation and is associated with lung inflammation, remodeling, and bronchopulmonary dysplasia. We previously reported lung vascular and parenchymal remodeling in a neonatal rat model of chorioamnionitis. However, the early mechanisms through which chorioamnionitis leads to lung vascular remodeling and pulmonary hypertension are not well understood.

Objective: To determine mechanisms by which chorioamnionitis induces lung injury and pulmonary vascular remodeling and the long-term consequences.

Design/Methods: Pregnant Sprague-Dawley rats were randomized to receive ultrasound-guided intra-amniotic (IA) injections of lipopolysaccharide (LPS) or saline on gestational day 19 and allowed to deliver spontaneously. Localization of IA LPS was determined by in vivo imaging of a fluorescent tagged LPS. Placental and lung tissue was harvested at 24 hours post-exposure. Lung tissue was harvested at postnatal days (P) 0, 3, 7 and 14. Lung structural changes were assessed by immunostaining. Cytokine levels and mRNA expression were evaluated by multiplex assay and RT-PCR. Echocardiograms were performed at P14 to assess for right ventricular hypertrophy.

Results: At 24 hours post-LPS exposure, there was a trend toward increased placental expression of TNF-ꭤ, IL-1β, IL-6 and IL-10 (LPS-exposed n=2, Controls n=2). At P0, lung mRNA expression of pro-inflammatory mediators TNF-ꭤ and IL-1β in IA LPS-exposed rat pups were significantly increased (n=4 per group). However, lung cytokine multiplex assay at P0 showed downregulation of multiple pro-inflammatory mediators (IFN-γ, IL-17A, CXCL5, IL-18) and no difference at P3, including TNF-ꭤ and IL-1β. IA LPS-exposed rat pups had decreased levels of pro-angiogenic CXCL5 and increased anti-angiogenic CXCL10 at P0, and decreased pro-angiogenic VEGF at P3 (n=5 per group). At P14, LPS-exposed pups had decreased lung angiogenesis, increased pulmonary vascular remodeling and right ventricular hypertrophy (RV:LV ratio 0.31 vs 0.26, p< 0.02).Conclusion(s): In a neonatal rat model of chorioamnionitis, IA LPS exposure induced early, short-term lung inflammation and lung vascular remodeling. Despite resolution of lung inflammation at P3 there was suppression of VEGF. Chorioamnionitis-induced lung vascular remodeling is associated with early suppression of CXCL5 and induction of CXCL10 leading to development of pulmonary hypertension. Further studies will be needed to characterize the time-course and investigate potential targeted therapies for perinatal lung injury and vascular remodeling.
Figure 1.Cytokine multiplex assay showing decrease in pro-angiogenic factors VEGF and CXCL5 (at P3 and P0 respectively), and increase in anti-angiogenic factor CXCL10 at P0 (*p < 0.05, **p < 0.02). Controls n=5, LPS-exposed n=5
Figure 2.Left to right: At P14, decreased lung angiogenesis in LPS-exposed pups (controls n=5, LPS n=4) shown by decreased number of vessels stained with von Willebrand factor (vWF) per high power field (hpf); Increased pulmonary vascular remodeling in LPS-exposed pups shown by increased ratio of vessels stained with smooth muscle actin/vWF (SMA/vWF) per hpf (controls n=5, LPS n=4); Echocardiogram data showing right ventricular hypertrophy by increase in RV/LV ratio in LPS-exposed pups (n=5) compared to controls (n=5). **p < 0.02, ***p < 0.01