Hypoxia-Dependent Epigenetic Modifications in the Pulmonary Vasculature

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1 Hypoxia-Dependent Epigenetic Modifications in the Pulmonary Vasculature I have no financial disclosures or conflicts of interest Sheila Krishnan, D.O. 10th International Conference Neonatal & Childhood Pulmonary Vascular Disease San Francisco, CA March 11, 2017 Significance of High Altitude Pulmonary Hypertension Divergent and Reversible Postnatal Pulmonary Vascular Remodeling in High Altitude vs. Sea Level HAPH is a designated subset of PH under the group III clinical classification (PH due to lung disease/hypoxemia) Estimated that 140 million people reside at high altitude (>8200 feet above sea level) and 40 million temporary visitors to mountains Pathology involves hypoxia-driven pulmonary artery smooth muscle cell proliferation that is reversible upon descent to sea level P Bartsch, et al. NEJM 2013 D Penaloza, et al. Circ 2007 F Sime, et al. Brit Heart J

2 Peri and Postnatal Events in PH Risk Factors Genetic Environmental Endogenous Augmented Vasoreactivity in Adult Life Associated with Perinatal Vascular Insult * Fetus Child Adult TIME Derived from E Austin, et al. Ann Am Thorac Soc 2014 C Sartori, et al. Lancet 1999 Significance of Epigenetics and PH Epigenetics: refers to changes in gene expression that do not involve changes in the DNA sequence Change in phenotype without change in genotype Epigenetic Induction of Pulmonary Vascular Dysfunction is Reversible through Modification of the In Utero Environment Epigenetic changes in mitochondrial metabolism and histone acetylation have been linked to vascular pathology in PH development in animal models SL Archer, et al. Circ 2010 L Zhao, et al. Circ 2012 # p=0.002 vs. controls p=0.009 vs. diet + vehicle p=0.02 vs. controls E Rexhaj, et al. Am J Physiol Heart Circ Physiol

3 Research Questions Differentially Methylated Genes in Peripheral Blood of High Altitude vs. Low Altitude Infants Do epigenetic modifications play a role in the adaptive response to chronic hypoxia? If so, what pathways are involved and how early in life do these modifications begin? Green: hypomethylated (upregulated) genes Red: hypermethylated (downregulated) genes Hypomethylated pathways/genes Lung differentiation (NFATc1) VEGF signaling (SEMA3A) Low Altitude n=10 High Altitude n=10 S. Krishnan, et al. Am J Respir Crit Care Med 193;2016:A7841 Hypotheses Research Design Epigenetic changes play a role in the developmental adaptive response to chronic hypoxia Chronic hypoxia in utero stimulates epigenetic modifications of hypoxia-sensitive pathways that provide developmental adaptive processes in the cardiopulmonary system and minimize HAPH Breeding pair in hypobaric hypoxia (FiO2=15%; equiv to 9,000 ft altitude) Hypoxia In-utero Hypoxia Post-natal The epigenetic modifications that occur in utero are inducible and reversible when the post utero environment is changed Responses to chronic hypoxia differ between males and females Breeding pair in normoxia Room air In-utero Room air Post-natal 3

4 Datapoints Post natal day 1: Lung and vascular structure DNA-epigenetic analysis: peripheral blood, lung, heart, skeletal muscle with Increased Diffusing Capacities at 6 wks of age 0.15 p= weeks: Lung volumes Diffusing capacity Right ventricular thickness Cardiac output Hemodynamics Pulmonary artery structure DNA-epigenetic analysis: peripheral blood, lung, heart, skeletal muscle DLCO p= with Increased Functional Residual Capacity at 6 wks of age FRC/weight p=0.007 with Increased RV Cardiac Output in Males at 6 wks of age RV CO/weight p=

5 with Increased RV Mass in Males at 6 wks of age Summary Preliminary data indicates there is a HAPH phenotype at 15% FiO2 RV/LV+septum p= Males seem to have a more distinct phenotype compared to females, suggesting that sex hormones may play a role Next Steps: Perform epigenetic analyses on tissue from and groups Perform cross-over study for RA-H and H-RA groups THANK YOU Mentors: Tim Lahm, M.D. Rob Tepper, M.D, Ph.D. Lab Members: Yong Gao Amanda Fischer Margie Albrecht Andrea Frump, Ph.D. Funding: PHA - Cordelia's Pediatric PH Research and Mentoring Grant T32 Training Program in Molecular Physiology and Clinical Mechanisms of Lung Disease, Indiana University 5