Hypoxia-Dependent Epigenetic Modifications in the Pulmonary I have - - PowerPoint PPT Presentation

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Sheila Krishnan, D.O.

10th International Conference Neonatal & Childhood Pulmonary Vascular Disease San Francisco, CA March 11, 2017

Hypoxia-Dependent Epigenetic Modifications in the Pulmonary Vasculature

I have no financial disclosures or conflicts of interest Significance of High Altitude Pulmonary Hypertension

• 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

Divergent and Reversible Postnatal Pulmonary Vascular Remodeling in High Altitude vs. Sea Level

F Sime, et al. Brit Heart J 1971

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Peri and Postnatal Events in PH

Risk Factors

• Genetic
• Environmental
• Endogenous

Derived from E Austin, et al. Ann Am Thorac Soc 2014

Fetus Child Adult TIME

*☨

C Sartori, et al. Lancet 1999

Augmented Vasoreactivity in Adult Life Associated with Perinatal Vascular Insult

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 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 E Rexhaj, et al. Am J Physiol Heart Circ Physiol 2011

Epigenetic Induction of Pulmonary Vascular Dysfunction is Reversible through Modification of the In Utero Environment

# p=0.002 vs. controls ⍺ p=0.009 vs. diet + vehicle ✻p=0.02 vs. controls

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Research Questions

• 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)

Differentially Methylated Genes in Peripheral Blood of High Altitude vs. Low Altitude Infants

Low Altitude n=10 High Altitude n=10

• S. Krishnan, et al. Am J Respir Crit Care Med

193;2016:A7841

Hypotheses

• 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

• 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

Research Design

Breeding pair in hypobaric hypoxia (FiO2=15%; equiv to 9,000 ft altitude) Breeding pair in normoxia

Hypoxia In-utero Hypoxia Post-natal Room air In-utero Room air Post-natal

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Datapoints

• Post natal day 1:
• Lung and vascular structure
• DNA-epigenetic analysis: peripheral blood, lung, heart, skeletal muscle
• 6 weeks:
• Lung volumes
• Diffusing capacity
• Right ventricular thickness
• Cardiac output
• Hemodynamics
• Pulmonary artery structure
• DNA-epigenetic analysis: peripheral blood, lung, heart, skeletal muscle

Simulated High Altitude Exposure is Associated with Increased Diffusing Capacities at 6 wks of age

male female male female 0.00 0.05 0.10 0.15 DLCO RA-RA H-H

p=0.028 p=0.0127

Simulated High Altitude Exposure is Associated with Increased Functional Residual Capacity at 6 wks of age

male female male female 0.000 0.005 0.010 0.015 0.020 FRC/weight RA-RA H-H

p=0.007

Simulated High Altitude Exposure is Associated with Increased RV Cardiac Output in Males at 6 wks of age

male female male female 0.0 0.5 1.0 1.5 2.0

RV CO/weight

RA-RA H-H p=0.0475

3/11/2017 5 Simulated High Altitude Exposure is Associated with Increased RV Mass in Males at 6 wks of age

male female male female 0.0 0.1 0.2 0.3 0.4 0.5 RV/LV+septum

RA-RA H-H p=0.0019

Summary

• Preliminary data indicates there is a HAPH phenotype at 15% FiO2
• 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 RA-RA and H-H groups – Perform cross-over study for RA-H and H-RA groups

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

THANK YOU