Histone Deacetylation Inhibition in Pulmonary Hypertension: Therapeutic Potential of Valproic Acid (VPA) and Suberoylanilide Hydroxamic Acid (SAHA)
Background—Epigenetic programming, dynamically regulated by histone acetylation, is a key mechanism regulating cell proliferation and survival. Little is known about the contribution of histone deacetylase (HDAC) activity to the development of pulmonary arterial hypertension (PAH), a condition characterised by profound structural remodelling of pulmonary arteries and arterioles.
Methods and Results—HDAC1 and HDAC5 protein levels were elevated in lungs from human idiopathic PAH and in lungs and right ventricles from rats exposed to hypoxia. Immunohistochemistry localised increased expression to remodelled vessels in the lung. Both valproic acid (VPA), a class I HDAC inhibitor, and suberoylanilide hydroxamic acid (SAHA), an inhibitor of class I, II and IV HDACs, mitigated the development and reduced established hypoxia-induced pulmonary hypertension in the rat. Both VPA and SAHA inhibited the "imprinted" highly proliferative phenotype of fibroblasts and R-cells from pulmonary hypertensive bovine vessels and PDGF-stimulated growth of human vascular smooth muscle cells in culture. Exposure to VPA and SAHA was associated with increased levels of p21 and FOXO3 and reduced expression of survivin. The significantly higher level of expression of cKIT, MCP-1, IL-6, SDF-1, PDGFb and S100A4 in the R-cells were down regulated by VPA and SAHA treatment.
Conclusions—Increased HDAC activity contributes to the vascular pathology of pulmonary hypertension. The effectiveness of HDAC inhibitors VPA and SAHA, in models of PAH, support a therapeutic strategy based on HDAC inhibition in PAH.
- epigenetic modification
- histone deacetylation
- pulmonary hypertension
- suberoylanilide hydroxamic acid
- valproic acid
- Received March 2, 2012.
- Accepted June 8, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited