Bromodomain and extra-terminal protein mimic JQ1 decreases inflammation in human vascular endothelial cells: Implications for pulmonary arterial hypertension.

Sharon Mumby,S John Wort,Ian M Adcock,Chao Meng,Frederic Perros,Marc Humbert,Natalia Gambaryan

doi:10.1111/resp.12872

Abstract

ABSTRACT Background and objectiveNuclear factor kappa B (NF‐kB)‐mediated inflammatory gene expression and vascular endothelial cell proliferation/remodelling are implicated in the pathophysiology of the fatal disease, pulmonary arterial hypertension (PAH). Bromodomain and extra‐terminal (BET) proteins are essential for the expression of a subset of NF‐kB‐induced inflammatory genes. BET mimics including JQ1+ prevent binding of BETs to acetylated histones and down‐regulate the expression of selected genes.MethodsThe effects of JQ1+ on the proliferation of primary human pulmonary microvascular endothelial cells (HPMECs) from healthy subjects were measured by bromodeoxyuridine (BrdU) incorporation. Cell cycle progression was assessed by flow cytometry; mRNA and protein levels of cyclin‐dependent kinases (CDKs), inhibitors and cytokines were determined by reverse transcription‐quantitative PCR (RT‐qPCR), Western blotting or ELISA. Histone acetyltransferase (HAT) and deacetylase (HDAC) activities were determined in nuclear extracts from whole lung of PAH and control patients.Results JQ1+ significantly inhibited IL6 and IL8 (IL6 and CXCL8) mRNA and protein in HPMECs compared with its inactive enantiomer JQ1−. JQ1+ decreased NF‐kB p65 recruitment to native IL6 and IL8 promoters. JQ1+ showed a concentration‐dependent decrease in HPMEC proliferation compared with JQ1−‐treated cells. JQ1+ induced G1 cell cycle arrest by increasing the expression of the CDK inhibitors (CDKN) 1A (p21cip) and CDKN2D (p19INK4D) and decreasing that of CDK2, CDK4 and CDK6. JQ1+ also inhibited serum‐stimulated migration of HPMECs. Finally, HAT activity was significantly increased in the lung of PAH patients.ConclusionInhibition of BETs in primary HPMECs decreases inflammation and remodelling. BET proteins could be a target for future therapies for PAH.

Highlights

Pulmonary arterial hypertension (PAH) describes a group of diseases characterized by raised pulmonary vascular resistance, resulting from vascular remodelling in the pre-capillary resistance arterioles.[1]
Endothelial cell inflammation and proliferation are important in the pathogenesis of pulmonary arterial hypertension (PAH)
The enhanced histone acetyltransferase (HAT) activity in PAH suggests that Bromodomain and extra-terminal (BET) mimics may be effective in PAH experiments in disease cells/tissues are required

Summary

Introduction

Pulmonary arterial hypertension (PAH) describes a group of diseases characterized by raised pulmonary vascular resistance, resulting from vascular remodelling in the pre-capillary resistance arterioles.[1]. Patients die from right heart failure within 3 years of diagnosis if untreated Treatment with vasodilators, such as endothelin (ET) receptor antagonists, prostacyclin analogues and phophodiesterase type V inhibitors, has improved both morbidity and mortality[2]; these are not a cure and the mortality rate in patients is still unacceptably high.[2]. It is, important to understand the mechanisms of vascular remodelling in PAH and to determine novel therapies targeting these abnormalities. Nuclear factor kappa B (NF-kB)-mediated inflammatory gene expression and vascular endothelial cell proliferation/remodelling are implicated in the pathophysiology of the fatal disease, pulmonary arterial hypertension (PAH).

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