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

Respirology. 2017 Jan;22(1):157-164. doi: 10.1111/resp.12872. Epub 2016 Aug 18.

Abstract

Background and objective: 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). 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.

Methods: The 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.

Conclusion: Inhibition of BETs in primary HPMECs decreases inflammation and remodelling. BET proteins could be a target for future therapies for PAH.

Keywords: bromodomain and extra-terminal proteins; human pulmonary microvascular endothelial cells; inflammation; proliferation; pulmonary hypertension.

MeSH terms

  • Azepines / pharmacology
  • Cell Culture Techniques
  • Cell Proliferation / drug effects*
  • Down-Regulation
  • Endothelial Cells* / drug effects
  • Endothelial Cells* / metabolism
  • Humans
  • Hypertension, Pulmonary* / metabolism
  • Hypertension, Pulmonary* / physiopathology
  • Inflammation / metabolism
  • Interleukin-8 / metabolism
  • Lung / metabolism
  • Lung / pathology
  • Microvessels / drug effects
  • Microvessels / metabolism
  • NF-kappa B / metabolism*
  • Proteins / metabolism*
  • Pulmonary Circulation
  • Triazoles / pharmacology
  • Vascular Remodeling / drug effects*

Substances

  • (+)-JQ1 compound
  • Azepines
  • CXCL8 protein, human
  • Interleukin-8
  • NF-kappa B
  • Proteins
  • Triazoles
  • bromodomain and extra-terminal domain protein, human