2-Chlorohexadecanoic acid induces ER stress and mitochondrial dysfunction in brain microvascular endothelial cells

Redox Biol. 2018 May;15:441-451. doi: 10.1016/j.redox.2018.01.003. Epub 2018 Jan 5.

Abstract

Peripheral leukocytes induce blood-brain barrier (BBB) dysfunction through the release of cytotoxic mediators. These include hypochlorous acid (HOCl) that is formed via the myeloperoxidase-H2O2-chloride system of activated phagocytes. HOCl targets the endogenous pool of ether phospholipids (plasmalogens) generating chlorinated inflammatory mediators like e.g. 2-chlorohexadecanal and its conversion product 2-chlorohexadecanoic acid (2-ClHA). In the cerebrovasculature these compounds inflict damage to brain microvascular endothelial cells (BMVEC) that form the morphological basis of the BBB. To follow subcellular trafficking of 2-ClHA we synthesized a 'clickable' alkyne derivative (2-ClHyA) that phenocopied the biological activity of the parent compound. Confocal and superresolution structured illumination microscopy revealed accumulation of 2-ClHyA in the endoplasmic reticulum (ER) and mitochondria of human BMVEC (hCMEC/D3 cell line). 2-ClHA and its alkyne analogue interfered with protein palmitoylation, induced ER-stress markers, reduced the ER ATP content, and activated transcription and secretion of interleukin (IL)-6 as well as IL-8. 2-ClHA disrupted the mitochondrial membrane potential and induced procaspase-3 and PARP cleavage. The protein kinase R-like ER kinase (PERK) inhibitor GSK2606414 suppressed 2-ClHA-mediated activating transcription factor 4 synthesis and IL-6/8 secretion, but showed no effect on endothelial barrier dysfunction and cleavage of procaspase-3. Our data indicate that 2-ClHA induces potent lipotoxic responses in brain endothelial cells and could have implications in inflammation-induced BBB dysfunction.

Keywords: Apoptosis; Blood-brain barrier; Lipotoxicity; Myeloperoxidase; Neuroinflammation; Structured illumination microscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Apoptosis / drug effects
  • Blood-Brain Barrier / drug effects
  • Blood-Brain Barrier / pathology
  • Brain / metabolism*
  • Brain / pathology
  • Cell Line
  • Endoplasmic Reticulum Stress / drug effects
  • Endothelial Cells / metabolism*
  • Humans
  • Indoles / pharmacology
  • Interleukin-8 / genetics
  • Leukocytes / metabolism
  • Membrane Potential, Mitochondrial / drug effects
  • Mitochondria / drug effects*
  • Mitochondria / pathology
  • Palmitic Acids / adverse effects*
  • Palmitic Acids / metabolism
  • Peroxidase / metabolism
  • eIF-2 Kinase / genetics

Substances

  • 2-chlorohexadecanoic acid
  • 7-methyl-5-(1-((3-(trifluoromethyl)phenyl)acetyl)-2,3-dihydro-1H-indol-5-yl)-7H-pyrrolo(2,3-d)pyrimidin-4-amine
  • Indoles
  • Interleukin-8
  • Palmitic Acids
  • Peroxidase
  • PERK kinase
  • eIF-2 Kinase
  • Adenine