Phytochemical indicaxanthin suppresses 7-ketocholesterol-induced THP-1 cell apoptosis by preventing cytosolic Ca(2+) increase and oxidative stress

Br J Nutr. 2013 Jul 28;110(2):230-40. doi: 10.1017/S000711451200493X. Epub 2012 Dec 11.

Abstract

7-Ketocholesterol (7-KC)-induced apoptosis of macrophages is considered a key event in the development of human atheromas. In the present study, the effect of indicaxanthin (Ind), a bioactive pigment from cactus pear fruit, on 7-KC-induced apoptosis of human monocyte/macrophage THP-1 cells was investigated. A pathophysiological condition was simulated by using amounts of 7-KC that can be reached in human atheromatous plaque. Ind was assayed within a micromolar concentration range, consistent with its plasma level after dietary supplementation with cactus pear fruit. Pro-apoptotic effects of 7-KC were assessed by cell cycle arrest, exposure of phosphatidylserine at the plasma membrane, variation of nuclear morphology, decrease of mitochondrial trans-membrane potential, activation of Bcl-2 antagonist of cell death and poly(ADP-ribose) polymerase-1 cleavage. Kinetic measurements within 24 h showed early formation of intracellular reactive oxygen species over basal levels, preceding NADPH oxidase-4 (NOX-4) over-expression and elevation of cytosolic Ca²⁺, with progressive depletion of total thiols. 7-KC-dependent activation of the redox-sensitive NF-κB was observed. Co-incubation of 2·5 μm of Ind completely prevented 7-KC-induced pro-apoptotic events. The effects of Ind may be ascribed to inhibition of NOX-4 basal activity and over-expression, inhibition of NF-κB activation, maintaining cell redox balance and Ca homeostasis, with prevention of mitochondrial damage and consequently apoptosis. The findings suggest that Ind, a highly bioavailable dietary phytochemical, may exert protective effects against atherogenetic toxicity of 7-KC at a concentration of nutritional interest.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Atherosclerosis / prevention & control
  • Betaxanthins / blood
  • Betaxanthins / pharmacology*
  • Betaxanthins / therapeutic use
  • Calcium / metabolism*
  • Cell Line
  • Cytosol / metabolism
  • Dietary Supplements
  • Fruit
  • Humans
  • Ketocholesterols / adverse effects*
  • Ketocholesterols / metabolism
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Mitochondria / drug effects
  • Monocytes / drug effects
  • Monocytes / metabolism
  • NADPH Oxidase 4
  • NADPH Oxidases / metabolism
  • NF-kappa B / metabolism
  • Opuntia / chemistry*
  • Oxidative Stress / drug effects*
  • Phytotherapy
  • Plant Extracts / pharmacology*
  • Plaque, Atherosclerotic / prevention & control
  • Pyridines / blood
  • Pyridines / pharmacology*
  • Pyridines / therapeutic use
  • Reactive Oxygen Species / metabolism
  • Sulfhydryl Compounds / metabolism

Substances

  • Betaxanthins
  • Ketocholesterols
  • NF-kappa B
  • Plant Extracts
  • Pyridines
  • Reactive Oxygen Species
  • Sulfhydryl Compounds
  • indicaxanthin
  • NADPH Oxidase 4
  • NADPH Oxidases
  • NOX4 protein, human
  • 7-ketocholesterol
  • Calcium