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The Effects of Phellinus linteus Polysaccharide Extracts on Cholesterol Efflux in Oxidized Low-Density Lipoprotein–Loaded THP-1 Macrophages
  1. Xiao-hui Li, MD*,
  2. Yan Li, MD,
  3. Zhao-yun Cheng, MD*,
  4. Xi-guo Cai, MD,
  5. Hong-min Wang, MD§
  1. From the *Department of Cardiovascular Surgery ICU, Henan Provincial People’s Hospital, Zhengzhou; †Department of Radiology, Puyang City Oil-Field General Hospital, Puyang; and ‡Department of Rehabilitation Medicine, Henan Provincial People’s Hospital; and §Department of Respiratory, The First Affiliated Hospital of Zhengzhou University, Henan Province, China.
  1. Received December 3, 2014, and in revised form February 25, 2015.
  2. Accepted for publication March 24, 2015.
  3. Reprints: Xi-guo Cai, PhD, Department of Rehabilitation Medicine, Henan Provincial People’s Hospital, Zhengzhou 450003, Henan Province, China. E-mail: xiguocai2000{at}163.com.
  4. X.L. and Y.L. are contributed equally to this work.

Abstract

The removal of excess cellular cholesterol is critical for maintaining cellular cholesterol homeostasis. Phellinus linteus polysaccharide extracts (PLPEs) is an immunomudulatory agent with a molecular weight of 153 kd. Here, we analyzed the effects of PLPEs on cholesterol efflux in oxidized low-density lipoprotein (ox-LDL)–loaded THP-1 (human acute monocytic leukemia cell line) macrophages. Various concentrations of PLPEs (5, 10, 20, and 100 μg/mL) were used to treat cells. Cholesterol efflux analysis was performed to analyze the cholesterol efflux ratio in PLPE-treated cells. Semiquantitative reverse transcription–polymerase chain reaction and Western blot analysis were conducted to assess the expression of target genes. Low dose of PLPEs (5-20 μg/mL) dose dependently enhanced cholesterol efflux to apolipoprotein A-I (ApoA-I), evidenced by promoting the expression of adenosine 5′-triphosphate (ATP)–binding cassette A1, ATP-binding cassette G1, and peroxisome proliferation–activated receptor γ, key regulators for cholesterol efflux. Moreover, GW9662, a potent antagonist of peroxisome proliferation–activated receptor γ, inhibited PLPE (20 μg/mL)–promoted cholesterol efflux to ApoA-I in a dose-dependent fashion. However, high dose of PLPEs (100 μg/mL) inhibited cholesterol efflux to ApoA-I from ox-LDL–loaded THP-1 macrophages, enhanced the production of superoxide anion, decreased mitochondrial membrane potential and ATP levels, and raised nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate oxidase subunits. Thus, these results indicate that low and high doses of PLPEs exhibit opposite effects on cholesterol efflux from ox-LDL–loaded THP-1 cells.

Key Words
  • cholesterol efflux
  • THP-1 cells
  • Phellinus linteus polysaccharide extracts
  • peroxisome proliferation–activated receptor γ (PPAR-γ)
  • mitochondrial membrane potential

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