The alternation of autophagy/apoptosis in CD4+CD25+Foxp3+ Tregs on the developmental stages of atherosclerosis

Biomed Pharmacother. 2018 Jan:97:1053-1060. doi: 10.1016/j.biopha.2017.11.013. Epub 2017 Nov 9.

Abstract

Naturally regulatory T cells (Tregs) play a critical role in the regulation of T cell-mediated immune responses in atherosclerosis. However, the regulatory mechanism underlying Tregs upon long-term development of atherosclerosis remains unknown. Therefore, in this study, atherosclerotic model was induced in ApoE-/- mice by feeding fat-diet for 10 weeks. Quantification of atherosclerotic lesions was done by calculating the lesion size in the aortic sinus every 2 weeks. The lipid levels and inflammatory mediators were detected in serum sample. The populations of CD4+CD25+Foxp3+ Tregs were compared between ApoE-/- mice (ApoE-/-) and wild type C57BL/6 littermates (WT). The expression levels of autophagy and apoptosis signaling related regulators were determined by flow cytomery, RT-qPCR, and western blot assays in the CD4+CD25+Foxp3+ Tregs isolated from ApoE-/- and WT. We found that the sizes of plaque lesions in atherosclerotic ApoE-/- mice were larger than those in WT group during 10 weeks' detection (all P<0.05); Whereas, flow cytometry assay showed that the populations of CD4+CD25+Foxp3+ Tregs were significantly reduced in atherosclerotic ApoE-/- mice compared with those in corresponding WT group from the 4th weeks' detection (all P<0.05). The lipid accumulation and increased pro-inflammatory mediators were correlated with the developmental progression of atherosclerosis. Furthermore, compared to WT group, the functional properties of CD4+CD25+Foxp3+ Tregs from ApoE-/- mice showed a gradually decreased autophagic activity with aberrant expressions of LC3, Beclin1, ATG5, ATG7, p62 (all P<0.05), and a gradually increased apoptotic activity with abnormal expressions of cleaved caspase 3, Bim, Bcl-2 (all P<0.05) during the 10 weeks' detection period. Taken together, our data demonstrated that the population of CD4+CD25+Foxp3+ Tregs was reversely correlated with plaque forming in atherosclerotic ApoE-/- mice during atherosclerosis development. And the autophagy/apoptosis-dependent Tregs might play a crucial role for the maintenance of CD4 9+CD25+Foxp3+ Tregs survival during atherosclerosis progression.

Keywords: ApoE-/-; Apoptosis; Atherosclerosis; Autophagy; Foxp3; Naturally regulatory T cells.

MeSH terms

  • Animals
  • Apolipoproteins E / genetics
  • Apoptosis / immunology*
  • Atherosclerosis / immunology*
  • Autophagy / immunology*
  • Blotting, Western
  • CD4-Positive T-Lymphocytes / immunology
  • Disease Models, Animal
  • Disease Progression
  • Flow Cytometry
  • Forkhead Transcription Factors / immunology
  • Inflammation Mediators / immunology
  • Interleukin-2 Receptor alpha Subunit / immunology
  • Lipids / blood
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes, Regulatory / immunology*

Substances

  • Apolipoproteins E
  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • Inflammation Mediators
  • Interleukin-2 Receptor alpha Subunit
  • Lipids