KRP-203, Sphingosine 1-Phosphate Receptor Type 1 Agonist, Ameliorates Atherosclerosis in LDL-R −/− Mice

Abstract

Sphingosine 1-phosphate (S1P) partly accounts for antiatherogenic properties of high-density lipoproteins. We previously demonstrated that FTY720, a synthetic S1P analog targeting all S1P receptors but S1P receptor type 2, inhibits murine atherosclerosis. Here, we addressed the identity of S1P receptor mediating atheroprotective effects of S1P. Low-density lipoprotein receptor-deficient mice on cholesterol-rich diet were given selective S1P receptor type 1 agonist KRP-203 (3.0 mg/kg per day; 6 and 16 weeks). KRP-203 substantially reduced atherosclerotic lesion formation without affecting plasma lipid concentrations. However, KRP-203 induced lymphopenia, reduced total (CD4(+), CD8(+)) and activated (CD69(+)/CD8(+), CD69(+)/CD4(+)) T cells in peripheral lymphoid organs, and interfered with lymphocyte function, as evidenced by decreased T-cell proliferation and interleukin-2 and interferon-γ production in activated splenocytes. Cyto- and chemokine (tumor necrosis factor-α, regulated and normal T cell expressed and secreted) levels in plasma and aortas were reduced by KRP-203 administration. Moreover, macrophages from KRP-203-treated mice showed reduced expression of activation marker MCH-II and poly(I:C)-elicited production of tumor necrosis factor-α, monocyte chemoattractant protein-1, and interleukin-6. In vitro studies demonstrated that KRP-203 reduced tumor necrosis factor-α, interleukin-6, and interferon-γ-induced protein-10 production; IκB and signal transducer and activator of transcription-1 phosphorylation; and nuclear factor κB and signal transducer and activator of transcription-1 activation in poly(I:C)-, lipopolysaccharide-, or interferon-γ-stimulated bone marrow macrophages, respectively. Present results demonstrate that activation of S1P signaling pathways inhibit atherosclerosis by modulating lymphocyte and macrophage function and suggest that S1P receptor type 1 at least partially mediates antiatherogenic effects of S1P.