Abstract 154: Atherosclerosis-specific CD4 T Cells Use the Chemokine CCL5 and Its Receptor CCR5 to Home to Mature Atherosclerotic Lesions in Mice
Introduction: T cell adaptive immunity is involved in the pathogenesis of atherosclerosis, but the phenotype of T cell subset and chemokine receptor that regulates effector T cell trafficking to atherosclerotic aortas is unknown. By multi-color flow cytometry, we discovered that >40% of T cells in the atherosclerotic aortas express CCR5. We hypothesize that CCR5 plays an important role in T cell recruitment to atherosclerotic aortas and CCR5+ T cells play an important roll in the pathogenesis of atherosclerosis.
Methods: T cell phenotype in the aorta of Apoe-/- mice on western diet 3-5 months was analyzed by multi-color flow cytometry. T cell homing assay were done in vitro by incubating 400,000 Teff from CD45.1Apoe-/- mice with explanted Apoe-/- aortas 12 to 18 hrs with media alone, CCL5 neutralizing antibody (0.5 ug/ml) or PTX (300ng/ml), and in vivo by adoptively transferring splenocytes from Apoe-/-Ccr5-/- and dsRedApoe-/- mice at 1:1 ratio into CD45.1Apoe-/- recipients. 24 hours later, recipient aortas were digested and analyzed by flow cytometry. To visualize T cell proximity to APCs in the aorta by 2 photon imaging, Teff from Apoe-/- mice were labeled with SNARF before incubation with explanted aortas from CD11c-YFP+Apoe-/- mice in the above 3 conditions. In vitro T cell suppression assay was done by incubating 104 CD4+CD25- T cells with α-CD3 mAb and 5x104 irradiated splenic APCs and decreasing amount of Treg or CCR5Teff. Transcriptomic analysis is done following SMARTseq II prortocol from Illumina.
Results: 43±6% of αβ T cells in the atherosclerotic aortas express CCR5, significantly higher than that in aortas of wild-type C57BL/6 mice (10±7%) or Apoe-/- mice on normal diet (7±6%). CCR5 and its ligand CCL5 play the major role in regulating T cell homing to atherosclerotic aortas in vitro and in vivo. Interestingly, at late stage of disease, the CCR5+ T cells in the atherosclerotic plaques are all FoxP3+IFN-γ+T-bet+CD25-CD44hiCD62Llo (CCR5Teff) and do not suppress T cell proliferation. CCR5Teffs are only found in the aorta and para-aortic lymph nodes of Apoe-/- mice but not in the spleen or other organs. Transcriptomic analysis shows that CCR5Teff is more similar to Teff rather than Tregs.
Author Disclosures: J. Li: None. K. Ley: None.
This research has received full or partial funding support from the American Heart Association.
- © 2015 by American Heart Association, Inc.