Department of Medicine, Division of Rheumatology, Allergy and Immunology, University of California at San Diego , La Jolla, CA , USA ; Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology , La Jolla, CA , USA.
Department of Medicine, Division of Endocrinology and Metabolism, University of California at San Diego , La Jolla, CA , USA.
Front Immunol. 2013 Dec 27;4:493. doi: 10.3389/fimmu.2013.00493. eCollection 2013.
Subsets of CD4(+) T-cells have been proposed to serve differential roles in the development of atherosclerosis. Some T-cell types are atherogenic (T-helper type 1), while others are thought to be protective (regulatory T-cells). Lineage commitment toward one type of helper T-cell versus another is strongly influenced by the inflammatory context in which antigens are recognized. Immunization of atherosclerosis-prone mice with low-density lipoprotein (LDL) or its oxidized derivative (ox-LDL) is known to be atheroprotective. However, the antigen specificity of the T-cells induced by vaccination and the mechanism of protection are not known.
Identification of two peptide fragments (ApoB3501-3516 and ApoB978-993) from murine ApoB-100 was facilitated using I-Ab prediction models, and their binding to I-Ab determined. Utilizing a vaccination scheme based on complete and incomplete Freund's adjuvant (CFA and IFA) [1 × CFA + 4 × IFA], we immunized Apoe(-/-)mice with ApoB3501-3516 or ApoB978-993 emulsified in CFA once and subsequently boosted in IFA four times over 15 weeks. Spleens, lymph nodes, and aortas were harvested and evaluated by flow cytometry and real time RT-PCR. Total atherosclerotic plaque burden was determined by aortic pinning and by aortic root histology.
Mice immunized with ApoB3501-3516 or ApoB978-993 demonstrated 40% reduction in overall plaque burden when compared to adjuvant-only control mice. Aortic root frozen sections from ApoB3501-3516 immunized mice showed a >60% reduction in aortic sinus plaque development. Aortas from both ApoB3501-3516 and ApoB978-993 immunized mice contained significantly more mRNA for IL-10. Both antigen-specific IgG1 and IgG2c titers were elevated in ApoB3501-3516 or ApoB978-993 immunized mice, suggesting helper T-cell immune activity after immunization.
Our data show that MHC Class II restricted ApoB-100 peptides can be atheroprotective, potentially through a mechanism involving elevated IL-10.
已提出 CD4(+) T 细胞亚群在动脉粥样硬化的发展中发挥不同的作用。一些 T 细胞类型具有致动脉粥样硬化作用（辅助性 T 细胞 1 型），而另一些则被认为具有保护作用（调节性 T 细胞）。辅助性 T 细胞向一种类型而非另一种类型的谱系定向，强烈受到抗原识别时的炎症环境影响。用低密度脂蛋白（LDL）或其氧化衍生物（ox-LDL）对动脉粥样硬化易感小鼠进行免疫接种已知具有抗动脉粥样硬化作用。然而，疫苗接种诱导的 T 细胞的抗原特异性和保护机制尚不清楚。
使用 I-Ab 预测模型鉴定了来自鼠 ApoB-100 的两个肽片段（ApoB3501-3516 和 ApoB978-993），并确定了它们与 I-Ab 的结合。利用基于完全和不完全弗氏佐剂（CFA 和 IFA）的疫苗接种方案[1×CFA+4×IFA]，我们用 CFA 乳化 ApoB3501-3516 或 ApoB978-993 对 Apoe(-/-) 小鼠进行一次免疫接种，随后在 15 周内通过 IFA 进行四次加强免疫。收获脾脏、淋巴结和主动脉，并通过流式细胞术和实时 RT-PCR 进行评估。通过主动脉钉扎和主动脉根部组织学确定总动脉粥样硬化斑块负担。
与仅用佐剂对照的小鼠相比，用 ApoB3501-3516 或 ApoB978-993 免疫的小鼠的总斑块负担减少了 40%。用 ApoB3501-3516 免疫的小鼠的主动脉根部冷冻切片显示主动脉窦斑块发育减少了>60%。用 ApoB3501-3516 和 ApoB978-993 免疫的小鼠的主动脉均含有明显更多的 IL-10 mRNA。用 ApoB3501-3516 或 ApoB978-993 免疫的小鼠的 ApoB3501-3516 和 ApoB978-993 特异性 IgG1 和 IgG2c 滴度均升高，表明免疫后辅助性 T 细胞免疫活性。
我们的数据表明，MHC II 类限制的 ApoB-100 肽可能具有抗动脉粥样硬化作用，可能通过升高的 IL-10 机制。
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