Kimura Takayuki, Tse Kevin, McArdle Sara, Gerhardt Teresa, Miller Jacqueline, Mikulski Zbigniew, Sidney John, Sette Alessandro, Wolf Dennis, Ley Klaus
Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, La Jolla, California; and.
Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, California.
Am J Physiol Heart Circ Physiol. 2017 Apr 1;312(4):H781-H790. doi: 10.1152/ajpheart.00798.2016. Epub 2017 Jan 13.
Although immunization with major histocompatibility complex (MHC) class II-restricted apolipoprotein B (ApoB) peptides has been shown to be atheroprotective, the mechanism is unclear. Here, we investigated CD4 T cell populations in immunized atherosclerotic mice. Peptides (16-mers) from mouse ApoB, the core protein of low-density lipoprotein (LDL), were screened for binding to I-A by computer prediction and confirmed by radiolabeled peptide competition. Three new peptides, P101 (FGKQGFFPDSVNKALY, 5.5 nM IC), P102 (TLYALSHAVNSYFDVD, 6.8 nM), and P103 (LYYKEDKTSLSASAAS, 95 nM), were tested in an atherosclerosis model ( mice on Western diet). Immunization with each of the three peptides (1 time in complete Freund's adjuvant subcuntaneously and 4 time in incomplete Freund's adjuvant intraperitoneally) but not with adjuvant alone showed significantly reduced atherosclerotic plaques in the aortic root by serial sections and in the whole aorta by en face staining. There were no differences in body weight, LDL cholesterol, or triglycerides. Peritoneal leukocytes from ApoB peptide-immunized mice, but not control mice, secreted significant amounts of IL-10 (150 pg/ml). Flow cytometry showed that peptide immunization induced IL-10 in 10% of peritoneal CD4 T cells, some of which also expressed chemokine (C-C motif) receptor 5 (CCR5). Vaccination with ApoB peptides expanded peritoneal FoxP3 regulatory CD4 T cells and more than tripled the number of CCR5FoxP3 cells. Similar trends were also seen in the draining mediastinal lymph nodes but not in the nondraining inguinal lymph nodes. We conclude that vaccination with MHC class II-restricted autologous ApoB peptides induces regulatory T cells (Tregs) and IL-10, suggesting a plausible mechanism for atheroprotection. Vaccination against apolipoprotein B (ApoB), the protein of LDL, attracts attention as a novel approach to prevent atherosclerosis. We discovered major histocompatibility complex class II-restricted ApoB peptides, which reduce atherosclerosis and induce IL-10-producing CD4 T cells and chemokine (C-C motif) receptor 5 expression on regulatory T cells, suggesting that immunization with ApoB peptides inhibits atherosclerosis by inducing anti-inflammatory cytokines.
尽管用主要组织相容性复合体（MHC）II类限制性载脂蛋白B（ApoB）肽进行免疫已被证明具有抗动脉粥样硬化作用，但其机制尚不清楚。在此，我们研究了免疫的动脉粥样硬化小鼠中的CD4 T细胞群体。通过计算机预测筛选来自小鼠ApoB（低密度脂蛋白（LDL）的核心蛋白）的肽（16聚体）与I-A的结合，并通过放射性标记肽竞争进行确认。在动脉粥样硬化模型（西式饮食喂养的小鼠）中测试了三种新肽，P101（FGKQGFFPDSVNKALY，IC为5.5 nM）、P102（TLYALSHAVNSYFDVD，6.8 nM）和P103（LYYKEDKTSLSASAAS，95 nM）。用这三种肽中的每一种进行免疫（在完全弗氏佐剂中皮下注射1次，在不完全弗氏佐剂中腹腔注射4次），而不是单独用佐剂免疫，通过连续切片显示主动脉根部的动脉粥样硬化斑块显著减少，通过正面染色显示整个主动脉的斑块显著减少。体重、低密度脂蛋白胆固醇或甘油三酯没有差异。来自ApoB肽免疫小鼠而非对照小鼠的腹膜白细胞分泌大量IL-10（150 pg/ml）。流式细胞术显示，肽免疫在10%的腹膜CD4 T细胞中诱导IL-10，其中一些细胞还表达趋化因子（C-C基序）受体5（CCR5）。用ApoB肽接种疫苗可使腹膜FoxP3调节性CD4 T细胞扩增，CCR5+FoxP3细胞数量增加两倍多。在引流的纵隔淋巴结中也观察到类似趋势，但在非引流的腹股沟淋巴结中未观察到。我们得出结论，用MHC II类限制性自体ApoB肽接种疫苗可诱导调节性T细胞（Tregs）和IL-10，提示了一种可能的抗动脉粥样硬化机制。针对载脂蛋白B（ApoB）（LDL的蛋白质）的疫苗接种作为预防动脉粥样硬化的新方法引起了关注。我们发现了MHC II类限制性ApoB肽，其可减轻动脉粥样硬化并诱导产生IL-10的CD4 T细胞以及调节性T细胞上趋化因子（C-C基序）受体5的表达，提示用ApoB肽免疫通过诱导抗炎细胞因子来抑制动脉粥样硬化。
