Division of Inflammation Biology, La Jolla Institute for Allergy and Immunology, CA (T.K., K.K., H.W., K.T., J.M., M.V., D.W., C.R., M.O., K.L.).
Department of Microbiology, University of Minnesota Medical School, Minneapolis (T.D., M.K.J.).
Circulation. 2018 Sep 11;138(11):1130-1143. doi: 10.1161/CIRCULATIONAHA.117.031420.
CD4 T cells play an important role in atherosclerosis, but their antigen specificity is poorly understood. Immunization with apolipoprotein B (ApoB, core protein of low density lipoprotein) is known to be atheroprotective in animal models. Here, we report on a human APOB peptide, p18, that is sequence-identical in mouse ApoB and binds to both mouse and human major histocompatibility complex class II molecules.
We constructed p18 tetramers to detect human and mouse APOB-specific T cells and assayed their phenotype by flow cytometry including CD4 lineage transcription factors, intracellular cytokines, and T cell receptor activation. Apolipoprotein E-deficient ( Apoe) mice were vaccinated with p18 peptide or adjuvants alone, and atherosclerotic burden in the aorta was determined.
In human peripheral blood mononuclear cells from donors without cardiovascular disease, p18 specific CD4 T cells detected by a new human leukocyte antigen-antigen D related-p18 tetramers were mostly Foxp3 regulatory T cells (Tregs). Donors with subclinical cardiovascular disease as detected by carotid artery ultrasound had Tregs coexpressing retinoic acid-related orphan receptor gamma t or T-bet, which were both almost absent in donors without cardiovascular disease. In Apoe mice, immunization with p18 induced Tregs and reduced atherosclerotic lesions. After peptide restimulation, responding CD4 T cells identified by Nur77-GFP (green fluorescent protein) were highly enriched in Tregs. A new mouse I-A-p18 tetramer identified the expansion of p18-specific CD4 T cells on vaccination, which were enriched for interleukin-10-producing Tregs.
These findings show that APOB p18-specific CD4 T cells are mainly Tregs in healthy donors, but coexpress other CD4 lineage transcription factors in donors with subclinical cardiovascular disease. This study identifies ApoB peptide 18 as the first Treg epitope in human and mouse atherosclerosis.
CD4 T 细胞在动脉粥样硬化中发挥重要作用，但它们的抗原特异性尚不清楚。在动物模型中，用载脂蛋白 B（apoB，低密度脂蛋白的核心蛋白）免疫是一种抗动脉粥样硬化的方法。在这里，我们报告了一种人 APOB 肽 p18，它在小鼠 apoB 中序列相同，并且与小鼠和人主要组织相容性复合物 II 类分子结合。
我们构建了 p18 四聚体来检测人和小鼠的 APOB 特异性 T 细胞，并通过流式细胞术检测其表型，包括 CD4 谱系转录因子、细胞内细胞因子和 T 细胞受体激活。用 p18 肽或佐剂单独对载脂蛋白 E 缺陷（Apoe）小鼠进行疫苗接种，并确定主动脉中的动脉粥样硬化负担。
在无心血管疾病的供体外周血单核细胞中，通过新的人类白细胞抗原-抗原 D 相关-p18 四聚体检测到的 p18 特异性 CD4 T 细胞主要是 Foxp3 调节性 T 细胞（Tregs）。通过颈动脉超声检测到有亚临床心血管疾病的供体中，Tregs 共表达维甲酸相关孤儿受体γ t 或 T-bet，而在无心血管疾病的供体中几乎不存在。在 Apoe 小鼠中，p18 免疫诱导 Tregs 并减少动脉粥样硬化病变。在肽再刺激后，通过 Nur77-GFP（绿色荧光蛋白）鉴定的应答 CD4 T 细胞在 Tregs 中高度富集。一种新的小鼠 I-A-p18 四聚体鉴定了疫苗接种时 p18 特异性 CD4 T 细胞的扩增，其富含产生白细胞介素-10 的 Tregs。
这些发现表明，apoB p18 特异性 CD4 T 细胞在健康供体中主要是 Tregs，但在亚临床心血管疾病供体中共同表达其他 CD4 谱系转录因子。本研究鉴定了 apoB 肽 18 作为人类和小鼠动脉粥样硬化的第一个 Treg 表位。
