Identification of antigens presented by MHC for vaccines against tuberculosis
Identification of antigens presented by MHC for vaccines against tuberculosis
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DOI：
10.1038/s41541-019-0148-y
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发表时间：
2020-01-03
期刊：
影响因子：
9.2
通讯作者：
McShane, Helen
中科院分区：
文献类型：
--
作者：
Bettencourt, Paulo;Muller, Julius;McShane, Helen
结核分枝杆菌（M.tb）是全球死亡人数最多的病原体。唯一可用的疫苗是卡介苗，在世界各地的效力各不相同。迫切需要更有效的疫苗。针对结核病的免疫应答至少部分依赖于CD 4（+）T细胞。保护性疫苗需要通过感染的巨噬细胞中的MHC II类呈递的分枝杆菌肽诱导抗原特异性CD 4（+）T细胞。为了鉴定与MHC结合的分枝杆菌抗原，我们从BCG感染的THP-1巨噬细胞中免疫沉淀MHC I类和II类复合物，纯化MHC I类和MHC II类肽，并通过液相色谱串联质谱法对其进行分析。我们已经成功地确定了94 MHC-II和43 MHC-I，分别从76和41抗原提出的分枝杆菌肽。发现这些抗原在感染的巨噬细胞中高度表达。基因本体分析表明，这些抗原中的大多数与膜相关，并参与脂质的生物合成和运输。通过光谱匹配验证确认所选肽的序列，并通过IFN-γ ELISpot针对来自接种BCG的志愿者、结核分枝杆菌潜伏感染受试者或患有结核病的患者的外周血单核细胞评价免疫原性。三种抗原在病毒载体中表达，并在鼠气溶胶结核分枝杆菌攻击模型中单独或组合作为疫苗候选物进行评价。当组合递送时，与单独的BCG相比，三种候选疫苗在肺和脾中赋予显著的保护作用，证明了这种无偏倚的方法鉴定新候选抗原的概念验证。结核疫苗：免疫肽组学揭示潜在的疫苗抗原抗结核分枝杆菌的保护性疫苗结核分枝杆菌（M.tb），如卡介苗（BCG），触发对分枝杆菌肽特异性的强CD 4 T细胞应答，但它们的功效是可变的。Paulo Bettencourt及其同事现在通过主要相容性复合物（MHC）鉴定了一组由BCG感染的巨噬细胞呈递的分枝杆菌肽，并表明这些抗原中的三种可以结合起来配制疫苗，从而提高对小鼠Mtb感染的保护作用。在鉴定了94种MHC-II相关和43种MHC-I相关的分枝杆菌肽后，研究人员对BCG接种供体、潜伏性Mtb感染患者和结核病患者的外周血单核细胞进行了免疫原性测定，结果表明这些肽中的一组被免疫细胞识别，验证了它们作为新Mtb疫苗制剂可能成分的潜力。这些发现进一步支持了免疫肽组学用于鉴定有效疫苗替代品的新抗原的价值。
Mycobacterium tuberculosis (M.tb) is responsible for more deaths globally than any other pathogen. The only available vaccine, bacillus Calmette-Guerin (BCG), has variable efficacy throughout the world. A more effective vaccine is urgently needed. The immune response against tuberculosis relies, at least in part, on CD4(+) T cells. Protective vaccines require the induction of antigen-specific CD4(+) T cells via mycobacterial peptides presented by MHC class-II in infected macrophages. In order to identify mycobacterial antigens bound to MHC, we have immunoprecipitated MHC class-I and class-II complexes from THP-1 macrophages infected with BCG, purified MHC class-I and MHC class-II peptides and analysed them by liquid chromatography tandem mass spectrometry. We have successfully identified 94 mycobacterial peptides presented by MHC-II and 43 presented by MHC-I, from 76 and 41 antigens, respectively. These antigens were found to be highly expressed in infected macrophages. Gene ontology analysis suggests most of these antigens are associated with membranes and involved in lipid biosynthesis and transport. The sequences of selected peptides were confirmed by spectral match validation and immunogenicity evaluated by IFN-gamma ELISpot against peripheral blood mononuclear cell from volunteers vaccinated with BCG, M.tb latently infected subjects or patients with tuberculosis disease. Three antigens were expressed in viral vectors, and evaluated as vaccine candidates alone or in combination in a murine aerosol M.tb challenge model. When delivered in combination, the three candidate vaccines conferred significant protection in the lungs and spleen compared with BCG alone, demonstrating proof-of-concept for this unbiased approach to identifying new candidate antigens.Tuberculosis vaccines: immunopeptidomics uncovers potential vaccine antigens Protective vaccines against Mycobacterium tuberculosis (M.tb), such as bacillus Calmette-Guerin (BCG), trigger strong CD4 T-cell responses specific to mycobacterium peptides, but their efficacy is variable. Paulo Bettencourt and colleagues now identify a set of mycobacterium peptides presented by BCG-infected macrophages via major compatibility complexes (MHC), and show that three of these antigens can be combined to formulate a vaccine that confers improved protection to Mtb infection in mice. After identifying 94 MHC-II-associated and 43 MHC-I-associated mycobacterium peptides, the researchers performed immunogenicity assays with peripheral blood mononuclear cells from BCG-vaccinated donors, latent Mtb-infected patients and patients with tuberculosis, and show that a set of these peptides was recognised by the immune cells, validating their potential as possible components for new Mtb vaccine formulations. These findings further support the value of immunopeptidomics for the identification of new antigens for effective vaccine alternatives.