Adotevi Olivier, Vingert Benoit, Freyburger Ludovic, Shrikant Protul, Lone Yu-Chun, Quintin-Colonna Françoise, Haicheur Nacilla, Amessou Mohamed, Herbelin André, Langlade-Demoyen Pierre, Fridman Wolf H, Lemonnier François, Johannes Ludger, Tartour Eric
Equipe d'accueil 4054 Université Paris-Descartes, Ecole Nationale Vétérinaire d'Alfort, Paris, France.
J Immunol. 2007 Sep 1;179(5):3371-9. doi: 10.4049/jimmunol.179.5.3371.
The nontoxic B subunit of Shiga toxin (STxB) targets in vivo Ag to dendritic cells that preferentially express the glycolipid Gb(3) receptor. After administration of STxB chemically coupled to OVA (STxB-OVA) or E7, a polypeptide derived from HPV, in mice, we showed that the addition of alpha-galactosylceramide (alpha-GalCer) resulted in a dramatic improvement of the STxB Ag delivery system, as reflected by the more powerful and longer lasting CD8(+) T cell response observed even at very low dose of immunogen (50 ng). This synergy was not found with other adjuvants (CpG, poly(I:C), IFN-alpha) also known to promote dendritic cell maturation. With respect to the possible mechanism explaining this synergy, mice immunized with alpha-GalCer presented in vivo the OVA(257-264)/K(b) complex more significantly and for longer period than mice vaccinated with STxB alone or mixed with other adjuvants. To test whether this vaccine could break tolerance against self Ag, OVA transgenic mice were immunized with STxB-OVA alone or mixed with alpha-GalCer. Although no CTL induction was observed after immunization of OVA transgenic mice with STxB-OVA, tetramer assay clearly detected specific anti-OVA CD8(+) T cells in 8 of 11 mice immunized with STxB-OVA combined with alpha-GalCer. In addition, vaccination with STxB-OVA and alpha-GalCer conferred strong protection against a challenge with vaccinia virus encoding OVA with virus titers in the ovaries reduced by 5 log compared with nonimmunized mice. STxB combined with alpha-GalCer therefore appears as a promising vaccine strategy to more successfully establish protective CD8(+) T cell memory against intracellular pathogens and tumors.
志贺毒素（STxB）的无毒B亚基在体内将抗原靶向递送至优先表达糖脂Gb(3)受体的树突状细胞。在给小鼠注射化学偶联OVA（STxB-OVA）或源自人乳头瘤病毒的多肽E7的STxB后，我们发现添加α-半乳糖神经酰胺（α-GalCer）可显著改善STxB抗原递送系统，即使在非常低剂量的免疫原（50 ng）下，也能观察到更强大且持久的CD8(+) T细胞反应。其他已知可促进树突状细胞成熟的佐剂（CpG、聚肌苷酸胞苷酸、干扰素-α）未发现这种协同作用。关于解释这种协同作用的可能机制，与单独接种STxB或与其他佐剂混合接种的小鼠相比，接种α-GalCer的小鼠在体内更显著且更长时间地呈现OVA(257-264)/K(b)复合物。为了测试这种疫苗是否能打破对自身抗原的耐受性，用单独的STxB-OVA或与α-GalCer混合的STxB-OVA对OVA转基因小鼠进行免疫。尽管用STxB-OVA免疫OVA转基因小鼠后未观察到CTL诱导，但四聚体分析在11只接种STxB-OVA与α-GalCer组合的小鼠中有8只清楚地检测到了特异性抗OVA CD8(+) T细胞。此外，用STxB-OVA和α-GalCer进行疫苗接种可提供强大的保护，抵抗携带OVA的痘苗病毒攻击，与未免疫的小鼠相比，卵巢中的病毒滴度降低了5个对数。因此，STxB与α-GalCer联合使用似乎是一种很有前景的疫苗策略，可更成功地建立针对细胞内病原体和肿瘤的保护性CD8(+) T细胞记忆。
