Elucidation of the role of Vα14+NKT cells during infection with various microbial pathogens and application of medical treatment

本文研究了细菌感染时小鼠肝脏糖脂/CD1d反应性V-αL4~+T细胞的表型和功能变化。单核细胞增多性李斯特菌感染或IL-12处理后，在胸腺和胸腺切除早期，共表达NK1.1标志的α-半乳糖神经酰胺/CD1d四聚体反应性(α-GalCer/CD1d^+)T细胞消失，同时出现缺失NK1.1的细胞。NK1.1亚群的缺失阻止了α-GalCer/CD1d^+NK1.1^-T细胞的出现。在感染前，IL-4的产生是由NK1.1^+而不是NK1.1-，α-GalCer/CD1d^+T细胞负责的，而干扰素-γ是由细胞产生的，而与NK1.1或CD4的表达无关。感染后，在α-GalCer/CD1d^+T细胞中检测不到分泌IL-A的细胞，但在缺乏γ的NK1.1细胞中可检测到相当数量的分泌干扰素的细胞。因此，NK1.1的表面表达和…的功能活性在李斯特菌病的早期阶段，更多的VαL4^+T细胞经历了戏剧性的变化，并且这些变化以不依赖胸腺的方式进行。在缺乏α-GalCer/CD1d~+T细胞的突变小鼠中，李斯特菌病得到了改善，这表明NK1.1^-T细胞亚群对抗菌保护的微妙贡献被NK1.1^+T细胞亚群更深刻的有害影响所掩盖。在以后的时间点，NK1.1^-iNKT细胞群收缩，而NK1.1^+iNKT细胞重新出现。INKT细胞表面NK1.1表达的改变与肝脏中IL-12产生的数量变化相平行，并可被内源性IL-12中和完全阻止，而α-GalCer刺激后iNKT细胞表面NK1.1的改变并未被阻止。过继细胞转移实验显示，单核细胞增多性李斯特氏菌感染小鼠的肝脏NK1.1-iNKT细胞聚集在受体重组激活基因-1缺陷小鼠的肝脏中，并获得NK1.1表面表达，提示单核细胞增多性李斯特氏菌感染时肝脏iNKT细胞表面NK1.1表达是可逆的，TCR和IL-12刺激的机制不同。α-GalCer治疗显著抑制了单核细胞增多性李斯特氏菌感染后肝和脾中的细菌生长和炎症。经γ/δ-GalCer处理后，肝脏粒细胞和αT细胞的浸润加快，这些细胞的耗竭加剧了李斯特菌病。我们的结果表明，α-GalCer诱导了抗菌免疫，部分原因是炎症细胞加速渗入肝脏。较少

The phenotypic and functional changes of glycolipid/CD1d-reactive Vαl4^+ T cells in the liver of mice during bacterial infection were investigated. After Listeria monocytogenes infection or IL-12 treatment, α-galactosylceramide/CD1d tetramer-reactive (α-GalCer/CD1d^+) T cells coexpressing NK1.1 marker became undetectable and concomitantly cells lacking NK1.1 emerged in both euthymic and thymectomized animals at early stages of infection. Depletion of the NK1.1 subpopulation prevented the emergence of α-GalCer/CD1d^+ NK1.1^- T cells. Before infection, NK1.1^+, rather than NK1.1^-, α-GalCer/CD1d^+ T cells coexpressing CD4 were responsible for IL-4 production, whereas IFN-γ was produced by cells regardless of NK1.1 or CD4 expression. After infection, IL-A-secreting cells became undetectable among α-GalCer/CD1d^+ T cells, but considerable numbers of IFN-γ-secreting cells were found among NK1.1, but not NK1.1^+, cells lacking CD4. Thus, NK1.1 surface expression and functional activities of … More Vαl4^+ T cells underwent dramatic changes at early stages of listeriosis and these alterations progressed in a thymus-independent manner. In mutant mice lacking all α-GalCer/CD1d~^+T cells, listeriosis was ameliorated, suggesting that subtle contribution of the NK1.1^-T-cell subset to antibacterial protection is covered by more profound detrimental effects of the NK1.1^+T-cell subset. At later time points, the NK1.1^- iNKT cell population contracted, whereas NK1.1^+ iNKT cells reemerged. Alterations in NK1.1 surface expression of iNKT cells were paralleled by numerical changes of IL-12 producers in the liver and were completely prevented by endogenous IL-12 neutralization, whereas NK1.1 surface alterations on iNKT cells following α-GalCer stimulation were not prevented. Adoptive cell transfer experiments revealed that the liver NK1.1^- iNKT cells from L.monocytogenes-infected mice accumulated in the liver of recipient recombination-activating gene-1-deficient mice where they acquired NK1.1 surface expression, suggesting that NK1.1 surface expression on liver iNKT cells is reversible during L.monocytogenes infection, and that different mechanisms underlie stimulation by TCR and IL-12. Bacterial growth and inflammation in the liver and spleen following Listeria monocytogenes infection were dramatically inhibited by α-GalCer treatment. Liver infiltration of granulocytes and γ/δ T cells was accelerated by α-GalCer treatment, and depletion of these cells exacerbated listeriosis. Our results indicate that α-GalCer induces antibacterial immunity caused, in part, by accelerated infiltration of inflammatory cells into the liver. Less