Sireci Guido, La Manna Marco P, Di Sano Caterina, Di Liberto Diana, Porcelli Steven A, Kronenberg Mitch, Dieli Francesco, Salerno Alfredo
Dipartimento di Biopatologia e Metodologie Biomeeiche, Università di Palermo, Palermo, Italy.
J Leukoc Biol. 2007 Mar;81(3):607-22. doi: 10.1189/jlb.0506298. Epub 2006 Oct 17.
alpha-galactosylceramide, a natural killer T cell ligand, and its synthetic homolog, KRN7000, consistently influence IFN-gamma and TNF-alpha release, both mediators of LPS-induced shock. To modify the course of endotoxin shock, we injected KRN7000 at different time points of experimental systemic Shwartzman reaction. Mice treated with KRN7000 survived when it was injected within 2 h before and after LPS challenge. Mice survival was associated with low levels of T helper 1 (Th1) cytokines, such as IFN-gamma and TNF-alpha. By contrast, protection from endotoxin shock was associated with an increase of T helper 2 (Th2) cytokines, like IL-4 and IL-10. A role of Th2 cytokines in counteracting LPS-induced shock was supported by experiments in which the protection against Shwartzman reaction by KRN7000 was abrogated by in vivo coadministration of anti-Th2 cytokines antibodies. In addition, cytofluorimetric analysis showed that surviving animals have higher percentages of NKT-IL-10-positive cells and lower percentages of NKT-IFN-gamma and macrophages/TNF-alpha-stained cells than nonprotected mice. Taken together, our data demonstrate that KRN7000 treatment given at times near LPS challenge is protective for endotoxin shock inhibiting IFN-gamma and TNF-alpha release. Moreover, KRN7000-mediated protection occurs through an increased production of IL-4 and IL-10, which are mainly secreted by NKT cells. Since IFN-gamma release by NKT requires a longer TCR stimulation than that required for Th2 cytokines production, we demonstrate that timing of KRN7000 in vivo exposure affect the pattern of cytokines expression protecting animals by endotoxin shock.
α-半乳糖神经酰胺，一种自然杀伤T细胞配体，及其合成类似物KRN7000，持续影响干扰素-γ和肿瘤坏死因子-α的释放，这两种物质都是脂多糖诱导休克的介质。为了改变内毒素休克的病程，我们在实验性全身性施瓦茨曼反应的不同时间点注射KRN7000。在脂多糖攻击前2小时内及攻击后注射KRN7000的小鼠存活下来。小鼠存活与低水平的辅助性T细胞1（Th1）细胞因子有关，如干扰素-γ和肿瘤坏死因子-α。相比之下，免受内毒素休克与辅助性T细胞2（Th2）细胞因子的增加有关，如白细胞介素-4和白细胞介素-10。体内联合给予抗Th2细胞因子抗体可消除KRN7000对施瓦茨曼反应的保护作用，这一实验支持了Th2细胞因子在对抗脂多糖诱导休克中的作用。此外，细胞荧光分析显示，与未受保护的小鼠相比，存活动物中NKT-IL-10阳性细胞的百分比更高，而NKT-干扰素-γ和巨噬细胞/肿瘤坏死因子-α染色细胞的百分比更低。综上所述，我们的数据表明，在脂多糖攻击附近时间给予KRN7000治疗对内毒素休克具有保护作用，可抑制干扰素-γ和肿瘤坏死因子-α的释放。此外，KRN7000介导的保护作用是通过增加白细胞介素-4和白细胞介素-10的产生而实现的，这些细胞因子主要由NKT细胞分泌。由于NKT细胞释放干扰素-γ比产生Th2细胞因子需要更长时间的TCR刺激，我们证明了KRN7000体内暴露的时间会影响细胞因子表达模式，从而保护动物免受内毒素休克。
