Mizuashi Masato, Ohtani Tomoyuki, Nakagawa Satoshi, Aiba Setsuya
Department of Dermatology, Tohoku University School of Medicine, Aobaku, Sendai, Japan.
J Invest Dermatol. 2005 Mar;124(3):579-86. doi: 10.1111/j.0022-202X.2005.23624.x.
Although p38 mitogen-activated protein kinases (MAPK) play a crucial role in the activation of monocyte-derived dendritic cells (MoDC) by contact sensitizers, the upstream signals of p38 MAPK remain undetermined. To examine whether sensitizers induce redox or oxidative stress in dendritic cells (DC), which subsequently stimulate p38 MAPK, we measured the ratio of the oxidized (GSSG) versus reduced (GSH) form of cellular glutathione in MoDC stimulated with five sensitizers including NiCl2 and 2,4-dinitrochlorobenzene (DNCB) and three non-sensitizers including sodium dodecyl sulfate using colorimetric assays. All the sensitizers, but none of the non-sensitizers at sublethal concentration, reduced the GSH/GSSG ratio, which was accompanied by phosphorylation of p38 MAPK. Treatment with the antioxidant, N-acetyl-L-cysteine, which suppressed the reduction of the GSH/GSSG ratio, abrogated both the phosphorylation of p38 MAPK and the augmentation of CD86 expression. A similar response pattern was observed in THP-1 macrophage-monocyte cells. Unexpectedly, however, formaldehyde (HCHO) reduced the GSH/GSSG ratio in MoDC, but not in THP-1. This finding, in conjunction with the observation that DNCB and NiCl2 reduced the GSH/GSSG ratio at different kinetics, indicated that the sensitizers reduced the GSH/GSSG ratio by a different mechanism. These data suggest that the GSH/GSSG imbalance plays a crucial role in triggering DC maturation by sensitizers.
尽管p38丝裂原活化蛋白激酶（MAPK）在接触性致敏剂激活单核细胞衍生的树突状细胞（MoDC）过程中发挥关键作用，但其上游信号仍未明确。为了研究致敏剂是否会在树突状细胞（DC）中诱导氧化还原或氧化应激，进而刺激p38 MAPK，我们使用比色法测定了用包括氯化镍和2,4 -二硝基氯苯（DNCB）在内的五种致敏剂以及包括十二烷基硫酸钠在内的三种非致敏剂刺激的MoDC中细胞谷胱甘肽氧化型（GSSG）与还原型（GSH）的比例。所有致敏剂在亚致死浓度下均可降低GSH/GSSG比例，同时伴有p38 MAPK的磷酸化，而所有非致敏剂均无此作用。用抗氧化剂N -乙酰半胱氨酸处理可抑制GSH/GSSG比例的降低，同时消除p38 MAPK的磷酸化及CD86表达的增加。在THP - 1巨噬细胞 - 单核细胞中也观察到类似的反应模式。然而，出乎意料的是，甲醛（HCHO）可降低MoDC中的GSH/GSSG比例，但在THP - 1中却不能。这一发现，结合DNCB和NiCl2以不同动力学降低GSH/GSSG比例的观察结果，表明致敏剂通过不同机制降低GSH/GSSG比例。这些数据表明，GSH/GSSG失衡在致敏剂触发DC成熟过程中起关键作用。
