Cell and Molecular Biology Branch, US Army Medical Research Institute of Chemical Defense, 3100 Ricketts Point Road, Aberdeen Proving Ground, 21010 MD, United States.
Toxicol In Vitro. 2013 Oct;27(7):2067-75. doi: 10.1016/j.tiv.2013.07.002. Epub 2013 Jul 10.
Uncontrolled inflammation contributes to cutaneous damage following exposure to the warfare agent bis(2-chloroethyl) sulfide (sulfur mustard, SM). Activation of the p38 mitogen activated protein kinase (MAPK) precedes SM-induced cytokine secretion in normal human epidermal keratinocytes (NHEKs). This study examined the role of p38-regulated MAPK activated kinase 2 (MK2) during this process. Time course analysis studies using NHEK cells exposed to 200μM SM demonstrated rapid MK2 activation via phosphorylation that occurred within 15 min. p38 activation was necessary for MK2 phosphorylation as determined by studies using the p38 inhibitor SB203580. To compare the role of p38 and MK2 during SM-induced cytokine secretion, small interfering RNA (siRNA) targeting these proteins was utilized. TNF-α, IL-1β, IL-6 and IL-8 secretion was evaluated 24h postexposure, while mRNA changes were quantified after 8h. TNF-α, IL-6 and IL-8 up regulation at the protein and mRNA level was observed following SM exposure. IL-1β secretion was also elevated despite unchanged mRNA levels. p38 knockdown reduced SM-induced secretion of all the cytokines examined, whereas significant reduction in SM-induced cytokine secretion was only observed with TNF-α and IL-6 following MK2 knockdown. Our observations demonstrate potential activation of other p38 targets in addition to MK2 during SM-induced cytokine secretion.
未受控制的炎症会导致接触到二（氯乙基）硫醚（硫芥，SM）等战剂后皮肤受损。在正常的人类表皮角质形成细胞（NHEK）中，p38 丝裂原激活蛋白激酶（MAPK）的激活先于 SM 诱导的细胞因子分泌。本研究检查了 p38 调节的 MAPK 激活激酶 2（MK2）在此过程中的作用。用 200μM SM 暴露的 NHEK 细胞进行的时间进程分析研究表明，MK2 通过在 15 分钟内发生的磷酸化而迅速激活。p38 激活是 MK2 磷酸化所必需的，这是通过使用 p38 抑制剂 SB203580 进行的研究确定的。为了比较 p38 和 MK2 在 SM 诱导的细胞因子分泌中的作用，使用针对这些蛋白的小干扰 RNA（siRNA）进行了研究。在暴露后 24 小时评估 TNF-α、IL-1β、IL-6 和 IL-8 的分泌，而在 8 小时后定量 mRNA 变化。SM 暴露后观察到 TNF-α、IL-6 和 IL-8 在蛋白和 mRNA 水平上调，尽管 IL-1β 的 mRNA 水平不变。p38 敲低减少了所有受检查细胞因子的 SM 诱导分泌，而仅在 MK2 敲低后观察到 TNF-α 和 IL-6 的 SM 诱导细胞因子分泌显著减少。我们的观察结果表明，在 SM 诱导的细胞因子分泌中，除了 MK2 之外，还可能激活其他 p38 靶标。
