Nukada Yuko, Miyazawa Masaaki, Kosaka Nanae, Ito Yuichi, Sakaguchi Hitoshi, Nishiyama Naohiro
Kao Corporation, Safety Science Research Laboratories, Tochigi, Japan.
J Toxicol Sci. 2008 May;33(2):175-85. doi: 10.2131/jts.33.175.
Contact allergens induce in vitro and in vivo the activation of dendritic cells (DC) and Langerhans cells (LC), which includes the up-regulation of surface marker expression (e.g. CD86, CD54) and cytokine production (e.g. TNF-alpha, IL-1beta, IL-8). The mitogen-activated protein kinase (MAPK) pathway also has a crucial role in this activation. However, the extent of MAPK involvement in the IL-8 production during DC/LC activation is not well understood. Earlier, we reported that contact allergens activated THP-1 cells, human monocytic cell line, like LC/DC in vitro. In this study, we further characterize the mechanism of IL-8 production using THP-1 cells as surrogate DCs. First, we evaluated the potential of 23 chemicals with different skin sensitization potencies to predominantly induce IL-8 production in vitro. Next we investigated the role of MAPK signaling and TNF-alpha, which is known to have autocrine effects on DC activation (e.g., IL-8 production). Inhibition of extracellular signal-regulated kinase (ERK), one of the MAPK pathways, suppressed the IL-8 production induced by both 2,4-dinitrochlorobenzene (DNCB) and nickel sulfate (NiSO(4)), and inhibition of p38 MAPK, a second MAPK pathway, significantly suppressed IL-8 production induced by only DNCB. Additionally, neutralization of TNF-alpha activity suppressed IL-8 production in THP-1 cells exposed to DNCB and NiSO(4). In conclusion, IL-8 production was predominantly induced in THP-1 cells following allergen stimulation, and MAPK pathways and TNF-alpha were involved in the IL-8 production induced by DNCB and NiSO(4). A better understanding of the mechanism of DC activation in vitro might lead to the clarification of the in vivo skin sensitization mechanism.
接触性变应原可在体外和体内诱导树突状细胞（DC）和朗格汉斯细胞（LC）活化，这包括表面标志物表达上调（如CD86、CD54）和细胞因子产生（如肿瘤坏死因子-α、白细胞介素-1β、白细胞介素-8）。丝裂原活化蛋白激酶（MAPK）途径在这种活化过程中也起着关键作用。然而，MAPK在DC/LC活化过程中对白细胞介素-8产生的参与程度尚不清楚。此前，我们报道接触性变应原在体外可像LC/DC一样活化人单核细胞系THP-1细胞。在本研究中，我们以THP-1细胞作为替代DC进一步表征白细胞介素-8产生的机制。首先，我们评估了23种具有不同皮肤致敏潜力的化学物质在体外主要诱导白细胞介素-8产生的可能性。接下来，我们研究了MAPK信号传导和肿瘤坏死因子-α的作用，已知肿瘤坏死因子-α对DC活化有自分泌作用（如白细胞介素-8产生）。抑制MAPK途径之一的细胞外信号调节激酶（ERK）可抑制2,4-二硝基氯苯（DNCB）和硫酸镍（NiSO₄）诱导的白细胞介素-8产生，而抑制另一条MAPK途径p38 MAPK仅显著抑制DNCB诱导的白细胞介素-8产生。此外，中和肿瘤坏死因子-α活性可抑制暴露于DNCB和NiSO₄的THP-1细胞中白细胞介素-8的产生。总之，变应原刺激后THP-1细胞中主要诱导白细胞介素-8产生，MAPK途径和肿瘤坏死因子-α参与了DNCB和NiSO₄诱导的白细胞介素-8产生。更好地理解体外DC活化机制可能有助于阐明体内皮肤致敏机制。
