The role of ATP-stimulated three-dimensional normal human epidermal keratinocytes in skin inflammation revealed by DNA microarray analysis

Abstract

Adenosine 5′-triphosphate (ATP) release can be triggered by various environmental stimuli, including mechanical or chemical stress or microbial products. Several papers have already reported the effects of ATP on keratinocytes, e.g., cell growth, differentiation, terminal differentiation, and cell-to-cell communication and IL-6 production. In previous studies, we have identified genes whose expression is augmented in ATP-stimulated normal human epidermal keratinocytes (NHEK) by DNA microarray. The statistical analysis revealed that, beside IL-6, the expression of several novel genes such as IL-20, CXCL1, CXCL2, CXCL3 and ATF3 was significantly augmented in NHEK after ATP treatment. Since two cytokines, IL-6 and IL-20, that are well known to stimulate STAT3, were produced by ATP-stimulated NHEK, we examined phosphorylation of STAT3 in ATP-stimulated NHEK. However, these results are only basal epidermal layer, the function of extracellular ATP in the upper layer, which constitute the majority of the skin (stratum spinosum, stratum granulosum) is unclear. In this study, to further clarify the role of ATP-stimulated epidermis cells cultured three-dimensional keratinocytes in skin inflammation or immune response, we tried to identify genes whose expression is augmented in ATP-stimulated three-dimensional NHEK by DNA microarray. The statistical analysis revealed that the expression of several novel genes such as IL-24, PTGS2, AREG, EGR-4 and HBEGF, was significantly augmented in NHEK. By these studies, we characterized the role of ATP-stimulated three-dimensional NHEK in skin inflammation or immune response via these novel factors, and extracellular ATP plays an important role in the regulation of skin homeostasis and immune response was suggested.