1. ^*Department of Dermatology, St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
2. ^†Department of Anatomy and Tumor Immunity Medical Research Center, Seoul National University College of Medicine, Seoul, Korea
3. ^‡School of Biological Sciences and Technology, Chonnam National University, Kwangju, Korea
4. ^§Laboratory of Immunology, Korea Research Institute of Bioscience and Biotechnology, Taejon, Korea
5. ^¶Department of Life Science, Sookmyung Women's University, Seoul, Korea

Correspondence: Dae Ho Cho, PhD, Department of Life Sciences, Sookmyung Women's University, Chungpa-Dong Z-Ka, Yongsan-Ku, Seoul, 140-742, Korea. Email: cdhkor@sookmyung.ac.kr

Received 24 June 2004; Revised 27 October 2004; Accepted 29 November 2004.

Abstract

It is generally accepted that corticotropin-releasing hormone (CRH) acts as the main coordinator of the central response to stress. Stress or an abnormal response to stressors has been found to modify the evolution of skin disorders, including psoriasis and atopic dermatitis. Nevertheless, the specific pathogenic role of stress remains unknown in skin diseases. Interleukin (IL)-18, a member of the IL-1 family, is a key mediator of peripheral inflammation and host defense responses, and is secreted by human keratinocytes. Here, we investigated the regulatory effect of CRH on expression of IL-18 in skin keratinocytes. Exposure of HaCaT cells to CRH resulted in a reduction of IL-18 mRNA transcripts and its production was in a concentration-dependent manner. In order to investigate whether the mitogen-activated protein kinase (MAPK) signaling pathway is involved in the downregulation of IL-18 production, cells were pre-treated with SB203580, an inhibitor of p38 MAPK, prior to the addition of CRH. This pre-treatment blocked the decrease in IL-18 production. In addition, CRH treatment induced rapid phosphorylation of p38 MAPK. SB203580 were able to inhibit CRH-induced p38 MAPK phosphorylation. CRH also inhibited production of IL-18 in human primary keratinocytes. These results suggest that CRH regulates IL-18 production through the MAPK signaling pathway in human keratinocytes.