Keratinocytes not only play a role in maintaining physical barrier function against infection and injury but also are actively involved in skin immune responses through production of various cytokines. Retinoids, vitamin A and its natural and synthetic derivatives, regulate the proliferation and differentiation of keratinocytes and have immunomodulatory properties.
In addition, topical retinoic acid (RA) also has inhibitory effect on ultraviolet light induced collagenase production from fibroblasts. RA are used commonly for the treatment of skin diseases such as acne and photoaging, but the usage is restricted because RA frequently has induced irritant contact dermatitis. In this study, we hypothesized that RA induced irritant contact dermatitis is closely related to production of cytokines from keratinocytes. We performed real time quantitative polymerase chain reaction to measure mRNA expression pattern of cytokines, IL-1 a, TNF-a, IL-8, MCP-1, IL-10, after 6, 12, and 24 hours incubation of RA with concentration of 10-6M and 10-7M to transformed keratinocyte cell (HaCaT cell).
As a result, after 6 hours incubation of 10_6M RA, mRNA expression of IL-8 increased. After 12 hours incubation, IL-1 a, TNF- a, IL-8, and IL-10 mRNA increased. After 24 hours incubation, we observed that expression of IL-1 a, IL-8, MCP-1 and IL-10 mRNA increased. In the case of 10-7M RA, IL-8 mRNA expression increased after 6 hours of incubation. After 12 hours incubation, IL-1 a, IL-8 and IL-10 mRNA increased. After 24 hours incubation, IL-la, MCP-1 and IL-10 mRNA increased.
In conclusion, RA induced mRNA expression of pro-inflammatory cytokines and chemokines such as IL-1 a, TNF- a, IL-8, and MCP-1 in HaCaT cells. Therefore pro-inflammatory cytokines induced by RA from keratinocytes may play a role in RA induced irritant contact dermatitis. In addition, RA also induced mRNA expression of anti-inflammatory cytokine, IL-10, and IL-10 may play a role in suppression of contact dermatitis.