Ultraviolet radiation-induced cytokines promote mast cell accumulation and matrix metalloproteinase production: potential role in cutaneous lupus erythematosus

Objective: To examine the role of mast cells (MCs), cytokines, and matrix metalloproteinases (MMPs) following ultraviolet B (UVB) radiation in cutaneous lupus erythematosus (CLE). Methods: Immunohistochemistry was used to determine the presence of MCs and the expression of MMP-1, MMP-9, interleukin (IL)-15, and CCL5/RANTES in skin from patients with CLE. Human keratinocytes were exposed to varying doses of UVB and supernatants were collected and assessed for IL-15, CCL5, MMP-1, and MMP-9 by protein assays. MC migration was determined against supernatants from UVB-treated keratinocytes. Results: MCs in the skin of patients with CLE were significantly increased. MMP-1 and MMP-9 expression was abundant in these lesions. Intense reactivity for IL-15 and CCL5 was found in skin, particularly in epidermal keratinocytes, from patients with CLE. UVB irradiation induced IL-15, CCL5, MMP-1, and MMP-9 production from keratinocytes in a dose-and time-dependent manner. Supernatants obtained from UVB-treated keratinocytes induced MC migration, which was attenuated by anti-IL-15 and anti-CCL5 neutralizing antibodies. IL-15 induced MC-derived MMP production. Conclusions: Our results indicate that MCs and MMPs may play a role in the skin inflammation in CLE. MC recruitment as well as MMP production may be perpetuated by UV irradiation through locally released mediators.