Human keratinocytes express fractalkine/CX3CL1

Abstract

Background: fractalkine/CX3CL1 is a unique chemokine that has properties of both chemoattractants and adhesion molecules. The major source of this chemokine in the skin is still controversial.

Objective: studies were undertaken to determine the expression of fractalkine in human skin.

Methods: RT-PCR, Western blotting, and immunostaining were performed with normal human epidermal keratinocytes (NHEK) and HaCaT cells, human keratinocyte cell line, for the presence of fractalkine. Biopsy specimens of normal and diseased skin were also investigated.

Results: we identified that NHEK and HaCaT cells expressed fractalkine mRNA and protein. The combination of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma upregulated their expression by NHEK. Immunohistochemistry demonstrated fractalkine expression in keratinocytes in lichen planus and psoriasis vulgaris. RT-PCR also showed that lesional skin of psoriatic patients expressed higher levels of fractalkine mRNA than non-lesional skin from the same patients.

Conclusion: these results suggests that keratinocytes strongly express fractalkine in lichen planus and psoriasis vulgaris and that the fractalkine-CXC3CR1 system in the diseased skin can be a target for the treatment.