Expressions of β-defensins in human keratinocyte cell lines

Background: Defensins, a major family of antimicrobial peptides, are small cationic, cysteine-rich peptides with a wide range of antimicrobial activity. In human, beta -defensin-1 was isolated from urine and cervical mucous suggesting that this peptide plays an antimicrobial role in the genitourinary tract. beta -defensin-2 was identified in psoriatic scale produced by keratinocytes suggesting that this peptide contributes to defend the expansive surface of the integuments. Objective: Current research was done to investigate the expression and modulation of beta -defensin mRNA in human keratinocyte cell lines. Methods: HaCaT and A431 cell lines were used to all culture experiments. Cultured human keratinocytes were stimulated with ultraviolet (UV) B irradiation or tumor necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS) to determine whether defensin mRNA production occurred. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to amplify defesin cDNA from stimulated keratinocytes, and southern blots were used to verify the specificity of RT-PCR amplication products. Results: Expression of human beta -defensins was upregulated with UVB irradiation, TNF-alpha and LPS in HaCaT cells and in comparison to the control, significantly higher at 6 h post stimulation with UVB 100 mJ/cm(2) and peak at 12 to 18 h post stimulation with UVB 30 mJ/cm(2), TNF-alpha and LPS. A431 cells did not show expression of human beta -defensins in unstimulated state, even after irradiation with UVB or TNF-alpha or LPS. Conclusions: This report demonstrates the presence of defensin in human keratinocytes and capacity of human keratinocytes to produce defensin mRNA in response to UVB irradiation, TNF-alpha and LPS. Release of defensins by keratinocytes in response to cytokines elaborated in inflammation may contribute to the host defense responses. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.