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, β-defensin-1 was isolated from urine and cervical mucous suggesting that this peptide plays an antimicrobial role in the genitourinary tract. β-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 β-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-α (TNF-α) 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 β-defensins was upregulated with UVB irradiation, TNF-α 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-α and LPS. A431 cells did not show expression of human β-defensins in unstimulated state, even after irradiation with UVB or TNF-α 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-α and LPS. Release of defensins by keratinocytes in response to cytokines elaborated in inflammation may contribute to the host defense responses.