PubMed2001
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/cm2 and peak at 12 to 18 h post stimulation with UVB 30 mJ/cm2, 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.