Expression of Human β-defensin-2 and IL-8 Following IL-1β Stimulation of Human Gingival Epithelial Cells in vitro

Abstract

Human β-defensin-2 (hBD-2) is one of the antimicrobial peptides produced by epithelial cells after stimulation by microorganisms and inflammatory mediators. Compared to Gram-positive bacteria, Gram-negative bacteria typically detected in the periodontal pockets in periodontitis elicit a stronger antibacterial peptide response of hBD-2. Differences between healthy subjects and those with periodontal disease in hBD-2 gene expression were recently reported, and hBD-2 gene expression in primary human gingival epithelial cells (HGEC) stimulated with Actinobacillus actinomycetemcomitans was described. We previously reported that expression of hBD-2 mRNA in HGEC was P. gingivalis-dependently induced according to stimulation time and was related to the initial stage of inflammatory responses after infection by pathogenic periodontal bacteria, ultimately with migration of neutrophils to infection sites. However, the role of hBD-2 is not at all clear because periodontal disease is not a chronic disease that repeatedly cycles between an advanced stage and suspended stage. We investigated the difference between the in vitro expression of hBD-2 and the production of IL-8 in HGEC in response to challenges with various concentrations of IL-1β, which is an inflammatory cytokine. mRNA expression of hBD-2 in HGEC stimulated under various conditions was assessed by the semi-quantitative reverse transcription-polymerase chain reaction, and culture supernatants from HGEC after stimulation under various conditions were analyzed quantitatively by enzyme-linked immunosorbant assay. Although the levels of hBD-2 mRNA and IL-8 production in HGEC stimulated with IL-1β tended to increase with exposure time, the levels were not significantly changed by variations in concentration. These findings suggest that the expression of hBD-2 and IL-8 was observed in IL-1β-stimulated HGEC regardless of the severity of the inflammation.