Enhancing Effects of Areca Nut Extracts on the Production of Interleukin‐6 and Interleukin‐8 by Peripheral Blood Mononuclear Cells

Abstract

The habit of chewing areca quid (AQ) has been implicated in oral pathogenesis, including periodontal disease. Little is understood about the roles of AQ in the cytokine secretion by immune cells. The study examined the effects of areca nut, the major ingredient of AQ, on the production of interleukin (IL)-6 and IL-8 by peripheral blood mononuclear cells (PBMC), the immunocompetent cells. The possible role of oxidative stress of areca nut was also examined. Extracts of ripe areca nut (rANE) and tender areca nut (tANE) were examined for their cytotoxic effects on human PBMC using the trypan blue exclusion test. The production of IL-6 and IL-8 by ANE-treated PBMC was analyzed using enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction. Effects of an antioxidant, pyrrolidine dithiocarbamate (PDTC), on ANE-induced cytokine secretion were also studied. At the experimental conditions, 20 micro g/ml rANE decreased cell viability significantly, whereas no significant effect of tANE (< or =80 micro g/ml) was observed. Both rANE (< or =20 micro g/ml) and tANE (< or =160 micro g/ml) significantly increased the secretion of IL-6 and IL-8 by PBMC in a dose- and time-dependent manner. The altered mRNA expression of IL-6 by rANE and tANE was also observed. Moreover, the stimulating effects of rANE on cytokine expression in PBMC could be attenuated by PDTC, suggesting that the oxidative stress of rANE may play a role. Markedly enhancing effects of ANE on PBMC-released inflammatory cytokines might cause a sustained cytokine-rich inflammatory milieu in oral cavity of AQ chewers. These excessive cytokines from ANE-treated immune cells may impair periodontal health.