Areca nut extracts increased expression of inflammatory cytokines, tumor necrosis factor‐α, interleukin‐1β, interleukin‐6 and interleukin‐8, in peripheral blood mononuclear cells

Abstract

Cytokines represent a central role in inflammatory tissue destruction and regulate the immune responses that may govern the progression of periodontal diseases. This study investigated the effects of areca nut extracts on the expression of inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-8 in peripheral blood mononuclear cells. The role of oxidative stress of areca nut extracts was also examined using curcumin. The expression of cytokines in peripheral blood mononuclear cells treated with extracts of ripe areca nut or extracts of tender areca nut was analyzed using enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction. Both extracts of ripe areca nut (< or = 40 microg/mL) and extracts of tender areca nut significantly enhanced the production of tumor necrosis factor-alpha and interleukin-1beta in peripheral blood mononuclear cells in a dose-dependent and time-dependent manner. The kinetics of mRNA expression of both cytokines was also enhanced by areca nut extracts. The stimulatory effects of areca nut extracts on the secretion of tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-8 and on the mRNA expression of tumor necrosis factor-alpha, interleukin-1beta and interleukin-6 at 4 h of incubation were reduced by curcumin (20-50 microm). However, the level of interleukin-8 transcripts was not affected by curcumin. Moreover, interleukin-1beta induction by extracts of tender areca nut, but not by extracts of ripe areca nut, was weakened by 10 microm curcumin. The inhibitory effects of curcumin may vary with different cytokines and with different areca nut extract treatments. The complex cytokine profile induced by areca nut extracts-treated peripheral blood mononuclear cells implied the possibility of enhanced local inflammation and altered immune functions by the areca chewing habit. The inhibitory effects of curcumin on cytokine expression suggested that oxidative stress might be involved in areca nut extracts-associated immune alteration.