Effects of areca nut extracts on the functions of human neutrophils in vitro

Abstract

Aqueous extracts of ripe areca nut without husk (ripe ANE) and fresh and tender areca nut with husk (tender ANE) were examined for their effects on the defensive functions of human neutrophils. Exposure of peripheral blood neutrophils to ripe ANE and tender ANE inhibited their bactericidal activity against oral pathogens, including Actinobacillus actinomycetemcomitans and Streptococcus mutans, in a dose-dependent manner. At the concentrations tested, ripe and tender ANEs did not significantly affect the viability of neutrophils as verified by their ability to exclude trypan blue dye. However, both ANEs inhibited the production of bactericidal superoxide anion by neutrophils as measured by cytochrome c reduction. Moreover, the ripe ANE inhibited neutrophils more effectively than did tender ANE. Arecoline, a major alkaloid of areca nut, only exhibited an inhibitory effect on the functions of neutrophils when high concentrations were used. Therefore, arecoline could not be used to explain the inhibitory effects observed for ANEs. In conclusion, our results demonstrated that ripe and tender ANEs reduced the antibacterial activity and the superoxide anion production of neutrophils. This effect may contribute to a less efficient elimination of bacteria from the periodontal environment. Inhibition of the antimicrobial functions of neutrophils may alter the microbial ecology of the oral cavity, and this may be one possible mechanism by which areca nut compromises the oral health of users of areca nut products.

Effects of Areca Nut Extracts on Phagocytosis of Actinobacillus actinomycete mcomitans ATCC 33384 by Neutrophils in Patients with Chronic Periondontitis

“…In both the groups, the phagocytic activity of neutrophils was reduced when they were treated with rANE as compared to tANE. This was consistent with the findings of another study which was done by Hung Sl et al, where they compared the neutrophil function which was obtained from peripheral blood which was treated with various concentrations of tANE, rANE, arecoline and catechin [12]. Another study showed that both rANE and tANE inhibited the phagocytic activity of neutrophils in a dose-dependent manner.…”

“…they produce toxins and other factors which either reduce neutrophil function or kill neutrophils [4]. However, it has been seen that the leukotoxicity of different strains of A.actinomycetemcomitans was not the main determinant that modified its interaction with human neutrophils, since phagocytosis and killing of the leukotoxic strains of A.actinomycetemcomitans could occur before the leukotoxin destroyed the neutrophils [12].…”

“…After exposure to different concentrations of rANE, tANE or catechin in healthy and chronic periodontitis groups, viable number of neutrophils was counted by Trypan blue exclusion assay [12]. The numbers of viable cells were counted by using a microscopic method and we found 84-85% cells remained viable after treatment in both the groups .The viability of the neutrophils did not differ significantly, both in intergroup and intragroup comparisons, thus suggesting that the integrity of the plasma membrane was not affected [Table/ Fig-1].…”

“…Treated and control neutrophils were incubated with Trypan blue solution for 3-5 minutes and they were counted on a haemocytometer [12]. The final preparation was studied under a Binocular bright field microscope at 400X magnification.…”

“…Then, from this, smears were made and they were fixed with methanol. They were then stained with Giemsa stain and the microscopically phagocytosed bacteria were counted [12].…”