OBJECTIVES: Cytokines induce the balance between inflammatory versus regulatory or antibody mediated reactions. So modulating the release of cytokines or inducing them by immunomodulating agents is an attractive mode for treating or help in treating several diseases such as autoimmune diseases. Eriobotrya japonica is a plant that is traditionally thought to have anti-inflammatory activities. Several compounds were isolated from the plant and showed distinctive biological effects. The purpose of this study was to determine the effects of epicatechin (EC) isolated from Eriobotrya Japonica on IL-6, IL-8, and IL-10 productions in whole blood stimulated with phytohemagglutinin (PHA)+lipopolysaccharide (LPS), and to examine if these cytokines are modulated through NFkappaB pathway.
METHODS: Sixteen healthy males and females volunteered in the study. Blood samples were drawn, diluted, and cultured for 24 h with different concentrations of EC and then PHA+LPS was added for another 24 h. The supernatant, then, was harvested and assayed for cytokines. In addition, mixing studies of EC and hydrocortisone were performed to examine the cytoplasmic and nuclear fractions of NFkB levels in association with cytokine production levels.
RESULTS: Increasing concentrations of EC (1-100 microg/ml) in PHA+LPS stimulated whole blood cells culture suppressed significantly (p<0.001) the production of IL-6 and IL-8. Moreover, increasing concentrations of EC modulated significantly the production of IL-10, as there was a significant increase in IL-10 level at 0.1, 1.0, and 10 microg/ml (p=0.058-0.004), while a significant decrease at a concentration of 100 microg/ml EC (p=0.037) was observed. In addition, an additive effect between EC and hydrocortisone (HC, 100 nmol/l) was seen in the production of IL-10, as there was a significant increase in IL-10 level (32%) compared with 27% for EC (10 microg/ml) and 19% HC. Furthermore, a significant decrease in cytoplasmic fractions of NFkappaB p65 level was found in samples containing EC 1, 10 microg/ml, but not in 100 microg/ml, when compared with control (p<0.03). These latter changes were accompanied with a 29%, 67%, and 98% increase, respectively, of NFkappaB p65 in nuclear fractions compared to 24% reduction of NFkappaB p65 level in HC culture (p<0.03).
CONCLUSIONS: These results indicate that EC suppresses the production of pro-inflammatory cytokines, IL6 and IL-8, enhances the production of anti-inflammatory cytokine, IL-10, and stimulates NFkappaB p65 translocation to nucleus in PHA+LPS stimulated whole blood culture.