Dietary exposure to benzoxazinoids enhances bacteria-induced monokine responses by peripheral blood mononuclear cells

SCOPE: To examine potentially immunomodulating effects of dietary benzoxazinoids (BXs), present in cereal grains.

METHODS AND RESULTS: Nineteen healthy volunteers were randomly distributed into two groups, who received diets with high or low content of BXs for three weeks. After a week's wash-out, the groups switched diets. Peripheral blood mononuclear cells (PBMCs) were stimulated with Porphyromonas gingivalis, Escherichia coli lipopolysaccharide (LPS), or tetanus toxoid (TT). PBMCs from a healthy donor received the same stimuli in presence of serum from each participant receiving BXs. The production of monokines, T-cell cytokines and T-helper cell proliferation were assessed. A three-week diet with high BX content enhanced IL-1β responses against LPS and P. gingivalis, as well as TNF-α response against P. gingivalis, after 24 hours of stimulation. Moreover, IL-6 was found to be increased after 7 days of stimulation with LPS. No effect was observed on T-cell cytokines or proliferation. BX levels in serum after a single meal did not modify cytokine responses.

CONCLUSIONS: High dietary intake of BXs enhances bacteria-induced production of pro-inflammatory monokines by PBMCs, but not T-cell responses; presumably due to intrinsic changes within PBMCs, built up over three weeks of BX-rich diet, rather than to immediate effects of BXs contained in serum. This article is protected by copyright. All rights reserved.