High Doses of In vitro Beta-carotene, Alpha-Tocopherol and Ascorbic Acid Induce Oxidative Stress and Secretion of IL-6 in Peripheral Blood Mononuclear Cells from Healthy Donors

Barbara      Fonseca de Oliveira; Clara      Araujo Veloso; Jose      Augusto Nogueira-Machado; Miriam      Martins Chaves

Abstract

Background: Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species (ROS) and a biological system's ability to readily detoxify the reactive intermediates or repair the resulting damage. Our objective was to verify the existence of an in vitro dual effect of alpha-tocopherol, beta-carotene and ascorbic acid in peripheral blood mononuclear cells (PBMNC) of healthy donors and the inflammatory capacity by IL-6 production.

Methods: PBMNC were incubated with two concentrations of vitamin complex: [A] = Ascorbic Acid = 0.08μM, α- tocopherol = 0.04μM, β-carotene = 0.0008 μM and [20A] = Ascorbic Acid = 1.6μM, α-tocopherol = 0.82μM, β-carotene = 0.016μM. Oxidizing and reducing response were measured by chemiluminescence and MTT assays, respectively. IL-6 production was measured by sandwich ELISA.

Results: Ours results demonstrated that PBMNC (from 20-39-year-old donors) incubated with vitamins activated free radical production only in [20A] concentration. However, in the age groups of 40-59 and 60-80 years old, there was a significant reduction and activation of the oxidizing response with both concentrations, respectively. The inflammatory profile showed an elevation of IL-6 production in pro-oxidant and a decrease in antioxidant conditions. Correlation between ROS production and IL-6 releasing was observed.

Conclusions: With this experiment we concluded that vitamins can exert an antioxidant effect and a pro-oxidant effect according to their concentration, and could be an inductor of an inflammatory process in vitro generating severe complications to the body in cellular levels.

Keywords: Free radicals, immune system, interleukins, in vitro, oxidative stress, vitamins, pro-oxidant, inflammatory