Ascorbic acid, alpha-tocopherol, and beta-carotene reduce oxidative stress and proinflammatory cytokines in mononuclear cells of Alzheimer's disease patients

OBJECTIVES: The in vitro effect of a vitamin complex in generating and reducing oxidative species in peripheral blood mononuclear cells (PBMNC) and plasma of patients with Alzheimer's disease (AD) and healthy subjects (HS) was evaluated. METHODS: Two concentrations of a vitamin complex ([A] and [20A]) with ascorbic acid, alpha-tocopherol, and beta-carotene were incubated with either mononuclear cells or plasma. The generation of oxidizing species was measured in a luminol-dependent chemiluminescence assay and the reducing response by the MTT dye reduction assay. The levels of cytokines (interleukin [IL]-1β, IL-6, and IL-4) were measured by sandwich enzyme-linked immunosorbent assay. RESULTS: Our results demonstrated that the increase in the vitamin complex concentration reduced the reactive oxygen species (ROS) production and enhanced cellular reduction capacity in cells of AD patients in concentration [20A]. Plasma reduction capacity rose significantly for both groups (AD and HS). Concentration [A] did not alter the IL-1β production, increased IL-4 production in both groups and lowered IL-6 production in AD cells. Concentration [20A] increased pro-inflammatory cytokines (IL-1β and IL-6) and decreased IL-4 production by PBMNC of HS leading to a pro-inflammatory status. DISCUSSION: The antioxidant vitamin complex was effective in reducing oxidative stress in PBMNC of AD patients by lowering ROS production, improving cellular antioxidant capacities and modifying cytokine induced inflammation.