Naturally occurring polyphenolic antioxidants modulate IgE-mediated mast cell activation

Reactive oxygen species (ROS) are known to modulate activities of a host of kinases, phosphatases and transcription factors. Rutin and chlorogenic aci d (CGA) are the major polyphenolic antioxidants present in the small molecu lar fraction of smokeless tobacco leaf extracts, as ascertained by reverse- phase high-pressure liquid chromatography (HPLC) and mass spectrometry. Lev els of intracellular ROS in resting versus antigen-immunoglobulin E (IgE)-c hallenged murine mast cells were measured at 510 nm by fluorescence-activat ed cell sorting (FACS) using carboxy-dichlorofluorescein (DCFH-DA). Enhance d ROS production was observed in IgE-sensitized mast cells following antige nic challenge. Rutin and CGA reduced ROS levels in antigen-IgE-activated ma st cells. Concomitantly, they also profoundly inhibited histamine release b y these activated mast cells. In contrast, rutin and CGA augmented the indu cible cytokine messages, i.e. interleukin (IL)-10, IL-13, interferon-gamma (IFN-gamma), IL-6 and tumour necrosis factor-alpha. (TNF-alpha) in IgE-sens itized mast cells following antigen challenge. This study indicates that to bacco polyphenolic antioxidants that quench intracellular ROS, differential ly affect two effector functions of antigen-IgE-activated mast cells. This model system may be employed to determine the molecular target of polypheno ls. The potential role of these polyphenolic antioxidants on IgE-mediated a llergy in vivo depends on a balance of their differential effects on mast c ell activation.