title: High dose dietary pyridoxine induces T-helper type 1 polarization and decreases contact hypersensitivity response to fluorescein isothiocyanate in mice.
abstract: Pyridoxine (vitamin B(6)) is commonly used as a dietary supplement and beneficial effects of it are expected. However, excess ingestion of pyridoxine has been shown to cause a severe sensory neuropathy in humans and experimental animals. We have been studying the linkage between the nervous and immune systems using a fluorescein isothiocyanate (FITC)-induced contact hypersensitivity (CHS) mouse model. We have found that activation of transient receptor potential ankyrin 1 (TRPA1), which is expressed on sensory neurons, enhances skin sensitization to FITC. Another feature of FITC-induced CHS is its dependence on T helper 2 (Th2) type responses. We hypothesized that the excess intake of pyridoxine may affect sensitization to FITC and influence helper T-cell polarization. We examined FITC-induced CHS in BALB/c mice fed a diet containing excess pyridoxine (120 mg/kg diet) for 3 weeks. We found that mice fed on the excess-pyridoxine diet exhibited a lower response as to FITC-induced CHS compared with ones fed on a diet with a standard pyridoxine content (6.0 mg/kg diet). Moreover, the interferon (IFN)-γ/interleukin (IL)-4 ratio produced by draining lymph node cells was significantly higher with the excess-pyridoxine diet. This suggested that the cytokine balance was shifted toward Th1 with the excess-pyridoxine diet. Consistently, Th1-dependent oxazolone-induced CHS was enhanced with the excess-pyridoxine diet. These results suggested that an excess pyridoxine intake actively influences the immune system by altering helper T cell polarization.
authors.affiliation: Laboratory of Microbiology and Immunology and the Global COE Program, University of Shizuoka School of Pharmaceutical Sciences, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Kohta
authors.initials: K
authors.lastname: Kurohane
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Imai
mesh_terms: D000818:Animals; D016207:Cytokines / Q000276:immunology; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology; D003877:Dermatitis, Contact / Q000276:immunology*; D004032:Diet; D004195:Disease Models, Animal; D005260:Female; D016650:Fluorescein-5-isothiocyanate; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010081:Oxazolone; D011736:Pyridoxine / Q000494:pharmacology*; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology; D014803:Vitamin B Complex / Q000494:pharmacology*
chemical_list: D016207:Cytokines; D014803:Vitamin B Complex; D010081:Oxazolone; D016650:Fluorescein-5-isothiocyanate; D011736:Pyridoxine