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* Nutrition Department,
Division of Pulmonary and Critical Care Medicine, and
United States Department of Agriculture Western Human Nutrition Research Center, University of California, Davis, CA 95616
The Th1/Th2 paradigm has become an important issue in the pathogenesis of asthma, characterized by normal Th1 and elevated Th2 cytokine expression. Vitamin A deficiency (VAD) can produce a Th1 bias, whereas high-level dietary vitamin A can promote a Th2 bias. We used the OVA exposure mouse model to determine the contributions of vitamin A-deficient, control (4IU/g), and high-level vitamin A (250-IU/g) diets to the development of allergic airway inflammation and hyperresponsiveness. VAD reduced serum IgE and IgG1 responses, pulmonary eosinophilia, and the levels of IL-4 and IL-5 in bronchoalveolar lavage specimens, whereas the 250-IU/g diet increased serum IgE. Also, VAD blocked pulmonary hyperresponsiveness following methacholine challenge while the 250-IU/g diet exacerbated pulmonary hyperresponsiveness. In conclusion, VAD diminished and high-level dietary vitamin A enhanced the development of experimental asthma in this model system. These data suggest that excessive intake of vitamin A may increase the risk or severity of asthma in industrialized countries whereas vitamin A deficiency continues to increase mortality from infectious diseases in developing countries.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by National Institutes of Health Grants R01AI50863, K08HL076415, and United States Department of Agriculture Current Research Information System Project 5306-51530-006-00D.
2 Address correspondence and reprint requests to Dr. Gertrud U. Schuster, Nutrition Department, United States Department of Agriculture Western Human Nutrition Research Center, 430 West Health Science Drive, University of California, Davis, CA 95616. E-mail address: gschuster{at}ucdavis.edu
3 Abbreviations used in this paper: VAD, vitamin A deficiency; AHR, airway hyperresponsiveness; AIR, sham aerosol; BAL, bronchoalveolar lavage; Mch, methacholine.
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