Effects of 7,8-dihydro-8-oxo-deoxyguanosine on antigen challenge in ovalbumin-sensitized mice may be mediated by suppression of Rac

J. Y. Ro, D. Y. Kim, S. H. Lee, J. W. Park, M. H. Chung

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Abstract

Background and purpose: Earlier we reported that 7,8-dihydro-8-oxo- deoxyguanosine (8-oxo-dG), an oxidatively modified guanine nucleoside, exerted anti-inflammatory activity through inactivation of the GTP binding protein, Rac. In the present study, the effects of 8-oxo-dG were investigated on responses to antigen challenge in sensitized mice, as Rac is also involved at several steps of the immune process including antigen-induced release of mediators from mast cells. Experimental approach: Mice were sensitized and challenged with ovalbumin without or with oral administration of 8-oxo-dG during the challenge. Effects of 8-oxo-dG were assessed by measuring lung function, cells and cytokines in broncho-alveolar lavage fluid (BALF) and serum levels of antigen-specific IgE. Rac activity in BALF cells was also measured. Key results: 8-oxo-dG inhibited the increased airway resistance and decreased lung compliance of sensitized and challenged mice to the levels of non-sensitized control mice and lowered the increased leukocytes particularly, eosinophils, in BALF. Furthermore, 8-oxo-dG suppressed allergy-associated immune responses, such as raised anti- ovalbumin IgE antibody in serum, increased expression of CD40 and CD40 ligand in lung, increased interleukin-4, -5, -13, interferon-γ and tumour necrosis factor-α in BALF and mRNA levels of these cytokines in BALF cells, dose-dependently. The corresponding purine, 8-oxo-guanine, showed no effects in the same experiments. Finally, 8-oxo-dG, but not 8-oxo-guanine, inhibited the increased Rac activity in sensitized and challenged mice. Conclusion and implications: 8-Oxo-dG had anti-allergic actions that might be mediated by Rac inactivation. This compound merits further evaluation of its therapeutic potential in allergic asthma.

Original languageEnglish
Pages (from-to)1743-1752
Number of pages10
JournalBritish Journal of Pharmacology
Volume158
Issue number7
DOIs
Publication statusPublished - 2009 Dec 1

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All Science Journal Classification (ASJC) codes

  • Pharmacology

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