Arsenic trioxide, a potent inhibitor of NF-kappaB, abrogates allergen-induced airway hyperresponsiveness and inflammation.

BACKGROUND

Overactivation of nuclear factor kappaB (NF-kappaB) orchestrates airway eosinophilia, but does not dampen airway hyperresponsiveness in asthma. NF-kappaB repression by arsenic trioxide (As2O3) contributes to apoptosis of eosinophils (EOS) in airways. Here we provide evidence that As2O3 abrogates allergen (OVA)-induced airway eosinophilia by modulating the expression of IkappaBalpha, an NF-kappaB inhibitory protein, and decreases the airway hyperresponsiveness.

METHODS

Using a murine model of asthma, the airway hyperresponsiveness was conducted by barometric whole-body plethysmography. Airway eosinophilia, OVA-specific IgE in serum, and chemokine eotaxin and RANTES (regulated upon activation, normal T cell expressed and secreted) in bronchoalveolar lavage fluid were measured by lung histology, Diff-Quick staining, and ELISA. Chemokine-induced EOS chemotactic activity was evaluated using EOS chemotaxis assay. Electrophoretic mobility shift assay and Western blot analysis were performed to assess pulmonary NF-kappaB activation and IkappaBalpha expression, respectively.

RESULTS

As2O3 attenuated the allergen-induced serum IgE, chemokine expression of eotaxin and RANTES, and the EOS recruitment in bronchoalveolar lavage fluid, which is associated with an increased IkappaBalpha expression as well as a decreased NF-kappaB activation. Also, As2O3 suppressed the chemotaxis of EOS dose-dependently in vitro. Additionally, As2O3 significantly ameliorated the allergen-driven airway hyperresponsiveness, the cardinal feature underlying asthma.

CONCLUSION

These findings demonstrate an essential role of NF-kappaB in airway eosinophilia, and illustrate a potential dissociation between airway inflammation and hyperresponsiveness. As2O3 likely exerts its broad anti-inflammatory effects by suppression of NF-kappaB activation through augmentation of IkappaBalpha expression in asthma.