Naringenin inhibits allergen-induced airway inflammation and airway responsiveness and inhibits NF-kappaB activity in a murine model of asthma.

Naringenin, a flavonoid, has antiinflammatory and immunomodulatory properties. We investigated whether naringenin could attenuate allergen-induced airway inflammation and its possible mechanism in a murine model of asthma. Mice were sensitized and challenged with ovalbumin. Some mice were administered with naringenin before ovalbumin challenge. We evaluated the development of airway inflammation and airway reactivity. Interleukin (IL)4, IL13, chemokine (C-C motif) ligand (CCL)5, and CCL11 in bronchoalveolar lavage fluid and serum total IgE were detected by ELISA. IkappaBalpha degradation and inducible nitric oxide synthase (iNOS) in lungs were measured by Western blot. We also tested NF-kappaB binding activity by electrophoretic mobility shift assay. The mRNA levels of iNOS, CCL5, and CCL11 were detected by real-time PCR. Naringenin attenuated ovalbumin-induced airway inflammation and airway reactivity in experimental mice. The naringenin-treated mice had lower levels of IL4 and IL13 in the bronchoalveolar lavage fluid and lower serum total IgE. Furthermore, naringenin inhibited pulmonary IkappaBalpha degradation and NF-kappaB DNA-binding activity. The levels of CCL5, CCL11, and iNOS were also significantly reduced. The results indicated that naringenin may play protective roles in the asthma process. The inhibition of NF-kappaB and the decreased expression of its target genes may account for this phenomenon.