Effects of an anthraquinone derivative from Rheum officinale Baill, emodin, on airway responses in a murine model of asthma

Emodin is a component from traditional Chinese herbal medicines. We focused on investigating whether emodin possesses distinct anti-inflammatory activity on a non-infectious mouse model of asthma, and we aimed to elucidate its involvement with the NF-kappa B pathway. BALB/c mice that were sensitized and challenged to ovalbumin were treated with emodin (40 mg/kg) 1 h before they were challenged with OVA. Our study demonstrated that emodin inhibited OVA-induced increases in eosinophil count; interleukin (IL)-4. IL-5, and IL-13 levels were recovered in bronchoalveolar lavage fluid and reduced serum levels of OVA-specific IgE, IgG, and IgG1. Histological studies demonstrated that emodin substantially inhibited OVA-induced eosinophilia in lung tissue and mucus hyper-secretion by goblet cells in the airway. Furthermore, pretreatment with emodin resulted in a significant reduction in mRNA expression of acidic mammalian chitinase (AMCase), chitinase 3-like protein 4 (Ym2) and Muc5ac in lung tissues and airway hyperresponsiveness to methacholine. These findings suggest that emodin may effectively delay the progression of airway inflammation and could be used as a therapy for patients with allergic airway inflammation. (C) 2012 Elsevier Ltd. All rights reserved.