Preventive and therapeutic anti-inflammatory properties of the sesquiterpene α-humulene in experimental airways allergic inflammation

Background and purpose: alpha-Humulene and trans-caryophyllene are plant sesquiterpenes with pronounced anti-inflammatory properties. Here, we evaluated the effects of these compounds in an experimental model of airways allergic inflammation. Experimental approach: Female BALB/c mice, sensitized to and challenged with ovalbumin received daily alpha-humulene or trans-caryophyllene (50 mg center dot kg-1, orally) or alpha-humulene (1 mg center dot mL-1, by aerosol) as either a preventive (for 22 days) or therapeutic (from the 18th to the 22nd day) treatment. Dexamethasone or budesonide was used as a positive control drug. Inflammation was determined on day 22 post-immunization by leukocyte recruitment, interleukin-5 (IL-5), CCL11, interferon-gamma (IFN-gamma) and leukotriene (LT)B-4 levels in bronchoalveolar lavage fluid (BALF). In addition, transcription factors [nuclear factor kappa B (NF-kappa B), activator protein 1 (AP-1)] and P-selectin in lung tissue were measured by immunohistochemistry and mucus secretion by histochemistry. Key results: Preventive or therapeutic treatments with alpha-humulene, but not with trans-caryophyllene, significantly reduced the eosinophil recruitment to the BALF. In addition, alpha-humulene recovery INF-gamma and reduced the IL-5, CCL11 and LTB4 levels in BALF, as well as the IL-5 production in mediastinal lymph nodes (in vitro assay). Furthermore, alpha-humulene decreased the NF-kB and the AP-1 activation, the expression of P-selectin and the increased mucus secretion in the lung. Conclusions and implications: alpha-Humulene, given either orally or by aerosol, exhibited marked anti-inflammatory properties in a murine model of airways allergic inflammation, an effect that seemed to be mediated via reduction of inflammatory mediators, adhesion molecule expression and transcription factors activation. This article is part of a themed issue on Mediators and Receptors in the Resolution of Inflammation. To view this issue visit http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009.