The overlapping between asthmatic subtypes, including both CD4+ T helper (TH)2 and TH17 cells, is found in the natural course of allergic asthma, especially in exacerbations and severe and insensitive forms to steroids, which are in need of new molecular therapies. In the TH2-subset mediated asthma, fenofibrate displays therapeutic promises, besides evidenced therapeutic effects on TH17-mediated colitis and myocarditis. Therefore, the effects of fenofibrate versus dexamethasone on IL-23/IL-17 axis in ovalbumin (OVA)/lipopolysaccharide (LPS)-induced airway inflammation and bronchial asthma in rats were explored. The OVA/LPS sensitization and challenge were performed for 28 days in male Wistar rats. After sensitization, fenofibrate (100 mg/kg/day) or dexamethasone (2.5 mg/kg/day) was orally administered from the day 15 to 28. Either fenofibrate or dexamethasone attenuated the severity of OVA/LPS-induced airway inflammation and bronchial asthma through significant ameliorations in the total serum immunoglobulin (Ig)E assay; the total and differential leukocytic counts in the bronchoalveolar lavage (BAL) fluid; the lung inflammatory cytokines such as interleukin (IL)-4, IL-13, IL-17, and IL-23, transforming growth factor (TGF)-β1, and tumor necrosis factor(TNF)-α levels; and the lung IL-17 and IL-23 expressions. In addition to the reduction in the inflammatory and fibrotic histopathological scores, fenofibrate significantly ameliorated the BAL neutrophilic count and the lung IL-17 and IL-23 expressions in comparison to dexamethasone. The suppression of IL-23/IL-17 axis could be considered a molecular therapeutic target for fenofibrate in OVA/LPS-induced airway inflammation and bronchial asthma. Combined therapeutic regimens of fenofibrate and steroids should be furtherly investigated in severe and resistant asthma.
Keywords: Dexamethasone; Fenofibrate; Interleukin-17; Interleukin-23; OVA/LPS-induced airway inflammation and bronchial asthma.