Suppression of interleukin (IL)-8 and human beta defensin-2 secretion in LPS-and/or IL-1β-stimulated airway epithelial A549 cells by a herbal formulation against respiratory infections (BNO 1030)

Abstract

A special ethanolic-aqueous extract from seven traditional medicinal plants (BNO 1030) has been used for several decades to treat recurrent infections of the respiratory tract. Considering the potential role of interleukin-8 (IL-8) and human beta defensin-2 (hBD-2) in inflammation, we investigated the effect of BNO 1030 on lipopolysaccharide (LPS) from Pseudomonas aeruginosa or IL-1β-induced inflammatory mediators in A549 human type II alveolar epithelial cells. A549 cells were stimulated with LPS (100 μg/ml) or IL-1β (50 ng/ml) in the presence of the preparation and the secretion of IL-8 and hBD-2 were measured after 18 h and 24h in cell free supernatants using enzyme-linked immunosorbent assays (ELISA). Cell viability and cell growth was investigated by propidium iodide uptake and WST-1 assay, respectively. BNO 1030 inhibited the secretion of IL-8 and hBD-2 at non-cytotoxic concentrations (0.1-100 μg/ml; cell growth inhibitory concentration, 50% (IC(50))=678 ± 87.6 μg/ml). Stimulation by IL-1β led to a 7-fold activation of IL-8 secretion, which was reduced by 37.7 ± 4.1% (p<0.05) after incubation with 100 μg/ml BNO 1030. Inducible hBD-2 was suppressed by 91.8 ± 15.6% (p<0.01) at the same concentration of BNO 1030 (IC(50)=0.7 ± 0.1 μg/ml). The 2-fold increase of IL-8 secretion by LPS-stimulated cells was completely abolished at concentration of 50 μg/ml BNO 1030 (IC(50)=5.7±3.6 μg/ml). BNO 1030 suppressed the secretion of IL-8 and hBD-2 in cultured epithelial A549 cells. These results support its use as a phytotherapeutic product prepared from traditional remedies in inflammatory diseases, especially those affecting the respiratory tract.