Cryptoporus volvatus polysaccharides attenuate LPS-induced expression of pro-inflammatory factors via the TLR2 signaling pathway in human alveolar epithelial cells.

ABSTRACT

CONTEXT Cryptoporus volvatus (Peck) Hubb grows wild in China, and its fruiting bodies have been used traditionally to treat asthma and bronchitis. OBJECTIVES: This study evaluates the anti-inflammatory effect of Cryptoporus polysaccharides (CP) extracted from fruiting bodies of C. volvatus on lipopolysaccharide (LPS)-induced pro-inflammatory factors and the signaling pathways involved in human alveolar epithelial cells. MATERIALS AND METHODS: To evaluate the effects of CP on LPS-induced pro-inflammatory factors, A549 cells were pre-incubated with CP 1, 10, and 100 µg/ml for 1 h and then stimulated with LPS 10 µg/ml for 24 h. The expression of pro-inflammatory factors monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), Toll-like receptor 2 (TLR2), and phosphorylation of ERK1/2, p38, and NF-κB p65 were measured by q-PCR, ELISA, and western blotting. RESULTS: CP decreased LPS-induced mRNA expression of MCP-1, TNF-α, and IL-1ß (IC50 = 83.3, 85.2, and 91.6 µg/ml, respectively) and their correspondent protein expression (IC50 = 88.6, 76.4, and 81.6 µg/ml, respectively). Investigation of potential mechanisms indicated that CP 100 µg/ml reduced LPS-induced expression of TLR2 mRNA (66.9%, p < 0.01) and protein (63.2%, p < 0.01) that was a result of the decreased pro-inflammatory factors. LPS induction increased the expression of TLR2 and the phosphorylation of p38 and ERK1/2, NF-kB p65 concomitantly. CP 100 µg/ml inhibited the LPS-induced phosphorylation of the signaling proteins (p < 0.05). CONCLUSIONS: This suggests that CP pretreatment down-regulates LPS-mediated inflammation in lung epithelial cells. This study further confirmed that CP is a potential anti-inflammatory drug for the treatment of airway inflammatory diseases.