Thuja orientalis reduces airway inflammation in ovalbumin-induced allergic asthma.

Thuja orientalis (TO) may be used as a herbal remedy for the treatment of numerous inflammatory diseases. In the present study, the effects of TO were evaluated on airway inflammation in ovalbumin (OVA)‑induced allergic asthma and RAW264.7 murine macrophage cells. The effects of TO on the production of proinflammatory mediators, were determined in RAW264.7 cells that had been stimulated with lipopolysaccharide (LPS). Furthermore, an in vivo experiment was performed on mice that were sensitized to OVA and then received an OVA airway challenge. TO was administered by daily oral gavage at a dose of 30 mg/kg, 21‑23 days after the initial OVA sensitization. TO was shown to reduce nitric oxide production and reduce the relative mRNA expression levels of inducible nitric oxide synthase (iNOS), interleukin (IL)‑6, cyclooxygenase‑2, matrix metalloproteinase (MMP)‑9, and tumor necrosis factor‑α in RAW264.7 cells stimulated with LPS. In addition, TO markedly decreased the inflammatory cell counts in bronchial alveolar lavage fluid, reduced the levels of IL‑4, IL‑5, IL‑13, eotaxin and immunoglobulin E, and reduced airway hyperresponsivenes, in the OVA sensitized mice. Furthermore, TO attenuated airway inflammation and mucus hypersecretion, induced by the OVA challenge of the lung tissue. TO also reduced the expression of iNOS and MMP‑9 in lung tissue. In conclusion, TO exerted anti‑inflammatory effects in an OVA‑induced allergic asthma model, and in LPS‑stimulated RAW264.7 cells. These results suggest that TO may be a useful therapeutic agent for the treatment of inflammatory diseases, including allergic asthma.