Anti-asthmatic effects of volatile organic compounds from Chamaecyparis obtusa, Pinus densiflora, Pinus koraiensis, or Larix kaempferi wood panels.

Asthma is a common chronic inflammatory disease in which lung airways narrow and produce extra mucus. Numerous medications, such as steroids, are used to prevent or control asthmatic symptoms, but side effects are associated with those medications. There are reports of anti-inflammatory, antibacterial, and antiparasitic effects of terpene, a volatile organic compound (VOC) in conifers. VOCs easily enter a gaseous form, and wood products are good sources of VOCs. However, only a few studies have been conducted on the effect on asthma of VOCs emitted by wood. In this study, we examined the effects of VOCs diffused from wood panels on ovoalbumin (OVA)-induced asthma in a mouse model. The mice were intraperitoneally sensitized with 10 μg of OVA with aluminum hydroxide on days 0, 7, and 14. From day 21 to day 26, the mice were challenged with 2% OVA intranasally for 30 min. For VOC treatment, asthma model mice were placed in polyacrylamide chambers containing wood panels of Chamaecyparis obtusa, Pinus densiflora, Pinus koraiensis, or Larix kaempferi. On day 27, serum, lung tissue, and bronchoalveolar lavage fluids were prepared for H&E staining, qRT-PCR, ELISA, and Diff-Quik staining, as appropriate. OVA treatment induced hypertrophy of the bronchiolar wall. The budesonide group and all four of the wood panel-exposed groups showed less thickening of the bronchiolar wall and downregulated transcriptional expressions of cytokines such as interleukin-4 (IL-4) and interleukin-13 (IL-13). The serum tumor necrosis factor-α (TNF-α) mRNA expression level was significantly decreased only in the C. obtusa group, but the serum IL-4 levels were decreased in all wood panel treatment groups. Diff-Quik staining of bronchoalveolar lavage fluids revealed a decrease in the number of granulocytes in all wood panel treatment groups. The results suggest that VOCs from C. obtusa, P. densiflora, P. koraiensis and L. kaempferi produce antiasthmatic effects by regulating the production of IL-4, IL-9, IL-13, TNF-α.