Lilium lancifolium Thunb. extract attenuates pulmonary inflammation and air space enlargement in a cigarette smoke-exposed mouse model

Lilium lancifolium Thunb. (Liliaceae) has long been used as a traditional medicine in Korea and China to treat bronchitis, pneumonia, and other pulmonary ailments. Cigarette smoke (CS) is a major risk factor for the development of pulmonary inflammatory response; it also triggers pulmonary alveoli enlargement. In the present study, we investigate the effects of Lilium lancifolium Thunb. root extract on pulmonary inflammatory responses in a CS-exposed mouse model. Water extract of Lilium lancifolium Thunb. root was fed to C57BL/6 mice prior CS exposure every day for 3 weeks. The numbers of macrophages and neutrophils in bronchoalveolar lavage fluid (BALF) were counted. The relative inflammatory factors, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), monocyte chemotactic protein-1 (MCP-1), and matrix metalloproteinase-12 (MMP-12) were measured by real-time PCR, ELISA, or Western blot analysis. The average alveoli size was determined by lung histology. Lilium lancifolium Thunb. root extract was found to significantly inhibit the numbers of macrophages and neutrophils in BALF due to CS exposure. Lilium lancifolium Thunb. root extract also reduced the protein secretion levels of TNF-α, IL-6, IL-1β, and MCP-1 in BALF and the RNA expression levels of TNF-α, IL-6, IL-1β, MCP-1, and MMP-12 in lung tissue compared with mice only exposed to CS. Moreover, MMP-12 in serum was down regulated in Lilium lancifolium Thunb. root extract treated mice compared with CS-exposed mice. Finally, a morphometric analysis of the lungs of Lilium lancifolium Thunb. root extract treated mice demonstrated a significant reduction in airspace size compared to mice only exposed to CS. Our results show that Lilium lancifolium Thunb. root extract reduces lung inflammation and airspace enlargement in a CS-exposed mouse model. These data indicate that Lilium lancifolium Thunb. root extract is a therapeutic candidate for pulmonary inflammation and emphysema caused by CS.