Zingiber cassumunar ROXb. and its active constituent inhibit MMP-9 direct activation by house dust mite allergens and MMP-9 expression in PMA-stimulated human airway epithelial cells

Background: House dust mite (HDM) induced-matrix metalloproteinase (MMP)-9 plays a role in asthma. Zingiber cassumunar Roxb. (Phlai in Thai) has been used in folk medicine for asthma treatment. Objective: We investigated effects of Phlai and its constituent (E)-4-(3',4'-dimethoxyphenyl)but-3-en-1-ol (compound D) on the cleavage of pro-MMP-9 by HDM. The effects of these compounds on phorbol 12-myristate 13-acetate (PMA)-induced MMP-9 gene and protein expression in airway epithelial cells (NCI-H292) were also investigated. Methods: Pro-MMP-9 was directly activated in vitro with HDM in the presence or absence of the ethanolic extracts of Phlai or compound D for 1 hour. The amount of activated MMP-9 was determined using gelatin zymography. To study the cellular response of Phlai, NCI-H292 cells were pretreated with crude Phlai extracts or compound D for 2 hours, and then the cells were stimulated with PMA for 48 hours. The mRNA and protein levels of MMP-9 were measured by RT-PCR and Western blotting, respectively. MMP-9 activity was determined by gelatin zymography. Results: Crude Phlai extracts (0.25 - 2.0 mg/ml) and compound D (0.5 - 4.0 mg/ml) inhibited proMMP-9 cleavage by HDM. Furthermore, crude Phlai extracts (100 mu g/ml) and compound D, at concentrations of 50 and 100 mu g/ml, attenuated the PMA-induced MMP-9 gene and expression in NCI-H292 cells. These compound also suppressed MMP-9 release from PMA-induced NCI-H292 cells. Conclusion: The crude ethanolic extract of Z. cassumunar and its active constituent compound D inhibited the cleavage of pro-MMP-9 by HDM. They also inhibited PMA-induced MMP-9 gene and protein synthesis in human airway epithelial cells.