Background: The variety of beneficial effects of green tea has been reported. Epigallocatechin-3-gallate (EGCG) is a major component of green tea extract. The biological activity of EGCG includes anti-allergic and anti-inflammatory activities. However, the precise effect of EGCG on the allergic airway inflammation has not been fully defined.
Methodology: In lung tissues of an asthma model-mouse, and nasal epithelial cells of patients with allergic rhinitis, the effect and brief signaling pathway of EGCG on MUC5B expression were investigated using real-time polymerase chain reaction, immunohistochemical, and immunoblot analysis.
Results: In the asthma model-mouse, mucus production, MUC5B expression, p38 mitogen-activated protein kinase (MAPK) and matrix metalloprotease (MMP)-9 expression of the asthma group were significantly higher than in the control group. Extracellular signal related kinase (ERK)1/2 MAPK expression did not change. Mucus production, MUC5B expression, p38 MAPK expression, and MMP-9 expression of the asthma + EGCG group were significantly lower than in the asthma group. In the nasal epithelial cells of patients with allergic rhinitis, EGCG significantly decreased phorbol 12-myristate 13-acetate (PMA)-induced MUC5B and MMP-9 expression.
Conclusion: These results suggest that EGCG reduces mucin expression in the asthma model-mouse and nasal epithelial cells of patients with allergic inflammation.