Inhibition of NADPH oxidase subunits translocation by tea catechin EGCG in mast cell

The inhibitory mechanism of tea catechins for allergy remains undefined. We studied the effect of catechins, mainly EGCG, on the activation of mast cell line canine cutaneous mastocytoma cells (CM-MC). Compound 48/80 induced the degranulation in CM-MC dose dependently, whereas its release of beta-hexosaminidase was inhibited by EGCG and O-methylated EGCG (EGCG-Me). Both catechins were found to inhibit intracellular ROS generation dose dependently together with DPI. Intracellular ROS generation in human polymorphonuclear leukocytes was also inhibited by EGCG. Neither L-NAME, ebeselen nor NAC inhibited ROS generation. From the Western blot analysis of the subunits components of NADPH oxidase, we detected cytosolic subunits; p47(phox), p67(phox), p40(phox), rac2 and membrane subunits; gp91(phox), p22(phox) in CM-MC. Cytosolic subunits were translocated from cytosol to membrane time dependently after stimulation with compound 48/80. EGCG and DPI inhibited cytosolic subunits from translocating into membrane. These data suggest that EGCG inhibits the activation of NADPH oxidase in CM-MC.