TGF-β1 is critical in the pathogenesis of chronic asthma and acts on eosinophils and other cells in the airways. Recently, we found TGF-β1 increases CLC3 expression in human blood eosinophils and induces migration. Here, we examined the interaction of TGF-β1 with IL-5 and eotaxin in the activation of chloride currents in human blood eosinophils. Eosinophils were purified (<99% pure, >98% viable) from the blood of healthy volunteers. Chloride current was measured at pH 7.4 by whole cell patch clamping in freshly isolated eosinophils using Axopatch 200B amplifier and analyzed by pClamp 10 software. Both eotaxin-1 and eotaxin-3 at low doses (0.075-10 ng/ml) increased outwardly rectified Cl- current in a time-dependent manner with maximum response at 500msec plus 100 mV. The eotaxin response at low doses (0.075-0.1 ng/ml) was slower in onset than at high dose. SB328437, a CCR3 antagonist (100 nM), inhibited eotaxin-induced Cl- current. Effect of eotaxin-3 was about 7-times larger than eotaxin-1. TGF-β1 (10ng/ml) decreased eotaxin-induced Cl- current. Incubation of eosinophils with IL-5 (10ng/ml) for 3hr decreased basal level of Cl- current. However, the addition of TGF-β1 with IL-5 significantly enhanced Cl- current. These data suggest differential effect of TGF-β1 in the activation and migration of human blood eosinophils in the presence of eotaxin or IL-5 in allergic airway inflammation and chronic asthma.
- Copyright © 2013 by The American Association of Immunologists, Inc.