Cyclosporin A-Sensitive Calcium Signaling Represses NFκB Activation in Human Bronchial Epithelial Cells and Enhances NFκB Activation in Jurkat T-Cells

Abstract

Activation of the NFkappaB transcription factor in 16HBE human bronchial epithelial cells was compared with activation of NFkappaB in Jurkat T-cells. An NFkappaB-luciferase reporter gene was activated by phorbol myristyl acetate (PMA) in both cell types. Ionomycin added to PMA (P/I) inhibited NFkappaB activation in epithelial cells and enhanced PMA activation in T-cells. Cyclosporin A (CsA) inhibited calcium signaling in both cell types. Nuclear NFkappaB DNA-binding stimulated with PMA was inhibited with ionomycin in epithelial cells and was enhanced with ionomycin in T-cells; CsA reversed both effects of ionomycin. Cytosolic IkappaB-alpha was regulated identically in both cell types. Thus, calcium activated opposing nuclear signaling pathways in epithelial cells and T-cells. Calcium-mediated repression of NFkappaB in epithelial cells was derepressed by CsA, and this establishes a mechanism through which CsA may exert proinflammatory effects in nonlymphoid cells.