Leukotriene B4 mediates histamine induction of NF-kappaB and IL-8 in human bronchial epithelial cells.

In 16HBE transformed human bronchial epithelial cells, histamine stimulated interleukin (IL)-8 mRNA and protein secretion, and this histamine stimulation was inhibited by the H1-receptor antagonist diphenhydramine (DPH), by the inhibitor of 5-lipoxygenase-activating protein (FLAP) MK-886, by the 5-lipoxygenase inhibitor Zileuton, and by dexamethasone. Histamine stimulated bronchial epithelial cell production of leukotriene B4 (LTB4), and this production was inhibited by FLAP inhibitors MK-886 and L-655,238 and Zileuton. Histamine stimulated IL-8 luciferase reporter gene activity that was inhibited with DPH, dexamethasone, MK-886 and L-655,238, and Zileuton. The inhibition of IL-8 transcription and protein secretion by FLAP inhibitors and Zileuton was reversed with exogenous LTB4. There was increased IL-8 nuclear factor-kappaB (NF-kappaB) DNA-binding activity after histamine stimulation, and this was inhibited by DPH and MK-886. Cytoplasmic phospholipase A2 mRNA levels were also potently induced by histamine. Thus histamine stimulation of bronchial epithelial cells involves binding at H1 receptors, production of LTB4, activation of NF-kappaB and increased expression of IL-8.