Background: Histamine stimulates the release of several cytokines, such as interleukin (IL)-8 and granulocyte macrophage colony-stimulating factor, from bronchial epithelial cells. However, the functional individual histamine receptor subtype and intracellular signaling in bronchial epithelial cells are poorly defined.
Methods: Using human primary epithelial cells and the NCI-H292 cell line, we examined the expression of histamine receptor subtypes and histamine-induced second messenger. We also evaluated the involvements of mitogen-activated protein kinase, protein kinase C (PKC) and epidermal growth factor receptor in cytokine expression caused by histamine.
Results: Histamine H1 receptor (H1R) was the only subtype expressed in both types of cells. Histamine elevated intracellular calcium ion without affecting cAMP levels. Histamine induced the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Histamine also phosphorylated PKC and myristoylated alanine-rich C kinase substrate. Ro-31-8220, a PKC inhibitor, and PD98059, a mitogen-activated protein/ERK kinase inhibitor, suppressed the histamine-induced ERK activation and the production of granulocyte macrophage colony-stimulating factor and IL-8. On the contrary, histamine had no effect on the phosphorylation of epidermal growth factor receptor, and its specific inhibitor AG1478 failed to inhibit the histamine-induced ERK activation. Olopatadine, an H1 antagonist, completely blocked the histamine-related responses, whereas H2 and H3 antagonists did not. Histamine also augmented the IL-8 production caused by IL-4 or tumor necrosis factor-alpha.
Conclusions: The H1R-PKC-ERK pathway may play crucial roles in eliciting cytokine production from bronchial epithelial cells stimulated by histamine, leading to airway inflammation.
Copyright (c) 2006 S. Karger AG, Basel.