The Primary Role in Biologic Activity of the Neutrophil Chemokines IL-8 and GRO- α in Cultured Nasal Epithelial Cells

Abstract

Primary nasal epithelial cells were investigated for their ability to synthesize and deliver neutrophil chemotactic factors (chemokines) following tumor necrosis factor-α (TNF-α) induction. The chemokines interleukin8 (IL-8), growth-related oncogene-α (GRO-α), epithelial cell-derived neutrophil attractant-78 (ENA-78), and granulocyte chemotactic protein-2(GCP-2) have been detected and characterized and shown to have different potencies in the chemotaxis of neutrophils. Cultures of primary nasal epithelial cells were treated with TNF-α in concentrations of 20 and 200 ng/ml for 2, 8, 24, and 72 h. The chemokine protein concentrations in the supernatants of the incubations were determined by the ELISA technique. Chemokine mRNA expression in epithelial cells was also measured using the reverse transcriptase-polymerase chain reaction (RT-PCR). The biologic activity of the chemokines was identified using a three-step high-performance liquid chromatography (HPLC) technique, a bioassay involving measurement of neutrophil chemotaxis in a single Boyden chamber. Both the IL-8 and GRO-α proteins and their respective mRNA appear to be induced by TNF-α in epithelial cells. The chemotactic responsiveness of both GRO-α and IL-8 appears to predominate after 24 h incubation with TNF-α. The chemokines GCP-2 and ENA-78 were only weakly induced by TNF-α. The neutrophil chemokines IL-8 and GRO-α were synthesized in nasal epithelial cell culture induced by TNF-α in biologically active concentrations of 0.8 ng/ml and 1.42 ng/ml, respectively. It appears that both the IL-8 and GRO-α chemokines may contribute to neutrophil tissue migration in sinusitis, whereas GCP-2 and ENA-78 are of secondary importance to the chemotaxis of neutrophils in this condition.