Abstract
BackgroundDiesel exhaust particles (DEP) are a major source of air pollution. Nasal fibroblasts are known to produce various cytokines and chemokines. The aim of this study was to evaluate DEP-induced cytokines and chemokines in nasal fibroblasts and to identify the signaling pathway involved.MethodsA cytokine and chemokine array performed after stimulation of nasal fibroblasts with DEP revealed that levels of IL-6 and IL-8 were increased most significantly among various cytokines and chemokines. RT—PCR and ELISA were used to determine the mRNA and protein expression levels of IL-6 and IL-8. Signaling pathways of p-38, Akt, and NF-κB were analyzed by western blotting, luciferase assay, and ELISA. Organ cultures of nasal interior turbinate were also developed to demonstrate the ex vivo effect of DEP on the expression of IL-6 and IL-8 and the associated signaling pathway.ResultsDEP increased the expressions of IL-6 and IL-8 in nasal fibroblasts at mRNA and protein levels. DEP induced phosphorylation of p38, Akt, and NF-κB, whereas inhibitors of p38, Akt, and NF-κB blocked these phophorylations and the expressions of IL-6 and IL-8. These findings were also observed in ex vivo organ culture of nasal inferior turbinate.ConclusionsDEP induces expression of IL-6 and IL-8 via p38, Akt, and NF-κB signaling pathways in nasal fibroblasts. This finding suggests that air pollution might induce or aggravate allergic rhinitis or chronic rhinosinusitis.
Highlights
Because of its position at the entry into the airways, the nasal mucosa is continuously exposed to inhaled agents from the environment [1]
Diesel exhaust particles (DEP) increased the expressions of IL-6 and IL-8 in nasal fibroblasts at mRNA and protein levels
DEP induces expression of IL-6 and IL-8 via p38, Akt, and NF-κB signaling pathways in nasal fibroblasts. This finding suggests that air pollution might induce or aggravate allergic rhinitis or chronic rhinosinusitis
Summary
Because of its position at the entry into the airways, the nasal mucosa is continuously exposed to inhaled agents from the environment [1]. To prevent stimulation of inflammation by these agents, the nasal mucosa has developed various mechanical mechanisms including tight junction molecules, mucus production, and ciliary movement. It possesses endogenous defense mechanisms involving many cytokines and chemokines [1,2]. Nasal fibroblasts are known to play a very important role in various pathophysiologic conditions of the nose. Their key role is as a structural modifier of the nasal mucosa through the production of extracellular matrix [3]. The aim of this study was to evaluate DEP-induced cytokines and chemokines in nasal fibroblasts and to identify the signaling pathway involved
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