CX3CR1 Contributes to Nasal Neutrophilia in Airways Allergy: Novel Rolefor IL-8 in Inducing CX3CR1Expression by Neutrophils

Background: CX3CR1 is involved in promotion of inflammation by recruiting inflammatory cells to the inflamed tissue. However, no reports studied their expression by neutrophils infiltrating the nasal tissue in chronic rhinosinusitis (CRS) patients with or without associated airways allergy. Objectives: Our objectives were to evaluate the expression of CX3CR1 by neutrophil infiltrating the inflamed nasal tissue in patients suffering from CRS, and to study the receptor gene induction in activated human neutrophils. Methods: Immunohistochemistry were conducted to evaluate CX3CR1 expression by neutrophil cells infiltrating the middle turbinate from patients operated for endoscopic sinus surgery. The gene expression and the receptor surface expression in resting versus activated neurophils by IL-8 were studied by Q-PCR and flow cytometry (FACS). Results: It is shown that CX3CR1 was significantly expressed by nasal infiltrating leukocytes when compared to control group. This expression was higher in patients with CRS and airway allergy than those with CRS and no airway allergy. Neutrophils contributed largely to the sub-epithelial layer inflammatory cells expressing CX3CR1. Both the gene and the surface expression of CX3CR1 were significantly induced in activated neutrophils by IL-8. Conclusion: CX3CR1 expression by neutrophils is expressed in CRS and the receptor’s gene expression is induced in activated neutrophils by IL-8. These results further highlights and identifies an importance role for CX3CR1 in nasal inflammation.