Increased expression of chemokine receptors CCR1 and CCR3 in nasal polyps: molecular basis for recruitment of the granulocyte infiltrate.

Inflammatory processes play an important role in the development of nasal polyps (NP), but the etiology and, to a high degree also, the pathogenesis of NP are not fully understood. The role of several cytokines and chemokines such as eotaxins, IL-4, IL-5, IL-6, IL-8, and RANTES has been reported in NP. Herewith, we investigated the expression and pattern of distribution of chemokine receptors CCR1 and CCR3 in nasal polyps. Immunohistochemical detection was carried out in frozen sections of biopsies from 22 NP and 18 nasal mucosa specimens in both the epithelial and stromal compartments. Fluorescence microscopy and computerized image analysis revealed a statistically significant increased number of CCR1 (45.2 ± 2.8 vs. 15.1 ± 1.9, p < 0.001)-positive as well as CCR3 (16.4 ± 1.4 vs. 9.7 ± 1.1, p < 0.001)-positive cells in the stroma of NP compared to nasal mucosa. In comparison to healthy nasal mucosa, increased positivity of CCR3 was detected in the epithelial compartment of NP. Our data suggest that increased expression of CCR1 and CCR3 chemokine receptors may, in accord with various chemokines, contribute to the pathogenesis of nasal polyposis by facilitating increased migration and prolonged accumulation of inflammatory cells, e.g., eosinophils, in the inflammatory infiltrate of NP.