The main findings of our study are: 1st) fetal bovine serum induced the secretion of IL-6, IL-8, GM-CSF, and sICAM-1 by cultured epithelial cells from both nasal mucosa and polyps; 2nd) in both nasal mucosa and polyp epithelial cells, mometasone inhibited the induced secretion of IL-6, IL-8, GM-CSF and sICAM-1; 3rd) desloratadine weakly but significantly potentiated the inhibitory effect of low concentrations of mometasone (nanomolar) on IL-6 secretion from nasal mucosa epithelial cells; 4th) epithelial cell secretions from both nasal mucosa and nasal polyps induced eosinophil survival; 5th) mometasone inhibited in a dose-dependent manner the eosinophil survival induced by both nasal mucosa and nasal polyp epithelial secretions; and 6th) desloratadine weakly but significantly potentiated the effect of low concentrations of mometasone (picomolar) on decreasing eosinophil survival, especially when epithelial secretions were from nasal mucosa.
In the present study, we have shown that human nasal mucosa and polyp epithelial cells increased the release of IL-6, IL-8, GM-CSF, and sICAM-1 in response to FBS. These findings confirm our previous studies which show that cultured nasal epithelial cells from both human nasal mucosa and nasal polyp express and release GM-CSF, IL-1β, IL-6, IL-8 and TNF-α [7, 11, 12, 15, 16, 30]. Moreover, a recent study has reported high concentrations of IL-6 in nasal tissue from patients suffering from CRS with NP 
In our in vitro model of eosinohil inflammation, MF showed an inhibitory effect on FBS-induced IL-6, IL-8, GM-CSF, and sICAM-1 secretion in both nasal mucosa and polyp epithelial cell cultures. In fact, we have previously demonstrated that other corticosteroids, such as beclometasone dipropionate fluticasone, triamcinolone and budesonide, have a similar effect [11, 15, 16]. This inhibitory effect suggests that these drugs, including MF may decrease inflammation in the upper airways by inhibiting pro-inflammatory cytokine release by epithelial cells, and consequently, leading to a reduction in inflammatory cell recruitment and activation promoted by such cytokines. In support with our findings, it has been reported that MF inhibit the cytokine-induced GM-CSF expression in a respiratory cell line , the LPS-induced IL-1, IL-6 and TNF-α expression in murine blood cells  as well as the ICAM-1 expression in skin  and lung fibroblasts .
In the present study, DL inhibited IL-6 secretion from both NM and NP epithelial cells. We realize that the high concentrations of DL used in our study are significantly higher than those found in blood or epithelial lining fluid during the treatment of patients. However, since our research is a mechanistic study, our research cannot be used as a guide for therapeutic indications. In fact, previous studies have found similar results in relation to DL effect on pro-inflammatory mediators' production and secretion, not only in epithelial cells but also in other cell types. On this regard, DL decreased IL-6 and IL-8 secretion from basophilic cells (KU812) and human mast cell line (HMC-1) , IL-4 and IL-13 from basophil-enriched suspension , and GM-CSF secretion from HMC-1 cells  and airway epithelial cells . The inhibition of a wide range of cytokines suggests that DL may play a role in modulating mediators associated with the airway inflammatory process.
When used in combination with the corticosteroid MF, DL was able to increase the inhibitory effect caused by MF alone on IL-6 secretion, and to inhibit IL-8 secretion in a dose of MF that caused no significant effect on this cytokine when administered alone. Thus, DL seems to improve and potentiate MF effects on cytokine secretion by nasal epithelial cells. However, this effect seems to be present only at low but significant inhibitory doses of MF. To some extent, these findings agree with clinical trials in which it has been demonstrated improvements in the sneezing , rhinorrhoea , total symptom score , nasal itching  and total nasal symptom score  when combining different corticosteroids and antihistamines in the treatment of allergic and non-allergic rhinitis.
In the present study, MF decreased the eosinophil survival induced by epithelial secretions from both NM and NP. In keeping with our results, it has been reported that MF reduced the sputum eosinophilia in asthmatic patients , decreased the number of eosinophils in nasal mucosa biopsies  and induced apoptosis in eosinophil cultured in vitro . In addition, we found that DL reduced eosinophil survival induced by epithelial secretions from nasal mucosa, as previously reported .
When investigating the combined effect of MF plus DL on eosinophil viability, an additive effect was found on eosinophil survival induced by epithelial cell secretions, since DL increased the inhibitory effect of MF alone. In the same line, it has been reported that loratadine improved the effect of a corticosteroid in the treatment of non-allergic rhinitis with eosinophilia decreasing eosinophil counts in nasal smears  and nasal sneezing in seasonal allergic rhinitis .