Background: T-regulatory cells (Treg) affect the balance of TH2 and TH1 cells. Treg, TH2 and TH1 cells are regulated by the FOXP3, GATA-3 and T-bet transcription factors respectively. Our aim was to determine the number of FOXP3+, GATA-3+ and T-bet+ cells in nasal mucosa in symptom-free allergic rhinitis (AR) patients vs healthy controls, as well as the effects of natural pollen exposure and concomitant nasal glucocorticoid treatment on these cells.
Methods: Nasal biopsies were taken from healthy controls and patients with grass-pollen AR preseason. The AR patients were randomized to receive treatment with either fluticasone propionate (FP) or a placebo, and additional biopsies were taken during the pollen season. FOXP3+, GATA-3+ and T-bet+ cells in nasal mucosa were quantified by immunohistochemistry.
Results: The number of FOXP3+ and GATA-3+ cells, but not T-bet+ cells, was significantly higher in AR patients vs controls preseason. The number of FOXP3+ cells remained unchanged in the former group after the pollen season but decreased significantly in the nasal mucosa as a result of FP treatment. The pollen season substantially increased the number of GATA-3+ cells, which was inhibited by FP. The number of T-bet+ cells was not affected by pollen or FP.
Conclusion: These data suggest that nasal glucocorticoids attenuate the allergic inflammation partly by reducing the number of TH2 cells, but not by means of local upregulation of Treg cells. The local relationship between TH1 and TH2 cells as well as between Treg and TH2 is maintained by nasal glucocorticoid treatment.