Abstract
BACKGROUND: Systemic corticosteroids are the most effective anti-inflammatory drugs used for controlling chronic rhinosinusitis (CRS) symptoms. The potential mechanisms for their beneficial effects include increasing the number and function of T regulatory cells (Tregs), as reported in the local tissue post-intranasal steroid treatment. We investigated the effect of systemic corticosteroids on peripheral blood (PB) Tregs in subjects with CRS. METHODS: Twenty CRS subjects and 19 controls were recruited. PB mononuclear cells (PBMCs) were isolated from CRS subjects before and after systemic corticosteroid administration in the course of clinical treatment. Control subjects received no treatment and were studied at one visit. Nasal symptoms were recorded. CD4(+) CD25(+) Foxp3(+) cells (Tregs) were analyzed by flow cytometry. Messenger RNA (mRNA) levels for interferon γ (IFN-γ), interleukin 4 (IL-4), IL-10, IL-13, IL-17A, transforming growth factor β1 (TGF-β1), forkhead box P3 (FoxP3), and GATA-binding factor 3 (GATA-3) were measured in PBMCs using real-time polymerase chain reaction (PCR). RESULTS: CRS subjects reported improved nasal symptoms (p = 0.005) and significantly reduced PB Tregs after treatment with corticosteroids (p = 0.042). The transcript levels of IL-4 and GATA-3 were significantly higher in the CRS subjects at their first visit when compared to controls (p = 0.019 and p = 0.05, respectively). Corticosteroid treatment lowered the transcript levels of immunoregulatory transcription factors [FoxP3 (p = 0.048) and GATA-3 (p = 0.012)] and IFN-γ (p = 0.036) in PB. CONCLUSION: In contrast to prior work in local nasal tissue, our study reports reduced PB Tregs and decreased T helper 1 (T(H)1) and T(H)2 function after treatment with systemic corticosteroids. These data indicate that corticosteroid effects on Tregs in CRS are complex involving local signals in the tissue that are distinct from those in circulating cells.