In vitro effects of fluticasone propionate on IL-13 production by mitogen-stimulated lymphocytes.
BACKGROUND
Corticosteroid administration produces multiple immunomodulatory effects, including down-regulation of cytokine production by CD4 T lymphocytes. Fluticasone propionate (FP) (Glaxo Smith&Kline, Greenford, UK), a highly lipophilic topical corticosteroid, has been shown to be safe and effective in the treatment of asthma and of both seasonal and perennial rhinitis.


OBJECTIVE
To gain insight into the mechanisms of FP therapeutic effects, we evaluated interleukin (IL)-13 (a type 2 cytokine that seemingly plays a pivotal role in allergic mechanisms) production by mitogen-stimulated peripheral blood mononuclear cells (MNC) in vitro, treated or not with FP.


METHODS
MNC from 10 healthy subjects and 10 asthmatic atopic patients with Parietaria allergy were stimulated v/v with phytohaemagglutinin (PHA) (50 gamma/ml) or with complete medium alone as a control. Culture supernatants, in vitro treated or not with 10(-7) or 10(-8) M FP, were collected after 48 or 72 h incubation. IL-13 production was assessed by enzyme-linked immunosorbent assay. In random selected samples, after 4 or 24 h of cell cultures, RNA was extracted and IL-4 and IL-5 reverse transcriptase-polymerase chain reaction (RT-PCR) products analyzed.


RESULTS
At 48 h, there were no differences in IL-13 concentration in PHA-stimulated cultures between healthy subjects and asthmatic patients (93.6 +/- 18.9 versus 111.0 +/- 25.1 pg/ml). At 72 h, similar results were obtained (63.9 +/- 3.0 versus 73.3 +/- 2.5 pg/ml, respectively). At this time, however, IL-13 concentrations were significantly decreased versus 48 h both in asthmatics (p < 0.001) and in controls (p < 0.001). Treatment with 10(-7) M FP significantly reduced IL-13 production in healthy subjects and asthmatic patients both at 48 h (93.6 +/- 18.9 versus 50.50 +/- 10.6 pg/ml, p < 0.001, and 111.0 +/- 25.1 versus 59.3 +/- 13.6 pg/ml, p < 0.001, respectively) and at 72 h (63.9 +/- 9.6 versus 35.5 +/- 4.4 pg/ml, p < 0.001, and 73.3 +/- 8.0 versus 40.7 +/- 4.5 pg/ml, p < 0.001, respectively). Similar results were obtained with 10(-8) M FP at 48 and 72 h. Accordingly, evaluation of RT-PCR products from selected cell samples showed a FP dosage-dependent inhibition of IL-4 and IL-5 mRNA production both for healthy subjects and asthmatic patients.


CONCLUSIONS
FP in vitro impairs IL-13 production by PHA-stimulated MNC from asthmatic and control subjects. This strengthens previous suggestions that IL-13 inhibition by steroids may, at least in part, account for their therapeutic effects.
Di Lorenzo
Gabriele
G
Dipartimento di Medicina, Clinica e delle Patologie emergenti, Università degli Studi di Palermo, Italy. dilo601@unipa.it
Pacor
Maria Luisa
ML
Pellitteri
Maria Esposito
ME
Gangemi
Sebastiano
S
Di Blasi
Patrizia
P
Candore
Giuseppina
G
Colombo
Alfredo
A
Lio
Domenico
D
Caruso
Calogero
C
D000287:Administration, Topical; D000730:Androstadienes / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001249:Asthma / Q000276:immunology; D002478:Cells, Cultured; D000068298:Fluticasone; D005938:Glucocorticoids; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D018793:Interleukin-13 / Q000378:metabolism*; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010835:Phytohemagglutinins / Q000494:pharmacology; D012313:RNA / Q000378:metabolism
D000730:Androstadienes; D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D018793:Interleukin-13; D010835:Phytohemagglutinins; D012313:RNA; D000068298:Fluticasone