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Background: Interleukin-8 (IL-8), a potent chemotactic and activating factor for neutrophils and eosinophils, may be a crucial factor in severe asthma. The aim of this study was to evaluate the effect of fluticasone propionate (FP), a corticosteroid with potent anti-inflammatory activity, on the in vitro release of IL-8 by monocytes obtained from asthmatic patients. Methods: Monocytes from 15 non-atopic healthy donors and from 15 patients affected by moderate-severe allergic asthma were isolated and incubated (37°C, 5% CO[sub 2] ) for 24 h with varying combinations of lipopolysaccharide (LPS) from Escherichia coli (1 μg/ml) and FP (100 nmol/l). IL-8 concentration in the culture supernatant was measured by an immuno-enzymatic method (ELISA). Results: A highly significant inverse correlation between FEV1 (forced expiratory volume) values before withdrawal and in vitro IL-8 production by unstimulated monocytes from asthmatic patients was observed (Rho = –0.787; p = 0.0032). IL-8 production by either LPS-stimulated or unstimulated monocytes from asthmatic subjects was statistically increased compared to monocytes from healthy donors (p < 0.05). FP addition reduced IL-8 production by monocytes from asthmatic patients and also from healthy donors (p < 0.05). Conclusions: The partial IL-8 inhibition by FP could be closely related to the anti-inflammatory activity of this corticosteroid. Based on these results, we propose that the clinical improvement of asthma, observed following FP administration, may depend, at least in part, on the ability of this drug to modulate cytokine production by monocytes.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

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. Aims: 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 γ/ml) or with complete medium alone as a control. Culture supernatants, in vitro treated or not with 10[sup -7] or 10[sup -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[sup -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[sup -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. [ABSTRACT FROM AUTHOR]

Abstract: Transforming growth factor (TGF)-β may play a significant role in nasal polyposis pathogenesis, possibly through fibroblast activation. We studied the effects of two TGF-β isoforms (TGF-β1 and TGF-β2) on nasal polyposis fibroblasts by evaluating cell proliferation and differentiation into myofibroblasts. In addition, the inhibitory activity of different concentrations of fluticasone propionate (F.P.) was tested in this in vitro system. Primary nasal polyp tissue-derived fibroblasts were stimulated with different concentrations (1, 10 and 20ng/ml) of TGF-β1 and TGF-β2 for different incubation periods (24, 48 and 72h) and cell proliferation [3H thymidine ([3H]TdR) incorporation] and α-smooth muscle actin (α-SMA) expression (immunocytochemistry) was evaluated. The lowest concentration of TGF-β1 (1ng/ml) induced a significant increase in [3H]TdR incorporation at 48 and 72h (p <0.05, each comparison), while in the presence of TGF-β (10ng/ml) and TGF-β2 (1ng/ml) the enhancement in cell proliferation was significant only after 48h (p <0.05, each comparison with the unstimulated cells). In contrast, a significant increase in α-SMA expression was observed in the presence of the two highest concentration of both TGF-β isoforms, at 48 and 72h for TGF-β1 (p <0.05, each comparison), but only at 72h for TGF-β2 (<0.05, each comparison). Finally, at all concentrations tested, F.P. significantly inhibited the TGF-β1 and TGF-β2-induced 3HTdR incorporation (p <0.01, each comparison) and the α-SMA expression (p <0.05, each comparison). Thus, in vitro different concentrations of TGF-β1 and TGF-β2 appear to sequentially stimulate primary nasal polyp tissue-derived fibroblast proliferation and myofibroblast differentiation. These activities are effectively inhibited by F.P. [Copyright &y& Elsevier]

Transforming growth factor (TGF)-beta may play a significant role in nasal polyposis pathogenesis, possibly through fibroblast activation. We studied the effects of two TGF-beta isoforms (TGF-beta1 and TGF-beta2) on nasal polyposis fibroblasts by evaluating cell proliferation and differentiation into myofibroblasts. In addition, the inhibitory activity of different concentrations of fluticasone propionate (F.P.) was tested in this in vitro system. Primary nasal polyp tissue-derived fibroblasts were stimulated with different concentrations (1, 10 and 20 ng/ml) of TGF-beta1 and TGF-beta2 for different incubation periods (24, 48 and 72 h) and cell proliferation [3H thymidine ([3H]TdR) incorporation] and alpha-smooth muscle actin (alpha-SMA) expression (immunocytochemistry) was evaluated. The lowest concentration of TGF-beta1 (1 ng/ml) induced a significant increase in [3H]TdR incorporation at 48 and 72 h (p<0.05, each comparison), while in the presence of TGF-beta (10 ng/ml) and TGF-beta2 (1 ng/ml) the enhancement in cell proliferation was significant only after 48 h (p<0.05, each comparison with the unstimulated cells). In contrast, a significant increase in alpha-SMA expression was observed in the presence of the two highest concentration of both TGF-beta isoforms, at 48 and 72 h for TGF-beta1 (p<0.05, each comparison), but only at 72 h for TGF-beta2 (<0.05, each comparison). Finally, at all concentrations tested, F.P. significantly inhibited the TGF-beta1 and TGF-beta2-induced 3HTdR incorporation (p<0.01, each comparison) and the alpha-SMA expression (p<0.05, each comparison). Thus, in vitro different concentrations of TGF-beta1 and TGF-beta2 appear to sequentially stimulate primary nasal polyp tissue-derived fibroblast proliferation and myofibroblast differentiation. These activities are effectively inhibited by F.P.