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gamma-interferon production in atopic dermatitis shows differential modification by phosphodiesterase and
L S Ostlere1, R B Mallett, A Kaminski
1Department of Dermatology, St Helier NHS Trust, Carshalton, Surrey, U.K.
Abstract:
Interferon-gamma (IFN-gamma) production by peripheral blood mononuclear leucocytes (MNL) is reduced in atopic dermatitis (AD) patients. This may be related to abnormalities in second messenger systems, and increased prostaglandin E2 (PGE2) release from monocytes. We compared the effects of manipulating the second messenger activity using the phosphodiesterase (PDE) inhibitor Ro 20-1724, dibutyryl cyclic adenosine monophosphate (cAMP), and cyclooxygenase inhibition of PGE2, on IFN-gamma production by cultured MNL from AD patients (n = 9) and normal controls (n = 10). Ficoll-Hypaque-separated MNL were cultured for 48 h with OKT3 stimulation, and cAMP, Ro 20-1724, or indomethacin. Supernatants were analysed for IFN-gamma by ELISA. Basal IFN-gamma was lower in AD patients, and the increase in IFN-gamma production with OKT3 was 6.5-fold greater in control subjects than patients with AD. Culture with indomethacin significantly enhanced OKT3-stimulated IFN-gamma production in both groups, whereas OKT3-stimulated IFN-gamma production was abolished with dibutyryl cAMP. IFN-gamma production was significantly lower with Ro 20-1742 in AD than in normal controls. We have shown reduced IFN-gamma release from unstimulated and stimulated MNL in AD patients compared with normal controls. The addition of indomethacin increased IFN-gamma production in both groups, although the increase was less in AD patients, suggesting an intrinsic cellular defect. IFN-gamma release from AD MNL was more sensitive to the inhibitory effects of PDE, and this may be due to increased PDE activity, or the hyperdynamic cAMP system present in atopics.
Insights
Peripheral blood mononuclear leucocytes from atopic dermatitis patients show reduced interferon-gamma (IFN-gamma) production. This impairment is linked to second messenger system abnormalities and increased prostaglandin E2 (PGE2) release.
Area of Science:
- Immunology
- Cellular Biology
- Dermatology
Background:
- Atopic dermatitis (AD) is associated with reduced interferon-gamma (IFN-gamma) production by peripheral blood mononuclear leucocytes (MNL).
- Potential causes include abnormalities in cellular second messenger systems and increased prostaglandin E2 (PGE2) release from monocytes.
- Investigating these pathways may reveal therapeutic targets for AD.
Purpose of the Study:
- To compare the effects of manipulating second messenger activity on IFN-gamma production in MNL from AD patients and healthy controls.
- To investigate the role of phosphodiesterase (PDE) inhibition, cyclic adenosine monophosphate (cAMP) levels, and cyclooxygenase inhibition of PGE2 on IFN-gamma release.
Main Methods:
- MNL were isolated from AD patients (n=9) and normal controls (n=10) using Ficoll-Hypaque density gradient centrifugation.
- Cells were cultured for 48 hours with OKT3 stimulation in the presence of dibutyryl cAMP, PDE inhibitor Ro 20-1724, or cyclooxygenase inhibitor indomethacin.
- Supernatants were analyzed for IFN-gamma levels using enzyme-linked immunosorbent assay (ELISA).
Main Results:
- Basal IFN-gamma levels were lower in AD patients compared to controls.
- OKT3-stimulated IFN-gamma production increased significantly more in controls than in AD patients.
- Indomethacin enhanced IFN-gamma production in both groups, but less so in AD patients.
- Dibutyryl cAMP abolished OKT3-stimulated IFN-gamma production, while Ro 20-1724 showed significantly lower IFN-gamma production in AD patients.
Conclusions:
- AD patients exhibit reduced IFN-gamma release from both unstimulated and stimulated MNL.
- The diminished response to indomethacin suggests an intrinsic cellular defect in AD.
- AD MNL appear more sensitive to PDE inhibition, potentially due to increased PDE activity or a hyperdynamic cAMP system.