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In vivo expression of cytokine receptor mRNA in atopic dermatitis
R A Taha1, D Y Leung, O Ghaffar
1Meakins-Christie Laboratories, McGill University, Montreal, Quebec, Canada.
Background:
Atopic dermatitis (AD) is a chronic inflammatory skin disease with immunopathologic features that vary depending on the duration of the lesion. Acute lesions are associated with a T-cell infiltrate and a high expression of IL-4 mRNA compared with chronic lesions, uninvolved AD skin, or skin from normal control subjects. Chronic lesions are rich in eosinophils and monocyte/macrophages and contain a greater number of IL-5, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-12 (p40) mRNA-positive cells.
Objectives:
In this study, we investigated the mRNA expression of the IL-4 receptor (IL-4Ralpha), IL-5Ralpha, GM-CSFRalpha, and IL-12Rbeta2 in biopsy specimens from acute and chronic AD lesions, uninvolved AD skin, normal skin, and psoriatic skin lesions.
Methods:
Cytokine receptor mRNA was examined in paraformaldehyde-fixed biopsy specimens with in situ hybridization with specific antisense riboprobes.
Results:
Acute and chronic skin lesions exhibited a significant increase in numbers of IL-5Rbeta and GM-CSFRalpha mRNA-positive cells compared with uninvolved AD skin and normal skin (P < .001). Chronic skin lesions had a significantly greater number of IL-5Ralpha and GM-CSFRalpha mRNA-positive cells when compared with acute AD skin (P < .001). In contrast, IL-4Ralpha mRNA expression was increased in acute but not chronic AD lesions compared with uninvolved and normal skin (P < .001). No significant differences were observed in numbers of IL-12Rbeta2 mRNA-positive cells when comparing acute AD, chronic AD, uninvolved AD, and normal skin. In psoriatic skin, the numbers of GM-CSFRalpha and IL-12Rbeta2 mRNA-positive cells were significantly increased compared with acute AD lesions, uninvolved skin, and normal control skin (P < .01).
Conclusions:
These results demonstrate that acute AD is associated with a high expression of IL-4Ralpha, whereas IL-5Ralpha and GM-CSFRalpha mRNA are predominantly increased in chronic AD and to lesser extent in acute lesions. These findings support the biphasic role of IL-4, IL-5, and GM-CSF in the pathophysiology of AD.
Insights
Atopic dermatitis (AD) involves distinct immune responses. Acute AD shows high interleukin-4 receptor alpha (IL-4Ralpha) mRNA, while chronic AD elevates interleukin-5 receptor alpha (IL-5Ralpha) and granulocyte-macrophage colony-stimulating factor receptor alpha (GM-CSFRalpha) mRNA, supporting a biphasic role.
Area of Science:
- Immunodermatology
- Molecular biology
Background:
- Atopic dermatitis (AD) is a chronic inflammatory skin condition with varying immunopathology based on lesion duration.
- Acute AD lesions feature T-cell infiltrates and high IL-4 mRNA, while chronic lesions contain eosinophils, macrophages, and increased IL-5, GM-CSF, and IL-12 mRNA.
Purpose of the Study:
- To investigate the mRNA expression of key cytokine receptors (IL-4Ralpha, IL-5Ralpha, GM-CSFRalpha, IL-12Rbeta2) in different stages of AD and control skin.
- To elucidate the differential roles of these receptors in the pathogenesis of acute and chronic atopic dermatitis.
Main Methods:
- In situ hybridization was used to examine cytokine receptor mRNA expression.
- Analysis was performed on biopsy specimens from acute AD lesions, chronic AD lesions, uninvolved AD skin, normal skin, and psoriatic skin.
Main Results:
- Both acute and chronic AD lesions showed significantly increased IL-5Ralpha and GM-CSFRalpha mRNA compared to normal and uninvolved skin.
- Chronic AD lesions exhibited higher IL-5Ralpha and GM-CSFRalpha mRNA than acute lesions.
- Acute AD lesions, but not chronic, displayed increased IL-4Ralpha mRNA compared to controls.
- Psoriatic lesions showed elevated GM-CSFRalpha and IL-12Rbeta2 mRNA compared to AD and normal skin.
Conclusions:
- Acute AD is characterized by high IL-4Ralpha mRNA expression.
- Chronic AD demonstrates predominant increases in IL-5Ralpha and GM-CSFRalpha mRNA.
- These findings support a biphasic role for IL-4, IL-5, and GM-CSF in the immunopathogenesis of atopic dermatitis.