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Clin Exp Allergy. 2006 Apr;36(4):543-53.

The alpha4bbeta7-integrin is dynamically expressed on murine eosinophils and involved in eosinophil trafficking to the intestine.

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  • 1Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.

Abstract

BACKGROUND:

Of the numerous adhesion molecules expressed by eosinophils, the alpha4-integrin has been identified as critically involved in eosinophil trafficking in the lung. Most studies have focused on the role of the alpha4beta1-adhesion complex, but eosinophils also express the alpha4beta7-integrin complex.

OBJECTIVE:

To investigate the role of alpha4beta7, by assessing its membrane expression on eosinophils from different compartments using allergen-challenged mice and IL-4/IL-5 bi-transgenic mice. In addition, we aim to determine the impact of beta7-integrin deficiency on eosinophil recruitment to the lungs and intestine in specific experimental allergic models.

RESULTS:

Evaluation of alpha4beta7 expression on bronchoalveolar lavage fluid (BALF) and lung tissue eosinophils revealed a down-regulation of this integrin as eosinophils migrate through the lungs. Indeed eosinophils isolated from the BALF and lung of allergic mice had low expression of the alpha4beta7-complex. While expression of the alpha4-chain remained unchanged, a significant decrease in beta7-surface expression was observed. Intestinal eosinophils, isolated from Peyer's patches, also displayed a down-regulation of the alpha4beta7-integrin, albeit only modest. In contrast, circulating eosinophils, isolated from the blood and spleen, expressed high levels of the alpha4beta7-integrin. However, eosinophil trafficking into the lungs of beta7-integrin-deficient mice was not significantly impaired in response to respiratory allergen challenges. In contrast, beta7-deficient mice had impaired eosinophil recruitment to the intestine.

CONCLUSION:

Taken together, these results identify differential expression of the alpha4beta7-integrin on eosinophils and its critical role in regulating eosinophil responses in the intestine.

PMID:
16630161
[PubMed - indexed for MEDLINE]
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