Regulation of eosinophil trafficking by SWAP-70 and its role in allergic airway inflammation

Eosinophils are the predominant inflammatory cells recruited to allergic airways. In this article, we show that human and murine eosinophils express SWAP-70, an intracellular RAC-binding signaling protein, and examine its role in mediating eosinophil trafficking and pulmonary recruitment in a murine...

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Published in:	The Journal of immunology (1950) Vol. 188; no. 3; pp. 1479 - 1490
Main Authors:	Bahaie, Nooshin S, Hosseinkhani, M Reza, Ge, Xiao Na, Kang, Bit Na, Ha, Sung Gil, Blumenthal, Malcolm S, Jessberger, Rolf, Rao, Savita P, Sriramarao, P
Format:	Journal Article
Language:	English
Published:	United States 01-02-2012
Subjects:	Allergens Animals Cell Adhesion Cell Movement DNA-Binding Proteins Eosinophils - pathology Guanine Nucleotide Exchange Factors Humans Inflammation Mice Minor Histocompatibility Antigens Nuclear Proteins Respiratory Hypersensitivity - etiology Respiratory Hypersensitivity - pathology Venules - pathology
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Summary:	Eosinophils are the predominant inflammatory cells recruited to allergic airways. In this article, we show that human and murine eosinophils express SWAP-70, an intracellular RAC-binding signaling protein, and examine its role in mediating eosinophil trafficking and pulmonary recruitment in a murine model of allergic airway inflammation. Compared with wild-type eosinophils, SWAP-70-deficient (Swap-70(-/-)) eosinophils revealed altered adhesive interactions within inflamed postcapillary venules under conditions of blood flow by intravital microscopy, exhibiting enhanced slow rolling but decreased firm adhesion. In static adhesion assays, Swap-70(-/-) eosinophils adhered poorly to VCAM-1 and ICAM-1 and exhibited inefficient leading edge and uropod formation. Adherent Swap-70(-/-) eosinophils failed to translocate RAC1 to leading edges and displayed aberrant cell surface localization/distribution of α4 and Mac-1. Chemokine-induced migration of Swap-70(-/-) eosinophils was significantly decreased, correlating with reduced intracellular calcium levels, defective actin polymerization/depolymerization, and altered cytoskeletal rearrangement. In vivo, recruitment of eosinophils to the lungs of allergen-challenged Swap-70(-/-) mice, compared with wild-type mice, was significantly reduced, along with considerable attenuation of airway inflammation, indicated by diminished IL-5, IL-13, and TNF-α levels; reduced mucus secretion; and improved airway function. These findings suggest that regulation of eosinophil trafficking and migration by SWAP-70 is important for the development of eosinophilic inflammation after allergen exposure.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0022-1767 1550-6606
DOI:	10.4049/jimmunol.1102253