CCR3-dependent eosinophil recruitment is regulated by sialyltransferase ST3Gal-IV.

Abstract

Eosinophil recruitment is a pathological hallmark of many allergic and helminthic diseases. Here, we investigated chemokine receptor CCR3-induced eosinophil recruitment in sialyltransferase <i>St3gal4^-/-</i> mice. We found a marked decrease in eosinophil extravasation into CCL11-stimulated cremaster muscles and into the inflamed peritoneal cavity of <i>St3gal4^-/-</i> mice. Ex vivo flow chamber assays uncovered reduced adhesion of <i>St3gal4</i>^-/- compared to wild type eosinophils. Using flow cytometry, we show reduced binding of CCL11 to <i>St3gal4^-/-</i> eosinophils. Further, we noted reduced binding of CCL11 to its chemokine receptor CCR3 isolated from <i>St3gal4</i>^-/- eosinophils. This was accompanied by almost absent CCR3 internalization of CCL11-stimulated <i>St3gal4</i>^-/- eosinophils. Applying an ovalbumin-induced allergic airway disease model, we found a dramatic reduction in eosinophil numbers in bronchoalveolar lavage fluid following intratracheal challenge with ovalbumin in <i>St3gal4</i>-deficient mice. Finally, we also investigated tissue-resident eosinophils under homeostatic conditions and found reduced resident eosinophil numbers in the thymus and adipose tissue in the absence of ST3Gal-IV. Taken together, our results demonstrate an important role of ST3Gal-IV in CCR3-induced eosinophil recruitment in vivo rendering this enzyme an attractive target in reducing unwanted eosinophil infiltration in various disorders including allergic diseases.