Targeting of PMN Expressed Lewis‐X Blocks PMN Transepithelial Migration and Increases Phagocytosis and Surface Mobilization of Granule Contents

Abstract

Dysregulated transepithelial migration (TEM) of neutrophils (PMN) is pathognomonic of numerous inflammatory disorders including inflammatory bowel disease (IBD), yet mechanisms controlling PMN TEM remain poorly defined. The glycan determinant Lewis X (Galβ1‐4 (Fucα1‐3) GlcNAc‐β‐R), expressed by PMN surface glycoproteins (including MAC‐1 and LFA‐1), has previously been implicated in adhesive interactions between PMN and endothelium. However, little is known about the wider role of Lex in PMN function following extravasation. Studies revealed that engagement of terminal Lex glycans (but not the related glycan sLex) increased PMN adhesive interactions, both with other PMNs and with intestinal epithelial cells, blocking PMN chemotaxis and TEM. Further, flow cytometry analyses revealed increased surface expression of Lex on human PMN following TEM. In addition to blocking PMN trafficking, targeting of Lex also altered post‐migratory PMN functions, increasing both PMN phagocytosis and the surface mobilization of azurophilic granule (CD63 and MPO) and specific granule (CD66b and lactoferrin) markers. Finally, immunohistochemistry analyses revealed robust expression of Lex by PMN in the crypt abscesses of individuals with active IBD. Therefore, Lex represents a potential target for regulating PMN trafficking into the intestinal lumen and PMN luminal function. Further, given its abundant expression on migrating PMN and during inflammation, Lex may be a rational target for modulating inflammation in IBD.