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Targeting of Neutrophil Lewis X Blocks Transepithelial Migration and Increases Phagocytosis and Degranulation
Jennifer C Brazil1, Ronen Sumagin2, Richard D Cummings3
1Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia; Department of Pathology, University of Michigan, Ann Arbor, Michigan.
Abstract:
Polymorphonuclear leukocytes (PMNs) are innate immune cells whose principal function is to migrate from the blood to sites of inflammation, where they exert crucial anti-infectious and immunomodulatory effects. However, dysregulated migration of PMNs into mucosal epithelial tissues is characteristic of chronic inflammatory disorders, including inflammatory bowel disease. Carbohydrate-mediated binding interactions between PMN Lewis glycans and endothelial glycan-binding proteins are critical for initial migration of PMN out of the vasculature. However, the role of Lewis glycans during transepithelial migration (TEM) has not been well characterized. Herein, we show that antibody blockade of Lewis X (Le(x)) displayed as terminal glycan residues on the PMN surface blocks chemotaxis and TEM while enhancing PMN-adhesive interactions with intestinal epithelia. Unexpectedly, targeting of subterminal Le(x) residues within glycan chains had no effect on PMN migration or adhesive interactions. There was increased surface expression of Le(x) on PMN after TEM, and blockade of terminal Le(x) regulated post-migratory PMN functions, increasing PMN phagocytosis and the surface mobilization of azurophilic (CD63, myeloperoxidase, and neutrophil elastase) and specific (CD66b and lactoferrin) granule markers. These findings suggest that terminal Le(x) represents a potential target for regulating PMN trafficking and function in inflamed mucosa. Furthermore, given its abundant expression on migrating PMN, Le(x) may be a rational target for modulating inflammation in diseases where dysregulated PMN influx is associated with host tissue damage.
Insights
Terminal Lewis X (Le(x)) on polymorphonuclear leukocytes (PMNs) is crucial for their migration and function. Blocking terminal Le(x) impacts PMN movement and enhances their ability to fight infection in inflamed tissues.
Area of Science:
- Immunology
- Cell Biology
- Glycobiology
Background:
- Polymorphonuclear leukocytes (PMNs) are key innate immune cells that migrate to inflammatory sites.
- Dysregulated PMN migration into mucosal tissues is implicated in chronic inflammatory diseases like inflammatory bowel disease.
- Carbohydrate interactions, specifically PMN Lewis glycans with endothelial proteins, are vital for initial PMN extravasation.
Purpose of the Study:
- To investigate the role of Lewis glycans, particularly Lewis X (Le(x)), in the transepithelial migration (TEM) of PMNs.
- To determine the impact of targeting terminal versus subterminal Le(x) on PMN migration and adhesion.
- To explore the effect of Le(x) blockade on post-migratory PMN functions.
Main Methods:
- Antibody blockade of Lewis X (Le(x)) on PMN surfaces.
- Assessment of PMN chemotaxis and transepithelial migration (TEM).
- Analysis of PMN adhesion to intestinal epithelia.
- Evaluation of surface expression of Le(x) and PMN granule markers post-migration.
Main Results:
- Antibody blockade of terminal Le(x) on PMNs inhibited chemotaxis and TEM but increased adhesion to intestinal epithelia.
- Targeting subterminal Le(x) residues had no significant effect on PMN migration or adhesion.
- Post-TEM, increased Le(x) expression was observed, and blocking terminal Le(x) enhanced PMN phagocytosis and granule mobilization.
Conclusions:
- Terminal Le(x) on PMNs plays a critical role in regulating their migration and function across epithelial barriers.
- Targeting terminal Le(x) offers a potential strategy for modulating PMN trafficking and inflammatory responses in mucosal tissues.
- Le(x) may serve as a therapeutic target for inflammatory diseases characterized by excessive PMN infiltration and tissue damage.
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