Ly6G ligation blocks recruitment of neutrophils via a β2-integrin–dependent mechanism

JX Wang, AM Bair, SL King, R Shnayder… - Blood, The Journal …, 2012 - ashpublications.org
JX Wang, AM Bair, SL King, R Shnayder, YF Huang, CC Shieh, RJ Soberman…
Blood, The Journal of the American Society of Hematology, 2012ashpublications.org
Ly6G is a glycosylphosphatidylinositol (GPI)–anchored protein of unknown function that is
commonly targeted to induce experimental neutrophil depletion in mice. In the present study,
we found that doses of anti-Ly6G Abs too low to produce sustained neutropenia remained
capable of inhibiting experimental arthritis, leaving joint tissues free of infiltrating neutrophils.
Thioglycollate-stimulated peritonitis was also attenuated. No alteration in neutrophil
apoptosis was observed, implicating impaired recruitment. Indeed, Ly6G ligation abrogated …
Abstract
Ly6G is a glycosylphosphatidylinositol (GPI)–anchored protein of unknown function that is commonly targeted to induce experimental neutrophil depletion in mice. In the present study, we found that doses of anti-Ly6G Abs too low to produce sustained neutropenia remained capable of inhibiting experimental arthritis, leaving joint tissues free of infiltrating neutrophils. Thioglycollate-stimulated peritonitis was also attenuated. No alteration in neutrophil apoptosis was observed, implicating impaired recruitment. Indeed, Ly6G ligation abrogated neutrophil migration toward LTB4 and other chemoattractants in a transwell system. Exploring the basis for this blockade, we identified colocalization of Ly6G and β2-integrins by confocal microscopy and confirmed close association by both coimmunoprecipitation and fluorescence lifetime imaging microscopy. Anti-Ly6G Ab impaired surface expression of β2-integrins in LTB4-stimulated neutrophils and mimicked CD11a blockade in inhibiting both ICAM-1 binding and firm adhesion to activated endothelium under flow conditions. Correspondingly, migration of β2-integrin–deficient neutrophils was no longer inhibited by anti-Ly6G. These results demonstrate that experimental targeting of Ly6G has functional effects on the neutrophil population and identify a previously unappreciated role for Ly6G as a modulator of neutrophil migration to sites of inflammation via a β2-integrin–dependent mechanism.
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