Ly6G ligation blocks recruitment of neutrophils via a β2-integrin-dependent mechanism.
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 LTB(4) 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 LTB(4)-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.
Department of Medicine, Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Jun-Xia
JX
Wang
Angela M
AM
Bair
Sandra L
SL
King
Ruslan
R
Shnayder
Ya-Fang
YF
Huang
Chi-Chang
CC
Shieh
Roy J
RJ
Soberman
Robert C
RC
Fuhlbrigge
Peter A
PA
Nigrovic
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000950:Antigens, Ly / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects; D001168:Arthritis / Q000097:blood / Q000473:pathology / Q000517:prevention & control; D015415:Biomarkers / Q000378:metabolism; D018821:CD18 Antigens / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D007249:Inflammation / Q000473:pathology; D007596:Joints / Q000187:drug effects / Q000473:pathology; D007975:Leukotriene B4 / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018375:Neutrophil Activation / Q000187:drug effects; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D010537:Peritoneum / Q000187:drug effects / Q000473:pathology; D018102:Receptors, Leukotriene B4 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
D000906:Antibodies; D000950:Antigens, Ly; D015415:Biomarkers; D018821:CD18 Antigens; C480309:Ly6G antigen, mouse; D018102:Receptors, Leukotriene B4; D007975:Leukotriene B4; D002118:Calcium