Src family kinases mediate neutrophil adhesion to adherent platelets.
Polymorphonuclear leukocyte (PMN)-platelet interactions at sites of vascular damage contribute to local and systemic inflammation. We sought to determine the role of "outside-in" signaling by Src-family tyrosine kinases (SFKs) in the regulation of alphaMbeta2-integrin-dependent PMN recruitment by activated platelets under (patho)physiologic conditions. Activation-dependent epitopes in beta2 integrin were exposed at the contact sites between PMNs and platelets and were abolished by SFK inhibitors. PMNs from alphaMbeta2(-/-), hck(-/-)fgr(-/-), and hck(-/-)fgr(-/-)lyn(-/-) mice had an impaired capacity to adhere with activated platelets in suspension. Phosphorylation of Pyk2 accompanied PMN adhesion to platelets and was blocked by inhibition as well as by genetic deletion of alphaMbeta2 integrin and SFKs. A Pyk2 inhibitor reduced platelet-PMN adhesion, indicating that Pyk2 may be a downstream effector of SFKs. Analysis of PMN-platelet interactions under flow revealed that SFK signaling was required for alphaMbeta2-mediated shear-resistant adhesion of PMNs to adherent platelets, but was dispensable for P-selectin-PSGL-1-mediated recruitment and rolling. Finally, SFK activity was required to support PMN accumulation along adherent platelets at the site of vascular injury, in vivo. These results definitely establish a role for SFKs in PMN recruitment by activated platelets and suggest novel targets to disrupt the pathophysiologic consequences of platelet-leukocyte interactions in vascular disease.
Evangelista
Virgilio
V
Laboratory of Vascular Biology and Pharmacology, Consorzio Mario Negri Sud, Via Nazionale 8/A, 66030 Santa Maria Imbaro, Italy. evangelista@negrisud.it
Pamuklar
Zehra
Z
Piccoli
Antonio
A
Manarini
Stefano
S
Dell'elba
Giuseppe
G
Pecce
Romina
R
Martelli
Nicola
N
Federico
Lorenzo
L
Rojas
Mauricio
M
Berton
Giorgio
G
Lowell
Clifford A
CA
Totani
Licia
L
Smyth
Susan S
SS
D000818:Animals; D001792:Blood Platelets / Q000166:cytology* / Q000201:enzymology*; D039481:CD11b Antigen / Q000378:metabolism; D018821:CD18 Antigens / Q000378:metabolism; D002448:Cell Adhesion; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D006801:Humans; D016177:Macrophage-1 Antigen / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009504:Neutrophils / Q000166:cytology* / Q000201:enzymology*; D019007:P-Selectin / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D015539:Platelet Activation; D019061:src-Family Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D039481:CD11b Antigen; D018821:CD18 Antigens; D016177:Macrophage-1 Antigen; D019007:P-Selectin; D019000:Phosphotyrosine; D051418:Focal Adhesion Kinase 2; D019061:src-Family Kinases