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Efficient inhibition of collagen-induced platelet activation and adhesion by LAIR-2, a soluble Ig-like receptor family member.

Lenting PJ, Westerlaken GH, Denis CV, Akkerman JW, Meyaard L - PLoS ONE (2010)

Bottom Line: LAIR-2/Fc but not LAIR-1/Fc inhibited collagen-induced platelet aggregation.Additional experiments revealed that LAIR-2/Fc leaves interactions between collagen and alpha2beta1 unaffected, but efficiently prevents binding of collagen to Glycoprotein VI and von Willebrand factor.Thus, LAIR-2/Fc has the capacity to interfere with platelet-collagen interactions mediated by Glycoprotein VI and the VWF/Glycoprotein Ib axis.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U770 & Univ Paris-Sud, Le Kremlin-Bicêtre, France.

ABSTRACT
LAIR-1 (Leukocyte Associated Ig-like Receptor -1) is a collagen receptor that functions as an inhibitory receptor on immune cells. It has a soluble family member, LAIR-2, that also binds collagen and can interfere with LAIR-1/collagen interactions. Collagen is a main initiator for platelet adhesion and aggregation. Here, we explored the potential of soluble LAIR proteins to inhibit thrombus formation in vitro. LAIR-2/Fc but not LAIR-1/Fc inhibited collagen-induced platelet aggregation. In addition, LAIR-2/Fc also interfered with platelet adhesion to collagen at low shear rate (300 s(-1); IC(50) = 18 microg/ml) and high shear rate (1500 s(-1); IC(50) = 30 microg/ml). Additional experiments revealed that LAIR-2/Fc leaves interactions between collagen and alpha2beta1 unaffected, but efficiently prevents binding of collagen to Glycoprotein VI and von Willebrand factor. Thus, LAIR-2/Fc has the capacity to interfere with platelet-collagen interactions mediated by Glycoprotein VI and the VWF/Glycoprotein Ib axis.

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LAIR-2/Fc interferes with VWF binding to collagen.Microtiter wells were coated with 50 µg/ml collagen I (panel A) or collagen III (panel B) and subsequently incubated with 0.1 µg/ml purified plasma-derived VWF in the presence of increasing concentrations of LAIR-1/Fc (open circles), LAIR-2/Fc (closed circles) or SIRL-1/Fc (squares). VWF binding was detected with horseradish-conjugated polyclonal anti-human VWF antibodies and 3-3′-5-5′-tetramethylbenzidine. Data are representative of 3 independent experiments.
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pone-0012174-g005: LAIR-2/Fc interferes with VWF binding to collagen.Microtiter wells were coated with 50 µg/ml collagen I (panel A) or collagen III (panel B) and subsequently incubated with 0.1 µg/ml purified plasma-derived VWF in the presence of increasing concentrations of LAIR-1/Fc (open circles), LAIR-2/Fc (closed circles) or SIRL-1/Fc (squares). VWF binding was detected with horseradish-conjugated polyclonal anti-human VWF antibodies and 3-3′-5-5′-tetramethylbenzidine. Data are representative of 3 independent experiments.

Mentions: When added to PRP, LAIR-2/Fc but not LAIR-1/Fc was able to interfere with collagen-induced platelet aggregation (Fig. 2). LAIR-2/Fc mediated inhibition was found to be dose-dependent and specific, given that no inhibition was observed upon TRAP-induced platelet aggregation (Fig. 2). A LAIR-2/Fc specific inhibition of platelet-collagen interactions was also observed in in vitro perfusion experiments. The addition of LAIR-2/Fc to anticoagulated whole blood resulted in a dramatic decrease in the deposition of platelets when perfused over a collagen surface, both at low (300 s−1) and high (1500 s−1) shear rates (Fig. 3). Since different receptors dominate the interactions between platelets and collagen at low and high shear rates, our findings indicate that LAIR-2/Fc is able to interfere with the action of more than one collagen-receptor. Indeed, whereas LAIR-2/Fc was unable to interfere with the interaction between collagen and α2β1, LAIR-2/Fc but not LAIR-1/Fc inhibited binding of collagen to GpVI-expressing cells as well as binding of VWF to collagen (Figs. 4 and 5). These data are in agreement with the perfusion data, in that GpVI is important in the adhesion of platelets to collagen under low shear rate conditions, whereas VWF is pertinent to the adhesion of platelets to collagen under high shear rate conditions.


Efficient inhibition of collagen-induced platelet activation and adhesion by LAIR-2, a soluble Ig-like receptor family member.

Lenting PJ, Westerlaken GH, Denis CV, Akkerman JW, Meyaard L - PLoS ONE (2010)

LAIR-2/Fc interferes with VWF binding to collagen.Microtiter wells were coated with 50 µg/ml collagen I (panel A) or collagen III (panel B) and subsequently incubated with 0.1 µg/ml purified plasma-derived VWF in the presence of increasing concentrations of LAIR-1/Fc (open circles), LAIR-2/Fc (closed circles) or SIRL-1/Fc (squares). VWF binding was detected with horseradish-conjugated polyclonal anti-human VWF antibodies and 3-3′-5-5′-tetramethylbenzidine. Data are representative of 3 independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2921339&req=5

pone-0012174-g005: LAIR-2/Fc interferes with VWF binding to collagen.Microtiter wells were coated with 50 µg/ml collagen I (panel A) or collagen III (panel B) and subsequently incubated with 0.1 µg/ml purified plasma-derived VWF in the presence of increasing concentrations of LAIR-1/Fc (open circles), LAIR-2/Fc (closed circles) or SIRL-1/Fc (squares). VWF binding was detected with horseradish-conjugated polyclonal anti-human VWF antibodies and 3-3′-5-5′-tetramethylbenzidine. Data are representative of 3 independent experiments.
Mentions: When added to PRP, LAIR-2/Fc but not LAIR-1/Fc was able to interfere with collagen-induced platelet aggregation (Fig. 2). LAIR-2/Fc mediated inhibition was found to be dose-dependent and specific, given that no inhibition was observed upon TRAP-induced platelet aggregation (Fig. 2). A LAIR-2/Fc specific inhibition of platelet-collagen interactions was also observed in in vitro perfusion experiments. The addition of LAIR-2/Fc to anticoagulated whole blood resulted in a dramatic decrease in the deposition of platelets when perfused over a collagen surface, both at low (300 s−1) and high (1500 s−1) shear rates (Fig. 3). Since different receptors dominate the interactions between platelets and collagen at low and high shear rates, our findings indicate that LAIR-2/Fc is able to interfere with the action of more than one collagen-receptor. Indeed, whereas LAIR-2/Fc was unable to interfere with the interaction between collagen and α2β1, LAIR-2/Fc but not LAIR-1/Fc inhibited binding of collagen to GpVI-expressing cells as well as binding of VWF to collagen (Figs. 4 and 5). These data are in agreement with the perfusion data, in that GpVI is important in the adhesion of platelets to collagen under low shear rate conditions, whereas VWF is pertinent to the adhesion of platelets to collagen under high shear rate conditions.

Bottom Line: LAIR-2/Fc but not LAIR-1/Fc inhibited collagen-induced platelet aggregation.Additional experiments revealed that LAIR-2/Fc leaves interactions between collagen and alpha2beta1 unaffected, but efficiently prevents binding of collagen to Glycoprotein VI and von Willebrand factor.Thus, LAIR-2/Fc has the capacity to interfere with platelet-collagen interactions mediated by Glycoprotein VI and the VWF/Glycoprotein Ib axis.

View Article: PubMed Central - PubMed

Affiliation: Institut National de la Santé et de la Recherche Médicale (INSERM) U770 & Univ Paris-Sud, Le Kremlin-Bicêtre, France.

ABSTRACT
LAIR-1 (Leukocyte Associated Ig-like Receptor -1) is a collagen receptor that functions as an inhibitory receptor on immune cells. It has a soluble family member, LAIR-2, that also binds collagen and can interfere with LAIR-1/collagen interactions. Collagen is a main initiator for platelet adhesion and aggregation. Here, we explored the potential of soluble LAIR proteins to inhibit thrombus formation in vitro. LAIR-2/Fc but not LAIR-1/Fc inhibited collagen-induced platelet aggregation. In addition, LAIR-2/Fc also interfered with platelet adhesion to collagen at low shear rate (300 s(-1); IC(50) = 18 microg/ml) and high shear rate (1500 s(-1); IC(50) = 30 microg/ml). Additional experiments revealed that LAIR-2/Fc leaves interactions between collagen and alpha2beta1 unaffected, but efficiently prevents binding of collagen to Glycoprotein VI and von Willebrand factor. Thus, LAIR-2/Fc has the capacity to interfere with platelet-collagen interactions mediated by Glycoprotein VI and the VWF/Glycoprotein Ib axis.

Show MeSH
Related in: MedlinePlus