ABSTRACT
Title
IL-17A increases ADP-induced platelet aggregation
Authors
F. Maione1, A. Parisi1, E. Liverani2, M. Perretti2, F. D’Acquisto2, N. Mascolo1, C. Cicala1.
1Dept. of Exp. Pharm., Univ. of Naples “Federico II”, Via Domenico Montesano 49, 81031, Naples, Italy.
2William Harvey Res. Inst., Queen Mary Univ. of London, Barts and The London School of Medicine and Dentistry, Charterhouse Square, London EC1M 6BQ, UK.
Abstract
Interleukin-17A (IL-17A) belongs to a new family of cytokines that have recently taken center stage in autoimmunity(D'Acquisto et al; 2010). This cytokine plays a pivotal role in the development of various models of chronic immune inflammatory diseases including collagen-induced arthritis and in mice affected by lupus-like diseases such as MRL/lpr or SNF1 (New Zealand Black x SWR F1) mice(Zhang et al; 2009). These experimental findings have been confirmed by clinical studies showing a positive correlation between plasma levels of IL-17A and the Systemic Lupus Erythematosus Disease(Chen et al; 2010) or the rheumatoid arthritis Disease (Leipe et al; 2010).One common feature of patients suffering from chronic autoimmune inflammatory diseases is the development of cardiovascular complications such as an increased risk of thromboembolism, an important causes of morbidity and mortality in these immune pathologies(Frostegard et al; 2005,Mameli et al; 2009).However, the molecular and cellular mechanisms underlying these effects are poorly understood.
In this study we tested the hypothesis that IL-17A, a key pro-inflammatory cytokine involved in the development of autoimmune diseases,might influence platelet responsiveness and activation; revealing another piece of evidence of the complex crosstalk between systemic inflammation and risk of cardiovascular pathologies in autoimmune diseases.
Using a standard light transmission Born aggregometerwe demonstrated that IL-17A, at concentrations known to exert an inflammatory response(Maione et al; 2009), increases ADP-induced platelet aggregation in both human and murine samples.To confirm the activating effects of IL-17A on platelets, we next measured membrane expression of CD62P and exposure of fibrinogen-binding sites by FACS. Consistent with results obtained on aggregation, platelets pre-treated with IL-17A displayed faster kinetics of CD62P upregulation and binding to fibrinogen compared to platelets stimulated with ADP alone. We next determined if platelets would express a functional IL-17A receptor. To this aim, we stained human platelets with IL-17 receptor A (IL-17RA) and their specific marker CD42. We demonstrated that a proportion of IL-17RA is stored intracellularly, available for externalization upon platelet activation. Moreover, the stimulation of this receptor was associated with a time-dependent increase in Erk-2 phosphorylation that represent the main signalling pathway for platelet function. Finally, the causal involvement of IL-17RA in the observed effects was obtained by testing the cytokine on platelets from IL-17RA-/- and wild-type mice. IL-17RA-/- platelets displayed no difference in response to ADP compared to wild-type control platelets. However, costimulation in presence of IL-17A showed an increase in aggregation in the latter but not the former genotype.
Together these results unveil a novel aspect of the inflammatory nature of IL-17A suggesting, at the same time, that IL-17A might sustain platelet adhesion and/or aggregation to inflamed vasculaturein autoimmune diseases.Congruently, we provide first evidence that therapies targeting IL-17A in autoimmune diseases might provide an extra beneficial therapeutic effect by limiting the risk of cardiovascular diseases associated with thromboembolic events.
D'Acquisto et al. (2010). Biochem Pharmacol. 79, 525-534.
Zhang et al. (2009). J Immunol. 183, 3160-3169.
Chen et al. (2010). J Clin Immunol. 30, 221-225.
Leipe et al. (2010). Arthritis Rheum. 62, 2876-2885.
Frostegard et al. (2005). Arterioscler Thromb Vasc Biol. 25, 1776-1785.
Mameli et al. (2009). Clin Exp Rheumatol. 27, 846-855.
Maione et al. (2009). Biochem Pharmacol. 77, 878-88.
In this study we tested the hypothesis that IL-17A, a key pro-inflammatory cytokine involved in the development of autoimmune diseases,might influence platelet responsiveness and activation; revealing another piece of evidence of the complex crosstalk between systemic inflammation and risk of cardiovascular pathologies in autoimmune diseases.
Using a standard light transmission Born aggregometerwe demonstrated that IL-17A, at concentrations known to exert an inflammatory response(Maione et al; 2009), increases ADP-induced platelet aggregation in both human and murine samples.To confirm the activating effects of IL-17A on platelets, we next measured membrane expression of CD62P and exposure of fibrinogen-binding sites by FACS. Consistent with results obtained on aggregation, platelets pre-treated with IL-17A displayed faster kinetics of CD62P upregulation and binding to fibrinogen compared to platelets stimulated with ADP alone. We next determined if platelets would express a functional IL-17A receptor. To this aim, we stained human platelets with IL-17 receptor A (IL-17RA) and their specific marker CD42. We demonstrated that a proportion of IL-17RA is stored intracellularly, available for externalization upon platelet activation. Moreover, the stimulation of this receptor was associated with a time-dependent increase in Erk-2 phosphorylation that represent the main signalling pathway for platelet function. Finally, the causal involvement of IL-17RA in the observed effects was obtained by testing the cytokine on platelets from IL-17RA-/- and wild-type mice. IL-17RA-/- platelets displayed no difference in response to ADP compared to wild-type control platelets. However, costimulation in presence of IL-17A showed an increase in aggregation in the latter but not the former genotype.
Together these results unveil a novel aspect of the inflammatory nature of IL-17A suggesting, at the same time, that IL-17A might sustain platelet adhesion and/or aggregation to inflamed vasculaturein autoimmune diseases.Congruently, we provide first evidence that therapies targeting IL-17A in autoimmune diseases might provide an extra beneficial therapeutic effect by limiting the risk of cardiovascular diseases associated with thromboembolic events.
D'Acquisto et al. (2010). Biochem Pharmacol. 79, 525-534.
Zhang et al. (2009). J Immunol. 183, 3160-3169.
Chen et al. (2010). J Clin Immunol. 30, 221-225.
Leipe et al. (2010). Arthritis Rheum. 62, 2876-2885.
Frostegard et al. (2005). Arterioscler Thromb Vasc Biol. 25, 1776-1785.
Mameli et al. (2009). Clin Exp Rheumatol. 27, 846-855.
Maione et al. (2009). Biochem Pharmacol. 77, 878-88.