[Thrombocytes express functional cytokine receptors in patients with Crohn disease and ulcerative colitis].

Inflammatory bowel disease (IBD) is characterized by T-cell activation and mucosal influx of inflammatory cells partly mediated by increased local release of cytokines and chemokines. Increased levels of activated platelets are reported in IBD. Activated platelets induce endothelial cells in vitro to secrete several cytokines and growth factors and to express adhesion molecules. This study investigates the expression of interleukin-1 (IL-1), IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors on circulating platelets from patients with IBD and healthy controls and assesses the in vitro effect of various concentrations of IL-1 beta, IL-8 and GM-CSF on platelet activation in healthy controls. Flow cytometry was performed to quantify the percentage of platelets binding phycoerythrin (PE) labeled recombinant human IL-1 beta, IL-8 and GM-CSF. Platelet activation was assessed using fluorochrome labeled anti-GMP-140, an activation-dependent antigen. Results are expressed as percentage cytokine receptor expressing platelets (median and interquartile range IQR). Platelets from patients with IBD expressed significantly more cytokine receptors compared to healthy controls: IL-1R [8.7% (5.5-18.2) vs 3.1% (2.4-4.8), p < 0.05], IL-8R [22.5% (18.1-27.9) vs 8% (4.5-9.2), p < 0.001)], GM-CSFR [25.9% (16.1-39.2) vs 3.9% (2.7-3.9), p < 0.001]. The percentage of activated platelets was significantly increased after in vitro stimulation with IL-1 beta, IL-8 and GM-CSF. We conclude that cytokines and chemokines modulate platelet activation through specific, functional receptors which are upregulated in IBD.