Supplementary Material for: Increased Platelet-Monocyte Interaction in Stable COPD in the Absence of Platelet Hyper-Reactivity

Background: Chronic obstructive pulmonary disease (COPD) is well known for its cardiovascular co-morbidities. Increased platelet-monocyte interaction is found in COPD and may reflect altered platelet function and a potential role for anti-platelet therapy. Objectives: The objectives were to investigate platelet-monocyte interaction, platelet activation and reactivity and plasmatic coagulation in stable COPD. Methods: Platelet-monocyte interaction and platelet activation were determined by flow cytometry in 30 stable COPD patients and 25 controls. Platelet activation was measured by binding of fibrinogen to the activated fibrinogen receptor and platelet P-selectin expression at baseline and after platelet stimulation with platelet agonists. Plasmatic coagulation was measured by D-dimer and thrombin generation. Results: Platelet-monocyte interaction was increased in stable COPD (median fluorescence intensity of platelet CD61 was 19.8 [IQR 14.0-33.2] vs. 10.0 [IQR 8.7-16.7], p = 0.002). In contrast, platelet activation and reactivity, reflected by fibrinogen binding and P-selectin expression, were the same in both groups. Plasma P-selectin and interleukin-6 were increased in COPD (p = 0.01 and p = 0.02, respectively), whereas soluble fibrinogen, D-dimer and thrombin generation were similar. Conclusions: Increased platelet-monocyte interaction was found in the absence of platelet hyper-reactivity and activation of plasmatic coagulation in stable COPD. Future clinical evaluation of the effects of different anti-platelet drugs in COPD is warranted, as anti-platelet therapy may interfere with platelet-monocyte interaction.