Activated factor XI and tissue factor in chronic obstructive pulmonary disease: links with inflammation and thrombin generation

Abstract

Introduction: Increased cardiovascular mortality and risk of venous thromboembolism are serious extra-pulmonary complications of chronic obstructive pulmonary disease (COPD). Previously, circulating active tissue factor (TF) and factor XIa (FXIa) have been reported to be associated with acute coronary syndromes.

Objective: To measure plasma FXIa and active TF, prothrombin fragment 1.2 (F1.2), and markers of systemic inflammation (C-reactive protein [CRP], interleukin-6 [IL-6], tumor necrosis factor α [TNFα] and matrix metalloproteinase 9 [MMP-9]) in 60 patients with documented stable COPD free of previous thromboembolic events.

Methods: In-house clotting assays using inhibitory monoclonal antibodies against FXIa and TF.

Results: FXIa was detected in 9 (15%) and TF activity in 7 (11.7%) COPD patients. Subjects positive for FXIa and/or TF (n=10; 16.7%) had higher F1.2 (median [interquartile range], 398 [216] vs 192 [42] pM, p<0.000001), fibrinogen (5.58 [2.01] vs 3.97 [2.47] g/L, p=0.0007), CRP (14.75 [1.20] vs 1.88 [2.95] mg/L, p<0.000001), IL-6 (8.14 [4.74] vs 2.45 [2.24] pg/mL, p=0.00002), and right ventricular systolic pressure (47 [15] vs 38 [12] mmHg, p=0.023), and lower vital capacity (66 [15] vs 80 [17] % predicted, p=0.04) than COPD patients without detectable FXIa and TF. COPD severity was not associated with the presence of circulating FXIa and active TF.

Conclusions: This is the first study to show that active FXIa and TF are present in stable COPD patients, who exhibit enhanced systemic inflammation and thrombin generation. Our findings suggest a new prothrombotic mechanism which might contribute to elevated risk of thromboembolic complications in COPD.

Fig. 1

Prothrombin fragment 1.2 (F1.2; A), fibrinogen (B), C-reactive protein (CRP; C), interleukin 6 (IL-6; D), matrix metalloproteinase 9 (MMP-9; E), and FXIa (F) in COPD patients with detectable FXIa and/or TF activity (FXIa/TF+; n=10) as compared to patients without detectable FXIa and/or TF activity (FXIa-TF-; n=50). Medians and interquartile ranges are shown.