Rhinovirus infection induces procoagulant changes in parallel with eosinophilic airway inflammation

Abstract

Background: Asthma exacerbations are frequently triggered by rhinovirus infections. Asthma itself is associated with activated coagulation and increased risk of venous thromboembolism1 and also respiratory viruses may activate hemostasis. Vice versa, a prothrombotic state in the lung can also induce or aggravate pulmonary inflammation. Aim: To determine whether rhinovirus infection and asthmatic airway inflammation act on the local and systemic hemostatic balance in patients in vivo. Methods: In a two-groups parallel study design 28 volunteers (14 patients with mild asthma (seven females, 19-26 years) and 14 healthy controls (13 females, 19-31 years)) were experimentalliy infected with low-dose rhinovirus serotype 16 (RV16). Patients with mild asthma were stable after discontinuation of their asthma medication 2 weeks prior to RV16 inoculation. Venous plasma and bronchoalveolar lavage fluid (BAL fluid) were obtained 1 day before and 6 days after rhinovirus challange to evaluate several key markers of coagulation activation in plasma and BAL fluid, as well as the coagulant features of microparticles in BAL fluid. Thrombin-antithrombin complexes (TATc), von Willebrand factor (vWF), Plasmin-antiplasmin complexes (PAP), Plasminogen activator inhibitor type-1 (PAI-1), and eosinophil cationic protein (ECP) in plasma and BAL fluid were measured by immunoassay. Endogenous thrombin potential (ETP) was analysed using the Calibrated Automated Thrombogram® and tissue factor bearing microparticles, measured by fibrin generation test (FGT). Eosinophils were counted on cytospin preparations. Comparisons and correlations were performed by non-parametric testing. Results: In plasma, RV16 challange resulted in increased PAI-1 levels in patients with asthma after viral infection (26.5 ng/mL in patients with astma vs. 10.0 ng/mL in healthy controls, P = 0.01) and decreased PAP levels (318 vs. 534 ng/mL resp., P = 0.04). Changes in PAI-1 levels were significantly elevated in asthma than in control subjects (3.0 vs. -3.5 ng/L respectively, P = 0.024), while changes in TATc, D-dimer, vWF and ETP did not differ between both groups. In BAL fluid, the FGT shortened after viral infection in asthma (t = -1 day: 689s vs. t = 6 days: 516 s; P = 0.011), but not in healthy controls (t = -1 day: 695s vs. t = 6 days: 672 s; P = 0.79). The changes in TATc and PAP did not differ between both groups and vWF, D-dimer and PAI-1 were below the detection limit. Both FGT and TATc in BAL fluid correlated (Spearman) with eosinophil counts and ECP (r = -0.583 and -0.682 resp. for FGT and r = 0.535 and 0.619 resp. for TATc, all P <0.01) Conclusion: Experimental rhinovirus infection induces procoagulant changes in patients with asthma systemically through PAI-1 and in the airways by TF-bearing microparticles. This did not lead to changes in global assays of hemostasis, probably due to the relatively mild infection in patients with mild to intermittent asthma. In the airways, microparticle-associated procoagulant changes are associated with eosinophilic inflammation, suggesting that virus infection and eosinophilic inflammation both act on the hemostatic (dis)balance during asthma exacerbations